ORF Sequence: NC_006576 [GENIUS II[Archive

Lifescience Database Archive (English)

Full Text Available ferase [Synechococcus elongatus PCC 6301] MSDYSDRSDFSERQDRSSDDRPNFRRFDRDRPSEGRRLEGRSEGGYRGRDDRGGSGGYRQNRDDRGGFRGRDDRG...GYRGGDRDRPSEGRRFEGRSEGGYRGRDDRGGSGGYRQNRDDRGGFRGRDDRGGYRGGDRDRPSEGRRFEGRSEGGFRGRDDRGGSGGYRGRDDRGGFRGRDDRGGFRGRDDRG...SSGSYRGRDDRGGFRGRDDRRDDRDNFRPSRDRELNREVNTSPAGDQEATDHELIYGRHAVLAALQ

Physiological and biochemical responses of Synechococcus sp. PCC7942 to Irgarol 1051 and diuron.

Science.gov (United States)

Deng, Xiangyuan; Gao, Kun; Sun, Junlong

2012-10-15

Cyanobacteria are prokaryotic algae found in oceans and freshwaters worldwide. These organisms are important primary producers in aquatic ecosystems because they can provide essential food for grazers and herbivores. In this study, the physiological and biochemical responses of the freshwater cyanobacterium Synechococcus sp. PCC7942 to two organic booster biocides Irgarol 1051 and diuron were compared and evaluated using 96 h growth tests in a batch-culture system. The 96 h median effective concentrations (EC(50)) were 0.019 and 0.097 μmol L(-1) for Irgarol 1051 and diuron, respectively, which indicate that Irgarol 1051 is about 5 times more toxic than diuron to cyanobacteria. Moreover, remarkable physiological and biochemical responses occurred in the Irgarol 1051 and diuron treatments. Irgarol 1051 and diuron stimulated cyanobacterial growth, increased the soluble protein content, and enhanced the catalase (CAT) activity at low concentrations, but inhibited them at high concentrations. However, the malondialdehyde (MDA) and polysaccharide content of the cyanobacteria were only significantly affected by Irgarol 1051. These observations suggest that Irgarol 1051 and diuron are toxic to Synechococcus sp. PCC7942, and their use should be restricted in maritime industries. Copyright © 2012 Elsevier B.V. All rights reserved.

MapA, an iron-regulated, cytoplasmic membrane protein in the cyanobacterium Synechococcus sp. strain PCC7942.

Science.gov (United States)

Webb, R; Troyan, T; Sherman, D; Sherman, L A

1994-08-01

Growth of Synechococcus sp. strain PCC 7942 in iron-deficient media leads to the accumulation of an approximately 34-kDa protein. The gene encoding this protein, mapA (membrane-associated protein A), has been cloned and sequenced (GenBank accession number, L01621). The mapA transcript is not detectable in normally grown cultures but is stably accumulated by cells grown in iron-deficient media. However, the promoter sequence for this gene does not resemble other bacterial iron-regulated promoters described to date. The carboxyl-terminal region of the derived amino acid sequence of MapA resembles bacterial proteins involved in iron acquisition, whereas the amino-terminal end of MapA has a high degree of amino acid identity with the abundant, chloroplast envelope protein E37. An approach employing improved cellular fractionation techniques as well as electron microscopy and immunocytochemistry was essential in localizing MapA protein to the cytoplasmic membrane of Synechococcus sp. strain PCC 7942. When these cells were grown under iron-deficient conditions, a significant fraction of MapA could also be localized to the thylakoid membranes.

ORF Alignment: NC_006576 [GENIUS II[Archive

Lifescience Database Archive (English)

Full Text Available ECEASDVKSLLEALEQSFPGIKARLCDEQGQLRRFLNVYVN 62 ... ITVLIPTPLQKFTNNQASLECEASDVKS...LLEALEQSFPGIKARLCDEQGQLRRFLNVYVN Sbjct: 1 ... ITVLIPTPLQKFTNNQASLECEASDVKSLLEALEQSFPGIKARLCDEQGQLRRFLNVYVN 60 ... ...subunit ... [Synechococcus elongatus PCC 7942] ... Length = 89 ... Query: 3 ... ITVLIPTPLQKFTNNQASL

Engineering Limonene and Bisabolene Production in Wild Type and a Glycogen-Deficient Mutant of Synechococcus sp. PCC 7002

Energy Technology Data Exchange (ETDEWEB)

Davies, Fiona K., E-mail: fdavies@mines.edu [Department of Chemistry and Geochemistry, Colorado School of Mines, Golden, CO (United States); Work, Victoria H. [Civil and Environmental Engineering Division, Colorado School of Mines, Golden, CO (United States); Beliaev, Alexander S. [Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA (United States); Posewitz, Matthew C. [Department of Chemistry and Geochemistry, Colorado School of Mines, Golden, CO (United States)

2014-06-19

The plant terpenoids limonene (C{sub 10}H{sub 16}) and α-bisabolene (C{sub 15}H{sub 24}) are hydrocarbon precursors to a range of industrially relevant chemicals. High-titer microbial synthesis of limonene and α-bisabolene could pave the way for advances in in vivo engineering of tailor-made hydrocarbons, and production at commercial scale. We have engineered the fast-growing unicellular euryhaline cyanobacterium Synechococcus sp. PCC 7002 to produce yields of 4 mg L{sup −1} limonene and 0.6 mg L{sup −1} α-bisabolene through heterologous expression of the Mentha spicatal-limonene synthase or the Abies grandis (E)-α-bisabolene synthase genes, respectively. Titers were significantly higher when a dodecane overlay was applied during culturing, suggesting either that dodecane traps large quantities of volatile limonene or α-bisabolene that would otherwise be lost to evaporation, and/or that continuous product removal in dodecane alleviates product feedback inhibition to promote higher rates of synthesis. We also investigate limonene and bisabolene production in the ΔglgC genetic background, where carbon partitioning is redirected at the expense of glycogen biosynthesis. The Synechococcus sp. PCC 7002 ΔglgC mutant excreted a suite of overflow metabolites (α-ketoisocaproate, pyruvate, α-ketoglutarate, succinate, and acetate) during nitrogen-deprivation, and also at the onset of stationary growth in nutrient-replete media. None of the excreted metabolites, however, appeared to be effectively utilized for terpenoid metabolism. Interestingly, we observed a 1.6- to 2.5-fold increase in the extracellular concentration of most excreted organic acids when the ΔglgC mutant was conferred with the ability to produce limonene. Overall, Synechococcus sp. PCC 7002 provides a highly promising platform for terpenoid biosynthetic and metabolic engineering efforts.

Engineering limonene and bisabolene production in wild type and a glycogen-deficient mutant of Synechococcus sp. PCC 7002

Energy Technology Data Exchange (ETDEWEB)

Davies, Fiona K.; Work, Victoria H.; Beliaev, Alex S.; Posewitz, Matthew C.

2014-06-19

The plant terpenoids limonene (C10H16) and α-bisabolene (C15H24) are hydrocarbon precursors to a range of industrially-relevant chemicals. High-titer microbial synthesis of limonene and α- bisabolene could pave the way for advances in in vivo engineering of tailor-made hydrocarbons, and production at commercial scale. We have engineered the fast-growing unicellular euryhaline cyanobacterium Synechococcus sp. PCC 7002 to produce yields of 4 mg L-1 limonene and 0.6 mg L-1 α-bisabolene through heterologous expression of the Mentha spicata L-limonene synthase or the Abies grandis (E)-α-bisabolene synthase genes, respectively. Titers were significantly higher when a dodecane overlay was applied during culturing, suggesting either that dodecane traps large quantities of volatile limonene and α-bisabolene that would otherwise be lost to evaporation, and/or that continuous product removal in dodecane alleviates product feedback inhibition to promote higher rates of synthesis. We also investigate limonene and bisabolene production in the ΔglgC genetic background, where carbon partitioning is redirected at the expense of glycogen biosynthesis. The Synechococcus sp. PCC 7002 ΔglgC mutant excreted a suite of overflow metabolites (α-ketoisocaproate, pyruvate, α-ketoglutarate, succinate and acetate) during nitrogen deprivation, and also at the onset of stationary growth in nutrient-replete media. None of the excreted metabolites, however, appeared to be effectively utilized for terpenoid metabolism. Interestingly, we observed a 1.6 to 2.5-fold increase in the extracellular concentration of most excreted organic acids when the ΔglgC mutant was conferred with the ability to produce limonene. Overall, Synechococcus sp. PCC 7002 provides a highly promising platform for terpenoid biosynthetic and metabolic engineering efforts.

Engineering Limonene and Bisabolene Production in Wild Type and a Glycogen-Deficient Mutant of Synechococcus sp. PCC 7002.

Science.gov (United States)

Davies, Fiona K; Work, Victoria H; Beliaev, Alexander S; Posewitz, Matthew C

2014-01-01

The plant terpenoids limonene (C10H16) and α-bisabolene (C15H24) are hydrocarbon precursors to a range of industrially relevant chemicals. High-titer microbial synthesis of limonene and α-bisabolene could pave the way for advances in in vivo engineering of tailor-made hydrocarbons, and production at commercial scale. We have engineered the fast-growing unicellular euryhaline cyanobacterium Synechococcus sp. PCC 7002 to produce yields of 4 mg L(-1) limonene and 0.6 mg L(-1) α-bisabolene through heterologous expression of the Mentha spicatal-limonene synthase or the Abies grandis (E)-α-bisabolene synthase genes, respectively. Titers were significantly higher when a dodecane overlay was applied during culturing, suggesting either that dodecane traps large quantities of volatile limonene or α-bisabolene that would otherwise be lost to evaporation, and/or that continuous product removal in dodecane alleviates product feedback inhibition to promote higher rates of synthesis. We also investigate limonene and bisabolene production in the ΔglgC genetic background, where carbon partitioning is redirected at the expense of glycogen biosynthesis. The Synechococcus sp. PCC 7002 ΔglgC mutant excreted a suite of overflow metabolites (α-ketoisocaproate, pyruvate, α-ketoglutarate, succinate, and acetate) during nitrogen-deprivation, and also at the onset of stationary growth in nutrient-replete media. None of the excreted metabolites, however, appeared to be effectively utilized for terpenoid metabolism. Interestingly, we observed a 1.6- to 2.5-fold increase in the extracellular concentration of most excreted organic acids when the ΔglgC mutant was conferred with the ability to produce limonene. Overall, Synechococcus sp. PCC 7002 provides a highly promising platform for terpenoid biosynthetic and metabolic engineering efforts.

Engineering Limonene and Bisabolene Production in Wild Type and a Glycogen-Deficient Mutant of Synechococcus sp. PCC 7002

International Nuclear Information System (INIS)

Davies, Fiona K.; Work, Victoria H.; Beliaev, Alexander S.; Posewitz, Matthew C.

2014-01-01

The plant terpenoids limonene (C 10 H 16 ) and α-bisabolene (C 15 H 24 ) are hydrocarbon precursors to a range of industrially relevant chemicals. High-titer microbial synthesis of limonene and α-bisabolene could pave the way for advances in in vivo engineering of tailor-made hydrocarbons, and production at commercial scale. We have engineered the fast-growing unicellular euryhaline cyanobacterium Synechococcus sp. PCC 7002 to produce yields of 4 mg L −1 limonene and 0.6 mg L −1 α-bisabolene through heterologous expression of the Mentha spicatal-limonene synthase or the Abies grandis (E)-α-bisabolene synthase genes, respectively. Titers were significantly higher when a dodecane overlay was applied during culturing, suggesting either that dodecane traps large quantities of volatile limonene or α-bisabolene that would otherwise be lost to evaporation, and/or that continuous product removal in dodecane alleviates product feedback inhibition to promote higher rates of synthesis. We also investigate limonene and bisabolene production in the ΔglgC genetic background, where carbon partitioning is redirected at the expense of glycogen biosynthesis. The Synechococcus sp. PCC 7002 ΔglgC mutant excreted a suite of overflow metabolites (α-ketoisocaproate, pyruvate, α-ketoglutarate, succinate, and acetate) during nitrogen-deprivation, and also at the onset of stationary growth in nutrient-replete media. None of the excreted metabolites, however, appeared to be effectively utilized for terpenoid metabolism. Interestingly, we observed a 1.6- to 2.5-fold increase in the extracellular concentration of most excreted organic acids when the ΔglgC mutant was conferred with the ability to produce limonene. Overall, Synechococcus sp. PCC 7002 provides a highly promising platform for terpenoid biosynthetic and metabolic engineering efforts.

Alterations in the antibacterial potential of Synechococcus spp. PCC7942 under the influence of UV-B radiations on skin pathogens

Directory of Open Access Journals (Sweden)

Nida Fatima

2017-11-01

Full Text Available Marine organisms are seen as a source of novel drugs and the discovery of new pharmaceutical is increasingly in demand. Cyanobacteria are regarded as a potential target for this as antibacterial, antiviral, antifungal, algicide and cytotoxic activities have been reported in these organisms. They have been identified as a new and rich source of bioactive compounds belonging to diversified groups. Radiation in the UV-B range interferes with various metabolic reactions by generating free radicals and active oxygen species. These deleterious compounds are inactivated by antioxidants. Among them are the carotenoids and phycocyanin which protect against photodynamic action in different ways. Stress plays an important role in the production of bioactive metabolites from organisms. Synechococcus spp. PCC7942 was studied for antibacterial activity against various pathogenic bacteria resistant to a number of available antibiotics after being exposed to UV-B radiation. The antibacterial activity of Synechococcus spp. PCC7942 was studied on five potent skin pathogens. The highest antibacterial activity was seen the methanol extracts of 24 h UV-B exposed cultures of Synechococcus spp. PCC7942. It can be concluded that there was moderate antibacterial activity. Results showed stress, solvent and dose-dependent activity. This antibacterial activity might be due to the enhanced synthesis of carotenoids and phycocyanin under UV-B stress. The purpose of the present study was to relate the inhibitory effects of the cyanobacterial compounds specifically on skin pathogens with exposure to UV-B radiation as UV protecting compounds are already reported in these organisms.

Network analysis of transcriptomics expands regulatory landscapes in Synechococcus sp. PCC 7002

Energy Technology Data Exchange (ETDEWEB)

McClure, Ryan S.; Overall, Christopher C.; McDermott, Jason E.; Hill, Eric A.; Markillie, Lye Meng; McCue, Lee Ann; Taylor, Ronald C.; Ludwig, Marcus; Bryant, Donald A.; Beliaev, Alexander S.

2016-08-27

Cyanobacterial regulation of gene expression must contend with a genome organization that lacks apparent functional context, as the majority of cellular processes and metabolic pathways are encoded by genes found at disparate locations across the genome. In addition, the fact that coordinated regulation of cyanobacterial cellular machinery takes place with significantly fewer transcription factors, compared to other Eubacteria, suggests the involvement of post-transcriptional mechanisms and regulatory adaptations which are not fully understood. Global transcript abundance from model cyanobacterium Synechococcus sp. PCC 7002 grown under 42 different conditions was analyzed using context-likelihood of relatedness. The resulting 903-gene network, which was organized into 11 modules, not only allowed classification of cyanobacterial responses to specific environmental variables but provided insight into the transcriptional network topology and led to the expansion of predicted regulons. When used in conjunction with genome sequence, the global transcript abundance allowed identification of putative post-transcriptional changes in expression as well as novel potential targets of both DNA binding proteins and asRNA regulators. The results offer a new perspective into the multi-level regulation that governs cellular adaptations of fast-growing physiologically robust cyanobacterium Synechococcus sp. PCC 7002 to changing environmental variables. It also extends a methodological knowledge-based framework for studying multi-scale regulatory mechanisms that operate in cyanobacteria. Finally, it provides valuable context for integrating systems-level data to enhance evidence-driven genomic annotation, especially in organisms where traditional context analyses cannot be implemented due to lack of operon-based functional organization.

comparative transcriptomics between Synechococcus PCC 7942 and Synechocystis PCC 6803 provide insights into mechanisms of adaptation to stress.

Energy Technology Data Exchange (ETDEWEB)

Konstantinos, Billis [USDOE Joint Genome Institute (JGI), Walnut Creek, CA (United States); European Bioinformatics Inst., Hinxton, Cambridge (United Kingdom). European Molecular Biology Lab.; Aristotle Univ., Thessaloniki (Greece). Dept. of Genetics; Billini, Maria [USDOE Joint Genome Institute (JGI), Walnut Creek, CA (United States); Max Planck Inst. for Terrestrial Microbiology, Marburg (Germany); Tripp, Harry J. [USDOE Joint Genome Institute (JGI), Walnut Creek, CA (United States); Kyrpides, Nikos C. [USDOE Joint Genome Institute (JGI), Walnut Creek, CA (United States); Mavrommatis, Konstantinos [USDOE Joint Genome Institute (JGI), Walnut Creek, CA (United States); Celgene Corp, San Francisco, CA (United States)

2014-03-21

Background: Synechococcus sp. PCC 7942 and Synechocystis sp. PCC 6803 are model cyanobacteria from which the metabolism and adaptive responses of other cyanobacteria are inferred. Here we report the gene expression response of these two strains to a variety of nutrient and environmental stresses of varying duration, using transcriptomics. Our data comprise both stranded and 5? enriched libraries in order to elucidate many aspects of the transcriptome. Results: Both organisms were exposed to stress conditions due to nutrient deficiency (inorganic carbon) or change of environmental conditions (salinity, temperature, pH, light) sampled at 1 and 24 hours after the application of stress. The transcriptome profile of each strain revealed similarities and differences in gene expression for photosynthetic and respiratory electron transport chains and carbon fixation. Transcriptome profiles also helped us improve the structural annotation of the genome and identify possible missed genes (including anti-sense) and determine transcriptional units (operons). Finally, we predicted association of proteins of unknown function biochemical pathways by associating them to well-characterized ones based on their transcript levels correlation. Conclusions: Overall, this study results an informative annotation of those species and the comparative analysis of the response of the two organisms revealed similarities but also significant changes in the way they respond to external stress and the duration of the response

Resistance to the photosystem II herbicide diuron is dominant to sensitivity in the cyanobacterium Synechococcus sp. PCC7942

OpenAIRE

Brusslan, Judy; Haselkorn, Robert

1989-01-01

The transformable cyanobacterium, Synechococcus sp. PCC7942, was used to study the genetics of resistance to the herbicide diuron. In wild-type cells, diuron binds to one of the core proteins, called D1, of photosystem II reaction centres. This binding prevents the transfer of electrons from QA, the primary quinone acceptor, to QB, which is necessary to create the charge separation that drives ATP synthesis. A single amino acid substitution in the D1 protein reduces diuron binding and confers...

ORF Alignment: NC_006576 [GENIUS II[Archive

Lifescience Database Archive (English)

Full Text Available NC_006576 gi|56750058 >1v7zA 4 251 11 256 7e-49 ... ref|YP_170759.1| creatinine amido...hydrolase [Synechococcus elongatus PCC 6301] ... dbj|BAD78239.1| creatinine amidohydrolase [Synechoco

Integrated in silico Analyses of Regulatory and Metabolic Networks of Synechococcus sp. PCC 7002 Reveal Relationships between Gene Centrality and Essentiality

Directory of Open Access Journals (Sweden)

Hyun-Seob Song

2015-03-01

Full Text Available Cyanobacteria dynamically relay environmental inputs to intracellular adaptations through a coordinated adjustment of photosynthetic efficiency and carbon processing rates. The output of such adaptations is reflected through changes in transcriptional patterns and metabolic flux distributions that ultimately define growth strategy. To address interrelationships between metabolism and regulation, we performed integrative analyses of metabolic and gene co-expression networks in a model cyanobacterium, Synechococcus sp. PCC 7002. Centrality analyses using the gene co-expression network identified a set of key genes, which were defined here as “topologically important.” Parallel in silico gene knock-out simulations, using the genome-scale metabolic network, classified what we termed as “functionally important” genes, deletion of which affected growth or metabolism. A strong positive correlation was observed between topologically and functionally important genes. Functionally important genes exhibited variable levels of topological centrality; however, the majority of topologically central genes were found to be functionally essential for growth. Subsequent functional enrichment analysis revealed that both functionally and topologically important genes in Synechococcus sp. PCC 7002 are predominantly associated with translation and energy metabolism, two cellular processes critical for growth. This research demonstrates how synergistic network-level analyses can be used for reconciliation of metabolic and gene expression data to uncover fundamental biological principles.

Isolation Of PS II Nanoparticles And Oxygen Evolution Studies In Synechococcus Spp. PCC 7942 Under Heavy Metal Stress

Science.gov (United States)

Ahmad, Iffat Zareen; Sundaram, Shanthy; Tripathi, Ashutosh; Soumya, K. K.

2009-06-01

The effect of heavy metals was seen on the oxygen evolution pattern of a unicellular, non-heterocystous cyanobacterial strain of Synechococcus spp. PCC 7942. It was grown in a BG-11 medium supplemented with heavy metals, namely, nickel, copper, cadmium and mercury. Final concentrations of the heavy metal solution used in the culture were 0.1, 0.4 and 1 μM. All the experiments were performed in the exponential phase of the culture. Oxygen-evolving photosystem II (PS II) particles were purified from Synechococcus spp. PCC 7942 by a single-step Ni2+-affinity column chromatography after solubilization of thylakoid membranes with sucrose monolaurate. Oxygen evolution was measured with Clark type oxygen electrode fitted with a circulating water jacket. The light on the surface of the vessel was 10 w/m2. The cultures were incubated in light for 15 minutes prior to the measurement of oxygen evolution. Oxygen evolution was measured in assay mixture containing phosphate buffer (pH-7.5, 0.1 M) in the presence of potassium ferricyanide as the electron acceptor. The preparation from the control showed a high oxygen-evolving activity of 2, 300-2, 500 pmol O2 (mg Chl)-1 h-1 while the activity was decreased in the cultures grown with heavy metals. The inhibition of oxygen evolution shown by the organism in the presence of different metals was in the order Hg>Ni>Cd>Cu. Such heavy metal resistant strains will find application in the construction of PS II- based biosensors for the monitoring of pollutants.

Electric field effects on red chlorophylls, b-carotenes and P700 in cyanobacterial photosystem I complexes.

NARCIS (Netherlands)

Frese, R.N.; Palacios, M.A.; Azzizi, A.; van Stokkum, I.H.M.; Kruip, J.; Rögner, M.; Karapetyan, N.V.; Schlodder, E.; van Grondelle, R.; Dekker, J.P.

2002-01-01

We have probed the absorption changes due to an externally applied electric field (Stark effect) of Photosystem I (PSI) core complexes from the cyanobacteria Synechocystis sp. PCC 6803, Synechococcus elongatus and Spirulina platensis. The results reveal that the so-called C719 chlorophylls in S.

Photoautotrophic production of polyhydroxyalkanoates in a synthetic mixed culture of Synechococcus elongatus cscB and Pseudomonas putida cscAB.

Science.gov (United States)

Löwe, Hannes; Hobmeier, Karina; Moos, Manuel; Kremling, Andreas; Pflüger-Grau, Katharina

2017-01-01

One of the major challenges for the present and future generations is to find suitable substitutes for the fossil resources we rely on today. Cyanobacterial carbohydrates have been discussed as an emerging renewable feedstock in industrial biotechnology for the production of fuels and chemicals, showing promising production rates when compared to crop-based feedstock. However, intrinsic capacities of cyanobacteria to produce biotechnological compounds are limited and yields are low. Here, we present an approach to circumvent these problems by employing a synthetic bacterial co-culture for the carbon-neutral production of polyhydroxyalkanoates (PHAs) from CO 2 . The co-culture consists of two bio - modules : Bio - module I , in which the cyanobacterial strain Synechococcus elongatus cscB fixes CO 2 , converts it to sucrose, and exports it into the culture supernatant; and bio - module II , where this sugar serves as C-source for Pseudomonas putida cscAB and is converted to PHAs that are accumulated in the cytoplasm. By applying a nitrogen-limited process, we achieved a maximal PHA production rate of 23.8 mg/(L day) and a maximal titer of 156 mg/L. We will discuss the present shortcomings of the process and show the potential for future improvement. These results demonstrate the feasibility of mixed cultures of S. elongatus cscB and P. putida cscAB for PHA production, making room for the cornucopia of possible products that are described for P. putida . The construction of more efficient sucrose-utilizing P. putida phenotypes and the optimization of process conditions will increase yields and productivities and eventually close the gap in the contemporary process. In the long term, the co-culture may serve as a platform process, in which P. putida is used as a chassis for the implementation of synthetic metabolic pathways for biotechnological production of value-added products.

Variety of DNA Replication Activity Among Cyanobacteria Correlates with Distinct Respiration Activity in the Dark.

Science.gov (United States)

Ohbayashi, Ryudo; Yamamoto, Jun-Ya; Watanabe, Satoru; Kanesaki, Yu; Chibazakura, Taku; Miyagishima, Shin-Ya; Yoshikawa, Hirofumi

2017-02-01

Cyanobacteria exhibit light-dependent cell growth since most of their cellular energy is obtained by photosynthesis. In Synechococcus elongatus PCC 7942, one of the model cyanobacteria, DNA replication depends on photosynthetic electron transport. However, the critical signal for the regulatory mechanism of DNA replication has not been identified. In addition, conservation of this regulatory mechanism has not been investigated among cyanobacteria. To understand this regulatory signal and its dependence on light, we examined the regulation of DNA replication under both light and dark conditions among three model cyanobacteria, S. elongatus PCC 7942, Synechocystis sp. PCC 6803 and Anabaena sp. PCC 7120. Interestingly, DNA replication activity in Synechocystis and Anabaena was retained when cells were transferred to the dark, although it was drastically decreased in S. elongatus. Glycogen metabolism and respiration were higher in Synechocystis and Anabaena than in S. elongatus in the dark. Moreover, DNA replication activity in Synechocystis and Anabaena was reduced to the same level as that in S. elongatus by inhibition of respiratory electron transport after transfer to the dark. These results demonstrate that there is disparity in DNA replication occurring in the dark among cyanobacteria, which is caused by the difference in activity of respiratory electron transport. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Minimal tool set for a prokaryotic circadian clock.

Science.gov (United States)

Schmelling, Nicolas M; Lehmann, Robert; Chaudhury, Paushali; Beck, Christian; Albers, Sonja-Verena; Axmann, Ilka M; Wiegard, Anika

2017-07-21

Circadian clocks are found in organisms of almost all domains including photosynthetic Cyanobacteria, whereby large diversity exists within the protein components involved. In the model cyanobacterium Synechococcus elongatus PCC 7942 circadian rhythms are driven by a unique KaiABC protein clock, which is embedded in a network of input and output factors. Homologous proteins to the KaiABC clock have been observed in Bacteria and Archaea, where evidence for circadian behavior in these domains is accumulating. However, interaction and function of non-cyanobacterial Kai-proteins as well as homologous input and output components remain mainly unclear. Using a universal BLAST analyses, we identified putative KaiC-based timing systems in organisms outside as well as variations within Cyanobacteria. A systematic analyses of publicly available microarray data elucidated interesting variations in circadian gene expression between different cyanobacterial strains, which might be correlated to the diversity of genome encoded clock components. Based on statistical analyses of co-occurrences of the clock components homologous to Synechococcus elongatus PCC 7942, we propose putative networks of reduced and fully functional clock systems. Further, we studied KaiC sequence conservation to determine functionally important regions of diverged KaiC homologs. Biochemical characterization of exemplary cyanobacterial KaiC proteins as well as homologs from two thermophilic Archaea demonstrated that kinase activity is always present. However, a KaiA-mediated phosphorylation is only detectable in KaiC1 orthologs. Our analysis of 11,264 genomes clearly demonstrates that components of the Synechococcus elongatus PCC 7942 circadian clock are present in Bacteria and Archaea. However, all components are less abundant in other organisms than Cyanobacteria and KaiA, Pex, LdpA, and CdpA are only present in the latter. Thus, only reduced KaiBC-based or even simpler, solely KaiC-based timing systems

Alterations in protein synthesis in the cyanobacterium Synechococcus sp. Strain PCC 6301 in response to Calendula Micrantha extract with the Molluscicidal activity.

Energy Technology Data Exchange (ETDEWEB)

Hammouda, O H.E. [Botany Department, Faculty of Science, Cairo University, Beni-Suef branch. Beni Suef (Egypt); Borbely, G [Institute of plant physiology, Biological Research Center, Szeged H-6701, (Hungary)

1995-10-01

The response to the extract of the egyptian wild herb Calendula Micrantha, with the Molluscicidal activity, was examined in the unicellular no bacterium Synechococcus sp. strain PCC 6301. growth and chlorophyll of the cells were only slightly affected by low plant extract concentrations but were drastically reduced by high concentration. the rate of protein synthesis progressively decreased by increasing extract concentration. the cells preferentially induced the synthesis of a limited number of polypeptides in response to the treatment. Among the induced polypeptides were those with apparent molecular weights of 161 K (161.000), 96.7 K, 93.4 K, 69.9 K, 59 K, 49 K, 45 K, 35 K, 32.4 K, 28 K, 24 K, 21.7 K, 18 K and 16 K based on their mobilities in gel electrophoresis. these initial studies suggest that the plant extract exerted certain stress which stimulated alteration in the pattern of protein synthesis in Synechococcus sp. some of induced polypeptides are similar to that known to occur in other stresses specially heat shock stress. 3 figs.

Alterations in protein synthesis in the cyanobacterium Synechococcus sp. Strain PCC 6301 in response to Calendula Micrantha extract with the Molluscicidal activity

International Nuclear Information System (INIS)

Hammouda, O.H.E.; Borbely, G.

1995-01-01

The response to the extract of the egyptian wild herb Calendula Micrantha, with the Molluscicidal activity, was examined in the unicellular no bacterium Synechococcus sp. strain PCC 6301. growth and chlorophyll of the cells were only slightly affected by low plant extract concentrations but were drastically reduced by high concentration. the rate of protein synthesis progressively decreased by increasing extract concentration. the cells preferentially induced the synthesis of a limited number of polypeptides in response to the treatment. Among the induced polypeptides were those with apparent molecular weights of 161 K (161.000), 96.7 K, 93.4 K, 69.9 K, 59 K, 49 K, 45 K, 35 K, 32.4 K, 28 K, 24 K, 21.7 K, 18 K and 16 K based on their mobilities in gel electrophoresis. these initial studies suggest that the plant extract exerted certain stress which stimulated alteration in the pattern of protein synthesis in Synechococcus sp. some of induced polypeptides are similar to that known to occur in other stresses specially heat shock stress. 3 figs

Impact on the Fe redox cycling of organic ligands released by Synechococcus PCC 7002, under different iron fertilization scenarios. Modeling approach

Science.gov (United States)

Samperio-Ramos, Guillermo; González-Dávila, Melchor; Santana-Casiano, J. Magdalena

2018-06-01

The kinetics of Fe redox transformations are of crucial importance in determining the bioavailability of iron, due to inorganic Fe(II) and Fe weakly organic complexes being the most easily assimilated species by phytoplankton. The role played by the natural organic ligands excreted by the cyanobacteria Synecococcus PCC 7002 on the iron redox chemistry was studied at different stages of growth, considering changes in the organic exudation of the cyanobacteria, associated with growth under two different scenarios of iron availability. The oxidation/reduction processes of iron were studied at nanomolar levels and under different physicochemical conditions of pH (7.2- 8.2), temperature (5- 35 °C) and salinity (10- 37). The presence of natural organic exudates of Synechococcus affected the redox behavior of iron. A pH-dependent and photo-induced Fe(III) reduction process was detected in the presence of exudates produced under Fe-Low conditions. Photolytic reactions also modified the reactivity of those exudates with respect to Fe(II), increasing its lifetime in seawater. Without light mediated processes, organic ligands excreted under iron deficient conditions intensified the Fe(II) oxidation at pH redox constants between iron and the major ligands present in solution. Two organic type ligands for the exudates of Synechococcus PCC 7002, with different iron-chelation properties were included in the model. The Fe(II) speciation was radically affected when organic ligands were considered. The individual contributions to the overall Fe(II) oxidation rate demonstrated that these organic ligands played a key role in the oxidation process, although their contributions were dependent on the prescribed iron conditions. The study, therefore, suggests that the variability in the composition and nature of organic exudates released, due to iron availability conditions, might determine the redox behaviour of iron in seawater.

Toward solar biodiesel production from CO2 using engineered cyanobacteria.

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Woo, Han Min; Lee, Hyun Jeong

2017-05-01

Metabolic engineering of cyanobacteria has received attention as a sustainable strategy to convert carbon dioxide to various biochemicals including fatty acid-derived biodiesel. Recently, Synechococcus elongatus PCC 7942, a model cyanobacterium, has been engineered to convert CO2 to fatty acid ethyl esters (FAEEs) as biodiesel. Modular pathway has been constructed for FAEE production. Several metabolic engineering strategies were discussed to improve the production levels of FAEEs, including host engineering by improving CO2 fixation rate and photosynthetic efficiency. In addition, protein engineering of key enzyme in S. elongatus PCC 7942 was implemented to address issues on FAEE secretions toward sustainable FAEE production from CO2. Finally, advanced metabolic engineering will promote developing biosolar cell factories to convert CO2 to feasible amount of FAEEs toward solar biodiesel. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Microbial Carbonate Precipitation by Synechococcus PCC8806, LS0519 and Synechocystis PCC6803 on Concrete Surfaces and in Low Saturation Solution

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Zhu, T.; Lin, Y.; Dittrich, M.

2015-12-01

Microbial carbonate precipitation (MCP) by cyanobacteria has been recognized in a variety of environment such as freshwater, marine, cave, and even desert. Recently, their calcification potential has been tested in an emerging technology-- bioconcrete. This study is to explore the calcification by three cyanobacteria strains under different environmental conditions. Experiment A was carried out in 2mM NaHCO3 and 5mM CaCl2, with a cell concentration of 107 cells L-1. In experiment B, one side of the concrete surface was treated with bacteria and then immersed in the solution containing 0.4 mM NaHCO3 and 300 mM CaCl2. In experiment A, the pH of the abiotic condition remained constant around 8.55, while that of biotic conditions increased by 0.15 units in the presence of LS0519, and by 0.3 units in the presence of PCC8806 or PCC6803 within 8 hours. Over a period of 30 hours, PCC8806, LS0519 and PCC6803 removed 0.1, 0.12 and 0.2 mM calcium from the solution respectively. After 30 hours, the alkalinity of the solution decreased by 30 mg/L, 10 mg/L and 5 mg/L respectively in the presence of PCC6803, LS0519 and PCC8806. Under scanning electron microscopy (SEM), no precipitate was found in the abiotic condition, while calcium carbonate was associated by all the three strains. Among them, PCC6803 precipitated more carbonates. In experiment B, LS0519 and PCC8806 increased the pH with a value of 0.25, while PCC6803 increased the pH by 0.33 units. SEM shows LS0519 was less likely attached to the concrete surface. Neither did the precipitates on concrete surface differ from that in the abiotic condition. In comparison, PCC8806 and PCC6803 were closely associated with 8-μm porous precipitates. Cells were either found enclosed in precipitates or connecting two precipitates. In conclusion, all the three strains triggered the calcium carbonate precipitation. LS0519 has a little impact on the carbonate precipitation in the solution, but negligent influence on the concrete surface

Synechocystis sp. PCC 6803 CruA (sll0147) encodes lycopene cyclase and requires bound chlorophyll a for activity.

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Xiong, Wei; Shen, Gaozhong; Bryant, Donald A

2017-03-01

The genome of the model cyanobacterium, Synechococcus sp. PCC 7002, encodes two paralogs of CruA-type lycopene cyclases, SynPCC7002_A2153 and SynPCC7002_A0043, which are denoted cruA and cruP, respectively. Unlike the wild-type strain, a cruA deletion mutant is light-sensitive, grows slowly, and accumulates lycopene, γ-carotene, and 1-OH-lycopene; however, this strain still produces β-carotene and other carotenoids derived from it. Expression of cruA from Synechocystis sp. PCC 6803 (cruA 6803 ) in Escherichia coli strains that synthesize either lycopene or γ-carotene did not lead to the synthesis of either γ-carotene or β-carotene, respectively. However, expression of this orthologous cruA 6803 gene (sll0147) in the Synechococcus sp. PCC 7002 cruA deletion mutant produced strains with phenotypic properties identical to the wild type. CruA 6803 was purified from Synechococcus sp. PCC 7002 by affinity chromatography, and the purified protein was pale yellow-green due to the presence of bound chlorophyll (Chl) a and β-carotene. Native polyacrylamide gel electrophoresis of the partly purified protein in the presence of lithium dodecylsulfate at 4 °C confirmed that the protein was yellow-green in color. When purified CruA 6803 was assayed in vitro with either lycopene or γ-carotene as substrate, β-carotene was synthesized. These data establish that CruA 6803 is a lycopene cyclase and that it requires a bound Chl a molecule for activity. Possible binding sites for Chl a and the potential regulatory role of the Chl a in coordination of Chl and carotenoid biosynthesis are discussed.

Improved Alkane Production in Nitrogen-Fixing and Halotolerant Cyanobacteria via Abiotic Stresses and Genetic Manipulation of Alkane Synthetic Genes.

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Kageyama, Hakuto; Waditee-Sirisattha, Rungaroon; Sirisattha, Sophon; Tanaka, Yoshito; Mahakhant, Aparat; Takabe, Teruhiro

2015-07-01

Cyanobacteria possess the unique capacity to produce alkane. In this study, effects of nitrogen deficiency and salt stress on biosynthesis of alkanes were investigated in three kinds of cyanobacteria. Intracellular alkane accumulation was increased in nitrogen-fixing cyanobacterium Anabaena sp. PCC7120, but decreased in non-diazotrophic cyanobacterium Synechococcus elongatus PCC7942 and constant in a halotolerant cyanobacterium Aphanothece halophytica under nitrogen-deficient condition. We also found that salt stress increased alkane accumulation in Anabaena sp. PCC7120 and A. halophytica. The expression levels of two alkane synthetic genes were not upregulated significantly under nitrogen deficiency or salt stress in Anabaena sp. PCC7120. The transformant Anabaena sp. PCC7120 cells with additional alkane synthetic gene set from A. halophytica increased intracellular alkane accumulation level compared to control cells. These results provide a prospect to improve bioproduction of alkanes in nitrogen-fixing halotolerant cyanobacteria via abiotic stresses and genetic engineering.

Roles of xanthophyll carotenoids in protection against photoinhibition and oxidative stress in the cyanobacterium Synechococcus sp. strain PCC 7002.

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Zhu, Yuehui; Graham, Joel E; Ludwig, Marcus; Xiong, Wei; Alvey, Richard M; Shen, Gaozhong; Bryant, Donald A

2010-12-01

Synechococcus sp. strain PCC 7002 is a robust, genetically tractable cyanobacterium that produces six different xanthophyll carotenoids (zeaxanthin, cryptoxanthin, myxoxanthophyll (myxol-2'-fucoside), echinenone, 3'-hydroxyechinenone, and synechoxanthin) and tolerates many environmental stresses, including high light intensities. Targeted mutations were introduced to block the branches of the carotenoid biosynthetic pathway leading to specific xanthophylls, and a mutant lacking all xanthophylls was constructed. Some of the mutants showed severe growth defects at high light intensities, and multi-locus mutants had somewhat lower chlorophyll contents and lower photosystem I levels. The results suggested that xanthophylls, particularly zeaxanthin and echinenone, might play regulatory roles in thylakoid biogenesis. Measurements of reactive oxygen (ROS) and nitrogen (RNS) species in the mutants showed that all xanthophylls participate in preventing ROS/RNS accumulation and that a mutant lacking all xanthophylls accumulated very high levels of ROS/RNS. Results from transcription profiling showed that mRNA levels for most genes encoding the enzymes of carotenogenesis are significantly more abundant after exposure to high light. These studies indicated that all xanthophylls contribute to protection against photo-oxidative stress. Copyright © 2010 Elsevier Inc. All rights reserved.

Anchoring a plant cytochrome P450 via PsaM to the thylakoids in Synechococcus sp. PCC 7002: evidence for light-driven biosynthesis.

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Lærke Münter Lassen

Full Text Available Plants produce an immense variety of specialized metabolites, many of which are of high value as their bioactive properties make them useful as for instance pharmaceuticals. The compounds are often produced at low levels in the plant, and due to their complex structures, chemical synthesis may not be feasible. Here, we take advantage of the reducing equivalents generated in photosynthesis in developing an approach for producing plant bioactive natural compounds in a photosynthetic microorganism by functionally coupling a biosynthetic enzyme to photosystem I. This enables driving of the enzymatic reactions with electrons extracted from the photosynthetic electron transport chain. As a proof of concept, we have genetically fused the soluble catalytic domain of the cytochrome P450 CYP79A1, originating from the endoplasmic reticulum membranes of Sorghum bicolor, to a photosystem I subunit in the cyanobacterium Synechococcus sp. PCC 7002, thereby targeting it to the thylakoids. The engineered enzyme showed light-driven activity both in vivo and in vitro, demonstrating the possibility to achieve light-driven biosynthesis of high-value plant specialized metabolites in cyanobacteria.

The use of fluorescence microscopy and image analysis for rapid detection of non-producing revertant cells of Synechocystis sp. PCC6803 and Synechococcus sp. PCC7002.

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Schulze, Katja; Lang, Imke; Enke, Heike; Grohme, Diana; Frohme, Marcus

2015-04-17

Ethanol production via genetically engineered cyanobacteria is a promising solution for the production of biofuels. Through the introduction of a pyruvate decarboxylase and alcohol dehydrogenase direct ethanol production becomes possible within the cells. However, during cultivation genetic instability can lead to mutations and thus loss of ethanol production. Cells then revert back to the wild type phenotype. A method for a rapid and simple detection of these non-producing revertant cells in an ethanol producing cell population is an important quality control measure in order to predict genetic stability and the longevity of a producing culture. Several comparable cultivation experiments revealed a difference in the pigmentation for non-producing and producing cells: the accessory pigment phycocyanin (PC) is reduced in case of the ethanol producer, resulting in a yellowish appearance of the culture. Microarray and western blot studies of Synechocystis sp. PCC6803 and Synechococcus sp. PCC7002 confirmed this PC reduction on the level of RNA and protein. Based on these findings we developed a method for fluorescence microscopy in order to distinguish producing and non-producing cells with respect to their pigmentation phenotype. By applying a specific filter set the emitted fluorescence of a producer cell with a reduced PC content appeared orange. The emitted fluorescence of a non-producing cell with a wt pigmentation phenotype was detected in red, and dead cells in green. In an automated process multiple images of each sample were taken and analyzed with a plugin for the image analysis software ImageJ to identify dead (green), non-producing (red) and producing (orange) cells. The results of the presented validation experiments revealed a good identification with 98 % red cells in the wt sample and 90 % orange cells in the producer sample. The detected wt pigmentation phenotype (red cells) in the producer sample were either not fully induced yet (in 48 h induced

Species-specific roles of sulfolipid metabolism in acclimation of photosynthetic microbes to sulfur-starvation stress.

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Norihiro Sato

Full Text Available Photosynthetic organisms utilize sulfate for the synthesis of sulfur-compounds including proteins and a sulfolipid, sulfoquinovosyl diacylglycerol. Upon ambient deficiency in sulfate, cells of a green alga, Chlamydomonas reinhardtii, degrade the chloroplast membrane sulfolipid to ensure an intracellular-sulfur source for necessary protein synthesis. Here, the effects of sulfate-starvation on the sulfolipid stability were investigated in another green alga, Chlorella kessleri, and two cyanobacteria, Synechocystis sp. PCC 6803 and Synechococcus elongatus PCC 7942. The results showed that sulfolipid degradation was induced only in C. kessleri, raising the possibility that this degradation ability was obtained not by cyanobacteria, but by eukaryotic algae during the evolution of photosynthetic organisms. Meanwhile, Synechococcus disruptants concerning sqdB and sqdX genes, which are involved in successive reactions in the sulfolipid synthesis pathway, were respectively characterized in cellular response to sulfate-starvation. Phycobilisome degradation intrinsic to Synechococcus, but not to Synechocystis, and cell growth under sulfate-starved conditions were repressed in the sqdB and sqdX disruptants, respectively, relative to in the wild type. Their distinct phenotypes, despite the common loss of the sulfolipid, inferred specific roles of sqdB and sqdX. This study demonstrated that sulfolipid metabolism might have been developed to enable species- or cyanobacterial-strain dependent processes for acclimation to sulfate-starvation.

Genome Engineering of the 2,3-Butanediol Biosynthetic Pathway for Tight Regulation in Cyanobacteria.

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Nozzi, Nicole E; Atsumi, Shota

2015-11-20

Cyanobacteria have gained popularity among the metabolic engineering community as a tractable photosynthetic host for renewable chemical production. However, though a number of successfully engineered production systems have been reported, long-term genetic stability remains an issue for cyanobacterial systems. The genetic engineering toolbox for cyanobacteria is largely lacking inducible systems for expression control. The characterization of tight regulation systems for use in cyanobacteria may help to alleviate this problem. In this work we explore the function of the IPTG inducible promoter P(L)lacO1 in the model cyanobacterium Synechococcus elongatus PCC 7942 as well as the effect of gene order within an operon on pathway expression. According to our experiments, P(L)lacO1 functions well as an inducible promoter in S. elongatus. Additionally, we found that gene order within an operon can strongly influence control of expression of each gene.

Unique attributes of cyanobacterial metabolism revealed by improved genome-scale metabolic modeling and essential gene analysis

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Broddrick, Jared T.; Rubin, Benjamin E.; Welkie, David G.; Du, Niu; Mih, Nathan; Diamond, Spencer; Lee, Jenny J.; Golden, Susan S.; Palsson, Bernhard O.

2016-01-01

The model cyanobacterium, Synechococcus elongatus PCC 7942, is a genetically tractable obligate phototroph that is being developed for the bioproduction of high-value chemicals. Genome-scale models (GEMs) have been successfully used to assess and engineer cellular metabolism; however, GEMs of phototrophic metabolism have been limited by the lack of experimental datasets for model validation and the challenges of incorporating photon uptake. Here, we develop a GEM of metabolism in S. elongatus using random barcode transposon site sequencing (RB-TnSeq) essential gene and physiological data specific to photoautotrophic metabolism. The model explicitly describes photon absorption and accounts for shading, resulting in the characteristic linear growth curve of photoautotrophs. GEM predictions of gene essentiality were compared with data obtained from recent dense-transposon mutagenesis experiments. This dataset allowed major improvements to the accuracy of the model. Furthermore, discrepancies between GEM predictions and the in vivo dataset revealed biological characteristics, such as the importance of a truncated, linear TCA pathway, low flux toward amino acid synthesis from photorespiration, and knowledge gaps within nucleotide metabolism. Coupling of strong experimental support and photoautotrophic modeling methods thus resulted in a highly accurate model of S. elongatus metabolism that highlights previously unknown areas of S. elongatus biology. PMID:27911809

Light-optimized growth of cyanobacterial cultures: Growth phases and productivity of biomass and secreted molecules in light-limited batch growth.

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Clark, Ryan L; McGinley, Laura L; Purdy, Hugh M; Korosh, Travis C; Reed, Jennifer L; Root, Thatcher W; Pfleger, Brian F

2018-03-27

Cyanobacteria are photosynthetic microorganisms whose metabolism can be modified through genetic engineering for production of a wide variety of molecules directly from CO 2 , light, and nutrients. Diverse molecules have been produced in small quantities by engineered cyanobacteria to demonstrate the feasibility of photosynthetic biorefineries. Consequently, there is interest in engineering these microorganisms to increase titer and productivity to meet industrial metrics. Unfortunately, differing experimental conditions and cultivation techniques confound comparisons of strains and metabolic engineering strategies. In this work, we discuss the factors governing photoautotrophic growth and demonstrate nutritionally replete conditions in which a model cyanobacterium can be grown to stationary phase with light as the sole limiting substrate. We introduce a mathematical framework for understanding the dynamics of growth and product secretion in light-limited cyanobacterial cultures. Using this framework, we demonstrate how cyanobacterial growth in differing experimental systems can be easily scaled by the volumetric photon delivery rate using the model organisms Synechococcus sp. strain PCC7002 and Synechococcus elongatus strain UTEX2973. We use this framework to predict scaled up growth and product secretion in 1L photobioreactors of two strains of Synechococcus PCC7002 engineered for production of l-lactate or L-lysine. The analytical framework developed in this work serves as a guide for future metabolic engineering studies of cyanobacteria to allow better comparison of experiments performed in different experimental systems and to further investigate the dynamics of growth and product secretion. Copyright © 2018 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

Persistence of Only a Minute Viable Population in Chlorotic Microcystis aeruginosa PCC 7806 Cultures Obtained by Nutrient Limitation.

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Diogo de Abreu Meireles

Full Text Available Cultures from the cyanobacterial strain Microcystis aeruginosa PCC 7806 submitted to nutrient limitation become chlorotic. When returned to nutrient rich conditions these cultures regain their green colour. The aim of this study was to verify whether the cells in these cultures could be considered resting stages allowing the survival of periods of nutrient starvation as has been reported for Synechococcus PCC 7942. The experiments with Microcystis were carried out in parallel with Synechococcus cultures to rule out the possibility that any results obtained with Microcystis were due to our particular experimental conditions. The results of the experiments with Synechococcus PCC 7942 cultures were comparable to the reported in the literature. For Microcystis PCC 7806 a different response was observed. Analysis of chlorotic Microcystis cultures by flow cytometry showed that the phenotype of the cells in the population was not homogenous: the amount of nucleic acids was about the same in all cells but only around one percent of the population emitted red autofluorescence indicating the presence of chlorophyll. Monitoring of the reversion of chlorosis by flow cytometry showed that the re-greening was most likely the result of the division of the small population of red autofluorescent cells originally present in the chlorotic cultures. This assumption was confirmed by analysing the integrity of the DNA and the membrane permeability of the cells of chlorotic cultures. Most of the DNA of these cultures was degraded and only the autofluorescent population of the chlorotic cultures showed membrane integrity. Thus, contrary to what has been reported for other cyanobacterial genera, most of the cells in chlorotic Microcystis cultures are not resting stages but dead. It is interesting to note that the red autofluorescent cells of green and chlorotic cultures obtained in double strength ASM-1 medium differ with respect to metabolism: levels of emission of

Persistence of Only a Minute Viable Population in Chlorotic Microcystis aeruginosa PCC 7806 Cultures Obtained by Nutrient Limitation.

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Meireles, Diogo de Abreu; Schripsema, Jan; Arnholdt, Andrea Cristina Vetö; Dagnino, Denise

2015-01-01

Cultures from the cyanobacterial strain Microcystis aeruginosa PCC 7806 submitted to nutrient limitation become chlorotic. When returned to nutrient rich conditions these cultures regain their green colour. The aim of this study was to verify whether the cells in these cultures could be considered resting stages allowing the survival of periods of nutrient starvation as has been reported for Synechococcus PCC 7942. The experiments with Microcystis were carried out in parallel with Synechococcus cultures to rule out the possibility that any results obtained with Microcystis were due to our particular experimental conditions. The results of the experiments with Synechococcus PCC 7942 cultures were comparable to the reported in the literature. For Microcystis PCC 7806 a different response was observed. Analysis of chlorotic Microcystis cultures by flow cytometry showed that the phenotype of the cells in the population was not homogenous: the amount of nucleic acids was about the same in all cells but only around one percent of the population emitted red autofluorescence indicating the presence of chlorophyll. Monitoring of the reversion of chlorosis by flow cytometry showed that the re-greening was most likely the result of the division of the small population of red autofluorescent cells originally present in the chlorotic cultures. This assumption was confirmed by analysing the integrity of the DNA and the membrane permeability of the cells of chlorotic cultures. Most of the DNA of these cultures was degraded and only the autofluorescent population of the chlorotic cultures showed membrane integrity. Thus, contrary to what has been reported for other cyanobacterial genera, most of the cells in chlorotic Microcystis cultures are not resting stages but dead. It is interesting to note that the red autofluorescent cells of green and chlorotic cultures obtained in double strength ASM-1 medium differ with respect to metabolism: levels of emission of red autofluorescence

Transcription profiling of the model cyanobacterium Synechococcus sp. strain PCC 7002 by NextGen (SOLiD™ Sequencing of cDNA

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Marcus eLudwig

2011-03-01

Full Text Available The genome of the unicellular, euryhaline cyanobacterium Synechococcus sp. PCC 7002 encodes about 3200 proteins. Transcripts were detected for nearly all annotated open reading frames by a global transcriptomic analysis by Next-Generation (SOLiDTM sequencing of cDNA. In the cDNA samples sequenced, ~90% of the mapped sequences were derived from the 16S and 23S ribosomal RNAs and ~10% of the sequences were derived from mRNAs. In cells grown photoautotrophically under standard conditions (38 °C, 1% (v/v CO2 in air, 250 µmol photons m-2 s-1, the highest transcript levels (up to 2% of the total mRNA for the most abundantly transcribed genes (e. g., cpcAB, psbA, psaA were generally derived from genes encoding structural components of the photosynthetic apparatus. High light exposure for one hour caused changes in transcript levels for genes encoding proteins of the photosynthetic apparatus, Type-1 NADH dehydrogenase complex and ATP synthase, whereas dark incubation for one hour resulted in a global decrease in transcript levels for photosynthesis-related genes and an increase in transcript levels for genes involved in carbohydrate degradation. Transcript levels for pyruvate kinase and the pyruvate dehydrogenase complex decreased sharply in cells incubated in the dark. Under dark anoxic (fermentative conditions, transcript changes indicated a global decrease in transcripts for respiratory proteins and suggested that cells employ an alternative phosphoenolpyruvate degradation pathway via phosphoenolpyruvate synthase (ppsA and the pyruvate:ferredoxin oxidoreductase (nifJ. Finally, the data suggested that an apparent operon involved in tetrapyrrole biosynthesis and fatty acid desaturation, acsF2-ho2-hemN2-desF, may be regulated by oxygen concentration.

Iron Isotope Fractionation during Fe(II) Oxidation Mediated by the Oxygen-Producing Marine Cyanobacterium Synechococcus PCC 7002

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Swanner, E. D.; Bayer, T.; Wu, W.; Hao, L.; Obst, M.; Sundman, A.; Byrne, J. M.; Michel, F. M.; Kleinhanns, I. C.; Kappler, A.; Schoenberg, R.

2017-04-11

In this study, we couple iron isotope analysis to microscopic and mineralogical investigation of iron speciation during circumneutral Fe(II) oxidation and Fe(III) precipitation with photosynthetically produced oxygen. In the presence of the cyanobacterium Synechococcus PCC 7002, aqueous Fe(II) (Fe(II)_aq) is oxidized and precipitated as amorphous Fe(III) oxyhydroxide minerals (iron precipitates, Fe_ppt), with distinct isotopic fractionation (ε⁵⁶Fe) values determined from fitting the δ⁵⁶Fe(II)_aq (1.79‰ and 2.15‰) and the δ⁵⁶Fe_ppt (2.44‰ and 2.98‰) data trends from two replicate experiments. Additional Fe(II) and Fe(III) phases were detected using microscopy and chemical extractions and likely represent Fe(II) and Fe(III) sorbed to minerals and cells. The iron desorbed with sodium acetate (FeNaAc) yielded heavier δ⁵⁶Fe compositions than Fe(II)_aq. Modeling of the fractionation during Fe(III) sorption to cells and Fe(II) sorption to Feppt, combined with equilibration of sorbed iron and with Fe(II)_aq using published fractionation factors, is consistent with our resulting δ⁵⁶FeNaAc. The δ⁵⁶Fe_ppt data trend is inconsistent with complete equilibrium exchange with Fe(II)aq. Because of this and our detection of microbially excreted organics (e.g., exopolysaccharides) coating Feppt in our microscopic analysis, we suggest that electron and atom exchange is partially suppressed in this system by biologically produced organics. These results indicate that cyanobacteria influence the fate and composition of iron in sunlit environments via their role in Fe(II) oxidation through O₂ production, the capacity of their cell surfaces to sorb iron, and the interaction of secreted organics with Fe(III) minerals.

Marine Synechococcus Aggregation

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Neuer, S.; Deng, W.; Cruz, B. N.; Monks, L.

2016-02-01

Cyanobacteria are considered to play an important role in the oceanic biological carbon pump, especially in oligotrophic regions. But as single cells are too small to sink, their carbon export has to be mediated by aggregate formation and possible consumption by zooplankton producing sinking fecal pellets. Here we report results on the aggregation of the ubiquitous marine pico-cyanobacterium Synechococcus as a model organism. We first investigated the mechanism behind such aggregation by studying the potential role of transparent exopolymeric particles (TEP) and the effects of nutrient (nitrogen or phosphorus) limitation on the TEP production and aggregate formation of these pico-cyanobacteria. We further studied the aggregation and subsequent settling in roller tanks and investigated the effects of the clays kaolinite and bentonite in a series of concentrations. Our results show that despite of the lowered growth rates, Synechococcus in nutrient limited cultures had larger cell-normalized TEP production, formed a greater volume of aggregates, and resulted in higher settling velocities compared to results from replete cultures. In addition, we found that despite their small size and lack of natural ballasting minerals, Synechococcus cells could still form aggregates and sink at measureable velocities in seawater. Clay minerals increased the number and reduced the size of aggregates, and their ballasting effects increased the sinking velocity and carbon export potential of aggregates. In comparison with the Synechococcus, we will also present results of the aggregation of the pico-cyanobacterium Prochlorococcus in roller tanks. These results contribute to our understanding in the physiology of marine Synechococcus as well as their role in the ecology and biogeochemistry in oligotrophic oceans.

Specific Interaction between Redox Phospholipid Polymers and Plastoquinone in Photosynthetic Electron Transport Chain.

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Tanaka, Kenya; Kaneko, Masahiro; Ishikawa, Masahito; Kato, Souichiro; Ito, Hidehiro; Kamachi, Toshiaki; Kamiya, Kazuhide; Nakanishi, Shuji

2017-04-19

Redox phospholipid polymers added in culture media are known to be capable of extracting electrons from living photosynthetic cells across bacterial cell membranes with high cytocompatibility. In the present study, we identify the intracellular redox species that transfers electrons to the polymers. The open-circuit electrochemical potential of an electrolyte containing the redox polymer and extracted thylakoid membranes shift to positive (or negative) under light irradiation, when an electron transport inhibitor specific to plastoquinone is added upstream (or downstream) in the photosynthetic electron transport chain. The same trend is also observed for a medium containing living photosynthetic cells of Synechococcus elongatus PCC7942. These results clearly indicate that the phospholipid redox polymers extract photosynthetic electrons mainly from plastoquinone. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Towards a synthetic chloroplast.

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Christina M Agapakis

2011-04-01

Full Text Available The evolution of eukaryotic cells is widely agreed to have proceeded through a series of endosymbiotic events between larger cells and proteobacteria or cyanobacteria, leading to the formation of mitochondria or chloroplasts, respectively. Engineered endosymbiotic relationships between different species of cells are a valuable tool for synthetic biology, where engineered pathways based on two species could take advantage of the unique abilities of each mutualistic partner.We explored the possibility of using the photosynthetic bacterium Synechococcus elongatus PCC 7942 as a platform for studying evolutionary dynamics and for designing two-species synthetic biological systems. We observed that the cyanobacteria were relatively harmless to eukaryotic host cells compared to Escherichia coli when injected into the embryos of zebrafish, Danio rerio, or taken up by mammalian macrophages. In addition, when engineered with invasin from Yersinia pestis and listeriolysin O from Listeria monocytogenes, S. elongatus was able to invade cultured mammalian cells and divide inside macrophages.Our results show that it is possible to engineer photosynthetic bacteria to invade the cytoplasm of mammalian cells for further engineering and applications in synthetic biology. Engineered invasive but non-pathogenic or immunogenic photosynthetic bacteria have great potential as synthetic biological devices.

Diversification of DnaA dependency for DNA replication in cyanobacterial evolution.

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Ohbayashi, Ryudo; Watanabe, Satoru; Ehira, Shigeki; Kanesaki, Yu; Chibazakura, Taku; Yoshikawa, Hirofumi

2016-05-01

Regulating DNA replication is essential for all living cells. The DNA replication initiation factor DnaA is highly conserved in prokaryotes and is required for accurate initiation of chromosomal replication at oriC. DnaA-independent free-living bacteria have not been identified. The dnaA gene is absent in plastids and some symbiotic bacteria, although it is not known when or how DnaA-independent mechanisms were acquired. Here, we show that the degree of dependency of DNA replication on DnaA varies among cyanobacterial species. Deletion of the dnaA gene in Synechococcus elongatus PCC 7942 shifted DNA replication from oriC to a different site as a result of the integration of an episomal plasmid. Moreover, viability during the stationary phase was higher in dnaA disruptants than in wild-type cells. Deletion of dnaA did not affect DNA replication or cell growth in Synechocystis sp. PCC 6803 or Anabaena sp. PCC 7120, indicating that functional dependency on DnaA was already lost in some nonsymbiotic cyanobacterial lineages during diversification. Therefore, we proposed that cyanobacteria acquired DnaA-independent replication mechanisms before symbiosis and such an ancestral cyanobacterium was the sole primary endosymbiont to form a plastid precursor.

Global metabolic rewiring for improved CO2 fixation and chemical production in cyanobacteria

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Kanno, Masahiro; Carroll, Austin L.; Atsumi, Shota

2017-03-01

Cyanobacteria have attracted much attention as hosts to recycle CO2 into valuable chemicals. Although cyanobacteria have been engineered to produce various compounds, production efficiencies are too low for commercialization. Here we engineer the carbon metabolism of Synechococcus elongatus PCC 7942 to improve glucose utilization, enhance CO2 fixation and increase chemical production. We introduce modifications in glycolytic pathways and the Calvin Benson cycle to increase carbon flux and redirect it towards carbon fixation. The engineered strain efficiently uses both CO2 and glucose, and produces 12.6 g l-1 of 2,3-butanediol with a rate of 1.1 g l-1 d-1 under continuous light conditions. Removal of native regulation enables carbon fixation and 2,3-butanediol production in the absence of light. This represents a significant step towards industrial viability and an excellent example of carbon metabolism plasticity.

PipY, a Member of the Conserved COG0325 Family of PLP-Binding Proteins, Expands the Cyanobacterial Nitrogen Regulatory Network

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José I. Labella

2017-07-01

Full Text Available Synechococcus elongatus PCC 7942 is a paradigmatic model organism for nitrogen regulation in cyanobacteria. Expression of genes involved in nitrogen assimilation is positively regulated by the 2-oxoglutarate receptor and global transcriptional regulator NtcA. Maximal activation requires the subsequent binding of the co-activator PipX. PII, a protein found in all three domains of life as an integrator of signals of the nitrogen and carbon balance, binds to PipX to counteract NtcA activity at low 2-oxoglutarate levels. PII-PipX complexes can also bind to the transcriptional regulator PlmA, whose regulon remains unknown. Here we expand the nitrogen regulatory network to PipY, encoded by the bicistronic operon pipXY in S. elongatus. Work with PipY, the cyanobacterial member of the widespread family of COG0325 proteins, confirms the conserved roles in vitamin B6 and amino/keto acid homeostasis and reveals new PLP-related phenotypes, including sensitivity to antibiotics targeting essential PLP-holoenzymes or synthetic lethality with cysK. In addition, the related phenotypes of pipY and pipX mutants are consistent with genetic interactions in the contexts of survival to PLP-targeting antibiotics and transcriptional regulation. We also showed that PipY overexpression increased the length of S. elongatus cells. Taken together, our results support a universal regulatory role for COG0325 proteins, paving the way to a better understanding of these proteins and of their connections with other biological processes.

Silica ecosystem for synergistic biotransformation

Science.gov (United States)

Mutlu, Baris R.; Sakkos, Jonathan K.; Yeom, Sujin; Wackett, Lawrence P.; Aksan, Alptekin

2016-06-01

Synergistical bacterial species can perform more varied and complex transformations of chemical substances than either species alone, but this is rarely used commercially because of technical difficulties in maintaining mixed cultures. Typical problems with mixed cultures on scale are unrestrained growth of one bacterium, which leads to suboptimal population ratios, and lack of control over bacterial spatial distribution, which leads to inefficient substrate transport. To address these issues, we designed and produced a synthetic ecosystem by co-encapsulation in a silica gel matrix, which enabled precise control of the microbial populations and their microenvironment. As a case study, two greatly different microorganisms: Pseudomonas sp. NCIB 9816 and Synechococcus elongatus PCC 7942 were encapsulated. NCIB 9816 can aerobically biotransform over 100 aromatic hydrocarbons, a feat useful for synthesis of higher value commodity chemicals or environmental remediation. In our system, NCIB 9816 was used for biotransformation of naphthalene (a model substrate) into CO2 and the cyanobacterium PCC 7942 was used to provide the necessary oxygen for the biotransformation reactions via photosynthesis. A mathematical model was constructed to determine the critical cell density parameter to maximize oxygen production, and was then used to maximize the biotransformation rate of the system.

Engineering a cyanobacterium as the catalyst for the photosynthetic conversion of CO2 to 1,2-propanediol

Directory of Open Access Journals (Sweden)

Li Han

2013-01-01

Full Text Available Abstract Background The modern society primarily relies on petroleum and natural gas for the production of fuels and chemicals. One of the major commodity chemicals 1,2-propanediol (1,2-PDO, which has an annual production of more than 0.5 million tons in the United States, is currently produced by chemical processes from petroleum derived propylene oxide, which is energy intensive and not sustainable. In this study, we sought to achieve photosynthetic production of 1,2-PDO from CO2 using a genetically engineered cyanobacterium Synechococcus elongatus PCC 7942. Compared to the previously reported biological 1,2-PDO production processes which used sugar or glycerol as the substrates, direct chemical production from CO2 in photosynthetic organisms recycles the atmospheric CO2 and will not compete with food crops for arable land. Results In this study, we reported photosynthetic production of 1,2-PDO from CO2 using a genetically engineered cyanobacterium Synechococcus elongatus PCC 7942. Introduction of the genes encoding methylglyoxal synthase (mgsA, glycerol dehydrogenase (gldA, and aldehyde reductase (yqhD resulted in the production of ~22mg/L 1,2-PDO from CO2. However, a comparable amount of the pathway intermediate acetol was also produced, especially during the stationary phase. The production of 1,2-PDO requires a robust input of reducing equivalents from cellular metabolism. To take advantage of cyanobacteria’s NADPH pool, the synthetic pathway of 1,2-PDO was engineered to be NADPH-dependent by exploiting the NADPH-specific secondary alcohol dehydrogenases which have not been reported for 1,2-PDO production previously. This optimization strategy resulted in the production of ~150mg/L 1,2-PDO and minimized the accumulation of the incomplete reduction product, acetol. Conclusion This work demonstrated that cyanobacteria can be engineered as a catalyst for the photosynthetic conversion of CO2 to 1,2-PDO. This work also characterized two NADPH

Cell surface acid-base properties of the cyanobacterium Synechococcus: Influences of nitrogen source, growth phase and N:P ratios

Science.gov (United States)

Liu, Yuxia; Alessi, D. S.; Owttrim, G. W.; Kenney, J. P. L.; Zhou, Qixing; Lalonde, S. V.; Konhauser, K. O.

2016-08-01

The distribution of many trace metals in the oceans is controlled by biological uptake. Recently, Liu et al. (2015) demonstrated the propensity for a marine cyanobacterium to adsorb cadmium from seawater, suggesting that cell surface reactivity might also play an important role in the cycling of metals in the oceans. However, it remains unclear how variations in cyanobacterial growth rates and nutrient supply might affect the chemical properties of their cellular surfaces. In this study we used potentiometric titrations and Fourier Transform Infrared (FT-IR) spectrometry to profile the key metabolic changes and surface chemical responses of a Synechococcus strain, PCC 7002, during different growth regimes. This included testing various nitrogen (N) to phosphorous (P) ratios (both nitrogen and phosphorous dependent), nitrogen sources (nitrate, ammonium and urea) and growth stages (exponential, stationary, and death phase). FT-IR spectroscopy showed that varying the growth substrates on which Synechococcus cells were cultured resulted in differences in either the type or abundance of cellular exudates produced or a change in the cell wall components. Potentiometric titration data were modeled using three distinct proton binding sites, with resulting pKa values for cells of the various growth conditions in the ranges of 4.96-5.51 (pKa1), 6.67-7.42 (pKa2) and 8.13-9.95 (pKa3). According to previous spectroscopic studies, these pKa ranges are consistent with carboxyl, phosphoryl, and amine groups, respectively. Comparisons between the titration data (for the cell surface) and FT-IR spectra (for the average cellular changes) generally indicate (1) that the nitrogen source is a greater determinant of ligand concentration than growth phase, and (2) that phosphorus limitation has a greater impact on Synechococcus cellular and extracellular properties than does nitrogen limitation. Taken together, these techniques indicate that nutritional quality during cell growth can

Circadian clock protein KaiC forms ATP-dependent hexameric rings and binds DNA.

Science.gov (United States)

Mori, Tetsuya; Saveliev, Sergei V; Xu, Yao; Stafford, Walter F; Cox, Michael M; Inman, Ross B; Johnson, Carl H

2002-12-24

KaiC from Synechococcus elongatus PCC 7942 (KaiC) is an essential circadian clock protein in cyanobacteria. Previous sequence analyses suggested its inclusion in the RecADnaB superfamily. A characteristic of the proteins of this superfamily is that they form homohexameric complexes that bind DNA. We show here that KaiC also forms ring complexes with a central pore that can be visualized by electron microscopy. A combination of analytical ultracentrifugation and chromatographic analyses demonstrates that these complexes are hexameric. The association of KaiC molecules into hexamers depends on the presence of ATP. The KaiC sequence does not include the obvious DNA-binding motifs found in RecA or DnaB. Nevertheless, KaiC binds forked DNA substrates. These data support the inclusion of KaiC into the RecADnaB superfamily and have important implications for enzymatic activity of KaiC in the circadian clock mechanism that regulates global changes in gene expression patterns.

Enhancing the light-driven production of D-lactate by engineering cyanobacterium using a combinational strategy

Science.gov (United States)

Li, Chao; Tao, Fei; Ni, Jun; Wang, Yu; Yao, Feng; Xu, Ping

2015-05-01

It is increasingly attractive to engineer cyanobacteria for bulk production of chemicals from CO2. However, cofactor bias of cyanobacteria is different from bacteria that prefer NADH, which hampers cyanobacterial strain engineering. In this study, the key enzyme D-lactate dehydrogenase (LdhD) from Lactobacillus bulgaricus ATCC11842 was engineered to reverse its favored cofactor from NADH to NADPH. Then, the engineered enzyme was introduced into Synechococcus elongatus PCC7942 to construct an efficient light-driven system that produces D-lactic acid from CO2. Mutation of LdhD drove a fundamental shift in cofactor preference towards NADPH, and increased D-lactate productivity by over 3.6-fold. We further demonstrated that introduction of a lactic acid transporter and bubbling CO2-enriched air also enhanced D-lactate productivity. Using this combinational strategy, increased D-lactate concentration and productivity were achieved. The present strategy may also be used to engineer cyanobacteria for producing other useful chemicals.

Optimization of isopropanol production by engineered cyanobacteria with a synthetic metabolic pathway.

Science.gov (United States)

Hirokawa, Yasutaka; Suzuki, Iwane; Hanai, Taizo

2015-05-01

Cyanobacterium is an attractive host for the production of various chemicals and alternative fuels using solar energy and carbon dioxide. In previous study, we succeeded to produce isopropanol using engineered Synechococcus elongatus PCC 7942 under dark and anaerobic conditions (0.43 mM, 26.5 mg/l). In the present study, we report the further optimization of this isopropanol producing condition. We then optimized growth conditions for production of isopropanol by the engineered cyanobacteria, including the use of cells in early stationary phase and buffering of the production medium to neutral pH. We observed that shifting of cultures from dark and anaerobic to light and aerobic conditions during the production phase dramatically increased isopropanol production by conversion to isopropanol from acetate, byproduct under dark and anaerobic condition. Under the optimized production conditions, the titer of isopropanol was elevated 6-fold, to 2.42 mM (146 mg/l). Copyright © 2014 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Engineering an Obligate Photoautotrophic Cyanobacterium to Utilize Glycerol for Growth and Chemical Production.

Science.gov (United States)

Kanno, Masahiro; Atsumi, Shota

2017-01-20

Cyanobacteria have attracted much attention as a means to directly recycle carbon dioxide into valuable chemicals that are currently produced from petroleum. However, the titers and productivities achieved are still far below the level required in industry. To make a more industrially applicable production scheme, glycerol, a byproduct of biodiesel production, can be used as an additional carbon source for photomixotrophic chemical production. Glycerol is an ideal candidate due to its availability and low cost. In this study, we found that a heterologous glycerol respiratory pathway enabled Synechococcus elongatus PCC 7942 to utilize extracellular glycerol. The engineered strain produced 761 mg/L of 2,3-butanediol in 48 h with a 290% increase over the control strain under continuous light conditions. Glycerol supplementation also allowed for continuous cell growth and 2,3-butanediol production in diurnal light conditions. These results highlight the potential of glycerol as an additional carbon source for photomixotrophic chemical production in cyanobacteria.

studies on trace metal concentration pseudotolithus elongatus from ...

African Journals Online (AJOL)

DJFLEX

KEY WORDS: Trace metals, Lead Pollution, Pseudotolithus elongatus, Mbo coastal waters, ..... Analysis of soil heavy metal pollution and ... Pekey, H., Karakas, D., and Bakog'lu, M., 2004. Source apportionment of trace metals in the surface.

Physiological tolerance and stoichiometric potential of cyanobacteria for hydrocarbon fuel production.

Science.gov (United States)

Kämäräinen, Jari; Knoop, Henning; Stanford, Natalie J; Guerrero, Fernando; Akhtar, M Kalim; Aro, Eva-Mari; Steuer, Ralf; Jones, Patrik R

2012-11-30

Cyanobacteria are capable of directly converting sunlight, carbon dioxide and water into hydrocarbon fuel or precursors thereof. Many biological and non-biological factors will influence the ability of such a production system to become economically sustainable. We evaluated two factors in engineerable cyanobacteria which could potentially limit economic sustainability: (i) tolerance of the host to the intended end-product, and (ii) stoichiometric potential for production. Alcohols, when externally added, inhibited growth the most, followed by aldehydes and acids, whilst alkanes were the least inhibitory. The growth inhibition became progressively greater with increasing chain-length for alcohols, whilst the intermediate C6 alkane caused more inhibition than both C3 and C11 alkane. Synechocystis sp. PCC 6803 was more tolerant to some of the tested chemicals than Synechococcus elongatus PCC 7942, particularly ethanol and undecane. Stoichiometric evaluation of the potential yields suggested that there is no difference in the potential productivity of harvestable energy between any of the studied fuels, with the exception of ethylene, for which maximal stoichiometric yield is considerably lower. In summary, it was concluded that alkanes would constitute the best choice metabolic end-product for fuel production using cyanobacteria if high-yielding strains can be developed. Copyright © 2012 Elsevier B.V. All rights reserved.

Factors controlling the temporal and spatial variations in Synechococcus abundance in a monsoonal estuary

Digital Repository Service at National Institute of Oceanography (India)

Rajaneesh, K.M.; Mitbavkar, S.

salinity preferences with phycoerythrin-rich cells at salinities >2 (Synechococcus-PEI), >20 (Synechococcus-PEII) and <1 (Synechococcus-PEIII) whereas phycocyanin-rich (Synechococcus-PC) dominant at lower salinities. Downstream stratification during monsoon...

Nitrogen-Dependent Carbon Fixation by Picoplankton In Culture and in the Mississippi River

Energy Technology Data Exchange (ETDEWEB)

Aubrey Smith; Marguerite W. Coomes; Thomas E. Smith

2005-04-30

The pepc gene, which encodes phosphoenolpyruvate carboxylase (PEPC), of the marine cyanobacterium Synechococcus PCC 7002, was isolated and sequenced. PEPC is an anaplerotic enzyme, but it may also contribute to overall CO2 fixation through β-carboxylation reactions. A consensus sequence generated by aligning the pepc genes of Anabaena variabilis, Anacystis nidulans and Synechocystis PCC 6803 was used to design two sets of primers that were used to amplify segments of Synechococcus PCC 7002 pepc. In order to isolate the gene, the sequence of the PCR product was used to search for the pepc nucleotide sequence from the publicly available genome of Synechococcus PCC 7002. At the time, the genome for this organism had not been completed although sequences of a significant number of its fragments are available in public databases. Thus, the major challenge was to find the pepc gene among those fragments and to complete gaps as necessary. Even though the search did not yield the complete gene, PCR primers were designed to amplify a DNA fragment using a high fidelity thermostable DNA polymerase. An open reading frame (ORF) consisting of 2988 base pairs coding for 995 amino acids was found in the 3066 bp PCR product. The pepc gene had a GC content of 52% and the deduced protein had a calculated molecular mass of 114,049 Da. The amino acid sequence was closely related to that of PEPC from other cyanobacteria, exhibiting 59-61% identity. The sequence differed significantly from plant and E. coli PEPC with only 30% homology. However, comparing the Synechococcus PCC 7002 sequence to the recently resolved E. coli PEPC revealed that most of the essential domains and amino acids involved in PEPC activity were shared by both proteins. The recombinant Synechococcus PCC 7002 PEPC was expressed in E. coli.

Enzyme kinetics, inhibitors, mutagenesis and electron paramagnetic resonance analysis of dual-affinity nitrate reductase in unicellular N(2)-fixing cyanobacterium Cyanothece sp. PCC 8801.

Science.gov (United States)

Wang, Tung-Hei; Chen, Yung-Han; Huang, Jine-Yung; Liu, Kang-Cheng; Ke, Shyue-Chu; Chu, Hsiu-An

2011-11-01

The assimilatory nitrate reductase (NarB) of N(2)-fixing cyanobacterium Cyanothece sp. PCC 8801 is a monomeric enzyme with dual affinity for substrate nitrate. We purified the recombinant NarB of Cyanothece sp. PCC 8801 and further investigated it by enzyme kinetics analysis, site-directed mutagenesis, inhibitor kinetics analysis, and electron paramagnetic resonance (EPR) spectroscopy. The NarB showed 2 kinetic regimes at pH 10.5 or 8 and electron-donor conditions methyl viologen or ferredoxin (Fd). Fd-dependent NR assay revealed NarB with very high affinity for nitrate (K(m)1, ∼1μM; K(m)2, ∼270μM). Metal analysis and EPR results showed that NarB contains a Mo cofactor and a [4Fe-4S] cluster. In addition, the R352A mutation on the proposed nitrate-binding site of NarB greatly altered both high- and low-affinity kinetic components. Furthermore, the effect of azide on the NarB of Cyanothece sp. PCC 8801 was more complex than that on the NarB of Synechococcus sp. PCC 7942 with its single kinetic regime. With 1mM azide, the kinetics of the wild-type NarB was transformed from 2 kinetic regimes to hyperbolic kinetics, and its activity was enhanced significantly under medium nitrate concentrations. Moreover, EPR results also suggested a structural difference between the two NarBs. Taken together, our results show that the NarB of Cyanothece sp. PCC 8801 contains only a single Mo-catalytic center, and we rule out that the enzyme has 2 independent, distinct catalytic sites. In addition, the NarB of Cyanothece sp. PCC 8801 may have a regulatory nitrate-binding site. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

Synechococcus in the Atlantic gateway to the Arctic Ocean

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Maria Lund Paulsen

2016-10-01

Full Text Available Increasing temperatures, with pronounced effects at high latitudes, have raised questions about potential changes in species composition, as well as possible increased importance of small-celled phytoplankton in marine systems. In this study, we mapped out one of the smallest and globally most widespread primary producers, the picocyanobacterium Synechococcus, within the Atlantic inflow to the Arctic Ocean. In contrast to the general understanding that Synechococcus is almost absent in polar oceans due to low temperatures, we encountered high abundances (up to 21,000 cells mL-1 at 79 °N, and documented their presence as far north as 82.5 °N. Covering an annual cycle in 2014, we found that during autumn and winter, Synechococcus was often more abundant than picoeukaryotes, which usually dominate the picophytoplankton communities in the Arctic. Synechococcus community composition shifted from a quite high genetic diversity during the spring bloom to a clear dominance of two specific operational taxonomic units (OTUs in autumn and winter. We observed abundances higher than 1,000 cells mL-1 in water colder than 2 °C at seven distinct stations and size-fractionation experiments demonstrated a net growth of Synechococcus at 2 °C in the absence of nano-sized grazers at certain periods of the year. Phylogenetic analysis of petB sequences demonstrated that these high latitude Synechococcus group within the previously described cold-adapted clades I and IV, but also contributed to unveil novel genetic diversity, especially within clade I.

Novel lineages of Prochlorococcus and Synechococcus in the global oceans.

Science.gov (United States)

Huang, Sijun; Wilhelm, Steven W; Harvey, H Rodger; Taylor, Karen; Jiao, Nianzhi; Chen, Feng

2012-02-01

Picocyanobacteria represented by Prochlorococcus and Synechococcus have an important role in oceanic carbon fixation and nutrient cycling. In this study, we compared the community composition of picocyanobacteria from diverse marine ecosystems ranging from estuary to open oceans, tropical to polar oceans and surface to deep water, based on the sequences of 16S-23S rRNA internal transcribed spacer (ITS). A total of 1339 ITS sequences recovered from 20 samples unveiled diverse and several previously unknown clades of Prochlorococcus and Synechococcus. Six high-light (HL)-adapted Prochlorococcus clades were identified, among which clade HLVI had not been described previously. Prochlorococcus clades HLIII, HLIV and HLV, detected in the Equatorial Pacific samples, could be related to the HNLC clades recently found in the high-nutrient, low-chlorophyll (HNLC), iron-depleted tropical oceans. At least four novel Synechococcus clades (out of six clades in total) in subcluster 5.3 were found in subtropical open oceans and the South China Sea. A niche partitioning with depth was observed in the Synechococcus subcluster 5.3. Members of Synechococcus subcluster 5.2 were dominant in the high-latitude waters (northern Bering Sea and Chukchi Sea), suggesting a possible cold-adaptation of some marine Synechococcus in this subcluster. A distinct shift of the picocyanobacterial community was observed from the Bering Sea to the Chukchi Sea, which reflected the change of water temperature. Our study demonstrates that oceanic systems contain a large pool of diverse picocyanobacteria, and further suggest that new genotypes or ecotypes of picocyanobacteria will continue to emerge, as microbial consortia are explored with advanced sequencing technology.

CRISPR-Cas9 for the genome engineering of cyanobacteria and succinate production.

Science.gov (United States)

Li, Hung; Shen, Claire R; Huang, Chun-Hung; Sung, Li-Yu; Wu, Meng-Ying; Hu, Yu-Chen

2016-11-01

Cyanobacteria hold promise as a cell factory for producing biofuels and bio-derived chemicals, but genome engineering of cyanobacteria such as Synechococcus elongatus PCC 7942 poses challenges because of their oligoploidy nature and long-term instability of the introduced gene. CRISPR-Cas9 is a newly developed RNA-guided genome editing system, yet its application for cyanobacteria engineering has yet to be reported. Here we demonstrated that CRISPR-Cas9 system can effectively trigger programmable double strand break (DSB) at the chromosome of PCC 7942 and provoke cell death. With the co-transformation of template plasmid harboring the gene cassette and flanking homology arms, CRISPR-Cas9-mediated DSB enabled precise gene integration, ameliorated the homologous recombination efficiency and allowed the use of lower amount of template DNA and shorter homology arms. The CRISPR-Cas9-induced cell death imposed selective pressure and enhanced the chance of concomitant integration of gene cassettes into all chromosomes of PCC 7942, hence accelerating the process of obtaining homogeneous and stable recombinant strains. We further explored the feasibility of engineering cyanobacteria by CRISPR-Cas9-assisted simultaneous glgc knock-out and gltA/ppc knock-in, which improved the succinate titer to 435.0±35.0μg/L, an ≈11-fold increase when compared with that of the wild-type cells. These data altogether justify the use of CRISPR-Cas9 for genome engineering and manipulation of metabolic pathways in cyanobacteria. Copyright © 2016 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

Heterochromatin analysis in the fish species Liposarcus anisitsi (siluriformes and Leporinus elongatus (characiformes

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Roberto Ferreira Artoni

1999-03-01

Full Text Available The chromosomes of two neotropical freshwater fish species, namely Liposarcus anisitsi (Siluriformes, Loricariidae and Leporinus elongatus (Characiformes, Anostomidae, were investigated by means of C-banding, Ag-NORs, fluorochrome staining and banding by hot saline solution (HSS treatment, to reveal patterns of heterochromatin differentiation. The karyotype of L. anisitsi is described for the first time. Staining with the GC-specific fluorescent antibiotic mithramycin (MM revealed bright signals in some C-banded blocks in both species, suggesting that these MM+ heterochromatin contains GC-rich DNA. Banding by denaturation employing HSS, followed by Giemsa staining, yielded corresponding results documenting the thermal stability of GC-rich DNA part of heterochromatin positive after C-banding. In L. elongatus the Ag-NOR also followed the above banding patterns. However, in L. anisitsi the Ag-NOR was MM+ but negatively stained after C-banding and HSS treatment. L. elongatus also showed C-banded segments that were negative for mithramycin staining and HSS treatment. The results obtained evidence the heterochromatin heterogeneity in these fish species.Cromossomos mitóticos de duas especies de peixes neotropicais, Leporinus elongatus (Characiformes e Liposarcus anisitsi (Siluriformes, foram estudados por diferentes métodos de bandamentos, com o intuito de investigar a diferenciação da heterocromatina. Enquanto que a macroestrutura cariotípica de L. elongatus já foi objeto de estudos anteriores, o cariótipo de L. anisitsi está sendo apresentado pela primeira vez. Em ambas as espécies, a coloração dos cromossomos com a mitramicina (MM, fluorocromo GC específico, evidenciou sinais brilhantes em alguns segmentos heterocromáticos também positivos ao bandamento C, sugerindo ser esta fração da heterocromatina rica em seqüências de bases GC. O tratamento dos cromossomos com solução salina aquecida e posterior coloração com Giemsa

ORF Alignment: NC_006576 [GENIUS II[Archive

Lifescience Database Archive (English)

Full Text Available occus ... elongatus PCC 6301] ... Length = 168 ... Query: 361 RTIAERQRAIILRSDAVRKHLAGISLLERGGPEIY...SPEMSDRTXXXXXXXXXXXXXXXXX 420 ... RTIAERQRAIILRSDAVRKHLAGISLLERGGPEIYSPEMS...DRT ... Sbjct: 17 ... RTIAERQRAIILRSDAVRKHLAGISLLERGGPEIYSPEMSDRTYGRLLYLGLGLAQAGYR 76 ... Query: 481

Cyanobacterial defense mechanisms against foreign DNA transfer and their impact on genetic engineering

Directory of Open Access Journals (Sweden)

Karina Stucken

2013-01-01

Full Text Available Cyanobacteria display a large diversity of cellular forms ranging from unicellular to complex multicellular filaments or aggregates. Species in the group present a wide range of metabolic characteristics including the fixation of atmospheric nitrogen, resistance to extreme environments, production of hydrogen, secondary metabolites and exopolysaccharides. These characteristics led to the growing interest in cyanobacteria across the fields of ecology, evolution, cell biology and biotechnology. The number of available cyanobacterial genome sequences has increased considerably in recent years, with more than 140 fully sequenced genomes to date. Genetic engineering of cyanobacteria is widely applied to the model unicellular strains Synechocystis sp. PCC 6803 and Synechococcus elongatus PCC 7942. However the establishment of transformation protocols in many other cyanobacterial strains is challenging. One obstacle to the development of these novel model organisms is that many species have doubling times of 48 h or more, much longer than the bacterial models E. coli or B. subtilis. Furthermore, cyanobacterial defense mechanisms against foreign DNA pose a physical and biochemical barrier to DNA insertion in most strains. Here we review the various barriers to DNA uptake in the context of lateral gene transfer among microbes and the various mechanisms for DNA acquisition within the prokaryotic domain. Understanding the cyanobacterial defense mechanisms is expected to assist in the development and establishment of novel transformation protocols that are specifically suitable for this group.

Protein (Cyanobacteria): 52198 [PGDBj - Ortholog DB

Lifescience Database Archive (English)

Full Text Available 02412 Synechococcus sp. PCC 7502 MKLTPYLFLTITVTAIIGTSVWQSSAQMNKMMNHNMDEMSMELGAADANLDLRFIDAMIPHHQGAVQMAKEALKK...SKRPEIQKLATAIIKAQQEEIAQLQKWRKLWYPNMSSTPMAWHGEMGHMMTMSASQQKAMMMSMDLGAGDAKFDLRFIDAMIPHHEGALTMAQEALSKSKRPEIQKLAKAIITSQKAEIIEMQKWRKAWY ...

Reproductive biology of the Del Norte salamander (Plethodon elongatus).

Science.gov (United States)

Clara A. Wheeler; Hartwell H. Welsh Jr.; Lisa M. Ollivier

2013-01-01

We examined seasonal reproductive patterns of the Del Norte Salamander, Plethodon elongatus, in mixed conifer and hardwood forests of northwestern California and southwestern Oregon. Seasonal size differences in reproductive structures suggested that maximum spermatogenic activity occurred during the late summer, with spermatozoa transfer to the...

PCC/SRC, PCC and SRC Calculation from Multivariate Input for Sensitivity Analysis

International Nuclear Information System (INIS)

Iman, R.L.; Shortencarier, M.J.; Johnson, J.D.

1995-01-01

1 - Description of program or function: PCC/SRC is designed for use in conjunction with sensitivity analyses of complex computer models. PCC/SRC calculates the partial correlation coefficients (PCC) and the standardized regression coefficients (SRC) from the multivariate input to, and output from, a computer model. 2 - Method of solution: PCC/SRC calculates the coefficients on either the original observations or on the ranks of the original observations. These coefficients provide alternative measures of the relative contribution (importance) of each of the various input variables to the observed variations in output. Relationships between the coefficients and differences in their interpretations are identified. If the computer model output has an associated time or spatial history, PCC/SRC will generate a graph of the coefficients over time or space for each input-variable, output- variable combination of interest, indicating the importance of each input value over time or space. 3 - Restrictions on the complexity of the problem - Maxima of: 100 observations, 100 different time steps or intervals between successive dependent variable readings, 50 independent variables (model input), 20 dependent variables (model output). 10 ordered triples specifying intervals between dependent variable readings

ORF Alignment: NC_006576 [GENIUS II[Archive

Lifescience Database Archive (English)

Full Text Available ccus ... elongatus PCC 6301] ... Length = 155 ... Query: 2 ... AKTASTMLALGTAAPDFALPDVVSGRTVQLADFSDR...AGLLVMFICQHCPFVKHVEEELAA 61 ... AKTASTMLALGTAAPDFALPDVVSGRTVQLADFSDRAGLLVM...FICQHCPFVKHVEEELAA Sbjct: 1 ... AKTASTMLALGTAAPDFALPDVVSGRTVQLADFSDRAGLLVMFICQHCPFVKHVEEELAA 60 ... Query: 122 DF

Protein (Cyanobacteria): 515895859 [PGDBj - Ortholog DB

Lifescience Database Archive (English)

Full Text Available 302 ... hypothetical protein Synechococcus sp. PCC 7336 MADRNESFTPQSCRHILSVEDCDGLRDHALGAPKYFIGRDIANDICLNSQFASRYHALLLRVPAEREGEYFYRLLDGDLEGKPSTNGLTVNGLKVSAHELHEGDEISFGPDAKATYRVECLSADAK

Cross-amplification of heterologous microsatellite markers in Rhamdia quelen and Leporinus elongatus

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Nelson Mauricio Lopera-Barrero

2016-02-01

Full Text Available Native fish species in Brazil are an asset in fish farming, but their natural stocks have been significantly reduced in recent years. To mitigate this negative impact, studies on fish conservation are being conducted and genetic tools for the discrimination of population parameters are increasingly achieving great importance. Current analysis evaluates a set of microsatellite heterologous primers in the jundiá (Rhamdia quelen and in the piapara (Leporinus elongatus. Samples from the caudal fin of 15 broodstock from each species were analyzed. DNA extraction was performed with NaCl protocol and the integrity of the extracted DNA was checked with agarose gel 1%. Twenty primers developed for Piaractus mesopotamicus, Colossoma macropomum, Prochilodus lineatus, Brycon opalinus and Oreochromis niloticus were evaluated. Cross amplification of four primers of the B. opalinus and P. lineatus species (BoM12, Pli43 and Pli60 in R. quelen and BoM2, Pli43 and Pli60 in L. elongatus was assessed. Primers of P. mesopotamicus, C. macropomum and O. niloticus showed no cross amplification in the two species analyzed. Results revealed the possibility of using the four amplified heterologous primers in genetic studies for R. quelen and L. elongatus.

Defining an additivity framework for mixture research in inducible whole-cell biosensors

DEFF Research Database (Denmark)

Martin-Betancor, K; Ritz, Christian; Fernández-Piñas, F

2015-01-01

A novel additivity framework for mixture effect modelling in the context of whole cell inducible biosensors has been mathematically developed and implemented in R. The proposed method is a multivariate extension of the effective dose (EDp) concept. Specifically, the extension accounts for differe......A novel additivity framework for mixture effect modelling in the context of whole cell inducible biosensors has been mathematically developed and implemented in R. The proposed method is a multivariate extension of the effective dose (EDp) concept. Specifically, the extension accounts...... for differential maximal effects among analytes and response inhibition beyond the maximum permissive concentrations. This allows a multivariate extension of Loewe additivity, enabling direct application in a biphasic dose-response framework. The proposed additivity definition was validated, and its applicability...... illustrated by studying the response of the cyanobacterial biosensor Synechococcus elongatus PCC 7942 pBG2120 to binary mixtures of Zn, Cu, Cd, Ag, Co and Hg. The novel method allowed by the first time to model complete dose-response profiles of an inducible whole cell biosensor to mixtures. In addition...

Photosynthetic functions of Synechococcus in the ocean microbiomes of diverse salinity and seasons.

Science.gov (United States)

Kim, Yihwan; Jeon, Jehyun; Kwak, Min Seok; Kim, Gwang Hoon; Koh, InSong; Rho, Mina

2018-01-01

Synechococcus is an important photosynthetic picoplankton in the temperate to tropical oceans. As a photosynthetic bacterium, Synechococcus has an efficient mechanism to adapt to the changes in salinity and light intensity. The analysis of the distributions and functions of such microorganisms in the ever changing river mouth environment, where freshwater and seawater mix, should help better understand their roles in the ecosystem. Toward this objective, we have collected and sequenced the ocean microbiome in the river mouth of Kwangyang Bay, Korea, as a function of salinity and temperature. In conjunction with comparative genomics approaches using the sequenced genomes of a wide phylogeny of Synechococcus, the ocean microbiome was analyzed in terms of their composition and clade-specific functions. The results showed significant differences in the compositions of Synechococcus sampled in different seasons. The photosynthetic functions in such enhanced Synechococcus strains were also observed in the microbiomes in summer, which is significantly different from those in other seasons.

Variation of Synechococcus Pigment Genetic Diversity Along Two Turbidity Gradients in the China Seas.

Science.gov (United States)

Xia, Xiaomin; Liu, Hongbin; Choi, Donghan; Noh, Jae Hoon

2018-01-01

Synechococcus are important and widely distributed picocyanobacteria that encompass a high pigment diversity. In this study, we developed a primer set (peBF/peAR) for amplifying the cpeBA operon sequence from Synechococcus genomic DNA to study Synechococcus pigment diversity along two turbidity gradients in the China seas. Our data revealed that all previously reported pigment types occurred in the South (SCS) and East (ECS) China Seas. In addition, a novel pigment genetic type (type 3f), represented by the high phycourobilin Synechococcus sp. strain KORDI-100 (Exc495:545 = 2.35), was detected. This pigment genetic type differs from the 3c/3d types not only for a very high PUB/PEB ratio but also for a different intergenic spacer sequence and gene organization of the phycobilisome. Synechococcus of different pigment types exhibited clear niche differentiation. Type 2 dominated in the coastal waters, whereas type 3c/3d and 3f were predominant in oceanic waters of the SCS in summer. In the ECS, however, type 3a was the major pigment type throughout the transect. We suggest that in marine environment, various pigment types often co-occur but with one type dominant and PUB/PEB ratio is related to geographic distribution of Synechococcus pigment types. The two marginal seas of China have markedly different Synechococcus pigment compositions.

Taxonomy Icon Data: Synechocystis sp.PCC 6803 [Taxonomy Icon

Lifescience Database Archive (English)

Full Text Available Synechocystis sp.PCC 6803 Synechocystis sp.PCC 6803 Synechocystis_sp_PCC_6803_L.png Synecho...cystis_sp_PCC_6803_NL.png Synechocystis_sp_PCC_6803_S.png Synechocystis_sp_PCC_6803_NS.png http://bi...osciencedbc.jp/taxonomy_icon/icon.cgi?i=Synechocystis+sp%2ePCC+6803&t=L http://biosciencedbc.jp/taxonomy_icon/icon.cgi?i=Synecho...cystis+sp%2ePCC+6803&t=NL http://biosciencedbc.jp/taxonomy_icon/icon.cgi?i=Synecho...cystis+sp%2ePCC+6803&t=S http://biosciencedbc.jp/taxonomy_icon/icon.cgi?i=Synechocystis

Biochemical Validation of the Glyoxylate Cycle in the Cyanobacterium Chlorogloeopsis fritschii Strain PCC 9212.

Science.gov (United States)

Zhang, Shuyi; Bryant, Donald A

2015-05-29

Cyanobacteria are important photoautotrophic bacteria with extensive but variable metabolic capacities. The existence of the glyoxylate cycle, a variant of the TCA cycle, is still poorly documented in cyanobacteria. Previous studies reported the activities of isocitrate lyase and malate synthase, the key enzymes of the glyoxylate cycle in some cyanobacteria, but other studies concluded that these enzymes are missing. In this study the genes encoding isocitrate lyase and malate synthase from Chlorogloeopsis fritschii PCC 9212 were identified, and the recombinant enzymes were biochemically characterized. Consistent with the presence of the enzymes of the glyoxylate cycle, C. fritschii could assimilate acetate under both light and dark growth conditions. Transcript abundances for isocitrate lyase and malate synthase increased, and C. fritschii grew faster, when the growth medium was supplemented with acetate. Adding acetate to the growth medium also increased the yield of poly-3-hydroxybutyrate. When the genes encoding isocitrate lyase and malate synthase were expressed in Synechococcus sp. PCC 7002, the acetate assimilation capacity of the resulting strain was greater than that of wild type. Database searches showed that the genes for the glyoxylate cycle exist in only a few other cyanobacteria, all of which are able to fix nitrogen. This study demonstrates that the glyoxylate cycle exists in a few cyanobacteria, and that this pathway plays an important role in the assimilation of acetate for growth in one of those organisms. The glyoxylate cycle might play a role in coordinating carbon and nitrogen metabolism under conditions of nitrogen fixation. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

A Deg-protease family protein in marine Synechococcus is involved in outer membrane protein organization

Directory of Open Access Journals (Sweden)

Rhona Kayra Stuart

2014-06-01

Full Text Available Deg-family proteases are a periplasm-associated group of proteins that are known to be involved in envelope stress responses and are found in most microorganisms. Orthologous genes SYNW2176 (in strain WH8102 and sync_2523 (strain CC9311 are predicted members of the Deg-protease family and are among the few genes induced by copper stress in both open ocean and coastal marine Synechococcus strains. In contrast to the lack of a phenotype in a similar knockout in Synechocystis PCC6803, a SYNW2176 knockout mutant in strain WH8102 was much more resistant to copper than the wild-type. The mutant also exhibited a significantly altered outer membrane protein composition which may contribute to copper resistance, longer lag phase after transfer, low-level consistent alkaline phosphatase activity, and an inability to induce high alkaline phosphatase activity in response to phosphate stress. This phenotype suggests a protein-quality-control role for SYNW2176, the absence of which leads to a constitutively activated stress response. Deg-protease family proteins in this ecologically important cyanobacterial group thus help to determine outer membrane responses to both nutrients and toxins.

Production of volatile organic compounds by cyanobacteria Synechococcus sp.

Science.gov (United States)

Hiraiwa, M.; Abe, M.; Hashimoto, S.

2014-12-01

Phytoplankton are known to produce volatile organic compounds (VOCs), which contribute to environmental problems such as global warming and decomposition of stratospheric ozone. For example, picophytoplankton, such as Prochlorococcus and Synechococcus, are distributed in freshwater and oceans worldwide, accounting for a large proportion of biomass and primary production in the open ocean. However, to date, little is known about the production of VOCs by picophytoplankton. In this study, VOCs production by cyanobacteria Synechococcus sp. (NIES-981) was investigated. Synechococcus sp. was obtained from the National Institute for Environmental Studies (NIES), Japan, and cultured at 24°C in autoclaved f/2-Si medium under 54 ± 3 µE m-2 s-1 (1 E = 1 mol of photons) with a 12-h light and 12-h dark cycle. VOCs concentrations were determined using a purge-and-trap gas chromatograph-mass spectrometer (Agilent 5973). The concentrations of chlorophyll a (Chl a) were also determined using a fluorometer (Turner TD-700). Bromomethane (CH3Br) and isoprene were produced by Synechococcus sp. Isoprene production was similar to those of other phytoplankton species reported earlier. Isoprene was produced when Chl a was increasing in the early stage of the incubation period (5-15 days of incubation time, exponential phase), but CH3Br was produced when Chl a was reduced in the late stage of the incubation period (30-40 days of incubation time, death phase).

Genetic diversity and temporal variation of the marine Synechococcus community in the subtropical coastal waters of Hong Kong.

Science.gov (United States)

Jing, Hongmei; Zhang, Rui; Pointing, Stephen B; Liu, Hongbin; Qian, Peiyuan

2009-03-01

The phylogenetic diversity of the marine Synechococcus community in the subtropical coastal waters of Hong Kong, China, was examined through intergenic transcribed spacer clone libraries. All the sequences obtained fell within both marine cluster A (MC-A) and B (MC-B), with MC-A phylotypes dominating throughout the year. Distinct phylogenetic lineages specific to Hong Kong waters were detected from both MC-A and MC-B. The highest Synechococcus community diversity occurred in December, but the highest Synechococcus abundance occurred in August. On the other hand, both the abundance and diversity of Synechococcus showed a minimum in February. The remarkable seasonal variations of Synechococcus diversity observed were likely the result of the changes of hydrographic condition modulated by monsoons. Principal component analysis revealed that the in situ abiotic water characteristics, especially salinity and water turbidity, explained much of the variability of the marine Synechococcus population diversity in Hong Kong coastal waters. In addition, the temporal changes of Synechococcus abundance were largely driven by water temperature.

Determination of the glycogen content in cyanobacteria

DEFF Research Database (Denmark)

Porcellinis, Alice De; Frigaard, Niels-Ulrik; Sakuragi, Yumiko

2017-01-01

of glycogen to generate glucose monomers, which are detected by a glucose oxidase-peroxidase (GOD-POD) enzyme coupled assay. The method has been applied to Synechocystis sp. PCC 6803 and Synechococcus sp. PCC 7002, two model cyanobacterial species that are widely used in metabolic engineering. Moreover...

Unraveling the mechanism responsible for the contrasting tolerance of Synechocystis and Synechococcus to Cr(VI): Enzymatic and non-enzymatic antioxidants

Energy Technology Data Exchange (ETDEWEB)

Gupta, Alka [Molecular Biology Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Ballal, Anand, E-mail: aballal@barc.gov.in [Molecular Biology Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 40085 (India)

2015-07-15

Highlights: • Cr(VI) accumulation generates higher ROS in Synechocystis than in Synechococcus. • Synechococcus exhibits better photosynthetic activity in response to Cr(VI). • Synechococcus has higher enzymatic/non-enzymatic antioxidants than Synechocystis. • Synechococcus shows better tolerance to other oxidative stresses than Synechocystis. • Differential detoxification of ROS is responsible for the contrasting tolerance to Cr(VI) - Abstract: Two unicellular cyanobacteria, Synechocystis and Synechococcus, showed contrasting tolerance to Cr(VI); with Synechococcus being 12-fold more tolerant than Synechocystis to potassium dichromate. The mechanism responsible for this differential sensitivity to Cr(VI) was explored in this study. Total content of photosynthetic pigments as well as photosynthetic activity decreased at lower concentration of Cr(VI) in Synechocystis as compared to Synechococcus. Experiments with {sup 51}Cr showed Cr to accumulate intracellularly in both the cyanobacteria. At lower concentrations, Cr(VI) caused excessive ROS generation in Synechocystis as compared to that observed in Synechococcus. Intrinsic levels of enzymatic antioxidants, i.e., superoxide dismutase, catalase and 2-Cys-peroxiredoxin were considerably higher in Synechococcus than Synechocystis. Content of total thiols (both protein as well as non-protein) and reduced glutathione (GSH) was also higher in Synechococcus as compared to Synechocystis. This correlated well with higher content of carbonylated proteins observed in Synechocystis than Synechococcus. Additionally, in contrast to Synechocystis, Synechococcus exhibited better tolerance to other oxidative stresses like high intensity light and H{sub 2}O{sub 2}. The data indicate that the disparity in the ability to detoxify ROS could be the primary mechanism responsible for the differential tolerance of these cyanobacteria to Cr(VI)

Enhanced limonene production in cyanobacteria reveals photosynthesis limitations.

Science.gov (United States)

Wang, Xin; Liu, Wei; Xin, Changpeng; Zheng, Yi; Cheng, Yanbing; Sun, Su; Li, Runze; Zhu, Xin-Guang; Dai, Susie Y; Rentzepis, Peter M; Yuan, Joshua S

2016-12-13

Terpenes are the major secondary metabolites produced by plants, and have diverse industrial applications as pharmaceuticals, fragrance, solvents, and biofuels. Cyanobacteria are equipped with efficient carbon fixation mechanism, and are ideal cell factories to produce various fuel and chemical products. Past efforts to produce terpenes in photosynthetic organisms have gained only limited success. Here we engineered the cyanobacterium Synechococcus elongatus PCC 7942 to efficiently produce limonene through modeling guided study. Computational modeling of limonene flux in response to photosynthetic output has revealed the downstream terpene synthase as a key metabolic flux-controlling node in the MEP (2-C-methyl-d-erythritol 4-phosphate) pathway-derived terpene biosynthesis. By enhancing the downstream limonene carbon sink, we achieved over 100-fold increase in limonene productivity, in contrast to the marginal increase achieved through stepwise metabolic engineering. The establishment of a strong limonene flux revealed potential synergy between photosynthate output and terpene biosynthesis, leading to enhanced carbon flux into the MEP pathway. Moreover, we show that enhanced limonene flux would lead to NADPH accumulation, and slow down photosynthesis electron flow. Fine-tuning ATP/NADPH toward terpene biosynthesis could be a key parameter to adapt photosynthesis to support biofuel/bioproduct production in cyanobacteria.

Delineating Substrate Diversity of Disparate Short-Chain Dehydrogenase Reductase from Debaryomyces hansenii.

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Arindam Ghatak

Full Text Available Short-chain dehydrogenase reductases (SDRs have been utilized for catalyzing the reduction of many aromatic/aliphatic prochiral ketones to their respective alcohols. However, there is a paucity of data that elucidates their innate biological role and diverse substrate space. In this study, we executed an in-depth biochemical characterization and substrate space mapping (with 278 prochiral ketones of an unannotated SDR (DHK from Debaryomyces hansenii and compared it with structurally and functionally characterized SDR Synechococcus elongatus. PCC 7942 FabG to delineate its industrial significance. It was observed that DHK was significantly more efficient than FabG, reducing a diverse set of ketones albeit at higher conversion rates. Comparison of the FabG structure with a homology model of DHK and a docking of substrate to both structures revealed the presence of additional flexible loops near the substrate binding site of DHK. The comparative elasticity of the cofactor and substrate binding site of FabG and DHK was experimentally substantiated using differential scanning fluorimetry. It is postulated that the loop flexibility may account for the superior catalytic efficiency of DHK although the positioning of the catalytic triad is conserved.

Genetic diversity and distribution of periphytic Synechococcus spp. in biofilms and picoplankton of Lake Constance

NARCIS (Netherlands)

Becker, S.; Singh, A.K.; Postius, C.; Böger, P.; Ernst, A.

2004-01-01

In various water depths of the littoral zone of Lake Constance (Bodensee) cyanobacteria of the Synechococcus-type were isolated from biofilms (periphyton) on three natural substrates and an artificial one (unglazed tiles). From one tile three strains of phycoerythrin (PE)-rich Synechococcus spp.

Novel Synechococcus genomes reconstructed from freshwater reservoirs

Czech Academy of Sciences Publication Activity Database

Cabello-Yeves, P.J.; Haro-Moreno, J.M.; Martin-Cuadrado, A.B.; Ghai, Rohit; Picazo, A.; Camacho, A.; Rodriguez-Valera, F.

2017-01-01

Roč. 8, June (2017), č. článku 1151. ISSN 1664-302X R&D Projects: GA ČR(CZ) GA17-04828S Institutional support: RVO:60077344 Keywords : Synechococcus * picocyanobacteria * freshwater reservoirs * metagenomics * abundance Subject RIV: EE - Microbiology, Virology OBOR OECD: Microbiology Impact factor: 4.076, year: 2016

Species-specific differences of the spectroscopic properties of P700 - Analysis of the influence of non-conserved amino acid residues by site-directed mutagenesis of photosystem I from Chlamydomonas reinhardtii

NARCIS (Netherlands)

Witt, H.; Bordignon, E.; Carbonera, D.; Dekker, J.P.; Karapetyan, N.; Teutloff, C.; Webber, A.; Lubitz, W.; Schlodder, E.

2003-01-01

We applied optical spectroscopy, magnetic resonance techniques, and redox titrations to investigate the properties of the primary electron donor P700 in photosystem I (PS I) core complexes from cyanobacteria (Thermosynechococcus elongatus, Spirulina platensis, and Synechocystis sp. PCC 6803), algae

A numerical investigation of phytoplankton and Pseudocalanus elongatus dynamics in the spring bloom time in the Gdańsk Gulf

Science.gov (United States)

Dzierzbicka-Głowacka, Lidia

2005-01-01

A nutrient-phytoplankton-zooplankton-detritus (1D-NPZD) `phytoplankton {Phyt} and Pseudocalanus elongatus {Zoop} dynamics in the spring bloom time in the Gdańsk Gulf. The 1D-NPZD model consists of three coupled, partial second-order differential equations of the diffusion type for phytoplankton {Phyt}, zooplankton {Zoop}, nutrients {Nutr} and one ordinary first-order differential equation for benthic detritus pool {Detr}, together with initial and boundary conditions. In this model, the {Zoop} is presented by only one species of copepod ( P. elongatus) and {Zoop} is composed of six cohorts of copepods with weights ( Wi) and numbers ( Zi); where Zoop= limit∑i=16W iZ i. The calculations were made for 90 days (March, April, May) for two stations at Gdańsk Gulf with a vertical space step of 0.5m and a time step of 900 s. The flow field and water temperature used as the inputs in the biological model 1D-NPZD were reproduced by the prognostic numerical simulation technique using hydrographic climatological data. The results of the numerical investigations described here were compared with the mean observed values of surface chlorophyll- a and depth integrated P. elongatus biomass for 10 years, 1980-1990. The slight differences between the calculated and mean observed values of surface chlorophyll- a and zooplankton biomass are ca. 10-60 mg C m -3 and ca. 5-23 mg C m -2, respectively, depending on the location of the hydrographic station. The 1D-NPZD model with a high-resolution zooplankton module for P. elongatus can be used to describe the temporal patterns for phytoplankton biomass and P. elongatus in the centre of the Gdańsk Gulf.

Co-occurring Synechococcus ecotypes occupy four major oceanic regimes defined by temperature, macronutrients and iron.

Science.gov (United States)

Sohm, Jill A; Ahlgren, Nathan A; Thomson, Zachary J; Williams, Cheryl; Moffett, James W; Saito, Mak A; Webb, Eric A; Rocap, Gabrielle

2016-02-01

Marine picocyanobacteria, comprised of the genera Synechococcus and Prochlorococcus, are the most abundant and widespread primary producers in the ocean. More than 20 genetically distinct clades of marine Synechococcus have been identified, but their physiology and biogeography are not as thoroughly characterized as those of Prochlorococcus. Using clade-specific qPCR primers, we measured the abundance of 10 Synechococcus clades at 92 locations in surface waters of the Atlantic and Pacific Oceans. We found that Synechococcus partition the ocean into four distinct regimes distinguished by temperature, macronutrients and iron availability. Clades I and IV were prevalent in colder, mesotrophic waters; clades II, III and X dominated in the warm, oligotrophic open ocean; clades CRD1 and CRD2 were restricted to sites with low iron availability; and clades XV and XVI were only found in transitional waters at the edges of the other biomes. Overall, clade II was the most ubiquitous clade investigated and was the dominant clade in the largest biome, the oligotrophic open ocean. Co-occurring clades that occupy the same regime belong to distinct evolutionary lineages within Synechococcus, indicating that multiple ecotypes have evolved independently to occupy similar niches and represent examples of parallel evolution. We speculate that parallel evolution of ecotypes may be a common feature of diverse marine microbial communities that contributes to functional redundancy and the potential for resiliency.

The distribution of exocrine glands in Lepeophtheirus salmonis and Caligus elongatus (Copepoda: Caligidae)

NARCIS (Netherlands)

Bell, S.; Bron, J.E.; Sommerville, C.

2000-01-01

The morphology, function and distribution of exocrine glands of copepods have rarely been studied in detail and almost nothing is known about them in the sea lice species L. salmonis and C. elongatus. This study utilised a novel application of a light-microscopy staining technique to reveal a

Diurnal variability of Synechococcus abundance in Sagami Bay, Japan

Digital Repository Service at National Institute of Oceanography (India)

Mitbavkar, S.; Saino, T.

Synechococcus, the most dominant picophytoplankton in coastal regions, exhibits diurnal variations in the open ocean. The aim of this study was to assess its short-term population dynamics and cell cycle phases through DNA analysis in a coastal...

Lego clocks: building a clock from parts.

Science.gov (United States)

Brunner, Michael; Simons, Mirre J P; Merrow, Martha

2008-06-01

A new finding opens up speculation that the molecular mechanism of circadian clocks in Synechococcus elongatus is composed of multiple oscillator systems (Kitayama and colleagues, this issue, pp. 1513-1521), as has been described in many eukaryotic clock model systems. However, an alternative intepretation is that the pacemaker mechanism-as previously suggested-lies primarily in the rate of ATP hydrolysis by the clock protein KaiC.

Phylogeography and pigment type diversity of Synechococcus cyanobacteria in surface waters of the northwestern pacific ocean.

Science.gov (United States)

Xia, Xiaomin; Partensky, Frédéric; Garczarek, Laurence; Suzuki, Koji; Guo, Cui; Yan Cheung, Shun; Liu, Hongbin

2017-01-01

The widespread unicellular cyanobacteria Synechococcus are major contributors to global marine primary production. Here, we report their abundance, phylogenetic diversity (as assessed using the RNA polymerase gamma subunit gene rpoC1) and pigment diversity (as indirectly assessed using the laterally transferred cpeBA genes, encoding phycoerythrin-I) in surface waters of the northwestern Pacific Ocean, sampled over nine distinct cruises (2008-2015). Abundance of Synechococcus was low in the subarctic ocean and South China Sea, intermediate in the western subtropical Pacific Ocean, and the highest in the Japan and East China seas. Clades I and II were by far the most abundant Synechococcus lineages, the former dominating in temperate cold waters and the latter in (sub)tropical waters. Clades III and VI were also fairly abundant in warm waters, but with a narrower distribution than clade II. One type of chromatic acclimater (3dA) largely dominated the Synechococcus communities in the subarctic ocean, while another (3dB) and/or cells with a fixed high phycourobilin to phycoerythrobilin ratio (pigment type 3c) predominated at mid and low latitudes. Altogether, our results suggest that the variety of pigment content found in most Synechococcus clades considerably extends the niches that they can colonize and therefore the whole genus habitat. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

Identification and characterization of a carboxysomal γ-carbonic anhydrase from the cyanobacterium Nostoc sp. PCC 7120.

Science.gov (United States)

de Araujo, Charlotte; Arefeen, Dewan; Tadesse, Yohannes; Long, Benedict M; Price, G Dean; Rowlett, Roger S; Kimber, Matthew S; Espie, George S

2014-09-01

Carboxysomes are proteinaceous microcompartments that encapsulate carbonic anhydrase (CA) and ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco); carboxysomes, therefore, catalyze reversible HCO3 (-) dehydration and the subsequent fixation of CO2. The N- and C-terminal domains of the β-carboxysome scaffold protein CcmM participate in a network of protein-protein interactions that are essential for carboxysome biogenesis, organization, and function. The N-terminal domain of CcmM in the thermophile Thermosynechococcus elongatus BP-1 is also a catalytically active, redox regulated γ-CA. To experimentally determine if CcmM from a mesophilic cyanobacterium is active, we cloned, expressed and purified recombinant, full-length CcmM from Nostoc sp. PCC 7120 as well as the N-terminal 209 amino acid γ-CA-like domain. Both recombinant proteins displayed ethoxyzolamide-sensitive CA activity in mass spectrometric assays, as did the carboxysome-enriched TP fraction. NstCcmM209 was characterized as a moderately active and efficient γ-CA with a k cat of 2.0 × 10(4) s(-1) and k cat/K m of 4.1 × 10(6) M(-1) s(-1) at 25 °C and pH 8, a pH optimum between 8 and 9.5 and a temperature optimum spanning 25-35 °C. NstCcmM209 also catalyzed the hydrolysis of the CO2 analog carbonyl sulfide. Circular dichroism and intrinsic tryptophan fluorescence analysis demonstrated that NstCcmM209 was progressively and irreversibly denatured above 50 °C. NstCcmM209 activity was inhibited by the reducing agent tris(hydroxymethyl)phosphine, an effect that was fully reversed by a molar excess of diamide, a thiol oxidizing agent, consistent with oxidative activation being a universal regulatory mechanism of CcmM orthologs. Immunogold electron microscopy and Western blot analysis of TP pellets indicated that Rubisco and CcmM co-localize and are concentrated in Nostoc sp. PCC 7120 carboxysomes.

An evolutionary fitness enhancement conferred by the circadian system in cyanobacteria

International Nuclear Information System (INIS)

Ma, Peijun; Woelfle, Mark A.; Johnson, Carl Hirschie

2013-01-01

Circadian clocks are found in a wide variety of organisms from cyanobacteria to mammals. Many believe that the circadian clock system evolved as an adaption to the daily cycles in light and temperature driven by the rotation of the earth. Studies on the cyanobacterium, Synechococcus elongatus PCC 7942, have confirmed that the circadian clock in resonance with environmental cycles confers an adaptive advantage to cyanobacterial strains with different clock properties when grown in competition under light–dark cycles. The results thus far suggest that in a cyclic environment, the cyanobacterial strains whose free running periods are closest to the environmental period are the most fit and the strains lacking a functional circadian clock are at a competitive disadvantage relative to strains with a functional clock. In contrast, the circadian system provides little or no advantage to cyanobacteria grown in competition in constant light. To explain the potential mechanism of this clock-mediated enhancement in fitness in cyanobacteria, several models have been proposed; these include the limiting resource model, the diffusible inhibitor model and the cell-to-cell communication model. None of these models have been excluded by the currently available experimental data and the mechanistic basis of clock-mediated fitness enhancement remains elusive

Circadian Rhythms in Cyanobacteria

Science.gov (United States)

Golden, Susan S.

2015-01-01

SUMMARY Life on earth is subject to daily and predictable fluctuations in light intensity, temperature, and humidity created by rotation of the earth. Circadian rhythms, generated by a circadian clock, control temporal programs of cellular physiology to facilitate adaptation to daily environmental changes. Circadian rhythms are nearly ubiquitous and are found in both prokaryotic and eukaryotic organisms. Here we introduce the molecular mechanism of the circadian clock in the model cyanobacterium Synechococcus elongatus PCC 7942. We review the current understanding of the cyanobacterial clock, emphasizing recent work that has generated a more comprehensive understanding of how the circadian oscillator becomes synchronized with the external environment and how information from the oscillator is transmitted to generate rhythms of biological activity. These results have changed how we think about the clock, shifting away from a linear model to one in which the clock is viewed as an interactive network of multifunctional components that are integrated into the context of the cell in order to pace and reset the oscillator. We conclude with a discussion of how this basic timekeeping mechanism differs in other cyanobacterial species and how information gleaned from work in cyanobacteria can be translated to understanding rhythmic phenomena in other prokaryotic systems. PMID:26335718

Symbiotic adaptation drives genome streamlining of the cyanobacterial sponge symbiont "Candidatus Synechococcus pongiarum"

KAUST Repository

Gao, Zhao-Ming

2014-04-01

"Candidatus Synechococcus spongiarum" is a cyanobacterial symbiont widely distributed in sponges, but its functions at the genome level remain unknown. Here, we obtained the draft genome (1.66 Mbp, 90% estimated genome recovery) of "Ca. Synechococcus spongiarum" strain SH4 inhabiting the Red Sea sponge Carteriospongia foliascens. Phylogenomic analysis revealed a high dissimilarity between SH4 and free-living cyanobacterial strains. Essential functions, such as photosynthesis, the citric acid cycle, and DNA replication, were detected in SH4. Eukaryoticlike domains that play important roles in sponge-symbiont interactions were identified exclusively in the symbiont. However, SH4 could not biosynthesize methionine and polyamines and had lost partial genes encoding low-molecular-weight peptides of the photosynthesis complex, antioxidant enzymes, DNA repair enzymes, and proteins involved in resistance to environmental toxins and in biosynthesis of capsular and extracellular polysaccharides. These genetic modifications imply that "Ca. Synechococcus spongiarum" SH4 represents a low-light-adapted cyanobacterial symbiont and has undergone genome streamlining to adapt to the sponge\\'s mild intercellular environment. 2014 Gao et al.

Symbiotic adaptation drives genome streamlining of the cyanobacterial sponge symbiont "Candidatus Synechococcus pongiarum"

KAUST Repository

Gao, Zhao-Ming; Wang, Yong; Tian, Ren-Mao; Wong, Yue Him; Batang, Zenon B.; Al-Suwailem, Abdulaziz M.; Bajic, Vladimir B.; Qian, Pei-Yuan

2014-01-01

"Candidatus Synechococcus spongiarum" is a cyanobacterial symbiont widely distributed in sponges, but its functions at the genome level remain unknown. Here, we obtained the draft genome (1.66 Mbp, 90% estimated genome recovery) of "Ca. Synechococcus spongiarum" strain SH4 inhabiting the Red Sea sponge Carteriospongia foliascens. Phylogenomic analysis revealed a high dissimilarity between SH4 and free-living cyanobacterial strains. Essential functions, such as photosynthesis, the citric acid cycle, and DNA replication, were detected in SH4. Eukaryoticlike domains that play important roles in sponge-symbiont interactions were identified exclusively in the symbiont. However, SH4 could not biosynthesize methionine and polyamines and had lost partial genes encoding low-molecular-weight peptides of the photosynthesis complex, antioxidant enzymes, DNA repair enzymes, and proteins involved in resistance to environmental toxins and in biosynthesis of capsular and extracellular polysaccharides. These genetic modifications imply that "Ca. Synechococcus spongiarum" SH4 represents a low-light-adapted cyanobacterial symbiont and has undergone genome streamlining to adapt to the sponge's mild intercellular environment. 2014 Gao et al.

Phycoerythrin evolution and diversification of spectral phenotype in marine Synechococcus and related picocyanobacteria.

Science.gov (United States)

Everroad, R Craig; Wood, A Michelle

2012-09-01

In marine Synechococcus there is evidence for the adaptive evolution of spectrally distinct forms of the major light harvesting pigment phycoerythrin (PE). Recent research has suggested that these spectral forms of PE have a different evolutionary history than the core genome. However, a lack of explicit statistical testing of alternative hypotheses or for selection on these genes has made it difficult to evaluate the evolutionary relationships between spectral forms of PE or the role horizontal gene transfer (HGT) may have had in the adaptive phenotypic evolution of the pigment system in marine Synechococcus. In this work, PE phylogenies of picocyanobacteria with known spectral phenotypes, including newly co-isolated strains of marine Synechococcus from the Gulf of Mexico, were constructed to explore the diversification of spectral phenotype and PE evolution in this group more completely. For the first time, statistical evaluation of competing evolutionary hypotheses and tests for positive selection on the PE locus in picocyanobacteria were performed. Genes for PEs associated with specific PE spectral phenotypes formed strongly supported monophyletic clades within the PE tree with positive directional selection driving evolution towards higher phycourobilin (PUB) content. The presence of the PUB-lacking phenotype in PE-containing marine picocyanobacteria from cyanobacterial lineages identified as Cyanobium is best explained by HGT into this group from marine Synechococcus. Taken together, these data provide strong examples of adaptive evolution of a single phenotypic trait in bacteria via mutation, positive directional selection and horizontal gene transfer. Copyright © 2012 Elsevier Inc. All rights reserved.

Age validation and variation in growth, mortality and population structure of Liza argentea and Myxus elongatus (Mugilidae) in two temperate Australian estuaries.

Science.gov (United States)

Kendall, B W; Gray, C A; Bucher, D

2009-12-01

This study investigated variation in the rates of growth and mortality, and age and fork-length (L(F)) compositions of two exploited species of Mugilidae, Liza argentea and Myxus elongatus, in two south-east Australian estuaries (Lake Macquarie and St Georges Basin). An ageing protocol was developed by counting opaque growth zones on sectioned otoliths which was validated by periodically examining the otoliths of captive-reared young-of-the-year fishes, and marginal increment analysis of wild fishes. The maximum recorded age was 17 years for L. argentea and 12 years for M. elongatus, which is greater than generally observed in other species of mugilids. Growth models of each species significantly differed between sexes and, except for male L. argentea, between estuaries. Fishes from Lake Macquarie generally had a greater mean L(F) at age than those from St Georges Basin and females of both species generally attained a greater maximum L(F) and age than males. Gillnet catches of L. argentea were of similar L(F) and age compositions in both estuaries, whereas the age composition of catches of M. elongatus in Lake Macquarie contained a greater proportion of younger fish. Estimates of total, natural and fishing mortality were greater for M. elongatus than L. argentea across both estuaries, and estimates of total mortality were greatest for both species in Lake Macquarie. The data indicate that neither species has been overfished in these estuaries.

Development and application of the PCC biodosimetry method in emergency preparedness

Energy Technology Data Exchange (ETDEWEB)

Stricklin, D. (Swedish Defence Research Agency, FOI (Sweden)); Lindholm, C. (Finnish Radiation and Nuclear Safety Authority, STUK (Finland)); Jaworska, A. (Norwegian Radiation Protection Authority, NRPA (Norway))

2008-07-15

A method for biological assessment of radiation dose for specific application in emergency preparedness was developed. Premature chromosome condensation (PCC) was investigated to provide a potentially faster means of analysis and the ability to assess higher doses than with the dicentric assay which is routinely applied in biodosimetry today. A review of existing methods was made, followed by experiments determine optimal assay conditions, and evaluations to determination of optimal conditions and the most appropriate endpoints for analyses. Twelve different experimental conditions were examined with four different evaluation approaches. Aspects during optimization such as practicality, speed, and reliability were considered. The conclusion from these studies was a PCC protocol utilizing okadaic acid for induction of PCC cells in stimulated lymphocytes but without the use of colcemid for metaphase arrest with the subsequent evaluation of ring chromosomes. Well-defined criteria were established for evaluation of PCC cells and ring chromosome aberrations. An inter-calibration was made by comparing assessment of ring chromosomes between all three laboratories. Agreement was made to count only rings with observable open spaces or large, obvious rings without open spaces. Finally a dose response curve for the PCC method was prepared and a comparison of the PCC method to the traditional dicentric assay in triage mode was made. The triage method requires a minimal number of evaluations so that categorization of high, medium and low doses may be made in an emergency situation where large numbers of people should be evaluated. The comparison of the PCC method with the dicentric assay triage method indicated that the PCC assay performed superior to the dicentric assay for evaluation of samples at higher doses, however, the dicentric assay appeared to provide more accurate dose assessment at lower doses. This project suggests a PCC assay method for biological dose estimates

GC/MS analysis of piperidinocyclohexanecarbonitrile (PCC) smoking products

International Nuclear Information System (INIS)

Lue, L.P.; Scimeca, J.A.; Thomas, B.F.; Martin, B.R.

1986-01-01

Piperidinocyclohexanecarbonitrile (PCC), an intermediate in phencyclidine (PCP) synthesis, is a major contaminant of illicit PCP. Due to the frequent abuse of PCP by smoking, this study was conducted to determine the PCC pyrolysis products delivered in smoke. Marihuana placebo cigarettes were impregnated with 3 H-piperidino- 14 C-cyano-PCC (synthesized in the lab and recrystallized twice, m.p. 67 0 C) and burned under conditions which simulated smoking. Mainstream smoke was passed through glass wool filters and H 2 SO 4 and NaOH traps. Tritium and 14 C were recovered as 83%, and 56%, respectively, of the starting material. Seventy-six percent of the recovered tritium was found in the glass wool trap followed by 13, 7 and 4% in the acid trap, base trap and in the ash/unburned butt, respectively. Seventy-three percent of the recovered 14 C was found in the glass wool filter and 16 and 8% were found in the acid and base traps, respectively. GC/MS analysis revealed the presence of 1-piperidinocyclohexene (30%), PCC (24%), piperidine (7%), and 1-acetyl-piperidine (5%)

Removal of triazine herbicides from freshwater systems using photosynthetic microorganisms

International Nuclear Information System (INIS)

Gonzalez-Barreiro, O.; Rioboo, C.; Herrero, C.; Cid, A.

2006-01-01

The uptake of the triazine herbicides, atrazine and terbutryn, was determined for two freshwater photosynthetic microorganisms, the green microalga Chlorella vulgaris and the cyanobacterium Synechococcus elongatus. An extremely rapid uptake of both pesticides was recorded, although uptake rate was lower for the cyanobacterium, mainly for atrazine. Other parameters related to the herbicide bioconcentration capacity of these microorganisms were also studied. Growth rate, biomass, and cell viability in cultures containing herbicide were clearly affected by herbicide uptake. Herbicide toxicity and microalgae sensitivity were used to determine the effectiveness of the bioconcentration process and the stability of herbicide removal. C. vulgaris showed higher bioconcentration capability for these two triazine herbicides than S. elongatus, especially with regard to terbutryn. This study supports the usefulness of such microorganisms, as a bioremediation technique in freshwater systems polluted with triazine herbicides

Removal of triazine herbicides from freshwater systems using photosynthetic microorganisms

Energy Technology Data Exchange (ETDEWEB)

Gonzalez-Barreiro, O. [Laboratorio de Microbiologia, Facultad de Ciencias, Universidad de A Coruna, Campus da Zapateira s/n. 15071 A Coruna (Spain); Rioboo, C. [Laboratorio de Microbiologia, Facultad de Ciencias, Universidad de A Coruna, Campus da Zapateira s/n. 15071 A Coruna (Spain); Herrero, C. [Laboratorio de Microbiologia, Facultad de Ciencias, Universidad de A Coruna, Campus da Zapateira s/n. 15071 A Coruna (Spain); Cid, A. [Laboratorio de Microbiologia, Facultad de Ciencias, Universidad de A Coruna, Campus da Zapateira s/n. 15071 A Coruna (Spain)]. E-mail: cid@udc.es

2006-11-15

The uptake of the triazine herbicides, atrazine and terbutryn, was determined for two freshwater photosynthetic microorganisms, the green microalga Chlorella vulgaris and the cyanobacterium Synechococcus elongatus. An extremely rapid uptake of both pesticides was recorded, although uptake rate was lower for the cyanobacterium, mainly for atrazine. Other parameters related to the herbicide bioconcentration capacity of these microorganisms were also studied. Growth rate, biomass, and cell viability in cultures containing herbicide were clearly affected by herbicide uptake. Herbicide toxicity and microalgae sensitivity were used to determine the effectiveness of the bioconcentration process and the stability of herbicide removal. C. vulgaris showed higher bioconcentration capability for these two triazine herbicides than S. elongatus, especially with regard to terbutryn. This study supports the usefulness of such microorganisms, as a bioremediation technique in freshwater systems polluted with triazine herbicides.

Systems-Level Synthetic Biology for Advanced Biofuel Production

Energy Technology Data Exchange (ETDEWEB)

Ruffing, Anne [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jensen, Travis J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Strickland, Lucas Marshall [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Meserole, Stephen [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Tallant, David [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2015-03-01

Cyanobacteria have been shown to be capable of producing a variety of advanced biofuels; however, product yields remain well below those necessary for large scale production. New genetic tools and high throughput metabolic engineering techniques are needed to optimize cyanobacterial metabolisms for enhanced biofuel production. Towards this goal, this project advances the development of a multiple promoter replacement technique for systems-level optimization of gene expression in a model cyanobacterial host: Synechococcus sp. PCC 7002. To realize this multiple-target approach, key capabilities were developed, including a high throughput detection method for advanced biofuels, enhanced transformation efficiency, and genetic tools for Synechococcus sp. PCC 7002. Moreover, several additional obstacles were identified for realization of this multiple promoter replacement technique. The techniques and tools developed in this project will help to enable future efforts in the advancement of cyanobacterial biofuels.

Integration of DNA barcoding for the initial recordings of Lessepsian fishes: a case study of the Indo-Pacific slender ponyfish Equulites elongatus.

Science.gov (United States)

Sakinan, S; Karahan, A; Ok, M

2017-03-01

In this study, the DNA barcode of a regional Lessepsian sighting of the slender ponyfish Equulites elongatus is integrated with morphometric and meristic descriptors as a case study to address further identification problems in the Mediterranean Sea. The study also aims to contribute to the regional mitochondrial cytochrome oxidase I information pool, to support other potential uses. The initial sighting of E. elongatus from the north-eastern Mediterranean coast of Turkey is provided from a trawl survey on 3 June 2015, where 76 specimens were captured during a 15 min tow. © 2016 The Fisheries Society of the British Isles.

Anatomy and systematics of Anodontites Elongatus (Swainson from Amazon and Parana Basins, Brazil (Mollusca, Bivalvia, Unionoida, Mycetopodidae

Directory of Open Access Journals (Sweden)

Luiz Ricardo L Simone

1997-12-01

Full Text Available The anatomy of Anodontiies elongatus (Swainson, 1823, a rare species restricted to the Amazon and Parana Basins, is described by first time, showing a group of conchological and anatomical characters exclusive of this species that may be analyzed to identify it. Diagnosis of A. elongatus: shell long antero-posteriorly, umbones prominent, periostracum opaque and smooth, two posterior radial striae; middle fold of mantle edge veiy tall; gill long antero-posteriorly and short dorso-ventrally, extending about a half of it total length beyond visceral mass; palps proportionally small, several furrows in its outer surface; stomach without esophageal transversal ridjp, dorsal hood and gastric shield poorly developed, major typhlosole entering in ddd , posterior pouch of sa³ very-long; style sac reduced, without crystalline style; distal region of intestine and rectum with a well developed typhlosole, "T" in section, other intestinal regions without folds; gonad gonochoristic.

Two new species of the Liolaemus elongatus-kriegi complex (Iguania, Liolaemidae) from Andean highlands of southern Chile

Science.gov (United States)

Troncoso-Palacios, Jaime; Díaz, Hugo A.; Esquerré, Damien; Urra, Felix A.

2015-01-01

Abstract The elongatus-kriegi complex is one of the most diverse clades of the Liolaemus (sensu stricto) subgenus of lizards. There are currently 29 species recognized in this group distributed between Chile and Argentina. Based on molecular evidence, there seem to be five main clades nested within this complex: the elongatus, leopardinus, kriegi, petrophilus and punmahuida clades. Liolaemus buergeri and Liolaemus kriegi, both of the kriegi clade, were believed to inhabit the surroundings of the Laja Lagoon, in the Biobío Region of Chile. Moreover, this Chilean population of Liolaemus kriegi was recently recognized as an undescribed taxon called “Liolaemus sp. A” based on molecular phylogenetics. In this work, we studied these two populations of the Laja Lagoon and provided the morphological diagnosis to describe them as two new species: Liolaemus scorialis sp. n. and Liolaemus zabalai sp. n., previously considered Liolaemus buergeri and “Liolaemus kriegi/Liolaemus sp. A” respectively. Additionally, we identified another population of Liolaemus scorialis in the vicinity of La Mula Lagoon in the Araucanía Region of Chile. Liolaemus scorialis differs from almost all of the species of the elongatus-kriegi complex by its considerably smaller size. Nevertheless, without molecular data we cannot assign it to any particular subclade. Liolaemus zabalai belongs to the kriegi clade based on published molecular phylogenies. Finally, we provide some natural history data on both species and we document for the first time the presence of Liolaemus neuquensis in Chile from a museum specimen from La Mula Lagoon. PMID:25987873

An allele of the crm gene blocks cyanobacterial circadian rhythms.

Science.gov (United States)

Boyd, Joseph S; Bordowitz, Juliana R; Bree, Anna C; Golden, Susan S

2013-08-20

The SasA-RpaA two-component system constitutes a key output pathway of the cyanobacterial Kai circadian oscillator. To date, rhythm of phycobilisome associated (rpaA) is the only gene other than kaiA, kaiB, and kaiC, which encode the oscillator itself, whose mutation causes completely arrhythmic gene expression. Here we report a unique transposon insertion allele in a small ORF located immediately upstream of rpaA in Synechococcus elongatus PCC 7942 termed crm (for circadian rhythmicity modulator), which results in arrhythmic promoter activity but does not affect steady-state levels of RpaA. The crm ORF complements the defect when expressed in trans, but only if it can be translated, suggesting that crm encodes a small protein. The crm1 insertion allele phenotypes are distinct from those of an rpaA null; crm1 mutants are able to grow in a light:dark cycle and have no detectable oscillations of KaiC phosphorylation, whereas low-amplitude KaiC phosphorylation rhythms persist in the absence of RpaA. Levels of phosphorylated RpaA in vivo measured over time are significantly altered compared with WT in the crm1 mutant as well as in the absence of KaiC. Taken together, these results are consistent with the hypothesis that the Crm polypeptide modulates a circadian-specific activity of RpaA.

Population Dynamics and Diversity of Synechococcus on the New England Shelf

Science.gov (United States)

2014-09-01

Suzanne L Strom, Brian Palenik, and Bianca Brahamsha. Vari- ability in protist grazing and growth on different marine Synechococcus isolates. Applied...Ricardo Anadón. Protist control of phytoplankton growth in the subtropical north-east atlantic. Marine Ecology Progress Series, 221:29– 38, 2001. [86

Roseicyclus marinus sp. nov., isolated from a Synechococcus culture, and emended description of the genus Roseicyclus.

Science.gov (United States)

Tang, Lili; Zhang, Zenghu; Zhou, Chao; Cui, Rong; Tian, Yu; Zhang, Yongyu

2018-05-01

A novel Gram-stain-negative, aerobic, non-flagellated, pink-pigmented and rod-shaped strain with gliding motility, designated strain CCMM001 T , was isolated from a mixed culture of Synechococcus species PCC7002 and a natural bacterial community from a sample of offshore seawater from Qingdao, China, during September 2014. The strain contained bacteriochlorophyll a with a small peak at 802 nm and a large in vivo absorption band at 870 nm. Strain CCMM001 T grew optimally at pH 7.0 and 30 °C in the presence of 3 % (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain CCMM001 T is most closely related to the genus Roseicyclus and its type and only species Roseicyclus mahoneyensis ML6 T with 96.9 % sequence similarity. The polar lipids of strain CCMM001 T consisted of phosphatidylethanolamine, phosphatidylcholine, one unidentified aminolipid, and five unidentified lipids. The predominant isoprenoid quinone was Q-10. The major fatty acids included C18 : 1ω7c and C19 : 0cyclo ω8c. The DNA G+C content of strain CCMM001 T was 63.5 mol%. These phylogenetic, physiological and chemotaxonomic data indicated that strain CCMM001 T represents a novel species of the genus Roseicyclus, for which the name Roseicyclus marinus sp. nov. is proposed. The type strain is CCMM001 T (=MCCC 1K03242 T =KCTC 52641 T ).

Penggunaan precipitated calcium carbonate (PCC sebagai filler untuk sol karet sepatu olah raga

Directory of Open Access Journals (Sweden)

Herminiwati

2010-12-01

Full Text Available Abstract The objective of the research was to investigate the utilization of Precipitated Calcium Carbonate (PCC as filler in producing sport shoe rubber soles. PCC is a white filler needed for production of nonblack colour rubber products. There are four types of PCC that have been used including two local PCC from Wonosari and East Java, and two imported PCC from Japan and Taiwan. The amount of PCC added into the sport shoe sole rubber compound was varied in 30,45,60,75 and 90 per hundred rubber (phr. The compounding was carried-out by using two roll mills machine, and the compound was subsequently measured their optimum vulcanization time by using rheometer. The produced compound was then subjected to vulcanistion process by using hydrolic press at temperature 1500C and pressure 150 kg/ cm2. The quality of shoes sole vulcanisates were compare to standard quality of SNI. 12-7075-2005 about cemented system sport shoes. The results indicated that the best formula of rubber compound for sport shoes sole were made by using NR 80 phr, NBR 20 phr, paraffinic oil 10 phr, aluminium silicate 30 phr, ZnO 5 phr, TiO2 10 phr, stearic acid 1 phr, vulkanox SP 1 phr, paraffin wax 1 phr, TMTD 0,5 phr, CBS 2 phr, sulphur 1,2 phr with the amount of PCC Actifort 700 of 45 phr. The best formula meet the requirement SNI 12-7075-2005 and they were characterized by tensile sterength 16,79 N/mm2, elongation at break 529,92% tear resistance 9,06 N/mm2, specific gravity 1,28 g/cm3, hardness 55 shore A, Grasselli absrassion resistancing filler. The local PCC from Wonosari can be used for substitution of the imported PCC as the white filler for the production of rubber compound sport shoes sole. However, particle size reduction and coating or surface treatment of local PCC were needed for improving the quality and the role of reinforcing filler.

Seasonal changes in food quantity and quality of the common North Sea copepods Temora longicornis and Pseudocalanus elongatus: a bioassay approach

DEFF Research Database (Denmark)

Koski, Marja; Dutz, Jörg; Klein Breteler, W.

2010-01-01

We evaluated the food quantity and quality over a seasonal cycle for the development and egg production of the common North Sea copepods Temora longicornis and Pseudocalanus elongatus, using a bioassay approach. Seston was sampled from December to October from a well-mixed water column of the Mar......We evaluated the food quantity and quality over a seasonal cycle for the development and egg production of the common North Sea copepods Temora longicornis and Pseudocalanus elongatus, using a bioassay approach. Seston was sampled from December to October from a well-mixed water column...... with the seston from the spring bloom in March-April. The juveniles of both species were able to complete their development only in spring experiments. A multiple regression analyses and comparison to a good-quality standard food of the same concentration suggested that, in an annual scale, the egg production...

Phycoerythrin-specific bilin lyase-isomerase controls blue-green chromatic acclimation in marine Synechococcus.

Science.gov (United States)

Shukla, Animesh; Biswas, Avijit; Blot, Nicolas; Partensky, Frédéric; Karty, Jonathan A; Hammad, Loubna A; Garczarek, Laurence; Gutu, Andrian; Schluchter, Wendy M; Kehoe, David M

2012-12-04

The marine cyanobacterium Synechococcus is the second most abundant phytoplanktonic organism in the world's oceans. The ubiquity of this genus is in large part due to its use of a diverse set of photosynthetic light-harvesting pigments called phycobiliproteins, which allow it to efficiently exploit a wide range of light colors. Here we uncover a pivotal molecular mechanism underpinning a widespread response among marine Synechococcus cells known as "type IV chromatic acclimation" (CA4). During this process, the pigmentation of the two main phycobiliproteins of this organism, phycoerythrins I and II, is reversibly modified to match changes in the ambient light color so as to maximize photon capture for photosynthesis. CA4 involves the replacement of three molecules of the green light-absorbing chromophore phycoerythrobilin with an equivalent number of the blue light-absorbing chromophore phycourobilin when cells are shifted from green to blue light, and the reverse after a shift from blue to green light. We have identified and characterized MpeZ, an enzyme critical for CA4 in marine Synechococcus. MpeZ attaches phycoerythrobilin to cysteine-83 of the α-subunit of phycoerythrin II and isomerizes it to phycourobilin. mpeZ RNA is six times more abundant in blue light, suggesting that its proper regulation is critical for CA4. Furthermore, mpeZ mutants fail to normally acclimate in blue light. These findings provide insights into the molecular mechanisms controlling an ecologically important photosynthetic process and identify a unique class of phycoerythrin lyase/isomerases, which will further expand the already widespread use of phycoerythrin in biotechnology and cell biology applications.

Drug-induced premature chromosome condensation (PCC) protocols: cytogenetic approaches in mitotic chromosome and interphase chromatin.

Science.gov (United States)

Gotoh, Eisuke

2015-01-01

Chromosome analysis is a fundamental technique which is used in wide areas of cytogenetic study including karyotyping species, hereditary diseases diagnosis, or chromosome biology study. Chromosomes are usually prepared from mitotic cells arrested by colcemid block protocol. However, obtaining mitotic chromosomes is often hampered under several circumstances. As a result, cytogenetic analysis will be sometimes difficult or even impossible in such cases. Premature chromosome condensation (PCC) (see Note 1) is an alternative method that has proved to be a unique and useful way in chromosome analysis. Former, PCC has been achieved following cell fusion method (cell-fusion PCC) mediated either by fusogenic viruses (e.g., Sendai virus) or cell fusion chemicals (e.g., polyethylene glycol), but the cell fusion PCC has several drawbacks. The novel drug-induced PCC using protein phosphatase inhibitors was introduced about 20 years ago. This method is much simpler and easier even than the conventional mitotic chromosome preparation protocol use with colcemid block and furthermore obtained PCC index (equivalent to mitotic index for metaphase chromosome) is usually much higher than colcemid block method. Moreover, this method allows the interphase chromatin to be condensed to visualize like mitotic chromosomes. Therefore drug-induced PCC has opened the way for chromosome analysis not only in metaphase chromosomes but also in interphase chromatin. The drug-induced PCC has thus proven the usefulness in cytogenetics and other cell biology fields. For this second edition version, updated modifications/changes are supplemented in Subheadings 2, 3, and 4, and a new section describing the application of PCC in chromosome science fields is added with citation of updated references.

Inhibitory activities of microalgal extracts against Epstein-Barr Virus (EBV antigen expression in lymphoblastoid cells

Directory of Open Access Journals (Sweden)

Koh Yih Yih

2014-01-01

Full Text Available The inhibitory activities of microalgal extracts against the expression of three EBV antigens, latent membrane protein (LMP1, Epstein-Barr nuclear antigen (EBNA1 and Z Epstein-Barr reactivation activator (ZEBRA were assessed by immunocytochemistry. The observation that the methanol extracts and their fractions from Ankistrodesmus convolutus, Synechococcus elongatus and Spirulina platensis exhibited inhibitory activity against EBV proteins in three Burkitt’s lymphoma cell lines at concentrations as low as 20 μg/ml suggests that microalgae could be a potential source of antiviral compounds against EBV.

TetR Family Transcriptional Regulator PccD Negatively Controls Propionyl Coenzyme A Assimilation in Saccharopolyspora erythraea.

Science.gov (United States)

Xu, Zhen; Wang, Miaomiao; Ye, Bang-Ce

2017-10-15

Propanol stimulates erythromycin biosynthesis by increasing the supply of propionyl coenzyme A (propionyl-CoA), a starter unit of erythromycin production in Saccharopolyspora erythraea Propionyl-CoA is assimilated via propionyl-CoA carboxylase to methylmalonyl-CoA, an extender unit of erythromycin. We found that the addition of n -propanol or propionate caused a 4- to 16-fold increase in the transcriptional levels of the SACE_3398-3400 locus encoding propionyl-CoA carboxylase, a key enzyme in propionate metabolism. The regulator PccD was proved to be directly involved in the transcription regulation of the SACE_3398-3400 locus by EMSA and DNase I footprint analysis. The transcriptional levels of SACE_3398-3400 were upregulated 15- to 37-fold in the pccD gene deletion strain (Δ pccD ) and downregulated 3-fold in the pccD overexpression strain (WT/pIB- pccD ), indicating that PccD was a negative transcriptional regulator of SACE_3398-3400. The Δ pccD strain has a higher growth rate than that of the wild-type strain (WT) on Evans medium with propionate as the sole carbon source, whereas the growth of the WT/pIB- pccD strain was repressed. As a possible metabolite of propionate metabolism, methylmalonic acid was identified as an effector molecule of PccD and repressed its regulatory activity. A higher level of erythromycin in the Δ pccD strain was observed compared with that in the wild-type strain. Our study reveals a regulatory mechanism in propionate metabolism and suggests new possibilities for designing metabolic engineering to increase erythromycin yield. IMPORTANCE Our work has identified the novel regulator PccD that controls the expression of the gene for propionyl-CoA carboxylase, a key enzyme in propionyl-CoA assimilation in S. erythraea PccD represses the generation of methylmalonyl-CoA through carboxylation of propionyl-CoA and reveals an effect on biosynthesis of erythromycin. This finding provides novel insight into propionyl-CoA assimilation, and

Engineered Photosystem II reaction centers optimize photochemistry versus photoprotection at different solar intensities.

Science.gov (United States)

Vinyard, David J; Gimpel, Javier; Ananyev, Gennady M; Mayfield, Stephen P; Dismukes, G Charles

2014-03-12

The D1 protein of Photosystem II (PSII) provides most of the ligating amino acid residues for the Mn4CaO5 water-oxidizing complex (WOC) and half of the reaction center cofactors, and it is present as two isoforms in the cyanobacterium Synechococcus elongatus PCC 7942. These isoforms, D1:1 and D1:2, confer functional advantages for photosynthetic growth at low and high light intensities, respectively. D1:1, D1:2, and seven point mutations in the D1:2 background that are native to D1:1 were expressed in the green alga Chlamydomonas reinhardtii. We used these nine strains to show that those strains that confer a higher yield of PSII charge separation under light-limiting conditions (where charge recombination is significant) have less efficient photochemical turnover, measured in terms of both a lower WOC turnover probability and a longer WOC cycle period. Conversely, these same strains under light saturation (where charge recombination does not compete) confer a correspondingly faster O2 evolution rate and greater protection against photoinhibition. Taken together, the data clearly establish that PSII primary charge separation is a trade-off between photochemical productivity (water oxidation and plastoquinone reduction) and charge recombination (photoprotection). These trade-offs add up to a significant growth advantage for the two natural isoforms. These insights provide fundamental design principles for engineering of PSII reaction centers with optimal photochemical efficiencies for growth at low versus high light intensities.

A balanced ATP driving force module for enhancing photosynthetic biosynthesis of 3-hydroxybutyrate from CO2.

Science.gov (United States)

Ku, Jason T; Lan, Ethan I

2018-03-01

Using engineered photoautotrophic microorganisms for the direct chemical synthesis from CO 2 is an attractive direction for both sustainability and CO 2 mitigation. However, the behaviors of non-native metabolic pathways may be difficult to control due to the different intracellular contexts between natural and heterologous hosts. While most metabolic engineering efforts focus on strengthening driving forces in pathway design to favor biochemical production in these organisms, excessive driving force may be detrimental to product biosynthesis due to imbalanced cellular intermediate distribution. In this study, an ATP-hydrolysis based driving force module was engineered into cyanobacterium Synechococcus elongatus PCC 7942 to produce 3-hydroxybutyrate (3HB), a valuable chemical feedstock for the synthesis of biodegradable plastics and antibiotics. However, while the ATP driving force module is effective for increasing product formation, uncontrolled accumulation of intermediate metabolites likely led to metabolic imbalance and thus to cell growth inhibition. Therefore, the ATP driving force module was reengineered by providing a reversible outlet for excessive carbon flux. Upon expression of this balanced ATP driving force module with 3HB biosynthesis, engineered strain produced 3HB with a cumulative titer of 1.2 g/L, a significant increase over the initial strain. This result highlighted the importance of pathway reversibility as an effective design strategy for balancing driving force and intermediate accumulation, thereby achieving a self-regulated control for increased net flux towards product biosynthesis. Copyright © 2018 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

A new species of Leporinus Agassiz, 1829 from the upper Rio Paraná basin (Characiformes, Anostomidae with redescription of L. elongatus Valenciennes, 1850 and L. obtusidens (Valenciennes, 1837

Directory of Open Access Journals (Sweden)

Heraldo A. Britski

2012-01-01

Full Text Available Leporinus obtusidens Valenciennes, 1837 and L. elongatus Valenciennes, 1850 are redescribed based on the type specimens, including those of their junior synonyms, and recently collected specimens. Leporinus obtusidens is considered to be widespread, occuring in the river drainages of La Plata, São Francisco, and Parnaíba. Leporinus aguapeiensis Campos, 1945, described from the upper Rio Paraná, and L. silvestrii Boulenger, 1902, described from the Rio Paraguay, are considered junior synonyms of L. obtusidens. Leporinus elongatus is endemic to the Rio Jequitinhonha and Rio Pardo, two eastern Brazilian river basins, and the locality cited for the lectotype, Rio São Fransico, likely to be erroneous. Leporinus crassilabris Borodin, 1929, and L. crassilabris breviceps Borodin, 1929, both described from the Rio Jequitinhonha, are considered junior synynoms of L. elongatus. A new species of Leporinus, endemic to the upper Rio Paraná, very similar and sometimes mistaken with L. obtusidens, is formally described. In addition, comments on Leporinus pachyurus Valenciennes, 1850 and on L. bimaculatus Castelnau, 1855 are provided, and a lectotype for L. bimaculatus is selected.

Changes in the Synechococcus Assemblage Composition at the Surface of the East China Sea Due to Flooding of the Changjiang River.

Science.gov (United States)

Chung, Chih-Ching; Gong, Gwo-Ching; Huang, Chin-Yi; Lin, Jer-Young; Lin, Yun-Chi

2015-10-01

The aim of this study was to elucidate how flooding of the Changjiang River affects the assemblage composition of phycoerythrin-rich (PE-rich) Synechococcus at the surface of the East China Sea (ECS). During non-flooding summers (e.g., 2009), PE-rich Synechococcus usually thrive at the outer edge of the Changjiang River diluted water coverage (CDW; salinity ≤31 PSU). In the summer of 2010, a severe flood occurred in the Changjiang River basin. The plentiful freshwater injection resulted in the expansion of the CDW over half of the ECS and caused PE-rich cells to show a uniform distribution pattern, with decreased abundance compared with the non-flooding summer. The phylogenetic diversity of 16S rRNA gene sequences indicated that the flooding event also shifted the picoplankton community composition from being dominated by Synechococcus, mainly attributed to the clade II lineage, to various orders of heterotrophic bacteria, including Actinobacteria, Flavobacteria, α-Proteobacteria, and γ-Proteobacteria. As an increasing number of studies have proposed that global warming might result in more frequent floods, combining this perspective with the information obtained from our previous [1] and this studies yield a more comprehensive understanding of the relationship between the composition of the marine Synechococcus assemblage and global environmental changes.

Morphology, chemistry and function of the postpharyngeal gland in the South American digger wasps Trachypus boharti and Trachypus elongatus.

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Gudrun Herzner

Full Text Available Microbes pose severe threats to animals as competitors or pathogens and strongly affect the evolution of life history traits like parental care. Females of the European beewolf Philanthus triangulum, a solitary digger wasp, provision their offspring with paralyzed honeybees and embalm them with the secretion from large postpharyngeal glands (PPG that contain mainly unsaturated hydrocarbons. This coating changes the physico-chemical properties of the prey surface, causes a reduction of water condensation and retards growth of mold fungi. Here we examined the closely related South American genus Trachypus, which shows a life-history similar to Philanthus. We investigated whether Trachypus spp. also possess PPGs and embalm larval provisions. Using histological methods and 3D reconstructions we show that Trachypus boharti and T. elongatus possess PPGs that are similar to P. triangulum but somewhat smaller. The ultrastructure of the gland epithelium suggests that the gland content is at least partly sequestered from the hemolymph. Chemical analyses using gas chromatography / mass spectrometry revealed that both the cuticle and PPGs of Trachypus contain mainly unsaturated long-chain hydrocarbons. The gland of T. boharti additionally contains long-chain ketones. The hydrocarbons from the PPG of T. elongatus occurred on prey bees excavated from nests in the field but not on conspecific control bees. While the embalming only slightly elevated the amount of hydrocarbons on prey bees, the proportion of unsaturated hydrocarbons, which is crucial for the antifungal effect, was significantly increased. The Trachypus species under study possess PPGs that are very similar to the PPG of P. triangulum with regard to morphology, ultrastructure and chemistry. Moreover, we provide clear evidence that T. elongatus females embalm their prey, presumably as a means of prey preservation. The observed differences among Trachypus and Philanthus in gland size and prey

Evaluating and optimizing recycled concrete fines in PCC mixtures containing supplementary cementitious materials.

Science.gov (United States)

2010-08-01

Portland cement concrete (PCC) is used throughout transportation infrastructure, for roads as well as bridges : and other structures. One of the most effective ways of making PCC more green is to replace a portion of the : portland cement (the ...

Factors Associated with Parental Satisfaction with a Pediatric Crisis Clinic (PCC).

Science.gov (United States)

Lee, Jonathan; Korczak, Daphne

2014-05-01

Little is known about parental satisfaction with pediatric crisis clinics (PCCs) that provide a single consultation to families in need of urgent psychiatric care. Parental satisfaction may improve long-term adherence to physician recommendations. To explore parental satisfaction with a PCC. Parental satisfaction was ascertained by a structured telephone interview following crisis consultation at the PCC of an academic, tertiary care centre. Parents of 71% (n = 124) of 174 pediatric patients seen in the PCC from 2007-2008 participated in the post-consultation interview. The majority of parents stated they were either somewhat satisfied (49/122, 40.2%) or very satisfied (49/122, 40.2%) with the PCC. Parental satisfaction correlated with time between referral and consultation (p<0.05), the degree to which parents felt listened to by the consultant (p<0.01), the amount of psychoeducation parents felt they received (p<0.01), and appointment length (p<0.001). Parents were satisfied overall with an urgent care service model. Satisfaction was correlated with the time between referral and consultation, degree to which they felt their consultant had listened to them, and the amount of information they received at the consultation's conclusion.

Quantitative and functional characterization of the hyper-conserved protein of Prochlorococcus and marine Synechococcus.

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Caroline E Whidden

Full Text Available A large fraction of any bacterial genome consists of hypothetical protein-coding open reading frames (ORFs. While most of these ORFs are present only in one or a few sequenced genomes, a few are conserved, often across large phylogenetic distances. Such conservation provides clues to likely uncharacterized cellular functions that need to be elucidated. Marine cyanobacteria from the Prochlorococcus/marine Synechococcus clade are dominant bacteria in oceanic waters and are significant contributors to global primary production. A Hyper Conserved Protein (PSHCP of unknown function is 100% conserved at the amino acid level in genomes of Prochlorococcus/marine Synechococcus, but lacks homologs outside of this clade. In this study we investigated Prochlorococcus marinus strains MED4 and MIT 9313 and Synechococcus sp. strain WH 8102 for the transcription of the PSHCP gene using RT-Q-PCR, for the presence of the protein product through quantitative immunoblotting, and for the protein's binding partners in a pull down assay. Significant transcription of the gene was detected in all strains. The PSHCP protein content varied between 8±1 fmol and 26±9 fmol per ug total protein, depending on the strain. The 50 S ribosomal protein L2, the Photosystem I protein PsaD and the Ycf48-like protein were found associated with the PSHCP protein in all strains and not appreciably or at all in control experiments. We hypothesize that PSHCP is a protein associated with the ribosome, and is possibly involved in photosystem assembly.

Incorporation of 14C-succinate in Synechococcus

International Nuclear Information System (INIS)

Doehler, G.

1983-01-01

The cyanobacterium Synechococcus (= Anacystis nidulans) was grown under normal air conditions (0.03 vol.% CO 2 ) and in low white light (0.5 x 10 3 μW/cm 2 ) at 37 0 C. Kinetics of 14 C incorporation into several soluble products and pigments were studied after adding 14 C-succinate during photosynthesis and in the dark using the autoradiographic method. Radioactivity was found mainly in glutamate and aspartate during the photosynthetic period independent on 3-(3',4'-dichlorphenyl)-1,1-dimethylurea preincubation. In the dark period 14 C label could also be detected in malate. Short-term kinetics experiments showed a decrease in 14 C label of glutamate and a parallel increase of aspartate. Results were discussed in respect to the interrupted tricarboxylic acid cycle. (author)

Evaluation of the MIT-Scan-T2 for non-destructive PCC pavement thickness determination.

Science.gov (United States)

2008-07-01

The MIT-Scan-T2 device is marketed as a non-destructive way to determine pavement thickness on both : HMA and PCC pavements. PCC pavement thickness determination is an important incentivedisincentive : measurement for the Iowa DOT and contractors. Th...

Culturing photosynthetic bacteria through surface plasmon resonance

Energy Technology Data Exchange (ETDEWEB)

Ooms, Matthew D.; Bajin, Lauren; Sinton, David [Department of Mechanical and Industrial Engineering and Centre for Sustainable Energy, University of Toronto, Toronto M5S 3G8 (Canada)

2012-12-17

In this work, cultivation of photosynthetic microbes in surface plasmon enhanced evanescent fields is demonstrated. Proliferation of Synechococcus elongatus was obtained on gold surfaces excited with surface plasmons. Excitation over three days resulted in 10 {mu}m thick biofilms with maximum cell volume density of 20% vol/vol (2% more total accumulation than control experiments with direct light). Collectively, these results indicate the ability to (1) excite surface-bound cells using plasmonic light fields, and (2) subsequently grow thick biofilms by coupling light from the surface. Plasmonic light delivery presents opportunities for high-density optofluidic photobioreactors for microalgal analysis and solar fuel production.

Determination of coefficient of thermal expansion effects on Louisiana's PCC pavement design : technical summary report.

Science.gov (United States)

2011-12-01

The coefficient of thermal expansion (CTE) has been widely considered as a fundamental property of : Portland cement concrete (PCC) pavement but has never played an important role in the thickness design : procedure for PCC pavement until recently. I...

PCC-ring induction in human lymphocytes exposed to gamma and neutron irradiation

Energy Technology Data Exchange (ETDEWEB)

Lamadrid B, A I; Garcia L, O [CPHR, Calle 20 No. 4113 e/41 y 47, Playa, La Habana 11300 (Cuba); Delbos, M; Voisin, P; Roy, L [Institut de Radioprotection et de Surete Nucleaire, BP 17, 92262 Fontenay-aux-Roses (France)

2006-07-01

Dose-effect curves for dose assessment in Gamma and neutron overexposures to high doses are presented in this paper for the first time in literature. The relationships were obtained by plotting the Premature Chromosome Condensation -rings (PCC-R) frequencies in PCC Iymphocytes obtained by chemical induction with Calyculin A in vitro, with radiation doses between 5 to 25 Gy. For the elaboration of these curves 9 676 PCC cells in Gl G2 and M stages were analyzed. The results were fitted to a lineal quadratic model in Gamma irradiation. For neutron irradiation the data was fitted to a lineal quadratic model up to 10 Gy and then a markedly cell cycle arrest and saturation was observed. These curves are of particular interest for victims exposed to doses exceeding 5 Gy where it is always very difficult to estimate a dose using the conventional technique. (Author)

PCC-ring induction in human lymphocytes exposed to gamma and neutron irradiation

International Nuclear Information System (INIS)

Lamadrid B, A.I.; Garcia L, O.; Delbos, M.; Voisin, P.; Roy, L.

2006-01-01

Dose-effect curves for dose assessment in Gamma and neutron overexposures to high doses are presented in this paper for the first time in literature. The relationships were obtained by plotting the Premature Chromosome Condensation -rings (PCC-R) frequencies in PCC Iymphocytes obtained by chemical induction with Calyculin A in vitro, with radiation doses between 5 to 25 Gy. For the elaboration of these curves 9 676 PCC cells in Gl G2 and M stages were analyzed. The results were fitted to a lineal quadratic model in Gamma irradiation. For neutron irradiation the data was fitted to a lineal quadratic model up to 10 Gy and then a markedly cell cycle arrest and saturation was observed. These curves are of particular interest for victims exposed to doses exceeding 5 Gy where it is always very difficult to estimate a dose using the conventional technique. (Author)

Evaluation of MIT-SCAN-T2 for Thickness Quality Control for PCC and HMA Pavements

Science.gov (United States)

2018-02-01

Thickness is currently a pay item for PCC pavements and a quality control item for both PCC and HMA pavements. A change in pavement thickness of 0.5 in. can result in a change of multiple years of service. Current thickness measurements are performed...

PCC-ring induction in human lymphocytes exposed to gamma and neutron irradiation

Energy Technology Data Exchange (ETDEWEB)

Lamadrid Boada, Ana I; Garcia Lima, Omar [Centro de Proteccion e Higiene de las Radiaciones (CPHR), La Habana (Cuba); Delbos, Martine; Voisin, Philipe; Roy, Laurence [Institut de Radioprotection et de Surete Nucleaire, Fontenay-aux-Roses (France)

2008-07-01

Dose-effect curves for dose assessment in Gamma and neutron overexposures to high doses are presented in this paper for the first time in literature. The relationships were obtained by plotting the Premature Chromosome Condensation -rings (PCC-R) frequencies in PCC lymphocytes obtained by chemical induction with Calyculin A in vitro, with radiation doses between 5 to 25 Gy. For the elaboration of these curves 9 676 PCC cells in G1 G2 and M stages were analyzed. The results were fitted to a lineal quadratic model in Gamma irradiation and showed saturation starting from 20 Gy. For neutron irradiation the data was fitted to a lineal quadratic model up to 10 Gy, and then a markedly cell cycle arrest and saturation was observed. These curves are of particular interest for victims exposed to doses exceeding 5 Gy where it is always very difficult to estimate a dose using the conventional technique. (author)

PCC-ring induction in human lymphocytes exposed to gamma and neutron irradiation

International Nuclear Information System (INIS)

Lamadrid Boada, Ana I.; Garcia Lima, Omar; Delbos, Martine; Voisin, Philipe; Roy, Laurence

2008-01-01

Dose-effect curves for dose assessment in Gamma and neutron overexposures to high doses are presented in this paper for the first time in literature. The relationships were obtained by plotting the Premature Chromosome Condensation -rings (PCC-R) frequencies in PCC lymphocytes obtained by chemical induction with Calyculin A in vitro, with radiation doses between 5 to 25 Gy. For the elaboration of these curves 9 676 PCC cells in G1 G2 and M stages were analyzed. The results were fitted to a lineal quadratic model in Gamma irradiation and showed saturation starting from 20 Gy. For neutron irradiation the data was fitted to a lineal quadratic model up to 10 Gy, and then a markedly cell cycle arrest and saturation was observed. These curves are of particular interest for victims exposed to doses exceeding 5 Gy where it is always very difficult to estimate a dose using the conventional technique. (author)

Evaluation of algal biofilms on indium tin oxide (ITO for use in biophotovoltaic platforms based on photosynthetic performance.

Directory of Open Access Journals (Sweden)

Fong-Lee Ng

Full Text Available In photosynthesis, a very small amount of the solar energy absorbed is transformed into chemical energy, while the rest is wasted as heat and fluorescence. This excess energy can be harvested through biophotovoltaic platforms to generate electrical energy. In this study, algal biofilms formed on ITO anodes were investigated for use in the algal biophotovoltaic platforms. Sixteen algal strains, comprising local isolates and two diatoms obtained from the Culture Collection of Marine Phytoplankton (CCMP, USA, were screened and eight were selected based on the growth rate, biochemical composition and photosynthesis performance using suspension cultures. Differences in biofilm formation between the eight algal strains as well as their rapid light curve (RLC generated using a pulse amplitude modulation (PAM fluorometer, were examined. The RLC provides detailed information on the saturation characteristics of electron transport and overall photosynthetic performance of the algae. Four algal strains, belonging to the Cyanophyta (Cyanobacteria Synechococcus elongatus (UMACC 105, Spirulina platensis. (UMACC 159 and the Chlorophyta Chlorella vulgaris (UMACC 051, and Chlorella sp. (UMACC 313 were finally selected for investigation using biophotovoltaic platforms. Based on power output per Chl-a content, the algae can be ranked as follows: Synechococcus elongatus (UMACC 105 (6.38×10(-5 Wm(-2/µgChl-a>Chlorella vulgaris UMACC 051 (2.24×10(-5 Wm(-2/µgChl-a>Chlorella sp.(UMACC 313 (1.43×10(-5 Wm(-2/µgChl-a>Spirulina platensis (UMACC 159 (4.90×10(-6 Wm(-2/µgChl-a. Our study showed that local algal strains have potential for use in biophotovoltaic platforms due to their high photosynthetic performance, ability to produce biofilm and generation of electrical power.

Production of cyanopeptolins, anabaenopeptins, and microcystins by the harmful cyanobacteria Anabaena 90 and Microcystis PCC 7806

NARCIS (Netherlands)

Tonk, L.; Welker, M.; Huisman, J.; Visser, P.M.

2009-01-01

This study investigated the effects of light intensity, temperature, and phosphorus limitation on the peptide production of the cyanobacteria Microcystis PCC 7806 and Anabaena 90. Microcystis PCC 7806 produced two microcystin variants and three cyanopeptolins, whereas Anabaena 90 produced four

Effect of Hydraulic Activity on Crystallization of Precipitated Calcium Carbonate (PCC) for Eco-Friendly Paper

Science.gov (United States)

Kim, Jung-Ah; Han, Gi-Chun; Lim, Mihee; You, Kwang-Suk; Ryu, Miyoung; Ahn, Ji-Whan; Fujita, Toyohisa; Kim, Hwan

2009-01-01

Wt% of aragonite, a CaCO3 polymorph, increased with higher hydraulic activity (°C) of limestone in precipitated calcium carbonate (PCC) from the lime-soda process (Ca(OH)2-NaOH-Na2CO3). Only calcite, the most stable polymorph, was crystallized at hydraulic activity under 10 °C, whereas aragonite also started to crystallize over 10 °C. The crystallization of PCC is more dependent on the hydraulic activity of limestone than CaO content, a factor commonly used to classify limestone ores according to quality. The results could be effectively applied to the determination of polymorphs in synthetic PCC for eco-friendly paper manufacture. PMID:20087470

Effect of water curing duration on strength behaviour of portland composite cement (PCC) mortar

Science.gov (United States)

Caronge, M. A.; Tjaronge, M. W.; Hamada, H.; Irmawaty, R.

2017-11-01

Cement manufacturing of Indonesia has been introduced Portland Composite Cement (PCC) to minimize the rising production cost of cement which contains 80% clinker and 20% mineral admixture. A proper curing is very important when the cement contains mineral admixture materials. This paper reports the results of an experimental study conducted to evaluate the effect of water curing duration on strength behaviour of PCC mortar. Mortar specimens with water to cement ratio of (W/C) 0.5 were casted. Compressive strength, flexural strength and concrete resistance were tested at 7, 28 and 91 days cured water. The results indicated that water curing duration is essential to continue the pozzolanic reaction in mortar which contributes to the development of strength of mortar made with PCC.

Dose - Response Curves for Dicentrics and PCC Rings: Preparedness for Radiological Emergency in Thailand

International Nuclear Information System (INIS)

Rungsimaphorn, B.; Rerkamnuaychoke, B.; Sudprasert, W.

2014-01-01

Establishing in-vitro dose calibration curves is important for reconstruction of radiation dose in the exposed individuals. The aim of this pioneering work in Thailand was to generate dose-response curves using conventional biological dosimetry: dicentric chromosome assay (DCA) and premature chromosome condensation (PCC) assay. The peripheral blood lymphocytes were irradiated with 137 Cs at a dose rate of 0.652 Gy/min to doses of 0.1, 0.25, 0.5, 0.75, 1, 2, 3, 4 and 5 Gy for DCA technique, and 5, 10, 15, 20 and 25 Gy for PCC technique. The blood samples were cultured and processed following the standard procedure given by the IAEA with slight modifications. At least 500-1,000 metaphases or 100 dicentrics/ PCC rings were analyzed using an automated metaphase finder system. The yield of dicentrics with dose was fitted to a linear quadratic model using Chromosome Aberration Calculation Software (CABAS, version 2.0), whereas the dose-response curve of PCC rings was fitted to a linear relationship. These curves will be useful for in-vitro dose reconstruction and can support the preparedness for radiological emergency in the country.

The structure of allophycocyanin from Thermosynechococcus elongatus at 3.5 Å resolution

Energy Technology Data Exchange (ETDEWEB)

Murray, James William; Maghlaoui, Karim; Barber, James, E-mail: j.barber@imperial.ac.uk [Division of Molecular Biosciences, Imperial College, Exhibition Road, London SW7 2AZ (United Kingdom)

2007-12-01

The crystal structure of a light-harvesting protein that interacts with photosystem II is reported. Cyanobacteria and red algae use light-harvesting pigments bound by proteins to capture solar radiation and to channel excitation energy into their reaction centres. In most cyanobacteria, a multi-megadalton soluble structure known as the phycobilisome is a major light-harvesting system. Allophycocyanin is the main component of the phycobilisome core, forming a link between the rest of the phycobilisome and the reaction-centre core. The crystal structure of allophycocyanin from Thermosynechococcus elongatus (TeAPC) has been determined and refined at 3.5 Å resolution to a crystallographic R value of 26.0% (R{sub free} = 28.5%). The structure was solved by molecular replacement using the allophycocyanin structure from Spirulina platensis as the search model. The asymmetric unit contains an (αβ) monomer which is expanded by symmetry to a crystallographic trimer.

Spatial genetic structure and mitochondrial DNA phylogeography of Argentinean populations of the grasshopper Dichroplus elongatus.

Directory of Open Access Journals (Sweden)

Natalia Rosetti

Full Text Available Many grasshopper species are considered of agronomical importance because they cause damage to pastures and crops. Comprehension of pest population dynamics requires a clear understanding of the genetic diversity and spatial structure of populations. In this study we report on patterns of genetic variation in the South American grasshopper Dichroplus elongatus which is an agricultural pest of crops and forage grasses of great economic significance in Argentina. We use Direct Amplification of Minisatellite Regions (DAMD and partial sequences of the cytochrome oxydase 1 (COI mitochondrial gene to investigate intraspecific structure, demographic history and gene flow patterns in twenty Argentinean populations of this species belonging to different geographic and biogeographic regions. DAMD data suggest that, although genetic drift and migration occur within and between populations, measurable relatedness among neighbouring populations declines with distance and dispersal over distances greater than 200 km is not typical, whereas effective gene flow may occur for populations separated by less than 100 km. Landscape analysis was useful to detect genetic discontinuities associated with environmental heterogeneity reflecting the changing agroecosystem. The COI results indicate the existence of strong genetic differentiation between two groups of populations located at both margins of the Paraná River which became separated during climate oscillations of the Middle Pleistocene, suggesting a significant restriction in effective dispersion mediated by females and large scale geographic differentiation. The number of migrants between populations estimated through mitochondrial and DAMD markers suggest that gene flow is low prompting a non-homogeneous spatial structure and justifying the variation through space. Moreover, the genetic analysis of both markers allows us to conclude that males appear to disperse more than females, reducing the chance of the

Secondary metabolite from Nostoc XPORK14A inhibits photosynthesis and growth of Synechocystis PCC 6803.

Science.gov (United States)

Shunmugam, Sumathy; Jokela, Jouni; Wahlsten, Matti; Battchikova, Natalia; Ateeq ur Rehman; Vass, Imre; Karonen, Maarit; Sinkkonen, Jari; Permi, Perttu; Sivonen, Kaarina; Aro, Eva-Mari; Allahverdiyeva, Yagut

2014-06-01

Screening of 55 different cyanobacterial strains revealed that an extract from Nostoc XPORK14A drastically modifies the amplitude and kinetics of chlorophyll a fluorescence induction of Synechocystis PCC6803 cells.After 2 d exposure to the Nostoc XPORK14A extract, Synechocystis PCC 6803 cells displayed reduced net photosynthetic activity and significantly modified electron transport properties of photosystem II under both light and dark conditions. However, the maximum oxidizable amount of P700 was not strongly affected. The extract also induced strong oxidative stress in Synechocystis PCC 6803 cells in both light and darkness. We identified the secondary metabolite of Nostoc XPORK14A causing these pronounced effects on Synechocystis cells. Mass spectrometry and nuclear magnetic resonance analyses revealed that this compound, designated as M22, has a non-peptide structure. We propose that M22 possesses a dualaction mechanism: firstly, by photogeneration of reactive oxygen species in the presence of light, which in turn affects the photosynthetic machinery of Synechocystis PCC 6803; and secondly, by altering the in vivo redox status of cells, possibly through inhibition of protein kinases.

Signature proteins for the major clades of Cyanobacteria

Directory of Open Access Journals (Sweden)

Mathews Divya W

2010-01-01

Full Text Available Abstract Background The phylogeny and taxonomy of cyanobacteria is currently poorly understood due to paucity of reliable markers for identification and circumscription of its major clades. Results A combination of phylogenomic and protein signature based approaches was used to characterize the major clades of cyanobacteria. Phylogenetic trees were constructed for 44 cyanobacteria based on 44 conserved proteins. In parallel, Blastp searches were carried out on each ORF in the genomes of Synechococcus WH8102, Synechocystis PCC6803, Nostoc PCC7120, Synechococcus JA-3-3Ab, Prochlorococcus MIT9215 and Prochlor. marinus subsp. marinus CCMP1375 to identify proteins that are specific for various main clades of cyanobacteria. These studies have identified 39 proteins that are specific for all (or most cyanobacteria and large numbers of proteins for other cyanobacterial clades. The identified signature proteins include: (i 14 proteins for a deep branching clade (Clade A of Gloebacter violaceus and two diazotrophic Synechococcus strains (JA-3-3Ab and JA2-3-B'a; (ii 5 proteins that are present in all other cyanobacteria except those from Clade A; (iii 60 proteins that are specific for a clade (Clade C consisting of various marine unicellular cyanobacteria (viz. Synechococcus and Prochlorococcus; (iv 14 and 19 signature proteins that are specific for the Clade C Synechococcus and Prochlorococcus strains, respectively; (v 67 proteins that are specific for the Low B/A ecotype Prochlorococcus strains, containing lower ratio of chl b/a2 and adapted to growth at high light intensities; (vi 65 and 8 proteins that are specific for the Nostocales and Chroococcales orders, respectively; and (vii 22 and 9 proteins that are uniquely shared by various Nostocales and Oscillatoriales orders, or by these two orders and the Chroococcales, respectively. We also describe 3 conserved indels in flavoprotein, heme oxygenase and protochlorophyllide oxidoreductase proteins that

Highly plastic genome of Microcystis aeruginosa PCC 7806, a ubiquitous toxic freshwater cyanobacterium

Directory of Open Access Journals (Sweden)

Latifi Amel

2008-06-01

Full Text Available Abstract Background The colonial cyanobacterium Microcystis proliferates in a wide range of freshwater ecosystems and is exposed to changing environmental factors during its life cycle. Microcystis blooms are often toxic, potentially fatal to animals and humans, and may cause environmental problems. There has been little investigation of the genomics of these cyanobacteria. Results Deciphering the 5,172,804 bp sequence of Microcystis aeruginosa PCC 7806 has revealed the high plasticity of its genome: 11.7% DNA repeats containing more than 1,000 bases, 6.8% putative transposases and 21 putative restriction enzymes. Compared to the genomes of other cyanobacterial lineages, strain PCC 7806 contains a large number of atypical genes that may have been acquired by lateral transfers. Metabolic pathways, such as fermentation and a methionine salvage pathway, have been identified, as have genes for programmed cell death that may be related to the rapid disappearance of Microcystis blooms in nature. Analysis of the PCC 7806 genome also reveals striking novel biosynthetic features that might help to elucidate the ecological impact of secondary metabolites and lead to the discovery of novel metabolites for new biotechnological applications. M. aeruginosa and other large cyanobacterial genomes exhibit a rapid loss of synteny in contrast to other microbial genomes. Conclusion Microcystis aeruginosa PCC 7806 appears to have adopted an evolutionary strategy relying on unusual genome plasticity to adapt to eutrophic freshwater ecosystems, a property shared by another strain of M. aeruginosa (NIES-843. Comparisons of the genomes of PCC 7806 and other cyanobacterial strains indicate that a similar strategy may have also been used by the marine strain Crocosphaera watsonii WH8501 to adapt to other ecological niches, such as oligotrophic open oceans.

Sintesa Precipitated Calcium Carbonate (PCC) dari Cangkang Kerang Darah (Anadara Granosa) dengan Variasi Ukuran Partikel dan Waktu Karbonasi

OpenAIRE

Rahmawati, Lucy; Amri, Amun; Zultiniar, Zultiniar; Yelmida, Yelmida

2015-01-01

Precipitated Calcium Carbonate (PCC) is a product of the processing of natural materials containing calcium carbonate resulting from the precipitation process with high purity. Bloodcockle shell can be used as a source of calcium for precipitated Calcium Carbonate. The purpose of this study to produce PCC of waste shells blood with carbonation method and determine the particle size of the PCC and the best carbonation time. Synthesis performed using carbonation method by adding nitric acid to ...

Flexible dynamic operation of solar-integrated power plant with solvent based post-combustion carbon capture (PCC) process

International Nuclear Information System (INIS)

Qadir, Abdul; Sharma, Manish; Parvareh, Forough; Khalilpour, Rajab; Abbas, Ali

2015-01-01

Highlights: • Flexible operation of power and PCC plant may significantly increase operational revenue. • Higher optimal carbon capture rates observed with solar thermal energy input. • Solar thermal repowering of the power plant provides highest net revenue. • Constant optimal capture rate observed for one of the flexible operation cases. • Up to 42% higher revenue generation observed between two cases with solar input. - Abstract: This paper examines flexible operation of solvent-based post-combustion carbon capture (PCC) for the reduction of power plant carbon emissions while minimizing revenue loss due to the reduced power plant electricity output. The study is conducted using a model superstructure enveloping three plants; a power plant, a PCC plant and a solar thermal field where the power plant and PCC plant are operated flexibly under the influence of hourly electricity market and weather conditions. Reduced (surrogate) models for the reboiler duty and auxiliary power requirement for the carbon capture plant are generated and applied to simulate and compare four cases, (A) power plant with PCC, (B) power plant with solar assisted PCC, (C) power plant with PCC and solar repowering – variable net electricity output and (D) power plant with PCC and solar repowering – fixed net electricity output. Such analyses are conducted under dynamic conditions including power plant part-load operation while varying the capture rate to optimize the revenue of the power plant. Each case was simulated with a lower carbon price of $25/tonne-CO 2 and a higher price of $50/tonne-CO 2 . The comparison of cases B–D found that optimal revenue generation for case C can be up to 42% higher than that of solar-assisted PCC (case B). Case C is found to be the most profitable with the lowest carbon emissions intensity and is found to exhibit a constant capture rate for both carbon prices. The optimal revenue for case D is slightly lower than case C for the lower carbon

Deep sequencing-based identification of small regulatory RNAs in Synechocystis sp. PCC 6803.

Directory of Open Access Journals (Sweden)

Wen Xu

Full Text Available Synechocystis sp. PCC 6803 is a genetically tractable model organism for photosynthesis research. The genome of Synechocystis sp. PCC 6803 consists of a circular chromosome and seven plasmids. The importance of small regulatory RNAs (sRNAs as mediators of a number of cellular processes in bacteria has begun to be recognized. However, little is known regarding sRNAs in Synechocystis sp. PCC 6803. To provide a comprehensive overview of sRNAs in this model organism, the sRNAs of Synechocystis sp. PCC 6803 were analyzed using deep sequencing, and 7,951,189 reads were obtained. High quality mapping reads (6,127,890 were mapped onto the genome and assembled into 16,192 transcribed regions (clusters based on read overlap. A total number of 5211 putative sRNAs were revealed from the genome and the 4 megaplasmids, and 27 of these molecules, including four from plasmids, were confirmed by RT-PCR. In addition, possible target genes regulated by all of the putative sRNAs identified in this study were predicted by IntaRNA and analyzed for functional categorization and biological pathways, which provided evidence that sRNAs are indeed involved in many different metabolic pathways, including basic metabolic pathways, such as glycolysis/gluconeogenesis, the citrate cycle, fatty acid metabolism and adaptations to environmentally stress-induced changes. The information from this study provides a valuable reservoir for understanding the sRNA-mediated regulation of the complex physiology and metabolic processes of cyanobacteria.

Fundamental Frequency Estimation of the Speech Signal Compressed by MP3 Algorithm Using PCC Interpolation

Directory of Open Access Journals (Sweden)

MILIVOJEVIC, Z. N.

2010-02-01

Full Text Available In this paper the fundamental frequency estimation results of the MP3 modeled speech signal are analyzed. The estimation of the fundamental frequency was performed by the Picking-Peaks algorithm with the implemented Parametric Cubic Convolution (PCC interpolation. The efficiency of PCC was tested for Catmull-Rom, Greville and Greville two-parametric kernel. Depending on MSE, a window that gives optimal results was chosen.

Transcription and Regulation of the Bidirectional Hydrogenase in the Cyanobacterium Nostoc sp. Strain PCC 7120▿

Science.gov (United States)

Sjöholm, Johannes; Oliveira, Paulo; Lindblad, Peter

2007-01-01

The filamentous, heterocystous cyanobacterium Nostoc sp. strain PCC 7120 (Anabaena sp. strain PCC 7120) possesses an uptake hydrogenase and a bidirectional enzyme, the latter being capable of catalyzing both H2 production and evolution. The completely sequenced genome of Nostoc sp. strain PCC 7120 reveals that the five structural genes encoding the bidirectional hydrogenase (hoxEFUYH) are separated in two clusters at a distance of approximately 8.8 kb. The transcription of the hox genes was examined under nitrogen-fixing conditions, and the results demonstrate that the cluster containing hoxE and hoxF can be transcribed as one polycistronic unit together with the open reading frame alr0750. The second cluster, containing hoxU, hoxY, and hoxH, is transcribed together with alr0763 and alr0765, located between the hox genes. Moreover, alr0760 and alr0761 form an additional larger operon. Nevertheless, Northern blot hybridizations revealed a rather complex transcription pattern in which the different hox genes are expressed differently. Transcriptional start points (TSPs) were identified 66 and 57 bp upstream from the start codon of alr0750 and hoxU, respectively. The transcriptions of the two clusters containing the hox genes are both induced under anaerobic conditions concomitantly with the induction of a higher level of hydrogenase activity. An additional TSP, within the annotated alr0760, 244 bp downstream from the suggested translation start codon, was identified. Electrophoretic mobility shift assays with purified LexA from Nostoc sp. strain PCC 7120 demonstrated specific interactions between the transcriptional regulator and both hox promoter regions. However, when LexA from Synechocystis sp. strain PCC 6803 was used, the purified protein interacted only with the promoter region of the alr0750-hoxE-hoxF operon. A search of the whole Nostoc sp. strain PCC 7120 genome demonstrated the presence of 216 putative LexA binding sites in total, including recA and rec

Applications of Cyanobacteria in Biofuel Production

DEFF Research Database (Denmark)

Möllers, K. Benedikt

and to evolve from a wasteful petrochemical system into a sustainable bio-based society, biofuels and the introduction of bio-refineries play an essential role. Aquatic phototrophs are promising organisms to employ photosynthetic capacities as well as the derived carbohydrates for the production of biofuels......, enzymatic conversion of lignocellulosic biomass for further fermentation or as a platform chemical in a bio-refinery concept. Autotrophically cultivated cells of the marine model cyanobacterium Synechococcus sp. PCC 7002 (Synechococcus) were exposed to mild nitrogen starvation which has been identified...... for fermentation of plant waste material or a substitute for yeast extract. By mimicking photosynthetic electron transport from light excited photo pigments to LPMOs in combination with a reductant and cellulose as substrate, a 100-fold increase in catalytic activity of LPMOs was observed. Also, it was found...

Visualizing tributyltin (TBT) in bacterial aggregates by specific rhodamine-based fluorescent probes.

Science.gov (United States)

Jin, Xilang; Hao, Likai; She, Mengyao; Obst, Martin; Kappler, Andreas; Yin, Bing; Liu, Ping; Li, Jianli; Wang, Lanying; Shi, Zhen

2015-01-01

Here we present the first examples of fluorescent and colorimetric probes for microscopic TBT imaging. The fluorescent probes are highly selective and sensitive to TBT and have successfully been applied for imaging of TBT in bacterial Rhodobacter ferrooxidans sp. strain SW2 cell-EPS-mineral aggregates and in cell suspensions of the marine cyanobacterium Synechococcus PCC 7002 by using confocal laser scanning microscopy. Copyright © 2014 Elsevier B.V. All rights reserved.

Characterization of hydrocortisone bioconversion and 16S RNA gene in Synechococcus nidulans cultures.

Science.gov (United States)

Rasoul-Amini, S; Ghasemi, Y; Morowvat, M H; Ghoshoon, M B; Raee, M J; Mosavi-Azam, S B; Montazeri-Najafabady, N; Nouri, F; Parvizi, R; Negintaji, N; Khoubani, S

2010-01-01

A unicellular cyanobacterium, Synechococcus nidulans (Pringsheim) Komárek, was isolated from paddy-fields and applied in the biotransformation experiment of hydrocortisone (1). This strain has not been previously tested for steroid bioconversion. Fermentation was carried out in BG-11 medium supplemented with 0.05% substrate at 25 degrees C for 14 days of incubation. The obtained products were chromatographically purified followed by their characterization using spectroscopic methods. 11beta,17beta-dihydroxyandrost-4-en-3-one (2), 11beta-hydroxyandrost-4-en-3,17-dione (3), and androst-4-ene-3,17-dione (4) were the main bioproducts in the hydrocortisone bioconversion. The observed bioreaction characteristics were the side chain degradation of the substrate to prepare compounds (2) and (3) following the 11beta-dehydroxylation for accumulation of the compound (4). Time course study showed the accumulation of the product (2) from the second day of the fermentation and compounds (3) and (4) from the third day. All the metabolites reached their maximum concentration in seven days. Cyanobacterial 16S rRNA gene was also amplified by PCR. Sequences were amplified using the universal prokaryotic primers which amplify a approximately 400-bp region of the 16S rRNA gene. PCR products were sequenced to confirm their authenticity as 16S rRNA gene of cyanobacteria. The result of PCR blasted with other sequenced cyanobacteria in NCBI showed 99% identity to the 16S small subunit rRNA of seven Synechococcus species.

THE STRUCTURE OF PHOTOSYSTEM-I FROM THE THERMOPHILIC CYANOBACTERIUM SYNECHOCOCCUS SP DETERMINED BY ELECTRON-MICROSCOPY OF 2-DIMENSIONAL CRYSTALS

NARCIS (Netherlands)

BOTTCHER, B; GRABER, P; BOEKEMA, EJ

1992-01-01

The structure of the Photosystem I (PS I) complex from the thermophilic cyanobacterium Synechococcus sp. has been investigated by electron microscopy and image analysis of two-dimensional crystals. Crystals were obtained from isolated PS I by removal of detergents with Bio-Beads. After negative

Evaluation of MIT-SCAN-T2 for thickness quality control for PCC and HMA pavements : research project capsule.

Science.gov (United States)

2013-04-01

Thickness is currently a pay item for portland cement concrete (PCC) pavements : and a quality control item for both PCC and hot mix asphalt (HMA) pavements. : A change in pavement thickness of 0.5 in. can result in a reduction of multiple : years of...

Transfected parvalbumin alters calcium homeostasis in teratocarcinoma PCC7 cells

DEFF Research Database (Denmark)

Müller, B K; Kabos, P; Belhage, B

1996-01-01

Indirect evidence supports a protective role of some EF-hand calcium-binding proteins against calcium-induced neurotoxicity. Little is known about how these proteins influence cytosolic calcium levels. After cloning the parvalbumin cDNA into an expression vector, teratocarcinoma cells (PCC7) were...

Identification of residues important for the activity of aldehyde-deformylating oxygenase through investigation into the structure-activity relationship.

Science.gov (United States)

Wang, Qing; Bao, Luyao; Jia, Chenjun; Li, Mei; Li, Jian-Jun; Lu, Xuefeng

2017-03-16

Aldehyde-deformylating oxygenase (ADO) is a key enzyme involved in the biosynthetic pathway of fatty alk(a/e)nes in cyanobacteria. However, cADO (cyanobacterial ADO) showed extreme low activity with the k cat value below 1 min -1 , which would limit its application in biofuel production. To identify the activity related key residues of cADO is urgently required. The amino acid residues which might affect cADO activity were identified based on the crystal structures and sequence alignment of cADOs, including the residues close to the di-iron center (Tyr39, Arg62, Gln110, Tyr122, Asp143 of cADO-1593), the protein surface (Trp 178 of cADO-1593), and those involved in two important hydrogen bonds (Gln49, Asn123 of cADO-1593, and Asp49, Asn123 of cADO-sll0208) and in the oligopeptide whose conformation changed in the absence of the di-iron center (Leu146, Asn149, Phe150 of cADO-1593, and Thr146, Leu148, Tyr150 of cADO-sll0208). The variants of cADO-1593 from Synechococcus elongatus PCC7942 and cADO-sll0208 from Synechocystis sp. PCC6803 were constructed, overexpressed, purified and kinetically characterized. The k cat values of L146T, Q49H/N123H/F150Y and W178R of cADO-1593 and L148R of cADO-sll0208 were increased by more than two-fold, whereas that of R62A dropped by 91.1%. N123H, Y39F and D143A of cADO-1593, and Y150F of cADO-sll0208 reduced activities by ≤ 20%. Some important amino acids, which exerted some effects on cADO activity, were identified. Several enzyme variants exhibited greatly reduced activity, while the k cat values of several mutants are more than two-fold higher than the wild type. This study presents the report on the relationship between amino acid residues and enzyme activity of cADOs, and the information will provide a guide for enhancement of cADO activity through protein engineering.

EasyPCC: Benchmark Datasets and Tools for High-Throughput Measurement of the Plant Canopy Coverage Ratio under Field Conditions

Directory of Open Access Journals (Sweden)

Wei Guo

2017-04-01

Full Text Available Understanding interactions of genotype, environment, and management under field conditions is vital for selecting new cultivars and farming systems. Image analysis is considered a robust technique in high-throughput phenotyping with non-destructive sampling. However, analysis of digital field-derived images remains challenging because of the variety of light intensities, growth environments, and developmental stages. The plant canopy coverage (PCC ratio is an important index of crop growth and development. Here, we present a tool, EasyPCC, for effective and accurate evaluation of the ground coverage ratio from a large number of images under variable field conditions. The core algorithm of EasyPCC is based on a pixel-based segmentation method using a decision-tree-based segmentation model (DTSM. EasyPCC was developed under the MATLAB® and R languages; thus, it could be implemented in high-performance computing to handle large numbers of images following just a single model training process. This study used an experimental set of images from a paddy field to demonstrate EasyPCC, and to show the accuracy improvement possible by adjusting key points (e.g., outlier deletion and model retraining. The accuracy (R2 = 0.99 of the calculated coverage ratio was validated against a corresponding benchmark dataset. The EasyPCC source code is released under GPL license with benchmark datasets of several different crop types for algorithm development and for evaluating ground coverage ratios.

Phenotypic characterization of Synechocystis sp PCC 6803 substrains reveals differences in sensitivity to abiotic stress

Czech Academy of Sciences Publication Activity Database

Zavřel, Tomáš; Očenášová, Petra; Červený, Jan

2017-01-01

Roč. 12, č. 12 (2017), č. článku e0189130. E-ISSN 1932-6203 R&D Projects: GA MŠk(CZ) LO1415; GA ČR(CZ) GA15-17367S; GA ČR(CZ) GA15-17367S Institutional support: RVO:86652079 Keywords : sp strain pcc-6803 * high-temperature * sp pcc6803 * cyanobacterium * growth * responses * acclimation * gene * photobioreactor * identification Subject RIV: EI - Biotechnology ; Bionics OBOR OECD: Environmental biotechnology Impact factor: 2.806, year: 2016

Mono-, di- and trimeric PS I reaction center complexes isolated from the thermophilic cyanobacterium Synechococcus sp. Size, shape and activity

NARCIS (Netherlands)

Rögner, M.; Mühlenhoff, U.; Boekema, E.J.; Witt, H.T.

1990-01-01

Photosystem I preparations from the cyanobacterium Synechococcus sp. were treated with high concentrations of Tris and octyl glucoside at alkaline pH and elevated temperature. A sucrose density gradient yielded three pigment-protein complexes; these were further purified on a HPLC anion-exchange

The susceptibility of five African Anopheles species to Anabaena PCC 7120 expressing Bacillus thuringiensis subsp. israelensis mosquitocidal cry genes

Directory of Open Access Journals (Sweden)

Ketseoglou Irene

2012-10-01

Full Text Available Abstract Background Malaria, one of the leading causes of death in Africa, is transmitted by the bite of an infected female Anopheles mosquito. Problems associated with the development of resistance to chemical insecticides and concerns about the non-target effects and persistence of chemical insecticides have prompted the development of environmentally friendly mosquito control agents. The aim of this study was to evaluate the larvicidal activity of a genetically engineered cyanobacterium, Anabaena PCC 7120#11, against five African Anopheles species in laboratory bioassays. Findings There were significant differences in the susceptibility of the anopheline species to PCC 7120#11. The ranking of the larvicidal activity of PCC 7120#11 against species in the An. gambiae complex was: An. merus An. arabiensis An. gambiae An. quadriannulatus, where 50. The LC50 of PCC 7120#11 against the important malaria vectors An. gambiae and An. arabiensis was 12.3 × 105 cells/ml and 8.10 × 105 cells/ml, respectively. PCC 7120#11 was not effective against An. funestus, with less than 50% mortality obtained at concentrations as high as 3.20 × 107 cells/ml. Conclusions PCC 7120#11 exhibited good larvicidal activity against larvae of the An. gambiae complex, but relatively weak larvicidal activity against An. funestus. The study has highlighted the importance of evaluating a novel mosquitocidal agent against a range of malaria vectors so as to obtain a clear understanding of the agent’s spectrum of activity and potential as a vector control agent.

Polyhydroxybutyrate particles in Synechocystis sp PCC 6803: facts and fiction

Energy Technology Data Exchange (ETDEWEB)

Tsang, TK; Roberson, RW; Vermaas, WFJ

2013-09-20

Transmission electron microscopy has been used to identify poly-3-hydroxybutyrate (PHB) granules in cyanobacteria for over 40 years. Spherical inclusions inside the cell that are electron-transparent and/or slightly electron-dense and that are found in transmission electron micrographs of cyanobacteria are generally assumed to be PHB granules. The aim of this study was to test this assumption in different strains of the cyanobacterium Synechocystis sp. PCC 6803. Inclusions that resemble PHB granules were present in strains lacking a pair of genes essential for PHB synthesis and in wild-type cells under conditions that no PHB granules could be detected by fluorescence staining of PHB. Indeed, in these cells PHB could not be demonstrated chemically by GC/MS either. Based on the results gathered, it is concluded that not all the slightly electron-dense spherical inclusions are PHB granules in Synechocystis sp. PCC 6803. This result is potentially applicable to other cyanobacteria. Alternate assignments for these inclusions are discussed.

Final Techno-Economic Analysis of 550 MWe Supercritical PC Power Plant CO₂ Capture with Linde-BASF Advanced PCC Technology

Energy Technology Data Exchange (ETDEWEB)

Bostick, Devin [Linde LLC, Murray Hill, NJ (United States); Stoffregen, Torsten [Linde AG Linde Engineering Division, Dresden (Germany); Rigby, Sean [BASF Corporation, Houston, TX (United States)

2017-01-09

This topical report presents the techno-economic evaluation of a 550 MWe supercritical pulverized coal (PC) power plant utilizing Illinois No. 6 coal as fuel, integrated with 1) a previously presented (for a subcritical PC plant) Linde-BASF post-combustion CO₂ capture (PCC) plant incorporating BASF’s OASE® blue aqueous amine-based solvent (LB1) [Ref. 6] and 2) a new Linde-BASF PCC plant incorporating the same BASF OASE® blue solvent that features an advanced stripper interstage heater design (SIH) to optimize heat recovery in the PCC process. The process simulation and modeling for this report is performed using Aspen Plus V8.8. Technical information from the PCC plant is determined using BASF’s proprietary thermodynamic and process simulation models. The simulations developed and resulting cost estimates are first validated by reproducing the results of DOE/NETL Case 12 representing a 550 MWe supercritical PC-fired power plant with PCC incorporating a monoethanolamine (MEA) solvent as used in the DOE/NETL Case 12 reference [Ref. 2]. The results of the techno-economic assessment are shown comparing two specific options utilizing the BASF OASE® blue solvent technology (LB1 and SIH) to the DOE/NETL Case 12 reference. The results are shown comparing the energy demand for PCC, the incremental fuel requirement, and the net higher heating value (HHV) efficiency of the PC power plant integrated with the PCC plant. A comparison of the capital costs for each PCC plant configuration corresponding to a net 550 MWe power generation is also presented. Lastly, a cost of electricity (COE) and cost of CO₂ captured assessment is shown illustrating the substantial cost reductions achieved with the Linde-BASF PCC plant utilizing the advanced SIH configuration in combination with BASF’s OASE® blue solvent technology as compared to the DOE/NETL Case 12 reference. The key factors contributing to the reduction of COE and the cost of CO₂ captured

The study of desiccation-tolerance in drying leaves of the desiccation-tolerant grass Sporobolus elongatus and the desiccation-sensitive grass Sporobolus pyramidalis.

Science.gov (United States)

Ghasempour, Hamid Reza; Kianian, Jahanbakheshe

2007-03-01

Hydrated leaves of the resurrection grass Sporobolus elongatus are not desiccation tolerant (DT), but moderate to severe drought stress can induce their DT with the leaves remain attach to drying intact plants. In vivo protein synthesis was studied with SDS-page of extracts of leaves of intact drying plants of S. elongatus (a desiccation-Tolerant grass (DT)) and S. pyramidalis (a desiccation-sensitive species (DS)). Free proline increased in drying leaves. Soluble sugar contents also increased with drying but were less than fully hydrated leaves at 8% RWC. Total protein also showed an increase with an exception at 8% RWC which showed a decrease. SDS-page of extracts of drying leaves of both DT and DS plants were studied as relative water contents (RWC) decreased. In first phase, DT species at 58% RWC (80-51% RWC range), two proteins increased in contents. In the second phase, at 8% (35-4% RWC range) two new bands increased and two bands decreased. In leaves of DS species some bands decreased as drying progressed. Also, as drying advanced free proline increased in DT species. Total protein increased as drying increased but at 8% RWC decreased. All data of results are consistent with current views about studied factors and their roles during drying and induction of desiccation tolerance in DT plants.

Synthesis of Hydroxyapatite using Precipitated Calcium Carbonate (PCC) from Limestones

Science.gov (United States)

Wardhani, Sri; Isnaini Azkiya, Noor; Triandi Tjahjanto, Rachmat

2018-01-01

Hydroxyapatite (HAp) is a material that widely applied in bone and teeth implant due to its biocompatibility and bioactivity. This material can be prepared from PCC by precipitation method using CaO and H3PO4 in ethanol. In this work, variations of phosphoric acid amount and aging time were investigated. The synthesized HAp was characterized by FT-IR, AAS, UV-Vis Spectrophotometer, PSA, SEM, and powder XRD. The results showed that the high concentration of calcium in PCC gives better yields in which PCC obtained from carbonation method has higher yield than that of caustic soda method. The determination of optimum phosphoric acid addition based on targeted Ca/P ratio (1.67) from HAp was obtained on the addition of 0.1271 mol phosphoric acid with Ca/P ratio of 1.66. The aging time gave significant effect to the particle size of synthesised HAp. The smallest particle size was obtained in aging time for 48 hours as high as 49.25 μm. FTIR spectra of the synthesized HAp show the presence of hydroxyl (-OH) group at 3438.8 cm-1, PO4 3- at 557.39 and 1035.7 cm-1, and CaO at 1413.72 cm-1. The synthesized HAp forms agglomeration solid based on the SEM analysis. The powder XRD data shows three highest peaks at 2θ i.e. 27.8296; 31.1037; and 34.3578 which corresponds to β-TCP (tricalcium phosphate) in accordance with JCPDS no.09-0169. The characteristic 2θ peak of hydroxyapatite with low intensity is observed from the synthesized HAp refer to the JCPDS data no. 09-0432.

Production of bioplastics and hydrogen gas by photosynthetic microorganisms

Science.gov (United States)

Yasuo, Asada; Masato, Miyake; Jun, Miyake

1998-03-01

Our efforts have been aimed at the technological basis of photosynthetic-microbial production of materials and an energy carrier. We report here accumulation of poly-(3-hydroxybutyrate) (PHB), a raw material of biodegradable plastics and for production of hydrogen gas, and a renewable energy carrier by photosynthetic microorganisms (tentatively defined as cyanobacteria plus photosynthetic bateria, in this report). A thermophilic cyanobacterium, Synechococcus sp. MA19 that accumulates PHB at more than 20% of cell dry wt under nitrogen-starved conditions was isolated and microbiologically identified. The mechanism of PHB accumulation was studied. A mesophilic Synechococcus PCC7942 was transformed with the genes encoding PHB-synthesizing enzymes from Alcaligenes eutrophus. The transformant accumulated PHB under nitrogen-starved conditions. The optimal conditions for PHB accumulation by a photosynthetic bacterium grown on acetate were studied. Hydrogen production by photosynthetic microorganisms was studied. Cyanobacteria can produce hydrogen gas by nitrogenase or hydrogenase. Hydrogen production mediated by native hydrogenase in cyanobacteria was revealed to be in the dark anaerobic degradation of intracellular glycogen. A new system for light-dependent hydrogen production was targeted. In vitro and in vivo coupling of cyanobacterial ferredoxin with a heterologous hydrogenase was shown to produce hydrogen under light conditions. A trial for genetic trasformation of Synechococcus PCC7942 with the hydrogenase gene from Clostridium pasteurianum is going on. The strong hydrogen producers among photosynthetic bacteria were isolated and characterized. Co-culture of Rhodobacter and Clostriumdium was applied to produce hydrogen from glucose. Conversely in the case of cyanobacteria, genetic regulation of photosynthetic proteins was intended to improve conversion efficiency in hydrogen production by the photosynthetic bacterium, Rhodobacter sphaeroides RV. A mutant acquired by

An easy and efficient permeabilization protocol for in vivo enzyme activity assays in cyanobacteria

DEFF Research Database (Denmark)

Rasmussen, Randi Engelberth; Erstad, Simon Matthé; Ramos Martinez, Erick Miguel

2016-01-01

microbial cell factories. Better understanding of the activities of enzymes involved in the central carbon metabolism would lead to increasing product yields. Currently cell-free lysates are the most widely used method for determination of intracellular enzyme activities. However, due to thick cell walls...... used directly in the assays, the permeabilized cells exhibited the enzyme activities that are comparable or even higher than those detected for cell-free lysates. Moreover, the permeabilized cells could be stored at -20 °C without losing the enzyme activities. The permeabilization process...... for permeabilization of the cyanobacteria Synechococcus sp. PCC 7002 and Synechocystis sp. PCC 6803, and determination of two intracellular enzymes, ribulose-1,5-bisphosphate carboxylase/decarboxylase (Rubisco) and glucose-6-phosphate dehydrogenase (G6PDH), that play pivotal roles in the central carbon metabolism...

Fine-scale distribution patterns of Synechococcus ecological diversity in the microbial mats of Mushroom Spring, Yellowstone National Park

DEFF Research Database (Denmark)

Becraft, E.; Cohan, F.; Kühl, Michael

2011-01-01

Past analyses of sequence diversity in high-resolution protein-encoding genes have identified putative ecological species of unicellular cyanobacteria in the genus Synechococcus, which are specialized to 60°C but not 65°C in Mushroom Spring microbial mats. Because these studies were limited to only...

Effects of fatty acid activation on photosynthetic production of fatty acid-based biofuels in Synechocystis sp. PCC6803

Directory of Open Access Journals (Sweden)

Gao Qianqian

2012-03-01

Full Text Available Abstract Background Direct conversion of solar energy and carbon dioxide to drop in fuel molecules in a single biological system can be achieved from fatty acid-based biofuels such as fatty alcohols and alkanes. These molecules have similar properties to fossil fuels but can be produced by photosynthetic cyanobacteria. Results Synechocystis sp. PCC6803 mutant strains containing either overexpression or deletion of the slr1609 gene, which encodes an acyl-ACP synthetase (AAS, have been constructed. The complete segregation and deletion in all mutant strains was confirmed by PCR analysis. Blocking fatty acid activation by deleting slr1609 gene in wild-type Synechocystis sp. PCC6803 led to a doubling of the amount of free fatty acids and a decrease of alkane production by up to 90 percent. Overexpression of slr1609 gene in the wild-type Synechocystis sp. PCC6803 had no effect on the production of either free fatty acids or alkanes. Overexpression or deletion of slr1609 gene in the Synechocystis sp. PCC6803 mutant strain with the capability of making fatty alcohols by genetically introducing fatty acyl-CoA reductase respectively enhanced or reduced fatty alcohol production by 60 percent. Conclusions Fatty acid activation functionalized by the slr1609 gene is metabolically crucial for biosynthesis of fatty acid derivatives in Synechocystis sp. PCC6803. It is necessary but not sufficient for efficient production of alkanes. Fatty alcohol production can be significantly improved by the overexpression of slr1609 gene.

Synechococcus nidulans from a thermoelectric coal power plant as a potential CO2 mitigation in culture medium containing flue gas wastes.

Science.gov (United States)

Duarte, Jessica Hartwig; Costa, Jorge Alberto Vieira

2017-10-01

This study evaluated the intermittent addition of coal flue gas wastes (CO 2 , SO 2 , NO and ash) into a Synechococcus nidulans LEB 115 cultivation in terms of growth parameters, CO 2 biofixation and biomass characterization. The microalga from a coal thermoelectric plant showed tolerance up to 200ppm SO 2 and NO, with a maximum specific growth rate of 0.18±0.03d - 1 . The addition of thermal coal ash to the cultivation increased the Synechococcus nidulans LEB 115 maximum cell growth by approximately 1.3 times. The best CO 2 biofixation efficiency was obtained with 10% CO 2 , 60ppm SO 2 , 100ppm NO and 40ppm ash (55.0±3.1%). The biomass compositions in the assays were similar, with approximately 9.8% carbohydrates, 13.5% lipids and 62.7% proteins. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cd2+ Effect on Photosynthetic Apparatus in Synechococcus elongatus and Spinach (Spinacia oleracea L.)

Czech Academy of Sciences Publication Activity Database

Nováková, Marie; Matějová, E.; Sofrová, D.

2004-01-01

Roč. 42, č. 3 (2004), s. 425-430 ISSN 0300-3604 R&D Projects: GA ČR GA525/02/0301 Institutional research plan: CEZ:AV0Z5038910 Keywords : cyanobacteria * heavy metals * photochemical activity Subject RIV: ED - Physiology Impact factor: 0.734, year: 2004

Molecular exploration of the highly radiation resistant cyanobacterium Arthrospira sp. PCC 8005

Science.gov (United States)

Badri, Hanène; Leys, Natalie; Wattiez, Ruddy

Arthrospira (Spirulina) is a photosynthetic cyanobacterium able to use sunlight to release oxygen from water and remove carbon dioxide and nitrate from water. In addition, it is suited for human consumption (edible). For these traits, the cyanobacterium Arthrospira sp. PCC 8005 was selected by the European Space Agency (ESA) as part of the life support system MELiSSA for recycling oxygen, water, and food during future long-haul space missions. However, during such extended missions, Arthrospira sp. PCC 8005 will be exposed to continuous artificial illumination and harmful cosmic radiation. The aim of this study was to investigate how Arthrospira will react and behave when exposed to such stress environment. The cyanobacterium Arthrospira sp. PCC 8005 was exposed to high gamma rays doses in order to unravel in details the response of this bacterium following such stress. Test results showed that after acute exposure to high doses of 60Co gamma radiation upto 3200 Gy, Arthrospira filaments were still able to restart photosynthesis and proliferate normally. Doses above 3200 Gy, did have a detrimental effect on the cells, and delayed post-irradiation proliferation. The photosystem activity, measured as the PSII quantum yield immediately after irradiation, decreased significantly at radiation doses above 3200 Gy. Likewise through pigment content analysis a significant decrease in phycocyanin was observed following exposure to 3200 Gy. The high tolerance of this bacterium to 60Co gamma rays (i.e. ca. 1000x more resistant than human cells for example) raised our interest to investigate in details the cellular and molecular mechanisms behind this amazing resistance. Optimised DNA, RNA and protein extraction methods and a new microarray chip specific for Arthrospira sp. PCC 8005 were developed to identify the global cellular and molecular response following exposure to 3200 Gy and 5000 Gy A total of 15,29 % and 30,18 % genes were found differentially expressed in RNA

Towards PCC for Concurrent and Distributed Systems (Work in Progress)

Science.gov (United States)

Henriksen, Anders S.; Filinski, Andrzej

2009-01-01

We outline some conceptual challenges in extending the PCC paradigm to a concurrent and distributed setting, and sketch a generalized notion of module correctness based on viewing communication contracts as economic games. The model supports compositional reasoning about modular systems and is meant to apply not only to certification of executable code, but also of organizational workflows.

Extensive Turnover of Compatible Solutes in Cyanobacteria Revealed by Deuterium Oxide (D_2O) Stable Isotope Probing

International Nuclear Information System (INIS)

Baran, Richard; Lau, Rebecca; Bowen, Benjamin P.; Diamond, Spencer; Jose, Nick

2017-01-01

In diverse environments on a global scale cyanobacteria are important primary producers of organic matter. Moreover, while mechanisms of CO_2 fixation are well understood, the distribution of the flow of fixed organic carbon within individual cells and complex microbial communities is less well characterized. To obtain a general overview of metabolism, we describe the use of deuterium oxide (D_2O) to measure deuterium incorporation into the intracellular metabolites of two physiologically diverse cyanobacteria: a terrestrial filamentous strain (Microcoleus vaginatus PCC 9802) and a euryhaline unicellular strain (Synechococcus sp. PCC 7002). D_2O was added to the growth medium during different phases of the diel cycle. Incorporation of deuterium into metabolites at nonlabile positions, an indicator of metabolite turnover, was assessed using liquid chromatography mass spectrometry. Expectedly, large differences in turnover among metabolites were observed. Some metabolites, such as fatty acids, did not show significant turnover over 12–24 h time periods but did turn over during longer time periods. Unexpectedly, metabolites commonly regarded to act as compatible solutes, including glutamate, glucosylglycerol, and a dihexose, showed extensive turnover compared to most other metabolites already after 12 h, but only during the light phase in the cycle. We observed extensive turnover and found it surprising considering the conventional view on compatible solutes as biosynthetic end points given the relatively slow growth and constant osmotic conditions. Our suggests the possibility of a metabolic sink for some compatible solutes (e.g., into glycogen) that allows for rapid modulation of intracellular osmolarity. To investigate this, uniformly "1"3C-labeled Synechococcus sp. PCC 7002 were exposed to "1"2C glucosylglycerol. Following metabolite extraction, amylase treatment of methanol-insoluble polymers revealed "1"2C labeling of glycogen. Overall, our work shows that D_2

Distribución geográfica, prevalencia e intensidad de las infecciones de Gregarina ronderosi (Eugregarinorida: Gregarinidae en Dichroplus elongatus (Orthoptera: Acrididae

Directory of Open Access Journals (Sweden)

Christian Bardi

2016-01-01

Full Text Available regarina ronderosi es un parásito obligado del tracto digestivo del acrídido plaga Dichroplus elongatus y una de las únicas dos eugregarinas de acrídidos argentinos descriptas con su ciclo de vida completo. Dada la falta de conocimiento acerca de aspectos epizootiológicos fundamentales de las infecci- ones causadas por eugregarinas en acrídidos de Argentina, el objetivo de esta contribución es iniciar el registro de la distribución geográfica de G. ronderosi en la región Pampeana, su prevalencia natural y la intensidad de las infecciones en condiciones naturales. Para ello, se colectaron ejemplares de D. elongatus (2008 – 2012 en distintos puntos de la región Pampeana. Se obtuvieron y analizaron un total de 4084 ejemplares provenientes de cuarenta y dos localidades. La prevalen- cia promedio de G. ronderosi para el total de localidades con presencia (diecisiete localidades fue de 29,7 ± EE 6,6% (n = 1071. El total de individuos infectados (n = 396 fue categorizado respecto de la intensidad de las infecciones: tres (0,8% presentaron infecciones muy fuertes, ochenta (20% fuerte, doscientos diez (53% moderadas y ciento tres (26% infecciones leves. Se ha ampliado la distribución ge- ográfica conocida, se han registrado prevalencias elevadas que sugieren la ocur - rencia de epizootias y se han registrado por primera vez en condiciones naturales infecciones de G. ronderosi categorizadas como Fuertes y Muy Fuertes.

The effect of coatings and coating weight by two types of PCC on barrier and optical properties and roughness of paper

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rouzbeh asadi khansari

2017-08-01

Full Text Available The objective of this work is to investigate the use of PCC, and the impact of its coating weight on paper coating. In this study, two base papers from Mazandaran Wood and Paper Industries (APC and NS, and two coating compositions with the solid content of 25% containing PCC filler (100 parts, PVA binder (14 parts and dispersant (1 part were used. The first composition included PCC B102 for opacity increment, and the second one PCC 9020 for the improvement of brightness. Two rod RDS14 and RDS30 were used for different coating weights. After coating, the treated samples were dried in room conditions at air temperature of 25◦C and relative humidity of 54%. Physical and optical properties of control and treated samples such as air resistance, thickness, Cobb60, brightness, yellowness, opacity and roughness were determined. In comparison to the control group, all the treated samples showed improvement in brightness, opacity, yellowness and air resistance. By the two different formulations and two rods, paper roughness was increased, and the increment of water absorption was due to capillary development in coating texture. The analysis of variances showed that the usage of PCC 9020 had considerable effect on roughness of papers. In NS papers, change of PCC caused significant difference in brightness and roughness, but in APC papers did not. The change of coating rod in APC papers had significant effect on water absorption, brightness and opacity but did not show in NS.

Nostoc PCC7524, a cyanobacterium which contains five sequence-specific deoxyribonucleases

NARCIS (Netherlands)

Reaston, J.; Duybesteyn, M.G.C.; Waard, Adrian de

1982-01-01

Five nucleotide sequence-specific deoxyribonucleases present in cell-free extracts of the filamentous cyanobacterium Nostoc PCC7524 have been purified and characterized. One of these enzymes, designated Nsp(7524)I cleaves at a new kind of nucleotide sequence i.e. 5'-PuCATG λ Py-3'. The other four

Comparison of Chain-Length Preferences and Glucan Specificities of Isoamylase-Type α-Glucan Debranching Enzymes from Rice, Cyanobacteria, and Bacteria.

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Taiki Kobayashi

Full Text Available It has been believed that isoamylase (ISA-type α-glucan debranching enzymes (DBEs play crucial roles not only in α-glucan degradation but also in the biosynthesis by affecting the structure of glucans, although molecular basis on distinct roles of the individual DBEs has not fully understood. In an attempt to relate the roles of DBEs to their chain-length specificities, we analyzed the chain-length distribution of DBE enzymatic reaction products by using purified DBEs from various sources including rice, cyanobacteria, and bacteria. When DBEs were incubated with phytoglycogen, their chain-length specificities were divided into three groups. First, rice endosperm ISA3 (OsISA3 and Eschericia coli GlgX (EcoGlgX almost exclusively debranched chains having degree of polymerization (DP of 3 and 4. Second, OsISA1, Pseudomonas amyloderamosa ISA (PsaISA, and rice pullulanase (OsPUL could debranch a wide range of chains of DP≧3. Third, both cyanobacteria ISAs, Cyanothece ATCC 51142 ISA (CytISA and Synechococcus elongatus PCC7942 ISA (ScoISA, showed the intermediate chain-length preference, because they removed chains of mainly DP3-4 and DP3-6, respectively, while they could also react to chains of DP5-10 and 7-13 to some extent, respectively. In contrast, all these ISAs were reactive to various chains when incubated with amylopectin. In addition to a great variation in chain-length preferences among various ISAs, their activities greatly differed depending on a variety of glucans. Most strikingly, cyannobacteria ISAs could attack branch points of pullulan to a lesser extent although no such activity was found in OsISA1, OsISA3, EcoGlgX, and PsaISA. Thus, the present study shows the high possibility that varied chain-length specificities of ISA-type DBEs among sources and isozymes are responsible for their distinct functions in glucan metabolism.

Morphometry and growth of three .i.Synechococcus./i.-like picoplanktic cyanobacteria at different culture conditions

Czech Academy of Sciences Publication Activity Database

Jezberová, Jitka; Komárková, J.

2007-01-01

Roč. 578, č. 1 (2007), s. 17-27 ISSN 0018-8158. [Workshop of the International Association of Phytoplankton Taxonomy and Ecology (IAP) /14./. Sapanca, 01.09.2005-11.09.2005] R&D Projects: GA AV ČR(CZ) IBS6017004; GA ČR(CZ) GA206/05/0007 Grant - others:EU(XE) EVK2-1999-00213 Institutional research plan: CEZ:AV0Z60170517 Keywords : cell elongation * crossed gradients * cyanobacteria * Cyanobium * involution cells * light * morphometry * nutrients * Synechococcus * temperature Subject RIV: EE - Microbiology, Virology Impact factor: 1.201, year: 2007

Colour evaluation of a phycobiliprotein-rich extract obtained from Nostoc PCC9205 in acidic solutions and yogurt.

Science.gov (United States)

de O Moreira, Isabela; Passos, Thaís S; Chiapinni, Claudete; Silveira, Gabrielle K; Souza, Joana C M; Coca-Vellarde, Luis Guillermo; Deliza, Rosires; de Lima Araújo, Kátia G

2012-02-01

Phycobiliproteins are coloured proteins produced by cyanobacteria, which have several applications because of their colour properties. However, there is no available information about the colour stability of phycobiliproteins from Nostoc sp. in food systems. The aim of this work was to study the colour stability of a purple-coloured phycobiliprotein-rich extract from the cyanobacterium Nostoc PCC9205 in acidic solutions and yogurt. Variations of pH for Nostoc PCC9205 extract have shown stability for the L* (lightness) and a* (redness) indexes in the range 1.0-7.0. The b* index (blueness), however, increased at pH values below 4.0, indicating loss of the blue colour. The Nostoc PCC9205 extract was used as colorant in yogurt (pH 4.17) stored for 60 days. Instrumental colour analysis showed no changes for the L* and a* indexes during storage, whereas the b* index changed after 20 days of storage. A multiple comparison test showed colour instability after 20 days of storage. A hedonic scale test performed on the 60th day of storage showed acceptability of the product. The red component of the phycobiliprotein-rich extract from Nostoc PCC9205 presented an improved stability in acidic media and yogurt compared with the blue component of this extract. Copyright © 2011 Society of Chemical Industry.

Production of precipitated calcium carbonate from industrial byproduct slags; Saostetun kalsiumkarbonaatin tuotanto karbonaattivapaista kuonatuotteista (SLAG2PCC)

Energy Technology Data Exchange (ETDEWEB)

Zevenhoven, R. [Aabo Akademi, Turku (Finland). Heat Engineering Lab.; Teir, S.; Eloneva, S.; Savolahti, J. [Helsinki Univ. of Technology, Espoo (Finland). Energy Technology and Environmental Protection

2006-12-19

Production of precipitate calcium carbonate from industrial by- product slags-project, 'SLAG2PCC', is a spin-off from ClimBus technology programme CO{sub 2} Nordic Plus-project, financed by the Finnish Technology Agency Tekes and the Finnish Recovery Boiler Committee. 'SLAG2PCC'-project is financed by Tekes, Ruukki Productions, UPM Kymmene and Waertsilae Finland. The possibility to produce precipitated calcium carbonate, PCC, from carbonate free industrial by-products (slags), combined with binding of carbon dioxide for climate change mitigation is studied in this project. The suitability of a process found from the literature, in which calcium used for carbonation is dissolved from calcium silicates using acetic acid as a solvent, is investigated for the carbonation of slags from the steel industry. During the calcium extraction experiments performed in the CO2 Nordic Plus - project it was found out that calcium is rapidly extracted from blast furnace and basic oxygen furnace slags. Atmospheric carbonation of the solution containing the dissolved slag and acetic acid directly has not succeeded yet due to low pH of the solution. Addition of NaOH, to increase of the solution pH, resulted in calcium carbonate precipitate in atmospheric pressure. The future goal of the project is to optimize process conditions so that the formed calcium carbonate is suitable for use as PCC. (orig.)

Techniques for induction of premature chromosome condensation (PCC) by Calyculin-A and micronucleus assay for biodosimetry in Vietnam

International Nuclear Information System (INIS)

Pham Ngoc Duy; Tran Que; Hoang Hung Tien; Bui Thi Kim Luyen; Nguyen Thi Kim Anh; Ha Thi Ngoc Lien

2014-01-01

The International Atomic Energy Agency (IAEA) and World Health Organization are interested in biological dosimetry method for radiation emergency medicine currently. Some cytogenetic techniques such as premature chromosome condensation (PCC) induced by Calyculin-A and micronucleus (MN) assay are necessary to develop biodosimetry in Vietnam. In this study, we optimized the condition for MN assay with 6 µg/ml Cytochalasin-B concentration and 72.5 hours for peripheral lymphocyte blood culture. The optimization for PCC method is 50 nM Calyculin-A concentration for 45 minutes peripheral lymphocyte blood treatment. For samples exposed to 3.0 Gy gamma 60 Co (dose rate 0.0916 Gy/s), the frequency of MN is 19.02 ± 0.38%, NBP is 1.95 ± 0.28%, dicentric and ring is 41.43 ± 8.12% and frag and min is 63.33 ± 5.16%. For samples exposed to 6.0 Gy gamma 60 Co (dose rate 0.0916 Gy/s), the frequency of ring-PCC is 17.73 ± 2.46%, extra unite is 218.91± 7.58%, dicentric is 83.81 ± 1.09%, ring is 10.75 ± 1.74%, fragment and minute is 193.17 ± 13.10%. MN and ring-PCC are specific marker applying for biodosimetry. (author)

A Cluster of Five Genes Essential for the Utilization of Dihydroxamate Xenosiderophores in Synechocystis sp. PCC 6803.

Science.gov (United States)

Obando S, Tobias A; Babykin, Michael M; Zinchenko, Vladislav V

2018-05-21

The unicellular freshwater cyanobacterium Synechocystis sp. PCC 6803 is capable of using dihydroxamate xenosiderophores, either ferric schizokinen (FeSK) or a siderophore of the filamentous cyanobacterium Anabaena variabilis ATCC 29413 (SAV), as the sole source of iron in the TonB-dependent manner. The fecCDEB1-schT gene cluster encoding a siderophore transport system that is involved in the utilization of FeSK and SAV in Synechocystis sp. PCC 6803 was identified. The gene schT encodes TonB-dependent outer membrane transporter, whereas the remaining four genes encode the ABC-type transporter FecB1CDE formed by the periplasmic binding protein FecB1, the transmembrane permease proteins FecC and FecD, and the ATPase FecE. Inactivation of any of these genes resulted in the inability of cells to utilize FeSK and SAV. Our data strongly suggest that Synechocystis sp. PCC 6803 can readily internalize Fe-siderophores via the classic TonB-dependent transport system.

Transcript analysis of the extended hyp-operon in the cyanobacteria Nostoc sp. strain PCC 7120 and Nostoc punctiforme ATCC 29133

Science.gov (United States)

2011-01-01

Background Cyanobacteria harbor two [NiFe]-type hydrogenases consisting of a large and a small subunit, the Hup- and Hox-hydrogenase, respectively. Insertion of ligands and correct folding of nickel-iron hydrogenases require assistance of accessory maturation proteins (encoded by the hyp-genes). The intergenic region between the structural genes encoding the uptake hydrogenase (hupSL) and the accessory maturation proteins (hyp genes) in the cyanobacteria Nostoc PCC 7120 and N. punctiforme were analysed using molecular methods. Findings The five ORFs, located in between the uptake hydrogenase structural genes and the hyp-genes, can form a transcript with the hyp-genes. An identical genomic localization of these ORFs are found in other filamentous, N2-fixing cyanobacterial strains. In N. punctiforme and Nostoc PCC 7120 the ORFs upstream of the hyp-genes showed similar transcript level profiles as hupS (hydrogenase structural gene), nifD (nitrogenase structural gene), hypC and hypF (accessory hydrogenase maturation genes) after nitrogen depletion. In silico analyzes showed that these ORFs in N. punctiforme harbor the same conserved regions as their homologues in Nostoc PCC 7120 and that they, like their homologues in Nostoc PCC 7120, can be transcribed together with the hyp-genes forming a larger extended hyp-operon. DNA binding studies showed interactions of the transcriptional regulators CalA and CalB to the promoter regions of the extended hyp-operon in N. punctiforme and Nostoc PCC 7120. Conclusions The five ORFs upstream of the hyp-genes in several filamentous N2-fixing cyanobacteria have an identical genomic localization, in between the genes encoding the uptake hydrogenase and the maturation protein genes. In N. punctiforme and Nostoc PCC 7120 they are transcribed as one operon and may form transcripts together with the hyp-genes. The expression pattern of the five ORFs within the extended hyp-operon in both Nostoc punctiforme and Nostoc PCC 7120 is similar to

Antimicrobial and cytotoxic assessment of marine cyanobacteria - Synechocystis and Synechococcus.

Science.gov (United States)

Martins, R F; Ramos, M F; Herfindal, L; Sousa, J A; Skaerven, K; Vasconcelos, V M

2008-01-22

Aqueous extracts and organic solvent extracts of isolated marine cyanobacteria strains were tested for antimicrobial activity against a fungus, Gram-positive and Gram-negative bacteria and for cytotoxic activity against primary rat hepatocytes and HL-60 cells. Antimicrobial activity was based on the agar diffusion assay. Cytotoxic activity was measured by apoptotic cell death scored by cell surface evaluation and nuclear morphology. A high percentage of apoptotic cells were observed for HL-60 cells when treated with cyanobacterial organic extracts. Slight apoptotic effects were observed in primary rat hepatocytes when exposed to aqueous cyanobacterial extracts. Nine cyanobacteria strains were found to have antibiotic activity against two Gram-positive bacteria, Clavibacter michiganensis subsp. insidiosum and Cellulomonas uda. No inhibitory effects were found against the fungus Candida albicans and Gram-negative bacteria. Marine Synechocystis and Synechococcus extracts induce apoptosis in eukaryotic cells and cause inhibition of Gram-positive bacteria. The different activity in different extracts suggests different compounds with different polarities.

Antimicrobial and Cytotoxic Assessment of Marine Cyanobacteria - Synechocystis and Synechococcus

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Vitor M. Vasconcelos

2008-01-01

Full Text Available Aqueous extracts and organic solvent extracts of isolated marine cyanobacteria strains were tested for antimicrobial activity against a fungus, Gram-positive and Gram-negative bacteria and for cytotoxic activity against primary rat hepatocytes and HL-60 cells. Antimicrobial activity was based on the agar diffusion assay. Cytotoxic activity was measured by apoptotic cell death scored by cell surface evaluation and nuclear morphology. A high percentage of apoptotic cells were observed for HL-60 cells when treated with cyanobacterial organic extracts. Slight apoptotic effects were observed in primary rat hepatocytes when exposed to aqueous cyanobacterial extracts. Nine cyanobacteria strains were found to have antibiotic activity against two Gram-positive bacteria, Clavibacter michiganensis subsp. insidiosum and Cellulomonas uda. No inhibitory effects were found against the fungus Candida albicans and Gram-negative bacteria. Marine Synechocystis and Synechococcus extracts induce apoptosis in eukaryotic cells and cause inhibition of Gram-positive bacteria. The different activity in different extracts suggests different compounds with different polarities.

Assessment of Chemical and Physico-Chemical Properties of Cyanobacterial Lipids for Biodiesel Production

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Heizir F. De Castro

2013-07-01

Full Text Available Five non-toxin producing cyanobacterial isolates from the genera Synechococcus, Trichormus, Microcystis, Leptolyngbya and Chlorogloea were examined in terms of quantity and quality as lipid feedstock for biofuel production. Under the conditions used in this study, the biomass productivity ranged from 3.7 to 52.7 mg·L−1·day−1 in relation to dry biomass, while the lipid productivity varied between 0.8 and 14.2 mg·L−1·day−1. All cyanobacterial strains evaluated yielded lipids with similar fatty acid composition to those present in the seed oils successfully used for biodiesel synthesis. However, by combining biomass and lipid productivity parameters, the greatest potential was found for Synechococcus sp. PCC7942, M. aeruginosa NPCD-1 and Trichormus sp. CENA77. The chosen lipid samples were further characterized using Fourier Transform Infrared spectroscopy (FTIR, viscosity and thermogravimetry and used as lipid feedstock for biodiesel synthesis by heterogeneous catalysis.

ppGpp Controls Global Gene Expression in Light and in Darkness in S. elongatus

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Anna M. Puszynska

2017-12-01

Full Text Available The bacterial and plant stringent response involves production of the signaling molecules guanosine tetraphosphate and guanosine pentaphosphate ((pppGpp, leading to global reorganization of gene expression. The function of the stringent response has been well characterized in stress conditions, but its regulatory role during unstressed growth is less studied. Here, we demonstrate that (pppGpp-deficient strains of S. elongatus have globally deregulated biosynthetic capacity, with increased transcription rate, translation rate, and cell size in unstressed conditions in light and impaired viability in darkness. Synthetic restoration of basal guanosine tetraphosphate (ppGpp levels is sufficient to recover transcriptional balance and appropriate cell size in light and to rescue viability in light/dark conditions, but it is insufficient to enable efficient dark-induced transcriptional shutdown. Our work underscores the importance of basal ppGpp signaling for regulation of cyanobacterial physiology in the absence of stress and for viability in energy-limiting conditions, highlighting that basal (pppGpp level is essential in cyanobacteria in the environmental light/dark cycle.

The Transcriptomes of Xiphinema index and Longidorus elongatus Suggest Independent Acquisition of Some Plant Parasitism Genes by Horizontal Gene Transfer in Early-Branching Nematodes

Science.gov (United States)

Danchin, Etienne G.J.; Perfus-Barbeoch, Laetitia; Rancurel, Corinne; Thorpe, Peter; Da Rocha, Martine; Bajew, Simon; Neilson, Roy; Sokolova (Guzeeva), Elena; Da Silva, Corinne; Guy, Julie; Labadie, Karine; Esmenjaud, Daniel; Helder, Johannes; Jones, John T.

2017-01-01

Nematodes have evolved the ability to parasitize plants on at least four independent occasions, with plant parasites present in Clades 1, 2, 10 and 12 of the phylum. In the case of Clades 10 and 12, horizontal gene transfer of plant cell wall degrading enzymes from bacteria and fungi has been implicated in the evolution of plant parasitism. We have used ribonucleic acid sequencing (RNAseq) to generate reference transcriptomes for two economically important nematode species, Xiphinema index and Longidorus elongatus, representative of two genera within the early-branching Clade 2 of the phylum Nematoda. We used a transcriptome-wide analysis to identify putative horizontal gene transfer events. This represents the first in-depth transcriptome analysis from any plant-parasitic nematode of this clade. For each species, we assembled ~30 million Illumina reads into a reference transcriptome. We identified 62 and 104 transcripts, from X. index and L. elongatus, respectively, that were putatively acquired via horizontal gene transfer. By cross-referencing horizontal gene transfer prediction with a phylum-wide analysis of Pfam domains, we identified Clade 2-specific events. Of these, a GH12 cellulase from X. index was analysed phylogenetically and biochemically, revealing a likely bacterial origin and canonical enzymatic function. Horizontal gene transfer was previously shown to be a phenomenon that has contributed to the evolution of plant parasitism among nematodes. Our findings underline the importance and the extensiveness of this phenomenon in the evolution of plant-parasitic life styles in this speciose and widespread animal phylum. PMID:29065523

The Transcriptomes of Xiphinema index and Longidorus elongatus Suggest Independent Acquisition of Some Plant Parasitism Genes by Horizontal Gene Transfer in Early-Branching Nematodes.

Science.gov (United States)

Danchin, Etienne G J; Perfus-Barbeoch, Laetitia; Rancurel, Corinne; Thorpe, Peter; Da Rocha, Martine; Bajew, Simon; Neilson, Roy; Guzeeva, Elena Sokolova; Da Silva, Corinne; Guy, Julie; Labadie, Karine; Esmenjaud, Daniel; Helder, Johannes; Jones, John T; den Akker, Sebastian Eves-van

2017-10-23

Nematodes have evolved the ability to parasitize plants on at least four independent occasions, with plant parasites present in Clades 1, 2, 10 and 12 of the phylum. In the case of Clades 10 and 12, horizontal gene transfer of plant cell wall degrading enzymes from bacteria and fungi has been implicated in the evolution of plant parasitism. We have used ribonucleic acid sequencing (RNAseq) to generate reference transcriptomes for two economically important nematode species, Xiphinema index and Longidorus elongatus , representative of two genera within the early-branching Clade 2 of the phylum Nematoda. We used a transcriptome-wide analysis to identify putative horizontal gene transfer events. This represents the first in-depth transcriptome analysis from any plant-parasitic nematode of this clade. For each species, we assembled ~30 million Illumina reads into a reference transcriptome. We identified 62 and 104 transcripts, from X. index and L. elongatus , respectively, that were putatively acquired via horizontal gene transfer. By cross-referencing horizontal gene transfer prediction with a phylum-wide analysis of Pfam domains, we identified Clade 2-specific events. Of these, a GH12 cellulase from X. index was analysed phylogenetically and biochemically, revealing a likely bacterial origin and canonical enzymatic function. Horizontal gene transfer was previously shown to be a phenomenon that has contributed to the evolution of plant parasitism among nematodes. Our findings underline the importance and the extensiveness of this phenomenon in the evolution of plant-parasitic life styles in this speciose and widespread animal phylum.

The Transcriptomes of Xiphinema index and Longidorus elongatus Suggest Independent Acquisition of Some Plant Parasitism Genes by Horizontal Gene Transfer in Early-Branching Nematodes

Directory of Open Access Journals (Sweden)

Etienne G.J. Danchin

2017-10-01

Full Text Available Nematodes have evolved the ability to parasitize plants on at least four independent occasions, with plant parasites present in Clades 1, 2, 10 and 12 of the phylum. In the case of Clades 10 and 12, horizontal gene transfer of plant cell wall degrading enzymes from bacteria and fungi has been implicated in the evolution of plant parasitism. We have used ribonucleic acid sequencing (RNAseq to generate reference transcriptomes for two economically important nematode species, Xiphinema index and Longidorus elongatus, representative of two genera within the early-branching Clade 2 of the phylum Nematoda. We used a transcriptome-wide analysis to identify putative horizontal gene transfer events. This represents the first in-depth transcriptome analysis from any plant-parasitic nematode of this clade. For each species, we assembled ~30 million Illumina reads into a reference transcriptome. We identified 62 and 104 transcripts, from X. index and L. elongatus, respectively, that were putatively acquired via horizontal gene transfer. By cross-referencing horizontal gene transfer prediction with a phylum-wide analysis of Pfam domains, we identified Clade 2-specific events. Of these, a GH12 cellulase from X. index was analysed phylogenetically and biochemically, revealing a likely bacterial origin and canonical enzymatic function. Horizontal gene transfer was previously shown to be a phenomenon that has contributed to the evolution of plant parasitism among nematodes. Our findings underline the importance and the extensiveness of this phenomenon in the evolution of plant-parasitic life styles in this speciose and widespread animal phylum.

[Growth and metabolite production of the marine cyanobacterium Synechococcus sp. (Chroococcales) in function to irradiance].

Science.gov (United States)

Rosales-Loaiza, Néstor; Guevara, Miguel; Lodeiros, César; Morales, Ever

2008-06-01

Changes in salinity, temperature and irradiance during wet and dry seasons have induced metabolic versatility in cyanobacteria from saline environments. Cyanobacteria from these environments have biotechnological potential for the production of metabolites with pharmaceutical and industrial interest. We studied the growth, dry mass and metabolite production of the cyanobacterium Synechococcus sp. MOF-03 in function of irradiance (78, 156 and 234 micromol q m(-2) s(-1)). All batch cultures were maintained by triplicate in constant aeration, 12:12 h photoperiod, 30 +/- 2 degrees C and 35% per hundred. Maximum values of protein, carbohydrates and lipids, of 530.19 +/- 11.16, 408.94 +/- 4.27 and 56.20 +/- 1.17 microg ml(-1), respectively, were achieved at 78 micromol q m(-2) s(-1). Pigments, analyzed by HPLC, showed maximum values at 78 micromol q m(-2) s(-1) for chlorophyll a with 7.72 +/- 0.16 microg ml(-1), and at 234 micromol q m(-2) s(-1) for beta-carotene and zeaxanthin with 0.70 +/- 0.01 and 0.67 +/- 0.05 microg ml(-1). Chlorophyll a:beta-carotene ratio decreased from 17.15 to 6.91 at 78 and 234 micromol q m(-2) s(-'1); whereas beta-carotene:zeaxanthin ratio showed no changes between 78 and 156 micromol q m(-2) s(-1), around 1.21, and decreased at 234 micromol q m(-2) s(-1), to 1.04. Also, this cyanobacterium produced the greatest cell density and dry mass at 156 micromol q m(-2) s(-1), with 406.13 +/- 21.74 x l0(6) cell ml(-1) and 1.49 +/- 0.11 mg ml(-1), respectively. Exopolysaccharide production was stable between 156 y 234 micromol q m(-2) s(-1), around 110 microg ml(-1). This Synechococcus strain shows a great potential for the production of enriched biomass with high commercial value metabolites.

3D-nuclear heat generation in PCC-charcoal filter in TAPP-3 and 4

International Nuclear Information System (INIS)

Kaushal, Manish; Pradhan, A.S.; Kumar, A.N.

2006-01-01

This paper deals with the calculations of 3D nuclear heat generation profile in the charcoal filter and subsequently the commencement time of Primary Containment Cleanup (PCC) system of 540MWe Pressurized Heavy Water Reactor (PHWR). Fuel failure is predicted due to overheating of the fuel under loss of Coolant Accident (LOCA) without Emergency Core Cooling System (LOCA without ECCS). Subsequently fission product gasses along with water vapours are released to Reactor Building (RB) atmosphere. Plate-out and water trapping mechanism stabilizes the concentration of significant fission products i.e. radioiodines in about 4 hours before being circulated through charcoal filters of Containment Cleanup system. After cleaning up the RB atmosphere, it is discharged to outside atmosphere through stack. The isotopes of radioiodine emit beta and gamma radiations. Gamma radiations are partly stopped within the charcoal and heat is generated. The part of gamma radiations escaping the bed produce heat in the adjacent beds also. PCC system can be operated, after 4 hours of LOCA, based on radioiodine concentration in RB atmosphere. During iodine removal, the iodine concentration in the charcoal filter goes through a peak value. Maximum heat is generated in the filter if PCC fans stops eventually when iodine concentration in the filter is maximum. Analysis done by TRAFIC code indicates that the system can be commenced after 7 hrs of LOCA so that desorption temperature of charcoal is not reached. Accuracy in estimating heat generation rates in charcoal helps in deciding commencement of the system after LOCA

Synechococcus microscopy counts collected from CTD casts aboard the R/V ATLANTIS, from the euphotic zone of the Eastern Tropical South Pacific during February, 2010 (NODC Accession 0069125)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This cruise provides the opportunity to expand the database we are amassing on Synechococcus diversity and distribution for our NSF project "The role of iron (Fe) in...

Multiple ketolases involved in light regulation of canthaxanthin biosynthesis in Nostoc punctiforme PCC 73102.

Science.gov (United States)

Schöpf, Lotte; Mautz, Jürgen; Sandmann, Gerhard

2013-05-01

In the genome of Nostoc punctiforme PCC 73102, three functional β-carotene ketolase genes exist, one of the crtO and two of the crtW type. They were all expressed and their corresponding enzymes were functional inserting 4-keto groups into β-carotene as shown by functional pathway complementation in Escherichia coli. They all synthesized canthaxanthin but with different efficiencies. Canthaxanthin is the photoprotective carotenoid of N. punctiforme PCC 73102. Under high-light stress, its synthesis was enhanced. This was caused by up-regulation of the transcripts of two genes in combination. The first crtB-encoding phytoene synthase is the gate way enzyme of carotenogenesis resulting in an increased inflow into the pathway. The second was the ketolase gene crtW148 which in high light takes over β-carotene conversion into canthaxanthin from the other ketolases. The other ketolases were down-regulated under high-light conditions. CrtW148 was also exclusively responsible for the last step in 4-keto-myxoxanthophyll synthesis.

Transcription of the extended hyp-operon in Nostoc sp. strain PCC 7120

Science.gov (United States)

Agervald, Åsa; Stensjö, Karin; Holmqvist, Marie; Lindblad, Peter

2008-01-01

Background The maturation of hydrogenases into active enzymes is a complex process and e.g. a correctly assembled active site requires the involvement of at least seven proteins, encoded by hypABCDEF and a hydrogenase specific protease, encoded either by hupW or hoxW. The N2-fixing cyanobacterium Nostoc sp. strain PCC 7120 may contain both an uptake and a bidirectional hydrogenase. The present study addresses the presence and expression of hyp-genes in Nostoc sp. strain PCC 7120. Results RT-PCRs demonstrated that the six hyp-genes together with one ORF may be transcribed as a single operon. Transcriptional start points (TSPs) were identified 280 bp upstream from hypF and 445 bp upstream of hypC, respectively, demonstrating the existence of several transcripts. In addition, five upstream ORFs located in between hupSL, encoding the small and large subunits of the uptake hydrogenase, and the hyp-operon, and two downstream ORFs from the hyp-genes were shown to be part of the same transcript unit. A third TSP was identified 45 bp upstream of asr0689, the first of five ORFs in this operon. The ORFs are annotated as encoding unknown proteins, with the exception of alr0692 which is identified as a NifU-like protein. Orthologues of the four ORFs asr0689-alr0692, with a highly conserved genomic arrangement positioned between hupSL, and the hyp genes are found in several other N2-fixing cyanobacteria, but are absent in non N2-fixing cyanobacteria with only the bidirectional hydrogenase. Short conserved sequences were found in six intergenic regions of the extended hyp-operon, appearing between 11 and 79 times in the genome. Conclusion This study demonstrated that five ORFs upstream of the hyp-gene cluster are co-transcribed with the hyp-genes, and identified three TSPs in the extended hyp-gene cluster in Nostoc sp. strain PCC 7120. This may indicate a function related to the assembly of a functional uptake hydrogenase, hypothetically in the assembly of the small subunit of

6-Pyruvoyltetrahydropterin synthase orthologs of either a single or dual domain structure are responsible for tetrahydrobiopterin synthesis in bacteria.

Science.gov (United States)

Kong, Jin Sun; Kang, Ji-Youn; Kim, Hye Lim; Kwon, O-Seob; Lee, Kon Ho; Park, Young Shik

2006-09-04

6-Pyruvoyltetrahydropterin synthase (PTPS) catalyzes the second step of tetrahydrobiopterin (BH4) synthesis. We previously identified PTPS orthologs (bPTPS-Is) in bacteria which do not produce BH4. In this study we disrupted the gene encoding bPTPS-I in Synechococcus sp. PCC 7942, which produces BH4-glucoside. The mutant was normal in BH4-glucoside production, demonstrating that bPTPS-I does not participate in BH4 synthesis in vivo and bringing us a new PTPS ortholog (bPTPS-II) of a bimodular polypeptide. The recombinant Synechococcus bPTPS-II was assayed in vitro to show PTPS activity higher than human enzyme. Further computational analysis revealed the presence of mono and bimodular bPTPS-II orthologs mostly in green sulfur bacteria and cyanobacteria, respectively, which are well known for BH4-glycoside production. In summary we found new bacterial PTPS orthologs, having either a single or dual domain structure and being responsible for BH4 synthesis in vivo, thereby disclosing all the bacterial PTPS homologs.

Is the distribution of Prochlorococcus and Synechococcus ecotypes in the Mediterranean Sea affected by global warming?

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M. Ostrowski

2011-09-01

Full Text Available Biological communities populating the Mediterranean Sea, which is situated at the northern boundary of the subtropics, are often claimed to be particularly affected by global warming. This is indicated, for instance, by the introduction of (subtropical species of fish or invertebrates that can displace local species. This raises the question of whether microbial communities are similarly affected, especially in the Levantine basin where sea surface temperatures have significantly risen over the last 25 years (0.50 ± 0.11 °C in average per decade, P Prochlorococcus and Synechococcus, was examined during two cruises through both eastern and western Mediterranean Sea basins held in September 1999 (PROSOPE cruise and in June–July 2008 (BOUM cruise. Diversity was studied using dot blot hybridization with clade-specific 16S rRNA oligonucleotide probes and/or clone libraries of the 16S-23S ribosomal DNA Internal Transcribed Spacer (ITS region, with a focus on the abundance of clades that may constitute bioindicators of warm waters. During both cruises, the dominant Prochlorococcus clade in the upper mixed layer at all stations was HLI, a clade typical of temperate waters, whereas the HLII clade, the dominant group in (subtropical waters, was only present at very low concentrations. The Synechococcus community was dominated by clades I, III and IV in the northwestern waters of the Gulf of Lions and by clade III and groups genetically related to clades WPC1 and VI in the rest of the Mediterranean Sea. In contrast, only a few sequences of clade II, a group typical of warm waters, were observed. These data indicate that local cyanobacterial populations have not yet been displaced by their (subtropical counterparts.

A comparison of G2 phase radiation-induced chromatid break kinetics using calyculin-PCC with those obtained using colcemid block.

Science.gov (United States)

Bryant, Peter E; Mozdarani, Hossein

2007-09-01

To study the possible influence of cell-cycle delay on cells reaching mitosis during conventional radiation-induced chromatid break experiments using colcemid as a blocking agent, we have compared the chromatid break kinetics following a single dose of gamma rays (0.75 Gy) in metaphase CHO cells using calyculin-induced premature chromosome condensation (PCC), with those using colcemid block. Calyculin-induced PCC causes very rapid condensation of G2 cell chromosomes without the need for a cell to progress to mitosis, hence eliminating any effect of cell-cycle checkpoint on chromatid break frequency. We found that the kinetics of the exponential first-order decrease in chromatid breaks with time after irradiation was similar (not significantly different) between the two methods of chromosome condensation. However, use of the calyculin-PCC technique resulted in a slightly increased rate of disappearance of chromatid breaks and thus higher frequencies of breaks at 1.5 and 2.5 h following irradiation. We also report on the effect of the nucleoside analogue ara A on chromatid break kinetics using the two chromosome condensation techniques. Ara A treatment of cells abrogated the decrease in chromatid breaks with time, both using the calyculin-PCC and colcemid methods. We conclude that cell-cycle delay may be a factor determining the absolute frequency of chromatid breaks at various times following irradiation of cells in G2 phase but that the first-order disappearance of chromatid breaks with time and its abrogation by ara A are not significantly influenced by the G2 checkpoint.

The Anabaena sp. PCC 7120 Exoproteome: Taking a Peek outside the Box

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Paulo Oliveira

2015-01-01

Full Text Available The interest in examining the subset of proteins present in the extracellular milieu, the exoproteome, has been growing due to novel insights highlighting their role on extracellular matrix organization and biofilm formation, but also on homeostasis and development. The cyanobacterial exoproteome is poorly studied, and the role of cyanobacterial exoproteins on cell wall biogenesis, morphology and even physiology is largely unknown. Here, we present a comprehensive examination of the Anabaena sp. PCC 7120 exoproteome under various growth conditions. Altogether, 139 proteins belonging to 16 different functional categories have been identified. A large fraction (48% of the identified proteins is classified as “hypothetical”, falls into the “other categories” set or presents no similarity to other proteins. The evidence presented here shows that Anabaena sp. PCC 7120 is capable of outer membrane vesicle formation and that these vesicles are likely to contribute to the exoproteome profile. Furthermore, the activity of selected exoproteins associated with oxidative stress has been assessed, suggesting their involvement in redox homeostasis mechanisms in the extracellular space. Finally, we discuss our results in light of other cyanobacterial exoproteome studies and focus on the potential of exploring cyanobacteria as cell factories to produce and secrete selected proteins.

Crystallization and preliminary X-ray crystallographic studies of O-methyltransferase from Anabaena PCC 7120

International Nuclear Information System (INIS)

Li, Guoming; Tang, Zhenting; Meng, Geng; Dai, Kesheng; Zhao, Jindong; Zheng, Xiaofeng

2009-01-01

The O-methyltransferase (OMT) from the Anabaena PCC 7120 has been overexpressed in a soluble form in E. coli, purified and crystallized. The crystals belonged to space group C222 1 and diffracted to 2.4 Å resolution. O-Methyltransferase (OMT) is a ubiquitous enzyme that exists in bacteria, plants and humans and catalyzes a methyl-transfer reaction using S-adenosyl-l-methionine as a methyl donor and a wide range of phenolics as acceptors. To investigate the structure and function of OMTs, omt from Anabaena PCC 7120 was cloned into expression vector pET21a and expressed in a soluble form in Escherichia coli strain BL21 (DE3). The recombinant OMT protein was purified to homogeneity using a two-step strategy. Crystals of OMT that diffracted to a resolution of 2.4 Å were obtained using the hanging-drop vapour-diffusion method. The crystals belonged to space group C222 1 , with unit-cell parameters a = 131.620, b = 227.994, c = 150.777 Å, α = β = γ = 90°. There are eight molecules per asymmetric unit

Cyanobacterial diversity in extreme environments in Baja California, Mexico: a polyphasic study.

Science.gov (United States)

López-Cortés, A; García-Pichel, F; Nübel, U; Vázquez-Juárez, R

2001-12-01

Cyanobacterial diversity from two geographical areas of Baja California Sur, Mexico, were studied: Bahia Concepcion, and Ensenada de Aripez. The sites included hypersaline ecosystems, sea bottom, hydrothermal springs, and a shrimp farm. In this report we describe four new morphotypes, two are marine epilithic from Bahia Concepcion, Dermocarpa sp. and Hyella sp. The third, Geitlerinema sp., occurs in thermal springs and in shrimp ponds, and the fourth, Tychonema sp., is from a shrimp pond. The partial sequences of the 16S rRNA genes and the phylogenetic relationship of four cyanobacterial strains (Synechococcus cf. elongatus, Leptolyngbya cf. thermalis, Leptolyngbya sp., and Geitlerinema sp.) are also presented. Polyphasic studies that include the combination of light microscopy, cultures and the comparative analysis of 16S rRNA gene sequences provide the most powerful approach currently available to establish the diversity of these oxygenic photosynthetic microorganisms in culture and in nature.

Proximate composition, mineral content and fatty acid profile of two marine fishes from Cameroonian coast: Pseudotolithus typus (Bleeker, 1863 and Pseudotolithus elongatus (Bowdich, 1825

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J.M. Njinkoue

2016-10-01

Full Text Available Background: Knowledge of chemical composition of fish from Cameroon is poor. The genera Pseudotolithus are nutritionally and economically important in Cameroon. Thus the knowledge on their chemical composition could help in functional food elaboration. Purpose: In this study, Proximate composition, fatty acid profiles and mineral composition were determined in two fish species, Pseudotolithus typus and Pseudotolithus elongatus from Cameroonian coasts. Basic procedure: AOAC standard method was used. Fatty acids were identified by GC/MS as N-acylpyrolidides. Mineral compositions were determined by atomic absorption spectrophotometry for Ca, Na, K, Mg, Fe, Zn, Cu, Mn, and by UV spectrophotometry for phosphorus (P. Main finding: Results indicated that chemical composition was not similar in the two fish species. Results also showed that water is the main constituent in the edible parts and in the bones with 76.17% to 78.24% and 51.21% to 55.28% respectively. Pseudotolithus typus and Pseudotolithus elongatus were good sources of proteins with 16.17% and 13.4% respectively. All the fish analyzed for fat were lean with fat contents less than 0.5%. These species of fish were poor in ω6PUFA and were rich in ω3PUFA with about one third of total fatty acids. The main ω3 fatty acids were eicosapentaenoic acid (EPA and docosahexaenoic acid (DHA. The most abundant main elements were the potassium in the edible parts (1.39% and calcium in the bones (18.26%. The most abundant trace elements were Zn and Fe in the edible parts and in the bones. Principal conclusion: The Na/K ratio values and ω3 fatty acids contents suggest that consumption of these two fish species could be recommended to prevent cardiovascular diseases. Keywords: Proximal composition, Mineral content, Fatty acid profiles, Pseudotolithus typus, Pseudotolithus elongates

Flux Balance Analysis of Cyanobacterial Metabolism.The Metabolic Network of Synechocystis sp. PCC 6803

Czech Academy of Sciences Publication Activity Database

Knoop, H.; Gründel, M.; Zilliges, Y.; Lehmann, R.; Hoffmann, S.; Lockau, W.; Steuer, Ralf

2013-01-01

Roč. 9, č. 6 (2013), e1003081-e1003081 ISSN 1553-7358 R&D Projects: GA MŠk(CZ) EE2.3.20.0256 Institutional support: RVO:67179843 Keywords : SP STRAIN PCC-6803 * SP ATCC 51142 * photoautotrophic metabolism * anacystis-nidulans * reconstructions * pathway * plants * models * growth Subject RIV: EI - Biotechnology ; Bionics Impact factor: 4.829, year: 2013

Transcription of the extended hyp-operon in Nostoc sp. strain PCC 7120

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Lindblad Peter

2008-04-01

Full Text Available Abstract Background The maturation of hydrogenases into active enzymes is a complex process and e.g. a correctly assembled active site requires the involvement of at least seven proteins, encoded by hypABCDEF and a hydrogenase specific protease, encoded either by hupW or hoxW. The N2-fixing cyanobacterium Nostoc sp. strain PCC 7120 may contain both an uptake and a bidirectional hydrogenase. The present study addresses the presence and expression of hyp-genes in Nostoc sp. strain PCC 7120. Results RT-PCRs demonstrated that the six hyp-genes together with one ORF may be transcribed as a single operon. Transcriptional start points (TSPs were identified 280 bp upstream from hypF and 445 bp upstream of hypC, respectively, demonstrating the existence of several transcripts. In addition, five upstream ORFs located in between hupSL, encoding the small and large subunits of the uptake hydrogenase, and the hyp-operon, and two downstream ORFs from the hyp-genes were shown to be part of the same transcript unit. A third TSP was identified 45 bp upstream of asr0689, the first of five ORFs in this operon. The ORFs are annotated as encoding unknown proteins, with the exception of alr0692 which is identified as a NifU-like protein. Orthologues of the four ORFs asr0689-alr0692, with a highly conserved genomic arrangement positioned between hupSL, and the hyp genes are found in several other N2-fixing cyanobacteria, but are absent in non N2-fixing cyanobacteria with only the bidirectional hydrogenase. Short conserved sequences were found in six intergenic regions of the extended hyp-operon, appearing between 11 and 79 times in the genome. Conclusion This study demonstrated that five ORFs upstream of the hyp-gene cluster are co-transcribed with the hyp-genes, and identified three TSPs in the extended hyp-gene cluster in Nostoc sp. strain PCC 7120. This may indicate a function related to the assembly of a functional uptake hydrogenase, hypothetically in the

Komposit Nano TiO2 Dengan PCC, Zeolit atau Karbon Aktif Untuk Menurunkan Total Krom dan Zat Organik Pada Air Limbah Industri Penyamakan Kulit

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Bumiarto Nugroho Jati

2012-04-01

Full Text Available Telah dilakukan penelitian untuk menurunkan total krom dan zat organik pada limbah industri penyamakan kulit dengan menggunakan nano TiO2 yang dikompositkan dengan adsorben karbon aktif, zeolit, dan precipitated calcium carbonate (PCC dalam suatu reaktor fotokatalitik yang disusun secara batch dan dilengkapi dengan 6 buah lampu UV dan magnetic stirrer. Penurunan kadar krom total diukur dengan menggunakan Atomic Absorption Spectro-photometer (AAS dan penurunan zat organik dianalisa dengan menggunakan titrasi permanganatometri. Hasil penelitian menunjukkan pengolahan terbaik untuk penurunan kadar krom total adalah dengan menggunakan komposit TiO2:PCC = 8:2 yang dapat menurunkan total krom hampir 100% pada menit ke-170 dengan konsentrasi awal 214,35 mg/L. Untuk penurunan kadar zat organik, pengolahan terbaik dengan menggunakan komposit TiO2:PCC = 9:1 yang dapat menurunkan kadar zat organik hingga 100% pada menit ke-180. 

Diurnal Regulation of Cellular Processes in the Cyanobacterium Synechocystis sp. Strain PCC 6803: Insights from Transcriptomic, Fluxomic, and Physiological Analyses

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Rajib Saha

2016-05-01

Full Text Available Synechocystis sp. strain PCC 6803 is the most widely studied model cyanobacterium, with a well-developed omics level knowledgebase. Like the lifestyles of other cyanobacteria, that of Synechocystis PCC 6803 is tuned to diurnal changes in light intensity. In this study, we analyzed the expression patterns of all of the genes of this cyanobacterium over two consecutive diurnal periods. Using stringent criteria, we determined that the transcript levels of nearly 40% of the genes in Synechocystis PCC 6803 show robust diurnal oscillating behavior, with a majority of the transcripts being upregulated during the early light period. Such transcripts corresponded to a wide array of cellular processes, such as light harvesting, photosynthetic light and dark reactions, and central carbon metabolism. In contrast, transcripts of membrane transporters for transition metals involved in the photosynthetic electron transport chain (e.g., iron, manganese, and copper were significantly upregulated during the late dark period. Thus, the pattern of global gene expression led to the development of two distinct transcriptional networks of coregulated oscillatory genes. These networks help describe how Synechocystis PCC 6803 regulates its metabolism toward the end of the dark period in anticipation of efficient photosynthesis during the early light period. Furthermore, in silico flux prediction of important cellular processes and experimental measurements of cellular ATP, NADP(H, and glycogen levels showed how this diurnal behavior influences its metabolic characteristics. In particular, NADPH/NADP+ showed a strong correlation with the majority of the genes whose expression peaks in the light. We conclude that this ratio is a key endogenous determinant of the diurnal behavior of this cyanobacterium.

Modelling Pseudocalanus elongatus stage-structured population dynamics embedded in a water column ecosystem model for the northern North Sea

Science.gov (United States)

Moll, Andreas; Stegert, Christoph

2007-01-01

This paper outlines an approach to couple a structured zooplankton population model with state variables for eggs, nauplii, two copepodites stages and adults adapted to Pseudocalanus elongatus into the complex marine ecosystem model ECOHAM2 with 13 state variables resolving the carbon and nitrogen cycle. Different temperature and food scenarios derived from laboratory culture studies were examined to improve the process parameterisation for copepod stage dependent development processes. To study annual cycles under realistic weather and hydrographic conditions, the coupled ecosystem-zooplankton model is applied to a water column in the northern North Sea. The main ecosystem state variables were validated against observed monthly mean values. Then vertical profiles of selected state variables were compared to the physical forcing to study differences between zooplankton as one biomass state variable or partitioned into five population state variables. Simulated generation times are more affected by temperature than food conditions except during the spring phytoplankton bloom. Up to six generations within the annual cycle can be discerned in the simulation.

Unlocking the Constraints of Cyanobacterial Productivity: Acclimations Enabling Ultrafast Growth

Energy Technology Data Exchange (ETDEWEB)

Bernstein, Hans C.; McClure, Ryan S.; Hill, Eric A.; Markillie, Lye Meng; Chrisler, William B.; Romine, Margie F.; McDermott, Jason E.; Posewitz, Matthew C.; Bryant, Donald A.; Konopka, Allan E.; Fredrickson, James K.; Beliaev, Alexander S.

2016-07-26

Harnessing the metabolic potential of photosynthetic microbes for next-generation biotechnology objectives requires detailed scientific understanding of the physiological constraints and regulatory controls affecting carbon partitioning between biomass, metabolite storage pools, and bioproduct synthesis. We dissected the cellular mechanisms underlying the remarkable physiological robustness of the euryhaline unicellular cyanobacteriumSynechococcussp. strain PCC 7002 (Synechococcus7002) and identify key mechanisms that allow cyanobacteria to achieve unprecedented photoautotrophic productivities (~2.5-h doubling time). Ultrafast growth ofSynechococcus7002 was supported by high rates of photosynthetic electron transfer and linked to significantly elevated transcription of precursor biosynthesis and protein translation machinery. Notably, no growth or photosynthesis inhibition signatures were observed under any of the tested experimental conditions. Finally, the ultrafast growth inSynechococcus7002 was also linked to a 300% expansion of average cell volume. We hypothesize that this cellular adaptation is required at high irradiances to support higher cell division rates and reduce deleterious effects, corresponding to high light, through increased carbon and reductant sequestration.

IMPORTANCEEfficient coupling between photosynthesis and productivity is central to the development of biotechnology based on solar energy. Therefore, understanding the factors constraining maximum rates of carbon processing is necessary to identify regulatory mechanisms and devise strategies to overcome productivity constraints. Here, we interrogate the molecular mechanisms that operate at a systems level to allow cyanobacteria to achieve ultrafast growth. This was done by considering growth and photosynthetic kinetics with global transcription patterns. We have delineated

Responses of Synechocystis sp. PCC 6803 to heterologous biosynthetic pathways

DEFF Research Database (Denmark)

Vavitsas, Konstantinos; Rue, Emil Østergaard; Stefánsdóttir, Lára Kristín

2017-01-01

BACKGROUND: There are an increasing number of studies regarding genetic manipulation of cyanobacteria to produce commercially interesting compounds. The majority of these works study the expression and optimization of a selected heterologous pathway, largely ignoring the wholeness and complexity...... different compounds, the cyanogenic glucoside dhurrin and the diterpenoid 13R-manoyl oxide in Synechocystis PCC 6803. We used genome-scale metabolic modelling to study fluxes in individual reactions and pathways, and we determined the concentrations of key metabolites, such as amino acids, carotenoids...

In silico characterization and transcriptomic analysis of nif family genes from Anabaena sp. PCC7120.

Science.gov (United States)

Singh, Shilpi; Shrivastava, Alok Kumar

2017-10-01

In silico approaches in conjunction with morphology, nitrogenase activity, and qRT-PCR explore the impact of selected abiotic stressor such as arsenic, salt, cadmium, copper, and butachlor on nitrogen fixing (nif family) genes of diazotrophic cyanobacterium Anabaena sp. PCC7120. A total of 19 nif genes are present within the Anabaena genome that is involved in the process of nitrogen fixation. Docking studies revealed the interaction between these nif gene-encoded proteins and the selected abiotic stressors which were further validated through decreased heterocyst frequency, fragmentation of filaments, and downregulation of nitrogenase activity under these stresses indicating towards their toxic impact on nitrogen fixation potential of filamentous cyanobacterium Anabaena sp. PCC7120. Another appealing finding of this study is even though having similar binding energy and similar interacting residues between arsenic/salt and copper/cadmium to nif-encoded proteins, arsenic and cadmium are more toxic than salt and copper for nitrogenase activity of Anabaena which is crucial for growth and yield of rice paddy and soil reclamation.

Diversity of the marine picocyanobacteria Prochlorococcus and Synechococcus assessed by terminal restriction fragment length polymorphisms of 16S-23S rRNA internal transcribed spacer sequences Diversidad de las picocianobacterias marinas Prochlorococcus y Synechococcus por medio de polimorfismos de longitud de fragmentos de restricción terminal en secuencias del espaciador transcrito interno del ARNr 16S - 23S

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PARIS LAVIN

2008-12-01

Full Text Available In order to assess the appropriateness of the use of internal transcribed spacer (ITS sequences for the study of population genetics of marine cyanobacteria, we amplified and cloned the 16S rRNA gene plus the 16S-23S ITS regions of six strains of Prochlorococcus and Synechococcus. We analyzed them by denaturing gradient gel electrophoresis (DGGE and terminal restriction fragment length polymorphisms (T-RFLP. When using the standard application of these techniques, we obtained more than one band or terminal restriction fragment (T-RF per strain or cloned sequence. Reports in literature have suggested that these anomalies can result from the formation of secondary structures. Secondary structures of the ITS sequences of Prochlorococcus and Synechococcus strains were computationally modelled at the different temperatures that were used during the polymerase chain reaction (PCR. Modelling results predicted the existence of hairpin loops that would still be present at the extensión temperature; it is likely that these loops produced incomplete and single stranded PCR products. We modified the standard T-RFLP procedure by adding the labelled ITS primer in the last two cycles of the PCR reaction; this resulted, in most cases, in only one T-RF per ribotype. Application of this technique to a natural picoplankton community in marine waters off northern Chile, showed that it was possible to identify the presence, and determine the relative abundance, of several phylogenetic lineages within the genera Prochlorococcus and Synechococcus inhabiting the euphotic zone. Phylogenetic analysis of ITS sequences obtained by cloning and sequencing DNA from the same sample confirmed the presence of the different genotypes. With the proposed modification, T-RFLP profiles should therefore be suitable for studying the diversity of natural populations of cyanobacteria, and should become an important tool to study the factors influencing the genetic structure and

Live microbial cells adsorb Mg2+ more effectively than lifeless organic matter

Science.gov (United States)

Qiu, Xuan; Yao, Yanchen; Wang, Hongmei; Duan, Yong

2018-03-01

The Mg2+ content is essential in determining different Mg-CaCO3 minerals. It has been demonstrated that both microbes and the organic matter secreted by microbes are capable of allocating Mg2+ and Ca2+ during the formation of Mg-CaCO3, yet detailed scenarios remain unclear. To investigate the mechanism that microbes and microbial organic matter potentially use to mediate the allocation of Mg2+ and Ca2+ in inoculating systems, microbial mats and four marine bacterial strains ( Synechococcus elongatus, Staphylococcus sp., Bacillus sp., and Desulfovibrio vulgaris) were incubated in artificial seawater media with Mg/Ca ratios ranging from 0.5 to 10.0. At the end of the incubation, the morphology of the microbial mats and the elements adsorbed on them were analyzed using scanning electronic microscopy (SEM) and energy diffraction spectra (EDS), respectively. The content of Mg2+ and Ca2+ adsorbed by the extracellular polysaccharide substances (EPS) and cells of the bacterial strains were analyzed with atomic adsorption spectroscopy (AAS). The functional groups on the surface of the cells and EPS of S. elongatus were estimated using automatic potentiometric titration combined with a chemical equilibrium model. The results show that live microbial mats generally adsorb larger amounts of Mg2+ than Ca2+, while this rarely is the case for autoclaved microbial mats. A similar phenomenon was also observed for the bacterial strains. The living cells adsorb more Mg2+ than Ca2+, yet a reversed trend was observed for EPS. The functional group analysis indicates that the cell surface of S. elongatus contains more basic functional groups (87.24%), while the EPS has more acidic and neutral functional groups (83.08%). These features may be responsible for the different adsorption behavior of Mg2+ and Ca2+ by microbial cells and EPS. Our work confirms the differential Mg2+ and Ca2+ mediation by microbial cells and EPS, which may provide insight into the processes that microbes use to

Is the distribution of Prochlorococcus and Synechococcus ecotypes in the Mediterranean Sea affected by global warming?

Science.gov (United States)

Mella-Flores, D.; Mazard, S.; Humily, F.; Partensky, F.; Mahé, F.; Bariat, L.; Courties, C.; Marie, D.; Ras, J.; Mauriac, R.; Jeanthon, C.; Bendif, E. M.; Ostrowski, M.; Scanlan, D. J.; Garczarek, L.

2011-05-01

Biological communities populating the Mediterranean Sea, which is situated at the northern boundary of the subtropics, are often claimed to be particularly affected by global warming. This is indicated, for instance, by the introduction of (sub)tropical species of fish or invertebrates that can displace local species. This raises the question of whether microbial communities are similarly affected, especially in the Levantine basin where sea surface temperatures have risen in recent years. In this paper, the genetic diversity of the two most abundant members of the phytoplankton community, the picocyanobacteria Prochlorococcus and Synechococcus, was examined on a transect from the South coast of France to Cyprus in the summer of 2008 (BOUM cruise). Diversity was studied using dot blot hybridization with clade-specific 16S rRNA oligonucleotide probes and clone libraries of the 16S-23S ribosomal DNA Internal Transcribed Spacer (ITS) region. Data were compared with those obtained during the PROSOPE cruise held almost a decade earlier, with a focus on the abundance of clades that may constitute bioindicators of warm waters. During both cruises, the dominant Prochlorococcus clade in the upper mixed layer at all stations was HLI, a clade typical of temperate waters, whereas the HLII clade, the dominant group in (sub)tropical waters, was only present at very low concentrations. The Synechococcus community was dominated by clades I, III and IV in the northwestern waters of the Gulf of Lions and by clade III and groups genetically related to clades WPC1 and VI in the rest of the Mediterranean Sea. In contrast, only a few sequences of clade II, a group typical of warm waters, were observed. These data indicate that local cyanobacterial populations have not yet been displaced by their (sub)tropical counterparts. This is discussed in the context of the low phosphorus concentrations found in surface waters in the eastern Mediterranean basin, as this may constitute a barrier to

United States Air Force Research on Airfield Pavement Repairs Using Precast Portland Cement Concrete (PCC) Slabs (BRIEFING SLIDES)

National Research Council Canada - National Science Library

Saeed, Athar

2008-01-01

...) slab repairs using precast PCC slab panels. AFRL is leading the technology development by critically reviewing the research conducted to date in this arena by the Air Force and the highway and civil aviation agencies and adopting...

Coping with iron limitation: a metabolomic study of Synechocystis sp PCC 6803

Czech Academy of Sciences Publication Activity Database

Rivas-Ubach, A.; Poret-Peterson, A. T.; Penuelas, J.; Sardans, J.; Pérez-Trujillo, M.; Legido-Quigley, C.; Oravec, Michal; Urban, Otmar; Elser, J. J.

2018-01-01

Roč. 40, č. 2 (2018), č. článku 28. ISSN 0137-5881 R&D Projects: GA MŠk(CZ) LO1415; GA MŠk(CZ) LM2015061 Institutional support: RVO:86652079 Keywords : sp strain pcc-6803 * ocean acidification * unicellular cyanobacterium * marine-phytoplankton * foliar metabolomes * nitrogen-fixation * metal homeostasis * oxidative stress * pacific-ocean * responses * Metabolomics * Metallomics * Iron limitation * Cyanobacteria * Ecological stoichiometry Subject RIV: EH - Ecology, Behaviour OBOR OECD: Environmental sciences (social aspects to be 5.7) Impact factor: 1.364, year: 2016

Improved sugar-free succinate production by Synechocystis sp. PCC 6803 following identification of the limiting steps in glycogen catabolism

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Tomohisa Hasunuma

2016-12-01

Full Text Available Succinate produced by microorganisms can replace currently used petroleum-based succinate but typically requires mono- or poly-saccharides as a feedstock. The cyanobacterium Synechocystis sp. PCC6803 can produce organic acids such as succinate from CO2 not supplemented with sugars under dark anoxic conditions using an unknown metabolic pathway. The TCA cycle in cyanobacteria branches into oxidative and reductive routes. Time-course analyses of the metabolome, transcriptome and metabolic turnover described here revealed dynamic changes in the metabolism of Synechocystis sp. PCC6803 cultivated under dark anoxic conditions, allowing identification of the carbon flow and rate-limiting steps in glycogen catabolism. Glycogen biosynthesized from CO2 assimilated during periods of light exposure is catabolized to succinate via glycolysis, the anaplerotic pathway, and the reductive TCA cycle under dark anoxic conditions. Expression of the phosphoenolpyruvate (PEP carboxylase gene (ppc was identified as a rate-limiting step in succinate biosynthesis and this rate limitation was alleviated by ppc overexpression, resulting in improved succinate excretion. The sugar-free succinate production was further enhanced by the addition of bicarbonate. In vivo labeling with NaH13CO3 clearly showed carbon incorporation into succinate via the anaplerotic pathway. Bicarbonate is in equilibrium with CO2. Succinate production by Synechocystis sp. PCC6803 therefore holds significant promise for CO2 capture and utilization. Keywords: Autofermentation, Cyanobacteria, Dynamic metabolic profiling, Metabolomics, Succinate, Synechocystis

Integrity and activity of photosystem 2 complexes isolated from the thermophilic cyanobacterium Synechococcus elongatus using various detergents

Czech Academy of Sciences Publication Activity Database

Šetlíková, Eva; Sofrová, D.; Prášil, Ondřej; Budáč, Petr; Koblížek, Michal; Šetlík, Ivan

1999-01-01

Roč. 37, č. 2 (1999), s. 183-200 ISSN 0300-3604. [Regional Photosynthesis Workshop /2./. Lipno, 31.01.1999-03.02.1999] R&D Projects: GA ČR GA206/96/1266; GA ČR GA206/98/P110; GA MŠk VS96085; GA MŠk ME 138 Grant - others:NATO(EC) LG970388 Subject RIV: ED - Physiology Impact factor: 0.734, year: 1999

Estimating microalgae Synechococcus nidulans daily biomass concentration using neuro-fuzzy network

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Vitor Badiale Furlong

2013-02-01

Full Text Available In this study, a neuro-fuzzy estimator was developed for the estimation of biomass concentration of the microalgae Synechococcus nidulans from initial batch concentrations, aiming to predict daily productivity. Nine replica experiments were performed. The growth was monitored daily through the culture medium optic density and kept constant up to the end of the exponential phase. The network training followed a full 3³ factorial design, in which the factors were the number of days in the entry vector (3,5 and 7 days, number of clusters (10, 30 and 50 clusters and internal weight softening parameter (Sigma (0.30, 0.45 and 0.60. These factors were confronted with the sum of the quadratic error in the validations. The validations had 24 (A and 18 (B days of culture growth. The validations demonstrated that in long-term experiments (Validation A the use of a few clusters and high Sigma is necessary. However, in short-term experiments (Validation B, Sigma did not influence the result. The optimum point occurred within 3 days in the entry vector, 10 clusters and 0.60 Sigma and the mean determination coefficient was 0.95. The neuro-fuzzy estimator proved a credible alternative to predict the microalgae growth.

Single Molecule Spectroscopy on Photosynthetic Pigment-Protein Complexes

CERN Document Server

Jelezko, F; Schuler, S; Thews, E; Tietz, C; Wechsler, A; Wrachtrup, J

2001-01-01

Single molecule spectroscopy was applied to unravel the energy transfer pathway in photosynthetic pigment-protein complexes. Detailed analysis of excitation and fluorescence emission spectra has been made for peripheral plant antenna LHC II and Photosystem I from cyanobacterium Synechococcus elongatus. Optical transitions of individual pigments were resolved under nonselective excitation of antenna chlorophylls. High-resolution fluorescence spectroscopy of individual plant antenna LHC II indicates that at low temperatures, the excitation energy is localized on the red-most Chl a pool absorbing at 680 nm. More than one pigment molecule is responsible for the fluorescence emission of the LHC II trimer. The spectral lines of single Chl a molecules absorbing at 675 nm are broadened because of the Foerster energy transfer towards the red-most pigments. Low-temperature spectroscopy on single PS I trimers indicates that two subgroups of pigments, which are present in the red antenna pool, differ by the strength of t...

Preparation and HPLC isolation of L-[U-14C]tryptophan from enzyme hydrolysate labelled with 14C

International Nuclear Information System (INIS)

Novak, J.; Tintera, S.; Hromadkova, B.

1990-01-01

Tryptophan was obtained from biomass of the blue-green alga Synechococcus elongatus cultivated under 14 CO 2 . After partial purification, the protein fraction was subjected to enzymatic hydrolysis using pronase. Semipreparative isolation of L-[U- 14 C]tryptophan was accomplished on a HPLC column of Separon S Hema 1000 CM, 2% ethanol were added to the eluent, and a precolumn packed with the basic anion exchanger Spheron 1000 DEAE was used. Always after the passage of L-[U- 14 C]tryptophan, the precolumn was decoupled. The substance was collected in 96% ethanol. After removing the solvent by vacuum evaporation, the sample was analyzed on a column packed with Separon SIX C 18 in the eluent of 0.1M-NaH 2 PO 4 , 2% methanol. When the desired radiochemical purity was not attained, the sample was purified on Separon SIX C 18 using 2% methanol. The final radiochemical purity achieved by using this method is 98%. (P.A.). 5 figs., 2 tabs., 4 refs

Fluorescent minerals - A potential source of UV protection and visible light for the growth of green algae and cyanobacteria in extreme cosmic environments

Science.gov (United States)

Omairi, Tareq; Wainwright, Milton

2015-07-01

We propose that green algae (Chlorella variabilis and Dunaliella tertiolecta) and cyanobacteria (Synechococcus elongatus and Nostoc commune) can grow inside fluorescent rock minerals which convert damaging UV light to visible light, thereby allowing these organisms to survive and thrive in UV-rich environments without (or with limited) visible light, which would otherwise be inimical to them. The four microorganisms were incubated inside fluorescent rocks composed of fluorite, calcite and pyrite. The resultant growth was then measured following exposure to UV radiation, with the use of optical density and measurement of chlorophyll concentration. Results show that the microorganisms were shielded from harmful UV in these semi-transparent rocks, while at the same time benefiting from the fact that the minerals converted UV to visible light; this have been shown by a statistically significant increase in their growth, which although lower than when the cells were incubated in sunlight, was significantly higher than in controls incubated in the dark.

Estimating microalgae Synechococcus nidulans daily biomass concentration using neuro-fuzzy network Estimador neuro-fuzzy de concentração diária de biomassa da microalga Synechococcus nidulans

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Vitor Badiale Furlong

2013-02-01

Full Text Available In this study, a neuro-fuzzy estimator was developed for the estimation of biomass concentration of the microalgae Synechococcus nidulans from initial batch concentrations, aiming to predict daily productivity. Nine replica experiments were performed. The growth was monitored daily through the culture medium optic density and kept constant up to the end of the exponential phase. The network training followed a full 3³ factorial design, in which the factors were the number of days in the entry vector (3,5 and 7 days, number of clusters (10, 30 and 50 clusters and internal weight softening parameter (Sigma (0.30, 0.45 and 0.60. These factors were confronted with the sum of the quadratic error in the validations. The validations had 24 (A and 18 (B days of culture growth. The validations demonstrated that in long-term experiments (Validation A the use of a few clusters and high Sigma is necessary. However, in short-term experiments (Validation B, Sigma did not influence the result. The optimum point occurred within 3 days in the entry vector, 10 clusters and 0.60 Sigma and the mean determination coefficient was 0.95. The neuro-fuzzy estimator proved a credible alternative to predict the microalgae growth.Neste trabalho, foi construído um estimador neuro-fuzzy da concentração de biomassa da microalga Synechococcus nidulans a partir de concentrações iniciais da batelada, visando possibilitar a predição da produtividade. Nove experimentos em réplica foram realizados. O crescimento foi acompanhado diariamente pela transmitância do meio e mantido até o final da fase exponencial de crescimento. O treinamento das redes ocorreu segundo delineamento experimental 3³, os fatores foram o número de dias no vetor de entrada (3, 5 e 7 dias, o número de clusters (10, 30 e 50 clusters e o valor de abrandamento do filtro interno (Sigma (0,30, 0,45 e 0,60. A variável resposta foi o somatório do erro quadrático das validações. Estas possuíam 24 (A

Utility of Synechocystis sp. PCC glutaredoxin A as a platform to study high-resolution mutagenesis of proteins.

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David B Knaff

2013-11-01

Full Text Available Glutaredoxin from the cyanobacterium Synechocystis sp. PCC 6803 is a small protein, containing only 88 amino acids, that participates in a large number of redox reactions, serving both as an electron donor for enzyme-catalyzed reductions and as a regulator of diverse metabolic pathways. The crystal structures of glutaredoxins from several species have been solved, including the glutaredoxin A isoform from the cyanobacterium Synechocystis sp. PCC 6803. We have utilized the small size of Synechocystis glutaredoxin A and its propensity to form protein crystals that diffract to high resolution to explore a long-standing question in biochemistry; i.e., what are the effects of mutations on protein structure and function? Taking advantage of these properties, we have initiated a long-term educational project that would examine the structural and biochemical changes in glutaredoxin as a function of single-point mutational replacements. Here, we report some of the mutational effects that we have observed to date.

Physiology, Fe(II oxidation, and Fe mineral formation by a marine planktonic cyanobacterium grown under ferruginous conditions

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Elizabeth D. Swanner

2015-10-01

Full Text Available Evidence for Fe(II oxidation and deposition of Fe(III-bearing minerals from anoxic or redox-stratified Precambrian oceans has received support from decades of sedimentological and geochemical investigation of Banded Iron Formations (BIF. While the exact mechanisms of Fe(II oxidation remains equivocal, reaction with O2 in the marine water column, produced by cyanobacteria or early oxygenic phototrophs, was likely. In order to understand the role of cyanobacteria in the deposition of Fe(III minerals to BIF, we must first know how planktonic marine cyanobacteria respond to ferruginous (anoxic and Fe(II-rich waters in terms of growth, Fe uptake and homeostasis, and Fe mineral formation. We therefore grew the common marine cyanobacterium Synechococcus PCC 7002 in closed bottles that began anoxic, and contained Fe(II concentrations that span the range of possible concentrations in Precambrian seawater. These results, along with cell suspension experiments, indicate that Fe(II is likely oxidized by this strain via chemical oxidation with oxygen produced during photosynthesis, and not via any direct enzymatic or photosynthetic pathway. Imaging of the cell-mineral aggregates with scanning electron microscopy (SEM and confocal laser scanning microscopy (CLSM are consistent with extracellular precipitation of Fe(III (oxyhydroxide minerals, but that >10% of Fe(III sorbs to cell surfaces rather than precipitating. Proteomic experiments support the role of reactive oxygen species (ROS in Fe(II toxicity to Synechococcus PCC 7002. The proteome expressed under low Fe conditions included multiple siderophore biosynthesis and siderophore and Fe transporter proteins, but most siderophores are not expressed during growth with Fe(II. These results provide a mechanistic and quantitative framework for evaluating the geochemical consequences of perhaps life’s greatest metabolic innovation, i.e. the evolution and activity of oxygenic photosynthesis, in ferruginous

Purification, crystallization and preliminary X-ray diffraction of fluorescence recovery protein from Synechocystis PCC 6803

International Nuclear Information System (INIS)

Liu, Ting; Shuai, Yingli; Zhou, Honggang

2011-01-01

Fluorescence recovery protein from Synechocystis PCC 6803 plays a key role in the orange carotenoid protein-related photoprotective mechanism in cyanobacteria. The full-length form and a truncated form were overexpressed, purified and crystallized, and diffraction was observed to 2.75 Å resolution. Fluorescence recovery protein (FRP), which is encoded by the slr1964 gene in Synechocystis PCC 6803, plays a key role in the orange carotenoid protein-related photoprotective mechanism in cyanobacteria. As the crystal structure of FRP may provide information about the biological functions and mechanism of action of the protein, recombinant full-length FRP and a truncated form were overexpressed, purified and crystallized at 291 K using ethylene imine polymer as the precipitant. An FRP data set was collected to a resolution of 2.75 Å at low temperature (100 K). The crystal belonged to space group P4 1 2 1 2, with unit-cell parameters a = b = 61.9, c = 160.7 Å, α = β = γ = 90°. Assuming that the asymmetric unit contains three molecules, the Matthews coefficient was calculated to be 2.1 Å 3 Da −1

Localization and prediction of malignant potential in recurrent pheochromocytoma/paraganglioma (PCC/PGL) using 18F-FDG PET/CT.

Science.gov (United States)

Fikri, Ahmad Saad Fathinul; Kroiss, A; Ahmad, A Z F; Zanariah, H; Lau, W F E; Uprimny, C; Donnemiller, E; Kendler, D; Nordin, A J; Virgolini, I J

2014-06-01

To our knowledge, data are lacking on the role of 18F-FDG PET/CT in the localization and prediction of neuroendocrine tumors, in particular the pheochromocytoma/paraganglioma (PCC/PGL) group. To evaluate the role of 18F-FDG PET/CT in localizing and predicting the malignant potential of PCC/PGL. Twenty-three consecutive patients with a history of PCC/PGL, presenting with symptoms related to catecholamine excess, underwent 18F-FDG PET/CT. Final confirmation of the diagnosis was made using the composite references. PET/CT findings were analyzed on a per-lesion basis and a per-patient basis. Tumor SUVmax was analyzed to predict the dichotomization of patient endpoints for the local disease and metastatic groups. We investigated 23 patients (10 men, 13 women) with a mean age of 46.43 ± 3.70 years. Serum catecholamine levels were elevated in 82.60% of these patients. There were 136 sites (mean SUVmax: 16.39 ± 3.47) of validated disease recurrence. The overall sensitivities for diagnostic CT, FDG PET, and FDG PET/CT were 86.02%, 87.50%, and 98.59%, respectively. Based on the composite references, 39.10% of patients had local disease. There were significant differences in the SUVmax distribution between the local disease and metastatic groups; a significant correlation was noted when a SUVmax cut-off was set at 9.2 (Plocalization of recurrent tumors. Tumor SUVmax is a potentially useful predictor of malignant tumor potential. © The Foundation Acta Radiologica 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Inference of Interactions in Cyanobacterial-Heterotrophic Co-Cultures via Transcriptome Sequencing

Energy Technology Data Exchange (ETDEWEB)

Beliaev, Alex S.; Romine, Margaret F.; Serres, Margaret; Bernstein, Hans C.; Linggi, Bryan E.; Markillie, Lye Meng; Isern, Nancy G.; Chrisler, William B.; Kucek, Leo A.; Hill, Eric A.; Pinchuk, Grigoriy; Bryant, Donald A.; Wiley, H. S.; Fredrickson, Jim K.; Konopka, Allan

2014-04-29

We employed deep sequencing technology to identify transcriptional adaptation of the euryhaline unicellular cyanobacterium Synechococcus sp. PCC 7002 and the marine facultative aerobe Shewanella putrefaciens W3-18-1 to growth in a co-culture and infer the effect of carbon flux distributions on photoautotroph-heterotroph interactions. The overall transcriptome response of both organisms to co-cultivation was shaped by their respective physiologies and growth constraints. Carbon limitation resulted in the expansion of metabolic capacities which was manifested through the transcriptional upregulation of transport and catabolic pathways. While growth coupling occurred via lactate oxidation or secretion of photosynthetically fixed carbon, there was evidence of specific metabolic interactions between the two organisms. On one hand, the production and excretion of specific amino acids (methionine and alanine) by the cyanobacterium correlated with the putative downregulation of the corresponding biosynthetic machinery of Shewanella W3-18-1. On the other hand, the broad and consistent decrease of mRNA levels for many Fe-regulated Synechococcus 7002 genes during co-cultivation suggested increased Fe availability as well as more facile and energy-efficient mechanisms for Fe acquisition by the cyanobacterium. Furthermore, evidence pointed at potentially novel interactions between oxygenic photoautotrophs and heterotrophs related to the oxidative stress response as transcriptional patterns suggested that Synechococcus 7002 rather than Shewanella W3-18-1 provided scavenging functions for reactive oxygen species under co-culture conditions. This study provides an initial insight into the complexity of photoautotrophic-heterotrophic interactions and brings new perspectives of their role in the robustness and stability of the association.

Crecimiento y producción de metabolitos de la cianobacteria marina Synechococcus sp. (Chroococcales en función de la irradiancia

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Néstor Rosales-Loaiza

2008-06-01

Full Text Available Las cianobacterias de ambientes salinos presentan una versatilidad metabólica inducida por los cambios de salinidad, temperatura e irradiancia, durante los períodos de sequía y lluvias. Por ello es importante la búsqueda en estos ambientes de cianobacterias con potencial biotecnológico para la producción de metabolitos de interés farmacéutico e industrial. Se reporta el crecimiento, masa seca y producción de metabolitos de la cianobacteria Synechococcus sp. MOF-03 en función de la irradiancia (78, 156 y 234 µmol q m-2 s-1. Los cultivos discontinuos por triplicado, fueron mantenidos con aireación constante, fotoperiodo 12:12 h, 30 ±2ºC y a 35‰. Los máximos valores de proteínas, carbohidratos y lípidos de 530.19 ±11.16, 408.94 ±4.27 y 56.20 ±1.17 µg ml-1 respectivamente, fueron obtenidos a 78 µmol q m-2 s-1. Los pigmentos, analizados por HPLC, mostraron los máximos a 78 µmol q m-2 s-1 para clorofila a con 7.72 ±0.16 µg ml-1; y a 234 µmol q m-2 s-1 para ß-caroteno y zeaxantina con 0.70 ±0.01 and 0.67 ±0.05 µg ml-1. La relación clorofila a:ß-caroteno disminuyó de 17.15 hasta 6.91 a 78 y 234 µmol q m-2 s-1; mientras que la relación ß-caroteno:zeaxantina se mantuvo sin cambios entre 78 y 156 µmol q m-2 s-1, con cerca de 1.21 y disminuyó a 234 µmol q m-2 s-1 a 1.04. La cianobacteria produjo la mayor densidad celular y masa seca a 156 µmol q m-2 s-1, con 406.13 ±21.74 x106 cel ml-1 y 1.49 ±0.11 mg ml-1 respectivamente. La producción de exopolisacáridos se mantuvo alrededor de 110 µg ml-1 entre 156 y 234 µmol q m-2 s-1. Así, esta cepa de Synechococcus muestra un gran potencial para la producción de biomasa enriquecida con metabolitos de alto valor comercial.Growth and metabolite production of the marine cyanobacterium Synechococcus sp. (Chroococcales in function to irradiance. Changes in salinity, temperature and irradiance during wet and dry seasons have induced metabolic versatility in cyanobacteria

LOFT CIS analysis: 1''-PCC-76-A inside containment penetration S-1A. Internal technical report

International Nuclear Information System (INIS)

Nitzel, M.E.

1978-01-01

The stress analysis performed on the 1''-PCC-76-A piping system inside containment penetration S-1A is described. Deadweight, thermal expansion, and seismic loads were considered. Results of this analysis show that the subject piping system will meet ASME Boiler and Pressure Vessel Code, Section III, Class 2 requirements provided that supports S8 and S9 are installed as recommended

Arsenic Demethylation by a C·As Lyase in Cyanobacterium Nostoc sp. PCC 7120.

Science.gov (United States)

Yan, Yu; Ye, Jun; Xue, Xi-Mei; Zhu, Yong-Guan

2015-12-15

Arsenic, a ubiquitous toxic substance, exists mainly as inorganic forms in the environment. It is perceived that organoarsenicals can be demethylated and degraded into inorganic arsenic by microorganisms. Few studies have focused on the mechanism of arsenic demethylation in bacteria. Here, we investigated arsenic demethylation in a typical freshwater cyanobacterium Nostoc sp. PCC 7120. This bacterium was able to demethylate monomethylarsenite [MAs(III)] rapidly to arsenite [As(III)] and also had the ability to demethylate monomethylarsenate [MAs(V)] to As(III). The NsarsI encoding a C·As lyase responsible for MAs(III) demethylation was cloned from Nostoc sp. PCC 7120 and heterologously expressed in an As-hypersensitive strain Escherichia coli AW3110 (ΔarsRBC). Expression of NsarsI was shown to confer MAs(III) resistance through arsenic demethylation. The purified NsArsI was further identified and functionally characterized in vitro. NsArsI existed mainly as the trimeric state, and the kinetic data were well-fit to the Hill equation with K0.5 = 7.55 ± 0.33 μM for MAs(III), Vmax = 0.79 ± 0.02 μM min(-1), and h = 2.7. Both of the NsArsI truncated derivatives lacking the C-terminal 10 residues (ArsI10) or 23 residues (ArsI23) had a reduced ability of MAs(III) demethylation. These results provide new insights for understanding the important role of cyanobacteria in arsenic biogeochemical cycling in the environment.

Photojournalism: the assaults of PCC in the pages of Folha and the Estadão Fotojornalismo: os ataques do PCC nas páginas da Folha e do Estadão

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Paulo Cesar Boni

2007-01-01

Full Text Available This article addresses the photojournalistic coverage carried out by Folha de S.Paulo and O Estado de S. Paulo during the assaults of the First Command in the Capital (PCC in May 2006. The methods used here were those of technical deconstruction - to analyze the elements of photographic language in the construction of the message – and comparative analysis - to check the creation of meaning in those messages. Through these methodological procedures, it is inferred that Folha adopted a more sensationalistic feature with spectacularization of those images than Estadão, which adopted a more neutral and realistic posture in the view of the facts. Esse artigo aborda a cobertura fotojornalística realizada pela Folha de S.Paulo e pelo O Estado de S. Paulo durante os ataques do Primeiro Comando da Capital (PCC em maio de 2006. Os métodos utilizados foram o da desconstrução técnica – para análise dos elementos da linguagem fotográfica na construção da mensagem – e análise comparativa – para aferir a geração de sentido nas mensagens. Por esses procedimentos metodológicos, conclui que Folha assumiu um caráter mais sensacionalista, com espetacularização das imagens que o Estadão, que adotou uma postura mais neutra e realista diante dos fatos.

Metabolic Engineering of Light and Dark Biochemical Pathways in Wild-Type and Mutant Strains of Synechocystis PCC 6803 for Maximal, 24-Hour Production of Hydrogen Gas

Energy Technology Data Exchange (ETDEWEB)

Ely, Roger L.; Chaplen, Frank W.R.

2014-03-11

This project used the cyanobacterial species Synechocystis PCC 6803 to pursue two lines of inquiry, with each line addressing one of the two main factors affecting hydrogen (H2) production in Synechocystis PCC 6803: NADPH availability and O2 sensitivity. H2 production in Synechocystis PCC 6803 requires a very high NADPH:NADP+ ratio, that is, the NADP pool must be highly reduced, which can be problematic because several metabolic pathways potentially can act to raise or lower NADPH levels. Also, though the [NiFe]-hydrogenase in PCC 6803 is constitutively expressed, it is reversibly inactivated at very low O2 concentrations. Largely because of this O2 sensitivity and the requirement for high NADPH levels, a major portion of overall H2 production occurs under anoxic conditions in the dark, supported by breakdown of glycogen or other organic substrates accumulated during photosynthesis. Also, other factors, such as N or S limitation, pH changes, presence of other substances, or deletion of particular respiratory components, can affect light or dark H2 production. Therefore, in the first line of inquiry, under a number of culture conditions with wild type (WT) Synechocystis PCC 6803 cells and a mutant with impaired type I NADPH-dehydrogenase (NDH-1) function, we used H2 production profiling and metabolic flux analysis, with and without specific inhibitors, to examine systematically the pathways involved in light and dark H2 production. Results from this work provided rational bases for metabolic engineering to maximize photobiological H2 production on a 24-hour basis. In the second line of inquiry, we used site-directed mutagenesis to create mutants with hydrogenase enzymes exhibiting greater O2 tolerance. The research addressed the following four tasks: 1. Evaluate the effects of various culture conditions (N, S, or P limitation; light/dark; pH; exogenous organic carbon) on H2 production profiles of WT cells and an NDH-1 mutant; 2. Conduct metabolic flux analyses for

Seasonal evolution of cholorophyll-a and cyanobacteria (Prochlorococcus and Synechococcus on the northeast continental shelf of the Gulf of Cádiz: relation to thermohaline and nutrients fields

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Eleonora Anfuso

2013-01-01

Full Text Available The seasonal evolution of nutrients, chlorophyll-a (chl-a and cyanobacteria (Synechococcus and Prochlorococcus on the northeast continental shelf of the Gulf of Cádiz was observed during four cruises in summer and autumn 2006 and winter and spring 2007. Samples were collected to determine the distribution of chl-a and cyanobacteria abundance and to analyse their coupling with thermohaline and chemical properties in the gulf region. Surface nutrient distributions showed clear seasonal variability. Maximum levels were recorded for the entire study region during winter due to winter mixing and the strong influence of the Guadalquivir River and Bay of Cádiz outflow. Maximum chl-a levels were reached during spring for the entire region and for the entire water column. Minimum values of chl-a were observed during summer, under prevailing oligotrophic conditions, and winter when in spite of relatively high nutrient concentrations, phytoplankton growth was probably light-limited. The distribution of both cyanobacteria populations also varied seasonally in association with the oceanographic conditions. Prochlorococcus maximum cell abundance was observed at the sea surface during the four cruises, except in the northern region during summer. However, Synechococcus showed a maximum concentration at the sea surface in autumn and winter and at the subsurface chlorophyll maximum in autumn and spring.

Determination of the Glycogen Content in Cyanobacteria.

Science.gov (United States)

De Porcellinis, Alice; Frigaard, Niels-Ulrik; Sakuragi, Yumiko

2017-07-17

Cyanobacteria accumulate glycogen as a major intracellular carbon and energy storage during photosynthesis. Recent developments in research have highlighted complex mechanisms of glycogen metabolism, including the diel cycle of biosynthesis and catabolism, redox regulation, and the involvement of non-coding RNA. At the same time, efforts are being made to redirect carbon from glycogen to desirable products in genetically engineered cyanobacteria to enhance product yields. Several methods are used to determine the glycogen contents in cyanobacteria, with variable accuracies and technical complexities. Here, we provide a detailed protocol for the reliable determination of the glycogen content in cyanobacteria that can be performed in a standard life science laboratory. The protocol entails the selective precipitation of glycogen from the cell lysate and the enzymatic depolymerization of glycogen to generate glucose monomers, which are detected by a glucose oxidase-peroxidase (GOD-POD) enzyme coupled assay. The method has been applied to Synechocystis sp. PCC 6803 and Synechococcus sp. PCC 7002, two model cyanobacterial species that are widely used in metabolic engineering. Moreover, the method successfully showed differences in the glycogen contents between the wildtype and mutants defective in regulatory elements or glycogen biosynthetic genes.

Nitrogen Starvation Acclimation in Synechococcus elongatus: Redox-Control and the Role of Nitrate Reduction as an Electron Sink

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Alexander Klotz

2015-03-01

Full Text Available Nitrogen starvation acclimation in non-diazotrophic cyanobacteria is characterized by a process termed chlorosis, where the light harvesting pigments are degraded and the cells gradually tune down photosynthetic and metabolic activities. The chlorosis response is governed by a complex and poorly understood regulatory network, which converges at the expression of the nblA gene, the triggering factor for phycobiliprotein degradation. This study established a method that allows uncoupling metabolic and redox-signals involved in nitrogen-starvation acclimation. Inhibition of glutamine synthetase (GS by a precise dosage of l-methionine-sulfoximine (MSX mimics the metabolic situation of nitrogen starvation. Addition of nitrate to such MSX-inhibited cells eliminates the associated redox-stress by enabling electron flow towards nitrate/nitrite reduction and thereby, prevents the induction of nblA expression and the associated chlorosis response. This study demonstrates that nitrogen starvation is perceived not only through metabolic signals, but requires a redox signal indicating over-reduction of PSI-reduced electron acceptors. It further establishes a cryptic role of nitrate/nitrite reductases as electron sinks to balance conditions of over-reduction.

Nitrogen Starvation Acclimation in Synechococcus elongatus: Redox-Control and the Role of Nitrate Reduction as an Electron Sink

Science.gov (United States)

Klotz, Alexander; Reinhold, Edgar; Doello, Sofía; Forchhammer, Karl

2015-01-01

Nitrogen starvation acclimation in non-diazotrophic cyanobacteria is characterized by a process termed chlorosis, where the light harvesting pigments are degraded and the cells gradually tune down photosynthetic and metabolic activities. The chlorosis response is governed by a complex and poorly understood regulatory network, which converges at the expression of the nblA gene, the triggering factor for phycobiliprotein degradation. This study established a method that allows uncoupling metabolic and redox-signals involved in nitrogen-starvation acclimation. Inhibition of glutamine synthetase (GS) by a precise dosage of l-methionine-sulfoximine (MSX) mimics the metabolic situation of nitrogen starvation. Addition of nitrate to such MSX-inhibited cells eliminates the associated redox-stress by enabling electron flow towards nitrate/nitrite reduction and thereby, prevents the induction of nblA expression and the associated chlorosis response. This study demonstrates that nitrogen starvation is perceived not only through metabolic signals, but requires a redox signal indicating over-reduction of PSI-reduced electron acceptors. It further establishes a cryptic role of nitrate/nitrite reductases as electron sinks to balance conditions of over-reduction. PMID:25780959

Diversidade genética de três estoques de piapara (Leporinus elongatus, utilizando RAPD = Genetic diversity of three stocks of piapara (Leporinus elongatus, using RAPD

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Patrícia Cristina Gomes

2008-04-01

Full Text Available Recentemente a produção aquícola brasileira tem apresentado grandeprogresso. Dentre as espécies nativas cultivadas no Brasil, a piapara (Leporinus elongatus tem sido amplamente preconizada. Com objetivo de avaliar os programas de repovoamento, foram analisadas a variabilidade e a divergência genética de três estoques de piapara com a técnica de RAPD (Random Amplified Polymorphic. O primeiro estoque pertence à Estação de Aquicultura e Hidrologia da Duke Energy International (A; o segundo, à piscicultura de Rolândia (B e o terceiro, ao Programa de Repovoamento dos Rios do Paraná (C. Os dezprimers para RAPD utilizados produziram 105 fragmentos polimórficos, conferindo um polimorfismo de 98,1% para os três estoques avaliados. A porcentagem de locos polimórficos e índice de Shannon foi superior para o estoque A. Porém, todos valores foram elevados, indicando alta diversidade intrapopulacional. Os valores de Gst indicam que houvebaixa diferenciação genética entre os estoques A x B e moderada diferenciação entre os demais. O Nm foi maior entre os estoques A x B. A distância genética e o dendrograma indicam que os estoques A x B são menos distantes geneticamente.Latelly, aquiculture production in Brazil has made great strides. Among the native species cultivated in Brazil, piapara (Leporinus elogatus has been widely praised. With the objective of evaluating restocking programs, the variability and genetic divergence ofthree piapara stocks were analyzed using the RAPD (Random Amplified Polymorphic DNA technique. The first stock belongs to the Aquiculture and Hydrology Station of Duke Energy International (A; the second one belongs to a fish farm in the city of Rolândia(B; and the third to the River Restocking Program of Paraná (C. The ten primers used for RAPD produced 105 polymorphic loci, conferring a polymorphism of 98.1% for the three evaluated stocks. Polymorphic loci percentage and Shannon index were higher for stock A

Safety study of PCC 2140 and ALILOG 21 used as part of safety measurement systems

International Nuclear Information System (INIS)

Meriaux, Pierre; Adnot, Serge; Rayrolles, Catherine.

1978-03-01

The PCC 2140 and ALILOG 21 equipment may be used at C.E.A. or E.D.F., as part of safety measurement systems. In a study of a similar, but earlier equipment, it was noticed that certain types of failures caused the system to switch to the least sensitive measurement range, which was detrimental to safety. This report analyses failure modes leading to unsafe failures and evaluates the risks ran into taking in account tests during use [fr

Cyanobacterial biomass as carbohydrate and nutrient feedstock for bioethanol production by yeast fermentation

DEFF Research Database (Denmark)

Möllers, K Benedikt; Canella, D.; Jørgensen, Henning

2014-01-01

cyanobacterium Synechococcus sp. PCC 7002 was fermented using yeast into bioethanol. Results: The cyanobacterium accumulated a total carbohydrate content of about 60% of cell dry weight when cultivated under nitrate limitation. The cyanobacterial cells were harvested by centrifugation and subjected to enzymatic...... cyanobacteria or microalgae. Importantly, as well as fermentable carbohydrates, the cyanobacterial hydrolysate contained additional nutrients that promoted fermentation. This hydrolysate is therefore a promising substitute for the relatively expensive nutrient additives (such as yeast extract) commonly used...... hydrolysis using lysozyme and two alpha-glucanases. This enzymatic hydrolysate was fermented into ethanol by Saccharomyces cerevisiae without further treatment. All enzyme treatments and fermentations were carried out in the residual growth medium of the cyanobacteria with the only modification being that p...

Quantitative proteomics reveals dynamic responses of Synechocystis sp. PCC 6803 to next-generation biofuel butanol.

Science.gov (United States)

Tian, Xiaoxu; Chen, Lei; Wang, Jiangxin; Qiao, Jianjun; Zhang, Weiwen

2013-01-14

Butanol is a promising biofuel, and recent metabolic engineering efforts have demonstrated the use of photosynthetic cyanobacterial hosts for its production. However, cyanobacteria have very low tolerance to butanol, limiting the economic viability of butanol production from these renewable producing systems. The existing knowledge of molecular mechanism involved in butanol tolerance in cyanobacteria is very limited. To build a foundation necessary to engineer robust butanol-producing cyanobacterial hosts, in this study, the responses of Synechocystis PCC 6803 to butanol were investigated using a quantitative proteomics approach with iTRAQ - LC-MS/MS technologies. The resulting high-quality dataset consisted of 25,347 peptides corresponding to 1452 unique proteins, a coverage of approximately 40% of the predicted proteins in Synechocystis. Comparative quantification of protein abundances led to the identification of 303 differentially regulated proteins by butanol. Annotation and GO term enrichment analysis showed that multiple biological processes were regulated, suggesting that Synechocystis probably employed multiple and synergistic resistance mechanisms in dealing with butanol stress. Notably, the analysis revealed the induction of heat-shock protein and transporters, along with modification of cell membrane and envelope were the major protection mechanisms against butanol. A conceptual cellular model of Synechocystis PCC 6803 responses to butanol stress was constructed to illustrate the putative molecular mechanisms employed to defend against butanol stress. Copyright © 2012 Elsevier B.V. All rights reserved.

Effects of freshwater Synechococcus sp. cyanobacteria pH buffering on CaCO3 precipitation: Implications for CO2 sequestration

International Nuclear Information System (INIS)

Martinez, Raul E.; Weber, Sebastian; Grimm, Christian

2016-01-01

In the present study, a mixed-flow steady-state bio-reactor was designed to biomineralize CO 2 as a consequence of photosynthesis from active Synechococcus sp. Dissolved CO 2 , generated by constant air bubbling of inorganic and cyanobacteria stock solutions, was the only source of inorganic carbon. The release of hydroxide ion by cyanobacteria from photosynthesis maintained highly alkaline pH conditions. In the presence of Ca 2+ and carbonate species, this led to calcite supersaturation under steady state conditions. Ca 2+ remained constant throughout the experiments showing the presence of steady state conditions. Similarly, the Synechococcus sp. biomass concentration remained stable within uncertainty. A gradual pH decrease was observed for the highest Ca 2+ condition coinciding with the formation of CaCO 3 . The high degree of supersaturation, under steady-state conditions, contributed to the stabilization of calcite and maintained a constant driving force for the mineral nucleation and growth. For the highest Ca 2+ condition a fast crystal growth rate was consistent with rapid calcite precipitation as suggested further by affinity calculations. Although saturation state based kinetic precipitation models cannot accurately reflect the controls on crystal growth kinetics or reliably predict growth mechanisms, the relatively reaction orders obtained from modeling of calcite precipitation rates as function of decreasing carbonate concentration suggest that the precipitation occurred via surface-controlled rate determining reactions. These high reaction orders support in addition the hypothesis that crystal growth proceeded through complex surface controlled mechanisms. In conclusion, the steady state supersaturated conditions generated by a constant cyanobacteria biomass and metabolic activity strongly suggest that these microorganisms could be used for the development of efficient CO 2 sequestration methods in a controlled large-scale environment. - Highlights: �

Comparative Genomics of DNA Recombination and Repair in Cyanobacteria: Biotechnological Implications

Science.gov (United States)

Cassier-Chauvat, Corinne; Veaudor, Théo; Chauvat, Franck

2016-01-01

Cyanobacteria are fascinating photosynthetic prokaryotes that are regarded as the ancestors of the plant chloroplast; the purveyors of oxygen and biomass for the food chain; and promising cell factories for an environmentally friendly production of chemicals. In colonizing most waters and soils of our planet, cyanobacteria are inevitably challenged by environmental stresses that generate DNA damages. Furthermore, many strains engineered for biotechnological purposes can use DNA recombination to stop synthesizing the biotechnological product. Hence, it is important to study DNA recombination and repair in cyanobacteria for both basic and applied research. This review reports what is known in a few widely studied model cyanobacteria and what can be inferred by mining the sequenced genomes of morphologically and physiologically diverse strains. We show that cyanobacteria possess many E. coli-like DNA recombination and repair genes, and possibly other genes not yet identified. E. coli-homolog genes are unevenly distributed in cyanobacteria, in agreement with their wide genome diversity. Many genes are extremely well conserved in cyanobacteria (mutMS, radA, recA, recFO, recG, recN, ruvABC, ssb, and uvrABCD), even in small genomes, suggesting that they encode the core DNA repair process. In addition to these core genes, the marine Prochlorococcus and Synechococcus strains harbor recBCD (DNA recombination), umuCD (mutational DNA replication), as well as the key SOS genes lexA (regulation of the SOS system) and sulA (postponing of cell division until completion of DNA reparation). Hence, these strains could possess an E. coli-type SOS system. In contrast, several cyanobacteria endowed with larger genomes lack typical SOS genes. For examples, the two studied Gloeobacter strains lack alkB, lexA, and sulA; and Synechococcus PCC7942 has neither lexA nor recCD. Furthermore, the Synechocystis PCC6803 lexA product does not regulate DNA repair genes. Collectively, these findings

Mutation of the murC and murB Genes Impairs Heterocyst Differentiation in Anabaena sp. Strain PCC 7120

OpenAIRE

Videau, Patrick; Rivers, Orion S.; Ushijima, Blake; Oshiro, Reid T.; Kim, Min Joo; Philmus, Benjamin; Cozy, Loralyn M.

2016-01-01

To stabilize cellular integrity in the face of environmental perturbations, most bacteria, including cyanobacteria, synthesize and maintain a strong, flexible, three-dimensional peptidoglycan lattice. Anabaena sp. strain PCC 7120 is a filamentous cyanobacterium capable of differentiating morphologically distinct nitrogen-fixing heterocyst cells in a periodic pattern. While heterocyst development has been shown to require proper peptidoglycan remodeling, the role of peptidoglycan synthesis has...

Fluorescent minerals--A potential source of UV protection and visible light for the growth of green algae and cyanobacteria in extreme cosmic environments.

Science.gov (United States)

Omairi, Tareq; Wainwright, Milton

2015-07-01

We propose that green algae (Chlorella variabilis and Dunaliella tertiolecta) and cyanobacteria (Synechococcus elongatus and Nostoc commune) can grow inside fluorescent rock minerals which convert damaging UV light to visible light, thereby allowing these organisms to survive and thrive in UV-rich environments without (or with limited) visible light, which would otherwise be inimical to them. The four microorganisms were incubated inside fluorescent rocks composed of fluorite, calcite and pyrite. The resultant growth was then measured following exposure to UV radiation, with the use of optical density and measurement of chlorophyll concentration. Results show that the microorganisms were shielded from harmful UV in these semi-transparent rocks, while at the same time benefiting from the fact that the minerals converted UV to visible light; this have been shown by a statistically significant increase in their growth, which although lower than when the cells were incubated in sunlight, was significantly higher than in controls incubated in the dark. Copyright © 2015 The Committee on Space Research (COSPAR). Published by Elsevier Ltd. All rights reserved.

Cytochrome c6B of Synechococcus sp. WH 8102 – Crystal structure and basic properties of novel c6-like family representative

International Nuclear Information System (INIS)

Zatwarnicki, Pawel; Barciszewski, Jakub; Krzywda, Szymon; Jaskolski, Mariusz; Kolesinski, Piotr; Szczepaniak, Andrzej

2014-01-01

Highlights: • Crystal structure of cytochrome c 6B from Synechococcus sp. WH 8102 was solved. • Basic biophysical properties of cytochrome c 6B were determined. • Cytochrome c 6B exhibits similar architecture to cytochrome c 6 . • Organization of heme binding pocket of cytochrome c 6B differs from that of c 6 . • Midpoint potential of cytochrome c 6B is significantly lower than of cytochrome c 6 . - Abstract: Cytochromes c are soluble electron carriers of relatively low molecular weight, containing single heme moiety. In cyanobacteria cytochrome c 6 participates in electron transfer from cytochrome b 6 f complex to photosystem I. Recent phylogenetic analysis revealed the existence of a few families of proteins homologous to the previously mentioned. Cytochrome c 6A from Arabidopsis thaliana was identified as a protein responsible for disulfide bond formation in response to intracellular redox state changes and c 550 is well known element of photosystem II. However, function of cytochromes marked as c 6B , c 6C and c M as well as the physiological process in which they take a part still remain unidentified. Here we present the first structural and biophysical analysis of cytochrome from the c 6B family from mesophilic cyanobacteria Synechococcus sp. WH 8102. Purified protein was crystallized and its structure was refined at 1.4 Å resolution. Overall architecture of this polypeptide resembles typical I-class cytochromes c. The main features, that distinguish described protein from cytochrome c 6 , are slightly red-shifted α band of UV–Vis spectrum as well as relatively low midpoint potential (113.2 ± 2.2 mV). Although, physiological function of cytochrome c 6B has yet to be determined its properties probably exclude the participation of this protein in electron trafficking between b 6 f complex and photosystem I

A Toxin-Antitoxin System VapBC15 from Synechocystis sp. PCC 6803 Shows Distinct Regulatory Features

Directory of Open Access Journals (Sweden)

Qian Fei

2018-03-01

Full Text Available Type II toxin–antitoxin (TA systems play important roles in bacterial stress survival by regulating cell growth or death. They are highly abundant in cyanobacteria yet remain poorly characterized. Here, we report the identification and regulation of a putative type II TA system from Synechocystis PCC6803, VapBC15. The VapBC15 system is encoded by the chromosomal operon vapBC15. Exogenous expression of VapC15 dramatically arrested cell growth of Escherichia coli and reduced the numbers of colony-forming units (CFU. The VapC15 toxicity could be which was counteracted neutralized by simultaneous or delayed production of VapB15. Biochemical analysis demonstrated the formation of VapB15-VapC15 complexes by the physical interaction between VapB15 and VapC15. Notably, the VapB15 antitoxin up-regulated the transcription of the vapBC15 operon by directly binding to the promoter region, and the VapC15 toxin abolished the up-regulatory effect by destabilizing the binding. Moreover, VapB15 can be degraded by the proteases Lons and ClpXP2s from Synechocystis PCC6803, thus activating the latent toxicity of VapBC15. These findings suggest that VapBC15 represents a genuine TA system that utilizes a distinct mechanism to regulate toxin activity.

Analysis of carbohydrate storage granules in the diazotrophic cyanobacterium Cyanothece sp. PCC 7822

Energy Technology Data Exchange (ETDEWEB)

Welkie, David G. [Purdue Univ., West Lafayette, IN (United States); Sherman, Debra M. [Purdue Univ., West Lafayette, IN (United States); Chrisler, William B. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Orr, Galya [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Sherman, Louis A. [Purdue Univ., West Lafayette, IN (United States)

2013-10-19

The unicellular diazotrophic cyanobacteria of the genus Cyanothece demonstrate oscillations in nitrogenase activity and H₂ production when grown under 12h light-12h dark cycles. We established that Cyanothece sp. PCC 7822 allows for the construction of knock-out mutants and our objective was to improve the growth characteristics of this strain and to identify the nature of the intracellular storage granules. We report the physiological and morphological effects of reduction in nitrate and phosphate concentrations in BG-11 media on this strain. We developed a series of BG-11-derived growth media and monitored batch culture growth, nitrogenase activity and nitrogenase-mediated hydrogen production, culture synchronicity, and intracellular storage content. Reduction in NaNO3 and K₂HPO₄ concentrations from 17.6 and 0.23 mM to 4.41 and 0.06 mM, respectively, improved growth characteristics such as cell size and uniformity, and enhanced the rate of cell division. Cells grown in this low NP BG-11 were less complex, a parameter that related to the composition of the intracellular storage granules. Cells grown in low NP BG-11 had less polyphosphate, fewer polyhydroxybutyrate granules and many smaller granules became evident. Biochemical analysis and transmission electron microscopy using the histocytochemical PATO technique demonstrated that these small granules contained glycogen. The glycogen levels and the number of granules per cell correlated nicely with a 2.3 to 3.3-fold change from the minimum at L0 to the maximum at D0. The differences in granule morphology and enzymes between Cyanothece ATCC 51142 and Cyanothece PCC 7822 provide insights into the formation of large starch-like granules in some cyanobacteria.

Lack of Phosphatidylglycerol Inhibits Chlorophyll Biosynthesis at Multiple Sites and Limits Chlorophyllide Reutilization in Synechocystis sp Strain PCC 6803

Czech Academy of Sciences Publication Activity Database

Kopečná, Jana; Pilný, Jan; Krynická, Vendula; Tomčala, Aleš; Kis, M.; Gombos, Z.; Komenda, Josef; Sobotka, Roman

2015-01-01

Roč. 169, č. 2 (2015), s. 1307-1317 ISSN 0032-0889 R&D Projects: GA MŠk LO1416; GA MŠk EE2.3.30.0059; GA ČR GBP501/12/G055 Institutional support: RVO:61388971 ; RVO:60077344 Keywords : II REACTION-CENTER * PHOTOSYSTEM-II * SP PCC-6803 Subject RIV: CE - Biochemistry Impact factor: 6.280, year: 2015

Comparison of the rate constants for energy transfer in the light-harvesting protein, C-phycocyanin, calculated from Foerster`s theory and experimentally measured by time-resolved fluorescence spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Debreczeny, Martin Paul [Univ. of California, Berkeley, CA (United States)

1994-05-01

We have measured and assigned rate constants for energy transfer between chromophores in the light-harvesting protein C-phycocyanin (PC), in the monomeric and trimeric aggregation states, isolated from Synechococcus sp. PCC 7002. In order to compare the measured rate constants with those predicted by Fdrster`s theory of inductive resonance in the weak coupling limit, we have experimentally resolved several properties of the three chromophore types ({beta}{sub 155} {alpha}{sub 84}, {beta}{sub 84}) found in PC monomers, including absorption and fluorescence spectra, extinction coefficients, fluorescence quantum yields, and fluorescence lifetimes. The cpcB/C155S mutant, whose PC is missing the {beta}{sub 155} chromophore, was, useful in effecting the resolution of the chromophore properties and in assigning the experimentally observed rate constants for energy transfer to specific pathways.

Concerted changes in gene expression and cell physiology of the cyanobacterium Synechocystis sp. strain PCC 6803 during transitions between nitrogen and light-limited growth

NARCIS (Netherlands)

Aquirre von Wobeser, E.; Ibelings, B.W.; Bok, J.M.; Krasikov, V.; Huisman, J.; Matthijs, H.C.P.

2011-01-01

Physiological adaptation and genome-wide expression profiles of the cyanobacterium Synechocystis sp. strain PCC 6803 in response to gradual transitions between nitrogen-limited and light-limited growth conditions were measured in continuous cultures. Transitions induced changes in pigment

BMAA Inhibits Nitrogen Fixation in the Cyanobacterium Nostoc sp. PCC 7120

Science.gov (United States)

Berntzon, Lotta; Erasmie, Sven; Celepli, Narin; Eriksson, Johan; Rasmussen, Ulla; Bergman, Birgitta

2013-01-01

Cyanobacteria produce a range of secondary metabolites, one being the neurotoxic non-protein amino acid β-N-methylamino-L-alanine (BMAA), proposed to be a causative agent of human neurodegeneration. As for most cyanotoxins, the function of BMAA in cyanobacteria is unknown. Here, we examined the effects of BMAA on the physiology of the filamentous nitrogen-fixing cyanobacterium Nostoc sp. PCC 7120. Our data show that exogenously applied BMAA rapidly inhibits nitrogenase activity (acetylene reduction assay), even at micromolar concentrations, and that the inhibition was considerably more severe than that induced by combined nitrogen sources and most other amino acids. BMAA also caused growth arrest and massive cellular glycogen accumulation, as observed by electron microscopy. With nitrogen fixation being a process highly sensitive to oxygen species we propose that the BMAA effects found here may be related to the production of reactive oxygen species, as reported for other organisms. PMID:23966039

Preirradiation of medium induces a subsequent stimulation or inhibition of growth according to the physiological state in Synechococcus lividus in culture

International Nuclear Information System (INIS)

Conter, A.

1987-01-01

The proliferation of Synechococcus lividus cells grown in preirradiated medium was compared with the proliferation of cells grown in a shielded or freshly prepared medium. Aging of medium in a shielded chamber resulted in a slight inhibiting effect on growth in every phase of the cell cycle which was used. Preirradiation of medium resulted in a stimulation of growth observed on Day 7 in cultures inoculated with cells selected in the deceleration phase and an inhibition of growth in cultures inoculated with exponentially growing cells. Addition of catalase (100 U X ml-1) counteracted the stimulating effect but did not modify the inhibiting effect induced by preirradiated medium. Results demonstrated the indirect effect of low doses of irradiation, implying the presence of hydrogen peroxide in radiostimulation and other radioproducts in the inhibitory effect

Research of an effect of radiostarvation on the cellular cycle time of the thermophilic cyanophyte, (Synechococcus sp.)

International Nuclear Information System (INIS)

Roux, J.-C.; Gilet, Roland.

1980-12-01

An effect of radiostarvation (lowering of the background dose-rate of irradiation-in the experiments described here, lowering by a factor 5) was tried out on the growth of various liquid cultures of the blue-green alga Synechococcus sp. in conditions propitious, unpropitious and semi-propitious: continuous cultures maintained in exponential phase of growth and closed cultures with a bubbling of air-CO 2 mixture; closed cultures without any bubbling; closed cultures with bubbling of air. To follow the growth the best criterion is the study of the cellular density with an electronic counter; the pigment content and the protein contents are less accurate than the cellular counting. A great technical improvement enabled to grow several continuous cultures where the fluctuations of the doubling time were less than 1 hour for a doubling time of 12 hours. The statistical study of the results shows that the radiostarvation does not significantly change the doubling time in continuous cultures and it does not modify the growth and the plateau level of closed cultures [fr

The use of NH4+ rather than NO3- affects cell stoichiometry, C allocation, photosynthesis and growth in the cyanobacterium Synechococcus sp. UTEX LB 2380, only when energy is limiting.

Science.gov (United States)

Ruan, Zuoxi; Giordano, Mario

2017-02-01

The assimilation of N-NO 3 - requires more energy than that of N-NH 4 + . This becomes relevant when energy is limiting and may impinge differently on cell energy budget depending on depth, time of the day and season. We hypothesize that N-limited and energy-limited cells of the oceanic cyanobacterium Synechococcus sp. differ in their response to the N source with respect to growth, elemental stoichiometry and carbon allocation. Under N limitation, cells retained almost absolute homeostasis of elemental and organic composition, and the use of NH 4 + did not stimulate growth. When energy was limiting, however, Synechococcus grew faster in NH 4 + than in NO 3 - and had higher C (20%), N (38%) and S (30%) cell quotas. Furthermore, more C was allocated to protein, whereas the carbohydrate and lipid pool size did not change appreciably. Energy limitation also led to a higher photosynthetic rate relative to N limitation. We interpret these results as an indication that, under energy limitation, the use of the least expensive N source allowed a spillover of the energy saved from N assimilation to the assimilation of other nutrients. The change in elemental stoichiometry influenced C allocation, inducing an increase in cell protein, which resulted in a stimulation of photosynthesis and growth. © 2016 John Wiley & Sons Ltd.

The molecular dimension of microbial species: 1. Ecological distinctions among, and homogeneity within, putative ecotypes of Synechococcus inhabiting the cyanobacterial mat of Mushroom Spring, Yellowstone National Park

DEFF Research Database (Denmark)

Becraft, Eric D.; Wood, Jason M.; Rusch, Douglas B.

2015-01-01

Based on the Stable Ecotype Model, evolution leads to the divergence of ecologically distinct populations (e.g., with different niches and/or behaviors) of ecologically interchangeable membership. In this study, pyrosequencing was used to provide deep sequence coverage of Synechococcus psaA genes...... the PEs are ecologically distinct, the members of each ecotype are ecologically homogeneous. PEs responded differently to experimental perturbations of temperature and light, but the genetic variation within each PE was maintained as the relative abundances of PEs changed, further indicating that each...

An Integrative Approach to Energy, Carbon, and Redox Metabolism in the Cyanobacterium Synechocystis sp. PCC 6803. Special Report

Energy Technology Data Exchange (ETDEWEB)

Overbeek, R.

2003-06-30

The main objectives for the first year were to produce a detailed metabolic reconstruction of synechocystis sp. PCC 6803 especially in interrelated areas of photosynthesis, respiration, and central carbon metabolism to support a more complete understanding and modeling of this organism. Additionally, Integrated Genomics, Inc., provided detailed bioinformatic analysis of selected functional systems related to carbon and energy generation and utilization, and of the corresponding pathways, functional roles and individual genes to support wet lab experiments by collaborators.

BMAA Inhibits Nitrogen Fixation in the Cyanobacterium Nostoc sp. PCC 7120

Directory of Open Access Journals (Sweden)

Birgitta Bergman

2013-08-01

Full Text Available Cyanobacteria produce a range of secondary metabolites, one being the neurotoxic non-protein amino acid β-N-methylamino-L-alanine (BMAA, proposed to be a causative agent of human neurodegeneration. As for most cyanotoxins, the function of BMAA in cyanobacteria is unknown. Here, we examined the effects of BMAA on the physiology of the filamentous nitrogen-fixing cyanobacterium Nostoc sp. PCC 7120. Our data show that exogenously applied BMAA rapidly inhibits nitrogenase activity (acetylene reduction assay, even at micromolar concentrations, and that the inhibition was considerably more severe than that induced by combined nitrogen sources and most other amino acids. BMAA also caused growth arrest and massive cellular glycogen accumulation, as observed by electron microscopy. With nitrogen fixation being a process highly sensitive to oxygen species we propose that the BMAA effects found here may be related to the production of reactive oxygen species, as reported for other organisms.

Conserved Chloroplast Open-reading Frame ycf54 Is Required for Activity of the Magnesium Protoporphyrin Monomethylester Oxidative Cyclase in Synechocystis PCC 6803

Czech Academy of Sciences Publication Activity Database

Hollingshead, S.; Kopečná, Jana; Jackson, P. J.; Canniffe, D. P.; Davidson, P. A.; Dickman, M. J.; Sobotka, Roman; Hunter, C. N.

2012-01-01

Roč. 287, č. 33 (2012), s. 27823-27833 ISSN 0021-9258 R&D Projects: GA ČR GAP501/10/1000; GA MŠk(CZ) ED2.1.00/03.0110 Institutional support: RVO:61388971 Keywords : CHLOROPHYLL ISOCYCLIC RING * RHODOBACTER-SPHAEROIDES * SP PCC-6803 Subject RIV: CE - Biochemistry Impact factor: 4.651, year: 2012

Subcellular pigment distribution is altered under far-red light acclimation in cyanobacteria that contain chlorophyll f.

Science.gov (United States)

Majumder, Erica L-W; Wolf, Benjamin M; Liu, Haijun; Berg, R Howard; Timlin, Jerilyn A; Chen, Min; Blankenship, Robert E

2017-11-01

Far-Red Light (FRL) acclimation is a process that has been observed in cyanobacteria and algae that can grow solely on light above 700 nm. The acclimation to FRL results in rearrangement and synthesis of new pigments and pigment-protein complexes. In this study, cyanobacteria containing chlorophyll f, Synechococcus sp. PCC 7335 and Halomicronema hongdechloris, were imaged as live cells with confocal microscopy. H. hongdechloris was further studied with hyperspectral confocal fluorescence microscopy (HCFM) and freeze-substituted thin-section transmission electron microscopy (TEM). Under FRL, phycocyanin-containing complexes and chlorophyll-containing complexes were determined to be physically separated and the synthesis of red-form phycobilisome and Chl f was increased. The timing of these responses was observed. The heterogeneity and eco-physiological response of the cells was noted. Additionally, a gliding motility for H. hongdechloris is reported.

Structural studies of cyanobacterial PSII

International Nuclear Information System (INIS)

Da Fonseca, Paula Cristina Alves

2001-01-01

Photosystem II (PSII) is the photosynthetic transmembrane protein-pigment complex which utilises light energy to drive the splitting of water and release of oxygen, a unique reaction in biological systems. The determination of the structure of PSII at high resolution is required in order to understand its mechanisms of reaction. For this reason, methods have been developed to purify highly active PSII complexes from the thermophilic cyanobacterium Synechococcus elongate These complexes have been studied by high resolution electron microscopy, using both single particle analysis and electron crystallography. A 30A three-dimensional map of the cyanobacterial PSII complex was obtained by single particle analysis. The comparison of this map with structural data from the spinach PSII core dimer revealed that both complexes share similar overall size and shape. These data also allowed a discussion on the organisation and positioning of the extrinsic lumenal proteins within the cyanobacterial PSII complex. A Synechococcus elongatus PSII projection map, at a resolution of 20A, was determined by image processing of two-dimensional crystals formed by the in vitro reconstitution method. This was the first projection map obtained by electron crystallography of a cyanobacterial highly active PSII complex, with all the extrinsic subunits retained. The analysis of this map and its comparison with a 10A three-dimensional map recently obtained from the spinach PSII core dimer revealed a similar organisation of the main transmembrane subunits. Moreover, at the level of resolution of the present data it is possible to identify differences which can be related to the content and organisation of the small subunits forming the PSII complex from both organisms. Cytochrome b559, an important but incompletely understood PSII subunit, was purified and subjected to crystallisation trials in order to aid the interpretation of intermediate resolution PSII structural data. Small crystals were

A newly designed 45 to 60 mer oligonucleotide Agilent platform microarray for global gene expression studies of Synechocystis PCC6803: example salt stress experiment

NARCIS (Netherlands)

Aguirre von Wobeser, E.; Huisman, J.; Ibelings, B.; Matthijs, H.C.P.; Matthijs, H.C.P.

2005-01-01

A newly designed 45 to 60 mer oligonucleotide Agilent platform microarray for global gene expression studies of Synechocystis PCC6803: example salt stress experiment Eneas Aguirre-von-Wobeser 1, Jef Huisman1, Bas Ibelings2 and Hans C.P. Matthijs1 1 Universiteit van Amsterdam, Amsterdam, The

The NADPH thioredoxin reductase C functions as an electron donor to 2-Cys peroxiredoxin in a thermophilic cyanobacterium Thermosynechococcus elongatus BP-1

International Nuclear Information System (INIS)

Sueoka, Keigo; Yamazaki, Teruaki; Hiyama, Tetsuo; Nakamoto, Hitoshi

2009-01-01

An NADPH thioredoxin reductase C was co-purified with a 2-Cys peroxiredoxin by the combination of anion exchange chromatography and electroelution from gel slices after native PAGE from a thermophilic cyanobacterium Thermosynechococcus elongatus as an NAD(P)H oxidase complex induced by oxidative stress. The result provided a strong evidence that the NADPH thioredoxin reductase C interacts with the 2-Cys peroxiredoxin in vivo. An in vitro reconstitution assay with purified recombinant proteins revealed that both proteins were essential for an NADPH-dependent reduction of H 2 O 2 . These results suggest that the reductase transfers the reducing power from NADPH to the peroxiredoxin, which reduces peroxides in the cyanobacterium under oxidative stress. In contrast with other NADPH thioredoxin reductases, the NADPH thioredoxin reductase C contains a thioredoxin-like domain in addition to an NADPH thioredoxin reductase domain in the same polypeptide. Each domain contains a conserved CXYC motif. A point mutation at the CXYC motif in the NADPH thioredoxin reductase domain resulted in loss of the NADPH oxidation activity, while a mutation at the CXYC motif in the thioredoxin-like domain did not affect the electron transfer, indicating that this motif is not essential in the electron transport from NADPH to the 2-Cys peroxiredoxin.

HupW Protease Specifically Required for Processing of the Catalytic Subunit of the Uptake Hydrogenase in the Cyanobacterium Nostoc sp. Strain PCC 7120

Science.gov (United States)

Lindberg, Pia; Devine, Ellenor; Stensjö, Karin

2012-01-01

The maturation process of [NiFe] hydrogenases includes a proteolytic cleavage of the large subunit. We constructed a mutant of Nostoc strain PCC 7120 in which hupW, encoding a putative hydrogenase-specific protease, is inactivated. Our results indicate that the protein product of hupW selectively cleaves the uptake hydrogenase in this cyanobacterium. PMID:22020512

An integrative approach to energy, carbon, and redox metabolism in the cyanobacterium Synechocystis sp. PCC 6803

Energy Technology Data Exchange (ETDEWEB)

Overbeek, Ross; Fonstein, Veronika; Osterman, Andrei; Gerdes, Svetlana; Vassieva, Olga; Zagnitko, Olga; Rodionov, Dmitry

2005-02-15

The team of the Fellowship for Interpretation of Genomes (FIG) under the leadership of Ross Overbeek, began working on this Project in November 2003. During the previous year, the Project was performed at Integrated Genomics Inc. A transition from the industrial environment to the public domain prompted us to adjust some aspects of the Project. Notwithstanding the challenges, we believe that these adjustments had a strong positive impact on our deliverables. Most importantly, the work of the research team led by R. Overbeek resulted in the deployment of a new open source genomic platform, the SEED (Specific Aim 1). This platform provided a foundation for the development of CyanoSEED a specialized portal to comparative analysis and metabolic reconstruction of all available cyanobacterial genomes (Specific Aim 3). The SEED represents a new generation of software for genome analysis. Briefly, it is a portable and extendable system, containing one of the largest and permanently growing collections of complete and partial genomes. The complete system with annotations and tools is freely available via browsing or via installation on a user's Mac or Linux computer. One of the important unique features of the SEED is the support of metabolic reconstruction and comparative genome analysis via encoding and projection of functional subsystems. During the project period, the FIG research team has validated the new software by developing a significant number of core subsystems, covering many aspects of central metabolism (Specific Aim 2), as well as metabolic areas specific for cyanobacteria and other photoautotrophic organisms (Specific Aim 3). In addition to providing a proof of technology and a starting point for further community-based efforts, these subsystems represent a valuable asset. An extensive coverage of central metabolism provides the bulk of information required for metabolic modeling in Synechocystis sp.PCC 6803. Detailed analysis of several subsystems

Identification of a New Target slr0946 of the Response Regulator Sll0649 Involving Cadmium Tolerance in Synechocystis sp. PCC 6803

Directory of Open Access Journals (Sweden)

Tao Sun

2017-08-01

Full Text Available Survival of photosynthetic cyanobacteria is challenged by environmental contaminations like heavy metals. Among them, deciphering the regulatory mechanisms for cadmium (Cd in cyanobacteria would facilitate the construction of Cd-resistant strains. In this study, the DNA-Affinity-Purified-chromatin immunoprecipitation assay was employed to identify the direct targets of Sll0649, which was a Cd2+-related response regulator identified in our previous work in model cyanobacteria Synechocystis sp. PCC 6803. As a result, the promoter region of slr0946 encoding the arsenate reductase was enriched fourfolds by quantitative real time PCR analysis. Further, deletion of slr0946 led to a sensitive phenotype to Cd2+ stress compared with the wild type (WT and the sensitive phenotype of Δslr0946 could be rescued by complementation assay via introducing slr0946 back into Δslr0946. Finally, individually overexpression of slr0946 as well as two Cd2+-related genes identified priviously (i.e., sll1598 and slr0798 in WT could significantly improve the tolerance of Synechocystis sp. PCC 6803 to Cd2+. This study provided a better understanding of the tolerance mechanism to Cd2+ in cyanobacteria and also feasible strategies for tolerance modifications to heavy metals in the future.

Engineering Cyanobacterial Cell Morphology for Enhanced Recovery and Processing of Biomass.

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Jordan, Adam; Chandler, Jenna; MacCready, Joshua S; Huang, Jingcheng; Osteryoung, Katherine W; Ducat, Daniel C

2017-05-01

Cyanobacteria are emerging as alternative crop species for the production of fuels, chemicals, and biomass. Yet, the success of these microbes depends on the development of cost-effective technologies that permit scaled cultivation and cell harvesting. Here, we investigate the feasibility of engineering cell morphology to improve biomass recovery and decrease energetic costs associated with lysing cyanobacterial cells. Specifically, we modify the levels of Min system proteins in Synechococcus elongatus PCC 7942. The Min system has established functions in controlling cell division by regulating the assembly of FtsZ, a tubulin-like protein required for defining the bacterial division plane. We show that altering the expression of two FtsZ-regulatory proteins, MinC and Cdv3, enables control over cell morphology by disrupting FtsZ localization and cell division without preventing continued cell growth. By varying the expression of these proteins, we can tune the lengths of cyanobacterial cells across a broad dynamic range, anywhere from an ∼20% increased length (relative to the wild type) to near-millimeter lengths. Highly elongated cells exhibit increased rates of sedimentation under low centrifugal forces or by gravity-assisted settling. Furthermore, hyperelongated cells are also more susceptible to lysis through the application of mild physical stress. Collectively, these results demonstrate a novel approach toward decreasing harvesting and processing costs associated with mass cyanobacterial cultivation by altering morphology at the cellular level. IMPORTANCE We show that the cell length of a model cyanobacterial species can be programmed by rationally manipulating the expression of protein factors that suppress cell division. In some instances, we can increase the size of these cells to near-millimeter lengths with this approach. The resulting elongated cells have favorable properties with regard to cell harvesting and lysis. Furthermore, cells treated in this

The Genome Sequence of the Cyanobacterium Oscillatoria sp. PCC 6506 Reveals Several Gene Clusters Responsible for the Biosynthesis of Toxins and Secondary Metabolites▿

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Méjean, Annick; Mazmouz, Rabia; Mann, Stéphane; Calteau, Alexandra; Médigue, Claudine; Ploux, Olivier

2010-01-01

We report a draft sequence of the genome of Oscillatoria sp. PCC 6506, a cyanobacterium that produces anatoxin-a and homoanatoxin-a, two neurotoxins, and cylindrospermopsin, a cytotoxin. Beside the clusters of genes responsible for the biosynthesis of these toxins, we have found other clusters of genes likely involved in the biosynthesis of not-yet-identified secondary metabolites. PMID:20675499

Isolation, one-step affinity purification, and characterization of a polyextremotolerant laccase from the halophilic bacterium Aquisalibacillus elongatus and its application in the delignification of sugar beet pulp.

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Rezaei, Shahla; Shahverdi, Ahmad Reza; Faramarzi, Mohammad Ali

2017-04-01

The aim of the present work was to study the ability of a halophilic bacterial laccase to efficient delignification in extreme conditions. Here, a highly stable extracellular laccase showing ligninolytic activity from halophilic Aquisalibacillus elongatus is described. The laccase production was strongly influenced by NaCl and CuSO 4 and under optimal conditions reached 4.8UmL -1 . The monomeric enzyme of 75kDa was purified by a synthetic affinity column with 68.2% yield and 99.8-fold purification. The enzyme showed some valuable features viz. stability against a wide range of organic solvents, salts, metals, inhibitors, and surfactants and specificity to a wide spectrum of substrates diverse in structure and redox potential. It retained more than 50% of the original activity at 25-75°C and pH 5.0-10.0. Furthermore, the enzyme was found to be effective in the delignification of sugar beet pulp in an ionic liquid that makes it useful for industrial applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

The interplay between siderophore secretion and coupled iron and copper transport in the heterocyst-forming cyanobacterium Anabaena sp. PCC 7120.

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Nicolaisen, Kerstin; Hahn, Alexander; Valdebenito, Marianne; Moslavac, Suncana; Samborski, Anastazia; Maldener, Iris; Wilken, Corinna; Valladares, Ana; Flores, Enrique; Hantke, Klaus; Schleiff, Enrico

2010-11-01

Iron uptake is essential for Gram-negative bacteria including cyanobacteria. In cyanobacteria, however, the iron demand is higher than in proteobacteria due to the function of iron as a cofactor in photosynthesis and nitrogen fixation, but our understanding of iron uptake by cyanobacteria stands behind the knowledge in proteobacteria. Here, two genes involved in this process in the heterocyst-forming cyanobacterium Anabaena sp. PCC 7120 were identified. ORF all4025 encodes SchE, a putative cytoplasmic membrane-localized transporter involved in TolC-dependent siderophore secretion. Inactivation of schE resulted in an enhanced sensitivity to high metal concentrations and decreased secretion of hydroxamate-type siderophores. ORF all4026 encodes a predicted outer membrane-localized TonB-dependent iron transporter, IacT. Inactivation of iacT resulted in decreased sensitivity to elevated iron and copper levels. Expression of iacT from the artificial trc promoter (P(trc)) resulted in sensitization against tested metals. Further analysis showed that iron and copper effects are synergistic because a decreased supply of iron induced a significant decrease of copper levels in the iacT insertion mutant but an increase of those levels in the strain carrying P(trc)-iacT. Our results unravel a link between iron and copper homeostasis in Anabaena sp. PCC 7120. Copyright © 2010 Elsevier B.V. All rights reserved.

Different activation of opercular and posterior cingulate cortex (PCC) in patients with complex regional pain syndrome (CRPS I) compared with healthy controls during perception of electrically induced pain: a functional MRI study.

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Freund, Wolfgang; Wunderlich, Arthur P; Stuber, Gregor; Mayer, Florian; Steffen, Peter; Mentzel, Martin; Weber, Frank; Schmitz, Bernd

2010-05-01

Although the etiology of complex regional pain syndrome type 1 (CRPS 1) is still debated, many arguments favor central maladaptive changes in pain processing as an important causative factor. To look for the suspected alterations, 10 patients with CRPS affecting the left hand were explored with functional magnetic resonance imaging during graded electrical painful stimulation of both hands subsequently and compared with healthy participants. Activation of the anterior insula, posterior cingulate cortex (PCC), and caudate nucleus was seen in patients during painful stimulation. Compared with controls, CRPS patients had stronger activation of the PCC during painful stimulation of the symptomatic hand. The comparison of insular/opercular activation between controls and patients with CRPS I during painful stimulation showed stronger (posterior) opercular activation in controls than in patients. Stronger PCC activation during painful stimulation may be interpreted as a correlate of motor inhibition during painful stimuli different from controls. Also, the decreased opercular activation in CRPS patients shows less sensory-discriminative processing of painful stimuli.These results show that changed cerebral pain processing in CRPS patients is less sensory-discriminative but more motor inhibition during painful stimuli. These changes are not limited to the diseased side but show generalized alterations of cerebral pain processing in chronic pain patients.

Retinal is formed from apo-carotenoids in Nostoc sp. PCC7120: in vitro characterization of an apo-carotenoid oxygenase

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Scherzinger, Daniel; Ruch, Sandra; Kloer, Daniel P.; Wilde, Annegret; Al-Babili, Salim

2006-01-01

The sensory rhodopsin from Anabaena (Nostoc) sp. PCC7120 is the first cyanobacterial retinylidene protein identified. Here, we report on NosACO (Nostoc apo-carotenoid oxygenase), encoded by the ORF (open reading frame) all4284, as the candidate responsible for the formation of the required chromophore, retinal. In contrast with the enzymes from animals, NosACO converts β-apo-carotenals instead of β-carotene into retinal in vitro. The identity of the enzymatic products was proven by HPLC and gas chromatography–MS. NosACO exhibits a wide substrate specificity with respect to chain lengths and functional end-groups, converting β-apo-carotenals, (3R)-3-hydroxy-β-apo-carotenals and the corresponding alcohols into retinal and (3R)-3-hydroxyretinal respectively. However, kinetic analyses revealed very divergent Km and Vmax values. On the basis of the crystal structure of SynACO (Synechocystis sp. PCC6803 apo-carotenoid oxygenase), a related enzyme showing similar enzymatic activity, we designed a homology model of the native NosACO. The deduced structure explains the absence of β-carotene-cleavage activity and indicates that NosACO is a monotopic membrane protein. Accordingly, NosACO could be readily reconstituted into liposomes. To localize SynACO in vivo, a Synechocystis knock-out strain was generated expressing SynACO as the sole carotenoid oxygenase. Western-blot analyses showed that the main portion of SynACO occurred in a membrane-bound form. PMID:16759173

Improved Eco-Friendly Recombinant Anabaena sp. Strain PCC7120 with Enhanced Nitrogen Biofertilizer Potential▿

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Chaurasia, Akhilesh Kumar; Apte, Shree Kumar

2011-01-01

Photosynthetic, nitrogen-fixing Anabaena strains are native to tropical paddy fields and contribute to the carbon and nitrogen economy of such soils. Genetic engineering was employed to improve the nitrogen biofertilizer potential of Anabaena sp. strain PCC7120. Constitutive enhanced expression of an additional integrated copy of the hetR gene from a light-inducible promoter elevated HetR protein expression and enhanced functional heterocyst frequency in the recombinant strain. The recombinant strain displayed consistently higher nitrogenase activity than the wild-type strain and appeared to be in homeostasis with compatible modulation of photosynthesis and respiration. The enhanced combined nitrogen availability from the recombinant strain positively catered to the nitrogen demand of rice seedlings in short-term hydroponic experiments and supported better growth. The engineered strain is stable, eco-friendly, and useful for environmental application as nitrogen biofertilizer in paddy fields. PMID:21057013

Improved eco-friendly recombinant Anabaena sp. strain PCC7120 with enhanced nitrogen biofertilizer potential.

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Chaurasia, Akhilesh Kumar; Apte, Shree Kumar

2011-01-01

Photosynthetic, nitrogen-fixing Anabaena strains are native to tropical paddy fields and contribute to the carbon and nitrogen economy of such soils. Genetic engineering was employed to improve the nitrogen biofertilizer potential of Anabaena sp. strain PCC7120. Constitutive enhanced expression of an additional integrated copy of the hetR gene from a light-inducible promoter elevated HetR protein expression and enhanced functional heterocyst frequency in the recombinant strain. The recombinant strain displayed consistently higher nitrogenase activity than the wild-type strain and appeared to be in homeostasis with compatible modulation of photosynthesis and respiration. The enhanced combined nitrogen availability from the recombinant strain positively catered to the nitrogen demand of rice seedlings in short-term hydroponic experiments and supported better growth. The engineered strain is stable, eco-friendly, and useful for environmental application as nitrogen biofertilizer in paddy fields.

An alternative methionine aminopeptidase, MAP-A, is required for nitrogen starvation and high-light acclimation in the cyanobacterium Synechocystis sp. PCC 6803.

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Drath, Miriam; Baier, Kerstin; Forchhammer, Karl

2009-05-01

Methionine aminopeptidases (MetAPs or MAPs, encoded by map genes) are ubiquitous and pivotal enzymes for protein maturation in all living organisms. Whereas most bacteria harbour only one map gene, many cyanobacterial genomes contain two map paralogues, the genome of Synechocystis sp. PCC 6803 even three. The physiological function of multiple map paralogues remains elusive so far. This communication reports for the first time differential MetAP function in a cyanobacterium. In Synechocystis sp. PCC 6803, the universally conserved mapC gene (sll0555) is predominantly expressed in exponentially growing cells and appears to be a housekeeping gene. By contrast, expression of mapA (slr0918) and mapB (slr0786) genes increases during stress conditions. The mapB paralogue is only transiently expressed, whereas the widely distributed mapA gene appears to be the major MetAP during stress conditions. A mapA-deficient Synechocystis mutant shows a subtle impairment of photosystem II properties even under non-stressed conditions. In particular, the binding site for the quinone Q(B) is affected, indicating specific N-terminal methionine processing requirements of photosystem II components. MAP-A-specific processing becomes essential under certain stress conditions, since the mapA-deficient mutant is severely impaired in surviving conditions of prolonged nitrogen starvation and high light exposure.

A bioelectrochemical approach to characterize extracellular electron transfer by Synechocystis sp. PCC6803.

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Angelo Cereda

Full Text Available Biophotovoltaic devices employ photosynthetic organisms at the anode of a microbial fuel cell to generate electrical power. Although a range of cyanobacteria and algae have been shown to generate photocurrent in devices of a multitude of architectures, mechanistic understanding of extracellular electron transfer by phototrophs remains minimal. Here we describe a mediatorless bioelectrochemical device to measure the electrogenic output of a planktonically grown cyanobacterium, Synechocystis sp. PCC6803. Light dependent production of current is measured, and its magnitude is shown to scale with microbial cell concentration and light intensity. Bioelectrochemical characterization of a Synechocystis mutant lacking Photosystem II demonstrates conclusively that production of the majority of photocurrent requires a functional water splitting aparatus and electrons are likely ultimately derived from water. This shows the potential of the device to rapidly and quantitatively characterize photocurrent production by genetically modified strains, an approach that can be used in future studies to delineate the mechanisms of cyanobacterial extracellular electron transport.

Arsenic biotransformation by a cyanobacterium Nostoc sp. PCC 7120.

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Xue, Xi-Mei; Yan, Yu; Xiong, Chan; Raber, Georg; Francesconi, Kevin; Pan, Ting; Ye, Jun; Zhu, Yong-Guan

2017-09-01

Nostoc sp. PCC 7120 (Nostoc), a typical filamentous cyanobacterium ubiquitous in aquatic system, is recognized as a model organism to study prokaryotic cell differentiation and nitrogen fixation. In this study, Nostoc cells incubated with arsenite (As(III)) for two weeks were extracted with dichloromethane/methanol (DCM/MeOH) and the extract was partitioned between water and DCM. Arsenic species in aqueous and DCM layers were determined using high performance liquid chromatography - inductively coupled plasma mass spectrometer/electrospray tandem mass spectrometry (HPLC-ICPMS/ESIMSMS). In addition to inorganic arsenic (iAs), the aqueous layer also contained monomethylarsonate (MAs(V)), dimethylarsinate (DMAs(V)), and the two arsenosugars, namely a glycerol arsenosugar (Oxo-Gly) and a phosphate arsenosugar (Oxo-PO4). Two major arsenosugar phospholipids (AsSugPL982 and AsSugPL984) were detected in DCM fraction. Arsenic in the growth medium was also investigated by HPLC/ICPMS and shown to be present mainly as the inorganic forms As(III) and As(V) accounting for 29%-38% and 29%-57% of the total arsenic respectively. The total arsenic of methylated arsenic, arsenosugars, and arsenosugar phospholipids in Nostoc cells with increasing As(III) exposure were not markedly different, indicating that the transformation to organoarsenic in Nostoc was not dependent on As(III) concentration in the medium. Our results provide new insights into the role of cyanobacteria in the biogeochemical cycling of arsenic. Copyright © 2017 Elsevier Ltd. All rights reserved.

Genetic engineering of Synechocystis PCC6803 for the photoautotrophic production of the sweetener erythritol.

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van der Woude, Aniek D; Perez Gallego, Ruth; Vreugdenhil, Angie; Puthan Veetil, Vinod; Chroumpi, Tania; Hellingwerf, Klaas J

2016-04-08

Erythritol is a polyol that is used in the food and beverage industry. Due to its non-caloric and non-cariogenic properties, the popularity of this sweetener is increasing. Large scale production of erythritol is currently based on conversion of glucose by selected fungi. In this study, we describe a biotechnological process to produce erythritol from light and CO2, using engineered Synechocystis sp. PCC6803. By functionally expressing codon-optimized genes encoding the erythrose-4-phosphate phosphatase TM1254 and the erythrose reductase Gcy1p, or GLD1, this cyanobacterium can directly convert the Calvin cycle intermediate erythrose-4-phosphate into erythritol via a two-step process and release the polyol sugar in the extracellular medium. Further modifications targeted enzyme expression and pathway intermediates. After several optimization steps, the best strain, SEP024, produced up to 2.1 mM (256 mg/l) erythritol, excreted in the medium.

Quantitative iTRAQ LC-MS/MS proteomics reveals metabolic responses to biofuel ethanol in cyanobacterial Synechocystis sp. PCC 6803.

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Qiao, Jianjun; Wang, Jiangxin; Chen, Lei; Tian, Xiaoxu; Huang, Siqiang; Ren, Xiaoyue; Zhang, Weiwen

2012-11-02

Recent progress in metabolic engineering has led to autotrophic production of ethanol in various cyanobacterial hosts. However, cyanobacteria are known to be sensitive to ethanol, which restricts further efforts to increase ethanol production levels in these renewable host systems. To understand the mechanisms of ethanol tolerance so that engineering more robust cyanobacterial hosts can be possible, in this study, the responses of model cyanobacterial Synechocystis sp. PCC 6803 to ethanol were determined using a quantitative proteomics approach with iTRAQ LC-MS/MS technologies. The resulting high-quality proteomic data set consisted of 24,887 unique peptides corresponding to 1509 identified proteins, a coverage of approximately 42% of the predicted proteins in the Synechocystis genome. Using a cutoff of 1.5-fold change and a p-value less than 0.05, 135 and 293 unique proteins with differential abundance levels were identified between control and ethanol-treated samples at 24 and 48 h, respectively. Functional analysis showed that the Synechocystis cells employed a combination of induced common stress response, modifications of cell membrane and envelope, and induction of multiple transporters and cell mobility-related proteins as protection mechanisms against ethanol toxicity. Interestingly, our proteomic analysis revealed that proteins related to multiple aspects of photosynthesis were up-regulated in the ethanol-treated Synechocystis cells, consistent with increased chlorophyll a concentration in the cells upon ethanol exposure. The study provided the first comprehensive view of the complicated molecular mechanisms against ethanol stress and also provided a list of potential gene targets for further engineering ethanol tolerance in Synechocystis PCC 6803.

Biological effects of low doses of ionizing radiations. Evidence of effect of pre-irradiation of culture medium on subsequent growth in Cyanobacterium Synechococcus lividus in culture

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Conter, A.; Planel, H.

1986-01-01

In order to distinguish the direct effects of low dose of ionizing radiations at the cellular level from those indirect through the culture medium, we have compared proliferation of Synechococcus lividus grown in pre-irradiated medium to proliferation of cultures grown in non-irradiated medium. A stimulation of growth was observed at the 7th day in cultures inoculated with cells selected in deceleration phase, while an inhibition occured in cultures inoculated with exponential growing cells. Addition of catalase (100 U/ml) counteracted the stimulating effect but did not change the inhibiting effect induced by pre-irradiated medium. Results demonstrated the indirect effect of low dose of irradiation, implying hydrogen peroxide, but let us to think that others radioproduced products could be also involved in the mechanism [fr

Is Monoglucosyldiacylglycerol a Precursor to Monogalactosyldiacylglycerol in All Cyanobacteria?

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Sato, Naoki

2015-10-01

Monogalactosyldiacylglycerol (MGDG) is ubiquitous in the photosynthetic membranes of cyanobacteria and chloroplasts. It is synthesized by galactosylation of diacylglycerol (DAG) in the chloroplasts, whereas it is produced by epimerization of monoglucosyldiacylglycerol (GlcDG) in at least several cyanobacteria that have been analyzed such as Synechocystis sp. PCC 6803. A previous study, however, showed that the mgdE gene encoding the epimerase is absent in some cyanobacteria such as Gloeobacter violaceus, Thermosynechococcus elongatus and Acaryochloris marina. In addition, the N-terminal 'fatty acid hydroxylase' domain is lacking in the MgdE protein of Prochlorococcus marinus. These problems may cast doubt upon the general (or exclusive) role of MgdE in the epimerization of GlcDG to MGDG in cyanobacteria. In addition, GlcDG is usually present at a very low level, and the structural determination of endogenous GlcDG has not been accomplished with cyanobacterial samples. In this study, I determined the structure of GlcDG from Anabaena variabilis by (1)H- and (13)C-nuclear magnetic resonance (NMR) spectroscopy. I then showed that G. violaceus, T. elongatus, A. marina and P. marinus contain GlcDG. In all cases, GlcDG consisted of fewer unsaturated molecular species than MGDG, providing further evidence that GlcDG is a precursor to MGDG. The conversion of GlcDG to MGDG was also demonstrated by radiolabeling and chase experiments in G. violaceus and P. marinus. These results demonstrate that all the analyzed cyanobacteria contain GlcDG, which is converted to MGDG, and suggest that an alternative epimerase is required for MGDG synthesis in these cyanobacteria. © The Author 2015. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

The Multiple Functions of Common Microbial Carbon Polymers, Glycogen and PHB, during Stress Responses in the Non-Diazotrophic Cyanobacterium Synechocystis sp. PCC 6803.

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Damrow, Ramon; Maldener, Iris; Zilliges, Yvonne

2016-01-01

Classical microbial carbon polymers such as glycogen and polyhydroxybutyrate (PHB) have a crucial impact as both a sink and a reserve under macronutrient stress conditions. Most microbial species exclusively synthesize and degrade either glycogen or PHB. A few bacteria such as the phototrophic model organism Synechocystis sp. PCC 6803 surprisingly produce both physico-chemically different polymers under conditions of high C to N ratios. For the first time, the function and interrelation of both carbon polymers in non-diazotrophic cyanobacteria are analyzed in a comparative physiological study of single- and double-knockout mutants (ΔglgC; ΔphaC; ΔglgC/ΔphaC), respectively. Most of the observed phenotypes are explicitly related to the knockout of glycogen synthesis, highlighting the metabolic, energetic, and structural impact of this process whenever cells switch from an active, photosynthetic 'protein status' to a dormant 'glycogen status'. The carbon flux regulation into glycogen granules is apparently crucial for both phycobilisome degradation and thylakoid layer disassembly in the presence of light. In contrast, PHB synthesis is definitely not involved in this primary acclimation response. Moreover, the very weak interrelations between the two carbon-polymer syntheses indicate that the regulation and role of PHB synthesis in Synechocystis sp. PCC 6803 is different from glycogen synthesis.

Biopan-survival I: exposure of the osmophiles synechococcus sp. (Nageli) and haloarcula sp. to the space environment

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Mancinelli, R. L.; White, M. R.; Rothschild, L. J.

The objective of this study was to determine the survivability of osmophilic microorganisms in space, as well as examine the DNA breakage in osmophilic cells exposed to solar UV-radiation plus vacuum and to vacuum only. The organisms used were an unidentified species of Synechococcus (Nägeli) that inhabits the evaporitic gypsum-halite crusts that form along the marine intertidal, and an unidentified species of the extremely halophilic genus Haloarcula (designated as isolate G) isolated from a evaporitic NaCl crystal. Because these organisms are desiccation resistant and gypsum-halite as well as NaCl attenuate UV-radiation, we hypothesized that these organisms would survive in the space environment, better than most others. The organisms were exposed to the space environment for 2 weeks while in earth orbit aboard the Biopan facility. Ground controls were tested in a space simulation facility. All samples were compared to unexposed samples. Survivability was determined by plate counts and the most probable number technique. DNA breakage was determined by labeling breaks in the DNA with ^32P followed by translation. Results indicate that the osmophilic microbes survived the 2 week exposure. The major cause of cell death was DNA damage. The number of strand breaks in the DNA from vacuum UV exposed cells was greater than the vacuum only exposed cells.

Protein Redox Dynamics During Light-to-Dark Transitions in Cyanobacteria and Impacts Due to Nutrient Limitation

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Aaron T Wright

2014-07-01

Full Text Available Protein redox chemistry constitutes a major void in knowledge pertaining to photoautotrophic system regulation and signaling processes. We have employed a chemical biology approach to analyze redox sensitive proteins in live Synechococcus sp. PCC 7002 cells in both light and dark periods, and to understand how cellular redox balance is disrupted during nutrient perturbation. The present work identified 300 putative redox-sensitive proteins that are involved in the generation of reductant, macromolecule synthesis, and carbon flux through central metabolic pathways, and may be involved in cell signaling and response mechanisms. Furthermore, our research suggests that dynamic redox changes in response to specific nutrient limitations, including carbon and nitrogen limitations, contribute to the regulatory changes driven by a shift from light to dark. Taken together, these results contribute to a high-level understanding of post-translational mechanisms regulating flux distributions and suggest potential metabolic engineering targets for redirecting carbon towards biofuel precursors.

An Approach for Predicting Essential Genes Using Multiple Homology Mapping and Machine Learning Algorithms.

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Hua, Hong-Li; Zhang, Fa-Zhan; Labena, Abraham Alemayehu; Dong, Chuan; Jin, Yan-Ting; Guo, Feng-Biao

Investigation of essential genes is significant to comprehend the minimal gene sets of cell and discover potential drug targets. In this study, a novel approach based on multiple homology mapping and machine learning method was introduced to predict essential genes. We focused on 25 bacteria which have characterized essential genes. The predictions yielded the highest area under receiver operating characteristic (ROC) curve (AUC) of 0.9716 through tenfold cross-validation test. Proper features were utilized to construct models to make predictions in distantly related bacteria. The accuracy of predictions was evaluated via the consistency of predictions and known essential genes of target species. The highest AUC of 0.9552 and average AUC of 0.8314 were achieved when making predictions across organisms. An independent dataset from Synechococcus elongatus , which was released recently, was obtained for further assessment of the performance of our model. The AUC score of predictions is 0.7855, which is higher than other methods. This research presents that features obtained by homology mapping uniquely can achieve quite great or even better results than those integrated features. Meanwhile, the work indicates that machine learning-based method can assign more efficient weight coefficients than using empirical formula based on biological knowledge.

Discrete gene replication events drive coupling between the cell cycle and circadian clocks.

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Paijmans, Joris; Bosman, Mark; Ten Wolde, Pieter Rein; Lubensky, David K

2016-04-12

Many organisms possess both a cell cycle to control DNA replication and a circadian clock to anticipate changes between day and night. In some cases, these two rhythmic systems are known to be coupled by specific, cross-regulatory interactions. Here, we use mathematical modeling to show that, additionally, the cell cycle generically influences circadian clocks in a nonspecific fashion: The regular, discrete jumps in gene-copy number arising from DNA replication during the cell cycle cause a periodic driving of the circadian clock, which can dramatically alter its behavior and impair its function. A clock built on negative transcriptional feedback either phase-locks to the cell cycle, so that the clock period tracks the cell division time, or exhibits erratic behavior. We argue that the cyanobacterium Synechococcus elongatus has evolved two features that protect its clock from such disturbances, both of which are needed to fully insulate it from the cell cycle and give it its observed robustness: a phosphorylation-based protein modification oscillator, together with its accompanying push-pull read-out circuit that responds primarily to the ratios of different phosphoform concentrations, makes the clock less susceptible to perturbations in protein synthesis; the presence of multiple, asynchronously replicating copies of the same chromosome diminishes the effect of replicating any single copy of a gene.

Sll0528, a Site-2-Protease, Is Critically Involved in Cold, Salt and Hyperosmotic Stress Acclimation of Cyanobacterium Synechocystis sp. PCC 6803

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Haijin Lei

2014-12-01

Full Text Available Site-2-proteases (S2Ps mediated proteolysis of transmembrane transcriptional regulators is a conserved mechanism to regulate transmembrane signaling. The universal presence of S2P homologs in different cyanobacterial genomes suggest conserved and fundamental functions, though limited data has been available. Here we provide the first evidence that Sll0528, a site-2-protease in Synechocystis sp. PCC 6803 is crucial for salt, cold and hyperosmotic stress acclimation. Remarkable induction of sll0528 gene expression was observed under salt, cold and hyperosmotic stress, much higher than induction of the other three S2Ps. Knock-out of sll0528 gene in wild type Synechocystis sp. PCC 6803 increased their sensitivity to salt, cold and hyperosmotic stress, as revealed by retarded growth, reduced pigments and disrupted photosystems. The sll0528 gene was induced to a much smaller extent by high light and mixotrophic growth with glucose. Similar growth responses of the sll0528 knockout mutant and wild type under high light and mixotrophic growth indicated that sll0528 was dispensable for these conditions. Recombinant Sll0528 protein could cleave beta-casein into smaller fragments. These results together suggest that the Sll0528 metalloprotease plays a role in the stress response and lays the foundation for further investigation of its mechanism, as well as providing hints for the functional analysis of other S2Ps in cyanobacteria.

Advances in the Function and Regulation of Hydrogenase in the Cyanobacterium Synechocystis PCC6803

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Cassier-Chauvat, Corinne; Veaudor, Théo; Chauvat, Franck

2014-01-01

In order to use cyanobacteria for the biological production of hydrogen, it is important to thoroughly study the function and the regulation of the hydrogen-production machine in order to better understand its role in the global cell metabolism and identify bottlenecks limiting H2 production. Most of the recent advances in our understanding of the bidirectional [Ni-Fe] hydrogenase (Hox) came from investigations performed in the widely-used model cyanobacterium Synechocystis PCC6803 where Hox is the sole enzyme capable of combining electrons with protons to produce H2 under specific conditions. Recent findings suggested that the Hox enzyme can receive electrons from not only NAD(P)H as usually shown, but also, or even preferentially, from ferredoxin. Furthermore, plasmid-encoded functions and glutathionylation (the formation of a mixed-disulfide between the cysteines residues of a protein and the cysteine residue of glutathione) are proposed as possible new players in the function and regulation of hydrogen production. PMID:25365180

Regulation of intracellular free calcium concentration during heterocyst differentiation by HetR and NtcA in Anabaena sp. PCC 7120.

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Shi, Yunming; Zhao, Weixing; Zhang, Wei; Ye, Zi; Zhao, Jindong

2006-07-25

Calcium ions are important to some prokaryotic cellular processes, such as heterocyst differentiation of cyanobacteria. Intracellular free Ca(2+)concentration, [Ca(2+)](i), increases several fold in heterocysts and is regulated by CcbP, a Ca(2+)-binding protein found in heterocyst-forming cyanobacteria. We demonstrate here that CcbP is degraded by HetR, a serine-type protease that controls heterocyst differentiation. The degradation depends on Ca(2+) and appears to be specific because HetR did not digest other tested proteins. CcbP was found to bind two Ca(2+) per molecule with K(D) values of 200 nM and 12.8 microM. Degradation of CcbP releases bound Ca(2+) that contributes significantly to the increase of [Ca(2+)](i) during the process of heterocyst differentiation in Anabaena sp. strain PCC 7120. We suggest that degradation of CcbP is a mechanism of positive autoregulation of HetR. The down-regulation of ccbP in differentiating cells and mature heterocysts, which also is critical to the regulation of [Ca(2+)](i), depends on NtcA. Coexpression of ntcA and a ccbP promoter-controlled gfp in Escherichia coli diminished production of GFP, and the decrease is enhanced by alpha-ketoglutarate. It was also found that NtcA could bind a fragment of the ccbP promoter containing an NtcA-binding sequence in a alpha-ketoglutarate-dependent fashion. Therefore, [Ca(2+)](i) is regulated by a collaboration of HetR and NtcA in heterocyst differentiation in Anabaena sp. strain PCC 7120.

Fast-GPU-PCC: A GPU-Based Technique to Compute Pairwise Pearson's Correlation Coefficients for Time Series Data-fMRI Study.

Science.gov (United States)

Eslami, Taban; Saeed, Fahad

2018-04-20

Functional magnetic resonance imaging (fMRI) is a non-invasive brain imaging technique, which has been regularly used for studying brain’s functional activities in the past few years. A very well-used measure for capturing functional associations in brain is Pearson’s correlation coefficient. Pearson’s correlation is widely used for constructing functional network and studying dynamic functional connectivity of the brain. These are useful measures for understanding the effects of brain disorders on connectivities among brain regions. The fMRI scanners produce huge number of voxels and using traditional central processing unit (CPU)-based techniques for computing pairwise correlations is very time consuming especially when large number of subjects are being studied. In this paper, we propose a graphics processing unit (GPU)-based algorithm called Fast-GPU-PCC for computing pairwise Pearson’s correlation coefficient. Based on the symmetric property of Pearson’s correlation, this approach returns N ( N − 1 ) / 2 correlation coefficients located at strictly upper triangle part of the correlation matrix. Storing correlations in a one-dimensional array with the order as proposed in this paper is useful for further usage. Our experiments on real and synthetic fMRI data for different number of voxels and varying length of time series show that the proposed approach outperformed state of the art GPU-based techniques as well as the sequential CPU-based versions. We show that Fast-GPU-PCC runs 62 times faster than CPU-based version and about 2 to 3 times faster than two other state of the art GPU-based methods.

集胞藻PCC6803基因slr2049定点突变及其体内重组功能研究%Site-directed mutation of the gene slr2049 from Synechocy-stis sp.PCC 6803 and the study on the function

Institute of Scientific and Technical Information of China (English)

朱超; 陈思礼

2013-01-01

在Synechocystis sp.PCC 6803中找到与cpeS具有高度同源性的基因slr2049.采用PCR从Synechocystis sp.PCC 6803 DNA中扩增出cpcB,slr2049,hol,pcyA 4个基因；定点突变试剂盒构建8个突变体slr2049 (H21S)、slr2049 (L23S)、slr2049 (A24S)、slr2049 (F25S)、slr2049(W72L)、slr2049(G84S)、slr2049(R107S)和slr2049(Y124S)；将它们与表达载体pCDFDuet-1和pET-23a(+)相连构建pCDF-cpcB-slr2049野生型和pCDF-cpcB-slr2049突变体以及pET-ho1-pcyA,进行高效表达,用亲和层析柱纯化,产物用SDS-PAGE和光谱检测.研究表明:突变体slr2049(H21S)、slr2049(L23S)、slr2049(F25S)、slr2049 (W72L)、slr2049 (G84S)、slr2049(Y124S)与野生型slr2049催化获得的重组藻蓝蛋白β亚基具有与天然藻蓝蛋白β亚基相似的光谱特性,其他2个突变体slr2049 (A24S)和slr2049(R107S)催化的产物则没有光谱特性.由此推测,第24位丙氨酸和第107位精氨酸可能是slr2049酶活性的必需氨基酸,其所处位置是slr2049的活性位点.%We have found gene slr2049 in Synechocystis sp.PCC 6803 which was homol ogous to the bilin lyase gene cpeS by some softwares for homologous analysis.Four genes were amplifed from DNA of Synechocystis sp.PCC 6803 by PCR.Eight mutants which were slr2049 (H21S),slr2049 (L23S),slr2049 (A24S),slr2049 (F25S),slr2049 (W72L),slr2049(G84S),slr2049(R107S)and sl-r2049(Y124S)were constructed by Mutan BEST Kit.pCDF-cpcB-slr2049,pCDF-cpcB-slr2049 mutants and pET-ho1-pcyA were formed from the linkage of four genes and mutants with pCDFDuet-land pET-23a (+).They were expressed and purified by affinity column.Proteins were detected by SDS-PAGE,absorption and fluorescence spectra.The results showed that phycocyanin β-subunit which had the same spectral characteristic with native phycocyanin β-subunit were catalysed by the protein encoded by gene slr2049 and mutants slr2049 (H21S),slr2049(L23S),slr2049(F25S),slr2049 (W72L),slr2049 (G84S),slr2049 (Y124S).The rest of mutants slr2049(A24S

Advances in Understanding Carboxysome Assembly in Prochlorococcus and Synechococcus Implicate CsoS2 as a Critical Component

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Fei Cai

2015-03-01

Full Text Available The marine Synechococcus and Prochlorococcus are the numerically dominant cyanobacteria in the ocean and important in global carbon fixation. They have evolved a CO2-concentrating-mechanism, of which the central component is the carboxysome, a self-assembling proteinaceous organelle. Two types of carboxysome, α and β, encapsulating form IA and form IB d-ribulose-1,5-bisphosphate carboxylase/oxygenase, respectively, differ in gene organization and associated proteins. In contrast to the β-carboxysome, the assembly process of the α-carboxysome is enigmatic. Moreover, an absolutely conserved α-carboxysome protein, CsoS2, is of unknown function and has proven recalcitrant to crystallization. Here, we present studies on the CsoS2 protein in three model organisms and show that CsoS2 is vital for α-carboxysome biogenesis. The primary structure of CsoS2 appears tripartite, composed of an N-terminal, middle (M-, and C-terminal region. Repetitive motifs can be identified in the N- and M-regions. Multiple lines of evidence suggest CsoS2 is highly flexible, possibly an intrinsically disordered protein. Based on our results from bioinformatic, biophysical, genetic and biochemical approaches, including peptide array scanning for protein-protein interactions, we propose a model for CsoS2 function and its spatial location in the α-carboxysome. Analogies between the pathway for β-carboxysome biogenesis and our model for α-carboxysome assembly are discussed.

Engineering Synechocystis PCC6803 for hydrogen production: influence on the tolerance to oxidative and sugar stresses.

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Marcia Ortega-Ramos

Full Text Available In the prospect of engineering cyanobacteria for the biological photoproduction of hydrogen, we have studied the hydrogen production machine in the model unicellular strain Synechocystis PCC6803 through gene deletion, and overexpression (constitutive or controlled by the growth temperature. We demonstrate that the hydrogenase-encoding hoxEFUYH operon is dispensable to standard photoautotrophic growth in absence of stress, and it operates in cell defense against oxidative (H₂O₂ and sugar (glucose and glycerol stresses. Furthermore, we showed that the simultaneous over-production of the proteins HoxEFUYH and HypABCDE (assembly of hydrogenase, combined to an increase in nickel availability, led to an approximately 20-fold increase in the level of active hydrogenase. These novel results and mutants have major implications for those interested in hydrogenase, hydrogen production and redox metabolism, and their connections with environmental conditions.

PRR11 regulates late-S to G2/M phase progression and induces premature chromatin condensation (PCC)

Energy Technology Data Exchange (ETDEWEB)

Zhang, Chundong; Zhang, Ying; Li, Yi; Zhu, Huifang; Wang, Yitao; Cai, Wei [Department of Biochemistry and Molecular Biology, Chongqing Medical University, Chongqing 400016 (China); Molecular Medicine and Cancer Research Center, Chongqing Medical University, Chongqing 400016 (China); Zhu, Jiang [Molecular Medicine and Cancer Research Center, Chongqing Medical University, Chongqing 400016 (China); Ozaki, Toshinori [Laboratory of DNA Damage Signaling, Chiba Cancer Center Research Institute, 666-2 Nitona, Chuohku, Chiba 260-8717 (Japan); Bu, Youquan, E-mail: buyqcn@aliyun.com [Department of Biochemistry and Molecular Biology, Chongqing Medical University, Chongqing 400016 (China); Molecular Medicine and Cancer Research Center, Chongqing Medical University, Chongqing 400016 (China)

2015-03-13

Recently, we have demonstrated that proline-rich protein 11 (PRR11) is a novel tumor-related gene product likely implicated in the regulation of cell cycle progression as well as lung cancer development. However, its precise role in cell cycle progression remains unclear. In the present study, we have further investigated the expression pattern and functional implication of PRR11 during cell cycle in detail in human lung carcinoma-derived H1299 cells. According to our immunofluorescence study, PRR11 was expressed largely in cytoplasm, the amount of PRR11 started to increase in the late S phase, and was retained until just before mitotic telophase. Consistent with those observations, siRNA-mediated knockdown of PRR11 caused a significant cell cycle arrest in the late S phase. Intriguingly, the treatment with dNTPs further augmented PRR11 silencing-mediated S phase arrest. Moreover, knockdown of PRR11 also resulted in a remarkable retardation of G2/M progression, and PRR11-knockdown cells subsequently underwent G2 phase cell cycle arrest accompanied by obvious mitotic defects such as multipolar spindles and multiple nuclei. In addition, forced expression of PRR11 promoted the premature Chromatin condensation (PCC), and then proliferation of PRR11-expressing cells was massively attenuated and induced apoptosis. Taken together, our current observations strongly suggest that PRR11, which is strictly regulated during cell cycle progression, plays a pivotal role in the regulation of accurate cell cycle progression through the late S phase to mitosis. - Highlights: • PRR11 started to increase in the late S phase and was retained until just before mitotic telophase. • PRR11-knockdown caused a significant cell cycle arrest in the late S phase and G2 phase. • The treatment with dNTPs further augmented PRR11 silencing-mediated S phase arrest. • PRR11-knockdown led to multipolar spindles and multiple nuclei. • Forced expression of PRR11 promoted the PCC and inhibited

PRR11 regulates late-S to G2/M phase progression and induces premature chromatin condensation (PCC)

International Nuclear Information System (INIS)

Zhang, Chundong; Zhang, Ying; Li, Yi; Zhu, Huifang; Wang, Yitao; Cai, Wei; Zhu, Jiang; Ozaki, Toshinori; Bu, Youquan

2015-01-01

Recently, we have demonstrated that proline-rich protein 11 (PRR11) is a novel tumor-related gene product likely implicated in the regulation of cell cycle progression as well as lung cancer development. However, its precise role in cell cycle progression remains unclear. In the present study, we have further investigated the expression pattern and functional implication of PRR11 during cell cycle in detail in human lung carcinoma-derived H1299 cells. According to our immunofluorescence study, PRR11 was expressed largely in cytoplasm, the amount of PRR11 started to increase in the late S phase, and was retained until just before mitotic telophase. Consistent with those observations, siRNA-mediated knockdown of PRR11 caused a significant cell cycle arrest in the late S phase. Intriguingly, the treatment with dNTPs further augmented PRR11 silencing-mediated S phase arrest. Moreover, knockdown of PRR11 also resulted in a remarkable retardation of G2/M progression, and PRR11-knockdown cells subsequently underwent G2 phase cell cycle arrest accompanied by obvious mitotic defects such as multipolar spindles and multiple nuclei. In addition, forced expression of PRR11 promoted the premature Chromatin condensation (PCC), and then proliferation of PRR11-expressing cells was massively attenuated and induced apoptosis. Taken together, our current observations strongly suggest that PRR11, which is strictly regulated during cell cycle progression, plays a pivotal role in the regulation of accurate cell cycle progression through the late S phase to mitosis. - Highlights: • PRR11 started to increase in the late S phase and was retained until just before mitotic telophase. • PRR11-knockdown caused a significant cell cycle arrest in the late S phase and G2 phase. • The treatment with dNTPs further augmented PRR11 silencing-mediated S phase arrest. • PRR11-knockdown led to multipolar spindles and multiple nuclei. • Forced expression of PRR11 promoted the PCC and inhibited

Metabolic flux analysis of the hydrogen production potential in Synechocystis sp. PCC6803

Energy Technology Data Exchange (ETDEWEB)

Navarro, E. [Departamento de Lenguajes y Ciencias de la Computacion, Campus de Teatrinos, Universidad de Malaga, 29071 Malaga (Spain); Montagud, A.; Fernandez de Cordoba, P.; Urchueguia, J.F. [Instituto Universitario de Matematica Pura y Aplicada, Universidad Politecnica de Valencia, Camino de Vera 14, 46022 Valencia (Spain)

2009-11-15

Hydrogen is a promising energy vector; however, finding methods to produce it from renewable sources is essential to allow its wide-scale use. In that line, biological hydrogen production, although it is considered as a possible alternative, requires substantial improvements to overcome its present low yields. In that direction, genetic manipulation probably will play a central role and from that point of view metabolic flux analysis (MFA) constitutes an important tool to guide a priori most suitable genetic modifications oriented to a hydrogen yield increase. In this work MFA has been applied to analyze hydrogen photoproduction of Synechocystis sp. PCC6803. Flux analysis was carried out based on literature data and several basic fluxes were estimated in different growing conditions of the system. From this analysis, an upper limit for hydrogen photoproduction has been determined indicating a wide margin for improvement. MFA was also used to find a feasible operating space for hydrogen production, which avoids oxygen inhibition, one of the most important limitations to make hydrogen production cost effective. In addition, a set of biotechnological strategies are proposed that would be consistent with the performed mathematical analysis. (author)

Production of squalene in Synechocystis sp. PCC 6803.

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Elias Englund

Full Text Available In recent years, there has been an increased interest in the research and development of sustainable alternatives to fossil fuels. Using photosynthetic microorganisms to produce such alternatives is advantageous, since they can achieve direct conversion of carbon dioxide from the atmosphere into the desired product, using sunlight as the energy source. Squalene is a naturally occurring 30-carbon isoprenoid, which has commercial use in cosmetics and in vaccines. If it could be produced sustainably on a large scale, it could also be used instead of petroleum as a raw material for fuels and as feedstock for the chemical industry. The unicellular cyanobacterium Synechocystis PCC 6803 possesses a gene, slr2089, predicted to encode squalene hopene cyclase (Shc, an enzyme converting squalene into hopene, the substrate for forming hopanoids. Through inactivation of slr2089 (shc, we explored the possibility to produce squalene using cyanobacteria. The inactivation led to accumulation of squalene, to a level over 70 times higher than in wild type cells, reaching 0.67 mg OD750(-1 L(-1. We did not observe any significant growth deficiency in the Δshc strain compared to the wild type Synechocystis, even at high light conditions, suggesting that the observed squalene accumulation was not detrimental to growth, and that formation of hopene by Shc is not crucial for growth under normal conditions, nor for high-light stress tolerance. Effects of different light intensities and growth stages on squalene accumulation in the Δshc strain were investigated. We also identified a gene, sll0513, as a putative squalene synthase in Synechocystis, and verified its function by inactivation. In this work, we show that it is possible to use the cyanobacterium Synechocystis to generate squalene, a hydrocarbon of commercial interest and a potential biofuel. We also report the first identification of a squalene hopene cyclase, and the second identification of squalene synthase

In vivo effects of photosynthesis inhibitors in Synechococcus as determined by 31P NMR spectroscopy

International Nuclear Information System (INIS)

Thoma, W.J.; Gleason, F.K.

1987-01-01

Phosphorus-31 nuclear magnetic resonance spectra were obtained from darkened cells of the unicellular cyanobacterium Synechococcus sp. Resonance peaks were assigned to intracellular pools of sugar-phosphates, inorganic phosphate (P/sub i/), nucleotides, and polyphosphate. An internal pH of 7.2 was estimated from the chemical shift of the P/sub i/ resonance. Cells were then illuminated at 1600 μE m -2 s -1 photosynthetically active radiation by a fiber optic cable immersed in the cell sample. Spectra obtained after approximately 15 min of illumination showed an increase in nucleotide pools and an increase in the cytoplasmic pH to 7.6. In the presence of 0.3 mM dinitrophenol (DNP), an uncoupler of phosphorylation, spectra of illuminated cells showed an immediate decline in nucleotide pools while sugar-phosphate levels remained constant. Addition of the photosystem II (PS II) electron-transport inhibitor 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) (7.2 μM) did not affect nucleotide levels in the cells during the time course of the experiment (15-30 min). However, an abrupt rise in the resonance in the sugar-phosphate region was noted. Spectra of DCMU-treated cells extracts indicated that one metabolite was principally responsible for the change in pool size. The metabolite was identified as 3-phosphoglyceric acid. Spectra of illuminated cells were also obtained in the presence of the natural herbicide cyanobacterin. Unlike results obtained with DNP or DCMU, spectra of cyanobacterin-treated cells showed no major changes in nucleotide or sugar-phosphate resonances. A slow decline in cytoplasmic pH was seen in the presence of cyanobacterin, indicating that the natural product affects the proton pumping mechanism in PS II

Genomic responses to arsenic in the cyanobacterium Synechocystis sp. PCC 6803.

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Ana María Sánchez-Riego

Full Text Available Arsenic is a ubiquitous contaminant and a toxic metalloid which presents two main redox states in nature: arsenite [As(III] and arsenate [As(V]. Arsenic resistance in Synechocystis sp. strain PCC 6803 is mediated by the arsBHC operon and two additional arsenate reductases encoded by the arsI1 and arsI2 genes. Here we describe the genome-wide responses to the presence of arsenate and arsenite in wild type and mutants in the arsenic resistance system. Both forms of arsenic produced similar responses in the wild type strain, including induction of several stress related genes and repression of energy generation processes. These responses were transient in the wild type strain but maintained in time in an arsB mutant strain, which lacks the arsenite transporter. In contrast, the responses observed in a strain lacking all arsenate reductases were somewhat different and included lower induction of genes involved in metal homeostasis and Fe-S cluster biogenesis, suggesting that these two processes are targeted by arsenite in the wild type strain. Finally, analysis of the arsR mutant strain revealed that ArsR seems to only control 5 genes in the genome. Furthermore, the arsR mutant strain exhibited hypersentivity to nickel, copper and cadmium and this phenotype was suppressed by mutation in arsB but not in arsC gene suggesting that overexpression of arsB is detrimental in the presence of these metals in the media.

Transgenic tobacco plants with improved cyanobacterial Rubisco expression but no extra assembly factors grow at near wild-type rates if provided with elevated CO2.

Science.gov (United States)

Occhialini, Alessandro; Lin, Myat T; Andralojc, P John; Hanson, Maureen R; Parry, Martin A J

2016-01-01

Introducing a carbon-concentrating mechanism and a faster Rubisco enzyme from cyanobacteria into higher plant chloroplasts may improve photosynthetic performance by increasing the rate of CO2 fixation while decreasing losses caused by photorespiration. We previously demonstrated that tobacco plants grow photoautotrophically using Rubisco from Synechococcus elongatus, although the plants exhibited considerably slower growth than wild-type and required supplementary CO2 . Because of concerns that vascular plant assembly factors may not be adequate for assembly of a cyanobacterial Rubisco, prior transgenic plants included the cyanobacterial chaperone RbcX or the carboxysomal protein CcmM35. Here we show that neither RbcX nor CcmM35 is needed for assembly of active cyanobacterial Rubisco. Furthermore, by altering the gene regulatory sequences on the Rubisco transgenes, cyanobacterial Rubisco expression was enhanced and the transgenic plants grew at near wild-type growth rates, although still requiring elevated CO2 . We performed detailed kinetic characterization of the enzymes produced with and without the RbcX and CcmM35 cyanobacterial proteins. These transgenic plants exhibit photosynthetic characteristics that confirm the predicted benefits of introduction of non-native forms of Rubisco with higher carboxylation rate constants in vascular plants and the potential nitrogen-use efficiency that may be achieved provided that adequate CO2 is available near the enzyme. © 2015 The Authors The Plant Journal © 2015 John Wiley & Sons Ltd.

PSII as an in vivo molecular catalyst for the production of energy rich hydroquinones - A new approach in renewable energy.

Science.gov (United States)

Das, Sai; Maiti, Soumen K

2018-03-01

One of the pertinent issues in the field of energy science today is the quest for an abundant source of hydrogen or hydrogen equivalents. In this study, phenyl-p-benzoquinone (pPBQ) has been used to generate a molecular store of hydrogen equivalents (phenyl-p-hydroquinone; pPBQH 2 ) from thein vivo splitting of water by photosystem II of the marine cyanobacterium Synechococcus elongatus BDU 70542. Using this technique, 10.8 μmol of pPBQH 2 per mg chlorophyll a can be extracted per minute, an efficiency that is orders of magnitude higher when compared to the techniques present in the current literature. Moreover, the photo-reduction process was stable when tested over longer periods of time. Addition of phenyl-p-benzoquinone on an intermittent basis resulted in the precipitation of phenyl-p-hydroquinone, obviating the need for costly downstream processing units for product recovery. Phenyl-p-hydroquinone so obtained is a molecular store of free energy preserved through the light driven photolysis of water and can be used as a cheap and a renewable source of hydrogen equivalents by employing transition metal catalysts or fuel cells with the concomitant regeneration of phenyl-p-benzoquinone. The cyclic nature of this technique makes it an ideal candidate to be utilized in mankind's transition from fossil fuels to solar fuels. Copyright © 2018 Elsevier B.V. All rights reserved.

Isobutanol production in Synechocystis PCC 6803 using heterologous and endogenous alcohol dehydrogenases

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Rui Miao

2017-12-01

Full Text Available Isobutanol is a flammable compound that can be used as a biofuel due to its high energy density and suitable physical and chemical properties. In this study, we examined the capacity of engineered strains of Synechocystis PCC 6803 containing the α-ketoisovalerate decarboxylase from Lactococcus lactis and different heterologous and endogenous alcohol dehydrogenases (ADH for isobutanol production. A strain expressing an introduced kivd without any additional copy of ADH produced 3 mg L−1 OD750−1 isobutanol in 6 days. After the cultures were supplemented with external addition of isobutyraldehyde, the substrate for ADH, 60.8 mg L−1 isobutanol was produced after 24 h when OD750 was 0.8. The in vivo activities of four different ADHs, two heterologous and two putative endogenous in Synechocystis, were examined and the Synechocystis endogenous ADH encoded by slr1192 showed the highest efficiency for isobutanol production. Furthermore, the strain overexpressing the isobutanol pathway on a self-replicating vector with the strong Ptrc promoter showed significantly higher gene expression and isobutanol production compared to the corresponding strains expressing the same operon introduced on the genome. Hence, this study demonstrates that Synechocystis endogenous AHDs have a high capacity for isobutanol production, and identifies kivd encoded α-ketoisovalerate decarboxylase as one of the likely bottlenecks for further isobutanol production.

Role of phosphatidylglycerol in the function and assembly of Photosystem II reaction center, studied in a cdsA-inactivated PAL mutant strain of Synechocystis sp. PCC6803 that lacks phycobilisomes

Czech Academy of Sciences Publication Activity Database

Laczkó-Dobos, H.; Ughy, B.; Tóth, S. Z.; Komenda, Josef; Zsiros, O.; Domonkos, I.; Párducz, A.; Bogos, B.; Komura, M.; Itoh, S.; Gombos, Z.

2008-01-01

Roč. 1777, č. 9 (2008), s. 1184-1194 ISSN 0005-2728 R&D Projects: GA AV ČR IAA400200801 Grant - others:HU(HU) OTKA T60109; HU(HU) OTKA T68692 Institutional research plan: CEZ:AV0Z50200510 Keywords : synechocystis sp. pcc6803 * phosphatidylglycerol * photosystem II Subject RIV: EE - Microbiology, Virology Impact factor: 4.447, year: 2008

Long-Term Acclimation of the Cyanobacterium Synechocystis sp PCC 6803 to High Light Is Accompanied by an Enhanced Production of Chlorophyll That Is Preferentially Channeled to Trimeric Photosystem I

Czech Academy of Sciences Publication Activity Database

Kopečná, Jana; Komenda, Josef; Bučinská, Lenka; Sobotka, Roman

2012-01-01

Roč. 160, č. 4 (2012), s. 2239-2250 ISSN 0032-0889 R&D Projects: GA MŠk(CZ) ED2.1.00/03.0110; GA ČR GAP501/10/1000; GA ČR GBP501/12/G055 Institutional support: RVO:61388971 Keywords : CAB-LIKE-PROTEINS * SP PCC-6803 * PHOTOSYNTHETIC APPARATUS Subject RIV: EE - Microbiology, Virology Impact factor: 6.555, year: 2012

Identification of a fourth family of lycopene cyclases in photosynthetic bacteria.

Science.gov (United States)

Maresca, Julia A; Graham, Joel E; Wu, Martin; Eisen, Jonathan A; Bryant, Donald A

2007-07-10

A fourth and large family of lycopene cyclases was identified in photosynthetic prokaryotes. The first member of this family, encoded by the cruA gene of the green sulfur bacterium Chlorobium tepidum, was identified in a complementation assay with a lycopene-producing strain of Escherichia coli. Orthologs of cruA are found in all available green sulfur bacterial genomes and in all cyanobacterial genomes that lack genes encoding CrtL- or CrtY-type lycopene cyclases. The cyanobacterium Synechococcus sp. PCC 7002 has two homologs of CruA, denoted CruA and CruP, and both were shown to have lycopene cyclase activity. Although all characterized lycopene cyclases in plants are CrtL-type proteins, genes orthologous to cruP also occur in plant genomes. The CruA- and CruP-type carotenoid cyclases are members of the FixC dehydrogenase superfamily and are distantly related to CrtL- and CrtY-type lycopene cyclases. Identification of these cyclases fills a major gap in the carotenoid biosynthetic pathways of green sulfur bacteria and cyanobacteria.

Overexpression of FurA in Anabaena sp. PCC 7120 reveals new targets for this regulator involved in photosynthesis, iron uptake and cellular morphology.

Science.gov (United States)

González, Andrés; Bes, M Teresa; Barja, François; Peleato, M Luisa; Fillat, María F

2010-11-01

Previous genomic analyses of the filamentous nitrogen-fixing cyanobacterium Anabaena sp. PCC 7120 have identified three ferric uptake regulator (Fur) homologs with low sequence identities and probably different functions in the cell. FurA is a constitutive protein that shares the highest homology with Fur from heterotrophic bacteria and appears to be essential for in vitro growth. In this study, we have analysed the effects of FurA overexpression on the Anabaena sp. phenotype and investigated which of the observed alterations were directly operated by FurA. Overexpression of the regulator led to changes in cellular morphology, resulting in shorter filaments with rounded cells of different sizes. The furA-overexpressing strain showed a slower photoautotrophic growth and a marked decrease in the oxygen evolution rate. Overexpression of the regulator also decreased both catalase and superoxide dismutase activities, but did not lead to an increase in the levels of intracellular reactive oxygen species. By combining phenotypic studies, reverse transcription-PCR analyses and electrophoretic mobility shift assays, we identified three novel direct targets of FurA, including genes encoding a siderophore outer membrane transporter (schT), bacterial actins (mreBCD) and the PSII reaction center protein D1 (psbA). The affinity of FurA for these novel targets was markedly affected by the absence of divalent metal ions, confirming previous evidence of a critical role for the metal co-repressor in the function of the regulator in vivo. The results unravel new cellular processes modulated by FurA, supporting its role as a global transcriptional regulator in Anabaena sp. PCC 7120.

Optimization of pH and nitrogen for enhanced hydrogen production by Synechocystis sp. PCC 6803 via statistical and machine learning methods.

Science.gov (United States)

Burrows, Elizabeth H; Wong, Weng-Keen; Fern, Xiaoli; Chaplen, Frank W R; Ely, Roger L

2009-01-01

The nitrogen (N) concentration and pH of culture media were optimized for increased fermentative hydrogen (H(2)) production from the cyanobacterium, Synechocystis sp. PCC 6803. The optimization was conducted using two procedures, response surface methodology (RSM), which is commonly used, and a memory-based machine learning algorithm, Q2, which has not been used previously in biotechnology applications. Both RSM and Q2 were successful in predicting optimum conditions that yielded higher H(2) than the media reported by Burrows et al., Int J Hydrogen Energy. 2008;33:6092-6099 optimized for N, S, and C (called EHB-1 media hereafter), which itself yielded almost 150 times more H(2) than Synechocystis sp. PCC 6803 grown on sulfur-free BG-11 media. RSM predicted an optimum N concentration of 0.63 mM and pH of 7.77, which yielded 1.70 times more H(2) than EHB-1 media when normalized to chlorophyll concentration (0.68 +/- 0.43 micromol H(2) mg Chl(-1) h(-1)) and 1.35 times more when normalized to optical density (1.62 +/- 0.09 nmol H(2) OD(730) (-1) h(-1)). Q2 predicted an optimum of 0.36 mM N and pH of 7.88, which yielded 1.94 and 1.27 times more H(2) than EHB-1 media when normalized to chlorophyll concentration (0.77 +/- 0.44 micromol H(2) mg Chl(-1) h(-1)) and optical density (1.53 +/- 0.07 nmol H(2) OD(730) (-1) h(-1)), respectively. Both optimization methods have unique benefits and drawbacks that are identified and discussed in this study. (c) 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009.

In vitro kinetics of P700+ reduction of Thermosynechococcus elongatus trimeric Photosystem I complexes by recombinant cytochrome c 6 using a Joliot-type LED spectrophotometer.

Science.gov (United States)

Nguyen, Khoa; Vaughn, Michael; Frymier, Paul; Bruce, Barry D

2017-01-01

The reduction rate of photo-oxidized Photosystem I (PSI) with various natural and artificial electron donors have been well studied by transient absorption spectroscopy. The electron transfer rate from various donors to P 700 + has been measured for a wide range of photosynthetic organisms encompassing cyanobacteria, algae, and plants. PSI can be a limiting component due to tedious extraction and purification methods required for this membrane protein. In this report, we have determined the in vivo, intracellular cytochrome c 6 (cyt c 6 )/PSI ratio in Thermosynechococcus elongatus (T.e.) using quantitative Western blot analysis. This information permitted the determination of P 700 + reduction kinetics via recombinant cyt c 6 in a physiologically relevant ratio (cyt c 6 : PSI) with a Joliot-type, LED-driven, pump-probe spectrophotometer. Dilute PSI samples were tested under varying cyt c 6 concentration, temperature, pH, and ionic strength, each of which shows similar trends to the reported literature utilizing much higher PSI concentrations with laser-based spectrophotometer. Our results do however indicate kinetic differences between actinic light sources (laser vs. LED), and we have attempted to resolve these effects by varying our LED light intensity and duration. The standardized configuration of this spectrophotometer will also allow a more uniform kinetic analysis of samples in different laboratories. We can conclude that our findings from the LED-based system display an added total protein concentration effect due to multiple turnover events of P 700 + reduction by cyt c 6 during the longer illumination regime.

Genome-wide comparative analysis of metacaspases in unicellular and filamentous cyanobacteria

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Qin Song

2010-03-01

Full Text Available Abstract Background Cyanobacteria are an ancient group of photoautotrophic prokaryotes with wide variations in genome size and ecological habitat. Metacaspases (MCAs are cysteine proteinases that have sequence homology to caspases and play essential roles in programmed cell death (PCD. MCAs have been identified in several prokaryotes, fungi and plants; however, knowledge about cyanobacterial metacaspases still remains obscure. With the availability of sequenced genomes of 33 cyanobacteria, we perform a comparative analysis of metacaspases and explore their distribution, domain structure and evolution. Results A total of 58 putative MCAs were identified, which are abundant in filamentous diazotrophic cyanobacteria and Acaryochloris marina MBIC 11017 and absent in all Prochlorococcus and marine Synechococcus strains, except Synechococcus sp. PCC 7002. The Cys-His dyad of caspase superfamily is conserved, while mutations (Tyr in place of His and Ser/Asn/Gln/Gly instead of Cys are also detected in some cyanobacteria. MCAs can be classified into two major families (α and β based on the additional domain structure. Ten types and a total of 276 additional domains were identified, most of which involves in signal transduction. Apoptotic related NACHT domain was also found in two cyanobacterial MCAs. Phylogenetic tree of MCA catalytic P20 domains coincides well with the domain structure and the phylogenies based on 16s rRNA. Conclusions The existence and quantity of MCA genes in unicellular and filamentous cyanobacteria are a function of the genome size and ecological habitat. MCAs of family α and β seem to evolve separately and the recruitment of WD40 additional domain occurs later than the divergence of the two families. In this study, a general framework of sequence-structure-function connections for the metacaspases has been revealed, which may provide new targets for function investigation.

Comparing the in Vivo Function of α-Carboxysomes and β-Carboxysomes in Two Model Cyanobacteria1[W][OPEN

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Whitehead, Lynne; Long, Benedict M.; Price, G. Dean; Badger, Murray R.

2014-01-01

The carbon dioxide (CO2)-concentrating mechanism of cyanobacteria is characterized by the occurrence of Rubisco-containing microcompartments called carboxysomes within cells. The encapsulation of Rubisco allows for high-CO2 concentrations at the site of fixation, providing an advantage in low-CO2 environments. Cyanobacteria with Form-IA Rubisco contain α-carboxysomes, and cyanobacteria with Form-IB Rubisco contain β-carboxysomes. The two carboxysome types have arisen through convergent evolution, and α-cyanobacteria and β-cyanobacteria occupy different ecological niches. Here, we present, to our knowledge, the first direct comparison of the carboxysome function from α-cyanobacteria (Cyanobium spp. PCC7001) and β-cyanobacteria (Synechococcus spp. PCC7942) with similar inorganic carbon (Ci; as CO2 and HCO3−) transporter systems. Despite evolutionary and structural differences between α-carboxysomes and β-carboxysomes, we found that the two strains are remarkably similar in many physiological parameters, particularly the response of photosynthesis to light and external Ci and their modulation of internal ribulose-1,5-bisphosphate, phosphoglycerate, and Ci pools when grown under comparable conditions. In addition, the different Rubisco forms present in each carboxysome had almost identical kinetic parameters. The conclusions indicate that the possession of different carboxysome types does not significantly influence the physiological function of these species and that similar carboxysome function may be possessed by each carboxysome type. Interestingly, both carboxysome types showed a response to cytosolic Ci, which is of higher affinity than predicted by current models, being saturated by 5 to 15 mm Ci. This finding has bearing on the viability of transplanting functional carboxysomes into the C3 chloroplast. PMID:24642960

Characterization of three bioenergetically active respiratory terminal oxidases in the cyanobacterium Synechocystis sp. strain PCC 6803.

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Pils, D; Schmetterer, G

2001-09-25

Synechocystis sp. PCC 6803 contains three respiratory terminal oxidases (RTOs): cytochrome c oxidase (Cox), quinol oxidase (Cyd), and alternate RTO (ARTO). Mutants lacking combinations of the RTOs were used to characterize these key enzymes of respiration. Pentachlorophenol and 2-heptyl-4-hydroxy-quinoline-N-oxide inhibited Cyd completely, but had little effect on electron transport to the other RTOs. KCN inhibited all three RTOs but the in vivo K(I) for Cox and Cyd was quite different (7 vs. 27 microM), as was their affinity for oxygen (K(M) 1.0 vs. 0.35 microM). ARTO has a very low respiratory activity. However, when uptake of 3-O-methylglucose, an active H+ co-transport, was used to monitor energization of the cytoplasmic membrane, ARTO was similarly effective as the other RTOs. As removal of the gene for cytochrome c(553) had the same effects as removal of ARTO genes, we propose that the ARTO might be a second Cox. The possible functions, localization and regulation of the RTOs are discussed.

Function and Regulation of Ferredoxins in the Cyanobacterium, Synechocystis PCC6803: Recent Advances.

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Cassier-Chauvat, Corinne; Chauvat, Franck

2014-11-07

Ferredoxins (Fed), occurring in most organisms, are small proteins that use their iron-sulfur cluster to distribute electrons to various metabolic pathways, likely including hydrogen production. Here, we summarize the current knowledge on ferredoxins in cyanobacteria, the prokaryotes regarded as important producers of the oxygenic atmosphere and biomass for the food chain, as well as promising cell factories for biofuel production. Most studies of ferredoxins were performed in the model strain, Synechocystis PCC6803, which possesses nine highly-conserved ferredoxins encoded by monocistronic or operonic genes, some of which are localized in conserved genome regions. Fed1, encoded by a light-inducible gene, is a highly abundant protein essential to photosynthesis. Fed2-Fed9, encoded by genes differently regulated by trophic conditions, are low-abundant proteins that play prominent roles in the tolerance to environmental stresses. Concerning the selectivity/redundancy of ferredoxin, we report that Fed1, Fed7 and Fed9 belong to ferredoxin-glutaredoxin-thioredoxin crosstalk pathways operating in the protection against oxidative and metal stresses. Furthermore, Fed7 specifically interacts with a DnaJ-like protein, an interaction that has been conserved in photosynthetic eukaryotes in the form of a composite protein comprising DnaJ- and Fed7-like domains. Fed9 specifically interacts with the Flv3 flavodiiron protein acting in the photoreduction of O2 to H2O.

Function and Regulation of Ferredoxins in the Cyanobacterium, Synechocystis PCC6803: Recent Advances

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Corinne Cassier-Chauvat

2014-11-01

Full Text Available Ferredoxins (Fed, occurring in most organisms, are small proteins that use their iron-sulfur cluster to distribute electrons to various metabolic pathways, likely including hydrogen production. Here, we summarize the current knowledge on ferredoxins in cyanobacteria, the prokaryotes regarded as important producers of the oxygenic atmosphere and biomass for the food chain, as well as promising cell factories for biofuel production. Most studies of ferredoxins were performed in the model strain, Synechocystis PCC6803, which possesses nine highly-conserved ferredoxins encoded by monocistronic or operonic genes, some of which are localized in conserved genome regions. Fed1, encoded by a light-inducible gene, is a highly abundant protein essential to photosynthesis. Fed2-Fed9, encoded by genes differently regulated by trophic conditions, are low-abundant proteins that play prominent roles in the tolerance to environmental stresses. Concerning the selectivity/redundancy of ferredoxin, we report that Fed1, Fed7 and Fed9 belong to ferredoxin-glutaredoxin-thioredoxin crosstalk pathways operating in the protection against oxidative and metal stresses. Furthermore, Fed7 specifically interacts with a DnaJ-like protein, an interaction that has been conserved in photosynthetic eukaryotes in the form of a composite protein comprising DnaJ- and Fed7-like domains. Fed9 specifically interacts with the Flv3 flavodiiron protein acting in the photoreduction of O2 to H2O.

Photosynthetic Versatility in the Genome of Geitlerinema sp. PCC 9228 (Formerly Oscillatoria limnetica 'Solar Lake'), a Model Anoxygenic Photosynthetic Cyanobacterium.

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Grim, Sharon L; Dick, Gregory J

2016-01-01

Anoxygenic cyanobacteria that use sulfide as the electron donor for photosynthesis are a potentially influential but poorly constrained force on Earth's biogeochemistry. Their versatile metabolism may have boosted primary production and nitrogen cycling in euxinic coastal margins in the Proterozoic. In addition, they represent a biological mechanism for limiting the accumulation of atmospheric oxygen, especially before the Great Oxidation Event and in the low-oxygen conditions of the Proterozoic. In this study, we describe the draft genome sequence of Geitlerinema sp. PCC 9228, formerly Oscillatoria limnetica 'Solar Lake', a mat-forming diazotrophic cyanobacterium that can switch between oxygenic photosynthesis and sulfide-based anoxygenic photosynthesis (AP). Geitlerinema possesses three variants of psbA , which encodes protein D1, a core component of the photosystem II reaction center. Phylogenetic analyses indicate that one variant is closely affiliated with cyanobacterial psbA genes that code for a D1 protein used for oxygen-sensitive processes. Another version is phylogenetically similar to cyanobacterial psbA genes that encode D1 proteins used under microaerobic conditions, and the third variant may be cued to high light and/or elevated oxygen concentrations. Geitlerinema has the canonical gene for sulfide quinone reductase (SQR) used in cyanobacterial AP and a putative transcriptional regulatory gene in the same operon. Another operon with a second, distinct sqr and regulatory gene is present, and is phylogenetically related to sqr genes used for high sulfide concentrations. The genome has a comprehensive nif gene suite for nitrogen fixation, supporting previous observations of nitrogenase activity. Geitlerinema possesses a bidirectional hydrogenase rather than the uptake hydrogenase typically used by cyanobacteria in diazotrophy. Overall, the genome sequence of Geitlerinema sp. PCC 9228 highlights potential cyanobacterial strategies to cope with fluctuating

Hydrogen production by the engineered cyanobacterial strain Nostoc PCC 7120 ΔhupW examined in a flat panel photobioreactor system.

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Nyberg, Marcus; Heidorn, Thorsten; Lindblad, Peter

2015-12-10

Nitrogenase based hydrogen production was examined in a ΔhupW strain of the filamentous heterocystous cyanobacterium Nostoc PCC 7120, i.e., cells lacking the last step in the maturation system of the large subunit of the uptake hydrogenase and as a consequence with a non-functional uptake hydrogenase. The cells were grown in a developed flat panel photobioreactor system with 3.0L culture volume either aerobically (air) or anaerobically (Ar or 80% N2/20% Ar) and illuminated with a mixture of red and white LED. Aerobic growth of the ΔhupW strain of Nostoc PCC 7120 at 44μmolar photons m(-2)s(-1) PAR gave the highest hydrogen production of 0.7mL H2 L(-1)h(-1), 0.53mmol H2 mg chlorophyll a(-1)h(-1), and a light energy conversion efficiency of 1.2%. Anaerobic growth using 100% argon showed a maximal hydrogen production of 1.7mLL(-1)h(-1), 0.85mmol per mg chlorophyll a(-1) h(-1), and a light energy conversion efficiency of 2.7%. Altering between argon/N2 (20/80) and 100% argon phases resulted in a maximal hydrogen production at hour 128 (100% argon phase) with 6.2mL H2L(-1)h(-1), 0.71mL H2 mg chlorophyll a(-1)h(-1), and a light energy efficiency conversion of 4.0%. The highest buildup of hydrogen gas observed was 6.89% H2 (100% argon phase) of the total photobioreactor system with a maximal production of 4.85mL H2 L(-1)h(-1). The present study clearly demonstrates the potential to use purpose design cyanobacteria in developed flat panel photobioreactor systems for the direct production of the solar fuel hydrogen. Further improvements in the strain used, environmental conditions employed, and growth, production and collection systems used, are needed before a sustainable and economical cyanobacterial based hydrogen production can be realized. Copyright © 2015 Elsevier B.V. All rights reserved.

Monitoring Photosynthesis in Individual Cells of Synechocystis sp. PCC 6803 on a Picosecond Timescale

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Krumova, S.B.; Laptenok, S.P.; Borst, J.W.; Ughy, B.; Gombos, Z.; Ajlani, G.; van Amerongen, H.

2010-01-01

Picosecond fluorescence kinetics of wild-type (WT) and mutant cells of Synechocystis sp. PCC 6803, were studied at the ensemble level with a streak-camera and at the cell level using fluorescence-lifetime-imaging microscopy (FLIM). The FLIM measurements are in good agreement with the ensemble measurements, but they (can) unveil variations between and within cells. The BE mutant cells, devoid of photosystem II (PSII) and of the light-harvesting phycobilisomes, allowed the study of photosystem I (PSI) in vivo for the first time, and the observed 6-ps equilibration process and 25-ps trapping process are the same as found previously for isolated PSI. No major differences are detected between different cells. The PAL mutant cells, devoid of phycobilisomes, show four lifetimes: ∼20 ps (PSI and PSII), ∼80 ps, ∼440 ps, and 2.8 ns (all due to PSII), but not all cells are identical and variations in the kinetics are traced back to differences in the PSI/PSII ratio. Finally, FLIM measurements on WT cells reveal that in some cells or parts of cells, phycobilisomes are disconnected from PSI/PSII. It is argued that the FLIM setup used can become instrumental in unraveling photosynthetic regulation mechanisms in the future. PMID:20858447

Biochemical Characterization of Putative Adenylate Dimethylallyltransferase and Cytokinin Dehydrogenase from Nostoc sp. PCC 7120.

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Frébortová, Jitka; Greplová, Marta; Seidl, Michael F; Heyl, Alexander; Frébort, Ivo

2015-01-01

Cytokinins, a class of phytohormones, are adenine derivatives common to many different organisms. In plants, these play a crucial role as regulators of plant development and the reaction to abiotic and biotic stress. Key enzymes in the cytokinin synthesis and degradation in modern land plants are the isopentyl transferases and the cytokinin dehydrogenases, respectively. Their encoding genes have been probably introduced into the plant lineage during the primary endosymbiosis. To shed light on the evolution of these proteins, the genes homologous to plant adenylate isopentenyl transferase and cytokinin dehydrogenase were amplified from the genomic DNA of cyanobacterium Nostoc sp. PCC 7120 and expressed in Escherichia coli. The putative isopentenyl transferase was shown to be functional in a biochemical assay. In contrast, no enzymatic activity was detected for the putative cytokinin dehydrogenase, even though the principal domains necessary for its function are present. Several mutant variants, in which conserved amino acids in land plant cytokinin dehydrogenases had been restored, were inactive. A combination of experimental data with phylogenetic analysis indicates that adenylate-type isopentenyl transferases might have evolved several times independently. While the Nostoc genome contains a gene coding for protein with characteristics of cytokinin dehydrogenase, the organism is not able to break down cytokinins in the way shown for land plants.

Near infrared fluorescent biliproteins generated from bacteriophytochrome AphB of Nostoc sp. PCC 7120.

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Yuan, Che; Li, Hui-Zhen; Tang, Kun; Gärtner, Wolfgang; Scheer, Hugo; Zhou, Ming; Zhao, Kai-Hong

2016-04-01

The genome of the cyanobacterium Nostoc sp. PCC 7120 encodes a large number of putative bacteriophytochrome and cyanobacteriochrome photoreceptors that, due to their long-wavelength absorption and fluorescence emission, might serve as fluorescent tags in intracellular investigations. We show that the PAS-GAF domain of the bacteriophytochrome, AphB, binds biliverdin covalently and exhibits, besides its reversible photochemistry, a moderate fluorescence in the near infrared (NIR) spectral region. It was selected for further increasing the brightness while retaining the NIR fluorescence. In the first step, amino acids assumed to improve fluorescence were selectively mutated. The resulting variants were then subjected to several rounds of random mutagenesis and screened for enhanced fluorescence in the NIR. The brightness of optimized PAS-GAF variants increased more than threefold compared to that of wt AphB(1-321), with only insignificant spectral shifts (Amax around 695 nm, and Fmax around 720 nm). In general, the brightness increases with decreasing wavelengths, which allows for a selection of the fluorophore depending on the optical properties of the tissue. A spectral heterogeneity was observed when residue His260, located in close proximity to the chromophore, was mutated to Tyr, emphasizing the strong effects of the environment on the electronic properties of the bound biliverdin chromophore.

The role of Slr0151, a tetratricopeptide repeat protein from Synechocystis sp. PCC 6803, during Photosystem II assembly and repair

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Anna eRast

2016-05-01

Full Text Available The assembly and repair of photosystem II (PSII is facilitated by a variety of assembly factors. Among those, the tetratricopeptide repeat (TPR protein Slr0151 from Synechocystis sp. PCC 6803 (hereafter Synechocystis has previously been assigned a repair function under high light conditions (Yang et al., 2014, J. Integr. Plant Biol. 56, 1136-50. Here, we show that inactivation of Slr0151 affects thylakoid membrane ultrastructure even under normal light conditions. Moreover, the level and localization of Slr0151 are affected in a variety of PSII-related mutants. In particular, the data suggest a close functional relationship between Slr0151 and Sll0933, which interacts with Ycf48 during PSII assembly and is homologous to PAM68 in Arabidopsis thaliana. Immunofluorescence analysis revealed a punctate distribution of Slr0151 within several different membrane types in Synechocystis cells.

Seawater cultivation of freshwater cyanobacterium Synechocystis sp. PCC 6803 drastically alters amino acid composition and glycogen metabolism

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Hiroko eIijima

2015-04-01

Full Text Available Water use assessment is important for bioproduction using cyanobacteria. For eco-friendly reasons, seawater should preferably be used for cyanobacteria cultivation instead of freshwater. In this study, we demonstrated that the freshwater unicellular cyanobacterium Synechocystis sp. PCC 6803 could be grown in a medium based on seawater. The Synechocystis wild-type strain grew well in an artificial seawater (ASW medium supplemented with nitrogen and phosphorus sources. The addition of HEPES buffer improved cell growth overall, although the growth in ASW medium was inferior to that in the synthetic BG-11 medium. The levels of proteins involved in sugar metabolism changed depending on the culture conditions. The biosynthesis of several amino acids including aspartate, glutamine, glycine, proline, ornithine, and lysine, was highly up-regulated by cultivation in ASW. Two types of natural seawater (NSW were also made available for the cultivation of Synechocystis cells, with supplementation of both nitrogen and phosphorus sources. These results revealed the potential use of seawater for the cultivation of freshwater cyanobacteria, which would help to reduce freshwater consumption during biorefinery using cyanobacteria.

Effects of selected electron transport chain inhibitors on 24-h hydrogen production by Synechocystis sp. PCC 6803.

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Burrows, Elizabeth H; Chaplen, Frank W R; Ely, Roger L

2011-02-01

One factor limiting biosolar hydrogen (H(2)) production from cyanobacteria is electron availability to the hydrogenase enzyme. In order to optimize 24-h H(2) production this study used Response Surface Methodology and Q2, an optimization algorithm, to investigate the effects of five inhibitors of the photosynthetic and respiratory electron transport chains of Synechocystis sp. PCC 6803. Over 3 days of diurnal light/dark cycling, with the optimized combination of 9.4 mM KCN (3.1 μmol 10(10) cells(-1)) and 1.5 mM malonate (0.5 μmol 10(10) cells(-1)) the H(2) production was 30-fold higher, in EHB-1 media previously optimized for nitrogen (N), sulfur (S), and carbon (C) concentrations (Burrows et al., 2008). In addition, glycogen concentration was measured over 24 h with two light/dark cycling regimes in both standard BG-11 and EHB-1 media. The results suggest that electron flow as well as glycogen accumulation should be optimized in systems engineered for maximal H(2) output. Copyright © 2010 Elsevier Ltd. All rights reserved.

PfsR is a key regulator of iron homeostasis in Synechocystis PCC 6803.

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Dan Cheng

Full Text Available Iron is an essential cofactor in numerous cellular processes. The iron deficiency in the oceans affects the primary productivity of phytoplankton including cyanobacteria. In this study, we examined the function of PfsR, a TetR family transcriptional regulator, in iron homeostasis of the cyanobacterium Synechocystis PCC 6803. Compared with the wild type, the pfsR deletion mutant displayed stronger tolerance to iron limitation and accumulated significantly more chlorophyll a, carotenoid, and phycocyanin under iron-limiting conditions. The mutant also maintained more photosystem I and photosystem II complexes than the wild type after iron deprivation. In addition, the activities of photosystem I and photosystem II were much higher in pfsR deletion mutant than in wild-type cells under iron-limiting conditions. The transcripts of pfsR were enhanced by iron limitation and inactivation of the gene affected pronouncedly expression of fut genes (encoding a ferric iron transporter, feoB (encoding a ferrous iron transporter, bfr genes (encoding bacterioferritins, ho genes (encoding heme oxygenases, isiA (encoding a chlorophyll-binding protein, and furA (encoding a ferric uptake regulator. The iron quota in pfsR deletion mutant cells was higher than in wild-type cells both before and after exposure to iron limitation. Electrophoretic mobility shift assays showed that PfsR bound to its own promoter and thereby auto-regulated its own expression. These data suggest that PfsR is a critical regulator of iron homeostasis.

From PII signaling to metabolite sensing: a novel 2-oxoglutarate sensor that details PII-NAGK complex formation.

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Jan Lüddecke

Full Text Available The widespread PII signal transduction proteins are known for integrating signals of nitrogen and energy supply and regulating cellular behavior by interacting with a multitude of target proteins. The PII protein of the cyanobacterium Synechococcus elongatus forms complexes with the controlling enzyme of arginine synthesis, N-acetyl-L-glutamate kinase (NAGK in a 2-oxoglutarate- and ATP/ADP-dependent manner. Fusing NAGK and PII proteins to either CFP or YFP yielded a FRET sensor that specifically responded to 2-oxoglutarate. The impact of the fluorescent tags on PII and NAGK was evaluated by enzyme assays, surface plasmon resonance spectroscopy and isothermal calorimetric experiments. The developed FRET sensor provides real-time data on PII - NAGK interaction and its modulation by the effector molecules ATP, ADP and 2-oxoglutarate in vitro. Additionally to its utility to monitor 2-oxoglutarate levels, the FRET assay provided novel insights into PII - NAGK complex formation: (i It revealed the formation of an encounter-complex between PII and NAGK, which holds the proteins in proximity even in the presence of inhibitors of complex formation; (ii It revealed that the PII T-loop residue Ser49 is neither essential for complex formation with NAGK nor for activation of the enzyme but necessary to form a stable complex and efficiently relieve NAGK from arginine inhibition; (iii It showed that arginine stabilizes the NAGK hexamer and stimulates PII - NAGK interaction.

Diversidade genética de três estoques de piapara (Leporinus elongatus, utilizando RAPD - DOI: 10.4025/actascianimsci.v30i2.4710 Genetic diversity of three stocks of piapara (Leporinus elongatus, using RAPD - DOI: 10.4025/actascianimsci.v30i2.4710

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Lauro Vargas

2008-08-01

Full Text Available Recentemente a produção aquícola brasileira tem apresentado grande progresso. Dentre as espécies nativas cultivadas no Brasil, a piapara (Leporinus elongatus tem sido amplamente preconizada. Com objetivo de avaliar os programas de repovoamento, foram analisadas a variabilidade e a divergência genética de três estoques de piapara com a técnica de RAPD (Random Amplified Polymorphic. O primeiro estoque pertence à Estação de Aquicultura e Hidrologia da Duke Energy International (A; o segundo, à piscicultura de Rolândia (B e o terceiro, ao Programa de Repovoamento dos Rios do Paraná (C. Os dez primers para RAPD utilizados produziram 105 fragmentos polimórficos, conferindo um polimorfismo de 98,1% para os três estoques avaliados. A porcentagem de locos polimórficos e índice de Shannon foi superior para o estoque A. Porém, todos valores foram elevados, indicando alta diversidade intrapopulacional. Os valores de indicam que houve baixa diferenciação genética entre os estoques A x B e moderada diferenciação entre os demais. O Nm foi maior entre os estoques A x B. A distância genética e o dendrograma indicam que os estoques A x B são menos distantes geneticamente.Latelly, aquiculture production in Brazil has made great strides. Among the native species cultivated in Brazil, piapara (Leporinus elogatus has been widely praised. With the objective of evaluating restocking programs, the variability and genetic divergence of three piapara stocks were analyzed using the RAPD (Random Amplified Polymorphic DNA technique. The first stock belongs to the Aquiculture and Hydrology Station of Duke Energy International (A; the second one belongs to a fish farm in the city of Rolândia (B; and the third to the River Restocking Program of Paraná (C. The ten primers used for RAPD produced 105 polymorphic loci, conferring a polymorphism of 98.1% for the three evaluated stocks. Polymorphic loci percentage and Shannon index were higher for stock A

Biocomputional construction of a gene network under acid stress in Synechocystis sp. PCC 6803.

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Li, Yi; Rao, Nini; Yang, Feng; Zhang, Ying; Yang, Yang; Liu, Han-ming; Guo, Fengbiao; Huang, Jian

2014-01-01

Acid stress is one of the most serious threats that cyanobacteria have to face, and it has an impact at all levels from genome to phenotype. However, very little is known about the detailed response mechanism to acid stress in this species. We present here a general analysis of the gene regulatory network of Synechocystis sp. PCC 6803 in response to acid stress using comparative genome analysis and biocomputational prediction. In this study, we collected 85 genes and used them as an initial template to predict new genes through co-regulation, protein-protein interactions and the phylogenetic profile, and 179 new genes were obtained to form a complete template. In addition, we found that 11 enriched pathways such as glycolysis are closely related to the acid stress response. Finally, we constructed a regulatory network for the intricate relationship of these genes and summarize the key steps in response to acid stress. This is the first time a bioinformatic approach has been taken systematically to gene interactions in cyanobacteria and the elaboration of their cell metabolism and regulatory pathways under acid stress, which is more efficient than a traditional experimental study. The results also provide theoretical support for similar research into environmental stresses in cyanobacteria and possible industrial applications. Copyright © 2014 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Proteomic responses of oceanic Synechococcus WH8102 to phosphate and zinc scarcity and cadmium additions

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Alysia eCox

2013-12-01

Full Text Available Synechococcus sp. WH 8102 is a motile marine cyanobacterium isolated originally from the Sargasso Sea. To test the response of this organism to cadmium (Cd -generally considered a toxin- cultures were grown in a matrix of high and low zinc (Zn and phosphate (PO43- and were then exposed to an addition of 4.4 pM free Cd2+ at mid-log phase and harvested after 24 h. Whereas Zn and PO43- had little effect on overall growth rates, in the final 24 h of the experiment three growth effects were noticed: i low PO43- treatments showed increased growth rates relative to high PO43- treatments, ii the Zn/high PO43- treatment appeared to enter stationary phase, and iii Cd increased growth rates further in both the low PO43- and Zn treatments. Global proteomic analysis revealed that: i Zn appeared to be critical to the PO43- response in this organism, ii bacterial metallothionein (SmtA appears correlated with PO43- stress-associated proteins, iii Cd has the greatest influence on the proteome at low PO43- and Zn, iv Zn buffered the effects of Cd, and v in the presence of both replete PO43- and added Cd the proteome showed little response to the presence of Zn. Similar trends in alkaline phosphate (ALP and SmtA suggest the possibility of a Zn supply system to provide Zn to ALP that involves SmtA. In addition, proteome results were consistent with a previous transcriptome study of PO43- stress (with replete Zn in this organism, including the greater relative abundance of ALP (PhoA, ABC phosphate binding protein (PstS and other proteins. Yet with no Zn in this proteome experiment the PO43- response was quite different including the greater relative abundance of five hypothetical proteins with no increase in PhoA or PstS, suggesting that Zn nutritional levels are connected to the PO43- response in this cyanobacterium. Alternate ALP PhoX (Ca was found to be a low abundance protein, suggesting that PhoA (Zn, Mg may be more environmentally relevant than PhoX.

Bioinformatic evaluation of L-arginine catabolic pathways in 24 cyanobacteria and transcriptional analysis of genes encoding enzymes of L-arginine catabolism in the cyanobacterium Synechocystis sp. PCC 6803

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Pistorius Elfriede K

2007-11-01

Full Text Available Abstract Background So far very limited knowledge exists on L-arginine catabolism in cyanobacteria, although six major L-arginine-degrading pathways have been described for prokaryotes. Thus, we have performed a bioinformatic analysis of possible L-arginine-degrading pathways in cyanobacteria. Further, we chose Synechocystis sp. PCC 6803 for a more detailed bioinformatic analysis and for validation of the bioinformatic predictions on L-arginine catabolism with a transcript analysis. Results We have evaluated 24 cyanobacterial genomes of freshwater or marine strains for the presence of putative L-arginine-degrading enzymes. We identified an L-arginine decarboxylase pathway in all 24 strains. In addition, cyanobacteria have one or two further pathways representing either an arginase pathway or L-arginine deiminase pathway or an L-arginine oxidase/dehydrogenase pathway. An L-arginine amidinotransferase pathway as a major L-arginine-degrading pathway is not likely but can not be entirely excluded. A rather unusual finding was that the cyanobacterial L-arginine deiminases are substantially larger than the enzymes in non-photosynthetic bacteria and that they are membrane-bound. A more detailed bioinformatic analysis of Synechocystis sp. PCC 6803 revealed that three different L-arginine-degrading pathways may in principle be functional in this cyanobacterium. These are (i an L-arginine decarboxylase pathway, (ii an L-arginine deiminase pathway, and (iii an L-arginine oxidase/dehydrogenase pathway. A transcript analysis of cells grown either with nitrate or L-arginine as sole N-source and with an illumination of 50 μmol photons m-2 s-1 showed that the transcripts for the first enzyme(s of all three pathways were present, but that the transcript levels for the L-arginine deiminase and the L-arginine oxidase/dehydrogenase were substantially higher than that of the three isoenzymes of L-arginine decarboxylase. Conclusion The evaluation of 24

Looking at the stability of life-support microorganisms in space : the MELGEN activity highlights the cyanobacterium Arthrospira sp. PCC8005

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Morin, Nicolas

The MELGEN activity (MELiSSA Genetic Stability Study) mainly covers the molecular aspects of the regenerative life-support system MELiSSA (Micro-Ecological Life Support System Alternative) of the European Space Agency (ESA). The general objective of MELGEN is to establish and validate methods and the related hardware in order to detect genetic instability and microbial contaminants in the MELISSA compartments. This includes (1) a genetic description of the MELISSA strains, (2) studies of microbial behavior and genetic stability in bioreactors and (3) the detection of chemical, genetical and biological contamination and their effect on microbial metabolism. Selected as oxygen producer and complementary food source, the cyanobacterium Arthrospira sp. PCC8005 plays a major role within the MELiSSA loop. As the genomic information on this organism was insufficient, sequencing of its genome was proposed at the French National Sequencing Center, Genoscope, as a joint effort between ESA and different laboratories. So far, a preliminary assembly of 16 contigs representing circa 6.3 million basepairs was obtained. Even though the finishing of the genome is on its way, automatic annotation of the contigs has already been performed on the MaGe annotation platform, and curation of the sequence is currently being carried out, with a special focus on biosynthesis pathways, photosynthesis, and maintenance processes of the cell. According to the index of repetitiveness described by Haubold and Wiehe (2006), we discovered that the genome of Arthrospira sp. is among the 50 most repeated bacterial genomes sequenced to date. Thanks to the sequencing project, we have identified and catalogued mobile genetics elements (MGEs) dispersed throughout the unique chromosome of this cyanobacterium. They represent a quite large proportion of the genome, as genes identified as putative transposases are indeed found in circa 5 Results : We currently have a first draft of the complete genome of

Multiplex PCR assay for detection of recombinant genes encoding fatty acid desaturases fused with lichenase reporter protein in GM plants.

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Berdichevets, Iryna N; Shimshilashvili, Hristina R; Gerasymenko, Iryna M; Sindarovska, Yana R; Sheludko, Yuriy V; Goldenkova-Pavlova, Irina V

2010-07-01

Thermostable lichenase encoded by licB gene of Clostridium thermocellum can be used as a reporter protein in plant, bacterial, yeast, and mammalian cells. It has important advantages of high sensitivity and specificity in qualitative and quantitative assays. Deletion variants of LicB (e.g., LicBM3) retain its enzymatic activity and thermostability and can be expressed in translational fusion with target proteins without compromising with their properties. Fusion with the lichenase reporter is especially convenient for the heterologous expression of proteins whose analysis is difficult or compromised by host enzyme activities, as it is in case of fatty acid desaturases occurring in all groups of organisms. Recombinant desaturase-lichenase genes can be used for creating genetically modified (GM) plants with improved chill tolerance. Development of an analytical method for detection of fused desaturase-lichenase transgenes is necessary both for production of GM plants and for their certification. Here, we report a multiplex polymerase chain reaction method for detection of desA and desC desaturase genes of cyanobacteria Synechocystis sp. PCC6803 and Synechococcus vulcanus, respectively, fused to licBM3 reporter in GM plants.

Genetic variability of wild populations of Leporinus elongatus in the São Domingos River - MS Brazil: a preliminary view on the construction of the hydroelectric plant

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Ricardo Pereira Ribeiro

2016-09-01

Full Text Available Most of the electricity used in Brazil comes from hydroelectric plants, mainly due to the great availability of its water resources. However, the construction of these plants denotes serious problems related to migration of native fish and the genetic conservation of stocks. Current study evaluates two wild population of Leporinus elongatus (piapara located downstream (Population A - PopA and upstream (Population B - PopB of the Cachoeira Branca before the construction of the São Domingos hydroelectric plant (HPP in the Mato Grosso do Sul State, Brazil. Thirty samples from caudal fins were collected and analyzed for each population. Eighty-nine fragments, including 72 polymorphic ones (80.9%, were analyzed. Low fragments (less than 0.100 in both populations (PopA = 2 and PopB = 3 were identified. Nine fixed fragments (frequency 1.000 (PopA = 3 and PopB = 6, and four exclusive fragments (PopA = 3 and PopB = 1 were also reported. The genetic variability within populations, calculated by Shannon Index and by percentage of polymorphic fragments, indicated high rates of intrapopulation variability (PopA = 0.309 and 61.80% and PopB = 0.392 and 71.90%, respectively. Genetic distance and identity rates (0.089 and 0.915, respectively were different between populations, whilst AMOVA showed that most variations lie within the populations and not between them. Fst and Nm rates showed moderate genetic differentiation with low numbers of migrants. Results reveal populations with high intra-population genetic variability and genetic differentiation, with low gene flow. The passage ladders of São Domingos HPP should control fish transposition to preserve genetic variability.

A revised geographical range for Liolaemus elongates Koslowsky, 1896 (Squamata: Liolaemini in Argentina: review of reported and new-data based distribution with new localities

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Ignacio Minoli

2013-12-01

Full Text Available Estimating the effective geographical ranges of species is central to species-oriented conservation and management. In this paper, we review the geographical distribution of Liolaemus elongatus Koslowsky, 1896 with three new records for northern Chubut and southern Río Negro provinces, Argentina. Based on detailed locality records pooled from multiple data sources, including new records obtained for this study, we revise the range of L. elongatus sensu stricto and provide geographical distribution maps comparing the previously recognized range to that proposed herein. Our results show that L. elongatus possesses a much more limited geographic distribution than previously thought, being restricted to areas south of 38°S latitude; the newly proposed range is merely half the species formerly recognized geographical distribution.

Proteomic analysis reveals resistance mechanism against biofuel hexane in Synechocystis sp. PCC 6803

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Liu Jie

2012-09-01

Full Text Available Abstract Background Recent studies have demonstrated that photosynthetic cyanobacteria could be an excellent cell factory to produce renewable biofuels and chemicals due to their capability to utilize solar energy and CO2 as the sole energy and carbon sources. Biosynthesis of carbon-neutral biofuel alkanes with good chemical and physical properties has been proposed. However, to make the process economically feasible, one major hurdle to improve the low cell tolerance to alkanes needed to be overcome. Results Towards the goal to develop robust and high-alkane-tolerant hosts, in this study, the responses of model cyanobacterial Synechocystis PCC 6803 to hexane, a representative of alkane, were investigated using a quantitative proteomics approach with iTRAQ - LC-MS/MS technologies. In total, 1,492 unique proteins were identified, representing about 42% of all predicted protein in the Synechocystis genome. Among all proteins identified, a total of 164 and 77 proteins were found up- and down-regulated, respectively. Functional annotation and KEGG pathway enrichment analyses showed that common stress responses were induced by hexane in Synechocystis. Notably, a large number of transporters and membrane-bound proteins, proteins against oxidative stress and proteins related to sulfur relay system and photosynthesis were induced, suggesting that they are possibly the major protection mechanisms against hexane toxicity. Conclusion The study provided the first comprehensive view of the complicated molecular mechanism employed by cyanobacterial model species, Synechocystis to defend against hexane stress. The study also provided a list of potential targets to engineer Synechocystis against hexane stress.

Contribution of two ζ-carotene desaturases to the poly-cis desaturation pathway in the cyanobacterium Nostoc PCC 7120.

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Breitenbach, Jürgen; Bruns, Marius; Sandmann, Gerhard

2013-07-01

The presence of two completely unrelated ζ-carotene desaturases CrtQa and CrtQb in some Nostoc strains is unique. CrtQb is the ζ-carotene desaturase, which was acquired by almost all cyanobacteria. The additional CrtQa can be regarded as an evolutionary relict of the CrtI desaturase present in non-photosynthetic bacteria. By reconstruction of the carotene desaturation pathway, we showed that both enzymes from Nostoc PCC 7120 were active. However, they differed in their preferred utilization of ζ-carotene Z isomers. CrtQa converted ζ-carotene isomers that were poorly metabolized by CrtQb. In this respect, CrtQa complemented the reactions of CrtQb, which is an advantage avoiding dead ends in the poly-cis desaturation pathway. In addition to ζ-carotene desaturation, CrtQa still possesses the Z to E isomerase function of the ancestral desaturase CrtI. Biochemical characterization showed that CrtQb is an enzyme with one molecule of tightly bound FAD and acts as a dehydrogenase transferring hydrogen to oxidized plastoquinone.

Seasonal dynamics of Pseudocalanus minutus elongatus and Acartia spp. in the southern Baltic Sea (Gdańsk Deep – numerical simulations

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L. Dzierzbicka-Głowacka

2006-01-01

Full Text Available A population dynamics model for copepods is presented, describing the seasonal dynamics of Pseudocalanus minutus elongatus and Acartia spp. in the southern Baltic Sea (Gdańsk Deep. The copepod model was coupled with a one-dimensional physical and biological upper layer model for nutrients (total inorganic nitrogen, phosphate, phytoplankton, microzooplankton, and an early juvenile of herring as a predator. In this model, mesozooplankton (herbivorous copepods has been introduced as an animal having definite patterns of growth in successive stages, reproduction and mortality. The populations are represented by 6 cohorts in different developmental stages, thus assuming that recruitment of the next generation occurs after a fixed period of adult life. The copepod model links trophic processes and population dynamics, and simulates individual growth within cohorts and the changes in biomass between cohorts. The simulations of annual cycles of copepods contain one complete generation of Pseudocalanus and two generations of Acartia in the whole column water, and indicate the importance of growth in the older stages of 6 cohorts of each species, to arrive at a total population biomass. The peaks of copepods' biomass are larger at the turn of June and July for Pseudocalanus and smaller in July for Acartia, lagging that of phytoplankton by ca. two mouths, due to the growth of cohorts in successive stages and egg production by females. The numerical results show that the investigated species could not be the main factor limiting the spring phytoplankton bloom in the Gdańsk Deep, because the initial development was slow for Acartia and faster for Pseudocalanus, but the main development formed after the bloom, in both cases. The phytoplankton bloom is very important in the diet of the adults of the copepods, but it is not particularly important for the youngest part of new generation (early nauplii. However, the simulated microzooplankton biomass was

Physiological regulation of isocitrate dehydrogenase and the role of 2-oxoglutarate in Prochlorococcus sp. strain PCC 9511.

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María Agustina Domínguez-Martín

Full Text Available The enzyme isocitrate dehydrogenase (ICDH; EC 1.1.1.42 catalyzes the oxidative decarboxylation of isocitrate, to produce 2-oxoglutarate. The incompleteness of the tricarboxylic acids cycle in marine cyanobacteria confers a special importance to isocitrate dehydrogenase in the C/N balance, since 2-oxoglutarate can only be metabolized through the glutamine synthetase/glutamate synthase pathway. The physiological regulation of isocitrate dehydrogenase was studied in cultures of Prochlorococcus sp. strain PCC 9511, by measuring enzyme activity and concentration using the NADPH production assay and Western blotting, respectively. The enzyme activity showed little changes under nitrogen or phosphorus starvation, or upon addition of the inhibitors DCMU, DBMIB and MSX. Azaserine, an inhibitor of glutamate synthase, induced clear increases in the isocitrate dehydrogenase activity and icd gene expression after 24 h, and also in the 2-oxoglutarate concentration. Iron starvation had the most significant effect, inducing a complete loss of isocitrate dehydrogenase activity, possibly mediated by a process of oxidative inactivation, while its concentration was unaffected. Our results suggest that isocitrate dehydrogenase responds to changes in the intracellular concentration of 2-oxoglutarate and to the redox status of the cells in Prochlorococcus.

Physical, chemical, and metabolic state sensors expand the synthetic biology toolbox for Synechocystis sp. PCC 6803.

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Immethun, Cheryl M; DeLorenzo, Drew M; Focht, Caroline M; Gupta, Dinesh; Johnson, Charles B; Moon, Tae Seok

2017-07-01

Many under-developed organisms possess important traits that can boost the effectiveness and sustainability of microbial biotechnology. Photoautotrophic cyanobacteria can utilize the energy captured from light to fix carbon dioxide for their metabolic needs while living in environments not suited for growing crops. Various value-added compounds have been produced by cyanobacteria in the laboratory; yet, the products' titers and yields are often not industrially relevant and lag behind what have been accomplished in heterotrophic microbes. Genetic tools for biological process control are needed to take advantage of cyanobacteria's beneficial qualities, as tool development also lags behind what has been created in common heterotrophic hosts. To address this problem, we developed a suite of sensors that regulate transcription in the model cyanobacterium Synechocystis sp. PCC 6803 in response to metabolically relevant signals, including light and the cell's nitrogen status, and a family of sensors that respond to the inexpensive chemical, l-arabinose. Increasing the number of available tools enables more complex and precise control of gene expression. Expanding the synthetic biology toolbox for this cyanobacterium also improves our ability to utilize this important under-developed organism in biotechnology. Biotechnol. Bioeng. 2017;114: 1561-1569. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Absorption and emission spectroscopic characterization of blue-light receptor Slr1694 from Synechocystis sp. PCC6803.

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Zirak, P; Penzkofer, A; Lehmpfuhl, C; Mathes, T; Hegemann, P

2007-01-03

The BLUF protein Slr1694 from the cyanobacterium Synechocystis sp. PCC6803 is characterized by absorption and emission spectroscopy. Slr1694 expressed from E. coli which non-covalently binds FAD, FMN, and riboflavin (called Slr1694(I)), and reconstituted Slr1694 which dominantly contains FAD (called Slr1694(II)) are investigated. The receptor conformation of Slr1694 (dark adapted form Slr1694(r)) is transformed to the putative signalling state (light adapted form Slr1694(s)) with red-shifted absorption and decreased fluorescence efficiency by blue-light excitation. In the dark at 22 degrees C, the signalling state recovers back to the initial receptor state with a time constants of about 14.2s for Slr1694(I) and 17s for Slr1694(II). Quantum yields of signalling state formation of approximately 0.63+/-0.07 for both Slr1694(I) and Slr1694(II) were determined by transient transmission measurements and intensity dependent steady-state transmission measurements. Extended blue-light excitation causes some bound flavin conversion to the hydroquinone form and some photo-degradation, both with low quantum efficiency. The flavin-hydroquinone re-oxidizes slowly back (time constant 5-9 min) to the initial flavoquinone form in the dark. A photo-cycle dynamics scheme is presented.

Cadmium toxicity to Microcystis aeruginosa PCC 7806 and its microcystin-lacking mutant.

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Bin Huang

Full Text Available The adverse effects of microcystin (MC produced by cyanobacteria have drawn considerable attention from the public. Yet it remains unclear whether MC confers any benefits to the cyanobacteria themselves. One suggested function of MC is complexation, which may influence the bioaccumulation and toxicity of trace metals. To test this hypothesis, we examined Cd toxicity to wild-type Microcystis aeruginosa PCC 7806 (WT and its MC-lacking mutant (MT under nutrient-enriched (+NP, phosphorus-limited (-P, and nitrogen-limited (-N conditions. The accumulation of Cd and the biochemical parameters associated with its detoxification [total phosphorus (TP, inorganic polyphosphate (Poly-P, and glutathione (GSH in the cells as well as intra- and extra-cellular carbohydrates] were quantified. Although the -P cyanobacteria accumulated less Cd than their +NP and -N counterparts, the different nutrient-conditioned cyanobacteria were similarly inhibited by similar free ion concentration of Cd in the medium ([Cd2+]F. Such good toxicity predictability of [Cd2+]F was ascribed to the synchronous decrease in the intracellular concentrations of Cd and TP. Nevertheless, Cd toxicity was still determined by the intracellular Cd to phosphorus ratio (Cd/P, in accordance with what has been reported in the literature. On the other hand, the concentrations of TP, Poly-P, and carbohydrates went up, but GSH concentration dropped down with the enhancement of [Cd2+]F, indicating their association with Cd detoxification. Although the inactivation of MC peptide synthetase gene had some nutrient and Cd concentration dependent effects on the parameters above, both cyanobacterial strains showed the same Cd accumulation ability and displayed similar Cd sensitivity. These results suggest that MC cannot affect metal toxicity either by regulating metal accumulation or by altering the detoxification ability of the cyanobacteria. Other possible functions of MC need to be further investigated.

Photosynthetic versatility in the genome of Geitlerinema sp. PCC 9228 (formerly Oscillatoria limnetica ‘Solar Lake’, a model anoxygenic photosynthetic cyanobacterium

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Sharon L Grim

2016-10-01

Full Text Available Anoxygenic cyanobacteria that use sulfide as the electron donor for photosynthesis are a potentially influential but poorly constrained force on Earth’s biogeochemistry. Their versatile metabolism may have boosted primary production and nitrogen cycling in euxinic coastal margins in the Proterozoic. In addition, they represent a biological mechanism for limiting the accumulation of atmospheric oxygen, especially before the Great Oxidation Event and in the low-oxygen conditions of the Proterozoic. In this study, we describe the draft genome sequence of Geitlerinema sp. PCC 9228, formerly Oscillatoria limnetica ‘Solar Lake’, a mat-forming diazotrophic cyanobacterium that can switch between oxygenic photosynthesis and sulfide-based anoxygenic photosynthesis. Geitlerinema possesses three variants of psbA, which encodes protein D1, a core component of the photosystem II reaction center. Phylogenetic analyses indicate that one variant is closely affiliated with cyanobacterial psbA genes that code for a D1 protein used for oxygen-sensitive processes. Another version is phylogenetically similar to cyanobacterial psbA genes that encode D1 proteins used under microaerobic conditions, and the third variant may be cued to high light and/or elevated oxygen concentrations. Geitlerinema has the canonical gene for sulfide quinone reductase (SQR used in cyanobacterial anoxygenic photosynthesis and a putative transcriptional regulatory gene in the same operon. Another operon with a second, distinct sqr and regulatory gene is present, and is phylogenetically related to sqr genes used for high sulfide concentrations. The genome has a comprehensive nif gene suite for nitrogen fixation, supporting previous observations of nitrogenase activity. Geitlerinema possesses a bidirectional hydrogenase rather than the uptake hydrogenase typically used by cyanobacteria in diazotrophy. Overall, the genome sequence of Geitlerinema sp. PCC 9228 highlights potential

Photosynthetic Versatility in the Genome of Geitlerinema sp. PCC 9228 (Formerly Oscillatoria limnetica ‘Solar Lake’), a Model Anoxygenic Photosynthetic Cyanobacterium

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Grim, Sharon L.; Dick, Gregory J.

2016-01-01

Anoxygenic cyanobacteria that use sulfide as the electron donor for photosynthesis are a potentially influential but poorly constrained force on Earth’s biogeochemistry. Their versatile metabolism may have boosted primary production and nitrogen cycling in euxinic coastal margins in the Proterozoic. In addition, they represent a biological mechanism for limiting the accumulation of atmospheric oxygen, especially before the Great Oxidation Event and in the low-oxygen conditions of the Proterozoic. In this study, we describe the draft genome sequence of Geitlerinema sp. PCC 9228, formerly Oscillatoria limnetica ‘Solar Lake’, a mat-forming diazotrophic cyanobacterium that can switch between oxygenic photosynthesis and sulfide-based anoxygenic photosynthesis (AP). Geitlerinema possesses three variants of psbA, which encodes protein D1, a core component of the photosystem II reaction center. Phylogenetic analyses indicate that one variant is closely affiliated with cyanobacterial psbA genes that code for a D1 protein used for oxygen-sensitive processes. Another version is phylogenetically similar to cyanobacterial psbA genes that encode D1 proteins used under microaerobic conditions, and the third variant may be cued to high light and/or elevated oxygen concentrations. Geitlerinema has the canonical gene for sulfide quinone reductase (SQR) used in cyanobacterial AP and a putative transcriptional regulatory gene in the same operon. Another operon with a second, distinct sqr and regulatory gene is present, and is phylogenetically related to sqr genes used for high sulfide concentrations. The genome has a comprehensive nif gene suite for nitrogen fixation, supporting previous observations of nitrogenase activity. Geitlerinema possesses a bidirectional hydrogenase rather than the uptake hydrogenase typically used by cyanobacteria in diazotrophy. Overall, the genome sequence of Geitlerinema sp. PCC 9228 highlights potential cyanobacterial strategies to cope with

The role of lantern fish (Myctophidae) in the life-cycle of cetacean parasites from western Mediterranean waters

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Mateu, Paula; Nardi, Valentina; Fraija-Fernández, Natalia; Mattiucci, Simonetta; Gil de Sola, Luis; Raga, Juan Antonio; Fernández, Mercedes; Aznar, Francisco Javier

2015-01-01

Myctophids (lantern fish) and cephalopods play a key role in trophic webs from the continental slope and oceanic waters linking the zooplankton to top predators. Many cetaceans feed on both lantern fish and cephalopods, and such prey would thus be expected to bridge the trophic gap in the life-cycles of helminths infecting cetaceans. However, information on the life-cycles of most of these helminths is extremely scanty. We examined the parasite fauna of myctophids and cephalopods in two areas from the western Mediterranean where at least 21 helminth taxa from cetaceans have been reported and both cetacean diversity and abundance is high. A total of 1012 individuals of 8 lantern fish species, namely, Ceratoscopelus maderensis, Lampanyctus crocodilus, Notoscopelus elongatus, Benthosema glaciale, Myctophum punctatum, Lobianchia dofleini, Diaphus holti and Hygophum benoiti, and 792 individuals of 2 cephalopod species, Alloteuthis media and Sepietta oweniana, were collected from the Gulf of Valencia and Alboran Sea (Spanish Mediterranean) during 2010-2012 and examined for larval helminths. All these species have been reported as prey for at least some cetacean species in the area. Only five helminth taxa were found. The nematodes Anisakis pegreffii and Anisakis physeteris were detected in N. elongatus and C. maderensis (overall prevalence for Anisakis: 8.1% and 0.5%, respectively). Their prevalence in N. elongatus was significantly higher than that from the other three myctophid species with n>50 individuals. A single individual of Hysterothylacium sp. was found in N. elongatus (prevalence: 0.5%) and Raphidascarididae gen. spp. in N. elongatus and L. crocodilus (prevalence: 20.3% and 0.7%, respectively). Juvenile didymozoid digeneans (Torticaecum type) were detected in N. elongatus and L. crocodilus (prevalence: 18.5% and 4.3%, respectively). Two unidentified cestode plerocercoids were collected from N. elongatus. Our study suggests, for the first time, that myctophids

Recombinant thermoactive phosphoenolpyruvate carboxylase (PEPC) from Thermosynechococcus elongatus and its coupling with mesophilic/thermophilic bacterial carbonic anhydrases (CAs) for the conversion of CO2 to oxaloacetate.

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Del Prete, Sonia; De Luca, Viviana; Capasso, Clemente; Supuran, Claudiu T; Carginale, Vincenzo

2016-01-15

With the continuous increase of atmospheric CO2 in the last decades, efficient methods for carbon capture, sequestration, and utilization are urgently required. The possibility of converting CO2 into useful chemicals could be a good strategy to both decreasing the CO2 concentration and for achieving an efficient exploitation of this cheap carbon source. Recently, several single- and multi-enzyme systems for the catalytic conversion of CO2 mainly to bicarbonate have been implemented. In order to design and construct a catalytic system for the conversion of CO2 to organic molecules, we implemented an in vitro multienzyme system using mesophilic and thermophilic enzymes. The system, in fact, was constituted by a recombinant phosphoenolpyruvate carboxylase (PEPC) from the thermophilic cyanobacterium Thermosynechococcus elongatus, in combination with mesophilic/thermophilic bacterial carbonic anhydrases (CAs), for converting CO2 into oxaloacetate, a compound of potential utility in industrial processes. The catalytic procedure is in two steps: the conversion of CO2 into bicarbonate by CA, followed by the carboxylation of phosphoenolpyruvate with bicarbonate, catalyzed by PEPC, with formation of oxaloacetate (OAA). All tested CAs, belonging to α-, β-, and γ-CA classes, were able to increase OAA production compared to procedures when only PEPC was used. Interestingly, the efficiency of the CAs tested in OAA production was in good agreement with the kinetic parameters for the CO2 hydration reaction of these enzymes. This PEPC also revealed to be thermoactive and thermostable, and when coupled with the extremely thermostable CA from Sulphurhydrogenibium azorense (SazCA) the production of OAA was achieved even if the two enzymes were exposed to temperatures up to 60 °C, suggesting a possible role of the two coupled enzymes in biotechnological processes. Copyright © 2015 Elsevier Ltd. All rights reserved.

Two new Liolaemus lizards from the Andean highlands of Southern Chile (Squamata, Iguania, Liolaemidae)

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Troncoso-Palacios, Jaime; Diaz, Hugo A.; Puas, German I.; Riveros-Riffo, Edvin; Elorza, Alvaro A.

2016-01-01

Abstract Liolaemus is a diverse genus of lizards, subdivided into two subgenera: Liolaemus (sensu stricto) and Eulaemus, distributed mainly in Chile and Argentina. The Liolaemus elongatus-kriegi complex is the most diverse group within Liolaemus (sensu stricto), especially the species closely related to Liolaemus elongatus, which form a clade currently comprising nine species. Several Chilean species of this group have been recently described, mainly from volcanoes and poorly explored mountains. Here molecular and morphological evidence are provided for a new species of the Liolaemus elongatus clade, which is characterized by its small size and lack of dorsal pattern, unusual features for the species of this group of lizards. Additionally, the lack of precloacal pores in males of Liolaemus (sensu stricto) is a trait found in few species, which do not constitute a monophyletic group. A second new southern Chilean species is also described, without precloacal pores and supported by molecular phylogenetics to be related to Liolaemus villaricensis. Both new species were found in the same locality, near a lake located in a pre-Andean zone with Araucaria and Nothofagus forest. The two species are dedicated to prominent Lonkos (tribal chiefs) of the Mapuche and Pehuenche people: Janequeo and Leftraru. Additionally, the phylogenetic results suggest that Liolaemus lonquimayensis is a synonym of Liolaemus elongatus. PMID:27920609

Phosphoproteome of the cyanobacterium Synechocystis sp. PCC 6803 and its dynamics during nitrogen starvation.

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Philipp eSpät

2015-03-01

Full Text Available Cyanobacteria have shaped the earth’s biosphere as the first oxygenic photoautotrophs and still play an important role in many ecosystems. The ability to adapt to changing environmental conditions is an essential characteristic in order to ensure survival. To this end, numerous studies have shown that bacteria use protein post-translational modifications such as Ser/Thr/Tyr phosphorylation in cell signalling, adaptation and regulation. Nevertheless, our knowledge of cyanobacterial phosphoproteomes and their dynamic response to environmental stimuli is relatively limited. In this study, we applied gel-free methods and high accuracy mass spectrometry towards the unbiased detection of Ser/Thr/Tyr phosphorylation events in the model cyanobacterium Synechocystis sp. PCC 6803. We could identify over 300 phosphorylation events in cultures grown on nitrate as exclusive nitrogen source. Chemical dimethylation labelling was applied to investigate proteome and phosphoproteome dynamics during nitrogen starvation. Our dataset describes the most comprehensive (phosphoproteome of Synechocystis to date, identifying 2,382 proteins and 183 phosphorylation events and quantifying 2,111 proteins and 148 phosphorylation events during nitrogen starvation. Global protein phosphorylation levels were increased in response to nitrogen depletion after 24 hours. Among the proteins with increased phosphorylation, the PII signalling protein showed the highest fold-change, serving as positive control. Other proteins with increased phosphorylation levels comprised functions in photosynthesis and in carbon and nitrogen metabolism. This study reveals dynamics of Synechocystis phosphoproteome in response to environmental stimuli and suggests an important role of protein Ser/Thr/Tyr phosphorylation in fundamental mechanisms of homeostatic control in cyanobacteria.

Absorption and emission spectroscopic characterization of BLUF protein Slr1694 from Synechocystis sp. PCC6803 with roseoflavin cofactor.

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Zirak, P; Penzkofer, A; Mathes, T; Hegemann, P

2009-11-09

The wild-type BLUF protein Slr1694 from Synechocystis sp. PCC6803 (BLUF=blue-light sensor using FAD) has flavin adenosine dinucleotide (FAD) as natural cofactor. This light sensor causes positive phototaxis of the marine cyanobacterium. In this study the FAD cofactor of the wild-type Slr1694 was replaced by roseoflavin (RoF) and the roseoflavin derivatives RoFMN and RoFAD during heterologous expression in a riboflavin auxotrophic E. coli strain. An absorption and emission spectroscopic characterization of the cofactor-exchanged-Slr1694 (RoSlr) was carried out both under dark conditions and under illuminated conditions. The behaviour of RoF embedded in RoSlr in aqueous solution at pH 8 is compared with the behaviour of RoF in aqueous solution. The fluorescence of RoF and RoSlr is quenched by photo-induced twisted intra-molecular charge transfer at room temperature with stronger effect for RoF. The fluorescence quenching is diminished at liquid nitrogen temperature. Light exposure of RoSlr causes irreversible conversion of the protein embedded roseoflavins to 8-methylamino-flavins, 8-dimethylamino-lumichrome and 8-methylamino-lumichrome.

In silico screening for candidate chassis strains of free fatty acid-producing cyanobacteria.

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Motwalli, Olaa; Essack, Magbubah; Jankovic, Boris R; Ji, Boyang; Liu, Xinyao; Ansari, Hifzur Rahman; Hoehndorf, Robert; Gao, Xin; Arold, Stefan T; Mineta, Katsuhiko; Archer, John A C; Gojobori, Takashi; Mijakovic, Ivan; Bajic, Vladimir B

2017-01-05

Finding a source from which high-energy-density biofuels can be derived at an industrial scale has become an urgent challenge for renewable energy production. Some microorganisms can produce free fatty acids (FFA) as precursors towards such high-energy-density biofuels. In particular, photosynthetic cyanobacteria are capable of directly converting carbon dioxide into FFA. However, current engineered strains need several rounds of engineering to reach the level of production of FFA to be commercially viable; thus new chassis strains that require less engineering are needed. Although more than 120 cyanobacterial genomes are sequenced, the natural potential of these strains for FFA production and excretion has not been systematically estimated. Here we present the FFA SC (FFASC), an in silico screening method that evaluates the potential for FFA production and excretion of cyanobacterial strains based on their proteomes. A literature search allowed for the compilation of 64 proteins, most of which influence FFA production and a few of which affect FFA excretion. The proteins are classified into 49 orthologous groups (OGs) that helped create rules used in the scoring/ranking of algorithms developed to estimate the potential for FFA production and excretion of an organism. Among 125 cyanobacterial strains, FFASC identified 20 candidate chassis strains that rank in their FFA producing and excreting potential above the specifically engineered reference strain, Synechococcus sp. PCC 7002. We further show that the top ranked cyanobacterial strains are unicellular and primarily include Prochlorococcus (order Prochlorales) and marine Synechococcus (order Chroococcales) that cluster phylogenetically. Moreover, two principal categories of enzymes were shown to influence FFA production the most: those ensuring precursor availability for the biosynthesis of lipids, and those involved in handling the oxidative stress associated to FFA synthesis. To our knowledge FFASC is the first

In silico screening for candidate chassis strains of free fatty acid-producing cyanobacteria

KAUST Repository

Motwalli, Olaa Amin

2017-01-05

Background Finding a source from which high-energy-density biofuels can be derived at an industrial scale has become an urgent challenge for renewable energy production. Some microorganisms can produce free fatty acids (FFA) as precursors towards such high-energy-density biofuels. In particular, photosynthetic cyanobacteria are capable of directly converting carbon dioxide into FFA. However, current engineered strains need several rounds of engineering to reach the level of production of FFA to be commercially viable; thus new chassis strains that require less engineering are needed. Although more than 120 cyanobacterial genomes are sequenced, the natural potential of these strains for FFA production and excretion has not been systematically estimated. Results Here we present the FFA SC (FFASC), an in silico screening method that evaluates the potential for FFA production and excretion of cyanobacterial strains based on their proteomes. A literature search allowed for the compilation of 64 proteins, most of which influence FFA production and a few of which affect FFA excretion. The proteins are classified into 49 orthologous groups (OGs) that helped create rules used in the scoring/ranking of algorithms developed to estimate the potential for FFA production and excretion of an organism. Among 125 cyanobacterial strains, FFASC identified 20 candidate chassis strains that rank in their FFA producing and excreting potential above the specifically engineered reference strain, Synechococcus sp. PCC 7002. We further show that the top ranked cyanobacterial strains are unicellular and primarily include Prochlorococcus (order Prochlorales) and marine Synechococcus (order Chroococcales) that cluster phylogenetically. Moreover, two principal categories of enzymes were shown to influence FFA production the most: those ensuring precursor availability for the biosynthesis of lipids, and those involved in handling the oxidative stress associated to FFA synthesis. Conclusion To

Supplementary Material for: In silico screening for candidate chassis strains of free fatty acid-producing cyanobacteria

KAUST Repository

Motwalli, Olaa Amin

2017-01-01

Abstract Background Finding a source from which high-energy-density biofuels can be derived at an industrial scale has become an urgent challenge for renewable energy production. Some microorganisms can produce free fatty acids (FFA) as precursors towards such high-energy-density biofuels. In particular, photosynthetic cyanobacteria are capable of directly converting carbon dioxide into FFA. However, current engineered strains need several rounds of engineering to reach the level of production of FFA to be commercially viable; thus new chassis strains that require less engineering are needed. Although more than 120 cyanobacterial genomes are sequenced, the natural potential of these strains for FFA production and excretion has not been systematically estimated. Results Here we present the FFA SC (FFASC), an in silico screening method that evaluates the potential for FFA production and excretion of cyanobacterial strains based on their proteomes. A literature search allowed for the compilation of 64 proteins, most of which influence FFA production and a few of which affect FFA excretion. The proteins are classified into 49 orthologous groups (OGs) that helped create rules used in the scoring/ranking of algorithms developed to estimate the potential for FFA production and excretion of an organism. Among 125 cyanobacterial strains, FFASC identified 20 candidate chassis strains that rank in their FFA producing and excreting potential above the specifically engineered reference strain, Synechococcus sp. PCC 7002. We further show that the top ranked cyanobacterial strains are unicellular and primarily include Prochlorococcus (order Prochlorales) and marine Synechococcus (order Chroococcales) that cluster phylogenetically. Moreover, two principal categories of enzymes were shown to influence FFA production the most: those ensuring precursor availability for the biosynthesis of lipids, and those involved in handling the oxidative stress associated to FFA synthesis

Increasing the Photoautotrophic Growth Rate of Synechocystis sp. PCC 6803 by Identifying the Limitations of Its Cultivation.

Science.gov (United States)

van Alphen, Pascal; Abedini Najafabadi, Hamed; Branco Dos Santos, Filipe; Hellingwerf, Klaas J

2018-03-25

Many conditions have to be optimized in order to be able to grow the cyanobacterium Synechocystis sp. PCC 6803 (Synechocystis) for an extended period of time under physiologically well-defined and constant conditions. It is still poorly understood what limits growth of this organism in batch and continuous cultures in BG-11, the standard medium used to grow Synechocystis. Through a series of batch experiments in flasks and continuous mode experiments in advanced photobioreactors, it is shown that the limiting nutrient during batch cultivation is sulfate, the depletion of which leads to ROS formation and rapid bleaching of pigments after entry into stationary phase. In continuous mode, however, the limiting nutrient is iron. Optimizing these growth conditions resulted in a so far highest growth rate of 0.16 h -1 (4.3 h doubling time), which is significantly higher than the textbook value of 0.09 h -1 (8 h doubling time). An improved medium, BG-11 for prolonged cultivation (BG-11-PC) is introduced, that allows for controlled, extended cultivation of Synechocystis, under well-defined physiological conditions. The data present here have implications for mass-culturing of cyanobacteria. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of culture density on biomass production and light utilization efficiency of Synechocystis sp. PCC 6803.

Science.gov (United States)

Straka, Levi; Rittmann, Bruce E

2018-02-01

The viability of large-scale microalgae cultivation depends on providing optimal growth conditions, for which a key operational parameter is culture density. Using Synechocystis sp. PCC 6803, we conducted a series of fixed-density, steady-state experiments and one batch-growth experiment to investigate the role of culture density on biomass production and light utilization efficiency. In all cases, the fixed-density, steady-state experiments and batch-growth experiment showed good agreement. The highest biomass production rates (260 mg L -1  d -1 ) and efficiency for converting light energy to biomass (0.80 μg (μmol photons) -1 ) occurred together at a culture density near 760 mg L -1 , which approximately corresponded to the lowest culture density where almost all incident light was absorbed. The ratio of OD 680 /OD 735 increased with culture density up to the point of maximum productivity, where it plateaued (at a value of 2.4) for higher culture densities. This change in OD 680 /OD 735 indicates a photoacclimation effect that depended on culture density. Very high culture densities led to a sharp decline in efficiency of biomass production per photons absorbed, likely due to a combination of increased decay relative to growth, metabolic changes due to cell-cell interactions, and photodamage due to mixing between regions with high light intensity and zero light intensity. © 2017 Wiley Periodicals, Inc.

Bioremediation/Biorecovery of uranium from aquatic resource/waste: the Cyano-Deino story

International Nuclear Information System (INIS)

Apte, Shree Kumar

2015-01-01

Terrestrial sources of uranium are getting depleted fast and may be exhausted in the next few decades. This has triggered a search for alternate or secondary resources for this precious metal. Nearly 4.5 billion tons of uranium on our planet resides in seawater, albeit at very low concentrations of 3 ppb. Recovering uranium from such low concentrations is a major challenge. Two marine cyanobacteria, the unicellular Synechococcus elongatus and the filamentous Anabaena torulosa, were found to be capable of rapidly sequestering uranyl carbonate (the predominant uranyl species at the sea-water pH of 7.8) from aqueous solutions, including simulated sea-water. While Synechococcus strain adsorbed the metal as carbonato complexes on cell surface ligands, A. torulosa trapped it in novel surface-associated polyphosphate bodies. The uranium binding potential of cyanobacterial biomass was comparable to, if not better than, the currently in use polyamidoxime resin. The bound uranium could be desorbed easily and the biomass reused a few times. The method has eminently higher application potential in uranium-contaminated terrestrial waters, where the metal concentration is several times higher. Low concentrations (<1 to few mM) of uranium are also found in acidic/alkaline nuclear waste and arise from metal extraction or during reprocessing of fuel. Removal of uranium from such solutions is very desirable for safer disposal of such waste. Biological agents to be employed in such situations also need to be tolerant to and stable in high radiation environments, unless dead cells can be used. To address such bioremediation, the extremely radio-resistant microbe Deinococcus radiodurans was genetically engineered to express either a non-specific acid phosphatase PhoN or a highly active novel alkaline phosphatase PhoK. Apart from the need for high expression of desired protein, such engineering is also fraught with problems of stability, localization and activity of the expressed

Involvement of sulfoquinovosyl diacylglycerol in DNA synthesis in Synechocystis sp. PCC 6803

Directory of Open Access Journals (Sweden)

Aoki Motohide

2012-02-01

Full Text Available Abstract Background Sulfoquinovosyl diacylglycerol (SQDG is present in the membranes of cyanobacteria and their postulated progeny, plastids, in plants. A cyanobacterium, Synechocystis sp. PCC 6803, requires SQDG for growth: its mutant (SD1 with the sqdB gene for SQDG synthesis disrupted can grow with external supplementation of SQDG. However, upon removal of SQDG from the medium, its growth is retarded, with a decrease in the cellular content of SQDG throughout cell division, and finally ceases. Concomitantly with the decrease in SQDG, the maximal activity of photosynthesis at high-light intensity is repressed by 40%. Findings We investigated effects of SQDG-defect on physiological aspects in Synechocystis with the use of SD1. SD1 cells defective in SQDG exhibited normal photosynthesis at low-light intensity as on culturing. Meanwhile, SD1 cells defective in SQDG were impaired in light-activated heterotrophic growth as well as in photoautotrophic growth. Flow cytometric analysis of the photoautotrophically growing cells gave similar cell size histograms for the wild type and SD1 supplemented with SQDG. However, the profile of SD1 defective in SQDG changed such that large part of the cell population was increased in size. Of particular interest was the microscopic observation that the mitotic index, i.e., population of dumbbell-like cells with a septum, increased from 14 to 29% in the SD1 culture without SQDG. Flow cytometric analysis also showed that the enlarged cells of SD1 defective in SQDG contained high levels of Chl, however, the DNA content was low. Conclusions Our experiments strongly support the idea that photosynthesis is not the limiting factor for the growth of SD1 defective in SQDG, and that SQDG is responsible for some physiologically fundamental process common to both photoautotrophic and light-activated heterotrophic growth. Our findings suggest that the SQDG-defect allows construction of the photosynthetic machinery at an

Influence of weather variables and plant communities on grasshopper density in the Southern Pampas, Argentina.

Science.gov (United States)

de Wysiecki, María Laura; Arturi, Marcelo; Torrusio, Sandra; Cigliano, María Marta

2011-01-01

A study was conducted to evaluate the influence of weather (precipitation and temperature) and plant communities on grasshopper density over a 14-year period (1996-2009) in Benito Juárez County, Southern Pampas, Argentina. Total density strongly varied among plant communities. Highest values were registered in 2001 and 2003 in highly disturbed pastures and in 2002 and 2009 in halophilous grasslands. Native grasslands had the lowest density values. Seasonal precipitation and temperature had no significant effect on total grasshopper density. Dichroplus elongatus (Giglio-Tos) (Orthoptera: Acridoidea), Covasacris pallidinota (Bruner), Dichroplus pratensis Bruner, Scotussa lemniscata Stål, Borellia bruneri (Rehn) and Dichroplus maculipennis (Blanchard) comprised, on average, 64% of the grasshopper assemblages during low density years and 79% during high density years. Dichroplus elongatus, S. lemniscata and C. pallidinota were the most abundant species in 2001, 2002 and 2003, while D. elongatus, B. brunneri and C. pallidinota in 2009. Dichroplus elongatus and D. pratensis, mixed feeders species, were positively affected by summer rainfall. This suggests that the increase in summer precipitation had a positive effect on the quantity and quality forage production, affecting these grasshopper populations. Scotussa lemniscata and C. pallidinota were negatively affected by winter and fall temperature, possibly affecting the embryonic development before diapause and hatching. Dichroplus elongatus and D. pratensis were associated with highly disturbed pastures, S. lemniscata with pastures and B. bruneri and D. maculipennis with halophilous grasslands. Covasacris pallidinota was closely associated with halophilous grasslands and moderately disturbed pastures. Weather conditions changed over the years, with 2001, 2002 and 2003 having excessive rainfall while 2008 and 2009 were the driest years since the study started. We suggest that although seasonal precipitation and

Comparison of Optimal Thermodynamic Models of the Tricarboxylic Acid Cycle from Heterotrophs, Cyanobacteria, and Green Sulfur Bacteria

Energy Technology Data Exchange (ETDEWEB)

Thomas, Dennis G.; Jaramillo Riveri, Sebastian I.; Baxter, Douglas J.; Cannon, William R.

2014-12-15

We have applied a new stochastic simulation approach to predict the metabolite levels, energy flow, and material flux in the different oxidative TCA cycles found in E. coli and Synechococcus sp. PCC 7002, and in the reductive TCA cycle typical of chemolithoautotrophs and phototrophic green sulfur bacteria such as Chlorobaculum tepidum. The simulation approach is based on equations of state and employs an assumption similar to that used in transition state theory. The ability to evaluate the thermodynamics of metabolic pathways allows one to understand the relationship between coupling of energy and material gradients in the environment and the selforganization of stable biological systems, and it is shown that each cycle operates in the direction expected due to its environmental niche. The simulations predict changes in metabolite levels and flux in response to changes in cofactor concentrations that would be hard to predict without an elaborate model based on the law of mass action. In fact, we show that a thermodynamically unfavorable reaction can still have flux in the forward direction when it is part of a reaction network. The ability to predict metabolite levels, energy flow and material flux should be significant for understanding the dynamics of natural systems and for understanding principles for engineering organisms for production of specialty chemicals, such as biofuels.

Comparison of Optimal Thermodynamic Models of the Tricarboxylic Acid Cycle from Heterotrophs, Cyanobacteria, and Green Sulfur Bacteria.

Science.gov (United States)

Thomas, Dennis G; Jaramillo-Riveri, Sebastian; Baxter, Douglas J; Cannon, William R

2014-12-26

We have applied a new stochastic simulation approach to predict the metabolite levels, material flux, and thermodynamic profiles of the oxidative TCA cycles found in E. coli and Synechococcus sp. PCC 7002, and in the reductive TCA cycle typical of chemolithoautotrophs and phototrophic green sulfur bacteria such as Chlorobaculum tepidum. The simulation approach is based on modeling states using statistical thermodynamics and employs an assumption similar to that used in transition state theory. The ability to evaluate the thermodynamics of metabolic pathways allows one to understand the relationship between coupling of energy and material gradients in the environment and the self-organization of stable biological systems, and it is shown that each cycle operates in the direction expected due to its environmental niche. The simulations predict changes in metabolite levels and flux in response to changes in cofactor concentrations that would be hard to predict without an elaborate model based on the law of mass action. In fact, we show that a thermodynamically unfavorable reaction can still have flux in the forward direction when it is part of a reaction network. The ability to predict metabolite levels, energy flow, and material flux should be significant for understanding the dynamics of natural systems and for understanding principles for engineering organisms for production of specialty chemicals.

CyanoEXpress: A web database for exploration and visualisation of the integrated transcriptome of cyanobacterium Synechocystis sp. PCC6803.

Science.gov (United States)

Hernandez-Prieto, Miguel A; Futschik, Matthias E

2012-01-01

Synechocystis sp. PCC6803 is one of the best studied cyanobacteria and an important model organism for our understanding of photosynthesis. The early availability of its complete genome sequence initiated numerous transcriptome studies, which have generated a wealth of expression data. Analysis of the accumulated data can be a powerful tool to study transcription in a comprehensive manner and to reveal underlying regulatory mechanisms, as well as to annotate genes whose functions are yet unknown. However, use of divergent microarray platforms, as well as distributed data storage make meta-analyses of Synechocystis expression data highly challenging, especially for researchers with limited bioinformatic expertise and resources. To facilitate utilisation of the accumulated expression data for a wider research community, we have developed CyanoEXpress, a web database for interactive exploration and visualisation of transcriptional response patterns in Synechocystis. CyanoEXpress currently comprises expression data for 3073 genes and 178 environmental and genetic perturbations obtained in 31 independent studies. At present, CyanoEXpress constitutes the most comprehensive collection of expression data available for Synechocystis and can be freely accessed. The database is available for free at http://cyanoexpress.sysbiolab.eu.

Ethylene Regulates the Physiology of the Cyanobacterium Synechocystis sp. PCC 6803 via an Ethylene Receptor.

Science.gov (United States)

Lacey, Randy F; Binder, Brad M

2016-08-01

Ethylene is a plant hormone that plays a crucial role in the growth and development of plants. The ethylene receptors in plants are well studied, and it is generally assumed that they are found only in plants. In a search of sequenced genomes, we found that many bacterial species contain putative ethylene receptors. Plants acquired many proteins from cyanobacteria as a result of the endosymbiotic event that led to chloroplasts. We provide data that the cyanobacterium Synechocystis (Synechocystis sp. PCC 6803) has a functional receptor for ethylene, Synechocystis Ethylene Response1 (SynEtr1). We first show that SynEtr1 directly binds ethylene. Second, we demonstrate that application of ethylene to Synechocystis cells or disruption of the SynEtr1 gene affects several processes, including phototaxis, type IV pilus biosynthesis, photosystem II levels, biofilm formation, and spontaneous cell sedimentation. Our data suggest a model where SynEtr1 inhibits downstream signaling and ethylene inhibits SynEtr1. This is similar to the inverse-agonist model of ethylene receptor signaling proposed for plants and suggests a conservation of structure and function that possibly originated over 1 billion years ago. Prior research showed that SynEtr1 also contains a light-responsive phytochrome-like domain. Thus, SynEtr1 is a bifunctional receptor that mediates responses to both light and ethylene. To our knowledge, this is the first demonstration of a functional ethylene receptor in a nonplant species and suggests that that the perception of ethylene is more widespread than previously thought. © 2016 American Society of Plant Biologists. All Rights Reserved.

Growth of nutrient-replete Microcystis PCC 7806 cultures is inhibited by an extracellular signal produced by chlorotic cultures.

Science.gov (United States)

Dagnino, Denise; de Abreu Meireles, Diogo; de Aquino Almeida, João Carlos

2006-01-01

The frequency of cyanobacterial blooms has been increasing all over the world. These blooms are often toxic and have become a serious health problem. The aim of this work was to search for population density control mechanisms that could inhibit the proliferation of the toxic bloom-forming genus Microcystis. Microcystis PCC 7806 cultured for long periods in liquid ASM-1 medium loses its characteristic green colour. When a medium of chlorotic cultures is added to a nutrient-replete culture, cell density increase is drastically reduced when compared with controls. Inhibition of cell proliferation occurs in Microcystis cultures from any growth stage and was not strain-specific, but other genera tested showed no response. Investigations on the mechanism of growth inhibition showed that cultures treated with the conditioned medium acquired a pale colour, with pigment concentration similar to that found in chlorotic cultures. Ultrastructural examination showed that the conditioned medium induced thylakoid membrane disorganization, typical of chlorotic cells, in nutrient-replete cultures. An active extract was obtained and investigations showed that activity was retained after heating and after addition of an apolar solvent. This indicates that activity of the conditioned medium from chlorotic cells results from non-protein, apolar compound(s).

NCBI nr-aa BLAST: CBRC-AGAM-02-0168 [SEVENS

Lifescience Database Archive (English)

Full Text Available CBRC-AGAM-02-0168 ref|YP_001226076.1| Hydrogenase/urease accessory protein [Synecho...coccus sp. WH 7803] emb|CAK24779.1| Hydrogenase/urease accessory protein [Synechococcus sp. WH 7803] YP_001226076.1 1.0 28% ...

Heterologous expression of Anabaena PCC 7120 all3940 (a Dps family gene) protects Escherichia coli from nutrient limitation and abiotic stresses

International Nuclear Information System (INIS)

Narayan, Om Prakash; Kumari, Nidhi; Rai, Lal Chand

2010-01-01

This study presents first hand data on the cloning and heterologous expression of Anabaena PCC 7120 all3940 (a dps family gene) in combating nutrients limitation and multiple abiotic stresses. The Escherichia coli transformed with pGEX-5X-2-all3940 construct when subjected to iron, carbon, nitrogen, phosphorus limitation and carbofuron, copper, UV-B, heat, salt and cadmium stress registered significant increase in growth over the cells transformed with empty vector under iron (0%), carbon (0.05%), nitrogen (3.7 mM) and phosphorus (2 mM) limitation and carbofuron (0.025 mg ml -1 ), CuCl 2 (1 mM), UV-B (10 min), heat (47 o C), NaCl (6% w/v) and CdCl 2 (4 mM) stress. Enhanced expression of all3940 gene measured by semi-quantitative RT-PCR at different time points under above mentioned treatments clearly demonstrates its role in tolerance against aforesaid abiotic stresses. This study opens the gate for developing transgenic cyanobacteria capable of growing successfully under above mentioned stresses.

Cloning expression and analysis of phytochelatin synthase (pcs) gene from Anabaena sp. PCC 7120 offering multiple stress tolerance in Escherichia coli

International Nuclear Information System (INIS)

Chaurasia, Neha; Mishra, Yogesh; Rai, Lal Chand

2008-01-01

Phytochelatin synthase (PCS) is involved in the synthesis of phytochelatins (PCs), plays role in heavy metal detoxification. The present study describes for first time the functional expression and characterization of pcs gene of Anabaena sp. PCC 7120 in Escherichia coli in terms of offering protection against heat, salt, carbofuron (pesticide), cadmium, copper, and UV-B stress. The involvement of pcs gene in tolerance to above abiotic stresses was investigated by cloning of pcs gene in expression vector pGEX-5X-2 and its transformation in E. coli BL21 (DE3). The E. coli cells transformed with pGEX-5X-pcs showed better growth than control cells (pGEX-5X-2) under temperature (47 deg. C), NaCl (6% w/v), carbofuron (0.025 mg ml -1 ), CdCl 2 (4 mM), CuCl 2 (1 mM), and UV-B (10 min) exposure. The enhanced expression of pcs gene revealed by RT-PCR analysis under above stresses at different time intervals further advocates its role in tolerance against above abiotic stresses

Diversity and transcription of proteases involved in the maturation of hydrogenases in Nostoc punctiforme ATCC 29133 and Nostoc sp. strain PCC 7120

Science.gov (United States)

2009-01-01

Background The last step in the maturation process of the large subunit of [NiFe]-hydrogenases is a proteolytic cleavage of the C-terminal by a hydrogenase specific protease. Contrary to other accessory proteins these hydrogenase proteases are believed to be specific whereby one type of hydrogenases specific protease only cleaves one type of hydrogenase. In cyanobacteria this is achieved by the gene product of either hupW or hoxW, specific for the uptake or the bidirectional hydrogenase respectively. The filamentous cyanobacteria Nostoc punctiforme ATCC 29133 and Nostoc sp strain PCC 7120 may contain a single uptake hydrogenase or both an uptake and a bidirectional hydrogenase respectively. Results In order to examine these proteases in cyanobacteria, transcriptional analyses were performed of hupW in Nostoc punctiforme ATCC 29133 and hupW and hoxW in Nostoc sp. strain PCC 7120. These studies revealed numerous transcriptional start points together with putative binding sites for NtcA (hupW) and LexA (hoxW). In order to investigate the diversity and specificity among hydrogeanse specific proteases we constructed a phylogenetic tree which revealed several subgroups that showed a striking resemblance to the subgroups previously described for [NiFe]-hydrogenases. Additionally the proteases specificity was also addressed by amino acid sequence analysis and protein-protein docking experiments with 3D-models derived from bioinformatic studies. These studies revealed a so called "HOXBOX"; an amino acid sequence specific for protease of Hox-type which might be involved in docking with the large subunit of the hydrogenase. Conclusion Our findings suggest that the hydrogenase specific proteases are under similar regulatory control as the hydrogenases they cleave. The result from the phylogenetic study also indicates that the hydrogenase and the protease have co-evolved since ancient time and suggests that at least one major horizontal gene transfer has occurred. This co

Diversity and transcription of proteases involved in the maturation of hydrogenases in Nostoc punctiforme ATCC 29133 and Nostoc sp. strain PCC 7120

Directory of Open Access Journals (Sweden)

Lindblad Peter

2009-03-01

Full Text Available Abstract Background The last step in the maturation process of the large subunit of [NiFe]-hydrogenases is a proteolytic cleavage of the C-terminal by a hydrogenase specific protease. Contrary to other accessory proteins these hydrogenase proteases are believed to be specific whereby one type of hydrogenases specific protease only cleaves one type of hydrogenase. In cyanobacteria this is achieved by the gene product of either hupW or hoxW, specific for the uptake or the bidirectional hydrogenase respectively. The filamentous cyanobacteria Nostoc punctiforme ATCC 29133 and Nostoc sp strain PCC 7120 may contain a single uptake hydrogenase or both an uptake and a bidirectional hydrogenase respectively. Results In order to examine these proteases in cyanobacteria, transcriptional analyses were performed of hupW in Nostoc punctiforme ATCC 29133 and hupW and hoxW in Nostoc sp. strain PCC 7120. These studies revealed numerous transcriptional start points together with putative binding sites for NtcA (hupW and LexA (hoxW. In order to investigate the diversity and specificity among hydrogeanse specific proteases we constructed a phylogenetic tree which revealed several subgroups that showed a striking resemblance to the subgroups previously described for [NiFe]-hydrogenases. Additionally the proteases specificity was also addressed by amino acid sequence analysis and protein-protein docking experiments with 3D-models derived from bioinformatic studies. These studies revealed a so called "HOXBOX"; an amino acid sequence specific for protease of Hox-type which might be involved in docking with the large subunit of the hydrogenase. Conclusion Our findings suggest that the hydrogenase specific proteases are under similar regulatory control as the hydrogenases they cleave. The result from the phylogenetic study also indicates that the hydrogenase and the protease have co-evolved since ancient time and suggests that at least one major horizontal gene transfer

Active prey selection in two pelagic copepods feeding on potentially toxic and non-toxic dinoflagellates

DEFF Research Database (Denmark)

Schultz, Mette; Kiørboe, Thomas

2009-01-01

Grazing on two red tide dinoflagellates, the potentially toxic Karenia mikimotoi and the non-toxic Gyrodinium instriatum, was examined in two species of marine copepods, Pseudocalanus elongatus and Temora longicornis. Both copepods cleared K. mikimotoi at rates that were a little lower but compar......Grazing on two red tide dinoflagellates, the potentially toxic Karenia mikimotoi and the non-toxic Gyrodinium instriatum, was examined in two species of marine copepods, Pseudocalanus elongatus and Temora longicornis. Both copepods cleared K. mikimotoi at rates that were a little lower...

Adsorption of lignocelluloses of pre-hydrolysis liquor on calcium carbonate to induce functional filler.

Science.gov (United States)

Fatehi, Pedram; Hamdan, Fadia C; Ni, Yonghao

2013-04-15

In this work, we aimed at adsorbing the oligo-sugars of prehydrolysis liquor on precipitated calcium carbonate (PCC) to produce modified PCC. The results showed that the adsorptions of oligo-sugars, lignin and furfural were greater on porous PCC (PCC2) than on nano-sized PCC (PCC1) due to the larger surface area of PCC2. The adsorption reached its maximum in 5 h on PCC1, but it gradually increased on PCC2 due to the diffusion of oligo-sugars and lignin into the pores of PCC2. Also, the experimental isotherm and kinetic results were well fitted into Langmuir and pseudo-second order models, respectively. The adsorption was greater at a lower temperature (i.e. 40°C) and pH (i.e. 7). Alternatively, cationic poly acrylamide (CPAM) was added to the PHL/PCC system, which led to more promising results (than that to PHL/PCC system) with the maximum lignocelluloses adsorption of 0.36 g/g on PCC2, among which 0.22 g/g was oligo-sugars. Copyright © 2013 Elsevier Ltd. All rights reserved.

New Insight into the Cleavage Reaction of Nostoc sp. Strain PCC 7120 Carotenoid Cleavage Dioxygenase in Natural and Nonnatural Carotenoids

Science.gov (United States)

Heo, Jinsol; Kim, Se Hyeuk

2013-01-01

Carotenoid cleavage dioxygenases (CCDs) are enzymes that catalyze the oxidative cleavage of carotenoids at a specific double bond to generate apocarotenoids. In this study, we investigated the activity and substrate preferences of NSC3, a CCD of Nostoc sp. strain PCC 7120, in vivo and in vitro using natural and nonnatural carotenoid structures. NSC3 cleaved β-apo-8′-carotenal at 3 positions, C-13C-14, C-15C-15′, and C-13′C-14′, revealing a unique cleavage pattern. NSC3 cleaves the natural structure of carotenoids 4,4′-diaponeurosporene, 4,4′-diaponeurosporen-4′-al, 4,4′-diaponeurosporen-4′-oic acid, 4,4′-diapotorulene, and 4,4′-diapotorulen-4′-al to generate novel cleavage products (apo-14′-diaponeurosporenal, apo-13′-diaponeurosporenal, apo-10′-diaponeurosporenal, apo-14′-diapotorulenal, and apo-10′-diapotorulenal, respectively). The study of carotenoids with natural or nonnatural structures produced by using synthetic modules could provide information valuable for understanding the cleavage reactions or substrate preferences of other CCDs in vivo and in vitro. PMID:23524669

Gene expression patterns of sulfur starvation in Synechocystis sp. PCC 6803

Directory of Open Access Journals (Sweden)

Pendse Ninad D

2008-07-01

Full Text Available Abstract Background The unicellular cyanobacterium Synechocystis sp. PCC 6803 is a model microbe for studying biochemistry, genetics and molecular biology of photobiological processes. Importance of this bacterium in basic and applied research calls for a systematic, genome-wide description of its transcriptional regulatory capacity. Characteristic transcriptional responses to changes in the growth environment are expected to provide a scaffold for describing the Synechocystis transcriptional regulatory network as well as efficient means for functional annotation of genes in the genome. Results We designed, validated and used Synechocystis genome-wide oligonucleotide (70-mer microarray (representing 96.7% of all chromosomal ORFs annotated at the time of the beginning of this project to study transcriptional activity of the cyanobacterial genome in response to sulfur (S starvation. The microarray data were verified by quantitative RT-PCR. We made five main observations: 1 Transcriptional changes upon sulfate starvation were relatively moderate, but significant and consistent with growth kinetics; 2 S acquisition genes encoding for a high-affinity sulfate transporter were significantly induced, while decreased transcription of genes for phycobilisome, photosystems I and II, cytochrome b6/f, and ATP synthase indicated reduced light-harvesting and photosynthetic activity; 3 S starvation elicited transcriptional responses associated with general growth arrest and stress; 4 A large number of genes regulated by S availability encode hypothetical proteins or proteins of unknown function; 5 Hydrogenase structural and maturation accessory genes were not identified as differentially expressed, even though increased hydrogen evolution was observed. Conclusion The expression profiles recorded by using this oligonucleotide-based microarray platform revealed that during transition from the condition of plentiful S to S starvation, Synechocystis undergoes

Comparison of orthologous cyanobacterial aldehyde deformylating oxygenases in the production of volatile C3-C7 alkanes in engineered E. coli

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Pekka Patrikainen

2017-12-01

Full Text Available Aldehyde deformylating oxygenase (ADO is a unique enzyme found exclusively in photosynthetic cyanobacteria, which natively converts acyl aldehyde precursors into hydrocarbon products embedded in cellular lipid bilayers. This capacity has opened doors for potential biotechnological applications aiming at biological production of diesel-range alkanes and alkenes, which are compatible with the nonrenewable petroleum-derived end-products in current use. The development of production platforms, however, has been limited by the relative inefficiency of ADO enzyme, promoting research towards finding new strategies and information to be used for rational design of enhanced pathways for hydrocarbon over-expression. In this work we present an optimized approach to study different ADO orthologs derived from different cyanobacterial species in an in vivo set-up in Escherichia coli. The system enabled comparison of alternative ADOs for the production efficiency of short-chain volatile C3-C7 alkanes, propane, pentane and heptane, and provided insight on the differences in substrate preference, catalytic efficiency and limitations associated with the enzymes. The work concentrated on five ADO orthologs which represent the most extensively studied cyanobacterial species in the field, and revealed distinct differences between the enzymes. In most cases the ADO from Nostoc punctiforme PCC 73102 performed the best in respect to yields and initial rates for the production of the volatile hydrocarbons. At the other extreme, the system harboring the ADO form Synechococcus sp. RS9917 produced very low amounts of the short-chain alkanes, primarily due to poor accumulation of the enzyme in E. coli. The ADOs from Synechocystis sp. PCC 6803 and Prochlorococcus marinus MIT9313, and the corresponding variant A134F displayed less divergence, although variation between chain-length preferences could be observed. The results confirmed the general trend of ADOs having

Can environmental conditions trigger cyanobacterial surfaces and following carbonate formation: implication for biomineralization and biotechnology

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Paulo, C.; Dittrich, M.; Zhu, T.

2015-12-01

In this presentation we will give an overview what kind of the factors may trigger carbonate formations at the cell surfaces under a variety of environmental conditions. As examples, we will present the results from our recent studies on formation of calcium carbonates, dolomites and bio-cements. The extracellular polymeric substances (EPS) in the Synechococcuscell envelope are recognized key players in the nucleation of carbonates in marine and freshwater environments. Yet, little is known about a nutrient contents control over the molecular composition of Synechococcus cell envelope, and consequently, biomineralization. In the first study, we investigated how a variation of the phosphorus (P) in the growth media can lead to changes in the surface reactivity of the cells and impact their ability to form carbonates. The objective of the second study is to gain insights into the spatial distribution of cyanobacterial EPS and dolomite from different sediment layers of Khor Al-Adaid sabkha (Qatar). Here, we characterized microbial mats on molecular level in respect of organic and inorganic components using in-situ 2D Raman spectroscopy and Atomic Force Microscopy (AFM) were used. Additionally, 2D chemical maps of sediment layers documented spectral characterizations of minerals and organic matter of microbial origins at high spatial resolution. Finally, we will show the results from the experiments with auto-phototrophic cyanobacteria Gloeocapsa PCC73106, which habitat on the monument surfaces, towards its application for bio-concrete, a product of microbial carbonate precipitation. We studied the biomineralization in biofilm forming Gloeocapsa PCC73106 on the concrete surface as a pre-requirement for microbial carbonate precipitation. Biomineralization on the concrete surface by live cells and killed cells were compared with that under the abiotic condition. Our experiments allow us to conclude that environmental conditions play a significant role in the control of

NblA1/A2-Dependent Homeostasis of Amino Acid Pools during Nitrogen Starvation in Synechocystis sp. PCC 6803.

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Kiyota, Hiroshi; Hirai, Masami Yokota; Ikeuchi, Masahiko

2014-06-30

Nutrient balance is important for photosynthetic growth and biomass production in microalgae. Here, we investigated and compared metabolic responses of amino acid pools to nitrogen and sulfur starvation in a unicellular model cyanobacterium, Synechocystis sp. PCC 6803, and its mutant nblA1/A2. It is known that NblA1/A2-dependent and -independent breakdown of abundant photosynthetic phycobiliproteins and other cellular proteins supply nutrients to the organism. However, the contribution of the NblA1/A2-dependent nutrient supply to amino acid pool homeostasis has not been studied. Our study demonstrates that changes in the pool size of many amino acids during nitrogen starvation can be categorized as NblA1/A2-dependent (Gln, Glu, glutathione, Gly, Ile, Leu, Met, Phe, Pro, Ser, Thr, Tyr and Val) and NblA1/A2-independent (Ala, Asn, Lys, and Trp). We also report unique changes in amino acid pool sizes during sulfur starvation in wild type and the mutant and found a generally marked increase in the Lys pool in cyanobacteria during nutrient starvation. In conclusion, the NblA1/A2-dependent protein turnover contributes to the maintenance of many amino acid pools during nitrogen starvation.

NblA1/A2-Dependent Homeostasis of Amino Acid Pools during Nitrogen Starvation in Synechocystis sp. PCC 6803

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Hiroshi Kiyota

2014-06-01

Full Text Available Nutrient balance is important for photosynthetic growth and biomass production in microalgae. Here, we investigated and compared metabolic responses of amino acid pools to nitrogen and sulfur starvation in a unicellular model cyanobacterium, Synechocystis sp. PCC 6803, and its mutant nblA1/A2. It is known that NblA1/A2-dependent and -independent breakdown of abundant photosynthetic phycobiliproteins and other cellular proteins supply nutrients to the organism. However, the contribution of the NblA1/A2-dependent nutrient supply to amino acid pool homeostasis has not been studied. Our study demonstrates that changes in the pool size of many amino acids during nitrogen starvation can be categorized as NblA1/A2-dependent (Gln, Glu, glutathione, Gly, Ile, Leu, Met, Phe, Pro, Ser, Thr, Tyr and Val and NblA1/A2-independent (Ala, Asn, Lys, and Trp. We also report unique changes in amino acid pool sizes during sulfur starvation in wild type and the mutant and found a generally marked increase in the Lys pool in cyanobacteria during nutrient starvation. In conclusion, the NblA1/A2-dependent protein turnover contributes to the maintenance of many amino acid pools during nitrogen starvation.

Amino Acid Transporters and Release of Hydrophobic Amino Acids in the Heterocyst-Forming Cyanobacterium Anabaena sp. Strain PCC 7120

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Rafael Pernil

2015-04-01

Full Text Available Anabaena sp. strain PCC 7120 is a filamentous cyanobacterium that can use inorganic compounds such as nitrate or ammonium as nitrogen sources. In the absence of combined nitrogen, it can fix N2 in differentiated cells called heterocysts. Anabaena also shows substantial activities of amino acid uptake, and three ABC-type transporters for amino acids have been previously characterized. Seven new loci encoding predicted amino acid transporters were identified in the Anabaena genomic sequence and inactivated. Two of them were involved in amino acid uptake. Locus alr2535-alr2541 encodes the elements of a hydrophobic amino acid ABC-type transporter that is mainly involved in the uptake of glycine. ORF all0342 encodes a putative transporter from the dicarboxylate/amino acid:cation symporter (DAACS family whose inactivation resulted in an increased uptake of a broad range of amino acids. An assay to study amino acid release from Anabaena filaments to the external medium was set up. Net release of the alanine analogue α-aminoisobutyric acid (AIB was observed when transport system N-I (a hydrophobic amino acid ABC-type transporter was engaged in the uptake of a specific substrate. The rate of AIB release was directly proportional to the intracellular AIB concentration, suggesting leakage from the cells by diffusion.

Metabolic engineering of the pentose phosphate pathway for enhanced limonene production in the cyanobacterium Synechocysti s sp. PCC 6803.

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Lin, Po-Cheng; Saha, Rajib; Zhang, Fuzhong; Pakrasi, Himadri B

2017-12-13

Isoprenoids are diverse natural compounds, which have various applications as pharmaceuticals, fragrances, and solvents. The low yield of isoprenoids in plants makes them difficult for cost-effective production, and chemical synthesis of complex isoprenoids is impractical. Microbial production of isoprenoids has been considered as a promising approach to increase the yield. In this study, we engineered the model cyanobacterium Synechocystis sp. PCC 6803 for sustainable production of a commercially valuable isoprenoid, limonene. Limonene synthases from the plants Mentha spicata and Citrus limon were expressed in cyanobacteria for limonene production. Production of limonene was two-fold higher with limonene synthase from M. spicata than that from C. limon. To enhance isoprenoid production, computational strain design was conducted by applying the OptForce strain design algorithm on Synechocystis 6803. Based on the metabolic interventions suggested by this algorithm, genes (ribose 5-phosphate isomerase and ribulose 5-phosphate 3-epimerase) in the pentose phosphate pathway were overexpressed, and a geranyl diphosphate synthase from the plant Abies grandis was expressed to optimize the limonene biosynthetic pathway. The optimized strain produced 6.7 mg/L of limonene, a 2.3-fold improvement in productivity. Thus, this study presents a feasible strategy to engineer cyanobacteria for photosynthetic production of isoprenoids.

Identification of a transporter Slr0982 involved in ethanol tolerance in cyanobacterium Synechocystis sp. PCC 6803

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Yanan eZhang

2015-05-01

Full Text Available Cyanobacteria have been engineered to produce ethanol through recent synthetic biology efforts. However, one major challenge to the cyanobacterial systems for high-efficiency ethanol production is their low tolerance to the ethanol toxicity. With a major goal to identify novel transporters involved in ethanol tolerance, we constructed gene knockout mutants for 58 transporter-encoding genes of Synechocystis sp. PCC 6803 and screened their tolerance change under ethanol stress. The efforts allowed discovery of a mutant of slr0982 gene encoding an ATP-binding cassette transporter which grew poorly in BG11 medium supplemented with 1.5% (v/v ethanol when compared with the wild type, and the growth loss could be recovered by complementing slr0982 in the ∆slr0982 mutant, suggesting that slr0982 is involved in ethanol tolerance in Synechocystis. To decipher the tolerance mechanism involved, a comparative metabolomic and network-based analysis of the wild type and the ethanol-sensitive ∆slr0982 mutant was performed. The analysis allowed the identification of four metabolic modules related to slr0982 deletion in the ∆slr0982 mutant, among which metabolites like sucrose and L-pyroglutamic acid which might be involved in ethanol tolerance, were found important for slr0982 deletion in the ∆slr0982 mutant. This study reports on the first transporter related to ethanol tolerance in Synechocystis, which could be a useful target for further tolerance engineering. In addition, metabolomic and network analysis provides important findings for better understanding of the tolerance mechanism to ethanol stress in Synechocystis.

Effects of non-steroidal anti-inflammatory drugs on cyanobacteria and algae in laboratory strains and in natural algal assemblages.

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Bácsi, István; B-Béres, Viktória; Kókai, Zsuzsanna; Gonda, Sándor; Novák, Zoltán; Nagy, Sándor Alex; Vasas, Gábor

2016-05-01

In recent years measurable concentrations of non-steroidal anti-inflammatory drugs (NSAIDs) have been shown in the aquatic environment as a result of increasing human consumption. Effects of five frequently used non-steroidal anti-inflammatory drugs (diclofenac, diflunisal, ibuprofen, mefenamic acid and piroxicam in 0.1 mg ml(-1) concentration) in batch cultures of cyanobacteria (Synechococcus elongatus, Microcystis aeruginosa, Cylindrospermopsis raciborskii), and eukaryotic algae (Desmodesmus communis, Haematococcus pluvialis, Cryptomonas ovata) were studied. Furthermore, the effects of the same concentrations of NSAIDs were investigated in natural algal assemblages in microcosms. According to the changes of chlorophyll-a content, unicellular cyanobacteria seemed to be more tolerant to NSAIDs than eukaryotic algae in laboratory experiments. Growth of eukaryotic algae was reduced by all drugs, the cryptomonad C. ovata was the most sensitive to NSAIDs, while the flagellated green alga H. pluvialis was more sensitive than the non-motile green alga D. communis. NSAID treatments had weaker impact in the natural assemblages dominated by cyanobacteria than in the ones dominated by eukaryotic algae, confirming the results of laboratory experiments. Diversity and number of functional groups did not change notably in cyanobacteria dominated assemblages, while they decreased significantly in eukaryotic algae dominated ones compared to controls. The results highlight that cyanobacteria (especially unicellular ones) are less sensitive to the studied, mostly hardly degradable NSAIDs, which suggest that their accumulation in water bodies may contribute to the expansion of cyanobacterial mass productions in appropriate environmental circumstances by pushing back eukaryotic algae. Thus, these contaminants require special attention during wastewater treatment and monitoring of surface waters. Copyright © 2016 Elsevier Ltd. All rights reserved.

CopM is a novel copper-binding protein involved in copper resistance in Synechocystis sp. PCC 6803

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Giner-Lamia, Joaquín; López-Maury, Luis; Florencio, Francisco J

2015-01-01

Copper resistance system in the cyanobacterium Synechocystis sp. PCC 6803 comprises two operons, copMRS and copBAC, which are expressed in response to copper in the media. copBAC codes for a heavy-metal efflux–resistance nodulation and division (HME-RND) system, while copMRS codes for a protein of unknown function, CopM, and a two-component system CopRS, which controls the expression of these two operons. Here, we report that CopM is a periplasmic protein able to bind Cu(I) with high affinity (KD ∼3 × 10−16). Mutants lacking copM showed a sensitive copper phenotype similar to mutants affected in copB, but lower than mutants of the two-component system CopRS, suggesting that CopBAC and CopM constitute two independent resistance mechanisms. Moreover, constitutive expression of copM is able to partially suppress the copper sensitivity of the copR mutant strain, pointing out that CopM per se is able to confer copper resistance. Furthermore, constitutive expression of copM was able to reduce total cellular copper content of the copR mutant to the levels determined in the wild-type (WT) strain. Finally, CopM was localized not only in the periplasm but also in the extracellular space, suggesting that CopM can also prevent copper accumulation probably by direct copper binding outside the cell. PMID:25545960

Photoautotrophic Polyhydroxybutyrate Granule Formation Is Regulated by Cyanobacterial Phasin PhaP in Synechocystis sp. Strain PCC 6803

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Hauf, Waldemar; Watzer, Björn; Roos, Nora; Klotz, Alexander

2015-01-01

Cyanobacteria are photoautotrophic microorganisms which fix atmospheric carbon dioxide via the Calvin-Benson cycle to produce carbon backbones for primary metabolism. Fixed carbon can also be stored as intracellular glycogen, and in some cyanobacterial species like Synechocystis sp. strain PCC 6803, polyhydroxybutyrate (PHB) accumulates when major nutrients like phosphorus or nitrogen are absent. So far only three enzymes which participate in PHB metabolism have been identified in this organism, namely, PhaA, PhaB, and the heterodimeric PHB synthase PhaEC. In this work, we describe the cyanobacterial PHA surface-coating protein (phasin), which we term PhaP, encoded by ssl2501. Translational fusion of Ssl2501 with enhanced green fluorescent protein (eGFP) showed a clear colocalization to PHB granules. A deletion of ssl2501 reduced the number of PHB granules per cell, whereas the mean PHB granule size increased as expected for a typical phasin. Although deletion of ssl2501 had almost no effect on the amount of PHB, the biosynthetic activity of PHB synthase was negatively affected. Secondary-structure prediction and circular dichroism (CD) spectroscopy of PhaP revealed that the protein consists of two α-helices, both of them associating with PHB granules. Purified PhaP forms oligomeric structures in solution, and both α-helices of PhaP contribute to oligomerization. Together, these results support the idea that Ssl2501 encodes a cyanobacterial phasin, PhaP, which regulates the surface-to-volume ratio of PHB granules. PMID:25911471

Potential of Microalgae Cultivation in Dairy Wastewater as a Step in Low-Cost Biofuel Production

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Basma Abbas Abdulmajeed

2018-04-01

Full Text Available The present study addresses adopting the organic and nutritious materials in dairy wastewater as media for cultivation of microalgae, which represent an important source of renewable energy. This study was carried out through cultivation of three types of microalgae; Chlorella sp., Synechococcus, and Anabaena. The results shows the success the cultivation of the Synechococcus and Chlorella Sp, while the Anabaena microalgae were in low-growth level. The highest growth was in the Synechococcus farm, followed by Chlorella and Anabaena. However, the growth of Synechococcus required 10 days to achieve this increase that represents a negative indicator of the adoption of this type of microalgae in this media to meet the desired aims. While Chlorella needs less than two days to start growing. Moreover, the data obtained from the experiment show that removal of chemical oxygen demand in Chlorella cultures was (72% more than that obtained from cultivation of other microalgae. Thus this microalgae is more efficient in wastewater treatment than other types.

Three- versus four-factor prothrombin complex concentrate for the reversal of warfarin-induced bleeding

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Holt, Tara; Taylor, Scott; Abraham, Prasad; Mcmillian, Wesley; Harris, Serena; Curtis, James; Elder, Tai

2018-01-01

Objective: The objective of this study was to evaluate the effectiveness of 3-factor prothrombin complex concentrate (3F-PCC) compared to 4-factor PCC (4F-PCC) in warfarin-associated bleeding. Methods: This multicenter, retrospective, cohort study analyzed data from patients admitted between May 2011 and October 2014 who received PCC for warfarin-associated bleeding. The primary outcome was the rate of international normalized ratio (INR) normalization, defined as an INR ≤1.3, after administration of 3F-PCC compared to 4F-PCC. Other variables of interest included the incidence of additional reversal agents, new thromboembolic events, and mortality. Results: A total of 134 patients were included in the analysis. The average dose of PCC administered was 24.6 ± 9.3 units/kg versus 36.3 ± 12.8 units/kg in the 3F-PCC and 4F-PCC groups, respectively, P < 0.001. Baseline INR in the 3F-PCC and 4F-PCC groups was 3.61 ± 2.3 and 6.87 ± 2.3, respectively P < 0.001. 4F-PCC had a higher rate of INR normalization at first INR check post-PCC administration compared to 3F-PCC (84.2% vs. 51.9%, P = 0.0001). Thromboembolic events, intensive care unit and hospital length of stay, and mortality were similar among both groups. Conclusion: The use of 4F-PCC leads to a more significant reduction in INR compared to 3F-PCC though no difference in mortality or length of stay was observed. Thromboembolism rates were similar among both groups. PMID:29619338

The molecular dimension of microbial species: 3. Comparative genomics of Synechococcus strains with different light responses and in situ diel transcription patterns of associated ecotypes in the Mushroom Spring microbial mat

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Millie T. Olsen

2015-06-01

Full Text Available Genomes were obtained for three closely related strains of Synechococcus that are representative of putative ecotypes that predominate at different depths in the 1 mm-thick, upper-green layer in the 60°C mat of Mushroom Spring, Yellowstone National Park, and exhibit different light adaptation and acclimation responses. The genomes were compared to the published genome of a previously obtained, closely related strain from a neighboring spring, and differences in both gene content and orthologous gene alleles between high-light-adapted and low-light-adapted strains were identified. Evidence of genetic differences that relate to adaptation to light intensity and/or quality, CO2 uptake, nitrogen metabolism, organic carbon metabolism, and uptake of other nutrients were found between strains of the different putative ecotypes. In situ diel transcription patterns of genes, including genes unique to either low-light-adapted or high-light-adapted strains and different alleles of an orthologous photosystem gene, revealed that expression is fine-tuned to the different light environments experienced by ecotypes prevalent at various depths in the mat. This study suggests that strains of closely related putative ecotypes have different genomic adaptations that enable them to inhabit distinct ecological niches while living in close proximity within a microbial community.

Distinguishing the Roles of Thylakoid Respiratory Terminal Oxidases in the Cyanobacterium Synechocystis sp. PCC 6803.

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Ermakova, Maria; Huokko, Tuomas; Richaud, Pierre; Bersanini, Luca; Howe, Christopher J; Lea-Smith, David J; Peltier, Gilles; Allahverdiyeva, Yagut

2016-06-01

Various oxygen-utilizing electron sinks, including the soluble flavodiiron proteins (Flv1/3), and the membrane-localized respiratory terminal oxidases (RTOs), cytochrome c oxidase (Cox) and cytochrome bd quinol oxidase (Cyd), are present in the photosynthetic electron transfer chain of Synechocystis sp. PCC 6803. However, the role of individual RTOs and their relative importance compared with other electron sinks are poorly understood, particularly under light. Via membrane inlet mass spectrometry gas exchange, chlorophyll a fluorescence, P700 analysis, and inhibitor treatment of the wild type and various mutants deficient in RTOs, Flv1/3, and photosystem I, we investigated the contribution of these complexes to the alleviation of excess electrons in the photosynthetic chain. To our knowledge, for the first time, we demonstrated the activity of Cyd in oxygen uptake under light, although it was detected only upon inhibition of electron transfer at the cytochrome b6f site and in ∆flv1/3 under fluctuating light conditions, where linear electron transfer was drastically inhibited due to impaired photosystem I activity. Cox is mostly responsible for dark respiration and competes with P700 for electrons under high light. Only the ∆cox/cyd double mutant, but not single mutants, demonstrated a highly reduced plastoquinone pool in darkness and impaired gross oxygen evolution under light, indicating that thylakoid-based RTOs are able to compensate partially for each other. Thus, both electron sinks contribute to the alleviation of excess electrons under illumination: RTOs continue to function under light, operating on slower time ranges and on a limited scale, whereas Flv1/3 responds rapidly as a light-induced component and has greater capacity. © 2016 American Society of Plant Biologists. All Rights Reserved.

An assessment of the usefulness of the cyanobacterium Synechococcus subsalsus as a source of biomass for biofuel production

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Bruno R.S. Setta

2014-05-01

Full Text Available Nowadays algal biofuels are considered one of the most promising solutions of global energy crisis and climate change for the years to come. By manipulation of the culture conditions, many algal species can be induced to accumulate high concentrations of particular biomolecules and can be directed to the desired output for each fuel. In this context, the present study involved the assessment of the effects of CO2 availability and nitrogen starvation on growth and chemical composition of the cyanobacterium Synechococcus subsalsus, testing a fast-growing native strain. The control experiments were performed with Conway culture medium in 12-day batch cultures, in 6-liter flasks and 12 h photoperiod, with addition of 2 L min-1 filtered air to each flask. Other two experimental conditions were also tested: (i the placement into the cultures of additional dissolved nutrients except nitrogen, one week after the start of growth (N-, and (ii the input of pure CO2 into the flasks from the 5th day of growth (C+. In all cultures, daily cell counts were done throughout the cultivation, as well as measurements of pH and cell biovolumes. Maximum cell yield were found in N-experiments, while cell yields of C+ and control were similar. Dissolved nitrogen was exhausted before the end of the experiments, but dissolved phosphorus was not totally consumed. Protein and chlorophyll-a concentrations decreased from the exponential to the stationary growth phase of all experiments, except for protein in the control. In all experiments, carbohydrate, lipid and total carotenoid increased from the exponential to the stationary growth phase, as an effect of nitrogen limitation. Increments in carbohydrate concentrations were remarkable, achieving more than 42% of the dry weight (dw, but concentrations of lipid were always lower than 13% dw. The addition of pure CO2 did not cause a significant increase in biomass of S. subsalsus nor generated more lipid and carbohydrate than

[Increasing reductant NADPH content via metabolic engineering of PHB synthesis pathway in Synechocystis sp. PCC 6803].

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Xie, Juan; Zhou, Jie; Zhang, Haifeng; Li, Yin

2011-07-01

Cyanobacteria have become attractive hosts for renewable chemicals production. The low productivity, however, prevents it from industrial application. Reductant NAD(P)H availability is a chief hurdle for the production of reductive metabolites in microbes. To increase NADPH content in Synechocystis sp. PCC 6803, PHB synthase encoding gene phaC and phaE in Synechocystis was inactivated by replacing phaC&E genes with chloromycetin resistance cassette via homologous recombination. PCR analysis showed that mutant S.delta phaC&E with complete genome segregation was generated. The comparison between growth curves of S.wt and S.delta phaC&E indicated the knockout of phaC & phaE genes did not affect obviously the cell growth. Gas chromatography analysis showed that the accumulation of PHB in wild type was about 2.3% of the dry cell weight, whereas no PHB was detected in the mutant S.delta phaC&E. The data indicated that inactivation of PHB synthase gene phaC and phaE interrupted the synthesis of PHB. Further comparative study of wild type and mutant demonstrated that NADPH content in S.delta phaC&E was obviously increased. On the third day, the NADPH content in S.delta phaC&E was up to 1.85 fold higher than that in wild type. These results indicated that deleting PHB synthase gene phaC and phaE not only can block the synthesis of PHB, but also can save NADPH to contribute reductant sink in cyanobacteria. Hence, the engineered cyanobacterial strain S.delta phaC&E, in which carbon flux was redirected and NADPH was increased, will be a potential host strain for chemicals production in cyanobacteria.

Lipid and carotenoid cooperation-driven adaptation to light and temperature stress in Synechocystis sp. PCC6803.

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Zakar, Tomas; Herman, Eva; Vajravel, Sindhujaa; Kovacs, Laszlo; Knoppová, Jana; Komenda, Josef; Domonkos, Ildiko; Kis, Mihaly; Gombos, Zoltan; Laczko-Dobos, Hajnalka

2017-05-01

Polyunsaturated lipids are important components of photosynthetic membranes. Xanthophylls are the main photoprotective agents, can assist in protection against light stress, and are crucial in the recovery from photoinhibition. We generated the xanthophyll- and polyunsaturated lipid-deficient ROAD mutant of Synechocystis sp. PCC6803 (Synechocystis) in order to study the little-known cooperative effects of lipids and carotenoids (Cars). Electron microscopic investigations confirmed that in the absence of xanthophylls the S-layer of the cellular envelope is missing. In wild-type (WT) cells, as well as the xanthophyll-less (RO), polyunsaturated lipid-less (AD), and the newly constructed ROAD mutants the lipid and Car compositions were determined by MS and HPLC, respectively. We found that, relative to the WT, the lipid composition of the mutants was remodeled and the Car content changed accordingly. In the mutants the ratio of non-bilayer-forming (NBL) to bilayer-forming (BL) lipids was found considerably lower. Xanthophyll to β-carotene ratio increased in the AD mutant. In vitro and in vivo methods demonstrated that saturated, monounsaturated lipids and xanthophylls may stabilize the trimerization of Photosystem I (PSI). Fluorescence induction and oxygen-evolving activity measurements revealed increased light sensitivity of RO cells compared to those of the WT. ROAD showed a robust increase in light susceptibility and reduced recovery capability, especially at moderate low (ML) and moderate high (MH) temperatures, indicating a cooperative effect of xanthophylls and polyunsaturated lipids. We suggest that both lipid unsaturation and xanthophylls are required for providing the proper structure and functioning of the membrane environment that protects against light and temperature stress. Copyright © 2017 Elsevier B.V. All rights reserved.

Ethylene Regulates the Physiology of the Cyanobacterium Synechocystis sp. PCC 6803 via an Ethylene Receptor1[OPEN

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2016-01-01

Ethylene is a plant hormone that plays a crucial role in the growth and development of plants. The ethylene receptors in plants are well studied, and it is generally assumed that they are found only in plants. In a search of sequenced genomes, we found that many bacterial species contain putative ethylene receptors. Plants acquired many proteins from cyanobacteria as a result of the endosymbiotic event that led to chloroplasts. We provide data that the cyanobacterium Synechocystis (Synechocystis sp. PCC 6803) has a functional receptor for ethylene, Synechocystis Ethylene Response1 (SynEtr1). We first show that SynEtr1 directly binds ethylene. Second, we demonstrate that application of ethylene to Synechocystis cells or disruption of the SynEtr1 gene affects several processes, including phototaxis, type IV pilus biosynthesis, photosystem II levels, biofilm formation, and spontaneous cell sedimentation. Our data suggest a model where SynEtr1 inhibits downstream signaling and ethylene inhibits SynEtr1. This is similar to the inverse-agonist model of ethylene receptor signaling proposed for plants and suggests a conservation of structure and function that possibly originated over 1 billion years ago. Prior research showed that SynEtr1 also contains a light-responsive phytochrome-like domain. Thus, SynEtr1 is a bifunctional receptor that mediates responses to both light and ethylene. To our knowledge, this is the first demonstration of a functional ethylene receptor in a nonplant species and suggests that that the perception of ethylene is more widespread than previously thought. PMID:27246094

Specific role of the cyanobacterial PipX factor in the heterocysts of Anabaena sp. strain PCC 7120.

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Valladares, Ana; Rodríguez, Virginia; Camargo, Sergio; Martínez-Noël, Giselle M A; Herrero, Antonia; Luque, Ignacio

2011-03-01

The PipX factor is a regulatory protein that seems to occur only in cyanobacteria. In the filamentous, heterocyst-forming Anabaena sp. strain PCC 7120, open reading frame (ORF) asr0485, identified as the pipX gene, is expressed mainly under conditions of combined-nitrogen deprivation dependent on the global N regulator NtcA and the heterocyst-specific regulator HetR. Primer extension and 5' rapid amplification of cDNA ends (RACE) analyses detected three transcription start points corresponding to a canonical NtcA-activated promoter (to which direct binding of NtcA was observed), an NtcA- and HetR-dependent promoter, and a consensus-type promoter, the last with putative -35 and -10 determinants. Activation of pipX took place in cells differentiating into heterocysts at intermediate to late stages of the process. Accordingly, disruption of pipX led to impaired diazotrophic growth, reduced nitrogenase activity, and impaired activation of the nitrogenase structural genes. The nitrogenase activity of the mutant was low under oxic conditions, likely resulting from inefficient protection against oxygen. In line with this, the activation of the coxB2A2C2 and coxB3A3C3 operons, encoding heterocyst-specific terminal respiratory oxidases responsible for internal oxygen removal, was deficient in the pipX mutant. Therefore, the Anabaena PipX factor shows a spatiotemporal specificity contributing to normal heterocyst function, including full activation of the nitrogenase structural genes and genes of the nitrogenase-protective features of the heterocyst.

Reconstruction and comparison of the metabolic potential of cyanobacteria Cyanothece sp. ATCC 51142 and Synechocystis sp. PCC 6803.

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Rajib Saha

Full Text Available Cyanobacteria are an important group of photoautotrophic organisms that can synthesize valuable bio-products by harnessing solar energy. They are endowed with high photosynthetic efficiencies and diverse metabolic capabilities that confer the ability to convert solar energy into a variety of biofuels and their precursors. However, less well studied are the similarities and differences in metabolism of different species of cyanobacteria as they pertain to their suitability as microbial production chassis. Here we assemble, update and compare genome-scale models (iCyt773 and iSyn731 for two phylogenetically related cyanobacterial species, namely Cyanothece sp. ATCC 51142 and Synechocystis sp. PCC 6803. All reactions are elementally and charge balanced and localized into four different intracellular compartments (i.e., periplasm, cytosol, carboxysome and thylakoid lumen and biomass descriptions are derived based on experimental measurements. Newly added reactions absent in earlier models (266 and 322, respectively span most metabolic pathways with an emphasis on lipid biosynthesis. All thermodynamically infeasible loops are identified and eliminated from both models. Comparisons of model predictions against gene essentiality data reveal a specificity of 0.94 (94/100 and a sensitivity of 1 (19/19 for the Synechocystis iSyn731 model. The diurnal rhythm of Cyanothece 51142 metabolism is modeled by constructing separate (light/dark biomass equations and introducing regulatory restrictions over light and dark phases. Specific metabolic pathway differences between the two cyanobacteria alluding to different bio-production potentials are reflected in both models.

Glutaredoxins are essential for stress adaptation in the cyanobacterium Synechocystis sp. PCC 6803.

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Ana M Sánchez-Riego

2013-11-01

Full Text Available Glutaredoxin are small redox proteins able to reduce disulfides and mixed disulfides between GSH and proteins. Synechocystis sp. PCC 6803 contains three genes coding for glutaredoxins: ssr2061 (grxA and slr1562 (grxB code for dithiolic glutaredoxins while slr1846 (grxC codes for a monothiolic glutaredoxin. We have analyzed the expression of these glutaredoxins in response to different stresses, such as high light, H2O2 and heat shock. Analysis of the mRNA levels showed that grxA is only induced by heat while grxC is repressed by heat shock and is induced by high light and H2O2. In contrast, grxB expression was maintained almost constant under all conditions. Analysis of GrxA and GrxC protein levels by western blot showed that GrxA increases in response to high light, heat or H2O2 while GrxC is only induced by high light and H2O2, in accordance with its mRNA levels. In addition, we have also generated mutants that have interrupted one, two or three glutaredoxin genes. These mutants were viable and did not show any different phenotype from the WT under standard growth conditions. Nevertheless, analysis of these mutants under several stress conditions revealed that single grxA mutants grow slower after H2O2, heat and high light treatments, while mutants in grxB are indistinguishable from WT. grxC mutants were hypersensitive to treatments with H2O2, heat, high light and metals. A double grxAgrxC mutant was found to be even more sensitive to H2O2 than each corresponding single mutants. Surprisingly a mutation in grxB suppressed totally or partially the phenotypes of grxA and grxC mutants except the H2O2 sensitivity of the grxC mutant. This suggests that grxA and grxC participate in independent pathways while grxA and grxB participate in a common pathway for H2O2 resistance. The data presented here show that glutaredoxins are essential for stress adaptation in cyanobacteria, although their targets and mechanism of action remain unidentified.

Resistance, accumulation and transformation of selenium by the cyanobacterium Synechocystis sp. PCC 6803 after exposure to inorganic SeVI or SeIV

International Nuclear Information System (INIS)

Gouget, B.; Avoscan, L.; Collins, R.; Carriere, M.; Sarret, G.

2005-01-01

Our purpose was to investigate the ability of Synechocystis sp. PCC 6803, a photosynthetic prokaryote isolated from fresh water, to resist, incorporate and reduce the oxidized forms of selenium including selenite and selenate, the major selenium species present in aquatic systems. Selenium speciation and the chemical intermediates during selenium transformation were determined by X-ray absorption near edge structure (XANES) spectroscopy. The possible internalisation pathways involving selenium and the metabolic fate of selenate and selenite were examined. Selenate metabolism seemed to proceed via the sulfate reduction pathway resulting in the formation of the R-Se-H, R-Se-R and R-Se-Se-R species. The transformation of selenate to toxic amino acids may explain the high sensitivity of Synechocystis to selenate. Several mechanisms of selenium reduction seem to complete during selenite assimilation. A specific mechanism may transform internalised selenite into selenide and, subsequently induce the biosynthesis of selenoproteins. A non-specific mechanism may interfere with thiols, such as glutathione in the cell cytoplasm, or with proteins in the periplasm of the bacteria, notably thioredoxins. Several hypotheses concerning the complex transformation of selenium in Synechocystis could therefore be proposed. (orig.)

ORF Alignment: NC_004113 [GENIUS II[Archive

Lifescience Database Archive (English)

Full Text Available se ... [Thermosynechococcus elongatus BP-1] ... Length = 99 ... Query: 9 ... PWKRTPVKTWRFPIKTTIRIGRAADNDVI...LNDILVSRYHAELSCYRDPENLGRWFLKSLG 68 ... PWKRTPVKTWRFPIKTTIRIGRAADNDVI...LNDILVSRYHAELSCYRDPENLGRWFLKSLG Sbjct: 1 ... PWKRTPVKTWRFPIKTTIRIGRAADNDVILNDILVSRYHAELSCYRDPENLGRWFLKSLG 60 ...

Mechanisms of High Temperature Resistance of Synechocystis sp. PCC 6803: An Impact of Histidine Kinase 34

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Jan Červený

2015-03-01

Full Text Available Synechocystis sp. PCC 6803 is a widely used model cyanobacterium for studying responses and acclimation to different abiotic stresses. Changes in transcriptome, proteome, lipidome, and photosynthesis in response to short term heat stress are well studied in this organism, and histidine kinase 34 (Hik34 is shown to play an important role in mediating such response. Corresponding data on long term responses, however, are fragmentary and vary depending on parameters of experiments and methods of data collection, and thus are hard to compare. In order to elucidate how the early stress responses help cells to sustain long-term heat stress, as well as the role of Hik34 in prolonged acclimation, we examined the resistance to long-term heat stress of wild-type and ΔHik34 mutant of Synechocystis. In this work, we were able to precisely control the long term experimental conditions by cultivating Synechocystis in automated photobioreactors, measuring selected physiological parameters within a time range of minutes. In addition, morphological and ultrastructural changes in cells were analyzed and western blotting of individual proteins was used to study the heat stress-affected protein expression. We have shown that the majority of wild type cell population was able to recover after 24 h of cultivation at 44 °C. In contrast, while ΔHik34 mutant cells were resistant to heat stress within its first hours, they could not recover after 24 h long high temperature treatment. We demonstrated that the early induction of HspA expression and maintenance of high amount of other HSPs throughout the heat incubation is critical for successful adaptation to long-term stress. In addition, it appears that histidine kinase Hik34 is an essential component for the long term high temperature resistance.

Mechanisms of High Temperature Resistance of Synechocystis sp. PCC 6803: An Impact of Histidine Kinase 34.

Science.gov (United States)

Červený, Jan; Sinetova, Maria A; Zavřel, Tomáš; Los, Dmitry A

2015-03-02

Synechocystis sp. PCC 6803 is a widely used model cyanobacterium for studying responses and acclimation to different abiotic stresses. Changes in transcriptome, proteome, lipidome, and photosynthesis in response to short term heat stress are well studied in this organism, and histidine kinase 34 (Hik34) is shown to play an important role in mediating such response. Corresponding data on long term responses, however, are fragmentary and vary depending on parameters of experiments and methods of data collection, and thus are hard to compare. In order to elucidate how the early stress responses help cells to sustain long-term heat stress, as well as the role of Hik34 in prolonged acclimation, we examined the resistance to long-term heat stress of wild-type and ΔHik34 mutant of Synechocystis. In this work, we were able to precisely control the long term experimental conditions by cultivating Synechocystis in automated photobioreactors, measuring selected physiological parameters within a time range of minutes. In addition, morphological and ultrastructural changes in cells were analyzed and western blotting of individual proteins was used to study the heat stress-affected protein expression. We have shown that the majority of wild type cell population was able to recover after 24 h of cultivation at 44 °C. In contrast, while ΔHik34 mutant cells were resistant to heat stress within its first hours, they could not recover after 24 h long high temperature treatment. We demonstrated that the early induction of HspA expression and maintenance of high amount of other HSPs throughout the heat incubation is critical for successful adaptation to long-term stress. In addition, it appears that histidine kinase Hik34 is an essential component for the long term high temperature resistance.

Designing & Evaluating General Individual Preconception Care : - The Ready for a Baby program -

NARCIS (Netherlands)

S. Temel (Sevilay)

2016-01-01

markdownabstractPreconception Care (PCC) entails risk assessment, health promotion, counselling, and intervention. The Dutch Health Council categorized PCC into general PCC targeted at couples planning a pregnancy within the general population, and specialist PCC for couples with a known or

RNA-seq based identification and mutant validation of gene targets related to ethanol resistance in cyanobacterial Synechocystis sp. PCC 6803

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Wang Jiangxin

2012-12-01

Full Text Available Abstract Background Fermentation production of biofuel ethanol consumes agricultural crops, which will compete directly with the food supply. As an alternative, photosynthetic cyanobacteria have been proposed as microbial factories to produce ethanol directly from solar energy and CO2. However, the ethanol productivity from photoautotrophic cyanobacteria is still very low, mostly due to the low tolerance of cyanobacterial systems to ethanol stress. Results To build a foundation necessary to engineer robust ethanol-producing cyanobacterial hosts, in this study we applied a quantitative transcriptomics approach with a next-generation sequencing technology, combined with quantitative reverse-transcript PCR (RT-PCR analysis, to reveal the global metabolic responses to ethanol in model cyanobacterial Synechocystis sp. PCC 6803. The results showed that ethanol exposure induced genes involved in common stress responses, transporting and cell envelope modification. In addition, the cells can also utilize enhanced polyhydroxyalkanoates (PHA accumulation and glyoxalase detoxication pathway as means against ethanol stress. The up-regulation of photosynthesis by ethanol was also further confirmed at transcriptional level. Finally, we used gene knockout strains to validate the potential target genes related to ethanol tolerance. Conclusion RNA-Seq based global transcriptomic analysis provided a comprehensive view of cellular response to ethanol exposure. The analysis provided a list of gene targets for engineering ethanol tolerance in cyanobacterium Synechocystis.

ORF Alignment: NC_004113 [GENIUS II[Archive

Lifescience Database Archive (English)

Full Text Available ... elongatus BP-1] ... Length = 211 ... Query: 1 ... MATLEFLTFPDPAIAADHTLLLLHGWGANAADLISLGPLLAPHAQIYAAEAPF...PHPYVAQ 60 ... MATLEFLTFPDPAIAADHTLLLLHGWGANAADLISLGPLLAPHAQIYAAEAPFPHPYVA...Q Sbjct: 1 ... MATLEFLTFPDPAIAADHTLLLLHGWGANAADLISLGPLLAPHAQIYAAEAPFPHPYVAQ 60 ... Query: 121 AVGLRLPLAGLLVFSGYLV

The effect of hippocampal function, volume and connectivity on posterior cingulate cortex functioning during episodic memory fMRI in mild cognitive impairment.

Science.gov (United States)

Papma, Janne M; Smits, Marion; de Groot, Marius; Mattace Raso, Francesco U; van der Lugt, Aad; Vrooman, Henri A; Niessen, Wiro J; Koudstaal, Peter J; van Swieten, John C; van der Veen, Frederik M; Prins, Niels D

2017-09-01

Diminished function of the posterior cingulate cortex (PCC) is a typical finding in early Alzheimer's disease (AD). It is hypothesized that in early stage AD, PCC functioning relates to or reflects hippocampal dysfunction or atrophy. The aim of this study was to examine the relationship between hippocampus function, volume and structural connectivity, and PCC activation during an episodic memory task-related fMRI study in mild cognitive impairment (MCI). MCI patients (n = 27) underwent episodic memory task-related fMRI, 3D-T1w MRI, 2D T2-FLAIR MRI and diffusion tensor imaging. Stepwise linear regression analysis was performed to examine the relationship between PCC activation and hippocampal activation, hippocampal volume and diffusion measures within the cingulum along the hippocampus. We found a significant relationship between PCC and hippocampus activation during successful episodic memory encoding and correct recognition in MCI patients. We found no relationship between the PCC and structural hippocampal predictors. Our results indicate a relationship between PCC and hippocampus activation during episodic memory engagement in MCI. This may suggest that during episodic memory, functional network deterioration is the most important predictor of PCC functioning in MCI. • PCC functioning during episodic memory relates to hippocampal functioning in MCI. • PCC functioning during episodic memory does not relate to hippocampal structure in MCI. • Functional network changes are an important predictor of PCC functioning in MCI.

CT Perfusion evaluation of gastric cancer. Correlation with histologic type

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Lee, Dong Ho; Joo, Ijin [Seoul National University Hospital, Department of Radiology, Seoul (Korea, Republic of); Kim, Se Hyung [Seoul National University Hospital, Department of Radiology, Seoul (Korea, Republic of); Seoul National University College of Medicine, Department of Radiology, Seoul (Korea, Republic of); Han, Joon Koo [Seoul National University Hospital, Department of Radiology, Seoul (Korea, Republic of); Seoul National University College of Medicine, Department of Radiology, Seoul (Korea, Republic of); Seoul National University Medical Research Center, Institute of Radiation Medicine, Seoul (Korea, Republic of)

2018-02-15

To prospectively evaluate if the perfusion parameters of gastric cancer can provide information on histologic subtypes of gastric cancer. We performed preoperative perfusion CT (PCT) and curative gastrectomy in 46 patients. PCT data were analysed using a dedicated software program. Perfusion parameters were obtained by two independent radiologists and were compared according to histologic type using Kruskal-Wallis, Mann-Whitney U test and receiver operating characteristic analysis. To assess inter-reader agreement, we used intraclass correlation coefficient (ICC). Inter-reader agreement for perfusion parameters was moderate to substantial (ICC = 0.585-0.678). Permeability surface value of poorly cohesive carcinoma (PCC) was significantly higher than other histologic types (47.3 ml/100 g/min in PCC vs 26.5 ml/100 g/min in non-PCC, P < 0.001). Mean transit time (MTT) of PCC was also significantly longer than non-PCC (13.0 s in PCC vs 10.3 s in non-PCC, P = 0.032). The area under the curve to predict PCC was 0.891 (P < 0.001) for permeability surface and 0.697 (P = 0.015) for MTT. Obtaining perfusion parameters from PCT was feasible in gastric cancer patients and can aid in the preoperative imaging diagnosis of PCC-type gastric cancer as the permeability surface and MTT value of PCC type gastric cancer were significantly higher than those of non-PCC. (orig.)

CT Perfusion evaluation of gastric cancer. Correlation with histologic type

International Nuclear Information System (INIS)

Lee, Dong Ho; Joo, Ijin; Kim, Se Hyung; Han, Joon Koo

2018-01-01

To prospectively evaluate if the perfusion parameters of gastric cancer can provide information on histologic subtypes of gastric cancer. We performed preoperative perfusion CT (PCT) and curative gastrectomy in 46 patients. PCT data were analysed using a dedicated software program. Perfusion parameters were obtained by two independent radiologists and were compared according to histologic type using Kruskal-Wallis, Mann-Whitney U test and receiver operating characteristic analysis. To assess inter-reader agreement, we used intraclass correlation coefficient (ICC). Inter-reader agreement for perfusion parameters was moderate to substantial (ICC = 0.585-0.678). Permeability surface value of poorly cohesive carcinoma (PCC) was significantly higher than other histologic types (47.3 ml/100 g/min in PCC vs 26.5 ml/100 g/min in non-PCC, P < 0.001). Mean transit time (MTT) of PCC was also significantly longer than non-PCC (13.0 s in PCC vs 10.3 s in non-PCC, P = 0.032). The area under the curve to predict PCC was 0.891 (P < 0.001) for permeability surface and 0.697 (P = 0.015) for MTT. Obtaining perfusion parameters from PCT was feasible in gastric cancer patients and can aid in the preoperative imaging diagnosis of PCC-type gastric cancer as the permeability surface and MTT value of PCC type gastric cancer were significantly higher than those of non-PCC. (orig.)

Optical characterization of the oceanic unicellular cyanobacterium Synechococcus grown under a day-night cycle in natural irradiance

Science.gov (United States)

Stramski, Dariusz; Shalapyonok, Alexi; Reynolds, Rick A.

1995-01-01

The optical properties of the ocenanic cyanobacterium Synechococcus (clone WH8103) were examined in a nutrient-replete laboratory culture grown under a day-night cycle in natural irradiance. Measurements of the spectral absorption and beam attenuation coefficients, the size distribution of cells in suspension, and microscopic analysis of samples were made at intervals of 2-4 hours for 2 days. These measurements were used to calculate the optical properties at the level of a single 'mean' cell representative of the acutal population, specifically, the optical cross sections for spectral absorption bar-(sigma(sub a)), scattering bar-sigma(sub b))(lambda), and attentuation bar-(sigma(sub c))(lambda). In addition, concurrent determinations of chlorophyll a and particulate organic carbon allowed calculation of the Chl a- and C-specific optical coefficients. The refractive index of cells was derived from the observed data using a theory of light absorption and scattering by homogeneous spheres. Low irradiance because of cloudy skies resulted in slow division rates of cells in the culture. The percentage of dividing cells was unusually high (greater than 30%) throughout the experiment. The optical cross sections varied greatly over a day-night cycle, with a minimum near dawn or midmorning and maximum near dusk. During daylight hours, bar-(sigma(sub b)) and bar-(sigma(sub c)) can increase more than twofold and bar-(sigma(sub a) by as much as 45%. The real part of the refractive index n increaed during the day; changes in n had equal or greater effect than the varying size distribution on changes in bar-(sigma(sub c)) and bar-(sigma(sub b)). The contribution of changes in n to the increase of bar-(sigma(sub c))(660) during daylight hours was 65.7% and 45.1% on day 1 and 2, respectively. During the dark period, when bar-(sigma(sub c))(660) decreased by a factor of 2.9, the effect of decreasing n was dominant (86.3%). With the exception of a few hours during the second light

Cofactors involved in light-driven charge separation in photosystem I identified by subpicosecond infrared spectroscopy.

Science.gov (United States)

Di Donato, Mariangela; Stahl, Andreas D; van Stokkum, Ivo H M; van Grondelle, Rienk; Groot, Marie-Louise

2011-02-01

Photosystem I is one of the key players in the conversion of solar energy into chemical energy. While the chlorophyll dimer P(700) has long been identified as the primary electron donor, the components involved in the primary charge separation process in PSI remain undetermined. Here, we have studied the charge separation dynamics in Photosystem I trimers from Synechococcus elongatus by femtosecond vis-pump/mid-infrared-probe spectroscopy upon excitation at 700, 710, and 715 nm. Because of the high specificity of the infrared region for the redox state and small differences in the molecular structure of pigments, we were able to clearly identify specific marker bands indicating chlorophyll (Chl) oxidation. Magnitudes of chlorophyll cation signals are observed to increase faster than the time resolution of the experiment (~0.2 ps) upon both excitation conditions: 700 nm and selective red excitation. Two models, involving either ultrafast charge separation or charge transfer character of the red pigments in PSI, are discussed to explain this observation. A further increase in the magnitudes of cation signals on a subpicosecond time scale (0.8-1 ps) indicates the formation of the primary radical pair. Evolution in the cation region with time constants of 7 and 40 ps reveals the formation of the secondary radical pair, involving a secondary electron donor. Modeling of the data allows us to extract the spectra of the two radical pairs, which have IR signatures consistent with A+A₀- and P₇₀₀+A₁-. We conclude that the cofactor chlorophyll A acts as the primary donor in PSI. The existence of an equilibrium between the two radical pairs we interpret as concerted hole/electron transfer between the pairs of electron donors and acceptors, until after 40 ps, relaxation leads to a full population of the P₇₀₀+A₁. radical pair.

Loop-Loop Interactions Regulate KaiA-Stimulated KaiC Phosphorylation in the Cyanobacterial KaiABC Circadian Clock

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Egli, Martin [Vanderbilt Univ., Nashville, TN (United States); Pattanayek, Rekha [Vanderbilt Univ., Nashville, TN (United States); Sheehan, Jonathan H. [Vanderbilt Univ., Nashville, TN (United States); Xu, Yao [Vanderbilt Univ., Nashville, TN (United States); Mori, Tetsuya [Vanderbilt Univ., Nashville, TN (United States); Smith, Jarrod A. [Vanderbilt Univ., Nashville, TN (United States); Johnson, Carl H. [Vanderbilt Univ., Nashville, TN (United States)

2013-01-25

We found that the Synechococcus elongatus KaiA, KaiB, and KaiC proteins in the presence of ATP generate a post-translational oscillator that runs in a temperature-compensated manner with a period of 24 h. KaiA dimer stimulates phosphorylation of KaiC hexamer at two sites per subunit, T432 and S431, and KaiB dimers antagonize KaiA action and induce KaiC subunit exchange. Neither the mechanism of KaiA-stimulated KaiC phosphorylation nor that of KaiB-mediated KaiC dephosphorylation is understood in detail at present. We demonstrate here that the A422V KaiC mutant sheds light on the former mechanism. It was previously reported that A422V is less sensitive to dark pulse-induced phase resetting and has a reduced amplitude of the KaiC phosphorylation rhythm in vivo. A422 maps to a loop (422-loop) that continues toward the phosphorylation sites. By pulling on the C-terminal peptide of KaiC (A-loop), KaiA removes restraints from the adjacent 422-loop whose increased flexibility indirectly promotes kinase activity. We found in the crystal structure that A422V KaiC lacks phosphorylation at S431 and exhibits a subtle, local conformational change relative to wild-type KaiC. Molecular dynamics simulations indicate higher mobility of the 422-loop in the absence of the A-loop and mobility differences in other areas associated with phosphorylation activity between wild-type and mutant KaiCs. Finally, the A-loop–422-loop relay that informs KaiC phosphorylation sites of KaiA dimer binding propagates to loops from neighboring KaiC subunits, thus providing support for a concerted allosteric mechanism of phosphorylation.

CryoEM and Molecular Dynamics of the Circadian KaiB-KaiC Complex Indicates That KaiB Monomers Interact with KaiC and Block ATP Binding Clefts

Energy Technology Data Exchange (ETDEWEB)

Villarreal, Seth A.; Pattanayek, Rekha; Williams, Dewight R.; Mori, Tetsuya; Qin, Ximing; Johnson, Carl H.; Egli, Martin; Stewart, Phoebe L. [Case Western; (Vanderbilt); (Vanderbilt-MED)

2014-10-02

The circadian control of cellular processes in cyanobacteria is regulated by a posttranslational oscillator formed by three Kai proteins. During the oscillator cycle, KaiA serves to promote autophosphorylation of KaiC while KaiB counteracts this effect. Here, we present a crystallographic structure of the wild-type Synechococcus elongatus KaiB and a cryo-electron microscopy (cryoEM) structure of a KaiBC complex. The crystal structure shows the expected dimer core structure and significant conformational variations of the KaiB C-terminal region, which is functionally important in maintaining rhythmicity. The KaiBC sample was formed with a C-terminally truncated form of KaiC, KaiC-Δ489, which is persistently phosphorylated. The KaiB–KaiC-Δ489 structure reveals that the KaiC hexamer can bind six monomers of KaiB, which form a continuous ring of density in the KaiBC complex. We performed cryoEM-guided molecular dynamics flexible fitting simulations with crystal structures of KaiB and KaiC to probe the KaiBC protein–protein interface. This analysis indicated a favorable binding mode for the KaiB monomer on the CII end of KaiC, involving two adjacent KaiC subunits and spanning an ATP binding cleft. A KaiC mutation, R468C, which has been shown to affect the affinity of KaiB for KaiC and lengthen the period in a bioluminescence rhythm assay, is found within the middle of the predicted KaiBC interface. The proposed KaiB binding mode blocks access to the ATP binding cleft in the CII ring of KaiC, which provides insight into how KaiB might influence the phosphorylation status of KaiC.

Patient perception and the barriers to practicing patient-centered communication: A survey and in-depth interview of Chinese patients and physicians.

Science.gov (United States)

Ting, Xu; Yong, Bao; Yin, Liang; Mi, Tian

2016-03-01

To investigate patient perceptions of patient-centered communication (PCC) in doctor-patient consultations and explore barriers to PCC implementation in China. This study was conducted in public teaching hospital in Guiyang, Guizhou, China. In Phase 1, patient attitudes to PCC were quantitatively assessed in 317 outpatients using modified Patient-Practitioner Orientation Scale (PPOS). In Phase 2, we conducted in-depth interviews with 20 outpatients to explore their views on PCC and expose potential barriers to PCC implementation. Participants communicated "patient-centered" preferences, particularly with regard to their doctors' empathy, communication skills, time and information sharing. Patients were more concerned about doctors exhibiting caring perspective than power sharing. Younger and highly educated patients were more likely to prefer PCC and highly educated patients paid more attention to power sharing. Several factors including inadequate time for PCC resulting from doctors' high patient-load, doctor-patient communication difficulties and excessive treatment due to inappropriate medical payment system affected PCC implementation in China. Patients expressed moderate enthusiasm for PCC in China. They expressed strong preferences concerning physician respect for patient perspective, but less concern for power sharing. Government should improve health care system by implementing PCC in daily healthcare practice to improve patient awareness and preferences. Copyright © 2016. Published by Elsevier Ireland Ltd.

Improving the adsorption of lignocelluloses of prehydrolysis liquor on precipitated calcium carbonate.

Science.gov (United States)

Fatehi, Pedram; Shen, Jing; Hamdan, Fadia C; Ni, Yonghao

2013-02-15

In this work, the adsorption of lignocelluloses of pre-hydrolysis liquor (PHL) on precipitated calcium carbonate (PCC) was studied in the presence of poly diallyldimethylammonium chloride (PDADMAC) or cationic polyacrylamide (CPAM). The results revealed that adding PCC to PHL and subsequently adding cationic polymers to PHL/PCC systems was more effective than adding cationic polymers to PHL and then adding PCC to the cationic polymer/PHL systems. At the same dosage applied, PDADMAC resulted in a higher adsorption of lignocelluloses on PCC than CPAM did due to its higher charge density. The adsorption of lignocelluloses on PCC reached its maximum in 3h, and a high temperature reduced the adsorption level as the adsorption was an exothermic process. The maximum adsorptions of 530 mg/g oligo-sugars, 203 mg/g lignin and 58 mg/g furfural on PCC were achieved via adding 0.8 mg/g PDADMAC2 (i.e. higher MW PDADMAC) to PCC/PHL system. Copyright © 2012 Elsevier Ltd. All rights reserved.

A novel parameter, cell-cycle progression index, for radiation dose absorbed estimation in the premature chromosome condensation assay

International Nuclear Information System (INIS)

Miura, Tomisato; Kasai, Kosuke; Nakano, Manabu; Nakata, Akifumi; Yoshida, Mitsuaki A.; Abe, Yu; Tsushima, Eiki; Ossetrova, Natalia I.; Blakely, William F.

2014-01-01

The calyculin A-induced premature chromosome condensation (PCC) assay is a simple and useful method for assessing the cell-cycle distribution in cells, since calyculin A induces chromosome condensation in various phases of the cell cycle. In this study, a novel parameter, the cell-cycle progression index (CPI), in the PCC assay was validated as a novel bio-marker for bio-dosimetry. Peripheral blood was drawn from healthy donors after informed consent was obtained. CPI was investigated using a human peripheral blood lymphocyte (PBL) ex vivo irradiation ( 60 Co-gamma rays: ∼0.6 Gy min -1 , or X ray: 1.0 Gy min -1 ; 0-10 Gy) model. The calyculin A-induced PCC assay was performed for chromosome preparation. PCC cells were divided into the following five categories according to cell-cycle stage: non-PCC, G1-PCC, S-PCC, G2/M-PCC and M/A-PCC cells. CPI was calculated as the ratio of G2/M-PCC cells to G1-PCC cells. The PCC-stage distribution varied markedly with irradiation doses. The G1-PCC cell fraction was significantly reduced, and the G2/M-PCC cell fraction increased, in 10-Gy-irradiated PBL after 48 h of culture. CPI levels were fitted to an exponential dose-response curve with gamma-ray irradiation [y = 0.6729 + 0.3934 exp(0.5685D), r = 1.0000, p < 0.0001] and X-ray irradiation [y = -0.3743 + 0.9744 exp(0.3321D), r = 0.9999, p < 0.0001]. There were no significant individual (p = 0.853) or gender effects (p = 0.951) on the CPI in the human peripheral blood ex vivo irradiation model. Furthermore, CPI measurements are rapid (< 15 min per case). These results suggest that the CPI is a useful screening tool for the assessment of radiation doses received ranging from 0 to 10 Gy in radiation exposure early after a radiation event, especially after a mass-casualty radiological incident. (authors)

Photoautotrophic Production of Biomass, Laurate, and Soluble Organics by Synechocystis sp. PCC 6803

Science.gov (United States)

Nguyen, Binh Thanh

Photosynthesis converts sunlight to biomass at a global scale. Among the photosynthetic organisms, cyanobacteria provide an excellent model to study how photosynthesis can become a practical platform of large-scale biotechnology. One novel approach involves metabolically engineering the cyanobacterium Synechocystis sp. PCC 6803 to excrete laurate, which is harvested directly. This work begins by defining a working window of light intensity (LI). Wild-type and laurate-excreting Synechocystis required an LI of at least 5 muE/m2-s to sustain themselves, but are photo-inhibited by LI of 346 to 598 muE/m2-s. Fixing electrons into valuable organic products, e.g., biomass and excreted laurate, is critical to success. Wild-type Synechocystis channeled 75% to 84% of its fixed electrons to biomass; laurate-excreting Synechocystis fixed 64 to 69% as biomass and 6.6% to 10% as laurate. This means that 16 to 30% of the electrons were diverted to non-valuable soluble products, and the trend was accentuated with higher LI. How the Ci concentration depended on the pH and the nitrogen source was quantified by the proton condition and experimentally validated. Nitrate increased, ammonium decreased, but ammonium nitrate stabilized alkalinity and Ci. This finding provides a mechanistically sound tool to manage Ci and pH independently. Independent evaluation pH and Ci on the growth kinetics of Synechocystis showed that pH 8.5 supported the fastest maximum specific growth rate (mumax): 2.4/day and 1.7/day, respectively, for the wild type and modified strains with LI of 202 muE/m2-s. Half-maximum-rate concentrations (KCi) were less than 0.1 mM, meaning that Synechocystis should attain its mumax with a modest Ci concentration (≥1.0 mM). Biomass grown with day-night cycles had a night endogenous decay rate of 0.05-1.0/day, with decay being faster with higher LI and the beginning of dark periods. Supplying light at a fraction of daylight reduced dark decay rate and improved overall

Identification of OmpR-family response regulators interacting with thioredoxin in the Cyanobacterium Synechocystis sp. PCC 6803.

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Taro Kadowaki

Full Text Available The redox state of the photosynthetic electron transport chain is known to act as a signal to regulate the transcription of key genes involved in the acclimation responses to environmental changes. We hypothesized that the protein thioredoxin (Trx acts as a mediator connecting the redox state of the photosynthetic electron transport chain and transcriptional regulation, and established a screening system to identify transcription factors (TFs that interact with Trx. His-tagged TFs and S-tagged mutated form of Trx, TrxMC35S, whose active site cysteine 35 was substituted with serine to trap the target interacting protein, were co-expressed in E. coli cells and Trx-TF complexes were detected by immuno-blotting analysis. We examined the interaction between Trx and ten OmpR family TFs encoded in the chromosome of the cyanobacterium Synechocystis sp. PCC 6803 (S.6803. Although there is a highly conserved cysteine residue in the receiver domain of all OmpR family TFs, only three, RpaA (Slr0115, RpaB (Slr0947 and ManR (Slr1837, were identified as putative Trx targets [corrected].The recombinant forms of wild-type TrxM, RpaA, RpaB and ManR proteins from S.6803 were purified following over-expression in E. coli and their interaction was further assessed by monitoring changes in the number of cysteine residues with free thiol groups. An increase in the number of free thiols was observed after incubation of the oxidized TFs with Trx, indicating the reduction of cysteine residues as a consequence of interaction with Trx. Our results suggest, for the first time, the possible regulation of OmpR family TFs through the supply of reducing equivalents from Trx, as well as through the phospho-transfer from its cognate sensor histidine kinase.

Enhanced accumulation of glycogen, lipids and polyhydroxybutyrate under optimal nutrients and light intensities in the cyanobacterium Synechocystis sp. PCC 6803.

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Monshupanee, T; Incharoensakdi, A

2014-04-01

Glycogen (GL) and lipids (LP) are efficient biofuel substrates, whereas polyhydroxybutyrate (PHB) is a potent biodegradable plastic. This study aimed to increase accumulation of these three compounds in Synechocystis sp. PCC 6803. Under autophototrophic growth, co-accumulation of the three compounds reached maximum level in a mid-stationary phase at 39·2% of dry weight (22·7% GL, 14·1% LP and 2·4% PHB). Nitrogen deprivation increased this to 61·5% (36·8% GL, 11·2% LP and 13·5% PHB), higher than that achieved by phosphorus, sulfur, iron or calcium deprivation. Combining nitrogen deprivation with 0·4% (w/v) glucose addition for heterophototrophic growth and optimizing the light intensity (200 μmol photons m(-2) s(-1) ) synergistically enhanced combined accumulation to 71·1% of biomass (41·3% GL, 16·7% LP and 13·1% PHB), a higher level than previously reported in Synechocystis. However, the maximum coproductivity of GL, LP and PHB (at 0·72 g l(-1) ) was obtained in the 12-day heterophototrophic culture without nitrogen deprivation. Accumulation of GL, LP and PHB was enhanced under both autophototrophic and heterophototrophic conditions by optimizations of nutrient and light supplies. This study provides a means for increasing co-production of potent bioenergy substrates and useful biomaterials in Synechocystis which may also be applicable to other cyanobacteria. © 2013 The Society for Applied Microbiology.

Cyanide binding to hexacoordinate cyanobacterial hemoglobins: hydrogen-bonding network and heme pocket rearrangement in ferric H117A Synechocystis hemoglobin.

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Vu, B Christie; Nothnagel, Henry J; Vuletich, David A; Falzone, Christopher J; Lecomte, Juliette T J

2004-10-05

The truncated hemoglobin (Hb) from the cyanobacterium Synechocystis sp. PCC 6803 is a bis-histidyl hexacoordinate complex in the absence of exogenous ligands. This protein can form a covalent cross-link between His117 in the H-helix and the heme 2-vinyl group. Cross-linking, the physiological importance of which has not been established, is avoided with the His117Ala substitution. In the present work, H117A Hb was used to explore exogenous ligand binding to the heme group. NMR and thermal denaturation data showed that the replacement was of little consequence to the structural and thermodynamic properties of ferric Synechocystis Hb. It did, however, decelerate the association of cyanide ions with the heme iron. Full complexation required hours, instead of minutes, of incubation at optical and NMR concentrations. At neutral pH and in the presence of excess cyanide, binding occurred with a first-order dependence on cyanide concentration, eliminating distal histidine decoordination as the rate-limiting step. The cyanide complex of the H117A variant was characterized for the conformational changes occurring as the histidine on the distal side, His46 (E10), was displaced. Extensive rearrangement allowed Tyr22 (B10) to insert in the heme pocket and Gln43 (E7) and Gln47 (E11) to come in contact with it. H-bond formation to the bound cyanide was identified in solution with the use of (1)H(2)O/(2)H(2)O mixtures. Cyanide binding also resulted in a change in the ratio of heme orientational isomers, in a likely manifestation of heme environment reshaping. Similar observations were made with the related Synechococcus sp. PCC 7002 H117A Hb, except that cyanide binding was rapid in this protein. In both cases, the (15)N chemical shift of bound cyanide was reminiscent of that in peroxidases and the orientation of the proximal histidine was as in other truncated Hbs. The ensemble of the data provided insight into the structural cooperativity of the heme pocket scaffold and pointed

[Evaluation of ten fish species to be included as part of renal diet, due to their protein, phosphorus and fatty acids content].

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Castro-González, Maria Isabel; Maafs-Rodríguez, Ana Gabriela; Pérez-Gil Romo, Fernando

2012-06-01

Because renal disease is highly complex, its nutritional treatment is complicated and many foods are restricted, including fish because its phosphorus content. The aim of the present study was to analyze ten fillet fish species, commonly consumed in Mexico (Cyprinus carpio carpio, Ophichthus rex, Symphurus elongatus, Eucinostomus entomelas, Chirostoma patzcuaro, Bairdiella chrysoura, Salmo salar Oreochromis urolepis hornorum, Sphyraena guachancho, Istiophorus albicans), to determine their phosphorus (P), protein (Pr), cholesterol, sodium, potassium, vitamins D3 and E, and n-3 PUFA (EPA+DHA) according to the AOAC techniques, in order to identify which species could be included in renal diet; particularly because of their risk:benefit relations (calculated with those results). Protein values ranged from 16.5 to 33.5g/100 g of fillet; the specie with the highest phosphorus contest was Salmo salar, and with the lowest, Symphurus elongatus. EPA+DHA quantity ranged from 79.64 mg/100 g to 1,381.53 mg/100 g. Considering de P/Pr relation recommended to renal patients, all analyzed species (except Salmo salar, Ophichthus rex and Istiophorus albicans) could be included in their diet. As for the P/EPA+DHA relation, the species most recommended to renal patients are Symphurus elongatus, Bairdiella chrysoura and Sphyraena guachancho.

The Affect of the Space Environment on the Survival of Halorubrum Chaoviator and Synechococcus (Nageli): Data from the Space Experiment OSMO on EXPOSE-R

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Mancinelli, R. L.

2014-01-01

We have shown using ESA's Biopan facility flown in Earth orbit that when exposed to the space environment for 2 weeks the survival rate of Synechococcus (Nageli), a halophilic cyanobacterium isolated from the evaporitic gypsum-halite crusts that form along the marine intertidal, and Halorubrum chaoviator a member of the Halobacteriaceae isolated from an evaporitic NaCl crystal obtained from a salt evaporation pond, were higher than all other test organisms except Bacillus spores. These results led to the EXPOSE-R mission to extend and refine these experiments as part of the experimental package for the external platform space exposure facility on the ISS. The experiment was flown in February 2009 and the organisms were exposed to low-Earth orbit for nearly 2 years. Samples were either exposed to solar ultraviolet (UV)-radiation (lambda is greater than 110 nm or lambda is greater than 200 nm, cosmic radiation (dosage range 225-320 mGy), or kept in darkness shielded from solar UV-radiation. Half of each of the UV-radiation exposed samples and dark samples were exposed to space vacuum and half kept at 105 pascals in argon. Duplicate samples were kept in the laboratory to serve as unexposed controls. Ground simulation control experiments were also performed. After retrieval, organism viability was tested using Molecular Probes Live-Dead Bac-Lite stain and by their reproduction capability. Samples kept in the dark, but exposed to space vacuum had a 90 +/- 5% survival rate compared to the ground controls. Samples exposed to full UV-radiation for over a year were bleached and although results from Molecular Probes Live-Dead stain suggested approximately 10% survival, the data indicate that no survival was detected using cell growth and division using the most probable number method. Those samples exposed to attenuated UV-radiation exhibited limited survival. Results from of this study are relevant to understanding adaptation and evolution of life, the future of life

Transcription activation by NtcA and 2-oxoglutarate of three genes involved in heterocyst differentiation in the cyanobacterium Anabaena sp. strain PCC 7120.

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Valladares, Ana; Flores, Enrique; Herrero, Antonia

2008-09-01

In Anabaena sp. strain PCC 7120, differentiation of heterocysts takes place in response to the external cue of combined nitrogen deprivation, allowing the organism to fix atmospheric nitrogen in oxic environments. NtcA, a global transcriptional regulator of cyanobacteria, is required for activation of the expression of multiple genes involved in heterocyst differentiation, including key regulators that are specific to the process. We have set up a fully defined in vitro system, which includes the purified Anabaena RNA polymerase, and have studied the effects of NtcA and its signaling effector 2-oxoglutarate on RNA polymerase binding, open complex formation, and transcript production from promoters of the hetC, nrrA, and devB genes that are activated by NtcA at different stages of heterocyst differentiation. Both RNA polymerase and NtcA could specifically bind to the target DNA in the absence of any effector. 2-Oxoglutarate had a moderate positive effect on NtcA binding, and NtcA had a limited positive effect on RNA polymerase recruitment at the promoters. However, a stringent requirement of both NtcA and 2-oxoglutarate was observed for the detection of open complexes and transcript production at the three investigated promoters. These results support a key role for 2-oxoglutarate in transcription activation in the developing heterocyst.

Degradation of textile dyes by cyanobacteria.

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Dellamatrice, Priscila Maria; Silva-Stenico, Maria Estela; Moraes, Luiz Alberto Beraldo de; Fiore, Marli Fátima; Monteiro, Regina Teresa Rosim

Dyes are recalcitrant compounds that resist conventional biological treatments. The degradation of three textile dyes (Indigo, RBBR and Sulphur Black), and the dye-containing liquid effluent and solid waste from the Municipal Treatment Station, Americana, São Paulo, Brazil, by the cyanobacteria Anabaena flos-aquae UTCC64, Phormidium autumnale UTEX1580 and Synechococcus sp. PCC7942 was evaluated. The dye degradation efficiency of the cyanobacteria was compared with anaerobic and anaerobic-aerobic systems in terms of discolouration and toxicity evaluations. The discoloration was evaluated by absorption spectroscopy. Toxicity was measured using the organisms Hydra attenuata, the alga Selenastrum capricornutum and lettuce seeds. The three cyanobacteria showed the potential to remediate textile effluent by removing the colour and reducing the toxicity. However, the growth of cyanobacteria on sludge was slow and discoloration was not efficient. The cyanobacteria P. autumnale UTEX1580 was the only strain that completely degraded the indigo dye. An evaluation of the mutagenicity potential was performed by use of the micronucleus assay using Allium sp. No mutagenicity was observed after the treatment. Two metabolites were produced during the degradation, anthranilic acid and isatin, but toxicity did not increase after the treatment. The cyanobacteria showed the ability to degrade the dyes present in a textile effluent; therefore, they can be used in a tertiary treatment of effluents with recalcitrant compounds. Copyright © 2016 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

Strong, weak, and missing links in a microbial community of the N.W. Mediterranean Sea.

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Bettarel, Y; Dolan, J R; Hornak, K; Lemée, R; Masin, M; Pedrotti, M-L; Rochelle-Newall, E; Simek, K; Sime-Ngando, T

2002-12-01

Planktonic microbial communities often appear stable over periods of days and thus tight links are assumed to exist between different functional groups (i.e. producers and consumers). We examined these links by characterizing short-term temporal correspondences in the concentrations and activities of microbial groups sampled from 1 m depth, at a coastal site of the N.W. Mediterranean Sea, in September 2001 every 3 h for 3 days. We estimated the abundance and activity rates of the autotrophic prokaryote Synechococcus, heterotrophic bacteria, viruses, heterotrophic nanoflagellates, as well as dissolved organic carbon concentrations. We found that Synechococcus, heterotrophic bacteria, and viruses displayed distinct patterns. Synechococcus abundance was greatest at midnight and lowest at 21:00 and showed the common pattern of an early evening maximum in dividing cells. In contrast, viral concentrations were minimal at midnight and maximal at 18:00. Viral infection of heterotrophic bacteria was rare (0.5-2.5%) and appeared to peak at 03:00. Heterotrophic bacteria, as % eubacteria-positive cells, peaked at midday, appearing loosely related to relative changes in dissolved organic carbon concentration. Bacterial production as assessed by leucine incorporation showed no consistent temporal pattern but could be related to shifts in the grazing rates of heterotrophic nanoflagellates and viral infection rates. Estimates of virus-induced mortality of heterotrophic bacteria, based on infection frequencies, were only about 10% of cell production. Overall, the dynamics of viruses appeared more closely related to Synechococcus than to heterotrophic bacteria. Thus, we found weak links between dissolved organic carbon concentration, or grazing, and bacterial activity, a possibly strong link between Synechococcus and viruses, and a missing link between light and viruses.

The effect of hippocampal function, volume and connectivity on posterior cingulate cortex functioning during episodic memory fMRI in mild cognitive impairment

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Papma, Janne M.; Koudstaal, Peter J.; Swieten, John C. van; Smits, Marion; Lugt, Aad van der; Groot, Marius de; Vrooman, Henri A.; Mattace Raso, Francesco U.; Niessen, Wiro J.; Veen, Frederik M. van der; Prins, Niels D.

2017-01-01

Diminished function of the posterior cingulate cortex (PCC) is a typical finding in early Alzheimer's disease (AD). It is hypothesized that in early stage AD, PCC functioning relates to or reflects hippocampal dysfunction or atrophy. The aim of this study was to examine the relationship between hippocampus function, volume and structural connectivity, and PCC activation during an episodic memory task-related fMRI study in mild cognitive impairment (MCI). MCI patients (n = 27) underwent episodic memory task-related fMRI, 3D-T1w MRI, 2D T2-FLAIR MRI and diffusion tensor imaging. Stepwise linear regression analysis was performed to examine the relationship between PCC activation and hippocampal activation, hippocampal volume and diffusion measures within the cingulum along the hippocampus. We found a significant relationship between PCC and hippocampus activation during successful episodic memory encoding and correct recognition in MCI patients. We found no relationship between the PCC and structural hippocampal predictors. Our results indicate a relationship between PCC and hippocampus activation during episodic memory engagement in MCI. This may suggest that during episodic memory, functional network deterioration is the most important predictor of PCC functioning in MCI. (orig.)

The effect of hippocampal function, volume and connectivity on posterior cingulate cortex functioning during episodic memory fMRI in mild cognitive impairment

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Papma, Janne M.; Koudstaal, Peter J.; Swieten, John C. van [Erasmus MC - University Medical Center Rotterdam, Department of Neurology, Rotterdam (Netherlands); Smits, Marion; Lugt, Aad van der [Erasmus MC - University Medical Center Rotterdam, Department of Radiology, Rotterdam (Netherlands); Groot, Marius de; Vrooman, Henri A. [Erasmus MC - University Medical Center Rotterdam, Department of Radiology, Rotterdam (Netherlands); Erasmus MC - University Medical Center Rotterdam, Department of Medical Informatics, Rotterdam (Netherlands); Mattace Raso, Francesco U. [Erasmus MC - University Medical Center Rotterdam, Department of Geriatrics, Rotterdam (Netherlands); Niessen, Wiro J. [Erasmus MC - University Medical Center Rotterdam, Department of Radiology, Rotterdam (Netherlands); Erasmus MC - University Medical Center Rotterdam, Department of Medical Informatics, Rotterdam (Netherlands); Delft University of Technology, Faculty of Applied Sciences, Delft (Netherlands); Veen, Frederik M. van der [Erasmus University Rotterdam, Institute of Psychology, Rotterdam (Netherlands); Prins, Niels D. [VU University Medical Center, Alzheimer Center, Department of Neurology, Amsterdam (Netherlands)

2017-09-15

Diminished function of the posterior cingulate cortex (PCC) is a typical finding in early Alzheimer's disease (AD). It is hypothesized that in early stage AD, PCC functioning relates to or reflects hippocampal dysfunction or atrophy. The aim of this study was to examine the relationship between hippocampus function, volume and structural connectivity, and PCC activation during an episodic memory task-related fMRI study in mild cognitive impairment (MCI). MCI patients (n = 27) underwent episodic memory task-related fMRI, 3D-T1w MRI, 2D T2-FLAIR MRI and diffusion tensor imaging. Stepwise linear regression analysis was performed to examine the relationship between PCC activation and hippocampal activation, hippocampal volume and diffusion measures within the cingulum along the hippocampus. We found a significant relationship between PCC and hippocampus activation during successful episodic memory encoding and correct recognition in MCI patients. We found no relationship between the PCC and structural hippocampal predictors. Our results indicate a relationship between PCC and hippocampus activation during episodic memory engagement in MCI. This may suggest that during episodic memory, functional network deterioration is the most important predictor of PCC functioning in MCI. (orig.)

Competing agendas and other tensions in developing patient-centred communication in audiology education: a qualitative study of educator perspectives.

Science.gov (United States)

Tai, Samantha; Barr, Caitlin; Woodward-Kron, Robyn

2018-04-01

Patient-centred communication (PCC) is an essential skill for effective healthcare provision and is accepted as a core competency in medicine and allied health. In audiology, recent studies have shown that audiologists rarely display PCC in adult hearing interactions. This highlights a need to investigate how PCC is taught and learnt in audiology. There is a paucity of studies on PCC in audiology education. The aim of this study is to examine educator perceptions of teaching PCC, including barriers and facilitators, in Australian graduate audiology programmes. Semi-structured interviews were conducted with audiology educators responsible for communication training. Interview transcripts were analysed using qualitative content analysis. Nine participants, including programme coordinators and key teaching staff from all six Australian audiology programmes participated in the study. PCC education was found to be influenced by four emerging themes: professional culture and values, contextual factors, knowledge and understanding of PCC and individual factors. These results provide an insight into the competing agendas involved in implementing PCC education in both the university and clinical component of audiology programmes. The findings can play a role in refining and building the evidence-base for teaching and facilitating patient-centred audiological care in future audiologists.

Does posterior cingulate hypometabolism result from disconnection or local pathology across preclinical and clinical stages of Alzheimer's disease?

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Teipel, Stefan [University of Rostock, Department of Psychosomatic Medicine, Rostock (Germany); DZNE, German Center for Neurodegenerative Diseases, Rostock (Germany); Alzheimer' s Disease Neuroimaging Initiative (United States); Grothe, Michel J. [DZNE, German Center for Neurodegenerative Diseases, Rostock (Germany); Alzheimer' s Disease Neuroimaging Initiative (United States)

2016-03-15

Posterior cingulate cortex (PCC) hypometabolism as measured by FDG PET is an indicator of Alzheimer's disease (AD) in prodromal stages, such as in mild cognitive impairment (MCI), and has been found to be closely associated with hippocampus atrophy in AD dementia.We studied the effects of local and remote atrophy and of local amyloid load on the PCC metabolic signal in patients with different preclinical and clinical stages of AD. We determined the volume of the hippocampus and PCC grey matter based on volumetric MRI scans, PCC amyloid load based on AV45 PET, and PCC metabolism based on FDG PET in 667 subjects participating in the Alzheimer's Disease Neuroimaging Initiative spanning the range from cognitively normal ageing through prodromal AD to AD dementia. In cognitively normal individuals and those with early MCI, PCC hypometabolism was exclusively associated with hippocampus atrophy, whereas in subjects with late MCI it was associated with both local and remote effects of atrophy as well as local amyloid load. In subjects with AD dementia, PCC hypometabolism was exclusively related to local atrophy. Our findings suggest that the effects of remote pathology on PCC hypometabolism decrease and the effects of local pathology increase from preclinical to clinical stages of AD, consistent with a progressive disconnection of the PCC from downstream cortical and subcortical brain regions. (orig.)

Does posterior cingulate hypometabolism result from disconnection or local pathology across preclinical and clinical stages of Alzheimer's disease?

International Nuclear Information System (INIS)

Teipel, Stefan; Grothe, Michel J.

2016-01-01

Posterior cingulate cortex (PCC) hypometabolism as measured by FDG PET is an indicator of Alzheimer's disease (AD) in prodromal stages, such as in mild cognitive impairment (MCI), and has been found to be closely associated with hippocampus atrophy in AD dementia.We studied the effects of local and remote atrophy and of local amyloid load on the PCC metabolic signal in patients with different preclinical and clinical stages of AD. We determined the volume of the hippocampus and PCC grey matter based on volumetric MRI scans, PCC amyloid load based on AV45 PET, and PCC metabolism based on FDG PET in 667 subjects participating in the Alzheimer's Disease Neuroimaging Initiative spanning the range from cognitively normal ageing through prodromal AD to AD dementia. In cognitively normal individuals and those with early MCI, PCC hypometabolism was exclusively associated with hippocampus atrophy, whereas in subjects with late MCI it was associated with both local and remote effects of atrophy as well as local amyloid load. In subjects with AD dementia, PCC hypometabolism was exclusively related to local atrophy. Our findings suggest that the effects of remote pathology on PCC hypometabolism decrease and the effects of local pathology increase from preclinical to clinical stages of AD, consistent with a progressive disconnection of the PCC from downstream cortical and subcortical brain regions. (orig.)

Parental perspectives on the awareness and delivery of preconception care.

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Poels, M; Koster, M P H; Franx, A; van Stel, H F

2017-09-26

The attention for Preconception Care (PCC) has grown substantially in recent years, yet the implementation of PCC appears challenging as uptake rates remain low. The objective of this study was to assess parental perspectives on how PCC should be provided. Recruitment of participants took place among couples who received antenatal care at a Dutch community midwifery practice. Between June and September 2014, five focus group sessions were held with 29 women and one focus group session with 5 men. Thematic analysis was conducted using NVivo 10 software. Participants were generally unfamiliar with the concept of PCC. It was proposed to raise awareness by means of a promotional campaign, stipulating that PCC is suited for every couple with a (future) child wish. Suggestions were made to display marketing materials in both formal and informal (local community) settings. Addressing existing social networks and raising social dialogue was expected to be most efficient. It was recommended to make PCC more accessible by offering multiple forms and to involve male partners. Opportunistic offering PCC by healthcare providers was considered more acceptable when the subject was deliberately raised, for example while discussing contraceptives, lifestyle risks or drug prescriptions. GP's or midwifes were regarded the most suitable PCC providers, however provider characteristics such as experience, empathy and communication skills were considered more important. This study showed that from the parental perspective it is recommended to address every couple with a (future) child wish by means of enlarging the awareness and accessibility of PCC. In order to enlarge the awareness, it is recommended to address social networks, to raise the social dialogue and to conduct promotional campaigns regarding PCC. In order to improve the accessibility of PCC, it was suggested to simultaneously offer multiple forms: group sessions, individual consultations, walk-in-hours and online sessions

The photosynthetic bacteria Rhodobacter capsulatus and Synechocystis sp. PCC 6803 as new hosts for cyclic plant triterpene biosynthesis.

Directory of Open Access Journals (Sweden)

Anita Loeschcke

Full Text Available Cyclic triterpenes constitute one of the most diverse groups of plant natural products. Besides the intriguing biochemistry of their biosynthetic pathways, plant triterpenes exhibit versatile bioactivities, including antimicrobial effects against plant and human pathogens. While prokaryotes have been extensively used for the heterologous production of other classes of terpenes, the synthesis of cyclic triterpenes, which inherently includes the two-step catalytic formation of the universal linear precursor 2,3-oxidosqualene, is still a major challenge. We thus explored the suitability of the metabolically versatile photosynthetic α-proteobacterium Rhodobacter capsulatus SB1003 and cyanobacterium Synechocystis sp. PCC 6803 as alternative hosts for biosynthesis of cyclic plant triterpenes. Therefore, 2,3-oxidosqualene production was implemented and subsequently combined with different cyclization reactions catalyzed by the representative oxidosqualene cyclases CAS1 (cycloartenol synthase, LUP1 (lupeol synthase, THAS1 (thalianol synthase and MRN1 (marneral synthase derived from model plant Arabidopsis thaliana. While successful accumulation of 2,3-oxidosqualene could be detected by LC-MS analysis in both hosts, cyclase expression resulted in differential production profiles. CAS1 catalyzed conversion to only cycloartenol, but expression of LUP1 yielded lupeol and a triterpenoid matching an oxidation product of lupeol, in both hosts. In contrast, THAS1 expression did not lead to cyclic product formation in either host, whereas MRN1-dependent production of marnerol and hydroxymarnerol was observed in Synechocystis but not in R. capsulatus. Our findings thus indicate that 2,3-oxidosqualene cyclization in heterologous phototrophic bacteria is basically feasible but efficient conversion depends on both the respective cyclase enzyme and individual host properties. Therefore, photosynthetic α-proteo- and cyanobacteria are promising alternative candidates

Finding novel relationships with integrated gene-gene association network analysis of Synechocystis sp. PCC 6803 using species-independent text-mining.

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Kreula, Sanna M; Kaewphan, Suwisa; Ginter, Filip; Jones, Patrik R

2018-01-01

The increasing move towards open access full-text scientific literature enhances our ability to utilize advanced text-mining methods to construct information-rich networks that no human will be able to grasp simply from 'reading the literature'. The utility of text-mining for well-studied species is obvious though the utility for less studied species, or those with no prior track-record at all, is not clear. Here we present a concept for how advanced text-mining can be used to create information-rich networks even for less well studied species and apply it to generate an open-access gene-gene association network resource for Synechocystis sp. PCC 6803, a representative model organism for cyanobacteria and first case-study for the methodology. By merging the text-mining network with networks generated from species-specific experimental data, network integration was used to enhance the accuracy of predicting novel interactions that are biologically relevant. A rule-based algorithm (filter) was constructed in order to automate the search for novel candidate genes with a high degree of likely association to known target genes by (1) ignoring established relationships from the existing literature, as they are already 'known', and (2) demanding multiple independent evidences for every novel and potentially relevant relationship. Using selected case studies, we demonstrate the utility of the network resource and filter to ( i ) discover novel candidate associations between different genes or proteins in the network, and ( ii ) rapidly evaluate the potential role of any one particular gene or protein. The full network is provided as an open-source resource.

Structure-Function, Stability, and Chemical Modification of the Cyanobacterial Cytochrome b6f Complex from Nostoc sp. PCC 7120*

Science.gov (United States)

Baniulis, Danas; Yamashita, Eiki; Whitelegge, Julian P.; Zatsman, Anna I.; Hendrich, Michael P.; Hasan, S. Saif; Ryan, Christopher M.; Cramer, William A.

2009-01-01

The crystal structure of the cyanobacterial cytochrome b6f complex has previously been solved to 3.0-Å resolution using the thermophilic Mastigocladus laminosus whose genome has not been sequenced. Several unicellular cyanobacteria, whose genomes have been sequenced and are tractable for mutagenesis, do not yield b6f complex in an intact dimeric state with significant electron transport activity. The genome of Nostoc sp. PCC 7120 has been sequenced and is closer phylogenetically to M. laminosus than are unicellular cyanobacteria. The amino acid sequences of the large core subunits and four small peripheral subunits of Nostoc are 88 and 80% identical to those in the M. laminosus b6f complex. Purified b6f complex from Nostoc has a stable dimeric structure, eight subunits with masses similar to those of M. laminosus, and comparable electron transport activity. The crystal structure of the native b6f complex, determined to a resolution of 3.0Å (PDB id: 2ZT9), is almost identical to that of M. laminosus. Two unique aspects of the Nostoc complex are: (i) a dominant conformation of heme bp that is rotated 180° about the α- and γ-meso carbon axis relative to the orientation in the M. laminosus complex and (ii) acetylation of the Rieske iron-sulfur protein (PetC) at the N terminus, a post-translational modification unprecedented in cyanobacterial membrane and electron transport proteins, and in polypeptides of cytochrome bc complexes from any source. The high spin electronic character of the unique heme cn is similar to that previously found in the b6f complex from other sources. PMID:19189962

The affect of the space environment on the survival of Halorubrum chaoviator and Synechococcus (Nägeli): data from the Space Experiment OSMO on EXPOSE-R

Science.gov (United States)

Mancinelli, R. L.

2015-01-01

We have shown using ESA's Biopan facility flown in Earth orbit that when exposed to the space environment for 2 weeks the survival rate of Synechococcus (Nägeli), a halophilic cyanobacterium isolated from the evaporitic gypsum-halite crusts that form along the marine intertidal, and Halorubrum chaoviator a member of the Halobacteriaceae isolated from an evaporitic NaCl crystal obtained from a salt evaporation pond, were higher than all other test organisms except Bacillus spores. These results led to the EXPOSE-R mission to extend and refine these experiments as part of the experimental package for the external platform space exposure facility on the ISS. The experiment was flown in February 2009 and the organisms were exposed to low-Earth orbit for nearly 2 years. Samples were either exposed to solar ultraviolet (UV)-radiation (λ > 110 nm or λ > 200 nm, cosmic radiation (dosage range 225-320 mGy), or kept in darkness shielded from solar UV-radiation. Half of each of the UV-radiation exposed samples and dark samples were exposed to space vacuum and half kept at 105 pascals in argon. Duplicate samples were kept in the laboratory to serve as unexposed controls. Ground simulation control experiments were also performed. After retrieval, organism viability was tested using Molecular Probes Live-Dead Bac-Lite stain and by their reproduction capability. Samples kept in the dark, but exposed to space vacuum had a 90 +/- 5% survival rate compared to the ground controls. Samples exposed to full UV-radiation for over a year were bleached and although results from Molecular Probes Live-Dead stain suggested ~10% survival, the data indicate that no survival was detected using cell growth and division using the most probable number method. Those samples exposed to attenuated UV-radiation exhibited limited survival. Results from of this study are relevant to understanding adaptation and evolution of life, the future of life beyond earth, the potential for interplanetary

Coupling of the spatial dynamic of picoplankton and nanoflagellate grazing pressure and carbon flow of the microbial food web in the subtropical pelagic continental shelf ecosystem

Science.gov (United States)

Chiang, K.-P.; Tsai, A.-Y.; Tsai, P.-J.; Gong, G.-C.; Tsai, S.-F.

2013-01-01

In order to investigate the mechanism of spatial dynamics of picoplankton community (bacteria and Synechococcus spp.) and estimate the carbon flux of the microbial food web in the oligotrophic Taiwan Warm Current Water of subtropical marine pelagic ecosystem, we conducted size-fractionation experiments in five cruises by the R/V Ocean Research II during the summers of 2010 and 2011 in the southern East China Sea. We carried out culture experiments using surface water which, according to a temperature-salinity (T-S) diagram, is characterized as oligotrophic Taiwan Current Warm Water. We found a negative correlation bettween bacteria growth rate and temperature, indicating that the active growth of heterotrophic bacteria might be induced by nutrients lifted from deep layer by cold upwelling water. This finding suggests that the area we studied was a bottom-up control pelagic ecosystem. We suggest that the microbial food web of an oligotrophic ecosystem may be changed from top-down control to resource supply (bottom-up control) when a physical force brings nutrient into the oligotrophic ecosystem. Upwelling brings nutrient-rich water to euphotic zone and promotes bacteria growth, increasing the picoplankton biomass which increased the consumption rate of nanoflagellate. The net growth rate (growth rate-grazing rate) becomes negative when the densities of bacteria and Synechococcus spp. are lower than the threshold values. The interaction between growth and grazing will limit the abundances of bacteria (105-106 cells mL-1 and Synechococcus spp. (104-105 cells mL-1) within a narrow range, forming a predator-prey eddy. Meanwhile, 62% of bacteria production and 55% of Synechococcus spp. production are transported to higher trophic level (nanoflagellate), though the cascade effect might cause an underestimation of both percentages of transported carbon. Based on the increasing number of sizes we found in the size-fractionation experiments, we estimated that the predation

Thrombotic safety of prothrombin complex concentrate (Beriplex P/N) for dabigatran reversal in a rabbit model.

Science.gov (United States)

Herzog, Eva; Kaspereit, Franz J; Krege, Wilfried; Doerr, Baerbel; van Ryn, Joanne; Dickneite, Gerhard; Pragst, Ingo

2014-09-01

In vivo animal data have shown prothrombin complex concentrate (PCC) to be effective in preventing bleeding induced by excessive plasma levels of the direct thrombin inhibitor dabigatran. This animal model study was designed to determine the risk of thrombosis associated with administration of a PCC (Beriplex P/N) to reverse dabigatran-induced bleeding. Anesthetized rabbits were treated with initial 0, 75, 200 or 450 μg kg(-1) dabigatran boluses followed by continuous infusions to maintain elevated plasma dabigatran levels. At 15 min after the start of dabigatran administration, PCC doses of 0, 50 or 300 IU kg(-1) were administered. Thereafter, coagulation in an arteriovenous (AV) shunt was evaluated and histopathologic examination for thrombotic changes performed. Venous thrombosis was also assessed in a modified Wessler model. At the suprapharmacologic dose of 300 IU kg(-1), PCC increased thrombus weight during AV shunting, but this effect could be prevented by dabigatran at all tested doses. AV shunt occlusion after PCC administration was delayed by 75 μg kg(-1) dabigatran and abolished by progressively higher dabigatran doses. High-dose treatment with 300 IU kg(-1) PCC resulted in histologically evident low-grade pulmonary thrombi; however, that effect could be blocked by dabigatran in a dose-dependent manner (p=0.034). In rabbits treated with high-dose PCC, dabigatran inhibited thrombus formation during venous stasis. PCC effectively reversed dabigatran-induced bleeding. In this animal study, thrombosis after PCC administration could be prevented in the presence of dabigatran. PCC reversed dabigatran-induced excessive bleeding while retaining protective anticoagulatory activity of dabigatran. Copyright © 2014. Published by Elsevier Ltd.

Caracterización de las comunidades de acridios (Orthoptera: Acridoidea del partido de Benito Juárez, sudeste de la provincia de Buenos Aires, Argentina Grasshopper (Orthoptera: Acridoidea community structure in Benito Juárez county, in outhern Buenos Aires province, Argentina

Directory of Open Access Journals (Sweden)

María Laura de Wysiecki

2004-12-01

Full Text Available Se analizó la riqueza, densidad, constancia y distribución de especies de acridios, en distintas comunidades vegetales (1997-2002 en el partido de Benito Juárez, sudeste de la provincia de Buenos Aires. Las comunidades vegetales se categorizaron en pastizales nativos, comunidades halófilas, pasturas sin disturbio, pasturas con moderado disturbio y pasturas con alto disturbio. En total se registraron 23 especies de acridios. Los melanoplinos dominaron en casi todas las comunidades vegetales, excepto en las halófilas que se caracterizaron por la presencia de un acridino, Covasacris pallidinota (Bruner. La riqueza de especies promedio por sitio por año, varió entre 2,10 ± 0,60 especies en las pasturas con moderado disturbio y 6,20 ± 0,58 especies en las comunidades halófilas. La riqueza de especies acumulada fue de 17 en los pastizales nativos, 14 en las comunidades halófilas, 19 en las pasturas sin disturbio, 18 en las pasturas con moderado disturbio y 14 en las pasturas con alto disturbio. La densidad promedio de acridios fue máxima en el 2001 y 2002. Dichroplus pratensis Bruner y Dichroplus elongatus Giglio-Tos dominaron en los pastizales nativos y en las pasturas con alto disturbio, C. pallidinota en las comunidades halófilas, D. elongatus y Scotussa lemniscata (Stål en las pasturas sin disturbio y en las pasturas con moderado disturbio. La estructura taxonómica de las comunidades de acridios fue constante en los pastizales nativos, las comunidades halófilas y las pasturas. Hubo pocas especies de amplia distribución e intermedias y las raras fueron las más numerosas. De las 23 especies registradas en todos los sitios, D. elongatus fue la única de amplia distribución. Históricamente, para la zona de estudio, Dichroplus maculipennis (Blanch fue señalada como la especie dominante. Sin embargo, nuestros resultados sugieren que en la actualidad la especie dominante es D. elongatus. Si bien resulta imposible conocer las causas

Calibration curves for biological dosimetry by drug-induced prematurely condensed chromosomes in human lymphocytes

International Nuclear Information System (INIS)

Kang, C. M.; Chung, H. C.; Cho, C. K.

2002-01-01

To develop the cytogenetic tool to detect chromosome damages after high dose exposure with 60 Coγ- rays, dose-response curves were measured for induction of prematurely condensed chromosomes (PCC) in peripheral lymphocytes. Blood was obtained from 10 different healthy donors, and given okadaic acid (OA) 500nM in cultured lymphocytes 1h after radiation exposure. Cells were analyzed by the frequencies of OA-induced PCC rings because it is difficult to obtain mitotic chromosomes using a conventional chromosome aberration (CA). PCC-rings were scored in cells exposed in the dose range of 0.2-16Gy. The frequency of the cells with PCC and the dose-response relationship for the yield of PCC rings were examined in the irradiated lymphocytes. The yield of PCC-rings increased with dose dependent-manner up to 16Gy. The observed dose-effect relationship for the percentage of cells with PCC-rings was calculated by linear-quadratic model. This technique can be applied to biological dosimetry of radiation exposures involving whole body irradiation to allow damaged chromosomes to be detected with great sensitivity. Detection of okadaic acid-induced PCC rings is a useful method up to 16Gy or more doses in estimating the absorbed doses of victims after high dose exposure. Calibration curves described in this paper will be used in our laboratory for biological dosimetry by PCC-ring after a high dose exposure

Molecular mechanism of endocrine system impairment by 17α-methyltestosterone in gynogenic Pengze crucian carp offspring.

Science.gov (United States)

Zheng, Yao; Chen, Jiazhang; Liu, Yan; Gao, Jiancao; Yang, Yanping; Zhang, Yingying; Bing, Xuwen; Gao, Zexia; Liang, Hongwei; Wang, Zaizhao

2016-06-01

The effects of synthetic androgen 17α-methyltestosterone (MT) on endocrine impairment were examined in crucian carp. Immature 7-month old mono-female Pengze crucian carp (Pcc) F2 offspring were exposed to 50 and 100 μg/L of MT (week 2, 4, and 8). Gonadosomatic index, hepatosomatic index and intestine weight altered considerably and oocyte development was repressed. In the treatment groups, ovarian 11-ketotestosterone decreased, whereas 17β-estradiol and testosterone increased, and ovarian aromatase activities increased at week 4. However, in the brain tissue, those values significantly decreased. Quantitative RT-PCR analysis demonstrated changes in steroid receptor genes and upregulation of steroidogenic genes (Pcc-3bhsd, Pcc-11bhsd2 Pcc-cyp11a1), while the other three steroidogenic genes (Pcc-cyp17a1, Pcc-cyp19a1a and Pcc-star) decreased from week 4 to week 8. Ovarian, hepatic Pcc-vtg B and vitellogenin concentration increased in both 50 and 100 μg/L of MT exposure groups. This study adds further information regarding the effects of androgens on the development of previtellogenic oocytes, which suggests that MT could directly target estrogen signaling pathway, or indirectly affect steroidogenesis and vitellogenesis. Copyright © 2016 Elsevier Inc. All rights reserved.

Involvement of posterior cingulate cortex in ketamine-induced psychosis relevant behaviors in rats.

Science.gov (United States)

Ma, Jingyi; Leung, L Stan

2018-02-15

The involvement of posterior cingulate cortex (PCC) on ketamine-induced psychosis relevant behaviors was investigated in rats. Bilateral infusion of muscimol, a GABA A receptor agonist, into the PCC significantly antagonized ketamine-induced deficit in prepulse inhibition of a startle reflex (PPI), deficit in gating of hippocampal auditory evoked potentials, and behavioral hyperlocomotion in a dose dependent manner. Local infusion of ketamine directly into the PCC also induced a PPI deficit. Systemic injection of ketamine (3mg/kg,s.c.) induced an increase in power of electrographic activity in the gamma band (30-100Hz) in both the PCC and the hippocampus; peak theta (4-10Hz) power was not significantly altered, but peak theta frequency was increased by ketamine. In order to exclude volume conduction from the hippocampus to PCC, inactivation of the hippocampus was made by local infusion of muscimol into the hippocampus prior to ketamine administration. Muscimol in the hippocampus effectively blocked ketamine-induced increase of gamma power in the hippocampus but not in the PCC, suggesting independent generation of gamma waves in PCC and hippocampus. It is suggested that the PCC is part of the brain network mediating ketamine-induced psychosis related behaviors. Copyright © 2017 Elsevier B.V. All rights reserved.

Premature chromosome condensation following x irradiation of mammalian cells: expression time and dose-response

International Nuclear Information System (INIS)

Griffiths, T.D.; Carpenter, J.G.

1979-01-01

Premature chromosome condensation (PCC) in Chinese hamster ovary (CHO) cells following exposure to 300-kVp x rays was first detected in the mitosis that followed the second postirradiation S phase. Thus, cells irradiated in G1 first expressed PCC at the second postirradiation mitosis while cells irradiated in G2 did not express PCC until the third postirradiation mitosis. Cells irradiated in the S phase expressed PCC at the second postirradiation mitosis with a frequency that was related to the position of the cells in the S phase at the time of exposure, cells in the first half of the S phase (at the time of exposure) showing a higher frequency than cells positioned in the second half. Thus, DNA replication during the first postirradiation S phase may be involved in the processing of lesions that eventually give rise to PCC. For cells in G1 at the time of exposure, the D/sub o/ for PCC expression at the second postirradiation mitosis was around 825 rad, indicating that PCC may play only a minor role in x-ray-induced cell killing. Autoradiographic analysis indicated approximately 50% of the PCC patches scored were replicating DNA at the time condensation was attempted. Daughter cells derived from such cells would suffer loss of genetic material

A dose-effect curve of premature condensation chromosome ring in lymphocytes of human peripheral blood exposed to high dose of 60Co γ-rays in vitro

International Nuclear Information System (INIS)

Yao Bo; Li Yufang; Liu Guangxian; Huang Shan; Jiang Benrong; Ai Huisheng

2009-01-01

Objective: To establish a dose-effect curve of premature condensation chromosome ring (PCC-R) in lymphocytes of human peripheral blood after exposed to high doses of γ-rays. Methods: Peripheral blood samples was drawn from three healthy individuals, and exposed to 60 Co γ-rays with doses between 0 and 30 Gy. The frequencies of PCC-R in premature condensation chromosome (PCC) cells obtained by Okadaic acid (OA) induction were calculated, and a dose-effect curve was fitted. Results: PCC index tapered with dose. Frequencies of PCC-R per cell increased until 20 Gy, and then saturation was observed. The results were fitted to a lineal model up to 20 Gy: y=-0.020 + 0.052D, where y was the frequencies of PCC-R per cell, D was the radiation dose(Gy). Conclusions: The highest dose could be estimated is 20 Gy by the dose-effect curve established with PCC-R method. Its utility and validity will be verified in the future application of radiation accident. (authors)

The influence of nanoflagellates on the spatial variety of picoplankton and the carbon flow of the microbial food web in the oligotrophic subtropical pelagic continental shelf ecosystem

Science.gov (United States)

Chiang, Kuo-Ping; Tsai, An-Yi; Tsai, Pei-Jung; Gong, Gwo-Ching; Huang, Bang-Qin; Tsai, Sheng-Fang

2014-06-01

To investigate the mechanism of the spatial dynamics of picoplankton community (bacteria and Synechococcus spp.) and to estimate the carbon flux of the microbial food web in the oligotrophic Taiwan Warm Current Water of the subtropical marine pelagic ecosystem, we conducted size-fractionation experiments during five cruises by the R/V Ocean Research II during the summers of 2010 and 2011 in the southern East China Sea. We carried out culture experiments using surface water, which according to a temperature-salinity (T-S) diagram, is characterized as oligotrophic Taiwan Current Warm Water. We found a negative correlation between bacteria growth rate and temperature, and another negative correlation between nitrate and temperature indicating that the active growth of heterotrophic bacteria might be induced by nutrients lifted from a deep layer by cold upwelling water. This finding suggests that the area we studied was a bottom-up control pelagic ecosystem. Upwelling brings nutrient-rich water to the euphotic zone and promotes bacterial growth, resulting in increased picoplankton biomass, which increases the consumption rate of nanoflagellates. The net growth rate (growth rate-grazing rate) becomes negative when the densities of bacteria and Synechococcus spp. are lower than the threshold values. The interaction between growth and grazing will limit the abundance of bacteria (105-106 cells ml-1) and Synechococcus spp. (104-105 cells ml-1) within a narrow range. Meanwhile, 61% of bacteria production and 54% of Synechococcus spp. production are transported to a higher trophic level (nanoflagellate), though the cascade effect might cause an underestimation of both percentages of transported carbon. Based on the successive size-fractionation experiments, we estimated that the predation values were underestimated and that the diet of nanoflagellates is composed of 64% bacteria and 36% Synechococcus spp.

Mobile acoustic telemetry data - Lingcod Stock Enhancement: ecological interactions, fishery contributions, and life history

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Lingcod (Ophiodon elongatus) populations along the West Coast of North America have recovered from overfishing, but the status of genetically distinct lingcod in...

Tag effect data - Lingcod Stock Enhancement: ecological interactions, fishery contributions, and life history

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Lingcod (Ophiodon elongatus) populations along the West Coast of North America have recovered from overfishing, but the status of genetically distinct lingcod in...

Why do women not use preconception care? A systematic review on barriers and facilitators.

NARCIS (Netherlands)

Poels, M.; Koster, M.P.H.; Boeije, H.R.; Franx, A.; Stel, H.F.

2016-01-01

Importance: Preconception care (PCC) has the potential to optimize pregnancy outcomes. However, awareness of PCC among the target population is generally limited, and the use of PCC remains low. Importance: The objective of this studywas to reviewthe literature onwomen's perceptions regarding

Co-ordination of NDH and Cup proteins in CO2 uptake in cyanobacterium Synechocystis sp. PCC 6803.

Science.gov (United States)

Han, Xunling; Sun, Nan; Xu, Min; Mi, Hualing

2017-06-01

High and low affinity CO2-uptake systems containing CupA (NDH-1MS) and CupB (NDH-1MS'), respectively, have been identified in Synechocystis sp. PCC 6803, but it is yet unknown how the complexes function in CO2 uptake. In this work, we found that deletion of cupB significantly lowered the growth of cells, and deletion of both cupA and cupB seriously suppressed the growth below pH 7.0 even under 3% CO2. The rate of photosynthetic oxygen evolution was decreased slightly by deletion of cupA but significantly by deletion of cupB and more severely by deletion of both cupA and cupB, especially in response to changed pH conditions under 3% CO2. Furthermore, we found that assembly of CupB into NDH-1MS' was dependent on NdhD4 and NdhF4. NDH-1MS' was not affected in the NDH-1MS-degradation mutant and NDH-1MS was not affected in the NDH-1MS'-degradation mutants, indicating the existence of independent CO2-uptake systems under high CO2 conditions. The light-induced proton gradient across thylakoid membranes was significantly inhibited in ndhD-deletion mutants, suggesting that NdhDs functions in proton pumping. The carbonic anhydrase activity was suppressed partly in the cupA- or cupB-deletion mutant but severely in the mutant with both cupA and cupB deletion, indicating that CupA and CupB function in conversion of CO2 to HCO3-. In turn, deletion of cup genes lowered the transthylakoid membrane proton gradient and deletion of ndhDs decreased the CO2 hydration. Our results suggest that NDH-1M provides an alkaline region to activate Cup proteins involved in CO2 uptake. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Four-factor prothrombin complex concentrate improves thrombin generation and prothrombin time in patients with bleeding complications related to rivaroxaban: a single-center pilot trial.

Science.gov (United States)

Schenk, Bettina; Goerke, Stephanie; Beer, Ronny; Helbok, Raimund; Fries, Dietmar; Bachler, Mirjam

2018-01-01

Direct oral anticoagulants (DOACs) pose a great challenge for physicians in life-threatening bleeding events. The aim of this study was to test the efficacy of reversing the DOAC rivaroxaban using four-factor PCC (prothrombin complex concentrate), a non-specific reversing agent. Patients with life-threatening bleeding events during rivaroxaban treatment were included and administered 25 U kg -1 of PCC. Blood samples were collected immediately prior to as well as after PCC treatment at predefined time intervals. The primary endpoint was defined as the difference in thrombin generation (TG) parameters ETP (endogenous thrombin potential) and C max (peak thrombin generation) prior to and ten minutes subsequent to PCC treatment. Thirteen patients, of whom the majority suffered from intra-cranial haemorrhage (ICH) or subdural haemorrhage (SDH), were included and administered PCC. The results show that the ETP (TG) significantly ( p  = 0.001) improved by 68% and C max (TG) by 54% (p = 0.001) during PCC treatment. In addition, the Quick value (prothrombin time: Quick PT ) significantly improved by 28% and the activated partial thromboplastin time (aPTT) was decreased by 7% ten minutes after PCC administration. C max was reduced at baseline, but not ETP, aPTT or Quick PT . Lag time until initiation (TG, t lag ), thromboelastometry clotting time (CT EXTEM ) and time to peak (TG, t max ) correlated best with measured rivaroxaban levels and were out of normal ranges at baseline, but did not improve after PCC administration. In 77% of the patients bleeding (ICH/SDH-progression) ceased following PCC administration. During the study three participants passed away due to other complications not related to PCC treatment. The possibility of thrombosis formation was also evaluated seven days after administering PCC and no thromboses were found. This study shows that use of PCC improved ETP, C max, Quick PT and aPTT. However, of these parameters, only C max was reduced at the

Picophytoplankton as Tracers of Environmental Forcing in a Tropical Monsoonal Bay.

Science.gov (United States)

Mitbavkar, Smita; Patil, Jagadish S; Rajaneesh, K M

2015-10-01

In order to better understand the picophytoplankton (PP) dynamics in tropical monsoon influenced coastal regions, samples were collected daily (June-September 2008: monsoon, December 2008: post-monsoon and April 2009: pre-monsoon) from a fixed station in Dona Paula Bay, India. Eight PP abundance peaks comprising Prochlorococcus-like cells, picoeukaryotes, and three groups of Synechococcus occurred. The chlorophyll biomass and PP abundance were negatively influenced by reduced solar radiation, salinity and water transparency due to precipitation and positively influenced by the stabilized waters during precipitation break/non-monsoon periods. Responses to environmental conditions differed with PP groups, wherein the presence of Synechococcus-PEI (phycoerythrin) throughout the year suggested its ability to tolerate salinity and temperature variations and low light conditions. Synechococcus-PEII appearance toward monsoon end and non-monsoon during high water transparency suggests its tidal advection from offshore waters. Dominance of Synechococcus-PC (phycocyanin) at intermediate salinities under low water transparency during MON and high salinities in PrM coinciding with high nitrate concentrations implies a greater influence of light quality or nutrients. Cyanobacteria and not picoeukaryotes were the dominant picophytoplankton in terms of numbers as well as biomass. This study suggests that PP could be used as tracers of environmental forcing driven by tides and freshwater influx and also highlights the importance of high-frequency samplings in dynamic coastal regions through which transient responses can be captured.

Patient-Centered Care; Physicians’ View of Obstacles against and Ideas for Implementation

Directory of Open Access Journals (Sweden)

Faisal Abdullatif Alnasir

2016-04-01

Full Text Available To implement proper family medicine practice and to get the best of it, the concept of patient-centered care (PCC has to be put into use. Studies have found that one of the most important advantages of PCC is the increase in the patients' quality of life. PCC has been recognized as a marker of quality in health service delivery with its improvement. However, the physicians’ belief is essential for its implementation. A cross-sectional study was done to find out what family physicians think of PCC and what they believe are the obstacles that block from its use in Bahrain. Twenty-eight family physicians (FPs working in the primary health care centers were arbitrarily culled from a pool of doctors. To all a pre-designed questionnaire was sent that contained three parts; demographic information, type of facilities that they work and whether it is promoting PCC practice and the last was concerned with the physicians’ view about the barrier against its implementation and what they cerebrate that could avail in promoting it. The results showed that the majority of the participants were family physicians working in governmental health centers. More than 85% knew the congruous definition of PCC and 96.4% thought that the most common barrier for not implementing PCC approach is the time constraint while almost 93% thought that the short duration of time of the consultation is another impediment for implementing PCC. Withal, 57.1% and 53.6% of FPs thought that language and the doctor’s communication skills are other barriers respectively. Since the ultimate aim of provision of health care in any country is the optimal health of the population and since PCC practice could fortify and avail in achieving that goal, it is recommended that policy makers and health authorities are required to abstract all obstacles that works against implementing PCC and change the work environment in order to make it facile for the practitioners to apply PCC practice

Comparison of 3-Factor Prothrombin Complex Concentrate and Low-Dose Recombinant Factor VIIa for Warfarin Reversal

OpenAIRE

Chapman, Scott A; Irwin, Eric D; Abou-Karam, Nada M; Rupnow, Nichole M; Hutson, Katherine E; Vespa, Jeffrey; Roach, Robert M

2014-01-01

Introduction Prothrombin complex concentrate (PCC) and recombinant Factor VIIa (rFVIIa) have been used for emergent reversal of warfarin anticoagulation. Few clinical studies have compared these agents in warfarin reversal. We compared warfarin reversal in patients who received either 3 factor PCC (PCC3) or low-dose rFVIIa (LDrFVIIa) for reversal of warfarin anticoagulation. Methods Data were collected from medical charts of patients who received at least one dose of PCC3 (20 units/kg) or LDr...

Evaluation of Precast Portland Cement Concrete Panels for Airfield Pavement Repairs

Science.gov (United States)

2015-05-01

quality PCC over a 152-mm compacted well-graded limestone base, over compacted sandy, low-plasticity clay . Measured PCC material strengths of field...by 20 ft by 14 in. The PCC was constructed on a 6-in.-thick, well-graded limestone base over a sandy, low-plasticity clay subgrade. The PCC had an...Ratio of the second stress invariant on the tensile to compressive meridian, Kc 0.667 0.667 0.667 Viscosity parameter, µ 0 0 0 Fracture

Person-centred care in nurse-led outpatient rheumatology clinics: Conceptualization and initial development of a measurement instrument.

Science.gov (United States)

Bala, Sidona-Valentina; Forslind, Kristina; Fridlund, Bengt; Samuelson, Karin; Svensson, Björn; Hagell, Peter

2018-06-01

Person-centred care (PCC) is considered a key component of effective illness management and high-quality care. However, the PCC concept is underdeveloped in outpatient care. In rheumatology, PCC is considered an unmet need and its further development and evaluation is of high priority. The aim of the present study was to conceptualize and operationalize PCC, in order to develop an instrument for measuring patient-perceived PCC in nurse-led outpatient rheumatology clinics. A conceptual outpatient PCC framework was developed, based on the experiences of people with rheumatoid arthritis (RA), person-centredness principles and existing PCC frameworks. The resulting framework was operationalized into the PCC instrument for outpatient care in rheumatology (PCCoc/rheum), which was tested for acceptability and content validity among 50 individuals with RA attending a nurse-led outpatient clinic. The conceptual framework focuses on the meeting between the person with RA and the nurse, and comprises five interrelated domains: social environment, personalization, shared decision-making, empowerment and communication. Operationalization of the domains into a pool of items generated a preliminary PCCoc/rheum version, which was completed in a mean (standard deviation) of 5.3 (2.5) min. Respondents found items easy to understand (77%) and relevant (93%). The Content Validity Index of the PCCoc/rheum was 0.94 (item level range, 0.87-1.0). About 80% of respondents considered some items redundant. Based on these results, the PCCoc/rheum was revised into a 24-item questionnaire. A conceptual outpatient PCC framework and a 24-item questionnaire intended to measure PCC in nurse-led outpatient rheumatology clinics were developed. The extent to which the questionnaire represents a measurement instrument remains to be tested. Copyright © 2018 John Wiley & Sons, Ltd.

Abnormal resting-state functional connectivity study in unilateral pulsatile tinnitus patients with single etiology: A seed-based functional connectivity study

Energy Technology Data Exchange (ETDEWEB)

Lv, Han [Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing 100050 (China); Neuroradiology Division, Department of Radiology, Stanford University, CA, 94305 (United States); Zhao, Pengfei [Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing 100050 (China); Liu, Zhaohui [Department of Radiology, Beijing Tongren Hospital, Capital Medical University, Beijing, 100730 (China); Li, Rui; Zhang, Ling; Wang, Peng [Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing 100050 (China); Yan, Fei [Department of Radiology, Beijing Tongren Hospital, Capital Medical University, Beijing, 100730 (China); Liu, Liheng [Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing 100050 (China); Wang, Guopeng; Zeng, Rong [Department of Otolaryngology Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing 100050 (China); Li, Ting [Department of Radiology, Beijing Tongren Hospital, Capital Medical University, Beijing, 100730 (China); Dong, Cheng [Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing 100050 (China); Gong, Shusheng, E-mail: gongss@ccmu.edu.cn [Department of Otolaryngology Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing 100050 (China); Wang, Zhenchang, E-mail: cjr.wzhch@vip.163.com [Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing 100050 (China)

2016-11-15

Objective: Previous studies demonstrated altered regional neural activations in several brain areas in patients with pulsatile tinnitus (PT), especially indicating an important role of posterior cingulate cortex (PCC). However, few studies focused on the degree of functional connectivity (FC) of this area in PT patients. In this study, we will compare the FC of PCC in patients affected with this condition and normal controls by using resting-state functional magnetic resonance imaging (fMRI). Methods: Structural and functional MRI data were obtained from 36 unilateral PT patients with single etiology and 36 matched healthy controls. FC feature of the region of interest (PCC) were characterized using a seed-based correlation method with the voxels in the whole-brain. Results: Compared with healthy controls, patients showed significant decreased FC to the right middle temporal gyrus (MTG), right thalamus and bilateral insula. By contrast, PCC demonstrated increased functional connectivity between the precuneus, bilateral inferior parietal lobule and middle occipital gyrus. We also found correlations between the disease duration of PT and FC of PCC-right MTG (r = −0.616, p < 0.001). Conclusions: Unilateral PT patients could have abnormal FC to the PCC bilaterally in the brain. PCC, as a highly integrated brain area, is an example of nucleus that was involved in mediation between different neural networks. It might be a modulation core between visual network and auditory network. The decreased FC of MTG to PCC may indicate a down regulation of activity between PCC and auditory associated brain cortex. Decreased FC between limbic system (bilateral AI) and PCC may reflect the emotional message control in patient group. This study facilitated understanding of the underlying neuropathological process in patients with pulsatile tinnitus.

Abnormal resting-state functional connectivity study in unilateral pulsatile tinnitus patients with single etiology: A seed-based functional connectivity study

International Nuclear Information System (INIS)

Lv, Han; Zhao, Pengfei; Liu, Zhaohui; Li, Rui; Zhang, Ling; Wang, Peng; Yan, Fei; Liu, Liheng; Wang, Guopeng; Zeng, Rong; Li, Ting; Dong, Cheng; Gong, Shusheng; Wang, Zhenchang

2016-01-01

Objective: Previous studies demonstrated altered regional neural activations in several brain areas in patients with pulsatile tinnitus (PT), especially indicating an important role of posterior cingulate cortex (PCC). However, few studies focused on the degree of functional connectivity (FC) of this area in PT patients. In this study, we will compare the FC of PCC in patients affected with this condition and normal controls by using resting-state functional magnetic resonance imaging (fMRI). Methods: Structural and functional MRI data were obtained from 36 unilateral PT patients with single etiology and 36 matched healthy controls. FC feature of the region of interest (PCC) were characterized using a seed-based correlation method with the voxels in the whole-brain. Results: Compared with healthy controls, patients showed significant decreased FC to the right middle temporal gyrus (MTG), right thalamus and bilateral insula. By contrast, PCC demonstrated increased functional connectivity between the precuneus, bilateral inferior parietal lobule and middle occipital gyrus. We also found correlations between the disease duration of PT and FC of PCC-right MTG (r = −0.616, p < 0.001). Conclusions: Unilateral PT patients could have abnormal FC to the PCC bilaterally in the brain. PCC, as a highly integrated brain area, is an example of nucleus that was involved in mediation between different neural networks. It might be a modulation core between visual network and auditory network. The decreased FC of MTG to PCC may indicate a down regulation of activity between PCC and auditory associated brain cortex. Decreased FC between limbic system (bilateral AI) and PCC may reflect the emotional message control in patient group. This study facilitated understanding of the underlying neuropathological process in patients with pulsatile tinnitus.

Protein (Cyanobacteria): 500464022 [PGDBj - Ortholog DB

Lifescience Database Archive (English)

Full Text Available thetical protein Synechococcus sp. WH 7803 MSRQRFRGLYLQNTGHPLCFSFVTYTPQTREQMVACGDLRADEEYFSPVLFDFLLFVSEGILGASPGVAFPFGYDDLAIVASRIRGTGVQHEYLIAINASAWNESKQAVLQQLRDILSRDLWDGARLRRGNDHPSPSE

A dimensional analysis of patient-centered care.

Science.gov (United States)

Hobbs, Jennifer Lynn

2009-01-01

Patient-centered care (PCC) is a poorly conceptualized phenomenon and can indicate anything from soothing room design, emotional support of patients, customization of meals, to support of patient decision making. This inconsistency across the clinical and research literature makes the application of PCC difficult. The objective of this study was to identify dimensions of PCC as found in the literature. A dimensional analysis of PCC was conducted from 69 clinical and research articles published from 2000 to 2006. Coding of the literature for the perspective, context, conditions, process, and consequences of PCC was completed. These codes were used to determine literature selected for inclusion, organize article content, and frame the delineation of PCC. Alleviating vulnerabilities, consisting of both compromised physiological states and threats to individual identity, was constant throughout the literature. Therapeutic engagement was the process sustaining the patient during an illness episode that necessitated service use and involved allocating time, carrying out information practices, knowing the patient, and developing a relationship. This process occurs during nurse-patient interaction, sustained during successive interactions, and reinforced by the information practices of a particular setting. The interaction between nurse and patient is central to the effective study and application of PCC. Appropriate use of PCC can improve study outcomes and measurements by clarifying the variables involved, and PCC holds great promise to frame patient outcome and satisfaction research by analyzing how and with what effect nurses alleviate patient vulnerability. Moreover, consideration of information practices as a critical supporting structure of nurse-patient interaction can be explored.

How to practice person-centred care: A conceptual framework.

Science.gov (United States)

Santana, Maria J; Manalili, Kimberly; Jolley, Rachel J; Zelinsky, Sandra; Quan, Hude; Lu, Mingshan

2018-04-01

Globally, health-care systems and organizations are looking to improve health system performance through the implementation of a person-centred care (PCC) model. While numerous conceptual frameworks for PCC exist, a gap remains in practical guidance on PCC implementation. Based on a narrative review of the PCC literature, a generic conceptual framework was developed in collaboration with a patient partner, which synthesizes evidence, recommendations and best practice from existing frameworks and implementation case studies. The Donabedian model for health-care improvement was used to classify PCC domains into the categories of "Structure," "Process" and "Outcome" for health-care quality improvement. The framework emphasizes the structural domain, which relates to the health-care system or context in which care is delivered, providing the foundation for PCC, and influencing the processes and outcomes of care. Structural domains identified include: the creation of a PCC culture across the continuum of care; co-designing educational programs, as well as health promotion and prevention programs with patients; providing a supportive and accommodating environment; and developing and integrating structures to support health information technology and to measure and monitor PCC performance. Process domains describe the importance of cultivating communication and respectful and compassionate care; engaging patients in managing their care; and integration of care. Outcome domains identified include: access to care and Patient-Reported Outcomes. This conceptual framework provides a step-wise roadmap to guide health-care systems and organizations in the provision PCC across various health-care sectors. © 2017 The Authors Health Expectations published by John Wiley & Sons Ltd.

GP-initiated preconception counselling in a randomised controlled trial does not induce anxiety

NARCIS (Netherlands)

de Jong-Potjer, L. C.; Elsinga, J.; le Cessie, S.; van der Pal-de Bruin, K. M.; Neven, A. Knuistingh; Buitendijk, S. E.; Assendelft, W. J. J.

2006-01-01

BACKGROUND: Preconception counselling (PCC) can reduce adverse pregnancy outcome by addressing risk factors prior to pregnancy. This study explores whether anxiety is induced in women either by the offer of PCC or by participation with GP-initiated PCC. METHODS: Randomised trial of usual care versus

GP-initiated preconception counselling in a randomised controlled trial does not induce anxiety

NARCIS (Netherlands)

Jong-Potjer, L.C. de; Elsinga, J.; Cessie, S. le; Pal-de Bruin, K.M. van der; Knuistingh Neven, A.; Buitendijk, S.E.; Assendelft, W.J.J.

2006-01-01

Background: Preconception counselling (PCC) can reduce adverse pregnancy outcome by addressing risk factors prior to pregnancy. This study explores whether anxiety is induced in women either by the offer of PCC or by participation with GP-initiated PCC. Methods: Randomised trial of usual care versus

Why Do Women Not Use Preconception Care? : A Systematic Review On Barriers And Facilitators

NARCIS (Netherlands)

Poels, Marjolein; Koster, Maria P H; Boeije, Hennie R; Franx, Arie; van Stel, Henk F

2016-01-01

Importance: Preconception care (PCC) has the potential to optimize pregnancy outcomes. However, awareness of PCC among the target population is generally limited, and the use of PCC remains low. Objective: The objective of this study was to review the literature on women's perceptions regarding

Parental perspectives on the awareness and delivery of preconception care

NARCIS (Netherlands)

Poels, M; Koster, M P H; Franx, A; van Stel, H F

2017-01-01

BACKGROUND: The attention for Preconception Care (PCC) has grown substantially in recent years, yet the implementation of PCC appears challenging as uptake rates remain low. The objective of this study was to assess parental perspectives on how PCC should be provided. METHODS: Recruitment of

GP-initiated preconception counselling in a randomised controlled trial does not induce anxiety

Directory of Open Access Journals (Sweden)

Neven A Knuistingh

2006-11-01

Full Text Available Abstract Background Preconception counselling (PCC can reduce adverse pregnancy outcome by addressing risk factors prior to pregnancy. This study explores whether anxiety is induced in women either by the offer of PCC or by participation with GP-initiated PCC. Methods Randomised trial of usual care versus GP-initiated PCC for women aged 18–40, in 54 GP practices in the Netherlands. Women completed the six-item Spielberger State Trait Anxiety Inventory (STAI before PCC (STAI-1 and after (STAI-2. After pregnancy women completed a STAI focusing on the first trimester of pregnancy (STAI-3. Results The mean STAI-1-score (n = 466 was 36.4 (95% CI 35.4 – 37.3. Following PCC there was an average decrease of 3.6 points in anxiety-levels (95% CI, 2.4 – 4.8. Mean scores of the STAI-3 were 38.5 (95% CI 37.7 – 39.3 in the control group (n = 1090 and 38.7 (95% CI 37.9 – 39.5 in the intervention group (n = 1186. Conclusion PCC from one's own GP reduced anxiety after participation, without leading to an increase in anxiety among the intervention group during pregnancy. We therefore conclude that GPs can offer PCC to the general population without fear of causing anxiety. Trial Registration: ISRCTN53942912

Description of a new genus and species of the Coleopterous family Colydidae

NARCIS (Netherlands)

Reitter, E.

1882-01-01

Corpus valde elongatum, convexum. Antennae 11-articulatae, sub frontis margine ante oculos insertae, apicem versus sensim incrassatae, articulo ultimo rotundato. Fronte tateribus elevata. Oculi antice emarginati. Prothorax elongatus, carinatus. Scutellum minutum. Elytra punctatostriata, interstitiis

Acetylome analysis reveals the involvement of lysine acetylation in photosynthesis and carbon metabolism in the model cyanobacterium Synechocystis sp. PCC 6803.

Science.gov (United States)

Mo, Ran; Yang, Mingkun; Chen, Zhuo; Cheng, Zhongyi; Yi, Xingling; Li, Chongyang; He, Chenliu; Xiong, Qian; Chen, Hui; Wang, Qiang; Ge, Feng

2015-02-06

Cyanobacteria are the oldest known life form inhabiting Earth and the only prokaryotes capable of performing oxygenic photosynthesis. Synechocystis sp. PCC 6803 (Synechocystis) is a model cyanobacterium used extensively in research on photosynthesis and environmental adaptation. Posttranslational protein modification by lysine acetylation plays a critical regulatory role in both eukaryotes and prokaryotes; however, its extent and function in cyanobacteria remain unexplored. Herein, we performed a global acetylome analysis on Synechocystis through peptide prefractionation, antibody enrichment, and high accuracy LC-MS/MS analysis; identified 776 acetylation sites on 513 acetylated proteins; and functionally categorized them into an interaction map showing their involvement in various biological processes. Consistent with previous reports, a large fraction of the acetylation sites are present on proteins involved in cellular metabolism. Interestingly, for the first time, many proteins involved in photosynthesis, including the subunits of phycocyanin (CpcA, CpcB, CpcC, and CpcG) and allophycocyanin (ApcA, ApcB, ApcD, ApcE, and ApcF), were found to be lysine acetylated, suggesting that lysine acetylation may play regulatory roles in the photosynthesis process. Six identified acetylated proteins associated with photosynthesis and carbon metabolism were further validated by immunoprecipitation and Western blotting. Our data provide the first global survey of lysine acetylation in cyanobacteria and reveal previously unappreciated roles of lysine acetylation in the regulation of photosynthesis. The provided data set may serve as an important resource for the functional analysis of lysine acetylation in cyanobacteria and facilitate the elucidation of the entire metabolic networks and photosynthesis process in this model cyanobacterium.

Parent-Child Communication on Sexuality-Related Matters in the ...

African Journals Online (AJOL)

There are contrasting findings on the role of parent-child communication (PCC) in shaping young people's sexual behaviour. This paper provides answers to questions on gender differentials in parents' involvement in PCC; age and gender differentials in young people's involvement in PCC; and the relationship between ...

Incidentally Detected Inoperable Malignant Pheochromocytoma with Hepatic Metastasis Treated by Transcatheter Arterial Chemoembolization

Directory of Open Access Journals (Sweden)

Joong Keun Kim

2014-12-01

Full Text Available Malignant pheochromocytoma (PCC is a rare condition. Although the liver is the second most frequent site of metastasis in malignant PCC, no definite treatments have been established. Herein, we report a case of liver metastasis of PCC that was successfully treated by transcatheter arterial chemoembolization (TACE. A 69-year-old man was admitted to the Department of Gastroenterology for evaluation of an incidental hepatic mass in August 2013. He had undergone right adrenalectomy in May 2005 and PCC had been confirmed on the basis of histopathological findings. Liver biopsy was performed, and metastatic PCC was diagnosed. The lesion appeared inoperable because of invasion of the portal vein and metastases in the lymph nodes along the hepatoduodenal ligament. Thus, TACE was performed instead. After TACE, symptoms including dizziness and cold sweating improved, and the patient's serum catecholamine levels decreased. On the basis of this case, we believe that TACE may be a useful treatment for liver metastasis in malignant PCC.

Protein (Cyanobacteria): 498001483 [PGDBj - Ortholog DB

Lifescience Database Archive (English)

Full Text Available 2363:858 ... hypothetical protein Synechococcus sp. CB0205 MQPRLSQQEQRALIRAKRAVRCLPFRRRFYEELEREALSSTQLAARSDWTALSCRRLSANHCEYLLIWLIQLGVLRREVDGQGLTERVRLTPLGRVVLSDWPGEIPSASLPSRLRHWIKQHWPRL

Healthcare providers’ views on the delivery of preconception care in a local community setting in the Netherlands

NARCIS (Netherlands)

Poels, M.; M.P.H. Koster (Maria); A. Franx (Arie); H.F. van Stel (Henk)

2017-01-01

textabstractBackground: The attention for preconception care (PCC) has grown substantially in recent years, yet PCC is far from routine in daily practice. One of the major challenges for the implementation of PCC is to identify how it can best be organized and provided within the primary care

Measuring patient-centered communication in cancer care: a literature review and the development of a systematic approach.

Science.gov (United States)

McCormack, Lauren A; Treiman, Katherine; Rupert, Douglas; Williams-Piehota, Pamela; Nadler, Eric; Arora, Neeraj K; Lawrence, William; Street, Richard L

2011-04-01

Patient-centered communication (PCC) is a critical element of patient-centered care, which the Institute of Medicine (Committee on Quality of Health Care in America, 2001) promulgates as essential to improving healthcare delivery. Consequently, the US National Cancer Institute's Strategic Plan for Leading the Nation (2006) calls for assessing the delivery of PCC in cancer care. However, no comprehensive measure of PCC exists, and stakeholders continue to embrace different conceptualizations and assumptions about how to measure it. Our approach was grounded in the PCC conceptual framework presented in a recent US National Cancer Institute monograph (Epstein & Street, 2007). In this study, we developed a comprehensive inventory of domains and subdomains for PCC by reviewing relevant literature and theories, interviewing a limited number of cancer patients, and consulting experts. The resulting measurement domains are organized under the six core functions specified in the PCC conceptual framework: exchanging information, fostering healing relationships, recognizing and responding to emotions, managing uncertainty, making decisions, and enabling patient self-management. These domains represent a promising platform for operationalizing the complicated PCC construct. Although this study focused specifically on cancer care, the PCC measurements are relevant to other clinical contexts and illnesses, given that patient-centered care is a goal across all healthcare. Finally, we discuss considerations for developing PCC measures for research, quality assessment, and surveillance purposes. United States Department of Health and Human Services, National Institutes of Health, National Cancer Institute (2006). The NCI Strategic Plan for Leading the Nation: To Eliminate the Suffering and Death Due to Cancer. NIH Publication No. 06-5773. Copyright © 2011 Elsevier Ltd. All rights reserved.

Protein (Cyanobacteria): 218248342 [PGDBj - Ortholog DB

Lifescience Database Archive (English)

Full Text Available ... hypothetical protein PCC8801_3595 Cyanothece sp. PCC 8801 MSIQYLLDENLPHLYREQLLRLKSDLTVWIIGDPGVPPKSTLDPEILIWCEQNKFILVTNNRASMPVHLADHLSQNRHIPGIFVLRPKASIGEIIDDLILIDELGNPQDYQDCISHIPFI

Healthcare providers' views on the delivery of preconception care in a local community setting in the Netherlands

NARCIS (Netherlands)

Poels, M; Koster, MPH; Franx, A; van Stel, H F

2017-01-01

BACKGROUND: The attention for preconception care (PCC) has grown substantially in recent years, yet PCC is far from routine in daily practice. One of the major challenges for the implementation of PCC is to identify how it can best be organized and provided within the primary care setting. The aim

Pharmacists’ social authority to transform community pharmacy practice

Directory of Open Access Journals (Sweden)

Timothy McPherson, PhD, RPh

2011-01-01

Full Text Available Leaders in the profession of pharmacy have articulated a vision of pharmacists as providers of patient-centered care (PCC services and the Doctor of Pharmacy was established as the required practice degree to achieve this vision. Pharmacist-provided PCC services have been shown to reduce medication costs and improve patient compliance with therapies. While community pharmacists are capable of, and are ideally placed for, providing PCC services, in fact they devote most of their time to prescription dispensing rather than direct patient care. As professionals, community pharmacists are charged with protecting society by providing expert services to help consumers manage risks associated with drug therapies. Historically pharmacists fulfilled this responsibility by accurately dispensing prescription medications, verifying doses, and allergy checking. This limited view of pharmacy practice is insufficient in light of the modern view of pharmacists as providers of PCC. The consumers’ view of community pharmacy as a profession represents a barrier to transforming the basis of community pharmacy from product distribution to providing PCC services. Community pharmacists are conferred with social authority to dictate the manner in which their professional services are provided. Pharmacists can therefore facilitate the transition to PCC as the primary function of community pharmacy by exercising their social authority to engage consumers in their roles in the new patient-pharmacist relationship. Each pharmacist must decide to provide PCC services. Suggestions for initiating PCC services in community pharmacy are offered.

Pharmacists' social authority to transform community pharmacy practice

Directory of Open Access Journals (Sweden)

Timothy McPherson

2011-01-01

Full Text Available Leaders in the profession of pharmacy have articulated a vision of pharmacists as providers of patient-centered care (PCC services and the Doctor of Pharmacy was established as the required practice degree to achieve this vision. Pharmacist-provided PCC services have been shown to reduce medication costs and improve patient compliance with therapies. While community pharmacists are capable of, and are ideally placed for, providing PCC services, in fact they devote most of their time to prescription dispensing rather than direct patient care. As professionals, community pharmacists are charged with protecting society by providing expert services to help consumers manage risks associated with drug therapies. Historically pharmacists fulfilled this responsibility by accurately dispensing prescription medications, verifying doses, and allergy checking. This limited view of pharmacy practice is insufficient in light of the modern view of pharmacists as providers of PCC. The consumers' view of community pharmacy as a profession represents a barrier to transforming the basis of community pharmacy from product distribution to providing PCC services. Community pharmacists are conferred with social authority to dictate the manner in which their professional services are provided. Pharmacists can therefore facilitate the transition to PCC as the primary function of community pharmacy by exercising their social authority to engage consumers in their roles in the new patient-pharmacist relationship. Each pharmacist must decide to provide PCC services. Suggestions for initiating PCC services in community pharmacy are offered.   Type: Idea Paper

Dose response curve for prematurely condensed chromosome fragments of human lymphocytes after 60Co-γ ray exposure

International Nuclear Information System (INIS)

Gao Jinsheng; Zheng Siying; Bao Hong

1992-06-01

The dose-effect relationship of premature condensed chromosome fragments in human lymphocytes irradiated by 60 Co gamma ray was studied by PCC method (premature condensed chromosomes). In addition, The conventional cellular genetics method was also used in the study. The response curve of both methods can represented by two linear equations. The ratio of two slopes, K PCC /K M1 , is about 28. Comparing with conventional method, the PCC method has many advantages such as faster, simpler, more sensitive and accurate. The PCC method used in the studying of radiation damage is also discussed

Utilizing a Pediatric Disaster Coalition Model to Increase Pediatric Critical Care Surge Capacity in New York City.

Science.gov (United States)

Frogel, Michael; Flamm, Avram; Sagy, Mayer; Uraneck, Katharine; Conway, Edward; Ushay, Michael; Greenwald, Bruce M; Pierre, Louisdon; Shah, Vikas; Gaffoor, Mohamed; Cooper, Arthur; Foltin, George

2017-08-01

A mass casualty event can result in an overwhelming number of critically injured pediatric victims that exceeds the available capacity of pediatric critical care (PCC) units, both locally and regionally. To address these gaps, the New York City (NYC) Pediatric Disaster Coalition (PDC) was established. The PDC includes experts in emergency preparedness, critical care, surgery, and emergency medicine from 18 of 25 major NYC PCC-capable hospitals. A PCC surge committee created recommendations for making additional PCC beds available with an emphasis on space, staff, stuff (equipment), and systems. The PDC assisted 15 hospitals in creating PCC surge plans by utilizing template plans and site visits. These plans created an additional 153 potential PCC surge beds. Seven hospitals tested their plans through drills. The purpose of this article was to demonstrate the need for planning for disasters involving children and to provide a stepwise, replicable model for establishing a PDC, with one of its primary goals focused on facilitating PCC surge planning. The process we describe for developing a PDC can be replicated to communities of any size, setting, or location. We offer our model as an example for other cities. (Disaster Med Public Health Preparedness. 2017;11:473-478).

Rerouting of carbon flux in a glycogen mutant of cyanobacteria assessed via isotopically non-stationary 13 C metabolic flux analysis.

Science.gov (United States)

Hendry, John I; Prasannan, Charulata; Ma, Fangfang; Möllers, K Benedikt; Jaiswal, Damini; Digmurti, Madhuri; Allen, Doug K; Frigaard, Niels-Ulrik; Dasgupta, Santanu; Wangikar, Pramod P

2017-10-01

Cyanobacteria, which constitute a quantitatively dominant phylum, have attracted attention in biofuel applications due to favorable physiological characteristics, high photosynthetic efficiency and amenability to genetic manipulations. However, quantitative aspects of cyanobacterial metabolism have received limited attention. In the present study, we have performed isotopically non-stationary 13 C metabolic flux analysis (INST- 13 C-MFA) to analyze rerouting of carbon in a glycogen synthase deficient mutant strain (glgA-I glgA-II) of the model cyanobacterium Synechococcus sp. PCC 7002. During balanced photoautotrophic growth, 10-20% of the fixed carbon is stored in the form of glycogen via a pathway that is conserved across the cyanobacterial phylum. Our results show that deletion of glycogen synthase gene orchestrates cascading effects on carbon distribution in various parts of the metabolic network. Carbon that was originally destined to be incorporated into glycogen gets partially diverted toward alternate storage molecules such as glucosylglycerol and sucrose. The rest is partitioned within the metabolic network, primarily via glycolysis and tricarboxylic acid cycle. A lowered flux toward carbohydrate synthesis and an altered distribution at the glucose-1-phosphate node indicate flexibility in the network. Further, reversibility of glycogen biosynthesis reactions points toward the presence of futile cycles. Similar redistribution of carbon was also predicted by Flux Balance Analysis. The results are significant to metabolic engineering efforts with cyanobacteria where fixed carbon needs to be re-routed to products of interest. Biotechnol. Bioeng. 2017;114: 2298-2308. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

The persistence and ecological impacts of a cyanobacterium genetically engineered to express mosquitocidal Bacillus thuringiensis toxins.

Science.gov (United States)

Ketseoglou, Irene; Bouwer, Gustav

2016-05-10

The cyanobacterium Anabaena PCC 7120#11 has been genetically engineered to act as a delivery vehicle for Bacillus thuringiensis subspecies israelensis mosquitocidal toxins. To address ecological concerns about releasing this genetically engineered microorganism into the environment for mosquito larva control, the persistence and ecological impacts of PCC 7120#11 was evaluated using multi-species, standardized aquatic microcosms. The microcosms were set up as described in ASTM E1366-02 (Standard Practice for Standardized Aquatic Microcosms: Fresh Water), with a few modifications. The treatment group microcosms were inoculated with PCC 7120#11 and key water quality parameters and non-target effects were compared between the treatment and control groups over a period of 35 days. PCC 7120#11 decreased from a concentration of 4.50 × 10(6) cells/ml (at inoculation) to 1.32 × 10(3) cells/ml after 4 weeks and larvicidal activity against third instar larvae of Anopheles arabiensis was only evident for two weeks after treatment. Both treatment and the interaction of treatment and time had a significant effect on nitrate, phosphate and photosynthetic microorganism concentrations. Treatment with PCC 7120#11 caused a temporary spike in ammonia in the microcosms a week after treatment, but the concentrations were well below acute and chronic criteria values for ammonia in freshwater ecosystems. Cyprinotus vidua concentrations were not significantly different between PCC 7120#11 and control microcosms. In PCC 7120#11 microcosms, Daphnia pulex concentrations were significantly lower than control concentrations between days 18 and 25. By the end of the experiment, none of the measured variables were significantly different between the treatment groups. The standard aquatic microcosm experiments provided more data on the ecological impacts of PCC 7120#11 than single-organism assessments would have. On the basis of the relatively minor, short-term effects that PCC 7120

Effect of precipitated calcium carbonate--Cellulose nanofibrils composite filler on paper properties.

Science.gov (United States)

He, Ming; Cho, Byoung-Uk; Won, Jong Myoung

2016-01-20

A new concept of composite filler was developed by using cellulose nanofibrils (CNF), precipitated calcium carbonate (PCC) and cationic starch (C-starch). In this study, cellulose nanofibrils were utilized in two different ways: a PCC-CNF composite filler and a papermaking additive in sheet forming. The aim was to elucidate their effects on flocculation, filler retention and the strength and optical properties of handsheets. The highest filler retention was obtained by using the PCC-CNF composite filler in paper sheets. The paper filled with the composite fillers had much higher bursting and tensile strengths than conventional PCC loading. It was also found that the paper prepared with PCC-CNF composite fillers became denser with increasing the filler content of paper. Copyright © 2015 Elsevier Ltd. All rights reserved.

Treatment in a Preventive Cardiology Clinic Utilizing Advanced Practice Providers (APPs) Effectively Closes Atherosclerotic Cardiovascular Disease (ASCVD) Risk Management Gaps Amongst a Primary Prevention Population Compared with a Propensity-Matched Primary Care Cohort: A Team Based Care Model and its Impact on Lipid and Blood Pressure Management.

Science.gov (United States)

Fentanes, Emilio; Vande Hei, Anthony G; Holuby, R Scott; Suarez, Norma; Slim, Yousif; Slim, Jennifer N; Slim, Ahmad M; Thomas, Dustin

2018-04-17

Advanced Practice Providers (APPs) can fill access to care gaps created by physician shortages and improve adherence/compliance with preventive atherosclerotic cardiovascular disease (ASCVD) interventions. We retrospectively reviewed data on 595 patients enrolled in a preventive cardiology clinic (PCC) utilizing APPs compared with a propensity-matched cohort (PMC) of 595 patients enrolled in primary care clinics alone. PCC patients were risk stratified using Framingham risk scoring (FRS) and coronary artery calcium scoring (CACS) and treated based on published guideline-based algorithms. Baseline demographics were well balanced between the groups. CACS was more commonly obtained in PCC patients (p<0.001) resulting in reclassification of 30.6% patients to a higher risk category, including statin therapy in 26.6% of low FRS PCC patients with CACS ≥75 th MESA percentile. Aspirin initiation was higher for high and intermediate FRS patients in the PCC (p <0.001). Post-intervention mean LDL, non-HDL, and triglycerides (all p<0.05) were lower in the PCC group. Compliance with appropriate lipid treatment was higher in intermediate to high FRS patients (p=0.004) in the PCC group. Aggressive LDL and non-HDL treatment goals <70mg/dL (p=0.005) and <130mg/dL (p<0.001), respectively, were more commonly achieved in high FRS PCC patients. Median post-intervention SBP was lower amongst intermediate and low FRS patients (p=0.001 & p<0.001, respectively). Cumulatively, this resulted in a reduction in median post-intervention PCC FRS across all initial FRS risk categories (p<0.001 for all). APPs within a preventive cardiology clinic effectively risk stratify and aggressively manage ASCVD risk factors resulting in a reduction in post-intervention FRS. This article is protected by copyright. All rights reserved.

Floating cultivation of marine cyanobacteria using coal fly ash

Energy Technology Data Exchange (ETDEWEB)

Matsumoto, M.; Yoshida, E.; Takeyama, H.; Matsunaga, T. [Tokyo University of Agriculture and Technology, Tokyo (Japan). Dept. of Biotetechnology

2000-07-01

The aim was to develop improved methodologies for bulk culturing of biotechnologically useful marine cyanobacteria in the open ocean. The viability of using coal fly ash (CFA) blocks as the support medium in a novel floating culture system for marine microalgae was investigated. The marine cyanobacterium Synechococcus sp. NKBC 040607 was found to adhere to floating CFA blocks in liquid culture medium. The marine cyanobacterium Synechococcus sp. NKBG 042902 weakly adhered to floating CFA blocks in BG-11 medium. Increasing the concentration of calcium ion in the culture medium enhanced adherence to CFA blocks.

Role of Two Cell Wall Amidases in Septal Junction and Nanopore Formation in the Multicellular Cyanobacterium Anabaena sp. PCC 7120

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Jan Bornikoel

2017-09-01

Full Text Available Filamentous cyanobacteria have developed a strategy to perform incompatible processes in one filament by differentiating specialized cell types, N2-fixing heterocysts and CO2-fixing, photosynthetic, vegetative cells. These bacteria can be considered true multicellular organisms with cells exchanging metabolites and signaling molecules via septal junctions, involving the SepJ and FraCD proteins. Previously, it was shown that the cell wall lytic N-acetylmuramyl-L-alanine amidase, AmiC2, is essential for cell–cell communication in Nostoc punctiforme. This enzyme perforates the septal peptidoglycan creating an array of nanopores, which may be the framework for septal junction complexes. In Anabaena sp. PCC 7120, two homologs of AmiC2, encoded by amiC1 and amiC2, were identified and investigated in two different studies. Here, we compare the function of both AmiC proteins by characterizing different Anabaena amiC mutants, which was not possible in N. punctiforme, because there the amiC1 gene could not be inactivated. This study shows the different impact of each protein on nanopore array formation, the process of cell–cell communication, septal protein localization, and heterocyst differentiation. Inactivation of either amidase resulted in significant reduction in nanopore count and in the rate of fluorescent tracer exchange between neighboring cells measured by FRAP analysis. In an amiC1 amiC2 double mutant, filament morphology was affected and heterocyst differentiation was abolished. Furthermore, the inactivation of amiC1 influenced SepJ localization and prevented the filament-fragmentation phenotype that is characteristic of sepJ or fraC fraD mutants. Our findings suggest that both amidases are to some extent redundant in their function, and describe a functional relationship of AmiC1 and septal proteins SepJ and FraCD.

Trade-Off between Growth and Carbohydrate Accumulation in Nutrient-Limited Arthrospira sp. PCC 8005 Studied by Integrating Transcriptomic and Proteomic Approaches.

Directory of Open Access Journals (Sweden)

Orily Depraetere

Full Text Available Cyanobacteria have a strong potential for biofuel production due to their ability to accumulate large amounts of carbohydrates. Nitrogen (N stress can be used to increase the content of carbohydrates in the biomass, but it is expected to reduce biomass productivity. To study this trade-off between carbohydrate accumulation and biomass productivity, we characterized the biomass productivity, biomass composition as well as the transcriptome and proteome of the cyanobacterium Arthrospira sp. PCC 8005 cultured under N-limiting and N-replete conditions. N limitation resulted in a large increase in the carbohydrate content of the biomass (from 14 to 74% and a decrease in the protein content (from 37 to 10%. Analyses of fatty acids indicated that no lipids were accumulated under N-limited conditions. Nevertheless, it did not affect the biomass productivity of the culture up to five days after N was depleted from the culture medium. Transcriptomic and proteomic analysis indicated that de novo protein synthesis was down-regulated in the N-limited culture. Proteins were degraded and partly converted into carbohydrates through gluconeogenesis. Cellular N derived from protein degradation was recycled through the TCA and GS-GOGAT cycles. In addition, photosynthetic energy production and carbon fixation were both down-regulated, while glycogen synthesis was up-regulated. Our results suggested that N limitation resulted in a redirection of photosynthetic energy from protein synthesis to glycogen synthesis. The fact that glycogen synthesis has a lower energy demand than protein synthesis might explain why Arthrospira is able to achieve a similar biomass productivity under N-limited as under N-replete conditions despite the fact that photosynthetic energy production was impaired by N limitation.

Modeling selective pressures on phytoplankton in the global ocean.

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Jason G Bragg

Full Text Available Our view of marine microbes is transforming, as culture-independent methods facilitate rapid characterization of microbial diversity. It is difficult to assimilate this information into our understanding of marine microbe ecology and evolution, because their distributions, traits, and genomes are shaped by forces that are complex and dynamic. Here we incorporate diverse forces--physical, biogeochemical, ecological, and mutational--into a global ocean model to study selective pressures on a simple trait in a widely distributed lineage of picophytoplankton: the nitrogen use abilities of Synechococcus and Prochlorococcus cyanobacteria. Some Prochlorococcus ecotypes have lost the ability to use nitrate, whereas their close relatives, marine Synechococcus, typically retain it. We impose mutations for the loss of nitrogen use abilities in modeled picophytoplankton, and ask: in which parts of the ocean are mutants most disadvantaged by losing the ability to use nitrate, and in which parts are they least disadvantaged? Our model predicts that this selective disadvantage is smallest for picophytoplankton that live in tropical regions where Prochlorococcus are abundant in the real ocean. Conversely, the selective disadvantage of losing the ability to use nitrate is larger for modeled picophytoplankton that live at higher latitudes, where Synechococcus are abundant. In regions where we expect Prochlorococcus and Synechococcus populations to cycle seasonally in the real ocean, we find that model ecotypes with seasonal population dynamics similar to Prochlorococcus are less disadvantaged by losing the ability to use nitrate than model ecotypes with seasonal population dynamics similar to Synechococcus. The model predictions for the selective advantage associated with nitrate use are broadly consistent with the distribution of this ability among marine picocyanobacteria, and at finer scales, can provide insights into interactions between temporally varying

Modeling selective pressures on phytoplankton in the global ocean.

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Bragg, Jason G; Dutkiewicz, Stephanie; Jahn, Oliver; Follows, Michael J; Chisholm, Sallie W

2010-03-10

Our view of marine microbes is transforming, as culture-independent methods facilitate rapid characterization of microbial diversity. It is difficult to assimilate this information into our understanding of marine microbe ecology and evolution, because their distributions, traits, and genomes are shaped by forces that are complex and dynamic. Here we incorporate diverse forces--physical, biogeochemical, ecological, and mutational--into a global ocean model to study selective pressures on a simple trait in a widely distributed lineage of picophytoplankton: the nitrogen use abilities of Synechococcus and Prochlorococcus cyanobacteria. Some Prochlorococcus ecotypes have lost the ability to use nitrate, whereas their close relatives, marine Synechococcus, typically retain it. We impose mutations for the loss of nitrogen use abilities in modeled picophytoplankton, and ask: in which parts of the ocean are mutants most disadvantaged by losing the ability to use nitrate, and in which parts are they least disadvantaged? Our model predicts that this selective disadvantage is smallest for picophytoplankton that live in tropical regions where Prochlorococcus are abundant in the real ocean. Conversely, the selective disadvantage of losing the ability to use nitrate is larger for modeled picophytoplankton that live at higher latitudes, where Synechococcus are abundant. In regions where we expect Prochlorococcus and Synechococcus populations to cycle seasonally in the real ocean, we find that model ecotypes with seasonal population dynamics similar to Prochlorococcus are less disadvantaged by losing the ability to use nitrate than model ecotypes with seasonal population dynamics similar to Synechococcus. The model predictions for the selective advantage associated with nitrate use are broadly consistent with the distribution of this ability among marine picocyanobacteria, and at finer scales, can provide insights into interactions between temporally varying ocean processes and

Micro and colloidal stickie pacification with precipitated calcium carbonate

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John H. Klungness; Roland L. Gleisner; Marguerite S. Sykes

2002-01-01

Colloidal stickies that build up in mill process water during pulping are problematic and difficult to remove. We examined precipitated calcium carbonate (PCC) as a means to ameliorate process water stickies. The effectiveness of PCC added directly into a slurry of deinked pulp was compared with in situ precipitation of PCC by the fiber loading method. We found that...

Person-centered care in Norwegian nursing homes and its relation to organizational factors and staff characteristics: a cross-sectional survey.

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Røen, Irene; Kirkevold, Øyvind; Testad, Ingelin; Selbæk, Geir; Engedal, Knut; Bergh, Sverre

2017-12-04

Person-centered care (PCC) is regarded as good quality care for persons with dementia. This study aimed to explore and understand the association between PCC and organizational, staff and unit characteristics in nursing homes (NHs). Staff from 175 NH units in Norway (n = 1,161) completed a survey, including measures of PCC and questions about staff characteristics and work-related psychosocial factors. In addition, data about organizational and structural factors and assessment of the physical environment in the units were obtained. The distribution of these factors in regular units (RUs) and special care units (SCUs) is described, and the differences between the two types of units are analyzed. Furthermore, multilevel linear regression analyses explored the extent to which variables were associated with PCC. Higher levels of PCC were associated with a greater job satisfaction, three years or more of health-related education, a lower level of quantitative demands and role conflict, a higher level of perception of mastery, empowering leadership, innovative climate and perception of group work, in addition to the type of unit and the physical environment in the NH unit designed for people with dementia. SCU and staff job satisfaction explained most of the variation in PCC. This study shows an association between PCC and organizational, staff and unit characteristics in NH. These findings indicate that providing PCC in NH care is closely linked to how the staff experiences their job situation in addition to both organizational and structural factors and the physical environment. Attention needs to be given to such factors when planning NH care.

Developing social marketed individual preconception care consultations: Which consumer preferences should it meet?

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van Voorst, Sabine F; Ten Kate, Chantal A; de Jong-Potjer, Lieke C; Steegers, Eric A P; Denktaş, Semiha

2017-10-01

Preconception care (PCC) is care that aims to improve the health of offspring by addressing risk factors in the pre-pregnancy period. Consultations are recognized as a method to promote perinatal health. However, prospective parents underutilize PCC services. Uptake can improve if delivery approaches satisfy consumer preferences. Aim of this study was to identify preferences of women (consumers) as a first step to social marketed individual PCC consultations. In depth, semi-structured interviews were performed to identify women's views regarding the four components of the social marketing model: product (individual PCC consultation), place (setting), promotion (how women are made aware of the product) and price (costs). Participants were recruited from general practices and a midwife's practice. Content analysis was performed by systematic coding with NVIVO software. The 39 participants reflected a multiethnic intermediately educated population. Product: Many participants had little knowledge of the need and the benefits of the product. Regarding the content of PCC, they wish to address fertility concerns and social aspects of parenthood. PCC was seen as an informing and coaching service with a predominant role for health-care professionals. the general practitioner and midwife setting was the most mentioned setting. Promotion: A professional led promotion approach was preferred. Price: Introduction of a fee for PCC consultations will make people reconsider their need for a consultation and could exclude vulnerable patients from utilization. This study provides consumer orientated data to design a social marketed delivery approach for individual PCC consultations. © 2017 The Authors Health Expectations Published by John Wiley & Sons Ltd.

CXCR4/Let-7a Axis Regulates Metastasis and Chemoresistance of Pancreatic Cancer Cells Through Targeting HMGA2

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Guangfa Xiao

2017-09-01

Full Text Available Background/Aims: Pancreatic cancer cells (PCC is one of the most risky cancers and gemcitabine (GEM is the standard first-line drug for treating PCC. The PCC will develop drug resistance to GEM after a period of treatment. However, the detailed molecular mechanism of pathogenesis and drug resistance remains unresolved. Methods: we employed qRT-PCR and western blot to examine the expression level of CXCR4, let-7a and HMGA2. In addition, we used MTT assay to detect cell proliferation and transwell assay to measure migration and invasiveness. The expression level of epithelial marker E-cadherin and mesenthymal marker N-cadherin was detected by western blot. The apoptosis was determined using annexin V-FITC/PI apoptosis detection kit by flow cytometry. Results: we first proved that CXCR4 negatively regulated let-7a in PCC. Next, let-7a was confirmed to play crucial role in tumorigenesis, metastasis and drug resistance of pancreatic cancer cells Bxpc-3 and Panc-1 in vitro and in vivo. Finally, we identified HMGA2 as important downsteam target of let-7a in PCC and overexpression of HMGA2 restores cell proliferation, metastasis and chemosensitivity of GEM inhibited by let-7a. Conlusion: Taken together, we show an important signaling pathway involved in pathogenesis and drug resistance of PCC, thereby providing deeper insight into molecular mechanism by which CXCR4/let-7a regulates tumorigenesis and drug resistance of PCC. These findings will help us develop new strategies for diagnosis and treatment of PCC.

Does Person-Centered Care Improve Residents' Satisfaction With Nursing Home Quality?

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Poey, Judith L; Hermer, Linda; Cornelison, Laci; Kaup, Migette L; Drake, Patrick; Stone, Robyn I; Doll, Gayle

2017-11-01

Person-centered care (PCC) is meant to enhance nursing home residents' quality of life (QOL). Including residents' perspectives is critical to determining whether PCC is meeting residents' needs and desires. This study examines whether PCC practices promote satisfaction with QOL and quality of care and services (QOC and QOS) among nursing home residents. A longitudinal, retrospective cohort study using an in-person survey. Three hundred twenty nursing homes in Kansas enrolled or not enrolled in a pay-for-performance program, Promoting Excellent Alternatives in Kansas (PEAK 2.0), to promote PCC in nursing homes. A total of 6214 nursing home residents in 2013-2014 and 5538 residents in 2014-2015, with a Brief Interview for Mental Status score ≥8, participated in face-to-face interviews. Results were aggregated to the nursing home level. My InnerView developed a Resident Satisfaction Survey for Kansas composed of 32 questions divided into QOL, QOC, QOS, and global satisfaction subdomains. After controlling for facility characteristics, satisfaction with overall QOL and QOC was higher in homes that had fully implemented PCC. Although some individual measures in the QOS domain (eg, food) showed greater satisfaction at earlier levels of implementation, high satisfaction was observed primarily in homes that had fully implemented PCC. These findings provide evidence for the effectiveness of PCC implementation on nursing home resident satisfaction. The PEAK 2.0 program may provide replicable methods for nursing homes and states to implement PCC systematically. Copyright © 2017 AMDA – The Society for Post-Acute and Long-Term Care Medicine. Published by Elsevier Inc. All rights reserved.

Description d’une nouvelle espèce de Gyrinide du Musée de Leyde

NARCIS (Netherlands)

Regimbart, M.

1884-01-01

Long. 6 3/4 mm. (ano excepto). — Oblongo-ovalis, elongatus, mediocriter convexus; supra in regionibus glabris purpureocupreus, nitidus, subtilissime reticulatus, in regionibus punctato-tomentosis obscure cœruleus et subopacus, anguste pallide testaceo limbatus; infra pallide testaceus, pedibus

New synonymy in Cuban Tilloclytus (Coleoptera: Cerambycidae: Anaglyptini)

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Examination of holotypes of Tilloclytus (Coleoptera: Cerambycidae: Anaglyptini) in the Fernando de Zayas collection (Havana, Cuba) and the Museum of Comparative Zoology, Harvard University reveals that T. elongatus Zayas (1975) is a new synonym of T. rufipes Fisher (1942)....

Evaluation of the Township Proper Carrying Capacity over Qinghai-Tibet plateau by CASA model

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Wu, Chengyong; Cao, Guangchao; Xue, Huaju; Jiang, Gang; Wang, Qi; Yuan, Jie; Chen, Kelong

2018-01-01

The existing study of proper carrying capacity (PCC) has mostly focused on province or county administrative units, which can only macroscopically master the quantitative characteristics of PCC, but could not effectively take some animal husbandry management measures that are pertinent and operational. At town-scale, this paper used CASA model to estimate the PCC in Mongolian Autonomous County of Henan, Qinghai province, China,with serious grassland degeneration that mainly caused by overgrazing. The results showed that the PCC throughout the County was 950,417 sheep unit. For the township, the PCC of Saierlong and Duosong were the largest (247,100 sheep unit) and the smallest (82,016 sheep unit) respectively. This study will provide reference data for developing sustainable development of town-scale pasture policies and also will help to evaluate the health status of the alpine grassland ecosystem on Qinghai-Tibet plateau.

Analysis of Combustion Process in Industrial Gas Engine with Prechamber-Based Ignition System

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Rafał Ślefarski

2018-02-01

Full Text Available Application of a pre-combustion chamber (PCC ignition system is one of the methods to improve combustion stability and reduce toxic compounds emission, especially NOx. Using PCC allows the operation of the engine at lean combustion conditions or the utilization of low calorific gaseous fuels such as syngas or biogas. The paper presents the results of an experimental study of the combustion process in two stroke, large bore, stationary gas engine GMVH 12 equipped with two spark plugs (2-SP and a PCC ignition system. The experimental research has been performed during the normal operation of the engine in an industrial compression station. It was observed that application of PCC provides less cycle-to-cycle combustion variation (more than 10% and nitric oxide and carbon monoxide emissions decreased to 60% and 26% respectively. The total hydrocarbon (THC emission rate is 25% higher for the engine equipped with PCC, which results in roughly two percent engine efficiency decrease. Another important criterion of engine retrofitting was the PCC location in the engine head. The experimental results show that improvement of engine operating parameters was recorded only for a configuration with one port offset by 45° from the axis of the main chamber. The study of the ignition delay angle and equivalence ratio in PCC did not demonstrate explicit influence on engine performance.

Polymeric nanoparticles developed by vitamin E-modified aliphatic polycarbonate polymer to promote oral absorption of oleanolic acid

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Wenjuan Zhang

2017-11-01

Full Text Available Oleanolic acid (OA exhibited good pharmacological activities in the clinical treatment of hypoglycemia, immune regulation, acute jaundice and chronic toxic hepatitis. However, the oral delivery of OA is greatly limited by its inferior water solubility and poor intestinal mucosa permeability. Herein, we developed a novel polymeric nanoparticle (NP delivery system based on vitamin E modified aliphatic polycarbonate (mPEG-PCC-VE to facilitate oral absorption of OA. OA encapsulated mPEG-PCC-VE NPs (OA/mPEG-PCC-VE NPs showed uniform particle size of about 170 nm with high drug loading capability (8.9%. Furthermore, the polymeric mPEG-PCC-VE NPs, with good colloidal stability and pH-sensitive drug release characteristics, significantly enhanced the in vitro dissolution of OA in the alkaline medium. The in situ single pass intestinal perfusion (SPIP studies performed on rats demonstrated that the OA/mPEG-PCC-VE NPs showed significantly improved permeability in the whole intestinal tract when compared to OA solution, especially for duodenum and colon. As a result, the in vivo pharmacokinetics study indicated that the bioavailability of OA/mPEG-PCC-VE NPs showed 1.5-fold higher than commercially available OA tablets. These results suggest that mPEG-PCC-VE NPs are a promising platform to facilitate the oral delivery of OA.

Psychometric evaluation and design of patient-centered communication measures for cancer care settings.

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Reeve, Bryce B; Thissen, David M; Bann, Carla M; Mack, Nicole; Treiman, Katherine; Sanoff, Hanna K; Roach, Nancy; Magnus, Brooke E; He, Jason; Wagner, Laura K; Moultrie, Rebecca; Jackson, Kathryn D; Mann, Courtney; McCormack, Lauren A

2017-07-01

To evaluate the psychometric properties of questions that assess patient perceptions of patient-provider communication and design measures of patient-centered communication (PCC). Participants (adults with colon or rectal cancer living in North Carolina) completed a survey at 2 to 3 months post-diagnosis. The survey included 87 questions in six PCC Functions: Exchanging Information, Fostering Health Relationships, Making Decisions, Responding to Emotions, Enabling Patient Self-Management, and Managing Uncertainty. For each Function we conducted factor analyses, item response theory modeling, and tests for differential item functioning, and assessed reliability and construct validity. Participants included 501 respondents; 46% had a high school education or less. Reliability within each Function ranged from 0.90 to 0.96. The PCC-Ca-36 (36-question survey; reliability=0.94) and PCC-Ca-6 (6-question survey; reliability=0.92) measures differentiated between individuals with poor and good health (i.e., known-groups validity) and were highly correlated with the HINTS communication scale (i.e., convergent validity). This study provides theory-grounded PCC measures found to be reliable and valid in colorectal cancer patients in North Carolina. Future work should evaluate measure validity over time and in other cancer populations. The PCC-Ca-36 and PCC-Ca-6 measures may be used for surveillance, intervention research, and quality improvement initiatives. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.