WorldWideScience

Sample records for synechococcus elongatus pcc

  1. Direct Conversion of CO2to α-Farnesene Using Metabolically Engineered Synechococcus elongatus PCC 7942.

    Science.gov (United States)

    Lee, Hyun Jeong; Lee, Jiwon; Lee, Sun-Mi; Um, Youngsoon; Kim, Yunje; Sim, Sang Jun; Choi, Jong-Il; Woo, Han Min

    2017-12-06

    Direct conversion of carbon dioxide (CO 2 ) to value-added chemicals by engineering of cyanobacteria has received attention as a sustainable strategy in food and chemical industries. Herein, Synechococcus elongatus PCC 7942, a model cyanobacterium, was engineered to produce α-farnesene from CO 2 . As a result of the lack of farnesene synthase (FS) activity in the wild-type cyanobacterium, we metabolically engineered S. elongatus PCC 7942 to express heterologous FS from either Norway spruce or apple fruit, resulting in detectable peaks of α-farnesene. To enhance α-farnesene production, an optimized methylerythritol phosphate (MEP) pathway was introduced in the farnesene-producing strain to supply farnesyl diphosphate. Subsequent cyanobacterial culture with a dodecane overlay resulted in photosynthetic production of α-farnesene (4.6 ± 0.4 mg/L in 7 days) from CO 2 . To the best of our knowledge, this is the first report of the photosynthetic production of α-farnesene from CO 2 in the unicellular cyanobacterium S. elongatus PCC 7942.

  2. Transcriptome landscape of Synechococcus elongatus PCC 7942 for nitrogen starvation responses using RNA-seq

    Science.gov (United States)

    Choi, Sun Young; Park, Byeonghyeok; Choi, In-Geol; Sim, Sang Jun; Lee, Sun-Mi; Um, Youngsoon; Woo, Han Min

    2016-01-01

    The development of high-throughput technology using RNA-seq has allowed understanding of cellular mechanisms and regulations of bacterial transcription. In addition, transcriptome analysis with RNA-seq has been used to accelerate strain improvement through systems metabolic engineering. Synechococcus elongatus PCC 7942, a photosynthetic bacterium, has remarkable potential for biochemical and biofuel production due to photoautotrophic cell growth and direct CO2 conversion. Here, we performed a transcriptome analysis of S. elongatus PCC 7942 using RNA-seq to understand the changes of cellular metabolism and regulation for nitrogen starvation responses. As a result, differentially expressed genes (DEGs) were identified and functionally categorized. With mapping onto metabolic pathways, we probed transcriptional perturbation and regulation of carbon and nitrogen metabolisms relating to nitrogen starvation responses. Experimental evidence such as chlorophyll a and phycobilisome content and the measurement of CO2 uptake rate validated the transcriptome analysis. The analysis suggests that S. elongatus PCC 7942 reacts to nitrogen starvation by not only rearranging the cellular transport capacity involved in carbon and nitrogen assimilation pathways but also by reducing protein synthesis and photosynthesis activities. PMID:27488818

  3. Blueprint for a minimal photoautotrophic cell: conserved and variable genes in Synechococcus elongatus PCC 7942

    Directory of Open Access Journals (Sweden)

    Peretó Juli

    2011-01-01

    Full Text Available Abstract Background Simpler biological systems should be easier to understand and to engineer towards pre-defined goals. One way to achieve biological simplicity is through genome minimization. Here we looked for genomic islands in the fresh water cyanobacteria Synechococcus elongatus PCC 7942 (genome size 2.7 Mb that could be used as targets for deletion. We also looked for conserved genes that might be essential for cell survival. Results By using a combination of methods we identified 170 xenologs, 136 ORFans and 1401 core genes in the genome of S. elongatus PCC 7942. These represent 6.5%, 5.2% and 53.6% of the annotated genes respectively. We considered that genes in genomic islands could be found if they showed a combination of: a unusual G+C content; b unusual phylogenetic similarity; and/or c a small number of the highly iterated palindrome 1 (HIP1 motif plus an unusual codon usage. The origin of the largest genomic island by horizontal gene transfer (HGT could be corroborated by lack of coverage among metagenomic sequences from a fresh water microbialite. Evidence is also presented that xenologous genes tend to cluster in operons. Interestingly, most genes coding for proteins with a diguanylate cyclase domain are predicted to be xenologs, suggesting a role for horizontal gene transfer in the evolution of Synechococcus sensory systems. Conclusions Our estimates of genomic islands in PCC 7942 are larger than those predicted by other published methods like SIGI-HMM. Our results set a guide to non-essential genes in S. elongatus PCC 7942 indicating a path towards the engineering of a model photoautotrophic bacterial cell.

  4. Growth engineering of Synechococcus elongatus PCC 7942 for mixotrophy under natural light conditions for improved feedstock production.

    Science.gov (United States)

    Sarnaik, Aditya; Pandit, Reena; Lali, Arvind

    2017-09-01

    Synechococcus elongatus PCC 7942 has been widely explored as cyanobacterial cell factory through genetic modifications for production of various value-added compounds. However, successful industrial scale-ups have not been reported for the system predominantly due to its obligate photoautotrophic metabolism and use of artificial light in photobioreactors. Hence, engineering the organism to perform mixotrophy under natural light could serve as an effective solution. Thus, we applied a genetically engineered strain of Synechococcus elongatus PCC 7942 expressing heterologous hexose transporter gene (galP) to perform mixotrophy under natural light in a temperature controlled environmental chamber (EC). We systematically studied the comparative performances of these transformants using autotrophy and mixotrophy, which showed 3.4 times increase in biomass productivity of mixotrophically grown transformants over autotrophs in EC. Chlorophyll a yield was found to have decreased in mixotrophic conditions, possibly indicating reduced dependency on light for energy metabolism. Although pigment yield decreases under mixotrophy, titer was found to have improved due to increased biomass productivity. Carotenoid analysis showed that zeaxanthin is the major carotenoid produced by the species which is essential for photoprotection. Our work thus demonstrates that mixotrophy under temperature controlled natural light can serve as the viable solution to improve biomass productivity of Synechococcus elongatus PCC 7942 and for commercial production of natural or engineered value added compounds from the system. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:1182-1192, 2017. © 2017 American Institute of Chemical Engineers.

  5. Using a Microfluidic Gradient Generator to Characterize BG-11 Medium for the Growth of Cyanobacteria Synechococcus elongatus PCC7942

    Directory of Open Access Journals (Sweden)

    Chih-Chun Yang

    2015-11-01

    Full Text Available The photosynthetic cyanobacterium Synechococcus elongatus PCC7942 has recently gained great attention for its ability to directly convert CO2 into renewable chemicals upon genetic engineering. Thus, it is of great interest to increase the growth speed and lower the medium requirement for cultivating this cyanobacterium. The cultivation medium of Synechococcus elongatus PCC7942 has been developed, which consists of many inorganic and metal ingredients with a specific composition, known as the BG-11 medium. In this work, we analyzed the concentration effect of each ingredient and identified the absolutely essential components in BG-11 medium for cyanobacteria growth using the concentration gradient generator chip (CGGC fabricated by MEMS technology. As shown by our results, removal of the individual component sodium nitrate, potassium phosphate, or magnesium sulfate from the BG-11 medium led to severe growth inhibition of Synechococcus elongatus PCC7942. Contrary to our expectation, increasing concentration of the crucial ingredients showed either insignificant or negative impact on cell growth. Overall, standard growth could be achieved without supplementation of ethylenediaminetetraacetic acid (EDTA disodium, sodium carbonate, or sodium citrate to the culture medium. Further improvement of the CGGC-based microfluidic system based on this preliminary study may broaden its application range to analyze more complicated correlations.

  6. Digalactosyldiacylglycerol is essential in Synechococcus elongatus PCC 7942, but its function does not depend on its biosynthetic pathway.

    Science.gov (United States)

    Maida, Eri; Awai, Koichiro

    2016-09-01

    Digalactosyldiacylglycerol (DGDG) is a major component of thylakoid membranes, occupying approximately 20% of the membrane system. This lipid composition is conserved from cyanobacteria to the chloroplasts of terrestrial plants, suggesting that DGDG is important for the function of photosynthetic membranes. Here we isolated the gene for DGDG synthase in the cyanobacterium Synechococcus elongatus PCC 7942 (7942dgdA) and found that this gene is essential for this species. 7942dgdA could be knocked out only when genes for cyanobacterial or plant DGDG synthases were expressed, indicating that the important factor was not the specific synthetic pathway but the lipid product. Lack of DGDG could not be compensated by the other membrane lipids in S. elongatus PCC 7942 or by glucosylgalactosyldiacylglycerol synthesized by the β-GlcT gene of Chloroflexus aurantiacus. These results reveal that DGDG has an indispensable role in S. elongatus PCC 7942 and that the second galactose molecule is key. Conservation and distribution of the galactolipid synthetic pathway among oxygenic phototrophs is discussed. This article is part of a Special Issue entitled: Plant Lipid Biology edited by Kent D. Chapman and Ivo Feussner. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Metabolic engineering of cyanobacteria for photosynthetic 3-hydroxypropionic acid production from CO2 using Synechococcus elongatus PCC 7942.

    Science.gov (United States)

    Lan, Ethan I; Chuang, Derrick S; Shen, Claire R; Lee, Annabel M; Ro, Soo Y; Liao, James C

    2015-09-01

    Photosynthetic conversion of CO2 to chemicals using cyanobacteria is an attractive approach for direct recycling of CO2 to useful products. 3-Hydroxypropionic acid (3 HP) is a valuable chemical for the synthesis of polymers and serves as a precursor to many other chemicals such as acrylic acid. 3 HP is naturally produced through glycerol metabolism. However, cyanobacteria do not possess pathways for synthesizing glycerol and converting glycerol to 3 HP. Furthermore, the latter pathway requires coenzyme B12, or an oxygen sensitive, coenzyme B12-independent enzyme. These characteristics present major challenges for production of 3 HP using cyanobacteria. To overcome such difficulties, we constructed two alternative pathways in Synechococcus elongatus PCC 7942: a malonyl-CoA dependent pathway and a β-alanine dependent pathway. Expression of the malonyl-CoA dependent pathway genes (malonyl-CoA reductase and malonate semialdehyde reductase) enabled S. elongatus to synthesize 3 HP to a final titer of 665 mg/L. β-Alanine dependent pathway expressing S. elongatus produced 3H P to final titer of 186 mg/L. These results demonstrated the feasibility of converting CO2 into 3 HP using cyanobacteria. Copyright © 2015 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

  8. Photophysiological and photosynthetic complex changes during iron starvation in Synechocystis sp. PCC 6803 and Synechococcus elongatus PCC 7942.

    Science.gov (United States)

    Fraser, Jared M; Tulk, Sarah E; Jeans, Jennifer A; Campbell, Douglas A; Bibby, Thomas S; Cockshutt, Amanda M

    2013-01-01

    Iron is an essential component in many protein complexes involved in photosynthesis, but environmental iron availability is often low as oxidized forms of iron are insoluble in water. To adjust to low environmental iron levels, cyanobacteria undergo numerous changes to balance their iron budget and mitigate the physiological effects of iron depletion. We investigated changes in key protein abundances and photophysiological parameters in the model cyanobacteria Synechococcus PCC 7942 and Synechocystis PCC 6803 over a 120 hour time course of iron deprivation. The iron stress induced protein (IsiA) accumulated to high levels within 48 h of the onset of iron deprivation, reaching a molar ratio of ~42 IsiA : Photosystem I in Synechococcus PCC 7942 and ~12 IsiA : Photosystem I in Synechocystis PCC 6803. Concomitantly the iron-rich complexes Cytochrome b6f and Photosystem I declined in abundance, leading to a decrease in the Photosystem I : Photosystem II ratio. Chlorophyll fluorescence analyses showed a drop in electron transport per Photosystem II in Synechococcus, but not in Synechocystis after iron depletion. We found no evidence that the accumulated IsiA contributes to light capture by Photosystem II complexes.

  9. ParA-like protein influences the distribution of multi-copy chromosomes in cyanobacterium Synechococcus elongatus PCC 7942.

    Science.gov (United States)

    Watanabe, Satoru; Noda, Aska; Ohbayashi, Ryudo; Uchioke, Kana; Kurihara, Ami; Nakatake, Shizuka; Morioka, Sayumi; Kanesaki, Yu; Chibazakura, Taku; Yoshikawa, Hirofumi

    2018-01-01

    While many bacteria, such as Escherichia coli and Bacillus subtilis, harbour a single-copy chromosome, freshwater cyanobacteria have multiple copies of each chromosome per cell. Although it has been reported that multi-copy chromosomes are evenly distributed along the major axis of the cell in cyanobacterium Synechococcus elongatus PCC 7942, the distribution mechanism of these chromosomes remains unclear. In S. elongatus, the carboxysome, a metabolic microcompartment for carbon fixation that is distributed in a similar manner to the multi-copy chromosomes, is regulated by ParA-like protein (hereafter ParA). To elucidate the role of ParA in the distribution of multi-copy chromosomes, we constructed and analysed ParA disruptant and overexpressing strains of S. elongatus. Our fluorescence in situ hybridization assay revealed that the parA disruptants displayed an aberrant distribution of their multi-copy chromosomes. In the parA disruptant the multiple origin and terminus foci, corresponding to the intracellular position of each chromosomal region, were aggregated, which was compensated by the expression of exogenous ParA from other genomic loci. The parA disruptant is sensitive to UV-C compared to the WT strain. Additionally, giant cells appeared under ParA overexpression at the late stage of growth indicating that excess ParA indirectly inhibits cell division. Screening of the ParA-interacting proteins by yeast two-hybrid analysis revealed four candidates that are involved in DNA repair and cell membrane biogenesis. These results suggest that ParA is involved in the pleiotropic cellular functions with these proteins, while parA is dispensable for cell viability in S. elongatus.

  10. In vivo features of signal transduction by the essential response regulator RpaB from Synechococcus elongatus PCC 7942.

    Science.gov (United States)

    Moronta-Barrios, Félix; Espinosa, Javier; Contreras, Asunción

    2012-05-01

    The NblS-RpaB signalling pathway, the most conserved two-component system in cyanobacteria, regulates photosynthesis and acclimatization to a variety of environmental conditions and is involved in negative regulation of high-light-induced genes. However, relevant regulatory details of the NblS-RpaB signalling pathway remain to be elucidated. We recently showed that the response regulator RpaB is regulated by specific (de)phosphorylation from the histidine kinase NblS and that RpaB and its phosphorylatable residue Asp56 are both required for viability of Synechococcus elongatus PCC 7942. We show here that the phosphorylated form of RpaB is present in cells growing under standard laboratory conditions and that high light stress affected the ratio of phosphorylated to non-phosphorylated RpaB. It also decreased the amount of rpaB transcripts without appreciably changing the total levels of RpaB. Quantitative Western blotting and confocal microscopy analyses were consistent with RpaB being a very abundant regulator, with nucleoid localization. A genetically engineered RpaB-GFP (green fluorescent protein) fusion protein rescued lethality of the rpaB null mutant, indicating that it was functional. This is, to our knowledge, the first study demonstrating in a cyanobacterium, and for a two-component response regulator, that the in vivo ratio of phosphorylated to non-phosphorylated protein changes in response to environmental conditions.

  11. Identification of small droplets of photosynthetic squalene in engineered Synechococcus elongatus PCC 7942 using TEM and selective fluorescent Nile red analysis.

    Science.gov (United States)

    Choi, Sun Young; Sim, Sang Jun; Choi, Jong-Il; Woo, Han Min

    2018-03-12

    To identify microbial squalene that has been widely used in various industrial applications, intracellular formation of photosynthetic squalene was investigated using the previously engineered Synechococcus elongatus PCC 7942 strain. Unlike the proposed localization of squalene in the membrane bilayer, small droplets were identified in the cytoplasm of S. elongatus PCC 7942 as squalene using transmission electron microscopy analysis. Determination of the diameters of the squalene droplets with manual examination of 1,016 droplets in different squalene-producing strains indicated larger squalene droplets in larger cells. Based on the observation of a sole droplet of squalene in a cyanobacterium, fluorescent Nile red was used for the selective staining of squalene. The fluorescent intensities were correlated with squalene contents determined using gas chromatography-mass spectrometry. Photosynthetic squalene was identified as a small droplet in S. elongatus PCC 7942 and this non-invasive quantitative method could be useful to promote high-throughput strain development for squalene production. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  12. Development of a high-frequency in vivo transposon mutagenesis system for Synechocystis sp. PCC 6803 and Synechococcus elongatus PCC 7942.

    Science.gov (United States)

    Watabe, Kazuyuki; Mimuro, Mamoru; Tsuchiya, Tohru

    2014-11-01

    Synechocystis sp. PCC 6803 (Synechocystis) is the first sequenced photosynthetic organism and has two advantages: natural transformation and light-activated heterotrophic growth. Such characteristics have mainly promoted reverse genetic analysis in this organism, however, to date approximately 50% of genes are still annotated as 'unknown protein' or 'hypothetical protein'. Therefore, forward genetic analysis is required for the identification of significant genes responsible for photosynthesis and other physiological phenomena among the genes of unknown function. The in vivo transposon mutagenesis system is one of the major methods for random mutagenesis. However, present in vivo transposon mutagenesis systems for cyanobacteria face problems such as relatively low frequency of transposition and repeated transposition in the host cells. In this study, we constructed vectors based on a mini-Tn5-derived vector that was designed to prevent repeated transposition. Our vectors carry a hyperactive transposase and optimized recognition sequence of transposase, which were reported to enhance frequency of transposition. Using the vector, we succeeded in highly frequent transposition (9×10(-3) per recipient cell) in Synechocystis. Transposon insertion sites of 10 randomly selected mutants indicated that the insertion sites spread throughout the genome with low sequence dependency. Furthermore, one of the 10 mutants exhibited the slow-growing phenotype, and the mutant was functionally complemented by using our expression vector. Our system also worked with another model cyanobacterium, Synechococcus elongatus PCC 7942, with high frequency. These results indicate that the developed system can be applied to the forward genetic analysis of a broad range of cyanobacteria. © The Author 2014. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  13. Efficient delivery of large DNA from Escherichia coli to Synechococcus elongatus PCC7942 by broad-host-range conjugal plasmid pUB307.

    Science.gov (United States)

    Itaya, Mitsuhiro; Kusakabe, Hiroko; Sato, Mitsuru; Tomita, Masaru; Sato, Rintaro

    2018-02-06

    Synechococcus elongatus PCC7942, a cyanobacterium that uses light and carbon dioxide to grow, has a high ability to incorporate DNA by transformation. To assess the effective delivery of large DNA in plasmid form, we cloned the endogenous plasmid pANL (46.4 kbp) into a BAC vector of Escherichia coli. The plasmid p38ANL (54.3 kbp) replaced the native plasmid. To assess the delivery of larger DNA into PCC7942, p38ANL was fused to the broad-host-range conjugal transfer plasmid pUB307IP (53.5 kbp). The resulting plasmid pUB307IP501 (107.9 kbp) was transmitted from E. coli to PCC7942 by simple mixing of donor and recipient cultures. PCC7942 transcipients possessed only pUB307IP501, replacing the preexisting pANL. In contrast, the pUB307IP501 plasmid was unable to transform PCC7942, indicating that natural transformation of DNA may be restricted by size limitations. The ability to deliver large DNA by conjugation may lead to genetic engineering in PCC7942. © The Authors 2018. Published by Oxford University Press on behalf of the Japanese Biochemical Society. All rights reserved.

  14. Effects of Reduced and Enhanced Glycogen Pools on Salt-Induced Sucrose Production in a Sucrose-Secreting Strain of Synechococcus elongatus PCC 7942.

    Science.gov (United States)

    Qiao, Cuncun; Duan, Yangkai; Zhang, Mingyi; Hagemann, Martin; Luo, Quan; Lu, Xuefeng

    2018-01-15

    Sucrose and glycogen syntheses in cyanobacteria share the common precursor glucose-1-phosphate. It is generally assumed that lowering glycogen synthesis could drive more carbon toward sucrose synthesis that can be induced by salt stress among cyanobacteria. By using a theophylline-dependent riboswitch system, the expression of glgC , a key gene in glycogen synthesis, was downregulated in a quantitative manner in a sucrose-secreting strain of Synechococcus elongatus PCC 7942. We observed that the stepwise suppression of glycogen synthesis limited rather than stimulated sucrose production in the salt-stressed cells, suggesting that glycogen could serve as a carbon pool for the synthesis of sucrose. Accordingly, we generated glycogen-overproducing strains, but the increased glycogen pool alone did not stimulate sucrose production, indicating that alternative steps limit the carbon flux toward the synthesis of sucrose. Consistent with previous studies that showed that sucrose-phosphate synthase (SPS) catalyzes the rate-limiting step in sucrose synthesis, the combination of glycogen overproduction and sps overexpression resulted in increased sucrose production. Our results indicate that the glycogen and sucrose pools are closely linked in Synechococcus elongatus PCC 7942, and we propose that enhancing the glycogen pool could be a promising strategy for the improvement of sucrose production by cyanobacteria in the presence of a strong sucrose synthesis sink. IMPORTANCE Many cyanobacteria naturally synthesize and accumulate sucrose when stressed by NaCl, which provides novel possibilities for obtaining sugar feedstock by engineering of cyanobacteria. It has been assumed that glycogen synthesis competes with sucrose synthesis for the carbon flux. However, our results showed that the suppression of glycogen synthesis decreased rather than stimulated sucrose production in a sucrose-secreting strain of Synechococcus elongatus PCC 7942. This result suggests that glycogen could

  15. Metabolic engineering of Synechococcus elongatus PCC 7942 for improvement of 1,3-propanediol and glycerol production based on in silico simulation of metabolic flux distribution.

    Science.gov (United States)

    Hirokawa, Yasutaka; Matsuo, Shingo; Hamada, Hiroyuki; Matsuda, Fumio; Hanai, Taizo

    2017-11-25

    Production directly from carbon dioxide by engineered cyanobacteria is one of the promising technologies for sustainable future. Previously, we have successfully achieved 1,3-propanediol (1,3-PDO) production using Synechococcus elongatus PCC 7942 with a synthetic metabolic pathway. The strain into which the synthetic metabolic pathway was introduced produced 3.48 mM (0.265 g/L) 1,3-PDO and 14.3 mM (1.32 g/L) glycerol during 20 days of incubation. In this study, the productivities of 1,3-PDO were improved by gene disruption selected by screening with in silico simulation. First, a stoichiometric metabolic model was applied to prediction of cellular metabolic flux distribution in a 1,3-PDO-producing strain of S. elongatus PCC 7942. A genome-scale model of S. elongatus PCC 7942 constructed by Knoop was modified by the addition of a synthetic metabolic pathway for 1,3-PDO production. Next, the metabolic flux distribution predicted by metabolic flux balance analysis (FBA) was used for in silico simulation of gene disruption. As a result of gene disruption simulation, NADPH dehydrogenase 1 (NDH-1) complexes were found by screening to be the most promising candidates for disruption to improve 1,3-PDO production. The effect of disruption of the gene encoding a subunit of the NDH-1 complex was evaluated in the 1,3-PDO-producing strain. During 20 days of incubation, the ndhF1-null 1,3-PDO-producing strain showed the highest titers: 4.44 mM (0.338 g/L) 1,3-PDO and 30.3 mM (2.79 g/L) glycerol. In this study, we successfully improved 1,3-PDO productivity on the basis of in silico simulation of gene disruption.

  16. Sulfite-stress induced functional and structural changes in the complexes of photosystems I and II in a cyanobacterium, Synechococcus elongatus PCC 7942.

    Science.gov (United States)

    Kobayashi, Satomi; Tsuzuki, Mikio; Sato, Norihiro

    2015-08-01

    Excess sulfite is well known to have toxic effects on photosynthetic activities and growth in plants, however, so far, the behavior of the photosynthetic apparatus during sulfite-stress has not been characterized as to the responsible proteins or genes. Here, the effects of sulfite on photosystem complexes were investigated in a cyanobacterium, Synechococcus elongatus PCC 7942, a possible model organism of chloroplasts. Culturing of the cells for 24 h in the presence of 10 mM sulfite retarded cell growth of the wild type, concomitantly with synthesis of Chl and phycobilisome repressed. The excess sulfite simultaneously repressed photosynthesis by more than 90%, owing largely to structural destabilization and resultant inactivation of the PSII complex, which seemed to consequently retard the cell growth. Notably, the PsbO protein, one of the subunits that construct the water-splitting system of PSII, was retained at a considerable level, and disruption of the psbO gene led to higher sensitivity of photosynthesis and growth to sulfite. Meanwhile, the PSI complex showed monomerization of its trimeric configuration with little effect on the activity. The structural alterations of these PS complexes depended on light. Our data provide evidence for quantitative decreases in the photosystem complex(es) including their antenna(e), structural alterations of the PSI and PSII complexes that would modulate their functions, and a crucial role of psbO in PSII protection, in Synechococcus cells during sulfite-stress. We suggest that the reconstruction of the photosystem complexes is beneficial to cell survival. © 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.

  17. Isobutanol production as an alternative metabolic sink to rescue the growth deficiency of the glycogen mutant of Synechococcus elongatus PCC 7942

    Energy Technology Data Exchange (ETDEWEB)

    Li, XQ; Shen, CR; Liao, JC

    2014-03-04

    Glycogen synthesis initiated by glucose-1-phosphate adenylyltransferase (glgC) represents a major carbon storage route in cyanobacteria which could divert a significant portion of assimilated carbon. Significant growth retardation in cyanobacteria with glgC knocked out (Delta glgC) has been reported in high light conditions. Here, we knocked out the glgC gene and analyzed its effects on carbon distribution in an isobutanol-producing strain of Synechococcus elongatus PCC7942 and its parental wild-type strain. We showed that isobutanol production was able to partially rescue the growth of Delta glgC mutant where the growth rescue effect positively correlated with the rate of isobutanol production. Using (NaHCO3)-C-14 incorporation analysis, we observed a 28 % loss of total carbon fixation rate in the Delta glgC mutant compared to the wild-type. Upon expression of the isobutanol production pathway in Delta glgC mutant, the total carbon fixation rate was restored to the wild-type level. Furthermore, we showed that 52 % of the total carbon fixed was redirected into isobutanol biosynthesis in the Delta glgC mutant expressing enzymes for isobutanol production, which is 2.5 times higher than that of the wild-type expressing the same enzymes. These results suggest that biosynthesis of non-native product such as isobutanol can serve as a metabolic sink for replacing glycogen to rescue growth and restore carbon fixation rate. The rescue effect may further serve as a platform for cyanobacteria energy and carbon metabolism study.

  18. Improved Free Fatty Acid Production in Cyanobacteria with Synechococcus sp. PCC 7002 as Host.

    Science.gov (United States)

    Ruffing, Anne M

    2014-01-01

    Microbial free fatty acids (FFAs) have been proposed as a potential feedstock for renewable energy. The ability to directly convert carbon dioxide into FFAs makes cyanobacteria ideal hosts for renewable FFA production. Previous metabolic engineering efforts using the cyanobacterial hosts Synechocystis sp. PCC 6803 and Synechococcus elongatus PCC 7942 have demonstrated this direct conversion of carbon dioxide into FFAs; however, FFA yields in these hosts are limited by the negative impact of FFA production on the host cell physiology. This work investigates the use of Synechococcus sp. PCC 7002 as a cyanobacterial host for FFA production. In comparison to S. elongatus PCC 7942, Synechococcus sp. PCC 7002 strains produced and excreted FFAs at similar concentrations but without the detrimental effects on host physiology. The enhanced tolerance to FFA production with Synechococcus sp. PCC 7002 was found to be temperature-dependent, with physiological effects such as reduced photosynthetic yield and decreased photosynthetic pigments observed at higher temperatures. Additional genetic manipulations were targeted for increased FFA production, including thioesterases and ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO). Overexpression of non-native RuBisCO subunits (rbcLS) from a psbAI promoter resulted in more than a threefold increase in FFA production, with excreted FFA concentrations reaching >130 mg/L. This work illustrates the importance of host strain selection for cyanobacterial biofuel production and demonstrates that the FFA tolerance of Synechococcus sp. PCC 7002 can allow for high yields of excreted FFA.

  19. Uptake of uranium from sea water by Synechococcus elongatus

    International Nuclear Information System (INIS)

    Horikoshi, Takao; Nakajima, Akira; Sakaguchi, Takashi

    1979-01-01

    Basic features of the uranium uptake by Synechococcus elongatus, and the factors affecting it were examined. Synechococcus elongatus was grown in Roux flasks containing 1 liter of culture solution in light (20,000 lux) and with aeration at 30 deg C. Synechococcus cells in the linear growth phase were collected by centrifugation at 6,000 x g for 5 minutes, washed with sea water, and used for the uranium-uptake experiments. The uptake of uranium from sea water containing 1 ppm of the element was strongly affected by the pH of sea water. The optimum uptake was at pH 5. Presence of carbonate ions markedly inhibited and decarbonation of sea water greatly enhanced the uptake. Absorption of uranium by Synechococcus cells was initially rapid, and reached a plateau within 24 hours. The uranium accumulation capacity of Synechococcus cells was increased by heat treatment, the capacity of scalded cells being about twice as much as that of living cells. Most of the uranium absorbed by Synechococcus was found in the inner space of the cells, and only a small amount was present in the cell walls. (Kaihara, S.)

  20. Dispensability of a sulfolipid for photoautotrophic cell growth and photosynthesis in a marine cyanobacterium, Synechococcus sp. PCC 7002.

    Science.gov (United States)

    Sato, Norihiro; Kamimura, Ryohei; Tsuzuki, Mikio

    2016-09-02

    Sulfoquinovosyl diacylglycerol, which mainly comprises thylakoid membranes in oxygenic photosynthetic organisms, plays species-dependent roles in freshwater microbes. In this study, a sulfoquinovosyl-diacylglycerol deficient mutant was generated in a cyanobacterium, Synechococcus sp. PCC 7002, for the first time among marine microbes to gain more insight into its physiological significance. The mutation had little deleterious impact on photoautotrophic cell growth, and functional and structural properties of the photosystem II complex. These findings were similar to previous observations for a freshwater cyanobacterium, Synechococcus elongatus PCC 7942, but were distinct from those for another freshwater cyanobacterium, Synechocystis sp. PCC 6803, and a green alga, Chlamydomonas reinhardtii, both of which require sulfoquinovosyl diacylglycerol for cell growth and/or photosystem II. Therefore, the functionality of PSII to dispense with sulfoquinovosyl diacylglycerol in Synechococcus sp. PCC 7002, similar to that in Synechococcus elongatus PCC 7942, seemed to have been excluded from the evolution of the PSII complex from cyanobacteria to green algal chloroplasts. Meanwhile, sulfoquinovosyl diacylglycerol was found to contribute to photoheterotrophic growth of Synechococcus sp. PCC 7002, which revealed a novel species-dependent strategy for utilizing SQDG in physiological processes. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. Adjustments to Photosystem Stoichiometry and Electron Transfer Proteins Are Key to the Remarkably Fast Growth of the Cyanobacterium Synechococcus elongatus UTEX 2973

    Directory of Open Access Journals (Sweden)

    Justin Ungerer

    2018-02-01

    Full Text Available At the genome level, Synechococcus elongatus UTEX 2973 (Synechococcus 2973 is nearly identical to the model cyanobacterium Synechococcus elongatus PCC 7942 (Synechococcus 7942 with only 55 single nucleotide differences separating the two strains. Despite the high similarity between the two strains, Synechococcus 2973 grows three times faster, accumulates significantly more glycogen, is tolerant to extremely high light intensities, and displays higher photosynthetic rates. The high homology between the two strains provides a unique opportunity to examine the factors that lead to increased photosynthetic rates. We compared the photophysiology of the two strains and determined the differences in Synechococcus 2973 that lead to increased photosynthetic rates and the concomitant increase in biomass production. In this study, we identified inefficiencies in the electron transport chain of Synechococcus 7942 that have been alleviated in Synechococcus 2973. Photosystem II (PSII capacity is the same in both strains. However, Synechococcus 2973 exhibits a 1.6-fold increase in PSI content, a 1.5-fold increase in cytochrome b6f content, and a 2.4-fold increase in plastocyanin content on a per cell basis. The increased content of electron carriers allows a higher flux of electrons through the photosynthetic electron transport chain, while the increased PSI content provides more oxidizing power to maintain upstream carriers ready to accept electrons. These changes serve to increase the photosynthetic efficiency of Synechococcus 2973, the fastest growing cyanobacterium known.

  2. CRISPR interference (CRISPRi) for gene regulation and succinate production in cyanobacterium S. elongatus PCC 7942.

    Science.gov (United States)

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

    2016-11-15

    Cyanobacterium Synechococcus elongatus PCC 7942 holds promise for biochemical conversion, but gene deletion in PCC 7942 is time-consuming and may be lethal to cells. CRISPR interference (CRISPRi) is an emerging technology that exploits the catalytically inactive Cas9 (dCas9) and single guide RNA (sgRNA) to repress sequence-specific genes without the need of gene knockout, and is repurposed to rewire metabolic networks in various procaryotic cells. To employ CRISPRi for the manipulation of gene network in PCC 7942, we integrated the cassettes expressing enhanced yellow fluorescent protein (EYFP), dCas9 and sgRNA targeting different regions on eyfp into the PCC 7942 chromosome. Co-expression of dCas9 and sgRNA conferred effective and stable suppression of EYFP production at efficiencies exceeding 99%, without impairing cell growth. We next integrated the dCas9 and sgRNA targeting endogenous genes essential for glycogen accumulation (glgc) and succinate conversion to fumarate (sdhA and sdhB). Transcription levels of glgc, sdhA and sdhB were effectively suppressed with efficiencies depending on the sgRNA binding site. Targeted suppression of glgc reduced the expression to 6.2%, attenuated the glycogen accumulation to 4.8% and significantly enhanced the succinate titer. Targeting sdhA or sdhB also effectively downregulated the gene expression and enhanced the succinate titer ≈12.5-fold to ≈0.58-0.63 mg/L. These data demonstrated that CRISPRi-mediated gene suppression allowed for re-directing the cellular carbon flow, thus paving a new avenue to rationally fine-tune the metabolic pathways in PCC 7942 for the production of biotechnological products.

  3. Construction of a novel d-lactate producing pathway from dihydroxyacetone phosphate of the Calvin cycle in cyanobacterium, Synechococcus elongatus PCC 7942.

    Science.gov (United States)

    Hirokawa, Yasutaka; Goto, Ryota; Umetani, Yoshitaka; Hanai, Taizo

    2017-07-01

    Using engineered cyanobacteria to produce various chemicals from carbon dioxide is a promising technology for a sustainable future. Lactate is a valuable commodity that can be used for the biodegradable plastic, polylactic acid. Typically, lactate production using engineered cyanobacteria was via the conversion of pyruvate in glycolysis by lactate dehydrogenase. In cyanobacteria, the metabolic flux in the Calvin cycle is higher than that in glycolysis under photoautotrophic conditions. The construction of a novel lactate producing pathway that uses metabolites from the Calvin cycle could potentially increase lactate productivity in cyanobacteria. In order to develop such a novel lactate production pathway, we engineered a cyanobacterium Synechococcus elongatus PCC 7942 strain that produced lactate directly from carbon dioxide using dihydroxyacetone phosphate (DHAP) via methylglyoxal. We confirmed that wild-type strain of S. elongatus PCC 7942 could produce lactate using exogenous methylglyoxal. A methylglyoxal synthase gene, mgsA, from Escherichia coli was introduced into Synechococcus elongates PCC 7942 for conversion of DHAP to methylglyoxal. This engineered strain produced lactate directly from carbon dioxide. Genes encoding intrinsic putative glyoxalase I, II (Synpcc7942_0638, 1403) and the lactate/H + symporter from E. coli (lldP) were additionally introduced to enhance the production. For higher lactate production, it was important to maintain elevated extracellular pH due to the characteristics of lactate exporting system. In this study, the highest lactate titer of 13.7 mM (1.23 g/l) was achieved during a 24-day incubation with the engineered S. elongatus PCC 7942 strain possessing the novel lactate producing pathway. Copyright © 2017 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  4. Collapsing aged culture of the cyanobacterium Synechococcus elongatus produces compound(s toxic to photosynthetic organisms.

    Directory of Open Access Journals (Sweden)

    Assaf Cohen

    Full Text Available Phytoplankton mortality allows effective nutrient cycling, and thus plays a pivotal role in driving biogeochemical cycles. A growing body of literature demonstrates the involvement of regulated death programs in the abrupt collapse of phytoplankton populations, and particularly implicates processes that exhibit characteristics of metazoan programmed cell death. Here, we report that the cell-free, extracellular fluid (conditioned medium of a collapsing aged culture of the cyanobacterium Synechococcus elongatus is toxic to exponentially growing cells of this cyanobacterium, as well as to a large variety of photosynthetic organisms, but not to eubacteria. The toxic effect, which is light-dependent, involves oxidative stress, as suggested by damage alleviation by antioxidants, and the very high sensitivity of a catalase-mutant to the conditioned medium. At relatively high cell densities, S. elongatus cells survived the deleterious effect of conditioned medium in a process that required de novo protein synthesis. Application of conditioned medium from a collapsing culture caused severe pigment bleaching not only in S. elongatus cells, but also resulted in bleaching of pigments in a cell free extract. The latter observation indicates that the elicited damage is a direct effect that does not require an intact cell, and therefore, is mechanistically different from the metazoan-like programmed cell death described for phytoplankton. We suggest that S. elongatus in aged cultures are triggered to produce a toxic compound, and thus, this process may be envisaged as a novel regulated death program.

  5. The stringent response regulates adaptation to darkness in the cyanobacterium Synechococcus elongatus.

    Science.gov (United States)

    Hood, Rachel D; Higgins, Sean A; Flamholz, Avi; Nichols, Robert J; Savage, David F

    2016-08-16

    The cyanobacterium Synechococcus elongatus relies upon photosynthesis to drive metabolism and growth. During darkness, Synechococcus stops growing, derives energy from its glycogen stores, and greatly decreases rates of macromolecular synthesis via unknown mechanisms. Here, we show that the stringent response, a stress response pathway whose genes are conserved across bacteria and plant plastids, contributes to this dark adaptation. Levels of the stringent response alarmone guanosine 3'-diphosphate 5'-diphosphate (ppGpp) rise after a shift from light to dark, indicating that darkness triggers the same response in cyanobacteria as starvation in heterotrophic bacteria. High levels of ppGpp are sufficient to stop growth and dramatically alter many aspects of cellular physiology, including levels of photosynthetic pigments and polyphosphate, DNA content, and the rate of translation. Cells unable to synthesize ppGpp display pronounced growth defects after exposure to darkness. The stringent response regulates expression of a number of genes in Synechococcus, including ribosomal hibernation promoting factor (hpf), which causes ribosomes to dimerize in the dark and may contribute to decreased translation. Although the metabolism of Synechococcus differentiates it from other model bacterial systems, the logic of the stringent response remains remarkably conserved, while at the same time having adapted to the unique stresses of the photosynthetic lifestyle.

  6. CRISPR/Cas9 mediated targeted mutagenesis of the fast growing cyanobacterium Synechococcus elongatus UTEX 2973.

    Science.gov (United States)

    Wendt, Kristen E; Ungerer, Justin; Cobb, Ryan E; Zhao, Huimin; Pakrasi, Himadri B

    2016-06-23

    As autotrophic prokaryotes, cyanobacteria are ideal chassis organisms for sustainable production of various useful compounds. The newly characterized cyanobacterium Synechococcus elongatus UTEX 2973 is a promising candidate for serving as a microbial cell factory because of its unusually rapid growth rate. Here, we seek to develop a genetic toolkit that enables extensive genomic engineering of Synechococcus 2973 by implementing a CRISPR/Cas9 editing system. We targeted the nblA gene because of its important role in biological response to nitrogen deprivation conditions. First, we determined that the Streptococcus pyogenes Cas9 enzyme is toxic in cyanobacteria, and conjugational transfer of stable, replicating constructs containing the cas9 gene resulted in lethality. However, after switching to a vector that permitted transient expression of the cas9 gene, we achieved markerless editing in 100 % of cyanobacterial exconjugants after the first patch. Moreover, we could readily cure the organisms of antibiotic resistance, resulting in a markerless deletion strain. High expression levels of the Cas9 protein in Synechococcus 2973 appear to be toxic and result in cell death. However, introduction of a CRISPR/Cas9 genome editing system on a plasmid backbone that leads to transient cas9 expression allowed for efficient markerless genome editing in a wild type genetic background.

  7. Structural basis and target-specific modulation of ADP sensing by the Synechococcus elongatus PII signaling protein.

    Science.gov (United States)

    Zeth, Kornelius; Fokina, Oleksandra; Forchhammer, Karl

    2014-03-28

    PII signaling proteins comprise one of the most versatile signaling devices in nature and have a highly conserved structure. In cyanobacteria, PipX and N-acetyl-L-glutamate kinase are receptors of PII signaling, and these interactions are modulated by ADP, ATP, and 2-oxoglutarate. These effector molecules bind interdependently to three anti-cooperative binding sites on the trimeric PII protein and thereby affect its structure. Here we used the PII protein from Synechococcus elongatus PCC 7942 to reveal the structural basis of anti-cooperative ADP binding. Furthermore, we clarified the mutual influence of PII-receptor interaction and sensing of the ATP/ADP ratio. The crystal structures of two forms of trimeric PII, one with one ADP bound and the other with all three ADP-binding sites occupied, revealed significant differences in the ADP binding mode: at one site (S1) ADP is tightly bound through side-chain and main-chain interactions, whereas at the other two sites (S2 and S3) the ADP molecules are only bound by main-chain interactions. In the presence of the PII-receptor PipX, the affinity of ADP to the first binding site S1 strongly increases, whereas the affinity for ATP decreases due to PipX favoring the S1 conformation of PII-ADP. In consequence, the PII-PipX interaction is highly sensitive to subtle fluctuations in the ATP/ADP ratio. By contrast, the PII-N-acetyl-L-glutamate kinase interaction, which is negatively affected by ADP, is insensitive to these fluctuations. Modulation of the metabolite-sensing properties of PII by its receptors allows PII to differentially perceive signals in a target-specific manner and to perform multitasking signal transduction.

  8. NMR studies on Na+ transport in Synechococcus PCC 6311

    Science.gov (United States)

    Nitschmann, W. H.; Packer, L.

    1992-01-01

    The freshwater cyanobacterium Synechococcus PCC 6311 is able to adapt to grow after sudden exposure to salt (NaCl) stress. We have investigated the mechanism of Na+ transport in these cells during adaptation to high salinity. Na+ influx under dark aerobic conditions occurred independently of delta pH or delta psi across the cytoplasmic membrane, ATPase activity, and respiratory electron transport. These findings are consistent with the existence of Na+/monovalent anion cotransport or simultaneous Na+/H+ +anion/OH- exchange. Na+ influx was dependent on Cl-, Br-, NO3-, or NO2-. No Na+ uptake occurred after addition of NaI, NaHCO3, or Na2SO4. Na+ extrusion was absolutely dependent on delta pH and on an ATPase activity and/or on respiratory electron transport. This indicates that Na+ extrusion via Na+/H+ exchange is driven by primary H+ pumps in the cytoplasmic membrane. Cells grown for 4 days in 0.5 m NaCl medium, "salt-grown cells," differ from control cells by a lower maximum velocity of Na+ influx and by lower steady-state ratios of [Na+]in/[Na+]out. These results indicate that cells grown in high-salt medium increase their capacity to extrude Na+. During salt adaptation Na+ extrusion driven by respiratory electron transport increased from about 15 to 50%.

  9. Zn2+-Inducible Expression Platform for Synechococcus sp. Strain PCC 7002 Based on the smtA Promoter/Operator and smtB Repressor.

    Science.gov (United States)

    Pérez, Adam A; Gajewski, John P; Ferlez, Bryan H; Ludwig, Marcus; Baker, Carol S; Golbeck, John H; Bryant, Donald A

    2017-02-01

    Synechococcus sp. strain PCC 7002 has been gaining significance as both a model system for photosynthesis research and for industrial applications. Until recently, the genetic toolbox for this model cyanobacterium was rather limited and relied primarily on tools that only allowed constitutive gene expression. This work describes a two-plasmid, Zn 2+ -inducible expression platform that is coupled with a zurA mutation, providing enhanced Zn 2+ uptake. The control elements are based on the metal homeostasis system of a class II metallothionein gene (smtA 7942 ) and its cognate SmtB 7942 repressor from Synechococcus elongatus strain PCC 7942. Under optimal induction conditions, yellow fluorescent protein (YFP) levels were about half of those obtained with the strong, constitutive phycocyanin (cpcBA 6803 ) promoter of Synechocystis sp. strain PCC 6803. This metal-inducible expression system in Synechococcus sp. strain PCC 7002 allowed the titratable gene expression of YFP that was up to 19-fold greater than the background level. This system was utilized successfully to control the expression of the Drosophila melanogaster β-carotene 15,15'-dioxygenase, NinaB, which is toxic when constitutively expressed from a strong promoter in Synechococcus sp. strain PCC 7002. Together, these properties establish this metal-inducible system as an additional useful tool that is capable of controlling gene expression for applications ranging from basic research to synthetic biology in Synechococcus sp. strain PCC 7002. This is the first metal-responsive expression system in cyanobacteria, to our knowledge, that does not exhibit low sensitivity for induction, which is one of the major hurdles for utilizing this class of genetic tools. In addition, high levels of expression can be generated that approximate those of established constitutive systems, with the added advantage of titratable control. Together, these properties establish this Zn 2+ -inducible system, which is based on the

  10. Genetic tools for advancement of Synechococcus sp. PCC 7002 as a cyanobacterial chassis.

    Science.gov (United States)

    Ruffing, Anne M; Jensen, Travis J; Strickland, Lucas M

    2016-11-10

    Successful implementation of modified cyanobacteria as hosts for industrial applications requires the development of a cyanobacterial chassis. The cyanobacterium Synechococcus sp. PCC 7002 embodies key attributes for an industrial host, including a fast growth rate and high salt, light, and temperature tolerances. This study addresses key limitations in the advancement of Synechococcus sp. PCC 7002 as an industrial chassis. Tools for genome integration were developed and characterized, including several putative neutral sites for genome integration. The minimum homology arm length for genome integration in Synechococcus sp. PCC 7002 was determined to be approximately 250 bp. Three fluorescent protein reporters (hGFP, Ypet, and mOrange) were characterized for gene expression, microscopy, and flow cytometry applications in Synechococcus sp. PCC 7002. Of these three proteins, the yellow fluorescent protein (Ypet) had the best optical properties for minimal interference with the native photosynthetic pigments and for detection using standard microscopy and flow cytometry optics. Twenty-five native promoters were characterized as tools for recombinant gene expression in Synechococcus sp. PCC 7002 based on previous RNA-seq results. This characterization included comparisons of protein and mRNA levels as well as expression under both continuous and diurnal light conditions. Promoters A2520 and A2579 were found to have strong expression in Synechococcus sp. PCC 7002 while promoters A1930, A1961, A2531, and A2813 had moderate expression. Promoters A2520 and A2813 showed more than twofold increases in gene expression under light conditions compared to dark, suggesting these promoters may be useful tools for engineering diurnal regulation. The genome integration, fluorescent protein, and promoter tools developed in this study will help to advance Synechococcus sp. PCC 7002 as a cyanobacterial chassis. The long minimum homology arm length for Synechococcus sp. PCC 7002 genome

  11. The potential of Synechococcus elongatus UTEX 2973 for sugar feedstock production.

    Science.gov (United States)

    Song, Kuo; Tan, Xiaoming; Liang, Yajing; Lu, Xuefeng

    2016-09-01

    It is important to obtain abundant sugar feedstocks economically and sustainably for bio-fermentation industry, especially for producing cheap biofuels and biochemicals. Besides plant biomass, photosynthetic cyanobacteria have also been considered to be potential microbe candidates for sustainable production of carbohydrate feedstocks. As the fastest growing cyanobacterium reported so far, Synechococcus elongatus UTEX 2973 (Syn2973) might have huge potential for bioproduction. In this study, we explored the potentials of this strain as photo-bioreactors for sucrose and glycogen production. Under nitrogen-replete condition, Syn2973 could accumulate glycogen with a rate of 0.75 g L(-1) day(-1) at the exponential phase and reach a glycogen content as high as 51 % of the dry cell weight (DCW) at the stationary phase. By introducing a sucrose transporter CscB, Syn2973 was endowed with an ability to secrete over 94 % sucrose out of cells under salt stress condition. The highest extracellular sucrose productivity reached 35.5 mg L(-1) h(-1) for the Syn2973 strain expressing cscB, which contained the similar amounts of intracellular glycogen with the wild type. Potassium chloride was firstly proved to induce sucrose accumulation as well as sodium chloride in Syn2973. By semi-continuous culturing, 8.7 g L(-1) sucrose was produced by the cscB-expressing strain of Syn2973 in 21 days. These results support that Syn2973 is a promising candidate with great potential for production of sugars.

  12. Overproduction, purification, and characterization of nanosized polyphosphate bodies from Synechococcus sp. PCC 7002.

    Science.gov (United States)

    Gao, Fengzheng; Wu, Haohao; Zeng, Mingyong; Huang, Min; Feng, Guangxin

    2018-02-20

    Inorganic polyphosphate bodies (PPB) have recently been linked to a variety of functions in mammalian cells. To improve the yield of PPB from Synechococcus sp. PCC 7002 and characterize its form, in this study, a recombinant plasmid containing a polyphosphate kinase (ppk) gene was generated and transformed into Synechococcus sp. PCC 7002. PPB separated by Sephadex G-100 was characterized and added to polarized human intestinal epithelial (Caco-2) cells, and the absorption effect was assessed. The ppk gene was stably expressed by induction with 1 μM nickel, and the resulting PPB yield from Synechococcus sp. PCC 7002 cells increased by 89.66%. Transmission electron microscopy and dynamic light scattering analyses showed that PPB from these cells were nanosized, ranging from a few to approximately 100 nanometres in diameter. PPB can be taken up by Caco-2 cells and are mainly distributed around lipid droplets. We determined that PPB can be overproduced in Synechococcus sp. PCC 7002 and that the resulting PPB were well absorbed by Caco-2 cells. Microalgae provide a promising "cell factory" for PPB production.

  13. CyanOmics: an integrated database of omics for the model cyanobacterium Synechococcus sp. PCC 7002.

    Science.gov (United States)

    Yang, Yaohua; Feng, Jie; Li, Tao; Ge, Feng; Zhao, Jindong

    2015-01-01

    Cyanobacteria are an important group of organisms that carry out oxygenic photosynthesis and play vital roles in both the carbon and nitrogen cycles of the Earth. The annotated genome of Synechococcus sp. PCC 7002, as an ideal model cyanobacterium, is available. A series of transcriptomic and proteomic studies of Synechococcus sp. PCC 7002 cells grown under different conditions have been reported. However, no database of such integrated omics studies has been constructed. Here we present CyanOmics, a database based on the results of Synechococcus sp. PCC 7002 omics studies. CyanOmics comprises one genomic dataset, 29 transcriptomic datasets and one proteomic dataset and should prove useful for systematic and comprehensive analysis of all those data. Powerful browsing and searching tools are integrated to help users directly access information of interest with enhanced visualization of the analytical results. Furthermore, Blast is included for sequence-based similarity searching and Cluster 3.0, as well as the R hclust function is provided for cluster analyses, to increase CyanOmics's usefulness. To the best of our knowledge, it is the first integrated omics analysis database for cyanobacteria. This database should further understanding of the transcriptional patterns, and proteomic profiling of Synechococcus sp. PCC 7002 and other cyanobacteria. Additionally, the entire database framework is applicable to any sequenced prokaryotic genome and could be applied to other integrated omics analysis projects. Database URL: http://lag.ihb.ac.cn/cyanomics. © The Author(s) 2015. Published by Oxford University Press.

  14. Evidence for accumulation of Synechococcus elongatus (Cyanobacteria: Cyanophyceae) in the tissues of the oyster Crassostrea gigas (Mollusca: Bivalvia).

    Science.gov (United States)

    Avila-Poveda, Omar Hernando; Torres-Ariño, Alejandra; Girón-Cruz, Diego Ademir; Cuevas-Aguirre, Angel

    2014-10-01

    Cyanobacteria appear to have direct relations with mollusks in several aspects. This is the first time, distinguishing Gram-negative cyanoprokaryotic Synechococcus elongatus as bright yellow-gold autofluorescence by Lillie's and Hiss' staining methods on paraffin-embedded tissues of Crassostrea gigas. Three diets: cyanoprokaryotes, cyanoprokaryotes with microalgae, and only microalgae were evaluated. Cyanoprokaryotes were intact, densely bundled, and immersed in the cytosol of the digestive gland, connective tissue, mantle, and gonad of C. gigas, revealing an accumulation systemic without tissue damage observed by histology. Unexpectedly, cyanoprokaryotes were slightly most accumulated with microalgae diet by each of the tissues of the C. gigas than with any other diets. Cyanoprokaryotes tend to be in mean slightly higher in the digestive gland than in any other tissues respectively for each diet, although these values are closely similar to connective tissue. A possible order of exposure of the oyster tissues to accumulation of cyanoprokaryotes was digestive gland, connective tissue, mantle, and gonad. Thereby, the digestive gland could be the major target tissue for the accumulation. Our observations provide a valuable insight regarding the ability of cyanoprokaryotes to penetrate, spread, and remain inside the oyster tissues, suggesting for S. elongatus: (1) a pre-accumulation in oyster tissues from the natural environment, (2) a phagocytosis and/or endocytosis process rather than ingestion and extracellular digestion, (3) an apparent cellular division in the cytosol of oyster tissues, (4) an apparent inter-tissue movement, and (5) a possible endosymbiosis between C. gigas and S. elongatus. Hereby, it is possible that S. elongatus have a well-developed host-endobiont relationship with oysters, and thereby support future work toward a description of the escape and spreading mechanisms of S. elongatus inside the tissues of mollusks, and put forward questions as

  15. Complementation of Cobalamin Auxotrophy in Synechococcus sp. Strain PCC 7002 and Validation of a Putative Cobalamin Riboswitch In Vivo.

    Science.gov (United States)

    Pérez, Adam A; Liu, Zhenfeng; Rodionov, Dmitry A; Li, Zhongkui; Bryant, Donald A

    2016-10-01

    The euryhaline cyanobacterium Synechococcus sp. strain PCC 7002 has an obligate requirement for exogenous vitamin B12 (cobalamin), but little is known about the roles of this compound in cyanobacteria. Bioinformatic analyses suggest that only the terminal enzyme in methionine biosynthesis, methionine synthase, requires cobalamin as a coenzyme in Synechococcus sp. strain PCC 7002. Methionine synthase (MetH) catalyzes the transfer of a methyl group from N(5)-methyl-5,6,7,8-tetrahydrofolate to l-homocysteine during l-methionine synthesis and uses methylcobalamin as an intermediate methyl donor. Numerous bacteria and plants alternatively employ a cobalamin-independent methionine synthase isozyme, MetE, that catalyzes the same methyl transfer reaction as MetH but uses N(5)-methyl-5,6,7,8-tetrahydrofolate directly as the methyl donor. The cobalamin auxotrophy of Synechococcus sp. strain PCC 7002 was complemented by using the metE gene from the closely related cyanobacterium Synechococcus sp. strain PCC 73109, which possesses genes for both methionine synthases. This result suggests that methionine biosynthesis is probably the sole use of cobalamin in Synechococcus sp. strain PCC 7002. Furthermore, a cobalamin-repressible gene expression system was developed in Synechococcus sp. strain PCC 7002 that was used to validate the presence of a cobalamin riboswitch in the promoter region of metE from Synechococcus sp. strain PCC 73109. This riboswitch acts as a cobalamin-dependent transcriptional attenuator for metE in that organism. Synechococcus sp. strain PCC 7002 is a cobalamin auxotroph because, like eukaryotic marine algae, it uses a cobalamin-dependent methionine synthase (MetH) for the final step of l-methionine biosynthesis but cannot synthesize cobalamin de novo Heterologous expression of metE, encoding cobalamin-independent methionine synthase, from Synechococcus sp. strain PCC 73109, relieved this auxotrophy and enabled the construction of a truly autotrophic

  16. Identification and Regulation of Genes for Cobalamin Transport in the Cyanobacterium Synechococcus sp. Strain PCC 7002.

    Science.gov (United States)

    Pérez, Adam A; Rodionov, Dmitry A; Bryant, Donald A

    2016-10-01

    The cyanobacterium Synechococcus sp. strain PCC 7002 is a cobalamin auxotroph and utilizes this coenzyme solely for the synthesis of l-methionine by methionine synthase (MetH). Synechococcus sp. strain PCC 7002 is unable to synthesize cobalamin de novo, and because of the large size of this tetrapyrrole, an active-transport system must exist for cobalamin uptake. Surprisingly, no cobalamin transport system was identified in the initial annotation of the genome of this organism. With more sophisticated in silico prediction tools, a btuB-cpdA-btuC-btuF operon encoding components putatively required for a B12 uptake (btu) system was identified. The expression of these genes was predicted to be controlled by a cobalamin riboswitch. Global transcriptional profiling by high-throughput RNA sequencing of a cobalamin-independent form of Synechococcus sp. strain PCC 7002 grown in the absence or presence of cobalamin confirmed regulation of the btu operon by cobalamin. Pérez et al. (A. A. Pérez, Z. Liu, D. A. Rodionov, Z. Li, and D. A. Bryant, J Bacteriol 198:2743-2752, 2016, http://dx.doi.org/10.1128/JB.00475-16) developed a cobalamin-dependent yellow fluorescent protein reporter system in a Synechococcus sp. strain PCC 7002 variant that had been genetically modified to allow cobalamin-independent growth. This reporter system was exploited to validate components of the btu uptake system by assessing the ability of targeted mutants to transport cobalamin. The btuB promoter and a variant counterpart mutated in an essential element of the predicted cobalamin riboswitch were fused to a yfp reporter. The combined data indicate that the btuB-cpdA-btuF-btuC operon in this cyanobacterium is transcriptionally regulated by a cobalamin riboswitch. With a cobalamin-regulated reporter system for expression of yellow fluorescent protein, genes previously misidentified as encoding subunits of a siderophore transporter were shown to encode components of cobalamin uptake in the

  17. Synthetic biology toolbox for controlling gene expression in the cyanobacterium Synechococcus sp. strain PCC 7002.

    Science.gov (United States)

    Markley, Andrew L; Begemann, Matthew B; Clarke, Ryan E; Gordon, Gina C; Pfleger, Brian F

    2015-05-15

    The application of synthetic biology requires characterized tools to precisely control gene expression. This toolbox of genetic parts previously did not exist for the industrially promising cyanobacterium, Synechococcus sp. strain PCC 7002. To address this gap, two orthogonal constitutive promoter libraries, one based on a cyanobacterial promoter and the other ported from Escherichia coli, were built and tested in PCC 7002. The libraries demonstrated 3 and 2.5 log dynamic ranges, respectively, but correlated poorly with E. coli expression levels. These promoter libraries were then combined to create and optimize a series of IPTG inducible cassettes. The resultant induction system had a 48-fold dynamic range and was shown to out-perform Ptrc constructs. Finally, a RBS library was designed and tested in PCC 7002. The presented synthetic biology toolbox will enable accelerated engineering of PCC 7002.

  18. Expression of Anabaena PCC 7937 plastocyanin in Synechococcus PCC 7942 enhances photosynthetic electron transfer and alters the electron distribution between photosystem I and cytochrome-c oxidase

    NARCIS (Netherlands)

    Geerts, D.; Schubert, H.; de Vrieze, G.; Borrias, M.; Matthijs, H. C.; Weisbeek, P. J.

    1994-01-01

    The petE gene encoding plastocyanin precursor protein from the cyanobacterium Anabaena PCC 7937 was introduced in the cyanobacterial host strain Synechococcus PCC 7942. The host normally only uses cytochrome c553 as Photosystem I (PS I) donor. The heterologous gene was efficiently expressed using

  19. Differences in energy transfer of a cyanobacterium, Synechococcus sp. PCC 7002, grown in different cultivation media.

    Science.gov (United States)

    Niki, Kenta; Aikawa, Shimpei; Yokono, Makio; Kondo, Akihiko; Akimoto, Seiji

    2015-08-01

    Currently, cyanobacteria are regarded as potential biofuel sources. Large-scale cultivation of cyanobacteria in seawater is of particular interest because seawater is a low-cost medium. In the present study, we examined differences in light-harvesting and energy transfer processes in the cyanobacterium Synechococcus sp. PCC 7002 grown in different cultivation media, namely modified A medium (the optimal growth medium for Synechococcus sp. PCC 7002) and f/2 (a seawater medium). The concentrations of nitrate and phosphate ions were varied in both media. Higher nitrate ion and/or phosphate ion concentrations yielded high relative content of phycobilisome. The cultivation medium influenced the energy transfers within phycobilisome, from phycobilisome to photosystems, within photosystem II, and from photosystem II to photosystem I. We suggest that the medium also affects charge recombination at the photosystem II reaction center and formation of a chlorophyll-containing complex.

  20. Inducible expression of heterologous genes targeted to a chromosomal platform in the cyanobacterium Synechococcus sp. PCC 7942

    NARCIS (Netherlands)

    Geerts, D.; Bovy, A.; de Vrieze, G.; Borrias, M.; Weisbeek, P.

    1995-01-01

    High-level, inducible expression of heterologous genes in the cyanobacterium Synechococcus sp. strain PCC 7942 was obtained using the Escherichia coli trc promoter and lacI repressor. The petE gene of Anabaena sp. strain PCC 7937 encoding plastocyanin precursor protein and the E. coli uidA gene

  1. Glycogen production for biofuels by the euryhaline cyanobacteria Synechococcus sp. strain PCC 7002 from an oceanic environment.

    Science.gov (United States)

    Aikawa, Shimpei; Nishida, Atsumi; Ho, Shih-Hsin; Chang, Jo-Shu; Hasunuma, Tomohisa; Kondo, Akihiko

    2014-01-01

    Oxygenic photosynthetic microorganisms such as cyanobacteria and microalgae have attracted attention as an alternative carbon source for the next generation of biofuels. Glycogen abundantly accumulated in cyanobacteria is a promising feedstock which can be converted to ethanol through saccharification and fermentation processes. In addition, the utilization of marine cyanobacteria as a glycogen producer can eliminate the need for a freshwater supply. Synechococcus sp. strain PCC 7002 is a fast-growing marine coastal euryhaline cyanobacteria, however, the glycogen yield has not yet been determined. In the present study, the effects of light intensity, CO2 concentration, and salinity on the cell growth and glycogen content were investigated in order to maximize glycogen production in Synechococcus sp. strain PCC 7002. The optimal culture conditions for glycogen production in Synechococcus sp. strain PCC 7002 were investigated. The maximum glycogen production of 3.5 g L(-1) for 7 days (a glycogen productivity of 0.5 g L(-1) d(-1)) was obtained under a high light intensity, a high CO2 level, and a nitrogen-depleted condition in brackish water. The glycogen production performance in Synechococcus sp. strain PCC 7002 was the best ever reported in the α-polyglucan (glycogen or starch) production of cyanobacteria and microalgae. In addition, the robustness of glycogen production in Synechococcus sp. strain PCC 7002 to salinity was evaluated in seawater and freshwater. The peak of glycogen production of Synechococcus sp. strain PCC 7002 in seawater and freshwater were 3.0 and 1.8 g L(-1) in 7 days, respectively. Glycogen production in Synechococcus sp. strain PCC 7002 maintained the same level in seawater and half of the level in freshwater compared with the optimal result obtained in brackish water. We conclude that Synechococcus sp. strain PCC 7002 has high glycogen production activity and glycogen can be provided from coastal water accompanied by a fluctuation

  2. Spermidine Synthase is Required for Growth of Synechococcus sp. PCC 7942 Under Osmotic Stress.

    Science.gov (United States)

    Pothipongsa, Apiradee; Jantaro, Saowarath; Incharoensakdi, Aran

    2016-11-01

    The Synechococcus sp. PCC 7942 spermidine synthase encoded by spds gene (Synpcc7942_0628) is responsible for spermidine biosynthesis. Two Synechococcus strains, the overexpressing spds (OX-spds) and the spds knockout (Δspds), were constructed and characterized for their growth and photosynthetic efficiency under osmotic stress imposed by sorbitol. The growth of Δspds was completely inhibited when cells were grown in the presence of 400 mM sorbitol. Under the same condition, the OX-spds showed a slightly higher growth than the wild type. The OX-spds under osmotic stress also had a significant increase of spermidine level in conjunction with the up-regulation of the genes involved in spermidine biosynthesis. A higher ratio of spermidine to putrescine, an index for stress tolerance, under osmotic stress was found in the OX-spds strain than in the wild type. Overall results indicated that the spermidine synthase enzyme plays an essential role in the survival of Synechococcus sp. PCC 7942 under osmotic stress.

  3. Transcriptional regulation of acetyl CoA and lipid synthesis by PIIprotein in Synechococcus PCC 7942.

    Science.gov (United States)

    Verma, Ekta; Chakraborty, Sindhunath; Tiwari, Balkrishna; Mishra, Arun K

    2018-02-01

    P II protein family is widespread in prokaryotes and plants. In this study, impacts of P II deficiency on the synthesis of acetyl CoA and acetyl CoA carboxylase enzyme (ACCase) was analyzed in the Synechococcus sp. PCC 7942 by evaluating the mRNA levels of pyruvate kinase (PK), pyruvate dehydrogenase (PDH), citrate synthase (CS), biotin synthase (BS), biotin carboxylase (BC), biotin carboxyl carrier protein (BCCP), carboxyl transferase (CT) α and β subunits. The P II deficient Synechococcus sp. PCC 7942 showed upregulation of all the above-mentioned genes, except CS. Analyses of genes required for acetyl coA synthesis exhibited a substantial increase in the transcript levels of PK and PDH in the P II mutant strain. In addition, the P II mutant also displayed reduced acetyl CoA content, high ACCase activity, and increased lipid content. The lessening of acetyl CoA content was attributed to the rapid utilization of acetyl CoA in fatty acid synthesis as well as in the TCA cycle whereas the increased ACCase activity was ascribed to the rise in mRNA levels of BS, BC, BCCP, CT α, and β genes. However, increased lipid content was correlated with the declined total protein content. Hence, the study suggested that P II protein regulates the synthesis of acetyl CoA and ACCase enzyme at the transcriptional level. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. 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.

  5. Computational evaluation of Synechococcus sp. PCC 7002 metabolism for chemical production

    Energy Technology Data Exchange (ETDEWEB)

    Vu, Trang; Hill, Eric A.; Kucek, Leo A.; Konopka, Allan; Beliaev, Alex S.; Reed, Jennifer L.

    2013-05-24

    Cyanobacteria are ideal metabolic engineering platforms for carbon-neutral biotechnology because they directly convert CO2 to a range of valuable products. In this study, we present a computational assessment of biochemical production in Synechococcus sp. PCC 7002 (Synechococcus 7002), a fast growing cyanobacterium whose genome has been sequenced, and for which genetic modification methods have been developed. We evaluated the maximum theoretical yields (mol product per mol CO2 or mol photon) of producing various chemicals under photoautotrophic and dark conditions using a genome-scale metabolic model of Synechococcus 7002. We found that the yields were lower under dark conditions, compared to photoautotrophic conditions, due to the limited amount of energy and reductant generated from glycogen. We also examined the effects of photon and CO2 limitations on chemical production under photoautotrophic conditions. In addition, using various computational methods such as MOMA, RELATCH, and OptORF, we identified gene-knockout mutants that are predicted to improve chemical production under photoautotrophic and/or dark anoxic conditions. These computational results are useful for metabolic engineering of cyanobacteria to synthesize valueadded products.

  6. 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

  7. Selection of proper reference genes for the cyanobacterium Synechococcus PCC 7002 using real-time quantitative PCR.

    Science.gov (United States)

    Szekeres, Edina; Sicora, Cosmin; Dragoş, Nicolae; Drugă, Bogdan

    2014-10-01

    Synechococcus sp. PCC 7002 is known to be tolerant to most of the environmental factors in natural habitats of Cyanobacteria. Gene expression can be easily studied in this cyanobacterium, as its complete genome sequence is available. These properties make Synechococcus sp. PCC 7002 an appropriate model organism for biotechnological applications. To study the gene expression in Cyanobacteria, real-time quantitative PCR (qPCR) can be used, but as this is a highly sensitive method, data standardization is indicated between samples. The most commonly used strategy is normalization against internal reference genes. Synechococcus sp. PCC 7002 has not yet been evaluated for the best reference genes. In this work, six candidate genes were analyzed for this purpose. Cyanobacterial cultures were exposed to several stress conditions, and three different algorithms were used for ranking the reference genes: geNorm, NormFinder, and BestKeeper. Moreover, gene expression stability value M and single-control normalization error E were calculated. Our data provided a list of reference genes that can be used in qPCR experiments in Synechococcus sp. PCC 7002. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  8. 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.

  9. Biodiesel production using blue-green cyanobacterium Synechococcus elongatus PCC 7942

    NARCIS (Netherlands)

    Voshol, Gerben

    2015-01-01

    Due to concerns about global climate change and diminishing supplies of petroleum, there is a need to develop a clean sustainable alternative. The two main alternative fuels are bioethanol and biodiesel. Production of these biofuels using cyanobacteria is a new promising development. I describe the

  10. 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...

  11. Construction of new synthetic biology tools for the control of gene expression in the cyanobacterium Synechococcus sp. strain PCC 7002.

    Science.gov (United States)

    Zess, Erin K; Begemann, Matthew B; Pfleger, Brian F

    2016-02-01

    Predictive control of gene expression is an essential tool for developing synthetic biological systems. The current toolbox for controlling gene expression in cyanobacteria is a barrier to more in-depth genetic analysis and manipulation. Towards relieving this bottleneck, this work describes the use of synthetic biology to construct an anhydrotetracycline-based induction system and adapt a trans-acting small RNA (sRNA) system for use in the cyanobacterium Synechococcus sp. strain PCC 7002. An anhydrotetracycline-inducible promoter was developed to maximize intrinsic strength and dynamic range. The resulting construct, PEZtet , exhibited tight repression and a maximum 32-fold induction upon addition of anhydrotetracycline. Additionally, a sRNA system based on the Escherichia coli IS10 RNA-IN/OUT regulator was adapted for use in Synechococcus sp. strain PCC 7002. This system exhibited 70% attenuation of target gene expression, providing a demonstration of the use of sRNAs for differential gene expression in cyanobacteria. These systems were combined to produce an inducible sRNA system, which demonstrated 59% attenuation of target gene expression. Lastly, the role of Hfq, a critical component of sRNA systems in E. coli, was investigated. Genetic studies showed that the Hfq homolog in Synechococcus sp. strain PCC 7002 did not impact repression by the engineered sRNA system. In summary, this work describes new synthetic biology tools that can be applied to physiological studies, metabolic engineering, or sRNA platforms in Synechococcus sp. strain PCC 7002. © 2015 Wiley Periodicals, Inc.

  12. Production of γ-linolenic acid and stearidonic acid by Synechococcus sp. PCC7002 containing cyanobacterial fatty acid desaturase genes

    Science.gov (United States)

    Dong, Xuewei; He, Qingfang; Peng, Zhenying; Yu, Jinhui; Bian, Fei; Li, Youzhi; Bi, Yuping

    2016-07-01

    Genetic modification is useful for improving the nutritional qualities of cyanobacteria. To increase the total unsaturated fatty acid content, along with the ratio of ω-3/ω-6 fatty acids, genetic engineering can be used to modify fatty acid metabolism. Synechococcus sp. PCC7002, a fast-growing cyanobacterium, does not contain a Δ6 desaturase gene and is therefore unable to synthesize γ-linolenic acid (GLA) and stearidonic acid (SDA), which are important in human health. In this work, we constructed recombinant vectors Syd6D, Syd15D and Syd6Dd15D to express the Δ15 desaturase and Δ6 desaturase genes from Synechocystis PCC6803 in Synechococcus sp. PCC7002, with the aim of expressing polyunsaturated fatty acids. Overexpression of the Δ15 desaturase gene in Synechococcus resulted in 5.4 times greater accumulation of α-linolenic acid compared with the wild-type while Δ6 desaturase gene expression produced both GLA and SDA. Co-expression of the two genes resulted in low-level accumulation of GLA but much larger amounts of SDA, accounting for as much to 11.64% of the total fatty acid content.

  13. Lauric acid production in a glycogen-less Synechococcus sp. PCC 7002 mutant

    Directory of Open Access Journals (Sweden)

    Victoria H. Work

    2015-04-01

    Full Text Available The cyanobacterium Synechococcus sp. PCC 7002 was genetically engineered to synthesize biofuel compatible medium-chain fatty acids during photoautotrophic growth. Expression of a heterologous lauroyl-acyl carrier protein (C12:0-ACP thioesterase with concurrent deletion of the endogenous putative acyl-ACP synthetase led to secretion of transesterifiable C12:0 fatty acid in CO2-supplemented batch cultures. When grown at steady state over a range of light intensities in an LED turbidostat photobioreactor, the C12-secreting mutant exhibited a modest reduction in growth rate and increased O2 evolution relative to the wildtype. Inhibition of i glycogen synthesis by deletion of the glgC-encoded ADP-glucose pyrophosphorylase (AGPase, and ii protein synthesis by nitrogen deprivation were investigated as potential mechanisms for metabolite redistribution to increase fatty acid synthesis. Deletion of AGPase led to a ten-fold decrease in reducing carbohydrates and secretion of organic acids during nitrogen deprivation consistent with an energy spilling phenotype. When the carbohydrate-deficient background (∆glgC was modified for C12 secretion, no increase in C12 was achieved during nutrient replete growth, and no C12 was recovered from any strain upon nitrogen deprivation under the conditions used. At steady state, the growth rate of the ∆glgC strain saturated at a lower light intensity than the wildtype, but O2 evolution was not compromised and became increasingly decoupled from growth rate with rising irradiance. Photophysiological properties of the ∆glgC strain suggest energy dissipation from photosystem II and reconfiguration of electron flow at the level of the plastoquinone pool.

  14. Effect of mono- and dichromatic light quality on growth rates and photosynthetic performance of Synechococcus sp. PCC 7002

    Directory of Open Access Journals (Sweden)

    Hans C Bernstein

    2014-09-01

    Full Text Available Synechococcus sp. PCC 7002 was grown to steady state in optically thin turbidostat cultures under conditions for which light quantity and quality was systematically varied by modulating the output of narrow-band LEDs. Cells were provided photons absorbed primarily by chlorophyll (680 nm or phycocyanin (630 nm as the organism was subjected to four distinct mono- and dichromatic regimes. During cultivation with dichromatic light, growth rates displayed by Synechococcus sp. PCC 7002 were generally proportional to the total incident irradiance at values < 275 µmol photons m-2 s-1 and were not affected by the ratio of 630:680 nm wavelengths. Notably, under monochromatic light conditions, cultures exhibited similar growth rates only when they were irradiated with 630 nm light; cultures irradiated with only 680 nm light grew at rates that were 60 – 70% of those under other light quality regimes at equivalent irradiances. The functionality of photosystem II and associated processes such as maximum rate of photosynthetic electron transport, rate of cyclic electron flow, and rate of dark respiration generally increased as a function of growth rate. Nonetheless, some of the photophysiological parameters measured here displayed distinct patterns with respect to growth rate of cultures adapted to a single wavelength including phycobiliprotein content, which increased under severely light-limited growth conditions. Additionally, the ratio of photosystem II to photosystem I increased approximately 40% over the range of growth rates, although cells grown with 680 nm light only had the highest ratios. These results suggest the presence of effective mechanisms which allow acclimation of Synechococcus sp. PCC 7002 acclimation to different irradiance conditions.

  15. 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.

  16. 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.

  17. 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 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 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. PMID:25152894

  18. 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.

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

    Directory of Open Access Journals (Sweden)

    Fiona K Davies

    2014-06-01

    Full Text Available 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.

  20. Growth of Chlamydomonas reinhardtii in acetate-free medium when co-cultured with alginate-encapsulated, acetate-producing strains of Synechococcus sp. PCC 7002.

    Science.gov (United States)

    Therien, Jesse B; Zadvornyy, Oleg A; Posewitz, Matthew C; Bryant, Donald A; Peters, John W

    2014-01-01

    The model alga Chlamydomonas reinhardtii requires acetate as a co-substrate for optimal production of lipids, and the addition of acetate to culture media has practical and economic implications for algal biofuel production. Here we demonstrate the growth of C. reinhardtii on acetate provided by mutant strains of the cyanobacterium Synechococcus sp. PCC 7002. Optimal growth conditions for co-cultivation of C. reinhardtii with wild-type and mutant strains of Synechococcus sp. 7002 were established. In co-culture, acetate produced by a glycogen synthase knockout mutant of Synechococcus sp. PCC 7002 was able to support the growth of a lipid-accumulating mutant strain of C. reinhardtii defective in starch production. Encapsulation of Synechococcus sp. PCC 7002 using an alginate matrix was successfully employed in co-cultures to limit growth and maintain the stability. The ability of immobilized strains of the cyanobacterium Synechococcus sp. PCC 7002 to produce acetate at a level adequate to support the growth of lipid-accumulating strains of C. reinhartdii offers a potentially practical, photosynthetic alternative to providing exogenous acetate into growth media.

  1. Diversity in photosynthetic electron transport under [CO2]-limitation: the cyanobacterium Synechococcus sp. PCC 7002 and green alga Chlamydomonas reinhardtii drive an O2-dependent alternative electron flow and non-photochemical quenching of chlorophyll fluorescence during CO2-limited photosynthesis.

    Science.gov (United States)

    Shimakawa, Ginga; Akimoto, Seiji; Ueno, Yoshifumi; Wada, Ayumi; Shaku, Keiichiro; Takahashi, Yuichiro; Miyake, Chikahiro

    2016-12-01

    Some cyanobacteria, but not all, experience an induction of alternative electron flow (AEF) during CO 2 -limited photosynthesis. For example, Synechocystis sp. PCC 6803 (S. 6803) exhibits AEF, but Synechococcus elongatus sp. PCC 7942 does not. This difference is due to the presence of flavodiiron 2 and 4 proteins (FLV2/4) in S. 6803, which catalyze electron donation to O 2 . In this study, we observed a low-[CO 2 ] induced AEF in the marine cyanobacterium Synechococcus sp. PCC 7002 that lacks FLV2/4. The AEF shows high affinity for O 2 , compared with AEF mediated by FLV2/4 in S. 6803, and can proceed under extreme low [O 2 ] (about a few µM O 2 ). Further, the transition from CO 2 -saturated to CO 2 -limited photosynthesis leads a preferential excitation of PSI to PSII and increased non-photochemical quenching of chlorophyll fluorescence. We found that the model green alga Chlamydomonas reinhardtii also has an O 2 -dependent AEF showing the same affinity for O 2 as that in S. 7002. These data represent the diverse molecular mechanisms to drive AEF in cyanobacteria and green algae. In this paper, we further discuss the diversity, the evolution, and the physiological function of strategy to CO 2 -limitation in cyanobacterial and green algal photosynthesis.

  2. Biochemical analysis of three putative KaiC clock proteins from Synechocystis sp. PCC 6803 suggests their functional divergence.

    Science.gov (United States)

    Wiegard, Anika; Dörrich, Anja K; Deinzer, Hans-Tobias; Beck, Christian; Wilde, Annegret; Holtzendorff, Julia; Axmann, Ilka M

    2013-05-01

    Cyanobacteria have been shown to have a circadian clock system that consists mainly of three protein components: KaiA, KaiB and KaiC. This system is well understood in the cyanobacterium Synechococcus elongatus PCC 7942, for which robust circadian oscillations have been shown. Like many other cyanobacteria, the chromosome of the model cyanobacterium Synechocystis sp. PCC 6803 contains additional kaiC and kaiB gene copies besides the standard kaiABC gene cluster. The respective gene products differ significantly in their amino acid sequences, especially in their C-terminal regions, suggesting different functional characteristics. Here, phosphorylation assays of the three Synechocystis sp. PCC 6803 KaiC proteins revealed that KaiC1 phosphorylation depends on KaiA, as is well documented for the Synechococcus elongatus PCC 7942 KaiC protein, whereas KaiC2 and KaiC3 autophosphorylate independently of KaiA. This was confirmed by in vivo protein-protein interaction studies, which demonstrate that only KaiC1 interacts with KaiA. Furthermore, we demonstrate that the three different Kai proteins form only homomeric complexes in vivo. As only KaiC1 phosphorylation depends on KaiA, a prerequisite for robust oscillations, we suggest that the kaiAB1C1 gene cluster in Synechocystis sp. PCC 6803 controls circadian timing in a manner similar to the clock described in Synechococcus elongatus PCC 7942.

  3. Spectral characteristic of fluorescence induction in a model cyanobacterium, Synechococcus sp. (PCC 7942)

    Czech Academy of Sciences Publication Activity Database

    Kaňa, Radek; Prášil, Ondřej; Komárek, Ondřej; Papageorgiou, G. C.; Govindjee, G.

    2009-01-01

    Roč. 1787, č. 10 (2009), s. 1170-1178 ISSN 0005-2728 R&D Projects: GA ČR GP206/09/P094; GA ČR GA206/07/0917; GA AV ČR IAA608170603 Institutional research plan: CEZ:AV0Z50200510; CEZ:AV0Z60870520 Keywords : fluorescence induction * cyanobacterium * PCC 7942 Subject RIV: EE - Microbiology, Virology Impact factor: 3.688, year: 2009

  4. Natural and Synthetic Variants of the Tricarboxylic Acid Cycle in Cyanobacteria: Introduction of the GABA Shunt into Synechococcus sp. PCC 7002.

    Science.gov (United States)

    Zhang, Shuyi; Qian, Xiao; Chang, Shannon; Dismukes, G C; Bryant, Donald A

    2016-01-01

    For nearly half a century, it was believed that cyanobacteria had an incomplete tricarboxylic acid (TCA) cycle, because 2-oxoglutarate dehydrogenase (2-OGDH) was missing. Recently, a bypass route via succinic semialdehyde (SSA), which utilizes 2-oxoglutarate decarboxylase (OgdA) and succinic semialdehyde dehydrogenase (SsaD) to convert 2-oxoglutarate (2-OG) into succinate, was identified, thus completing the TCA cycle in most cyanobacteria. In addition to the recently characterized glyoxylate shunt that occurs in a few of cyanobacteria, the existence of a third variant of the TCA cycle connecting these metabolites, the γ-aminobutyric acid (GABA) shunt, was considered to be ambiguous because the GABA aminotransferase is missing in many cyanobacteria. In this study we isolated and biochemically characterized the enzymes of the GABA shunt. We show that N -acetylornithine aminotransferase (ArgD) can function as a GABA aminotransferase and that, together with glutamate decarboxylase (GadA), it can complete a functional GABA shunt. To prove the connectivity between the OgdA/SsaD bypass and the GABA shunt, the gadA gene from Synechocystis sp. PCC 6803 was heterologously expressed in Synechococcus sp. PCC 7002, which naturally lacks this enzyme. Metabolite profiling of seven Synechococcus sp. PCC 7002 mutant strains related to these two routes to succinate were investigated and proved the functional connectivity. Metabolite profiling also indicated that, compared to the OgdA/SsaD shunt, the GABA shunt was less efficient in converting 2-OG to SSA in Synechococcus sp. PCC 7002. The metabolic profiling study of these two TCA cycle variants provides new insights into carbon metabolism as well as evolution of the TCA cycle in cyanobacteria.

  5. Lauric Acid Production in a Glycogen-Less Strain of Synechococcus sp. PCC 7002.

    Science.gov (United States)

    Work, Victoria H; Melnicki, Matthew R; Hill, Eric A; Davies, Fiona K; Kucek, Leo A; Beliaev, Alexander S; Posewitz, Matthew C

    2015-01-01

    The cyanobacterium Synechococcus sp. Pasteur culture collection 7002 was genetically engineered to synthesize biofuel-compatible medium-chain fatty acids (FAs) during photoautotrophic growth. Expression of a heterologous lauroyl-acyl carrier protein (C12:0-ACP) thioesterase with concurrent deletion of the endogenous putative acyl-ACP synthetase led to secretion of transesterifiable C12:0 FA in CO2-supplemented batch cultures. When grown at steady state over a range of light intensities in a light-emitting diode turbidostat photobioreactor, the C12-secreting mutant exhibited a modest reduction in growth rate and increased O2 evolution relative to the wild-type (WT). Inhibition of (i) glycogen synthesis by deletion of the glgC-encoded ADP-glucose pyrophosphorylase (AGPase) and (ii) protein synthesis by nitrogen deprivation were investigated as potential mechanisms for metabolite redistribution to increase FA synthesis. Deletion of AGPase led to a 10-fold decrease in reducing carbohydrates and secretion of organic acids during nitrogen deprivation consistent with an energy spilling phenotype. When the carbohydrate-deficient background (ΔglgC) was modified for C12 secretion, no increase in C12 was achieved during nutrient replete growth, and no C12 was recovered from any strain upon nitrogen deprivation under the conditions used. At steady state, the growth rate of the ΔglgC strain saturated at a lower light intensity than the WT, but O2 evolution was not compromised and became increasingly decoupled from growth rate with rising irradiance. Photophysiological properties of the ΔglgC strain suggest energy dissipation from photosystem II and reconfiguration of electron flow at the level of the plastoquinone pool.

  6. Far-red light photoacclimation (FaRLiP) in Synechococcus sp. PCC 7335: I. Regulation of FaRLiP gene expression.

    Science.gov (United States)

    Ho, Ming-Yang; Gan, Fei; Shen, Gaozhong; Zhao, Chi; Bryant, Donald A

    2017-02-01

    Far-red light photoacclimation (FaRLiP) is a mechanism that allows some cyanobacteria to utilize far-red light (FRL) for oxygenic photosynthesis. During FaRLiP, cyanobacteria remodel photosystem (PS) I, PS II, and phycobilisomes while synthesizing Chl d, Chl f, and far-red-absorbing phycobiliproteins, and these changes enable these organisms to use FRL for growth. In this study, a conjugation-based genetic system was developed for Synechococcus sp. PCC 7335. Three antibiotic cassettes were successfully used to generate knockout mutations in genes in Synechococcus sp. PCC 7335, which should allow up to three gene loci to be modified in one strain. This system was used to delete the rfpA, rfpB, and rfpC genes individually, and characterization of the mutants demonstrated that these genes control the expression of the FaRLiP gene cluster in Synechococcus sp. PCC 7335. The mutant strains exhibited some surprising differences from similar mutants in other FaRLiP strains. Notably, mutations in any of the three master transcription regulatory genes led to enhanced synthesis of phycocyanin and PS II. A time-course study showed that acclimation of the photosynthetic apparatus from that produced in white light to that produced in FRL occurs very slowly over a period 12-14 days in this strain and that it is associated with a substantial reduction (~34 %) in the chlorophyll a content of the cells. This study shows that there are differences in the detailed responses of cyanobacteria to growth in FRL in spite of the obvious similarities in the organization and regulation of the FaRLiP gene cluster.

  7. 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.

  8. Gene Inactivation in the Cyanobacterium Synechococcus sp. PCC 7002 and the Green Sulfur Bacterium Chlorobium tepidum Using In Vitro-Made DNA Constructs and Natural Transformation

    DEFF Research Database (Denmark)

    Frigaard, Niels-Ulrik; Sakuragi, Yumiko; Bryant, Donald A

    2004-01-01

    Inactivation of a chromosomal gene is a useful approach to study the function of the gene in question and can be used to produce a desired phenotype in the organism. This chapter describes how to generate such mutants of the cyanobacterium Synechococcus sp. PCC 7002 and the green sulfur bacterium...... Chlorobium tepidum by natural transformation with synthetic DNA constructs. Two alternative methods to generate the DNA constructs, both performed entirely in vitro and based on the polymerase chain reaction (PCR), are also presented. These methods are ligation of DNA fragments with T4 DNA ligase...

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

    Science.gov (United States)

    Song, Hyun-Seob; McClure, Ryan S.; Bernstein, Hans C.; Overall, Christopher C.; Hill, Eric A.; Beliaev, Alexander S.

    2015-01-01

    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. PMID:25826650

  10. 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.

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

    Science.gov (United States)

    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

  12. Modulation of Medium-Chain Fatty Acid Synthesis in Synechococcus sp. PCC 7002 by Replacing FabH with a Chaetoceros ketoacyl-ACP synthase

    Directory of Open Access Journals (Sweden)

    Huiya eGu

    2016-05-01

    Full Text Available The isolation or engineering of algal cells synthesizing high levels of medium-chain fatty acids (MCFAs is attractive to mitigate the high clouding point of longer chain fatty acids in algal based biodiesel. To develop a more informed understanding of MCFA synthesis is photosynthetic microorganisms, we isolated several algae from Great Salt Lake and screened this collection for MCFA accumulation to identify strains naturally accumulating high levels of MCFA. A diatom, Chaetoceros sp. GSL56, accumulated particularly high levels of C14 (up to 40%, with the majority of C14 fatty acids (~2/3 allocated in triacylglycerols. Using whole cell transcriptome sequencing and de novo assembly, putative genes encoding fatty acid synthesis enzymes were identified. Enzymes from this Chaetoceros sp. were expressed in the cyanobacterium Synechococcus sp. PCC 7002 to validate gene function and to determine whether eukaryotic enzymes lacking bacteria evolutionary control mechanisms could be used to improve MCFA production in this promising production strains. Replacement of the Synechococcus 7002 native FabH with a Chaetoceros ketoacyl-ACP synthase III increased MCFA synthesis up to five fold. The level of increase is dependent on promoter strength and culturing conditions.

  13. 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

  14. CRISPR interference as a titratable, trans-acting regulatory tool for metabolic engineering in the cyanobacterium Synechococcus sp. strain PCC 7002.

    Science.gov (United States)

    Gordon, Gina C; Korosh, Travis C; Cameron, Jeffrey C; Markley, Andrew L; Begemann, Matthew B; Pfleger, Brian F

    2016-11-01

    Trans-acting regulators provide novel opportunities to study essential genes and regulate metabolic pathways. We have adapted the clustered regularly interspersed palindromic repeats (CRISPR) system from Streptococcus pyogenes to repress genes in trans in the cyanobacterium Synechococcus sp. strain PCC 7002 (hereafter PCC 7002). With this approach, termed CRISPR interference (CRISPRi), transcription of a specific target sequence is repressed by a catalytically inactive Cas9 protein recruited to the target DNA by base-pair interactions with a single guide RNA that is complementary to the target sequence. We adapted this system for PCC 7002 and achieved conditional and titratable repression of a heterologous reporter gene, yellow fluorescent protein. Next, we demonstrated the utility of finely tuning native gene expression by downregulating the abundance of phycobillisomes. In addition, we created a conditional auxotroph by repressing synthesis of the carboxysome, an essential component of the carbon concentrating mechanism cyanobacteria use to fix atmospheric CO 2 . Lastly, we demonstrated a novel strategy for increasing central carbon flux by conditionally downregulating a key node in nitrogen assimilation. The resulting cells produced 2-fold more lactate than a baseline engineered cell line, representing the highest photosynthetically generated productivity to date. This work is the first example of titratable repression in cyanobacteria using CRISPRi, enabling dynamic regulation of essential processes and manipulation of flux through central carbon metabolism. This tool facilitates the study of essential genes of unknown function and enables groundbreaking metabolic engineering capability, by providing a straightforward approach to redirect metabolism and carbon flux in the production of high-value chemicals. Copyright © 2016 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

  15. FLAVODIIRON2 and FLAVODIIRON4 Proteins Mediate an Oxygen-Dependent Alternative Electron Flow in Synechocystis sp. PCC 6803 under CO2-Limited Conditions1[OPEN

    Science.gov (United States)

    Shimakawa, Ginga; Shaku, Keiichiro; Nishi, Akiko; Hayashi, Ryosuke; Yamamoto, Hiroshi; Sakamoto, Katsuhiko; Makino, Amane; Miyake, Chikahiro

    2015-01-01

    This study aims to elucidate the molecular mechanism of an alternative electron flow (AEF) functioning under suppressed (CO2-limited) photosynthesis in the cyanobacterium Synechocystis sp. PCC 6803. Photosynthetic linear electron flow, evaluated as the quantum yield of photosystem II [Y(II)], reaches a maximum shortly after the onset of actinic illumination. Thereafter, Y(II) transiently decreases concomitantly with a decrease in the photosynthetic oxygen evolution rate and then recovers to a rate that is close to the initial maximum. These results show that CO2 limitation suppresses photosynthesis and induces AEF. In contrast to the wild type, Synechocystis sp. PCC 6803 mutants deficient in the genes encoding FLAVODIIRON2 (FLV2) and FLV4 proteins show no recovery of Y(II) after prolonged illumination. However, Synechocystis sp. PCC 6803 mutants deficient in genes encoding proteins functioning in photorespiration show AEF activity similar to the wild type. In contrast to Synechocystis sp. PCC 6803, the cyanobacterium Synechococcus elongatus PCC 7942 has no FLV proteins with high homology to FLV2 and FLV4 in Synechocystis sp. PCC 6803. This lack of FLV2/4 may explain why AEF is not induced under CO2-limited photosynthesis in S. elongatus PCC 7942. As the glutathione S-transferase fusion protein overexpressed in Escherichia coli exhibits NADH-dependent oxygen reduction to water, we suggest that FLV2 and FLV4 mediate oxygen-dependent AEF in Synechocystis sp. PCC 6803 when electron acceptors such as CO2 are not available. PMID:25540330

  16. Protein (Cyanobacteria): 64998 [PGDBj - Ortholog DB

    Lifescience Database Archive (English)

    Full Text Available syc2491_c Synechococcus elongatus PCC 6301 MRPLTLEPHDQRSVLRLLIGAAWLDGDMQPEERNYLKGLLEKHRLAADPEFQDLMTRTTPISPAVFEQWLTAYLRQHPRREDVEALLEQISSVIYADSLIDAREAAVLCEIEQELEHRPALRLLDRLQTFFHHCLVMS ...

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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, Feppt), with distinct isotopic fractionation (ε56Fe) values determined from fitting the δ56Fe(II)aq (1.79‰ and 2.15‰) and the δ56Feppt (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 δ56Feppt 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.

  19. Deletion of the Synechocystis sp. PCC 6803 kaiAB1C1 gene cluster causes impaired cell growth under light-dark conditions.

    Science.gov (United States)

    Dörrich, Anja K; Mitschke, Jan; Siadat, Olga; Wilde, Annegret

    2014-11-01

    In contrast to Synechococcus elongatus PCC 7942, few data exist on the timing mechanism of the widely used cyanobacterium Synechocystis sp. PCC 6803. The standard kaiAB1C1 operon present in this organism was shown to encode a functional KaiC protein that interacted with KaiA, similar to the S. elongatus PCC 7942 clock. Inactivation of this operon in Synechocystis sp. PCC 6803 resulted in a mutant with a strong growth defect when grown under light-dark cycles, which was even more pronounced when glucose was added to the growth medium. In addition, mutants showed a bleaching phenotype. No effects were detected in mutant cells grown under constant light. Microarray experiments performed with cells grown for 1 day under a light-dark cycle revealed many differentially regulated genes with known functions in the ΔkaiABC mutant in comparison with the WT. We identified the genes encoding the cyanobacterial phytochrome Cph1 and the light-repressed protein LrtA as well as several hypothetical ORFs with a complete inverse behaviour in the light cycle. These transcripts showed a stronger accumulation in the light but a weaker accumulation in the dark in ΔkaiABC cells in comparison with the WT. In general, we found a considerable overlap with microarray data obtained for hik31 and sigE mutants. These genes are known to be important regulators of cell metabolism in the dark. Strikingly, deletion of the ΔkaiABC operon led to a much stronger phenotype under light-dark cycles in Synechocystis sp. PCC 6803 than in Synechococcus sp. PCC 7942. © 2014 The Authors.

  20. FLAVODIIRON2 and FLAVODIIRON4 proteins mediate an oxygen-dependent alternative electron flow in Synechocystis sp. PCC 6803 under CO2-limited conditions.

    Science.gov (United States)

    Shimakawa, Ginga; Shaku, Keiichiro; Nishi, Akiko; Hayashi, Ryosuke; Yamamoto, Hiroshi; Sakamoto, Katsuhiko; Makino, Amane; Miyake, Chikahiro

    2015-02-01

    This study aims to elucidate the molecular mechanism of an alternative electron flow (AEF) functioning under suppressed (CO2-limited) photosynthesis in the cyanobacterium Synechocystis sp. PCC 6803. Photosynthetic linear electron flow, evaluated as the quantum yield of photosystem II [Y(II)], reaches a maximum shortly after the onset of actinic illumination. Thereafter, Y(II) transiently decreases concomitantly with a decrease in the photosynthetic oxygen evolution rate and then recovers to a rate that is close to the initial maximum. These results show that CO2 limitation suppresses photosynthesis and induces AEF. In contrast to the wild type, Synechocystis sp. PCC 6803 mutants deficient in the genes encoding FLAVODIIRON2 (FLV2) and FLV4 proteins show no recovery of Y(II) after prolonged illumination. However, Synechocystis sp. PCC 6803 mutants deficient in genes encoding proteins functioning in photorespiration show AEF activity similar to the wild type. In contrast to Synechocystis sp. PCC 6803, the cyanobacterium Synechococcus elongatus PCC 7942 has no FLV proteins with high homology to FLV2 and FLV4 in Synechocystis sp. PCC 6803. This lack of FLV2/4 may explain why AEF is not induced under CO2-limited photosynthesis in S. elongatus PCC 7942. As the glutathione S-transferase fusion protein overexpressed in Escherichia coli exhibits NADH-dependent oxygen reduction to water, we suggest that FLV2 and FLV4 mediate oxygen-dependent AEF in Synechocystis sp. PCC 6803 when electron acceptors such as CO2 are not available. © 2015 American Society of Plant Biologists. All Rights Reserved.

  1. Ethylene production with engineered Synechocystis sp PCC 6803 strains.

    Science.gov (United States)

    Veetil, Vinod Puthan; Angermayr, S Andreas; Hellingwerf, Klaas J

    2017-02-23

    Metabolic engineering and synthetic biology of cyanobacteria offer a promising sustainable alternative approach for fossil-based ethylene production, by using sunlight via oxygenic photosynthesis, to convert carbon dioxide directly into ethylene. Towards this, both well-studied cyanobacteria, i.e., Synechocystis sp PCC 6803 and Synechococcus elongatus PCC 7942, have been engineered to produce ethylene by introducing the ethylene-forming enzyme (Efe) from Pseudomonas syringae pv. phaseolicola PK2 (the Kudzu strain), which catalyzes the conversion of the ubiquitous tricarboxylic acid cycle intermediate 2-oxoglutarate into ethylene. This study focuses on Synechocystis sp PCC 6803 and shows stable ethylene production through the integration of a codon-optimized version of the efe gene under control of the Ptrc promoter and the core Shine-Dalgarno sequence (5'-AGGAGG-3') as the ribosome-binding site (RBS), at the slr0168 neutral site. We have increased ethylene production twofold by RBS screening and further investigated improving ethylene production from a single gene copy of efe, using multiple tandem promoters and by putting our best construct on an RSF1010-based broad-host-self-replicating plasmid, which has a higher copy number than the genome. Moreover, to raise the intracellular amounts of the key Efe substrate, 2-oxoglutarate, from which ethylene is formed, we constructed a glycogen-synthesis knockout mutant (ΔglgC) and introduced the ethylene biosynthetic pathway in it. Under nitrogen limiting conditions, the glycogen knockout strain has increased intracellular 2-oxoglutarate levels; however, surprisingly, ethylene production was lower in this strain than in the wild-type background. Making use of different RBS sequences, production of ethylene ranging over a 20-fold difference has been achieved. However, a further increase of production through multiple tandem promoters and a broad-host plasmid was not achieved speculating that the transcription strength and

  2. ORF Alignment: NC_006576 [GENIUS II[Archive

    Lifescience Database Archive (English)

    Full Text Available ... [Synechococcus elongatus PCC 6301] ... Length = 288 ... Query: 24 ... LVYATYGELNRDRSNAILYPTSYGA...QHSTIDWLIGGDRILDPDRWFIVIVNQFGNGLSSS 83 ... LVYATYGELNRDRSNAILYPTSYGAQHSTID...WLIGGDRILDPDRWFIVIVNQFGNGLSSS Sbjct: 1 ... LVYATYGELNRDRSNAILYPTSYGAQHSTIDWLIGGDRILDPDRWFIVIVNQFGNGLSSS 60 ... Qu

  3. NMSBA: Aken Technologies Final Report: Toxicity Testing of Liquidoff

    Energy Technology Data Exchange (ETDEWEB)

    Ruffing, Anne [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jensen, Travis [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Strickland, Lucas [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-02-01

    To determine the effect of Liquidoff on bacteria, three bacterial strains were tested: Escherichia coli DH5α, Synechococcus sp. PCC 7002, and Synechococcus elongatus PCC 7942. E. coli DH5α is a Gram-negative, aerobic bacterium that is often found in normal gut flora and is commonly used the laboratory due to its fast growth rate. Synechococcus sp. PCC 7002 and S. elongatus PCC 7942 are Gram-negative, aquatic, autophototrophic cyanobacteria. Synechococcus sp. PCC 7002 is a marine cyanobacterium isolated from ‘fish pens’ on Magueyes Island, Puerto Rico in 1962, while S. elongatus PCC 7942 is a freshwater cyanobacterium. It should be noted that no Gram-positive bacterium was tested in this study.

  4. 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

  5. Glycogen Production in Marine Cyanobacterial Strain Synechococcus sp. NKBG 15041c.

    Science.gov (United States)

    Badary, Amr; Takamatsu, Shouhei; Nakajima, Mitsuharu; Ferri, Stefano; Lindblad, Peter; Sode, Koji

    2018-01-12

    An important feature offered by marine cyanobacterial strains over freshwater strains is the capacity to grow in seawater, replacing the need for often-limited freshwater. However, there are only limited numbers of marine cyanobacteria that are available for genetic manipulation and bioprocess applications. The marine unicellular cyanobacteria Synechococcus sp. strain NKBG 15041c (NKBG15041c) has been extensively studied. Recombinant DNA technologies are available for this strain, and its genomic information has been elucidated. However, an investigation of carbohydrate production, such as glycogen production, would provide information for inevitable biofuel-related compound production, but it has not been conducted. In this study, glycogen production by marine cyanobacterium NKBG15041c was investigated under different cultivation conditions. NKBG15041c yielded up to 399 μg/ml/OD 730 when cells were cultivated for 168 h in nitrogen-depleted medium (marine BG11 ΔN ) after medium replacement (336 h after inoculation). Cultivation under nitrogen-limited conditions also yielded an accumulation of glycogen in NKBG15041c cells (1 mM NaNO 3 , 301 μg/ml/OD 730 ; 3 mM NaNO 3 , 393 μg/ml/OD 730 ; and 5 mM NaNO 3 , 328 μg/ml/OD 730 ) under ambient conditions. Transcriptional analyses were carried out for 13 putative genes responsible for glycogen synthesis and catabolism that were predicted based on homology analyses with Synechocystis sp. PCC 6803 (PCC6803) and Synechococcus sp. PCC7002 (PCC7002). The transcriptional analyses revealed that glycogen production in NKBG15041c under nitrogen-depleted conditions can be explained by the contribution of both increased carbon flux towards glycogen synthesis, similar to PCC6803 and PCC7002, and increased transcriptional levels of genes responsible for glycogen synthesis, which is different from the conventionally reported phenomenon, resulting in a relatively high amount of glycogen under ambient conditions compared to

  6. Novel Synechococcus Genomes Reconstructed from Freshwater Reservoirs

    Directory of Open Access Journals (Sweden)

    Pedro J. Cabello-Yeves

    2017-06-01

    Full Text Available Freshwater picocyanobacteria including Synechococcus remain poorly studied at the genomic level, compared to their marine representatives. Here, using a metagenomic assembly approach we discovered two novel Synechococcus sp. genomes from two freshwater reservoirs Tous and Lake Lanier, both sharing 96% average nucleotide identity and displaying high abundance levels in these two lakes located at similar altitudes and temperate latitudes. These new genomes have the smallest estimated size (2.2 Mb and average intergenic spacer length (20 bp of any previously sequenced freshwater Synechococcus, which may contribute to their success in oligotrophic freshwater systems. Fluorescent in situ hybridization confirmed that Synechococcus sp. Tous comprises small cells (0.987 ± 0.139 μm length, 0.723 ± 0.119 μm width that amount to 90% of the picocyanobacteria in Tous. They appear together in a phylogenomic tree with Synechococcus sp. RCC307 strain, the main representative of sub-cluster 5.3 that has itself one of the smallest marine Synechococcus genomes. We detected a type II phycobilisome (PBS gene cluster in both genomes, which suggests that they belong to a phycoerythrin-rich pink low-light ecotype. The decrease of acidic proteins and the higher content of basic transporters and membrane proteins in the novel Synechococcus genomes, compared to marine representatives, support their freshwater specialization. A sulfate Cys transporter which is absent in marine but has been identified in many freshwater cyanobacteria was also detected in Synechococcus sp. Tous. The RuBisCo subunits from this microbe are phylogenetically close to the freshwater amoeba Paulinella chromatophora symbiont, hinting to a freshwater origin of the carboxysome operon of this protist. The novel genomes enlarge the known diversity of freshwater Synechococcus and improve the overall knowledge of the relationships among members of this genus at large.

  7. Novel Synechococcus Genomes Reconstructed from Freshwater Reservoirs

    Science.gov (United States)

    Cabello-Yeves, Pedro J.; Haro-Moreno, Jose M.; Martin-Cuadrado, Ana-Belen; Ghai, Rohit; Picazo, Antonio; Camacho, Antonio; Rodriguez-Valera, Francisco

    2017-01-01

    Freshwater picocyanobacteria including Synechococcus remain poorly studied at the genomic level, compared to their marine representatives. Here, using a metagenomic assembly approach we discovered two novel Synechococcus sp. genomes from two freshwater reservoirs Tous and Lake Lanier, both sharing 96% average nucleotide identity and displaying high abundance levels in these two lakes located at similar altitudes and temperate latitudes. These new genomes have the smallest estimated size (2.2 Mb) and average intergenic spacer length (20 bp) of any previously sequenced freshwater Synechococcus, which may contribute to their success in oligotrophic freshwater systems. Fluorescent in situ hybridization confirmed that Synechococcus sp. Tous comprises small cells (0.987 ± 0.139 μm length, 0.723 ± 0.119 μm width) that amount to 90% of the picocyanobacteria in Tous. They appear together in a phylogenomic tree with Synechococcus sp. RCC307 strain, the main representative of sub-cluster 5.3 that has itself one of the smallest marine Synechococcus genomes. We detected a type II phycobilisome (PBS) gene cluster in both genomes, which suggests that they belong to a phycoerythrin-rich pink low-light ecotype. The decrease of acidic proteins and the higher content of basic transporters and membrane proteins in the novel Synechococcus genomes, compared to marine representatives, support their freshwater specialization. A sulfate Cys transporter which is absent in marine but has been identified in many freshwater cyanobacteria was also detected in Synechococcus sp. Tous. The RuBisCo subunits from this microbe are phylogenetically close to the freshwater amoeba Paulinella chromatophora symbiont, hinting to a freshwater origin of the carboxysome operon of this protist. The novel genomes enlarge the known diversity of freshwater Synechococcus and improve the overall knowledge of the relationships among members of this genus at large. PMID:28680419

  8. The nitrogen interaction network in Synechococcus WH5701, a cyanobacterium with two PipX and two P(II)-like proteins.

    Science.gov (United States)

    Laichoubi, Karim Boumediene; Beez, Sabine; Espinosa, Javier; Forchhammer, Karl; Contreras, Asunción

    2011-04-01

    Nitrogen regulation involves the formation of different types of protein complexes between signal transducers and their transcriptional or metabolic targets. In oxygenic phototrophs, the signal integrator P(II) activates the enzyme N-acetyl-l-glutamate kinase (NAGK) by complex formation. P(II) also interacts with PipX, a protein with a tudor-like domain that mediates contacts with P(II) and with the transcriptional regulator NtcA, to which it binds to increase its activity. Here, we use a combination of in silico, yeast two-hybrid and in vitro approaches to investigate the nitrogen regulation network of Synechococcus WH5701, a marine cyanobacterium with two P(II) (GlnB_A and GlnB_B) and two PipX (PipX_I and PipX_II) proteins. Our results indicate that GlnB_A is functionally equivalent to the canonical P(II) protein from Synechococcus elongatus. GlnB_A interacted with PipX and NAGK proteins and stimulated NAGK activity, counteracting arginine inhibition. GlnB_B had only a slight stimulatory effect on NAGK activity, but its potential to bind effectors and form heterotrimers in Synechococcus WH5701 indicates additional regulatory functions. PipX_II, and less evidently PipX_I, specifically interacted with GlnB_A and NtcA, supporting a role for both Synechococcus WH5701 PipX proteins in partner swapping with GlnB_A and NtcA.

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

    Science.gov (United States)

    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.

  10. 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...

  11. studies on trace metal concentration pseudotolithus elongatus from ...

    African Journals Online (AJOL)

    DJFLEX

    ecological and human health implications of Lead (Pb) pollution are discussed. KEY WORDS: Trace metals, Lead Pollution, Pseudotolithus elongatus, Mbo coastal waters, Nigeria. INTRODUCTION. Anthropogenic activities which have taken place for the past two decades have greatly impacted on the marine ecosystem ...

  12. 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

  13. 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

  14. On the Mysterious Propulsion of Synechococcus

    Science.gov (United States)

    Ehlers, Kurt; Oster, George

    2012-01-01

    We propose a model for the self-propulsion of the marine bacterium Synechococcus utilizing a continuous looped helical track analogous to that found in Myxobacteria [1]. In our model cargo-carrying protein motors, driven by proton-motive force, move along a continuous looped helical track. The movement of the cargo creates surface distortions in the form of small amplitude traveling ridges along the S-layer above the helical track. The resulting fluid motion adjacent to the helical ribbon provides the propulsive thrust. A variation on the helical rotor model of [1] allows the motors to be anchored to the peptidoglycan layer, where they drive rotation of the track creating traveling helical waves along the S-layer. We derive expressions relating the swimming speed to the amplitude, wavelength, and velocity of the surface waves induced by the helical rotor, and show that they fall in reasonable ranges to explain the velocity and rotation rate of swimming Synechococcus. PMID:22567124

  15. Phosphatidylglycerol depletion affects photosystem II aktivity in Synechococcus sp. PCC 7942 cells

    Czech Academy of Sciences Publication Activity Database

    Bogos, B.; Ughy, B.; Domonkos, I.; Laczkó-Dobos, H.; Komenda, Josef; Abasova, L.; Cser, K.; Vass, I.; Sallai, A.; Wada, H.; Gombos, Z.

    2010-01-01

    Roč. 103, č. 1 (2010), s. 19-30 ISSN 0166-8595 Institutional research plan: CEZ:AV0Z50200510 Keywords : Oxygen-evolving activity * Phosphatidylglycerol * PS II acceptor side Subject RIV: EE - Microbiology, Virology Impact factor: 2.410, year: 2010

  16. Respiratory terminal oxidases alleviate photo-oxidative damage in photosystem I during repetitive short-pulse illumination in Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Shimakawa, Ginga; Miyake, Chikahiro

    2018-03-08

    Oxygenic phototrophs are vulnerable to damage by reactive oxygen species (ROS) that are produced in photosystem I (PSI) by excess photon energy over the demand of photosynthetic CO 2 assimilation. In plant leaves, repetitive short-pulse (rSP) illumination produces ROS to inactivate PSI. The production of ROS is alleviated by oxidation of the reaction center chlorophyll in PSI, P700, during the illumination with the short-pulse light, which is supported by flavodiiron protein (FLV). In this study, we found that in the cyanobacterium Synechocystis sp. PCC 6803 P700 was oxidized and PSI was not inactivated during rSP illumination even in the absence of FLV. Conversely, the mutant deficient in respiratory terminal oxidases was impaired in P700 oxidation during the illumination with the short-pulse light to suffer from photo-oxidative damage in PSI. Interestingly, the other cyanobacterium Synechococcus sp. PCC 7002 could not oxidize P700 without FLV during rSP illumination. These data indicate that respiratory terminal oxidases are critical to protect PSI from ROS damage during rSP illumination in Synechocystis sp. PCC 6803 but not Synechococcus sp. PCC 7002.

  17. Structural Analysis and Design of PCC Shoulders

    Science.gov (United States)

    1982-04-01

    A structural evaluation of PCC highway shoulders has been conducted and a comprehensive design procedure for plain jointed concrete shoulders developed. The procedure can be used to provide PCC shoulders either for rehabilitation of existing pavement...

  18. On the mysterious propulsion of Synechococcus.

    Directory of Open Access Journals (Sweden)

    Kurt Ehlers

    Full Text Available We propose a model for the self-propulsion of the marine bacterium Synechococcus utilizing a continuous looped helical track analogous to that found in Myxobacteria [1]. In our model cargo-carrying protein motors, driven by proton-motive force, move along a continuous looped helical track. The movement of the cargo creates surface distortions in the form of small amplitude traveling ridges along the S-layer above the helical track. The resulting fluid motion adjacent to the helical ribbon provides the propulsive thrust. A variation on the helical rotor model of [1] allows the motors to be anchored to the peptidoglycan layer, where they drive rotation of the track creating traveling helical waves along the S-layer. We derive expressions relating the swimming speed to the amplitude, wavelength, and velocity of the surface waves induced by the helical rotor, and show that they fall in reasonable ranges to explain the velocity and rotation rate of swimming Synechococcus.

  19. 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.

  20. Systems analysis of ethanol production in the genetically engineered cyanobacteriumSynechococcussp. PCC 7002.

    Science.gov (United States)

    Kopka, Joachim; Schmidt, Stefanie; Dethloff, Frederik; Pade, Nadin; Berendt, Susanne; Schottkowski, Marco; Martin, Nico; Dühring, Ulf; Kuchmina, Ekaterina; Enke, Heike; Kramer, Dan; Wilde, Annegret; Hagemann, Martin; Friedrich, Alexandra

    2017-01-01

    Future sustainable energy production can be achieved using mass cultures of photoautotrophic microorganisms, which are engineered to synthesize valuable products directly from CO 2 and sunlight. As cyanobacteria can be cultivated in large scale on non-arable land, these phototrophic bacteria have become attractive organisms for production of biofuels. Synechococcus sp. PCC 7002, one of the cyanobacterial model organisms, provides many attractive properties for biofuel production such as tolerance of seawater and high light intensities. Here, we performed a systems analysis of an engineered ethanol-producing strain of the cyanobacterium Synechococcus sp. PCC 7002, which was grown in artificial seawater medium over 30 days applying a 12:12 h day-night cycle. Biosynthesis of ethanol resulted in a final accumulation of 0.25% (v/v) ethanol, including ethanol lost due to evaporation. The cultivation experiment revealed three production phases. The highest production rate was observed in the initial phase when cells were actively growing. In phase II growth of the producer strain stopped, but ethanol production rate was still high. Phase III was characterized by a decrease of both ethanol production and optical density of the culture. Metabolomics revealed that the carbon drain due to ethanol diffusion from the cell resulted in the expected reduction of pyruvate-based intermediates. Carbon-saving strategies successfully compensated the decrease of central intermediates of carbon metabolism during the first phase of fermentation. However, during long-term ethanol production the producer strain showed clear indications of intracellular carbon limitation. Despite the decreased levels of glycolytic and tricarboxylic acid cycle intermediates, soluble sugars and even glycogen accumulated in the producer strain. The changes in carbon assimilation patterns are partly supported by proteome analysis, which detected decreased levels of many enzymes and also revealed the stress

  1. Expression of the copper metallothionein CUPI from Saccharomyces cerevisiae in the cyanobacterium Synechococcus R2-PIM8(smtA).

    Science.gov (United States)

    McCormick, P M; Cannon, G C; Heinhorst, S

    1999-03-01

    The coding sequence for Saccharomyces cerevisiae copper metallothionein (CUPI), the protein responsible for enhanced sequestration of Cu2+ in yeast, was placed under the control of an inducible synthetic Escherichia coli promoter in the cyanobacterial vector pTrcIK. Strain R2-PIM8(smtA) of Synechococcus sp. PCC 7942 was transformed with the resulting construct pMcK2, and the yeast CUPI gene was integrated into its genome via homologous recombination. The pMcK2 plasmid directed the synthesis of a protein product of the expected size in an in vitro E. coli transcription/translation system. In the transgenic cyanobacteria, the integrated CUPI gene was transcribed and produced a protein product with the expected metallothionein characteristics, as determined by 109Cd2+ binding assays. At this level of expression, the yeast metallothionein, although functional, did not increase the tolerance range of the transgenic Synechococcus to Cu2+ or Cd2+ beyond that of the untransformed R2-PIM8(smtA).

  2. Biological Observations on the Mudskipper Pseudapocryptes elongatus in the Mekong Delta, Vietnam

    DEFF Research Database (Denmark)

    Bucholtz, R. H.; Meilvang, A. S.; Cedhagen, Tomas

    2009-01-01

    Aspects of the population biology of the mudskipper, Pseudapocryptes elongatus, (Cuvier, 1816) were studied in Bac Lieu Province in the Lower Mekong Delta, Vietnam, including sex ratio, length–frequency distribution, sexual dimorphism, hepatosomatic index (HSI), female gonadosomatic index (GSI...

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

    Science.gov (United States)

    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

  4. Seasonal Diversity Patterns of a Coastal Synechococcus Population

    Science.gov (United States)

    Hunter-Cevera, K. R.; Sosik, H. M.; Neubert, M.; Hammar, K.; Post, A.

    2016-02-01

    Understanding how environmental and ecological factors determine phytoplankton species abundances requires knowledge of the diversity present within a population. For the important primary producer Synechococcus, clades demonstrate differences in temperature tolerance, light acclimation, grazer palatability, and more. Marine Synechococcus populations are often composed of more than one clade, and overall population dynamics will be governed by the types of cells present and by their individual physiological capabilities. We investigate the diversity of the Synechococcus assemblage at the Martha's Vineyard Coastal Observatory with high-throughput sequencing of the V6 hypervariable region of the 16S rRNA gene. Small nucleotide differences within this region allow for resolution of distinct phylotypes that can have a direct correspondence to the well-defined Synechococcus clades. From a three-year time series, we find that the Synechococcus population is dominated by 5 distinct phylotypes, and that each type exhibits a repeatable, seasonal pattern in relative abundance. We use compositional data analysis techniques to investigate the relationships between these patterns and environmental factors. We further interpret these patterns in the context of Synechococcus population dynamics assessed by automated, submersible flow cytometry (FlowCytobot). Observed diel changes in cell size distributions, coupled with a validated matrix population model, provide estimates of in situ population division rates. We find strong evidence that the main seasonal diversity patterns are governed by temperature, but that biological loss agents likely shape the diversity structure for certain times of year. For some phylotypes, relative abundance patterns are also related to light and nutrients. The composition of Synechococcus over the annual cycle appears to directly affect seasonal features of cell abundance patterns, such as the spring bloom.

  5. 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.

  6. Synechococcus in the Atlantic gateway to the Arctic Ocean

    Directory of Open Access Journals (Sweden)

    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.

  7. Patterns and Regulation of Silicon Accumulation in Synechococcus spp.

    Science.gov (United States)

    Brzezinski, M. A.; Krause, J. W.; Twining, B. S.; Baines, S. B.; Collier, J.

    2016-02-01

    Culture experiments confirm the accumulation of significant amounts of Si by six clones of marine Synechococcus representing four clades from a variety of marine habitats. Both cellular Si levels and the rate of Si accumulation in Synechococcus respond proportionately to changes in the concentration of silicic acid in the external medium. Si quota is inversely related to growth rate implying growth rate dilution of cellular Si quotas. The rate of Si accumulation as a function of silicic acid concentration is bi-linear between 1 and 500 μM Si(OH)4 with an abrupt increase in the slope at 100 μM. The linear response at environmentally-relevant [Si(OH)4] implies that in the surface ocean Synechococcus acquire Si through diffusion rather than through active transport. However, some evidence was obtained for Si uptake through a phosphate transporter under low-nutrient conditions. If all water-soluble Si associated with Synechococcus cells is internal, internal cellular concentrations would be above seawater silicic acid saturation (i.e. 2 millimolar) implying the existence of a large pool of organically bound silicic acid, as has been hypothesized for diatoms. Organic complexation of intracellular Si would both prevent spontaneous precipitation of amorphous silica and maintain low internal free silicic acid concentrations to drive a diffusive flux of silicic acid into the cell. Our experiments were not designed to address the specific evolutionary or physiological roles played by Si, if any, in Synechococcus. A partial answer will involve determining the chemical environment of Si within Synechococcus and whether the organism has evolved specific molecules that target and bind Si intracellularly or whether the internal complexation of Si is gratuitous.

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

    Science.gov (United States)

    Zhang, Shuyi; Bryant, Donald A.

    2015-01-01

    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. PMID:25869135

  9. First Record of Two Gobiid Fishes, Luciogobius elongatus, L. platycephalus (Perciformes: Gobiidae from Korea

    Directory of Open Access Journals (Sweden)

    Seung-Ho Choi

    2014-01-01

    Full Text Available Two species of small gobiid fishes genus Luciogobius, i.e., L. elongatus, L. platycephalus were described as the first records from Korea based on specimens collected from gravel beaches of Gijang-gun, Busan-si, Korea. Luciogobius elongatus is distinguished from congeners by very elongated and naked body, 42-44 vertebrae, 6-7 dorsal soft rays, and no free rays on pectoral fin, and L. platycephalus is characterized by having very depressed head, naked body, 40-41 vertebrae, 10-11 dorsal soft rays, and pectoral fin with only upper 2-4 free rays. We propose the new Korean name “Ga-neun-mi-kkeun-mang-dug”, “Nab-jak-mi-kkeunmang- dug” for L. elongatus and L. platycephalus, respectively.

  10. 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.

  11. Development of a sperm cryopreservation protocol for redside dace, Clinostomus elongatus: implications for genome resource banking

    DEFF Research Database (Denmark)

    Butts, Ian A.E.; Mokdad, A.; Trippel, E.A.

    2013-01-01

    Populations of Redside Dace Clinostomus elongatus have declined in many areas across the species’North American range. Therefore, the development of sperm cryopreservation technology would provide an invaluable means of preserving genetic diversity in populations that are in imminent danger...

  12. 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

  13. Combined SAXS/EM based models of the S. elongatus post-translational circadian oscillator and its interactions with the output His-kinase SasA.

    Directory of Open Access Journals (Sweden)

    Rekha Pattanayek

    Full Text Available The circadian clock in the cyanobacterium Synechococcus elongatus is composed of a post-translational oscillator (PTO that can be reconstituted in vitro from three different proteins in the presence of ATP and a transcription-translation feedback loop (TTFL. The homo-hexameric KaiC kinase, phosphatase and ATPase alternates between hypo- and hyper-phosphorylated states over the 24-h cycle, with KaiA enhancing phosphorylation, and KaiB antagonizing KaiA and promoting KaiC subunit exchange. SasA is a His kinase that relays output signals from the PTO formed by the three Kai proteins to the TTFL. Although the crystal structures for all three Kai proteins are known, atomic resolution structures of Kai and Kai/SasA protein complexes have remained elusive. Here, we present models of the KaiAC and KaiBC complexes derived from solution small angle X-ray scattering (SAXS, which are consistent with previous EM based models. We also present a combined SAXS/EM model of the KaiC/SasA complex, which has two N-terminal SasA sensory domains occupying positions on the C-terminal KaiC ring reminiscent of the orientations adopted by KaiB dimers. Using EM we demonstrate that KaiB and SasA compete for similar binding sites on KaiC. We also propose an EM based model of the ternary KaiABC complex that is consistent with the sequestering of KaiA by KaiB on KaiC during the PTO dephosphorylation phase. This work provides the first 3D-catalogue of protein-protein interactions in the KaiABC PTO and the output pathway mediated by SasA.

  14. Intertwined evolutionary histories of marine Synechococcus and Prochlorococcus marinus.

    Science.gov (United States)

    Zhaxybayeva, Olga; Doolittle, W Ford; Papke, R Thane; Gogarten, J Peter

    2009-09-02

    Prochlorococcus is a genus of marine cyanobacteria characterized by small cell and genome size, an evolutionary trend toward low GC content, the possession of chlorophyll b, and the absence of phycobilisomes. Whereas many shared derived characters define Prochlorococcus as a clade, many genome-based analyses recover them as paraphyletic, with some low-light adapted Prochlorococcus spp. grouping with marine Synechococcus. Here, we use 18 Prochlorococcus and marine Synechococcus genomes to analyze gene flow within and between these taxa. We introduce embedded quartet scatter plots as a tool to screen for genes whose phylogeny agrees or conflicts with the plurality phylogenetic signal, with accepted taxonomy and naming, with GC content, and with the ecological adaptation to high and low light intensities. We find that most gene families support high-light adapted Prochlorococcus spp. as a monophyletic clade and low-light adapted Prochlorococcus sp. as a paraphyletic group. But we also detect 16 gene families that were transferred between high-light adapted and low-light adapted Prochlorococcus sp. and 495 gene families, including 19 ribosomal proteins, that do not cluster designated Prochlorococcus and Synechococcus strains in the expected manner. To explain the observed data, we propose that frequent gene transfer between marine Synechococcus spp. and low-light adapted Prochlorococcus spp. has created a "highway of gene sharing" (Beiko RG, Harlow TJ, Ragan MA. 2005. Highways of gene sharing in prokaryotes. Proc Natl Acad Sci USA. 102:14332-14337) that tends to erode genus boundaries without erasing the Prochlorococcus-specific ecological adaptations.

  15. Genomics of "Candidatus Synechococcus spongiarium", a Cyanobacterial Sponge Symbiont

    Energy Technology Data Exchange (ETDEWEB)

    Slaby, Beate M. [Univ. of Wuerzburg (Germany); Copeland, Alex [Lawrence Berkeley National Lab. (LBNL), Walnut Creek, CA (United States). Dept. of Energy Joint Genome Inst.; Woyke, Tanja [Lawrence Berkeley National Lab. (LBNL), Walnut Creek, CA (United States). Dept. of Energy Joint Genome Inst.; Hentschel, Ute [Univ. of Wuerzburg (Germany)

    2014-03-21

    Marine sponges (Porifera): ancient metazoans of ecological importance, that produce bioactive secondary metabolites and interact with various microorganisms including cyanobacteria1: Marine Synechococcus spp.: cyanobacteria, important contributors to the global carbon cycle and major primary producers in the oceans2 Ca. S. spongiarum: an ecotype of this genus, widespread and abundant symbiont of various marine sponges around the world3, e.g. Aplysina aerophoba

  16. Abundance and distribution of Synechococcus spp. and cyanophages in the Chesapeake Bay.

    Science.gov (United States)

    Wang, Kui; Wommack, K Eric; Chen, Feng

    2011-11-01

    Despite the increasing knowledge of Synechococcus spp. and their co-occurring cyanophages in oceanic and coastal water, little is known about their abundance, distribution, and interactions in the Chesapeake Bay estuarine ecosystem. A 5-year interannual survey shows that Synechococcus spp. and their phages are persistent and abundant members of Chesapeake Bay microbial communities. Synechococcus blooms (10⁶ cells ml⁻¹) were often observed in summer throughout the Bay, contributing 20 to 40% of total phytoplankton chlorophyll a. The distribution of phycoerythrin-containing (PE-rich) Synechococcus cells appeared to mostly correlate with the salinity gradient, with higher abundances at higher salinities. Cyanophages infectious to Synechococcus were also abundant (up to 6 × 10⁵ viruses ml⁻¹ by the most probable number assay) during summer months in the Bay. The covariation in abundance of Synechococcus spp. and cyanophages was evident, although the latitude of observed positive correlation varied in different years, mirroring the changing environmental conditions and therefore the host-virus interactions. The impacts of cyanophages on host Synechococcus populations also varied spatially and temporally. Higher phage-related Synechococcus mortality was observed in drought years. Virus-mediated host mortality and subsequent liberation of dissolved organic matter (DOM) may substantially influence oceanic biogeochemical processing through the microbial loop as well as the microbial carbon pump. These observations emphasize the influence of environmental gradients on natural Synechococcus spp. and their phage population dynamics in the estuarine ecosystem.

  17. Abundance and Distribution of Synechococcus spp. and Cyanophages in the Chesapeake Bay▿†

    Science.gov (United States)

    Wang, Kui; Wommack, K. Eric; Chen, Feng

    2011-01-01

    Despite the increasing knowledge of Synechococcus spp. and their co-occurring cyanophages in oceanic and coastal water, little is known about their abundance, distribution, and interactions in the Chesapeake Bay estuarine ecosystem. A 5-year interannual survey shows that Synechococcus spp. and their phages are persistent and abundant members of Chesapeake Bay microbial communities. Synechococcus blooms (106 cells ml−1) were often observed in summer throughout the Bay, contributing 20 to 40% of total phytoplankton chlorophyll a. The distribution of phycoerythrin-containing (PE-rich) Synechococcus cells appeared to mostly correlate with the salinity gradient, with higher abundances at higher salinities. Cyanophages infectious to Synechococcus were also abundant (up to 6 × 105 viruses ml−1 by the most probable number assay) during summer months in the Bay. The covariation in abundance of Synechococcus spp. and cyanophages was evident, although the latitude of observed positive correlation varied in different years, mirroring the changing environmental conditions and therefore the host-virus interactions. The impacts of cyanophages on host Synechococcus populations also varied spatially and temporally. Higher phage-related Synechococcus mortality was observed in drought years. Virus-mediated host mortality and subsequent liberation of dissolved organic matter (DOM) may substantially influence oceanic biogeochemical processing through the microbial loop as well as the microbial carbon pump. These observations emphasize the influence of environmental gradients on natural Synechococcus spp. and their phage population dynamics in the estuarine ecosystem. PMID:21821760

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

    OpenAIRE

    Simone, Luiz Ricardo L

    1997-01-01

    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, e...

  19. 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

  20. Coprorhexy, coprophagy, and coprochaly in the copepods Calanus helgolandicus, Pseudocalanus elongatus, and Oithona similis

    DEFF Research Database (Denmark)

    Iversen, Morten; Poulsen, Louise K.

    2007-01-01

    is mainly thought to be caused by coprophagy (ingestion of fecal pellets) by copepods, and especially by the ubiquitous copepods Oithona spp. We examined fecal pellet ingestion rate and feeding behavior of O. similis and 2 other dominant copepod species from the North Sea (Calanus helgolandicus...... and Pseudocalanus elongatus). All investigations were done with fecal pellets as the sole food source and with fecal pellets offered together with an alternative suitable food source. The ingestion of fecal pellets by all 3 copepod species was highest when offered together with an alternative food source....... No feeding behavior was determined for O. similis due to the lack of pellet capture in those experiments. Fecal pellets offered together with an alternative food source increased the filtration activity by C. helgolandicus and P. elongatus and thereby the number of pellets caught in their feeding current...

  1. Spatial Genetic Structure and Mitochondrial DNA Phylogeography of Argentinean Populations of the Grasshopper Dichroplus elongatus

    OpenAIRE

    Rosetti, Natalia; Remis, Maria Isabel

    2012-01-01

    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 ...

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

    Directory of Open Access Journals (Sweden)

    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.

  3. Draft Genome Sequence of Synechococcus sp. Strain CB0101, Isolated From the Chesapeake Bay Estuary.

    Science.gov (United States)

    Marsan, David; Wommack, K Eric; Ravel, Jacques; Chen, Feng

    2014-01-09

    Here, we report the draft genome sequence of the estuarine Synechococcus sp. strain CB0101. The genomics information of this strain will facilitate the study of the poorly understood Synechococcus subcluster 5.2 and how this strain is capable of thriving in a dynamic estuarine system, such as the Chesapeake Bay.

  4. 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.

  5. 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.

  6. Biosynthesis of platform chemical 3-hydroxypropionic acid (3-HP) directly from CO2 in cyanobacterium Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Wang, Yunpeng; Sun, Tao; Gao, Xingyan; Shi, Mengliang; Wu, Lina; Chen, Lei; Zhang, Weiwen

    2016-03-01

    3-hydroxypropionic acid (3-HP) is an important platform chemical with a wide range of applications. So far large-scale production of 3-HP has been mainly through petroleum-based chemical processes, whose sustainability and environmental issues have attracted widespread attention. With the ability to fix CO2 directly, cyanobacteria have been engineered as an autotrophic microbial cell factory to produce fuels and chemicals. In this study, we constructed the biosynthetic pathway of 3-HP in cyanobacterium Synechocystis sp. PCC 6803, and then optimized the system through the following approaches: i) increasing expression of malonyl-CoA reductase (MCR) gene using different promoters and cultivation conditions; ii) enhancing supply of the precursor malonyl-CoA by overexpressing acetyl-CoA carboxylase and biotinilase; iii) improving NADPH supply by overexpressing the NAD(P) transhydrogenase gene; iv) directing more carbon flux into 3-HP by inactivating the competing pathways of PHA and acetate biosynthesis. Together, the efforts led to a production of 837.18 mg L(-1) (348.8 mg/g dry cell weight) 3-HP directly from CO2 in Synechocystis after 6 days cultivation, demonstrating the feasibility photosynthetic production of 3-HP directly from sunlight and CO2 in cyanobacteria. In addition, the results showed that overexpression of the ribulose-1, 5-bisphosphate carboxylase/oxygenase (Rubisco) gene from Anabaena sp. PCC 7120 and Synechococcus sp. PCC 7942 led to no increase of 3-HP production, suggesting CO2 fixation may not be a rate-limiting step for 3-HP biosynthesis in Synechocystis. Copyright © 2015 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

  7. Comparative genome analysis of the closely related Synechocystis strains PCC 6714 and PCC 6803.

    Science.gov (United States)

    Kopf, Matthias; Klähn, Stephan; Pade, Nadin; Weingärtner, Christian; Hagemann, Martin; Voß, Björn; Hess, Wolfgang R

    2014-06-01

    Synechocystis sp. PCC 6803 is the most popular cyanobacterial model for prokaryotic photosynthesis and for metabolic engineering to produce biofuels. Genomic and transcriptomic comparisons between closely related bacteria are powerful approaches to infer insights into their metabolic potentials and regulatory networks. To enable a comparative approach, we generated the draft genome sequence of Synechocystis sp. PCC 6714, a closely related strain of 6803 (16S rDNA identity 99.4%) that also is amenable to genetic manipulation. Both strains share 2838 protein-coding genes, leaving 845 unique genes in Synechocystis sp. PCC 6803 and 895 genes in Synechocystis sp. PCC 6714. The genetic differences include a prophage in the genome of strain 6714, a different composition of the pool of transposable elements, and a ∼ 40 kb genomic island encoding several glycosyltransferases and transport proteins. We verified several physiological differences that were predicted on the basis of the respective genome sequence. Strain 6714 exhibited a lower tolerance to Zn(2+) ions, associated with the lack of a corresponding export system and a lowered potential of salt acclimation due to the absence of a transport system for the re-uptake of the compatible solute glucosylglycerol. These new data will support the detailed comparative analyses of this important cyanobacterial group than has been possible thus far. Genome information for Synechocystis sp. PCC 6714 has been deposited in Genbank (accession no AMZV01000000). © The Author 2014. Published by Oxford University Press on behalf of Kazusa DNA Research Institute.

  8. The reversal effect of prothrombin complex concentrate (PCC), activated PCC and recombinant activated factor VII against anticoagulation of Xa inhibitor.

    Science.gov (United States)

    Schultz, Nina Haagenrud; Tran, Hoa Thi Tuyet; Bjørnsen, Stine; Henriksson, Carola Elisabeth; Sandset, Per Morten; Holme, Pål Andre

    2017-01-01

    An increasing number of patients are treated with direct-acting oral anticoagulants (DOACs), but the optimal way to reverse the anticoagulant effect is not known. Specific antidotes are not available and prothrombin complex concentrate (PCC), activated PCC (aPCC) and recombinant factor VIIa (rFVIIa) are variously used as reversal agents in case of a major bleeding. We aimed to determine the most effective haemostatic agent and dose to reverse the effect of rivaroxaban in blood samples from patients taking rivaroxaban for therapeutic reasons. Blood samples from rivaroxaban-treated patients ( n =  50) were spiked with PCC, aPCC and rFVIIa at concentrations imitating 80%, 100% and 125% of suggested therapeutic doses. The reversal effect was assessed by thromboelastometry in whole blood and a thrombin generation assay (TGA) in platelet-poor plasma. Samples from healthy subjects ( n =  40) were included as controls. In thromboelastometry measurements, aPCC and rFVIIa had a superior effect to PCC in reversing the rivaroxaban-induced lenghtening of clotting time (CT). aPCC was the only haemostatic agent that shortened the CT down to below the control level. Compared to healthy controls, patients on rivaroxaban also had a prolonged lag time and decreased peak concentration, velocity index and endogenous thrombin potential (ETP) in platelet-poor plasma. aPCC reversed these parameters more effectively than rFVIIa and PCC. There were no differences in efficacy between 80%, 100% and 125% doses of aPCC. aPCC seems to reverse the anticoagulant effect of rivaroxaban more effectively than rFVIIa and PCC by evaluation with thromboelastometry and TGA in vitro.

  9. Biological observations on the mudskipper Pseudapocryptes elongatus in the Mekong Delta, Vietnam

    DEFF Research Database (Denmark)

    Bucholtz, Rikke Hagstrøm; Meilvang, A. S.; Cedhagen, T.

    2009-01-01

    Aspects of the population biology of the mudskipper, Pseudapocryptes elongatus, (Cuvier, 1816) were studied in Bac Lieu Province in the Lower Mekong Delta, Vietnam, including sex ratio, length-frequency distribution, sexual dimorphism, hepatosomatic index (HSI), female gonadosomatic index (GSI......), gonad histology, fecundity and some observations on post-larvae and juveniles. In the population studied the sex ratio was skewed toward males. Females had a shorter mean length and a lower mean growth rate than males. No mature males or females were observed among mudskippers sampled in estuarine...

  10. Phenotypic Variation and Sexual Size Dimorphism in Dichroplus elongatus (Orthoptera: Acrididae).

    Science.gov (United States)

    Rosetti, N; Remis, M I

    2015-08-01

    Patterns of body size evolution are of particular interest because body size can affect virtually all the physiological and life history traits of an organism. Sexual size dimorphism (SSD), a difference in body size between males and females, is a widespread phenomenon in insects. Much of the variation in SSD is genetically based and likely due to differential selection acting on males and females. The importance of environmental variables and evolutionary processes affecting phenotypeic variation in both sexes may be useful to gain insights into insect ecology and evolution. Dichroplus elongatus Giglio-Tos is a South American grasshopper widely distributed throughout Argentina, Uruguay, most of Chile, and southern Brazil. In this study, we analyzed 122 adult females of D. elongatus collected in eight natural populations from central-east Argentina. Females show large body size variation among the analyzed populations and this variation exhibits a strong relationship with fecundity. Our results have shown that larger females were more fecund than smaller ones. We found that ovariole number varied along a latitudinal gradient, with higher ovariole numbers in populations from warmer locations. A considerable female-biased SSD was detected. SSD for three analyzed morphometric traits scaled isometrically. However, SSD for thorax length displayed a considerable variation across the studied area, indicating a larger relative increase in female size than in male size in warmer environmental conditions. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

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

    Science.gov (United States)

    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.

  12. 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.

  13. Blind dating - mate finding in planktonic copepods. II. The pheromone cloud of Pseudocalanus elongatus

    DEFF Research Database (Denmark)

    Kiørboe, Thomas; Bagøien, E.; Thygesen, Uffe Høgsbro

    2005-01-01

    as an almost spherical cloud with a very heterogeneous internal structure. This is very different from the long, distinct pheromone trails deposited by females of many cruising copepods and appears to be characteristic of hovering females. We estimate the encounter cross-section area of the pheromone plume...... of P. elongatus and find that it enhances the mate encounter probability by a factor of about 40, and we show that this area increases in proportion to the rate at which pheromones are released. We also show that pheromone clouds are affected by—but still quite robust to—turbulence, with the encounter...... cross section declining with the turbulent dissipation rate raised to a power of 1/2. The sensitivity of mate encounter rates to turbulence is similar among copepods that produce pheromone trails and pheromone clouds....

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

    Science.gov (United States)

    Rosetti, Natalia; Remis, Maria Isabel

    2012-01-01

    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 genetic loss

  15. 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

  16. Single particle analysis of thylakoid proteins from Thermosynechococcus elongatus and Synechocystis 6803 : Localization of the CupA subunit of NDH-1

    NARCIS (Netherlands)

    Folea, I. Mihaela; Zhang, Pengpeng; Nowaczyk, Marc M.; Ogawa, Teruo; Aro, Eva-Marl; Boekema, Egbert J.; Aro, Eva-Mari

    The larger protein complexes of the cyanobacterial photosynthetic membrane of Thermosynechoccus elongatus and Synechocystis 6803 were studied by single particle electron microscopy after detergent solubilization, without any purification steps. Besides the "standard" L-shaped NDH-1L complex, related

  17. Antimicrobial and Cytotoxic Assessment of Marine Cyanobacteria - Synechocystis and Synechococcus

    Directory of Open Access Journals (Sweden)

    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.

  18. Guidelines for PCC inputs to AASHTOWare Pavement ME.

    Science.gov (United States)

    2014-12-01

    The objective of this research study was to develop guidelines for portland cement concrete (PCC) material inputs to the : AASHTOWare Pavement ME Design program. The AASHTOWare Pavement ME Design is the software program used by the : Mississippi Depa...

  19. Evaluation of construction strategies for PCC pavement rehabilitation projects.

    Science.gov (United States)

    2010-09-30

    This study investigated project management level solutions to optimizing resources, minimizing costs : (including user costs) and time for PCC pavement rehabilitation projects. This study extensively : evaluated the applicability of the Construction ...

  20. Recycling Old PCC Pavement - Performance Evaluation of FAI 57 Inlays

    Science.gov (United States)

    1993-02-01

    This report details the construction and performance monitoring efforts of two demonstration projects proposed in an experimental features work plan entitled Recycling Old PCC Pavement". The objectives of this experimental feature were to evaluate th...

  1. Biotransformation of 6-deoxypseudoanisatin by Synechocystis sp. PCC6803

    Directory of Open Access Journals (Sweden)

    Zhi Wang

    2014-10-01

    Conclusion: Thus, the study appears to demonstrate that Synechocystis sp. PCC6803 can transform 6-deoxypseudoanisatin. The polarity of the converted product is less than that of 6-deoxypseudoanisatin.

  2. 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.

  3. Genetic transformation of marine cyanobacterium Synechococcus sp. CC9311 (Cyanophyceae) by electroporation

    Science.gov (United States)

    Chen, Huaxin; Lin, Hanzhi; Jiang, Peng; Li, Fuchao; Qin, Song

    2013-03-01

    Synechococcus sp. CC9311 is a marine cyanobacterium characterized by type IV chromatic acclimation (CA). A genetic transformation system was developed as a first step to elucidate the molecular mechanism of CA. The results show that Synechococcus sp. CC9311 cells were sensitive to four commonly used antibiotics: ampicillin, kanamycin, spectinomycin, and chloramphenicol. An integrative plasmid to disrupt the putative phycoerythrin lyase gene mpeV, using a kanamycin resistance gene as selectable marker, was constructed by recombinant polymerase chain reaction. The plasmid was then transformed into Synechococcus sp. CC9311 via electroporation. High transformation efficiency was achieved at a field strength of 2 kV/cm. DNA analysis showed that mpeV was fully disrupted following challenge of the transformants with a high concentration of kanamycin. In addition, the transformants that displayed poor growth on agar SN medium could be successfully plated on agarose SN medium.

  4. Protein (Cyanobacteria): 515893735 [PGDBj - Ortholog DB

    Lifescience Database Archive (English)

    Full Text Available 379 ... hypothetical protein Synechococcus sp. PCC 7336 MITENYFEDLHFTECNIGEFSFSDKDLYVNIDSGLYIFGEHPLKGIIQPSDSCIAIFKNVIYSHRILALYSEDRKGFTGEKIVDKNIAQPSEGQNYKRFSIEGVSKNPPAWLTWDIDAASFMLETISS

  5. Protein (Cyanobacteria): 52198 [PGDBj - Ortholog DB

    Lifescience Database Archive (English)

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

  6. Standardization of CalyculinA induced PCC assay and its advantages over Okadaic acid PCC assay in Biodosimetry applications.

    Science.gov (United States)

    Nairy, Rajesha K; Yerol, Narayana; Bhat, Nagesh N; Desai, Utkarsha; Shirsath, Kapil; Yadav, Usha; K Chaurasia, Rajesh; B K, Sapra

    2016-11-29

    In the present study an attempt was made to estimate coefficients of dose response curves for PCC aberrations induced by CalyculinA and Okadaic acid, using 60 Co gamma radiation and 8 MeV pulsed electron beam for biodosimetry application. The modified method outlined by Puig et al. 2013 was used to conduct Calyculin A and Okadaic acid induced PCC assay in human blood lymphocytes.Chemical treatment was given for the last 1 h of a 48 h culture. The study was carried out in the dose range 2.5 to 20 Gy using 60 Co gamma rays and 8 MeV pulsed electron beam. Results show a linear dose dependent increase with a slope of 0.047 ± 0.001 from Calycalin A PCC and 0.048 ± 0.002 form Okadaic acid PCC. The slope of the fragments curve was 0.327 ± 0.006 from Calyculin A and 0.328 ± 0.006 from Okadaic acid PCC. Further, dose calibration studies were carried out for 8 MeV electron using Calyculin A PCC assay and the obtained slope from ring yield was 0.054 ± 0.002 and 0.427 ± 0.009 from fragment yield.

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

    Directory of Open Access Journals (Sweden)

    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

  8. Comparison of the Seasonal Variations of Synechococcus Assemblage Structures in Estuarine Waters and Coastal Waters of Hong Kong

    Science.gov (United States)

    Xia, Xiaomin; Vidyarathna, Nayani K.; Palenik, Brian; Lee, Puiyin

    2015-01-01

    Seasonal variation in the phylogenetic composition of Synechococcus assemblages in estuarine and coastal waters of Hong Kong was examined through pyrosequencing of the rpoC1 gene. Sixteen samples were collected in 2009 from two stations representing estuarine and ocean-influenced coastal waters, respectively. Synechococcus abundance in coastal waters gradually increased from 3.6 × 103 cells ml−1 in March, reaching a peak value of 5.7 × 105 cells ml−1 in July, and then gradually decreased to 9.3 × 103 cells ml−1 in December. The changes in Synechococcus abundance in estuarine waters followed a pattern similar to that in coastal waters, whereas its composition shifted from being dominated by phycoerythrin-rich (PE-type) strains in winter to phycocyanin-only (PC-type) strains in summer owing to the increase in freshwater discharge from the Pearl River and higher water temperature. The high abundance of PC-type Synechococcus was composed of subcluster 5.2 marine Synechococcus, freshwater Synechococcus (F-PC), and Cyanobium. The Synechococcus assemblage in the coastal waters, on the other hand, was dominated by marine PE-type Synechococcus, with subcluster 5.1 clades II and VI as the major lineages from April to September, when the summer monsoon prevailed. Besides these two clades, clade III cooccurred with clade V at relatively high abundance in summer. During winter, the Synechococcus assemblage compositions at the two sites were similar and were dominated by subcluster 5.1 clades II and IX and an undescribed clade (represented by Synechococcus sp. strain miyav). Clade IX Synechococcus was a relatively ubiquitous PE-type Synechococcus found at both sites, and our study demonstrates that some strains of the clade have the ability to deal with large variation of salinity in subtropical estuarine environments. Our study suggests that changes in seawater temperature and salinity caused by the seasonal variation of monsoonal forcing are two major determinants of

  9. Toward solar biodiesel production from CO2 using engineered cyanobacteria.

    Science.gov (United States)

    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.

  10. Relative stability of ploidy in a marine Synechococcus across various growth conditions.

    Science.gov (United States)

    Perez-Sepulveda, Blanca; Pitt, Frances; N'Guyen, An N; Ratin, Morgane; Garczarek, Laurence; Millard, Andrew; Scanlan, David J

    2018-01-12

    Marine picocyanobacteria of the genus Synechococcus are ubiquitous phototrophs in oceanic systems. Consistent with these organisms occupying vast tracts of the nutrient impoverished ocean, most marine Synechococcus so far studied are monoploid, i.e., contain a single chromosome copy. The exception is the oligoploid strain Synechococcus sp. WH7803, which on average possesses around 4 chromosome copies. Here, we set out to understand the role of resource availability (through nutrient deplete growth) and physical stressors (UV, exposure to low and high temperature) in regulating ploidy level in this strain. Using qPCR to assay ploidy status we demonstrate the relative stability of chromosome copy number in Synechococcus sp. WH7803. Such robustness in maintaining an oligoploid status even under nutrient and physical stress is indicative of a fundamental role, perhaps facilitating recombination of damaged DNA regions as a result of prolonged exposure to oxidative stress, or allowing added flexibility in gene expression via possessing multiple alleles. © 2018 The Authors. Environmental Microbiology published by Society for Applied Microbiology and JohnWiley & Sons Ltd.

  11. Present and future global distributions of the marine Cyanobacteria Prochlorococcus and Synechococcus

    Science.gov (United States)

    Flombaum, Pedro; Gallegos, José L.; Gordillo, Rodolfo A.; Rincón, José; Zabala, Lina L.; Jiao, Nianzhi; Karl, David M.; Li, William K. W.; Lomas, Michael W.; Veneziano, Daniele; Vera, Carolina S.; Vrugt, Jasper A.; Martiny, Adam C.

    2013-01-01

    The Cyanobacteria Prochlorococcus and Synechococcus account for a substantial fraction of marine primary production. Here, we present quantitative niche models for these lineages that assess present and future global abundances and distributions. These niche models are the result of neural network, nonparametric, and parametric analyses, and they rely on >35,000 discrete observations from all major ocean regions. The models assess cell abundance based on temperature and photosynthetically active radiation, but the individual responses to these environmental variables differ for each lineage. The models estimate global biogeographic patterns and seasonal variability of cell abundance, with maxima in the warm oligotrophic gyres of the Indian and the western Pacific Oceans and minima at higher latitudes. The annual mean global abundances of Prochlorococcus and Synechococcus are 2.9 ± 0.1 × 1027 and 7.0 ± 0.3 × 1026 cells, respectively. Using projections of sea surface temperature as a result of increased concentration of greenhouse gases at the end of the 21st century, our niche models projected increases in cell numbers of 29% and 14% for Prochlorococcus and Synechococcus, respectively. The changes are geographically uneven but include an increase in area. Thus, our global niche models suggest that oceanic microbial communities will experience complex changes as a result of projected future climate conditions. Because of the high abundances and contributions to primary production of Prochlorococcus and Synechococcus, these changes may have large impacts on ocean ecosystems and biogeochemical cycles. PMID:23703908

  12. Envelope structure of Synechococcus sp. WH8113, a nonflagellated swimming cyanobacterium

    Directory of Open Access Journals (Sweden)

    Reese Thomas S

    2001-04-01

    Full Text Available Abstract Background Many bacteria swim by rotating helical flagellar filaments [1]. Waterbury et al. [15] discovered an exception, strains of the cyanobacterium Synechococcus that swim without flagella or visible changes in shape. Other species of cyanobacteria glide on surfaces [2,7]. The hypothesis that Synechococcus might swim using traveling surface waves [6,13] prompted this investigation. Results Using quick-freeze electron microscopy, we have identified a crystalline surface layer that encloses the outer membrane of the motile strain Synechococcus sp. WH8113, the components of which are arranged in a rhomboid lattice. Spicules emerge in profusion from the layer and extend up to 150 nm into the surrounding fluid. These spicules also send extensions inwards to the inner cell membrane where motility is powered by an ion-motive force [17]. Conclusion The envelope structure of Synechococcus sp. WH8113 provides new constraints on its motile mechanism. The spicules are well positioned to transduce energy at the cell membrane into mechanical work at the cell surface. One model is that an unidentified motor embedded in the cell membrane utilizes the spicules as oars to generate a traveling wave external to the surface layer in the manner of ciliated eukaryotes.

  13. 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 ...

  14. 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...

  15. 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

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

    Directory of Open Access Journals (Sweden)

    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

  17. Morphology, Chemistry and Function of the Postpharyngeal Gland in the South American Digger Wasps Trachypus boharti and Trachypus elongatus

    Science.gov (United States)

    Herzner, Gudrun; Kaltenpoth, Martin; Poettinger, Theodor; Weiss, Katharina; Koedam, Dirk; Kroiss, Johannes; Strohm, Erhard

    2013-01-01

    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 embalming may have

  18. 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...... transfected. Parvalbumin-transfected and mock-transfected cells were loaded with the calcium indicator fura-2 and were exposed, in the same dish, to different concentrations of the calcium ionophore A23187 or to KCI. The results show that parvalbumin-transfected PCC7 cells had much better calcium buffering...

  19. Estimates of bacterioplankton and Synechococcus spp. mortality from nanoflagellate grazing and viral lysis in the subtropical Danshui River estuary

    Science.gov (United States)

    Tsai, An-Yi; Gong, Gwo-Ching; Huang, Yu Wen; Chao, Chien Fu

    2015-02-01

    To better understand picoplankton dynamics in the surface waters of upriver the Danshui River and its estuary, we assessed nanoflagellate-induced and virus-induced mortality of bacteria and Synechococcus spp. during different seasons (October, 2012 and January, April and July, 2013) using a modified dilution technique. Bacteria and viruses were significantly higher in abundance upriver than at the estuary. The distribution of Synechococcus spp. did not follow this spatial pattern. Abundance of Synechococcus spp. was relatively low during the whole sampling period in the upriver region. Furthermore, bacterial mortality resulting from nanoflagellate grazing were generally higher than those resulting from viral lysis in the upriver region, while Synechococcus spp. losses appeared to be mainly due to viral lysis upriver and in the estuary. Our dilution experiments suggested that nanoflagellates largely depend on bacteria as an important energy source there.

  20. Transfected parvalbumin alters calcium homeostasis in teratocarcinoma PCC7 cells

    DEFF Research Database (Denmark)

    Müller, B K; Kabos, P; Belhage, B

    1996-01-01

    transfected. Parvalbumin-transfected and mock-transfected cells were loaded with the calcium indicator fura-2 and were exposed, in the same dish, to different concentrations of the calcium ionophore A23187 or to KCI. The results show that parvalbumin-transfected PCC7 cells had much better calcium buffering...

  1. 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.

  2. GC/MS analysis of piperidinocyclohexanecarbonitrile (PCC) smoking products

    Energy Technology Data Exchange (ETDEWEB)

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

    1986-03-05

    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 /sup 3/H-piperidino-/sup 14/C-cyano-PCC (synthesized in the lab and recrystallized twice, m.p. 67/sup 0/C) and burned under conditions which simulated smoking. Mainstream smoke was passed through glass wool filters and H/sub 2/SO/sub 4/ and NaOH traps. Tritium and /sup 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 /sup 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%).

  3. 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...

  4. A functional compartmental model of the Synechocystis PCC 6803 phycobilisome

    NARCIS (Netherlands)

    van Stokkum, Ivo H. M.; Gwizdala, Michal; Tian, Lijin; Snellenburg, Joris J.; van Grondelle, Rienk; van Amerongen, Herbert; Berera, Rudi

    In the light-harvesting antenna of the Synechocystis PCC 6803 phycobilisome (PB), the core consists of three cylinders, each composed of four disks, whereas each of the six rods consists of up to three hexamers (Arteni et al., Biochim Biophys Acta 1787(4):272–279, 2009). The rods and core contain

  5. A functional compartmental model of the Synechocystis PCC 6803 phycobilisome

    NARCIS (Netherlands)

    Stokkum, van Ivo H.M.; Gwizdala, Michal; Tian, Tian; Snellenburg, Joris J.; Grondelle, van Rienk; Amerongen, van Herbert; Berera, Rudi

    2018-01-01

    In the light-harvesting antenna of the Synechocystis PCC 6803 phycobilisome (PB), the core consists of three cylinders, each composed of four disks, whereas each of the six rods consists of up to three hexamers (Arteni et al., Biochim Biophys Acta 1787(4):272–279, 2009). The rods and core contain

  6. Blue light emitting diodes (LEDs) as an energy source in Chlorella fusca and Synechococcus nidulans cultures.

    Science.gov (United States)

    Duarte, Jessica Hartwig; Costa, Jorge Alberto Vieira

    2018-01-01

    LEDs have narrow wavelength bands, which can influence microalgae biomass. This study pioneers the evaluation of blue LEDs as an energy source in Chlorella fusca and Synechococcus nidulans cultures. Blue LEDs increased the specific growth rate in Synechococcus nidulans LEB 115 cultures by 80% compared to the standard light used in indoor cultivations. Moreover, blue LEDs also induced lipid accumulation in Chlorella fusca LEB 111 cells, yielding concentrations of this bioproduct of up to 23% (ww -1 ). The chlorophylls and carotenoids were photostimulated proportionally to the LED light intensity. When the intensity of the blue LEDs was increased from 50 to 150μmolm -2 s -1 , the biomass accumulated up to 4.5 and 2.4 times more chlorophylls and carotenoids, respectively. The potential of blue LEDs as an alternative environmentally friendly light source to stimulate biomass and metabolite production for different purposes was demonstrated. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. 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)

  8. 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.

    . Introduction Picophytoplankton (PP; < 3 µm) have been recognized as significant contributors to the total phytoplankton biomass and primary production in marine (Platt et al., 1983) and freshwater ecosystems (Paerl, 1977). PP comprises two major groups... of cyanobacteria, Prochlorococcus and Synechococcus (SYN) and small eukaryotes known as picoeukaryotes. Prochlorococcus is abundant in oligotrophic waters whereas picoeukaryotes are abundant in coastal waters. SYN proliferates in well-lit, eutrophic coastal...

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

    Directory of Open Access Journals (Sweden)

    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.

  10. 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.

  11. 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

  12. 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.

  13. Microevolution in cyanobacteria: re-sequencing a motile substrain of Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Trautmann, Danika; Voss, Björn; Wilde, Annegret; Al-Babili, Salim; Hess, Wolfgang R

    2012-12-01

    Synechocystis sp. PCC 6803 is a widely used model cyanobacterium for studying photosynthesis, phototaxis, the production of biofuels and many other aspects. Here we present a re-sequencing study of the genome and seven plasmids of one of the most widely used Synechocystis sp. PCC 6803 substrains, the glucose tolerant and motile Moscow or 'PCC-M' strain, revealing considerable evidence for recent microevolution. Seven single nucleotide polymorphisms (SNPs) specifically shared between 'PCC-M' and the 'PCC-N and PCC-P' substrains indicate that 'PCC-M' belongs to the 'PCC' group of motile strains. The identified indels and SNPs in 'PCC-M' are likely to affect glucose tolerance, motility, phage resistance, certain stress responses as well as functions in the primary metabolism, potentially relevant for the synthesis of alkanes. Three SNPs in intergenic regions could affect the promoter activities of two protein-coding genes and one cis-antisense RNA. Two deletions in 'PCC-M' affect parts of clustered regularly interspaced short palindrome repeats-associated spacer-repeat regions on plasmid pSYSA, in one case by an unusual recombination between spacer sequences.

  14. Dose assessment intercomparisons within the RENEB network using G0-lymphocyte prematurely condensed chromosomes (PCC assay).

    Science.gov (United States)

    Terzoudi, Georgia I; Pantelias, Gabriel; Darroudi, Firouz; Barszczewska, Katarzyna; Buraczewska, Iwona; Depuydt, Julie; Georgieva, Dimka; Hadjidekova, Valeria; Hatzi, Vasiliki I; Karachristou, Ioanna; Karakosta, Maria; Meschini, Roberta; M'Kacher, Radhia; Montoro, Alegria; Palitti, Fabrizio; Pantelias, Antonio; Pepe, Gaetano; Ricoul, Michelle; Sabatier, Laure; Sebastià, Natividad; Sommer, Sylwester; Vral, Anne; Zafiropoulos, Demetre; Wojcik, Andrzej

    2017-01-01

    Dose assessment intercomparisons within the RENEB network were performed for triage biodosimetry analyzing G 0 -lymphocyte PCC for harmonization, standardization and optimization of the PCC assay. Comparative analysis among different partners for dose assessment included shipment of PCC-slides and captured images to construct dose-response curves for up to 6 Gy γ-rays. Accident simulation exercises were performed to assess the suitability of the PCC assay by detecting speed of analysis and minimum number of cells required for categorization of potentially exposed individuals. Calibration data based on Giemsa-stained fragments in excess of 46 PCC were obtained by different partners using galleries of PCC images for each dose-point. Mean values derived from all scores yielded a linear dose-response with approximately 4 excess-fragments/cell/Gy. To unify scoring criteria, exercises were carried out using coded PCC-slides and/or coded irradiated blood samples. Analysis of samples received 24 h post-exposure was successfully performed using Giemsa staining (1 excess-fragment/cell/Gy) or centromere/telomere FISH-staining for dicentrics. Dose assessments by RENEB partners using appropriate calibration curves were mostly in good agreement. The PCC assay is quick and reliable for whole- or partial-body triage biodosimetry by scoring excess-fragments or dicentrics in G 0 -lymphocytes. Particularly, analysis of Giemsa-stained excess PCC-fragments is simple, inexpensive and its automation could increase throughput and scoring objectivity of the PCC assay.

  15. Effect of the ration processing on the apparent digestibility values of nutrients for the piau (Leporinus elongatus Efeito do tipo de ração sobre a digestibilidade aparente dos nutrientes para piau (Leporinus elongatus

    Directory of Open Access Journals (Sweden)

    Priscila Vieira Rosa Logato

    2009-06-01

    Full Text Available The experiment carried out at National Center for Research in Tropical Fish Pirassununga, SP, aiming to determine the effect of the ration processing on the apparent digestibility coefficients of the ingredients for the piau (L. elongatus. A total of 600 males of piau were utilized, allotted into six ponds of 300L. The applied treatments were: grinder processed ration, pelleting ration and extruded ration, utilizing rations with 32% crude protein and 3400 Kcal DE.Kg-1. The experiment was in a randomized blocks design with three treatments, three blocks and two replicates. The data were submitted to variance analysis by the SAEG computational package and the means of the treatments compared by SNK test (5% of significance. The results showed that there were significant differences among the digestibility coefficients of both protein and energy for the pelleted and extrused rations (P0.05.O experimento foi realizado no Centro Nacional de Pesquisa de Peixes Tropicais de Pirassununga, SP, objetivando-se determinar o efeito do processamento da ração sobre os coeficientes de digestibilidade aparente dos ingredientes para o piau (L. elongatus. Foram utilizados 600 machos de piau, distribuídos em seis tanques de 300 L. Os tratamentos aplicados foram: ração farelada, ração peletizada e ração extrusada, formuladas com 32% de PB e 3400 Kcal ED/Kg. O delineamento experimental foi em blocos casualizados, com três tratamentos, três blocos e duas repetições por tratamento. As análises estatísticas foram realizadas pelo SAEG, com as médias comparadas pelo teste SNK (5%. Houve diferenças entre os coeficientes de digestibilidade da proteína bruta e energia para as rações peletizada e extusada (P0,05.

  16. Culture time and reagent minimization in the chemical PCC assay.

    Science.gov (United States)

    Romero, Ivonne; Lamadrid, Ana Ilsa; González, Jorge Ernesto; Mandina, Tania; García, Omar

    2016-10-01

    The possibility to reduce the culture time and volume of blood and reagents required for the chemical Premature Chromosome Condensation (PCC) assay is demonstrated in this work. Peripheral whole blood was exposed to gamma radiation (1-20 Gy). Lymphocytes were cultured for 40 h, using 50 μl of blood and 450 μl of culture medium. The dose-response curves were adjusted, using length ratio (LR) of the longest to the shortest chromosome piece, and the frequency of rings per cell. No statistical differences were found between the results obtained with this method and those reported with the classical PCC assay culture. The minimization of culture time and reagents in combination with the automatic measurement of the LR of the chromosome pieces, or the scoring of rings, can be a valuable biodosimetry tool in a mass casualty scenario.

  17. 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

  18. Rational ‘correction’ of the amino-acid sequence of RbcX protein from the thermophilic cyanobacterium Thermosynechococcus elongatus dramatically improves crystallization

    International Nuclear Information System (INIS)

    Tarnawski, Miroslaw; Krzywda, Szymon; Szczepaniak, Andrzej; Jaskolski, Mariusz

    2008-01-01

    Recombinant RuBisCO chaperone from T. elongatus, TeRbcX, was aggregated and could not be crystallized. Mutations of an unusual Cys residue in the TeRbcX sequence yielded much better behaved proteins that could rapidly be crystallized. RbcX is a dimeric protein found in cyanobacteria that assists in the assembly of the oligomeric RuBisCO complex. RbcX from the thermophile Thermosynechococcus elongatus (TeRbcX) contains an unusual Cys103 residue in its sequence and when expressed recombinantly the protein aggregates and cannot be crystallized. Site-directed mutagenesis of Cys103 to either Arg or Ala produced non-aggregating proteins that could be readily crystallized in several crystal forms. Synchrotron-radiation X-ray diffraction data were collected to 1.96 Å resolution and formed the basis of crystal structure analysis of TeRbcX

  19. 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.

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

    Science.gov (United States)

    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.

  1. Junto e misturado, uma etnografia do PCC (Maria Biondi

    Directory of Open Access Journals (Sweden)

    Iván Parra Toro

    2011-01-01

    Full Text Available Al estudiar la fascinante diversidad socio-cultural brasileña solemos dejar de lado, injustificadamente, la considerable producción de los antropólogos brasileños. En este sentido, merece la pena detenerse en el controvertido libro de Karina Biondi, Junto e misturado, una etnografía do PCC, que podríamos traducir libremente como “Juntos y revueltos. Una etnografía del Primer Comando de la Capital”.

  2. 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...

  3. Toxin-Antitoxin Systems in Estuarine Synechococcus Strain CB0101 and Their Transcriptomic Responses to Environmental Stressors

    Directory of Open Access Journals (Sweden)

    David Marsan

    2017-07-01

    Full Text Available Bacterial toxin–antitoxin (TA systems are genetic elements composed of a toxin gene and its cognate antitoxin, with the ability to regulate growth. TA systems have not previously been reported in marine Synechococcus or Prochlorococcus. Here we report the finding of seven TA system pairs (Type II in the estuarine Synechococcus CB0101, and their responses of these TA genes to under different stress conditions, which include; nitrogen and phosphate starvation, phage infection, zinc toxicity, and photo-oxidation. Database searches discovered that eight other marine Synechococcus strains also contain at least one TA pair but none were found in Prochlorococcus. We demonstrate that the relB/relE TA pair was active and resulted in RNA degradation when CB0101 was under oxidative stress caused by either zinc toxicity or high light intensities, but the growth inhibition was released when the stress was removed. Having TA systems allows Synechococcus CB0101 to adapt to the low light and highly variable environments in the Chesapeake Bay. We propose that TA systems could be more important for picocyanobacteria living in the freshwater and estuarine environments compared to those living in the open ocean.

  4. 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

  5. Adaptation to Blue Light in MarineSynechococcusRequires MpeU, an Enzyme with Similarity to Phycoerythrobilin Lyase Isomerases.

    Science.gov (United States)

    Mahmoud, Rania M; Sanfilippo, Joseph E; Nguyen, Adam A; Strnat, Johann A; Partensky, Frédéric; Garczarek, Laurence; Abo El Kassem, Nabil; Kehoe, David M; Schluchter, Wendy M

    2017-01-01

    Marine Synechococcus has successfully adapted to environments with different light colors, which likely contributes to this genus being the second most abundant group of microorganisms worldwide. Populations of Synechococcus that grow in deep, blue ocean waters contain large amounts of the blue-light absorbing chromophore phycourobilin (PUB) in their light harvesting complexes (phycobilisomes). Here, we show that all Synechococcus strains adapted to blue light possess a gene called mpeU . MpeU is structurally similar to phycobilin lyases, enzymes that ligate chromophores to phycobiliproteins. Interruption of mpeU caused a reduction in PUB content, impaired phycobilisome assembly and reduced growth rate more strongly in blue than green light. When mpeU was reintroduced in the mpeU mutant background, the mpeU- less phenotype was complemented in terms of PUB content and phycobilisome content. Fluorescence spectra of mpeU mutant cells and purified phycobilisomes revealed red-shifted phycoerythrin emission peaks, likely indicating a defect in chromophore ligation to phycoerythrin-I (PE-I) or phycoerythrin-II (PE-II). Our results suggest that MpeU is a lyase-isomerase that attaches a phycoerythrobilin to a PEI or PEII subunit and isomerizes it to PUB. MpeU is therefore an important determinant in adaptation of Synechococcus spp. to capture photons in blue light environments throughout the world's oceans.

  6. 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...

  7. 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.

  8. Crystal structure at 1.5Å resolution of the PsbV2 cytochrome from the cyanobacterium Thermosynechococcus elongatus.

    Science.gov (United States)

    Suga, Michihiro; Lai, Thanh-Lan; Sugiura, Miwa; Shen, Jian-Ren; Boussac, Alain

    2013-10-01

    PsbV2 is a c-type cytochrome present in a very low abundance in the thermophilic cyanobacterium Thermosynechococcus elongatus. We purified this cytochrome and solved its crystal structure at a resolution of 1.5Å. The protein existed as a dimer in the crystal, and has an overall structure similar to other c-type cytochromes like Cytc6 and Cytc550, for example. However, the 5th and 6th heme iron axial ligands were found to be His51 and Cys101, respectively, in contrast to the more common bis-His or His/Met ligands found in most cytochromes. Although a few other c-type cytochromes were suggested to have this axial coordination, this is the first crystal structure reported for a c-type heme with this unusual His/Cys axial coordination. Previous spectroscopic characterizations of PsbV2 are discussed in relation to its structural properties. Copyright © 2013 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

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

    Directory of Open Access Journals (Sweden)

    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.

  10. Delignification and detoxification of peanut shell bio-waste using an extremely halophilic laccase from an Aquisalibacillus elongatus isolate.

    Science.gov (United States)

    Rezaie, Rezvan; Rezaei, Shahla; Jafari, Nasrin; Forootanfar, Hamid; Khoshayand, Mohammad Reza; Faramarzi, Mohammad Ali

    2017-11-01

    Lignocellulose bioconversion is a harsh process requiring the use of surfactants and organic solvents. Consequently, the incorporation of laccases in this bioconversion requires the bioprospecting of enzymes that can remain stable under extreme conditions. An extracellular, highly stable laccase was produced by the halophilic isolate Aquisalibacillus elongatus in submerged liquid culture fermentation. Statistical and non-statistical strategies gave the highest enzymatic activity (8.02 U mL -1 ) following addition of glucose (1.7 g L -1 ), copper sulfate (0.8 g L -1 ), urea (15 g L -1 ), and CaCl 2 (0.8 g L -1 ). The enzyme, after purification using a synthetic affinity support, delignified a peanut shell substrate by 45%. A pH of 8.0 and a temperature of 35 °C were optimal for delignification of this bio-waste material. Addition of [Bmim][PF 6 ], 1,4-dioxane, acetone, and HBT promoted this bio-waste delignification. Bio-treatment in the presence of 50% [Bmim][PF 6 ] gave a maximal lignin removal of 87%. The surfactants tested had no significant effects on the delignification yield. The laccase also detoxified the toxic phenols found in peanut shell waste. The high catalytic efficiency of this enzyme against a lignocellulosic sample under extreme conditions suggests the suitability of this laccase for industrial applications.

  11. 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

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

    Directory of Open Access Journals (Sweden)

    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.

  13. Intensive DNA Replication and Metabolism during the Lag Phase in Cyanobacteria.

    Directory of Open Access Journals (Sweden)

    Satoru Watanabe

    Full Text Available Unlike bacteria such as Escherichia coli and Bacillus subtilis, several species of freshwater cyanobacteria are known to contain multiple chromosomal copies per cell, at all stages of their cell cycle. We have characterized the replication of multi-copy chromosomes in the cyanobacterium Synechococcus elongatus PCC 7942 (hereafter Synechococcus 7942. In Synechococcus 7942, the replication of multi-copy chromosome is asynchronous, not only among cells but also among multi-copy chromosomes. This suggests that DNA replication is not tightly coupled to cell division in Synechococcus 7942. To address this hypothesis, we analysed the relationship between DNA replication and cell doubling at various growth phases of Synechococcus 7942 cell culture. Three distinct growth phases were characterised in Synechococcus 7942 batch culture: lag phase, exponential phase, and arithmetic (linear phase. The chromosomal copy number was significantly higher during the lag phase than during the exponential and linear phases. Likewise, DNA replication activity was higher in the lag phase cells than in the exponential and linear phase cells, and the lag phase cells were more sensitive to nalidixic acid, a DNA gyrase inhibitor, than cells in other growth phases. To elucidate physiological differences in Synechococcus 7942 during the lag phase, we analysed the metabolome at each growth phase. In addition, we assessed the accumulation of central carbon metabolites, amino acids, and DNA precursors at each phase. The results of these analyses suggest that Synechococcus 7942 cells prepare for cell division during the lag phase by initiating intensive chromosomal DNA replication and accumulating metabolites necessary for the subsequent cell division and elongation steps that occur during the exponential growth and linear phases.

  14. Real world usage of PCC to "rapidly" correct warfarin induced coagulopathy.

    Science.gov (United States)

    Toth, Peter; van Veen, Joost Jair; Robinson, Kate; Maclean, Rhona Murray; Hampton, Kingsley Kevin; Laidlaw, Stuart; Makris, Michael

    2013-10-01

    Life threatening bleeding and emergency procedures in patients on vitamin K antagonists are indications for urgent reversal with prothrombin complex concentrate and vitamin K. Rapid reversal in these situations is emphasized in the literature and guidelines, but only very limited information is available on its real life use, especially on the timing of treatment in relation to presentation. We retrospectively audited emergency warfarin reversal in 131 consecutive patients. We studied the indication, use of vitamin K, time between presentation and administration of vitamin K and PCC, effectiveness in INR reduction and clinical outcome. The median PCC dose was 26.8 IU/kg. The median INR was reduced from 3.1 to 1.2. Vitamin K (5 mg) was given in 91.6% of evaluable patients. We found significant delays in administration of PCC and vitamin K. The median time between presentation and administration of vitamin K/PCC was 3.6 and 5.2 hours respectively. The times in intracranial haemorrhage were 2.7 and 3.0 hours and in emergency procedures 17.4 and 15.9 hours respectively. Mortality related to bleeding was 7.6% overall but in patients with intracranial haemorrhage 22.8%. The thrombotic rate within 7 days of reversal was 1.5%. The local protocol for reversal with PCC and vitamin K was adhered to well but the delay in pre-procedural patients, suggests that intravenous vitamin K alone may be sufficient in many cases and PCC administration can be avoided by better planning. Intracranial haemorrhage in warfarinised patients carries a high mortality. Treatment delays should be avoided by making PCC stocks available within emergency departments, simple dosing structures independent of INR and administering PCC without waiting for INR and CT scan results in those with strong suspicion of intracranial haemorrhage and clear trauma. Future reports and studies should always include the time from presentation to PCC treatment.

  15. 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.

  16. Ultrastructural analysis of the shells of Anodontites trapesialis (Lamarck and Anodontites elongatus (Swaison (Mollusca, Bivalvia, Etherioidea from the Mato Grosso Pantanal Region, Brazil Análise da ultraestrutura das conchas de Anodontites trapesialis (Lamarck e Anodontites elongatus (Swaison (Mollusca, Bivalvia, Etherioidea do Pantanal do Mato Grosso, Brasil

    Directory of Open Access Journals (Sweden)

    Claudia T. Callil

    2005-09-01

    Full Text Available Based on optical and SEM microscopic observations, the projections of the outer surface of the periostracum and inner micro-structures of the shell are described and redefined. The outer surface of the periostracum is practically smooth in both species. Considering a mesoscopic view of the periostracum, A. trapesialis (Lamarck, 1819 presents regular corrugations in the form of radial sequences of arches on the disk region, isolated rays or horizontal sequences of rays on the anterior lower region. A. elongatus presents corrugations formed by series of oblique arches on the disc and oblique rays on the carina. Under SEM, micro ridges were more evident in A. elongatus, but a wide diversity of shapes and patterns of micro fringes were observed in A. trapesialis, especially in young individuals. Considering the profile of the shell layers, the periostracum is relatively thin and apparently simple in A. trapesialis and thinner in A. elongatus. The prismatic layer is thick in both species, consisting of a single series of elongated prisms and wedge-shaped prisms close to the outer surface. The nacreous layer consists of very fine lamellae without pattern or with a slight staircase-like; in A. elongatus this layer is divided by a laminar inclusion of conchiolin. The fringes are abundant and diversified in A. trapesialis, a species less resistant to desiccation due to the presence of a wide intervalvar gap. The existence of a greater density of micro fringes and spikes in juveniles may be related to the orientation of the animal in order to search for an ideal site for development or for escape from regions subject to seasonal droughts, like Pantanal.Projeções da superfície externa do perióstraco e micro estruturas da concha foram redefinidas com base na microscopia óptica e eletrônica de varredura. A superfície do perióstraco é praticamente lisa em ambas espécies. Sob vista mesoscópica, A. trapesialis (Lamarck, 1819 apresenta corruga

  17. A synthetic, light-driven consortium of cyanobacteria and heterotrophic bacteria enables stable polyhydroxybutyrate production.

    Science.gov (United States)

    Weiss, Taylor L; Young, Eric J; Ducat, Daniel C

    2017-11-01

    We previously reported that Synechococcus elongatus PCC 7942, engineered with the sucrose transporter CscB, can export up to 85% of its photosynthetically-fixed carbon as sucrose and shows considerable promise as an alternative carbohydrate source. One approach to effectively utilize this cyanobacterium is to generate synthetic, light-driven consortia in which sucrose-metabolizing heterotrophs catalyze the conversion of the low-value carbohydrate into higher-value compounds in co-culture. Here, we report an improved synthetic photoautotroph/chemoheterotroph consortial design in which sucrose secreted by S. elongatus CscB directly supports the bacterium Halomonas boliviensis, a natural producer of the bioplastic precursor, PHB. We show that alginate encapsulation of S. elongatus CscB enhances sucrose-export rates ~2-fold within 66h, to ~290mg sucrose L -1 d -1 OD 750 -1 and enhances the co-culture stability. Consortial H. boliviensis accumulate up to 31% of their dry-weight as PHB, reaching productivities up to 28.3mg PHB L -1 d -1 . This light-driven, alginate-partitioned co-culture platform achieves PHB productivities that match or exceed those of traditionally engineered cyanobacterial monocultures. Importantly, S. elongatus CscB/H. boliviensis co-cultures were continuously productive for over 5 months and resisted invasive microbial species without the application of antibiotics or other chemical selection agents. Copyright © 2017 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

  18. Evaluation of dowel bar inserter practices in PCC pavements with magnetic tomography technology : final report.

    Science.gov (United States)

    2016-12-01

    Dowel Bar Inserters (DBI) are automated mechanical equipment that position dowel bars in Portland Cement Concrete (PCC) after concrete is placed. Compared to the alternative approach, which is using dowel baskets, DBIs offer advantages in cost and sp...

  19. Influence on cell proliferation of background radiation or exposure to very low, chronic gamma radiation. [Paramecium tetraurelia; Synechococcus lividus

    Energy Technology Data Exchange (ETDEWEB)

    Planel, H.; Soleilhavoup, J.P.; Tixador, R.; Richoilley, G.; Conter, A.; Croute, F.; Caratero, C.; Gaubin, Y.

    1987-05-01

    Investigations carried out on the protozoan Paramecium tetraurelia and the cyanobacteria Synechococcus lividus, which were shielded against background radiation or exposed to very low doses of gamma radiation, demonstrated that radiation can stimulate the proliferation of these two single-cell organisms. Radiation hormesis depends on internal factors (age of starting cells) and external factors (lighting conditions). The stimulatory effect occurred only in a limited range of doses and disappeared for dose rates higher than 50 mGy/y.

  20. Effect of malic enzyme on ethanol production by Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Yoshikawa, Katsunori; Hirasawa, Takashi; Shimizu, Hiroshi

    2015-01-01

    We investigated effects of malic enzyme on ethanol production by Synechocystis sp. PCC 6803 under autotrophic conditions. Deletion of me, which encodes malic enzyme, decreased ethanol production, whereas its overexpression had no effect. Our results suggest that maintaining optimal malic enzyme activity controls ethanol production by Synechocystis sp. PCC 6803. Copyright © 2014 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  1. [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.

  2. 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.

  3. Analysis of the solution structure of Thermosynechococcus elongatus photosystem I in n-dodecyl-β-D-maltoside using small-angle neutron scattering and molecular dynamics simulation.

    Science.gov (United States)

    Le, Rosemary K; Harris, Bradley J; Iwuchukwu, Ifeyinwa J; Bruce, Barry D; Cheng, Xiaolin; Qian, Shuo; Heller, William T; O'Neill, Hugh; Frymier, Paul D

    2014-05-15

    Small-angle neutron scattering (SANS) and molecular dynamics (MD) simulation were used to investigate the structure of trimeric photosystem I (PSI) from Thermosynechococcus elongatus (T. elongatus) stabilized in n-dodecyl-β-d-maltoside (DDM) detergent solution. Scattering curves of detergent and protein-detergent complexes were measured at 18% D2O, the contrast match point for the detergent, and 100% D2O, allowing observation of the structures of protein/detergent complexes. It was determined that the maximum dimension of the PSI-DDM complex was consistent with the presence of a monolayer belt of detergent around the periphery of PSI. A dummy-atom reconstruction of the shape of the complex from the SANS data indicates that the detergent envelope has an irregular shape around the hydrophobic periphery of the PSI trimer rather than a uniform, toroidal belt around the complex. A 50 ns MD simulation model (a DDM ring surrounding the PSI complex with extra interstitial DDM) of the PSI-DDM complex was developed for comparison with the SANS data. The results suggest that DDM undergoes additional structuring around the membrane-spanning surface of the complex instead of a simple, relatively uniform belt, as is generally assumed for studies that use detergents to solubilize membrane proteins. Copyright © 2014 Elsevier Inc. All rights reserved.

  4. 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.

  5. 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.

  6. 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 ...

  7. "You produce while I clean up", a strategy revealed by exoproteomics during Synechococcus-Roseobacter interactions.

    Science.gov (United States)

    Christie-Oleza, Joseph A; Scanlan, David J; Armengaud, Jean

    2015-10-01

    Most of the energy that is introduced into the oceans by photosynthetic primary producers is in the form of organic matter that then sustains the rest of the food web, from micro to macro-organisms. However, it is the interactions between phototrophs and heterotrophs that are vital to maintaining the nutrient balance of marine microbiomes that ultimately feed these higher trophic levels. The primary produced organic matter is mostly remineralized by heterotrophic microorganisms but, because most of the oceanic dissolved organic matter is in the form of biopolymers, and microbial membrane transport systems operate with molecules microorganism can acquire it. As a simili of the marine microbiome, we analyzed, using state-of-the-art proteomics, the exoproteomes obtained from synthetic communities combining specific Roseobacter (Ruegeria pomeroyi DSS-3, Roseobacter denitrificans OCh114, and Dinoroseobacter shibae DFL-12) and Synechococcus strains (WH7803 and WH8102). This approach identified the repertoire of hydrolytic enzymes secreted by Roseobacter, opening up the black box of heterotrophic transformation/remineralization of biopolymers generated by marine phytoplankton. As well as highlighting interesting exoenzymes this strategy also allowed us to infer clues on the molecular basis of niche partitioning. © 2015 The Authors. PROTEOMICS published by Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  10. Biodosimetry for high dose accidental exposures by drug induced premature chromosome condensation (PCC) assay.

    Science.gov (United States)

    Balakrishnan, Sreedevi; Shirsath, Kapil; Bhat, Nagesh; Anjaria, Kshiti

    2010-06-17

    The conventional dicentric assay does not provide an accurate dose estimate in the case of accidental exposure to ionizing radiation above 6 Gy due to mitotic delay and poor mitotic index. The present study aims to establish a simple and rapid dose assessment technique based on scoring of rings and fragments in PCC spreads of stimulated lymphocytes. Human peripheral blood lymphocytes were gamma irradiated to different doses (6.2-24.5 Gy), cultured for two days with PHA and were forced to condense prematurely using 500 nM Okadaic acid (OA). The chromosome spreads were prepared, stained with Giemsa and observed under a microscope. The PCC index, PCC rings, and PCC fragments were scored for each dose point to arrive at the dose effect curve for various end points such as induction of rings and fragments and dicentrics. The PCC index varied from 12-18% up to 18 Gy and thereafter dropped to 6-8% at higher doses. The dose dependent increase in rings and fragments was found to be linear with a slope of 0.054+/-0.001 Gy(-1) for rings and 0.45+/-0.03 Gy(-1) for PCC fragments. An experiment was carried out to simulate partial-body exposure by mixing 10 Gy in vitro irradiated blood with un-irradiated blood in different proportions. The ratio of frequency of damaged cells among the total number of cells analyzed was found to be a good index of partial-body exposure. The culture duration was extended to 72 h to overcome the cell cycle delay induced by high doses of radiation. The conventional dicentrics rings and fragments also showed a dose response at high doses. The response can be best fitted to a linear model with a slope of 0.28+/-0.0007 Gy(-1) for the induction of dicentrics. However, long culture duration, technical skill and time required to analyse multi-aberrant cells makes the dicentric assay less suitable for high dose exposures requiring a rapid dose estimate. The PCC assay can be performed in 50 h with biodosimetric information about the irradiated fraction in

  11. Increased biomass production and glycogen accumulation in apcE gene deleted Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Joseph, Ancy; Aikawa, Shimpei; Sasaki, Kengo; Matsuda, Fumio; Hasunuma, Tomohisa; Kondo, Akihiko

    2014-01-01

    The effect of phycobilisome antenna-truncation in the cyanobacterium Synechocystis sp. PCC 6803 on biomass production and glycogen accumulation have not yet been fully clarified. To investigate these effects here, the apcE gene, which encodes the anchor protein linking the phycobilisome to the thylakoid membrane, was deleted in a glucose tolerant strain of Synechocystis sp. PCC 6803. Biomass production of the apcE-deleted strain under photoautotrophic and atmospheric air conditions was 1.6 times higher than that of strain PCC 6803 (1.32 ± 0.01 versus 0.84 ± 0.07 g cell-dry weight L(-1), respectively) after 15 days of cultivation. In addition, the glycogen content of the apcE-deleted strain (24.2 ± 0.7%) was also higher than that of strain PCC 6803 (11.1 ± 0.3%). Together, these results demonstrate that antenna truncation by deleting the apcE gene was effective for increasing biomass production and glycogen accumulation under photoautotrophic and atmospheric air conditions in Synechocystis sp. PCC 6803.

  12. Suitability of scoring PCC rings and fragments for dose assessment after high-dose exposures to ionizing radiation.

    Science.gov (United States)

    Puig, Roser; Barrios, Leonardo; Pujol, Mònica; Caballín, Maria Rosa; Barquinero, Joan-Francesc

    2013-09-18

    Assessment of radiation doses through measurement of dicentric chromosomes may be difficult due to the inability of damaged cells to reach mitosis. After high-dose exposures, premature chromosome condensation (PCC) has become an important method in biodosimetry. PCC can be induced upon fusion with mitotic cells, or by treatment with chemicals such as calyculin A or okadaic acid. Several different cytogenetic endpoints have been measured with chemically induced PCC, e.g., via scoring of extra chromosome pieces or ring chromosomes. The dose-effect curves published with chemically induced PCC show differences in their coefficients and in the distribution of rings among cells. Here we present a study with calyculin A to induce PCC in peripheral blood lymphocytes irradiated at nine different doses of γ-rays up to 20Gy. Colcemid was also added in order to observe metaphase cells. During microscopical analysis the chromosome aberrations observed in the different cell-cycle phases (G2/M-PCC, M/A-PCC and M cells) were recorded. The proportion of G2/M-PCC cells was predominant from 3 to 20Gy, M cells decreased above 1Gy and M/A-PCC cells remained constant at all doses and showed the highest frequencies of PCC rings. Depending on the cell-cycle phase there was a difference in the linear coefficients in the dose-effect curves of extra fragments and rings. Poisson distribution among PCC rings was observed after calyculin A+colcemid treatment, facilitating the use of this methodology also for partial body exposures to high doses. This has been tested with two simulated partial exposures to 6 and 12Gy. The estimated doses in the irradiated fraction were very close to the real dose, indicating the usefulness of this methodology. Copyright © 2013 Elsevier B.V. All rights reserved.

  13. Arsenic biotransformation by a cyanobacterium Nostoc sp. PCC 7120.

    Science.gov (United States)

    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.

  14. DTI and MR Volumetry of Hippocampus-PC/PCC Circuit: In Search of Early Micro- and Macrostructural Signs of Alzheimers's Disease.

    Science.gov (United States)

    Palesi, F; Vitali, P; Chiarati, P; Castellazzi, G; Caverzasi, E; Pichiecchio, A; Colli-Tibaldi, E; D'Amore, F; D'Errico, I; Sinforiani, E; Bastianello, S

    2012-01-01

    Hippocampal damage, by DTI or MR volumetry, and PET hypoperfusion of precuneus/posterior cingulate cortex (PC/PCC) were proposed as biomarkers of conversion from preclinical (MCI) to clinical stage of Alzheimer's disease (AD). This study evaluated structural damage, by DTI and MR volumetry, of hippocampi and tracts connecting hippocampus to PC/PCC (hipp-PC/PCC) in 10 AD, 10 MCI, and 18 healthy controls (CTRL). Normalized volumes, mean diffusivity (MD), and fractional anisotropy (FA) were obtained for grey matter (GM), white matter (WM), hippocampi, PC/PCC, and hipp-PC/PCC tracts. In hippocampi and hipp-PC/PCC tracts, decreased volumes and increased MD were found in AD versus CTRL (P PCC tract MD, and in MCI with FA of total WM. Both DTI and MR volumetry of hippocampi and hipp-PC/PCC tracts detect early signs of AD in MCI patients.

  15. 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.; Mahdi Bendif, E.; Ostrowski, M.; Scanlan, D. J.; Garczarek, L.

    2011-09-01

    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 significantly risen over the last 25 years (0.50 ± 0.11 °C in average per decade, P 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 (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.

  16. Enzyme-mediated Nutrient Regeneration Following Lysis of Synechococcus WH7803

    Science.gov (United States)

    Mine, A. H.; Coleman, M.; Colman, A. S.

    2016-02-01

    Phosphate availability plays a pivotal role in limiting primary production in large regions of the oceans. In order to meet their metabolic needs, microbes use a variety of strategies to overcome phosphate stress. Expression of enzymes such as alkaline phosphatase (APase) allows cells to hydrolyze and use certain ambient dissolved organic phosphorus (DOP) compounds to meet their P demand. Cell lysis releases a range of nutrient forms and enzymes into the ambient environment and is an essential component of the microbial loop. Yet very few studies have attempted to characterize both the immediate and sustained nutrient remineralization linked to the milieu of organophosphorus compounds and enzymatic activity in lysate. We conducted experiments using Synechococcus WH7803 grown under nutrient replete and starved conditions to quantify the release of phosphate during viral lysis and lysis by lysozyme treatment. Dissolved inorganic and organic phosphorus concentrations and APase activity were monitored over time following lysis. We observed a significant initial release of orthophosphate that accompanies lysis. Following lysis, phosphate concentrations continue to rise for a period of hours to days as organophosphorus compounds continue to hydrolyze. Our observations suggest this is due to a combination of direct hydrolysis of DOP released during lysis, solubilization of POP followed by hydrolysis, and possibly polyphosphate decomposition. Size fractionated enzymatic assays suggest cellular debris associated enzymes and dissolved fractions are both important in DOP hydrolysis in the viral lysate, whereas particle associated APase activity dominates in the lysozyme treatments. Moreover, nutrient status prior to lysis has important controls on the initial nutrient release and subsequent regenerative flux. These findings underscore the significance of lysis and subsequent enzyme-mediated hydrolysis in nutrient regeneration and biogeochemical dynamics in marine ecosystems.

  17. 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)

  18. 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)]. e-mail: ana@cphr.edu.cu

    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)

  19. 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.

  20. 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...

  1. 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 Marsdiep (Dutch Wadden Sea) and fed to cultured copepods at a constant temperature of 15 degrees C, thus excluding seasonal effects of temperature, body size, age, and maternal nutrition. Copepod response was evaluated by measuring egg production and juvenile development, while the seston quantity...... and quality were measured as the concentrations of chl a, specific phytoplankton pigments, particulate organic carbon (POC), particulate organic nitrogen (PON), fatty acids, and sterols. The egg production of both copepods was low when feeding on seston collected in winter, but increased to peak values...

  2. 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

  3. 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.

  4. 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.

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

    Directory of Open Access Journals (Sweden)

    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

  6. Cytogenetic markers as diagnoses in the identification of the hybrid between Piauçu (Leporinus macrocephalus and Piapara (Leporinus elongatus

    Directory of Open Access Journals (Sweden)

    Fábio Porto-Foresti

    2008-01-01

    Full Text Available The genetic monitoring of interspecific hybrids involves the application of methodologies able to provide an easy and indubitable genetic characterization of both parental and hybrid individuals. In the present work, cytogenetic techniques were used to identify a hybrid lineage of "Piaupara" in order to caracterize them in relation to the parental species, Leporinus macrocephalus (piauçu and L. elongatus (piapara. The cytogenetic analysis revealed that L. macrocephalus presented 2n = 54 chromosomes and a nucleolar organizer regions (NOR at the telomere of the long arm of the submetacentric chromosome pair 2. Analysis of constitutive heterochromatin (C-banding revealed a conspicuous block at the pericentromeric region on the long arm of a submetacentric chromosome pair. L. elongatus presented the same diploid number, 2n = 54, and a karyotypic formula similar to that of L. macrocephalus. The NORs were also at the telomere of the long arm of the submetacentric pair 2, which was morphologically different from that of L. macrocephalus. Heterochromatic blocks were observed at both telomeres of a submetacentric chromosome pair. The hybrid "Piaupara" presented the same diploid number (2n = 54 and karyotypic formula as the parental species and there were no visible differences between parental and hybrid individuals. Differently from the Giemsa staining, NOR- and C-banding analysis showed marked differences which allowed the identification of the hybrids by the different morphology and/or size of the chromosomes carrying the NORs and patterns of heterochromatin distribution in their chromosomes. Such genetic studies are important for fish culture since they can provide tools for monitoring natural and artificial hybridization. They are also useful in biological conservation programmes and in the proper management of natural and reared fish stocks.

  7. 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

  8. Dynamics of Prochlorococcus and Synechococcus at Station ALOHA Revealed through Flow Cytometry and High-Resolution Vertical Sampling

    Directory of Open Access Journals (Sweden)

    Ger J. van den Engh

    2017-11-01

    Full Text Available The fluorescence and scattering properties of Prochlorococcus and Synechococcus at Station ALOHA as measured by flow cytometry (termed the FCM phenotype vary with depth and over a variety of time scales. The variation in FCM phenotypes may reflect population selection or physiological acclimation to local conditions. Observations before, during, and after a storm with deep water mixing show a short-term homogenization of the FCM phenotypes with depth, followed by a return to the stable pattern over the time span of a few days. These dynamics indicate that, within the upper mixed-layer, the FCM phenotype distribution represents acclimation to ambient light. The populations in the pycnocline (around 100 m and below, remain stable and are invariant with light conditions. In samples where both cyanobacteria coexist, fluorescence properties of Prochlorococcus and Synechococcus are tightly correlated providing further evidence that FCM phenotype variability is caused by a common environmental factor or factors. Measurements of the dynamics of FCM phenotypes provide insights into phytoplankton physiology and adaptation. Alternatively, FCM phenotype census of a water mass may provide information about its origin and illumination history.

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

    Directory of Open Access Journals (Sweden)

    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.

  10. Shortening the culture time in cytogenetic dosimetry using PCC-R assay.

    Science.gov (United States)

    Romero, Ivonne; Lamadrid, Ana Ilsa; González, Jorge Ernesto; García, Omar; Voisin, Philippe; Roy, Laurence

    2015-03-01

    The fast assessment of the dose received by exposed persons is crucial in radiological accidents, so the 48 h of cell culture in conventional cytogenetic dosimetry in addition to some limitations after high doses becomes a disadvantage. The premature chromosome condensation (PCC) assay permits to analyse enough cells after high radiation exposure, and the score of PCC-R may reduce the culture time up to 40-42 h. Peripheral whole-blood samples were exposed to 1-10 Gy of gamma radiation and cultured during 40 and 42 h. No statistical difference between frequencies was obtained between 40, 42 and 48 h of culture time, and PCC index decreased with the increase of the dose and increased with the culture time. The protocol proposed allows reduce the culture time down to 40 or 42 h when using the PCC-R assay with adequate precision in dose estimation. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  11. Computational protein structure modeling and analysis of UV-B stress protein in Synechocystis PCC 6803.

    Science.gov (United States)

    Rahman, Md Akhlaqur; Chaturvedi, Navaneet; Sinha, Sukrat; Pandey, Paras Nath; Gupta, Dwijendra Kumar; Sundaram, Shanthy; Tripathi, Ashutosh

    2013-01-01

    This study focuses on Ultra Violet stress (UVS) gene product which is a UV stress induced protein from cyanobacteria, Synechocystis PCC 6803. Three dimensional structural modeling of target UVS protein was carried out by homology modeling method. 3F2I pdb from Nostoc sp. PCC 7120 was selected as a suitable template protein structure. Ultimately, the detection of active binding regions was carried out for characterization of functional sites in modeled UV-B stress protein. The top five probable ligand binding sites were predicted and the common binding residues between target and template protein was analyzed. It has been validated for the first time that modeled UVS protein structure from Synechocystis PCC 6803 was structurally and functionally similar to well characterized UVS protein of another cyanobacterial species, Nostoc sp PCC 7120 because of having same structural motif and fold with similar protein topology and function. Investigations revealed that UVS protein from Synechocystis sp. might play significant role during ultraviolet resistance. Thus, it could be a potential biological source for remediation for UV induced stress.

  12. 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

  13. Genome-wide responses of Synechocystis PCC6803 to nitrogen deprivation

    NARCIS (Netherlands)

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

    2005-01-01

    Genome-wide responses of Synechocystis PCC6803 to nitrogen deprivation Vladimir Krasikov1, Eneas Aguirre-von-Wobeser1, Jef Huisman1, Bas Ibelings2, Hans C.P. Matthijs1 1Universiteit van Amsterdam, Amsterdam, the Netherlands; 2Netherlands Institute of Ecology, Limnological Institute, Nieuwersluis,

  14. 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.

  15. 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

  16. 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.

  17. Assessment of simulated high-dose partial-body irradiation by PCC-R assay.

    Science.gov (United States)

    Romero, Ivonne; García, Omar; Lamadrid, Ana I; Gregoire, Eric; González, Jorge E; Morales, Wilfredo; Martin, Cécile; Barquinero, Joan-Francesc; Voisin, Philippe

    2013-09-01

    The estimation of the dose and the irradiated fraction of the body is important information in the primary medical response in case of a radiological accident. The PCC-R assay has been developed for high-dose estimations, but little attention has been given to its applicability for partial-body irradiations. In the present work we estimated the doses and the percentage of the irradiated fraction in simulated partial-body radiation exposures at high doses using the PCC-R assay. Peripheral whole blood of three healthy donors was exposed to doses from 0-20 Gy, with ⁶⁰Co gamma radiation. To simulate partial body irradiations, irradiated and non-irradiated blood was mixed to obtain proportions of irradiated blood from 10-90%. Lymphocyte cultures were treated with Colcemid and Calyculin-A before harvest. Conventional and triage scores were performed for each dose, proportion of irradiated blood and donor. The Papworth's u test was used to evaluate the PCC-R distribution per cell. A dose-response relationship was fitted according to the maximum likelihood method using the frequencies of PCC-R obtained from 100% irradiated blood. The dose to the partially irradiated blood was estimated using the Contaminated Poisson method. A new D₀ value of 10.9 Gy was calculated and used to estimate the initial fraction of irradiated cells. The results presented here indicate that by PCC-R it is possible to distinguish between simulated partial- and whole-body irradiations by the u-test, and to accurately estimate the dose from 10-20 Gy, and the initial fraction of irradiated cells in the interval from 10-90%.

  18. Propofol Prevents the Progression of Malignant PCC In Vitro and In Vivo.

    Science.gov (United States)

    Wang, Hua; Zhang, Shu; Zhang, Aihong; Yan, Cunling

    2018-03-22

    This study aimed to explore the efficacy of propofol to treat malignant pheochromocytoma (PCC) in vitro and in vivo. In vitro, PC12 cells were treated with different concentrations of propofol (0, 1, 5, and 10 μg/mL) for specific times followed by a MTT assay to detect cell proliferation. Transwell assays were performed to assess the function of propofol on the migration and invasion of PC12 cells, and flow cytometry to analyze cell apoptosis and cell cycle progression. Quantitative real-time polymerase chain reaction was carried out to analyze the expression level of mRNA (Bcl-2, Bax, and CyclinE). The levels of Bcl-2, Bax, CyclinE, FOXO1, FOXO3, Bim, procaspase-3, and active caspase-3 were determined by western blotting. In vivo, the effects of propofol on PCC tumor growth were detected by transplanted mouse model. Transferase dUTP nick-end labeling was performed to detect tissue cell apoptosis. The results indicated that propofol inhibited PC12 cell proliferation, prevented cell migration and invasion, and induced the apoptosis of PC12 cells in a dose- and time-dependent manner. Propofol treatment increased the expression of Bax and decreased that of Bcl-2. In addition, propofol significantly induced the G1/S phase arrest in PC12 cells, and the expression of Cyclin E was reduced. Moreover, the levels of FOXO1, FOXO3, Bim, procaspase-3, and active caspase-3 were enhanced by propofol treatment. In vivo, propofol treatment significantly reduced the PCC tumor growth and induced tissue cell apoptosis. In conclusion, propofol has potent anti-PCC activity in vitro and in vivo, and is a potential small-molecule drug for treating malignant PCC.

  19. Caracterización molecular y funcional del gen PATHOGEN AND CIRCADIAN CONTROLLED 1 (PCC1) en Arabidopsis thaliana.

    OpenAIRE

    Mir Moreno, Ricardo

    2013-01-01

    Las plantas son capaces de modificar los patrones de desarrollo tras percibir ciertos tipos de estrés. En Arabidopsis, se identificó PCC1 como un regulador positivo de la transición floral en respuesta al estrés generado por irradiación con luz UV-C. El análisis de plantas transgénicas pPCC1::GUS muestra que PCC1 se expresa durante los primeros días de desarrollo en estomas y haces vasculares de cotiledones. En hojas verdaderas en formación se detecta tinción GUS en su part...

  20. 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...

  1. Design and construction of PCC pavements. Volume 2, design features and practices that influence performance of pavements

    Science.gov (United States)

    1998-10-01

    A study has been conducted to evaluate and analyze Portland cement concrete (PCC) pavements in order to develop recommendations for the design and construction of long-lived concrete pavements. In involved a detailed evaluation and analysis of the PC...

  2. Laboratory data to determine impact of coarse aggregate type and cementitious materials on design thickness of PCC pavements.

    Science.gov (United States)

    2016-12-01

    The Mississippi Department of Transportation (MDOT) needed mechanical and volume change properties of portland cement concrete (PCC) pavement in order to implement pavement thickness design procedures of the Mechanistic-Empirical Pavement Design Guid...

  3. Design and construction of PCC pavements, volume 2 : design features and practices that influence performance of pavements.

    Science.gov (United States)

    1998-10-01

    A study has been conducted to evaluate and analyze portland cement concrete (PCC) pavements in order to : develop recommendations for the design and construction of long-lived concrete pavements. It involved a : detailed evaluation and analysis of th...

  4. Design and construction of PCC pavements. Volume 1, summary of design features and construction practices that influence performance of pavements

    Science.gov (United States)

    1998-04-01

    A study has been conducted to evaluate and analyze Portland cement concrete (PCC) pavements in order to develop recommendations for the design and construction of long-lived concrete pavements. In involved a detailed evaluation and analysis of the PC...

  5. Development of a quantitative SRM-based proteomics method to study iron metabolism of Synechocystis sp PCC 6803

    NARCIS (Netherlands)

    Vuorijoki, L.; Isojärvi, J.; Kallio, P.; Kouvonen, P.; Aro, E.M.; Corthals, G.L.; Jones, P.R.; Muth-Pawlak, D.

    2016-01-01

    The cyanobacterium Synechocystis sp. PCC 6803 (S. 6803) is a well-established model species in oxygenic photosynthesis research and a potential host for biotechnological applications. Despite recent advances in genome sequencing and microarray techniques applied in systems biology, quantitative

  6. Genome Sequence of Pectobacterium carotovorum subsp. carotovorum Strain PCC21, a Pathogen Causing Soft Rot in Chinese Cabbage

    OpenAIRE

    Park, Tae-Ho; Choi, Beom-Soon; Choi, Ah-Young; Choi, Ik-Young; Heu, Sunggi; Park, Beom-Seok

    2012-01-01

    Pectobacterium carotovorum is a plant-pathogenic enterobacterium responsible for soft rot in various commercially important plants. Here we report the complete genome sequence and automatic annotation of strain PCC21.

  7. Genome sequence of Pectobacterium carotovorum subsp. carotovorum strain PCC21, a pathogen causing soft rot in Chinese cabbage.

    Science.gov (United States)

    Park, Tae-Ho; Choi, Beom-Soon; Choi, Ah-Young; Choi, Ik-Young; Heu, Sunggi; Park, Beom-Seok

    2012-11-01

    Pectobacterium carotovorum is a plant-pathogenic enterobacterium responsible for soft rot in various commercially important plants. Here we report the complete genome sequence and automatic annotation of strain PCC21.

  8. Validation Data Acquisition in HTTF during PCC Events

    Energy Technology Data Exchange (ETDEWEB)

    Bardet, Philippe

    2018-02-07

    A validation experimental campaign was conducted in an Integral Effect Test (IET) facility of High Temperature Gas Reactors (HTGR), the High-Temperature Test Facility (HTTF) at Oregon State University (OSU). The HTTF simulates Depressurized and Pressurized Conduction Cooldowns (DCC and PCC). This campaign required the development of a new laser spectroscopic diagnostic to measure velocity in the challenging conditions of the HTTF: low speed (~1 m/s) gas flows at HTGR prototypical temperature and 1/10th pressure. This was a collaborative effort between co-PIs at The George Washington University (GW), Oregon State University (OSU), and NASA Langley Research Center. The main accomplishments of this project include the record for dynamic range for velocimetry, highest accuracy obtained with this technique, successful deployment in an IET leading to new validation matrix for CFD. These are detailed below and in manuscript appended to this executive summary. For this project, we introduced a new class of laser spectroscopic diagnostics to Thermal-Hydraulics to measure velocity of gases; furthermore, the diagnostic was demonstrated in-situ in an IET during DCC events. In such scenarios, particles used in mainstream techniques, like Particle Image Velocimetry (PIV) are not appropriate as they settle down too rapidly and also contaminate the experimental facility. Molecular tracers stay mixed within the working gas and can seed the flow in a technique called Molecular Tagging Velocimetry (MTV). In MTV a molecular tracer is photo-dissociated by a first (write) laser into radicals or molecules. The pattern created by the write laser is then interrogated with planar laser-induced fluorescence (PLIF), the read pulse(s), which are recorded with a camera. The pattern is probed and matched at two times (interval or probe time, dt), resulting in a time-of-flight velocimetry technique. This project demonstrated a new application range for MTV in gases. MTV has been extensively used

  9. Dose assessment inter-comparisons within the RENEB network using G0-lymphocyte prematurely condensed chromosomes (PCC assay)

    Science.gov (United States)

    Terzoudi, Georgia I.; Pantelias, Gabriel; Darroudi, Firouz; Barszczewska, Katarzyna; Buraczewska, Iwona; Depuydt, Julie; Georgieva, Dimka; Hadjidekova, Valeria; Hatzi, Vasiliki I.; Karachristou, Ioanna; Karakosta, Maria; Meschini, Roberta; M’Kacher, Radhia; Montoro, Alegria; Palitti, Fabrizio; Pantelias, Antonio; Pepe, Gaetano; Ricoul, Michelle; Sabatier, Laure; Sebastià, Natividad; Sommer, Sylwester; Vral, Anne; Zafiropoulos, Demetre; Wojcik, Andrzej

    2017-01-01

    Purpose Dose assessment inter-comparisons within the RENEB network were performed for triage biodosimetry analysing G0-lymphocyte PCCs for harmonization, standardization and optimization of the PCC-assay. Materials and Methods Comparative analysis among different partners for dose assessment included shipment of PCC-slides and captured images to construct dose-response curves for up to 6Gy γ-rays. Accident simulation exercises were performed to assess the suitability of the PCC-assay by detecting speed of analysis and minimum number of cells required for categorization of potentially exposed individuals. Results Calibration data based on Giemsa stained fragments in excess of 46-PCCs were obtained by different partners using galleries of PCC-images for each dose-point. Mean values derived from all scores yielded a linear dose-response with approximately 4excess-fragments/cell/Gy. To unify scoring criteria, exercises were carried out using coded PCC-slides and/or coded irradiated blood samples. Analysis of samples received 24h post-exposure was successfully performed using Giemsa staining (1excess-fragment/cell/Gy) or centromere/telomere FISH-staining for dicentrics. Conclusions Dose assessments by RENEB partners using appropriate calibration curves were mostly in good agreement. The PCC-assay is quick and reliable for whole- or partial-body triage biodosimetry by scoring excess-fragments or dicentrics in G0-lymphocytes. Particularly, analysis of Giemsa-stained excess PCC-fragments is simple, inexpensive and its automation could increase throughput and scoring objectivity of the PCC-assay. PMID:27813725

  10. On Dichelyne (Cucullanellus elongatus (Tornquist, 1931 Petter, 1974: South American correlated species (Nematoda, Cucullanidae and some other helminths of micropogonias furnieri (Desmarest, 1823 (Pisces, Sciaenidae Sobre Dichelyne (Cucullanellus elongatus (Tornquist, 1931 Petter, 1974: espécies sul americanas correlatas (Nematoda, Cucullanidae e alguns outros helmintos de Micropogonias furnieri (Desmarest, 1823(Pisces, Sciaenidae

    Directory of Open Access Journals (Sweden)

    J. Júlio Vicente

    1989-09-01

    Full Text Available Dichelyne (Cucullanellus elongatus (Tomquist, 1931 Petter, 1974, from Venezuela, of which D.(C. amaurincai (Freitas, Vicente & Ibáñez, 1969 Petter, 1974 is proposed as a junior synonym, is redescribed and comments on the present status of the remaining species under the group, namely D.(C. dichelyneformes (Szidat, 1950 Petter, 1974, D.(C. rodriguesi (Pinto, Fábio & Noronha, 1970 Petter, 1974 and D.(C. travassosi (Guimarães & Cristofaro, 1974, occuring in South America are made. Dollfusentis chandleri Golvan, 1969 (Acanthocephala, Illiosentidae, Poecilancistrium caryophyllum (Diesing, 1850(Cestoidea, Otobothriidae and Callitetrarhynchus gracilis (Rudolphi, 1819(Cestoidea, Dasyrhynchidae as well as larval forms of Echinocephalus sp. (Nematoda, Gnathostomatidae and Contracaecum sp. (Nematoda, Anisakidae are also reported.Dichelyne (Cucullanellus elongatus (Tornquist, 1931 Petter, 1974, da Venezuela, da qual D.(C. amaurincai (Freitas, Vicente & Ibáñez, 1969 Petter, 1974 é proposta como sinônimo junior, é descrita, e são feitos comentários sobre a atual situação das outras espécies do mesmo grupo, ocorrendo na América do Sul, a saber: D.(C. dichelyneformes (Szidat, 1950 Petter, 1974, D.(C. rodriguesi (Pinto, Fábio & Noronha, 1971 Petter, 1974 e D.(C. travassosi (Guimarães & Cristofaro, 1974. Dollfusentis chandleri Golvan, 1969 (Acantochephala, Illiosentidae, Poecilancistrium cariophyllum (Diesing, 1850 (Cestoidea, Otobothriidae e Callitetrarhynchus gracilis (Rudolphi, 1819 (Cestoidea, Dayrhynchidae bem como formas larvares de Exhinocephalus sp. (Nematoda, Gnathostomatidae e Contracaecum sp. (Nematoda, Anisakidae são também assinaladas.

  11. Chemoheterotrophic growth of the Cyanobacterium Anabaena sp. strain PCC 7120 dependent on a functional cytochrome c oxidase.

    Science.gov (United States)

    Stebegg, Ronald; Wurzinger, Bernhard; Mikulic, Markus; Schmetterer, Georg

    2012-09-01

    Anabaena sp. strain PCC 7120 is a filamentous cyanobacterium commonly used as a model organism for studying cyanobacterial cell differentiation and nitrogen fixation. For many decades, this cyanobacterium was considered an obligate photo-lithoautotroph. We now discovered that this strain is also capable of mixotrophic, photo-organoheterotrophic, and chemo-organoheterotrophic growth if high concentrations of fructose (at least 50 mM and up to 200 mM) are supplied. Glucose, a substrate used by some facultatively organoheterotrophic cyanobacteria, is not effective in Anabaena sp. PCC 7120. The gtr gene from Synechocystis sp. PCC 6803 encoding a glucose carrier was introduced into Anabaena sp. PCC 7120. Surprisingly, the new strain containing the gtr gene did not grow on glucose but was very sensitive to glucose, with a 5 mM concentration being lethal, whereas the wild-type strain tolerated 200 mM glucose. The Anabaena sp. PCC 7120 strain containing gtr can grow mixotrophically and photo-organoheterotrophically, but not chemo-organoheterotrophically with fructose. Anabaena sp. PCC 7120 contains five respiratory chains ending in five different respiratory terminal oxidases. One of these enzymes is a mitochondrial-type cytochrome c oxidase. As in almost all cyanobacteria, this enzyme is encoded by three adjacent genes called coxBAC1. When this locus was disrupted, the cells lost the capability for chemo-organoheterotrophic growth.

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

    Science.gov (United States)

    Ketseoglou, Irene; Bouwer, Gustav

    2012-10-04

    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. 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 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. 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.

  13. Investigation possibility of PCC overvoltage transients in power electric system with PAF

    Energy Technology Data Exchange (ETDEWEB)

    Dobrucky, B.; Pavlanin, R.; Benova, M. [Zilina Univ. (Slovakia). Faculty of Electrical Engineering; Abdamula, M.A.R. [Univ. of 7th April, Zawia (Libyan Arab Jamahiriya)

    2009-07-01

    Overvoltages can damage power systems and create potential hazards to system workers. This paper discussed over-voltages that occurred during transient states in a power system comprised of a power active filter connected to a common coupling point. The study investigated the dynamic states of load step changes, source voltage step changes and load failures related to power active filters at the point of connection (PCC). Computerized simulations were developed to model the switching on and switching off of the power active filter at a maximum supply voltage for a linear R-L load. Laboratory experiments conducted to obtain data for the study were also presented. Results of the study demonstrated an overcurrent that corresponded to the charging of the PAF capacitor. It was concluded that the power active filter did not supply energy to the PCC point during overvoltage switch-offs. 10 refs., 10 figs.

  14. 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.

    Science.gov (United States)

    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.

  15. 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

  16. Premethylation of Foreign DNA Improves Integrative Transformation Efficiency in Synechocystis sp. Strain PCC 6803

    OpenAIRE

    Wang, Bo; Yu, Jianping; Zhang, Weiwen; Meldrum, Deirdre R.

    2015-01-01

    Restriction digestion of foreign DNA is one of the key biological barriers against genetic transformation in microorganisms. To establish a high-efficiency transformation protocol in the model cyanobacterium, Synechocystis sp. strain PCC 6803 (Synechocystis 6803), we investigated the effects of premethylation of foreign DNA on the integrative transformation of this strain. In this study, two type II methyltransferase-encoding genes, i.e., sll0729 (gene M) and slr0214 (gene C), were cloned fro...

  17. Characterization of a new bacteriocin, Carocin D, from Pectobacterium carotovorum subsp. carotovorum Pcc21.

    Science.gov (United States)

    Roh, Eunjung; Park, Tae-Ho; Kim, Myung-Il; Lee, Seungdon; Ryu, Sangryeol; Oh, Chang-Sik; Rhee, Sangkee; Kim, Doo-Ho; Park, Beom-Seok; Heu, Sunggi

    2010-11-01

    Two different bacteriocins, carotovoricin and carocin S1, had been found in Pectobacterium carotovorum subsp. carotovorum, which causes soft-rot disease in diverse plants. Previously, we reported that the particular strain Pcc21, producing only one high-molecular-weight bacteriocin, carried a new antibacterial activity against the indicator strain Pcc3. Here, we report that this new antibacterial activity is due to a new bacteriocin produced by strain Pcc21 and named carocin D. Carocin D is encoded by the caroDK gene located in the genomic DNA together with the caroDI gene, which seems to encode an immunity protein. N-terminal amino acid sequences of purified carocin D were determined by Edman degradation. In comparison with the primary translation product of caroDK, it was found that 8 amino acids are missing at the N terminus. This finding proved that carocin D is synthesized as a precursor peptide and that 8 amino acids are removed from its N terminus during maturation. Carocin D has two putative translocation domains; the N-terminal and C-terminal domains are homologous to those of Escherichia coli colicin E3 and Pseudomonas aeruginosa S-type pyocin, respectively. When caroDK and caroDI genes were transformed into carocin D-sensitive bacteria such as Pcc3, the bacteria became resistant to this bacteriocin. Carocin D has one putative DNase domain at the extreme C terminus and showed DNase activity in vitro. This bacteriocin had slight tolerance to heat but not to proteases. The caroDK gene was present in only 5 of 54 strains of P. carotovorum subsp. carotovorum. These results indicate that carocin D is a third bacteriocin found in P. carotovorum subsp. carotovorum, and this bacteriocin can be readily expressed in carocin D-sensitive nonpathogenic bacteria, which may have high potential as a biological control agent in the field.

  18. Characterization of a New Bacteriocin, Carocin D, from Pectobacterium carotovorum subsp. carotovorum Pcc21▿ †

    Science.gov (United States)

    Roh, Eunjung; Park, Tae-Ho; Kim, Myung-il; Lee, Seungdon; Ryu, Sangryeol; Oh, Chang-Sik; Rhee, Sangkee; Kim, Doo-Ho; Park, Beom-Seok; Heu, Sunggi

    2010-01-01

    Two different bacteriocins, carotovoricin and carocin S1, had been found in Pectobacterium carotovorum subsp. carotovorum, which causes soft-rot disease in diverse plants. Previously, we reported that the particular strain Pcc21, producing only one high-molecular-weight bacteriocin, carried a new antibacterial activity against the indicator strain Pcc3. Here, we report that this new antibacterial activity is due to a new bacteriocin produced by strain Pcc21 and named carocin D. Carocin D is encoded by the caroDK gene located in the genomic DNA together with the caroDI gene, which seems to encode an immunity protein. N-terminal amino acid sequences of purified carocin D were determined by Edman degradation. In comparison with the primary translation product of caroDK, it was found that 8 amino acids are missing at the N terminus. This finding proved that carocin D is synthesized as a precursor peptide and that 8 amino acids are removed from its N terminus during maturation. Carocin D has two putative translocation domains; the N-terminal and C-terminal domains are homologous to those of Escherichia coli colicin E3 and Pseudomonas aeruginosa S-type pyocin, respectively. When caroDK and caroDI genes were transformed into carocin D-sensitive bacteria such as Pcc3, the bacteria became resistant to this bacteriocin. Carocin D has one putative DNase domain at the extreme C terminus and showed DNase activity in vitro. This bacteriocin had slight tolerance to heat but not to proteases. The caroDK gene was present in only 5 of 54 strains of P. carotovorum subsp. carotovorum. These results indicate that carocin D is a third bacteriocin found in P. carotovorum subsp. carotovorum, and this bacteriocin can be readily expressed in carocin D-sensitive nonpathogenic bacteria, which may have high potential as a biological control agent in the field. PMID:20870796

  19. Photosynthetic poly-β-hydroxybutyrate accumulation in unicellular cyanobacterium Synechocystis sp. PCC 6714.

    Science.gov (United States)

    Kamravamanesh, Donya; Pflügl, Stefan; Nischkauer, Winfried; Limbeck, Andreas; Lackner, Maximilian; Herwig, Christoph

    2017-12-01

    Poly-β-hydroxybutyrate (PHB) production from CO 2 has the potential to reduce the production cost of this biodegradable polyesters, and also to make the material more sustainable compared to utilization of sugar feedstocks. In this study the unicellular cyanobacterium, Synechocystis sp. PCC 6714 has been identified as an unexplored potential organism for production of PHB. Synechocystis sp. PCC 6714 was studied under various cultivation conditions and nutritional limitations. Combined effects of nitrogen and phosphorus deficiency led to highest PHB accumulation under photoautotrophic conditions. Multivariate experimental design and quantitative bioprocess development methodologies were used to identify the key cultivation parameters for PHB accumulation. Biomass growth and PHB accumulation were studied under controlled defined conditions in a lab-scale photobioreactor. Specific growth rates were fourfold higher in photobioreactor experiments when cultivation conditions were controlled. After 14 days of cultivation in nitrogen and phosphorus, limited media intracellular PHB levels reached up to 16.4% from CO 2 . The highest volumetric production rate of PHB was 59 ± 6 mg L -1  day -1 . Scanning electron microscopy of isolated PHB granules of Synechocystis sp. PCC 6714 cultivated under nitrogen and phosphorus limitations showed an average diameter of 0.7 µm. The results of this study might contribute towards a better understanding of photoautotrophic PHB production from cyanobacteria.

  20. Effects of overexpressing photosynthetic carbon flux control enzymes in the cyanobacterium Synechocystis PCC 6803.

    Science.gov (United States)

    Liang, Feiyan; Lindblad, Peter

    2016-11-01

    Synechocystis PCC 6803 is a model unicellular cyanobacterium used in e.g. photosynthesis and CO 2 assimilation research. In the present study we examined the effects of overexpressing Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO), sedoheptulose 1,7-biphosphatase (SBPase), fructose-bisphosphate aldolase (FBA) and transketolase (TK), confirmed carbon flux control enzymes of the Calvin-Bassham-Benson (CBB) cycle in higher plants, in Synechocystis PCC 6803. Overexpressing RuBisCO, SBPase and FBA resulted in increased in vivo oxygen evolution (maximal 115%), growth rate and biomass accumulation (maximal 52%) under 100μmolphotonsm -2 s -1 light condition. Cells overexpressing TK showed a chlorotic phenotype but increased biomass by approximately 42% under 100μmolphotonsm -2 s -1 light condition. Under 15μmolphotonsm -2 s -1 light condition, cells overexpressing TK showed enhanced in vivo oxygen evolution. This study demonstrates increased growth and biomass accumulation when overexpressing selected enzymes of the CBB cycle. RuBisCO, SBPase, FBA and TK are identified as four potential targets to improve growth and subsequently also yield of valuable products from Synechocystis PCC 6803. Copyright © 2016 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

  1. TonB-Dependent Utilization of Dihydroxamate Xenosiderophores in Synechocystis sp. PCC 6803.

    Science.gov (United States)

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

    2018-02-01

    In Gram-negative bacteria, transport of ferric siderophores through outer membrane is a complex process that requires specific outer membrane transporters and energy-transducing TonB-ExbB-ExbD system in the cytoplasmic membrane. The genome of the non-siderophore-producing cyanobacterium Synechocystis sp. PCC 6803 encodes all putative components of the siderophore-mediated iron uptake system. So far, there has been no experimental evidence for the existence of such a pathway in this organism. On the contrary, its reductive iron uptake pathway has been studied in detail. We demonstrate that 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. Inactivation of the tonB gene or the exbB1-exbD1 gene cluster resulted in an inability to utilize these siderophores. At the same time, the inactivation of the feoB gene encoding FeoB plasma membrane ferrous iron transporter, or one of the futB or futC genes encoding permease and ATPase subunit of FutABC ferric iron transporter, did not impair the ability of cells to utilize FeSK or SAV as the sole source of iron for growth. Our data suggest that cyanobacterium Synechocystis sp. PCC 6803 is capable of acquiring iron-siderophore complexes in a TonB-dependent manner without iron reduction in the periplasm.

  2. Protein engineering of α-ketoisovalerate decarboxylase for improved isobutanol production in Synechocystis PCC 6803.

    Science.gov (United States)

    Miao, Rui; Xie, Hao; M Ho, Felix; Lindblad, Peter

    2018-03-01

    Protein engineering is a powerful tool to modify e.g. protein stability, activity and substrate selectivity. Heterologous expression of the enzyme α-ketoisovalerate decarboxylase (Kivd) in the unicellular cyanobacterium Synechocystis PCC 6803 results in cells producing isobutanol and 3-methyl-1-butanol, with Kivd identified as a potential bottleneck. In the present study, we used protein engineering of Kivd to improve isobutanol production in Synechocystis PCC 6803. Isobutanol is a flammable compound that can be used as a biofuel due to its high energy density and suitable physical and chemical properties. Single replacement, either Val461 to isoleucine or Ser286 to threonine, increased the Kivd activity significantly, both in vivo and in vitro resulting in increased overall production while isobutanol production was increased more than 3-methyl-1-butanol production. Moreover, among all the engineered strains examined, the strain with the combined modification V461I/S286T showed the highest (2.4 times) improvement of isobutanol-to-3M1B molar ratio, which was due to a decrease of the activity towards 3M1B production. Protein engineering of Kivd resulted in both enhanced total catalytic activity and preferential shift towards isobutanol production in Synechocystis PCC 6803. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

  3. Metabolic engineering of Synechocystis sp. PCC 6803 for enhanced ethanol production based on flux balance analysis.

    Science.gov (United States)

    Yoshikawa, Katsunori; Toya, Yoshihiro; Shimizu, Hiroshi

    2017-05-01

    Synechocystis sp. PCC 6803 is an attractive host for bio-ethanol production due to its ability to directly convert atmospheric carbon dioxide into ethanol using photosystems. To enhance ethanol production in Synechocystis sp. PCC 6803, metabolic engineering was performed based on in silico simulations, using the genome-scale metabolic model. Comprehensive reaction knockout simulations by flux balance analysis predicted that the knockout of NAD(P)H dehydrogenase enhanced ethanol production under photoautotrophic conditions, where ammonium is the nitrogen source. This deletion inhibits the re-oxidation of NAD(P)H, which is generated by ferredoxin-NADP + reductase and imposes re-oxidation in the ethanol synthesis pathway. The effect of deleting the ndhF1 gene, which encodes NADH dehydrogenase subunit 5, on ethanol production was experimentally evaluated using ethanol-producing strains of Synechocystis sp. PCC 6803. The ethanol titer of the ethanol-producing ∆ndhF1 strain increased by 145%, compared with that of the control strain.

  4. Rearranged Biosynthetic Gene Cluster and Synthesis of Hassallidin E in Planktothrix serta PCC 8927.

    Science.gov (United States)

    Pancrace, Claire; Jokela, Jouni; Sassoon, Nathalie; Ganneau, Christelle; Desnos-Ollivier, Marie; Wahlsten, Matti; Humisto, Anu; Calteau, Alexandra; Bay, Sylvie; Fewer, David P; Sivonen, Kaarina; Gugger, Muriel

    2017-07-21

    Cyanobacteria produce a wide range of natural products with antifungal bioactivity. The cyclic glycosylated lipopeptides of the hassallidin family have potent antifungal activity and display a great degree of chemical diversity. Here, we report the discovery of a hassallidin biosynthetic gene cluster from the filamentous cyanobacterium Planktothrix serta PCC 8927. The hassallidin gene cluster showed heavy rearrangement and marks of genomic plasticity. Nucleotide bias, differences in GC content, and phylogenetic incongruence suggested the acquisition of the hassallidin biosynthetic gene cluster in Planktothrix serta PCC 8927 by horizontal gene transfer. Chemical analyses by liquid chromatography and mass spectrometry demonstrated that this strain produced hassallidin E, a new glycosylated hassallidin variant. Hassallidin E was the only structural variant produced by Planktothrix serta PCC 8927 in all tested conditions. Further evaluated on human pathogenic fungi, hassallidin E showed an antifungal bioactivity. Hassallidin production levels correlated with nitrogen availability, in the only nitrogen-fixing Planktothrix described so far. Our results provide insights into the distribution and chemical diversity of cyanobacterial antifungal compounds as well as raise questions on their ecological relevance.

  5. Identification of alcohol stress tolerance genes ofSynechocystissp. PCC 6803 using adaptive laboratory evolution.

    Science.gov (United States)

    Matsusako, Takuya; Toya, Yoshihiro; Yoshikawa, Katsunori; Shimizu, Hiroshi

    2017-01-01

    Synechocystis sp. PCC 6803 is an attractive organism for the production of alcohols, such as isobutanol and ethanol. However, because stress against the produced alcohol is a major barrier for industrial applications, it is highly desirable to engineer organisms with strong alcohol tolerance. Isobutanol-tolerant strains of Synechocystis sp. PCC 6803 were obtained by long-term passage culture experiments using medium containing 2 g/L isobutanol. These evolved strains grew on medium containing 5 g/L isobutanol on which the parental strain could not grow. Mutation analysis of the evolved strains revealed that they acquired resistance ability due to combinatorial malfunctions of slr1044 ( mcpA ) and slr0369 ( envD ), or slr0322 ( hik43 ) and envD . The tolerant strains demonstrated stress resistance against isobutanol as well as a wide variety of alcohols such as ethanol, n -butanol, and isopentanol. As a result of introducing an ethanol-producing pathway into the evolved strain, its productivity successfully increased to 142% of the control strain. Novel mutations were identified that improved the stress tolerance ability of various alcohols in Synechocystis sp. PCC 6803.

  6. 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.

  7. Validation Data Acquisition in HTTF during PCC Events

    Energy Technology Data Exchange (ETDEWEB)

    Bardet, Philippe

    2018-02-07

    A validation experimental campaign was conducted in an Integral Effect Test (IET) facility of High Temperature Gas Reactors (HTGR), the High-Temperature Test Facility (HTTF) at Oregon State University (OSU). The HTTF simulates Depressurized and Pressurized Conduction Cooldowns (DCC and PCC). This campaign required the development of a new laser spectroscopic diagnostic to measure velocity in the challenging conditions of the HTTF: low speed (~1 m/s) gas flows at HTGR prototypical temperature and 1/10th pressure. This was a collaborative effort between co-PIs at The George Washington University (GW), Oregon State University (OSU), and NASA Langley Research Center. The main accomplishments of this project include the record for dynamic range for velocimetry, highest accuracy obtained with this technique, successful deployment in an IET leading to new validation matrix for CFD. These are detailed below and in manuscript appended to this executive summary. For this project, we introduced a new class of laser spectroscopic diagnostics to Thermal-Hydraulics to measure velocity of gases; furthermore, the diagnostic was demonstrated in-situ in an IET during DCC events. In such scenarios, particles used in mainstream techniques, like Particle Image Velocimetry (PIV) are not appropriate as they settle down too rapidly and also contaminate the experimental facility. Molecular tracers stay mixed within the working gas and can seed the flow in a technique called Molecular Tagging Velocimetry (MTV). In MTV a molecular tracer is photo-dissociated by a first (write) laser into radicals or molecules. The pattern created by the write laser is then interrogated with planar laser-induced fluorescence (PLIF), the read pulse(s), which are recorded with a camera. The pattern is probed and matched at two times (interval or probe time, dt), resulting in a time-of-flight velocimetry technique. This project demonstrated a new application range for MTV in gases. MTV has been extensively used

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  10. Ecological advantages from light adaptation and heterotrophic-like behavior in Synechococcus harvested from the Gulf of Trieste (Northern Adriatic Sea).

    Science.gov (United States)

    Paoli, Alessandro; Celussi, Mauro; Del Negro, Paola; Fonda Umani, Serena; Talarico, Laura

    2008-05-01

    A preliminary study was carried out on a picocyanobacterial mixed culture harvested from the Gulf of Trieste (Northern Adriatic) and identified as Synechococcus spp. both by transmission electron microscopy observations, biliprotein composition and molecular analyses. Absorption and fluorescence spectra revealed phycourobilin and phycoerythrobilin chromophores, suggesting the presence of both CU- and C-phycoerythrin, besides phycocyanobilin chromophores typical for phycocyanins and allophycocyanins. Both biliprotein analyses and molecular identification indicated the presence of at least two Synechococcus subgroups presumably differing either in phycoerythrin type or in physiological traits. Among the exoenzymatic activities acting on different substrates, only aminopeptidase showed high hydrolysis rates and the uptake of organic molecules was positive for leucine but not for thymidine. The protein carbon mobilized was high compared with the leucine incorporation rates, resulting in low percentages of newly mobilized carbon utilized by cultures. The organic carbon incorporated as leucine was compared with the photosynthetically produced one, and the balance between the phototrophic- and heterotrophic-like processes was c. 3 : 1. Our findings suggest that the Synechococcus heterotrophy plays an important role in cell's metabolism, and that the photoheterotrophic behavior, together with their chromatic adaptation capability, might represent the key for the absolute dominance of this genus in the Adriatic Sea.

  11. Rejoining kinetics of G1-PCC breaks induced by different heavy-ion beams with a similar LET value.

    Science.gov (United States)

    Tsuruoka, Chizuru; Furusawa, Yoshiya; Anzai, Kazunori; Okayasu, Ryuichi; Suzuki, Masao

    2010-08-14

    In previous studies we have shown that the linear energy transfer (LET)-relative biological effectiveness (RBE) curves were affected by LET and ion species [1,2]. In this paper we have examined the difference in the repair kinetics of G1-prematurely condensed chromosome breaks in normal human fibroblasts following irradiation with different heavy-ion beams of similar LET values. Normal human fibroblasts were irradiated with about 110 keV/microm of carbon (135 MeV/n), neon (400 MeV/n) and silicon ions (490 MeV/n), and the doses of carbon (3.25 Gy), neon (2.94+/-0.01 Gy) and silicon (2.31 Gy) were chosen to produce approximately the same number of initially measured G1-premature chromosome condensation (PCC) breaks (about 37 excess fragments per cell). The number of G1-PCC breaks was counted as excess fragments of prematurely condensed chromosomes using the PCC technique in the G1/G0 phase. The fractions of residual G1-PCC breaks after 24 h post-irradiation and half time, which is the time point where 50% of initially measured G1-PCC breaks are rejoined (t1/2), of the slow components of rejoining in carbon- and neon-ion irradiated cells were different from those of silicon-ion irradiated cells. However, no difference was observed in the half time of the fast components of rejoining in each ion beam. The results suggest that the difference in the fractions of residual G1-PCC breaks after 24 h post-irradiation reflect the result of the slow repair process for induced G1-PCC breaks, and that the repair process is dependent on the ion species, not the LET values. Copyright (c) 2010 Elsevier B.V. All rights reserved.

  12. DOE final report 100608.doc

    Energy Technology Data Exchange (ETDEWEB)

    Golden, Susan S

    2008-10-16

    The aim of this project was to inactivate each locus of the genome of the cyanobacterium Synechococcus elongatus PCC 7942 and screen resulting mutants for altered circadian phenotypes. The immediate goal was to identify all open reading frames (ORFs) that contribute to circadian timing. An additional result was to create a complete archived set of mutagenesis templates, of great utility for the wider research community, that will allow inactivation of any given locus in the genome of S. elongatus. Clones that carry segments of the S. elongatus genome were saturated with transposon insertions in vitro. We completed saturation mutagenesis of the chromosome (~2800 ORFs). The positions of insertions were sequenced for 17,767 mutagenized clones. Each individual insertion into the S. elongatus DNA in a cosmid or plasmid is a substrate for mutagenesis of the genome via homologous recombination. Because the complete insertion mutation clone set is 5-7 fold redundant, we produced a streamlined set of clones that contains one insertion mutation per locus in the genome, a unigene set. All clones are archived as Escherichia coli stocks frozen in glycerol in 96-well plates at -85ºC and as replicas of these plates on Whatman CloneSaver cards. Each of the mutagenesis substrates from the unigene set has been recombined into the chromosome of wild-type S. elongatus and these cyanobacterial mutants have been archived at -85ºC as well. S. elongatus insertion mutants defective for than 1400 independent genes have screened in luciferase reporter gene backgrounds to evaluate the effect of each mutation on circadian rhythms of gene expression. For the first 700 genes tested, mutagenesis of 71 different ORFs resulted in circadian phenotypes. The mutagenesis project also created insertion mutations in the endogenous large plasmid of S. elongatus, pANL. The sequence of pANL revealed two potential addiction cassettes that appear to account for selection for plasmid persistence. Genetic

  13. 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

  14. 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.

    Science.gov (United States)

    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.

  15. 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

    Directory of Open Access Journals (Sweden)

    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.

  16. In vitro kinetics of P700+reduction of Thermosynechococcus elongatus trimeric Photosystem I complexes by recombinant cytochrome c6using 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.

  17. Dihydroanatoxin-a Is Biosynthesized from Proline in Cylindrospermum stagnale PCC 7417: Isotopic Incorporation Experiments and Mass Spectrometry Analysis.

    Science.gov (United States)

    Méjean, Annick; Dalle, Klervi; Paci, Guillaume; Bouchonnet, Stéphane; Mann, Stéphane; Pichon, Valérie; Ploux, Olivier

    2016-07-22

    LC-MS and GC-MS analytical conditions have been developed to detect the cis- and trans-epimers (relative configuration of the carbon bearing the acetyl or propionyl group) of dihydroanatoxin-a and dihydrohomoanatoxin-a, in biological samples. These compounds epimerize under acidic conditions, yielding a major species that was tentatively assigned as the cis-epimer. Cylindrospermum stagnale PCC 7417 was definitively shown to produce dihydroanatoxin-a (1.2 mg/g dried cells). Oscillatoria sp. PCC 9107, Oscillatoria sp. PCC 6506, and C. stagnale PCC 7417, which produce anatoxin-a, homoanatoxin-a, and dihydroanatoxin-a, respectively, were cultivated in the presence of isotopically labeled proline, and the toxins were extracted. Interpretation of the GC-MS electron ionization mass spectra of these labeled anatoxins showed that they are all biosynthesized from proline and that the positions of the labels in these molecules are identical. These data and the fact that the ana cluster of genes is conserved in these cyanobacteria suggest that dihydroanatoxin-a is formed by the reduction of either anatoxin-a or its precursor in a specific step involving AnaK, an F420-dependent oxido-reductase whose gene is found in the ana gene cluster in C. stagnale PCC 7417. This is the first report of a cyanobacterium producing dihydroanatoxin-a, suggesting that other producers are present in the environment.

  18. 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.

  19. The baseline and longitudinal changes of PCC connectivity in mild cognitive impairment: a combined structure and resting-state fMRI study.

    Science.gov (United States)

    Wang, Zhiqun; Liang, Peipeng; Jia, Xiuqin; Jin, Guangwei; Song, Haiqing; Han, Ying; Lu, Jie; Li, Kuncheng

    2012-01-01

    The baseline and longitudinal changes of the posterior cingulate cortex (PCC) connectivity were assessed in order to clarify the neural mechanism of mild cognitive impairment (MCI). Twenty-eight right-handed subjects (14 MCI patients and 14 healthy elders) participated in this study. Clinical and neuropsychological examinations were performed on all the subjects. PCC functional connectivity was studied by examining the correlation between low frequency fMRI signal fluctuations in the PCC and those in all the other brain regions. Additionally, we traced all the MCI patients and compared their PCC connectivity in the initial stage and that in 3 years later. We also explored the relationship between the PCC functional connectivity strength and cognitive performances. Our results are as follows: Functional connectivity between the PCC and a set of regions is decreased in MCI patients. Most of these regions are within the default mode network (DMN). Three years later, the regions of superior frontal gyrus (SFG) and middle frontal gyrus (MFG) presented further decreased connectivity to the PCC in MCI. In addition, we also find enhanced functional connectivity between PCC and medial prefrontal cortex (MPFC), PCC and anterior cingulate cortex (ACC) in MCI patients. At last, our research also shows that the PCC connectivity with some regions significantly correlates with the cognitive performances of patients as measured by mini-mental state examination (MMSE), and California verbal learning test (CVLT) scores. The baseline and longitudinal changes of the PCC connectivity in our study suggest that impairment and compensation coexist in the disease progress of MCI patients.

  20. 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

  1. 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

  2. Estado e PCC em meio às tramas do poder arbitrário nas prisões The State and the "PCC" weaving the web of arbitrary power in prisons

    Directory of Open Access Journals (Sweden)

    Camila Caldeira Nunes Dias

    2011-11-01

    Full Text Available O objetivo do texto é discutir a normatização do cotidiano prisional, em que práticas punitivas ilegais conformam uma minuciosa penalidade extralegal que fundamenta as relações sociais nas prisões. Nas últimas décadas, em São Paulo, esses estabelecimentos assistem à expansão de uma organização de presos (o PCC que se constitui como instância reguladora de conflitos, cujo domínio está baseado num discurso de união dos presos diante de um inimigo comum, o Estado. Em resposta, este último utiliza mecanismos punitivos administrativos e extralegais que ferem princípios constitucionais e reforçam o sentimento de injustiça, base sobre a qual o poder do PCC se assenta. As práticas arbitrárias do Estado e do PCC são constitutivas de uma rede de poder que enreda a todos aqueles que são submetidos à pena de prisãoThe purpose of this text is to discuss the regulation of daily life in prison, where illegal punishments form a micro-level extralegal system of penalizations that founds social relations in prisons. In the last few decades, these establishments in São Paulo state have witnessed the expansion of an inmates organization (the 'PCC' which acts as an instance of conflict management and whose control is based on a discourse of prisoners uniting against a common enemy, the State. In response, the State uses administrative and extralegal punitive mechanisms, which contravene constitutional principles and reinforce the feeling of injustice that provides the base on which the PCC's power rests. The arbitrary practices of the State and the PCC constitute a power network that ensnares everyone sentenced to imprisonment

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

    Directory of Open Access Journals (Sweden)

    Tomáš Zavřel

    Full Text Available Synechocystis sp. PCC 6803 is a widely used model cyanobacterium, whose substrains can vary on both genotype and phenotype levels. Previously described phenotypic variations include ability of mixotrophic growth, ability of movement on agar plates and variations in pigments composition or cell size. In this study, we report for the first time significant variation among Synechocystis substrains in complex cellular traits such as growth rate, photosynthesis efficiency, cellular dry weight and cellular composition (including protein or carbohydrates content. We also confirmed previously reported differences in cell size. Synechocystis cultures were cultivated in controlled environment of flat panel photobioreactors under red, blue and white light of intensities up to 790 μmol(photons m-2 s-1, temperatures 23°C-60°C, input CO2 concentrations ranging from 400 to 15 000 ppm and in BG11 cultivation medium with and without addition of NaCl. Three Synechocystis substrains were used for the comparative experiments: GT-L, GT-B (Brno, CZ and PCC-B (Brno, CZ. Growth rates of Synechocystis GT-B were inhibited under high intensities of red light (585-670 nm, and growth rates of both substrains GT-B and PCC-B were inhibited under photons of wavelengths 485-585 nm and 670-700 nm. Synechocystis GT-B was more sensitive to low temperatures than the other two tested substrains, and Synechocystis GT-L was sensitive to the presence of NaCl in the cultivation media. The results suggest that stress sensitivity of commonly used Synechocystis substrains can strongly vary, similarly as glucose tolerance or motility as reported previously. Our study further supports the previous statement that emphasizes importance of proper Synechocystis substrains selection and awareness of phenotypical differences among Synechocystis substrains which is crucial for comparative and reproducible research. This is highly relevant for studies related to stress physiology and development

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

    Science.gov (United States)

    Zavřel, Tomáš; Očenášová, Petra; Červený, Jan

    2017-01-01

    Synechocystis sp. PCC 6803 is a widely used model cyanobacterium, whose substrains can vary on both genotype and phenotype levels. Previously described phenotypic variations include ability of mixotrophic growth, ability of movement on agar plates and variations in pigments composition or cell size. In this study, we report for the first time significant variation among Synechocystis substrains in complex cellular traits such as growth rate, photosynthesis efficiency, cellular dry weight and cellular composition (including protein or carbohydrates content). We also confirmed previously reported differences in cell size. Synechocystis cultures were cultivated in controlled environment of flat panel photobioreactors under red, blue and white light of intensities up to 790 μmol(photons) m-2 s-1, temperatures 23°C-60°C, input CO2 concentrations ranging from 400 to 15 000 ppm and in BG11 cultivation medium with and without addition of NaCl. Three Synechocystis substrains were used for the comparative experiments: GT-L, GT-B (Brno, CZ) and PCC-B (Brno, CZ). Growth rates of Synechocystis GT-B were inhibited under high intensities of red light (585-670 nm), and growth rates of both substrains GT-B and PCC-B were inhibited under photons of wavelengths 485-585 nm and 670-700 nm. Synechocystis GT-B was more sensitive to low temperatures than the other two tested substrains, and Synechocystis GT-L was sensitive to the presence of NaCl in the cultivation media. The results suggest that stress sensitivity of commonly used Synechocystis substrains can strongly vary, similarly as glucose tolerance or motility as reported previously. Our study further supports the previous statement that emphasizes importance of proper Synechocystis substrains selection and awareness of phenotypical differences among Synechocystis substrains which is crucial for comparative and reproducible research. This is highly relevant for studies related to stress physiology and development of sustainable

  5. Growth response of Spirulina platensis PCC9108 to elevated CO2 levels and flue gas

    Directory of Open Access Journals (Sweden)

    Seyedmahdi Hoseini

    2014-01-01

    Full Text Available Introduction: Because their ability to capture CO2, photosynthetical microorganisms have some advantages to CO2 mitigation from high CO2 streams such as flue gases and they can use CO2 as carbon source. Recently, experts have made efforts to exploit microorganisms intended for recovering CO2 from power plants. Materials and methods: To achieve this purpose, we studied the growth response of the cyanobacterium Spirulina platensis PCC9108 under different concentrations of carbon dioxide (ranging from 0.036% to 10% and flue gas in a bench-scale system. Preparation of different concentrations of CO2 and injection into Erlenmeyer flasks was performed by a system including air compressor, CO2 capsule, pressure gauge and flow meter. Results: The main goal of studying this paper is a survey of organism's potential to grow by generated CO2 from flue gas of power plant. It already had the potential and highest biomass production recorded at 8% CO2 (v/v. Also we proved that S.platensis PCC9108 can be grown under flue gas, although biomass production decreased fairly. Total lipid content of algae interestingly enhanced with elevated CO2 levels from ambient air to 4% and 6% which ranged from 14.5 to 15.8 and 16 dry weight (wt. % respectively. In contrast, total protein content illustrated no difference between all treatment and its value was about 46 wt.%. Discussion and conclusion: The results of present study suggested that understudied S.platensis PCC9108 is appropriate for mitigating CO2 because of its carbon fixation ability. Also due to its high protein content, this cyanobacterium is a good candidate to produce SCP (single cell protein.

  6. 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

  7. Surface modification of PCC with guar gum using organic titanium ionic crosslinking agent and its application as papermaking filler.

    Science.gov (United States)

    Xie, Wei; Song, Zhanqian; Liu, Zhenhua; Qian, Xueren

    2016-10-05

    Utilized the principles of guar gum (GG) gelation and crosslinking, a novel modified precipitated calcium carbonate (MPCC) papermaking filler was prepared by using organic titanium (OT) ionic crosslinking agent. The MPCC was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). FTIR results confirmed that GG had been coated on the surface of PCC particles, XPS analysis indicated the presence of titanium atoms on MPCC particles, and SEM and XRD results showed that the modification treatment did change the surface morphology and crystal structure of PCC particles. The handsheet testing results showed that the strength properties of handsheets were obviously improved when using MPCC as papermaking filler, and the optimum preparation conditions of MPCC were obtained. This research suggests that the GG modified PCC by using OT as crosslinking agent can be used to manufacture high filler content paper products. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Analysis of proteins involved in the production of MAA׳s in two Cyanobacteria Synechocystis PCC 6803 and Anabaena cylindrica.

    Science.gov (United States)

    Rahman, Md Akhlaqur; Sinha, Sukrat; Sachan, Shephali; Kumar, Gaurav; Singh, Shailendra Kumar; Sundaram, Shanthy

    2014-01-01

    Mycosporine- like amino acids (MAAs) are small (MAAs is presumed to occur via the first part of shikimate pathway. In the present work two cyanobacteria Synechocystis PCC 6803 and Anabaena cylindrica were tested for their ability to synthesize MAAs and protein involved in the production of MAAs. It was found that protein sequence 3-phosphoshikimate 1-carboxyvinyltransferase is involved in producing mycosporine glycine in Synechocystis PCC 6803 and 3-dehydroquinate synthase is involved for producing shinorine in Anabaena cylindrica. Phylogenetic and bioinformatic analysis of Mycosporine like amino acid producing protein sequence of both cyanobacterial species Synechocystis PCC 6803 and Anabaena cylindrica provide a useful framework to understand the relationship of the different forms and how they have evolved from a common ancestor. These products seem to be conserved but the residues are prone to variation which might be due the fact that different cyanobacteria show different physiological process in response of Ultraviolet stress.

  9. El PCC com a document de canvi i d'innovació als centres educatius de primària

    OpenAIRE

    Martínez Mínguez, Maria Lourdes

    2009-01-01

    Consultable des del TDX Títol obtingut de la portada digitalitzada Aquesta tesi pretén: establir quina és la situació real dels Projectes Curriculars de Centre (PCC) a les escoles d'Educació Infantil i Primària de Catalunya; comprovar si el PCC ha estat un instrument de canvi i d'innovació; i configurar propostes per facilitar i redreçar l'elaboració, aplicació i avaluació dels PCC. Per aconseguir aquests propòsits s'ha partit d'una recerca bibliogràfica i documental que ha permès dispo...

  10. The structure of PccH from Geobacter sulfurreducens - a novel low reduction potential monoheme cytochrome essential for accepting electrons from an electrode.

    Science.gov (United States)

    Dantas, Joana M; Campelo, Luísa M; Duke, Norma E C; Salgueiro, Carlos A; Pokkuluri, P Raj

    2015-06-01

    The structure of cytochrome c (GSU3274) designated as PccH from Geobacter sulfurreducens was determined at a resolution of 2.0 Å. PccH is a small (15 kDa) cytochrome containing one c-type heme, found to be essential for the growth of G. sulfurreducens with respect to accepting electrons from graphite electrodes poised at -300 mV versus standard hydrogen electrode. with fumarate as the terminal electron acceptor. The structure of PccH is unique among the monoheme cytochromes described to date. The structural fold of PccH can be described as forming two lobes with the heme sandwiched in a cleft between the two lobes. In addition, PccH has a low reduction potential of -24 mV at pH 7, which is unusual for monoheme cytochromes. Based on difference in structure, together with sequence phylogenetic analysis, we propose that PccH can be regarded as a first characterized example of a new subclass of class I monoheme cytochromes. The low reduction potential of PccH may enable the protein to be redox active at the typically negative potential ranges encountered by G. sulfurreducens. Because PccH is predicted to be located in the periplasm of this bacterium, it could not be involved in the first step of accepting electrons from the electrode but is very likely involved in the downstream electron transport events in the periplasm. © 2015 FEBS.

  11. 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.

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

    Directory of Open Access Journals (Sweden)

    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

  13. Analysis of α-particle-induced chromosomal aberrations by chemically-induced PCC. Elaboration of dose-effect curves.

    Science.gov (United States)

    Puig, Roser; Pujol, Mònica; Barrios, Leonardo; Caballín, María Rosa; Barquinero, Joan-Francesc

    2016-09-01

    In a similar way to high-dose exposures to low-LET radiations, cells show difficulties reaching mitosis after high-LET radiation exposure. For this reason, techniques have been proposed that are able to analyze chromosome aberrations in interphase by prematurely condensing the chromosomes (PCC-techniques). Few dose-effect curves for high-LET radiation types have been reported, and none for α-particles. The aim of this study was to evaluate, by chemically-induced PCC, the chromosome aberrations induced by several doses of α-particles. Monolayers of peripheral lymphocytes were exposed to an α-source of Americium-241 with a mean energy entering the cells of 2.7 MeV. Lymphocytes were exposed to 10 doses, from 0-2.5 Gy, and then cultured for 48 h. Colcemid and Calyculin-A were added at 24 and 1 h before harvesting, respectively. During microscope analysis, chromosome rings and extra chromosome pieces were scored in G2/M-PCC and M cells, while dicentric chromosomes were only scored in M cells. As the dose increased, fewer cells were able to reach mitosis and the proportion of G2/M-PCC cells increased. Chromosome rings were hardly observed in M cells when compared to G2/M-PCC cells. Extra fragments were more frequent than rings in both G2/M-PCC and M cells, but with lower frequencies than in G2/M-PCC cells. The distribution of dicentrics and extra fragments showed a clear overdispersion; this was not so evident for rings. The dose-effect curves obtained fitted very well to a linear model. Damaged cells after α-particle irradiation show more difficulties in reaching mitosis than cells exposed to γ-rays. After α-particle irradiation the frequency of all the chromosome aberrations considered increased linearly with the dose, and α-particles clearly produced more dicentrics and extra chromosome pieces with respect to γ-rays. After α-particle exposure, the existence of extra chromosome fragments in PCC cells seems to be a good candidate for use as a biomarker

  14. ATP-binding cassette transporters of the multicellular cyanobacterium Anabaena sp. PCC 7120: a wide variety for a complex lifestyle.

    Science.gov (United States)

    Shvarev, Dmitry; Maldener, Iris

    2018-02-01

    Two hundred genes or 3% of the known or putative protein-coding genes of the filamentous freshwater cyanobacterium Anabaena sp. PCC 7120 encode domains of ATP-binding cassette (ABC) transporters. Detailed characterization of some of these transporters (14-15 importers and 5 exporters) has revealed their crucial roles in the complex lifestyle of this multicellular photoautotroph, which is able to differentiate specialized cells for nitrogen fixation. This review summarizes the characteristics of the ABC transporters of Anabaena sp. PCC 7120 known to date. © FEMS 2018. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  15. Biosynthesis of cylindrospermopsin and 7-epicylindrospermopsin in Oscillatoria sp. strain PCC 6506: identification of the cyr gene cluster and toxin analysis.

    Science.gov (United States)

    Mazmouz, Rabia; Chapuis-Hugon, Florence; Mann, Stéphane; Pichon, Valérie; Méjean, Annick; Ploux, Olivier

    2010-08-01

    Cylindrospermopsin is a cytotoxin produced by Cylindrospermopsis raciborskii and other cyanobacteria that has been implicated in human intoxications. We report here the complete sequence of the gene cluster responsible for the biosynthesis of this toxin in Oscillatoria sp. strain PCC 6506. This cluster of genes was found to be homologous with that of C. raciborskii but with a different gene organization. Using an enzyme-linked immunosorbent assay and an optimized liquid chromatography analytical method coupled to tandem mass spectrometry, we detected 7-epicylindrospermopsin, cylindrospermopsin, and 7-deoxycylindrospermopsin in the culture medium of axenic Oscillatoria PCC 6506 at the following relative concentrations: 68.6%, 30.2%, and 1.2%, respectively. We measured the intracellular and extracellular concentrations, per mg of dried cells of Oscillatoria PCC 6506, of 7-epicylindrospermopsin (0.18 microg/mg and 0.29 microg/mg, respectively) and cylindrospermopsin (0.10 microg/mg and 0.11 microg/mg, respectively). We showed that these two toxins accumulated in the culture medium of Oscillatoria PCC 6506 but that the ratio (2.5 +/- 0.3) was constant with 7-epicylindrospermopsin being the major metabolite. We also determined the concentrations of these toxins in culture media of other Oscillatoria strains, PCC 6407, PCC 6602, PCC 7926, and PCC 10702, and found that, except for PCC 6602, they all produced 7-epicylindrospermopsin and cylindrospermopsin, with the former being the major toxin, except for PCC 7926, which produced very little 7-epicylindrospermopsin. All the cylindrospermopsin producers studied gave a PCR product using specific primers for the amplification of the cyrJ gene from genomic DNA.

  16. Scaffold-fused riboregulators for enhanced gene activation in Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Sakai, Yuta; Abe, Koichi; Nakashima, Saki; Ellinger, James J; Ferri, Stefano; Sode, Koji; Ikebukuro, Kazunori

    2015-08-01

    Cyanobacteria are an attractive host for biofuel production because they can produce valuable chemical compounds from CO2 fixed by photosynthesis. However, the available genetic tools that enable precise gene regulation for the applications of synthetic biology are insufficient. Previously, we engineered an RNA-based posttranscriptional regulator, termed riboregulator, for the control of target gene expression in cyanobacterium Synechocystis sp. PCC 6803. Moreover, we enhanced the gene regulation ability of the riboregulators in Escherichia coli by fusing and engineering a scaffold sequence derived from naturally occurring E. coli noncoding small RNAs. Here, we demonstrated that the scaffold sequence fused to the riboregulators improved their gene regulation ability in Synechocystis sp. PCC 6803. To further improve gene regulation, we expressed an exogenous RNA chaperone protein that is responsible for noncoding small RNA-mediated gene regulation, which resulted in higher target gene expression. The scaffold sequence derived from natural E. coli noncoding small RNAs is effective for designing RNA-based genetic tools and scaffold-fused riboregulators are a strong RNA-tool to regulate gene expression in cyanobacteria. © 2015 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

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

    Science.gov (United States)

    Oliveira, Paulo; Martins, Nuno M.; Santos, Marina; Couto, Narciso A. S.; Wright, Phillip C.; Tamagnini, Paula

    2015-01-01

    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. PMID:25782455

  18. 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.

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

    Directory of Open Access Journals (Sweden)

    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.

  20. 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.

  1. OmpF of Pectobacterium carotovorum subsp. carotovorum Pcc3 is required for carocin D sensitivity.

    Science.gov (United States)

    Lim, Jeong-A; Hong, Jisoo; Kim, Jonguk; Heu, Sunggi; Roh, Eunjung

    2016-12-01

    Carocin D is a bacteriocin produced by Pectobacterium carotovorum subsp. carotovorum Pcc21. Carocin D inhibits the growth of P carotovorum subsp. carotovorum and closely related strains. Pectobacterium carotovorum subsp. carotovorum is a causative bacterium for soft rot disease and leads to severe economic losses. Bacteriocins recognize and interact with a specific membrane protein of target bacteria as a receptor. To identify the receptor responsible for carocin D recognition, mutants that underwent a phenotypic change from carocin D sensitivity to carocin D insensitivity were screened. Based on Tn5 insertions, carocin D sensitivity was dependent on expression of the outer membrane protein OmpF. The insensitivity of the mutant (Pcc3MR) to carocin D was complemented with ompF from carocin D-sensitive strains, not from carocin D-resistant strains. The selectivity between sensitive and resistant strains could be attributed to variation in OmpFs in the cell-surface-exposed regions. Based on sequence analysis and complementation assays, it appears that carocin D uses OmpF as a receptor and is translocated by the TonB system. According to previously reported translocation mechanisms of colicins, OmpF works along with the TolA system rather than the TonB system. Therefore, the current findings suggest that carocin D is imported by a unique colicin-like bacteriocin translocation system. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  2. 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

  3. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Susan S. Golden

    2005-03-31

    The originally funded project was geared to pursue research on regulation of photosystem II (PSII) in the cyanobacterium Synechococcus elongatus PCC 7942. We characterized a locus, psfR, (psbA stimulating factor) that affects expression of the psbAI gene, which encodes the PSII protein D1. Over-expression of psfR, which encodes a protein with receiver and pseudo-receiver domains, acts at the promoter region to elevate expression of psbAI and a subset of other loci. We reoriented the remainder of the funding to make a greater impact through completion of a functional genomics project that had been initiated with funding from another agency. The goal is inactivation of each gene individually in the S. elongatus genome, and completion of the entire genome sequence. At the end of the project we will have screened all loci for involvement in circadian rhythms of gene expression and assembled an archived set of clones that can be used to create the mutations to screen for any other phenotype. During the project period we: (1) prepared a functional genomics website for S. elongatus PCC 7942 that posts sequences prior to GenBank release, and presents the strategy and progress for the genomics project (http://www.bio.tamu.edu/synecho/); (2) determined the sequence of and annotated the S. elongatus 46 kb plasmid, pANL; (3) submitted assembled sequences with annotation of 8 cosmid inserts to GenBank (313 kb), with sites of transposon insertions indicated; (4) mutagenized approximately an additional 600 kb of the genome (16 cosmids) and identified sequences flanking the mutations; (5) recombined mutagenesis substrates into the S. elongatus genome to produce gene inactivations (at the sites of transposon insertions) for approximately 415 kb of mutagenized sequence (85% of these have already been screened for circadian phenotypes) (6) identified the clpPIIclpX locus as important in determining circadian period; and (7) demonstrated effectiveness of antisense RNA for decreasing

  4. Forensic Investigation of AC and PCC Pavements with Extended Service Life : Volume 3 : Petrographic Examination of Blast Furnace Slag Aggregate Concrete Cores taken from PCC Pavements in Cuyahoga County , Ohio : Executive Summary Report

    Science.gov (United States)

    2010-09-01

    Air-cooled blast furnace slag has been used as a coarse : aggregate in portland cement-based pavement concretes : since at least the early 1900s. Many of these concretes : have performed satisfactorily. In recent times a number : of PCC slag aggre...

  5. MP3DG-PCC, open source software framework for implementation and evaluation of point cloud compression

    NARCIS (Netherlands)

    R.N. Mekuria (Rufael); P.S. Cesar Garcia (Pablo Santiago)

    2016-01-01

    textabstractWe present MP3DG-PCC, an open source framework for design, implementation and evaluation of point cloud compression algorithms. The framework includes objective quality metrics, lossy and lossless anchor codecs, and a test bench for consistent comparative evaluation. The framework and

  6. 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)

  7. A comparison of fermentation in the cyanobacterium Microcystis PCC7806 grown under a light/dark cycle and continuous light

    NARCIS (Netherlands)

    Moezelaar, R.; Stal, L.J.

    1997-01-01

    The cyanobacterium Microcystis PCC7806, grown under continuous light, fermented endogenously stored glycogen to equimolar amounts of acetate and ethanol when incubated anaerobically in the dark. In addition, H-2, CO2 and some L-lactate were produced. This fermentation pattern differed from that

  8. Role of the PsbI protein in Photosystem II assembly and repair in the cyanobacterium Synechocystis sp. PCC 6803

    Czech Academy of Sciences Publication Activity Database

    Dobáková, Marika; Tichý, Martin; Komenda, Josef

    2007-01-01

    Roč. 145, - (2007), s. 1681-1691 ISSN 0032-0889 R&D Projects: GA ČR GA206/06/0322 Institutional research plan: CEZ:AV0Z50200510 Keywords : photosystem II * cyanobacterium * synechocystis sp. pcc 6803 Subject RIV: EE - Microbiology, Virology Impact factor: 6.367, year: 2007

  9. Identification of Substrain-Specific Mutations by Massively Parallel Whole-Genome Resequencing of Synechocystis sp. PCC 6803

    Science.gov (United States)

    Kanesaki, Yu; Shiwa, Yuh; Tajima, Naoyuki; Suzuki, Marie; Watanabe, Satoru; Sato, Naoki; Ikeuchi, Masahiko; Yoshikawa, Hirofumi

    2012-01-01

    The cyanobacterium, Synechocystis sp. PCC 6803, was the first photosynthetic organism whose genome sequence was determined in 1996 (Kazusa strain). It thus plays an important role in basic research on the mechanism, evolution, and molecular genetics of the photosynthetic machinery. There are many substrains or laboratory strains derived from the original Berkeley strain including glucose-tolerant (GT) strains. To establish reliable genomic sequence data of this cyanobacterium, we performed resequencing of the genomes of three substrains (GT-I, PCC-P, and PCC-N) and compared the data obtained with those of the original Kazusa strain stored in the public database. We found that each substrain has sequence differences some of which are likely to reflect specific mutations that may contribute to its altered phenotype. Our resequence data of the PCC substrains along with the proposed corrections/refinements of the sequence data for the Kazusa strain and its derivatives are expected to contribute to investigations of the evolutionary events in the photosynthetic and related systems that have occurred in Synechocystis as well as in other cyanobacteria. PMID:22193367

  10. Carbon sink removal: Increased photosynthetic production of lactic acid by Synechocystis sp. PCC6803 in a glycogen storage mutant

    NARCIS (Netherlands)

    van der Woude, A.D.; Angermayr, S.A.; Puthan Veetil, V.; Osnato, A.; Hellingwerf, K.J.

    2014-01-01

    Deletion of pathways for carbon-storage in the cyanobacterium Synechocystis sp. PCC6803 has been suggested as a strategy to increase the size of the available pyruvate pool for the production of (heterologous) chemical commodities. Here we show that deletion of the pathway for glycogen synthesis

  11. Efek ukuran, bentuk dan konsentrasi partikel precipitated calcium carbonate (PCC yang ditambahkan pada sifat mekanik komposit karet alam

    Directory of Open Access Journals (Sweden)

    Ihda Novia Indrajati

    2013-06-01

    Full Text Available The objectives of this research was to study the effect of particle size, shape and concentration of PCC on mechanical properties of natural rubber composites, i.e. tensile strength (Ts and elongation at break (Eb at original and aging conditions. Two kinds of PCC were used, PCCL (local, size 12 μm, uncoated and PCCD (commercial, size 0.03-0.06 μm, stearate coated. PCCL was pre-treated by applying stearic acid. PCCLA was characterized with FTIR, TG/DTA thermal analysis, and morphological test using SEM. The loading of PCC were 2.5; 5.0; 7.5; 10.0 and 12.5 phr respectively. Natural rubber composites were compounded using laboratory scale two roll mill. The incorporation of PCCLA or PCCD into rubber matrix increased Ts and Eb. Both Ts and Eb initially increased continued up to the maximum point then decreased. The maximum point of Ts and Eb of PCCLA were given on 10 phr, while of PCCD were on 10 phr and 5 phr resepectively. PCCLA with its cubical particle shape gave higher Ts and Eb than those PCCD with its needle-like shape, eventhough the particle size was larger. Aging increased tensile and elongation, because of excessive crosslinking. The characeristic of the interfacial adhesion between rubber matrix and PCC particle was estimated by Ts value, and proved that the Ts of PCCLA higher than those of PCCD.

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

    Directory of Open Access Journals (Sweden)

    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

  13. Molecular cloning of Pcc-dmrt1s and their specific expression patterns in Pengze crucian carp (Carassius auratus var. Pengze) affected by 17α-methyltestosterone.

    Science.gov (United States)

    Zheng, Yao; Liang, Hongwei; Xu, Peng; Li, Meng; Wang, Zaizhao

    2014-08-01

    Dmrt1, an important transcription factor associated with testicular differentiation, is conserved among teleost, which could also be detected in ovaries. In the present study, three isoforms of Pcc-dmrt1s (Pcc-dmrt1a, Pcc-dmrt1b and Pcc-dmrt1c) resulting from alternative splicing of the dmrt1 gene were cloned and characterized in the triploid gynogenetic fish, the Pengze crucian carp. Their mRNA expression profiling was investigated in juvenile developmental stages, tissues of the adult fish, and the juveniles under 84.2 ng/L 17α-methyltestosterone (MT) treatments. Results showed that their putative proteins shared high identities to Dmrt1 in cyprinid fish species. Gene expression profiling in the developmental stages showed that all the three target genes had a highest/lowest expression at 56/40 days post-hatching (dph), respectively. The period of 40 dph appeared to be a key time during the process of the ovary development of Pengze crucian carp. The tissue distribution results indicated that Pcc-dmrt1s were predominantly expressed in hepatopancreas, brain, spleen and ovary of the female fish. MT significantly increased the mRNA expression of Pcc-dmrt1a (all 4-week exposures) and Pcc-dmrt1b (except for week 2), while repressed Pcc-dmrt1c transcripts at all exposure period except for week 2. MT extremely significant repressed cyp19a1a transcripts for 1 week. The present study indicated that MT could influence the ovary development of Pengze crucian carp by disturbing gene expressions of Pcc-dmrt1s and cyp19a1a. Furthermore, the present study will be of great significance to broaden the understanding of masculinizing pathway during ovary development in gynogenetic teleost.

  14. Glycogen synthase isoforms in Synechocystis sp. PCC6803: identification of different roles to produce glycogen by targeted mutagenesis.

    Directory of Open Access Journals (Sweden)

    Sang-Ho Yoo

    Full Text Available Synechocystis sp. PCC6803 belongs to cyanobacteria which carry out photosynthesis and has recently become of interest due to the evolutionary link between bacteria and plant species. Similar to other bacteria, the primary carbohydrate storage source of Synechocystis sp. PCC6803 is glycogen. While most bacteria are not known to have any isoforms of glycogen synthase, analysis of the genomic DNA sequence of Synechocystis sp. PCC6803 predicts that this strain encodes two isoforms of glycogen synthase (GS for synthesizing glycogen structure. To examine the functions of the putative GS genes, each gene (sll1393 or sll0945 was disrupted by double cross-over homologous recombination. Zymogram analysis of the two GS disruption mutants allowed the identification of a protein band corresponding to each GS isoform. Results showed that two GS isoforms (GSI and GSII are present in Synechocystis sp. PCC6803, and both are involved in glycogen biosynthesis with different elongation properties: GSI is processive and GSII is distributive. Total GS activities in the mutant strains were not affected and were compensated by the remaining isoform. Analysis of the branch-structure of glycogen revealed that the sll1393- mutant (GSI- produced glycogen containing more intermediate-length chains (DP 8-18 at the expense of shorter and longer chains compared with the wild-type strain. The sll0945- mutant (GSII- produced glycogen similar to the wild-type, with only a slightly higher proportion of short chains (DP 4-11. The current study suggests that GS isoforms in Synechocystis sp. PCC6803 have different elongation specificities in the biosynthesis of glycogen, combined with ADP-glucose pyrophosphorylase and glycogen branching enzyme.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  19. 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

  20. Serotonin Transporter Genotype Modulates Functional Connectivity between Amygdala and PCC/PCu during Mood Recovery

    Directory of Open Access Journals (Sweden)

    Zhuo eFang

    2013-10-01

    Full Text Available The short (S allele of the serotonin transporter-linked polymorphic region (5-HTTLPR has been associated with increased susceptibility to depression. Previous neuroimaging studies have consistently showed increased amygdala activity during the presentation of negative stimuli or regulation of negative emotion in the homozygous short allele carriers, suggesting the key role of amygdala response in mediating increased risk for depression. The default brain network (DMN has also been shown to modulate amygdala activity. However, it remains unclear whether 5-HTTLPR genetic variation modulates functional connectivity between the amygdala and regions of DMN. In this study, we re-analyzed our previous imaging dataset and examined the effects of 5-HTTLPR genetic variation on amygdala connectivity. A total of 15 homozygous short (S/S and 15 homozygous long individuals (L/L were scanned in functional MRI during four blocks: baseline, sad mood, mood recovery, and return to baseline. The S/S and L/L groups showed a similar pattern of functional connectivity and no differences were found between the two groups during baseline and sad mood scans. However, during mood recovery, the S/S group showed significantly reduced anti-correlations between amygdala and posterior cingulate cortex/precuneus (PCC/PCu compared to the L/L group. Moreover, PCC/PCu-amygdala connectivity correlated with amygdala activity in the S/S group but not the L/L group. These results suggest that 5-HTTLPR genetic variation modulates amygdala connectivity which subsequently affects its activity during mood regulation, providing an additional mechanism by which the S allele confers depression risk.

  1. Serotonin transporter genotype modulates functional connectivity between amygdala and PCC/PCu during mood recovery.

    Science.gov (United States)

    Fang, Zhuo; Zhu, Senhua; Gillihan, Seth J; Korczykowski, Marc; Detre, John A; Rao, Hengyi

    2013-01-01

    The short (S) allele of the serotonin transporter-linked polymorphic region (5-HTTLPR) has been associated with increased susceptibility to depression. Previous neuroimaging studies have consistently showed increased amygdala activity during the presentation of negative stimuli or regulation of negative emotion in the homozygous short allele carriers, suggesting the key role of amygdala response in mediating increased risk for depression. The brain default mode network (DMN) has also been shown to modulate amygdala activity. However, it remains unclear whether 5-HTTLPR genetic variation modulates functional connectivity (FC) between the amygdala and regions of DMN. In this study, we re-analyzed our previous imaging dataset and examined the effects of 5-HTTLPR genetic variation on amygdala connectivity. A total of 15 homozygous short (S/S) and 15 homozygous long individuals (L/L) were scanned in functional magnetic resonance imaging (fMRI) during four blocks: baseline, sad mood, mood recovery, and return to baseline. The S/S and L/L groups showed a similar pattern of FC and no differences were found between the two groups during baseline and sad mood scans. However, during mood recovery, the S/S group showed significantly reduced anti-correlation between amygdala and posterior cingulate cortex/precuneus (PCC/PCu) compared to the L/L group. Moreover, PCC/PCu-amygdala connectivity correlated with amygdala activity in the S/S group but not the L/L group. These results suggest that 5-HTTLPR genetic variation modulates amygdala connectivity which subsequently affects its activity during mood regulation, providing an additional mechanism by which the S allele confers depression risk.

  2. 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.

  3. The effect of enhanced acetate influx on Synechocystis sp. PCC 6803 metabolism.

    Science.gov (United States)

    Thiel, Kati; Vuorio, Eerika; Aro, Eva-Mari; Kallio, Pauli Tapio

    2017-02-02

    Acetate is a common microbial fermentative end-product, which can potentially be used as a supplementary carbon source to enhance the output of biotechnological production systems. This study focuses on the acetate metabolism of the photosynthetic cyanobacterium Synechocystis sp. PCC 6803 which is unable to grow on acetate as a sole carbon source but still can assimilate it via acetyl-CoA-derived metabolic intermediates. In order to gain insight into the acetate uptake, associated limitations and metabolic effects, a heterologous acetate transporter ActP from Escherichia coli was introduced into Synechocystis to facilitate the transport of supplemented acetate from the medium into the cell. The results show that enhanced acetate intake can efficiently promote the growth of the cyanobacterial host. The effect is apparent specifically under low-light conditions when the photosynthetic activity is low, and expected to result from increased availability of acetyl-CoA precursors, accompanied by changes induced in cellular glycogen metabolism which may include allocation of resources towards enhanced growth instead of glycogen accumulation. Despite the stimulated growth of the mutant, acetate is shown to suppress the activity of the photosynthetic apparatus, further emphasizing the contribution of glycolytic metabolism in the acetate-induced effect. The use of acetate by the cyanobacterium Synechocystis sp. PCC 6803 is at least partially restricted by the import into the cell. This can be improved by the introduction of a heterologous acetate transporter into the system, thereby providing a potential advantage by expanding the scope of acetate utilization for various biosynthetic processes.

  4. Synechocystis PCC 6803 overexpressing RuBisCO grow faster with increased photosynthesis

    Directory of Open Access Journals (Sweden)

    Feiyan Liang

    2017-06-01

    Full Text Available The ribulose-1,5-bisphosphate (RuBP oxygenation reaction catalyzed by Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO is competing with carboxylation, being negative for both energy and carbon balances in photoautotrophic organisms. This makes RuBisCO one of the bottlenecks for oxygenic photosynthesis and carbon fixation. In this study, RuBisCO was overexpressed in the unicellular cyanobacterium Synechocystis PCC 6803. Relative RuBisCO levels in the engineered strains FL50 and FL52 increased 2.1 times and 1.4 times, respectively, and both strains showed increased growth, photosynthesis and in vitro RuBisCO activity. The oxygen evolution rate increased by 54% and 42% on per chlorophyll basis, while the in vitro RuBisCO activity increased by 52% and 8.6%, respectively. The overexpressed RuBisCO were tagged with a FLAG tag, in strain FL50 on the N terminus of the large subunit while in strain FL52 on the C terminus of the small subunit. The presence of a FLAG tag enhanced transcription of the genes encoding RuBisCO, and, with high possibility, also enhanced the initiation of translation or stability of the enzyme. However, when using a streptavidin-binding tag II (strep-tag II, we did not observe a similar effect. Tagged RuBisCO offers an opportunity for further studying RuBisCO expression and stability. Increased levels of RuBisCO can further improve photosynthesis and growth in the cyanobacterium Synechocystis PCC 6803 under certain growth conditions.

  5. Rubisco mutagenesis provides new insight into limitations on photosynthesis and growth in Synechocystis PCC6803

    Science.gov (United States)

    Marcus, Yehouda; Altman-Gueta, Hagit; Wolff, Yael; Gurevitz, Michael

    2011-01-01

    Orthophosphate (Pi) stimulates the activation of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) while paradoxically inhibiting its catalysis. Of three Pi-binding sites, the roles of the 5P- and latch sites have been documented, whereas that of the 1P-site remained unclear. Conserved residues at the 1P-site of Rubisco from the cyanobacterium Synechocystis PCC6803 were substituted and the kinetic properties of the enzyme derivatives and effects on cell photosynthesis and growth were examined. While Pi-stimulated Rubisco activation diminished for enzyme mutants T65A/S and G404A, inhibition of catalysis by Pi remained unchanged. Together with previous studies, the results suggest that all three Pi-binding sites are involved in stimulation of Rubisco activation, whereas only the 5P-site is involved in inhibition of catalysis. While all the mutations reduced the catalytic turnover of Rubisco (Kcat) between 6- and 20-fold, the photosynthesis and growth rates under saturating irradiance and inorganic carbon (Ci) concentrations were only reduced 40–50% (in the T65A/S mutants) or not at all (G404A mutant). Analysis of the mutant cells revealed a 3-fold increase in Rubisco content that partially compensated for the reduced Kcat so that the carboxylation rate per chlorophyll was one-third of that in the wild type. Correlation between the kinetic properties of Rubisco and the photosynthetic rate (Pmax) under saturating irradiance and Ci concentrations indicate that a >60% reduction in Kcat can be tolerated before Pmax in Synechocystsis PCC6803 is affected. These results indicate that the limitation of Rubisco activity on the rate of photosynthesis in Synechocystis is low. Determination of Calvin cycle metabolites revealed that unlike in higher plants, cyanobacterial photosynthesis is constrained by phosphoglycerate reduction probably due to limitation of ATP or NADPH. PMID:21551078

  6. An assessment of the usefulness of the cyanobacterium Synechococcus subsalsus as a source of biomass for biofuel production

    Directory of Open Access Journals (Sweden)

    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

  7. Towards a synthetic chloroplast.

    Directory of Open Access Journals (Sweden)

    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.

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

    Science.gov (United States)

    Saha, Rajib; Liu, Deng; Hoynes-O'Connor, Allison; Liberton, Michelle; Yu, Jingjie; Bhattacharyya-Pakrasi, Maitrayee; Balassy, Andrea; Zhang, Fuzhong; Moon, Tae Seok; Maranas, Costas D; Pakrasi, Himadri B

    2016-05-03

    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. Cyanobacteria are photosynthetic microbes that use energy from sunlight and CO2 as feedstock. Certain cyanobacterial strains are amenable to facile genetic manipulation, thus enabling

  9. 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.

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

    Directory of Open Access Journals (Sweden)

    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.

  11. Retrospective study of rFVIIa, 4-factor PCC, and a rFVIIa and 3-factor PCC combination in improving bleeding outcomes in the warfarin and non-warfarin patient.

    Science.gov (United States)

    DeLoughery, Emma; Avery, Brian; DeLoughery, Thomas G

    2016-07-01

    In case of severe bleeding, the physician must rapidly and effectively halt bleeding without the risk of thromboembolic complications. Despite widespread use, no study has directly compared recombinant activated factor VII (rFVIIa), the rFVIIa and 3-factor prothrombin complex concentrate (PCC) combination ("combination"), and 4-factor PCC on their effectiveness in improving patient outcomes. This study examined the medical records of 299 patients, 65.2% on warfarin prior to admission, who received these hemostatic agents and were admitted to an ICU or through the emergency department at Oregon Health & Science University. Mortality, length of stay, change in international normalized ratio (INR), plasma use, and number of thromboembolic complications were used to assess effectiveness. In patients receiving warfarin, the combination group had the greatest decrease in INR as well as lowest overall INR, but experienced a higher number of clotting complications, while the rFVIIa group used the most plasma. Non-warfarin patients in the combination group had the shortest length of stay among survivors, but the rFVIIa group had the lowest mortality. Based on this data, it may be prudent to further study the use of rFVIIa in treating extreme bleeding in the non-warfarin patient, while this study supports other data that 4-factor PCC may be the most prudent for the warfarin patient. Am. J. Hematol. 91:705-708, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  12. Flux coupling and transcriptional regulation within the metabolic network of the photosynthetic bacterium Synechocystis sp. PCC6803

    DEFF Research Database (Denmark)

    Montagud, Arnau; Zelezniak, Aleksej; Navarro, Emilio

    2011-01-01

    Synechocystis sp. PCC6803 is a model cyanobacterium capable of producing biofuels with CO2 as carbon source and with its metabolism fueled by light, for which it stands as a potential production platform of socio-economic importance. Compilation and characterization of Synechocystis genome...... networks, surrounded by a stable core of pathways leading to biomass building blocks. This analysis identified potential bottlenecks for hydrogen and ethanol production. Integration of transcriptomic data with the Synechocystis flux coupling networks lead to identification of reporter flux coupling pairs...... and reporter flux coupling groups - regulatory hot spots during metabolic shifts triggered by the availability of light. Overall, flux coupling analysis provided insight into the structural organization of Synechocystis sp. PCC6803 metabolic network toward designing of a photosynthesis-based production...

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

    Directory of Open Access Journals (Sweden)

    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.

  14. Correlation of coagulation markers and 4F-PCC-mediated reversal of rivaroxaban in a rabbit model of acute bleeding.

    Science.gov (United States)

    Herzog, Eva; Kaspereit, Franz; Krege, Wilfried; Mueller-Cohrs, Jochen; Doerr, Baerbel; Niebl, Peter; Dickneite, Gerhard

    2015-03-01

    Rivaroxaban is an oral, selective direct factor Xa inhibitor approved for several indications in patients at risk of thrombotic events. One limitation of its clinical use is the lack of data pertaining to its reversal in situations where urgent response is critical (e.g. acute bleeding events or emergency surgery). This study assessed the effectiveness of a four-factor prothrombin complex concentrate (4F-PCC; Beriplex(®)/Kcentra(®)) for the reversal of rivaroxaban-associated bleeding in an in vivo rabbit model, and evaluated the correlations between in vitro coagulation parameters and haemostasis in vivo. Administration of single intravenous doses of rivaroxaban (150-450 μg/kg) resulted in increased and prolonged bleeding following standardised kidney incision. Pre-incision treatment with 4F-PCC (25-100 IU/kg) resulted in a dose-dependent reversal of rivaroxaban (150 and 300 μg/kg)-associated increases in time to haemostasis and blood loss; no reversal was seen at the highest rivaroxaban dose (450 μg/kg). Of the in vitro biomarkers tested, thrombin generation and whole-blood clotting time correlated well with in vivo measures of 4F-PCC-mediated effects. Thrombin generation was highly reagent-dependent, with the assay initiated using the phospholipid-only reagent being the most predictive of effective haemostasis in vivo. In summary, in a rabbit model of acute bleeding, treatment with 4F-PCC reduced bleeding to control levels following rivaroxaban 150 μg/kg and 300 μg/kg administration. Copyright © 2015. Published by Elsevier Ltd.

  15. 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

  16. 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.

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

    OpenAIRE

    Iijima, Hiroko; Nakaya, Yuka; Kuwahara, Ayuko; Hirai, Masami Yokota; Osanai, Takashi

    2015-01-01

    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 bu...

  18. 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

    Directory of Open Access Journals (Sweden)

    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

  19. Utilization of blended fluidized bed combustion (FBC) ash and pulverized coal combustion (PCC) fly ash in geopolymer.

    Science.gov (United States)

    Chindaprasirt, Prinya; Rattanasak, Ubolluk

    2010-04-01

    In this paper, synthesis of geopolymer from fluidized bed combustion (FBC) ash and pulverized coal combustion (PCC) fly ash was studied in order to effectively utilize both ashes. FBC-fly ash and bottom ash were inter-ground to three different finenesses. The ashes were mixed with as-received PCC-fly ash in various proportions and used as source material for synthesis of geopolymer. Sodium silicate (Na(2)SiO(3)) and 10M sodium hydroxide (NaOH) solutions at mass ratio of Na(2)SiO(3)/NaOH of 1.5 and curing temperature of 65 degrees C for 48h were used for making geopolymer. X-ray diffraction (XRD), scanning electron microscopy (SEM), degree of reaction, and thermal gravimetric analysis (TGA) were performed on the geopolymer pastes. Compressive strength was also tested on geopolymer mortars. The results show that high strength geopolymer mortars of 35.0-44.0MPa can be produced using mixture of ground FBC ash and as-received PCC-fly ash. Fine FBC ash is more reactive and results in higher degree of reaction and higher strength geopolymer as compared to the use of coarser FBC ash. Grinding increases reactivity of ash by means of increasing surface area and the amount of reactive phase of the ash. In addition, the packing effect due to fine particles also contributed to increase in strength of geopolymers. Copyright 2009 Elsevier Ltd. All rights reserved.

  20. Improved sugar-free succinate production bySynechocystissp. PCC 6803 following identification of the limiting steps in glycogen catabolism.

    Science.gov (United States)

    Hasunuma, Tomohisa; Matsuda, Mami; Kondo, Akihiko

    2016-12-01

    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 CO 2 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 CO 2 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 phospho enol pyruvate (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 NaH 13 CO 3 clearly showed carbon incorporation into succinate via the anaplerotic pathway. Bicarbonate is in equilibrium with CO 2 . Succinate production by Synechocystis sp. PCC6803 therefore holds significant promise for CO 2 capture and utilization.

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

    Directory of Open Access Journals (Sweden)

    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

  2. Characterization of genes required for the pathogenicity of Pectobacterium carotovorum subsp. carotovorum Pcc21 in Chinese cabbage.

    Science.gov (United States)

    Lee, Dong Hwan; Lim, Jeong-A; Lee, Juneok; Roh, Eunjung; Jung, Kyusuk; Choi, Minseon; Oh, Changsik; Ryu, Sangryeol; Yun, Jongchul; Heu, Sunggi

    2013-07-01

    Pectobacterium carotovorum subsp. carotovorum is a well-known plant pathogen that causes severe soft rot disease in various crops, resulting in considerable economic loss. To identify pathogenicity-related factors, Chinese cabbage was inoculated with 5314 transposon mutants of P. carotovorum subsp. carotovorum Pcc21 derived using Tn5 transposon mutagenesis. A total of 35 reduced-virulence or avirulent mutants were isolated, and 14 loci were identified. The 14 loci could be functionally grouped into nutrient utilization (pyrD, purH, purD, leuA and serB), production of plant cell-wall-degrading enzymes (PCWDEs) (expI, expR and PCC21_023220), motility (flgA, fliA and flhB), biofilm formation (expI, expR and qseC), susceptibility to antibacterial plant chemicals (tolC) and unknown function (ECA2640). Among the 14 genes identified, qseC, tolC and PCC21_023220 are novel pathogenicity factors of P. carotovorum subsp. carotovorum involved in biofilm formation, phytochemical resistance and PCWDE production, respectively.

  3. The rnb gene of Synechocystis PCC6803 encodes a RNA hydrolase displaying RNase II and not RNase R enzymatic properties.

    Directory of Open Access Journals (Sweden)

    Rute G Matos

    Full Text Available Cyanobacteria are photosynthetic prokaryotic organisms that share characteristics with bacteria and chloroplasts regarding mRNA degradation. Synechocystis sp. PCC6803 is a model organism for cyanobacteria, but not much is known about the mechanism of RNA degradation. Only one member of the RNase II-family is present in the genome of Synechocystis sp PCC6803. This protein was shown to be essential for its viability, which indicates that it may have a crucial role in the metabolism of Synechocystis RNA. The aim of this work was to characterize the activity of the RNase II/R homologue present in Synechocystis sp. PCC6803. The results showed that as expected, it displayed hydrolytic activity and released nucleoside monophosphates. When compared to two E. coli counterparts, the activity assays showed that the Synechocystis protein displays RNase II, and not RNase R characteristics. This is the first reported case where when only one member of the RNase II/R family exists it displays RNase II and not RNase R characteristics.

  4. 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

  5. Transcriptomic response to prolonged ethanol production in the cyanobacterium Synechocystis sp. PCC6803.

    Science.gov (United States)

    Dienst, Dennis; Georg, Jens; Abts, Thomas; Jakorew, Lew; Kuchmina, Ekaterina; Börner, Thomas; Wilde, Annegret; Dühring, Ulf; Enke, Heike; Hess, Wolfgang R

    2014-02-06

    The production of biofuels in photosynthetic microalgae and cyanobacteria is a promising alternative to the generation of fuels from fossil resources. To be economically competitive, producer strains need to be established that synthesize the targeted product at high yield and over a long time. Engineering cyanobacteria into forced fuel producers should considerably interfere with overall cell homeostasis, which in turn might counteract productivity and sustainability of the process. Therefore, in-depth characterization of the cellular response upon long-term production is of high interest for the targeted improvement of a desired strain. The transcriptome-wide response to continuous ethanol production was examined in Synechocystis sp. PCC6803 using high resolution microarrays. In two independent experiments, ethanol production rates of 0.0338% (v/v) ethanol d-1 and 0.0303% (v/v) ethanol d-1 were obtained over 18 consecutive days, measuring two sets of biological triplicates in fully automated photobioreactors. Ethanol production caused a significant (~40%) delay in biomass accumulation, the development of a bleaching phenotype and a down-regulation of light harvesting capacity. However, microarray analyses performed at day 4, 7, 11 and 18 of the experiment revealed only three mRNAs with a strongly modified accumulation level throughout the course of the experiment. In addition to the overexpressed adhA (slr1192) gene, this was an approximately 4 fold reduction in cpcB (sll1577) and 3 to 6 fold increase in rps8 (sll1809) mRNA levels. Much weaker modifications of expression level or modifications restricted to day 18 of the experiment were observed for genes involved in carbon assimilation (Ribulose bisphosphate carboxylase and Glutamate decarboxylase). Molecular analysis of the reduced cpcB levels revealed a post-transcriptional processing of the cpcBA operon mRNA leaving a truncated mRNA cpcA* likely not competent for translation. Moreover, western blots and zinc

  6. 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

  7. 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

    Directory of Open Access Journals (Sweden)

    Eric Daniel Becraft

    2015-06-01

    Full Text Available 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 and transcripts over a large number of habitat types in the Mushroom Spring microbial mat. Putative ecological species (putative ecotypes, which were predicted by an evolutionary simulation based on the Stable Ecotype Model (Ecotype Simulation, exhibited distinct distributions relative to temperature-defined positions in the effluent channel and vertical position in the upper 1 mm-thick mat layer. Importantly, in most cases variants predicted to belong to the same putative ecotype formed unique clusters relative to temperature and depth in the mat in canonical correspondence analysis, supporting the hypothesis that while the putative ecotypes are ecologically distinct, the members of each ecotype are ecologically homogeneous. Putative ecotypes responded differently to experimental perturbations of temperature and light, but the genetic variation within each putative ecotype was maintained as the relative abundances of putative ecotypes changed, further indicating that each population responded as a set of ecologically interchangeable individuals. Compared to putative ecotypes that predominate deeper within the mat photic zone, the timing of transcript abundances for selected genes differed for putative ecotypes that predominate in microenvironments closer to upper surface of the mat with spatiotemporal differences in light and O2 concentration. All of these findings are consistent with the hypotheses that Synechococcus species in hot spring mats are sets of ecologically interchangeable individuals that are differently adapted, that these adaptations control their distributions, and that the resulting distributions constrain the activities of the species

  8. Reversal of Vitamin K Antagonist (VKA) effect in patients with severe bleeding: a French multicenter observational study (Optiplex) assessing the use of Prothrombin Complex Concentrate (PCC) in current clinical practice.

    Science.gov (United States)

    Desmettre, Thibaut; Dehours, Emilie; Samama, Charles-Marc; Jhundoo, Suchin; Pujeau, Frédéric; Guillaudin, Christian; Hecquart, Claudine; Clerson, Pierre; Crave, Jean Charles; Jaussaud, Roland

    2012-10-04

    Prothrombin Complex Concentrate (PCC) is a key treatment in the management of bleeding related to Vitamin K antagonists (VKA). This study aimed to evaluate prospectively PCC use in patients with VKA-related bleeding in view of the French guidelines published in 2008. All consecutive patients with VKA-related bleeding treated with a 4-factor PCC (Octaplex®) were selected in 33 French hospitals. Collected data included demographics, site and severity of bleeding, modalities of PCC administration, International Normalized Ratio (INR) values before and after PCC administration, outcomes and survival rate 15 days after infusion. Of 825 patients who received PCC between August 2008 and December 2010, 646 had severe bleeding. The main haemorrhage sites were intracranial (43.7%) and abdominal (24.3%). Mean INR before PCC was 4.4 ± 1.9; INR was unavailable in 12.5% of patients. The proportions of patients who received a PCC dose according to guidelines were 15.8% in patients with initial INR 2-2.5, 41.5% in patients with INR 2.5-3, 40.8% in patients with INR 3-3.5, 26.9% in patients with INR > 3.5, and 63.5% of patients with unknown INR. Vitamin K was administered in 84.7% of patients. The infused dose of PCC did not vary with initial INR; the mean dose was 25.3 ± 9.8 IU/Kg. Rates of controlled bleeding and target INR achievement were similar, regardless of whether or not patients were receiving PCC doses as per the guidelines. No differences in INR after PCC treatment were observed, regardless of whether or not vitamin K was administered. INR was first monitored after a mean time frame of 4.5 ± 5.6 hours post PCC. The overall survival rate at 15 days after PCC infusion was 75.4% (65.1% in patients with intracranial haemorrhage). A better prognosis was observed in patients reaching the target INR. Severe bleeding related to VKA needs to be better managed, particularly regarding the PCC infused dose, INR monitoring and administration of vitamin K. A dose of 25 IU/kg PCC

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

    Science.gov (United States)

    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.

  10. Identification of gene disruptions for increased poly-3-hydroxybutyrate accumulation in Synechocystis PCC 6803.

    Science.gov (United States)

    Tyo, Keith E J; Jin, Yong-Su; Espinoza, Freddy A; Stephanopoulos, Gregory

    2009-01-01

    Inverse metabolic engineering (IME) is a combinatorial approach for identifying genotypes associated with a particular phenotype of interest. In this study, gene disruptions that increase the biosynthesis of poly-3-hydroxybutyrate (PHB) in the photosynthetic bacterium Synechocystis PCC6803 were identified. A Synechocystis mutant library was constructed by homologous recombination between the Synechocystis genome and a mutagenized genomic plasmid library generated through transposon insertion. Using a fluorescence-activated cell sorting-based high throughput screen, high PHB accumulating mutants from the library grown in different nutrient conditions were isolated and characterized. While several mutants isolated from the screen had increased PHB accumulation, transposon insertions in only two ORFs could be linked to increased PHB production. Disruptions of sll0461, coding for gamma-glutamyl phosphate reductase (proA), and sll0565, a hypothetical protein, resulted in increased accumulation in standard growth media and acetate supplemented media. These genetic perturbations have increased PHB accumulation in Synechocystis and serve as markers for engineering increased polymer production in higher photosynthetic organisms. 2009 American Institute of Chemical Engineers Biotechnol.

  11. Structural integrity of Synechocystis sp. PCC 6803 phycobilisomes evaluated by means of differential scanning calorimetry.

    Science.gov (United States)

    Petrova, Nia; Todinova, Svetla; Laczko-Dobos, Hajnalka; Zakar, Tomas; Vajravel, Sindhujaa; Taneva, Stefka; Gombos, Zoltan; Krumova, Sashka

    2018-01-10

    Phycobilisomes (PBSs) are supramolecular pigment-protein complexes that serve as light-harvesting antennae in cyanobacteria. They are built up by phycobiliproteins assembled into allophycocyanin core cylinders (ensuring the physical interaction with the photosystems) and phycocyanin rods (protruding from the cores and having light-harvesting function), the whole PBSs structure being maintained by linker proteins. PBSs play major role in light-harvesting optimization in cyanobacteria; therefore, the characterization of their structural integrity in intact cells is of great importance. The present study utilizes differential scanning calorimetry and spectroscopy techniques to explore for the first time, the thermodynamic stability of PBSs in intact Synechocystis sp. PCC 6803 cells and to probe its alteration as a result of mutations or under different growth conditions. As a first step, we characterize the thermodynamic behavior of intact and dismantled PBSs isolated from wild-type cells (having fully assembled PBSs) and from CK mutant cells (that lack phycocyanin rods and contain only allophycocyanin cores), and identified the thermal transitions of phycocyanin and allophycocyanin units in vitro. Next, we demonstrate that in intact cells PBSs exhibit sharp, high amplitude thermal transition at about 63 °C that strongly depends on the structural integrity of the PBSs supercomplex. Our findings implicate that calorimetry could offer a valuable approach for the assessment of the influence of variety of factors affecting the stability and structural organization of phycobilisomes in intact cyanobacterial cells.

  12. Overexpression of plastid terminal oxidase inSynechocystissp. PCC 6803 alters cellular redox state.

    Science.gov (United States)

    Feilke, Kathleen; Ajlani, Ghada; Krieger-Liszkay, Anja

    2017-09-26

    Cyanobacteria are the most ancient organisms performing oxygenic photosynthesis, and they are the ancestors of plant plastids. All plastids contain the plastid terminal oxidase (PTOX), while only certain cyanobacteria contain PTOX. Many putative functions have been discussed for PTOX in higher plants including a photoprotective role during abiotic stresses like high light, salinity and extreme temperatures. Since PTOX oxidizes PQH 2 and reduces oxygen to water, it is thought to protect against photo-oxidative damage by removing excess electrons from the plastoquinone (PQ) pool. To investigate the role of PTOX we overexpressed rice PTOX fused to the maltose-binding protein (MBP-OsPTOX) in Synechocystis sp. PCC 6803, a model cyanobacterium that does not encode PTOX. The fusion was highly expressed and OsPTOX was active, as shown by chlorophyll fluorescence and P 700 absorption measurements. The presence of PTOX led to a highly oxidized state of the NAD(P)H/NAD(P) + pool, as detected by NAD(P)H fluorescence. Moreover, in the PTOX overexpressor the electron transport capacity of PSI relative to PSII was higher, indicating an alteration of the photosystem I (PSI) to photosystem II (PSII) stoichiometry. We suggest that PTOX controls the expression of responsive genes of the photosynthetic apparatus in a different way from the PQ/PQH 2 ratio.This article is part of the themed issue 'Enhancing photosynthesis in crop plants: targets for improvement'. © 2017 The Author(s).

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

    Directory of Open Access Journals (Sweden)

    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.

  14. Biosafety of biotechnologically important microalgae: intrinsic suicide switch implementation in cyanobacterium Synechocystis sp. PCC 6803

    Directory of Open Access Journals (Sweden)

    Helena Čelešnik

    2016-04-01

    Full Text Available In recent years, photosynthetic autotrophic cyanobacteria have attracted interest for biotechnological applications for sustainable production of valuable metabolites. Although biosafety issues can have a great impact on public acceptance of cyanobacterial biotechnology, biosafety of genetically modified cyanobacteria has remained largely unexplored. We set out to incorporate biocontainment systems in the model cyanobacterium Synechocystis sp. PCC 6803. Plasmid-encoded safeguards were constructed using the nonspecific nuclease NucA from Anabaena combined with different metal-ion inducible promoters. In this manner, conditional lethality was dependent on intracellular DNA degradation for regulated autokilling as well as preclusion of horizontal gene transfer. In cells carrying the suicide switch comprising the nucA gene fused to a variant of the copM promoter, efficient inducible autokilling was elicited. Parallel to nuclease-based safeguards, cyanobacterial toxin/antitoxin (TA modules were examined in biosafety switches. Rewiring of Synechocystis TA pairs ssr1114/slr0664 and slr6101/slr6100 for conditional lethality using metal-ion responsive promoters resulted in reduced growth, rather than cell killing, suggesting cells could cope with elevated toxin levels. Overall, promoter properties and translation efficiency influenced the efficacy of biocontainment systems. Several metal-ion promoters were tested in the context of safeguards, and selected promoters, including a nrsB variant, were characterized by beta-galactosidase reporter assay.

  15. Regulation of the scp Genes in the Cyanobacterium Synechocystis sp. PCC 6803--What is New?

    Science.gov (United States)

    Cheregi, Otilia; Funk, Christiane

    2015-08-12

    In the cyanobacterium Synechocystis sp. PCC 6803 there are five genes encoding small CAB-like (SCP) proteins, which have been shown to be up-regulated under stress. Analyses of the promoter sequences of the scp genes revealed the existence of an NtcA binding motif in two scp genes, scpB and scpE. Binding of NtcA, the key transcriptional regulator during nitrogen stress, to the promoter regions was shown by electrophoretic mobility shift assay. The metabolite 2-oxoglutarate did not increase the affinity of NtcA for binding to the promoters of scpB and scpE. A second motif, the HIP1 palindrome 5' GGCGATCGCC 3', was detected in the upstream regions of scpB and scpC. The transcription factor encoded by sll1130 has been suggested to recognize this motif to regulate heat-responsive genes. Our data suggest that HIP1 is not a regulatory element within the scp genes. Further, the presence of the high light regulatory (HLR1) motif was confirmed in scpB-E, in accordance to their induced transcriptions in cells exposed to high light. The HLR1 motif was newly discovered in eight additional genes.

  16. 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)

  17. Metabolic Changes in Synechocystis PCC6803 upon Nitrogen-Starvation: Excess NADPH Sustains Polyhydroxybutyrate Accumulation

    Science.gov (United States)

    Hauf, Waldemar; Schlebusch, Maximilian; Hüge, Jan; Kopka, Joachim; Hagemann, Martin; Forchhammer, Karl

    2013-01-01

    Polyhydroxybutyrate (PHB) is a common carbon storage polymer among heterotrophic bacteria. It is also accumulated in some photoautotrophic cyanobacteria; however, the knowledge of how PHB accumulation is regulated in this group is limited. PHB synthesis in Synechocystis sp. PCC 6803 is initiated once macronutrients like phosphorus or nitrogen are limiting. We have previously reported a mutation in the gene sll0783 that impairs PHB accumulation in this cyanobacterium upon nitrogen starvation. In this study we present data which explain the observed phenotype. We investigated differences in intracellular localization of PHB synthase, metabolism, and the NADPH pool between wild type and mutant. Localization of PHB synthase was not impaired in the sll0783 mutant; however, metabolome analysis revealed a difference in sorbitol levels, indicating a more oxidizing intracellular environment than in the wild type. We confirmed this by directly measuring the NADPH/NADP ratio and by altering the intracellular redox state of wild type and sll0783 mutant. We were able to physiologically complement the mutant phenotype of diminished PHB synthase activity by making the intracellular environment more reducing. Our data illustrate that the NADPH pool is an important factor for regulation of PHB biosynthesis and metabolism, which is also of interest for potential biotechnological applications. PMID:24957892

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Science.gov (United States)

    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

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

    Directory of Open Access Journals (Sweden)

    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.

  3. Iron starvation-induced proteomic changes in Anabaena (Nostoc) sp. PCC 7120: exploring survival strategy.

    Science.gov (United States)

    Narayan, Om Prakash; Kumari, Nidhi; Rai, Lal Chand

    2011-02-01

    This study provides first-hand proteomic data on the survival strategy of Anabaena sp. PCC 7120 when subjected to long-term iron-starvation conditions. 2D-gel electrophoresis followed by MALDI-TOF/MS analysis of iron-deficient Anabaena revealed significant and reproducible alterations in ten proteins, of which six are associated with photosynthesis and respiration, three with the antioxidative defense system, and the last, hypothetical protein all1861, conceivably connected with iron homeostasis. Iron-starved Anabaena registered a reduction in growth, photosynthetic pigments, PSI, PSII, whole-chain electron transport, carbon and nitrogen fixation, and ATP and NADPH content. The kinetics of hypothetical protein all1861 expression, with no change in expression until day 3, maximum expression on the 7th day, and a decline in expression from the 15th day onward, coupled with in silico analysis, suggested its role in iron sequestration and homeostasis. Interestingly, the up-regulated FBP-aldolase, Mn/Fe-SOD, and all1861 all appear to assist the survival of Anabeana subjected to iron-starvation conditions. Furthermore, the N2-fixation capabilities of the iron-starved Anabaena encourage us to recommend its application as a biofertilizer, particularly in iron-limited paddy soils.

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

    Science.gov (United States)

    Liu, Jie; Chen, Lei; Wang, Jiangxin; Qiao, Jianjun; Zhang, Weiwen

    2012-09-07

    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. 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. 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.

  5. Metabolic Changes in Synechocystis PCC6803 upon Nitrogen-Starvation: Excess NADPH Sustains Polyhydroxybutyrate Accumulation

    Directory of Open Access Journals (Sweden)

    Waldemar Hauf

    2013-02-01

    Full Text Available Polyhydroxybutyrate (PHB is a common carbon storage polymer among heterotrophic bacteria. It is also accumulated in some photoautotrophic cyanobacteria; however, the knowledge of how PHB accumulation is regulated in this group is limited. PHB synthesis in Synechocystis sp. PCC 6803 is initiated once macronutrients like phosphorus or nitrogen are limiting. We have previously reported a mutation in the gene sll0783 that impairs PHB accumulation in this cyanobacterium upon nitrogen starvation. In this study we present data which explain the observed phenotype. We investigated differences in intracellular localization of PHB synthase, metabolism, and the NADPH pool between wild type and mutant. Localization of PHB synthase was not impaired in the sll0783 mutant; however, metabolome analysis revealed a difference in sorbitol levels, indicating a more oxidizing intracellular environment than in the wild type. We confirmed this by directly measuring the NADPH/NADP ratio and by altering the intracellular redox state of wild type and sll0783 mutant. We were able to physiologically complement the mutant phenotype of diminished PHB synthase activity by making the intracellular environment more reducing. Our data illustrate that the NADPH pool is an important factor for regulation of PHB biosynthesis and metabolism, which is also of interest for potential biotechnological applications.

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

    Directory of Open Access Journals (Sweden)

    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.

  7. Premethylation of foreign DNA improves integrative transformation efficiency in Synechocystis sp. strain PCC 6803.

    Science.gov (United States)

    Wang, Bo; Yu, Jianping; Zhang, Weiwen; Meldrum, Deirdre R

    2015-12-01

    Restriction digestion of foreign DNA is one of the key biological barriers against genetic transformation in microorganisms. To establish a high-efficiency transformation protocol in the model cyanobacterium, Synechocystis sp. strain PCC 6803 (Synechocystis 6803), we investigated the effects of premethylation of foreign DNA on the integrative transformation of this strain. In this study, two type II methyltransferase-encoding genes, i.e., sll0729 (gene M) and slr0214 (gene C), were cloned from the chromosome of Synechocystis 6803 and expressed in Escherichia coli harboring an integration plasmid. After premethylation treatment in E. coli, the integration plasmid was extracted and used for transformation of Synechocystis 6803. The results showed that although expression of methyltransferase M had little impact on the transformation of Synechocystis 6803, expression of methyltransferase C resulted in 11- to 161-fold-higher efficiency in the subsequent integrative transformation of Synechocystis 6803. Effective expression of methyltransferase C, which could be achieved by optimizing the 5' untranslated region, was critical to efficient premethylation of the donor DNA and thus high transformation efficiency in Synechocystis 6803. Since premethylating foreign DNA prior to transforming Synechocystis avoids changing the host genetic background, the study thus provides an improved method for high-efficiency integrative transformation of Synechocystis 6803. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  8. Effectiveness of prothrombin complex concentrate (PCC) in neonates and infants with bleeding or risk of bleeding: a systematic review and meta-analysis.

    Science.gov (United States)

    Zeng, Linan; Choonara, Imti; Zhang, Lingli; Li, Youping; Shi, Jing

    2017-05-01

    To systematically evaluate the effectiveness of prothrombin complex concentrate (PCC) in neonates and infants, we performed a systematic review and meta-analysis based on current evidence. Quality of studies was assessed by Cochrane Collaboration's risk of bias tool and Newcastle-Ottawa quality assessment scale. For dichotomous data, we obtained the number of events and total number and calculated the relative risk (RR) with 95% confidence intervals (CI). For continuous variables, we obtained mean and standard deviation (SD) values and calculated mean difference (MD) with 95% CI. We identified six trials and two cohort studies. For trials, selection bias and performance bias were high, while detection bias, attrition bias, and reporting bias were relatively low. For cohort studies, selection bias was low. Both individual studies and meta-analysis failed to find any benefit of PCC on mortality. Meta-analysis also failed to show any benefit in reducing intracranial hemorrhage. The effectiveness of PCC on the correction of hemostatic defects was inconsistent among studies. In addition, PCC was not more effective than fresh frozen plasma (FFP) in correcting hemostatic defects. There is insufficient evidence to allow a recommendation for use of PCC in neonates and infants. What is Known: • Prothrombin Complex Concentrate is becoming increasingly used off-label for treatment of neonates and infants with severe bleeding or risk of severe bleeding. • Some case reports showed PCC seemed to be effective for infants and children with coagulation factor deficiency, but evidence about the effectiveness of PCC to reverse serious Vitamin K Deficiency Bleeding is limited. What is New: • As far as we know, this is the first systematic review that evaluates the effectiveness of PPC in neonates with bleeding or risk of bleeding. • There is insufficient evidence to allow a recommendation for use of PCCs in neonates and infants.

  9. 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.

  10. 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.

  11. 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.

  12. Comparison between Prothrombin Complex Concentrate (PCC) and Fresh Frozen Plasma (FFP) for the Urgent Reversal of Warfarin in Patients with Mechanical Heart Valves in a Tertiary Care Cardiac Center.

    Science.gov (United States)

    Fariborz Farsad, Bahram; Golpira, Reza; Najafi, Hamideh; Totonchi, Ziae; Salajegheh, Shirin; Bakhshandeh, Hooman; Hashemian, Farshad

    2015-01-01

    Fresh frozen plasma (FFP) and prothrombin complex concentrate (PCC) reverse oral anticoagulants such as Warfarin. We compared the standard dosage of FFP and PCC in terms of efficacy and safety for patients with mechanical heart valves undergoing interventional procedures while receiving Warfarin. Fifty patients were randomized (25 for each group) with mechanical heart valves [international normalized ratio (INR) >2.5]. FFP dosage was administered based on body weight (10-15 mL/Kg), while PCC dosage was administered based on both body weight and target INR. INR measurements were obtained at different time after PCC and FFP infusion. The mean ± SD of INR pre treatment was not significantly different between the PCC and FFP groups. However, over a 48-hour period following the administration of PCC and FFP, 76% of the patients in the PCC group and only 20% of the patients in the FFP group reached the INR target. Five (20%) patients in the PCC group received an additional dose of PCC, whereas 17 (68%) patients in the FFP group received a further dose of FFP (P=0.001). There was no significant difference between the two groups in Hb and Hct before and during a 48-hour period after PCC and FFP infusion. As regards safety monitoring and adverse drug reaction screening in the FFP group, the INR was high (INR > 2.5) in 86% of the patients. There was no report of hemorrhage in both groups. PCC reverses anticoagulation both effectively and safely while having the advantage of obviating the need to extra doses.

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

    Directory of Open Access Journals (Sweden)

    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

  14. Distinguishing the Roles of Thylakoid Respiratory Terminal Oxidases in the Cyanobacterium Synechocystis sp. PCC 6803.

    Science.gov (United States)

    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.

  15. Phosphoproteome of the cyanobacterium Synechocystis sp. PCC 6803 and its dynamics during nitrogen starvation.

    Directory of Open Access Journals (Sweden)

    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.

  16. Mechanisms of High Temperature Resistance of Synechocystis sp. PCC 6803: An Impact of Histidine Kinase 34

    Directory of Open Access Journals (Sweden)

    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.

  17. Global transcriptional profiles of the copper responses in the cyanobacterium Synechocystis sp. PCC 6803.

    Directory of Open Access Journals (Sweden)

    Joaquin Giner-Lamia

    Full Text Available Copper is an essential element involved in fundamental processes like respiration and photosynthesis. However, it becomes toxic at high concentration, which has forced organisms to control its cellular concentration. We have recently described a copper resistance system in the cyanobacterium Synechocystis sp. PCC 6803, which is mediated by the two-component system, CopRS, a RND metal transport system, CopBAC and a protein of unknown function, CopM. Here, we report the transcriptional responses to copper additions at non-toxic (0.3 µM and toxic concentrations (3 µM in the wild type and in the copper sensitive copR mutant strain. While 0.3 µM copper slightly stimulated metabolism and promoted the exchange between cytochrome c6 and plastocyanin as soluble electron carriers, the addition of 3 µM copper catalyzed the formation of ROS, led to a general stress response and induced expression of Fe-S cluster biogenesis genes. According to this, a double mutant strain copRsufR, which expresses constitutively the sufBCDS operon, tolerated higher copper concentration than the copR mutant strain, suggesting that Fe-S clusters are direct targets of copper toxicity in Synechocystis. In addition we have also demonstrated that InrS, a nickel binding transcriptional repressor that belong to the CsoR family of transcriptional factor, was involved in heavy metal homeostasis, including copper, in Synechocystis. Finally, global gene expression analysis of the copR mutant strain suggested that CopRS only controls the expression of copMRS and copBAC operons in response to copper.

  18. Stable transformation of the cyanobacterium Synechocystis sp. PCC 6803 induced by UV irradiation

    International Nuclear Information System (INIS)

    Dzelzkalns, V.A.; Bogorad, L.

    1986-01-01

    Irradiation of the photoheterotrophic cyanobacterium Synechocystis sp. PCC 6803 with low levels of UV light allows for stable, integrative transformation of these cells by heterologous DNA. In this system, transformation does not rely on an autonomously replicating plasmid and is independent of homologous recombination. Cells treated with UV light in the absence of DNA and cells given DNA but not exposed to UV do not yield antibiotic-resistant colonies in platings of up to 2 x 10 8 cells. Optimal conditions for this UV-induced transformation are described. Analysis of the transformants indicates that (i) only a segment of the introduced plasmid is found in the DNA of the transformed cells; (ii) in independently isolated clones, DNA insertion apparently occurs at different sites in the chromosome; and (iii) hybridization data suggest that insertion in one of the transformants may have occurred into a region of the chromosome that is repeated or that integration of plasmid DNA may have been accompanied by a rearrangement or duplication of DNA sequences near the insertion site. DNA isolated from the primary transformants as well as a cloned fragment containing the UV- inserted plasmid sequence and flanking cyanobacterial DNA transform wild-type cells at a high frequency (5.0 x 10 -4 and 1.5 x 10 -5 , respectively). Possible mechanisms of this transformation system are discussed, as are the potential uses of this system as an integrative cloning-complementation vector and as a mutagenic agent in which the genetic lesion is already tagged with a selectable marker

  19. Identification of a transporter Slr0982 involved in ethanol tolerance in cyanobacterium Synechocystis sp. PCC 6803

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  2. 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

  3. Down-Regulation of the Alternative Sigma Factor SigJ Confers a Photoprotective Phenotype to Anabaena PCC 7120.

    Science.gov (United States)

    Srivastava, Amit; Brilisauer, Klaus; Rai, Ashutosh K; Ballal, Anand; Forchhammer, Karl; Tripathi, Anil K

    2017-02-01

    Alternative sigma factors belonging to Group 3 are thought to play an important role in the adaptation of cyanobacteria to environmental challenges by altering expression of genes needed for coping with such stresses. In this study, the role of an alternative sigma factor, SigJ, was analyzed in the filamentous nitrogen-fixing cyanobacterium, Anabaena sp. PCC 7120 by knocking down the expression of the sigJ gene (alr0277) employing an antisense RNA-mediated approach. In the absence of any stress, the knock-down (KD0277) or the wild-type strain both grew similarly. Upon exposure to high-intensity light, KD0277 showed substantially reduced bleaching of its pigments, higher photosynthetic activity and consequently better survival than the wild type. KD0277 also showed an enhanced accumulation of two carotenoids, which were identified as myxoxanthophyll and keto-myxoxanthophyll. Further, KD0277 was more tolerant to ammonium-triggered photodamage than the wild type. Moreover, PSII was better protected against photodamage in KD0277 than in the wild type. Down-regulation of sigJ in Anabaena PCC 7120, however, reduced its ability to cope with desiccation. This study demonstrates that down-regulation of the sigJ gene in Anabaena PCC 7120 differentially affects its ability to tolerate two environmentally relevant stresses, i.e. high-intensity light and desiccation. © 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.

  4. Daily expression pattern of protein-encoding genes and small noncoding RNAs in synechocystis sp. strain PCC 6803.

    Science.gov (United States)

    Beck, Christian; Hertel, Stefanie; Rediger, Anne; Lehmann, Robert; Wiegard, Anika; Kölsch, Adrian; Heilmann, Beate; Georg, Jens; Hess, Wolfgang R; Axmann, Ilka M

    2014-09-01

    Many organisms harbor circadian clocks with periods close to 24 h. These cellular clocks allow organisms to anticipate the environmental cycles of day and night by synchronizing circadian rhythms with the rising and setting of the sun. These rhythms originate from the oscillator components of circadian clocks and control global gene expression and various cellular processes. The oscillator of photosynthetic cyanobacteria is composed of three proteins, KaiA, KaiB, and KaiC, linked to a complex regulatory network. Synechocystis sp. strain PCC 6803 possesses the standard cyanobacterial kaiABC gene cluster plus multiple kaiB and kaiC gene copies and antisense RNAs for almost every kai transcript. However, there is no clear evidence of circadian rhythms in Synechocystis sp. PCC 6803 under various experimental conditions. It is also still unknown if and to what extent the multiple kai gene copies and kai antisense RNAs affect circadian timing. Moreover, a large number of small noncoding RNAs whose accumulation dynamics over time have not yet been monitored are known for Synechocystis sp. PCC 6803. Here we performed a 48-h time series transcriptome analysis of Synechocystis sp. PCC 6803, taking into account periodic light-dark phases, continuous light, and continuous darkness. We found that expression of functionally related genes occurred in different phases of day and night. Moreover, we found day-peaking and night-peaking transcripts among the small RNAs; in particular, the amounts of kai antisense RNAs correlated or anticorrelated with those of their respective kai target mRNAs, pointing toward the regulatory relevance of these antisense RNAs. Surprisingly, we observed that the amounts of 16S and 23S rRNAs in this cyanobacterium fluctuated in light-dark periods, showing maximum accumulation in the dark phase. Importantly, the amounts of all transcripts, including small noncoding RNAs, did not show any rhythm under continuous light or darkness, indicating the absence

  5. O PCC em São Paulo: coletivo de presos ou organização criminosa?

    OpenAIRE

    Alex Moreira

    2012-01-01

    As duas últimas décadas trouxeram transformações para o estado de São Paulo no que tange a segurança pública. O sistema carcerário, em especial, sofreu significativas mudanças estruturais e funcionais. Essas transformações englobam: o grande plano de expansão do sistema carcerário promovido pelo governo paulista; o exorbitante crescimento da população carcerária; e o nascimento e hegemonia do PCC (Primeiro Comando da Capital) dentro do sistema. A proposta aqui apresentada é o estudo da atuaçã...

  6. Characterization of three putative xylulose 5-phosphate/fructose 6-phosphate phosphoketolases in the cyanobacterium Anabaena sp. PCC 7120.

    Science.gov (United States)

    Moriyama, Takashi; Tajima, Naoyuki; Sekine, Kohsuke; Sato, Naoki

    2015-01-01

    Xylulose 5-phosphate/fructose 6-phosphate phosphoketolase (Xfp) is a key enzyme in the central carbohydrate metabolism in heterofermentative bacteria, in which enzymatic property of Xfps is well characterized. This is not the case in other microbes. The cyanobacterium Anabaena sp. PCC 7120 possesses three putative genes encoding Xfp, all1483, all2567, and alr1850. We purified three putative Xfps as recombinant proteins. The results of gel filtration indicated that these proteins form homomultimer complex. All1483 and All2567 showed phosphoketolase activity, whereas Alr1850 did not show the activity. Kinetic analyses demonstrated that substrates, fructose 6-phosphate and inorganic phosphate, are cooperatively bound to enzymes positively and negatively, respectively.

  7. Role of prothrombin complex concentrate (PCC) in Acute Intracerebral Hemorrhage with Positive CTA spot sign: An institutional experience at a regional and state designated stroke center.

    Science.gov (United States)

    Rehmani, Razia; Han, Angela; Hassan, Jawaad; Farkas, Jeffrey

    2017-06-01

    Our objective is to identify the effect of prothrombin complex concentrate (PCC) in acute intracranial hemorrhage (ICH) by evaluating intraparenchymal hematoma expansion between initial and follow-up head CT at 5-24 h, in those with positive CTA spot sign (CTASS). CTASS is an independent predictor of hematoma growth (1). Acute ICH, regardless of etiology, can present with quick mental status decline often resulting in irreversible brain damage. Hematoma expansion appears to be a modifiable predictor of clinical outcome and an appropriate target for medical therapy. PCC is a procoagulant which is the agent of choice in warfarin-related ICH. We explore utility of PCC in all patients regardless of warfarin status. We retrospectively reviewed patients with ICH at our NY State designated Stroke Center from Nov 2013 to Dec 2015. Twenty-three of the 85 patients with ICH received PCC, of which 8 had positive CTASS (E = 8). Four of the 62 patients without PCC, had a positive CTASS (C = 4). Interval change in ICH volume at 5-24 h was measured using ABC/2 formula, which is an accurate predictor of ICH volume (5). Control group (C) showed increase in mean ICH volume of 46% (SD = 37.3%), whereas experimental group (E) showed a decrease of 13% (SD = 29.9%) (p value = 0.012). We found a strong statistical correlation favoring our hypothesis. Use of PCC in active ICH with positive CTASS resulted in overall decrease in the mean hematoma size at 24 h, whereas the control group showed an overall increase.

  8. 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

    Directory of Open Access Journals (Sweden)

    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.

  9. 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

    Directory of Open Access Journals (Sweden)

    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

  10. Glutaredoxins are essential for stress adaptation in the cyanobacterium Synechocystis sp. PCC 6803.

    Directory of Open Access Journals (Sweden)

    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.

  11. 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

  12. 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

  13. Small Antisense RNA RblR Positively Regulates RuBisCo inSynechocystissp. PCC 6803.

    Science.gov (United States)

    Hu, Jinlu; Li, Tianpei; Xu, Wen; Zhan, Jiao; Chen, Hui; He, Chenliu; Wang, Qiang

    2017-01-01

    Small regulatory RNAs (sRNAs) function as transcriptional and post-transcriptional regulators of gene expression in organisms from all domains of life. Cyanobacteria are thought to have developed a complex RNA-based regulatory mechanism. In the current study, by genome-wide analysis of differentially expressed small RNAs in Synechocystis sp. PCC 6803 under high light conditions, we discovered an asRNA (RblR) that is 113nt in length and completely complementary to its target gene rbcL , which encodes the large chain of RuBisCO, the enzyme that catalyzes carbon fixation. Further analysis of the RblR(+)/(-) mutants revealed that RblR acts as a positive regulator of rbcL under various stress conditions; Suppressing RblR adversely affects carbon assimilation and thus the yield, and those phenotypes of both the wild type and the overexpressor could be downgraded to the suppressor level by carbonate depletion, indicated a regulatory role of RblR in CO 2 assimilation. In addition, a real-time expression platform in Escherichia coli was setup and which confirmed that RblR promoted the translation of the rbcL mRNA into the RbcL protein. The present study is the first report of a regulatory RNA that targets RbcL in Synechocystis sp. PCC 6803, and provides strong evidence that RblR regulates photosynthesis by positively modulating rbcL expression in Synechocystis .

  14. NDH-1 Is Important for Photosystem I Function ofSynechocystissp. Strain PCC 6803 under Environmental Stress Conditions.

    Science.gov (United States)

    Zhao, Jiaohong; Gao, Fudan; Fan, Da-Yong; Chow, Wah Soon; Ma, Weimin

    2017-01-01

    Cyanobacterial NDH-1 interacts with photosystem I (PSI) to form an NDH-1-PSI supercomplex. Here, we observed that absence of NDH-1 had little, if any, effect on the functional fractions of PSI under growth conditions, but significantly reduced the functional fractions of PSI when cells of Synechocystis sp. strain PCC 6803 were moved to conditions of multiple stresses. The significant reduction in NDH-1-dependent functional fraction of PSI was initiated after PSII activity was impaired. This finding is consistent with our observation that the functional fraction of PSI under growth conditions was rapidly and significantly decreased with increasing concentrations of DCMU, which rapidly and significantly suppressed PSII activity by blocking the transfer of electrons from Q A to Q B in the PSII reaction center. Furthermore, absence of NDH-1 resulted in the PSI limitation at the functionality of PSI itself but not its donor-side and acceptor-side under conditions of multiple stresses. This was supported by the result of a significant destabilization of the PSI complex in the absence of NDH-1 but the presence of multiple stresses. Based on the above results, we propose that NDH-1 is important for PSI function of Synechocystis sp. strain PCC 6803 mainly via maintaining stabilization of PSI under conditions of environmental stresses.

  15. NDH-1 Is Important for Photosystem I Function of Synechocystis sp. Strain PCC 6803 under Environmental Stress Conditions

    Directory of Open Access Journals (Sweden)

    Jiaohong Zhao

    2018-01-01

    Full Text Available Cyanobacterial NDH-1 interacts with photosystem I (PSI to form an NDH-1-PSI supercomplex. Here, we observed that absence of NDH-1 had little, if any, effect on the functional fractions of PSI under growth conditions, but significantly reduced the functional fractions of PSI when cells of Synechocystis sp. strain PCC 6803 were moved to conditions of multiple stresses. The significant reduction in NDH-1-dependent functional fraction of PSI was initiated after PSII activity was impaired. This finding is consistent with our observation that the functional fraction of PSI under growth conditions was rapidly and significantly decreased with increasing concentrations of DCMU, which rapidly and significantly suppressed PSII activity by blocking the transfer of electrons from QA to QB in the PSII reaction center. Furthermore, absence of NDH-1 resulted in the PSI limitation at the functionality of PSI itself but not its donor-side and acceptor-side under conditions of multiple stresses. This was supported by the result of a significant destabilization of the PSI complex in the absence of NDH-1 but the presence of multiple stresses. Based on the above results, we propose that NDH-1 is important for PSI function of Synechocystis sp. strain PCC 6803 mainly via maintaining stabilization of PSI under conditions of environmental stresses.

  16. The gamma-aminobutyric acid shunt contributes to closing the tricarboxylic acid cycle in Synechocystis sp PCC 6803

    Energy Technology Data Exchange (ETDEWEB)

    Xiong, W; Brune, D; Vermaas, WFJ

    2014-07-16

    A traditional 2-oxoglutarate dehydrogenase complex is missing in the cyanobacterial tricarboxylic acid cycle. To determine pathways that convert 2-oxoglutarate into succinate in the cyanobacterium Synechocystis sp. PCC 6803, a series of mutant strains, Delta sll1981, Delta slr0370, Delta slr1022 and combinations thereof, deficient in 2-oxoglutarate decarboxylase (Sll1981), succinate semialdehyde dehydrogenase (Slr0370), and/or in gamma-aminobutyrate metabolism (Slr1022) were constructed. Like in Pseudomonas aeruginosa, N-acetylornithine aminotransferase, encoded by slr1022, was shown to also function as gamma-aminobutyrate aminotransferase, catalysing gamma-aminobutyrate conversion to succinic semialdehyde. As succinic semialdehyde dehydrogenase converts succinic semialdehyde to succinate, an intact gamma-aminobutyrate shunt is present in Synechocystis. The Delta sll1981 strain, lacking 2-oxoglutarate decarboxylase, exhibited a succinate level that was 60% of that in wild type. However, the succinate level in the Delta slr1022 and Delta slr0370 strains and the Delta sll1981/Delta slr1022 and Delta sll1981/Delta slr0370 double mutants was reduced to 20-40% of that in wild type, suggesting that the gamma-aminobutyrate shunt has a larger impact on metabolite flux to succinate than the pathway via 2-oxoglutarate decarboxylase. C-13-stable isotope analysis indicated that the gamma-aminobutyrate shunt catalysed conversion of glutamate to succinate. Independent of the 2-oxoglutarate decarboxylase bypass, the gamma-aminobutyrate shunt is a major contributor to flux from 2-oxoglutarate and glutamate to succinate in Synechocystis sp. PCC 6803.

  17. 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.

  18. The Synechocystis sp. PCC6803 Sfp-type phosphopantetheinyl transferase does not possess characteristic broad-range activity.

    Science.gov (United States)

    Roberts, Alexandra A; Copp, Janine N; Marahiel, Mohamed A; Neilan, Brett A

    2009-07-20

    The cyanobacterium Synechocystis sp. PCC6803 harbours one phosphopantetheinyl transferase (PPTase), Sppt. Protein modelling supported previous bioinformatics analyses, which suggested that Sppt is a Sfp-type PPTase with the potential to phosphopantetheinylate a broad range of carrier proteins from both primary and secondary metabolism. However, no natural products are synthesised by this species, which raises interesting evolutionary and functional questions. Phosphopantetheinylation assays and kinetic data demonstrate that Sppt was able to activate its cognate fatty acid synthesis carrier protein, SACP, but was unable to effectively activate various cyanobacterial carrier proteins from secondary metabolism or glycolipid biosynthesis pathways. To our knowledge, this is the first example of a PPTase with a Sfp-type structure, but with activity more closely resembling AcpS-type enzymes. The broad-range PPTase from Nodularia spumigena NSOR10 was introduced into Synechocystis sp. PCC6803 and was shown to activate a noncognate carrier protein, in vivo. This engineered strain could provide a future biotechnological platform for the heterologous expression of cyanobacterial biosynthetic gene clusters.

  19. Cytochrome c(6B) of Synechococcus sp. WH 8102--crystal structure and basic properties of novel c(6)-like family representative.

    Science.gov (United States)

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

    2014-01-24

    Cytochromes c are soluble electron carriers of relatively low molecular weight, containing single heme moiety. In cyanobacteria cytochrome c6 participates in electron transfer from cytochrome b6f complex to photosystem I. Recent phylogenetic analysis revealed the existence of a few families of proteins homologous to the previously mentioned. Cytochrome c6A from Arabidopsis thaliana was identified as a protein responsible for disulfide bond formation in response to intracellular redox state changes and c550 is well known element of photosystem II. However, function of cytochromes marked as c6B, c6C and cM 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 c6B 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 c6, 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 c6B has yet to be determined its properties probably exclude the participation of this protein in electron trafficking between b6f complex and photosystem I. Copyright © 2013 Elsevier Inc. All rights reserved.

  20. Effect of Different Broad Waveband Lights on Membrane Lipids of a Cyanobacterium, Synechococcus sp., as Determined by UPLC-QToF-MS and Vibrational Spectroscopy

    Directory of Open Access Journals (Sweden)

    Olimpio Montero

    2016-05-01

    Full Text Available Differential profile of membrane lipids and pigments of a Synechococcus sp. cyanobacterial strain cells exposed to blue, green, red and white light are determined by means of liquid chromatography and mass spectrometry or diode array detection. Raman and ATR-IR spectra of intact cells under the diverse light wavebands are also reported. Blue light cells exhibited an increased content of photosynthetic pigments as well as specific species of membrane glycerolipids as compared to cells exposed to other wavebands. The A630/A680 ratio indicated an increased content of phycobilisomes (PBS in the blue light-exposed cells. Some differences in the protein conformation between the four light waveband-exposed cells were deduced from the variable absorbance at specific wavenumbers in the FT-Raman and ATR-FTIR spectra, in particular bands assigned to amide I and amide II. Bands from 1180 to 950 cm−1 in the ATR-FTIR spectrum suggest degraded outer membrane polysaccharide in the blue light-exposed cells.

  1. The PsaE subunit of photosystem I prevents light-induced formation of reduced oxygen species in the cyanobacterium Synechocystis sp. PCC 6803

    NARCIS (Netherlands)

    Jeanjean, R.; Latifi, A.; Matthijs, H.C.P.; Havaux, M.

    2008-01-01

    The PsaE protein is located at the reducing side of photosystem I (PSI) and is involved in docking the soluble electron acceptors, particularly ferredoxin. However, deletion of the psaE gene in the cyanobacterium Synechocystis sp. strain PCC 6803 inhibited neither photoautotrophic growth, nor in

  2. 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

  3. Construction of a stepwise gene integration system by transient expression of actinophage R4 integrase in cyanobacterium Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Miura, Takamasa; Nishizawa, Akito; Nishizawa, Tomoyasu; Asayama, Munehiko; Takahashi, Hideo; Shirai, Makoto

    2014-08-01

    The integrase of actinophage R4, which belongs to the large serine-recombinase family, catalyzes site-specific recombination between two distinct attachment site sequences of the phage (attP) and actinomycete Streptomyces parvulus 2297 chromosome (attB). We previously reported that R4 integrase (Sre) catalyzed site-specific recombination both in vivo and in vitro. In the present study, a Sre-based system was developed for the stepwise site-specific integration of multiple genes into the chromosome of cyanobacterium Synechocystis sp. PCC 6803 (hereafter PCC 6803). A transgene-integrated plasmid with two attP sites and a non-replicative sre-containing plasmid were co-introduced into attB-inserted PCC 6803 cells. The transiently expressed Sre catalyzed highly efficient site-specific integration between one of the two attP sites on the integration plasmid and the attB site on the chromosome of PCC 6803. A second transgene-integrated plasmid with an attB site was integrated into the residual attP site on the chromosome by repeating site-specific recombination. The transformation frequencies (%) of the first and second integrations were approximately 5.1 × 10(-5) and 8.2 × 10(-5), respectively. Furthermore, the expression of two transgenes was detected. This study is the first to apply the multiple gene site-specific integration system based on R4 integrase to cyanobacteria.

  4. A photosystem 1 psaFJ-null mutant of the cyanobacterium Synechocystis PCC 6803 expresses the isiAB operon under iron replete conditions

    NARCIS (Netherlands)

    Jeanjean, Robert; Zuther, Ellen; Yeremenko, Nataliya; Havaux, Michel; Matthijs, Hans C. P.; Hagemann, Martin

    2003-01-01

    A psaFJ-null mutant of Synechocystis sp. strain PCC 6803 was characterised. As opposed to similar mutants in chloroplasts of green algae, electron transfer from plastocyanin to photosystem 1 was not affected. Instead, a restraint in full chain photosynthetic electron transfer was correlated to

  5. Biotic factors in induced defence revisited: cell aggregate formation in the toxic cyanobacterium Microcystis aeruginosa PCC 7806 is triggered by spent Daphnia medium and disrupted cells

    NARCIS (Netherlands)

    Becker, S.

    2010-01-01

    Bioassays with the toxic cyanobacterium Microcystis aeruginosa PCC 7806, its non-toxic mutant ΔmcyB, and Daphnia magna as grazer were used to evaluate biotic factors in induced defence, in particular cyanobacterial and grazer-released info-chemicals. Three main questions were addressed in this

  6. Forced symbiosis between Synechocystis spp. PCC 6803 and apo-symbiotic Paramecium bursaria as an experimental model for evolutionary emergence of primitive photosynthetic eukaryotes.

    Science.gov (United States)

    Ohkawa, Hiroshi; Hashimoto, Naoko; Furukawa, Shunsuke; Kadono, Takashi; Kawano, Tomonori

    2011-06-01

    Single-cell green paramecia (Paramecium bursaria) is a swimming vehicle that carries several hundred cells of endo-symbiotic green algae. Here, a novel model for endo-symbiosis, prepared by introducing and maintaining the cells of cyanobacterium (Synechocystis spp. PCC 6803) in the apo-symbiotic cells of P. bursaria is described.

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

    Science.gov (United States)

    Holmqvist, Marie; Lindberg, Pia; Agervald, Asa; Stensjö, Karin; Lindblad, Peter

    2011-06-14

    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. 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. 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 the expression patterns of hup

  8. Disentangling resting-state BOLD variability and PCC functional connectivity in 22q11.2 deletion syndrome.

    Science.gov (United States)

    Zöller, Daniela; Schaer, Marie; Scariati, Elisa; Padula, Maria Carmela; Eliez, Stephan; Van De Ville, Dimitri

    2017-04-01

    Although often ignored in fMRI studies, moment-to-moment variability of blood oxygenation level dependent (BOLD) signals reveals important information about brain function. Indeed, higher brain signal variability has been associated with better cognitive performance in young adults compared to children and elderly adults. Functional connectivity, a very common approach in resting-state fMRI analysis, is scaled for variance. Thus, alterations might be confounded or driven by BOLD signal variance alterations. Chromosome 22q11.2 deletion syndrome (22q11.2DS) is a neurodevelopmental disorder that is associated with a vast cognitive and clinical phenotype. To date, several resting-state fMRI studies reported altered functional connectivity in 22q11.2DS, however BOLD signal variance has not yet been analyzed. Here, we employed PLS correlation analysis to reveal multivariate patterns of diagnosis-related alterations and age-relationship throughout the cortex of 50 patients between 9 and 25 years old and 50 healthy controls in the same age range. To address how functional connectivity in the default mode network is influenced by BOLD signal fluctuations, we conducted the same analysis on seed-to-voxel connectivity of the posterior cingulate cortex (PCC) and compared resulting brain patterns. BOLD signal variance was lower mainly in regions of the default mode network and in the dorsolateral prefrontal cortex, but higher in large parts of the temporal lobes. In those regions, BOLD signal variance was correlated with age in healthy controls, but not in patients, suggesting deviant developmental trajectories from child- to adulthood. Positive connectivity of the PCC within the default mode network as well as negative connectivity towards the frontoparietal network were weaker in patients with 22q11.2DS. We furthermore showed that lower functional connectivity of the PCC was not driven by higher BOLD signal variability. Our results confirm the strong implication of BOLD

  9. Strain of Synechocystis PCC 6803 with Aberrant Assembly of Photosystem II Contains Tandem Duplication of a Large Chromosomal Region.

    Science.gov (United States)

    Tichý, Martin; Bečková, Martina; Kopečná, Jana; Noda, Judith; Sobotka, Roman; Komenda, Josef

    2016-01-01

    Cyanobacterium Synechocystis PCC 6803 represents a favored model organism for photosynthetic studies. Its easy transformability allowed construction of a vast number of Synechocystis mutants including many photosynthetically incompetent ones. However, it became clear that there is already a spectrum of Synechocystis "wild-type" substrains with apparently different phenotypes. Here, we analyzed organization of photosynthetic membrane complexes in a standard motile Pasteur collection strain termed PCC and two non-motile glucose-tolerant substrains (named here GT-P and GT-W) previously used as genetic backgrounds for construction of many photosynthetic site directed mutants. Although, both the GT-P and GT-W strains were derived from the same strain constructed and described by Williams in 1988, only GT-P was similar in pigmentation and in the compositions of Photosystem II (PSII) and Photosystem I (PSI) complexes to PCC. In contrast, GT-W contained much more carotenoids but significantly less chlorophyll (Chl), which was reflected by lower level of dimeric PSII and especially trimeric PSI. We found that GT-W was deficient in Chl biosynthesis and contained unusually high level of unassembled D1-D2 reaction center, CP47 and especially CP43. Another specific feature of GT-W was a several fold increase in the level of the Ycf39-Hlip complex previously postulated to participate in the recycling of Chl molecules. Genome re-sequencing revealed that the phenotype of GT-W is related to the tandem duplication of a large region of the chromosome that contains 100 genes including ones encoding D1, Psb28, and other PSII-related proteins as well as Mg-protoporphyrin methylester cyclase (Cycl). Interestingly, the duplication was completely eliminated after keeping GT-W cells on agar plates under photoautotrophic conditions for several months. The GT-W strain without a duplication showed no obvious defects in PSII assembly and resembled the GT-P substrain. Although, we do not exactly

  10. 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

  11. Transgenic expression of delta-6 and delta-15 fatty acid desaturases enhances omega-3 polyunsaturated fatty acid accumulation in Synechocystis sp. PCC6803.

    Science.gov (United States)

    Chen, Gao; Qu, Shujie; Wang, Qiang; Bian, Fei; Peng, Zhenying; Zhang, Yan; Ge, Haitao; Yu, Jinhui; Xuan, Ning; Bi, Yuping; He, Qingfang

    2014-03-01

    Polyunsaturated fatty acids (PUFAs), which contain two or more double bonds in their backbone, are the focus of intensive global research, because of their nutritional value, medicinal applications, and potential use as biofuel. However, the ability to produce these economically important compounds is limited, because it is both expensive and technically challenging to separate omega-3 polyunsaturated fatty acids (ω-3 PUFAs) from natural oils. Although the biosynthetic pathways of some plant and microalgal ω-3 PUFAs have been deciphered, current understanding of the correlation between fatty acid desaturase content and fatty acid synthesis in Synechocystis sp. PCC6803 is incomplete. We constructed a series of homologous vectors for the endogenous and exogenous expression of Δ6 and Δ15 fatty acid desaturases under the control of the photosynthesis psbA2 promoter in transgenic Synechocystis sp. PCC6803. We generated six homologous recombinants, harboring various fatty acid desaturase genes from Synechocystis sp. PCC6803, Gibberella fujikuroi and Mortierella alpina. These lines produced up to 8.9 mg/l of α-linolenic acid (ALA) and 4.1 mg/l of stearidonic acid (SDA), which are more than six times the corresponding wild-type levels, at 20°C and 30°C. Thus, transgenic expression of Δ6 and Δ15 fatty acid desaturases enhances the accumulation of specific ω-3 PUFAs in Synechocystis sp. PCC6803. In the blue-green alga Synechocystis sp. PCC6803, overexpression of endogenous and exogenous genes encoding PUFA desaturases markedly increased accumulation of ALA and SDA and decreased accumulation of linoleic acid and γ-linolenic acid. This study lays the foundation for increasing the fatty acid content of cyanobacteria and, ultimately, for producing nutritional and medicinal products with high levels of essential ω-3 PUFAs.

  12. Increased bioplastic production with an RNA polymerase sigma factor SigE during nitrogen starvation in Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Osanai, Takashi; Numata, Keiji; Oikawa, Akira; Kuwahara, Ayuko; Iijima, Hiroko; Doi, Yoshiharu; Tanaka, Kan; Saito, Kazuki; Hirai, Masami Yokota

    2013-12-01

    Because cyanobacteria directly harvest CO2 and light energy, their carbon metabolism is important for both basic and applied sciences. Here, we show that overexpression of the sigma factor sigE in Synechocystis sp. PCC 6803 widely changes sugar catabolism and increases production of the biodegradable polyester polyhydroxybutyrate (PHB) during nitrogen starvation. sigE overexpression elevates the levels of proteins implicated in glycogen catabolism, the oxidative pentose phosphate pathway, and polyhydroxyalkanoate biosynthesis. PHB accumulation is enhanced by sigE overexpression under nitrogen-limited conditions, yet the molecular weights of PHBs synthesized by the parental glucose-tolerant and sigE overexpression strain are similar. Although gene expression induced by nitrogen starvation is changed and other metabolites (such as GDP-mannose and citrate) accumulate under sigE overexpression, genetic engineering of this sigma factor altered the metabolic pathway from glycogen to PHB during nitrogen starvation.

  13. Structural and biochemical characterization of MCAT from photosynthetic microorganism Synechocystis sp. PCC 6803 reveal its stepwise catalytic mechanism.

    Science.gov (United States)

    Liu, Yinghui; Feng, Yanbin; Wang, Yayue; Li, Xia; Cao, Xupeng; Xue, Song

    2015-02-13

    Malonyl-coenzyme A: acyl-carrier protein transacylase (MCAT) catalyzes the transfer of malonyl group from malonyl-CoA to the holo-acyl carrier protein (Holo-ACP), yielding malonyl-ACP. The overall reaction has been extensively studied in heterotrophic microorganisms, while its mechanism in photosynthetic autotrophs as well as the stepwise reaction information remains unclear. Here the 2.42 Å crystal structure of MCAT from photosynthetic microorganism Synechocystis sp. PCC 6803 is presented. It demonstrates that Arg113, Ser88 and His188 constitute catalytic triad. The second step involved ACP-MCAT-malonyl intermediate is speed-limited instead of the malonyl-CoA-MCAT intermediate in the first step. Therefore His87, Arg113 and Ser88 render different contributions for the two intermediates. Additionally, S88T mutant initializes the reaction by H87 deprotonating S88T which is different from the wild type. Copyright © 2015 Elsevier Inc. All rights reserved.

  14. 1H, 13C and 15N resonance assignments of the arsenate reductase from Synechocystis sp. strain PCC 6803.

    Science.gov (United States)

    Yu, Caifang; Xia, Bin; Jin, Changwen

    2011-04-01

    Arsenate reductases (ArsC) are a group of enzymes that play essential roles in biological arsenic detoxification pathways by catalyzing the intracellular reduction of arsenate to arsenite, which is subsequently extruded from the cells by specific transport systems. The ArsC protein from cyanobacterium Synechocystis sp. strain PCC 6803 (SynArsC) is related to the thioredoxin-dependent ArsC family, but uses the glutathione/glutaredoxin system for arsenate reduction. Therefore, it is classified to a novel thioredoxin/glutaredoxin hybrid arsenate reductase family. Herein we report the chemical shift assignments of (1)H, (13)C and (15)N atoms for the reduced form of SynArsC, which provides a starting point for further structural analysis and elucidation of its enzymatic mechanism.

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

    Directory of Open Access Journals (Sweden)

    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.

  16. 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

  17. Altering the Structure of Carbohydrate Storage Granules in the Cyanobacterium Synechocystis sp. Strain PCC 6803 through Branching-Enzyme Truncations

    Science.gov (United States)

    Welkie, David G.; Lee, Byung-Hoo

    2015-01-01

    ABSTRACT Carbohydrate storage is an important element of metabolism in cyanobacteria and in the chloroplasts of plants. Understanding how to manipulate the metabolism and storage of carbohydrate is also an important factor toward harnessing cyanobacteria for energy production. While most cyanobacteria produce glycogen, some have been found to accumulate polysaccharides in the form of water-insoluble α-glucan similar to amylopectin. Notably, this alternative form, termed “semi-amylopectin,” forms in cyanobacterial species harboring three branching-enzyme (BE) homologs, designated BE1, BE2, and BE3. In this study, mutagenesis of the branching genes found in Synechocystis sp. strain PCC 6803 was performed in order to characterize their possible impact on polysaccharide storage granule morphology. N-terminal truncations were made to the native BE gene of Synechocystis sp. PCC 6803. In addition, one of the two native debranching enzyme genes was replaced with a heterologous debranching enzyme gene from a semi-amylopectin-forming strain. Growth and glycogen content of mutant strains did not significantly differ from those of the wild type, and ultrastructure analysis revealed only slight changes to granule morphology. However, analysis of chain length distribution by anion-exchange chromatography revealed modest changes to the branched-chain length profile. The resulting glycogen shared structure characteristics similar to that of granules isolated from semi-amylopectin-producing strains. IMPORTANCE This study is the first to investigate the impact of branching-enzyme truncations on the structure of storage carbohydrates in cyanobacteria. The results of this study are an important contribution toward understanding the relationship between the enzymatic repertoire of a cyanobacterial species and the morphology of its storage carbohydrates. PMID:26668264

  18. 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

  19. Towards clarifying what distinguishes cyanobacteria able to resurrect after desiccation from those that cannot: The photosynthetic aspect.

    Science.gov (United States)

    Raanan, Hagai; Oren, Nadav; Treves, Haim; Keren, Nir; Ohad, Itzhak; Berkowicz, Simon M; Hagemann, Martin; Koch, Moriz; Shotland, Yoram; Kaplan, Aaron

    2016-06-01

    Organisms inhabiting biological soil crusts (BSCs) are able to cope with extreme environmental conditions including daily hydration/dehydration cycles, high irradiance and extreme temperatures. The photosynthetic machinery, potentially the main source of damaging reactive oxygen species during cessation of CO(2) fixation in desiccating cells, must be protected to avoid sustained photodamage. We compared certain photosynthetic parameters and the response to excess light of BCS-inhabiting, desiccation-tolerant cyanobacteria Leptolyngbya ohadii and Nostoc reinholdii with those observed in the "model" organisms Nostoc sp. PCC 7120, able to resurrect after mild desiccation, and Synechococcus elongatus PCC 7942 and Synechocystis sp. PCC 6803 that are unable to recover from dehydration. Desiccation-tolerant strains exhibited a transient decline in the photosynthetic rate at light intensities corresponding to the inflection point in the PI curve relating the O(2) evolution rate to light intensity. They also exhibited a faster and larger loss of variable fluorescence and profoundly faster Q(A)(-) re-oxidation rates after exposure to high illumination. Finally, a smaller difference was found in the temperature of maximal thermoluminescence signal in the absence or presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) than observed in "model" cyanobacteria. These parameters indicate specific functional differences of photosystem II (PSII) between desiccation tolerant and sensitive cyanobacteria. We propose that exposure to excess irradiation activates a non-radiative electron recombination route inside PSII that minimizes formation of damaging singlet oxygen in the desiccation-tolerant cyanobacteria and thereby reduces photodamage. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. 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.

  1. 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

  2. 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

    Directory of Open Access Journals (Sweden)

    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.

  3. 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.

  4. O desenvolvimento embrionário da Piapara, Leporinus elongatus (Pisces, Anostomidae, utilizando técnicas de histologia, microscopia eletrônica de varredura e imunológicas empregando marcadores ósseos

    Directory of Open Access Journals (Sweden)

    Erika Z. Sousa

    2014-12-01

    Full Text Available Resumo O desenvolvimento embrionário dos peixes é de grande importância para a piscicultura e na reintrodução de espécies ameaçadas de extinção em seus ambientes, e seu conhecimento constitui uma importante maneira para minimizar doenças e mortalidades dessas espécies. Com o auxílio de técnicas como a Microscopia Eletrônica de Varredura (MEV e a imuno-histoquimica para identificar proteínas ósseas, foi possível avaliar as fases de desenvolvimento com mais riqueza de detalhes, facilitando a compreensão de hábitos e da biologia da espécie. Neste trabalho pudemos observar a ontogenia e osteogênese da Piapara (Leporinus elongatus, desde a fecundação até a fase juvenil, sendo evidenciadas estruturas importantes como o tamanho do vitelo, essencial para a nutrição do embrião; o fechamento do blastóporo, evento principal da embriogênese, que indica as taxas de fertilização; a metamorfose, que indica a formação dos primeiros e principais órgãos do animal e a formação de sua estrutura óssea. As Proteínas Ósseas Morfogenéticas (BMP-2 e BMP-4, moléculas essenciais reguladoras no desenvolvimento embrionário e na formação óssea, foram observadas apenas no estádio larval até o período juvenil, não sendo evidenciadas nos estágios anteriores. Os resultados desse trabalho trouxeram novas informações quanto à biologia do desenvolvimento dessa espécie, que certamente poderão auxiliar no aprimoramento de técnicas reprodutivas visando uma melhora na sua produção seja para fins comerciais ou de repovoamento.

  5. Genome-wide analyses of the transcriptomes of salicylic acid-deficient versus wild-type plants uncover Pathogen and Circadian Controlled 1 (PCC1) as a regulator of flowering time in Arabidopsis.

    Science.gov (United States)

    Segarra, Silvia; Mir, Ricardo; Martínez, Cristina; León, José

    2010-01-01

    Salicylic acid (SA) has been characterized as an activator of pathogen-triggered resistance of plants. SA also regulates developmental processes such as thermogenesis in floral organs and stress-induced flowering. To deepen our knowledge of the mechanism underlying SA regulation of flowering time in Arabidopsis, we compared the transcriptomes of SA-deficient late flowering genotypes with wild-type plants. Down- or up-regulated genes in SA-deficient plants were screened for responsiveness to ultraviolet (UV)-C light, which accelerates flowering in Arabidopsis. Among them, only Pathogen and Circadian Controlled 1 (PCC1) was up-regulated by UV-C light through a SA-dependent process. Moreover, UV-C light-activated expression of PCC1 was also dependent on the flowering activator CONSTANS (CO). PCC1 gene has a circadian-regulated developmental pattern of expression with low transcript levels after germination that increased abruptly by day 10. RNAi plants with very low expression of PCC1 gene were late flowering, defective in UV-C light acceleration of flowering and contained FLOWERING LOCUS T (FT) transcript levels below 5% of that detected in wild-type plants. Although PCC1 seems to function between CO and FT in the photoperiod-dependent flowering pathway, transgenic plants overexpressing a Glucocorticoid Receptor (GR)-fused version of CO strongly activated FT but not PCC1 after dexamethasone treatment.

  6. Potential of Synechocystis PCC 6803 as a novel cyanobacterial chassis for heterologous expression of enzymes in the trans-resveratrol biosynthetic pathway.

    Science.gov (United States)

    Tantong, Supaluk; Incharoensakdi, Aran; Sirikantaramas, Supaart; Lindblad, Peter

    2016-05-01

    Selected model strains of phototrophic cyanobacteria have been genetically engineered for heterologous expression of numerous enzymes. In the present study, we initially explored the heterologous expression of enzymes involved in trans-resveratrol production, namely, the production of tyrosine ammonia-lyase, coumaroyl CoA-ligase, and stilbene synthase, in the unicellular cyanobacterium Synechocystis PCC 6803. Under the promoters Ptrc1Ocore and Ptrc1O, the respective genes were transcribed and translated into the corresponding soluble proteins at concentrations of 16-34 μg L(-1). The expression levels of these enzymes did not affect the growth rate of the cyanobacterial cells. Interestingly, coumaroyl CoA-ligase expression slightly increased the chlorophyll a content of the cells. Overall, our results suggest that the complete pathway of trans-resveratrol production can be engineered in Synechocystis PCC 6803. Copyright © 2016 Elsevier Inc. All rights reserved.

  7. Toxicities of four anti-neoplastic drugs and their binary mixtures tested on the green alga Pseudokirchneriella subcapitata and the cyanobacterium Synechococcus leopoliensis.

    Science.gov (United States)

    Brezovšek, Polona; Eleršek, Tina; Filipič, Metka

    2014-04-01

    The residues of anti-neoplastic drugs are new and emerging pollutants in aquatic environments. This is not only because of their increasing use, but also because due to their mechanisms of action, they belong to a group of particularly dangerous compounds. However, information on their ecotoxicological properties is very limited. We tested the toxicities of four anti-neoplastic drugs with different mechanisms of action (5-fluorouracil [5-FU], cisplatin [CDDP], etoposide [ET], and imatinib mesylate [IM]), and some of their binary mixtures, against two phytoplankton species: the alga Pseudokirchneriella subcapitata, and the cyanobacterium Synechococcus leopoliensis. These four drugs showed different toxic potential, and the two species examined also showed differences in their susceptibilities towards the tested drugs and their mixtures. With P. subcapitata, the most toxic of these drugs was 5-FU (EC50, 0.13 mg/L), followed by CDDP (EC50, 1.52 mg/L), IM (EC50, 2.29 mg/L), and the least toxic, ET (EC50, 30.43 mg/L). With S. leopoliensis, the most toxic was CDDP (EC50, 0.67 mg/L), followed by 5-FU (EC50, 1.20 mg/L) and IM (EC50, 5.36 mg/L), while ET was not toxic up to 351 mg/L. The toxicities of the binary mixtures tested (5-FU + CDDP, 5-FU + IM, CDDP + ET) were predicted by the concepts of 'concentration addition' and 'independent action', and are compared to the experimentally determined toxicities. The measured toxicity of 5-FU + CDDP with P. subcapitata and S. leopoliensis was higher than that predicted, while the measured toxicity of CDDP + ET with both species was lower than that predicted. The measured toxicity of 5-FU + IM with P. subcapitata was higher, and with S. leopoliensis was lower, than that predicted. These data show that these mixtures can have compound-specific and species-specific synergistic or antagonistic effects, and they suggest that single compound toxicity data are not sufficient for the prediction of the aquatic

  8. 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

  9. The Affect of the Space Environment on the Survival of Halorubrum Chaoviator and Synechococcus (Nageli): Data from the Space Experiment OSMO on EXPOSE-R

    Science.gov (United States)

    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

  10. Determination of carbon-to-nitrogen ratio in the filamentous and heterocystous cyanobacterium Anabaena sp. PCC 7120 with single-cell soft X-ray imaging

    Science.gov (United States)

    Teramoto, T.; Yoshimura, M.; Azai, C.; Terauchi, K.; Ohta, T.

    2017-06-01

    Vegetative cells and heterocysts in the filamentous cyanobacterium Anabaena sp. PCC 7120 were observed by soft X-ray microscopy. Carbon-to-nitrogen (C/N) ratio of each cell was estimated by the difference of the absorbance of the images below and above the nitrogen K-edge absorption. It was revealed that the C/N ratios in vegetative cells and heterocysts are 4.54 and 2.46, respectively.

  11. Accumulation of the D2 Protein Is a Key Regulatory Step for Assembly of the Photosystem II Reaction Center Complex in Synechocystis PCC 6803

    Czech Academy of Sciences Publication Activity Database

    Komenda, Josef; Reisinger, V.; Muller, B. Ch.; Dobáková, Marika; Granvogl, B.; Eichacker, L. A.

    2004-01-01

    Roč. 279, č. 47 (2004), s. 48620-48629 ISSN 0021-9258 R&D Projects: GA MŠk LN00A141 Grant - others:GA Deutsche Forschungsgemeinschaft Grants(DE) SFB TR1; GA Deutsche Forschungsgemeinschaft Grants(DE) SFB 594 Institutional research plan: CEZ:AV0Z5020903 Keywords : synechocystis PCC 6803 * D2 protein * photosystem PSII Subject RIV: EE - Microbiology, Virology Impact factor: 6.355, year: 2004

  12. The Psb27 Assembly Factor Binds to the CP43 Complex of Photosystem II in the Cyanobacterium Synechocystis sp PCC 6803

    Czech Academy of Sciences Publication Activity Database

    Komenda, Josef; Knoppová, Jana; Kopečná, Jana; Sobotka, Roman; Halada, Petr; Yu, J.; Nickelsen, J.; Boehm, M.; Nixon, P. J.

    2012-01-01

    Roč. 158, č. 1 (2012), s. 476-486 ISSN 0032-0889 R&D Projects: GA ČR(CZ) GAP501/11/0377; GA ČR GAP501/10/1000; GA MŠk LC07017 Institutional research plan: CEZ:AV0Z50200510 Keywords : MEMBRANE-PROTEIN COMPLEXES * SP PCC-6803 * D1 PROTEIN Subject RIV: EE - Microbiology, Virology Impact factor: 6.555, year: 2012

  13. The FtsH protease slr0228 is important for quality control of photosystem II in the thylakoid membrane of Synechocystis sp. PCC 6803

    Czech Academy of Sciences Publication Activity Database

    Komenda, Josef; Barker, M.; Kuviková, Stanislava; de Vries, R.; Mullineaux, C.W.; Tichý, Martin; Nixon, P.

    2006-01-01

    Roč. 281, č. 2 (2006), s. 1145-1151 ISSN 0021-9258 R&D Projects: GA ČR GA203/04/0800; GA MŠk LN00A141 Institutional research plan: CEZ:AV0Z50200510 Keywords : photosystem II * synechocystis sp. pcc 6803 * ftsh protease Subject RIV: EE - Microbiology, Virology Impact factor: 5.808, year: 2006

  14. Subcellular localization and clues for the function of the HetN factor influencing heterocyst distribution in Anabaena sp. strain PCC 7120

    OpenAIRE

    Corrales-Guerrero, Laura; Mariscal, Vicente; Nürnberg, Dennis J.; Elhai, Jeff; Mullineaux, Conrad W.; Flores, Enrique; Herrero, Antonia

    2014-01-01

    In the filamentous cyanobacterium Anabaena sp. strain PCC 7120, heterocysts are formed in the absence of combined nitrogen, following a specific distribution pattern along the filament. The PatS and HetN factors contribute to the heterocyst pattern by inhibiting the formation of consecutive heterocysts. Thus, inactivation of any of these factors produces the multiple contiguous heterocyst (Mch) phenotype. Upon N stepdown, a HetN protein with its C terminus fused to a superfolder version of gr...

  15. 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

  16. Biodosimetry estimation using the ratio of the longest:shortest length in the premature chromosome condensation (PCC) method applying autocapture and automatic image analysis.

    Science.gov (United States)

    González, Jorge E; Romero, Ivonne; Gregoire, Eric; Martin, Cécile; Lamadrid, Ana I; Voisin, Philippe; Barquinero, Joan-Francesc; García, Omar

    2014-09-01

    The combination of automatic image acquisition and automatic image analysis of premature chromosome condensation (PCC) spreads was tested as a rapid biodosimeter protocol. Human peripheral lymphocytes were irradiated with (60)Co gamma rays in a single dose of between 1 and 20 Gy, stimulated with phytohaemaglutinin and incubated for 48 h, division blocked with Colcemid, and PCC-induced by Calyculin A. Images of chromosome spreads were captured and analysed automatically by combining the Metafer 4 and CellProfiler platforms. Automatic measurement of chromosome lengths allows the calculation of the length ratio (LR) of the longest and the shortest piece that can be used for dose estimation since this ratio is correlated with ionizing radiation dose. The LR of the longest and the shortest chromosome pieces showed the best goodness-of-fit to a linear model in the dose interval tested. The application of the automatic analysis increases the potential use of the PCC method for triage in the event of massive radiation causalities. © The Author 2014. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology.

  17. N-Terminal Lipid Modification Is Required for the Stable Accumulation of CyanoQ in Synechocystis sp. PCC 6803.

    Directory of Open Access Journals (Sweden)

    Andrea D Juneau

    Full Text Available The CyanoQ protein has been demonstrated to be a component of cyanobacterial Photosystem II (PS II, but there exist a number of outstanding questions concerning its physical association with the complex. CyanoQ is a lipoprotein; upon cleavage of its transit peptide by Signal Peptidase II, which targets delivery of the mature protein to the thylakoid lumenal space, the N-terminal cysteinyl residue is lipid-modified. This modification appears to tether this otherwise soluble component to the thylakoid membrane. To probe the functional significance of the lipid anchor, mutants of the CyanoQ protein have been generated in Synechocystis sp. PCC 6803 to eliminate the N-terminal cysteinyl residue, preventing lipid modification. Substitution of the N-terminal cysteinyl residue with serine (Q-C22S resulted in a decrease in the amount of detectable CyanoQ protein to 17% that of the wild-type protein. Moreover, the physical properties of the accumulated Q-C22S protein were consistent with altered processing of the CyanoQ precursor. The Q-C22S protein was shifted to a higher apparent molecular mass and partitioned in the hydrophobic phase in TX-114 phase-partitioning experiments. These results suggest that the hydrophobic N-terminal 22 amino acids were not properly cleaved by a signal peptidase. Substitution of the entire CyanoQ transit peptide with the transit peptide of the soluble lumenal protein PsbO yielded the Q-SS mutant and resulted in no detectable accumulation of the modified CyanoQ protein. Finally, the CyanoQ protein was present at normal amounts in the PS II mutant strains ΔpsbB and ΔpsbO, indicating that an association with PS II was not a prerequisite for stable CyanoQ accumulation. Together these results indicate that CyanoQ accumulation in Synechocystis sp. PCC 6803 depends on the presence of the N-terminal lipid anchor, but not on the association of CyanoQ with the PS II complex.

  18. RNA-seq profiling reveals novel target genes of LexA in the cyanobacterium Synechocystis sp. PCC 6803

    Directory of Open Access Journals (Sweden)

    Ayumi eKizawa

    2016-02-01

    Full Text Available LexA is a well-established transcriptional repressor of SOS genes induced by DNA damage in E. coli and other bacterial species. However, LexA in the cyanobacterium Synechocystis sp. PCC 6803 has been suggested not to be involved in SOS response. In this study, we performed RNA-seq analysis of the wild-type strain and the lexA-disrupted mutant to obtain the comprehensive view of LexA-regulated genes in Synechocystis. Disruption of lexA positively or negatively affected expression of genes related to various cellular functions such as phototactic motility, accumulation of the major compatible solute glucosylglycerol and subunits of bidirectional hydrogenase, photosystem I and phycobilisome complexes. We also observed increase in the expression level of genes related to iron and manganese uptake in the mutant at the later stage of cultivation. However, none of the genes related to DNA metabolism were affected by disruption of lexA. DNA gel mobility shift assay using the recombinant LexA protein suggested that LexA binds to the upstream region of pilA7, pilA9, ggpS and slr1670 to directly regulate their expression, but changes in the expression level of photosystem I genes by disruption of lexA is likely a secondary effect.

  19. Reconstruction and comparison of the metabolic potential of cyanobacteria Cyanothece sp. ATCC 51142 and Synechocystis sp. PCC 6803.

    Directory of Open Access Journals (Sweden)

    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.

  20. In silico analysis and experimental validation of lipoprotein and novel Tat signal peptides processing in Anabaena sp. PCC7120.

    Science.gov (United States)

    Kumari, Sonika; Chaurasia, Akhilesh Kumar

    2015-12-01

    Signal peptide (SP) plays a pivotal role in protein translocation. Lipoprotein- and twin arginine translocase (Tat) dependent signal peptides were studied in All3087, a homolog of competence protein of Synechocystis PCC6803 and in two putative alkaline phosphatases (ALPs, Alr2234 and Alr4976), respectively. In silico analysis of All3087 is shown to possess the characteristics feature of competence proteins such as helix-hairpin-helix, N and C-terminal HKD endonuclease domain, calcium binding domain and N-terminal lipoprotein signal peptide. The SP recognition-cleavage site in All3087 was predicted (AIA-AC) using SignalP while further in-depth analysis using Pred-Lipo and WebLogo analysis for consensus sequence showed it as IAA-C. Activities of putative ALPs were confirmed by heterologous overexpression, activity assessment and zymogram analysis. ALP activity in Anabaena remains cell bound in log-phase, but during late log/stationary phase, an enhanced ALP activity was detected in extracellular milieu. The enhancement of ALP activity during stationary phase was not only due to inorganic phosphate limitation but also contributed by the presence of novel bipartite Tat-SP. The Tat signal transported the folded active ALPs to the membrane, followed by anchoring into the membrane and successive cleavage enabling transportation of the ALPs to the extracellular milieu, because of bipartite architecture and processing of transit Tat-SP.

  1. Comparison of the terrestrial cyanobacterium Leptolyngbya sp. NIES-2104 and the freshwater Leptolyngbya boryana PCC 6306 genomes

    Science.gov (United States)

    Shimura, Yohei; Hirose, Yuu; Misawa, Naomi; Osana, Yasunori; Katoh, Hiroshi; Yamaguchi, Haruyo; Kawachi, Masanobu

    2015-01-01

    The cyanobacterial genus Leptolyngbya is widely distributed throughout terrestrial environments and freshwater. Because environmental factors, such as oxygen level, available water content, and light intensity, vary between soil surface and water bodies, terrestrial Leptolyngbya should have genomic differences with freshwater species to adapt to a land habitat. To study the genomic features of Leptolyngbya species, we determined the complete genome sequence of the terrestrial strain Leptolyngbya sp. NIES-2104 and compared it with that of the near-complete sequence of the freshwater Leptolyngbya boryana PCC 6306. The greatest differences between these two strains were the presence or absence of a nitrogen fixation gene cluster for anaerobic nitrogen fixation and several genes for tetrapyrrole synthesis, which can operate under micro-oxic conditions. These differences might reflect differences in oxygen levels where these strains live. Both strains have the genes for trehalose biosynthesis, but only Leptolyngbya sp. NIES-2104 has genetic capacity to produce a mycosporine-like amino acid, mycosporine-glycine. Mycosporine-glycine has an antioxidant action, which may contribute to adaptation to terrestrial conditions. These features of the genomes yielded additional insights into the classification and physiological characteristics of these strains. PMID:26494835

  2. Physiological Regulation of Isocitrate Dehydrogenase and the Role of 2-Oxoglutarate in Prochlorococcus sp. Strain PCC 9511

    Science.gov (United States)

    Diez, Jesús; Gómez-Baena, Guadalupe; Rangel-Zúñiga, Oriol Alberto; García-Fernández, José Manuel

    2014-01-01

    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. PMID:25061751

  3. Amino Acid Transporters and Release of Hydrophobic Amino Acids in the Heterocyst-Forming Cyanobacterium Anabaena sp. Strain PCC 7120

    Directory of Open Access Journals (Sweden)

    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.

  4. 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.

  5. Metabolic engineering of the pentose phosphate pathway for enhanced limonene production in the cyanobacterium Synechocysti s sp. PCC 6803.

    Science.gov (United States)

    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.

  6. Regulation of the scp Genes in the Cyanobacterium Synechocystis sp. PCC 6803—What is New?

    Directory of Open Access Journals (Sweden)

    Otilia Cheregi

    2015-08-01

    Full Text Available In the cyanobacterium Synechocystis sp. PCC 6803 there are five genes encoding small CAB-like (SCP proteins, which have been shown to be up-regulated under stress. Analyses of the promoter sequences of the scp genes revealed the existence of an NtcA binding motif in two scp genes, scpB and scpE. Binding of NtcA, the key transcriptional regulator during nitrogen stress, to the promoter regions was shown by electrophoretic mobility shift assay. The metabolite 2-oxoglutarate did not increase the affinity of NtcA for binding to the promoters of scpB and scpE. A second motif, the HIP1 palindrome 5ʹ GGCGATCGCC 3ʹ, was detected in the upstream regions of scpB and scpC. The transcription factor encoded by sll1130 has been suggested to recognize this motif to regulate heat-responsive genes. Our data suggest that HIP1 is not a regulatory element within the scp genes. Further, the presence of the high light regulatory (HLR1 motif was confirmed in scpB-E, in accordance to their induced transcriptions in cells exposed to high light. The HLR1 motif was newly discovered in eight additional genes.

  7. Alcohol dehydrogenase AdhA plays a role in ethanol tolerance in model cyanobacterium Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Vidal, Rebeca

    2017-04-01

    The protein AdhA from the cyanobacterium Synechocystis sp. PCC 6803 (hereafter Synechocystis) has been previously reported to show alcohol dehydrogenase activity towards ethanol and both NAD and NADP. This protein is currently being used in genetically modified strains of Synechocystis capable of synthesizing ethanol showing the highest ethanol productivities. In the present work, mutant strains of Synechocystis lacking AdhA have been constructed and tested for tolerance to ethanol. The lack of AdhA in the wild-type strain reduces survival to externally added ethanol at lethal concentration of 4% (v/v). On the other hand, the lack of AdhA in an ethanologenic strain diminishes tolerance of cells to internally produced ethanol. It is also shown that light-activated heterotrophic growth (LAHG) of the wild-type strain is impaired in the mutant strain lacking AdhA (∆adhA strain). Photoautotrophic, mixotrophic, and photoheterotrophic growth are not affected in the mutant strain. Based on phenotypic characterization of ∆adhA mutants, the possible physiological function of AdhA in Synechocystis is discussed.

  8. A systems biology approach to reconcile metabolic network models with application to Synechocystis sp. PCC 6803 for biofuel production.

    Science.gov (United States)

    Mohammadi, Reza; Fallah-Mehrabadi, Jalil; Bidkhori, Gholamreza; Zahiri, Javad; Javad Niroomand, Mohammad; Masoudi-Nejad, Ali

    2016-07-19

    Production of biofuels has been one of the promising efforts in biotechnology in the past few decades. The perspective of these efforts can be reduction of increasing demands for fossil fuels and consequently reducing environmental pollution. Nonetheless, most previous approaches did not succeed in obviating many big challenges in this way. In recent years systems biology with the help of microorganisms has been trying to overcome these challenges. Unicellular cyanobacteria are widespread phototrophic microorganisms that have capabilities such as consuming solar energy and atmospheric carbon dioxide for growth and thus can be a suitable chassis for the production of valuable organic materials such as biofuels. For the ultimate use of metabolic potential of cyanobacteria, it is necessary to understand the reactions that are taking place inside the metabolic network of these microorganisms. In this study, we developed a Java tool to reconstruct an integrated metabolic network of a cyanobacterium (Synechocystis sp. PCC 6803). We merged three existing reconstructed metabolic networks of this microorganism. Then, after modeling for biofuel production, the results from flux balance analysis (FBA) disclosed an increased yield in biofuel production for ethanol, isobutanol, 3-methyl-1-butanol, 2-methyl-1-butanol, and propanol. The numbers of blocked reactions were also decreased for 2-methyl-1-butanol production. In addition, coverage of the metabolic network in terms of the number of metabolites and reactions was increased in the new obtained model.

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

    Directory of Open Access Journals (Sweden)

    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.

  10. NblA1/A2-Dependent Homeostasis of Amino Acid Pools during Nitrogen Starvation in Synechocystis sp. PCC 6803.

    Science.gov (United States)

    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.

  11. NblA1/A2-Dependent Homeostasis of Amino Acid Pools during Nitrogen Starvation in Synechocystis sp. PCC 6803

    Directory of Open Access Journals (Sweden)

    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.

  12. Enhanced accumulation of glycogen, lipids and polyhydroxybutyrate under optimal nutrients and light intensities in the cyanobacterium Synechocystis sp. PCC 6803.

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  14. 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

  15. 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...... 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......, the approach also allowed identification and quantification of departures from additivity (interactions) among analytes. The biosensor was found to respond in a near additive way to heavy metal mixtures except when Hg, Co and Ag were present, in which case strong interactions occurred. The method is a useful...

  16. 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

  17. 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.

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

    Directory of Open Access Journals (Sweden)

    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.

  19. Evanescent cultivation of photosynthetic bacteria on thin waveguides

    Science.gov (United States)

    Pierobon, S. C.; Ooms, M. D.; Sinton, D.

    2014-04-01

    Waveguides with thicknesses similar to biofilms (10-100 µm) provide an opportunity to improve the bioenergy density of biofilm photobioreactors, avoiding the fundamental light- and mass-transport productivity limitations of planktonic photobioreactors. This report investigates the biofilm growth of a mutant of Synechococcus elongatus (PCC 7942) in evanescent light fields that can be scaled over large planar areas. In this study, areas of 7.2 cm2 are illuminated via frustrated total internal reflections on planar waveguides. The resulting photosynthetic biofilm growth showed resilience to surface intensities exceeding photosynthetic limits and a more uniform cell density distribution (1.0 ± 0.3 × 109 mL-1) than predicted from surface light distribution profiles. These results indicate potential for larger area biofilms using the uniform lighting conditions identified. The combination of evanescent illumination with biofilms indicates a modular reactor cell density on the order of 108 mL-1, representing a two orders of magnitude improvement over current facility architectures, with significant potential for further improvement through denser biofilms.

  20. 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.

  1. 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.

  2. Sucrose secreted by the engineered cyanobacterium and its fermentability

    Science.gov (United States)

    Duan, Yangkai; Luo, Quan; Liang, Feiyan; Lu, Xuefeng

    2016-10-01

    The unicellular cyanobacterium, Synechococcus elongatus PCC 7942 (Syn7942), synthesizes sucrose as the only compatible solute under salt stress. A series of engineered Syn7942 strains for sucrose production were constructed. The overexpression of the native sps (encoding a natively fused protein of sucrose phosphate synthase SPS and sucrose phosphate phosphatase SPP) in Syn7942 wild type caused a 93% improvement of sucrose productivity. The strain FL130 co-overexpressing sps and cscB (encoding a sucrose transporter) exhibited a 74% higher extracellular sucrose production than that overexpressing cscB only. Both results showed the significant improvement of sucrose productivity by the double functional protein SPS-SPP. Afterwards, FL130 was cultivated under a modified condition, and the cell-free culture medium containing 1.5 g L-1 sucrose was pre-treated with an acid hydrolysis technique. Cultivated with the neutralized hydrolysates as the starting media, two widely used microorganisms, Escherichia coli and Saccharomyces cerevisiae, showed a comparable growth with that in the control media supplemented with glucose. These results clearly demonstrated that the cell-free culture of sucrose-secreting cyanobacteria can be applied as starting media in microbial cultivation.

  3. 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.

  4. 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.

  5. 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

  6. The molecular dimension of microbial species: 2. Synechococcus strains representative of putative ecotypes inhabiting different depths in the Mushroom Spring microbial mat exhibit different adaptive and acclimative responses to light

    Directory of Open Access Journals (Sweden)

    Shane eNowack

    2015-06-01

    Full Text Available Closely related strains of thermophilic Synechococcus were cultivated from the microbial mats found in the effluent channels of Mushroom Spring, Yellowstone National Park (YNP. These strains have identical or nearly identical 16S rRNA sequences but are representative of separate, predicted putative ecotype populations, which were identified by using the more highly resolving psaA locus and which predominate at different vertical positions within the 1-mm-thick upper-green layer of the mat. Pyrosequencing confirmed that each strain contained a single, predominant psaA genotype. Strains differed in growth rate as a function of irradiance. A strain with a psaA genotype corresponding to a predicted putative ecotype that predominates near the mat surface grew fastest at high irradiances, whereas strains with psaA genotypes representative of predominant subsurface populations grew faster at low irradiance and exhibited greater sensitivity to abrupt shifts to high light. The high-light-adapted and low-light-adapted strains also exhibited differences in pigment content and the composition of the photosynthetic apparatus (photosystem ratio when grown under different light intensities. Cells representative of the different strains had similar morphologies under low-light conditions, but under high-light conditions, cells of low-light-adapted strains became elongated and formed short chains of cells. Collectively, the results presented here are consistent with the hypothesis that closely related, but distinct, ecological species of Synechococcus occupy different light niches in the Mushroom Spring microbial mat and acclimate differently to changing light environments.

  7. Isolation of cyanobacterial mutants exhibiting growth defects under microoxic conditions by transposon tagging mutagenesis of Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Terauchi, Kazuki; Sobue, Riho; Furutani, Yuho; Aoki, Rina; Fujita, Yuichi

    2017-05-12

    Cyanobacteria are photosynthetic prokaryotes that perform oxygenic photosynthesis by extracting electrons from water, with the generation of oxygen as a byproduct. Cyanobacteria use oxygen not only for respiration to produce energy in the dark but also for biosynthesis of various metabolites, such as heme and chlorophyll. Oxygen levels dynamically fluctuate in the field environments, from hyperoxic at daytime to almost anaerobic at night. Thus, adaptation to anaerobiosis should be important for cyanobacteria to survive in low-oxygen and anaerobic environments. However, little is known about the molecular mechanisms of cyanobacterial anaerobiosis because cyanobacteria have been regarded as aerobic organisms. As a first step to elucidate cyanobacterial adaptation mechanisms to low-oxygen environments, we isolated five mutants, T-1-T-5, exhibiting growth defects under microoxic conditions. The mutants were obtained from a transposon-tagged mutant library of the cyanobacterium Synechocystis sp. PCC 6803, which was produced by in vitro transposon tagging of cyanobacterial genomic DNA. Southern blot analysis indicated that a kanamycin resistance gene was inserted in the genome as a single copy. We identified the chromosomal transposon-tagged locus in T-5. Two open reading frames (sll0577 and sll0578) were partially deleted by the insertion of the kanamycin resistance gene in T-5. A reverse transcription polymerase chain reaction suggested that these co-transcribed genes are constitutively expressed under both aerobic and microoxic conditions. Then, we isolated two mutants in which one of the two genes was individually disrupted. Only the mutants partially lacking an intact sll0578 gene showed growth defects under microoxic conditions, whereas it grew normally under aerobic conditions. sll0578 is annotated as purK encoding N 5 -carboxy-aminoimidazole ribonucleotide synthetase involved in purine metabolism. This result implies the unexpected physiological importance of Pur

  8. Metabolic flux of the oxidative pentose phosphate pathway under low light conditions in Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Ueda, Kentaro; Nakajima, Tsubasa; Yoshikawa, Katsunori; Toya, Yoshihiro; Matsuda, Fumio; Shimizu, Hiroshi

    2018-02-27

    The role of the oxidative pentose phosphate pathway (oxPPP) in Synechocystis sp. PCC 6803 under mixotrophic conditions was investigated by 13 C metabolic flux analysis. Cells were cultured under low (10 μmol m -2  s -1 ) and high light intensities (100 μmol m -2  s -1 ) in the presence of glucose. The flux of CO 2 fixation by ribulose bisphosphate carboxylase/oxygenase under the high light condition was approximately 3-fold higher than that under the low light condition. Although no flux of the oxPPP was observed under the high light condition, flux of 0.08-0.19 mmol gDCW -1  h -1 in the oxPPP was observed under the low light condition. The balance between the consumption and production of NADPH suggested that approximately 10% of the total NADPH production was generated by the oxPPP under the low light condition. The growth phenotype of a mutant with deleted zwf, which encodes glucose-6-phosphate dehydrogenase in the oxPPP, was compared to that of the parental strain under low and high light conditions. Growth of the Δzwf mutant nearly stopped during the late growth phase under the low light condition, whereas the growth rates of the two strains were identical under the high light condition. These results indicate that NADPH production in the oxPPP is essential for anabolism under low light conditions. The oxPPP appears to play an important role in producing NADPH from glucose and ATP to compensate for NADPH shortage under low light conditions. Copyright © 2018 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  9. The LexA transcription factor regulates fatty acid biosynthetic genes in the cyanobacterium Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Kizawa, Ayumi; Kawahara, Akihito; Takashima, Kosuke; Takimura, Yasushi; Nishiyama, Yoshitaka; Hihara, Yukako

    2017-10-01

    Specific transcription factors have been identified in various heterotrophic bacterial species that regulate the sets of genes required for fatty acid metabolism. Here, we report that expression of the fab genes, encoding fatty acid biosynthetic enzymes, is regulated by the global regulator LexA in the photoautotrophic cyanobacterium Synechocystis sp. PCC 6803. Sll1626, an ortholog of the well-known LexA repressor involved in the SOS response in heterotrophic bacteria, was isolated from crude extracts of Synechocystis by DNA affinity chromatography, reflecting its binding to the upstream region of the acpP-fabF and fabI genes. An electrophoresis mobility shift assay revealed that the recombinant LexA protein can bind to the upstream region of each fab gene tested (fabD, fabH, fabF, fabG, fabZ and fabI). Quantitative RT-PCR analysis of the wild type and a lexA-disrupted mutant strain suggested that LexA acts as a repressor of the fab genes involved in initiation of fatty acid biosynthesis (fabD, fabH and fabF) and the first reductive step in the subsequent elongation cycle (fabG) under normal growth conditions. Under nitrogen-depleted conditions, downregulation of fab gene expression is partly achieved through an increase in LexA-repressing activity. In contrast, under phosphate-depleted conditions, fab gene expression is upregulated, probably due to the loss of repression by LexA. We further demonstrate that elimination of LexA largely increases the production of fatty acids in strains modified to secrete free fatty acids. © 2017 The Authors The Plant Journal © 2017 John Wiley & Sons Ltd.

  10. Role of Two Cell Wall Amidases in Septal Junction and Nanopore Formation in the Multicellular Cyanobacterium Anabaena sp. PCC 7120

    Directory of Open Access Journals (Sweden)

    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.

  11. Genetics of the Blue Light-Dependent Signal Cascade That Controls Phototaxis in the Cyanobacterium Synechocystis sp. PCC6803.

    Science.gov (United States)

    Sugimoto, Yuki; Nakamura, Hiroshi; Ren, Shukun; Hori, Koichi; Masuda, Shinji

    2017-03-01

    The Synechocystis sp. PCC6803 can move on a solid surface in response to light, a phenomenon called phototaxis. Although many of the photoreceptors involved in phototaxis have been identified, the mechanisms that regulate directional motility of Synechocystis are not well understood. Previous studies showed that a mutant lacking the blue light-using flavin (BLUF) photoreceptor PixD exhibits negative phototaxis under conditions where the wild type responds positively. PixD interacts with the pseudo-response regulator-like protein PixE in a light-dependent manner, suggesting that this intermolecular interaction is important for phototaxis regulation, although genetic evidence has been lacking. To gain further insight into phototaxis regulation by PixD-PixE signaling, we constructed the deletion mutants ΔPixE and ΔPixD-ΔPixE, and characterized their phenotypes, which matched those of the wild type (positive phototaxis). Because ΔPixD exhibited negative phototaxis, PixE must function downstream of PixD. Under intense blue light (>100 μmol m-2 s-1; 470 nm) the wild type exhibited negative phototaxis, but ΔPixD-PixE exhibited positive phototaxis toward low-intensity blue light (∼0.8 μmol m-2 s-1; 470 nm). These results suggest that an unknown light-sensing system(s), that is necessary for directional cell movement, can be activated by low-intensity blue light; on the other hand, PixD needs high-intensity blue light to be activated. We also isolated spontaneous mutants that compensated for the pixE deletion. Genome-wide sequencing of the mutants revealed that the uncharacterized gene sll2003 regulates positive and negative phototaxis in response to light intensity. © 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.

  12. Photoautotrophic Polyhydroxybutyrate Granule Formation Is Regulated by Cyanobacterial Phasin PhaP in Synechocystis sp. Strain PCC 6803

    Science.gov (United States)

    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

  13. 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

  14. The Nitrogen-regulated Response Regulator NrrA Controls Cyanophycin Synthesis and Glycogen Catabolism in the Cyanobacterium Synechocystis sp. PCC 6803*

    Science.gov (United States)

    Liu, Deng; Yang, Chen

    2014-01-01

    The cellular metabolism in cyanobacteria is extensively regulated in response to changes of environmental nitrogen availability. Multiple regulators are involved in this process, including a nitrogen-regulated response regulator NrrA. However, the regulatory role of NrrA in most cyanobacteria remains to be elucidated. In this study, we combined a comparative genomic reconstruction of NrrA regulons in 15 diverse cyanobacterial species with detailed experimental characterization of NrrA-mediated regulation in Synechocystis sp. PCC 6803. The reconstructed NrrA regulons in most species included the genes involved in glycogen catabolism, central carbon metabolism, amino acid biosynthesis, and protein degradation. A predicted NrrA-binding motif consisting of two direct repeats of TG(T/A)CA separated by an 8-bp A/T-rich spacer was verified by in vitro binding assays with purified NrrA protein. The predicted target genes of NrrA in Synechocystis sp. PCC 6803 were experimentally validated by comparing the transcript levels and enzyme activities between the wild-type and nrrA-inactivated mutant strains. The effect of NrrA deficiency on intracellular contents of arginine, cyanophycin, and glycogen was studied. Severe impairments in arginine synthesis and cyanophycin accumulation were observed in the nrrA-inactivated mutant. The nrrA inactivation also resulted in a significantly decreased rate of glycogen degradation. Our results indicate that by directly up-regulating expression of the genes involved in arginine synthesis, glycogen degradation, and glycolysis, NrrA controls cyanophycin accumulation and glycogen catabolism in Synechocystis sp. PCC 6803. It is suggested that NrrA plays a role in coordinating the synthesis and degradation of nitrogen and carbon reserves in cyanobacteria. PMID:24337581

  15. High radiation and desiccation tolerance of nitrogen-fixing cultures of the cyanobacterium Anabaena sp. strain PCC 7120 emanates from genome/proteome repair capabilities.

    Science.gov (United States)

    Singh, Harinder; Anurag, Kirti; Apte, Shree Kumar

    2013-10-12

    The filamentous nitrogen-fixing cyanobacterium, Anabaena sp. strain PCC 7120 was found to tolerate very high doses of 60 Co-gamma radiation or prolonged desiccation. Post-stress, cells remained intact and revived all the vital functions. A remarkable capacity to repair highly disintegrated genome and recycle the damaged proteome appeared to underlie such high radioresistance and desiccation tolerance. The close similarity observed between the cellular response to irradiation or desiccation stress lends strong support to the notion that tolerance to these stresses may involve similar mechanisms.

  16. Spectrum of biliary abnormalities in portal cavernoma cholangiopathy (PCC) secondary to idiopathic extrahepatic portal vein obstruction (EHPVO)-a prospective magnetic resonance cholangiopancreaticography (MRCP) based study.

    Science.gov (United States)

    Jabeen, Shumyla; Robbani, Irfan; Choh, Naseer A; Ashraf, Obaid; Shaheen, Feroze; Gojwari, Tariq; Gul, Sabeeha

    2016-12-01

    To characterize biliary abnormalities seen in portal cavernoma cholangiopathy (PCC) on MR cholangiopancreaticography (MRCP) and elucidate certain salient features of the disease by collaborating our findings with those of previous studies. We prospectively enrolled 52 patients with portal cavernoma secondary to idiopathic extrahepatic portal vein obstruction, who underwent a standard MRCP protocol. Images were analyzed for abnormalities involving the entire biliary tree. Terms used were those proposed by the Indian National Association for Study of the Liver. Angulation of the common bile duct (CBD) was measured in all patients with cholangiopathy. Cholangiopathy was seen in 80.7% of patients on MRCP. Extrahepatic ducts were involved in 95% of patients either alone (26%) or in combination with the intrahepatic ducts (69%). Isolated involvement of the intrahepatic ducts was seen in 4.8% of patients. Abnormalities of the extrahepatic ducts included angulation (90%), scalloping (76.2%), extrinsic impression/indentation (45.2%), stricture (14.3%) and smooth dilatation (4.8%). The mean CBD angle was 113.2 ± 19.8°. Abnormalities of the intrahepatic ducts included smooth dilatation (40%), irregularity (28%) and narrowing (9%). Cholelithiasis, choledocholithiasis and hepatolithiasis were seen in 28.6% (12) patients, 14.3% (6) patients and 11.9% (5) patients, respectively. There was a significant association between choledocholithiasis and CBD stricture, with no significant association between choledocholithiasis and cholelithiasis. A significant association was also seen between hepatolithiasis and choledocholithiasis. The spectrum of biliary abnormalities in PCC has been explored and some salient features of the disease have been elucidated, which allow a confident diagnosis of this entity. Advances in knowledge: PCC preferentially involves the extrahepatic biliary tree. Changes in the intrahepatic ducts generally occur as sequelae of involvement of the extrahepatic

  17. Kinetic analysis of cysteine desulfurase CD0387 from Synechocystis sp. PCC 6803: formation of the persulfide intermediate.

    Science.gov (United States)

    Behshad, Elham; Bollinger, J Martin

    2009-12-22

    Stopped-flow absorption and isotope effect experiments have been used to dissect the mechanism of formation of the enzyme cysteinyl persulfide intermediate in the reaction of a cysteine desulfurase (CD), CD0387 from Synechocystis sp. strain PCC 6803. Seven accumulating intermediates have been identified and tentatively mapped onto the CD chemical mechanism originally proposed by Dean, White, and co-workers [Zheng, L., White, R. H., Cash, V. L., and Dean, D. R. (1994) Biochemistry 33, 4714-4720]. The first intermediate with lambda(max) approximately 350 nm is assigned as either a gem-diamine complex or a thiol adduct formed by nucleophilic attack of either the amine group or the sulfhydryl group of the substrate on the internal aldimine form of the pyri