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Sample records for hydrogen-producing marine photosynthetic

  1. Enrichment of the hydrogen-producing microbial community from marine intertidal sludge by different pretreatment methods

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Hongyan [Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Road, Shinan District, Qingdao 266071, Shandong (China); College of Marine Science and Engineering, University of Science and Technology, Tianjin 300457 (China); Graduate School, Chinese Academy of Sciences, Beijing 100039 (China); Wang, Guangce [Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Road, Shinan District, Qingdao 266071, Shandong (China); College of Marine Science and Engineering, University of Science and Technology, Tianjin 300457 (China); Zhu, Daling; Pan, Guanghua [College of Marine Science and Engineering, University of Science and Technology, Tianjin 300457 (China)

    2009-12-15

    To determine the effects of pretreatment on hydrogen production and the hydrogen-producing microbial community, we treated the sludge from the intertidal zone of a bathing beach in Tianjin with four different pretreatment methods, including acid treatment, heat-shock, base treatment as well as freezing and thawing. The results showed that acid pretreatment significantly promoted the hydrogen production by sludge and provided the highest efficiency of hydrogen production among the four methods. The efficiency of the hydrogen production of the acid-pretreated sludge was 0.86 {+-} 0.07 mol H{sub 2}/mol glucose (mean {+-} S.E.), whereas that of the sludge treated with heat-shock, freezing and thawing, base method and control was 0.41 {+-} 0.03 mol H{sub 2}/mol glucose, 0.17 {+-} 0.01 mol H{sub 2}/mol glucose, 0.11 {+-} 0.01 mol H{sub 2}/mol glucose and 0.20 {+-} 0.04 mol H{sub 2}/mol glucose, respectively. The result of denaturing gradient gel electrophoresis (DGGE) showed that pretreatment methods altered the composition of the microbial community that accounts for hydrogen production. Acid and heat pretreatments were favorable to enrich the dominant hydrogen-producing bacterium, i.e. Clostridium sp., Enterococcus sp. and Bacillus sp. However, besides hydrogen-producing bacteria, much non-hydrogen-producing Lactobacillus sp. was also found in the sludge pretreated with base, freezing and thawing methods. Therefore, based on our results, we concluded that, among the four pretreatment methods using acid, heat-shock, base or freezing and thawing, acid pretreatment was the most effective method for promoting hydrogen production of microbial community. (author)

  2. Nitric oxide in marine photosynthetic organisms.

    Science.gov (United States)

    Kumar, Amit; Castellano, Immacolata; Patti, Francesco Paolo; Palumbo, Anna; Buia, Maria Cristina

    2015-05-01

    Nitric oxide is a versatile and powerful signaling molecule in plants. However, most of our understanding stems from studies on terrestrial plants and very little is known about marine autotrophs. This review summarizes current knowledge about the source of nitric oxide synthesis in marine photosynthetic organisms and its role in various physiological processes under normal and stress conditions. The interactions of nitric oxide with other stress signals and cross talk among secondary messengers are also highlighted. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Alternative photosynthetic electron flow to oxygen in marine Synechococcus.

    Science.gov (United States)

    Bailey, Shaun; Melis, Anastasios; Mackey, Katherine R M; Cardol, Pierre; Finazzi, Giovanni; van Dijken, Gert; Berg, Gry Mine; Arrigo, Kevin; Shrager, Jeff; Grossman, Arthur

    2008-03-01

    Cyanobacteria dominate the world's oceans where iron is often barely detectable. One manifestation of low iron adaptation in the oligotrophic marine environment is a decrease in levels of iron-rich photosynthetic components, including the reaction center of photosystem I and the cytochrome b6f complex [R.F. Strzepek and P.J. Harrison, Photosynthetic architecture differs in coastal and oceanic diatoms, Nature 431 (2004) 689-692.]. These thylakoid membrane components have well characterised roles in linear and cyclic photosynthetic electron transport and their low abundance creates potential impediments to photosynthetic function. Here we show that the marine cyanobacterium Synechococcus WH8102 exhibits significant alternative electron flow to O2, a potential adaptation to the low iron environment in oligotrophic oceans. This alternative electron flow appears to extract electrons from the intersystem electron transport chain, prior to photosystem I. Inhibitor studies demonstrate that a propyl gallate-sensitive oxidase mediates this flow of electrons to oxygen, which in turn alleviates excessive photosystem II excitation pressure that can often occur even at relatively low irradiance. These findings are also discussed in the context of satisfying the energetic requirements of the cell when photosystem I abundance is low.

  4. Biogeography of photosynthetic light-harvesting genes in marine phytoplankton.

    Directory of Open Access Journals (Sweden)

    Thomas S Bibby

    Full Text Available BACKGROUND: Photosynthetic light-harvesting proteins are the mechanism by which energy enters the marine ecosystem. The dominant prokaryotic photoautotrophs are the cyanobacterial genera Prochlorococcus and Synechococcus that are defined by two distinct light-harvesting systems, chlorophyll-bound protein complexes or phycobilin-bound protein complexes, respectively. Here, we use the Global Ocean Sampling (GOS Project as a unique and powerful tool to analyze the environmental diversity of photosynthetic light-harvesting genes in relation to available metadata including geographical location and physical and chemical environmental parameters. METHODS: All light-harvesting gene fragments and their metadata were obtained from the GOS database, aligned using ClustalX and classified phylogenetically. Each sequence has a name indicative of its geographic location; subsequent biogeographical analysis was performed by correlating light-harvesting gene budgets for each GOS station with surface chlorophyll concentration. CONCLUSION/SIGNIFICANCE: Using the GOS data, we have mapped the biogeography of light-harvesting genes in marine cyanobacteria on ocean-basin scales and show that an environmental gradient exists in which chlorophyll concentration is correlated to diversity of light-harvesting systems. Three functionally distinct types of light-harvesting genes are defined: (1 the phycobilisome (PBS genes of Synechococcus; (2 the pcb genes of Prochlorococcus; and (3 the iron-stress-induced (isiA genes present in some marine Synechococcus. At low chlorophyll concentrations, where nutrients are limited, the Pcb-type light-harvesting system shows greater genetic diversity; whereas at high chlorophyll concentrations, where nutrients are abundant, the PBS-type light-harvesting system shows higher genetic diversity. We interpret this as an environmental selection of specific photosynthetic strategy. Importantly, the unique light-harvesting system isiA is found

  5. Ecological and evolutionary genomics of marine photosynthetic organisms.

    Science.gov (United States)

    Coelho, Susana M; Simon, Nathalie; Ahmed, Sophia; Cock, J Mark; Partensky, Frédéric

    2013-02-01

    Environmental (ecological) genomics aims to understand the genetic basis of relationships between organisms and their abiotic and biotic environments. It is a rapidly progressing field of research largely due to recent advances in the speed and volume of genomic data being produced by next generation sequencing (NGS) technologies. Building on information generated by NGS-based approaches, functional genomic methodologies are being applied to identify and characterize genes and gene systems of both environmental and evolutionary relevance. Marine photosynthetic organisms (MPOs) were poorly represented amongst the early genomic models, but this situation is changing rapidly. Here we provide an overview of the recent advances in the application of ecological genomic approaches to both prokaryotic and eukaryotic MPOs. We describe how these approaches are being used to explore the biology and ecology of marine cyanobacteria and algae, particularly with regard to their functions in a broad range of marine ecosystems. Specifically, we review the ecological and evolutionary insights gained from whole genome and transcriptome sequencing projects applied to MPOs and illustrate how their genomes are yielding information on the specific features of these organisms. © 2012 Blackwell Publishing Ltd.

  6. Assessing the effects of ultraviolet radiation on the photosynthetic potential in Archean marine environments

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    Avila-Alonso, Dailé; Baetens, Jan M.; Cardenas, Rolando; de Baets, Bernard

    2017-07-01

    In this work, the photosynthesis model presented by Avila et al. in 2013 is extended and more scenarios inhabited by ancient cyanobacteria are investigated to quantify the effects of ultraviolet (UV) radiation on their photosynthetic potential in marine environments of the Archean eon. We consider ferrous ions as blockers of UV during the Early Archean, while the absorption spectrum of chlorophyll a is used to quantify the fraction of photosynthetically active radiation absorbed by photosynthetic organisms. UV could have induced photoinhibition at the water surface, thereby strongly affecting the species with low light use efficiency. A higher photosynthetic potential in early marine environments was shown than in the Late Archean as a consequence of the attenuation of UVC and UVB by iron ions, which probably played an important role in the protection of ancient free-floating bacteria from high-intensity UV radiation. Photosynthetic organisms in Archean coastal and ocean environments were probably abundant in the first 5 and 25 m of the water column, respectively. However, species with a relatively high efficiency in the use of light could have inhabited ocean waters up to a depth of 200 m and show a Deep Chlorophyll Maximum near 60 m depth. We show that the electromagnetic radiation from the Sun, both UV and visible light, could have determined the vertical distribution of Archean marine photosynthetic organisms.

  7. Contrasting Responses of Marine and Freshwater Photosynthetic Organisms to UVB Radiation: A Meta-Analysis

    KAUST Repository

    Jin, Peng

    2017-03-14

    Ultraviolet-B (UVB) radiation is a global stressor that has profound impacts on freshwater and marine ecosystems. However, an analysis of the patterns of sensitivity to UVB radiation across aquatic photosynthetic organisms has not yet been published. Here, we performed a meta-analysis on results reported in 214 studies compiled from the published literature to quantify and compare the magnitude of responses of aquatic photosynthetic organisms to changes in UVB radiation. The meta-analysis was conducted on observations of marine (n = 893) and freshwater macroalgae (n = 126) and of marine (n = 1,087) and freshwater (n = 2,889) microalgae (total n = 4,995). Most of these studies (85%) analyzed the performance of organisms exposed to natural solar radiation when UVB was partially or totally reduced compared with the organismal performance under the full solar radiation spectrum, whereas the remaining 15% of the studies examined the responses of organisms to elevated UVB radiation mostly using artificial lamps. We found that marine photosynthetic organisms tend to be more sensitive than freshwater photosynthetic organisms to UVB radiation; responses to either decreased or increased UVB radiation vary among taxa; the mortality rate is the most sensitive of the trait responses to elevated UVB radiation, followed by changes in cellular and molecular traits; the sensitivity of microalgae to UVB radiation is dependent on size, with small-celled microalgae more sensitive than large-celled microalgae to UVB radiation. Thick macroalgae morphotypes were the less sensitive to UVB, but this effect could not be separated from phylogenetic differences. The high sensitivity of marine species, particularly the smallest photosynthetic organisms, to increased UVB radiation suggests that the oligotrophic ocean, a habitat comprising 70% of the world\\'s oceans with high UVB penetration and dominated by picoautotrophs, is extremely vulnerable to changes in UVB radiation.

  8. Coherently wired light-harvesting in photosynthetic marine algae at ambient temperature.

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    Collini, Elisabetta; Wong, Cathy Y; Wilk, Krystyna E; Curmi, Paul M G; Brumer, Paul; Scholes, Gregory D

    2010-02-04

    Photosynthesis makes use of sunlight to convert carbon dioxide into useful biomass and is vital for life on Earth. Crucial components for the photosynthetic process are antenna proteins, which absorb light and transmit the resultant excitation energy between molecules to a reaction centre. The efficiency of these electronic energy transfers has inspired much work on antenna proteins isolated from photosynthetic organisms to uncover the basic mechanisms at play. Intriguingly, recent work has documented that light-absorbing molecules in some photosynthetic proteins capture and transfer energy according to quantum-mechanical probability laws instead of classical laws at temperatures up to 180 K. This contrasts with the long-held view that long-range quantum coherence between molecules cannot be sustained in complex biological systems, even at low temperatures. Here we present two-dimensional photon echo spectroscopy measurements on two evolutionarily related light-harvesting proteins isolated from marine cryptophyte algae, which reveal exceptionally long-lasting excitation oscillations with distinct correlations and anti-correlations even at ambient temperature. These observations provide compelling evidence for quantum-coherent sharing of electronic excitation across the 5-nm-wide proteins under biologically relevant conditions, suggesting that distant molecules within the photosynthetic proteins are 'wired' together by quantum coherence for more efficient light-harvesting in cryptophyte marine algae.

  9. Synthesis of High-Molecular-Weight Polyhydroxyalkanoates by Marine Photosynthetic Purple Bacteria.

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    Mieko Higuchi-Takeuchi

    Full Text Available Polyhydroxyalkanoate (PHA is a biopolyester/bioplastic that is produced by a variety of microorganisms to store carbon and increase reducing redox potential. Photosynthetic bacteria convert carbon dioxide into organic compounds using light energy and are known to accumulate PHA. We analyzed PHAs synthesized by 3 purple sulfur bacteria and 9 purple non-sulfur bacteria strains. These 12 purple bacteria were cultured in nitrogen-limited medium containing acetate and/or sodium bicarbonate as carbon sources. PHA production in the purple sulfur bacteria was induced by nitrogen-limited conditions. Purple non-sulfur bacteria accumulated PHA even under normal growth conditions, and PHA production in 3 strains was enhanced by nitrogen-limited conditions. Gel permeation chromatography analysis revealed that 5 photosynthetic purple bacteria synthesized high-molecular-weight PHAs, which are useful for industrial applications. Quantitative reverse transcription polymerase chain reaction analysis revealed that mRNA levels of phaC and PhaZ genes were low under nitrogen-limited conditions, resulting in production of high-molecular-weight PHAs. We conclude that all 12 tested strains are able to synthesize PHA to some degree, and we identify 5 photosynthetic purple bacteria that accumulate high-molecular-weight PHA molecules. Furthermore, the photosynthetic purple bacteria synthesized PHA when they were cultured in seawater supplemented with acetate. The photosynthetic purple bacteria strains characterized in this study should be useful as host microorganisms for large-scale PHA production utilizing abundant marine resources and carbon dioxide.

  10. Photoacclimation modulates excessive photosynthetically active and ultraviolet radiation effects in a temperate and an Antarctic marine diatom

    NARCIS (Netherlands)

    van de Poll, W.H.; Alderkamp, A.C.; Janknegt, P.J.; Roggeveld, J; Buma, A.G.J.

    The influence of photoacclimation on the effects of excessive photosynthetically active (PAR; 400-700 nm) and ultraviolet (UVR; 280-400 nm) radiation was assessed for the marine diatoms Thalassiosira weissflogii (Grunow) Fryxell and Hasle and Thalassiosira antarctica (Comber). Low and high PAR

  11. Methods to Estimate the Diversity in the Marine Photosynthetic Protist Community with Illustrations from Case Studies: A Review

    Directory of Open Access Journals (Sweden)

    Linda K. Medlin

    2010-07-01

    Full Text Available We review the application of molecular methods to estimate biodiversity in the marine environment. All of the methods reviewed here, which are at the forefront of molecular research, can be applied to all organisms in all habitats, but the case studies used to illustrate the points are derived from marine photosynthetic eukaryotic protists. It has been accepted that we know less than 10% of the identified diversity in the marine microbial world and the marine micro- and pico-eukaryotes are no exception. Even the species that we think we can easily recognize are often poorly described, and even less is known of their life histories and spatial and temporal trends in their abundance and distribution. With new molecular and analytical techniques, we can advance our knowledge of marine biodiversity at the species level to understand how marine biodiversity supports ecosystem structure, dynamics and resilience. Biogeochemical reactions performed by marine photosynthetic microbial organisms constitute a major sustaining component of ecosystem functioning, and therefore, affect climate changes. New interpretations of how environmental, ecological and evolutionary processes control and structure marine ecosystem biodiversity can be made so that we can augment our understanding of biodiversity and ecosystem dynamics in especially the pico- and nano-fractions of the plankton as well as in the deep sea benthos, both of which are very difficult to study without good analytical methods.

  12. Diel Bioluminescence in Heterotrophic and Photosynthetic Marine Dinoflagellates in an Arctic Fjord

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    1992-01-01

    bioluminescence in the marine dinoflagellates, Pyrodinium bahamense , Gonyaulax palyedra, and SPyrocystis tun ula. Journal of General Physiology, 54, 96-122...Observations ’Ind mcasurements of planktonic bioluminescence in and around a milkv sea. Journal of I xpjerimental Marine’ Biology and Ecology , 119, 55-RI1...parameters fiini a Norwegian fjord Marine Ecology Progress Series, 55, 217-227. I~apta, . & ose , JJ 1984. Observations of bioluminescence in manne

  13. Yields, photosynthetic efficiencies, and proximate chemical composition of dense cultures of marine microalgae. A subcontract report

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, W.H.; Seibert, D.L.R.; Alden, M.; Eldridge, P.; Neori, A.

    1983-07-01

    The yields, photosynthetic efficiencies, and proximate composition of several microalgae were compared in dense cultures grown at light intensities up to 70% sunlight. Yields ranged from 3.4 to 21.7 g dry weight/m/sup 2/ day. The highest yield was obtained with Phaeodactylum; the lowest in Botryococcus cultures. The same species had the highest and lowest efficiencies of utilization of photosynthetically active radiation. In nitrogen-sufficient cells of all but one species, most of the dry weight consisted of protein. Lipid content of all species was 20 to 29%, and carbohydrate content 11 to 23%. Lipid content increased somewhat in N-deficient Phaeodactylum and Isochrysis cells, but decreased in deficient Monallanthus cells. Because the overall dry weight yield was reduced by deficiency, lipid yields did not increase. However, since the carbohydrate content increased to about 65% in N-deficient Dunaliella and Tetraselmis cells, the carbohydrate yield increased. In Phaeodactylum the optimum light intensity was about 40% of full sunlight. Most experimets with this alga included a CUSO/sub 4/ filter to decrease infrared irradiance. When this filter was removed, the yield increased because more red light in the photosynthetically active spectral range was included. These results should prove useful to workers attempting to maximize yields and efficiencies, but additional studies are needed. 69 references, 27 figures, 18 tables.

  14. Vertical distribution of major photosynthetic picoeukaryotic groups in stratified marine waters

    KAUST Repository

    Cabello, Ana M.

    2016-03-14

    Photosynthetic picoeukaryotes (PPEs) are fundamental contributors to oceanic primary production and form diverse communities dominated by prymnesiophytes, chlorophytes, pelagophytes and chrysophytes. Here, we studied the vertical distribution of these major groups in two offshore regions of the northern Iberian Peninsula during summer stratification. We performed a fine-scale vertical sampling (every ∼2 m) across the DCM and used fluorescence in situ hybridization (FISH) to determine the PPE composition and to explore the possible segregation of target groups in the light, nutrient and temperature gradients. Chlorophytes, pelagophytes and prymnesiophytes, in this order of abundance, accounted for the total PPEs recorded by flow cytometry in the Avilés canyon, and for more than half in the Galicia Bank, whereas chrysophytes were undetected. Among the three detected groups, often the prymnesiophytes were dominant in biomass. In general, all groups were present throughout the water column with abundance peaks around the DCM, but their distributions differed: pelagophytes were located deeper than the other two groups, chlorophytes presented two peaks and prymnesiophytes exhibited surface abundances comparable to those at the DCM. This study offers first indications that the vertical distribution of different PPE groups is heterogeneous within the DCM. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

  15. Biogeography and Photosynthetic Biomass of Arctic Marine Pico-Eukaroytes during Summer of the Record Sea Ice Minimum 2012.

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    Metfies, Katja; von Appen, Wilken-Jon; Kilias, Estelle; Nicolaus, Anja; Nöthig, Eva-Maria

    2016-01-01

    Information on recent photosynthetic biomass distribution and biogeography of Arctic marine pico-eukaryotes (0.2-3 μm) is needed to better understand consequences of environmental change for Arctic marine ecosystems. We analysed pico-eukaryote biomass and community composition in Fram Strait and large parts of the Central Arctic Ocean (Nansen Basin, Amundsen Basin) using chlorophyll a (Chl a) measurements, automated ribosomal intergenic spacer analysis (ARISA) and 454-pyrosequencing. Samples were collected during summer 2012, the year with the most recent record sea ice minimum. Chl a concentrations were highest in eastern Fram Strait and pico-plankton accounted for 60-90% of Chl a biomass during the observation period. ARISA-patterns and 454-pyrosequencing revealed that pico-eukaryote distribution is closely related to water mass distribution in the euphotic zone of the Arctic Ocean. Phaeocystaceae, Micromonas sp., Dinophyceae and Syndiniales constitute a high proportion of sequence reads, while sequence abundance of autotrophic Phaeocystaceae and mixotrophic Micromonas sp. was inversely correlated. Highest sequence abundances of Phaeocystaceae were observed in the warm Atlantic Waters in Fram Strait, while Micromonas sp. dominated the abundant biosphere in the arctic halocline. Our results are of particular interest considering existing hypotheses that environmental conditions in Nansen Basin might become more similar to the current conditions in Fram Strait. We propose that in response, biodiversity and biomass of pico-eukaryotes in Nansen Basin could resemble those currently observed in Fram Strait in the future. This would significantly alter biogeochemical cycles in a large part of the Central Arctic Ocean.

  16. The maximum specific hydrogen-producing activity of anaerobic mixed cultures: definition and determination

    National Research Council Canada - National Science Library

    Mu, Yang; Yang, Hou-Yun; Wang, Ya-Zhou; He, Chuan-Shu; Zhao, Quan-Bao; Wang, Yi; Yu, Han-Qing

    2014-01-01

    .... Methodology for characterizing the hydrogen-producing activity of anaerobic mixed cultures is essential for monitoring reactor operation in fermentative hydrogen production, however there is lack...

  17. The organellar genome and metabolic potential of the hydrogen- producing mitochondrion of Nyctotherus ovalis

    NARCIS (Netherlands)

    J.H.P. Hackstein (Johannes); C. Burgtorf; B.E. Dutilh (Bas); I. Duarte (Isabel); G.W.M. van der Staay (Georg); R.M. de Graaf (Rob); J.W.P. Kuiper (Jan); M. Huynen (Martijn); T.A. van Alen (Theo); G. Ricard (Guenola); A.G.M. Tielens (Aloysius)

    2011-01-01

    textabstractAbstract It is generally accepted that hydrogenosomes (hydrogen-producing organelles) evolved from a mitochondrial ancestor. However, until recently, only indirect evidence for this hypothesis was available. Here, we present the almost complete genome of the hydrogen-producing

  18. System responses to equal doses of photosynthetically usable radiation of blue, green, and red light in the marine diatom Phaeodactylum tricornutum.

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    Kristin Collier Valle

    Full Text Available Due to the selective attenuation of solar light and the absorption properties of seawater and seawater constituents, free-floating photosynthetic organisms have to cope with rapid and unpredictable changes in both intensity and spectral quality. We have studied the transcriptional, metabolic and photo-physiological responses to light of different spectral quality in the marine diatom Phaeodactylum tricornutum through time-series studies of cultures exposed to equal doses of photosynthetically usable radiation of blue, green and red light. The experiments showed that short-term differences in gene expression and profiles are mainly light quality-dependent. Transcription of photosynthesis-associated nuclear genes was activated mainly through a light quality-independent mechanism likely to rely on chloroplast-to-nucleus signaling. In contrast, genes encoding proteins important for photoprotection and PSII repair were highly dependent on a blue light receptor-mediated signal. Changes in energy transfer efficiency by light-harvesting pigments were spectrally dependent; furthermore, a declining trend in photosynthetic efficiency was observed in red light. The combined results suggest that diatoms possess a light quality-dependent ability to activate photoprotection and efficient repair of photodamaged PSII. In spite of approximately equal numbers of PSII-absorbed quanta in blue, green and red light, the spectral quality of light is important for diatom responses to ambient light conditions.

  19. Comparative genomic analyses of the cyanobacterium, Lyngbya aestuarii BL J, a powerful hydrogen producer.

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    Ankita eKothari

    2013-12-01

    Full Text Available The filamentous, non-heterocystous cyanobacterium Lyngbya aestuarii is an important contributor to marine intertidal microbial mats system worldwide. The recent isolate L. aestuarii BL J, is an unusually powerful hydrogen producer. Here we report a morphological, ultrastructural and genomic characterization of this strain to set the basis for future systems studies and applications of this organism. The filaments contain circa 17 μm wide trichomes, composed of stacked disk-like short cells (2 μm long, encased in a prominent, laminated exopolysaccharide sheath. Cellular division occurs by transversal centripetal growth of cross-walls, where several rounds of division proceed simultaneously. Filament division occurs by cell self-immolation of one or groups of cells (necridial cells at the breakage point. Short, sheath-less, motile filaments (hormogonia are also formed. Morphologically and phylogenetically L. aestuarii belongs to a clade of important cyanobacteria that include members of the marine Trichodesmiun and Hydrocoleum genera, as well as terrestrial Microcoleus vaginatus strains, and alkalyphilic strains of Arthrospira. A draft genome of strain BL J was compared to those of other cyanobacteria in order to ascertain some of its ecological constraints and biotechnological potential. The genome had an average GC content of 41.1 %. Of the 6.87 Mb sequenced, 6.44 Mb was present as large contigs (>10,000 bp. It contained 6515 putative protein-encoding genes, of which, 43 % encode proteins of known functional role, 26 % corresponded to proteins with domain or family assignments, 19.6 % encode conserved hypothetical proteins, and 11.3 % encode apparently unique hypothetical proteins. The strain’s genome reveals its adaptations to a life of exposure to intense solar radiation and desiccation. It likely employs the storage compounds, glycogen and cyanophycin but no polyhydroxyalkanoates, and can produce the osmolytes, trehalose and glycine

  20. Exploration of the antioxidant system and photosynthetic system of a marine algicidal Bacillus and its effect on four harmful algal bloom species.

    Science.gov (United States)

    Hou, Shaoling; Shu, Wanjiao; Tan, Shuo; Zhao, Ling; Yin, Pinghe

    2016-01-01

    A novel marine bacterium, strain B1, initially showed 96.4% algicidal activity against Phaeocystis globosa. Under this situation, 3 other harmful algal species (Skeletonema costatum, Heterosigma akashiwo, and Prorocentrum donghaiense) were chosen to study the algicidal effects of strain B1, and the algicidal activities were 91.4%, 90.7%, and 90.6%, respectively. To explore the algicidal mechanism of strain B1 on these 4 harmful algal species, the characteristics of the antioxidant system and photosynthetic system were studied. Sensitivity to strain B1 supernatant, enzyme activity, and gene expression varied with algal species, while the algicidal patterns were similar. Strain B1 supernatant increased malondialdehyde contents; decreased chlorophyll a contents; changed total antioxidant and superoxide dismutase activity; and restrained psbA, psbD, and rbcL genes expression, which eventually resulted in the algal cells death. The algicidal procedure was observed using field emission scanning electron microscopy, which indicated that algal cells were lysed and cellular substances were released. These findings suggested that the antioxidant and photosynthetic system of these 4 algal species was destroyed under strain B1 supernatant stress. This is the first report to explore and compare the mechanism of a marine Bacillus against harmful algal bloom species of covered 4 phyla.

  1. The thylakoid membrane proteome of two marine diatoms outlines both diatom-specific and species-specific features of the photosynthetic machinery.

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    Grouneva, Irina; Rokka, Anne; Aro, Eva-Mari

    2011-12-02

    The thylakoid membrane of photoautotrophic organisms contains the main components of the photosynthetic electron transport chain. Detailed proteome maps of the thylakoid protein complexes of two marine diatoms, Thalassiosira pseudonana and Phaeodactylum tricornutum, were created by means of two-dimensional blue native (BN)/SDS-PAGE coupled with mass spectrometry analysis. One novel diatom-specific photosystem I (PS I)-associated protein was identified. A second plastid-targeted protein with possible PS I interaction was discovered to be restricted to the centric diatom species T. pseudonana. PGR5/PGRL homologues were found to be the only protein components of PS I-mediated cyclic electron transport common to both species. For the first time, evidence for a possible PS I localization of LI818-like light harvesting proteins (Lhcx) is presented. This study also advances the current knowledge on the light harvesting antenna composition and Lhcx expression in T. pseudonana on the protein level and presents details on the molecular distribution of Lhcx in diatoms. Above mentioned proteins and several others with unknown function provide a broad basis for further mutagenesis analysis, aiming toward further understanding of the composition and function of the photosynthetic apparatus of diatoms. The proteomics approach of this study further served as a tool to confirm and improve genome-derived protein models.

  2. Thermal alteration of organic matter in recent marine sediments. 1: Pigments. [photosynthetic pigments from Tanner Basin off Southern California

    Science.gov (United States)

    Ikan, R.; Aizenshtat, Z.; Baedecker, M. J.; Kaplan, I. R.

    1974-01-01

    Sediment from Tanner Basin, the outer continental shelf off Southern California, was analyzed for photosynthetic pigments and their derivatives, namely carotenes and chlorins. Samples of the sediment were also exposed to raised temperatures (65, 100, 150 C) for various periods of time (1 week, 1 month, 2 months). Analysis of the heat-treated sediment revealed the presence of alpha-ionene and 2,6-dimethylnapthalene, thermal degradation products of Betacarotente. Chlorins were converted to nickel porphyrins of both DPEP and etio series. Possible mechanisms of these transformations are presented.

  3. Photosynthetic response to temperature of marine phytoplankton along a latitudinal gradient (16°N to 74°N)

    Science.gov (United States)

    Li, W. K. W.

    1985-11-01

    Photosynthesis-temperature relationships for natural phytoplankton assemblages were established by measuring the uptake of H 14CO 3 in freshly collected seawater samples incubated for 2 h across a shipboard laboratory temperature gradient. The minimum, optimum and maximum temperatures for photosynthesis, as well as the extent of photosynthetic change per unit temperature change in the suboptimal range, all decreased from low to high latitude. The empirical mathematical model of RATKOWSKYet al. (1983, Journal of Bacteriology, 154, 1222-1226) provided a good fit to the data.

  4. Thiophaeococcus mangrovi gen. nov., sp. nov., a photosynthetic, marine gammaproteobacterium isolated from the Bhitarkanika mangrove forest of India.

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    Anil Kumar, P; Srinivas, T N R; Sasikala, Ch; Ramana, Ch V; Imhoff, J F

    2008-11-01

    A coccoid, phototrophic purple sulfur bacterium was isolated in pure culture from a mud sample collected from brackish water in the Bhitarkanika mangrove forest of Orissa, India, in a medium containing 2 % NaCl (w/v). This bacterium, strain JA304(T), was Gram-negative and had a requirement for NaCl. Intracellular photosynthetic membranes were of the vesicular type. The colour of the phototrophically grown culture was saddle-brown. Bacteriochlorophyll a and the carotenoid lycopene were present as photosynthetic pigments. Strain JA304(T) was able to grow photolithoautotrophically and could photoassimilate a number of organic substrates. Yeast extract was required for growth of strain JA304(T). The DNA G+C content was 68.1-68.9 mol%. 16S rRNA gene sequence comparisons indicate that the isolate represents a member of the Chromatiaceae within the class Gammaproteobacteria. According to sequence comparison data, strain JA304(T) is positioned distinctly outside the group formed by the four genera Thiocystis, Chromatium, Allochromatium and Thermochromatium, with only 86.7-91.0 % sequence similarity. Distinct morphological, physiological and genotypic differences from these previously described taxa support the classification of this isolate as a representative of a novel species in a new genus, for which the name Thiophaeococcus mangrovi gen. nov., sp. nov. is proposed. The type strain of Thiophaeococcus mangrovi is JA304(T) (=JCM 14889(T) =DSM 19863(T)).

  5. Photosynthetic activity in marine and brackish water strains of Fucus vesiculosus and Fucus radicans (Phaeophyceae) at different light qualities.

    Science.gov (United States)

    Svahn, Carina; Maria Gylle, A; Ekelund, Nils G A

    2012-01-01

    This study investigates the effects of different light qualities on the photosynthetic capacity of the brown algae Fucus vesiculosus, from the Norwegian Sea, and Fucus radicans and F. vesiculosus, from the Bothnian Sea. The electron transport rates (ETR) obtained for F. vesiculosus from the Norwegian Sea showed significantly higher levels of light saturation compared with both species of algae from the Bothnian Sea. The maximum of ETR values for the Norwegian Sea strain showed no significant changes due to varying light quality compared with the initial values. For F. vesiculosus, from the Bothnian Sea, treatment with blue light showed an effect after 1 week of 30 and 90 μmol photons m(-2) s(-1) (P<0.01), and for F. radicans from the Bothnian Sea, at the irradiance of 90 μmol photons m(-2) s(-1) and 1 week (P<0.01). After 1 week in the Bothnian Sea species and after 2 weeks in F. vesiculosus from the Norwegian Sea, the photosynthetic efficiency (α) was significantly higher regardless of light quality and irradiance compared with the initial values. Variation in light quality and irradiance had minor effects on the F(v):F(m) values of the three algal strains studied. © 2012 Wiley Periodicals, Inc. Photochemistry and Photobiology © 2012 The American Society of Photobiology.

  6. The Organellar Genome and Metabolic Potential of the Hydrogen-Producing Mitochondrion of Nyctotherus ovalis

    Science.gov (United States)

    de Graaf, Rob M.; Ricard, Guenola; van Alen, Theo A.; Duarte, Isabel; Dutilh, Bas E.; Burgtorf, Carola; Kuiper, Jan W. P.; van der Staay, Georg W. M.; Tielens, Aloysius G. M.; Huynen, Martijn A.; Hackstein, Johannes H. P.

    2011-01-01

    It is generally accepted that hydrogenosomes (hydrogen-producing organelles) evolved from a mitochondrial ancestor. However, until recently, only indirect evidence for this hypothesis was available. Here, we present the almost complete genome of the hydrogen-producing mitochondrion of the anaerobic ciliate Nyctotherus ovalis and show that, except for the notable absence of genes encoding electron transport chain components of Complexes III, IV, and V, it has a gene content similar to the mitochondrial genomes of aerobic ciliates. Analysis of the genome of the hydrogen-producing mitochondrion, in combination with that of more than 9,000 genomic DNA and cDNA sequences, allows a preliminary reconstruction of the organellar metabolism. The sequence data indicate that N. ovalis possesses hydrogen-producing mitochondria that have a truncated, two step (Complex I and II) electron transport chain that uses fumarate as electron acceptor. In addition, components of an extensive protein network for the metabolism of amino acids, defense against oxidative stress, mitochondrial protein synthesis, mitochondrial protein import and processing, and transport of metabolites across the mitochondrial membrane were identified. Genes for MPV17 and ACN9, two hypothetical proteins linked to mitochondrial disease in humans, were also found. The inferred metabolism is remarkably similar to the organellar metabolism of the phylogenetically distant anaerobic Stramenopile Blastocystis. Notably, the Blastocystis organelle and that of the related flagellate Proteromonas lacertae also lack genes encoding components of Complexes III, IV, and V. Thus, our data show that the hydrogenosomes of N. ovalis are highly specialized hydrogen-producing mitochondria. PMID:21378103

  7. Interacting Effects of Light and Iron Availability on the Coupling of Photosynthetic Electron Transport and CO2-Assimilation in Marine Phytoplankton

    Science.gov (United States)

    Schuback, Nina; Schallenberg, Christina; Duckham, Carolyn; Maldonado, Maria T.; Tortell, Philippe D.

    2015-01-01

    Iron availability directly affects photosynthesis and limits phytoplankton growth over vast oceanic regions. For this reason, the availability of iron is a crucial variable to consider in the development of active chlorophyll a fluorescence based estimates of phytoplankton primary productivity. These bio-optical approaches require a conversion factor to derive ecologically-relevant rates of CO2-assimilation from estimates of electron transport in photosystem II. The required conversion factor varies significantly across phytoplankton taxa and environmental conditions, but little information is available on its response to iron limitation. In this study, we examine the role of iron limitation, and the interacting effects of iron and light availability, on the coupling of photosynthetic electron transport and CO2-assimilation in marine phytoplankton. Our results show that excess irradiance causes increased decoupling of carbon fixation and electron transport, particularly under iron limiting conditions. We observed that reaction center II specific rates of electron transport (ETRRCII, mol e- mol RCII-1 s-1) increased under iron limitation, and we propose a simple conceptual model for this observation. We also observed a strong correlation between the derived conversion factor and the expression of non-photochemical quenching. Utilizing a dataset from in situ phytoplankton assemblages across a coastal – oceanic transect in the Northeast subarctic Pacific, this relationship was used to predict ETRRCII: CO2-assimilation conversion factors and carbon-based primary productivity from FRRF data, without the need for any additional measurements. PMID:26171963

  8. Interacting Effects of Light and Iron Availability on the Coupling of Photosynthetic Electron Transport and CO2-Assimilation in Marine Phytoplankton.

    Directory of Open Access Journals (Sweden)

    Nina Schuback

    Full Text Available Iron availability directly affects photosynthesis and limits phytoplankton growth over vast oceanic regions. For this reason, the availability of iron is a crucial variable to consider in the development of active chlorophyll a fluorescence based estimates of phytoplankton primary productivity. These bio-optical approaches require a conversion factor to derive ecologically-relevant rates of CO2-assimilation from estimates of electron transport in photosystem II. The required conversion factor varies significantly across phytoplankton taxa and environmental conditions, but little information is available on its response to iron limitation. In this study, we examine the role of iron limitation, and the interacting effects of iron and light availability, on the coupling of photosynthetic electron transport and CO2-assimilation in marine phytoplankton. Our results show that excess irradiance causes increased decoupling of carbon fixation and electron transport, particularly under iron limiting conditions. We observed that reaction center II specific rates of electron transport (ETR(RCII, mol e- mol RCII(-1 s(-1 increased under iron limitation, and we propose a simple conceptual model for this observation. We also observed a strong correlation between the derived conversion factor and the expression of non-photochemical quenching. Utilizing a dataset from in situ phytoplankton assemblages across a coastal--oceanic transect in the Northeast subarctic Pacific, this relationship was used to predict ETR(RCII: CO2-assimilation conversion factors and carbon-based primary productivity from FRRF data, without the need for any additional measurements.

  9. Photosynthetic bacteria as alternative energy sources: overview on hydrogen production research

    Energy Technology Data Exchange (ETDEWEB)

    Mitsui, A.; Ohta, Y.; Frank, J.

    1979-01-01

    Hydrogen production research towards the application of marine and non-marine species of photosynthetic bacteria is reviewed. Potential use of photosynthetic bacteria as renewable energy resources is discussed.

  10. Draft genome sequence of Thermoanaerobacterium sp. strain PSU-2 isolated from thermophilic hydrogen producing reactor.

    Science.gov (United States)

    O-Thong, Sompong; Khongkliang, Peerawat; Mamimin, Chonticha; Singkhala, Apinya; Prasertsan, Poonsuk; Birkeland, Nils-Kåre

    2017-06-01

    Thermoanaerobacterium sp. strain PSU-2 was isolated from thermophilic hydrogen producing reactor and subjected to draft genome sequencing on 454 pyrosequencing and annotated on RAST. The draft genome sequence of strain PSU-2 contains 2,552,497 bases with an estimated G + C content of 35.2%, 2555 CDS, 8 rRNAs and 57 tRNAs. The strain had a number of genes responsible for carbohydrates metabolic, amino acids and derivatives, and protein metabolism of 17.7%, 14.39% and 9.81%, respectively. Strain PSU-2 also had gene responsible for hydrogen biosynthesis as well as the genes related to Ni-Fe hydrogenase. Comparative genomic analysis indicates strain PSU-2 shares about 94% genome sequence similarity with Thermoanaerobacterium xylanolyticum LX-11. The nucleotide sequence of this draft genome was deposited into DDBJ/ENA/GenBank under the accession MSQD00000000.

  11. Price determination for hydrogen produced from bio-ethanol in Argentina

    Energy Technology Data Exchange (ETDEWEB)

    Gregorini, V.A.; Pasquevich, D. [Instituto de Energia y Desarrollo Sustentable - CNEA, Av. Del Libertador 8250, Buenos Aires (Argentina); Laborde, M. [Facultad de Ingenieria - Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires (Argentina)

    2010-06-15

    A massive penetration for hydrogen as a fuel vector requires a price reduction against fossil fuels (up to lower or at less equal to current prices). That is why it is important to calculate the current prices, so that we can determinate the gap between them and work in reducing them. In order to follow properly prices evolution it is necessary been able to compare data generated by Universities, Laboratories and Industries. So that, DOE creates in 2003 a tool (H2A) to determine prices for hydrogen, with some assumptions and pre defined values, to facilitate transparency and consistency of data. In this work we will use the H2A tool to calculate de price of hydrogen produced in a bio-ethanol semi-industrial Plant in Argentina, and we will compare it with the prices of USA studies. (author)

  12. Thermophilic hydrogen-producing bacteria inhabiting deep-sea hydrothermal environments represented by Caloranaerobacter.

    Science.gov (United States)

    Jiang, Lijing; Xu, Hongxiu; Zeng, Xiang; Wu, Xiaobing; Long, Minnan; Shao, Zongze

    2015-11-01

    Hydrogen is an important energy source for deep-sea hydrothermal vent ecosystems. However, little is known about microbes and their role in hydrogen turnover in the environment. In this study, the diversity and physiological characteristics of fermentative hydrogen-producing microbes from deep-sea hydrothermal vent fields were described for the first time. Seven enrichments were obtained from hydrothermal vent sulfides collected from the Southwest Indian Ocean, East Pacific and South Atlantic. 16S rRNA gene analysis revealed that members of the Caloranaerobacter genus were the dominant component in these enrichments. Subsequently, three thermophilic hydrogen producers, strains H363, H53214 and DY22619, were isolated. They were phylogenetically related to species of the genus Caloranaerobacter. The H2 yields of strains H363, H53214, DY22619 and MV107, which was the type species of genus Caloranaerobacter, were 0.11, 1.21, 3.13 and 2.85 mol H2/mol glucose, respectively. Determination of the main soluble metabolites revealed that strains H363, H53214 and MV107 performed heterolactic fermentations, while strain DY22619 performed butyric acid fermentation, indicating distinct fermentation patterns among members of the genus. Finally, a diversity of forms of [FeFe]-hydrogenase with different modular structures was revealed based on draft genomic data of Caloranaerobacter strains. This highlights the complexity of hydrogen metabolism in Caloranaerobacter, reflecting adaptations to environmental conditions in hydrothermal vent systems. Collectively, results suggested that Caloranaerobacter species might be ubiquitous and play a role in biological hydrogen generation in deep-sea hydrothermal vent fields. Copyright © 2015 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

  13. Dark fermentation: isolation and characterization of hydrogen-producing strains from sludges.

    Science.gov (United States)

    Rajhi, Haifa; Conthe, Mónica; Puyol, Daniel; Díaz, Emiliano; Sanz, José Luis

    2013-03-01

    To improve bacterial hydrogen production, ten hydrogen-producing strains belonging to Clostridium spp. were isolated from various sludges under low vacuum. Hydrogenogenesis by dark fermentation in batch cultures of these strains was optimal at about 35 degrees C and an initial pH of 6.5, which for all strains gradually dropped to ca. pH 4 during the fermentation. Clostridium roseum H5 and C. diolis RT2 had the highest hydrogen yields per total substrate (120 ml H2/g initial COD). Substrate consumption alone by C. beijerinckii UAM and C. diolis RT2 reached 573 and 475 ml H2/g consumed COD, respectively. Butyric acid fermentation was predominant, with butyrate and acetate as the major by-products and propionate, ethanol, and lactate as secondary metabolites. The acetate:butyrate ratios and fermentation pathways varied depending on the strains and environmental conditions. Hydrogenogenesis was studied in greater detail in C. saccharobutylicum H1. In butyric acid fermentation by this representative strain, acetoacetate was detected as an intermediate metabolite. Hydrogenogenesis was also analyzed in an enrichment culture, which behaved similarly to the axenic cultures.

  14. Hydrogen photoproduction by use of photosynthetic organisms and biomimetic systems.

    Science.gov (United States)

    Allakhverdiev, Suleyman I; Kreslavski, Vladimir D; Thavasi, Velmurugan; Zharmukhamedov, Sergei K; Klimov, Vyacheslav V; Nagata, Toshi; Nishihara, Hiroshi; Ramakrishna, Seeram

    2009-02-01

    Hydrogen can be important clean fuel for future. Among different technologies for hydrogen production, oxygenic natural and artificial photosyntheses using direct photochemistry in synthetic complexes have a great potential to produce hydrogen, since both use clean and cheap sources: water and solar energy. Artificial photosynthesis is one way to produce hydrogen from water using sunlight by employing biomimetic complexes. However, splitting of water into protons and oxygen is energetically demanding and chemically difficult. In oxygenic photosynthetic microorganisms such as algae and cyanobacteria, water is split into electrons and protons, which during primary photosynthetic process are redirected by photosynthetic electron transport chain, and ferredoxin, to the hydrogen-producing enzymes hydrogenase or nitrogenase. By these enzymes, e- and H+ recombine and form gaseous hydrogen. Biohydrogen activity of hydrogenase can be very high but it is extremely sensitive to photosynthetic O2. In contrast, nitrogenase is insensitive to O2, but has lower activity. At the moment, the efficiency of biohydrogen production is low. However, theoretical expectations suggest that the rates of photon conversion efficiency for H2 bioproduction can be high enough (>10%). Our review examines the main pathways of H2 photoproduction by using of photosynthetic organisms and biomimetic photosynthetic systems.

  15. Production of bioplastics and hydrogen gas by photosynthetic microorganisms

    Science.gov (United States)

    Yasuo, Asada; Masato, Miyake; Jun, Miyake

    1998-03-01

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

  16. Ultrastructure and Phylogeny of Kirithra asteri gen. et sp. nov. (Ceratoperidiniaceae, Dinophyceae) - a Free-Living, Thin-Walled Marine Photosynthetic Dinoflagellate from Argentina.

    Science.gov (United States)

    Boutrup, Pernille Vængebjerg; Moestrup, Øjvind; Tillmann, Urban; Daugbjerg, Niels

    2017-11-01

    A gymnodinioid photosynthetic dinoflagellate was isolated from Argentina and examined by light and electron microscopy and analysis of nuclear-encoded LSU rDNA. Kirithra asteri gen. et sp. nov. was proposed as morphology and molecular phylogeny separated this dinoflagellate from others within the family Ceratoperidiniaceae. Cells were surrounded by a hyaline amphiesma comprising polygonal vesicles. Each vesicle contained a honeycomb and a trilaminar structure. An anterior sulcal extension ending in a complete circle formed the apical structure complex (ASC), which characterizes Ceratoperidiniaceae. The ASC comprised three rows of vesicles. The nucleus was located in the hypocone, and several large, irregularly shaped vesicles were present in the epi- and hypocone. Chloroplasts were surrounded by three membranes, and grana-like arrangements of thylakoids were observed in one strain used for ultrastructural study. The cell centre contained 1-3 multiple-stalked pyrenoids and membrane-bound vesicles containing tile-like structures surrounded each pyrenoid. Two pusules with collecting chambers and associated vesicles branched off each of the flagellar canals. The flagellar apparatus featured a ventral connective between the amphiesma and the R1 root, and almost opposite basal bodies, rarely seen in dinoflagellates. This was the first ultrastructural study of a species within Ceratoperidiniaceae. Copyright © 2017 Elsevier GmbH. All rights reserved.

  17. Marine

    NARCIS (Netherlands)

    Govers, L.; Man in 't Veld, W.A.; Meffert, J.P.; Bouma, T.J.; van Rijswick, P.C.; Heusinkveld, J.H.T.; Orth, R.J.; van Katwijk, M.M.; van der Heide, T.

    2016-01-01

    Phytophthora species are potent pathogens that can devastate terrestrial plants, causing billions of dollars of damage yearly to agricultural crops and harming fragile ecosystems worldwide. Yet, virtually nothing is known about the distribution and pathogenicity of their marine relatives.

  18. Proton efflux coupled to dark H2 oxidation in whole cells of a marine sulfur photosynthetic bacterium (Chromatium sp. strain Miami PBS1071).

    Science.gov (United States)

    Kumazawa, S; Izawa, S; Mitsui, A

    1983-04-01

    Whole cells of photoanaerobically grown Chromatium sp. strain Miami PBS1071, a marine sulfur purple bacterium, oxidized H2 in the dark through the oxyhydrogen reaction at rates of up to 59 nmol of H2 per mg (dry weight) per min. H2 oxidation was routinely measured in H2 pulse experiments with air-equilibrated cells. The reaction was accompanied by a reversible H+ efflux from the cells, suggesting an outward H+ translocation reaction coupled to H2 oxidation. The H+/e- ratio, calculated from simultaneous measurements of H2, O2, and H+ changes in the medium, varied with the cultures from 0.7 to 1.2. The ratio increased considerably when the backflow of H+ was taken into account. Anaerobic H2 uptake with 2,5-dimethyl-p-benzoguinone as an oxidant also showed a weak H+-translocating activity. No H+-translocating activity was detected with methylene blue as an oxidant. Carbonylcyanide 3-chlorophenylhydrazone (1 microM) stimulated H2 oxidation and abolished the associated H+ changes when H2 oxidation was observed in O2 pulse experiments with H2-Ar-equilibrated cells. However, the uncoupler inhibited both H2 oxidation and H+ changes when measurements were made in H2 pulse experiments with air-equilibrated cells. It is suggested that in this bacterium the susceptibility of hydrogenase to reversible O2 inactivation in situ is enhanced by the presence of uncoupling agents.

  19. Proton efflux coupled to dark H/sub 2/ oxidation in whole cells of a marine sulfur photosynthetic bacterium (Chromatium sp. strain Miami PBS1071)

    Energy Technology Data Exchange (ETDEWEB)

    Kumazawa, S.; Izawa, S.; Mitsui, A.

    1983-04-01

    Whole cells of photoanaerobically grown Chromatium sp. strain Miami PBS1071, a marine sulfur purple bacterium, oxidized H/sub 2/ in the dark through the oxyhydrogen reaction at rates of up to 59 nmol of H/sub 2/ per mg (dry weight) per min. H/sub 2/ oxidation was routinely measured in H/sub 2/ pulse experiments with air-equilibrated cells. The reaction was accompanied by a reversible H/sup +/ efflux from the cells, suggesting an outward H/sup +/ translocation reaction coupled to H/sub 2/ oxidation. Anaerobic H/sub 2/ uptake with 2,5-dimethyl-p-benzoguinone as an oxidant also showed a weak H/sup +/-translocating activity. Carbonylcyanide 3-chlorophenylhydrazone (1 ..mu..M) stimulated H/sub 2/ oxidation and abolished the associated H/sup +/ changes when H/sub 2/ oxidation was observed in O/sub 2/ pulse experiments with H/sub 2/-Ar-equilibrated cells. However, the uncoupler inhibited both H/sub 2/ oxidation and H/sup +/ changes when measurements were made in H/sub 2/ pulse experiments with air-equilibrated cells. It is suggested that in this bacterium the susceptibility of hydrogenase to reversible O/sub 2/ inactivation in situ is enhanced by the presence of uncoupling agents.

  20. Modelling of hydrogen production in batch cultures of the photosynthetic bacterium Rhodobacter capsulatus

    Energy Technology Data Exchange (ETDEWEB)

    Obeid, Jamila; Magnin, Jean-Pierre [Grenoble Institute of Technology, LEPMI, UMR 5631 (CNRS-INPG-UJF), BP 75, 38402 St Martin d' Heres (France); Flaus, Jean-Marie; Adrot, Olivier [Grenoble Institute of Technology, Laboratoire des sciences pour la conception, l' optimisation et la production, 46, avenue Felix Viallet, 38031 Grenoble (France); Willison, John C. [Laboratoire de Chimie et Biologie des Metaux (UMR 5249 CEA-CNRS-UJF), iRTSV/LCBM, CEA-Grenoble, 38054 Grenoble (France); Zlatev, Roumen [Autonomous University of Baja California, Institute of Engineering, Mexicali, Baja California (Mexico)

    2009-01-15

    The photosynthetic bacterium, Rhodobacter capsulatus, produces hydrogen under nitrogen-limited, anaerobic, photosynthetic culture conditions, using various carbon substrates. In the present study, the relationship between light intensity and hydrogen production has been modelled in order to predict both the rate of hydrogen production and the amount of hydrogen produced at a given time during batch cultures of R. capsulatus. The experimental data were obtained by investigating the effect of different light intensities (6000-50,000 lux) on hydrogen-producing cultures of R. capsulatus grown in a batch photobioreactor, using lactate as carbon and hydrogen source. The rate of hydrogen production increased with increasing light intensity in a manner that was described by a static Baly model, modified to include the square of the light intensity. In agreement with previous studies, the kinetics of substrate utilization and growth of R. capsulatus was represented by the classical Monod or Michaelis-Menten model. When combined with a dynamic Leudekong-Piret model, the amount of hydrogen produced as a function of time was effectively predicted. These results will be useful for the automatization and control of bioprocesses for the photoproduction of hydrogen. (author)

  1. Light-field-characterization in a continuous hydrogen-producing photobioreactor by optical simulation and computational fluid dynamics.

    Science.gov (United States)

    Krujatz, Felix; Illing, Rico; Krautwer, Tobias; Liao, Jing; Helbig, Karsten; Goy, Katharina; Opitz, Jörg; Cuniberti, Gianaurelio; Bley, Thomas; Weber, Jost

    2015-12-01

    Externally illuminated photobioreactors (PBRs) are widely used in studies on the use of phototrophic microorganisms as sources of bioenergy and other photobiotechnology research. In this work, straightforward simulation techniques were used to describe effects of varying fluid flow conditions in a continuous hydrogen-producing PBR on the rate of photofermentative hydrogen production (rH2 ) by Rhodobacter sphaeroides DSM 158. A ZEMAX optical ray tracing simulation was performed to quantify the illumination intensity reaching the interior of the cylindrical PBR vessel. 24.2% of the emitted energy was lost through optical effects, or did not reach the PBR surface. In a dense culture of continuously producing bacteria during chemostatic cultivation, the illumination intensity became completely attenuated within the first centimeter of the PBR radius as described by an empirical three-parametric model implemented in Mathcad. The bacterial movement in chemostatic steady-state conditions was influenced by varying the fluid Reynolds number. The "Computational Fluid Dynamics" and "Particle Tracing" tools of COMSOL Multiphysics were used to visualize the fluid flow pattern and cellular trajectories through well-illuminated zones near the PBR periphery and dark zones in the center of the PBR. A moderate turbulence (Reynolds number = 12,600) and fluctuating illumination of 1.5 Hz were found to yield the highest continuous rH2 by R. sphaeroides DSM 158 (170.5 mL L(-1) h(-1) ) in this study. © 2015 Wiley Periodicals, Inc.

  2. Dynamics of hydrogen-producing bacteria in a repeated batch fermentation process using lake sediment as inoculum.

    Science.gov (United States)

    Romano, Stefano; Paganin, Patrizia; Varrone, Cristiano; Tabacchioni, Silvia; Chiarini, Luigi

    2014-02-01

    In this study, we evaluated the effectiveness of lake sediment as inoculum for hydrogen production through dark fermentation in a repeated batch process. In addition, we investigated the effect of heat treatment, applied to enrich hydrogen-producing bacteria, on the bacterial composition and metabolism. Denaturing gradient gel electrophoresis and molecular cloning, both performed using the 16S rDNA gene as target gene, were used to monitor the structure of the bacterial community. Hydrogen production and bacterial metabolism were analysed via gas chromatography and high-performance liquid chromatography. Both treated and non-treated inocula were able to produce high amounts of hydrogen. However, statistical analysis showed a clear difference in their bacterial composition and metabolism. The heat treatment favoured the growth of different Clostridia sp., in particular of Clostridium bifermentans, allowing the production of a constant amount of hydrogen over prolonged time. These cultures showed both butyrate and ethanol fermentation types. Absence of heat treatment allowed species belonging to the genera Bacillus, Sporolactobacillus and Massilia to outgrow Clostridia sp. with a reduction in hydrogen production and a significant metabolic change. Our data indicate that lake sediment harbours bacteria that can efficiently produce hydrogen over prolonged fermentation time. Moreover, we could show that the heat treatment stabilizes the bacterial community composition and the hydrogen production.

  3. Oxygen dynamics in photosynthetic membranes.

    Science.gov (United States)

    Savikhin, Sergei; Kihara, Shigeharu

    2008-03-01

    Production of oxygen by oxygenic photosynthetic organisms is expected to raise oxygen concentration within their photosynthetic membranes above normal aerobic values. These raised levels of oxygen may affect function of many proteins within photosynthetic cells. However, experiments on proteins in vitro are usually performed in aerobic (or anaerobic) conditions since the oxygen content of a membrane is not known. Using theory of diffusion and measured oxygen production rates we estimated the excess levels of oxygen in functioning photosynthetic cells. We show that for an individual photosynthetic cell suspended in water oxygen level is essentially the same as that for a non-photosynthetic sell. These data suggest that oxygen protection mechanisms may have evolved after the development of oxygenic photosynthesis in primitive bacteria and was driven by the overall rise of oxygen concentration in the atmosphere. Substantially higher levels of oxygen are estimated to occur in closely packed colonies of photosynthetic bacteria and in green leafs.

  4. Evolving a photosynthetic organelle

    Directory of Open Access Journals (Sweden)

    Nakayama Takuro

    2012-04-01

    Full Text Available Abstract The evolution of plastids from cyanobacteria is believed to represent a singularity in the history of life. The enigmatic amoeba Paulinella and its 'recently' acquired photosynthetic inclusions provide a fascinating system through which to gain fresh insight into how endosymbionts become organelles. The plastids, or chloroplasts, of algae and plants evolved from cyanobacteria by endosymbiosis. This landmark event conferred on eukaryotes the benefits of photosynthesis - the conversion of solar energy into chemical energy - and in so doing had a huge impact on the course of evolution and the climate of Earth 1. From the present state of plastids, however, it is difficult to trace the evolutionary steps involved in this momentous development, because all modern-day plastids have fully integrated into their hosts. Paulinella chromatophora is a unicellular eukaryote that bears photosynthetic entities called chromatophores that are derived from cyanobacteria and has thus received much attention as a possible example of an organism in the early stages of organellogenesis. Recent studies have unlocked the genomic secrets of its chromatophore 23 and provided concrete evidence that the Paulinella chromatophore is a bona fide photosynthetic organelle 4. The question is how Paulinella can help us to understand the process by which an endosymbiont is converted into an organelle.

  5. Photosynthetic fuel for heterologous enzymes

    DEFF Research Database (Denmark)

    Mellor, Silas Busck; Vavitsas, Konstantinos; Nielsen, Agnieszka Janina Zygadlo

    2017-01-01

    of reducing power. Recent work on the metabolic engineering of photosynthetic organisms has shown that the electron carriers such as ferredoxin and flavodoxin can be used to couple heterologous enzymes to photosynthetic reducing power. Because these proteins have a plethora of interaction partners and rely...... on electrostatically steered complex formation, they form productive electron transfer complexes with non-native enzymes. A handful of examples demonstrate channeling of photosynthetic electrons to drive the activity of heterologous enzymes, and these focus mainly on hydrogenases and cytochrome P450s. However......, competition from native pathways and inefficient electron transfer rates present major obstacles, which limit the productivity of heterologous reactions coupled to photosynthesis. We discuss specific approaches to address these bottlenecks and ensure high productivity of such enzymes in a photosynthetic...

  6. Newly discovered deep-branching marine plastid lineages are numerically rare but globally distributed

    Digital Repository Service at National Institute of Oceanography (India)

    Choi, C.J.; Bachy, C.; Jaeger, G.S.; Poirier, C.; Sudek, L.; Sarma, V.V.S.S.; Mahadevan, A.; Giovannoni, S.J.; Worden, A.Z.

    on the biological communities that carry out marine photosynthesis. Phytoplankton perform half of global biological CO2 uptake, fuel marine food chains, and include diverse eukaryotic algae that have photosynthetic organelles (plastids) acquired through multiple...

  7. Arsenic biomethylation by photosynthetic organisms

    Science.gov (United States)

    Ye, Jun; Rensing, Christopher; Rosen, Barry P.; Zhu, Yong-Guan

    2013-01-01

    Arsenic (As) is a ubiquitous element that is widespread in the environment and causes numerous health problems. Biomethylation of As has implications for its mobility and toxicity. Photosynthetic organisms may play a significant role in As geochemical cycling by methylating it to different As species, but little is known about the mechanisms of methylation. Methylated As species have been found in many photosynthetic organisms, and several arsenite S-adenosylmethionine (SAM) methyltransferases have been characterized in cyanobacteria and algae. However, higher plants may not have the ability to methylate As. Instead, methylated arsenicals in plants probably originate from microorganisms in soils and the rhizosphere. Here, we propose possible approaches for developing ‘smart’ photosynthetic organisms with an enhanced and sensitive biomethylation capacity for bioremediation and safer food. PMID:22257759

  8. Special issue of photosynthetic research

    NARCIS (Netherlands)

    Okamura, M.; Wraight, C.A.; van Grondelle, R.

    2014-01-01

    This Special Issue of Photosynthesis Research honors Louis M. N. Duysens, Roderick K. Clayton, and George Feher, three pioneering researchers whose work on bacterial photosynthesis laid much of the groundwork for our understanding of the role of the reaction center in photosynthetic light energy

  9. Special issue of photosynthetic research.

    Science.gov (United States)

    Okamura, Melvin; Wraight, Colin A; van Grondelle, Rienk

    2014-05-01

    This Special Issue of Photosynthesis Research honors Louis M. N. Duysens, Roderick K. Clayton, and George Feher, three pioneering researchers whose work on bacterial photosynthesis laid much of the groundwork for our understanding of the role of the reaction center in photosynthetic light energy conversion. Their key discoveries are briefly summarized and an overview of the special issue is presented.

  10. A comparison between fuel cells and other alternatives for marine electric power generation

    Directory of Open Access Journals (Sweden)

    Yousri M.A. Welaya

    2011-06-01

    Full Text Available The world is facing a challenge in meeting its needs for energy. Global energy consumption in the last half-century has increased very rapidly and is expected to continue to grow over the next 50 years. However, it is expected to see significant differences between the last 50 years and the next. This paper aims at introducing a good solution to replace or work with conventional marine power plants. This includes the use of fuel cell power plant operated with hydrogen produced through water electrolysis or hydrogen produced from natural gas, gasoline, or diesel fuels through steam reforming processes to mitigate air pollution from ships.

  11. Phytochromes in photosynthetically competent plants

    Energy Technology Data Exchange (ETDEWEB)

    Pratt, L.H.

    1990-07-01

    Plants utilize light as a source of information in photomorphogenesis and of free energy in photosynthesis, two processes that are interrelated in that the former serves to increase the efficiency with which plants can perform the latter. Only one pigment involved in photomorphogenesis has been identified unequivocally, namely phytochrome. The thrust of this proposal is to investigate this pigment and its mode(s) of action in photosynthetically competent plants. Our long term objective is to characterize phytochrome and its functions in photosynthetically competent plants from molecular, biochemical and cellular perspectives. It is anticipated that others will continue to contribute indirectly to these efforts at the physiological level. The ultimate goal will be to develop this information from a comparative perspective in order to learn whether the different phytochromes have significantly different physicochemical properties, whether they fulfill independent functions and if so what these different functions are, and how each of the different phytochromes acts at primary molecular and cellular levels.

  12. Flow of light energy in benthic photosynthetic microbial mats

    Energy Technology Data Exchange (ETDEWEB)

    Al-Najjar, Mohammad Ahmad A.

    2010-12-15

    The work in this thesis demonstrates the assessment of the energy budget inside microbial mat ecosystems, and the factors affecting light utilization efficiency. It presents the first balanced light energy budget for benthic microbial mat ecosystems, and shows how the budget and the spatial distribution of the local photosynthetic efficiencies within the euphotic zone depend on the absorbed irradiance (Jabs). The energy budget was dominated by heat dissipation on the expense of photosynthesis. The maximum efficiency of photosynthesis was at light limiting conditions When comparing three different marine benthic photosynthetic ecosystems (originated from Abu-Dhabi, Arctic, and Exmouth Gulf in Western Australia), differences in the efficiencies were calculated. The results demonstrated that the maximum efficiency depended on mat characteristics affecting light absorption and scattering; such as, photopigments ratio and distribution, and the structural organization of the photosynthetic organisms relative to other absorbing components of the ecosystem (i.e., EPS, mineral particles, detritus, etc.). The maximum efficiency decreased with increasing light penetration depth, and increased with increasing the accessory pigments (phycocyanin and fucoxanthin)/chlorophyll ratio. Spatial heterogeneity in photosynthetic efficiency, pigment distribution, as well as light acclimation in microbial mats originating from different geographical locations was investigated. We used a combined pigment imaging approach (variable chlorophyll fluorescence and hyperspectral imaging), and fingerprinting approach. For each mat, the photosynthetic activity was proportional to the local pigment concentration in the photic zone, but not for the deeper layers and between different mats. In each mat, yield of PSII and E1/2 (light acclimation) generally decreased in parallel with depth, but the gradients in both parameters varied greatly between samples. This mismatch between pigments concentration

  13. Changes in hydrogen production and polymer accumulation upon sulfur-deprivation in purple photosynthetic bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Melnicki, Matthew R. [Agricultural and Environmental Chemistry, University of California, 111 Koshland Hall, MC-3102, Berkeley, CA 94720 (United States); Eroglu, Ela [Plant and Microbial Biology, University of California, Berkeley, CA 94720-3102 (United States); Melis, Anastasios [Agricultural and Environmental Chemistry, University of California, 111 Koshland Hall, MC-3102, Berkeley, CA 94720 (United States); Plant and Microbial Biology, University of California, Berkeley, CA 94720-3102 (United States)

    2009-08-15

    The work investigated physiological conditions directing cellular metabolism toward either H{sub 2}-production or storage polymer accumulation in purple photosynthetic bacteria. Hydrogen-producing cultures of the purple anoxygenic photosynthetic bacterium Rhodospirillum rubrum were resuspended in media lacking sulfur (S) nutrients. S-deprived cultures displayed lack of growth, cessation of bacteriochlorophyll and protein accumulation, and inhibition of H{sub 2} evolution. Cell volume increased substantially and large amounts of polymer were found to accumulate extracellularly. Poly-{beta}-hydroxybutyrate (PHB) content increased about 3.5-fold within 24 h of S-deprivation. Most cells remained viable after 100 h of S-deprivation and cultures were capable of resuming growth and H{sub 2}-production when supplemented with sulfate. Transcript levels, protein amount, and activity of the nitrogenase enzyme, which are responsible for H{sub 2}-production, decreased with a halftime of about 15 h upon S-deprivation. In addition, the nitrogenase NifH subunits were modified by ADP-ribosylation, indicating post-translational inactivation. Comparative aconitase activity measurements of control and S-deprived cells failed to indicate a general stress to Fe-S proteins, as aconitase, a Fe-S protein in the citric acid cycle sensitive to oxidative stress, maintained activity throughout the course of the S-deprivation. In contrast to nifH transcriptional down-regulation, expression of cysK (encoding cysteine synthase) was upregulated in response to S-deprivation. The described physiology is not specific to R. rubrum, as Rhodobacter sphaeroides and Rhodopseudomonas palustris exhibited a similar response to S-deprivation. It is suggested that manipulation of the supply of S-nutrients may serve as a tool for the alternative production of H{sub 2} or PHB in purple photosynthetic bacteria, thus affording opportunities to design photobiological systems that serve in both energy conversion and

  14. Density Functional Theory and Car-Parrinello Molecular Dynamics Study of the Hydrogen-Producing Mechanism of the Co(dmgBF2)2and Co(dmgH)2Cobaloxime Complexes in Acetonitrile-Water Solvent.

    Science.gov (United States)

    Chen, Jinfan; Sit, Patrick H-L

    2017-05-11

    The catalytic hydrogen-producing processes of two prototypical cobaloxime catalysts, Co(dmgBF 2 ) 2 (dmgBF 2 = difluoroboryl-dimethylglyoxime) and Co(dmgH) 2 (dmgH = dimethylglyoxime), were studied by density functional theory (DFT) and Car-Parrinello molecular dynamics (CPMD) simulations in the explicit acetonitrile-water solvent. Our study demonstrates the key role of water molecules as shuttles to deliver protons to the cobalt active centers of these catalysts. However, the transfer of protons to the cobalt centers also competes with the diffusion of the proton away from the complex via the hydrogen bond network of water. Protons were found to react with the oxygen of the side group of Co(dmgH) 2 , while a similar reaction was not observed for Co(dmgBF 2 ) 2 . This explains the experimentally observed relative instability of Co(dmgH) 2 in the acidic medium. The rate-limiting step of the hydrogen-producing process was found to be the first proton transfer to the cobalt center for both cobaloxime complexes. Structural and electron population analysis was carried out to provide insight into the origin of the difference of the proton transfer free-energy barriers of these two cobalt complexes. Our study has contributed to the key microscopic understanding of the hydrogen-producing process by this class of catalysts.

  15. Photosynthetic light reactions at the gold interface

    NARCIS (Netherlands)

    Kamran, Muhammad

    2014-01-01

    In the project described in this thesis we studied a simple bio-electronic device for solar energy conversion by surface-assembly of photosynthetic pigment-protein complexes on a bare gold-electrode. Optical excitation of the photosynthetic pigments gives rise to charge separation in the so-called

  16. Anaerobic energy metabolism in unicellular photosynthetic eukaryotes.

    Science.gov (United States)

    Atteia, Ariane; van Lis, Robert; Tielens, Aloysius G M; Martin, William F

    2013-02-01

    Anaerobic metabolic pathways allow unicellular organisms to tolerate or colonize anoxic environments. Over the past ten years, genome sequencing projects have brought a new light on the extent of anaerobic metabolism in eukaryotes. A surprising development has been that free-living unicellular algae capable of photoautotrophic lifestyle are, in terms of their enzymatic repertoire, among the best equipped eukaryotes known when it comes to anaerobic energy metabolism. Some of these algae are marine organisms, common in the oceans, others are more typically soil inhabitants. All these species are important from the ecological (O(2)/CO(2) budget), biotechnological, and evolutionary perspectives. In the unicellular algae surveyed here, mixed-acid type fermentations are widespread while anaerobic respiration, which is more typical of eukaryotic heterotrophs, appears to be rare. The presence of a core anaerobic metabolism among the algae provides insights into its evolutionary origin, which traces to the eukaryote common ancestor. The predicted fermentative enzymes often exhibit an amino acid extension at the N-terminus, suggesting that these proteins might be compartmentalized in the cell, likely in the chloroplast or the mitochondrion. The green algae Chlamydomonas reinhardtii and Chlorella NC64 have the most extended set of fermentative enzymes reported so far. Among the eukaryotes with secondary plastids, the diatom Thalassiosira pseudonana has the most pronounced anaerobic capabilities as yet. From the standpoints of genomic, transcriptomic, and biochemical studies, anaerobic energy metabolism in C. reinhardtii remains the best characterized among photosynthetic protists. This article is part of a Special Issue entitled: The evolutionary aspects of bioenergetic systems. Copyright © 2012 Elsevier B.V. All rights reserved.

  17. The photosynthetic apparatus and its regulation in the aerobic gammaproteobacterium Congregibacter litoralis gen. nov., sp. nov.

    Directory of Open Access Journals (Sweden)

    Stefan Spring

    Full Text Available BACKGROUND: There is accumulating evidence that in some marine environments aerobic bacteriochlorophyll a-producing bacteria represent a significant part of the microbial population. The interaction of photosynthesis and carbon metabolism in these interesting bacteria is still largely unknown and requires further investigation in order to estimate their contribution to the marine carbon cycle. METHODOLOGY/PRINCIPAL FINDINGS: Here, we analyzed the structure, composition and regulation of the photosynthetic apparatus in the obligately aerobic marine gammaproteobacterium KT71(T. Photoheterotrophically grown cells were characterized by a poorly developed lamellar intracytoplasmic membrane system, a type 1 light-harvesting antenna complex and a photosynthetic reaction center associated with a tetraheme cytochrome c. The only photosynthetic pigments produced were bacteriochlorophyll a and spirilloxanthin. Under semiaerobic conditions KT71(T cells expressing a photosynthetic apparatus showed a light-dependent increase of growth yield in the range of 1.3-2.5 fold. The expression level of the photosynthetic apparatus depended largely on the utilized substrate, the intermediary carbon metabolism and oxygen tension. In addition, pigment synthesis was strongly influenced by light, with blue light exerting the most significant effect, implicating that proteins containing a BLUF domain may be involved in regulation of the photosynthetic apparatus. Several phenotypic traits in KT71(T could be identified that correlated with the assumed redox state of growing cells and thus could be used to monitor the cellular redox state under various incubation conditions. CONCLUSIONS/SIGNIFICANCE: In a hypothetical model that explains the regulation of the photosynthetic apparatus in strain KT71(T we propose that the expression of photosynthesis genes depends on the cellular redox state and is maximal under conditions that allow a balanced membrane redox state. So far

  18. Bioprospecting Marine Plankton

    Directory of Open Access Journals (Sweden)

    Chris Bowler

    2013-11-01

    Full Text Available The ocean dominates the surface of our planet and plays a major role in regulating the biosphere. For example, the microscopic photosynthetic organisms living within provide 50% of the oxygen we breathe, and much of our food and mineral resources are extracted from the ocean. In a time of ecological crisis and major changes in our society, it is essential to turn our attention towards the sea to find additional solutions for a sustainable future. Remarkably, while we are overexploiting many marine resources, particularly the fisheries, the planktonic compartment composed of zooplankton, phytoplankton, bacteria and viruses, represents 95% of marine biomass and yet the extent of its diversity remains largely unknown and underexploited. Consequently, the potential of plankton as a bioresource for humanity is largely untapped. Due to their diverse evolutionary backgrounds, planktonic organisms offer immense opportunities: new resources for medicine, cosmetics and food, renewable energy, and long-term solutions to mitigate climate change. Research programs aiming to exploit culture collections of marine micro-organisms as well as to prospect the huge resources of marine planktonic biodiversity in the oceans are now underway, and several bioactive extracts and purified compounds have already been identified. This review will survey and assess the current state-of-the-art and will propose methodologies to better exploit the potential of marine plankton for drug discovery and for dermocosmetics.

  19. Bioprospecting marine plankton.

    Science.gov (United States)

    Abida, Heni; Ruchaud, Sandrine; Rios, Laurent; Humeau, Anne; Probert, Ian; De Vargas, Colomban; Bach, Stéphane; Bowler, Chris

    2013-11-14

    The ocean dominates the surface of our planet and plays a major role in regulating the biosphere. For example, the microscopic photosynthetic organisms living within provide 50% of the oxygen we breathe, and much of our food and mineral resources are extracted from the ocean. In a time of ecological crisis and major changes in our society, it is essential to turn our attention towards the sea to find additional solutions for a sustainable future. Remarkably, while we are overexploiting many marine resources, particularly the fisheries, the planktonic compartment composed of zooplankton, phytoplankton, bacteria and viruses, represents 95% of marine biomass and yet the extent of its diversity remains largely unknown and underexploited. Consequently, the potential of plankton as a bioresource for humanity is largely untapped. Due to their diverse evolutionary backgrounds, planktonic organisms offer immense opportunities: new resources for medicine, cosmetics and food, renewable energy, and long-term solutions to mitigate climate change. Research programs aiming to exploit culture collections of marine micro-organisms as well as to prospect the huge resources of marine planktonic biodiversity in the oceans are now underway, and several bioactive extracts and purified compounds have already been identified. This review will survey and assess the current state-of-the-art and will propose methodologies to better exploit the potential of marine plankton for drug discovery and for dermocosmetics.

  20. Bioprospecting Marine Plankton

    Science.gov (United States)

    Abida, Heni; Ruchaud, Sandrine; Rios, Laurent; Humeau, Anne; Probert, Ian; De Vargas, Colomban; Bach, Stéphane; Bowler, Chris

    2013-01-01

    The ocean dominates the surface of our planet and plays a major role in regulating the biosphere. For example, the microscopic photosynthetic organisms living within provide 50% of the oxygen we breathe, and much of our food and mineral resources are extracted from the ocean. In a time of ecological crisis and major changes in our society, it is essential to turn our attention towards the sea to find additional solutions for a sustainable future. Remarkably, while we are overexploiting many marine resources, particularly the fisheries, the planktonic compartment composed of zooplankton, phytoplankton, bacteria and viruses, represents 95% of marine biomass and yet the extent of its diversity remains largely unknown and underexploited. Consequently, the potential of plankton as a bioresource for humanity is largely untapped. Due to their diverse evolutionary backgrounds, planktonic organisms offer immense opportunities: new resources for medicine, cosmetics and food, renewable energy, and long-term solutions to mitigate climate change. Research programs aiming to exploit culture collections of marine micro-organisms as well as to prospect the huge resources of marine planktonic biodiversity in the oceans are now underway, and several bioactive extracts and purified compounds have already been identified. This review will survey and assess the current state-of-the-art and will propose methodologies to better exploit the potential of marine plankton for drug discovery and for dermocosmetics. PMID:24240981

  1. Environmental influence on photosynthetic efficiency

    Science.gov (United States)

    Zilinskas, Barbara A.

    Photosynthesis is arguably the single most important metabolic process on earth. Through a series of reactions, ranging from 10-15 sec for absorption of light to 106 sec for primary productivity of a field crop, atmospheric CO2 is assimilated into carbohydrate necessary for the sustenance of all life forms. The process involves movement of electrons from water to CO2 through a series of charge transfer reactions. The ultimate source of energy to drive these reactions is solar energy absorbed by a collection of light-harvesting pigment-proteins and specialized reaction centers. Approximately half of the solar irradiance is useful in photosynthesis, but of this only 2-3% is converted into organic matter. Usually, light does not limit photosynthesis, but other environmental factors do, most often CO2 and water availability. Three different biochemical pathways for CO2 assimilation have independently evolved. These provide C3, C4 and CAM plants (names designating the different means of assimilating CO2) with adaptive advantages under the various environmental conditions encountered by plants in nature. Our current understanding of the photosynthetic light and carbon-fixing reactions now permits a closer look at responses of photosynthesis to changes in the environment, particularly with regard to making predictive models for absolute efficiencies of light, CO2 and water utilization.

  2. Difference in photosynthetic performance among three peach ...

    African Journals Online (AJOL)

    RuBPCase), Ca2+- adenosinetriphosphatase (Ca2+-ATPase) and Mg2+- adenosine triphosphatase (Mg2+-ATPase) activities, together with nicotinamide adenine dinucleotide phosphate (NADPH) content and photosynthetic O2 evolution rate ...

  3. Design principles of photosynthetic light-harvesting.

    Science.gov (United States)

    Fleming, Graham R; Schlau-Cohen, Gabriela S; Amarnath, Kapil; Zaks, Julia

    2012-01-01

    Photosynthetic organisms are capable of harvesting solar energy with near unity quantum efficiency. Even more impressively, this efficiency can be regulated in response to the demands of photosynthetic reactions and the fluctuating light-levels of natural environments. We discuss the distinctive design principles through which photosynthetic light-harvesting functions. These emergent properties of photosynthesis appear both within individual pigment-protein complexes and in how these complexes integrate to produce a functional, regulated apparatus that drives downstream photochemistry. One important property is how the strong interactions and resultant quantum coherence, produced by the dense packing of photosynthetic pigments, provide a tool to optimize for ultrafast, directed energy transfer. We also describe how excess energy is quenched to prevent photodamage under high-light conditions, which we investigate through theory and experiment. We conclude with comments on the potential of using these features to improve solar energy devices.

  4. Hybrid system of semiconductor and photosynthetic protein

    Science.gov (United States)

    Kim, Younghye; Shin, Seon Ae; Lee, Jaehun; Yang, Ki Dong; Nam, Ki Tae

    2014-08-01

    Photosynthetic protein has the potential to be a new attractive material for solar energy absorption and conversion. The development of semiconductor/photosynthetic protein hybrids is an example of recent progress toward efficient, clean and nanostructured photoelectric systems. In the review, two biohybrid systems interacting through different communicating methods are addressed: (1) a photosynthetic protein immobilized semiconductor electrode operating via electron transfer and (2) a hybrid of semiconductor quantum dots and photosynthetic protein operating via energy transfer. The proper selection of materials and functional and structural modification of the components and optimal conjugation between them are the main issues discussed in the review. In conclusion, we propose the direction of future biohybrid systems for solar energy conversion systems, optical biosensors and photoelectric devices.

  5. Separation, identification and quantification of photosynthetic ...

    African Journals Online (AJOL)

    Thirty one photosynthetic pigments (chlorophylls, carotenoids and degradation products) from the seaweeds, Codium dwarkense, (Chlorophyta), , Laurencia obtusa , (Rhodophyta) and , Lobophora variegata, (Phaeophyta), were separated in a single-step procedure by reversed phase high-performance liquid ...

  6. Metagenomic and PCR-based diversity surveys of [FeFe]-hydrogenases combined with isolation of alkaliphilic hydrogen-producing bacteria from the serpentinite-hosted Prony hydrothermal field, New Caledonia

    Directory of Open Access Journals (Sweden)

    Nan Mei

    2016-08-01

    Full Text Available High amounts of hydrogen are emitted in the serpentinite-hosted hydrothermal field of the Prony Bay (PHF, New Caledonia, where high-pH (~11, low-temperature (<40°C and low-salinity fluids are discharged in both intertidal and shallow submarine environments. In this study, we investigated the diversity and distribution of potentially hydrogen-producing bacteria in Prony hyperalkaline springs by using metagenomic analyses and different PCR-amplified DNA sequencing methods. The retrieved sequences of hydA genes, encoding the catalytic subunit of [FeFe]-hydrogenases and, used as a molecular marker of hydrogen-producing bacteria, were mainly related to those of Firmicutes and clustered into two distinct groups depending on sampling locations. Intertidal samples were dominated by new hydA sequences related to uncultured Firmicutes retrieved from paddy soils, while submarine samples were dominated by diverse hydA sequences affiliated with anaerobic and/or thermophilic submarine Firmicutes pertaining to the orders Thermoanaerobacterales or Clostridiales. The novelty and diversity of these [FeFe]-hydrogenases may reflect the unique environmental conditions prevailing in the PHF (i.e. high-pH, low-salt, mesothermic fluids. In addition, novel alkaliphilic hydrogen-producing Firmicutes (Clostridiales and Bacillales were successfully isolated from both intertidal and submarine PHF chimney samples. Both molecular and cultivation-based data demonstrated the ability of Firmicutes originating from serpentinite-hosted environments to produce hydrogen by fermentation, potentially contributing to the molecular hydrogen balance in situ.

  7. Biohydrogen production by isolated halotolerant photosynthetic bacteria using long-wavelength light-emitting diode (LW-LED)

    Energy Technology Data Exchange (ETDEWEB)

    Kawagoshi, Yasunori; Oki, Yukinori; Nakano, Issei; Fujimoto, Aya [Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555 (Japan); Takahashi, Hirokazu [Environmental Business DivisionDaiki Ataka Engineering Co. Ltd., 2-1-9 Nishiku-Urihori, Osaka 550-0012 (Japan)

    2010-12-15

    Biohydrogen is expected as one of the alternative energy to fossil fuel. In this study, halotolerant photosynthetic hydrogen producing bacteria (ht-PHB) were isolated from a sediment of tideland, and hydrogen gas (H{sub 2}) production by isolated ht-PHB from mixed short-chain fatty acids (SFAs) using a long-wavelength light emitting diode (LW-LED) was investigated. The isolated ht-PHB grow on a culture containing three kinds of SFAs (lactic acid, acetic acid, butyric acid) and produced H{sub 2} with their complete consumption at NaCl concentration in the 0-3% range in the light of tungsten lamp. The isolated ht-PHB was phylogenetically identified as Rhodobacter sp. KUPB1. The KUPB1 showed well growth and H{sub 2} production even under LW-LED light irradiation, indicating that LW-LED is quite useful as an energy-saving light source for photosynthetic H{sub 2} production. (author)

  8. Metagenomic and PCR-Based Diversity Surveys of [FeFe]-Hydrogenases Combined with Isolation of Alkaliphilic Hydrogen-Producing Bacteria from the Serpentinite-Hosted Prony Hydrothermal Field, New Caledonia.

    Science.gov (United States)

    Mei, Nan; Postec, Anne; Monnin, Christophe; Pelletier, Bernard; Payri, Claude E; Ménez, Bénédicte; Frouin, Eléonore; Ollivier, Bernard; Erauso, Gaël; Quéméneur, Marianne

    2016-01-01

    High amounts of hydrogen are emitted in the serpentinite-hosted hydrothermal field of the Prony Bay (PHF, New Caledonia), where high-pH (~11), low-temperature (Prony hyperalkaline springs by using metagenomic analyses and different PCR-amplified DNA sequencing methods. The retrieved sequences of hydA genes, encoding the catalytic subunit of [FeFe]-hydrogenases and, used as a molecular marker of hydrogen-producing bacteria, were mainly related to those of Firmicutes and clustered into two distinct groups depending on sampling locations. Intertidal samples were dominated by new hydA sequences related to uncultured Firmicutes retrieved from paddy soils, while submarine samples were dominated by diverse hydA sequences affiliated with anaerobic and/or thermophilic submarine Firmicutes pertaining to the orders Thermoanaerobacterales or Clostridiales. The novelty and diversity of these [FeFe]-hydrogenases may reflect the unique environmental conditions prevailing in the PHF (i.e., high-pH, low-salt, mesothermic fluids). In addition, novel alkaliphilic hydrogen-producing Firmicutes (Clostridiales and Bacillales) were successfully isolated from both intertidal and submarine PHF chimney samples. Both molecular and cultivation-based data demonstrated the ability of Firmicutes originating from serpentinite-hosted environments to produce hydrogen by fermentation, potentially contributing to the molecular hydrogen balance in situ.

  9. Iron utilization in marine cyanobacteria and eukaryotic algae

    Directory of Open Access Journals (Sweden)

    Joe eMorrissey

    2012-03-01

    Full Text Available Iron is essential for aerobic organisms. Additionally, photosynthetic organisms must maintain the iron-rich photosynthetic electron transport chain, which likely evolved in the iron-replete Proterozoic ocean. The subsequent rise in oxygen since those times has drastically decreased the levels of bioavailable iron, indicating that adaptations have been made to maintain sufficient cellular iron levels in the midst of scarcity. In combination with physiological studies, the recent sequencing of marine microorganism genomes and transcriptomes has begun to reveal the mechanisms of iron acquisition and utilization that allow marine microalgae to persist in iron-limited environments.

  10. Iron utilization in marine cyanobacteria and eukaryotic algae.

    Science.gov (United States)

    Morrissey, Joe; Bowler, Chris

    2012-01-01

    Iron is essential for aerobic organisms. Additionally, photosynthetic organisms must maintain the iron-rich photosynthetic electron transport chain, which likely evolved in the iron-replete Proterozoic ocean. The subsequent rise in oxygen since those times has drastically decreased the levels of bioavailable iron, indicating that adaptations have been made to maintain sufficient cellular iron levels in the midst of scarcity. In combination with physiological studies, the recent sequencing of marine microorganism genomes and transcriptomes has begun to reveal the mechanisms of iron acquisition and utilization that allow marine microalgae to persist in iron limited environments.

  11. Estimation of oxygen evolution by marine phytoplankton from measurement of the efficiency of Photosystem II electron flow.

    NARCIS (Netherlands)

    Geel, C.; Versluis, W.; Snel, J.F.H.

    1997-01-01

    The relation between photosynthetic oxygen evolution and Photosystem II electron transport was investigated for the marine algae t Phaeodactylum tricornutum, Dunaliella tertiolecta, Tetraselmis sp., t Isochrysis sp. and t Rhodomonas sp.. The rate of Photosystem II electron transport was estimated

  12. Ultrafast fluorescence of photosynthetic crystals and light-harvesting complexes

    NARCIS (Netherlands)

    Oort, van B.F.

    2008-01-01

    This thesis focuses on the study of photosynthetic pigment protein complexes using time resolved fluorescence techniques. Fluorescence spectroscopy often requires attaching fluorescent labels to the proteins under investigation. With photosynthetic proteins this is not necessary, because these

  13. Photosynthetic capacity of red spruce during winter

    Science.gov (United States)

    P.G. Schaberg; J.B. Shane; P.F. Cali; J.R. Donnelly; G.R. Strimbeck

    1998-01-01

    We measured the photosynthetic capacity (Pmax) of plantation-grown red spruce (Picea rubens Sarg.) during two winter seasons (1993-94 and 1994-95) and monitored field photosynthesis of these trees during one winter (1993-94). We also measured Pmax for mature montane trees from January through May 1995....

  14. Chemiosmotic coupling in oxidative and photosynthetic phosphorylation

    National Research Council Canada - National Science Library

    Mitchell, Peter

    2011-01-01

    ... in oxidative phosphorylation in mitochondria is that, for the equivalent of each pair of electrons traversing the respiratory chain, up to 3 anhydrobond equivalents may normally traverse the h/d pathway from adenosine diphosphate plus inorganic phosphate (ADP + P i ) to water. In photosynthetic phosphorylation the stoichiometry is less certain, and it is thought...

  15. Photosynthetic characteristics of Lycoris aurea and monthly ...

    African Journals Online (AJOL)

    AJL

    2012-02-21

    Feb 21, 2012 ... Medicinal Plant Resources, Key Laboratory of Hunan Higher Education for Hunan-western Medicinal Plant and. Ethnobotany ... lycorine and galantamine during the annual growth period were studied by using LI-6400 portable photosynthetic ... ingredients of several medicinal plants. Their production.

  16. Photosynthetic antenna engineering to improve crop yields.

    Science.gov (United States)

    Kirst, Henning; Gabilly, Stéphane T; Niyogi, Krishna K; Lemaux, Peggy G; Melis, Anastasios

    2017-05-01

    Evidence shows that decreasing the light-harvesting antenna size of the photosystems in tobacco helps to increase the photosynthetic productivity and plant canopy biomass accumulation under high-density cultivation conditions. Decreasing, or truncating, the chlorophyll antenna size of the photosystems can theoretically improve photosynthetic solar energy conversion efficiency and productivity in mass cultures of algae or plants by up to threefold. A Truncated Light-harvesting chlorophyll Antenna size (TLA), in all classes of photosynthetic organisms, would help to alleviate excess absorption of sunlight and the ensuing wasteful non-photochemical dissipation of excitation energy. Thus, solar-to-biomass energy conversion efficiency and photosynthetic productivity in high-density cultures can be increased. Applicability of the TLA concept was previously shown in green microalgae and cyanobacteria, but it has not yet been demonstrated in crop plants. In this work, the TLA concept was applied in high-density tobacco canopies. The work showed a 25% improvement in stem and leaf biomass accumulation for the TLA tobacco canopies over that measured with their wild-type counterparts grown under the same ambient conditions. Distinct canopy appearance differences are described between the TLA and wild type tobacco plants. Findings are discussed in terms of concept application to crop plants, leading to significant improvements in agronomy, agricultural productivity, and application of photosynthesis for the generation of commodity products in crop leaves.

  17. Photosynthetic performance, epiphyte biomass and nutrient content ...

    African Journals Online (AJOL)

    Heavy nutrient loads in coastal waters often lead to excessive growth of microalgal and macroalgal epiphytes on seagrass leaves, with varying effects on the underlying seagrasses. This study evaluates the photosynthetic performance, epiphytic biomass and tissue nutrient content of two tropical seagrasses, Cymodocea ...

  18. Effects of ultraviolet radiation on photosynthetic performance and N2 fixation in Trichodesmium erythraeum IMS 101

    Science.gov (United States)

    Cai, Xiaoni; Hutchins, David A.; Fu, Feixue; Gao, Kunshan

    2017-10-01

    Biological effects of ultraviolet radiation (UVR; 280-400 nm) on marine primary producers are of general concern, as oceanic carbon fixers that contribute to the marine biological CO2 pump are being exposed to increasing UV irradiance due to global change and ozone depletion. We investigated the effects of UV-B (280-320 nm) and UV-A (320-400 nm) on the biogeochemically critical filamentous marine N2-fixing cyanobacterium Trichodesmium (strain IMS101) using a solar simulator as well as under natural solar radiation. Short exposure to UV-B, UV-A, or integrated total UVR significantly reduced the effective quantum yield of photosystem II (PSII) and photosynthetic carbon and N2 fixation rates. Cells acclimated to low light were more sensitive to UV exposure compared to high-light-grown ones, which had more UV-absorbing compounds, most likely mycosporine-like amino acids (MAAs). After acclimation under natural sunlight, the specific growth rate was lower (by up to 44 %), MAA content was higher, and average trichome length was shorter (by up to 22 %) in the full spectrum of solar radiation with UVR, than under a photosynthetically active radiation (PAR) alone treatment (400-700 nm). These results suggest that prior shipboard experiments in UV-opaque containers may have substantially overestimated in situ nitrogen fixation rates by Trichodesmium, and that natural and anthropogenic elevation of UV radiation intensity could significantly inhibit this vital source of new nitrogen to the current and future oligotrophic oceans.

  19. Marine Science

    African Journals Online (AJOL)

    Aims and scope: The Western Indian Ocean Journal of Marine Science ... Topics include, but are not limited to: theoretical studies, oceanography, marine biology and ... While no populations of seals are resident in the tropical Indian Ocean, ...

  20. Marine Science

    African Journals Online (AJOL)

    Aims and scope: The Western Indian Ocean Journal of Marine Science provides an avenue ... Topics include, but are not limited to: theoretical studies, oceanography, marine biology and ecology, .... population of Chumbe Island Coral Park,.

  1. Regulation of photosynthetic carbon fixation on the ocean margins. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Paul, J.H.

    1997-06-01

    The US Department of Energy is concerned with the fate of energy-related materials, including carbon dioxide, in the marine environment. Using laboratory studies, as well as field studies, an attempt was made to understand the molecular regulation of photosynthetic carbon reduction. The objectives were: to determine the mechanism of regulation of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCase) in phytoplankton in response to changes in light fields; and to determine regulation of (RuBPCase) in response to light under nutrient deprivation.

  2. Marine Science

    African Journals Online (AJOL)

    sustainable coastal development in the region, as well as contributing to the global base of marine science. The journal publishes original research articles dealing with all aspects of marine science and coastal manage- ment. Topics include, but are not limited to: theoretical studies, oceanography, marine biology and ...

  3. Marine Science

    African Journals Online (AJOL)

    sustainable use of coastal and marine resources. This is central to the goal of supporting and promoting sustainable coastal development in the region, as well as contributing to the global base of marine science. The journal publishes original research articles dealing with all aspects of marine science and coastal manage-.

  4. Artificial photosynthetic systems for production of hydrogen.

    Science.gov (United States)

    Fukuzumi, Shunichi

    2015-04-01

    The rapid consumption of fossil fuels has caused unacceptable environmental problems such as the greenhouse effect, which may lead to disastrous climatic consequences. Because fossil fuels are the products of long-term photosynthesis, it is highly desirable to develop artificial photosynthetic systems for the production of renewable and clean energy such as hydrogen. This article summarizes recent advances on studies of artificial photosynthetic systems for photocatalytic production of hydrogen with hydrogenases and their functional mimics including hybrids of natural and artificial components. Because it is highly desired to convert gaseous H2 to an easily storable form, recent progress on storage of hydrogen as liquid or solid form has also been described in this article. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. Correlated interaction fluctuations in photosynthetic complexes

    CERN Document Server

    Vlaming, Sebastiaan M

    2011-01-01

    The functioning and efficiency of natural photosynthetic complexes is strongly influenced by their embedding in a noisy protein environment, which can even serve to enhance the transport efficiency. Interactions with the environment induce fluctuations of the transition energies of and interactions between the chlorophyll molecules, and due to the fact that different fluctuations will partially be caused by the same environmental factors, correlations between the various fluctuations will occur. We argue that fluctuations of the interactions should in general not be neglected, as these have a considerable impact on population transfer rates, decoherence rates and the efficiency of photosynthetic complexes. Furthermore, while correlations between transition energy fluctuations have been studied, we provide the first quantitative study of the effect of correlations between interaction fluctuations and transition energy fluctuations, and of correlations between the various interaction fluctuations. It is shown t...

  6. Coral bleaching independent of photosynthetic activity.

    Science.gov (United States)

    Tolleter, Dimitri; Seneca, François O; DeNofrio, Jan C; Krediet, Cory J; Palumbi, Stephen R; Pringle, John R; Grossman, Arthur R

    2013-09-23

    The global decline of reef-building corals is due in part to the loss of algal symbionts, or "bleaching," during the increasingly frequent periods of high seawater temperatures. During bleaching, endosymbiotic dinoflagellate algae (Symbiodinium spp.) either are lost from the animal tissue or lose their photosynthetic pigments, resulting in host mortality if the Symbiodinium populations fail to recover. The >1,000 studies of the causes of heat-induced bleaching have focused overwhelmingly on the consequences of damage to algal photosynthetic processes, and the prevailing model for bleaching invokes a light-dependent generation of toxic reactive oxygen species (ROS) by heat-damaged chloroplasts as the primary trigger. However, the precise mechanisms of bleaching remain unknown, and there is evidence for involvement of multiple cellular processes. In this study, we asked the simple question of whether bleaching can be triggered by heat in the dark, in the absence of photosynthetically derived ROS. We used both the sea anemone model system Aiptasia and several species of reef-building corals to demonstrate that symbiont loss can occur rapidly during heat stress in complete darkness. Furthermore, we observed damage to the photosynthetic apparatus under these conditions in both Aiptasia endosymbionts and cultured Symbiodinium. These results do not directly contradict the view that light-stimulated ROS production is important in bleaching, but they do show that there must be another pathway leading to bleaching. Elucidation of this pathway should help to clarify bleaching mechanisms under the more usual conditions of heat stress in the light. Copyright © 2013 Elsevier Ltd. All rights reserved.

  7. Nonclassical energy transfer in photosynthetic FMO complex

    Directory of Open Access Journals (Sweden)

    Abramavicius Vytautas

    2013-03-01

    Full Text Available Excitation energy transfer in a photosynthetic FMO complex has been simulated using the stochastic Schrödinger equation. Fluctuating chromophore transition energies are simulated from the quantum correlation function which allows to properly include the finite temperature. The resulting excitation dynamics shows fast thermalization of chromophore occupations into proper thermal equilibrium. The relaxation process is characterized by entropy dynamics, which shows nonclassical behavior.

  8. ENHANCED PRACTICAL PHOTOSYNTHETIC CO2 MITIGATION

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Gregory Kremer; Dr. David J. Bayless; Dr. Morgan Vis; Dr. Michael Prudich; Dr. Keith Cooksey; Dr. Jeff Muhs

    2003-04-15

    This quarterly report documents significant achievements in the Enhanced Practical Photosynthetic CO{sub 2} Mitigation project during the period from 1/2/2003 through 4/01/2003. As indicated in the list of accomplishments below we are progressing with long-term model scale bioreactor tests and are completing final preparations for pilot scale bioreactor testing. Specific results and accomplishments for the first quarter of 2003 are included.

  9. Detection of the clostridial hydrogenase gene activity as a bio-index in a molasses wastewater bio-hydrogen producing system by real time PCR and FISH/ flow cytometry

    Energy Technology Data Exchange (ETDEWEB)

    Jui-Jen Chang; Ping-Chi Hsu; Chi-Wa Choi; Sian-Jhong Yu; Cheng-Yu Ho; Wei-En Chen; Jiunn-Jyi Lay; Chieh-Chen Huang; Fu-Shyan Wen [Department of Life Sciences, National Chung Hsing University, Taichung, 40227, Taiwan (China)

    2006-07-01

    Hydrogenase is a key enzyme that is used by obligate, anaerobic clostridial to produce hydrogen. In this study a fermentative system with molasses wastewater as nutrient was used to produce hydrogen. For establishing the relationship between the vicissitude of clostridial hydrogenase gene activity and the hydrogen production of this system during the culturing period, total cellular RNA isolated at different growing stages were subjected to real time PCR using primer pair, which were designed according to the conserved sequence of clostridial hydrogenase genes. Cell samples at corresponding growing stages were subjected to in situ reverse transcriptase polymerase chain reaction (in situ RT-PCR) using the same primers and then to fluorescence in situ hybridization (FISH) using clostridial hydrogenase gene-specific DNA probe. Those clostridial cells expressed hydrogenase gene activity could be detected by fluorescence microscopy. This is the first time hydrogen-producing activity in a mixed culture could be successfully studied by means of FISH of hydrogenase mRNA. Besides, 16S rDNA was amplified from total cellular DNA analyzed by denaturing gradient gel electrophoresis (DGGE) to reveal the bacterial diversity in the fermentative system; FISH and flow cytometry aiming at 16S rRNA were also carried out to calculate the population of clostridia and total eubacteria in the system. (authors)

  10. Marine genomics

    DEFF Research Database (Denmark)

    Oliveira Ribeiro, Ângela Maria; Foote, Andrew David; Kupczok, Anne

    2017-01-01

    evolutionary biology of non-model organisms to species of commercial relevance for fishing, aquaculture and biomedicine. Instead of providing an exhaustive list of available genomic data, we rather set to present contextualized examples that best represent the current status of the field of marine genomics.......Marine ecosystems occupy 71% of the surface of our planet, yet we know little about their diversity. Although the inventory of species is continually increasing, as registered by the Census of Marine Life program, only about 10% of the estimated two million marine species are known. This lag......-throughput sequencing approaches have been helping to improve our knowledge of marine biodiversity, from the rich microbial biota that forms the base of the tree of life to a wealth of plant and animal species. In this review, we present an overview of the applications of genomics to the study of marine life, from...

  11. Influence of the quantity and quality of light on photosynthetic periodicity in coral endosymbiotic algae.

    Directory of Open Access Journals (Sweden)

    Michal Sorek

    Full Text Available Symbiotic corals, which are benthic organisms intimately linked with their environment, have evolved many ways to deal with fluctuations in the local marine environment. One possible coping mechanism is the endogenous circadian clock, which is characterized as free running, maintaining a ~24 h periodicity of circuits under constant stimuli or in the absence of external cues. The quantity and quality of light were found to be the most influential factors governing the endogenous clock for plants and algae. Unicellular dinoflagellate algae are among the best examples of organisms that exhibit circadian clocks using light as the dominant signal. This study is the first to examine the effects of light intensity and quality on the rhythmicity of photosynthesis in the symbiotic dinoflagellate Symbiodinium sp., both as a free-living organism and in symbiosis with the coral Stylophora pistillata. Oxygen production measurements in Symbiodinium cultures exhibited rhythmicity with a periodicity of approximately 24 h under constant high light (LL, whereas under medium and low light, the cycle time increased. Exposing Symbiodinium cultures and corals to spectral light revealed different effects of blue and red light on the photosynthetic rhythm, specifically shortening or increasing the cycle time respectively. These findings suggest that the photosynthetic rhythm is entrained by different light cues, which are wired to an endogenous circadian clock. Furthermore, we provide evidence that mRNA expression was higher under blue light for two potential cryptochrome genes and higher under red light for a phytochrome gene isolated from Symbiodinium. These results offer the first evidence of the impact of the intensity and quality of light on the photosynthetic rhythm in algal cells living freely or as part of a symbiotic association. Our results indicate the presence of a circadian oscillator in Symbiodinium governing the photosynthetic apparatus through a light

  12. Variability in photosynthetic production of dissolved and particulate organic carbon in the North Pacific Subtropical Gyre

    Directory of Open Access Journals (Sweden)

    Donn A. Viviani

    2015-10-01

    Full Text Available The partitioning of photosynthetically-derived organic carbon between particulate and dissolved phases has important implications for marine carbon cycling. In this study we utilized 14C-bicarbonate assimilation to quantify rates of photosynthetic production of both particulate and dissolved organic carbon (DOC at Station ALOHA (22˚45’N, 158˚W in the North Pacific Subtropical Gyre (NPSG. At near-monthly time scales over ~5 years, we examined retention of 14C-labeled organic matter by both glass fiber filters and 0.2 µm pore size polycarbonate membrane filters that are commonly used for measurements of 14C-based plankton productivity. Use of polycarbonate filters resulted in significantly lower (averaging 60% estimates of 14C-production compared to glass fiber filters. Coincident measurements of chlorophyll a concentrations from both 0.2 µm polycarbonate and glass fiber filters were not significantly different, suggesting the differences in 14C-productivity between these filter-types did not derive from differences in retention of photosynthetic biomass by these filters. Moreover, consistent with previous studies, results from experiments aimed at quantifying retention of organic matter by these filters suggested the difference between these two types of filters resulted from retention of DOC by glass fiber filters. We also quantified rates of 14C-DOC production to evaluate the partitioning of photosynthetic production between dissolved and particulate phases over daily to monthly time scales in this ecosystem. Unlike the strong depth-dependence observed in measurements of particulate organic carbon production, measured rates of 14C-DOC demonstrated no clear depth-dependence. On average, depth-integrated (0-75 m rates of 14C-DOC production rates were equivalent to 18 ± 10% of the total (particulate and dissolved productivity. Our findings indicate that in this oligotrophic ecosystem, rates of dissolved and particulate production can be

  13. Influence of the quantity and quality of light on photosynthetic periodicity in coral endosymbiotic algae.

    Science.gov (United States)

    Sorek, Michal; Levy, Oren

    2012-01-01

    Symbiotic corals, which are benthic organisms intimately linked with their environment, have evolved many ways to deal with fluctuations in the local marine environment. One possible coping mechanism is the endogenous circadian clock, which is characterized as free running, maintaining a ~24 h periodicity of circuits under constant stimuli or in the absence of external cues. The quantity and quality of light were found to be the most influential factors governing the endogenous clock for plants and algae. Unicellular dinoflagellate algae are among the best examples of organisms that exhibit circadian clocks using light as the dominant signal. This study is the first to examine the effects of light intensity and quality on the rhythmicity of photosynthesis in the symbiotic dinoflagellate Symbiodinium sp., both as a free-living organism and in symbiosis with the coral Stylophora pistillata. Oxygen production measurements in Symbiodinium cultures exhibited rhythmicity with a periodicity of approximately 24 h under constant high light (LL), whereas under medium and low light, the cycle time increased. Exposing Symbiodinium cultures and corals to spectral light revealed different effects of blue and red light on the photosynthetic rhythm, specifically shortening or increasing the cycle time respectively. These findings suggest that the photosynthetic rhythm is entrained by different light cues, which are wired to an endogenous circadian clock. Furthermore, we provide evidence that mRNA expression was higher under blue light for two potential cryptochrome genes and higher under red light for a phytochrome gene isolated from Symbiodinium. These results offer the first evidence of the impact of the intensity and quality of light on the photosynthetic rhythm in algal cells living freely or as part of a symbiotic association. Our results indicate the presence of a circadian oscillator in Symbiodinium governing the photosynthetic apparatus through a light-induced signaling

  14. Marine cosmeceuticals.

    Science.gov (United States)

    Kim, Se-Kwon

    2014-03-01

    Recently, a great deal of interest has been expressed in the cosmetic industry regarding marine-derived cosmetic active ingredients due to their numerous beneficial effects on human skin health. Bioactive substances derived from marine resources have diverse functional roles as natural skin care agents, and these properties can be applied to the development of novel cosmetics as well as nutricosmetics (from edible seaweeds and edible marine animals). This contribution focuses on marine-derived cosmeceutical active ingredients and presents an overview of their health beneficial effects on human skin. © 2014 Wiley Periodicals, Inc.

  15. Photoprotective, excited-state quenching mechanisms in diverse photosynthetic organisms.

    Science.gov (United States)

    Magdaong, Nikki Cecil M; Blankenship, Robert E

    2018-01-03

    Light-harvesting complexes (LHCs) serve a dual role in photosynthesis, depending on the prevailing light conditions. In low light, they ensure photosynthetic efficiency by maximizing the light absorption cross-section and subsequent energy storage. Under excess light conditions, LHCs perform photoprotective quenching functions to prevent harmful chemical species such as triplet chlorophyll and singlet oxygen from forming and damaging the photosynthetic apparatus. In this minireview, various photoprotective quenching mechanisms that have been identified in different photosynthetic organisms are surveyed and summarized, and implications for improving photosynthetic productivity are briefly discussed. Published under license by The American Society for Biochemistry and Molecular Biology, Inc.

  16. Photosynthetic sulfide oxidation by Chloroflexus aurantiacus, a filamentous, photosynthetic, gliding bacterium.

    Science.gov (United States)

    Madigan, M T; Brock, T D

    1975-01-01

    Chloroflexus, a newly described genus of filamentous, photosynthetic, gliding bacteria, oxidizes sulfide anaerobically under photoautotrophic or photoheterotrophic growh conditions and deposits elemental sulfur outside the cell. The formation of sulfur granules outside the cell supports the idea that this organism is related to the green sulfur bacteria (Chlorobiaceae). Images PMID:1092670

  17. Calculation of the hydrogen produced by a PEM electrolyzer based on solar radiation in Zacatecas; Estimacion del hidrogeno producido por un electrolizador PEM a partir de la radiacion solar en Zacatecas

    Energy Technology Data Exchange (ETDEWEB)

    Duron-Torres, S. M.; Villagrana-Munoz, L.E.; Garcia-Saldivar, V.M. [Universidad Autonoma de Zacatecas, Zacatecas (Mexico)]. E-mail: duronsm@prodigy.net.mx; Arriaga-Hurtado, L.G. [Centro de Investigacion y Desarrollo Tecnologico en Electroquimica, Pedro Escobedo, Queretaro (Mexico)

    2009-09-15

    This work presents the calculation of the amount of hydrogen obtained from the use of a proton exchange membrane electrolysis cell. Measurements performed at the solarimeter station of the Campus Siglo XXI at the Zacatecas Autonomous University were used as a basis. Solar radiation was analyzed for the period November 2007 to April 2008, corresponding to when there is less solar radiation. The amount of average irradiation measured was de 6.6 kW-h/ m{sup 2}. The evaluation of the solar-hydrogen system was conducted with linear regressions of the behavior of the hydrogen flow in LN/min versus the solar irradiance in W/m{sup 2} for a PEM electrolyzer. The results obtained indicate that the maximum amount of hydrogen produced occurred in the month of April, with 9LN/min produced with a radiation intensity of roughly 900 W/m{sup 2}; a minimum of 6 LN/min was produced with a radiation of roughly 600 W/m{sup 2} during the month of December. Based on these results, we can foresee a minimum amount of hydrogen generated of 6 to 9 LN/min in the state of Zacatecas during an entire year, since the months evaluated are those with the least solar radiation. The measurements performed by the Siglo XXI station show that the solar radiation power measured is higher than the national and worldwide means, making Zacatecas a strategic state for the use of this renewable energy. The amounts calculated of hydrogen produced would indicate that it is feasible to establish solar-hydrogen systems in this region in order to obtain this energy using PEM electrolyzers. [Spanish] En este trabajo se presenta el calculo de la cantidad de hidrogeno que se obtendria, empleando un electrolizador de membrana de intercambio de protones tipo, tomando como base las medidas realizadas en la Estacion Solarimetrica del Campus Siglo XXI en la Universidad Autonoma de Zacatecas. El analisis de la radiacion solar se realizo en el periodo de noviembre de 2007 a abril de 2008 correspondiendo a la epoca de menor

  18. Marine Science

    African Journals Online (AJOL)

    Aims and scope: The Western Indian Ocean Journal of Marine Science provides an avenue for the wide dissem- ination of high quality research generated in the Western Indian Ocean (WIO) region, in particular on the sustainable use of coastal and marine resources. This is central to the goal of supporting and promoting.

  19. Marine Science

    African Journals Online (AJOL)

    Aims and scope: The Western Indian Ocean Journal of Marine Science provides an avenue for the wide dissem- ination of high .... pod diversity and distribution are important especially since studies on marine biodiversity are scarce around Mauritius. .... accurate approach to molluscan systematics. They are helpful in ...

  20. Marine Biology

    Science.gov (United States)

    Dewees, Christopher M.; Hooper, Jon K.

    1976-01-01

    A variety of informational material for a course in marine biology or oceanology at the secondary level is presented. Among the topics discussed are: food webs and pyramids, planktonic blooms, marine life, plankton nets, food chains, phytoplankton, zooplankton, larval plankton and filter feeders. (BT)

  1. Marine Science

    African Journals Online (AJOL)

    Aims and scope: The Western Indian Ocean Journal of Marine Science provides an avenue for the wide dissem- ination of high ... The journal publishes original research articles dealing with all aspects of marine science and coastal manage- ment. Topics ..... of enteric pathogens from warm-blooded animals, including ...

  2. Thermal responses of Symbiodinium photosynthetic carbon assimilation

    Science.gov (United States)

    Oakley, Clinton A.; Schmidt, Gregory W.; Hopkinson, Brian M.

    2014-06-01

    The symbiosis between hermatypic corals and their dinoflagellate endosymbionts, genus Symbiodinium, is based on carbon exchange. This symbiosis is disrupted by thermally induced coral bleaching, a stress response in which the coral host expels its algal symbionts as they become physiologically impaired. The disruption of the dissolved inorganic carbon (DIC) supply or the thermal inactivation of Rubisco have been proposed as sites of initial thermal damage that leads to the bleaching response. Symbiodinium possesses a highly unusual Form II ribulose bisphosphate carboxylase/oxygenase (Rubisco), which exhibits a lower CO2:O2 specificity and may be more thermally unstable than the Form I Rubiscos of other algae and land plants. Components of the CO2 concentrating mechanism (CCM), which supplies inorganic carbon for photosynthesis, may also be temperature sensitive. Here, we examine the ability of four cultured Symbiodinium strains to acquire and fix DIC across a temperature gradient. Surprisingly, the half-saturation constant of photosynthesis with respect to DIC concentration ( K P), an index of CCM function, declined with increasing temperature in three of the four strains, indicating a greater potential for photosynthetic carbon acquisition at elevated temperatures. In the fourth strain, there was no effect of temperature on K P. Finding no evidence for thermal inhibition of the CCM, we conclude that CCM components are not likely to be the primary sites of thermal damage. Reduced photosynthetic quantum yields, a hallmark of thermal bleaching, were observed at low DIC concentrations, leaving open the possibility that reduced inorganic carbon availability is involved in bleaching.

  3. Non-photosynthetic pigments as potential biosignatures

    Science.gov (United States)

    Schwieterman, E. W.; Cockell, C. S.; Meadows, V. S.

    2014-03-01

    Photosynthetic organisms on Earth produce potentially detectable surface reflectance biosignatures due in part to the spectral location and strength of pigment absorption. However, life on Earth uses pigments for a multitude of purposes other than photosynthesis, including coping with extreme environments. Macroscopic environments exist on Earth where the surface reflectance is significantly altered by a nonphotosynthetic pigment, such as the case of hypersaline lakes and ponds (Oren et al. 1992). Here we explore the nature and potential detectability of non-photosynthetic pigments in disk-averaged planetary observations using a combination of laboratory measurements and archival reflectance spectra, along with simulated broadband photometry and spectra. The in vivo visible reflectance spectra of a cross section of pigmented microorganisms are presented to illustrate the spectral diversity of biologically produced pigments. Synthetic broadband colors are generated to show a significant spread in color space. A 1D radiative transfer model (Meadows & Crisp 1996; Crisp 1997) is used to approximate the spectra of scenarios where pigmented organisms are widespread on planets with Earth-like atmospheres. Broadband colors are revisited to show that colors due to surface reflectivity are not robust to the addition of scattering and absorption effects from the atmosphere. We consider a èbest case' plausible scenario for the detection of nonphotosynthetic pigments by using the Virtual Planetary Laboratory's 3D spectral Earth model (Robinson et al. 2011) to explore the detectability of the surface biosignature produced by pigmented halophiles that are widespread on an Earth-analog planet.

  4. Effect of plant density on the characteristics of photosynthetic ...

    African Journals Online (AJOL)

    ajl yemi

    2011-11-14

    Nov 14, 2011 ... At such densities, garlic developed a powerful photosynthetic apparatus and the bulbs were large and uniform. Key words: Garlic, plant density, leaf number per plant, leaf area, LAI. INTRODUCTION. The photosynthetic apparatus performs photosynthesis, which involves the production of organic matter.

  5. The effect of nitrogen on the development and photosynthetic activity ...

    African Journals Online (AJOL)

    Whole plant net photosynthetic rates appeared to vary according to the units in which the activity is expressed. The optimum levels of photosynthetic activity differed with the stage of development, depending on the basis of expression. The form and concentration of nitrogen applied influenced morphological development ...

  6. Variation of photosynthetic tolerance of rice cultivars (Oryza sativa L ...

    African Journals Online (AJOL)

    STORAGESEVER

    2010-03-01

    Mar 1, 2010 ... Photosynthetic characteristics of two cultivars tolerant (c.v. Taipei309 and Wuyujing3), two cultivars sensitive (c.v.CA212 and ... Key words: Rice, chilling tolerance, photosynthetic rate, photo-system, chilling stress, photooxidation, gluthione ...... response to low temperature: an overview.-Lyons JM. Low.

  7. Effects of ultraviolet radiation on photosynthetic performance and N2 fixation in Trichodesmium erythraeum IMS 101

    Directory of Open Access Journals (Sweden)

    X. Cai

    2017-10-01

    Full Text Available Biological effects of ultraviolet radiation (UVR; 280–400 nm on marine primary producers are of general concern, as oceanic carbon fixers that contribute to the marine biological CO2 pump are being exposed to increasing UV irradiance due to global change and ozone depletion. We investigated the effects of UV-B (280–320 nm and UV-A (320–400 nm on the biogeochemically critical filamentous marine N2-fixing cyanobacterium Trichodesmium (strain IMS101 using a solar simulator as well as under natural solar radiation. Short exposure to UV-B, UV-A, or integrated total UVR significantly reduced the effective quantum yield of photosystem II (PSII and photosynthetic carbon and N2 fixation rates. Cells acclimated to low light were more sensitive to UV exposure compared to high-light-grown ones, which had more UV-absorbing compounds, most likely mycosporine-like amino acids (MAAs. After acclimation under natural sunlight, the specific growth rate was lower (by up to 44 %, MAA content was higher, and average trichome length was shorter (by up to 22 % in the full spectrum of solar radiation with UVR, than under a photosynthetically active radiation (PAR alone treatment (400–700 nm. These results suggest that prior shipboard experiments in UV-opaque containers may have substantially overestimated in situ nitrogen fixation rates by Trichodesmium, and that natural and anthropogenic elevation of UV radiation intensity could significantly inhibit this vital source of new nitrogen to the current and future oligotrophic oceans.

  8. Diversity and abundance of photosynthetic sponges in temperate Western Australia

    Directory of Open Access Journals (Sweden)

    Brümmer Franz

    2009-02-01

    Full Text Available Abstract Background Photosynthetic sponges are important components of reef ecosystems around the world, but are poorly understood. It is often assumed that temperate regions have low diversity and abundance of photosynthetic sponges, but to date no studies have investigated this question. The aim of this study was to compare the percentages of photosynthetic sponges in temperate Western Australia (WA with previously published data on tropical regions, and to determine the abundance and diversity of these associations in a range of temperate environments. Results We sampled sponges on 5 m belt transects to determine the percentage of photosynthetic sponges and identified at least one representative of each group of symbionts using 16S rDNA sequencing together with microscopy techniques. Our results demonstrate that photosynthetic sponges are abundant in temperate WA, with an average of 63% of sponge individuals hosting high levels of photosynthetic symbionts and 11% with low to medium levels. These percentages of photosynthetic sponges are comparable to those found on tropical reefs and may have important implications for ecosystem function on temperate reefs in other areas of the world. A diverse range of symbionts sometimes occurred within a small geographic area, including the three "big" cyanobacterial clades, Oscillatoria spongeliae, "Candidatus Synechococcus spongiarum" and Synechocystis species, and it appears that these clades all occur in a wide range of sponges. Additionally, spongin-permeating red algae occurred in at least 7 sponge species. This study provides the first investigation of the molecular phylogeny of rhodophyte symbionts in sponges. Conclusion Photosynthetic sponges are abundant and diverse in temperate WA, with comparable percentages of photosynthetic to non-photosynthetic sponges to tropical zones. It appears that there are three common generalist clades of cyanobacterial symbionts of sponges which occur in a wide

  9. Antenna organization in green photosynthetic bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Blankenship, R.E.

    1987-01-01

    This project is concerned with the structure and function of the unique antenna system found in the green photosynthetic bacteria. The antenna system in these organisms is contained within a vesicle known as a chlorosome, which is attached to the cytoplasmic side of the cell membrane. Additional antenna pigments and reaction centers are contained in integral membrane proteins. Energy absorbed by the bacteriochlorophyll c (BChl c) pigments in the chlorosome is transferred via a baseplate'' array of BChl a antenna pigments into the membrane and to the reaction center. A schematic model of chlorosome structure is shown. This project is aimed at increasing our understanding of the organization of the pigments in the chlorosome and how the antenna system functions.

  10. Modifiable chromatophore proteins in photosynthetic bacteria.

    Science.gov (United States)

    Hui, K M; Hurlbert, R E

    1979-01-01

    The chromatophores of Chromatium vinosum, as well as six other photosynthetic bacteria, contained two or more proteins which were insoluble when heated in the presence of sodium dodecyl sulfate (SDS) and 2-mercaptoethanol (beta-ME). When the chromatophores were dissolved at room temperature in SDS-beta-ME, these proteins were present in the SDS-polyacrylamide gel electrophoresis profiles, but when the samples were dissolved at 100 degrees C, they were absent or considerably diminished. When one-dimensional gels of chromatophores solubilized at room temperature were soaked in the SDS-beta-ME solution and heated to 100 degrees C and the gels were run in a second dimension, the proteins became immobilized in the original first-dimension gel, where they could be detected by staining. The two major proteins so affected in C. vinosum had apparent molecular weights of 28,000 and 21,000. The chromatophores of several other photosynthetic bacteria also contained predominant proteins between 30,000 and 19,000 molecular weight, which became insoluble when heated in the presence of SDS and beta-ME. In at least two of the species examined, these appeared to be reaction center proteins. The conditions causing the proteins to become insoluble were complex and involved temperature, SDS concentration, and the presence of sulfhydryl reagents. The chromatophores of four of the Chromatiaceae species and two strains of one of the Rhodospirillaceae species examined had a protein-pigment complex that was visible in SDS-polyacrylamide gel profiles of samples dissolved at room temperature but was absent in samples dissolved at 100 degrees C. Images PMID:438130

  11. Marine Science

    African Journals Online (AJOL)

    stocking densities in places with limited land, fresh water and man power. ... grove forests, which provide habitat for several marine and estuarine species. ..... of cultured Florida apple snails, Pomacea paludosa. Aquaculture 311: 139 –145.

  12. Marine insects

    National Research Council Canada - National Science Library

    Cheng, Lanna

    1976-01-01

    .... Not only are true insects, such as the Collembola and insect parasites of marine birds and mammals, considered, but also other kinds of intertidal air-breathing arthropods, notably spiders, scorpions...

  13. Transitions between marine and freshwater environments provide new clues about the origins of multicellular plants and algae

    OpenAIRE

    Dittami, Simon M; Heesch, Svenja; Olsen, Jeanine L.; Collén, Jonas

    2017-01-01

    International audience; Marine-freshwater and freshwater-marine transitions have been key events in the evolution of life, and most major groups of organisms have independently undergone such events at least once in their history. Here we first compile an inventory of bidirectional freshwater and marine transitions in multicellular photosynthetic eukaryotes. While green and red algae have mastered multiple transitions in both directions, brown algae have colonized fresh water on a maximum of ...

  14. Origin and early evolution of photosynthetic eukaryotes in freshwater environments: reinterpreting proterozoic paleobiology and biogeochemical processes in light of trait evolution.

    Science.gov (United States)

    Blank, Carrine E

    2013-12-01

    Phylogenetic analyses were performed on concatenated data sets of 31 genes and 11,789 unambiguously alignable characters from 37 cyanobacterial and 35 chloroplast genomes. The plastid lineage emerged somewhat early in the cyanobacterial tree, at a time when Cyanobacteria were likely unicellular and restricted to freshwater ecosystems. Using relaxed molecular clocks and 22 age constraints spanning cyanobacterial and eukaryote nodes, the common ancestor to the photosynthetic eukaryotes was predicted to have also inhabited freshwater environments around the time that oxygen appeared in the atmosphere (2.0-2.3 Ga). Early diversifications within each of the three major plastid clades were also inferred to have occurred in freshwater environments, through the late Paleoproterozoic and into the middle Mesoproterozoic. The colonization of marine environments by photosynthetic eukaryotes may not have occurred until after the middle Mesoproterozoic (1.2-1.5 Ga). The evolutionary hypotheses proposed here predict that early photosynthetic eukaryotes may have never experienced the widespread anoxia or euxinia suggested to have characterized marine environments in the Paleoproterozoic to early Mesoproterozoic. It also proposes that earliest acritarchs (1.5-1.7 Ga) may have been produced by freshwater taxa. This study highlights how the early evolution of habitat preference in photosynthetic eukaryotes, along with Cyanobacteria, could have contributed to changing biogeochemical conditions on the early Earth. © 2013 Phycological Society of America.

  15. Marine Viruses that infect Eukaryotic Microalgae.

    Science.gov (United States)

    Kimura, Kei; Tomaru, Yuji

    2015-01-01

    Marine microalgae, in general, explain large amount of the primary productions on the planet. Their huge biomass through photosynthetic activities is significant to understand the global geochemical cycles. Many researchers are, therefore, focused on studies of marine microalgae, i.e. phytoplankton. Since the first report of high abundance of viruses in the sea at late 1980's, the marine viruses have recognized as an important decreasing factor of its host populations. They seem to be composed of diverse viruses infectious to different organism groups; most of them are considered to be phages infectious to prokaryotes, and viruses infecting microalgae might be ranked in second level. Over the last quarter of a century, the knowledge on marine microalgal viruses has been accumulated in many aspects. Until today, ca. 40 species of marine microalgal viruses have been discovered, including dsDNA, ssDNA, dsRNA and ssRNA viruses. Their features are unique and comprise new ideas and discoveries, indicating that the marine microalgal virus research is still an intriguing unexplored field. In this review, we summarize their basic biology and ecology, and discuss how and what we should research in this area for further progress.

  16. Primary endosymbiosis and the evolution of light and oxygen sensing in photosynthetic eukaryotes

    Directory of Open Access Journals (Sweden)

    Nathan C Rockwell

    2014-10-01

    Full Text Available The origin of the photosynthetic organelle in eukaryotes, the plastid, changed forever the evolutionary trajectory of life on our planet. Plastids are highly specialized compartments derived from a putative single cyanobacterial primary endosymbiosis that occurred in the common ancestor of the supergroup Archaeplastida that comprises the Viridiplantae (green algae and plants, red algae, and glaucophyte algae. These lineages include critical primary producers of freshwater and terrestrial ecosystems, progenitors of which provided plastids through secondary endosymbiosis to other algae such as diatoms and dinoflagellates that are critical to marine ecosystems. Despite its broad importance and the success of algal and plant lineages, the phagotrophic origin of the plastid imposed an interesting challenge on the predatory eukaryotic ancestor of the Archaeplastida. By engulfing an oxygenic photosynthetic cell, the host lineage imposed an oxidative stress upon itself in the presence of light. Adaptations to meet this challenge were thus likely to have occurred early on during the transition from a predatory phagotroph to an obligate phototroph (or mixotroph. Modern algae have recently been shown to employ linear tetrapyrroles (bilins to respond to oxidative stress under high light. Here we explore the early events in plastid evolution and the possible ancient roles of bilins in responding to light and oxygen.

  17. Induced modifications on algae photosynthetic activity monitored by pump-and-probe technique

    Energy Technology Data Exchange (ETDEWEB)

    Barbini, R.; Colao, F.; Fantoni, R.; Palucci, A.; Ribezzo, S. [ENEA, Centro Ricerche Frascati, Rome (Italy). Dip. Innovazione; Tarzillo, G.; Carlozzi, P.; Pelosi, E. [CNR, Florence (Italy). Centro Studi Microorganismi Autotrofi

    1995-12-01

    The lidar fluorosensor system available at ENEA Frascati has been used for a series of laboratory measurements on brackish-water and marine phytoplankton grown in laboratory with the proper saline solution. The system, already used to measure the laser induced fluorescence spectra of different algae species and their detection limits, has been upgraded with a short pulse Nd:YAG laser and rearranged to test a new technique based on laser pump and probe excitation. Results of this new technique for remote monitoring of the in-vivo photosynthetic activity will be presented, as measured during a field campaign carried out in Florence during the Autumn 1993, where the effects of an actinic saturating light and different chemicals have also been checked.

  18. Engineering of photosynthetic mannitol biosynthesis from CO2 in a cyanobacterium

    DEFF Research Database (Denmark)

    Jacobsen, Jacob Hedemand; Frigaard, Niels-Ulrik

    2014-01-01

    d-Mannitol (hereafter denoted mannitol) is used in the medical and food industry and is currently produced commercially by chemical hydrogenation of fructose or by extraction from seaweed. Here, the marine cyanobacterium Synechococcus sp. PCC 7002 was genetically modified to photosynthetically...... produce mannitol from CO2 as the sole carbon source. Two codon-optimized genes, mannitol-1-phosphate dehydrogenase (mtlD) from Escherichia coli and mannitol-1-phosphatase (mlp) from the protozoan chicken parasite Eimeria tenella, in combination encoding a biosynthetic pathway from fructose-6-phosphate...... to mannitol, were expressed in the cyanobacterium resulting in accumulation of mannitol in the cells and in the culture medium. The mannitol biosynthetic genes were expressed from a single synthetic operon inserted into the cyanobacterial chromosome by homologous recombination. The mannitol biosynthesis...

  19. A novel potassium channel in photosynthetic cyanobacteria.

    Directory of Open Access Journals (Sweden)

    Manuela Zanetti

    Full Text Available Elucidation of the structure-function relationship of a small number of prokaryotic ion channels characterized so far greatly contributed to our knowledge on basic mechanisms of ion conduction. We identified a new potassium channel (SynK in the genome of the cyanobacterium Synechocystis sp. PCC6803, a photosynthetic model organism. SynK, when expressed in a K(+-uptake-system deficient E. coli strain, was able to recover growth of these organisms. The protein functions as a potassium selective ion channel when expressed in Chinese hamster ovary cells. The location of SynK in cyanobacteria in both thylakoid and plasmamembranes was revealed by immunogold electron microscopy and Western blotting of isolated membrane fractions. SynK seems to be conserved during evolution, giving rise to a TPK (two-pore K(+ channel family member which is shown here to be located in the thylakoid membrane of Arabidopsis. Our work characterizes a novel cyanobacterial potassium channel and indicates the molecular nature of the first higher plant thylakoid cation channel, opening the way to functional studies.

  20. ENHANCED PRACTICAL PHOTOSYNTHETIC CO2 MITIGATION

    Energy Technology Data Exchange (ETDEWEB)

    Dr. David J. Bayless; Dr. Morgan Vis; Dr. Gregory Kremer; Dr. Michael Prudich; Dr. Keith Cooksey; Dr. Jeff Muhs

    2001-01-16

    This is the first quarterly report of the project Enhanced Practical Photosynthetic CO{sub 2} Mitigation. The official project start date, 10/02/2000, was delayed until 10/31/2000 due to an intellectual property dispute that was resolved. However, the delay forced a subsequent delay in subcontracting with Montana State University, which then delayed obtaining a sampling permit from Yellowstone National Park. However, even with these delays, the project moved forward with some success. Accomplishments for this quarter include: Culturing of thermophilic organisms from Yellowstone; Testing of mesophilic organisms in extreme CO{sub 2} conditions; Construction of a second test bed for additional testing; Purchase of a total carbon analyzer dedicated to the project; Construction of a lighting container for Oak Ridge National Laboratory optical fiber testing; Modified lighting of existing test box to provide more uniform distribution; Testing of growth surface adhesion and properties; Experimentation on water-jet harvesting techniques; and Literature review underway regarding uses of biomass after harvesting. Plans for next quarter's work and an update on the project's web page are included in the conclusions.

  1. Photocurrent of a single photosynthetic protein

    Science.gov (United States)

    Gerster, Daniel; Reichert, Joachim; Bi, Hai; Barth, Johannes V.; Kaniber, Simone M.; Holleitner, Alexander W.; Visoly-Fisher, Iris; Sergani, Shlomi; Carmeli, Itai

    2012-10-01

    Photosynthesis is used by plants, algae and bacteria to convert solar energy into stable chemical energy. The initial stages of this process--where light is absorbed and energy and electrons are transferred--are mediated by reaction centres composed of chlorophyll and carotenoid complexes. It has been previously shown that single small molecules can be used as functional components in electric and optoelectronic circuits, but it has proved difficult to control and probe individual molecules for photovoltaic and photoelectrochemical applications. Here, we show that the photocurrent generated by a single photosynthetic protein--photosystem I--can be measured using a scanning near-field optical microscope set-up. One side of the protein is anchored to a gold surface that acts as an electrode, and the other is contacted by a gold-covered glass tip. The tip functions as both counter electrode and light source. A photocurrent of ~10 pA is recorded from the covalently bound single-protein junctions, which is in agreement with the internal electron transfer times of photosystem I.

  2. ENHANCED PRACTICAL PHOTOSYNTHETIC CO2 MITIGATION

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Gregory Kremer; Dr. David J. Bayless; Dr. Morgan Vis; Dr. Michael Prudich; Dr. Keith Cooksey; Dr. Jeff Muhs

    2001-07-25

    This quarterly report documents significant achievements in the Enhanced Practical Photosynthetic CO{sub 2} Mitigation project during the period from 4/03/2001 through 7/02/2001. Most of the achievements are milestones in our efforts to complete the tasks and subtasks that constitute the project objectives. Note that this version of the quarterly technical report is a revision to add the reports from subcontractors Montana State and Oak Ridge National Laboratories The significant accomplishments for this quarter include: Development of an experimental plan and initiation of experiments to create a calibration curve that correlates algal chlorophyll levels with carbon levels (to simplify future experimental procedures); Completion of debugging of the slug flow reactor system, and development of a plan for testing the pressure drop of the slug flow reactor; Design and development of a new bioreactor screen design which integrates the nutrient delivery drip system and the harvesting system; Development of an experimental setup for testing the new integrated drip system/harvesting system; Completion of model-scale bioreactor tests examining the effects of CO{sub 2} concentration levels and lighting levels on Nostoc 86-3 growth rates; Completion of the construction of a larger model-scale bioreactor to improve and expand testing capabilities and initiation of tests; Substantial progress on construction of a pilot-scale bioreactor; and Preliminary economic analysis of photobioreactor deployment. Plans for next quarter's work are included in the conclusions. A preliminary economic analysis is included as an appendix.

  3. Antenna organization in green photosynthetic bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Blankenship, R.E.

    1987-01-01

    This project is concerned with the structure and function of the unique antenna system found in the green photosynthetic bacteria. The antenna system in these organisms is contained within a vesicle known as a chlorosome, which is attached to the cytoplasmic side of the cell membrane. Additional antenna pigments and reaction centers are contained in integral membrane proteins. Energy absorbed by the bacteriochlorophyll c (BChl c) pigments in the chlorosome is transferred via a baseplate'' array of BChl a antenna pigments into the membrane and to the reaction center. This system is similar in some respects to the phycobilisome antenna system found in cyanobacteria and some types of algae, in that a membrane-associated structure absorbs light and transfers it to the membrane where conversion to chemical energy takes place. However, the overall structure, the type of pigments utilized and the nature of the proteins in these two types of membrane-associated antenna bodies are entirely different, and they clearly represent two independent evolutionary solutions to the problem of light collection and excitation transfer.

  4. Otters, Marine

    Science.gov (United States)

    Estes, James A.; Bodkin, James L.; Ben-David, M.; Perrin, William F.; Würsing, Bernd; Thewissen, J.G.M.

    2009-01-01

    The otters (Mustelidae; Lutrinae) provide an exceptional perspective into the evolution of marine living by mammals. Most extant marine mammals (e.g. the cetaceans, pinnipeds, and sirenians) have been so highly modified by long periods of selection for life in the sea that they bear little resemblance to their terrestrial ancestors. Marine otters, in contrast, are more recent expatriates from freshwater habitats and some species still live in both environments. Contrasts among species within the otters, and among the otters, terrestrial mammals, and the more highly adapted pinnipeds and cetaceans provide powerful insights into mammalian adaptations to life in the sea (Estes, 1989). Among the marine mammals, sea otters (Enhydra lutris, Fig. 1) provide the clearest understanding of consumer-induced effects on ecosystem function. This is due in part to opportunities provided by history and in part to the relative ease with which shallow coastal systems where sea otters live can be observed and studied. Although more difficult to study than sea otters, other otter species reveal the connectivity among the marine, freshwater, and terrestrial systems. These three qualities of the otters – their comparative biology, their role as predators, and their role as agents of ecosystem connectivity – are what make them interesting to marine mammalogy.The following account provides a broad overview of the comparative biology and ecology of the otters, with particular emphasis on those species or populations that live in the sea. Sea otters are features prominently, in part because they live exclusively in the sea whereas other otters have obligate associations with freshwater and terrestrial environments (Kenyon, 1969; Riedman and Estes, 1990).

  5. Photosynthetic efficiency of Chlamydomonas reinhardtii in flashing light

    NARCIS (Netherlands)

    Vejrazka, C.; Janssen, M.G.J.; Streefland, M.; Wijffels, R.H.

    2011-01-01

    Efficient light to biomass conversion in photobioreactors is crucial for economically feasible microalgae production processes. It has been suggested that photosynthesis is enhanced in short light path photobioreactors by mixing-induced flashing light regimes. In this study, photosynthetic

  6. Cultivar variation in cotton photosynthetic performance under different temperature regimes

    Science.gov (United States)

    Cotton (Gossypium hirsutum L.) yields are impacted by overall photosynthetic production. Factors that influence crop photosynthesis are the plants genetic makeup and the environmental conditions. This study investigated cultivar variation in photosynthesis when plants were grown in the field under...

  7. Carotenoids are essential for the assembly of cyanobacterial photosynthetic complexes

    NARCIS (Netherlands)

    Tóth, T.N.; Chukhutsina, Volha; Domonkos, Ildikó; Knoppová, Jana; Komenda, Josef; Kis, Mihály; Lénárt, Zsófia; Garab, Gyozo; Kovács, László; Gombos, Zoltán; Amerongen, Van Herbert

    2015-01-01

    In photosynthetic organisms, carotenoids (carotenes and xanthophylls) are important for light harvesting, photoprotection and structural stability of a variety of pigment-protein complexes. Here, we investigated the consequences of altered carotenoid composition for the functional organization of

  8. Pharmaceutical, cosmeceutical, and traditional applications of marine carbohydrates.

    Science.gov (United States)

    Ahmed, Abdul Bakrudeen Ali; Adel, Mohaddeseh; Karimi, Pegah; Peidayesh, Mahvash

    2014-01-01

    Marine carbohydrates are most important organic molecules made by photosynthetic organisms. It is very essential for humankind: the role in being an energy source for the organism and they are considered as an important dissolve organic compound (DOC) in marine environment's sediments. Carbohydrates found in different marine environments in different concentrations. Polysaccharides of carbohydrates play an important role in various fields such as pharmaceutical, food production, cosmeceutical, and so on. Marine organisms are good resources of nutrients, and they are rich carbohydrate in sulfated polysaccharide. Seaweeds (marine microalgae) are used in different pharmaceutical industries, especially in pharmaceutical compound production. Seaweeds have a significant amount of sulfated polysaccharides, which are used in cosmeceutical industry, besides based on the biological applications. Since then, traditional people, cosmetics products, and pharmaceutical applications consider many types of seaweed as an important organism used in food process. Sulfated polysaccharides containing seaweed have potential uses in the blood coagulation system, antiviral activity, antioxidant activity, anticancer activity, immunomodulating activity, antilipidepic activity, etc. Some species of marine organisms are rich in polysaccharides such as sulfated galactans. Various polysaccharides such as agar and alginates, which are extracted from marine organisms, have several applications in food production and cosmeceutical industries. Due to their high health benefits, compound-derived extracts of marine polysaccharides have various applications and traditional people were using them since long time ago. In the future, much attention is supposed to be paid to unraveling the structural, compositional, and sequential properties of marine carbohydrate as well. © 2014 Elsevier Inc. All rights reserved.

  9. Engineering photosynthetic organisms for the production of biohydrogen

    OpenAIRE

    Dubini, Alexandra; Ghirardi, Maria L.

    2014-01-01

    Oxygenic photosynthetic organisms such as green algae are capable of absorbing sunlight and converting the chemical energy into hydrogen gas. This process takes advantage of the photosynthetic apparatus of these organisms which links water oxidation to H2 production. Biological H2 has therefore the potential to be an alternative fuel of the future and shows great promise for generating large scale sustainable energy. Microalgae are able to produce H2 under light anoxic or dark anoxic conditio...

  10. Variations in Photosynthetic Rates of Fourteen Coleus Cultivars

    Science.gov (United States)

    Rouhani, Iraj; Khosh-Khui, Morteza

    1977-01-01

    Fourteen cultivars of coleus (Coleus blumei Benth) were found to vary in chlorophyll content, photosynthetic rate, anthocyanin content and number of stomates. Cultivars `Gaslight' and `Velvet Rainbow' had 0.17 and 0.92 mg chlorophyll per g of leaves, fresh weight, respectively. Maximum photosynthetic rate (18.7 mg CO2/mg Chl·hr) was found in the leaves of `Pastle Rainbow' and minimum (2.7) in the `Velvet Rainbow.' PMID:16659778

  11. On the photosynthetic potential in the very Early Archean oceans.

    Science.gov (United States)

    Avila, Daile; Cardenas, Rolando; Martin, Osmel

    2013-02-01

    In this work we apply a mathematical model of photosynthesis to quantify the potential for photosynthetic life in the very Early Archean oceans. We assume the presence of oceanic blockers of ultraviolet radiation, specifically ferrous ions. For this scenario, our results suggest a potential for photosynthetic life greater than or similar to that in later eras/eons, such as the Late Archean and the current Phanerozoic eon.

  12. Marine Microbial Production of Dimethylsulfide From Dissolved Dimethylsulfoniopropionate

    Science.gov (United States)

    1993-02-01

    production, and yielded DDMs values on the order of half a day to a week. In four of seven experiments, net production rather than comsumption of DMS...zone, in contrast, would he fueled by upwelled nitrate and dominated by larger algae, thus sustaining a significant flux of sinking carbon even 149...photosynthetic bacteria. Japan Scientific Societies Press, Tokyo, and Springer-Verlag, Berlin. 33. Shiba, T. 1989. Taxonomy and ecology of marine bacteria

  13. Rice Photosynthetic Productivity and PSII Photochemistry under Nonflooded Irrigation

    Directory of Open Access Journals (Sweden)

    Haibing He

    2014-01-01

    Full Text Available Nonflooded irrigation is an important water-saving rice cultivation technology, but little is known on its photosynthetic mechanism. The aims of this work were to investigate photosynthetic characteristics of rice during grain filling stage under three nonflooded irrigation treatments: furrow irrigation with plastic mulching (FIM, furrow irrigation with nonmulching (FIN, and drip irrigation with plastic mulching (DI. Compared with the conventional flooding (CF treatment, those grown in the nonflooded irrigation treatments showed lower net photosynthetic rate (PN, lower maximum quantum yield (Fv/Fm, and lower effective quantum yield of PSII photochemistry (ΦPSII. And the poor photosynthetic characteristics in the nonflooded irrigation treatments were mainly attributed to the low total nitrogen content (TNC. Under non-flooded irrigation, the PN, Fv/Fm, and ΦPSII significantly decreased with a reduction in the soil water potential, but these parameters were rapidly recovered in the DI and FIM treatments when supplementary irrigation was applied. Moreover, The DI treatment always had higher photosynthetic productivity than the FIM and FIN treatments. Grain yield, matter translocation, and dry matter post-anthesis (DMPA were the highest in the CF treatment, followed by the DI, FIM, and FIN treatments in turn. In conclusion, increasing nitrogen content in leaf of rice plants could be a key factor to improve photosynthetic capacity in nonflooded irrigation.

  14. Production and Consumption of Hydrogen in Hot Spring Microbial Mats Dominated by a Filamentous Anoxygenic Photosynthetic Bacterium

    Science.gov (United States)

    Otaki, Hiroyo; Everroad, R. Craig; Matsuura, Katsumi; Haruta, Shin

    2012-01-01

    Microbial mats containing the filamentous anoxygenic photosynthetic bacterium Chloroflexus aggregans develop at Nakabusa hot spring in Japan. Under anaerobic conditions in these mats, interspecies interaction between sulfate-reducing bacteria as sulfide producers and C. aggregans as a sulfide consumer has been proposed to constitute a sulfur cycle; however, the electron donor utilized for microbial sulfide production at Nakabusa remains to be identified. In order to determine this electron donor and its source, ex situ experimental incubation of mats was explored. In the presence of molybdate, which inhibits biological sulfate reduction, hydrogen gas was released from mat samples, indicating that this hydrogen is normally consumed as an electron donor by sulfate-reducing bacteria. Hydrogen production decreased under illumination, indicating that C. aggregans also functions as a hydrogen consumer. Small amounts of hydrogen may have also been consumed for sulfur reduction. Clone library analysis of 16S rRNA genes amplified from the mats indicated the existence of several species of hydrogen-producing fermentative bacteria. Among them, the most dominant fermenter, Fervidobacterium sp., was successfully isolated. This isolate produced hydrogen through the fermentation of organic carbon. Dispersion of microbial cells in the mats resulted in hydrogen production without the addition of molybdate, suggesting that simultaneous production and consumption of hydrogen in the mats requires dense packing of cells. We propose a cyclic electron flow within the microbial mats, i.e., electron flow occurs through three elements: S (elemental sulfur, sulfide, sulfate), C (carbon dioxide, organic carbon) and H (di-hydrogen, protons). PMID:22446313

  15. Marine Science

    African Journals Online (AJOL)

    ination of high quality research generated in the Western Indian Ocean (WIO) region, in particular on the sustainable use of coastal ... The journal publishes original research articles dealing with all aspects of marine science and coastal manage- ment. Topics ..... diatom C-biomass is a result of changes in silicate. Figure 4.

  16. Marine Science

    African Journals Online (AJOL)

    Special Issue 1/ 2017 | Jul 2017 | ISSN: 0856-860X. Western Indian Ocean. J O U R N A L O F. Marine Science. Coral reefs of Mauritius in a changing global climate .... of coral diseases, and Stylophora pistillata-like morphotypes occurring around Mauritius Island, respec- tively. .... (2013) assumed that the life cycle of.

  17. Marine Science

    African Journals Online (AJOL)

    sustainable coastal development in the region, as well as contributing to the global base of marine science. .... to accommodate multiple user-groups while con- .... Criteria used to select trawling sites within the survey areas were traw- lability and depth range (100-699 m), and sites were stratified by depth and latitude.

  18. Marine Science

    African Journals Online (AJOL)

    The journal publishes original research articles dealing with all aspects of marine science and coastal manage- ment. ... Science (WIOJMS), as a special issue entitled “Coral reefs of Mauritius in a changing global climate”. ...... 2014) with the highest disaster risk exposed to natural hazards, including storms and floods.

  19. Marine Science

    African Journals Online (AJOL)

    between humans and the coastal and marine environment. In addition, Western Indian Ocean Journal of .... Spatial regulation of fishing effort will be most appropriate in minimizing the cumulative effects of fishing on vulnerable species ...... to maximize on returns (Johannes et al., 2001; Pet-. Soede et al., 2001; Wiyono et al., ...

  20. Marine Science

    African Journals Online (AJOL)

    Special Issue 1/ 2017 | Jul 2017 | ISSN: 0856-860X. Western ... Sweden. Johan GROENEVELD. South Africa. Issufo HALO. South Africa/Mozambique. Christina HICKS. Australia/UK. Johnson KITHEKA. Kenya. Kassim KULINDWA .... WIO Journal of Marine Science Special Issue 1 / 2017 31-41 | D. Kaullysing et al. sediment ...

  1. Marine Science

    African Journals Online (AJOL)

    The special issues aim to contribute for advancing marine science in the WIO by focusing on specific themes, geographical areas or assembling contributions from scientific meetings. The editorial processes are exactly the same as for regular issues, with double peer-review, and guest editors are considered. José Paula.

  2. Marine Science

    African Journals Online (AJOL)

    Aims and scope: The Western Indian Ocean Journal of Marine Science provides an avenue for the wide dissem- ination of high quality research generated in the Western Indian Ocean (WIO) region, in particular on the sustainable use of coastal and .... taken up to a depth of 5cm using a plastic hand core of. 2.6cm diameter.

  3. Marine Science

    African Journals Online (AJOL)

    Chief Editor José Paula | Faculty of Sciences of University of Lisbon, Portugal. Copy Editor ... sustainable coastal development in the region, as well as contributing to the global base of marine science. ... salt works along the coast of Ungwana Bay provide alternative fishing grounds for local fishers unable to venture.

  4. Differential allocation to photosynthetic and non-photosynthetic nitrogen fractions among native and invasive species.

    Science.gov (United States)

    Funk, Jennifer L; Glenwinkel, Lori A; Sack, Lawren

    2013-01-01

    Invasive species are expected to cluster on the "high-return" end of the leaf economic spectrum, displaying leaf traits consistent with higher carbon assimilation relative to native species. Intra-leaf nitrogen (N) allocation should support these physiological differences; however, N biochemistry has not been examined in more than a few invasive species. We measured 34 leaf traits including seven leaf N pools for five native and five invasive species from Hawaii under low irradiance to mimic the forest understory environment. We found several trait differences between native and invasive species. In particular, invasive species showed preferential N allocation to metabolism (amino acids) rather than photosynthetic light reactions (membrane-bound protein) by comparison with native species. The soluble protein concentration did not vary between groups. Under these low irradiance conditions, native species had higher light-saturated photosynthetic rates, possibly as a consequence of a greater investment in membrane-bound protein. Invasive species may succeed by employing a wide range of N allocation mechanisms, including higher amino acid production for fast growth under high irradiance or storage of N in leaves as soluble protein or amino acids.

  5. ENHANCED PRACTICAL PHOTOSYNTHETIC CO2 MITIGATION

    Energy Technology Data Exchange (ETDEWEB)

    Dr. David J. Bayless; Dr. Morgan Vis; Dr. Gregory Kremer; Dr. Michael Prudich; Dr. Keith Cooksey; Dr. Jeff Muhs

    2001-04-16

    This quarterly report documents significant achievements in the Enhanced Practical Photosynthetic CO{sub 2} Mitigation project during the period from 1/03/2001 through 4/02/2001. Many of the activities and accomplishments are continuations of work initiated and reported in last quarter's status report. Major activities and accomplishments for this quarter include: Three sites in Yellowstone National Park have been identified that may contain suitable organisms for use in a bioreactor; Full-scale culturing of one thermophilic organism from Yellowstone has progressed to the point that there is a sufficient quantity to test this organism in the model-scale bioreactor; The effects of the additive monoethanolamine on the growth of one thermophilic organism from Yellowstone has been tested; Testing of growth surface adhesion and properties is continuing; Construction of a larger model-scale bioreactor to improve and expand testing capabilities is completed and the facility is undergoing proof tests; Model-scale bioreactor tests examining the effects of CO{sub 2} concentration levels and lighting levels on organism growth rates are continuing; Alternative fiber optic based deep-penetration light delivery systems for use in the pilot-scale bioreactor have been designed, constructed and tested; An existing slug flow reactor system has been modified for use in this project, and a proof-of-concept test plan has been developed for the slug flow reactor; Research and testing of water-jet harvesting techniques is continuing, and a harvesting system has been designed for use in the model-scale bioreactor; and The investigation of comparative digital image analysis as a means for determining the ''density'' of algae on a growth surface is continuing Plans for next quarter's work and an update on the project's web page are included in the conclusions.

  6. Marine envenomations.

    Science.gov (United States)

    Balhara, Kamna S; Stolbach, Andrew

    2014-02-01

    This article describes the epidemiology and presentation of human envenomation from marine organisms. Venom pathophysiology, envenomation presentation, and treatment options are discussed for sea snake, stingray, spiny fish, jellyfish, octopus, cone snail, sea urchin, and sponge envenomation. The authors describe the management of common exposures that cause morbidity as well as the keys to recognition and treatment of life-threatening exposures. Copyright © 2014 Elsevier Inc. All rights reserved.

  7. Carotenoid Photoprotection in Artificial Photosynthetic Antennas

    Energy Technology Data Exchange (ETDEWEB)

    Kloz, Miroslav [VU Univ., Amsterdam (Netherlands); Pillai, Smitha [Arizona State Univ., Tempe, AZ (United States); Kodis, Gerdenis [Arizona State Univ., Tempe, AZ (United States); Gust, Devens [Arizona State Univ., Tempe, AZ (United States); Moore, Thomas A. [Arizona State Univ., Tempe, AZ (United States); Moore, Ana L. [Arizona State Univ., Tempe, AZ (United States); van Grondelle, Rienk [VU Univ., Amsterdam (Netherlands); Kennis, John T. M. [VU Univ., Amsterdam (Netherlands)

    2011-04-14

    . These synthetic systems are providing a deeper understanding of structural and environmental effects on the interactions between carotenoids and tetrapyrroles and thereby better defining their role in controlling natural photosynthetic systems.

  8. Growth and photosynthetic responses of wheat plants grown in space

    Science.gov (United States)

    Tripathy, B. C.; Brown, C. S.; Levine, H. G.; Krikorian, A. D.

    1996-01-01

    Growth and photosynthesis of wheat (Triticum aestivum L. cv Super Dwarf) plants grown onboard the space shuttle Discovery for 10 d were examined. Compared to ground control plants, the shoot fresh weight of space-grown seedlings decreased by 25%. Postflight measurements of the O2 evolution/photosynthetic photon flux density response curves of leaf samples revealed that the CO2-saturated photosynthetic rate at saturating light intensities in space-grown plants declined 25% relative to the rate in ground control plants. The relative quantum yield of CO2-saturated photosynthetic O2 evolution measured at limiting light intensities was not significantly affected. In space-grown plants, the light compensation point of the leaves increased by 33%, which likely was due to an increase (27%) in leaf dark-respiration rates. Related experiments with thylakoids isolated from space-grown plants showed that the light-saturated photosynthetic electron transport rate from H2O through photosystems II and I was reduced by 28%. These results demonstrate that photosynthetic functions are affected by the microgravity environment.

  9. Photosynthetic terpene hydrocarbon production for fuels and chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Wang, X; Ort, DR; Yuan, JS

    2015-01-28

    Photosynthetic hydrocarbon production bypasses the traditional biomass hydrolysis process and represents the most direct conversion of sunlight energy into the next-generation biofuels. As a major class of biologically derived hydrocarbons with diverse structures, terpenes are also valuable in producing a variety of fungible bioproducts in addition to the advanced drop-in' biofuels. However, it is highly challenging to achieve the efficient redirection of photosynthetic carbon and reductant into terpene biosynthesis. In this review, we discuss four major scientific and technical barriers for photosynthetic terpene production and recent advances to address these constraints. Collectively, photosynthetic terpene production needs to be optimized in a systematic fashion, in which the photosynthesis improvement, the optimization of terpene biosynthesis pathway, the improvement of key enzymes and the enhancement of sink effect through terpene storage or secretion are all important. New advances in synthetic biology also offer a suite of potential tools to design and engineer photosynthetic terpene platforms. The systemic integration of these solutions may lead to disruptive' technologies to enable biofuels and bioproducts with high efficiency, yield and infrastructure compatibility.

  10. Photosynthetic terpene hydrocarbon production for fuels and chemicals.

    Science.gov (United States)

    Wang, Xin; Ort, Donald R; Yuan, Joshua S

    2015-02-01

    Photosynthetic hydrocarbon production bypasses the traditional biomass hydrolysis process and represents the most direct conversion of sunlight energy into the next-generation biofuels. As a major class of biologically derived hydrocarbons with diverse structures, terpenes are also valuable in producing a variety of fungible bioproducts in addition to the advanced 'drop-in' biofuels. However, it is highly challenging to achieve the efficient redirection of photosynthetic carbon and reductant into terpene biosynthesis. In this review, we discuss four major scientific and technical barriers for photosynthetic terpene production and recent advances to address these constraints. Collectively, photosynthetic terpene production needs to be optimized in a systematic fashion, in which the photosynthesis improvement, the optimization of terpene biosynthesis pathway, the improvement of key enzymes and the enhancement of sink effect through terpene storage or secretion are all important. New advances in synthetic biology also offer a suite of potential tools to design and engineer photosynthetic terpene platforms. The systemic integration of these solutions may lead to 'disruptive' technologies to enable biofuels and bioproducts with high efficiency, yield and infrastructure compatibility. © 2015 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.

  11. Photosynthetic biomaterials: a pathway towards autotrophic tissue engineering.

    Science.gov (United States)

    Schenck, Thilo Ludwig; Hopfner, Ursula; Chávez, Myra Noemi; Machens, Hans-Günther; Somlai-Schweiger, Ian; Giunta, Riccardo Enzo; Bohne, Alexandra Viola; Nickelsen, Jörg; Allende, Miguel L; Egaña, José Tomás

    2015-03-01

    Engineered tissues are highly limited by poor vascularization in vivo, leading to hypoxia. In order to overcome this challenge, we propose the use of photosynthetic biomaterials to provide oxygen. Since photosynthesis is the original source of oxygen for living organisms, we suggest that this could be a novel approach to provide a constant source of oxygen supply independently of blood perfusion. In this study we demonstrate that bioartificial scaffolds can be loaded with a solution containing the photosynthetic microalgae Chlamydomonas reinhardtii, showing high biocompatibility and photosynthetic activity in vitro. Furthermore, when photosynthetic biomaterials were engrafted in a mouse full skin defect, we observed that the presence of the microalgae did not trigger a native immune response in the host. Moreover, the analyses showed that the algae survived for at least 5 days in vivo, generating chimeric tissues comprised of algae and murine cells. The results of this study represent a crucial step towards the establishment of autotrophic tissue engineering approaches and suggest the use of photosynthetic cells to treat a broad spectrum of hypoxic conditions. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  12. Timecourse analysis of photosynthetic microbial communities that degrade cellulose and fix nitrogen

    Science.gov (United States)

    Knapp, A.; van der Heyde, R.; Sheets, M.; Zhang, L.; Wang, Y.; Liu, X.; Slikas, B.; Amaral-Zettler, L. A.; Huang, J.

    2014-12-01

    Cellulose is an abundant polymer derived from plant matter and it is also a nitrogen poor resource. Nutrient cycling is carried out by microbial communities in nature, and bacteria that degrade cellulose must be able to obtain a source of fixed nitrogen for growth. We used light wavelength selection to enrich for a series of anoxygenic photosynthetic microbial communities from marine and freshwater environments that degrade cellulose and fix nitrogen. This research examines how the communities carry out these processes. We compare community composition and metabolite production measured using high performance liquid chromatography and gas chromatography over time of growth of the communities. A freshwater community grown at 590nm showed the highest metabolic rates. Acetate and propionate reached maximum concentration at around day 4 and hydrogen concentrations peaked at 5uM on day 6 at stationary phase. There was no methane production by this culture suggesting methanogens were not present or inactive. In contrast, methanogenesis was very active in another freshwater community grown at 760/940nm. This culture showed acetate and propionate accumulation and hydrogen gas concentrations that decreased over time as well suggesting that hydrogenotrophic methanogenesis was occurring. A similar trend was observed in a marine community grown at 470nm. This work can enable determination of factors important for efficient community nutrient cycling and understanding of community dynamics. Future work will be done to determine the roles of the individual species of bacteria within the communities and to investigate the potential of these communities in biofuel production.

  13. Superradiance Transition and Nonphotochemical Quenching in Photosynthetic Complexes

    Energy Technology Data Exchange (ETDEWEB)

    Berman, Gennady Petrovich [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Nesterov, Alexander [Universidad de Guadalajara, Departamento de Fısica, Jalisco (Mexico); Lopez, Gustavo [Universidad de Guadalajara, Departamento de Fısica, Jalisco (Mexico); Sayre, Richard Thomas [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-04-23

    Photosynthetic organisms have evolved protective strategies to allow them to survive in cases of intense sunlight fluctuation with the development of nonphotochemical quenching (NPQ). This process allows light harvesting complexes to transfer the excess sunlight energy to non-damaging quenching channels. This report compares the NPQ process with the superradiance transition (ST). We demonstrated that the maximum of the NPQ efficiency is caused by the ST to the sink associated with the CTS. However, experimental verifications are required in order to determine whether or not the NPQ regime is associated with the ST transition for real photosynthetic complexes. Indeed, it can happen that, in the photosynthetic apparatus, the NPQ regime occurs in the “non-optimal” region of parameters, and it could be independent of the ST.

  14. Photovoltaic concepts inspired by coherence effects in photosynthetic systems

    Science.gov (United States)

    Brédas, Jean-Luc; Sargent, Edward H.; Scholes, Gregory D.

    2017-01-01

    The past decade has seen rapid advances in our understanding of how coherent and vibronic phenomena in biological photosynthetic systems aid in the efficient transport of energy from light-harvesting antennas to photosynthetic reaction centres. Such coherence effects suggest strategies to increase transport lengths even in the presence of structural disorder. Here we explore how these principles could be exploited in making improved solar cells. We investigate in depth the case of organic materials, systems in which energy and charge transport stand to be improved by overcoming challenges that arise from the effects of static and dynamic disorder -- structural and energetic -- and from inherently strong electron-vibration couplings. We discuss how solar-cell device architectures can evolve to use coherence-exploiting materials, and we speculate as to the prospects for a coherent energy conversion system. We conclude with a survey of the impacts of coherence and bioinspiration on diverse solar-energy harvesting solutions, including artificial photosynthetic systems.

  15. Biological optimization systems for enhancing photosynthetic efficiency and methods of use

    Science.gov (United States)

    Hunt, Ryan W.; Chinnasamy, Senthil; Das, Keshav C.; de Mattos, Erico Rolim

    2012-11-06

    Biological optimization systems for enhancing photosynthetic efficiency and methods of use. Specifically, methods for enhancing photosynthetic efficiency including applying pulsed light to a photosynthetic organism, using a chlorophyll fluorescence feedback control system to determine one or more photosynthetic efficiency parameters, and adjusting one or more of the photosynthetic efficiency parameters to drive the photosynthesis by the delivery of an amount of light to optimize light absorption of the photosynthetic organism while providing enough dark time between light pulses to prevent oversaturation of the chlorophyll reaction centers are disclosed.

  16. ENHANCED PRACTICAL PHOTOSYNTHETIC CO2 MITIGATION

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Gregory Kremer; Dr. David J. Bayless; Dr. Morgan Vis; Dr. Michael Prudich; Dr. Keith Cooksey; Dr. Jeff Muhs

    2001-10-15

    This report documents significant achievements in the Enhanced Practical Photosynthetic CO{sub 2} Mitigation project during the period from 10/03/2000 through 10/02/2001. Most of the achievements are milestones in our efforts to complete the tasks and subtasks that constitute the project objectives. This is the fourth quarterly report for this project, so it also serves as a year-1 project review. We have made significant progress on our Phase I objectives, and our current efforts are focused on fulfilling these research objectives ''on time'' relative to the project timeline. Overall, we believe that we are on schedule to complete Phase I activities by 10/2002, which is the milestone date from the original project timeline. Our results to date concerning the individual factors which have the most significant effect on CO{sub 2} uptake are inconclusive, but we have gathered useful information about the effects of lighting, temperature and CO{sub 2} concentration on one particular organism (Nostoc) and significant progress has been made in identifying other organisms that are more suitable for use in the bioreactor due to their better tolerance for the high temperatures likely to be encountered in the flue gas stream. Our current tests are focused on one such thermophilic organism (Cyanidium), and an enlarged bioreactor system (CRF-2) has been prepared for testing this organism. Tests on the enhanced mass transfer CO{sub 2} absorption technique are underway and useful information is currently being collected concerning pressure drop. The solar collectors for the deep-penetration hybrid solar lighting system have been designed and a single solar collector tracking unit is being prepared for installation in the pilot scale bioreactor system currently under construction. Much progress has been made in designing the fiber optic light delivery system, but final selection of the ''optimum'' delivery system design depends on many

  17. ENHANCED PRACTICAL PHOTOSYNTHETIC CO2 MITIGATION

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Gregory Kremer; Dr. David J. Bayless; Dr. Morgan Vis; Dr. Michael Prudich; Dr. Keith Cooksey; Dr. Jeff Muhs

    2002-07-15

    This quarterly report documents significant achievements in the Enhanced Practical Photosynthetic CO{sub 2} Mitigation project during the period from 4/2/2001 through 7/01/2002. Most of the achievements are milestones in our efforts to complete the tasks and subtasks that constitute the project objectives, and we are currently on schedule to complete Phase I activities by 10/2002, the milestone date from the original project timeline. As indicated in the list of accomplishments below, our efforts are focused on improving the design of the bioreactor test system, evaluating candidate organisms and growth surfaces, and scaling-up the test facilities from bench scale to pilot scale. Specific results and accomplishments for the second quarter of 2002 include: Organisms and Growth Surfaces: (1) Our collection of cyanobacteria, isolated in YNP was increased to 15 unialgal cultures. (2) Illumination rate about 50 {micro}E/m{sup 2}/sec is not saturated for the growth of 1.2 s.c. (2) isolate. The decrease of illumination rate led to the decrease of doubling time of this isolate. (3) The positive effect of Ca{sup 2+} on the growth of isolate 1.2 s.c. (2) without Omnisil was revealed, though Ca{sup 2+} addition was indifferent for the growth of this isolate at the presence of Omnisil. (4) Calcium addition had a positive effect on the generation of cyanobacterial biofilm on Omnisil surface. (5) The survivability problems with the Tr9.4 organism on Omnisil screens in the CRF2 model-scale bioreactor have been solved. The problems were related to the method used to populate the growth surfaces. When pre-populated screens were placed in the bioreactor the microalgae died within 72 hours, but when the microalgae were cultured while in place in the bioreactor using a continuous-population method they grew well inside of the CRF2 test system and survived for the full 7-day test duration. CRF2 tests will continue as soon as the new combined drip system/harvesting system header pipe

  18. ENHANCED PRACTICAL PHOTOSYNTHETIC CO2 MITIGATION

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Gregory Kremer; Dr. David J. Bayless; Dr. Morgan Vis; Dr. Michael Prudich; Dr. Keith Cooksey; Dr. Jeff Muhs

    2002-01-15

    This quarterly report documents significant achievements in the Enhanced Practical Photosynthetic CO{sub 2} Mitigation project during the period from 10/3/2001 through 1/02/2002. Most of the achievements are milestones in our efforts to complete the tasks and subtasks that constitute the project objectives. Our research team has made significant progress towards completion of our Phase I objectives, and our current efforts remain focused on fulfilling these research objectives in accordance with the project timeline. Overall, we believe that we are on schedule to complete Phase I activities by 10/2002, which is the milestone date from the original project timeline. Specific results and accomplishments for the fourth quarter of 2001 include: (1) New procedures and protocols have been developed to increase the chances of successful implementation in the bioreactor of organisms that perform well in the lab. The new procedures include pre-screening of organisms for adhesion characteristics and a focus on identifying the organisms with maximum growth rate potential. (2) Preliminary results show an increase in adhesion to glass and a decrease in overall growth rates when using growth media prepared with tap water rather than distilled water. (3) Several of the organisms collected from Yellowstone National Park using the new procedures are currently being cultured in preparation for bioreactor tests. (4) One important result from a test of growth surface temperature distribution as a function of gas stream and drip-fluid temperatures showed a high dependence of membrane temperature on fluid temperature, with gas stream temperature having minimal effect. This result indicates that bioreactor growth surface temperatures can be controlled using fluid delivery temperature. The possible implications for implementation of the bioreactor concept are encouraging, since it may be possible to use the bioreactor with very high gas stream temperatures by controlling the temperature

  19. Enhanced Practical Photosynthetic CO2 Mitigation

    Energy Technology Data Exchange (ETDEWEB)

    Gregory Kremer; David J. Bayless; Morgan Vis; Michael Prudich; Keith Cooksey; Jeff Muhs

    2003-07-22

    This quarterly report documents significant achievements in the Enhanced Practical Photosynthetic CO{sub 2} Mitigation project during the period from 4/2/2003 through 7/01/2003. As indicated in the list of accomplishments below we have completed some long-term model scale bioreactor tests and are prepared to begin pilot scale bioreactor testing. Specific results and accomplishments for the second quarter of 2003 include: (1) Bioreactor support systems and test facilities: (a) Qualitative long-term survivability tests for S.C.1.2(2) on Omnisil have been successfully completed and results demonstrate a growth rate that appears to be acceptable. (b) Quantitative tests of long-term growth productivity for S.C.1.2(2) on Omnisil have been completed and initial results are promising. Initial results show that the mass of organisms doubled (from 54.9 grams to 109.8 grams) in about 5 weeks. Full results will be available as soon as all membranes and filters are completely dried. The growth rate should increase significantly with the initiation of weekly harvesting during the long term tests. (c) The phase 1 construction of the pilot scale bioreactor has been completed, including the solar collector and light distribution system. We are now in the phase of system improvement as we wait for CRF-2 results in order to be able to finalize the design and construction of the pilot scale system. (d) A mass transfer experimental setup was constructed in order to measure the mass transfer rate from the gas to the liquid film flowing over a membrane and to study the hydrodynamics of the liquid film flowing over a membrane in the bioreactor. Results were reported for mass transfer coefficient, film thickness, and fluid velocity over an Omnisil membrane with a ''drilled hole'' header pipe design. (2) Organisms and Growth Surfaces: (a) A selectivity approach was used to obtain a cyanobacterial culture with elevated resistance to acid pH. Microlonies of ''3

  20. Active Marine Station Metadata

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Active Marine Station Metadata is a daily metadata report for active marine bouy and C-MAN (Coastal Marine Automated Network) platforms from the National Data...

  1. Marine fungi: A critique

    Digital Repository Service at National Institute of Oceanography (India)

    Raghukumar, S.; Raghukumar, C.

    Obligate marine fungi, those which grow and sporulate exclusively under marine conditions, have received all the attention from marine mycologists. Fungi originating from freshwater, or terrestrial environment and capable of growth and sporulation...

  2. Marine Lubricants

    Science.gov (United States)

    Carter, B. H.; Green, D.

    Marine diesel engines are classified by speed, either large (medium speed) or very large (slow speed) with high efficiencies and burning low-quality fuel. Slow-speed engines, up to 200 rpm, are two-stroke with separate combustion chamber and sump connected by a crosshead, with trunk and system oil lubricants for each. Medium-speed diesels, 300-1500 rpm, are of conventional automotive design with one lubricant. Slow-speed engines use heavy fuel oil of much lower quality than conventional diesel with problems of deposit cleanliness, acidity production and oxidation. Lubricants are mainly SAE 30/40/50 monogrades using paraffinic basestocks. The main types of additives are detergents/dispersants, antioxidants, corrosion inhibitors, anti-wear/load-carrying/ep, pour-point depressants and anti-foam compounds. There are no simple systems for classifying marine lubricants, as for automotive, because of the wide range of engine design, ratings and service applications they serve. There are no standard tests; lubricant suppliers use their own tests or the Bolnes 3DNL, with final proof from field tests. Frequent lubricant analyses safeguard engines and require standard sampling procedures before determination of density, viscosity, flash point, insolubles, base number, water and wear metal content.

  3. The effect of temperature on photosynthetic induction under fluctuating light in Chrysanthemum morifolium

    DEFF Research Database (Denmark)

    Öztürk, Isik; Ottosen, Carl-Otto; Ritz, Christian

    2013-01-01

    The temporal course of photosynthetic induction was investigated on Chrysanthemum morifolium under dynamic light and temperature conditions to evaluate the effect of climatic variables on photosynthetic induction. The Plant material was grown under uniform, controlled conditions and analyzed...

  4. On the photosynthetic and devlopmental responses of leaves to the spectral composition of light

    NARCIS (Netherlands)

    Hogewoning, S.W.

    2010-01-01

    Key words: action spectrum, artificial solar spectrum, blue light, Cucumis sativus, gas-exchange, light-emitting diodes (LEDs), light interception, light quality, non-photosynthetic pigments, photo-synthetic capacity, photomorphogenesis, photosystem excitation balance, quantum yield, red light. A

  5. Photosynthetic Microbial Mats are Exemplary Sources of Diverse Biosignatures (Invited)

    Science.gov (United States)

    Des Marais, D. J.; Jahnke, L. L.

    2013-12-01

    Marine cyanobacterial microbial mats are widespread, compact, self-contained ecosystems that create diverse biosignatures and have an ancient fossil record. Within the mats, oxygenic photosynthesis provides organic substrates and O2 to the community. Both the absorption and scattering of light change the intensity and spectral composition of incident radiation as it penetrates a mat. Some phototrophs utilize infrared light near the base of the photic zone. A mat's upper layers can become highly reduced and sulfidic at night. Counteracting gradients of O2 and sulfide shape the chemical environment and provide daily-contrasting microenvironments separated on a scale of a few mm. Radiation hazards (UV, etc.), O2 and sulfide toxicity elicit motility and other physiological responses. This combination of benefits and hazards of light, O2 and sulfide promotes the allocation of various essential mat processes between light and dark periods and to various depths in the mat. Associated nonphotosynthetic communities, including anaerobes, strongly influence many of the ecosystem's overall characteristics, and their processes affect any biosignatures that enter the fossil record. A biosignature is an object, substance and/or pattern whose origin specifically requires a biological agent. The value of a biosignature depends not only on the probability of life creating it, but also on the improbability of nonbiological processes producing it. Microbial mats create biosignatures that identify particular groups of organisms and also reveal attributes of the mat ecosystem. For example, branched hydrocarbons and pigments can be diagnostic of cyanobacteria and other phototrophic bacteria, and isoprenoids can indicate particular groups of archea. Assemblages of lipid biosignatures change with depth due to changes in microbial populations and diagenetic transformations of organic matter. The 13C/12C values of organic matter and carbonates reflect isotopic discrimination by particular

  6. Enhanced Practical Photosynthetic CO2 Mitigation

    Energy Technology Data Exchange (ETDEWEB)

    Gregory Kremer; David J. Bayless; Morgan Vis; Michael Prudich; Keith Cooksey; Jeff Muhs

    2006-01-15

    This final report highlights significant achievements in the Enhanced Practical Photosynthetic CO{sub 2} Mitigation Project during the period from 10/1/2001 through 01/02/2006. As indicated in the list of accomplishments below, our efforts during this project were focused on the selection of candidate organisms and growth surfaces and initiating long-term tests in the bench-scale and pilot-scale bioreactor test systems. Specific results and accomplishments for the program include: (1) CRF-2 test system: (a) Sampling test results have shown that the initial mass of algae loaded into the Carbon Recycling Facility Version 2 (CRF-2) system can be estimated with about 3% uncertainty using a statistical sampling procedure. (b) The pressure shim header pipe insert design was shown to have better flow for harvesting than the drilled-hole design. (c) The CRF-2 test system has undergone major improvements to produce the high flow rates needed for harvesting (as determined by previous experiments). The main changes to the system are new stainless steel header/frame units, with increased flow capacity and a modified pipe-end-sealing method to improve flow uniformity, and installation and plumbing for a new high flow harvesting pump. Qualitative system tests showed that the harvesting system performed wonderfully, cleaning the growth surfaces within a matter of seconds. (d) Qualitative tests have shown that organisms can be repopulated on a harvested section of a bioreactor screen, demonstrating that continuous bioreactor operation is feasible, with continuous cycles of harvesting and repopulating screens. (e) Final preparations are underway for quantitative, long-term tests in the CRF-2 with weekly harvesting. (2) Pilot-scale test system: (a) The construction of the pilot-scale bioreactor was completed, including the solar collector and light distribution system. Over the course of the project, the solar collector used in the light delivery system showed some degradation, but

  7. Marine biosecurity: protecting indigenous marine species

    OpenAIRE

    Cook, Elizabeth; Brown,Sarah; Payne,Robin; Macleod,Adrian

    2016-01-01

    Elizabeth J Cook,1 Robin D Payne,2 Adrian K Macleod,3 Sarah F Brown4 1Scottish Association for Marine Science, Scottish Marine Institute, Oban, Argyll, 2Alyth, Perthshire, 3Scottish Association for Marine Science Research Services Limited, Scottish Marine Institute, Oban, Argyll, 4Firth of Clyde Forum, Glasgow, UK Abstract: Nonindigenous species (NIS) are those that have been intentionally or unintentionally introduced outside of their native range as a consequence of human activity. If thes...

  8. Changes in photosynthetic properties and antioxidative system of ...

    African Journals Online (AJOL)

    Seedlings of the Cuiguan cultivar of the Asian pear (Pyrus pyrifolia) were used to study the effects of boron toxicity on leaf photosynthetic properties and lipid peroxidation. The plants were grown hydroponically and treated with four concentrations of boron: 10 (CK), 100, 300 and 500 μmol·L-1. After 16 weeks of treatment, ...

  9. Variation of photosynthetic tolerance of rice cultivars (Oryza sativa L ...

    African Journals Online (AJOL)

    STORAGESEVER

    2010-03-01

    Mar 1, 2010 ... and cultivars that have intermediate tolerance to chilling in the light such as hybrid rice cultivar. Photosynthetic characteristics of two cultivars tolerant (c.v. Taipei309 and Wuyujing3), two cultivars sensitive (c.v.CA212 and Pusa) and two intermediated tolerant (c.v. Liangyoupeijiu and Shanyou63) to.

  10. Continuous Cultivation of Photosynthetic Bacteria for Fatty Acids Production

    DEFF Research Database (Denmark)

    Kim, Dong-Hoon; Lee, Ji-Hye; Hwang, Yuhoon

    2013-01-01

    In the present work, we introduced a novel approach for microbial fatty acids (FA) production. Photosynthetic bacteria, Rhodobacter sphaeroides KD131, were cultivated in a continuous-flow, stirred-tank reactor (CFSTR) at various substrate (lactate) concentrations.At hydraulic retention time (HRT) 4....... sphaeroides was around 35% of dry cell weight, mainly composed of vaccenic acid (C18:1, omega-7)....

  11. Effect of plant density on the characteristics of photosynthetic ...

    African Journals Online (AJOL)

    ajl yemi

    2011-11-14

    Nov 14, 2011 ... of stand density on the photosynthetic apparatus of the garlic plant. These effects were found to ... correlation between crop growth rate (CGR) and the leaf area index ..... and Quantity of garlic as Affected by Different Farming Systems and. Garlic Clones. Pak. ... light and carbon dioxide? Bioscience, 47(11): ...

  12. Variability of photosynthetic pigments in the Colombian Pacific ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 111; Issue 3. Variability of photosynthetic pigments in the Colombian Pacific Ocean and its relationship with the wind field using ADEOS-I data. Efrain Rodriguez-Rubio Jose Stuardo. Volume 111 Issue 3 September 2002 pp 227-236 ...

  13. Photosynthetic behaviour of Arabidopsis thaliana (Pa-1 accession ...

    African Journals Online (AJOL)

    The growth reduction observed in many plants caused by salinity is often associated with a decrease in their photosynthetic capacity. This effect could be associated with the partial stomatal closure and/or the non-stomatal limitation which involves the decrease in ribulose-1,5-bisphosphate carboxylase oxygenase ...

  14. Photosynthetic activity of isolated chloroplast fragments of Spirogyra

    NARCIS (Netherlands)

    Thomas, J.B.; Haans, A.J.M.; Leun, A.A.J. van der; Koning, J.

    1957-01-01

    Suspensions of fragmented Spirogyra chloroplasts were prepared and their capacity for photosynthetic oxygen evolution and carbon dioxide reduction was studied by means of manometry and mass spectrometry. No special substances, enzymes or cofactors were added to the suspensions. The rates of

  15. Photosynthetic Responses of Seedlings of two Indigenous Plants ...

    African Journals Online (AJOL)

    Bheema

    ABSTRACT. The potential role of exotic tree plantations in facilitating successional processes on degraded areas was evaluated in southern Ethiopia, Munessa-Shashemene forest, by examining photosynthetic responses of Bersamaabyssinica Fres. and Croton macrostachyusDel. seedlings naturally grown inside ...

  16. An Improved Method for Extraction and Separation of Photosynthetic Pigments

    Science.gov (United States)

    Katayama, Nobuyasu; Kanaizuka, Yasuhiro; Sudarmi, Rini; Yokohama, Yasutsugu

    2003-01-01

    The method for extracting and separating hydrophobic photosynthetic pigments proposed by Katayama "et al." ("Japanese Journal of Phycology," 42, 71-77, 1994) has been improved to introduce it to student laboratories at the senior high school level. Silica gel powder was used for removing water from fresh materials prior to…

  17. Photoconversion of organic substrates into hydrogen using photosynthetic bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Weaver, P. F.

    1981-03-01

    Under nitrogen-limited conditions, photosynthetic bacteria photoconvert a wide variety of organic substrates nearly totally into H/sub 2/ and CO/sub 2/. More than 98% of the chemical energy of defined organic compounds even from dilute solutions can be recovered as combustible energy of the H/sub 2/ produced. Not calculating the chemical energy input, radiant (solar) energy recoveries are approximately 5% over a wide range of incident light intensities. Batch cultures can photoproduce H/sub 2/ at rates of 175 ml per gram dry weight of cells per hour (equal to a volume of H/sub 2/ per equivalent volume of liquid medium every 4 to 6 hours) when incubated in saturating light. With periodic refeeding, rates remain constant for several weeks. In closed containers H/sub 2/ pressures of 735 psig can be generated. In principle, this pressure can be used to decrease storage volume of the gas, to move it through pipelines or to provide required process pressures. Alcohol stillage and food processing wastes are excellent photoconvertible substances. When non-photosynthetic bacteria synthesizing appropriate polysaccharases are included in co-culture with photosynthetic bacteria, cellulose and other polysaccharides can be converted to H/sub 2/ and CO/sub 2/, albeit at low rates. Prospects for enhancing the photoconversion reactions of photosynthetic bacteria by environmental and genetic manipulations are discussed.

  18. Photosynthetic Responses of Seedlings of two Indigenous Plants ...

    African Journals Online (AJOL)

    The potential role of exotic tree plantations in facilitating successional processes on degraded areas was evaluated in southern Ethiopia, Munessa-Shashemene forest, by examining photosynthetic responses of Bersamaabyssinica Fres. and Croton macrostachyusDel. seedlings naturally grown inside plantations of ...

  19. The role of energy losses in photosynthetic light harvesting

    NARCIS (Netherlands)

    Kruger, T. P. J.; van Grondelle, R.

    2017-01-01

    Photosynthesis operates at the bottom of the food chain to convert the energy of light into carbohydrates at a remarkable global rate of about 130 TW. Nonetheless, the overall photosynthetic process has a conversion efficiency of a few percent at best, significantly less than bottom-up photovoltaic

  20. Photosynthetic responses of pea plants (Pisum sativum L. cv. Little ...

    African Journals Online (AJOL)

    STORAGESEVER

    2008-08-04

    Aug 4, 2008 ... Full Length Research Paper. Photosynthetic responses of pea plants ... were measured three times during vegetative and reproductive stages with portable gas exchange system (LI-COR 6400). In general, Pn ..... ultraviolet-B (UV-B) radiation, carbon dioxide (CO2) ozone (O3) on vegetation. Environ. Pollut.

  1. The effect of dispersed Petrobaltic oil droplet size on photosynthetically active radiation in marine environment.

    Science.gov (United States)

    Haule, Kamila; Freda, Włodzimierz

    2016-04-01

    Oil pollution in seawater, primarily visible on sea surface, becomes dispersed as an effect of wave mixing as well as chemical dispersant treatment, and forms spherical oil droplets. In this study, we examined the influence of oil droplet size of highly dispersed Petrobaltic crude on the underwater visible light flux and the inherent optical properties (IOPs) of seawater, including absorption, scattering, backscattering and attenuation coefficients. On the basis of measured data and Mie theory, we calculated the IOPs of dispersed Petrobaltic crude oil in constant concentration, but different log-normal size distributions. We also performed a radiative transfer analysis, in order to evaluate the influence on the downwelling irradiance Ed, remote sensing reflectance Rrs and diffuse reflectance R, using in situ data from the Baltic Sea. We found that during dispersion, there occurs a boundary size distribution characterized by a peak diameter d0  = 0.3 μm causing a maximum E d increase of 40% within 0.5-m depth, and the maximum Ed decrease of 100% at depths below 5 m. Moreover, we showed that the impact of size distribution on the "blue to green" ratios of Rrs and R varies from 24% increase to 27% decrease at the same crude oil concentration.

  2. Evolution and functional diversification of fructose bisphosphate aldolase genes in photosynthetic marine diatoms.

    Science.gov (United States)

    Allen, Andrew E; Moustafa, Ahmed; Montsant, Anton; Eckert, Angelika; Kroth, Peter G; Bowler, Chris

    2012-01-01

    Diatoms and other chlorophyll-c containing, or chromalveolate, algae are among the most productive and diverse phytoplankton in the ocean. Evolutionarily, chlorophyll-c algae are linked through common, although not necessarily monophyletic, acquisition of plastid endosymbionts of red as well as most likely green algal origin. There is also strong evidence for a relatively high level of lineage-specific bacterial gene acquisition within chromalveolates. Therefore, analyses of gene content and derivation in chromalveolate taxa have indicated particularly diverse origins of their overall gene repertoire. As a single group of functionally related enzymes spanning two distinct gene families, fructose 1,6-bisphosphate aldolases (FBAs) illustrate the influence on core biochemical pathways of specific evolutionary associations among diatoms and other chromalveolates with various plastid-bearing and bacterial endosymbionts. Protein localization and activity, gene expression, and phylogenetic analyses indicate that the pennate diatom Phaeodactylum tricornutum contains five FBA genes with very little overall functional overlap. Three P. tricornutum FBAs, one class I and two class II, are plastid localized, and each appears to have a distinct evolutionary origin as well as function. Class I plastid FBA appears to have been acquired by chromalveolates from a red algal endosymbiont, whereas one copy of class II plastid FBA is likely to have originated from an ancient green algal endosymbiont. The other copy appears to be the result of a chromalveolate-specific gene duplication. Plastid FBA I and chromalveolate-specific class II plastid FBA are localized in the pyrenoid region of the chloroplast where they are associated with β-carbonic anhydrase, which is known to play a significant role in regulation of the diatom carbon concentrating mechanism. The two pyrenoid-associated FBAs are distinguished by contrasting gene expression profiles under nutrient limiting compared with optimal CO2 fixation conditions, suggestive of a distinct specialized function for each. Cytosolically localized FBAs in P. tricornutum likely play a role in glycolysis and cytoskeleton function and seem to have originated from the stramenopile host cell and from diatom-specific bacterial gene transfer, respectively.

  3. Protein structure, electron transfer and evolution of prokaryotic photosynthetic reaction centers

    Science.gov (United States)

    Blankenship, R. E.

    1994-01-01

    Photosynthetic reaction centers from a variety of organisms have been isolated and characterized. The groups of prokaryotic photosynthetic organisms include the purple bacteria, the filamentous green bacteria, the green sulfur bacteria and the heliobacteria as anoxygenic representatives as well as the cyanobacteria and prochlorophytes as oxygenic representatives. This review focuses on structural and functional comparisons of the various groups of photosynthetic reaction centers and considers possible evolutionary scenarios to explain the diversity of existing photosynthetic organisms.

  4. Photosynthetic and respiratory characterization of field grown tomato.

    Science.gov (United States)

    Bolaños, J A; Hsiao, T C

    1991-04-01

    The photosynthetic responses of tomato (Lycopersicum esculentum Mill.) leaves to environmental and ontogenetic factors were determined on plants grown in the field under high radiation and high nitrogen fertilization. Response curves showed net photosynthesis to only approach light saturation at a photosynthetic photon flux density (PPFD) of 2200 μmol m(-2) s(-1), with rates of approx. 40 μmol CO2 m(-2) s(-1). A broad temperature optimum was observed between 25° and 35°C, with 50% of the photosynthetic rates remaining even at 47°C. The high rate, the lack of saturation at the equivalent of full sunlight, and the tolerance to high temperature of tomato were unusual in light of the literature on this C3 species. Apparently, acclimation to the field environment of high radiation and hot daytime temperature, coupled with the high nitrogen nutrition, made possible the high photosynthetic performance normally associated with C4 species.Photosynthetic ability of the leaf reached a maximum near the time of its full expansion and declined steadily thereafter, regardless of the time of leaf initiation. Leaf nitrogen content showed a similar decline with leaf ontogeny. Photosynthesis was linearly correlated with nitrogen content, whether the nitrogen variation was due to leaf age or rates of nitrogen fertilization. Internal CO2 concentrations (Ci) of the leaf indicated that stomatal function was well coordinated with photosynthetic capacity as leaf age and fluence rate varied down to a PPFD of 500 μmol m(-2) s(-1). As PPFD decreased further, there was less stomatal control and Ci increased to as high as 320 μ bar bar(-1).Dark respiration was highest for expanding leaves and increased nearly exponentially with temperature. Respiration was also highest for young and expanding fruits, and next highest for fruits just turning pink. Fruit respiration increased approximately linearly with temperature, and was estimated to be an important component of the CO2 flux of the

  5. International Marine Biotechnology Culture Collection (IMBCC)

    Energy Technology Data Exchange (ETDEWEB)

    Zaborsky, O.R.; Baker, K. [Univ. of Hawaii at Manoa, Honolulu, HI (United States)

    1996-10-01

    The objective of this project is to establish a premier culture collection of tropical marine microorganisms able to generate hydrogen from water or organic substances. Both eukaryotic and prokaryotic microorganisms will serve as the biological reservoir or {open_quotes}library{close_quotes} for other DOE Hydrogen Program contractors, the biohydrogen research community and industry. This project consists of several tasks: (a) transfer of the Mitsui-Miami strains to Hawaii`s International Marine Biotechnology Culture Collection (IMBCC) housed at the Hawaii Natural Energy Institute (HNEI); (b) maintain and distribute Mitsui-Miami strains; (c) characterize key strains by traditional and advanced biotechnological techniques; (d) expand Hawaii`s IMBCC; and (e) establish and operate an information resource (database). The project was initiated only late in the summer of 1995 but progress has been made on all tasks. Of the 161 cyanobacterial strains imported, 147 survived storage and importation and 145 are viable. with most exhibiting growth. Of the 406 strains of other photosynthetic bacteria imported, 392 survived storage and importation and 353 are viable, with many exhibiting growth. This project is linked to cooperative efforts being supported by the Japanese Ministry of International Trade and Industry (MITI) through its Marine Biotechnology Institute (MBI) and Research Institute of Innovative Technology for the Earth (RITE).

  6. Engineering photosynthetic organisms for the production of biohydrogen.

    Science.gov (United States)

    Dubini, Alexandra; Ghirardi, Maria L

    2015-03-01

    Oxygenic photosynthetic organisms such as green algae are capable of absorbing sunlight and converting the chemical energy into hydrogen gas. This process takes advantage of the photosynthetic apparatus of these organisms which links water oxidation to H2 production. Biological H2 has therefore the potential to be an alternative fuel of the future and shows great promise for generating large scale sustainable energy. Microalgae are able to produce H2 under light anoxic or dark anoxic condition by activating 3 different pathways that utilize the hydrogenases as catalysts. In this review, we highlight the principal barriers that prevent hydrogen production in green algae and how those limitations are being addressed, through metabolic and genetic engineering.  We also discuss the major challenges and bottlenecks facing the development of future commercial algal photobiological systems for H2 production. Finally we provide suggestions for future strategies and potential new techniques to be developed towards an integrated system with optimized hydrogen production.

  7. Spatial coherence of thermal photons favors photosynthetic life

    CERN Document Server

    Manrique, Pedro; Caycedo-Soler, Felipe; Rodríguez, Ferney; Quiroga, Luis; Johnson, Neil

    2015-01-01

    Harvesting of sunlight underpins Life on Earth as well as driving novel energy device design. Though several experiments suggest that excitation energy transport and charge separation within a photosynthetic membrane may benefit from the quantum nature of their dynamics, the effects of spatial coherences in the incident light have been largely ignored. Here we show that spatial correlations in the incident light likely play an important role in trapping light and adding robustness, as well as providing a driving mechanism for an organism's adaptation toward more ordered structures. Our theory is grounded by empirical inputs, while its output is validated against testable predictions. Our results suggest that spatiotemporal correlations between photons, a fundamental property of the quantum world, should play a key role in our understanding of early Life and in improving the design of artificial photosynthetic systems.

  8. Photosynthetic planulae and planktonic hydroids: contrasting strategies of propagule survival

    Directory of Open Access Journals (Sweden)

    Patrizia Pagliara

    2000-12-01

    Full Text Available Settlement delays can be important to prevent propagule waste when proper settling substrates are not immediately available. Under laboratory conditions, the planulae of Clytia viridicans underwent two alternative developmental patterns. Some settled on the bottom, forming a hydranth-gonotheca complex that produced up to four medusae and later either degenerated or gave rise to a hydroid colony. Other planulae settled right below the air-water interface, forming floating colonies that eventually fell to the bottom and settled. Halecium nanum released planulae with a rich population of symbiotic zooxanthellae that survived into a rearing jar for three months. After a long period of apparent quiescence (possibly fuelled by photosynthetic activities of zooxanthellae the planulae produced new colonies. Both photosynthetic planulae and settlement at the interface air-water allow a delay in the passage from a planktonic to a fully functional benthic life.

  9. Anatomical structure of moss leaves and their photosynthetic activity

    Directory of Open Access Journals (Sweden)

    Jan Krupa

    2014-01-01

    Full Text Available The photosynthetic activity of the leaf area unit increases depending on the degree of differentiation of the anatomical structure of the leaves of six chosen moss species. There is a correlation between the leaf area and the degree of differentiation of the anatomical structure resulting in enlargement of the area of contact of the assimilating cells with air. The leaves of Catharinea undulata having a one-layer blade and provided with several lamellae show a higher photosynthesis per 1 cm2 of their surface than the one-layer leaves of Mniurnm or Funaria. Aloina leaves are the smallest in area among those of the moss species discussed, however, their photosynthetic rate is almost 4.5 times higher than in Funaria leaves. By analogy to the structure of leaves and their function in vascular, plants, these changes and correlations may be considered as attempts of primeval adaptation of mosses to terrestrial conditions of living.

  10. Hydrogen Production by the Photosynthetic Bacterium Rhodospirillum rubrum

    Science.gov (United States)

    Zürrer, Hans; Bachofen, Reinhard

    1979-01-01

    Continuous photosynthetic production of hydrogen by Rhodospirillum rubrum in batch cultures was observed up to 80 days with the hydrogen donor, pure lactate or lactic acid-containing wastes, supplied periodically. Hydrogen was produced at an average rate of 6 ml/h per g (dry weight) of cells with whey as a hydrogen donor. In continuous cultures with glutamate as a growth-limiting nitrogen source and lactate as a hydrogen donor, hydrogen was evolved at a rate of 20 ml/h per g (dry weight). The composition of the gas evolved remained practically constant (70 to 75% H2, 25 to 30% CO2). Photosynthetic bacteria processing specific organic wastes could be an advantage in large-scale production of hydrogen together with food protein of high value, compared to other biological systems. Images PMID:16345375

  11. Hydrogen production by the photosynthetic bacterium Rhodospirillum rubrum

    Energy Technology Data Exchange (ETDEWEB)

    Zuerrer, H.; Bachofen, R.

    1979-05-01

    Continuous photosynthetic production of hydrogen by Rhodospirillum rubrum in batch cultures was observed up to 80 days with the hydrogen donor, pure lactate or lactic acid-containing wastes, supplied periodically. Hydrogen was produced at an average rate of 6 ml/h per g (dry weight) of cells with whey as a hydrogen donor. In continuous cultures with glutamate as a growth-limiting nitrogen source and lactate as a hydrogen donor, hydrogen was evolved at a rate of 20 ml/h per g (dry weight). The composition of the gas evolved remained practically constant (70 to 75% H/sub 2/, 25 to 30% CO/sub 2/). Photosynthetic bacteria processing specific organic wastes could be an advantage in large-scale production of hydrogen together with food protein of high value, compared to other biological systems.

  12. Detecting extraterrestrial life with the Colossus telescope using photosynthetic biosignatures

    Science.gov (United States)

    Berdyugina, S.; Kuhn, J.; Harrington, D.; Moretto, G.; Langlois, M.; Halliday, D.; Harlingten, C.

    2014-03-01

    We propose to search for life on Earth-like planets in habitable zones using photosynthesis biosignatures. Many life forms on Earth process the solar light and utilize it to support their own activity and to provide a valuable energy source for other life forms. We expect therefore that photosynthesis is very likely to arise on another planet and can produce conspicuous biosignatures. We have recently identified biological polarization effects, e.g., selective light absorption or scattering by photosynthetic molecules which can be used for remote detection of extraterrestrial life. Here we present synthetic spectra and polarization of Earth-like planets with photosynthetic life and evaluate the sensitivity of the Colossus telescope for their remote detection in the solar neighborhood.

  13. Photosynthetic responses to phytoplasma infection in Chinese jujube.

    Science.gov (United States)

    Liu, Zhiguo; Zhao, Jin; Liu, Mengjun

    2016-08-01

    Phytoplasma is one of the most devastating plant pathogens. Jujube witches' broom (JWB) is a typical and highly fatal phytoplasma disease of Chinese jujube (Ziziphus jujuba Mill.), which is widely cultivated in Asia. To further elucidate the mechanism of plant-phytoplasma interaction, we first compared the effects of phytoplasma infection on photosynthetic pigments and activities between a JWB-resistant cultivar (Xingguang) and a susceptible cultivar (Pozao). Total chlorophyll and carotenoid levels were significantly decreased in the susceptible cultivar at later stages of infection, but were remarkably increased in the resistant cultivar at the earlier stages. Compared to uninfected plant, a significant decrease in the main photochemical parameters (Fv/Fm, ΦPSII and qP) was recorded at the initial stages of infection in the resistant cultivar, but occurred at later stages in the susceptible cultivar. Meanwhile, the qRT-PCR results of four key photosynthesis-related genes (ZjGluTR, ZjCBP, ZjRubisco and ZjRCA2) demonstrated that the expression patterns were similar in uninfected cultivars, but up-regulated in resistant cultivar and down-regulated in the susceptible one at 12 wks after grafting inoculation. Collectively, our data indicated that the resistant cultivar 'Xingguang' undergoes a decrease in initial stage (inhibiting phytoplasma multiplication) and then a rapid enhancement of photosynthetic activity (helping jujube recovery) in response to phytoplasma infection, while the susceptible cultivar 'Pozao' displays a later decrease in photosynthetic activity. The novel photosynthetic response pattern of the resistant cultivar may contribute to its stronger immunity to phytoplasma infection, which provides new insights into plant-phytoplasma interactions. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  14. Photosynthetic electron transport system promotes synthesis of Au-nanoparticles.

    Directory of Open Access Journals (Sweden)

    Nisha Shabnam

    Full Text Available In this communication, a novel, green, efficient and economically viable light mediated protocol for generation of Au-nanoparticles using most vital organelle, chloroplasts, of the plant system is portrayed. Thylakoids/chloroplasts isolated from Potamogeton nodosus (an aquatic plant and Spinacia oleracea (a terrestrial plant turned Au³⁺ solutions purple in presence of light of 600 µmol m⁻² s⁻¹ photon flux density (PFD and the purple coloration intensified with time. UV-Vis spectra of these purple colored solutions showed absorption peak at ∼545 nm which is known to arise due to surface plasmon oscillations specific to Au-nanoparticles. However, thylakoids/chloroplasts did not alter color of Au³⁺ solutions in dark. These results clearly demonstrated that photosynthetic electron transport can reduce Au³⁺ to Au⁰ which nucleate to form Au-nanoparticles in presence of light. Transmission electron microscopic studies revealed that Au-nanoparticles generated by light driven photosynthetic electron transport system of thylakoids/chloroplasts were in range of 5-20 nm. Selected area electron diffraction and powder X-ray diffraction indicated crystalline nature of these nanoparticles. Energy dispersive X-ray confirmed that these nanoparticles were composed of Au. To confirm the potential of light driven photosynthetic electron transport in generation of Au-nanoparticles, thylakoids/chloroplasts were tested for their efficacy to generate Au-nanoparticles in presence of light of PFD ranging from 60 to 600 µmol m⁻² s⁻¹. The capacity of thylakoids/chloroplasts to generate Au-nanoparticles increased remarkably with increase in PFD, which further clearly demonstrated potential of light driven photosynthetic electron transport in reduction of Au³⁺ to Au⁰ to form nanoparticles. The light driven donation of electrons to metal ions by thylakoids/chloroplasts can be exploited for large scale production of nanoparticles.

  15. Importance of Fluctuations in Light on Plant Photosynthetic Acclimation.

    Science.gov (United States)

    Vialet-Chabrand, Silvere; Matthews, Jack S A; Simkin, Andrew J; Raines, Christine A; Lawson, Tracy

    2017-04-01

    The acclimation of plants to light has been studied extensively, yet little is known about the effect of dynamic fluctuations in light on plant phenotype and acclimatory responses. We mimicked natural fluctuations in light over a diurnal period to examine the effect on the photosynthetic processes and growth of Arabidopsis (Arabidopsis thaliana). High and low light intensities, delivered via a realistic dynamic fluctuating or square wave pattern, were used to grow and assess plants. Plants subjected to square wave light had thicker leaves and greater photosynthetic capacity compared with fluctuating light-grown plants. This, together with elevated levels of proteins associated with electron transport, indicates greater investment in leaf structural components and photosynthetic processes. In contrast, plants grown under fluctuating light had thinner leaves, lower leaf light absorption, but maintained similar photosynthetic rates per unit leaf area to square wave-grown plants. Despite high light use efficiency, plants grown under fluctuating light had a slow growth rate early in development, likely due to the fact that plants grown under fluctuating conditions were not able to fully utilize the light energy absorbed for carbon fixation. Diurnal leaf-level measurements revealed a negative feedback control of photosynthesis, resulting in a decrease in total diurnal carbon assimilated of at least 20%. These findings highlight that growing plants under square wave growth conditions ultimately fails to predict plant performance under realistic light regimes and stress the importance of considering fluctuations in incident light in future experiments that aim to infer plant productivity under natural conditions in the field. © 2017 American Society of Plant Biologists. All Rights Reserved.

  16. Diazotrophy in Modern Marine Bahamian Stromatolites.

    Science.gov (United States)

    Steppe, T.F.; Pinckney, J.L.; Dyble, J.; Paerl, H.W.

    2001-01-01

    N2 fixation (nitrogenase activity), primary production, and diazotrophic community composition of stromatolite mats from Highborne Cay, Exuma, Bahamas, were examined over a 2-year period (1997-1998). The purpose of the study was to characterize the ecophysiology of N2 fixation in modern marine stromatolites. Microbial mats are an integral surface component of these stromatolites and are hypothesized to have a major role in stromatolite formation and growth. The stromatolite mats contained active photosynthetic and diazotrophic assemblages that exhibited temporal separation of nitrogenase activity (NA) and photosynthesis. Maximal NA was detected at night. Seasonal differences in NA and net O2 production were observed. Photosynthetic activity and the availability of reduced organic carbon appear to be the key determinants of NA. Additions of the de novo protein synthesis inhibitor chloramphenicol did not inhibit NA in March 1998, but greatly inhibited NA in August 1998. Partial sequence analysis of the nifH gene indicates that a broad diversity of diazotrophs may be responsible for NA in the stromatolites.

  17. Bacterially mediated precipitation in marine stromatolites.

    Science.gov (United States)

    Paerl, H W; Steppe, T F; Reid, R P

    2001-02-01

    Stromatolites are laminated, lithified (CaCO3) sedimentary deposits formed by precipitation and/or sediment accretion by cyanobacterial-bacterial mat communities. Stromatolites have been associated with these communities as far back as the Precambrian era some 2+ billion years ago. The means by which microbial communities mediate the precipitation processes have remained unclear, and are the subject of considerable debate and speculation. Two alternative explanations for microbially mediated precipitation include: (i) cyanobacterial photosynthesis increases pH in a system supersaturated in respect of CaCO3, resulting in CaCO3 precipitation and then laminated lithification, and (ii) decomposition of cyanobacterial extracellular organic matter (e.g. sheaths, mucilage and organic acids) by microheterotrophs leads to release of organic-bound Ca2+ ions and CaCO3 precipitation. We evaluated these explanations by examining metabolically active, lithifying stromatolitic mat communities from Highborne Cay, Bahamas, using microautoradiography. Microautoradiographic detection of 14CO2 fixation and 3H organic matter (D-glucose and an amino acid mixture) utilization by photosynthetically active cyanobacteria and microheterotrophs, combined with community-level uptake experiments, indicate that bacteria, rather than cyanobacteria are the dominant sites of CaCO3 deposition. In the oligotrophic waters in which stromatolites exist, microheterotrophs are reliant on the photosynthetic community as a main source of organic matter. Therefore, autotrophic production indirectly controls microbially mediated precipitation and stromatolite formation in these shallow marine environments.

  18. Photosynthetic efficiency of Chlamydomonas reinhardtii in flashing light.

    Science.gov (United States)

    Vejrazka, Carsten; Janssen, Marcel; Streefland, Mathieu; Wijffels, René H

    2011-12-01

    Efficient light to biomass conversion in photobioreactors is crucial for economically feasible microalgae production processes. It has been suggested that photosynthesis is enhanced in short light path photobioreactors by mixing-induced flashing light regimes. In this study, photosynthetic efficiency and growth of the green microalga Chlamydomonas reinhardtii were measured using LED light to simulate light/dark cycles ranging from 5 to 100 Hz at a light-dark ratio of 0.1 and a flash intensity of 1000 µmol m(-2) s(-1). Light flashing at 100 Hz yielded the same photosynthetic efficiency and specific growth rate as cultivation under continuous illumination with the same time-averaged light intensity (i.e., 100 µmol m(-2) s(-1)). The efficiency and growth rate decreased with decreasing flash frequency. Even at 5 Hz flashing, the rate of linear electron transport during the flash was still 2.5 times higher than during maximal growth under continuous light, suggesting storage of reducing equivalents during the flash which are available during the dark period. In this way the dark reaction of photosynthesis can continue during the dark time of a light/dark cycle. Understanding photosynthetic growth in dynamic light regimes is crucial for model development to predict microalgal photobioreactor productivities. Copyright © 2011 Wiley Periodicals, Inc.

  19. Photovoltaic concepts inspired by coherence effects in photosynthetic systems

    KAUST Repository

    Bredas, Jean-Luc

    2016-12-20

    The past decade has seen rapid advances in our understanding of how coherent and vibronic phenomena in biological photosynthetic systems aid in the efficient transport of energy from light-harvesting antennas to photosynthetic reaction centres. Such coherence effects suggest strategies to increase transport lengths even in the presence of structural disorder. Here we explore how these principles could be exploited in making improved solar cells. We investigate in depth the case of organic materials, systems in which energy and charge transport stand to be improved by overcoming challenges that arise from the effects of static and dynamic disorder-structural and energetic-and from inherently strong electron-vibration couplings. We discuss how solar-cell device architectures can evolve to use coherence-exploiting materials, and we speculate as to the prospects for a coherent energy conversion system. We conclude with a survey of the impacts of coherence and bioinspiration on diverse solar-energy harvesting solutions, including artificial photosynthetic systems.

  20. Photosynthetic efficiency of Pedunculate oak seedlings under simulated water stress

    Directory of Open Access Journals (Sweden)

    Popović Zorica

    2010-01-01

    Full Text Available Photosynthetic performance of seedlings of Quercus robur exposed to short-term water stress in the laboratory conditions was assessed through the method of induced fluorometry. The substrate for seedlings was clayey loam, with the dominant texture fraction made of silt, followed by clay and fine sand, with total porosity 68.2%. Seedlings were separated in two groups: control (C (soil water regime in pots was maintained at the level of field water capacity and treated (water-stressed, WS (soil water regime was maintained in the range of wilting point and lentocapillary capacity. The photosynthetic efficiency was 0.642±0.25 and 0.522±0.024 (WS and C, respectively, which was mostly due to transplantation disturbances and sporadic leaf chlorosis. During the experiment Fv/Fm decreased in both groups (0.551±0.0100 and 0.427±0.018 in C and WS, respectively. Our results showed significant differences between stressed and control group, in regard to both observed parameters (Fv/Fm and T½. Photosynthetic efficiency of pedunculate oak seedlings was significantly affected by short-term water stress, but to a lesser extent than by sufficient watering.

  1. Photosynthetic temperature responses of Eucalyptus globulus and Eucalyptus nitens

    Energy Technology Data Exchange (ETDEWEB)

    Battaglia, M.; Beadle, C. [Commonwealth Scientific and Industrial Research Organization (CSIRO), Canberra, ACT (Australia). Div. of Forestry and Forest Products; Loughead, S. [Tasmania Univ., Hobart, TAS (Australia)

    1996-01-01

    Photosynthetic responses to temperature variations of four year old Eucalyptus globulus and Eucalyptus nitens were investigated. Temperatures varied between 10 degrees C and 35 degrees C, and were measured at approximately monthly intervals from early spring until midwinter. The photosynthetic temperature optimum was found to be linearly related to the average temperature of the preceding week during the entire nine month period. For E. globulus the optimum temperature for net photosynthesis increased from 17 degrees C to 23 degrees C as the mean daily temperature increased from 7 degrees C to 16 degrees. The corresponding values for E. nitens were 14 to 20 degrees C as the mean daily temperature increased from 7 to 19 degrees C. The photosynthetic performance of E. nitens was less sensitive to temperatures above and below the optimum than E. globulus. In a second experiment E. globulus clones were acclimated in temperature-controlled greenhouses, and in a shadehouse in four climatically different regions of Tasmania. A comparison of light response curves of the plants showed that the maximum rate of net photosynthesis was affected by the growth temperature, whereas apparent quantum efficiency remained unchanged. 25 refs., 3 tabs., 8 figs.

  2. Photosynthetic reaction center as a quantum heat engine.

    Science.gov (United States)

    Dorfman, Konstantin E; Voronine, Dmitri V; Mukamel, Shaul; Scully, Marlan O

    2013-02-19

    Two seemingly unrelated effects attributed to quantum coherence have been reported recently in natural and artificial light-harvesting systems. First, an enhanced solar cell efficiency was predicted and second, population oscillations were measured in photosynthetic antennae excited by sequences of coherent ultrashort laser pulses. Because both systems operate as quantum heat engines (QHEs) that convert the solar photon energy to useful work (electric currents or chemical energy, respectively), the question arises whether coherence could also enhance the photosynthetic yield. Here, we show that both effects arise from the same population-coherence coupling term which is induced by noise, does not require coherent light, and will therefore work for incoherent excitation under natural conditions of solar excitation. Charge separation in light-harvesting complexes occurs in a pair of tightly coupled chlorophylls (the special pair) at the heart of photosynthetic reaction centers of both plants and bacteria. We show the analogy between the energy level schemes of the special pair and of the laser/photocell QHEs, and that both population oscillations and enhanced yield have a common origin and are expected to coexist for typical parameters. We predict an enhanced yield of 27% in a QHE motivated by the reaction center. This suggests nature-mimicking architectures for artificial solar energy devices.

  3. Evidence That Putrescine Modulates the Higher Plant Photosynthetic Proton Circuit

    Science.gov (United States)

    Kotzabasis, Kiriakos; Kramer, David M.

    2012-01-01

    The light reactions of photosynthesis store energy in the form of an electrochemical gradient of protons, or proton motive force (pmf), comprised of electrical (Δψ) and osmotic (ΔpH) components. Both components can drive the synthesis of ATP at the chloroplast ATP synthase, but the ΔpH component also plays a key role in regulating photosynthesis, down-regulating the efficiency of light capture by photosynthetic antennae via the qE mechanism, and governing electron transfer at the cytochrome b6f complex. Differential partitioning of pmf into ΔpH and Δψ has been observed under environmental stresses and proposed as a mechanism for fine-tuning photosynthetic regulation, but the mechanism of this tuning is unknown. We show here that putrescine can alter the partitioning of pmf both in vivo (in Arabidopsis mutant lines and in Nicotiana wild type) and in vitro, suggesting that the endogenous titer of weak bases such as putrescine represents an unrecognized mechanism for regulating photosynthetic responses to the environment. PMID:22253808

  4. Evidence that putrescine modulates the higher plant photosynthetic proton circuit.

    Directory of Open Access Journals (Sweden)

    Nikolaos E Ioannidis

    Full Text Available The light reactions of photosynthesis store energy in the form of an electrochemical gradient of protons, or proton motive force (pmf, comprised of electrical (Δψ and osmotic (ΔpH components. Both components can drive the synthesis of ATP at the chloroplast ATP synthase, but the ΔpH component also plays a key role in regulating photosynthesis, down-regulating the efficiency of light capture by photosynthetic antennae via the q(E mechanism, and governing electron transfer at the cytochrome b(6f complex. Differential partitioning of pmf into ΔpH and Δψ has been observed under environmental stresses and proposed as a mechanism for fine-tuning photosynthetic regulation, but the mechanism of this tuning is unknown. We show here that putrescine can alter the partitioning of pmf both in vivo (in Arabidopsis mutant lines and in Nicotiana wild type and in vitro, suggesting that the endogenous titer of weak bases such as putrescine represents an unrecognized mechanism for regulating photosynthetic responses to the environment.

  5. The role of energy losses in photosynthetic light harvesting

    Science.gov (United States)

    Krüger, T. P. J.; van Grondelle, R.

    2017-07-01

    Photosynthesis operates at the bottom of the food chain to convert the energy of light into carbohydrates at a remarkable global rate of about 130 TW. Nonetheless, the overall photosynthetic process has a conversion efficiency of a few percent at best, significantly less than bottom-up photovoltaic cells. The primary photosynthetic steps, consisting of light harvesting and charge separation, are often presented as having near-unity quantum efficiency but this holds only true under ideal conditions. In this review, we discuss the importance of energy loss mechanisms to establish robustness in photosynthetic light harvesting. Thermal energy dissipation of light-harvesting complexes (LHCs) in different environments is investigated and the relationships and contrasts between concentration quenching of high pigment concentrations, photoprotection (non-photochemical quenching), quenching due to protein aggregation, and fluorescence blinking are discussed. The role of charge-transfer states in light harvesting and energy dissipation is highlighted and the importance of controlled protein structural disorder to switch the light-harvesting antennae between effective light harvesters and efficient energy quenchers is underscored. The main LHC of plants, LHCII, is used as a prime example.

  6. Photosynthetic Reaction Centres-from Basic Research to Application

    Directory of Open Access Journals (Sweden)

    László NAGY

    2010-06-01

    Full Text Available There is no doubt that studying the photosynthetic conversion of light into chemical energy is extremely important in many points of view; e.g., 1 technical-in order to improve the utilization of the solar energy; 2 food production-to improve the photosynthetic production of plants in agriculture; 3 ecology-keeping the primer production in ecosystems in the biosphere balanced, etc. In the photosynthetic reaction centre protein, RC, light energy is converted by a quantum yield of almost unity. There is no such a system designed by human which is able to do that. The RC purified from purple bacteria provides an extremely unique system for studying the requirements for high efficiency conversion of light into electrochemical energy. Thanks to the recent structural (e.g. crystallography (Nobel prize to Michel, Deisenhofer, Huber and functional (Nobel prize to Marcus results together with the works of molecular biology, computer- and electro-techniques, a wealth of information made a relatively clear picture about the kinetics, energetics and stabilization of electron transport within this protein that opens possibilities for new generation practical applications. In this paper we provide a short summary of fields in which the reaction centre protein can be important from practical points of view.

  7. Photosynthetic Reaction Centres – from Basic Research to Application Possibilities

    Directory of Open Access Journals (Sweden)

    Krisztina NAGY

    2010-06-01

    Full Text Available There is no doubt that studying the photosynthetic conversion of light into chemical energy is extremely important in many points of view: 1 technical-in order to improve the utilization of the solar energy; 2 food production – to improve the photosynthetic production of plants in agriculture; 3 ecology – keeping the primer production in ecosystems in the biosphere balanced, etc. In the photosynthetic reaction centre protein, RC, light energy is converted by a quantum yield of almost unity. There is no such a system designed by human which is able to do that. The RC purified from purple bacteria provides an extremely unique system for studying the requirements for high efficiency conversion of light into electrochemical energy. Thanks to the recent structural (e.g. crystallography (Nobel prize to Michel, Deisenhofer, Huber and functional (Nobel prize to Marcus results together with the works of molecular biology, computer- and electro-techniques, a wealth of information made a relatively clear picture about the kinetics, energetics and stabilization of electron transport within this protein that opens possibilities for new generation practical applications. In this paper we provide a short summary of fields in which the reaction centre protein can be important from practical points of view.

  8. Improvement of Photosynthetic Efficiency Through Reduction of Chlorophyll Antenna Size

    Energy Technology Data Exchange (ETDEWEB)

    Blankinship, S.L.; Greenbaum, E.; Lee, J.W.; Mets, L.

    1999-05-03

    We have previously presented a graphical illustration of a strategy to improve photosynthetic conversion efficiencies by a reduction of the antenna size in photosynthetic reaction centers. During the current reporting period, we have made progress in demonstrating the conceptual correctness of this idea. Light-saturation studies for CO, in air were performed with an antenna-deficient mutant of Chlamydomonas (DS521) and the wild type (DES15). The light-saturated rate for CO(2), assimilation in mutant DS521 was about two times higher (187 Mu-mol.h(-1).mg chl(-1)) than that of the wild type, DES15 (95 Mu-mol.h(-1).mg chl(-1). Significantly, a partial linearization of the light-saturation curve was also observed. The light intensities that give half-saturation of the photosynthetic rate were 276 and 152 Mu-E.m(-2).s(-1) in DS521 and DES15, respectively. These results confirmed that DS521 has a smaller chlorophyll antenna size and demonstrated that the reduction of antenna size can indeed improve the overall efficiency of photon utilization. Corresponding experiments were also performed with CO(2), in helium. Under this anaerobic condition, no photoinhibition was observed, even at elevated light intensities. Photoinhibition occurs under aerobic conditions. The antenna-deficient mutant DS521 can also provide significant resistance to photoinhibition, in addition to the improvement in the overall efficiency in CO(2), fixation.

  9. Single-Molecule Fluorescence Spectroscopy of Photosynthetic Systems.

    Science.gov (United States)

    Kondo, Toru; Chen, Wei Jia; Schlau-Cohen, Gabriela S

    2017-01-25

    Photosynthesis begins when a network of pigment-protein complexes captures solar energy and transports it to the reaction center, where charge separation occurs. When necessary (under low light conditions), photosynthetic organisms perform this energy transport and charge separation with near unity quantum efficiency. Remarkably, this high efficiency is maintained under physiological conditions, which include thermal fluctuations of the pigment-protein complexes and changing local environments. These conditions introduce multiple types of heterogeneity in the pigment-protein complexes, including structural heterogeneity, energetic heterogeneity, and functional heterogeneity. Understanding how photosynthetic light-harvesting functions in the face of these fluctuations requires understanding this heterogeneity, which, in turn, requires characterization of individual pigment-protein complexes. Single-molecule spectroscopy has the power to probe individual complexes. In this review, we present an overview of the common techniques for single-molecule fluorescence spectroscopy applied to photosynthetic systems and describe selected experiments on these systems. We discuss how these experiments provide a new understanding of the impact of heterogeneity on light harvesting and thus how these systems are optimized to capture sunlight under physiological conditions.

  10. Evidence that putrescine modulates the higher plant photosynthetic proton circuit.

    Science.gov (United States)

    Ioannidis, Nikolaos E; Cruz, Jeffrey A; Kotzabasis, Kiriakos; Kramer, David M

    2012-01-01

    The light reactions of photosynthesis store energy in the form of an electrochemical gradient of protons, or proton motive force (pmf), comprised of electrical (Δψ) and osmotic (ΔpH) components. Both components can drive the synthesis of ATP at the chloroplast ATP synthase, but the ΔpH component also plays a key role in regulating photosynthesis, down-regulating the efficiency of light capture by photosynthetic antennae via the q(E) mechanism, and governing electron transfer at the cytochrome b(6)f complex. Differential partitioning of pmf into ΔpH and Δψ has been observed under environmental stresses and proposed as a mechanism for fine-tuning photosynthetic regulation, but the mechanism of this tuning is unknown. We show here that putrescine can alter the partitioning of pmf both in vivo (in Arabidopsis mutant lines and in Nicotiana wild type) and in vitro, suggesting that the endogenous titer of weak bases such as putrescine represents an unrecognized mechanism for regulating photosynthetic responses to the environment.

  11. Chromerid genomes reveal the evolutionary path from photosynthetic algae to obligate intracellular parasites

    KAUST Repository

    Woo, Yong

    2015-07-15

    The eukaryotic phylum Apicomplexa encompasses thousands of obligate intracellular parasites of humans and animals with immense socio-economic and health impacts. We sequenced nuclear genomes of Chromera velia and Vitrella brassicaformis, free-living non-parasitic photosynthetic algae closely related to apicomplexans. Proteins from key metabolic pathways and from the endomembrane trafficking systems associated with a free-living lifestyle have been progressively and non-randomly lost during adaptation to parasitism. The free-living ancestor contained a broad repertoire of genes many of which were repurposed for parasitic processes, such as extracellular proteins, components of a motility apparatus, and DNA- and RNA-binding protein families. Based on transcriptome analyses across 36 environmental conditions, Chromera orthologs of apicomplexan invasion-related motility genes were co-regulated with genes encoding the flagellar apparatus, supporting the functional contribution of flagella to the evolution of invasion machinery. This study provides insights into how obligate parasites with diverse life strategies arose from a once free-living phototrophic marine alga. © Woo et al.

  12. Chromerid genomes reveal the evolutionary path from photosynthetic algae to obligate intracellular parasites.

    Science.gov (United States)

    Woo, Yong H; Ansari, Hifzur; Otto, Thomas D; Klinger, Christen M; Kolisko, Martin; Michálek, Jan; Saxena, Alka; Shanmugam, Dhanasekaran; Tayyrov, Annageldi; Veluchamy, Alaguraj; Ali, Shahjahan; Bernal, Axel; del Campo, Javier; Cihlář, Jaromír; Flegontov, Pavel; Gornik, Sebastian G; Hajdušková, Eva; Horák, Aleš; Janouškovec, Jan; Katris, Nicholas J; Mast, Fred D; Miranda-Saavedra, Diego; Mourier, Tobias; Naeem, Raeece; Nair, Mridul; Panigrahi, Aswini K; Rawlings, Neil D; Padron-Regalado, Eriko; Ramaprasad, Abhinay; Samad, Nadira; Tomčala, Aleš; Wilkes, Jon; Neafsey, Daniel E; Doerig, Christian; Bowler, Chris; Keeling, Patrick J; Roos, David S; Dacks, Joel B; Templeton, Thomas J; Waller, Ross F; Lukeš, Julius; Oborník, Miroslav; Pain, Arnab

    2015-07-15

    The eukaryotic phylum Apicomplexa encompasses thousands of obligate intracellular parasites of humans and animals with immense socio-economic and health impacts. We sequenced nuclear genomes of Chromera velia and Vitrella brassicaformis, free-living non-parasitic photosynthetic algae closely related to apicomplexans. Proteins from key metabolic pathways and from the endomembrane trafficking systems associated with a free-living lifestyle have been progressively and non-randomly lost during adaptation to parasitism. The free-living ancestor contained a broad repertoire of genes many of which were repurposed for parasitic processes, such as extracellular proteins, components of a motility apparatus, and DNA- and RNA-binding protein families. Based on transcriptome analyses across 36 environmental conditions, Chromera orthologs of apicomplexan invasion-related motility genes were co-regulated with genes encoding the flagellar apparatus, supporting the functional contribution of flagella to the evolution of invasion machinery. This study provides insights into how obligate parasites with diverse life strategies arose from a once free-living phototrophic marine alga.

  13. Photosynthetic Picoeukaryotes in the Land-Fast Ice of the White Sea, Russia.

    Science.gov (United States)

    Belevich, T A; Ilyash, L V; Milyutina, I A; Logacheva, M D; Goryunov, D V; Troitsky, A V

    2017-09-24

    The White Sea is a unique marine environment combining features of temperate and Arctic seas. The composition and abundance of photosynthetic picoeukaryotes (PPEs) were investigated in the land-fast ice of the White Sea, Russia, in March 2013 and 2014. High-throughput tag sequencing (Illumina MiSeq system) of the V4 region of the 18S rRNA gene was used to reveal the diversity of PPE ice community. The integrated PPE abundance varied from 11 × 10 6 cells/m 2 to 364 × 10 6 cells/m 2 ; the integrated biomass ranged from 0.02 to 0.26 mg С/m 2 . The composition of sea-ice PPEs was represented by 16 algae genera belonging to eight classes and three super-groups. Chlorophyta, especially Mamiellophyceae, dominated among ice PPEs. The detailed analysis revealed the latent diversity of Micromonas and Mantоniella. Micromonas clade E2 revealed in the subarctic White Sea ice indicates that the area of distribution of this species is wider than previously thought. We suppose there exists a new Micromonas clade F. Micromonas clade C and Minutocellulus polymorphus were first discovered in the ice and extend the modern concept of sympagic communities' diversity generally and highlights the importance of further targeting subarctic sea ice for microbial study.

  14. Environmental science. Rethinking the marine carbon cycle: factoring in the multifarious lifestyles of microbes.

    Science.gov (United States)

    Worden, Alexandra Z; Follows, Michael J; Giovannoni, Stephen J; Wilken, Susanne; Zimmerman, Amy E; Keeling, Patrick J

    2015-02-13

    The profound influence of marine plankton on the global carbon cycle has been recognized for decades, particularly for photosynthetic microbes that form the base of ocean food chains. However, a comprehensive model of the carbon cycle is challenged by unicellular eukaryotes (protists) having evolved complex behavioral strategies and organismal interactions that extend far beyond photosynthetic lifestyles. As is also true for multicellular eukaryotes, these strategies and their associated physiological changes are difficult to deduce from genome sequences or gene repertoires—a problem compounded by numerous unknown function proteins. Here, we explore protistan trophic modes in marine food webs and broader biogeochemical influences. We also evaluate approaches that could resolve their activities, link them to biotic and abiotic factors, and integrate them into an ecosystems biology framework. Copyright © 2015, American Association for the Advancement of Science.

  15. Mariners Weather Log

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Mariners Weather Log (MWL) is a publication containing articles, news and information about marine weather events and phenomena, worldwide environmental impact...

  16. Supermarket Marine Biology.

    Science.gov (United States)

    Colby, Jennifer A.; And Others

    1995-01-01

    Describes a survey used to determine the availability of intact marine vertebrates and live invertebrates in supermarkets. Results shows that local supermarkets frequently provide a variety of intact marine organisms suitable for demonstrations, experiments, or dissections. (ZWH)

  17. Marine mammals: evolutionary biology

    National Research Council Canada - National Science Library

    Berta, Annalisa; Sumich, James L; Kovacs, Kit M

    2015-01-01

    The third edition of Marine Mammals: Evolutionary Biology provides a comprehensive and current assessment of the diversity, evolution, and biology of marine mammals, while highlighting the latest tools and techniques for their study...

  18. MarineCadastre.gov

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — MarineCadastre.gov is a marine information system that provides authoritative ocean data, offshore planning tools, and technical support to the offshore renewable...

  19. Mariner 10 Image Archive

    Data.gov (United States)

    National Aeronautics and Space Administration — The Mariner 10 Image Archive includes tools to view shaded relief maps of the surface of Mercury, a 3D globe, and all images acquired by NASA's Mariner 10 mission.

  20. Characterization of Cyanate Metabolism in Marine Synechococcus and Prochlorococcus spp. ▿

    OpenAIRE

    Nina A. Kamennaya; Post, Anton F

    2010-01-01

    Cyanobacteria of the genera Synechococcus and Prochlorococcus are the most abundant photosynthetic organisms on earth, occupying a key position at the base of marine food webs. The cynS gene that encodes cyanase was identified among bacterial, fungal, and plant sequences in public databases, and the gene was particularly prevalent among cyanobacteria, including numerous Prochlorococcus and Synechococcus strains. Phylogenetic analysis of cynS sequences retrieved from the Global Ocean Survey da...

  1. Could promontories have restricted sea-glacier penetration into marine embayments during Snow ball Earth events?

    OpenAIRE

    Campbell, Adam J.; Massarano, Betzalel; Waddington, Edwin D.; Warren, Stephen G.

    2016-01-01

    During the Neoproterozoic, Earth experienced several climate excursions of extreme cold, often referred to as the Snowball Earth events. During these periods, thick flowing ice, referred to as sea glaciers, covered the entire planet’s oceans. In addition, there is evidence that photosynthetic eukaryotic algae survived during these periods. With thick sea glaciers covering the oceans, it is uncertain where these organisms survived. One hypothesis is that these algae survived in marine embaymen...

  2. Characterization of cyanate metabolism in marine Synechococcus and Prochlorococcus spp.

    Science.gov (United States)

    Kamennaya, Nina A; Post, Anton F

    2011-01-01

    Cyanobacteria of the genera Synechococcus and Prochlorococcus are the most abundant photosynthetic organisms on earth, occupying a key position at the base of marine food webs. The cynS gene that encodes cyanase was identified among bacterial, fungal, and plant sequences in public databases, and the gene was particularly prevalent among cyanobacteria, including numerous Prochlorococcus and Synechococcus strains. Phylogenetic analysis of cynS sequences retrieved from the Global Ocean Survey database identified >60% as belonging to unicellular marine cyanobacteria, suggesting an important role for cyanase in their nitrogen metabolism. We demonstrate here that marine cyanobacteria have a functionally active cyanase, the transcriptional regulation of which varies among strains and reflects the genomic context of cynS. In Prochlorococcus sp. strain MED4, cynS was presumably transcribed as part of the cynABDS operon, implying cyanase involvement in cyanate utilization. In Synechococcus sp. strain WH8102, expression was not related to nitrogen stress responses and here cyanase presumably serves in the detoxification of cyanate resulting from intracellular urea and/or carbamoyl phosphate decomposition. Lastly, we report on a cyanase activity encoded by cynH, a novel gene found in marine cyanobacteria only. The presence of dual cyanase genes in the genomes of seven marine Synechococcus strains and their respective roles in nitrogen metabolism remain to be clarified.

  3. Direct extraction of photosynthetic electrons from single algal cells by nanoprobing system.

    Science.gov (United States)

    Ryu, WonHyoung; Bai, Seoung-Jai; Park, Joong Sun; Huang, Zubin; Moseley, Jeffrey; Fabian, Tibor; Fasching, Rainer J; Grossman, Arthur R; Prinz, Fritz B

    2010-04-14

    There are numerous sources of bioenergy that are generated by photosynthetic processes, for example, lipids, alcohols, hydrogen, and polysaccharides. However, generally only a small fraction of solar energy absorbed by photosynthetic organisms is converted to a form of energy that can be readily exploited. To more efficiently use the solar energy harvested by photosynthetic organisms, we evaluated the feasibility of generating bioelectricity by directly extracting electrons from the photosynthetic electron transport chain before they are used to fix CO(2) into sugars and polysaccharides. From a living algal cell, Chlamydomonas reinhardtii, photosynthetic electrons (1.2 pA at 6000 mA/m(2)) were directly extracted without a mediator electron carrier by inserting a nanoelectrode into the algal chloroplast and applying an overvoltage. This result may represent an initial step in generating "high efficiency" bioelectricity by directly harvesting high energy photosynthetic electrons.

  4. PS2013 Satellite Workshop on Photosynthetic Light-Harvesting Systems

    Energy Technology Data Exchange (ETDEWEB)

    Niederman, Robert A. [Rutgers Univ., New Brunswick, NJ (United States); Blankenship, Robert E. [Washington Univ., St. Louis, MO (United States); Frank, Harry A. [Univ. of Connecticut, Storrs, CT (United States)

    2015-02-07

    These funds were used for partial support of the PS2013 Satellite Workshop on Photosynthetic Light-Harvesting Systems, that was held on 8-11 August, 2013, at Washington University, St. Louis, MO. This conference, held in conjunction with the 16th International Congress on Photosynthesis/St. Louis, continued a long tradition of light-harvesting satellite conferences that have been held prior to the previous six international photosynthesis congresses. In this Workshop, the basis was explored for the current interest in replacing fossil fuels with energy sources derived form direct solar radiation, coupled with light-driven electron transport in natural photosynthetic systems and how they offer a valuable blueprint for conversion of sunlight to useful energy forms. This was accomplished through sessions on the initial light-harvesting events in the biological conversion of solar energy to chemically stored energy forms, and how these natural photosynthetic processes serve as a guide to the development of robust bio-hybrid and artificial systems for solar energy conversion into both electricity or chemical fuels. Organized similar to a Gordon Research Conference, a lively, informal and collegial setting was established, highlighting the exchange of exciting new data and unpublished results from ongoing studies. A significant amount of time was set aside for open discussion and interactive poster sessions, with a special session devoted to oral presentations by talented students and postdoctoral fellows judged to have the best posters. This area of research has seen exceptionally rapid progress in recent years, with the availability of a number of antenna protein structures at atomic resolution, elucidation of the molecular surface architecture of native photosynthetic membranes by atomic force microscopy and the maturing of ultrafast spectroscopic and molecular biological techniques for the investigation and manipulation of photosynthetic systems. The conferees

  5. Photoelectrochemical cells based on photosynthetic systems: a review

    Directory of Open Access Journals (Sweden)

    Roman A. Voloshin

    2015-06-01

    Full Text Available Photosynthesis is a process which converts light energy into energy contained in the chemical bonds of organic compounds by photosynthetic pigments such as chlorophyll (Chl a, b, c, d, f or bacteriochlorophyll. It occurs in phototrophic organisms, which include higher plants and many types of photosynthetic bacteria, including cyanobacteria. In the case of the oxygenic photosynthesis, water is a donor of both electrons and protons, and solar radiation serves as inexhaustible source of energy. Efficiency of energy conversion in the primary processes of photosynthesis is close to 100%. Therefore, for many years photosynthesis has attracted the attention of researchers and designers looking for alternative energy systems as one of the most efficient and eco-friendly pathways of energy conversion. The latest advances in the design of optimal solar cells include the creation of converters based on thylakoid membranes, photosystems, and whole cells of cyanobacteria immobilized on nanostructured electrode (gold nanoparticles, carbon nanotubes, nanoparticles of ZnO and TiO2. The mode of solar energy conversion in photosynthesis has a great potential as a source of renewable energy while it is sustainable and environmentally safety as well. Application of pigments such as Chl f and Chl d (unlike Chl a and Chl b, by absorbing the far red and near infrared region of the spectrum (in the range 700-750 nm, will allow to increase the efficiency of such light transforming systems. This review article presents the last achievements in the field of energy photoconverters based on photosynthetic systems.

  6. Alternating electron and proton transfer steps in photosynthetic water oxidation.

    Science.gov (United States)

    Klauss, André; Haumann, Michael; Dau, Holger

    2012-10-02

    Water oxidation by cyanobacteria, algae, and plants is pivotal in oxygenic photosynthesis, the process that powers life on Earth, and is the paradigm for engineering solar fuel-production systems. Each complete reaction cycle of photosynthetic water oxidation requires the removal of four electrons and four protons from the catalytic site, a manganese-calcium complex and its protein environment in photosystem II. In time-resolved photothermal beam deflection experiments, we monitored apparent volume changes of the photosystem II protein associated with charge creation by light-induced electron transfer (contraction) and charge-compensating proton relocation (expansion). Two previously invisible proton removal steps were detected, thereby filling two gaps in the basic reaction-cycle model of photosynthetic water oxidation. In the S(2) → S(3) transition of the classical S-state cycle, an intermediate is formed by deprotonation clearly before electron transfer to the oxidant (Y Z OX). The rate-determining elementary step (τ, approximately 30 µs at 20 °C) in the long-distance proton relocation toward the protein-water interface is characterized by a high activation energy (E(a) = 0.46 ± 0.05 eV) and strong H/D kinetic isotope effect (approximately 6). The characteristics of a proton transfer step during the S(0) → S(1) transition are similar (τ, approximately 100 µs; E(a) = 0.34 ± 0.08 eV; kinetic isotope effect, approximately 3); however, the proton removal from the Mn complex proceeds after electron transfer to . By discovery of the transient formation of two further intermediate states in the reaction cycle of photosynthetic water oxidation, a temporal sequence of strictly alternating removal of electrons and protons from the catalytic site is established.

  7. Biophysical consequences of photosynthetic temperature acclimation for climate

    Science.gov (United States)

    Smith, Nicholas G.; Lombardozzi, Danica; Tawfik, Ahmed; Bonan, Gordon; Dukes, Jeffrey S.

    2017-03-01

    Photosynthetic temperature acclimation is a commonly observed process that is increasingly being incorporated into Earth System Models (ESMs). While short-term acclimation has been shown to increase carbon storage in the future, it is uncertain whether acclimation will directly influence simulated future climate through biophysical mechanisms. Here, we used coupled atmosphere-biosphere simulations using the Community Earth System Model (CESM) to assess how acclimation-induced changes in photosynthesis influence global climate under present-day and future (RCP 8.5) conditions. We ran four 30 year simulations that differed only in sea surface temperatures and atmospheric CO2 (present or future) and whether a mechanism for photosynthetic temperature acclimation was included (yes or no). Acclimation increased future photosynthesis and, consequently, the proportion of energy returned to the atmosphere as latent heat, resulting in reduced surface air temperatures in areas and seasons where acclimation caused the biggest increase in photosynthesis. However, this was partially offset by temperature increases elsewhere, resulting in a small, but significant, global cooling of 0.05°C in the future, similar to that expected from acclimation-induced increases in future land carbon storage found in previous studies. In the present-day simulations, the photosynthetic response was not as strong and cooling in highly vegetated regions was less than warming elsewhere, leading to a net global increase in temperatures of 0.04°C. Precipitation responses were variable and rates did not change globally in either time period. These results, combined with carbon-cycle effects, suggest that models without acclimation may be overestimating positive feedbacks between climate and the land surface in the future.

  8. Wavelength-dependent induction of thymine dimers and growth rate reduction in the marine diatom Cyclotella sp. exposed to ultraviolet radiation

    NARCIS (Netherlands)

    Buma, A.G.J.; Engelen, A.H; Gieskes, W.W C

    1997-01-01

    Cultures of the marine diatom Cyclotella sp. were subjected to various polychromatic exposures of UVB radiation (280-320 nm), UVA radiation (320-400 nm) and photosynthetically active radiation, PAR (400-700 nm). Changes in growth rate and residual thymine dimer content (a measure for DNA damage)

  9. Dark hydrogen production in nitrogen atmosphere - An approach for sustainability by marine cyanobacterium Leptolyngbya valderiana BDU 20041

    Energy Technology Data Exchange (ETDEWEB)

    Prabaharan, D.; Arun Kumar, D.; Uma, L.; Subramanian, G. [National Facility for Marine Cyanobacteria (Sponsored by DBT, Govt. of India), Department of Marine Biotechnology, Bharathidasan University, Tiruchirapalli 620 024 (India)

    2010-10-15

    Biological hydrogen production is an ideal system for three main reasons i) forms a renewable energy source, ii) gives clean fuel and iii) serves as a good supplement to oil reserves. The major challenges faced in biological hydrogen production are the presence of uptake hydrogenase and lack of sustainability in the cyanobacterial hydrogen production system. Three different marine cyanobacterial species viz. Leptolyngbya valderiana BDU 20041, Dichothrix baueriana BDU 40481 and Nostoc calcicola BDU 40302 were studied for their potential use in hydrogen production. Among these, L. valderiana BDU 20041, was found to produce hydrogen even in 100% nitrogen atmosphere which was 85% of the hydrogen produced in argon atmosphere. This is the first report of such a high rate of production of hydrogen in a nitrogen atmosphere by a cyanobacterium, which makes it possible to develop sustained hydrogen production systems. L. valderiana BDU 20041, a dark hydrogen producer uses the reductant essentially supplied by the respiratory pathway for hydrogen production. Using inhibitors, this organism was found to produce hydrogen due to the activities of both nitrogenase and bidirectional hydrogenase, while it had no 'uptake' hydrogenase activity. The other two organisms though had low levels of bidirectional hydrogenase, possessed considerable 'uptake' hydrogenase activity and hence could not release much hydrogen either in argon or nitrogen atmosphere. (author)

  10. Advances in Metabolic Engineering of Cyanobacteria for Photosynthetic Biochemical Production

    Directory of Open Access Journals (Sweden)

    Martin C. Lai

    2015-10-01

    Full Text Available Engineering cyanobacteria into photosynthetic microbial cell factories for the production of biochemicals and biofuels is a promising approach toward sustainability. Cyanobacteria naturally grow on light and carbon dioxide, bypassing the need of fermentable plant biomass and arable land. By tapping into the central metabolism and rerouting carbon flux towards desirable compound production, cyanobacteria are engineered to directly convert CO2 into various chemicals. This review discusses the diversity of bioproducts synthesized by engineered cyanobacteria, the metabolic pathways used, and the current engineering strategies used for increasing their titers.

  11. Photosynthetic production of diterpenoids in chloroplasts and cyanobacteria

    DEFF Research Database (Denmark)

    Vavitsas, Konstantinos

    Terpenoids are one of the largest classes of chemical compounds, some of them with industrial interest as nutraceuticals, biofuels, or chemical feedstocks. Diterpenoids are a large terpenoid subclass, and their chemical structure consists of a core skeleton of 20 carbon atoms. This skeleton can...... and be assembled correctly by its native homologous recombination mechanisms. This theoretical and experimental work puts together the existing knowledge on terpenoid production and photosynthetic biotechnology, reveals the existing limitations and potential bottlenecks, and paves the way for future work towards...... the optimal use of photosynthesis to drive terpenoid production....

  12. Integrating Wind And Solar With Hydrogen Producing Fuel Cells

    NARCIS (Netherlands)

    Hemmes, K.

    2007-01-01

    The often proposed solution for the fluctuating wind energy supply is the conversion of the surplus of wind energy into hydrogen by means of electrolysis. In this paper a patented alternative is proposed consisting of the integration of wind turbines with internal reforming fuel-cells, capable of

  13. Bio-Prospecting for Improved Hydrogen-Producing Organisms

    Science.gov (United States)

    2011-06-01

    microbial composition , structure, and metabolic underpinnings in a couple of natural ecosystems, with Yellowstone National Park as the dominant site. The...splitting can be accomplished chemically in photochemical fuel cells, or in photovoltaics that use solar radiation indirectly for the electrolysis...and A. Mel is. 2000. Microalgae : a green source of renewable H2. Trends Biotechnol. 18:506-511. 37. (, km hit/. S., M. Labrenz, G. Jost, and K

  14. New Horizons for Hydrogen: Producing Hydrogen from Renewable Resources

    Energy Technology Data Exchange (ETDEWEB)

    2011-02-01

    Recent events have reminded us of the critical need to transition from crude oil, coal, and natural gas toward sustainable and domestic sources of energy. One reason is we need to strengthen our economy. In 2008 we saw the price of oil reach a record $93 per barrel. With higher oil prices, growing demand for gasoline, and increasing oil imports, an average of $235 billion per year, has left the United States economy to pay for foreign oil since 2005, or $1.2 trillion between 2005 and 2009. From a consumer perspective, this trend is seen with an average gasoline price of $2.50 per gallon since 2005, compared to an average of $1.60 between 1990 and 2004 (after adjusting for inflation). In addition to economic impacts, continued reliance on fossil fuels increases greenhouse gas emissions that may cause climate change, health impacts from air pollution, and the risk of disasters such as the Deepwater Horizon oil spill. Energy efficiency in the form of more efficient vehicles and buildings can help to reduce some of these impacts. However, over the long term we must shift from fossil resources to sustainable and renewable energy sources.

  15. CULTURE CONDITIONS AND THE DEVELOPMENT OF THE PHOTOSYNTHETIC MECHANISM : IV. INFLUENCE OF LIGHT INTENSITY ON PHOTOSYNTHETIC CHARACTERISTICS OF CHLORELLA.

    Science.gov (United States)

    Myers, J

    1946-07-20

    1. Chlorella pyrenoidosa has been grown in a continuous-culture apparatus under various light intensities provided by incandescent lamps, other conditions of culture being maintained constant. Light intensity curves for cells immersed in the No. 11 Warburg buffer and in Knop's solution + 4.4 per cent CO(2) at a saturating light intensity were determined as characteristics of the photosynthetic mechanism. These characteristics were referred to the centrifuged cell volume as an index of quantity of cellular material. 2. Cells grown at intensities in the range of about 35 f.-c. develop a capacity for a high rate of photosynthesis (c.mm. O(2)/hour/c.mm. cells). At culture intensities above or below this range the cells produced have a lower capacity for photosynthesis. A similar effect is observed for rate of photosynthesis per unit dry weight or rate per unit cell nitrogen. 3. The rate of photosynthesis per cell or rate per unit chlorophyll shows no maximum at any light intensity of culture but increases continuously throughout the range of light intensities studied. 4. Maximum rate of growth is attained at a light intensity of about 100 f.-c. The hypothesis is advanced that at culture intensities above that needed to give maximum rate of growth (100 f.-c.) a mechanism is developed which opposes the photosynthetic process and removes the photosynthetic products. 5. The low capacity for photosynthesis shown by cells grown at culture intensities below 35 f.-c. finds no immediate explanation. 6. The shape of the light intensity curve is markedly affected by the light intensity at which the cells have been cultured. Cells grown at lower intensities give light intensity curves approaching the Blackman type with a short transitional region between light limitation and light saturation.

  16. Sensing photosynthetic herbicides in an electrochemical flow cell.

    Science.gov (United States)

    Szabó, Tibor; Csekő, Richárd; Hajdu, Kata; Nagy, Krisztina; Sipos, Orsolya; Galajda, Péter; Garab, Győző; Nagy, László

    2017-05-01

    Specific inhibitory reactions of herbicides with photosynthetic reaction centers bound to working electrodes were monitored in a conventional electrochemical cell and a newly designed microfluidic electrochemical flow cell. In both cases, the bacterial reaction centers were bound to a transparent conductive metal oxide, indium-tin-oxide, electrode through carbon nanotubes. In the conventional cell, photocurrent densities of up to a few μA/cm2 could be measured routinely. The photocurrent could be blocked by the photosynthetic inhibitor terbutryn (I 50 = 0.38 ± 0.14 μM) and o-phenanthroline (I 50 = 63.9 ± 12.2 μM). The microfluidic flow cell device enabled us to reduce the sample volume and to simplify the electrode arrangement. The useful area of the electrodes remained the same (ca. 2 cm2), similar to the classical electrochemical cell; however, the size of the cell was reduced considerably. The microfluidic flow control enabled us monitoring in real time the binding/unbinding of the inhibitor and cofactor molecules at the secondary quinone site.

  17. Chlorophyll Fluorescence Imaging Uncovers Photosynthetic Fingerprint of Citrus Huanglongbing

    Directory of Open Access Journals (Sweden)

    Haiyan Cen

    2017-08-01

    Full Text Available Huanglongbing (HLB is one of the most destructive diseases of citrus, which has posed a serious threat to the global citrus production. This research was aimed to explore the use of chlorophyll fluorescence imaging combined with feature selection to characterize and detect the HLB disease. Chlorophyll fluorescence images of citrus leaf samples were measured by an in-house chlorophyll fluorescence imaging system. The commonly used chlorophyll fluorescence parameters provided the first screening of HLB disease. To further explore the photosynthetic fingerprint of HLB infected leaves, three feature selection methods combined with the supervised classifiers were employed to identify the unique fluorescence signature of HLB and perform the three-class classification (i.e., healthy, HLB infected, and nutrient deficient leaves. Unlike the commonly used fluorescence parameters, this novel data-driven approach by using the combination of the mean fluorescence parameters and image features gave the best classification performance with the accuracy of 97%, and presented a better interpretation for the spatial heterogeneity of photochemical and non-photochemical components in HLB infected citrus leaves. These results imply the potential of the proposed approach for the citrus HLB disease diagnosis, and also provide a valuable insight for the photosynthetic response to the HLB disease.

  18. Role of interference in the photosynthetic heat engine.

    Science.gov (United States)

    Xu, Y Y; Liu, J

    2014-11-01

    The observation of quantum coherence in pigment-protein complexes has attracted considerable interest. One such endeavor entails applying a quantum heat engine to model the photosynthetic reaction center, but the definition of work used is inconsistent with that defined in quantum thermodynamics. Using the definition of work proposed in Weimer et al. [Europhys. Lett. 83, 30008 (2008)EULEEJ0295-507510.1209/0295-5075/83/30008], we investigated two proposals for enhancing the performance of the photosynthetic reaction center. In proposal A, which is similar to that in Dorfman et al. [Proc. Natl. Acad. Sci. USA 110, 2746 (2013)PNASA60027-842410.1073/pnas.1212666110], we found that the power and current-voltage characteristic of the heat engine can be increased by Fano interference but the efficiency cannot. In proposal B, which is similar to that in Creatore et al. [Phys. Rev. Lett. 111, 253601 (2013)PRLTAO0031-900710.1103/PhysRevLett.111.253601], we found that the mechanism of strengthening the performance of the heat engine is invalid; i.e., the dipole-dipole interaction between two electron donors could not increase the power, efficiency, or current-voltage characteristic.

  19. Intracellular spectral recompositioning of light enhances algal photosynthetic efficiency.

    Science.gov (United States)

    Fu, Weiqi; Chaiboonchoe, Amphun; Khraiwesh, Basel; Sultana, Mehar; Jaiswal, Ashish; Jijakli, Kenan; Nelson, David R; Al-Hrout, Ala'a; Baig, Badriya; Amin, Amr; Salehi-Ashtiani, Kourosh

    2017-09-01

    Diatoms, considered as one of the most diverse and largest groups of algae, can provide the means to reach a sustainable production of petrochemical substitutes and bioactive compounds. However, a prerequisite to achieving this goal is to increase the solar-to-biomass conversion efficiency of photosynthesis, which generally remains less than 5% for most photosynthetic organisms. We have developed and implemented a rapid and effective approach, herein referred to as intracellular spectral recompositioning (ISR) of light, which, through absorption of excess blue light and its intracellular emission in the green spectral band, can improve light utilization. We demonstrate that ISR can be used chemogenically, by using lipophilic fluorophores, or biogenically, through the expression of an enhanced green fluorescent protein (eGFP) in the model diatom Phaeodactylum tricornutum. Engineered P. tricornutum cells expressing eGFP achieved 28% higher efficiency in photosynthesis than the parental strain, along with an increased effective quantum yield and reduced nonphotochemical quenching (NPQ) induction levels under high-light conditions. Further, pond simulator experiments demonstrated that eGFP transformants could outperform their wild-type parental strain by 50% in biomass production rate under simulated outdoor sunlight conditions. Transcriptome analysis identified up-regulation of major photosynthesis genes in the engineered strain in comparison with the wild type, along with down-regulation of NPQ genes involved in light stress response. Our findings provide a proof of concept for a strategy of developing more efficient photosynthetic cell factories to produce algae-based biofuels and bioactive products.

  20. Photosynthetic performance of phototrophic biofilms in extreme acidic environments.

    Science.gov (United States)

    Souza-Egipsy, Virginia; Altamirano, María; Amils, Ricardo; Aguilera, Angeles

    2011-08-01

    Photosynthesis versus irradiance curves and their associated photosynthetic parameters from different phototrophic biofilms isolated from an extreme acidic environment (Río Tinto, SW, Spain) were studied in order to relate them to their species composition and the physicochemical characteristics of their respective sampling locations. The results indicated that the biofilms are low light acclimated showing a photoinhibition model; only floating communities of filamentous algae showed a light saturation model. Thus, all the biofilms analysed showed photoinhibition over 60 µmol photon m(-2) s(-1) except in the case of Zygnemopsis sp. sample, which showed a light-saturated photosynthesis model under irradiations higher that 200 µmol photon m(-2) s(-1). The highest values of compensation light intensity (I(c)) were showed also by Zygnemosis sp. biofilm (c. 40 µmol photon m(-2) s(-1)), followed by Euglena mutabilis and Chlorella sp. samples (c. 20 µmol photon m(-2) s(-1)). The diatom sample showed the lowest I(c) values (c. 5 µmol photon m(-2) s(-1)). As far as we know this is the first attempt to determine the photosynthetic activity of low pH and heavy metal tolerant phototrophic biofilms, which may give light in the understanding of the ecological importance of these biofilms for the maintenance of the primary production of these extreme and unique ecosystems. © 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.

  1. Synergistic Two-Photon Absorption Enhancement in Photosynthetic Light Harvesting

    Science.gov (United States)

    Chen, Kuo-Mei; Chen, Yu-Wei; Gao, Ting-Fong

    2012-06-01

    The grand scale fixation of solar energies into chemical substances by photosynthetic reactions of light-harvesting organisms provides Earth's other life forms a thriving environment. Scientific explorations in the past decades have unraveled the fundamental photophysical and photochemical processes in photosynthesis. Higher plants, green algae, and light-harvesting bacteria utilize organized pigment-protein complexes to harvest solar power efficiently and the resultant electronic excitations are funneled into a reaction center, where the first charge separation process takes place. Here we show experimental evidences that green algae (Chlorella vulgaris) in vivo display a synergistic two-photon absorption enhancement in their photosynthetic light harvesting. Their absorption coefficients at various wavelengths display dramatic dependence on the photon flux. This newly found phenomenon is attributed to a coherence-electronic-energy-transfer-mediated (CEETRAM) photon absorption process of light-harvesting pigment-protein complexes of green algae. Under the ambient light level, algae and higher plants can utilize this quantum mechanical mechanism to create two entangled electronic excitations adjacently in their light-harvesting networks. Concerted multiple electron transfer reactions in the reaction centers and oxygen evolving complexes can be implemented efficiently by the coherent motion of two entangled excitons from antennae to the charge separation reaction sites. To fabricate nanostructured, synthetic light-harvesting apparatus, the paramount role of the CEETRAM photon absorption mechanism should be seriously considered in the strategic guidelines.

  2. SANS Investigation of the Photosynthetic Machinery of Chloroflexus Aurantiacus

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Kuo-Hsiang [ORNL; Urban, Volker S [ORNL; Jianzhong, Wen [Washington University, St. Louis; Yueyong, Xin [Washington University, St. Louis; Blankenship, Robert E [ORNL

    2010-01-01

    Green photosynthetic bacteria harvest light and perform photosynthesis in low light environments, and contain specialized antenna complexes to adapt to this condition. In this report, we present studies using small-angle neutron scattering (SANS) to elucidate structural information about the photosynthetic apparatus, including the peripheral light harvesting chlorosome complex, the integral membrane light-harvesting B808-866 complex and the reaction center (RC) in the thermophilic green phototrophic bacterium Chloroflexus aurantiacus. Using contract variation in SANS measurments, our studies suggest that the B808-866 comples is wrapped around the RC in Cfx. aurantiacus, and the overall size and conformation for the B808-866 complex of Cfx. aurantiacus is roughly comparable to the LH1 antenna complex of the purple bacteria. A similar size for the isolated B808-866 complex is also suggested via dynamic light scattering measurements. Alos, a smaller size of the RC of Cfx. aurantiacus that the RC of the purple bacteria is observed. Further, our SANS measurements indicate that the chlorosome is a lipid body with rod-like shape, and that the self-assembly of bacteriochlorophylls, the major component of the chlorosome, is lipid-like. Finally, two populations of chlorosome particles are suggested in our SANS measurements.

  3. SANS investigation of the photosynthetic machinery of Chloroflexus aurantiacus

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Kuo-Hsiang; Urban, Volker S; Wen, Jianzhong; Xin, Yueyong; Blankenship, R. E.

    Green photosynthetic bacteria harvest light and perform photosynthesis in low-light environments, and contain specialized antenna complexes to adapt to this condition. We performed small-angle neutron scattering (SANS) studies to obtain structural information about the photosynthetic apparatus, including the peripheral light-harvesting chlorosome complex, the integral membrane light-harvesting B808-866 complex, and the reaction center (RC) in the thermophilic green phototrophic bacterium Chloroflexus aurantiacus. Using contrast variation in SANS measurements, we found that the B808-866 complex is wrapped around the RC in Cfx. aurantiacus, and the overall size and conformation of the B808-866 complex of Cfx. aurantiacus is roughly comparable to the LH1 antenna complex of the purple bacteria. A similar size of the isolated B808-866 complex was suggested by dynamic light scattering measurements, and a smaller size of the RC of Cfx. aurantiacus compared to the RC of the purple bacteria was observed. Further, our SANS measurements indicate that the chlorosome is a lipid body with a rod-like shape, and that the self-assembly of bacteriochlorophylls, the major component of the chlorosome, is lipid-like. Finally, two populations of chlorosome particles are suggested in our SANS measurements.

  4. The genetic basis of anoxygenic photosynthetic arsenite oxidation

    Science.gov (United States)

    Hernandez-Maldonado, Jamie; Sanchez-Sedillo, Benjamin; Stoneburner, Brendon; Boren, Alison; Miller, Laurence G.; McCann, Shelley; Rosen, Michael R.; Oremland, Ronald S.; Saltikov, Chad W.

    2017-01-01

    “Photoarsenotrophy”, the use of arsenite as an electron donor for anoxygenic photosynthesis, is thought to be an ancient form of phototrophy along with the photosynthetic oxidation of Fe(II), H2S, H2, and NO2-. Photoarsenotrophy was recently identified from Paoha Island's (Mono Lake, CA) arsenic-rich hot springs. The genomes of several photoarsenotrophs revealed a gene cluster, arxB2AB1CD, where arxA is predicted to encode for the sole arsenite oxidase. The role of arxA in photosynthetic arsenite oxidation was confirmed by disrupting the gene in a representative photoarsenotrophic bacterium, resulting in the loss of light-dependent arsenite oxidation. In situ evidence of active photoarsenotrophic microbes was supported by arxA mRNA detection for the first time, in red-pigmented microbial mats within the hot springs of Paoha Island. This work expands on the genetics for photosynthesis coupled to new electron donors and elaborates on known mechanisms for arsenic metabolism, thereby highlighting the complexities of arsenic biogeochemical cycling.

  5. Towards quantification of vibronic coupling in photosynthetic antenna complexes

    Energy Technology Data Exchange (ETDEWEB)

    Singh, V. P.; Westberg, M.; Wang, C.; Gellen, T.; Engel, G. S., E-mail: gsengel@uchicago.edu [Department of Chemistry, The James Franck Institute and The Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637 (United States); Dahlberg, P. D. [Graduate Program in the Biophysical Sciences, The James Franck Institute and The Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637 (United States); Gardiner, A. T.; Cogdell, R. J. [Department of Botany, Institute of Molecular Cell and Systems Biology, University of Glasgow, Glasgow, Scotland (United Kingdom)

    2015-06-07

    Photosynthetic antenna complexes harvest sunlight and efficiently transport energy to the reaction center where charge separation powers biochemical energy storage. The discovery of existence of long lived quantum coherence during energy transfer has sparked the discussion on the role of quantum coherence on the energy transfer efficiency. Early works assigned observed coherences to electronic states, and theoretical studies showed that electronic coherences could affect energy transfer efficiency—by either enhancing or suppressing transfer. However, the nature of coherences has been fiercely debated as coherences only report the energy gap between the states that generate coherence signals. Recent works have suggested that either the coherences observed in photosynthetic antenna complexes arise from vibrational wave packets on the ground state or, alternatively, coherences arise from mixed electronic and vibrational states. Understanding origin of coherences is important for designing molecules for efficient light harvesting. Here, we give a direct experimental observation from a mutant of LH2, which does not have B800 chromophores, to distinguish between electronic, vibrational, and vibronic coherence. We also present a minimal theoretical model to characterize the coherences both in the two limiting cases of purely vibrational and purely electronic coherence as well as in the intermediate, vibronic regime.

  6. Toward a photosynthetic microbial platform for terpenoid engineering.

    Science.gov (United States)

    Davies, Fiona K; Jinkerson, Robert E; Posewitz, Matthew C

    2015-03-01

    Plant terpenoids are among the most diverse group of naturally-occurring organic compounds known, and several are used in contemporary consumer products. Terpene synthase enzymes catalyze complex rearrangements of carbon skeleton precursors to yield thousands of unique chemical structures that range in size from the simplest five carbon isoprene unit to the long polymers of rubber. Such chemical diversity has established plant terpenoids as valuable commodity chemicals with applications in the pharmaceutical, neutraceutical, cosmetic, and food industries. More recently, terpenoids have received attention as a renewable alternative to petroleum-derived fuels and as the building blocks of synthetic biopolymers. However, the current plant- and petrochemical-based supplies of commodity terpenoids have major limitations. Photosynthetic microorganisms provide an opportunity to generate terpenoids in a renewable manner, employing a single consolidated host organism that is able to use solar energy, H2O and CO2 as the primary inputs for terpenoid biosynthesis. Advances in synthetic biology have seen important breakthroughs in microbial terpenoid engineering, traditionally via fermentative pathways in yeast and Escherichia coli. This review draws on the knowledge obtained from heterotrophic microbial engineering to propose strategies for the development of microbial photosynthetic platforms for industrial terpenoid production. The importance of utilizing the wealth of genetic information provided by nature to unravel the regulatory mechanisms of terpenoid biosynthesis is highlighted.

  7. Changes of Photosynthetic Behaviors in Kappaphycus alvarezii Infected by Epiphyte

    Directory of Open Access Journals (Sweden)

    Tong Pang

    2011-01-01

    Full Text Available Epiphytic filamentous algae (EFA were noted as a serious problem to reduce the production and quality of K. alvarezii. The morphological studies revealed that the main epiphyte on K. alvarezii was Neosiphonia savatieri in China. Though the harmful effects of EFA on the production of K. alvarezii have been reported, the detailed mechanism of the N. savatieri in limiting the production of K. alvarezii has not been studied yet. The present paper studied the effects of N. savatieri infection on photosynthetic behaviors in K. alvarezii by detecting chlorophyll fluorescence transient in vivo. The results revealed that damage of oxygen-evolving complex (OEC, decrease of active reaction centers (RCs, and the plastoquinone (PQ pool as well as significant reduction in the performance indexes (PI of PSII were caused by the infection of N. savatieri. The influence of N. savatieri on photosynthetic activity of K. alvarezii should be one of the important reasons to reduce the production of K. alvarezii infected by N. savatieri.

  8. Towards quantification of vibronic coupling in photosynthetic antenna complexes.

    Science.gov (United States)

    Singh, V P; Westberg, M; Wang, C; Dahlberg, P D; Gellen, T; Gardiner, A T; Cogdell, R J; Engel, G S

    2015-06-07

    Photosynthetic antenna complexes harvest sunlight and efficiently transport energy to the reaction center where charge separation powers biochemical energy storage. The discovery of existence of long lived quantum coherence during energy transfer has sparked the discussion on the role of quantum coherence on the energy transfer efficiency. Early works assigned observed coherences to electronic states, and theoretical studies showed that electronic coherences could affect energy transfer efficiency--by either enhancing or suppressing transfer. However, the nature of coherences has been fiercely debated as coherences only report the energy gap between the states that generate coherence signals. Recent works have suggested that either the coherences observed in photosynthetic antenna complexes arise from vibrational wave packets on the ground state or, alternatively, coherences arise from mixed electronic and vibrational states. Understanding origin of coherences is important for designing molecules for efficient light harvesting. Here, we give a direct experimental observation from a mutant of LH2, which does not have B800 chromophores, to distinguish between electronic, vibrational, and vibronic coherence. We also present a minimal theoretical model to characterize the coherences both in the two limiting cases of purely vibrational and purely electronic coherence as well as in the intermediate, vibronic regime.

  9. Photosynthetic control of electron transport and the regulation of gene expression

    NARCIS (Netherlands)

    Foyer, C.H.; Neukermans, J.; Queval, G.; Noctor, G.; Harbinson, J.

    2012-01-01

    The term ‘photosynthetic control’ describes the short- and long-term mechanisms that regulate reactions in the photosynthetic electron transport (PET) chain so that the rate of production of ATP and NADPH is coordinated with the rate of their utilization in metabolism. At low irradiances these

  10. Chlorophylls d and f and Their Role in Primary Photosynthetic Processes of Cyanobacteria.

    Science.gov (United States)

    Allakhverdiev, S I; Kreslavski, V D; Zharmukhamedov, S K; Voloshin, R A; Korol'kova, D V; Tomo, T; Shen, J-R

    2016-03-01

    The finding of unique Chl d- and Chl f-containing cyanobacteria in the last decade was a discovery in the area of biology of oxygenic photosynthetic organisms. Chl b, Chl c, and Chl f are considered to be accessory pigments found in antennae systems of photosynthetic organisms. They absorb energy and transfer it to the photosynthetic reaction center (RC), but do not participate in electron transport by the photosynthetic electron transport chain. However, Chl d as well as Chl a can operate not only in the light-harvesting complex, but also in the photosynthetic RC. The long-wavelength (Qy) Chl d and Chl f absorption band is shifted to longer wavelength (to 750 nm) compared to Chl a, which suggests the possibility for oxygenic photosynthesis in this spectral range. Such expansion of the photosynthetically active light range is important for the survival of cyanobacteria when the intensity of light not exceeding 700 nm is attenuated due to absorption by Chl a and other pigments. At the same time, energy storage efficiency in photosystem 2 for cyanobacteria containing Chl d and Chl f is not lower than that of cyanobacteria containing Chl a. Despite great interest in these unique chlorophylls, many questions related to functioning of such pigments in primary photosynthetic processes are still not elucidated. This review describes the latest advances in the field of Chl d and Chl f research and their role in primary photosynthetic processes of cyanobacteria.

  11. Marine infectious disease ecology

    Science.gov (United States)

    Lafferty, Kevin D.

    2017-01-01

    To put marine disease impacts in context requires a broad perspective on the roles infectious agents have in the ocean. Parasites infect most marine vertebrate and invertebrate species, and parasites and predators can have comparable biomass density, suggesting they play comparable parts as consumers in marine food webs. Although some parasites might increase with disturbance, most probably decline as food webs unravel. There are several ways to adapt epidemiological theory to the marine environment. In particular, because the ocean represents a three-dimensional moving habitat for hosts and parasites, models should open up the spatial scales at which infective stages and host larvae travel. In addition to open recruitment and dimensionality, marine parasites are subject to fishing, filter feeders, dosedependent infection, environmental forcing, and death-based transmission. Adding such considerations to marine disease models will make it easier to predict which infectious diseases will increase or decrease in a changing ocean.

  12. Marine Environmental History

    DEFF Research Database (Denmark)

    Poulsen, Bo

    2012-01-01

    This essay provides an overview of recent trends in the historiography of marine environmental history, a sub-field of environmental history which has grown tremendously in scope and size over the last c. 15 years. The object of marine environmental history is the changing relationship between...... human society and natural marine resources. Within this broad topic, several trends and objectives are discernable. The essay argue that the so-called material marine environmental history has its main focus on trying to reconstruct the presence, development and environmental impact of past fisheries...... and whaling operations. This ambition often entails a reconstruction also of how marine life has changed over time. The time frame rages from Paleolithicum to the present era. The field of marine environmental history also includes a more culturally oriented environmental history, which mainly has come...

  13. 75 FR 68605 - Marine Mammals

    Science.gov (United States)

    2010-11-08

    ... National Oceanic and Atmospheric Administration RIN 0648-XX23 Marine Mammals AGENCY: National Marine... Marine Science Center, Newport, OR has been issued a permit to conduct research on marine mammals... authority of the Marine Mammal Protection Act of 1972, as amended (16 U.S.C. 1361 et seq.), the regulations...

  14. CO2-induced photosynthetic and stoichiometric responses to phosphorus limitation

    Science.gov (United States)

    de Boer, Hugo; di Lallo, Giacomo; van Dijk, Jerry

    2017-04-01

    Carbon fertilisation from rising atmospheric CO2 concentrations increases the productivity of plants globally. Meanwhile, the global cycles of Nitrogen (N) and Phosphorus (P) are also altered due to anthropogenic emissions. In general, the additional supply of N is expected to exceed that of P, leading to an increase in P limitation in natural ecosystems. Although the direct carbon fertilisation effect and the interaction with available N is relatively well understood, it remains uncertain how carbon fertilisation is confounded by the availability of P. It is hypothesised that (i) the photosynthetic P-use efficiency increases at elevated CO2 owing to a direct increase in photosynthesis and (ii) the photosynthetic maximum carboxylation rate (Vcmax) and electron transport rate (Jmax) are down-regulated in response to a combination of elevated CO2 and P-limitation via a coordinated reduction of leaf N and P content per unit leaf area. In this study we examined the hypothesised effects of P limitation and CO2 fertilisation on the photosynthetic and stoichiometric responses of three plant species: Holcus lanatus (C3 grass), Panicum miliaceum (C4 grass) and Solanum dulcamara (C3 herb). Individuals of these species were grown at sub-ambient (150 ppm), modern (450 ppm) and elevated CO2 concentrations (800 ppm) and exposed to an N:P treatment consisting of either severe nitrogen limitation at an N:P ratio of 1:1, or severe P limitation at an N:P ratio of 45:1, with a similar supply rate of N. Our results show significant effects of growth CO2 and P supply on Vcmax and Jmax, as well as the whole-plant biomass at the point of harvest. Interaction effects between growth CO2 and P supply were observed for the light-saturated photosynthesis rate, stomatal conductance, leaf P content, and the N:P ratio of the leaf. No significant change in the leaf N content was observed across treatments. These results suggest that limited availability of P constrains the biochemical potential

  15. Marine electrical practice

    CERN Document Server

    Watson, G O

    1991-01-01

    Marine Engineering Series: Marine Electrical Practice, Sixth Edition focuses on changes in the marine industry, including the application of programmable electronic systems, generators, and motors. The publication first ponders on insulation and temperature ratings of equipment, protection and discrimination, and AC generators. Discussions focus on construction, shaft-drive generators, effect of unbalanced loading, subtransient and transient reactance, protection discrimination, fault current, measurement of ambient air temperature, and basis of machine ratings. The text then examines AC switc

  16. Marine Ecological Regions 2000

    Data.gov (United States)

    California Department of Resources — This shapefile was screen digitized from 'Calecoregions1.jpg' a georectified digital image of the original map of California's ecoregions, including the marine...

  17. Biosurfactants from marine microorganisms

    Directory of Open Access Journals (Sweden)

    Suppasil Maneerat

    2005-11-01

    Full Text Available Biosurfactants are the surface-active molecules synthesized by microorganisms. With the advantage of environmental compatibility, the demand for biosurfactants has been steadily increasing and may eventually replace their chemically synthesized counterparts. Marine biosurfactants produced by some marine microorganisms have been paid more attention, particularly for the bioremediation of the sea polluted by crude oil. This review describes screening of biosurfactant-producing microorganisms, the determination of biosurfactant activity as well as the recovery of marine surfactant. The uses of marine biosurfactants for bioremediation are also discussed.

  18. Parasites and marine invasions

    Science.gov (United States)

    Torchin, M.E.; Lafferty, K.D.; Kuris, A.M.

    2002-01-01

    Introduced marine species are a major environmental and economic problem. The rate of these biological invasions has substantially increased in recent years due to the globalization of the world's economies. The damage caused by invasive species is often a result of the higher densities and larger sizes they attain compared to where they are native. A prominent hypothesis explaining the success of introduced species is that they are relatively free of the effects of natural enemies. Most notably, they may encounter fewer parasites in their introduced range compared to their native range. Parasites are ubiquitous and pervasive in marine systems, yet their role in marine invasions is relatively unexplored. Although data on parasites of marine organisms exist, the extent to which parasites can mediate marine invasions, or the extent to which invasive parasites and pathogens are responsible for infecting or potentially decimating native marine species have not been examined. In this review, we present a theoretical framework to model invasion success and examine the evidence for a relationship between parasite presence and the success of introduced marine species. For this, we compare the prevalence and species richness of parasites in several introduced populations of marine species with populations where they are native. We also discuss the potential impacts of introduced marine parasites on native ecosystems.

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

    Directory of Open Access Journals (Sweden)

    Fong-Lee Ng

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

  20. A cost-effective microbial fuel cell to detect and select for photosynthetic electrogenic activity in algae and cyanobacteria

    NARCIS (Netherlands)

    Luimstra, V.M.; Kennedy, S.J.; Güttler, J.; Wood, S.A.; Williams, D.E.; Packer, M.A.

    2014-01-01

    This work describes the development of an easily constructed, cost-effective photosynthetic microbial fuel cell design with highly reproducible electrochemical characteristics that can be used to screen algae and cyanobacteria for photosynthetic electrogenic activity. It is especially suitable for

  1. Sulfite Reductase Activity in Extracts of Various Photosynthetic Bacteria

    Science.gov (United States)

    Peck, H. D.; Tedro, S.; Kamen, M. D.

    1974-01-01

    Extracts of representative bacterial strains from the various families of photosynthetic prokaryotes are demonstrated to possess significant levels of sulfite reductase [EC 1.8.99.1; hydrogen-sulfide: (acceptor)oxidoreductase] activity with reduced methyl viologen as electron donor, but not NADPH2. The enzyme is localized primarily in the soluble fraction of the extracts, in contrast to adenylysulfate reductase [EC 1.8.99.2; AMP, sulfite: (acceptor) oxidoreductase], which is bound normally in the membrane fractions of those bacteria in which it is found. Assignment of the sulfite reductase activities to the biosynthetic (“assimilatory”) pathway is suggested by levels of specific activity noted and ready solubility. PMID:4526215

  2. C4 photosynthetic machinery: insights from maize chloroplast proteomics

    Directory of Open Access Journals (Sweden)

    Qi eZhao

    2013-04-01

    Full Text Available C4 plants exhibit much higher CO2 assimilation rates than C3 plants. The specialized differentiation of mesophyll cell (M and bundle sheath cell (BS type chloroplasts is unique to C4 plants and improves photosynthesis efficiency. Maize (Zea mays is an important crop and model with C4 photosynthetic machinery. Current high-throughput quantitative proteomics approaches (e.g., 2DE, iTRAQ, and shotgun proteomics have been employed to investigate maize chloroplast structure and function. These proteomic studies have provided valuable information on C4 chloroplast protein components, photosynthesis, and other metabolic mechanisms underlying chloroplast biogenesis, stromal and membrane differentiation, as well as response to salinity, high/low temperature, and light stress. This review presents an overview of proteomics advances in maize chloroplast biology.

  3. Proton-Coupled Electron Transfer in Artificial Photosynthetic Systems.

    Science.gov (United States)

    Mora, S Jimena; Odella, Emmanuel; Moore, Gary F; Gust, Devens; Moore, Thomas A; Moore, Ana L

    2018-01-08

    Artificial photosynthetic constructs can in principle operate more efficiently than natural photosynthesis because they can be rationally designed to optimize solar energy conversion for meeting human demands rather than the multiple needs of an organism competing for growth and reproduction in a complex ecosystem. The artificial photosynthetic constructs described in this Account consist primarily of covalently linked synthetic chromophores, electron donors and acceptors, and proton donors and acceptors that carry out the light absorption, electron transfer, and proton-coupled electron transfer (PCET) processes characteristic of photosynthetic cells. PCET is the movement of an electron from one site to another accompanied by proton transfer. PCET and the transport of protons over tens of angstroms are important in all living cells because they are a fundamental link between redox processes and the establishment of transmembrane gradients of proton electrochemical potential, known as proton-motive force (PMF), which is the unifying concept in bioenergetics. We have chosen a benzimidazole phenol (BIP) system as a platform for the study of PCET because with appropriate substitutions it is possible to design assemblies in which one or multiple proton transfers can accompany oxidation of the phenol. In BIP, oxidation of the phenol increases its acidity by more than ten pKa units; thus, electrochemical oxidation of the phenol is associated with a proton transfer to the imidazole. This is an example of a PCET process involving transfer of one electron and one proton, known as electron-proton transfer (EPT). When the benzimidazole moiety of BIP is substituted at the 4-position with good proton acceptor groups such as aliphatic amines, experimental and theoretical results indicate that two proton transfers occur upon one-electron oxidation of the phenol. This phenomenon is described as a one-electron-two-proton transfer (E2PT) process and results in translocation of

  4. Photosynthetic Pigments in Hypogymnia Physodes with Different Metal Contents

    Science.gov (United States)

    Meysurova, A. F.; Notov, A. A.; Pungin, A. V.

    2018-01-01

    Chlorophyll a and b contents in Hypogymnia physodes specimens collected from various economic areas and natural complexes of Tver Region were found to differ substantially using a spectrophotometric method, showing that the lichen photosynthetic system is highly adaptable. The chlorophyll b content was linked primarily to adaptation to specific environmental features in various plant communities. The chlorophyll a content changed to provide the necessary compensatory responses under technogenic stress. A total of 15 metals (Al, As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Sb, Ti, V, and Zn) were detected in H. physodes samples using inductively coupled plasma atomicemission spectroscopy (ICP AES). The most widespread of them were Fe, Al, and Ti. Significant correlations among the concentrations of these metals and the chlorophyll a content were revealed.

  5. Single Molecule Spectroscopy on Photosynthetic Pigment-Protein Complexes

    CERN Document Server

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

    2001-01-01

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

  6. Quantum Coherent Dynamics at Ambient Temperature in Photosynthetic Molecules

    CERN Document Server

    Walters, Zachary B

    2011-01-01

    Photosynthetic antenna complexes are responsible for absorbing energy from sunlight and transmitting it to remote locations where it can be stored. Recent experiments have found that this process involves long-lived quantum coherence between pigment molecules, called chromophores, which make up these complexes. Expected to decay within 100 fs at room temperature, these coherences were instead found to persist for picosecond time scales, despite having no apparent isolation from the thermal environment of the cell. This paper derives a quantum master equation which describes the coherent evolution of a system in strong contact with a thermal environment. Conditions necessary for long coherence lifetimes are identified, and the role of coherence in efficient energy transport is illuminated. Static spectra and exciton transfer rates for the PE545 complex of the cryptophyte algae CS24 are calculated and shown to have good agreement with experiment.

  7. Photosynthetic biomineralization of radioactive Sr via microalgal CO2 absorption.

    Science.gov (United States)

    Lee, Seung Yeop; Jung, Kwang-Hwan; Lee, Ju Eun; Lee, Keon Ah; Lee, Sang-Hyo; Lee, Ji Young; Lee, Jae Kwang; Jeong, Jong Tae; Lee, Seung-Yop

    2014-11-01

    Water-soluble radiostrontium ((90)Sr) was efficiently removed as a carbonate form through microalgal photosynthetic process. The immobilization of soluble (90)Sr radionuclide and production of highly-precipitable radio-strontianite ((90)SrCO3) biomineral are achieved by using Chlorella vulgaris, and the biologically induced mineralization drastically decreased the (90)Sr radioactivity in water to make the highest (90)Sr removal ever reported. The high-resolution microscopy revealed that the short-term removal of soluble (90)Sr by C. vulgaris was attributable to the rapid and selective carbonation of (90)Sr together with the consumption of dissolved CO2 during photosynthesis. A small amount of carbonate in water could act as Sr(2+) sinks through the particular ability of the microalga to make the carbonate mineral of Sr stabilized firmly at the surface site. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Legumes symbioses: absence of Nod genes in photosynthetic bradyrhizobia.

    Science.gov (United States)

    Giraud, Eric; Moulin, Lionel; Vallenet, David; Barbe, Valérie; Cytryn, Eddie; Avarre, Jean-Christophe; Jaubert, Marianne; Simon, Damien; Cartieaux, Fabienne; Prin, Yves; Bena, Gilles; Hannibal, Laure; Fardoux, Joel; Kojadinovic, Mila; Vuillet, Laurie; Lajus, Aurélie; Cruveiller, Stéphane; Rouy, Zoe; Mangenot, Sophie; Segurens, Béatrice; Dossat, Carole; Franck, William L; Chang, Woo-Suk; Saunders, Elizabeth; Bruce, David; Richardson, Paul; Normand, Philippe; Dreyfus, Bernard; Pignol, David; Stacey, Gary; Emerich, David; Verméglio, André; Médigue, Claudine; Sadowsky, Michael

    2007-06-01

    Leguminous plants (such as peas and soybeans) and rhizobial soil bacteria are symbiotic partners that communicate through molecular signaling pathways, resulting in the formation of nodules on legume roots and occasionally stems that house nitrogen-fixing bacteria. Nodule formation has been assumed to be exclusively initiated by the binding of bacterial, host-specific lipochito-oligosaccharidic Nod factors, encoded by the nodABC genes, to kinase-like receptors of the plant. Here we show by complete genome sequencing of two symbiotic, photosynthetic, Bradyrhizobium strains, BTAi1 and ORS278, that canonical nodABC genes and typical lipochito-oligosaccharidic Nod factors are not required for symbiosis in some legumes. Mutational analyses indicated that these unique rhizobia use an alternative pathway to initiate symbioses, where a purine derivative may play a key role in triggering nodule formation.

  9. Intercepted photosynthetically active radiation estimated by spectral reflectance

    Science.gov (United States)

    Hatfield, J. L.; Asrar, G.; Kanemasu, E. T.

    1984-01-01

    Interception of photosynthetically active radiation (PAR) was evaluated relative to greenness and normalized difference (MSS (7-5)/(7+5) for five planting dates of wheat for 1978-79 and 1979-80 at Phoenix, Arizona. Intercepted PAR was calculated from leaf area index and stage of growth. Linear relatinships were found with greeness and normalized difference with separate relatinships describing growth and senescence of the crop. Normalized difference was significantly better than greenness for all planting dates. For the leaf area growth portion of the season the relation between PAR interception and normalized difference was the same over years and planting dates. For the leaf senescence phase the relationships showed more variability due to the lack of data on light interception in sparse and senescing canopies. Normalized difference could be used to estimate PAR interception throughout a growing season.

  10. Photosynthetic antennae systems: energy transport and optical absorption

    Energy Technology Data Exchange (ETDEWEB)

    Reineker, P. E-mail: peter.reineker@physik.uni-ulm.de; Supritz, Ch.; Warns, Ch.; Barvik, I

    2004-06-01

    The energy transport and the optical line shape of molecular aggregates, modeling bacteria photosynthetic light-harvesting systems (chlorosomes in the case of Chlorobium tepidum or Chloroflexus aurantiacus and LH2 in the case of Rhodopseudomonas acidophila) is investigated theoretically. The molecular units are described by two-level systems with an average excitation energy {epsilon} and interacting with each other through nearest-neighbor interactions. For LH2 an elliptical deformation of the ring is also allowed. Furthermore, dynamic and in the case of LH2 also quasi-static fluctuations of the local excitation energies are taken into account, simulating fast molecular vibrations and slow motions of the protein backbone, respectively. The fluctuations are described by Gaussian Markov processes in the case of the chlorosomes and by colored dichotomic Markov processes, with exponentially decaying correlation functions, with small ({lambda}{sub s}) and large ({lambda}) decay constants, in the case of LH2.

  11. Mathematical Modeling of Acclimation Processes of the Photosynthetic Chain

    Directory of Open Access Journals (Sweden)

    S Heidari

    2016-10-01

    Full Text Available Introduction Photosynthetic energy conversion efficiency is characteristic of a system which is determined by interactions between various components of the system. The complex process of photosynthesis has been studied as a whole system which enables in silico examination of a large number of candidate genes for genetic engineering for a higher photosynthetic energy conversion efficiency. One of the most important environmental factors which influence the photosynthesis efficiency is light regime which can cause producing ROS components. To acclimate to such fluctuations, plants have evolved adaptive mechanisms to minimize damage of the photosynthetic apparatus excess light. A fast compatibility response to high light stresses is non-photochemical quenching process (NPQ, dissipating excessive energy to heat. Light harvested state switches into a quenched state by a conformational change of light harvesting complex (LHCII that regulated by xanthophylls and the PsbS protein within seconds. Low lumen pH activates xanthophyll synthesis via a xanthophyll cycle which consists of the de-epoxidation of violaxanthin to zeaxanthin by violaxanthin de-epoxidase in high light and inversely by zeaxanthin epoxidase in low light which occurs more slowly. Materials and Methods Thale cress (Arabidopsis thaliana (Chlombia-0 were grown on soil at 25/22 °C day/night temperature, with a 16/8 h photoperiod, and 40-70% (depend of plant species relative humidity. The light intensity was 150–200 µE m-2s-1 white light. Intensity of chlorophyll fluorescence was measured with PAM-2000 fluorometer (Heinz Walz, Germany and the manufacturer’s software (PamWin v.2. Results and Discussion In the present study, a dynamic kinetics amplified mathematical model was developed based on differential equations in order to predict short-term changes in NPQ in the process of adaptation to different light conditions. We investigated the stationary and dynamic behavior of the model

  12. Quantum delocalization directs antenna absorption to photosynthetic reaction centers

    CERN Document Server

    Caycedo-Soler, Felipe; Autenrieth, Caroline; Ghosh, Robin; Huelga, Susana F; Plenio, Martin B

    2015-01-01

    Photosynthesis -- the conversion of sunlight to chemical energy -- is fundamental for supporting life on our planet. Despite its importance, the physical principles that underpin the primary steps of photosynthesis, from photon absorption to electronic charge separation, remain to be understood in full. Previously, electronic coherence within tightly-packed light-harvesting (LH) units or within individual reaction centers (RCs) has been recognized as an important ingredient for a complete understanding of the excitation energy transfer dynamics. However, the electronic coherence across RC and LH units has been consistently neglected as it does not play a significant role during these relatively slow transfer processes. Here, we turn our attention to the absorption process, which occurs on much shorter timescales. We demonstrate that the - often overlooked - spatially extended but short-lived excitonic delocalization across RC and LH units plays a relevant role in general photosynthetic systems, as it causes a...

  13. Can phenotypic plasticity in Rubisco performance contribute to photosynthetic acclimation?

    Science.gov (United States)

    Cavanagh, Amanda P; Kubien, David S

    2014-02-01

    Photosynthetic acclimation varies among species, which likely reveals variations at the biochemical level in the pathways that constitute carbon assimilation and energy transfer. Local adaptation and phenotypic plasticity affect the environmental response of photosynthesis. Phenotypic plasticity allows for a wide array of responses from a single individual, encouraging fitness in a broad variety of environments. Rubisco catalyses the first enzymatic step of photosynthesis, and is thus central to life on Earth. The enzyme is well conserved, but there is habitat-dependent variation in kinetic parameters, indicating that local adaptation may occur. Here, we review evidence suggesting that land plants can adjust Rubisco's intrinsic biochemical characteristics during acclimation. We show that this plasticity can theoretically improve CO2 assimilation; the effect is non-trivial, but small relative to other acclimation responses. We conclude by discussing possible mechanisms that could account for biochemical plasticity in land plant Rubisco.

  14. Circadian rhythms of chloroplast orientation and photosynthetic capacity in ulva.

    Science.gov (United States)

    Britz, S J; Briggs, W R

    1976-07-01

    Ulva lactuca L. var. latissima (L.) Decandolle and var. rigida (C. Agardh) Le Jolis and U. mutabilis Foyn have a circadian rhythm of chloroplast orientation which results in large changes in the light-absorption properties of the thallus. During the day, the chloroplasts cover the outer face of the cells and absorbance is high. At night, the chloroplasts are along the side walls and absorbance is low. Enteromorpha linza (L.) J. Agardh, E. intestinalis (L.) Link, E. sp., and Monostroma grevillei (Thuret) Wittrock, members of the Ulvales, were not observed to have this rhythmic movement. Chloroplasts, when in the face position, could not be induced to move to the sides by high intensity light up to 80,000 lux. Unrelated to chloroplast position per se and light-absorption efficiency, there is a rhythm of photosynthetic capacity which peaks just before midday and which continues in constant darkness.

  15. Ecotoxicological studies of CdS nanoparticles on photosynthetic microorganisms.

    Science.gov (United States)

    Brayner, Roberta; Dahoumane, Si Amar; Nguyen, Julie Ngoc-Lan; Yéprémian, Claude; Djediat, Chakib; Couté, Alain; Fiévet, Fernand

    2011-03-01

    The potential ecotoxicity of nanosized cadmium sulfide (CdS), synthesized by the polyol process, was investigated using common Anabaena flos-aquae cyanobacteria and Euglena gracilis euglenoid microalgae. The photosynthetic activities of these microorganisms, after addition of free Cd2+ ions and CdS nanoparticles, varied with the presence of tri-n-octylphosphine oxide (TOPO) used to protect surface particle to avoid toxicity and also to control particle size and shape during the synthesis. The nanoparticle concentration was varied from 10(-3) to 5 x 10(-4) M. It was observed that the cadmium concentration, the addition of TOPO protective agent and the particle dissolution process in the culture medium play an important role during the ecotoxicological tests. Viability tests were followed by PAM fluorimetry. Cd2+ ions were very toxic for Anabaena flos aquae. The same behavior was observed after contact with CdS and CdS-TOPO nanoparticles. However, for Euglena gracilis, the photosynthetic activity was stable for more than 1 month in the presence of Cd2+ ions. Moreover, it was observed that the toxicity varies with the concentration of CdS and CdS-TOPO nanoparticles, both kind of nanoparticles are toxic for this microorganism. Transmission electron microscopy (TEM) analyses of microorganisms ultrathin sections showed that polysaccharides produced by Anabaena flos-aquae, after contact with CdS and CdS-TOPO nanoparticles, protect the microalgae against particle internalization. Only some particles were observed inside the cells. Moreover, the nanoparticle internalization was observed after contact with all nanoparticles in the presence of Euglena gracilis by endocytosis. All nanoparticles are inside vesicles formed by the cells.

  16. Some characteristics of photosynthetic apparatus under conditions of spaceflight.

    Science.gov (United States)

    Volovik, O I; Kordyum, E L; Guikema, J A

    1999-07-01

    During colonization of space by humans, the bioregenerative life-support systems on board the space ships will require the plants with a highly efficient photosynthesis, a process producing food and O2 and removing CO2-Therefore, in recent years the scientists increasingly focus the their attention to study on photosynthetic apparatus of plants grown in space. Although the available data are quite scanty and, at times, controversial, it is Considered that the space grown plants differ from around control plants by growth and development, many structural and functional indices and metabolism. Data exist showing changes in the chlorophyll (Chl) content, structure and number of chloroplasts in the cell, swelling of thylakoids and decrease in the number and size of starch grains in the chloroplasts (for reviews, see Halstead and Dutcher, 1987; Kordyum, 1997). The decrease of shoot fresh weight and reduction of CO2-saturated photosynthetic rate at saturating light intensities in space grown wheat plants in comparison with ground control have been reported by Tripathy et al. (1996). The thylakoids isolated from space grown plants displayed lower rates of electron transport through photosystems I and II (PSI and PSII) and in a whole chain. This study aimed to examine the electron transport rates through PSI and PSII in the isolated thylakoids, to elucidate if there are any differences in accumulation of thylakoid membranes between space grown Brassica rapa plants and ground control plants (based on Chl quantity) and to measure the Chl a/b ratio in isolated thylakoids. These studies were part of the Collaborative US/Ukrainian program during the STS-87 mission (1997).

  17. Photosynthetic activity of vascular bundles in Plantago media leaves.

    Science.gov (United States)

    Miszalski, Zbigniew; Skoczowski, Andrzej; Silina, Ekaterina; Dymova, Olga; Golovko, Tamara; Kornas, Andrzej; Strzalka, Kazimierz

    2016-10-01

    Photosynthetic processes in the leaf lamina and midribs of Plantago media were investigated using plants grown in high light (HL) or low light (LL) conditions. The fluorescence parameters, which indicate photochemical/photosynthetic activity, were different in HL and LL grown plants, but no major differences between lamina and midribs were found. An OJIP test (chlorophyll a fluorescence transient induction) of LL grown plants, indicative of the chloroplast electron transport chain, also showed both tissues to be similar. In HL plants, a partial blockage of electron flow between QA (the primary plastoquinone electron acceptor of PSII) and QB (the secondary plastoquinone acceptor of PSII) was found, and this was less visible in midribs. The effective dissipation of quantum energy per reaction center (DI0/RC) was similar in both tissues of HL grown plants, while in the midribs of LL leaves, this process seemed to be less effective. Measurements of (13)C discrimination showed that the midrib tissues of LL and HL leaves effectively used β-carboxylation products to accumulate their biomass. Thus, the well protected activity of electron transport in midribs with their limited capacity to fix CO2 from the air may indicate the involvement of this tissue in β-carboxylation, transport or signaling. Carbon accumulated in roots showed a lower (13)C discrimination value (more negative) than the values observed in lamina. This could indicate that roots are supplied with assimilates mostly during the light phase of the day cycle with intensive C3 photosynthesis. Copyright © 2016 Elsevier GmbH. All rights reserved.

  18. A variety of glycolipids in green photosynthetic bacteria.

    Science.gov (United States)

    Mizoguchi, Tadashi; Harada, Jiro; Yoshitomi, Taichi; Tamiaki, Hitoshi

    2013-03-01

    The compositions of glycolipids in the following seven strains of green photosynthetic bacteria were investigated at the molecular level using LC-MS coupled with an evaporative light scattering detector: Chlorobium (Chl.) limicola strains Larsen (30 °C as the optimal cultivation temperature) and DSM245 (30 °C), Chlorobaculum (Cba.) tepidum strain ATCC49652 (45 °C), Cba. parvum strain NCIB8327 (30 °C), Cba. limnaeum strain 1549 (30 °C), Chl. phaeovibrioides DSM269 (30 °C), and Chloroflexus (Cfl.) aurantiacus strain J-10-fl (55 °C). Dependence of the molecular structures of glycolipids including the chain-length of their acyl groups upon bacterial cultivation temperatures was clearly observed. The organisms with their optimal temperatures of 30, 45, and 55 °C dominantly accumulated glycolipids possessing the acyl chains in the range of C(15)-C(16), C(16)-C(17), and C(18)-C(20), respectively. Cba. tepidum with an optimal temperature of 45 °C preferred the insertion of a methylene group to produce finally a C(17)-cyclopropane chain. Cfl. aurantiacus cultured optimally at 55 °C caused a drastic increase in the chain-length. Notably, the length of such acyl groups corresponded to that of the esterifying chain in the 17-propionate residues of self-aggregative bacteriochlorophylls-c/d/e, indicating stabilization of their supramolecular structures through hydrophobic interactions among those hydrocarbon chains. Based on the detailed compositions of glycolipids, a survival strategy of green photosynthetic bacteria grown in the wide range of temperatures is discussed.

  19. Excitation energy flow in chlorosome antennas of green photosynthetic bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Mimuro, Mamoru (National Institute for Basic Biology, Aichi (Japan)); Nozawa, Tsunenori (Tohoku Univ., Miyagi (Japan)); Tamai, Naoto; Yamazaki, Iwao (Institute for Molecular Science, Aichi (Japan)); Shimada, Keizou (Tokyo Metropolitan Univ. (Japan)); Lin, Su; Knox, R.S. (Univ. of Rochester, NY (USA)); Wittmershaus, B.P.; Brune, D.C.; Blankenship, R.E. (Arizona State Univ., Tempe (USA))

    1989-10-19

    Energy flow in whole cells of the thermophilic green photosynthetic bacterium Chloroflexus aurantiacus was studied by measurements of time-resolved fluorescence spectra in the picosecond time range, detected by both streak camera and single-photon counting methods. These data characterize the energy-transfer sequence from bacteriochlorophyll c (BChl c), found in membrane-associated antenna structures called chlorosomes, to BChl a in the chlorosome baseplate, then to a BChl a antenna complex in the cytoplasmic membrane, and finally to the photochemical reaction center. Upon selective excitation of BChl c in chlorosomes, the decay time of the emission arising from BChl c was 16 ps. The apparent rise time of the emission from the baseplate pigment was < 3 ps. The time course of the transfer from the baseplate BChl a to the membrane-bound BChl a complex was clearly detected. A major 41-ps decay component of the baseplate BChl a emission corresponded to the rise term found for the membrane-bound BChl a emission. With a kinetic analysis, a model is proposed for the structure and function of the chlorosome antenna system in Chloroflexus aurantiacus. The data suggest that the excitation-transfer process may utilize a novel mechanism that takes advantage of the photophysical properties of aggregated pigments. BChl c molecules form naturally occurring aggregates with oligomeric structures similar to J aggregates, but very different from the organization of antenna pigment-proteins from other photosynthetic organisms. These oligomers absorb light and transfer excitations to a small amount of BChl a antenna proteins in the baseplate. The baseplate acts as an energy-transfer interface between the chlorosome and the antenna protein complexes located within the membrane. The integral membrane antenna complexes in turn deliver the excitations to the reaction center where photosynthesis is initiated by electron-transfer reactions.

  20. Complete fluorescent fingerprints of extremophilic and photosynthetic microbes

    Science.gov (United States)

    Dartnell, Lewis R.; Storrie-Lombardi, Michael C.; Ward, John M.

    2010-10-01

    The work reported here represents a study into the total fluorescence exhibited by a broad selection of model, extremophilic and photosynthetic bacterial strains, over a great range of excitation and emission wavelengths from ultraviolet (UV) through visible to near infrared. The aim is to identify distinctive fluorescent features that may serve as detectable biosignatures of remnant microbial life on the Martian surface. A lab-bench fluorescence spectrometer was used to generate an excitation-emission matrix (EEM) for the unpigmented Escherichia coli, radiation-resistant Deinococcus radiodurans, Antarctic Dry Valley isolates Brevundimonas sp. MV.7 and Rhodococcus sp. MV.10, and the cyanobacterium Synechocystis sp. PCC 6803. Detailed EEMs, representing the fluorescence signature of each organism, are presented, and the most significant features suitable for biosignature surveys are identified, including small-molecule cellular metabolites, light-harvesting photosynthetic pigments and extracellular UV-screening compounds. E. coli exhibits the most intense emission from tryptophan, presumably due to the absence of UV-screening pigments that would shield the organism from short-wavelength light-exciting intracellular fluorescence. The efficacy of commonly available laser diodes for exciting cellular fluorescence is treated, along with the most appropriate filter wavelengths for imaging systems. The best combination of available laser diodes and PanCam filters aboard the ExoMars probe is proposed. The possibility of detecting fluorescence excited by solar UV radiation in freshly exposed surface samples by imaging when both sunlit and shadowed, perhaps by the body of the rover itself, is discussed. We also study how these biological fluorophore molecules may be degraded, and thus the potential biosignatures erased, by the high flux of far-ultraviolet light on Mars.

  1. K-Pg extinction patterns in marine and freshwater environments: The impact winter model

    Science.gov (United States)

    Robertson, Douglas S.; Lewis, William M.; Sheehan, Peter M.; Toon, Owen B.

    2013-07-01

    Chicxulub asteroid impact produced massive extinction in terrestrial environments most likely through an intense heat pulse and subsequent widespread fires. Aquatic environments were shielded from this heat and fire but nevertheless showed massive extinction in marine environments and, for reasons unexplained, far less extinction in freshwater environments. Extinction in marine environments resulted from the effects of an "impact winter" caused by dust and smoke in the atmosphere that extinguished sunlight at the Earth's surface for a period of months to years. The resulting cessation of photosynthesis caused a globally extensive extinction of phytoplankton taxa. Because aquatic ecosystems, unlike terrestrial environments, are strongly dependent on daily photosynthetic output by autotrophs, loss of phytoplankton likely caused catastrophic mortality and extinction in aquatic ecosystems. Other potential causes of mortality in aquatic ecosystems include lower ambient temperatures and anoxia due to the lack of photosynthetic oxygen. Inland waters, although probably subject to high mortality, showed lower proportionate extinction than marine environments probably because of the greater potential among the freshwater taxa for dormancy, the greater efficiency of reaeration by rapid flow to offset oxygen demand, abundant thermal refugia fed by groundwater at moderate temperatures, and preadaptation of freshwater taxa to a great degree of environmental variability. In addition, detrital feeders appear to have had low extinction rates in either marine or freshwater environments, but again freshwater taxa would have been favored by higher renewal rates of detrital organic matter as a result of their direct hydrologic contact with soil.

  2. Carotenoid diagenesis in recent marine sediments--I. The Peru continental shelf (15°S, 75°W) *

    Science.gov (United States)

    Repeta, Daniel J.; Gagosian, Robert B.

    1987-04-01

    We report here the distribution of carotenoids in Peru marine surface sediments, including partial identification of 37 pigments, 33 of which have not been previously reported to occur in marine sediments. Our analysis demonstrates that zooplanktonic crustacea, diatoms, dinoflagellates, cryptomonads, purple nonsulfur photosynthetic bacteria, and unidentified species of photosynthetic bacteria are contributors to sedimentary organic matter. Fucoxanthin, fucoxanthinol, diadinoxanthin, peridinin and peridininol, the principal carotenoids of diatoms and dinoflagellates observed in sediment traps, are nearly absent from our sample, even though these phytoplankton are the primary source of organic matter. We attribute this to the presence of 5,6 epoxides in these pigments, a feature which causes rapid cleavage of the polyene and fragmentation to low molecular weight compounds.

  3. Carotenoid diagenesis in recent marine sediments. I. The Peru continental shelf (15/sup 0/S, 75/sup 0/W)

    Energy Technology Data Exchange (ETDEWEB)

    Repeta, D.J.; Gagosian, R.B.

    1987-04-01

    The authors report here the distribution of carotenoids in Peru marine surface sediments, including partial identification of 37 pigments, 33 of which have not been previously reported to occur in marine sediments. Their analysis demonstrates that zooplanktonic crustacea, diatoms, dinoflagellates, cryptomonads, purple nonsulfur photosynthetic bacteria, and unidentified species of photosynthetic bacteria are contributors to sedimentary organic matter. Fucoxanthin, fucoxanthinol, diadinoxanthin, peridinin and peridininol, the principal carotenoids of diatoms and dinoflagellates observed in sediment traps, are nearly absent from their sample, even though these phytoplankton are the primary source of organic matter. They attribute this to the presence of 5,6 epoxides in these pigments, a feature which causes rapid cleavage of the polyene and fragmentation to low molecular weight compounds.

  4. Protection of Marine Mammals

    NARCIS (Netherlands)

    Knoll, M.; Ciaccia, E.; Dekeling, R.P.A.; Kvadsheim, P.H.; Liddell, K.; Gunnarsson, S.L.; Ludwig, S.; Nissen, I.; Lorenzen, D.; Kreimeyer, R.; Pavan, G.; Meneghetti, N.; Nordlund, N.; Benders, F.P.A.; Zwan, T. van der; Zon, A.T. van; Fraser, L.; Johansson, T.; Garmelius, M.

    2016-01-01

    Within the European Defense Agency (EDA), the Protection of Marine Mammals (PoMM) project, a comprehensive common marine mammal database essential for risk mitigation tools, was established. The database, built on an extensive dataset collection with the focus on areas of operational interest for

  5. Marine Mammal Protection Act

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Marine Mammal Protection Act (MMPA or Act) prohibits, with certain exceptions, the "take" of marine mammals in U.S. waters and by U.S. citizens on the high seas,...

  6. Marine functional food

    NARCIS (Netherlands)

    Luten, J.B.

    2009-01-01

    This book reviews the research on seafood and health, the use and quality aspects of marine lipids and seafood proteins as ingredients in functional foods and consumer acceptance of (marine) functional food. The first chapter covers novel merging areas where seafood may prevent disease and improve

  7. Marin Tsunami (video)

    Science.gov (United States)

    Filmed and edited by: Loeffler, Kurt; Gesell, Justine

    2010-01-01

    Tsunamis are a constant threat to the coasts of our world. Although tsunamis are infrequent along the West coast of the United States, it is possible and necessary to prepare for potential tsunami hazards to minimize loss of life and property. Community awareness programs are important, as they strive to create an informed society by providing education and training. The Marin coast could be struck by a tsunami. Whether you live in Marin County, visit the beaches, or rent or own a home near the coast, it is vital to understand the tsunami threat and take preparation seriously. Marin Tsunami tells the story of what several West Marin communities are doing to be prepared. This video was produced by the US Geological Survey (USGS) in cooperation with the Marin Office of Emergency Services.

  8. High Performance Marine Vessels

    CERN Document Server

    Yun, Liang

    2012-01-01

    High Performance Marine Vessels (HPMVs) range from the Fast Ferries to the latest high speed Navy Craft, including competition power boats and hydroplanes, hydrofoils, hovercraft, catamarans and other multi-hull craft. High Performance Marine Vessels covers the main concepts of HPMVs and discusses historical background, design features, services that have been successful and not so successful, and some sample data of the range of HPMVs to date. Included is a comparison of all HPMVs craft and the differences between them and descriptions of performance (hydrodynamics and aerodynamics). Readers will find a comprehensive overview of the design, development and building of HPMVs. In summary, this book: Focuses on technology at the aero-marine interface Covers the full range of high performance marine vessel concepts Explains the historical development of various HPMVs Discusses ferries, racing and pleasure craft, as well as utility and military missions High Performance Marine Vessels is an ideal book for student...

  9. Eclipse effects on field crops and marine zooplankton: the 29 March 2006 total solar eclipse

    Science.gov (United States)

    Economou, G.; Christou, E. D.; Giannakourou, A.; Gerasopoulos, E.; Georgopoulos, D.; Kotoulas, V.; Lyra, D.; Tsakalis, N.; Tzortziou, M.; Vahamidis, P.; Papathanassiou, E.; Karamanos, A.

    2008-08-01

    Some effects in the biosphere from the Total Solar Eclipse of 29 March 2006 were investigated in field crops and marine zooplankton. Taking into account the decisive role of light on plant life and productivity, measurements of photosynthesis and stomatal behaviour were conducted on seven important field-grown cereal and leguminous crops. A drop in photosynthetic rates, by more than a factor of 5 in some cases, was observed, and the minimum values of photosynthetic rates ranged between 3.13 and 10.13 μmol CO2 m-2 s-1. The drop in solar irradiance and the increase in mesophyll CO2-concentration during the eclipse did not induce stomatal closure thus not blocking CO2 uptake by plants. Light effects on the photochemical phase of photosynthesis may be responsible for the observed depression in photosynthetic rates. Field studies addressing the migratory responses of marine zooplankton (micro-zooplankton (ciliates), and meso-zooplankton) due to the rapid changes in underwater light intensity were also performed. The light intensity attenuation was simulated with the use of accurate underwater radiative transfer modeling techniques. Ciliates, responded to the rapid decrease in light intensity during the eclipse adopting night-time behaviour. From the meso-zooplankton assemblage, various vertical migratory behaviours were adopted by different species.

  10. Eclipse effects on field crops and marine zooplankton: the 29 March 2006 total solar eclipse

    Directory of Open Access Journals (Sweden)

    G. Economou

    2008-08-01

    Full Text Available Some effects in the biosphere from the Total Solar Eclipse of 29 March 2006 were investigated in field crops and marine zooplankton. Taking into account the decisive role of light on plant life and productivity, measurements of photosynthesis and stomatal behaviour were conducted on seven important field-grown cereal and leguminous crops. A drop in photosynthetic rates, by more than a factor of 5 in some cases, was observed, and the minimum values of photosynthetic rates ranged between 3.13 and 10.13 μmol CO2 m−2 s−1. The drop in solar irradiance and the increase in mesophyll CO2-concentration during the eclipse did not induce stomatal closure thus not blocking CO2 uptake by plants. Light effects on the photochemical phase of photosynthesis may be responsible for the observed depression in photosynthetic rates. Field studies addressing the migratory responses of marine zooplankton (micro-zooplankton (ciliates, and meso-zooplankton due to the rapid changes in underwater light intensity were also performed. The light intensity attenuation was simulated with the use of accurate underwater radiative transfer modeling techniques. Ciliates, responded to the rapid decrease in light intensity during the eclipse adopting night-time behaviour. From the meso-zooplankton assemblage, various vertical migratory behaviours were adopted by different species.

  11. Effect of Pot Size on Various Characteristics Related to Photosynthetic Matter Production in Soybean Plants

    Directory of Open Access Journals (Sweden)

    Minobu Kasai

    2012-01-01

    Full Text Available Despite the wide uses of potted plants, information on how pot size affects plant photosynthetic matter production is still considerably limited. This study investigated with soybean plants how transplantation into larger pots affects various characteristics related to photosynthetic matter production. The transplantation was analyzed to increase leaf photosynthetic rate, transpiration rate, and stomatal conductance without affecting significantly leaf intercellular CO2 concentration, implicating that the transplantation induced equal increases in the rate of CO2 diffusion via leaf stomata and the rate of CO2 fixation in leaf photosynthetic cells. Analyses of Rubisco activity and contents of a substrate (ribulose-1,5-bisphosphate (RuBP for Rubisco and total protein in leaf suggested that an increase in leaf Rubisco activity, which is likely to result from an increase in leaf Rubisco content, could contribute to the transplantation-induced increase in leaf photosynthetic rate. Analyses of leaf major photosynthetic carbohydrates and dry weights of source and sink organs revealed that transplantation increased plant sink capacity that uses leaf starch, inducing a decrease in leaf starch content and an increase in whole plant growth, particularly, growth of sink organs. Previously, in the same soybean species, it was demonstrated that negative correlation exists between leaf starch content and photosynthetic rate and that accumulation of starch in leaf decreases the rate of CO2 diffusion within leaf. Thus, it was suggested that the transplantation-induced increase in plant sink capacity decreasing leaf starch content could cause the transplantation-induced increase in leaf photosynthetic rate by inducing an increase in the rate of CO2 diffusion within leaf and thereby substantiating an increase in leaf Rubisco activity in vivo. It was therefore concluded that transplantation of soybean plants into larger pots attempted in this study increased the

  12. Still acting green: continued expression of photosynthetic genes in the heterotrophic Dinoflagellate Pfiesteria piscicida (Peridiniales, Alveolata.

    Directory of Open Access Journals (Sweden)

    Gwang Hoon Kim

    Full Text Available The loss of photosynthetic function should lead to the cessation of expression and finally loss of photosynthetic genes in the new heterotroph. Dinoflagellates are known to have lost their photosynthetic ability several times. Dinoflagellates have also acquired photosynthesis from other organisms, either on a long-term basis or as "kleptoplastids" multiple times. The fate of photosynthetic gene expression in heterotrophs can be informative into evolution of gene expression patterns after functional loss, and the dinoflagellates ability to acquire new photosynthetic function through additional endosymbiosis. To explore this we analyzed a large-scale EST database consisting of 151,091 unique sequences (29,170 contigs, 120,921 singletons obtained from 454 pyrosequencing of the heterotrophic dinoflagellate Pfiesteria piscicida. About 597 contigs from P. piscicida showed significant homology (E-value photosynthetic function. Most of the genes involved in the Calvin-Benson cycle were found, genes of the light-dependent reaction were also identified. Also genes of associated pathways including the chorismate pathway and genes involved in starch metabolism were discovered. BLAST searches and phylogenetic analysis suggest that these plastid-associated genes originated from several different photosynthetic ancestors. The Calvin-Benson cycle genes are mostly associated with genes derived from the secondary plastids of peridinin-containing dinoflagellates, while the light-harvesting genes are derived from diatoms, or diatoms that are tertiary plastids in other dinoflagellates. The continued expression of many genes involved in photosynthetic pathways indicates that the loss of transcriptional regulation may occur well after plastid loss and could explain the organism's ability to "capture" new plastids (i.e. different secondary endosymbiosis or tertiary symbioses to renew photosynthetic function.

  13. Marine Viruses: Key Players in Marine Ecosystems

    Directory of Open Access Journals (Sweden)

    Mathias Middelboe

    2017-10-01

    Full Text Available Viruses were recognized as the causative agents of fish diseases, such as infectious pancreatic necrosis and Oregon sockeye disease, in the early 1960s [1], and have since been shown to be responsible for diseases in all marine life from bacteria to protists, mollusks, crustaceans, fish and mammals [2].[...

  14. Marine Viruses: Key Players in Marine Ecosystems

    OpenAIRE

    Middelboe, Mathias; Brussaard, Corina P. D.

    2017-01-01

    Viruses were recognized as the causative agents of fish diseases, such as infectious pancreatic necrosis and Oregon sockeye disease, in the early 1960s [1], and have since been shown to be responsible for diseases in all marine life from bacteria to protists, mollusks, crustaceans, fish and mammals [2].[...

  15. Marine Viruses: Key Players in Marine Ecosystems.

    Science.gov (United States)

    Middelboe, Mathias; Brussaard, Corina P D

    2017-10-18

    Viruses were recognized as the causative agents of fish diseases, such as infectious pancreatic necrosis and Oregon sockeye disease, in the early 1960s [1], and have since been shown to be responsible for diseases in all marine life from bacteria to protists, mollusks, crustaceans, fish and mammals [2].[...].

  16. Marine scaping: The structuring of marine practices

    NARCIS (Netherlands)

    Toonen, H.M.; Tatenhove, van J.

    2013-01-01

    Oceans and seas are heavily exploited by different kinds of human activities. More and more information becomes a formative force in governing conflicting human activities and spatial claims at sea, as it is changing processes, institutions and practices of marine governance. This paper presents a

  17. Marine fragrance chemistry.

    Science.gov (United States)

    Hügel, Helmut M; Drevermann, Britta; Lingham, Anthony R; Marriott, Philip J

    2008-06-01

    The main marine message in perfumery is projected by Calone 1951 (7-methyl-2H-1,5-benzodioxepin-3(4H)-one). Kraft (Givaudan) and Gaudin (Firmenich) further maximized the marine fragrance molecular membership by extending the carbon chain of the 7-Me group. Our research targeted the polar group of the benzodioxepinone parent compound to investigate how this region of molecular makeup resonates with the dominant marine fragrance of the Calone 1951 structure. The olfactory evaluation of analogues prepared by chemical modification or removal of the CO group resulted in the introduction of aldehydic, sweet and floral-fruity notes with a diluted/diminished potency of the marine odor. To further analyze the olfactory properties of benzodioxepinones containing a diverse range of aromatic ring substituents, a novel synthesis route was developed. We found that a 7-alkyl group in Calone 1951 was essential for the maintenance of the significant marine odor characteristic, and our studies support the concept that the odorant structure occupying the hydrophobic binding pocket adjacent to the aromatic ring-binding site of the olfactory receptor is pivotal in the design and discovery of more potent and characteristic marine fragrances. How the structure of benzodioxepinones connects to marine sea-breeze fragrances is our continuing challenging research focus at the chemistry-biology interface.

  18. Environmental analysis of present and future fuels in 2D simple model marine gas tubines

    Directory of Open Access Journals (Sweden)

    M. Morsy El Gohary

    2013-12-01

    Full Text Available Increased worldwide concerns about fossil fuel costs and effects on the environment lead many governments and scientific societies to consider the hydrogen as the fuel of the future. Many researches have been made to assess the suitability of using the hydrogen gas as fuel for internal combustion engines and gas turbines; this suitability was assessed from several viewpoints including the combustion characteristics, the fuel production and storage and also the thermodynamic cycle changes with the application of hydrogen instead of ordinary fossil fuels. This paper introduces the basic environmental differences happening when changing the fuel of a marine gas turbine from marine diesel fuel to gaseous hydrogen for the same power output. Environmentally, the hydrogen is the best when the CO2 emissions are considered, zero carbon dioxide emissions can be theoretically attained. But when the NOx emissions are considered, the hydrogen is not the best based on the unit heat input. The hydrogen produces 270% more NOx than the diesel case without any control measures. This is primarily due to the increased air flow rate bringing more nitrogen into the combustion chamber and the increased combustion temperature (10% more than the diesel case. Efficient and of course expensive NOx control measures are a must to control these emissions levels.

  19. 77 FR 2512 - Marine Mammals

    Science.gov (United States)

    2012-01-18

    ... National Oceanic and Atmospheric Administration RIN 0648-XA905 Marine Mammals AGENCY: National Marine...; receipt of application. SUMMARY: Notice is hereby given that Dorian Houser, Ph.D., National Marine Mammal... under the authority of the Marine Mammal Protection Act of 1972, as amended (MMPA; 16 U.S.C. 1361 et seq...

  20. 75 FR 77616 - Marine Mammals

    Science.gov (United States)

    2010-12-13

    ... National Oceanic and Atmospheric Administration RIN 0648-XP18 Marine Mammals AGENCY: National Marine... Marine Mammal Protection Act of 1972, as amended (16 U.S.C. 1361 et seq.), the regulations governing the taking and importing of marine mammals (50 CFR part 216), the Endangered Species Act of 1973, as amended...

  1. 76 FR 25308 - Marine Mammals

    Science.gov (United States)

    2011-05-04

    ... National Oceanic and Atmospheric Administration RIN 0648-XA165 Marine Mammals AGENCY: National Marine... ] scientific research on marine mammal parts. ADDRESSES: The permit and related documents are available for..., and export marine mammal parts for scientific research studies. The requested permit has been issued...

  2. 77 FR 14352 - Marine Mammals

    Science.gov (United States)

    2012-03-09

    ... National Oceanic and Atmospheric Administration RIN 0648-XB065 Marine Mammals AGENCY: National Marine... permit has been issued under the authority of the Marine Mammal Protection Act of 1972, as amended (16 U.S.C. 1361 et seq.), the regulations governing the taking and importing of marine mammals (50 CFR...

  3. 76 FR 72680 - Marine Mammals

    Science.gov (United States)

    2011-11-25

    ... National Oceanic and Atmospheric Administration RIN 0648-XA078 Marine Mammals AGENCY: National Marine.... Environmental Research and Services, Fairbanks, AK, to conduct research on marine mammals in Alaska. ADDRESSES... authority of the Marine Mammal Protection Act of 1972, as amended (16 U.S.C. 1361 et seq.), the regulations...

  4. A multi-pathway model for Photosynthetic reaction center

    CERN Document Server

    Qin, M; Yi, X X

    2015-01-01

    Charge separation in light-harvesting complexes occurs in a pair of tightly coupled chlorophylls at the heart of photosynthetic reaction centers of both plants and bacteria. Recently it has been shown that quantum coherence can, in principle, enhance the efficiency of a solar cell, working like a quantum heat engine (QHE). Here, we propose a biological quantum heat engine (BQHE) motivated by Photosystem {\\rm II} reaction center (PS{\\rm II} RC) to describe the charge separation. Our model mainly considers two charge-separation pathways more than that in the published literature. The two pathways can interfere via cross-couplings and work together to enhance the charge-separation yields. We explore how these cross-couplings increase the current and voltage of the charge separation and discuss the advantages of multiple pathways in terms of current and power. The robustness of the BQHE against the charge recombination in natural PS{\\rm II} RC and dephasing induced by environments is also explored, and extension ...

  5. Physiological and photosynthetic response of quinoa to drought stress

    Directory of Open Access Journals (Sweden)

    Rachid Fghire

    2015-06-01

    Full Text Available Water shortage is a critical problem touching plant growth and yield in semi-arid areas, for instance the Mediterranean región. For this reason was studied the physiological basis of drought tolerance of a new, drought tolerant crop quinoa (Chenopodium quinoa Willd. tested in Morocco in two successive seasons, subject to four irrigation treatments (100, 50, and 33%ETc, and rainfed. The chlorophyll a fluorescence transients were analyzed by the JIP-test to transíate stress-induced damage in these transients to changes in biophysical parameter's allowing quantification of the energy flow through the photosynthetic apparatus. Drought stress induced a significant decrease in the maximum quantum yield of primary photochemistry (Φpo = Fv/Fm, and the quantum yield of electron transport (Φeo. The amount of active Photosystem II (PSII reaction centers (RC per excited cross section (RC/CS also decreased when exposed to the highest drought stress. The effective antenna size of active RCs (ABS/RC increased and the effective dissipation per active reaction centers (DIo/RC increased by increasing drought stress during the growth season in comparison to the control. However the performance index (PI, was a very sensitive indicator of the physiological status of plants. Leaf area index, leaf water potential and stomatal conductance decreased as the drought increased. These results indicate that, in quinoa leaf, JIP-test can be used as a sensitive method for measuring drought stress effects.

  6. Mapping diffuse photosynthetically active radiation from satellite data in Thailand

    Science.gov (United States)

    Choosri, P.; Janjai, S.; Nunez, M.; Buntoung, S.; Charuchittipan, D.

    2017-12-01

    In this paper, calculation of monthly average hourly diffuse photosynthetically active radiation (PAR) using satellite data is proposed. Diffuse PAR was analyzed at four stations in Thailand. A radiative transfer model was used for calculating the diffuse PAR for cloudless sky conditions. Differences between the diffuse PAR under all sky conditions obtained from the ground-based measurements and those from the model are representative of cloud effects. Two models are developed, one describing diffuse PAR only as a function of solar zenith angle, and the second one as a multiple linear regression with solar zenith angle and satellite reflectivity acting linearly and aerosol optical depth acting in logarithmic functions. When tested with an independent data set, the multiple regression model performed best with a higher coefficient of variance R2 (0.78 vs. 0.70), lower root mean square difference (RMSD) (12.92% vs. 13.05%) and the same mean bias difference (MBD) of -2.20%. Results from the multiple regression model are used to map diffuse PAR throughout the country as monthly averages of hourly data.

  7. Spectral optical properties of selected photosynthetic microalgae producing biofuels

    Science.gov (United States)

    Lee, Euntaek; Heng, Ri-Liang; Pilon, Laurent

    2013-01-01

    This paper presents the spectral complex index of refraction of biofuel producing photosynthetic microalgae between 400 and 750 nm. They were retrieved from their experimentally measured average absorption and scattering cross-sections. The microalgae were treated as homogeneous polydisperse spheres with equivalent diameter such that their surface area was identical to that of their actual spheroidal shape. An inverse method was developed combining Lorentz-Mie theory as the forward method and genetic algorithm. The unicellular green algae Chlamydomonas reinhardtii strain CC125 and its truncated chlorophyll antenna transformants tla1, tlaX, and tla1-CW+ as well as Botryococcus braunii, Chlorella sp., and Chlorococcum littorale were investigated. These species were selected for their ability to produce either hydrogen gas or lipids for liquid fuel production. Their retrieved real and imaginary parts of the complex index of refraction were continuous functions of wavelength with absorption peaks corresponding to those of in vivo Chlorophylls a and b. The T-matrix method was also found to accurately predict the experimental measurements by treating the microalgae as axisymmetric spheroids with the experimentally measured major and minor diameter distributions and the retrieved spectral complex index of refraction. Finally, pigment mass fractions were also estimated from the retrieved absorption index. The method and/or the reported optical properties can be used in various applications from ocean remote sensing, carbon cycle study, as well as photobiological carbon dioxide mitigation and biofuel production.

  8. Taxon-rich multigene phylogeny of photosynthetic euglenoids (Euglenophyceae

    Directory of Open Access Journals (Sweden)

    Jong Im eKim

    2015-08-01

    Full Text Available To establish taxonomy and understand phylogenetic relationships among strains and species of the photosynthetic euglenoids, we performed phylogenetic analyses based on a four gene sequence dataset (nr SSU and LSU rDNA, and pt SSU and LSU rDNA from 343 taxa (including three outgroup. The phylogenetic tree based on the combined dataset was split into two major clades: Euglenaceae and Phacaceae. The family Euglenaceae was a well-supported monophyletic group containing eight genera (Colacium, Cryptoglena, Euglena, Euglenaformis, Euglenaria, Monomorphina, Strombomonas, and Trachelomonas, each representing a monophyletic lineage, except for the genus Euglena. The genus Euglena was divided into three subclades (A1, A2, and A3 and was paraphyletic due to Euglena archeoplastidiata being grouped with the genus Euglenaria and E. cf. velata with the genus Colacium. The family Phacaceae was supported as a monophyletic group and contained three genera (Discoplastis, Lepocinclis, and Phacus. The genus Phacus contained traditionally defined members as well as the non-traditional P. warszewiczii and P. limnophila, which support the generic concept of Linton et al. (2010.

  9. [Bioinformatics studies on photosynthetic system genes in cyanobacteria and chloroplasts].

    Science.gov (United States)

    Shi, Ding-Ji; Zhang, Chao; Li, Shi-Ming; Li, Ci-Shan; Zhang, Peng-Peng; Yang, Ming-Li

    2004-06-01

    This study compared homology of base sequences in genes encoding photosynthetic system proteins of cyanobacteria (Synechocystics sp. PCC6803, Nostoc sp. PCC7120) with these of chloroplasts (from Marchantia Polymorpha, Nicotiana tobacum, Oryza sativ, Euglena gracilis, Pinus thunbergii, Zea mays, Odentella sinesis, Cyanophora paradoxa, Porphyra purpurea and Arabidopsis thaliana) by BLAST method. While the gene sequence of Synechocystics sp. PCC6803 was considered as the criterion (100%) the homology of others were compared with it. Among the genes for photosystem I, psaC homology was the highest (90.14%) and the lowest was psaJ (52.24%). The highest ones were psbD (83.71%) for photosystem II, atpB (79.58%) for ATP synthase and petB (81.66%) for cytochrome b6/f complex. The lowest ones were psbN (49.70%) for photosystem II, atpF (26.69%) for ATP synthase and petA (55.27%) for cytochrome b6/f complex. Also, this paper discussed why the homology of gene sequences was the highest or the lowest. No report has been published and this bioinformatics research may provide some evidences for the origin and evolution of chloroplasts.

  10. Realistic Quantum Control of Energy Transfer in Photosynthetic Processes

    Directory of Open Access Journals (Sweden)

    Reda M. El-Shishtawy

    2016-12-01

    Full Text Available The occurrence of coherence phenomenon as a result of the interference of the probability amplitude terms is among the principle features of quantum mechanics concepts. Current experiments display the presence of quantum techniques whose coherence is supplied over large interval times. Specifically, photosynthetic mechanisms in light-harvesting complexes furnish oscillatory behaviors owing to quantum coherence. In this manuscript, we study the coherent quantum energy transfer for a single-excitation and nonlocal correlation in a dimer system (donor+acceptor displayed by two-level systems (TLSs, interacting with a cavity field with a time-dependent coupling effect considering the realistic situation of coupling between each TLS and the cavity field. We analyze and explore the specific conditions which are viable with real experimental realization for the ultimate transfer of quantum energy and nonlocal quantum correlation. We show that the enhancement of the probability for a single-excitation energy transfer greatly benefits from the energy detuning, photon-number transition, classicality of the field, and the time-dependent coupling effect. We also find that the entanglement between the donor and acceptor is very sensitive to the physical parameters and it can be generated during the coherent energy transfer.

  11. Design of Photobioreactors for Mass Cultivation of Photosynthetic Organisms

    Directory of Open Access Journals (Sweden)

    Qingshan Huang

    2017-06-01

    Full Text Available Photosynthetic microorganisms are important bioresources for producing desirable and environmentally benign products, and photobioreactors (PBRs play important roles in these processes. Designing PBRs for photocatalysis is still challenging at present, and most reactors are designed and scaled up using semi-empirical approaches. No appropriate types of PBRs are available for mass cultivation due to the reactors’ high capital and operating costs and short lifespan, which are mainly due to a current lack of deep understanding of the coupling of light, hydrodynamics, mass transfer, and cell growth in efficient reactor design. This review provides a critical overview of the key parameters that influence the performance of the PBRs, including light, mixing, mass transfer, temperature, pH, and capital and operating costs. The lifespan and the costs of cleaning and temperature control are also emphasized for commercial exploitation. Four types of PBRs—tubular, plastic bag, column airlift, and flat-panel airlift reactors are recommended for large-scale operations. In addition, this paper elaborates the modeling of PBRs using the tools of computational fluid dynamics for rational design. It also analyzes the difficulties in the numerical simulation, and presents the prospect for mechanism-based models.

  12. Engineering biosynthesis of high-value compounds in photosynthetic organisms.

    Science.gov (United States)

    O'Neill, Ellis C; Kelly, Steven

    2017-09-01

    The photosynthetic, autotrophic lifestyle of plants and algae position them as ideal platform organisms for sustainable production of biomolecules. However, their use in industrial biotechnology is limited in comparison to heterotrophic organisms, such as bacteria and yeast. This usage gap is in part due to the challenges in generating genetically modified plants and algae and in part due to the difficulty in the development of synthetic biology tools for manipulating gene expression in these systems. Plant and algal metabolism, pre-installed with multiple biosynthetic modules for precursor compounds, bypasses the requirement to install these pathways in conventional production organisms, and creates new opportunities for the industrial production of complex molecules. This review provides a broad overview of the successes, challenges and future prospects for genetic engineering in plants and algae for enhanced or de novo production of biomolecules. The toolbox of technologies and strategies that have been used to engineer metabolism are discussed, and the potential use of engineered plants for industrial manufacturing of large quantities of high-value compounds is explored. This review also discusses the routes that have been taken to modify the profiles of primary metabolites for increasing the nutritional quality of foods as well as the production of specialized metabolites, cosmetics, pharmaceuticals and industrial chemicals. As the universe of high-value biosynthetic pathways continues to expand, and the tools to engineer these pathways continue to develop, it is likely plants and algae will become increasingly valuable for the biomanufacturing of high-value compounds.

  13. Active transport of Ca2+ by an artificial photosynthetic membrane.

    Science.gov (United States)

    Bennett, Ira M; Farfano, Hebe M Vanegas; Bogani, Federica; Primak, Alex; Liddell, Paul A; Otero, Luis; Sereno, Leonides; Silber, Juana J; Moore, Ana L; Moore, Thomas A; Gust, Devens

    2002-11-28

    Transport of calcium ions across membranes and against a thermodynamic gradient is essential to many biological processes, including muscle contraction, the citric acid cycle, glycogen metabolism, release of neurotransmitters, vision, biological signal transduction and immune response. Synthetic systems that transport metal ions across lipid or liquid membranes are well known, and in some cases light has been used to facilitate transport. Typically, a carrier molecule located in a symmetric membrane binds the ion from aqueous solution on one side and releases it on the other. The thermodynamic driving force is provided by an ion concentration difference between the two aqueous solutions, coupling to such a gradient in an auxiliary species, or photomodulation of the carrier by an asymmetric photon flux. Here we report a different approach, in which active transport is driven not by concentration gradients, but by light-induced electron transfer in a photoactive molecule that is asymmetrically disposed across a lipid bilayer. The system comprises a synthetic, light-driven transmembrane Ca2+ pump based on a redox-sensitive, lipophilic Ca2+-binding shuttle molecule whose function is powered by an intramembrane artificial photosynthetic reaction centre. The resulting structure transports calcium ions across the bilayer of a liposome to develop both a calcium ion concentration gradient and a membrane potential, expanding Mitchell's concept of a redox loop mechanism for protons to include divalent cations. Although the quantum yield is relatively low (approximately 1 per cent), the Ca2+ electrochemical potential developed is significant.

  14. Evolutionary bursts in Euphorbia (Euphorbiaceae) are linked with photosynthetic pathway.

    Science.gov (United States)

    Horn, James W; Xi, Zhenxiang; Riina, Ricarda; Peirson, Jess A; Yang, Ya; Dorsey, Brian L; Berry, Paul E; Davis, Charles C; Wurdack, Kenneth J

    2014-12-01

    The mid-Cenozoic decline of atmospheric CO2 levels that promoted global climate change was critical to shaping contemporary arid ecosystems. Within angiosperms, two CO2 -concentrating mechanisms (CCMs)-crassulacean acid metabolism (CAM) and C4 -evolved from the C3 photosynthetic pathway, enabling more efficient whole-plant function in such environments. Many angiosperm clades with CCMs are thought to have diversified rapidly due to Miocene aridification, but links between this climate change, CCM evolution, and increased net diversification rates (r) remain to be further understood. Euphorbia (∼2000 species) includes a diversity of CAM-using stem succulents, plus a single species-rich C4 subclade. We used ancestral state reconstructions with a dated molecular phylogeny to reveal that CCMs independently evolved 17-22 times in Euphorbia, principally from the Miocene onwards. Analyses assessing among-lineage variation in r identified eight Euphorbia subclades with significantly increased r, six of which have a close temporal relationship with a lineage-corresponding CCM origin. Our trait-dependent diversification analysis indicated that r of Euphorbia CCM lineages is approximately threefold greater than C3 lineages. Overall, these results suggest that CCM evolution in Euphorbia was likely an adaptive strategy that enabled the occupation of increased arid niche space accompanying Miocene expansion of arid ecosystems. These opportunities evidently facilitated recent, replicated bursts of diversification in Euphorbia. © 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution.

  15. Quantum correlation dynamics in photosynthetic processes assisted by molecular vibrations

    Energy Technology Data Exchange (ETDEWEB)

    Giorgi, G.L., E-mail: g.giorgi@inrim.it [INRIM, Strada delle Cacce 91, I-10135 Torino (Italy); Roncaglia, M. [INRIM, Strada delle Cacce 91, I-10135 Torino (Italy); Raffa, F.A. [Politecnico di Torino, Dipartimento di Scienza Applicata e Tecnologia, Corso Duca degli Abruzzi 24, I-10129 Torino (Italy); Genovese, M. [INRIM, Strada delle Cacce 91, I-10135 Torino (Italy)

    2015-10-15

    During the long course of evolution, nature has learnt how to exploit quantum effects. In fact, recent experiments reveal the existence of quantum processes whose coherence extends over unexpectedly long time and space ranges. In particular, photosynthetic processes in light-harvesting complexes display a typical oscillatory dynamics ascribed to quantum coherence. Here, we consider the simple model where a dimer made of two chromophores is strongly coupled with a quasi-resonant vibrational mode. We observe the occurrence of wide oscillations of genuine quantum correlations, between electronic excitations and the environment, represented by vibrational bosonic modes. Such a quantum dynamics has been unveiled through the calculation of the negativity of entanglement and the discord, indicators widely used in quantum information for quantifying the resources needed to realize quantum technologies. We also discuss the possibility of approximating additional weakly-coupled off-resonant vibrational modes, simulating the disturbances induced by the rest of the environment, by a single vibrational mode. Within this approximation, one can show that the off-resonant bath behaves like a classical source of noise.

  16. PARduino: A Simple Device Measuring and Logging Photosynthetically Active Radiation

    Science.gov (United States)

    Barnard, H. R.; Findley, M. C.

    2013-12-01

    Photosynthetically Active Radiation (PAR, 400 to 700 nm) is one of the primary controls of forest carbon and water relations. In complex terrain, PAR has high spatial-variability. Given the high cost of commercial datalogging equipment, spatially-distributed measurements of PAR have been typically modeled using geographic coordinates and terrain indices. Here, we present a design for a low cost, field-deployable device for measuring and logging PAR built around an Arduino microcontroller (we named it PARduino). PARduino provides for widely distributed sensor arrays and tests the feasibility of using hobbyist-grade electronics for collecting scientific data. PARduino components include a LiCor quantum sensor, EME Systems signal converter/amplifier, and Sparkfun's Arduino Pro Mini microcontroller. Additional components include a real time clock, a microSD flash memory card, and a custom printed circuit board (PCB). We selected the components with an eye towards ease of assembly. Everything can be connected to the PCB using through-hole soldering techniques. Since the device will be deployed in remote research plots that lack easy access to line power, battery life was also a consideration in the design. Extended deployment is possible because PARduino's software keeps it in a low-power sleep mode until ready to make a measurement. PARduino will be open-source hardware for use and improvement by others.

  17. Engineering analysis of potential photosynthetic bacterial hydrogen-production systems

    Science.gov (United States)

    Herlevich, A.; Karpuk, M. E.

    1982-06-01

    Photosynthetic bacteria (PSB) are capable of generating hydrogen from organics in effluents from food processing, pulp and paper, and chemical and pharmaceutical industries. Hydrogen evolution takes place under light in the absence of air. The rate of hydrogen production is expected to range between 300 to 600 scf of hydrogen per 1000 galloons of waste stream treated per hour. This hydrogen production system has been demonstrated at a bench-scale level and is ready for engineering development. A conceptual design for a PSB hydrogen production system is described. The system is expected to be sited adjacent to a waste stream source which will be pretreated by fermentation and pH adjustment, innoculated with bacteria, and then passed into the reactor. The reactor effluent can either be discharged into a rapid infiltration system, an irrigation ditch, and/or recycled back into the reactor. Several potential reactor designs have been developed, analyzed, and costed. A large covered pond appears to be the most economical design approach.

  18. Host control and nutrient trading in a photosynthetic symbiosis.

    Science.gov (United States)

    Dean, Andrew D; Minter, Ewan J A; Sørensen, Megan E S; Lowe, Christopher D; Cameron, Duncan D; Brockhurst, Michael A; Jamie Wood, A

    2016-09-21

    Photosymbiosis is one of the most important evolutionary trajectories, resulting in the chloroplast and the subsequent development of all complex photosynthetic organisms. The ciliate Paramecium bursaria and the alga Chlorella have a well established and well studied light dependent endosymbiotic relationship. Despite its prominence, there remain many unanswered questions regarding the exact mechanisms of the photosymbiosis. Of particular interest is how a host maintains and manages its symbiont load in response to the allocation of nutrients between itself and its symbionts. Here we construct a detailed mathematical model, parameterised from the literature, that explicitly incorporates nutrient trading within a deterministic model of both partners. The model demonstrates how the symbiotic relationship can manifest as parasitism of the host by the symbionts, mutualism, wherein both partners benefit, or exploitation of the symbionts by the hosts. We show that the precise nature of the photosymbiosis is determined by both environmental conditions (how much light is available for photosynthesis) and the level of control a host has over its symbiont load. Our model provides a framework within which it is possible to pose detailed questions regarding the evolutionary behaviour of this important example of an established light dependent endosymbiosis; we focus on one question in particular, namely the evolution of host control, and show using an adaptive dynamics approach that a moderate level of host control may evolve provided the associated costs are not prohibitive. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  19. Protein translocons in photosynthetic organelles of Paulinella chromatophora

    Directory of Open Access Journals (Sweden)

    Przemysław Gagat

    2014-12-01

    Full Text Available The rhizarian amoeba Paulinella chromatophora harbors two photosynthetic cyanobacterial endosymbionts (chromatophores, acquired independently of primary plastids of glaucophytes, red algae and green plants. These endosymbionts have lost many essential genes, and transferred substantial number of genes to the host nuclear genome via endosymbiotic gene transfer (EGT, including those involved in photosynthesis. This indicates that, similar to primary plastids, Paulinella endosymbionts must have evolved a transport system to import their EGT-derived proteins. This system involves vesicular trafficking to the outer chromatophore membrane and presumably a simplified Tic-like complex at the inner chromatophore membrane. Since both sequenced Paulinella strains have been shown to undergo differential plastid gene losses, they do not have to possess the same set of Toc and Tic homologs. We searched the genome of Paulinella FK01 strain for potential Toc and Tic homologs, and compared the results with the data obtained for Paulinella CCAC 0185 strain, and 72 cyanobacteria, eight Archaeplastida as well as some other bacteria. Our studies revealed that chromatophore genomes from both Paulinella strains encode the same set of translocons that could potentially create a simplified but fully-functional Tic-like complex at the inner chromatophore membranes. The common maintenance of the same set of translocon proteins in two Paulinella strains suggests a similar import mechanism and/or supports the proposed model of protein import. Moreover, we have discovered a new putative Tic component, Tic62, a redox sensor protein not identified in previous comparative studies of Paulinella translocons.

  20. Leaf development and photosynthetic properties of three tropical tree species with delayed greening

    NARCIS (Netherlands)

    Cai, Z.Q.; Slot, M.; Fan, Z.X.

    2005-01-01

    Leaf developmental patterns were characterized for three tropical tree species with delayed greening. Changes in the pigment contents, photosynthetic capacity, stomata development, photosystem 2 efficiency, rate of energy dissipation, and the activity of partial protective enzymes were followed in

  1. Photosynthetic CO{sub 2} fixation and energy production - microalgae as a main subject

    Energy Technology Data Exchange (ETDEWEB)

    Asada, Yasuo [National Inst. of Bioscience and Human-Technology, Tsukuba-shi, Ibaraki-ken (Japan)

    1993-12-31

    Research activities for application of microalgal photosynthesis to CO{sub 2} fixation in Japan are overviewed. Presenter`s studies on energy (hydrogen gas) production by cyanobacteria (blue-green algae) and photosynthetic bacteria are also introduced.

  2. Photosynthetic characteristics of the phytoplankton in the Scheldt estuary: community and single-cell fluorescence measurements

    NARCIS (Netherlands)

    Dijkman, N.A.; Kromkamp, J.C.

    2006-01-01

    Estuaries present a very dynamic environment for phytoplankton with large changes in salinity occurring over relatively short distances, usually with high turbidity. We investigated the photosynthetic characteristics of phytoplankton in the Scheldt estuary (Belgium and the Netherlands) along a

  3. Photosynthetically Available Radiation, Aqua MODIS, NPP, 0.125 degrees, East US

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — MODIS measures photosynthetically available radiation that may be used to mode primary productivity. THIS IS AN EXPERIMENTAL PRODUCT: intended strictly for...

  4. Photosynthetically Available Radiation, Aqua MODIS, NPP, 0.05 degrees, Global, Science Quality

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — MODIS measures photosynthetically available radiation that may be used to mode primary productivity. THIS IS AN EXPERIMENTAL PRODUCT: intended strictly for...

  5. Photosynthetically Available Radiation, Aqua MODIS, NPP, 0.125 degrees, Gulf of Mexico

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — MODIS measures photosynthetically available radiation that may be used to mode primary productivity. THIS IS AN EXPERIMENTAL PRODUCT: intended strictly for...

  6. Photosynthetically Available Radiation, Aqua MODIS, NPP, 0.125 degrees, West US

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — MODIS measures photosynthetically available radiation that may be used to mode primary productivity. THIS IS AN EXPERIMENTAL PRODUCT: intended strictly for...

  7. On the photosynthetic responses of crops to intracanopy lighting with light emitting diodes

    NARCIS (Netherlands)

    Trouwborst, G.

    2011-01-01

    Key words: Cucumis sativus, intracanopy lighting, light-emitting diodes (LEDs), light distribution, light interception, light quality, photosynthesis, photosynthetic acclimation Assimilation lighting is a production factor of increasing importance in Dutch greenhouse horticulture. Assimilation

  8. Quantum - coherent dynamics in photosynthetic charge separation revealed by wavelet analysis

    NARCIS (Netherlands)

    Romero, Elisabet; Prior, Javier; Chin, Alex W.; Morgan, Sarah E.; Novoderezhkin, Vladimir I.; Plenio, Martin B.; van Grondelle, Rienk

    2017-01-01

    Experimental/theoretical evidence for sustained vibration-assisted electronic (vibronic) coherence in the Photosystem II Reaction Center (PSII RC) indicates that photosynthetic solar-energy conversion might be optimized through the interplay of electronic and vibrational quantum dynamics. This

  9. Using a Microscale Approach to Rapidly Separate and Characterize Three Photosynthetic Pigment Species from Fern

    Science.gov (United States)

    Ayudhya, Theppawut Israsena Na; Posey, Frederick T.; Tyus, Jessica C.; Dingra, Nin N.

    2015-01-01

    A rapid separation of three photosynthetic pigments (chlorophyll "a" and "b" and xanthophyll) from fern ("Polystichum acrostichoides") is described using microscale solvent extraction and traditional thin layer chromatography that minimizes use of harmful chemicals and lengthy procedures. The experiment introduces…

  10. Characterization of purple and green photosynthetic bacteria isolated from the lagoon of Agatti Atoll (Lakshadweep Sea)

    Digital Repository Service at National Institute of Oceanography (India)

    LokaBharathi, P.A.; Chandramohan, D.

    anaerobic photooxidation in the process of CO2 assimilation2. Not much information is available on these bacteria in tropical waters except one report on the photosynthetic non-sulphur bacteria of Rhodospirillaceae in India3. The present communi- cation...

  11. Leaf hydraulic evolution led a surge in leaf photosynthetic capacity during early angiosperm diversification.

    Science.gov (United States)

    Brodribb, Tim J; Feild, Taylor S

    2010-02-01

    Angiosperm evolution transformed global ecology, and much of this impact derives from the unrivalled vegetative productivity of dominant angiosperm clades. However, the origins of high photosynthetic capacity in angiosperms remain unknown. In this study, we describe the steep trajectory of leaf vein density (D(v)) evolution in angiosperms, and predict that this leaf plumbing innovation enabled a major shift in the capacity of leaves to assimilate CO(2). Reconstructing leaf vein evolution from an examination of 504 angiosperm species we found a rapid three- to fourfold increase in D(v) occurred during the early evolution of angiosperms. We demonstrate how this major shift in leaf vein architecture potentially allowed the maximum photosynthetic capacity in angiosperms to rise above competing groups 140-100 Ma. Our data suggest that early terrestrial angiosperms produced leaves with low photosynthetic rates, but that subsequent angiosperm success is linked to a surge in photosynthetic capacity during their early diversification.

  12. Microscale spatial distributions of microbes and viruses in intertidal photosynthetic microbial mats

    NARCIS (Netherlands)

    Carreira, C; Piel, T; Staal, M.; Stuut, J.-B; Middelboe, M.; Brussaard, C.P.D.

    2015-01-01

    Intertidal photosynthetic microbial mats from the Wadden Sea island Schiermonnikoog were examined for microscale (millimetre) spatial distributions of viruses, prokaryotes and oxygenic photoautotrophs (filamentous cyanobacteria and benthic diatoms) at different times of the year. Abundances of

  13. Comparison of Extrapolation and Interpolation Methods for Estimating Daily Photosynthetically Active Radiation (PAR)

    NARCIS (Netherlands)

    Wu, G.; Skidmore, A.K.; Leeuw, de J.; Liu, X.; Prins, H.H.T.

    2010-01-01

    Measurements of photosynthetically active radiation (PAR), which are indispensable for simulating plant growth and productivity, are generally very scarce. This study aimed to compare two extrapolation and one interpolation methods for estimating daily PAR reaching the earth surface within the

  14. VIIRSN Level-3 Standard Mapped Image, Photosynthetically available radiation, Monthly, 4km

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch distributes photosynthetically available radiation data from ther NPP-Suomi spacecraft. Measurements are gathered by VIIRS instrument carried aboard...

  15. Polyhouse cultivation of invitro raised elite Stevia rebaudiana Bertoni: An assessment of biochemical and photosynthetic characteristics

    Science.gov (United States)

    Polyhouse cultivated Stevia rebaudiana Bertoni plants, initially raised from synthetic seeds, were assessed for biochemical and photosynthetic characteristics and compared with their mother plant. Synthetic seeds were produced using nodal segments containing single axillary buds excised from in vitr...

  16. 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.

  17. VIIRSN Level-3 Standard Mapped Image, Photosynthetically available radiation, 8-Day, 4km

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch distributes photosynthetically available radiation data from the NPP-Suomi Spacecraft Measurements are gathered by the VIIRS instrument carried...

  18. Calibration of the Odyssey Photosynthetic Irradiance Recorder for Absolute Irradiance Measures

    Science.gov (United States)

    Researchers are increasingly interested in measuring hotosynthetically active radiation (PAR) because of its importance in determining the structure and function of lotic ecosystems. The Odyssey Photosynthetic Irradiance Recorder is an affordable PAR meter gaining popularity am...

  19. A Global Data Set of Leaf Photosynthetic Rates, Leaf N and P, and Specific Leaf Area

    Data.gov (United States)

    National Aeronautics and Space Administration — This global data set of photosynthetic rates and leaf nutrient traits was compiled from a comprehensive literature review. It includes estimates of Vcmax (maximum...

  20. A Global Data Set of Leaf Photosynthetic Rates, Leaf N and P, and Specific Leaf Area

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This global data set of photosynthetic rates and leaf nutrient traits was compiled from a comprehensive literature review. It includes estimates of Vcmax...

  1. Mariner Outreach Data -

    Data.gov (United States)

    Department of Transportation — This dataset provides MARAD with the ability to determine available personnel and resources in a time of emergency. It also provides a portal for mariners to update...

  2. Marine Bacterial Genomics

    DEFF Research Database (Denmark)

    Machado, Henrique

    microorganisms to be used as cell factories for production. Therefore exploitation of new microbial niches and use of different strategies is an opportunity to boost discoveries. Even though scientists have started to explore several habitats other than the terrestrial ones, the marine environment stands out...... as a hitherto under-explored niche. This thesis work uses high-throughput sequencing technologies on a collection of marine bacteria established during the Galathea 3 expedition, with the purpose of unraveling new biodiversity and new bioactivities. Several tools were used for genomic analysis in order...... to better understand the potential harbored in marine bacteria. The work presented makes use of whole genome sequencing of marine bacteria to prove that the genetic repertoire for secondary metabolite production harbored in these bacteria is far larger than anticipated; to identify and develop a new...

  3. Marine Reference Materials

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Various publications and other instructions for taking marine weather observations. includes Weather Service Observing Handbook No. 1, Weather Bureau Circular M, and...

  4. Marine Life Study

    Science.gov (United States)

    1988-01-01

    As a result of widespread ocean dumping and other pollution problems, marine scientists at Morgan State University are studying the populations of various marine organisms to determine the effects of pollution. They are also compiling data on the aging of marine organisms. There now exists a new method of determining the age of the surf clam. They are applying digital image processing to clam aging investigations. Computer creates digitized images of clam sections with annual rings. The image is enhanced -- manipulated to emphasize certain features in order to improve and amplify the information that can be extracted from the image. Also useful in other marine organisms that have growth bands making it easier to get an accurate count.

  5. Marine meteorology and fisheries

    Digital Repository Service at National Institute of Oceanography (India)

    RameshBabu, V.

    importance migrate in response to changes in sea temperature storms of shorter duration also influence the distribution of fish in shallow coastal waters as they set up turbulent conditions to which some species are unable to withstand. Therefore marine...

  6. PIR Marine Turtle Nesting

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Effective management of marine turtle data is essential to maximize their research value and enable timely population assessments and recovery monitoring. To provide...

  7. Biotechnology of marine fungi

    Digital Repository Service at National Institute of Oceanography (India)

    Damare, S.; Singh, P.; Raghukumar, S.

    Filamentous fungi are the most widely used eukaryotes in industrial and pharmaceutical applications. Their biotechnological uses include the production of enzymes, vitamins, polysaccharides, pigments, lipids and others. Marine fungi are a still...

  8. Foodborne Marine Biotoxins

    National Research Council Canada - National Science Library

    Poli, Mark

    2003-01-01

    ...). In addition to human intoxications, they cause massive fish kills, negatively impact coastal tourism and fishery industries, and have been implicated in mass mortalities of birds and marine mammals...

  9. LEGACY - EOP Marine Debris

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data contains towed diver surveys of and weights of marine debris removed from the near shore environments of the NWHI.

  10. Exopolysaccharides from marine bacteria

    Science.gov (United States)

    Chi, Zhenming; Fang, Yan

    2005-01-01

    Microbial polysaccharides represent a class of important products of growing interest for many sectors of industry. In recent years, there has been a growing interest in isolating new exopolysaccharides (EPSs)-producing bacteria from marine environments, particularly from various extreme marine environments. Many new marine microbial EPSs with novel chemical compositions, properties and structures have been found to have potential applications in fields such as adhesives, textiles, Pharmaceuticals and medicine for anti-cancer, food additives, oil recovery and metal removal in mining and industrial waste treatments, etc This paper gives a brief summary of the information about the EPSs produced by marine bacteria, including their chemical compositions, properties and structures, together with their potential applications in industry.

  11. Marine Trackline Geophysical Database

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains bathymetry, magnetic, gravity and seismic shot point navigation data collected during marine cruises from 1939 to the present. Coverage is...

  12. Permitted Marine Hydrokinetic Projects

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data represents pending or issued preliminary permits or issued licenses for marine hydrokinetic projects that produce energy from waves or directly from the...

  13. Marine turtle capture data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — To estimate abundance, growth, and survival rate and to collect tissue samples, marine turtles are captured at nesting beaches and foraging grounds through various...

  14. Marine prostanoids - a review

    Digital Repository Service at National Institute of Oceanography (India)

    Wahidullah, S.; DeSouza, L.

    The occurrence and structure of prostaglandins including clavulones, punaglandins and claviridenones in marine organisms is reviewEd. by comparison of the spectral data reported the identity of 20-acetoxy claviridenones b and c with 20 acetoxy...

  15. The marine cyanobacterium

    NARCIS (Netherlands)

    Pade, N.; Compaoré, J.; Klähn, S.; Stal, L.J.; Hagemann, M.

    2012-01-01

    Compatible solutes are small organic molecules that are involved in the acclimation to various stresses such as temperature and salinity. Marine or moderate halotolerant cyanobacteria accumulate glucosylglycerol, while cyanobacteria with low salt tolerance (freshwater strains) usually accumulate

  16. Marine Sanitation Devices (MSDs)

    Science.gov (United States)

    Marine sanitation devices treat or retain sewage from vessels, and have performance standards set by the EPA. This page provides information on MSDs, including who must use an MSD, states' roles, types of MSDs and standards.

  17. WMO Marine Final Reports

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Final reports of the World Meteorological Organization (WMO) Commission for Marine Meteorology, Commission for Synoptic Meteorology, and Commission for Basic...

  18. Marine Pollution Prevention Act

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Marine Pollution Prevention Act of 2008 implements the International Convention for the Prevention of Pollution from Ships, including related Protocols (MARPOL)...

  19. Assembly of Photosynthetic Antenna Protein / Pigments Complexes from Algae and Plants for Development of Nanobiodevices

    Science.gov (United States)

    2012-07-10

    synthetic protein-mimic materials. The majority of the aim is construction of the array of artificial photosynthetic antenna system with nano-patterning...developing nano-biophotonics as well as for energy harvesting materials. We proposed a scenario where the construction of artificial photosynthetic...bacterial photosynthesis . The structure of the reaction center (RC, the first membrane protein to have its structure determined to high resolution) revealed

  20. FLUORESCENT ANALYSIS OF PHOTOSYNTHETIC MICROBES AND POLYCYCLIC AROMATIC HYDROCARBONS LINKED TO OPTICAL REMOTE SENSING

    OpenAIRE

    Zhang, D.; Muller, J.-P.; Lavender, S.; Walton, D.; Dartnell, L. R.

    2012-01-01

    Fluorescence analysis, being a non-invasive technique, has become one of the most powerful and widely used techniques for microbiologists and chemists to study various types of sample from photosynthetic microbes to hydrocarbons. The work reported here focuses on experimental results of fluorescent features of photosynthetic microbial species (cyanobacteria) and also five different crude oil samples. The cyanobacteria samples were collected from the Baltic Sea at the end of July 2011...

  1. Fiber-optic fluorometer for microscale mapping of photosynthetic pigments in microbial communities

    DEFF Research Database (Denmark)

    Thar, Roland Matthias; Kühl, Michael; Holst, Gerhard

    2001-01-01

    Microscale fluorescence measurements were performed in photosynthetic biofilms at a spatial resolution of 100 to 200 µm with a new fiber-optic fluorometer which allowed four different excitation and emission wavelengths and was configured for measuring phycobiliproteins, chlorophylls, and bacteri......Microscale fluorescence measurements were performed in photosynthetic biofilms at a spatial resolution of 100 to 200 µm with a new fiber-optic fluorometer which allowed four different excitation and emission wavelengths and was configured for measuring phycobiliproteins, chlorophylls...

  2. Bycatch in marine fisheries

    OpenAIRE

    Ward, John M.; Benaka, Lee R.; Moore, Christopher M.; Meyers, Steve

    2012-01-01

    A review of the significant contributions in the peer-reviewed literature indicates that the discarding of marine fish known as bycatch remains one of the most significant problem facing fisheries managers. Bycatch has negative affects on marine biodiversity, is ripe with ethical and moral issues surrounding the waste of life from increased juvenile fish mortality, hinders commercial profitability and recreational satisfaction, increases management costs, and results in socio-cultural problem...

  3. Marine Ecosystem Services

    DEFF Research Database (Denmark)

    Hasler, Berit; Ahtiainen, Heini; Hasselström, Linus

    MARECOS (Marine Ecosystem Services) er et tværfagligt studie, der har haft til formål at tilvejebringe information vedrørende kortlægning og værdisætning af økosystemtjenester, som kan anvendes i forbindelse med udformning af regulering på det marine område såvel nationalt, som regionalt og...

  4. Marine Anthropogenic Litter

    OpenAIRE

    Bergmann, Melanie; Gutow, Lars; Klages, Michael

    2015-01-01

    This book describes how manmade litter, primarily plastic, has spread into the remotest parts of the oceans and covers all aspects of this pollution problem from the impacts on wildlife and human health to socio-economic and political issues. Marine litter is a prime threat to marine wildlife, habitats and food webs worldwide. The book illustrates how advanced technologies from deep-sea research, microbiology and mathematic modelling as well as classic beach litter counts by volunteers co...

  5. Improved Marine Waters Monitoring

    Science.gov (United States)

    Palazov, Atanas; Yakushev, Evgeniy; Milkova, Tanya; Slabakova, Violeta; Hristova, Ognyana

    2017-04-01

    IMAMO - Improved Marine Waters Monitoring is a project under the Programme BG02: Improved monitoring of marine waters, managed by Bulgarian Ministry of environment and waters and co-financed by the Financial Mechanism of the European Economic Area (EEA FM) 2009 - 2014. Project Beneficiary is the Institute of oceanology - Bulgarian Academy of Sciences with two partners: Norwegian Institute for Water Research and Bulgarian Black Sea Basin Directorate. The Project aims to improve the monitoring capacity and expertise of the organizations responsible for marine waters monitoring in Bulgaria to meet the requirements of EU and national legislation. The main outcomes are to fill the gaps in information from the Initial assessment of the marine environment and to collect data to assess the current ecological status of marine waters including information as a base for revision of ecological targets established by the monitoring programme prepared in 2014 under Art. 11 of MSFD. Project activities are targeted to ensure data for Descriptors 5, 8 and 9. IMAMO aims to increase the institutional capacity of the Bulgarian partners related to the monitoring and assessment of the Black Sea environment. The main outputs are: establishment of real time monitoring and set up of accredited laboratory facilities for marine waters and sediments chemical analysis to ensure the ability of Bulgarian partners to monitor progress of subsequent measures undertaken.

  6. Leaf ontogeny and demography explain photosynthetic seasonality in Amazon evergreen forests

    Science.gov (United States)

    Wu, J.; Albert, L.; Lopes, A. P.; Restrepo-Coupe, N.; Hayek, M.; Wiedemann, K. T.; Guan, K.; Stark, S. C.; Prohaska, N.; Tavares, J. V.; Marostica, S. F.; Kobayashi, H.; Ferreira, M. L.; Campos, K.; Silva, R. D.; Brando, P. M.; Dye, D. G.; Huxman, T. E.; Huete, A. R.; Nelson, B. W.; Saleska, S. R.

    2015-12-01

    Photosynthetic seasonality couples the evolutionary ecology of plant leaves to large-scale rhythms of carbon and water exchanges that are important feedbacks to climate. However, the extent, magnitude, and controls on photosynthetic seasonality of carbon-rich tropical forests are poorly resolved, controversial in the remote sensing literature, and inadequately represented in most earth system models. Here we show that ecosystem-scale phenology (measured by photosynthetic capacity), rather than environmental seasonality, is the primary driver of photosynthetic seasonality at four Amazon evergreen forests spanning gradients in rainfall seasonality, forest composition, and flux seasonality. We further demonstrate that leaf ontogeny and demography explain most of this ecosystem phenology at two central Amazon evergreen forests, using a simple leaf-cohort canopy model that integrates eddy covariance-derived CO2 fluxes, novel near-surface camera-detected leaf phenology, and ground observations of litterfall and leaf physiology. The coordination of new leaf growth and old leaf divestment (litterfall) during the dry season shifts canopy composition towards younger leaves with higher photosynthetic efficiency, driving large seasonal increases (~27%) in ecosystem photosynthetic capacity. Leaf ontogeny and demography thus reconciles disparate observations of forest seasonality from leaves to eddy flux towers to satellites. Strategic incorporation of such whole-plant coordination processes as phenology and ontogeny will improve ecological, evolutionary and earth system theories describing tropical forests structure and function, allowing more accurate representation of forest dynamics and feedbacks to climate in earth system models.

  7. Evaluation of Protocols for Measuring Leaf Photosynthetic Properties of Field-Grown Rice

    Directory of Open Access Journals (Sweden)

    Chang Tian-gen

    2017-01-01

    Full Text Available Largely due to the heterogeneity of environmental parameters and the logistical difficulty of moving photosynthetic equipment in the paddy fields, effective measurement of lowland rice photosynthesis is still a challenge. In this study, we showed that measuring detached rice leaves in the laboratory can not effectively represent the parameters measured in situ. We further described a new indoor facility, high-efficiency all-weather photosynthetic measurement system (HAPS, and the associated measurement protocol to enable whole-weather measurement of photosynthetic parameters of rice grown in the paddy fields. Using HAPS, we can conduct photosynthetic measurements with a time span much longer than that appropriate for the outdoor measurements. Comparative study shows that photosynthetic parameters obtained with the new protocol can effectively represent the parameters in the fields. There was much less standard deviation for measurements using HAPS compared to the outdoor measurements, no matter for technical replications of each recording or for biological replications of each leaf position. This new facility and protocol enables rice photosynthetic physiology studies to be less tough but more efficient, and provides a potential option for large scale studies of rice leaf photosynthesis.

  8. Marine Polysaccharide Networks and Diatoms at the Nanometric Scale

    Directory of Open Access Journals (Sweden)

    Tea Mišić Radić

    2013-10-01

    Full Text Available Despite many advances in research on photosynthetic carbon fixation in marine diatoms, the biophysical and biochemical mechanisms of extracellular polysaccharide production remain significant challenges to be resolved at the molecular scale in order to proceed toward an understanding of their functions at the cellular level, as well as their interactions and fate in the ocean. This review covers studies of diatom extracellular polysaccharides using atomic force microscopy (AFM imaging and the quantification of physical forces. Following a brief summary of the basic principle of the AFM experiment and the first AFM studies of diatom extracellular polymeric substance (EPS, we focus on the detection of supramolecular structures in polysaccharide systems produced by marine diatoms. Extracellular polysaccharide fibrils, attached to the diatom cell wall or released into the surrounding seawater, form distinct supramolecular assemblies best described as gel networks. AFM makes characterization of the diatom polysaccharide networks at the micro and nanometric scales and a clear distinction between the self-assembly and self-organization of these complex systems in marine environments possible.

  9. The molecular ecophysiology of programmed cell death in marine phytoplankton.

    Science.gov (United States)

    Bidle, Kay D

    2015-01-01

    Planktonic, prokaryotic, and eukaryotic photoautotrophs (phytoplankton) share a diverse and ancient evolutionary history, during which time they have played key roles in regulating marine food webs, biogeochemical cycles, and Earth's climate. Because phytoplankton represent the basis of marine ecosystems, the manner in which they die critically determines the flow and fate of photosynthetically fixed organic matter (and associated elements), ultimately constraining upper-ocean biogeochemistry. Programmed cell death (PCD) and associated pathway genes, which are triggered by a variety of nutrient stressors and are employed by parasitic viruses, play an integral role in determining the cell fate of diverse photoautotrophs in the modern ocean. Indeed, these multifaceted death pathways continue to shape the success and evolutionary trajectory of diverse phytoplankton lineages at sea. Research over the past two decades has employed physiological, biochemical, and genetic techniques to provide a novel, comprehensive, mechanistic understanding of the factors controlling this key process. Here, I discuss the current understanding of the genetics, activation, and regulation of PCD pathways in marine model systems; how PCD evolved in unicellular photoautotrophs; how it mechanistically interfaces with viral infection pathways; how stress signals are sensed and transduced into cellular responses; and how novel molecular and biochemical tools are revealing the impact of PCD genes on the fate of natural phytoplankton assemblages.

  10. The Molecular Ecophysiology of Programmed Cell Death in Marine Phytoplankton

    Science.gov (United States)

    Bidle, Kay D.

    2015-01-01

    Planktonic, prokaryotic, and eukaryotic photoautotrophs (phytoplankton) share a diverse and ancient evolutionary history, during which time they have played key roles in regulating marine food webs, biogeochemical cycles, and Earth's climate. Because phytoplankton represent the basis of marine ecosystems, the manner in which they die critically determines the flow and fate of photosynthetically fixed organic matter (and associated elements), ultimately constraining upper-ocean biogeochemistry. Programmed cell death (PCD) and associated pathway genes, which are triggered by a variety of nutrient stressors and are employed by parasitic viruses, play an integral role in determining the cell fate of diverse photoautotrophs in the modern ocean. Indeed, these multifaceted death pathways continue to shape the success and evolutionary trajectory of diverse phytoplankton lineages at sea. Research over the past two decades has employed physiological, biochemical, and genetic techniques to provide a novel, comprehensive, mechanistic understanding of the factors controlling this key process. Here, I discuss the current understanding of the genetics, activation, and regulation of PCD pathways in marine model systems; how PCD evolved in unicellular photoautotrophs; how it mechanistically interfaces with viral infection pathways; how stress signals are sensed and transduced into cellular responses; and how novel molecular and biochemical tools are revealing the impact of PCD genes on the fate of natural phytoplankton assemblages.

  11. Boron uptake, localization, and speciation in marine brown algae.

    Science.gov (United States)

    Miller, Eric P; Wu, Youxian; Carrano, Carl J

    2016-02-01

    In contrast to the generally boron-poor terrestrial environment, the concentration of boron in the marine environment is relatively high (0.4 mM) and while there has been extensive interest in its use as a surrogate of pH in paleoclimate studies in the context of climate change-related questions, the relatively depth independent, and the generally non-nutrient-like concentration profile of this element have led to boron being neglected as a potentially biologically relevant element in the ocean. Among the marine plant-like organisms the brown algae (Phaeophyta) are one of only five lineages of photosynthetic eukaryotes to have evolved complex multicellularity. Many of unusual and often unique features of brown algae are attributable to this singular evolutionary history. These adaptations are a reflection of the marine coastal environment which brown algae dominate in terms of biomass. Consequently, brown algae are of fundamental importance to oceanic ecology, geochemistry, and coastal industry. Our results indicate that boron is taken up by a facilitated diffusion mechanism against a considerable concentration gradient. Furthermore, in both Ectocarpus and Macrocystis some boron is most likely bound to cell wall constituent alginate and the photoassimilate mannitol located in sieve cells. Herein, we describe boron uptake, speciation, localization and possible biological function in two species of brown algae, Macrocystis pyrifera and Ectocarpus siliculosus.

  12. Photosynthetically oxygenated salicylate biodegradation in a continuous stirred tank photobioreactor.

    Science.gov (United States)

    Muñoz, Raul; Köllner, Claudia; Guieysse, Benoit; Mattiasson, Bo

    2004-09-20

    A consortium consisting of a Chlorella sorokiniana strain and a Ralstonia basilensis strain was able to carry out sodium salicylate biodegradation in a continuous stirred tank reactor (CSTR) using exclusively photosynthetic oxygenation. Salicylate biodegradation depended on algal activity, which itself was a function of microalgal concentration, light intensity, and temperature. Biomass recirculation improved the photobioreactor performance by up to 44% but the results showed the existence of an optimal biomass concentration above which dark respiration started to occur and the process efficiency started to decline. The salicylate removal efficiency increased by a factor of 3 when illumination was increased from 50-300 microE/m2.s. In addition, the removal rate of sodium salicylate was shown to be temperature-dependent, increasing from 14 to 27 mg/l.h when the temperature was raised from 26.5 to 31.5 degrees C. Under optimized conditions (300 microE/m2.s, 30 degrees C, 1 g sodium salicylate/l in the feed and biomass recirculation) sodium salicylate was removed at a maximum constant rate of 87 mg/l.h, corresponding to an estimated oxygenation capacity of 77 mg O2/l.h (based on a BOD value of 0.88 g O2/g sodium salicylate for the tested bacterium), which is in the range of the oxygen transfer capacity of large-scale mechanical surface aerators. Thus, although higher degradation rates were attained in the control reactor, the photobioreactor is a cost-efficient process which reduces the cost of aeration and prevents volatilization problems associated with the degradation of toxic volatile organic compounds under aerobic conditions. Copyright 2004 Wiley Periodicals, Inc.

  13. Widespread positive selection in the photosynthetic Rubisco enzyme

    Directory of Open Access Journals (Sweden)

    Filatov Dmitry A

    2007-05-01

    Full Text Available Abstract Background Rubisco enzyme catalyzes the first step in net photosynthetic CO2 assimilation and photorespiratory carbon oxidation and is responsible for almost all carbon fixation on Earth. The large subunit of Rubisco is encoded by the chloroplast rbcL gene, which is widely used for reconstruction of plant phylogenies due to its conservative nature. Plant systematicists have mainly used rbcL paying little attention to its function, and the question whether it evolves under Darwinian selection has received little attention. The purpose of our study was to evaluate how common is positive selection in Rubisco among the phototrophs and where in the Rubisco structure does positive selection occur. Results We searched for positive selection in rbcL sequences from over 3000 species representing all lineages of green plants and some lineages of other phototrophs, such as brown and red algae, diatoms, euglenids and cyanobacteria. Our molecular phylogenetic analysis found the presence of positive selection in rbcL of most analyzed land plants, but not in algae and cyanobacteria. The mapping of the positively selected residues on the Rubisco tertiary structure revealed that they are located in regions important for dimer-dimer, intradimer, large subunit-small subunit and Rubisco-Rubisco activase interactions, and that some of the positively selected residues are close to the active site. Conclusion Our results demonstrate that despite its conservative nature, Rubisco evolves under positive selection in most lineages of land plants, and after billions of years of evolution Darwinian selection still fine-tunes its performance. Widespread positive selection in rbcL has to be taken into account when this gene is used for phylogenetic reconstructions.

  14. Evaluation of photosynthetic electrons derivation by exogenous redox mediators.

    Science.gov (United States)

    Longatte, Guillaume; Fu, Han-Yi; Buriez, Olivier; Labbé, Eric; Wollman, Francis-André; Amatore, Christian; Rappaport, Fabrice; Guille-Collignon, Manon; Lemaître, Frédéric

    2015-10-01

    Oxygenic photosynthesis is the complex process that occurs in plants or algae by which the energy from the sun is converted into an electrochemical potential that drives the assimilation of carbon dioxide and the synthesis of carbohydrates. Quinones belong to a family of species commonly found in key processes of the Living, like photosynthesis or respiration, in which they act as electron transporters. This makes this class of molecules a popular candidate for biofuel cell and bioenergy applications insofar as they can be used as cargo to ship electrons to an electrode immersed in the cellular suspension. Nevertheless, such electron carriers are mostly selected empirically. This is why we report on a method involving fluorescence measurements to estimate the ability of seven different quinones to accept photosynthetic electrons downstream of photosystem II, the first protein complex in the light-dependent reactions of oxygenic photosynthesis. To this aim we use a mutant of Chlamydomonas reinhardtii, a unicellular green alga, impaired in electron downstream of photosystem II and assess the ability of quinones to restore electron flow by fluorescence. In this work, we defined and extracted a "derivation parameter" D that indicates the derivation efficiency of the exogenous quinones investigated. D then allows electing 2,6-dichlorobenzoquinone, 2,5-dichlorobenzoquinone and p-phenylbenzoquinone as good candidates. More particularly, our investigations suggested that other key parameters like the partition of quinones between different cellular compartments and their propensity to saturate these various compartments should also be taken into account in the process of selecting exogenous quinones for the purpose of deriving photoelectrons from intact algae. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Elementary Energy Transfer Pathways in Allochromatium vinosum Photosynthetic Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Lüer, Larry; Carey, Anne-Marie; Henry, Sarah; Maiuri, Margherita; Hacking, Kirsty; Polli, Dario; Cerullo, Giulio; Cogdell, Richard J.

    2015-11-01

    Allochromatium vinosum (formerly Chromatium vinosum) purple bacteria are known to adapt their light-harvesting strategy during growth according to environmental factors such as temperature and average light intensity. Under low light illumination or low ambient temperature conditions, most of the LH2 complexes in the photosynthetic membranes form a B820 exciton with reduced spectral overlap with LH1. To elucidate the reason for this light and temperature adaptation of the LH2 electronic structure, we performed broadband femtosecond transient absorption spectroscopy as a function of excitation wavelength in A. vinosum membranes. A target analysis of the acquired data yielded individual rate constants for all relevant elementary energy transfer (ET) processes. We found that the ET dynamics in high-light-grown membranes was well described by a homogeneous model, with forward and backward rate constants independent of the pump wavelength. Thus, the overall B800→B850→B890→ Reaction Center ET cascade is well described by simple triexponential kinetics. In the low-light-grown membranes, we found that the elementary backward transfer rate constant from B890 to B820 was strongly reduced compared with the corresponding constant from B890 to B850 in high-light-grown samples. The ET dynamics of low-light-grown membranes was strongly dependent on the pump wavelength, clearly showing that the excitation memory is not lost throughout the exciton lifetime. The observed pump energy dependence of the forward and backward ET rate constants suggests exciton diffusion via B850→ B850 transfer steps, making the overall ET dynamics nonexponential. Our results show that disorder plays a crucial role in our understanding of low-light adaptation in A. vinosum.

  16. Elementary Energy Transfer Pathways in Allochromatium vinosum Photosynthetic Membranes

    Science.gov (United States)

    Lüer, Larry; Carey, Anne-Marie; Henry, Sarah; Maiuri, Margherita; Hacking, Kirsty; Polli, Dario; Cerullo, Giulio; Cogdell, Richard J.

    2015-01-01

    Allochromatium vinosum (formerly Chromatium vinosum) purple bacteria are known to adapt their light-harvesting strategy during growth according to environmental factors such as temperature and average light intensity. Under low light illumination or low ambient temperature conditions, most of the LH2 complexes in the photosynthetic membranes form a B820 exciton with reduced spectral overlap with LH1. To elucidate the reason for this light and temperature adaptation of the LH2 electronic structure, we performed broadband femtosecond transient absorption spectroscopy as a function of excitation wavelength in A. vinosum membranes. A target analysis of the acquired data yielded individual rate constants for all relevant elementary energy transfer (ET) processes. We found that the ET dynamics in high-light-grown membranes was well described by a homogeneous model, with forward and backward rate constants independent of the pump wavelength. Thus, the overall B800→B850→B890→ Reaction Center ET cascade is well described by simple triexponential kinetics. In the low-light-grown membranes, we found that the elementary backward transfer rate constant from B890 to B820 was strongly reduced compared with the corresponding constant from B890 to B850 in high-light-grown samples. The ET dynamics of low-light-grown membranes was strongly dependent on the pump wavelength, clearly showing that the excitation memory is not lost throughout the exciton lifetime. The observed pump energy dependence of the forward and backward ET rate constants suggests exciton diffusion via B850→ B850 transfer steps, making the overall ET dynamics nonexponential. Our results show that disorder plays a crucial role in our understanding of low-light adaptation in A. vinosum. PMID:26536265

  17. Photonic multilayer structure of Begonia chloroplasts enhances photosynthetic efficiency.

    Science.gov (United States)

    Jacobs, Matthew; Lopez-Garcia, Martin; Phrathep, O-Phart; Lawson, Tracy; Oulton, Ruth; Whitney, Heather M

    2016-10-24

    Enhanced light harvesting is an area of interest for optimizing both natural photosynthesis and artificial solar energy capture1,2. Iridescence has been shown to exist widely and in diverse forms in plants and other photosynthetic organisms and symbioses3,4, but there has yet to be any direct link demonstrated between iridescence and photosynthesis. Here we show that epidermal chloroplasts, also known as iridoplasts, in shade-dwelling species of Begonia5, notable for their brilliant blue iridescence, have a photonic crystal structure formed from a periodic arrangement of the light-absorbing thylakoid tissue itself. This structure enhances photosynthesis in two ways: by increasing light capture at the predominantly green wavelengths available in shade conditions, and by directly enhancing quantum yield by 5-10% under low-light conditions. These findings together imply that the iridoplast is a highly modified chloroplast structure adapted to make best use of the extremely low-light conditions in the tropical forest understorey in which it is found5,6. A phylogenetically diverse range of shade-dwelling plant species has been found to produce similarly structured chloroplasts7-9, suggesting that the ability to produce chloroplasts whose membranes are organized as a multilayer with photonic properties may be widespread. In fact, given the well-established diversity and plasticity of chloroplasts10,11, our results imply that photonic effects may be important even in plants that do not show any obvious signs of iridescence to the naked eye but where a highly ordered chloroplast structure may present a clear blue reflectance at the microscale. Chloroplasts are generally thought of as purely photochemical; we suggest that one should also think of them as a photonic structure with a complex interplay between control of light propagation, light capture and photochemistry.

  18. Mutualistic damselfish induce higher photosynthetic rates in their host coral.

    Science.gov (United States)

    Garcia-Herrera, Nur; Ferse, Sebastian C A; Kunzmann, Andreas; Genin, Amatzia

    2017-05-15

    Coral reefs are amongst the most diverse ecosystems on Earth where complex inter-specific interactions are ubiquitous. An example of such interactions is the mutualistic relationship between damselfishes and branching corals in the Northern Red Sea, where the fish use corals as shelter and provide them with nutrients, enhance the flow between their branches, and protect them from predators. By enhancing the flow between the coral branches, the fish ventilate the coral's inner zone, mitigating hypoxic conditions that otherwise develop within that zone during the night. Here, we tested, for the first time, the effects of the damselfish Dascyllus marginatus on photosynthesis and respiration in its host coral Stylophora pistillata Laboratory experiments using an intermittent-flow respirometer showed that the presence of fish between the coral branches under light conditions augmented the coral's photosynthetic rate. No effect on the coral's respiration was found under dark conditions. When a fish was allowed to enter the inner zone of a dead coral skeleton, its respiration was higher than when it was in a live coral. Field observations indicated that damselfish were present between coral branches 18-34% of the time during daylight hours and at all times during the night. Considering the changes induced by the fish together with the proportion of time they were found between coral branches in the field, the effect of the fish amounted to an augmentation of 3-6% of the coral's daily photosynthesis. Our findings reveal a previously unknown positive contribution of coral-dwelling fish to their host's photosynthesis. © 2017. Published by The Company of Biologists Ltd.

  19. Exploring Marine Cyanobacteria for Lead Compounds of Pharmaceutical Importance

    Directory of Open Access Journals (Sweden)

    Bushra Uzair

    2012-01-01

    Full Text Available The Ocean, which is called the “mother of origin of life,” is also the source of structurally unique natural products that are mainly accumulated in living organisms. Cyanobacteria are photosynthetic prokaryotes used as food by humans. They are excellent source of vitamins and proteins vital for life. Several of these compounds show pharmacological activities and are helpful for the invention and discovery of bioactive compounds, primarily for deadly diseases like cancer, acquired immunodeficiency syndrome (AIDS, arthritis, and so forth, while other compounds have been developed as analgesics or to treat inflammation, and so forth. They produce a large variety of bioactive compounds, including substances with anticancer and antiviral activity, UV protectants, specific inhibitors of enzymes, and potent hepatotoxins and neurotoxins. Many cyanobacteria produce compounds with potent biological activities. This paper aims to showcase the structural diversity of marine cyanobacterial secondary metabolites with a comprehensive coverage of alkaloids and other applications of cyanobacteria.

  20. A limited legacy effect of copper in marine biofilms.

    Science.gov (United States)

    McElroy, David J; Doblin, Martina A; Murphy, Richard J; Hochuli, Dieter F; Coleman, Ross A

    2016-08-15

    The effects of confounding by temporal factors remains understudied in pollution ecology. For example, there is little understanding of how disturbance history affects the development of assemblages. To begin addressing this gap in knowledge, marine biofilms were subjected to temporally-variable regimes of copper exposure and depuration. It was expected that the physical and biological structure of the biofilms would vary in response to copper regime. Biofilms were examined by inductively coupled plasma optical emission spectrometry, chlorophyll-a fluorescence and field spectrometry and it was found that (1) concentrations of copper were higher in those biofilms exposed to copper, (2) concentrations of copper remain high in biofilms after the source of copper is removed, and (3) exposure to and depuration from copper might have comparable effects on the photosynthetic microbial assemblages in biofilms. The persistence of copper in biofilms after depuration reinforces the need for consideration of temporal factors in ecology. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. A Marine Traffic Flow Model

    Directory of Open Access Journals (Sweden)

    Tsz Leung Yip

    2013-03-01

    Full Text Available A model is developed for studying marine traffic flow through classical traffic flow theories, which can provide us with a better understanding of the phenomenon of traffic flow of ships. On one hand, marine traffic has its special features and is fundamentally different from highway, air and pedestrian traffic. The existing traffic models cannot be simply extended to marine traffic without addressing marine traffic features. On the other hand, existing literature on marine traffic focuses on one ship or two ships but does not address the issues in marine traffic flow.

  2. Marine Aerosols and Clouds.

    Science.gov (United States)

    Brooks, Sarah D; Thornton, Daniel C O

    2017-10-13

    The role of marine bioaerosols in cloud formation and climate is currently so uncertain that even the sign of the climate forcing is unclear. Marine aerosols form through direct emissions and through the conversion of gasphase emissions to aerosols in the atmosphere. The composition and size of aerosols determine how effective they are in catalyzing the formation of water droplets and ice crystals in clouds by acting as cloud condensation nuclei and ice nucleating particles, respectively. Marine organic aerosols may be sourced both from recent regional phytoplankton blooms that add labile organic matter to the surface ocean and from long-term global processes, such as the upwelling of old refractory dissolved organic matter from the deep ocean. Understanding the formation of marine aerosols and their propensity to catalyze cloud formation processes are challenges that must be addressed given the major uncertainties associated with aerosols in climate models. Expected final online publication date for the Annual Review of Marine Science Volume 10 is January 3, 2018. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

  3. Older Thinopyrum intermedium (Poaceae) plants exhibit superior photosynthetic tolerance to cold stress and greater increases in two photosynthetic enzymes under freezing stress compared with young plants.

    Science.gov (United States)

    Jaikumar, Nikhil S; Snapp, Sieglinde S; Sharkey, Thomas D

    2016-08-01

    Effects of plant age on resource acquisition and stress tolerance processes is a largely unstudied subject in herbaceous perennials. In a field experiment, we compared rates of photosynthesis (A), ribulose-1,5-bisphosphate (RuBP) carboxylation capacity (V Cmax), maximum electron transport rate (J max), and triose phosphate utilization (TPU), as well as concentrations of Rubisco and sucrose-phosphate synthase (SPS) in 5-year-old and 2-year-old intermediate wheatgrass (Thinopyrum intermedium) under both optimal growing conditions and cold stress in early spring and autumn. This species is a relative of wheat undergoing domestication. An additional experiment compared photosynthetic rates in different cohorts at mid-season and under colder conditions. We hypothesized that photosynthetic capacity in older plants would be lower under favorable conditions but higher under cold stress. Our hypothesis was generally supported. Under cold stress, 5-year-old plants exhibited higher A, TPU, and temperature-adjusted V Cmax than younger plants, as well as 50% more SPS and 37% more Rubisco. In contrast, at mid-season, photosynthetic capacities in older plants were lower than in younger plants in one experiment, and similar in the other, independent of differences in water status. Both cohorts increased A, temperature-adjusted TPU and J max, [Rubisco], and [SPS] under cold stress, but changes were greater in older plants. Photosynthetic differences were largest at 1.2 ºC in very early spring, where older plants had 200% higher A and maintained up to 17% of their peak photosynthetic capacity. We find evidence of increased cold tolerance in older cohorts of wheatgrass, consistent with a growing body of research in woody perennials. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  4. Triclosan causes toxic effects to algae in marine biofilms, but does not inhibit the metabolic activity of marine biofilm bacteria.

    Science.gov (United States)

    Johansson, C Henrik; Janmar, Lisa; Backhaus, Thomas

    2014-07-15

    Effects of the antimicrobial agent triclosan to natural periphyton communities (biofilms, comprising primarily microalgae and bacteria) were assessed in two independent experiments during spring and summer. For that purpose a semi-static test system was used in which periphyton was exposed to a concentration range of 5-9054 nmol/L triclosan. Effects on algae were analyzed as content and composition of photosynthetic pigments. The corresponding EC50 values were 39.25 and 302.45 nmol/L for the spring and summer experiment, respectively. Effects on periphytic bacteria were assessed as effects on carbon utilization patterns, using Biolog Ecoplates. No inhibition of either total carbon utilization or functional diversity was observed, indicating a pronounced triclosan tolerance of the marine bacteria. In contrast, a small stimulation of the total carbon utilization was observed at triclosan concentrations exceeding 100 nmol/L. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. Chemical composition and photosynthetically active radiation of forage grasses under irrigation

    Directory of Open Access Journals (Sweden)

    Edilane Aparecida da Silva

    2012-03-01

    Full Text Available The present study aimed to estimate the photosynthetically active radiation of tropical forage grasses in ten cutting dates, under irrigation. The following treatments were used: Brachiaria decumbens grass (Brachiaria decumbens cultivar Basilisk, Marandu grass (Brachiaria brizantha cultivar Marandu, Xaraes grass (Brachiaria brizantha, cultivar Xaraes, Mombaça grass (Panicum maximum cultivar Mombaça, Tanzania grass (Panicum maximum, cultivar Tanzania and Tifton 85 grass (Cynodon spp cultivar Tifton 85. The weather parameters were collected by an automatic meteorological station installed in the location and used for irrigation management. The experiment was arranged in a split-plot completely randomized block design, considering the grasses as plots and cutting seasons as subplots, with four replications in a 6 × 10 factorial arrangement, six grasses and ten cutting seasons. The results indicated increased use of photosynthetically active radiation in the wet season, in relation to the dry-wet season transition. Basilisk presented the highest values of photosynthetically active radiation (1,648.9 mE. The variables studied were affected by photosynthetically active radiation. The grass cultivars presented different light interceptions. The values of 87; 90; 90; 88; 92 and 77% were found for grass cultivars Basilisk, Marandu, Mombaça, Tanzania, Xaraes and Tifton 85, respectively. Differences were observed in forage accumulation rates for the grass plants studied. The grasses with the best productive performance were Brachiaria decumbens cultivar Basilisk and B. brizantha cultivar Xaraes. The highest values of crude protein and neutral detergent fiber were observed for Tifton 85. The use of photosynthetically active radiation was different among the grasses evaluated. There is a positive association between photosynthetically active radiation and dry matter production. Besides, photosynthetically active radiation indirectly affects crude protein

  6. Toward Describing the Effects of Ozone Depletion on Marine Primary Productivity and Carbon Cycling

    Science.gov (United States)

    Cullen, John J.

    1995-01-01

    This project was aimed at improved predictions of the effects of UVB and ozone depletion on marine primary productivity and carbon flux. A principal objective was to incorporate a new analytical description of photosynthesis as a function of UV and photosynthetically available radiation (Cullen et. al., Science 258:646) into a general oceanographic model. We made significant progress: new insights into the kinetics of photoinhibition were used in the analysis of experiments on Antarctic phytoplankton to generate a general model of UV-induced photoinhibition under the influence of ozone depletion and vertical mixing. The way has been paved for general models on a global scale.

  7. Modelling light and photosynthesis in the marine environment

    Directory of Open Access Journals (Sweden)

    Bogdan Woźniak

    2003-06-01

    Full Text Available The overriding and far-reaching aim of our work has been to achieve a good understanding of the processes of light interaction with phytoplankton in the sea and to develop an innovative physical model of photosynthesis in the marine environment, suitable for the remote sensin gof marine primary production. Unlike previous models, the present one takesgreater account of the complexity of the physiological processes in phytoplankton. We have focused in particular on photophysiological processes, which are governed directly or indirectly by light energy, or in which light, besides the nutrient content in and the temperature of seawater, is one of the principal limiting factors.    To achieve this aim we have carried out comprehensive statistical analyses of the natural variability of the main photophysiological properties of phytoplankton and their links with the principal abiotic factors in the sea. These analyses have made use of extensive empirical data gathered in a wide diversity of seas and oceans by Polish and Russian teams as well as by joint Polish-Russian expeditions. Data sets available on the Internet have also been applied. As a result, a set of more or less complex, semi-empirical models of light-stimulated processes occurring in marine phytoplankton cells has been developed. The trophic type of sea, photo-acclimation and the production of photoprotecting carotenoids, chromatic acclimation and the production of various forms of chlorophyll-antennas and photosynthetic carotenoids, cell adaptation by the package effect, light absorption, photosynthesis, photoinhibition, the fluorescence effect, and the activation of PS2 centres are all considered in the models. These take into account not only the influence of light, but also, indirectly, that of the vertical mixing of water; in the case of photosynthesis, the quantum yield has been also formulated as being dependent on the nutrient concentrations and the temperature of seawater

  8. The marine diversity spectrum

    DEFF Research Database (Denmark)

    Reuman, Daniel C.; Gislason, Henrik; Barnes, Carolyn

    2014-01-01

    of taxonomy (all the species in a region regardless of clade) are much less studied but are equally important and will illuminate a different set of ecological and evolutionary processes. We develop and test a mechanistic model of how diversity varies with body mass in marine ecosystems. The model predicts...... the form of the diversity spectrum', which quantifies the distribution of species' asymptotic body masses, is a species analogue of the classic size spectrum of individuals, and which we have found to be a new and widely applicable description of diversity patterns. The marine diversity spectrum...... is predicted to be approximately linear across an asymptotic mass range spanning seven orders of magnitude. Slope -0 center dot 5 is predicted for the global marine diversity spectrum for all combined pelagic zones of continental shelf seas, and slopes for large regions are predicted to lie between -0 center...

  9. Marine-Design Education

    DEFF Research Database (Denmark)

    Andersen, Poul; Birmingham, R.; Sortland, B.

    2006-01-01

    This report addresses Marine-Design Education in view of present and forecasted demands of the maritime industry, determined by a drastically transforming economic and technological maritime environment. In this framework, this report discusses in depth IT-based Marine Design education (par. 4......) and reveals innovative educational concepts and initiatives, such as the EiT (Experts in a Team) concept (par. 3), the SFS (Student Friendly Software) initiative (par. 5), Education Driven Research (EDR, par. 6) and Research Based Education (RBE, par. 6). Nevertheless, the paper stresses the need...... for continuity between traditional and modern ways of teaching (par. 4) and points out that Marine Design education is not only about Design, but should also address project/business administration and decision making issues (par. 7)....

  10. Marine Mineral Exploration

    DEFF Research Database (Denmark)

    resources was negotiated by the United Nations Conference on the Law of the Sea (UNCLOS III). A most important outcome of this conference was the establishment of an Exclusive Economic Zone (EEZ) of at least 200 nautical miles for all coastal states and the recognition of a deep-sea regime. Mineral deposits......The past 20 years have seen extensive marine exploration work by the major industrialized countries. Studies have, in part, been concentrated on Pacific manganese nodule occurrences and on massive sulfides on mid-oceanic ridges. An international jurisdictional framework of the sea-bed mineral...... in EEZ areas are fairly unknown; many areas need detailed mapping and mineral exploration, and the majority of coastal or island states with large EEZ areas have little experience in exploration for marine hard minerals. This book describes the systematic steps in marine mineral exploration...

  11. Marine natural products.

    Science.gov (United States)

    Blunt, John W; Copp, Brent R; Hu, Wan-Ping; Munro, Murray H G; Northcote, Peter T; Prinsep, Michèle R

    2009-02-01

    This review covers the literature published in 2007 for marine natural products, with 948 citations(627 for the period January to December 2007) referring to compounds isolated from marine microorganisms and phytoplankton, green algae, brown algae, red algae, sponges, cnidarians,bryozoans, molluscs, tunicates, echinoderms and true mangrove plants. The emphasis is on new compounds (961 for 2007), together with the relevant biological activities, source organisms and country of origin. Biosynthetic studies, first syntheses, and syntheses that lead to the revision of structures or stereochemistries, have been included.1 Introduction, 2 Reviews, 3 Marine microorganisms and phytoplankton, 4 Green algae, 5 Brown algae, 6 Red algae, 7 Sponges, 8 Cnidarians, 9 Bryozoans, 10 Molluscs, 11 Tunicates (ascidians),12 Echinoderms, 13 Miscellaneous, 14 Conclusion, 15 References.

  12. PHYLOGENETIC SIGNIFICANCE OF THE LIMITED DISTRIBUTION OF OCTADECAPENTAENOIC ACID IN PRYMNESIOPHYTES AND PHOTOSYNTHETIC DINOFLAGELLATES (14th Symposium on Polar Biology)

    OpenAIRE

    オクヤマ, ヒデトシ; コガメ, カズヒロ; タケダ, シゲノブ; Hidetoshi, Okuyama; Kazuhiro, KOGAME; Shigenobu, Takeda

    1993-01-01

    Fatty acid composition of lipids from two strains of prymnesiophytes, seven strains of photosynthetic dinoflagellates, one strain of non-photosynthetic dinoflagellates and two strains of cryptomonads was examined with special emphasis on the presence or the absence of an octadecapentaenoic acid [18:5(n-3)]. Prymnesiophytes (Emiliania huxleyi and Gephyrocapsa oceanicd) and photosynthetic dinoflagellates [Amphidinium carterae, Prorocentrum micans, Protoceratiwn reticulatum, Pyrocystis lunula, S...

  13. 75 FR 19670 - Marine Highway Projects

    Science.gov (United States)

    2010-04-15

    ... No: 2010-8619] DEPARTMENT OF TRANSPORTATION Maritime Administration Marine Highway Projects ACTION: Solicitation of applications for Marine highway projects. SUMMARY: The Department of Transportation is soliciting applications for Marine Highway Projects as specified in the America's Marine Highway Program...

  14. New Waves in Marine Science Symposium: Marine Animal Communication.

    Science.gov (United States)

    Allen, Betty, Comp.

    1989-01-01

    Presented are the abstracts from three research projects on marine social systems which were a part of a marine science symposium. Five sets of activities on marine animal communication are included, one each for grades K-2, 3-5, 6-8 and 9-12, and informal education. (CW)

  15. Faunistics (marine animals)

    DEFF Research Database (Denmark)

    2003-01-01

    These PowerPoint files are compiled from various sources: Internet, field guides, scientific monographs, textbooks, my own photos and drawings, etc. I have no copyright or permission to use most of the illustrations. The file is therefore only intended for internal use within the Marine Biology......) with the programme PowerPoint X for Mac® Service Release 1.     Comments and suggestions are welcome from students and colleagues. HD&P = Køie, Kristiansen & Weitemeyer, Havets dyr og planter. DN = Danmarks Natur, vol. 3, Havet     Tomas Cedhagen, Department of Marine Ecology, University of Aarhus, Finlandsgade 14...

  16. Transmission and Distribution of Photosynthetically Active Radiation (PAR) for Biomass Production in Exploration Missions [7226-270] Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Physical Sciences Inc. (PSI) proposes to develop a plant lighting system which collects, transmits and distributes photosynthetically active radiation (PAR) for...

  17. The biology of marine plants

    National Research Council Canada - National Science Library

    Dring, M.J

    1982-01-01

    Since over 90% of the species of marine plants are algae, most of the book is devoted to the marine representatives of this group, with examples from all oceans and coasts of the world where detailed work has been done...

  18. Bioactive alkaloids from marine sponges

    Digital Repository Service at National Institute of Oceanography (India)

    Singh, K.S.; Majik, M.S.

    of the molecules obtained from marine sponges have entered in market, while many are under clinical and preclinical trials. There is convincing report about the role of ecology on the production of these valuable secondary metabolites by marine organisms including...

  19. The Danish Marine Monitoring System

    DEFF Research Database (Denmark)

    Ærtebjerg, G.

    1997-01-01

    Indeholder abstracts fra Workshop on Marine Monitoring Systems and Technology, Risø, 17-18 April 1996.......Indeholder abstracts fra Workshop on Marine Monitoring Systems and Technology, Risø, 17-18 April 1996....

  20. Empowering marine science through genomics

    NARCIS (Netherlands)

    Volckaert, F.A M J; Barbier, M.; Canario, A; Olsen, J.L.; Wesnigk, J; Clark, M; Boyen, C

    Marine scientists in Europe summarize their successes with genome technologies in the marine sciences and make a plea for a concerted international effort to raise greater public education for support. (C) 2008 Elsevier B.V. All rights reserved.

  1. 75 FR 76399 - Marine Mammals

    Science.gov (United States)

    2010-12-08

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration RIN 0648-XZ66 Marine Mammals AGENCY: National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Commerce. ACTION: Notice; receipt of...

  2. Photosynthetic response to fluctuating environments and photoprotective strategies under abiotic stress.

    Science.gov (United States)

    Yamori, Wataru

    2016-05-01

    Plants in natural environments must cope with diverse, highly dynamic, and unpredictable conditions. They have mechanisms to enhance the capture of light energy when light intensity is low, but they can also slow down photosynthetic electron transport to prevent the production of reactive oxygen species and consequent damage to the photosynthetic machinery under excess light. Plants need a highly responsive regulatory system to balance the photosynthetic light reactions with downstream metabolism. Various mechanisms of regulation of photosynthetic electron transport under stress have been proposed, however the data have been obtained mainly under environmentally stable and controlled conditions. Thus, our understanding of dynamic modulation of photosynthesis under dramatically fluctuating natural environments remains limited. In this review, first I describe the magnitude of environmental fluctuations under natural conditions. Next, I examine the effects of fluctuations in light intensity, CO2 concentration, leaf temperature, and relative humidity on dynamic photosynthesis. Finally, I summarize photoprotective strategies that allow plants to maintain the photosynthesis under stressful fluctuating environments. The present work clearly showed that fluctuation in various environmental factors resulted in reductions in photosynthetic rate in a stepwise manner at every environmental fluctuation, leading to the conclusion that fluctuating environments would have a large impact on photosynthesis.

  3. Role of an elliptical structure in photosynthetic energy transfer: Collaboration between quantum entanglement and thermal fluctuation.

    Science.gov (United States)

    Oka, Hisaki

    2016-05-13

    Recent experiments have revealed that the light-harvesting complex 1 (LH1) in purple photosynthetic bacteria has an elliptical structure. Generally, symmetry lowering in a structure leads to a decrease in quantum effects (quantum coherence and entanglement), which have recently been considered to play a role in photosynthetic energy transfer, and hence, elliptical structure seems to work against efficient photosynthetic energy transfer. Here we analyse the effect of an elliptical structure on energy transfer in a purple photosynthetic bacterium and reveal that the elliptical distortion rather enhances energy transfer from peripheral LH2 to LH1 at room temperature. Numerical results show that quantum entanglement between LH1 and LH2 is formed over a wider range of high energy levels than would have been the case with circular LH1. Light energy absorbed by LH2 is thermally pumped via thermal fluctuation and is effectively transferred to LH1 through the entangled states at room temperature rather than at low temperature. This result indicates the possibility that photosynthetic systems adopt an elliptical structure to effectively utilise both quantum entanglement and thermal fluctuation at physiological temperature.

  4. Features of the photosynthetic tissue in the sheaths of rice (Oryza sativa L.)

    Science.gov (United States)

    Guo, Zhao Wu; He, Qiang; Feng, Deng Hua

    The photosynthesis of rice sheath plays a significant role to furnish rice yield, and it is accounted for 10 to 20% of the final yield. But, limited studies have been done to address this phenomenon and to characterize the features of the photosynthetic tissue in rice sheath. In this paper, a super hybrid rice and a hybrid rice were studied as the experimental materials, and the characteristics of the photosynthetic tissue in rice sheaths were examined by microscopic and super-microscopic observation. The results showed that the photosynthetic tissue of rice sheath was rich in the intact mesophyllous cells full of chloroplasts, grana and thylakoids, which were much the same as those of rice blade. The stomatal density in the outer epidermises of the sheaths was comparable to those in the up- and down-epidermises of the blades. The mesophyllous cells in the sheaths were also rich in chlorophylls, and had the net photosynthetic rate (Pn). Therefore, rice sheath was also full of the intact photosynthetic apparatus similar to those in rice blade, and had capabilities of photosynthesis.

  5. Mycorrhiza symbiosis increases the surface for sunlight capture in Medicago truncatula for better photosynthetic production.

    Directory of Open Access Journals (Sweden)

    Lisa Adolfsson

    Full Text Available Arbuscular mycorrhizal (AM fungi play a prominent role in plant nutrition by supplying mineral nutrients, particularly inorganic phosphate (Pi, and also constitute an important carbon sink. AM stimulates plant growth and development, but the underlying mechanisms are not well understood. In this study, Medicago truncatula plants were grown with Rhizophagus irregularis BEG141 inoculum (AM, mock inoculum (control or with P(i fertilization. We hypothesized that AM stimulates plant growth through either modifications of leaf anatomy or photosynthetic activity per leaf area. We investigated whether these effects are shared with P(i fertilization, and also assessed the relationship between levels of AM colonization and these effects. We found that increased P(i supply by either mycorrhization or fertilization led to improved shoot growth associated with increased nitrogen uptake and carbon assimilation. Both mycorrhized and P(i-fertilized plants had more and longer branches with larger and thicker leaves than the control plants, resulting in an increased photosynthetically active area. AM-specific effects were earlier appearance of the first growth axes and increased number of chloroplasts per cell section, since they were not induced by P(i fertilization. Photosynthetic activity per leaf area remained the same regardless of type of treatment. In conclusion, the increase in growth of mycorrhized and P(i-fertilized Medicago truncatula plants is linked to an increase in the surface for sunlight capture, hence increasing their photosynthetic production, rather than to an increase in the photosynthetic activity per leaf area.

  6. Mycorrhiza Symbiosis Increases the Surface for Sunlight Capture in Medicago truncatula for Better Photosynthetic Production

    Science.gov (United States)

    Adolfsson, Lisa; Keresztes, Áron; Uddling, Johan; Schoefs, Benoît; Spetea, Cornelia

    2015-01-01

    Arbuscular mycorrhizal (AM) fungi play a prominent role in plant nutrition by supplying mineral nutrients, particularly inorganic phosphate (Pi), and also constitute an important carbon sink. AM stimulates plant growth and development, but the underlying mechanisms are not well understood. In this study, Medicago truncatula plants were grown with Rhizophagus irregularis BEG141 inoculum (AM), mock inoculum (control) or with Pi fertilization. We hypothesized that AM stimulates plant growth through either modifications of leaf anatomy or photosynthetic activity per leaf area. We investigated whether these effects are shared with Pi fertilization, and also assessed the relationship between levels of AM colonization and these effects. We found that increased Pi supply by either mycorrhization or fertilization led to improved shoot growth associated with increased nitrogen uptake and carbon assimilation. Both mycorrhized and Pi-fertilized plants had more and longer branches with larger and thicker leaves than the control plants, resulting in an increased photosynthetically active area. AM-specific effects were earlier appearance of the first growth axes and increased number of chloroplasts per cell section, since they were not induced by Pi fertilization. Photosynthetic activity per leaf area remained the same regardless of type of treatment. In conclusion, the increase in growth of mycorrhized and Pi-fertilized Medicago truncatula plants is linked to an increase in the surface for sunlight capture, hence increasing their photosynthetic production, rather than to an increase in the photosynthetic activity per leaf area. PMID:25615871

  7. Carbon Concentrating Mechanisms & C4 Enzymes In Marine Phytoplankton

    Science.gov (United States)

    Moolna, A.; Hermoso, M.; Rickaby, R.

    2009-12-01

    Photosynthetic CO2 assimilation by marine phytoplankton is a major sink in the Earth’s carbon cycle. Understanding the molecular biogeochemistry of this carbon capture is crucial to predicting how the Earth will respond to the carbon emissions driving human-induced climate change. We are investigating the connection of phytoplankton photosynthesis to different CO2 levels using the diatom Thalassiosira weissflogii and the coccolithophores Emiliania huxleyi and Gephyrocapsa oceanica. Phytoplankton in equilibrium with present-day atmospheric CO2 levels have carbon concentrating mechanisms (CCMs) that increase their internal concentration of dissolved inorganic carbon (DIC) relative to their surrounding seawater. By acclimating cultures to seawater with quadrupled DIC availability, the CCM physiology is relaxed. This is demonstrated by resuspending the phytoplankton in CO2-free seawater and then plotting the response curve of photosynthetic O2 evolution rate against the addition of specific concentrations of DIC (Figure 1). Relaxation implies less energy used for CCMs and so more energy may be available for carbon fixation. Scanning electron micrographs of high DIC G. oceanica cultures, for example, show that the size of both the coccosphere and of individual coccoliths is unchanged; but the external shield of the coccolith extends further into the central area. This suggests an increase in calcification, with implications for carbon partition between organic and inorganic fluxes to the seafloor. Of particular interest is the possibility that C4 photosynthesis could provide a CCM for marine phytoplankton. The carbon-fixing Rubisco enzyme can only use CO2 as a substrate but, due to reaction between CO2 and H2O, most of the CO2 dissolved in seawater is actually present as HCO3-. In C4 land plants, CO2 for Rubisco is provided via a four-carbon intermediate compound generated from HCO3-; and the basic C4 machinery is found in all photosynthetic life because of

  8. Using the marine unicellular algae in biological monitoring

    Directory of Open Access Journals (Sweden)

    Kapkov V. I.

    2017-06-01

    Full Text Available The possibility of using marine unicellular algae from natural plankton community in biomonitoring of pollution by heavy metals has been investigated. Algae of different taxa from the Mediterranean Sea have been allocated to culture. In the laboratory the culture conditions – i. e. growth medium, temperature, photoperiod, level of artificial light and initial density – have been selected for every species. The impact of heavy metals (Hg, Cd, Cu, Pb in the form of chloride salts on the growth of axenic algae culture has been studied in the modelling experiments. The unicellular marine algae have a very short life cycle, therefore it is possible to use them in the experiments of studying the effect of anthropogenic factors at cellular and population levels on the test-object. With biomonitoring pollution of marine environment by heavy metals and others dangerous toxicants, the major indicators of algae community condition are the cellular cycle and the condition of the photosynthetic apparatus of the cell. The subsequent lysis of cells under the influence of heavy metals leads to the excretion of secondary metabolites which can essentially affect the metal toxicity. The established scales of threshold and lethal concentration of heavy metals for algae of different taxon make it possible to use the ratio of sensitive and resistant species to heavy metals as biological markers when forecasting ecological consequences of pollution of the marine environment by heavy metals. Distinctions in the resistance of different taxon to heavy metals can result in implementing the strategy of selection of test-objects depending on the purposes of the research.

  9. Integrative species delimitation in photosynthetic sea slugs reveals twenty candidate species in three nominal taxa studied for drug discovery, plastid symbiosis or biological control.

    Science.gov (United States)

    Krug, Patrick J; Vendetti, Jann E; Rodriguez, Albert K; Retana, Jennifer N; Hirano, Yayoi M; Trowbridge, Cynthia D

    2013-12-01

    DNA barcoding can highlight taxa in which conventional taxonomy underestimates species richness, identifying mitochondrial lineages that may correspond to unrecognized species. However, key assumptions of barcoding remain untested for many groups of soft-bodied marine invertebrates with poorly resolved taxonomy. Here, we applied an integrative approach for species delimitation to herbivorous sea slugs in clade Sacoglossa, in which unrecognized diversity may complicate studies of drug discovery, plastid endosymbiosis, and biological control. Using the mitochondrial barcoding COI gene and the nuclear histone 3 gene, we tested the hypothesis that three widely distributed "species" each comprised a complex of independently evolving lineages. Morphological and reproductive characters were then used to evaluate whether each lineage was distinguishable as a candidate species. The "circumtropical" Elysia ornata comprised a Caribbean species and four Indo-Pacific candidate species that are potential sources of kahalalides, anti-cancer compounds. The "monotypic" and highly photosynthetic Plakobranchus ocellatus, used for over 60 years to study chloroplast symbiosis, comprised 10 candidate species. Finally, six candidate species were distinguished in the Elysia tomentosa complex, including potential biological control agents for invasive green algae (Caulerpa spp.). We show that a candidate species approach developed for vertebrates effectively categorizes cryptic diversity in marine invertebrates, and that integrating threshold COI distances with non-molecular character data can delimit species even when common assumptions of DNA barcoding are violated. Copyright © 2013 Elsevier Inc. All rights reserved.

  10. Integrative species delimitation in photosynthetic sea slugs reveals twenty candidate species in three nominal taxa studied for drug discovery, plastid symbiosis or biological control

    Science.gov (United States)

    Krug, Patrick J.; Vendetti, Jann E.; Rodriguez, Albert K.; Retana, Jennifer N.; Hirano, Yayoi M.; Trowbridge, Cynthia D.

    2013-01-01

    DNA barcoding can highlight taxa in which conventional taxonomy underestimates species richness, identifying mitochondrial lineages that may correspond to unrecognized species. However, key assumptions of barcoding remain untested for many groups of soft-bodied marine invertebrates with poorly resolved taxonomy. Here, we applied an integrative approach for species delimitation to herbivorous sea slugs in clade Sacoglossa, in which unrecognized diversity may complicate studies of drug discovery, plastid endosymbiosis, and biological control. Using the mitochondrial barcoding COI gene and the nuclear histone 3 gene, we tested the hypothesis that three widely distributed “species” each comprised a complex of independently evolving lineages. Morphological and reproductive characters were then used to evaluate whether each lineage was distinguishable as a candidate species. The “circumtropical” Elysia ornata comprised a Caribbean species and four Indo-Pacific candidate species that are potential sources of kahalalides, anti-cancer compounds. The “monotypic” and highly photosynthetic Plakobranchus ocellatus, used for over 60 years to study chloroplast symbiosis, comprised 10 candidate species. Finally, six candidate species were distinguished in the Elysia tomentosa complex, including potential biological control agents for invasive green algae (Caulerpa spp.). We show that a candidate species approach developed for vertebrates effectively categorizes cryptic diversity in marine invertebrates, and that integrating threshold COI distances with non-molecular character data can delimit species even when common assumptions of DNA barcoding are violated. PMID:23876292

  11. Harm caused by Marine Litter

    NARCIS (Netherlands)

    Werner, S.; Budziak, A.; Franeker, van J.A.; Galgani, F.; Hanke, G.; Maes, T.; Matiddi, M.; Nilsson, P.; Oosterbaan, L.; Priestland, E.; Thompson, R.; Veiga, J.; Vlachogianni, T.

    2016-01-01

    Marine litter is a global concern with a range of problems associated to it, as recognised by the Marine Strategy Framework Directive (MSFD). Marine litter can impact organisms at different levels of biological organization and habitats in a number of ways namely: through entanglement in, or

  12. 76 FR 72681 - Marine Mammals

    Science.gov (United States)

    2011-11-25

    ... National Oceanic and Atmospheric Administration RIN 0648-XU87 Marine Mammals AGENCY: National Marine... Mammal Laboratory, (Responsible Party: Dr. John Bengtson, Director), Seattle, WA, has applied for an amendment to Scientific Research Permit No. 15126-01 for studies of marine mammals in Alaska. DATES: Written...

  13. Characterization of Cyanate Metabolism in Marine Synechococcus and Prochlorococcus spp. ▿

    Science.gov (United States)

    Kamennaya, Nina A.; Post, Anton F.

    2011-01-01

    Cyanobacteria of the genera Synechococcus and Prochlorococcus are the most abundant photosynthetic organisms on earth, occupying a key position at the base of marine food webs. The cynS gene that encodes cyanase was identified among bacterial, fungal, and plant sequences in public databases, and the gene was particularly prevalent among cyanobacteria, including numerous Prochlorococcus and Synechococcus strains. Phylogenetic analysis of cynS sequences retrieved from the Global Ocean Survey database identified >60% as belonging to unicellular marine cyanobacteria, suggesting an important role for cyanase in their nitrogen metabolism. We demonstrate here that marine cyanobacteria have a functionally active cyanase, the transcriptional regulation of which varies among strains and reflects the genomic context of cynS. In Prochlorococcus sp. strain MED4, cynS was presumably transcribed as part of the cynABDS operon, implying cyanase involvement in cyanate utilization. In Synechococcus sp. strain WH8102, expression was not related to nitrogen stress responses and here cyanase presumably serves in the detoxification of cyanate resulting from intracellular urea and/or carbamoyl phosphate decomposition. Lastly, we report on a cyanase activity encoded by cynH, a novel gene found in marine cyanobacteria only. The presence of dual cyanase genes in the genomes of seven marine Synechococcus strains and their respective roles in nitrogen metabolism remain to be clarified. PMID:21057026

  14. Marine Renewable Energies

    DEFF Research Database (Denmark)

    Azzellino, Arianna; Conley, Daniel; Vicinanza, Diego

    2013-01-01

    Countries with coastlines may have valuable renewable energy resources in the form of tides, currents, waves, and offshorewind.The potential to gather energy from the sea has recently gained interest in several nations, so Marine Renewable Energy Installations (hereinafter MREIs) will likely become...

  15. Thai marine fungal diversity

    Directory of Open Access Journals (Sweden)

    Rattaket Choeyklin

    2006-07-01

    Full Text Available The marine fungal diversity of Thailand was investigated and 116 Ascomycota, 3 Basidiomycota, 28 anamorphic fungi, 7 Stramenopiles recorded, with 30 tentatively identified. These species have primarily been collected from driftwood and attached decayed wood of mangrove trees. The holotype number of 15 taxa is from Thailand and 33 are new records from the country.

  16. Marine Electrician--Fundamentals.

    Science.gov (United States)

    Sutliff, Ronald D.; And Others

    This self-study course is designed to familiarize Marine Corps enlisted personnel with the principles of electricity, safety, and tools. The course contains three study units. Each study unit begins with a general objective, which is a statement of what the student should learn from the unit. The study units are divided into numbered work units,…

  17. Environmental Impacts - Marine Ecosystems

    NARCIS (Netherlands)

    Brander, K.; Ottersen, Geir; Bakker, Jan P.; Beaugrand, G.; Herr, H.; Garthe, S.; Gilles, A.; Kenny, Andrew; Siebert, Ursula; Skjoldal, Hein Rune; Tulp, I.Y.M.

    2016-01-01

    This chapter presents a review of what is known about the impacts of climate change on the biota (plankton, benthos, fish, seabirds and marine mammals) of the North Sea. Examples show how the changing North Sea environment is affecting biological processes and organisation at all scales, including

  18. Safety of Marine Structures

    DEFF Research Database (Denmark)

    Burcharth, H. F.

    1990-01-01

    of a "future safe" design code for exposed marine structures like breakwaters should be different from the ones usually applied in modern design standards for conventional structures within civil engineering. Moreover, results from ongoing development of a design code for rubble mound breakwaters are presented....

  19. Marine complex adaptive systems

    NARCIS (Netherlands)

    Bigagli, Emanuele

    2017-01-01

    Anthropogenic and climate-related stressors challenge the health of nearly every part of the global oceans. They affect the capacity of oceans to regulate global weather and climate, as well as ocean productivity and food services, and result in the loss or degradation of marine habitats and

  20. nent of marine ecosystems

    African Journals Online (AJOL)

    spamer

    trophic web of marine ecosystems (Clarke 1980,. 1996, Rodhouse et al. 1987, 1992, Lipinski et al. 1992, Rodhouse and Nigmatullin 1996, Guerra et al. 1993). .... deep in the submucosa and were encapsulated in an amorphous eosinophilic substance. The anterior ex- tremities of nematodes and the vacated hyaline caps.

  1. Marine sponges as pharmacy

    NARCIS (Netherlands)

    Sipkema, D.; Franssen, M.C.R.; Osinga, R.; Tramper, J.; Wijffels, R.H.

    2005-01-01

    Marine sponges have been considered as a gold mine during the past 50 years, with respect to the diversity of their secondary metabolites. The biological effects of new metabolites from sponges have been reported in hundreds of scientific papers, and they are reviewed here. Sponges have the

  2. Marine Fish Hybridization

    KAUST Repository

    He, Song

    2017-04-01

    Natural hybridization is reproduction (without artificial influence) between two or more species/populations which are distinguishable from each other by heritable characters. Natural hybridizations among marine fishes were highly underappreciated due to limited research effort; it seems that this phenomenon occurs more often than is commonly recognized. As hybridization plays an important role in biodiversity processes in the marine environment, detecting hybridization events and investigating hybridization is important to understand and protect biodiversity. The first chapter sets the framework for this disseration study. The Cohesion Species Concept was selected as the working definition of a species for this study as it can handle marine fish hybridization events. The concept does not require restrictive species boundaries. A general history and background of natural hybridization in marine fishes is reviewed during in chapter as well. Four marine fish hybridization cases were examed and documented in Chapters 2 to 5. In each case study, at least one diagnostic nuclear marker, screened from among ~14 candidate markers, was found to discriminate the putative hybridizing parent species. To further investigate genetic evidence to support the hybrid status for each hybrid offspring in each case, haploweb analysis on diagnostic markers (nuclear and/or mitochondrial) and the DAPC/PCA analysis on microsatellite data were used. By combining the genetic evidences, morphological traits, and ecological observations together, the potential reasons that triggered each hybridization events and the potential genetic/ecology effects could be discussed. In the last chapter, sequences from 82 pairs of hybridizing parents species (for which COI barcoding sequences were available either on GenBank or in our lab) were collected. By comparing the COI fragment p-distance between each hybridizing parent species, some general questions about marine fish hybridization were discussed: Is

  3. Photosynthetic capacity of senescent leaves for a subtropical broadleaf deciduous tree species Liquidambar formosana Hance.

    Science.gov (United States)

    Luo, Zidong; Guan, Huade; Zhang, Xinping; Liu, Na

    2017-07-24

    Photosynthetic capacity and leaf life span generally determine how much carbon a plant assimilates during the growing season. Leaves of deciduous tree species start senescence in late season, but whether the senescent leaves still retain capacity of carbon assimilation remains a question. In this study, we investigated leaf phenology and photosynthesis of a subtropical broadleaf deciduous tree species Liquidambar formosana Hance in the central southern continental China. The results show that L. formosana has extended leaf senescence (more than 2 months) with a substantial number of red leaves persisting on the tree. Leaf photosynthetic capacity decreases over season, but the senescent red leaves still maintain relatively high photosynthetic capacity at 42%, 66% and 66% of the mature leaves for net photosynthesis rate, apparent quantum yield, and quantum yield at the light compensation point, respectively. These results indicate that L. formosana may still contribute to carbon sink during leaf senescence.

  4. Effects of grafting on key photosynthetic enzymes and gene expression in the citrus cultivar Huangguogan.

    Science.gov (United States)

    Liao, L; Cao, S Y; Rong, Y; Wang, Z H

    2016-03-04

    Grafting influences scion photosynthetic capacity and fruit quality. Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), which strongly affects photosynthetic rate, and Rubisco activase (RCA), which regulates Rubisco activity, are two key photosynthetic enzymes. However, little information is available regarding the effect of grafting on the concentration and expression of Rubisco and RCA in the citrus cultivar Huangguogan. The objective of this study was to investigate the effect of grafting Huangguogan plants onto trifoliate orange, tangerine, and orange on: 1) the concentration of Rubisco and RCA; 2) the mRNA levels of rbcL, rbcS, and rca; and 3) fruit quality. Overall, the results showed that when Huangguogan plants budded on tangerine and orange, they had better fruit quality, while on trifoliate orange they had higher Rubisco concentration. Tangerine and orange are probably the most suitable rootstocks for Huangguogan plants given the environmental conditions of Sichuan Province, China.

  5. REPEATED MEASURES ANALYSIS OF CHANGES IN PHOTOSYNTHETIC EFFICIENCY IN SOUR CHERRY DURING WATER DEFICIT

    Directory of Open Access Journals (Sweden)

    Marija Viljevac

    2012-06-01

    Full Text Available The objective of this study was to investigate changes in photosynthetic efficiency applying repeated measures ANOVA using the photosynthetic performance index (PIABS of the JIP-test as a vitality parameter in seven genotypes of sour cherry (Prunus cerasus, L. during 10 days of continuous water deficit. Both univariate and multivariate ANOVA repeated measures revealed highly significant time effect (Days and its subsequent interactions with genotype and water deficit. However, the multivariate Pillai’s trace test detected the interaction Time × Genotype × Water deficit as not significant. According to the Tukey’s Studentized Range (HSD test, differences between the control and genotypes exposed to water stress became significant on the fourth day of the experiment, indicating that the plants on the average, began to lose their photosynthetic efficiency four days after being exposed to water shortage. It corroborates previous findings in other species that PIABS is very sensitive tool for detecting drought stress.

  6. [The protective action of cytokinins on the photosynthetic apparatus and productivity of plants under stress (review)].

    Science.gov (United States)

    Cherniad'ev, I I

    2009-01-01

    A putative way of the protective action of cytokinins on the photosynthetic processes in crops experiencing various stress factors is considered. Various cytokinins are characterized. Pathways of the multiple effects of cytokinin preparations mediating the protection of the photosynthetic machinery from stress are described. Cytokinins interact with receptor proteins, and then the signal is transduced to primary cellular targets (primary response genes). These genes, which possess receptor domains, induce synthesis of the corresponding mRNAs and photosynthesis-related proteins of chlorophyll-protein complexes, the electron-transport chain, and carbon metabolism, primarily, the key enzyme ribulose bisphosphate carboxylase/oxygenase. The protective action of cytokinins under stress conditions preserves the structure and function of the photosynthetic apparatus. The application of cytokinins to improving crop yields is discussed.

  7. Oxygen regulation of development of the photosynthetic membrane system in Chloroflexus aurantiacus

    Energy Technology Data Exchange (ETDEWEB)

    Foster, J.M.; Redlinger, T.E.; Blankenship, R.E.; Fuller, R.C.

    1986-08-01

    Oxygen levels which control induction of the assembly of the pigment-protein photosynthetic polypeptides in dark-grown Chloroflexus aurantiacus were determined. The induction signal by low-oxygen tension is not directly related to the respiratory competence of these photosynthetic cells. Cytochrome c/sub 554/, the primary electron donor to P865/sup +/ of the reaction center, is not present in dark-grown respiratory cells but is induced in parallel with bacteriochlorophylls a and c and at similar oxygen partial pressure. The development of these components of the photosynthetic apparatus and its electron transport chain is completely independent of the presence of any detectable light of bacteriochlorophyll c or a pigments in C. aurantiacus.

  8. Interactive effects of cadmium and acid rain on photosynthetic light reaction in soybean seedlings.

    Science.gov (United States)

    Sun, Zhaoguo; Wang, Lihong; Chen, Minmin; Wang, Lei; Liang, Chanjuan; Zhou, Qing; Huang, Xiaohua

    2012-05-01

    Interactive effects of cadmium (Cd(2+)) and acid rain on photosynthetic light reaction in soybean seedlings were investigated under hydroponic conditions. Single treatment with Cd(2+) or acid rain and the combined treatment decreased the content of chlorophyll, Hill reaction rate, the activity of Mg(2+)-ATPase, maximal photochemical efficiency and maximal quantum yield, increased initial fluorescence and damaged the chloroplast structure in soybean seedlings. In the combined treatment, the change in the photosynthetic parameters and the damage of chloroplast structure were stronger than those of any single pollution. Meanwhile, Cd(2+) and acid rain had the interactive effects on the test indices in soybean seedlings. The results indicated that the combined pollution of Cd(2+) and acid rain aggravated the toxic effect of the single pollution of Cd(2+) or acid rain on the photosynthetic parameters due to the serious damage to the chloroplast structure. Copyright © 2011 Elsevier Inc. All rights reserved.

  9. Photosynthetic potential of planets in 3 : 2 spin-orbit resonances

    Science.gov (United States)

    Brown, S. P.; Mead, A. J.; Forgan, D. H.; Raven, J. A.; Cockell, C. S.

    2014-10-01

    Photosynthetic life requires sufficient photosynthetically active radiation to metabolize. On Earth, plant behaviour, physiology and metabolism are sculpted around the night-day cycle by an endogenous biological circadian clock. The evolution of life was influenced by the Earth-Sun orbital dynamic, which generates the photo-environment incident on the planetary surface. In this work, the unusual photo-environment of an Earth-like planet (ELP) in 3 : 2 spin-orbit resonance is explored. Photo-environments on the ELP are longitudinally differentiated, in addition to differentiations related to latitude and depth (for aquatic organisms) which are familiar on Earth. The light environment on such a planet could be compatible with Earth's photosynthetic life although the threat of atmospheric freeze-out and prolonged periods of darkness would present significant challenges. We emphasize the relationship between the evolution of life on a planetary body with its orbital dynamics.

  10. Epigenomics in marine fishes.

    Science.gov (United States)

    Metzger, David C H; Schulte, Patricia M

    2016-12-01

    Epigenetic mechanisms are an underappreciated and often ignored component of an organism's response to environmental change and may underlie many types of phenotypic plasticity. Recent technological advances in methods for detecting epigenetic marks at a whole-genome scale have launched new opportunities for studying epigenomics in ecologically relevant non-model systems. The study of ecological epigenomics holds great promise to better understand the linkages between genotype, phenotype, and the environment and to explore mechanisms of phenotypic plasticity. The many attributes of marine fish species, including their high diversity, variable life histories, high fecundity, impressive plasticity, and economic value provide unique opportunities for studying epigenetic mechanisms in an environmental context. To provide a primer on epigenomic research for fish biologists, we start by describing fundamental aspects of epigenetics, focusing on the most widely studied and most well understood of the epigenetic marks: DNA methylation. We then describe the techniques that have been used to investigate DNA methylation in marine fishes to date and highlight some new techniques that hold great promise for future studies. Epigenomic research in marine fishes is in its early stages, so we first briefly discuss what has been learned about the establishment, maintenance, and function of DNA methylation in fishes from studies in zebrafish and then summarize the studies demonstrating the pervasive effects of the environment on the epigenomes of marine fishes. We conclude by highlighting the potential for ongoing research on the epigenomics of marine fishes to reveal critical aspects of the interaction between organisms and their environments. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. The evolution of photosynthetic capacity and the antioxidant enzymatic system during acclimatization of micropropagated Calathea plants.

    Science.gov (United States)

    Van Huylenbroeck JM; Piqueras; Debergh

    2000-06-12

    The effects of an increased PPFD on photosynthesis, the functioning of the photosynthetic apparatus and the response of the antioxidant enzymatic system were studied during the ex vitro establishment of micropropagated Calathea 'Maui Queen' plantlets. Measured chlorophyll and carotenoids contents in ex vitro formed leaves were almost three times higher compared to the in vitro formed ones. At the end of the acclimatization, an inverse relation between PPFD and the chlorophyll (a+b)/carotenoids ratio was observed. During the first days after transplantation Calathea plants are not photosynthetically active, as is illustrated by the photosynthetic light response curves. With the appearance of new leaves, higher photosynthetic capacities were observed and light saturation point increased (days 17 and 25). Also the maximal photosynthetic efficiency enlarged as shown by the increased initial slope of the curves. F(v)/F(m) decreased directly after transplantation of the micropropagated plantlets, afterwards a recovery was observed, but highest F(v)/F(m) values were observed in low light (LL) plants. The photochemical quenching coefficient increased gradually during the first two weeks of the acclimatization. In high light (HL) plants, q(P) decreased directly after transfer, while this was not observed in LL and medium light (ML). During the acclimatization period to increasing light intensities significant changes in the activity of the antioxidant enzymatic system were observed. A decrease in superoxide dismutase (SOD) activity was measured during the first half of the acclimatization period followed by a recovery in ML and HL plants by day 35. Dehydroascorbate reductase (DHAR) activity decreased during acclimatization. At the end of the experimental period the lowest levels were measured in ML plants. Catalase (CAT) activity increased significantly during the first two weeks after transfer, a clear inverse relationship to PPFD was detected. The relation between the

  12. Discussion of Yellow Starthistle Response to Photosynthetic Irradiance, Photoperiod, and CO2

    Science.gov (United States)

    Bubenheim, David

    2017-01-01

    Yellow Starthistle (Centaurea solstitialis) is a native annual weed of Eurasia and since introduction into the United STates has become an invasive and noxious weed. It grows in a rosette habit during the vegetative state and usually bolts in summer to produce a large and branched flowering stem. Time to flowering in Yellow Starthistle has been attributed to photoperiod, nitrogen nutrition, temperature, and water stress. We executed a series of studies to investigate the role of light, both photoperiod and photosynthetic photon flux, on flowering and development in Yellow Starthistle. Treatments were presented in 4 ways: 1) varying day length with constant photosynthetic photon flus (PPF) providing increasing daily integrated Photosynthetic Photon (PP) exposure with longer day lengths 2) varying day length while adjusting PPF to maintain daily PP exposure for all treatments 3) extending photoperiod treatments beyond common 12-h photosynthetic period with low light levels to maintain both PPF and daily PP across all treatments4)reciprocal exchange of plant among photoperiod treatments Yellow Starthistle appears to be a long-day plant with a critical day length requirement between 14-h and 16-h to induce transition from vegetative to floral stages in development. PPF and daily absorbed photons did not affect time to vegetative floral stage transition, but did affect factors such as biomass accumulation and canopy parameters such as specific leaf mass. Reciprocal exchange of plants between floral inducing and inhibiting photoperiod treatments, starting at 2-weeks post germination, had no effect on to flower. Flowering was determined by photoperiod experienced during the first 2-weeks (or less) post germination.Yellow Starthistle net photosynthetic response to elevated atmospheric CO2 concentrations over a range of photosynthetically active radiation flux rates and temperatures will also be presented and discussed.

  13. Prioritization of copper for the use in photosynthetic electron transport in developing leaves of hybrid poplar

    Directory of Open Access Journals (Sweden)

    Muhammad eShahbaz

    2015-06-01

    Full Text Available Plastocyanin is an essential and abundant copper protein required for photosynthesis in higher plants. Severe copper deprivation has the potential to cause a defect in photosynthetic electron transport due to a lack in plastocyanin. The Cu-microRNAs, which are up-regulated under Cu deficiency, down-regulate the expression of target Cu proteins other than plastocyanin, cytochrome-c oxidase and the ethylene receptors. It has been proposed that this mechanism saves Cu for plastocyanin maturation. We aimed to test how hybrid poplar, a species that has capacity to rapidly expand its photosynthetically active tissue, responds to variations in Cu availability over time. Measurement of chlorophyll fluorescence after Cu depletion revealed a drastic effect on photosynthesis in hybrid poplar. The decrease in photosynthetic capacity was correlated with a reduction in plastocyanin protein levels. Compared to older leaves, plastocyanin decreased more strongly in developing leaves, which also lost more photosynthetic electron transport capacity. The effect of Cu depletion on older and more developed leaves was minor and these leaves maintained much of their photosynthetic capacity. Interestingly, upon resupply of Cu to the medium a very rapid recovery of Cu levels was seen in the younger leaves with a concomitant rise in the expression and activity of plastocyanin. In contrast, the expression of those Cu proteins, which are targets of microRNAs was under the same circumstances delayed. At the same time, Cu resupply had only minor effects on the older leaves. The data suggest a model where rapid recovery of photosynthetic capacity in younger leaves is made possible by a preferred allocation of Cu to plastocyanin in younger leaves, which is supported by Cu-microRNA expression.

  14. Antitumor Peptides from Marine Organisms

    Directory of Open Access Journals (Sweden)

    Mi Sun

    2011-10-01

    Full Text Available The biodiversity of the marine environment and the associated chemical diversity constitute a practically unlimited resource of new antitumor agents in the field of the development of marine bioactive substances. In this review, the progress on studies of antitumor peptides from marine sources is provided. The biological properties and mechanisms of action of different marine peptides are described; information about their molecular diversity is also presented. Novel peptides that induce apoptosis signal pathway, affect the tubulin-microtubule equilibrium and inhibit angiogenesis are presented in association with their pharmacological properties. It is intended to provide useful information for further research in the fields of marine antitumor peptides.

  15. Anticoagulant effect of marine algae.

    Science.gov (United States)

    Kim, Se-Kwon; Wijesekara, Isuru

    2011-01-01

    Recently, a great deal of interest has been developed in the nutraceutical and pharmaceutical industries to isolate natural anticoagulant compounds from marine resources. Among marine resources, marine algae are valuable sources of novel bioactive compounds with anticoagulant effect. Phlorotannins and sulfated polysaccharides such as fucoidans in brown algae, carrageenans in red algae, and ulvans in green algae have been recognized as potential anticoagulant agents. Therefore, marine algae-derived phlorotannins and SPs have great potential for developing as anticoagulant drugs in nutraceutical and pharmaceutical areas. This chapter focuses on the potential anticoagulant agents in marine algae and presents an overview of their anticoagulant effect. Copyright © 2011 Elsevier Inc. All rights reserved.

  16. Tracking the molecular evolution of photosynthesis through characterization of atomic contents of the photosynthetic units.

    Science.gov (United States)

    Chen, Min; Zhang, Yinan

    2008-09-01

    Oxygen molecules have a great impact on protein evolution. We have performed a comparative study of key photosynthetic proteins in order to seek the answer to the question; did the evolutionary substitution of oxygen- and nitrogen-containing residues in the photosynthetic proteins correspond to nutrient constraints and metabolic optimization? The D1 peptide in RC II complexes has higher oxygen-containing amino acid residues and PufL/PufM have lower oxygen content in their peptides. In this article, we also discuss the possible influences of micro-environment and the available nutrients on the protein structure and their atomic distribution.

  17. Interference of Cd2+ in functioning of the photosynthetic apparatus of higher plants

    Directory of Open Access Journals (Sweden)

    Tadeusz Baszyński

    2014-01-01

    Full Text Available The actual opinions concerning the role of Cd2+ in inhibition of photosynthesis have been reviewed. The light phase of photosynthesis, particularly the site of Cd2+ action in the photosynthetic transport chain has been given the greatest attention. Cd2+-induced inhibition of Photosystem II activity as the result of thylakoid membrane degradation has been discussed. The present studies on Cd2+-inhibited dark reactions occurring in stroma has been analysed. Attention has been drawn to the fact that the results of studies in vitro are not always compatible with the changes found in the photosynthetic apparatus of higher plants growing in a Cd2 containing medium.

  18. The contributions of 49ers to the measurements and models of ultrafast photosynthetic energy transfer

    Energy Technology Data Exchange (ETDEWEB)

    Fleming, Graham R. [Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2017-02-28

    Progress in measuring and understanding the mechanism of the elementary energy transfer steps in photosynthetic light harvesting from roughly 1949 to the present is sketched with a focus on the group of scientists born in 1949 ± 1. Improvements in structural knowledge, laser spectroscopic methods, and quantum dynamical theories have led to the ability to record and calculate with reasonable accuracy the timescales of elementary energy transfer steps. The importance of delocalized excited states and of near-field Coulombic coupling is noted. The microscopic understanding enables consistent coarse graining and should enable a much-improved understanding of the regulation of photosynthetic light harvesting.

  19. Dynamic control of photosynthetic photon flux for lettuce production in CELSS

    Science.gov (United States)

    Chun, C.; Mitchell, C. A.

    1996-01-01

    A new dynamic control of photosynthetic photon flux (PPF) was tested using lettuce canopies growing in the Minitron II plant-growth/canopy gas-exchange system. Canopy photosynthetic rates (Pn) were measured in real time and fedback for further environment control. Pn can be manipulated by changing PPF, which is a good environmental parameter for dynamic control of crop production in a Controlled Ecological Life-Support Systems CELSS. Decision making that combines empirical mathematical models with rule sets developed from recent experimental data was tested. With comparable yield indices and potential for energy savings, dynamic control strategies will contribute greatly to the sustainability of space-deployed CELSS.

  20. The contributions of 49ers to the measurements and models of ultrafast photosynthetic energy transfer.

    Science.gov (United States)

    Fleming, Graham R

    2018-03-01

    Progress in measuring and understanding the mechanism of the elementary energy transfer steps in photosynthetic light harvesting from roughly 1949 to the present is sketched with a focus on the group of scientists born in 1949 ± 1. Improvements in structural knowledge, laser spectroscopic methods, and quantum dynamical theories have led to the ability to record and calculate with reasonable accuracy the timescales of elementary energy transfer steps. The significance of delocalized excited states and of near-field Coulombic coupling is noted. The microscopic understanding enables consistent coarse graining and should enable a much-improved understanding of the regulation of photosynthetic light harvesting.

  1. Diversity and regulation of ATP sulfurylase in photosynthetic organisms

    Directory of Open Access Journals (Sweden)

    Laura ePrioretti

    2014-11-01

    Full Text Available ATP sulfurylase (ATPS catalyzes the first committed step in the sulfate assimilation pathway, the activation of sulfate prior to its reduction. ATPS has been studied in only a few model organisms and even in these cases to a much smaller extent than the sulfate reduction and cysteine synthesis enzymes. This is possibly because the latter were considered of greater regulatory importance for sulfate assimilation. Recent evidences (reported in this paper challenge this view and suggest that ATPSes may have a crucial regulatory role in sulfate assimilation, at least in algae.In the ensuing text, we summarize the current knowledge on ATPS, with special attention to the processes that control its activity and gene(s expression. Special attention is given to algae ATPSes. The focus on algae is the consequence of the fact that a comprehensive investigation of ATPSes revealed that the algal enzymes, especially those that are most likely involved in the pathway of sulfate reduction to cysteine, possess features that are not present in other organisms. For instance, algae ATPSes show a great diversity of isoforms and a high content of cysteine residues, whose positions are often conserved. It is interesting that, at least with respect to the number of cysteines, the ATPSes of eukaryotic algae are closer to the marine cyanobacteria of the genera Synechococcus and Prochlorococcus and are more distant from freshwater cyanobacteria. These characteristics might have evolved in parallel with the radiation of algae in the oceans and the increase of sulfate concentration in seawater.

  2. Photosynthetic pigments of oceanic Chlorophyta belonging to prasinophytes clade VII.

    Science.gov (United States)

    Lopes Dos Santos, Adriana; Gourvil, Priscillia; Rodríguez, Francisco; Garrido, José Luis; Vaulot, Daniel

    2016-02-01

    The ecological importance and diversity of pico/nanoplanktonic algae remains poorly studied in marine waters, in part because many are tiny and without distinctive morphological features. Amongst green algae, Mamiellophyceae such as Micromonas or Bathycoccus are dominant in coastal waters while prasinophytes clade VII, yet not formerly described, appear to be major players in open oceanic waters. The pigment composition of 14 strains representative of different subclades of clade VII was analyzed using a method that improves the separation of loroxanthin and neoxanthin. All the prasinophytes clade VII analyzed here showed a pigment composition similar to that previously reported for RCC287 corresponding to pigment group prasino-2A. However, we detected in addition astaxanthin for which it is the first report in prasinophytes. Among the strains analyzed, the pigment signature is qualitatively similar within subclades A and B. By contrast, RCC3402 from subclade C (Picocystis) lacks loroxanthin, astaxanthin, and antheraxanthin but contains alloxanthin, diatoxanthin, and monadoxanthin that are usually found in diatoms or cryptophytes. For subclades A and B, loroxanthin was lowest at highest light irradiance suggesting a light-harvesting role of this pigment in clade VII as in Tetraselmis. © 2015 Phycological Society of America.

  3. Accumulation of Cu and Zn from antifouling paint particles by the marine macroalga, Ulva lactuca

    Energy Technology Data Exchange (ETDEWEB)

    Turner, Andrew, E-mail: aturner@plymouth.ac.u [School of Earth, Ocean and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom); Pollock, Heather [School of Earth, Ocean and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom); Brown, Murray T. [School of Biological Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom)

    2009-08-15

    The marine macroalga, Ulva lactuca, has been exposed to different concentrations of antifouling paint particles (4-200 mg L{sup -1}) in the presence of a fixed quantity of clean estuarine sediment and its photosynthetic response and accumulation of Cu and Zn monitored over a period of 2 days. An immediate (<2 h) toxic effect was elicited under all experimental conditions that was quantitatively related to the concentration of contaminated particles present. Likewise, the rate of leaching of both Cu and Zn was correlated with the concentration of paint particles added. Copper accumulation by the alga increased linearly with aqueous Cu concentration, largely through adsorption to the cell surface, but significant accumulation of Zn was not observed. Thus, in coastal environments where boat maintenance is practiced, discarded antifouling paint particles are an important source of Cu, but not Zn, to U. lactuca. - The marine macroalga, Ulva lactuca, is able to accumulate Cu but not Zn from discarded antifouling paint particles.

  4. Identification of large variation in the photosynthetic induction response among 37 soybean [Glycine max (L.) Merr.] genotypes that is not correlated with steady-state photosynthetic capacity.

    Science.gov (United States)

    Soleh, M A; Tanaka, Y; Kim, S Y; Huber, S C; Sakoda, K; Shiraiwa, T

    2017-03-01

    Irradiance continuously fluctuates during the day in the field. The speed of the induction response of photosynthesis in high light affects the cumulative carbon gain of the plant and could impact growth and yield. The photosynthetic induction response and its relationship with the photosynthetic capacity under steady-state conditions (P max) were evaluated in 37 diverse soybean [Glycine max (L.) Merr.] genotypes. The induction response of leaf photosynthesis showed large variation among the soybean genotypes. After 5 min illumination with strong light, genotype NAM23 had the highest leaf photosynthetic rate of 33.8 µmol CO2 m-2 s-1, while genotype NAM12 showed the lowest rate at 4.7 µmol CO2 m-2 s-1. Cumulative CO2 fixation (CCF) during the first 5 min of high light exposure ranged from 5.5 mmol CO2 m-2 for NAM23 to 0.81 mmol CO2 m-2 for NAM12. The difference in the induction response among genotypes was consistent throughout the growth season. However, there was no significant correlation between CCF and P max among genotypes suggesting that different mechanisms regulate P max and the induction response. The observed variation in the induction response was mainly attributed to ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activation, but soybean lines differing in the induction response did not differ in the leaf content of Rubisco activase α- and β-proteins. Future studies will be focused on identifying molecular determinants of the photosynthetic induction response and determining whether this trait could be an important breeding target to achieve improved growth of soybeans in the field.

  5. Emerging biopharmaceuticals from marine actinobacteria.

    Science.gov (United States)

    Hassan, Syed Shams Ul; Anjum, Komal; Abbas, Syed Qamar; Akhter, Najeeb; Shagufta, Bibi Ibtesam; Shah, Sayed Asmat Ali; Tasneem, Umber

    2017-01-01

    Actinobacteria are quotidian microorganisms in the marine world, playing a crucial ecological role in the recycling of refractory biomaterials and producing novel secondary metabolites with pharmaceutical applications. Actinobacteria have been isolated from the huge area of marine organisms including sponges, tunicates, corals, mollusks, crabs, mangroves and seaweeds. Natural products investigation of the marine actinobacteria revealed that they can synthesize numerous natural products including alkaloids, polyketides, peptides, isoprenoids, phenazines, sterols, and others. These natural products have a potential to provide future drugs against crucial diseases like cancer, HIV, microbial and protozoal infections and severe inflammations. Therefore, marine actinobacteria portray as a pivotal resource for marine drugs. It is an upcoming field of research to probe a novel and pharmaceutically important secondary metabolites from marine actinobacteria. In this review, we attempt to summarize the present knowledge on the diversity, chemistry and mechanism of action of marine actinobacteria-derived secondary metabolites from 2007 to 2016. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Temperature-sensitive PSII: a novel approach for sustained photosynthetic hydrogen production.

    Science.gov (United States)

    Bayro-Kaiser, Vinzenz; Nelson, Nathan

    2016-12-01

    The need for energy and the associated burden are ever growing. It is crucial to develop new technologies for generating clean and efficient energy for society to avoid upcoming energetic and environmental crises. Sunlight is the most abundant source of energy on the planet. Consequently, it has captured our interest. Certain microalgae possess the ability to capture solar energy and transfer it to the energy carrier, H2. H2 is a valuable fuel, because its combustion produces only one by-product: water. However, the establishment of an efficient biophotolytic H2 production system is hindered by three main obstacles: (1) the hydrogen-evolving enzyme, [FeFe]-hydrogenase, is highly sensitive to oxygen; (2) energy conversion efficiencies are not economically viable; and (3) hydrogen-producing organisms are sensitive to stressful conditions in large-scale production systems. This study aimed to circumvent the oxygen sensitivity of this process with a cyclic hydrogen production system. This approach required a mutant that responded to high temperatures by reducing oxygen evolution. To that end, we randomly mutagenized the green microalgae, Chlamydomonas reinhardtii, to generate mutants that exhibited temperature-sensitive photoautotrophic growth. The selected mutants were further characterized by their ability to evolve oxygen and hydrogen at 25 and 37 °C. We identified four candidate mutants for this project. We characterized these mutants with PSII fluorescence, P700 absorbance, and immunoblotting analyses. Finally, we demonstrated that these mutants could function in a prototype hydrogen-producing bioreactor. These mutant microalgae represent a novel approach for sustained hydrogen production.

  7. Inhibitory effects of tributyl phosphate on algal growth, photosynthesis, and fatty acid synthesis in the marine diatom Phaeodactylum tricornutum.

    Science.gov (United States)

    Song, Hao; Fan, Xiaoji; Liu, Guangfu; Xu, Jiahui; Li, Xingxing; Tan, Yuzhu; Qian, Haifeng

    2016-12-01

    The widely used solvent extractant, tributyl phosphate (TBP), primarily used as a solvent for the conventional processing of nuclear fuel, has come under scrutiny recently due to concerns surrounding potential environmental contamination and toxicity. In this study, we found that, in Phaeodactylum tricornutum, administration of TBP severely inhibited algal cell growth by reducing photosynthetic efficiency and inducing oxidative stress. We further explored the effect of TBP by examining the gene expression of the photosynthetic electron transport chain and its contribution to reactive oxygen species (ROS) burst. Our data revealed that TBP affected both fatty acid content and profile by regulating the transcription of genes related to glycolysis, fatty acid biosynthesis, and β-oxidation. These results demonstrated that TBP did in fact trigger the synthesis of ROS, disrupting the subcellular membrane structure of this aquatic organism. Our study brings new insight into the fundamental mechanism of toxicity exerted by TBP on the marine alga P. tricornutum.

  8. Effect on Growth, Photosynthesis, and Oxidative Stress of Single Walled Carbon Nanotubes Exposure to Marine Alga Dunaliella tertiolecta

    Directory of Open Access Journals (Sweden)

    Megha Thakkar

    2016-01-01

    Full Text Available Single walled carbon nanotubes were carboxylated by microwave assisted acid oxidation (f-SWCNTs and examined for their ecotoxicity on marine alga chlorophyte Dunaliella tertiolecta. Toxicity was evaluated based on growth, photosynthetic activities, oxidative stress, and intracellular glutathione in the concentration range of 0.1–20 mg/L f-SWCNT. Physical interactions between the f-SWCNT and alga were examined using light microscopy and scanning electron microscope. Increasing the nanotube concentration increased the toxic effects where growth inhibition was as high as 30%, photosynthetic yield decreased by as much as 18%, and intracellular glutathione reduction reached 95%. The results from f-SWCNTs were somewhat different when compared to our previous study using the same algae and functionalized multiwalled carbon nanotubes, where exposure led to longer lag phase and higher growth rate inhibition.

  9. Effect on Growth, Photosynthesis, and Oxidative Stress of Single Walled Carbon Nanotubes Exposure to Marine Alga Dunaliella tertiolecta.

    Science.gov (United States)

    Thakkar, Megha; Mitra, Somenath; Wei, Liping

    2016-01-01

    Single walled carbon nanotubes were carboxylated by microwave assisted acid oxidation (f-SWCNTs) and examined for their ecotoxicity on marine alga chlorophyte Dunaliella tertiolecta. Toxicity was evaluated based on growth, photosynthetic activities, oxidative stress, and intracellular glutathione in the concentration range of 0.1-20 mg/L f-SWCNT. Physical interactions between the f-SWCNT and alga were examined using light microscopy and scanning electron microscope. Increasing the nanotube concentration increased the toxic effects where growth inhibition was as high as 30%, photosynthetic yield decreased by as much as 18%, and intracellular glutathione reduction reached 95%. The results from f-SWCNTs were somewhat different when compared to our previous study using the same algae and functionalized multiwalled carbon nanotubes, where exposure led to longer lag phase and higher growth rate inhibition.

  10. Marine04 Marine radiocarbon age calibration, 26 ? 0 ka BP

    Energy Technology Data Exchange (ETDEWEB)

    Hughen, K; Baille, M; Bard, E; Beck, J; Bertrand, C; Blackwell, P; Buck, C; Burr, G; Cutler, K; Damon, P; Edwards, R; Fairbanks, R; Friedrich, M; Guilderson, T; Kromer, B; McCormac, F; Manning, S; Bronk-Ramsey, C; Reimer, P; Reimer, R; Remmele, S; Southon, J; Stuiver, M; Talamo, S; Taylor, F; der Plicht, J v; Weyhenmeyer, C

    2004-11-01

    New radiocarbon calibration curves, IntCal04 and Marine04, have been constructed and internationally ratified to replace the terrestrial and marine components of IntCal98. The new calibration datasets extend an additional 2000 years, from 0-26 ka cal BP (Before Present, 0 cal BP = AD 1950), and provide much higher resolution, greater precision and more detailed structure than IntCal98. For the Marine04 curve, dendrochronologically dated tree-ring samples, converted with a box-diffusion model to marine mixed-layer ages, cover the period from 0-10.5 ka cal BP. Beyond 10.5 ka cal BP, high-resolution marine data become available from foraminifera in varved sediments and U/Th-dated corals. The marine records are corrected with site-specific {sup 14}C reservoir age information to provide a single global marine mixed-layer calibration from 10.5-26.0 ka cal BP. A substantial enhancement relative to IntCal98 is the introduction of a random walk model, which takes into account the uncertainty in both the calendar age and the radiocarbon age to calculate the underlying calibration curve. The marine datasets and calibration curve for marine samples from the surface mixed layer (Marine04) are discussed here. The tree-ring datasets, sources of uncertainty, and regional offsets are presented in detail in a companion paper by Reimer et al.

  11. Relationship Between Diurnal Changes of Net Photosynthetic Rate and Influencing Factors in Rice under Saline Sodic Stress

    Directory of Open Access Journals (Sweden)

    Fu Yang

    2008-06-01

    Full Text Available The net photosynthetic rate of flag leaves and influencing factors under saline sodic soil conditions were investigated at the full heading stage of rice. The net photosynthetic rate of rice leaves showed a double-peak curve in a day in both non-saline sodic and saline sodic soil treatments. The first peak of the net photosynthetic rate appeared at 9:00–10:00 and 9:00 in the saline sodic and non-saline sodic soil treatments, respectively, whereas the second peak both at 14:00. The midday depression of the net photosynthetic rate always appeared regardless of non-saline sodic or saline sodic soil conditions. In addition, the net photosynthetic rate significantly decreased in all day under saline sodic conditions compared with that under non-saline sodic conditions. Some differences were observed in correlation characters between the net photosynthetic rate and all influencing factors during 9:00–13:00. Under non-saline sodic conditions, the diurnal changes of the net photosynthetic rate in a day were mainly caused by stomatal conductance, and the limitation value and the stomatal factors served as determinants; whereas under saline sodic stress, the diurnal changes of the net photosynthetic rate in a day were mainly caused by non stomatal factors including light intensity and air temperature.

  12. Marine Toxins: An Overview

    Science.gov (United States)

    Fusetani, Nobuhiro

    Oceans provide enormous and diverse space for marine life. Invertebrates are conspicuous inhabitants in certain zones such as the intertidal; many are soft-bodied, relatively immobile and lack obvious physical defenses. These animals frequently have evolved chemical defenses against predators and overgrowth by fouling organisms. Marine animals may accumulate and use a variety of toxins from prey organisms and from symbiotic microorganisms for their own purposes. Thus, toxic animals are particularly abundant in the oceans. The toxins vary from small molecules to high molecular weight proteins and display unique chemical and biological features of scientific interest. Many of these substances can serve as useful research tools or molecular models for the design of new drugs and pesticides. This chapter provides an initial survey of these toxins and their salient properties.

  13. Understanding Marine Mussel Adhesion

    Energy Technology Data Exchange (ETDEWEB)

    H. G. Silverman; F. F. Roberto

    2007-12-01

    In addition to identifying the proteins that have a role in underwater adhesion by marine mussels, research efforts have focused on identifying the genes responsible for the adhesive proteins, environmental factors that may influence protein production, and strategies for producing natural adhesives similar to the native mussel adhesive proteins. The production-scale availability of recombinant mussel adhesive proteins will enable researchers to formulate adhesives that are waterimpervious and ecologically safe and can bind materials ranging from glass, plastics, metals, and wood to materials, such as bone or teeth, biological organisms, and other chemicals or molecules. Unfortunately, as of yet scientists have been unable to duplicate the processes that marine mussels use to create adhesive structures. This study provides a background on adhesive proteins identified in the blue mussel, Mytilus edulis, and introduces our research interests and discusses the future for continued research related to mussel adhesion.

  14. Marine pollution: an overview

    Science.gov (United States)

    Valentukevičienė, Marina; Brannvall, Evelina

    2008-01-01

    This overview of marine pollution follows the methodology as proposed below. Firstly, well-known databases (Science Direct, GeoRef, SpringerLINK, etc.) on technological research were studied. All collected references were divided into 27 sections following the key words associated with marine pollution, oil spills, alien species migration, etc. The most commercially promising research and development (R & D) activities seem to be market-oriented sections: detection of oil spills at sea, containment and recovery of floating oil at sea, detection of oil spills on land, disposal of oil and debris on land, alien species migration prevention from ballast water and underwater hull cleaning in water, NOx and SOx emissions, pollutions from ship-building and repair, and biogeochemical modelling. Great market demands for commercially patented innovations are very attractive for initiating new R & D projects.

  15. Effects of elevated pCO2 on physiological performance of marine microalgae Dunaliella salina (Chlorophyta, Chlorophyceae)

    Science.gov (United States)

    Hu, Shunxin; Wang, You; Wang, Ying; Zhao, Yan; Zhang, Xinxin; Zhang, Yongsheng; Jiang, Ming; Tang, Xuexi

    2017-06-01

    The present study was conducted to determine the effects of elevated pCO2 on growth, photosynthesis, dark respiration and inorganic carbon acquisition in the marine microalga Dunaliella salina. To accomplish this, D. salina was incubated in semi-continuous cultures under present-day CO2 levels (390 μatm, pHNBS: 8.10), predicted year 2100 CO2 levels (1 000 μatm, pHNBS: 7.78) and predicted year 2300 CO2 levels (2 000 μatm, pHNBS: 7.49). Elevated pCO2 significantly enhanced photosynthesis (in terms of gross photosynthetic O2 evolution, effective quantum yield (ΔF/F' m ), photosynthetic efficiency (α), maximum relative electron transport rate (rETRmax) and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activity) and dark respiration of D. salina, but had insignificant effects on growth. The photosynthetic O2 evolution of D. salina was significantly inhibited by the inhibitors acetazolamide (AZ), ethoxyzolamide (EZ) and 4,4'-diisothiocyanostilbene-2,2'-disulfonate (DIDS), indicating that D. salina is capable of acquiring HCO3 - via extracellular carbonic anhydrase and anion-exchange proteins. Furthermore, the lower inhibition of the photosynthetic O2 evolution at high pCO2 levels by AZ, EZ and DIDS and the decreased carbonic anhydrase showed that carbon concentrating mechanisms were down-regulated at high pCO2. In conclusion, our results show that photosynthesis, dark respiration and CCMs will be affected by the increased pCO2/low pH conditions predicted for the future, but that the responses of D. salina to high pCO2/low pH might be modulated by other environmental factors such as light, nutrients and temperature. Therefore, further studies are needed to determine the interactive effects of pCO2, temperature, light and nutrients on marine microalgae.

  16. Osmoregulation in marine mammals

    Science.gov (United States)

    Ortiz, R. M.

    2001-01-01

    Osmoregulation in marine mammals has been investigated for over a century; however, a review of recent advances in our understanding of water and electrolyte balance and of renal function in marine mammals is warranted. The following topics are discussed: (i) kidney structure and urine concentrating ability, (ii) sources of water, (iii) the effects of feeding, fasting and diving, (iv) the renal responses to infusions of varying salinity and (v) hormonal regulation. The kidneys of pinnipeds and cetaceans are reniculate in structure, unlike those of terrestrial mammals (except bears), but this difference does not confer any greater concentrating ability. Pinnipeds, cetaceans, manatees and sea otters can concentrate their urine above the concentration of sea water, but only pinnipeds and otters have been shown to produce urine concentrations of Na+ and Cl- that are similar to those in sea water. This could afford them the capacity to drink sea water and not lose fresh water. However, with few exceptions, drinking is not a common behavior in pinnipeds and cetaceans. Water balance is maintained in these animals via metabolic and dietary water, while incidental ingestion and dietary salt may help maintain electrolyte homeostasis. Unlike most other aquatic mammals, sea otters commonly drink sea water and manatees frequently drink fresh water. Among the various taxonomic groups of marine mammals, the sensitivity of the renin-angiotensin-aldosterone system appears to be influenced by the availability of Na+. The antidiuretic role of vasopressin remains inconclusive in marine mammals, while the natriuretic function of atrial natriuretic peptide has yet to be examined. Ideas on the direction of future studies are presented.

  17. Marine cloud brightening

    Science.gov (United States)

    Latham, John; Bower, Keith; Choularton, Tom; Coe, Hugh; Connolly, Paul; Cooper, Gary; Craft, Tim; Foster, Jack; Gadian, Alan; Galbraith, Lee; Iacovides, Hector; Johnston, David; Launder, Brian; Leslie, Brian; Meyer, John; Neukermans, Armand; Ormond, Bob; Parkes, Ben; Rasch, Phillip; Rush, John; Salter, Stephen; Stevenson, Tom; Wang, Hailong; Wang, Qin; Wood, Rob

    2012-01-01

    The idea behind the marine cloud-brightening (MCB) geoengineering technique is that seeding marine stratocumulus clouds with copious quantities of roughly monodisperse sub-micrometre sea water particles might significantly enhance the cloud droplet number concentration, and thereby the cloud albedo and possibly longevity. This would produce a cooling, which general circulation model (GCM) computations suggest could—subject to satisfactory resolution of technical and scientific problems identified herein—have the capacity to balance global warming up to the carbon dioxide-doubling point. We describe herein an account of our recent research on a number of critical issues associated with MCB. This involves (i) GCM studies, which are our primary tools for evaluating globally the effectiveness of MCB, and assessing its climate impacts on rainfall amounts and distribution, and also polar sea-ice cover and thickness; (ii) high-resolution modelling of the effects of seeding on marine stratocumulus, which are required to understand the complex array of interacting processes involved in cloud brightening; (iii) microphysical modelling sensitivity studies, examining the influence of seeding amount, seed-particle salt-mass, air-mass characteristics, updraught speed and other parameters on cloud–albedo change; (iv) sea water spray-production techniques; (v) computational fluid dynamics studies of possible large-scale periodicities in Flettner rotors; and (vi) the planning of a three-stage limited-area field research experiment, with the primary objectives of technology testing and determining to what extent, if any, cloud albedo might be enhanced by seeding marine stratocumulus clouds on a spatial scale of around 100×100 km. We stress that there would be no justification for deployment of MCB unless it was clearly established that no significant adverse consequences would result. There would also need to be an international agreement firmly in favour of such action

  18. Marine Cloud Brightening

    Energy Technology Data Exchange (ETDEWEB)

    Latham, John; Bower, Keith; Choularton, Tom; Coe, H.; Connolly, P.; Cooper, Gary; Craft, Tim; Foster, Jack; Gadian, Alan; Galbraith, Lee; Iacovides, Hector; Johnston, David; Launder, Brian; Leslie, Brian; Meyer, John; Neukermans, Armand; Ormond, Bob; Parkes, Ben; Rasch, Philip J.; Rush, John; Salter, Stephen; Stevenson, Tom; Wang, Hailong; Wang, Qin; Wood, Robert

    2012-09-07

    The idea behind the marine cloud-brightening (MCB) geoengineering technique is that seeding marine stratocumulus clouds with copious quantities of roughly monodisperse sub-micrometre sea water particles might significantly enhance the cloud droplet number concentration, and thereby the cloud albedo and possibly longevity. This would produce a cooling, which general circulation model (GCM) computations suggest could - subject to satisfactory resolution of technical and scientific problems identified herein - have the capacity to balance global warming up to the carbon dioxide-doubling point. We describe herein an account of our recent research on a number of critical issues associated with MCB. This involves (i) GCM studies, which are our primary tools for evaluating globally the effectiveness of MCB, and assessing its climate impacts on rainfall amounts and distribution, and also polar sea-ice cover and thickness; (ii) high-resolution modelling of the effects of seeding on marine stratocumulus, which are required to understand the complex array of interacting processes involved in cloud brightening; (iii) microphysical modelling sensitivity studies, examining the influence of seeding amount, seedparticle salt-mass, air-mass characteristics, updraught speed and other parameters on cloud-albedo change; (iv) sea water spray-production techniques; (v) computational fluid dynamics studies of possible large-scale periodicities in Flettner rotors; and (vi) the planning of a three-stage limited-area field research experiment, with the primary objectives of technology testing and determining to what extent, if any, cloud albedo might be enhanced by seeding marine stratocumulus clouds on a spatial scale of around 100 km. We stress that there would be no justification for deployment of MCB unless it was clearly established that no significant adverse consequences would result. There would also need to be an international agreement firmly in favour of such action.

  19. Osmoregulation in marine mammals.

    Science.gov (United States)

    Ortiz, R M

    2001-06-01

    Osmoregulation in marine mammals has been investigated for over a century; however, a review of recent advances in our understanding of water and electrolyte balance and of renal function in marine mammals is warranted. The following topics are discussed: (i) kidney structure and urine concentrating ability, (ii) sources of water, (iii) the effects of feeding, fasting and diving, (iv) the renal responses to infusions of varying salinity and (v) hormonal regulation. The kidneys of pinnipeds and cetaceans are reniculate in structure, unlike those of terrestrial mammals (except bears), but this difference does not confer any greater concentrating ability. Pinnipeds, cetaceans, manatees and sea otters can concentrate their urine above the concentration of sea water, but only pinnipeds and otters have been shown to produce urine concentrations of Na+ and Cl- that are similar to those in sea water. This could afford them the capacity to drink sea water and not lose fresh water. However, with few exceptions, drinking is not a common behavior in pinnipeds and cetaceans. Water balance is maintained in these animals via metabolic and dietary water, while incidental ingestion and dietary salt may help maintain electrolyte homeostasis. Unlike most other aquatic mammals, sea otters commonly drink sea water and manatees frequently drink fresh water. Among the various taxonomic groups of marine mammals, the sensitivity of the renin-angiotensin-aldosterone system appears to be influenced by the availability of Na+. The antidiuretic role of vasopressin remains inconclusive in marine mammals, while the natriuretic function of atrial natriuretic peptide has yet to be examined. Ideas on the direction of future studies are presented.

  20. Biofouling in photobioreactors for marine microalgae.

    Science.gov (United States)

    Zeriouh, Ouassim; Reinoso-Moreno, José Vicente; López-Rosales, Lorenzo; Cerón-García, María Del Carmen; Sánchez-Mirón, Asterio; García-Camacho, Francisco; Molina-Grima, Emilio

    2017-12-01

    The economic and/or energetic feasibility of processes based on using microalgae biomass requires an efficient cultivation system. In photobioreactors (PBRs), the adhesion of microalgae to the transparent PBR surfaces leads to biofouling and reduces the solar radiation penetrating the PBR. Light reduction within the PBR decreases biomass productivity and, therefore, the photosynthetic efficiency of the cultivation system. Additionally, PBR biofouling leads to a series of further undesirable events including changes in cell pigmentation, culture degradation, and contamination by invasive microorganisms; all of which can result in the cultivation process having to be stopped. Designing PBR surfaces with proper materials, functional groups or surface coatings, to prevent microalgal adhesion is essential for solving the biofouling problem. Such a significant advance in microalgal biotechnology would enable extended operational periods at high productivity and reduce maintenance costs. In this paper, we review the few systematic studies performed so far and applied the existing thermodynamic and colloidal theories for microbial biofouling formation in order to understand microalgal adhesion on PBR surfaces and the microalgae-microalgae cell interactions. Their relationship to the physicochemical properties of the solid PBR surface, the microalgae cell surfaces, and the ionic strength of the culture medium is discussed. The suitability and the applicability of such theories are reviewed. To this end, an example of biofouling formation on a commercial glass surface is presented for the marine microalgae Nannochloropsis gaditana. It highlights the adhesion dynamics and the inaccuracies of the process and the need for further refinement of previous theories so as to apply them to flowing systems, such as is the case for PBRs used to culture microalgae.

  1. Viruses infecting marine molluscs.

    Science.gov (United States)

    Arzul, Isabelle; Corbeil, Serge; Morga, Benjamin; Renault, Tristan

    2017-07-01

    Although a wide range of viruses have been reported in marine molluscs, most of these reports rely on ultrastructural examination and few of these viruses have been fully characterized. The lack of marine mollusc cell lines restricts virus isolation capacities and subsequent characterization works. Our current knowledge is mostly restricted to viruses affecting farmed species such as oysters Crassostrea gigas, abalone Haliotis diversicolor supertexta or the scallop Chlamys farreri. Molecular approaches which are needed to identify virus affiliation have been carried out for a small number of viruses, most of them belonging to the Herpesviridae and birnaviridae families. These last years, the use of New Generation Sequencing approach has allowed increasing the number of sequenced viral genomes and has improved our capacity to investigate the diversity of viruses infecting marine molluscs. This new information has in turn allowed designing more efficient diagnostic tools. Moreover, the development of experimental infection protocols has answered some questions regarding the pathogenesis of these viruses and their interactions with their hosts. Control and management of viral diseases in molluscs mostly involve active surveillance, implementation of effective bio security measures and development of breeding programs. However factors triggering pathogen development and the life cycle and status of the viruses outside their mollusc hosts still need further investigations. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Marine botany. Second edition

    Energy Technology Data Exchange (ETDEWEB)

    Dawes, C.J. [Univ. of South Florida, Tampa, FL (United States)

    1998-12-01

    Marine plants are a diverse group that include unicellular algae, seaweeds, seagrasses, salt marshes, and mangrove forests. They carry out a variety of ecological functions and serve as the primary producers in coastal wetlands and oceanic waters. The theme that connects such a wide variety of plants is their ecology, which was also emphasized in the 1981 edition. The goal of this revision is to present taxonomic, physiological, chemical, and ecological aspects of marine plants, their adaptations, and how abiotic and biotic factors interact in their communities. The data are presented in a concise, comparative manner in order to identify similarities and differences between communities such as salt marsh and mangroves or subtidal seaweeds and seagrasses. To accomplish this, the text is organized into five chapters that introduce the marine habitats, consider abiotic and biotic factors, and anthropogenic influences on the communities followed by seven chapters that deal with microalgae, seaweeds, salt marshes, mangroves, seagrasses, and coral reefs. Two appendixes are included; one presents simple field techniques and the other is a summary of seaweed uses.

  3. Efficiency of light harvesting in a photosynthetic bacterium adapted to different levels of light.

    Science.gov (United States)

    Timpmann, Kõu; Chenchiliyan, Manoop; Jalviste, Erko; Timney, John A; Hunter, C Neil; Freiberg, Arvi

    2014-10-01

    In this study, we use the photosynthetic purple bacterium Rhodobacter sphaeroides to find out how the acclimation of photosynthetic apparatus to growth conditions influences the rates of energy migration toward the reaction center traps and the efficiency of charge separation at the reaction centers. To answer these questions we measured the spectral and picosecond kinetic fluorescence responses as a function of excitation intensity in membranes prepared from cells grown under different illumination conditions. A kinetic model analysis yielded the microscopic rate constants that characterize the energy transfer and trapping inside the photosynthetic unit as well as the dependence of exciton trapping efficiency on the ratio of the peripheral LH2 and core LH1 antenna complexes, and on the wavelength of the excitation light. A high quantum efficiency of trapping over 80% was observed in most cases, which decreased toward shorter excitation wavelengths within the near infrared absorption band. At a fixed excitation wavelength the efficiency declines with the LH2/LH1 ratio. From the perspective of the ecological habitat of the bacteria the higher population of peripheral antenna facilitates growth under dim light even though the energy trapping is slower in low light adapted membranes. The similar values for the trapping efficiencies in all samples imply a robust photosynthetic apparatus that functions effectively at a variety of light intensities. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Photosynthetic performance of rock-colonising lichens in the Mountain Zebra National Park, South Africa

    Directory of Open Access Journals (Sweden)

    Dirk Wessels

    1993-09-01

    Full Text Available The photosynthetic behaviour of endolithic andepilithic lichens characteristic of sedimentary and volcanic rock was investigated in situ in the Mountain Zebra National Park, South Africa. The park forms part of an inland semi-desert known as the Karoo, in the Cape Province. Temperatures within Balfour sandstone were monitored, the results showing that during the early morning, temperatures within the sandstone were nearly 5@C lower than ambient air temperatures. This may enhance the frequency of water condensing on the sandstone, which may be particularly important for the endoliths Leciclea aff. sarcogynoides and Sarcogyne cf. austroafricana. Maximum photosynthetic rates of the investigated species were found at temperatures between 20@C and 30@C, far higher than the recorded optimum temperatures for lichens from temperate and desert regions. Parmelia chlorea was the most productive species. Compared to the other epiliths, Peltula capensis was found to be a moderately productive species. The photosynthetic gain of Leciclea aff. sarcogynoides and Sarcogyne cf. austro-africana was low, but the photosynthetic gain of these two species still exceeded that of Acarospora sp.

  5. Halogenated 1-Hydroxynaphthalene-2-Carboxanilides Affecting Photosynthetic Electron Transport in Photosystem II

    Czech Academy of Sciences Publication Activity Database

    Goněc, T.; Kos, J.; Pesko, M.; Dohanosová, J.; Oravec, Michal; Liptaj, T.; Králová, K.; Jampílek, J.

    2017-01-01

    Roč. 22, č. 10 (2017), č. článku 1709. ISSN 1420-3049 R&D Projects: GA MŠk(CZ) LO1415 Institutional support: RVO:67179843 Keywords : hydroxynaphthalene-carboxamides * photosynthetic electron transport (PET) inhibition * spinach chloroplasts * structure-activity relationships Subject RIV: CE - Biochemistry Impact factor: 2.861, year: 2016

  6. Determination of microphytobenthos PSII quantum efficiency and photosynthetic activity by means of variable chlorophyll fluorescence

    NARCIS (Netherlands)

    Kromkamp, J.C.; Barranguet, C.; Peene, J.

    1998-01-01

    A pulse amplitude modulated fluorometer (PAM) was used to investigate photosynthetic activity of microphytobenthos on an intertidal mudflat. Spectral irradiance measurements indicate that 75% of the signal detectable by the PAM originates in the upper 150 mu m of the sediment. From the

  7. Features of the determination of photosynthetic pigments in peats of different genesis

    Directory of Open Access Journals (Sweden)

    G. Merkushina

    2013-09-01

    Full Text Available The paper represents the results on working out spectrophotometric procedure for determination of photosynthetic pigments in peat samples of different origin. According to the results of implementation of this technique at conditions of inter-laboratory precision; relative error in determination of chlorophyll "a" does not exceed 20%; chlorophyll «b» - 32%.

  8. Importance of light and oxygen for photochemical reactivation in photosynthetic stromatolite communities after natural sand burial

    NARCIS (Netherlands)

    Perkins, R.; Kromkamp, J.C.; Reid, R.P.

    2007-01-01

    Modern stromatolites at Highborne Cay, Exuma, Bahamas are formed in a high energy environment, where turbulent mixing of the water column supplies the sand particles that are trapped and bound by microbial phototrophs. The photosynthetic communities consist of cyanobacteria within the surface fabric

  9. Potassium starvation limits soybean growth more than the photosynthetic processes across CO2 levels

    Science.gov (United States)

    Potassium (K) deficiency might alter plant response to rising atmospheric carbon dioxide (CO2) and influence growth, and photosynthetic processes differently. To evaluate the combined effects of K and CO2 on soybean photosynthesis, growth, biomass partitioning, and yields, plants were grown under co...

  10. Photosynthetic responses of thalli and isolated protoplasts of Bryopsis hypnoides (Bryopsidales, Chlorophyta) during dehydration

    Science.gov (United States)

    Lü, Fang; Wang, Guangce; Jin, Haochen

    2011-03-01

    Bryopsis hypnoides Lamouroux is a unique intertidal siphonous green alga whose extruded protoplasm can aggregate spontaneously in seawater to form numerous new cells that can develop into mature algal thalli. In this study, the photosynthetic responses during dehydration of both the thalli and protoplasts isolated from B. hypnoides were measured using a Dual-PAM (pulse amplitude modulation)-100 fluorometer. The results show that the photosynthetic rates of B. hypnoides thalli were maintained for an initial period, beyond which continued desiccation resulted in reduced rates of PSI and PSII. However, the photosynthetic performances of the isolated protoplasts dehydrated in air (CO2 concentration 600-700 mg/L) showed a slight increase of Y(II) at 20% water loss, but the rates decreased thereafter with declining water content. When protoplasts were dehydrated in CO2 deficient conditions (CO2 concentration 40-80 mg/L), the values of Y(II) declined steadily with increased dehydration without an initial rise. These results indicated that the thalli and isolated protoplasts of this alga can utilize CO2 in ambient air effectively, and the photosynthetic performances of the isolated protoplasts were significantly different from that of the thalli during dehydration. Thus the protoplasts may be an excellent system for the study of stress tolerance.

  11. Disentangling the contributions of ontogeny and water stress to photosynthetic limitations in almond trees.

    Science.gov (United States)

    Egea, Gregorio; González-Real, María M; Baille, Alain; Nortes, Pedro A; Diaz-Espejo, Antonio

    2011-06-01

    Very few studies have attempted to disentangle the respective role of ontogeny and water stress on leaf photosynthetic attributes. The relative significance of both effects on photosynthetic attributes has been investigated in leaves of field-grown almond trees [Prunus dulcis (Mill.) D. A. Webb] during four growth cycles. Leaf ontogeny resulted in enhanced leaf dry weight per unit area (W(a)), greater leaf dry-to-fresh weight ratio and lower N content per unit of leaf dry weight (N(w)). Concomitantly, area-based maximum carboxylation rate (V(cmax)), maximum electron transport rate (J(max)), mesophyll conductance to CO₂ diffusion (gm)' and light-saturated net photosynthesis (A(max)) declined in both well-watered and water-stressed almond leaves. Although g(m) and stomatal conductance (g(s)) seemed to be co-ordinated, a much stronger coordination in response to ontogeny and prolonged water stress was observed between g(m) and the leaf photosynthetic capacity. Under unrestricted water supply, the leaf age-related decline of A(max) was equally driven by diffusional and biochemical limitations. Under restricted soil water availability, A(max) was mainly limited by g(s) and, to a lesser extent, by photosynthetic capacity and g(m). When both ontogeny and water stress effects were combined, diffusional limitations was the main determinant of photosynthesis limitation, while stomatal and biochemical limitations contributed similarly. © 2011 Blackwell Publishing Ltd.

  12. Abiotic Stresses: Insight into Gene Regulation and Protein Expression in Photosynthetic Pathways of Plants

    Science.gov (United States)

    Nouri, Mohammad-Zaman; Moumeni, Ali; Komatsu, Setsuko

    2015-01-01

    Global warming and climate change intensified the occurrence and severity of abiotic stresses that seriously affect the growth and development of plants, especially, plant photosynthesis. The direct impact of abiotic stress on the activity of photosynthesis is disruption of all photosynthesis components such as photosystem I and II, electron transport, carbon fixation, ATP generating system and stomatal conductance. The photosynthetic system of plants reacts to the stress differently, according to the plant type, photosynthetic systems (C3 or C4), type of the stress, time and duration of the occurrence and several other factors. The plant responds to the stresses by a coordinate chloroplast and nuclear gene expression. Chloroplast, thylakoid membrane, and nucleus are the main targets of regulated proteins and metabolites associated with photosynthetic pathways. Rapid responses of plant cell metabolism and adaptation to photosynthetic machinery are key factors for survival of plants in a fluctuating environment. This review gives a comprehensive view of photosynthesis-related alterations at the gene and protein levels for plant adaptation or reaction in response to abiotic stress. PMID:26343644

  13. Abiotic Stresses: Insight into Gene Regulation and Protein Expression in Photosynthetic Pathways of Plants

    Directory of Open Access Journals (Sweden)

    Mohammad-Zaman Nouri

    2015-08-01

    Full Text Available Global warming and climate change intensified the occurrence and severity of abiotic stresses that seriously affect the growth and development of plants,especially, plant photosynthesis. The direct impact of abiotic stress on the activity of photosynthesis is disruption of all photosynthesis components such as photosystem I and II, electron transport, carbon fixation, ATP generating system and stomatal conductance. The photosynthetic system of plants reacts to the stress differently, according to the plant type, photosynthetic systems (C3 or C4, type of the stress, time and duration of the occurrence and several other factors. The plant responds to the stresses by a coordinate chloroplast and nuclear gene expression. Chloroplast, thylakoid membrane, and nucleus are the main targets of regulated proteins and metabolites associated with photosynthetic pathways. Rapid responses of plant cell metabolism and adaptation to photosynthetic machinery are key factors for survival of plants in a fluctuating environment. This review gives a comprehensive view of photosynthesis-related alterations at the gene and protein levels for plant adaptation or reaction in response to abiotic stress.

  14. Structure and physiological state of photosynthetic apparatus of Equisetum arvense L.

    Directory of Open Access Journals (Sweden)

    Denis M. Sytnikov

    2014-04-01

    Full Text Available The ultrastructure characteristics of photosynthetic tissues and dynamic of content of chloroplast pigments from different organs of horsetail (Equisetum arvense L. were studied. In chlorenchyma cells of lower branches from vegetative shoots the clusters of chloroplasts with differentiated structure have been identified. The key role of lower branches chlorenchyma in chlorophyll accumulation during ontogenesis was ascertained.

  15. Effects of seasonal variation of photosynthetic capacity on the carbon fluxes of a temperate deciduous forest

    Science.gov (United States)

    David Medvigy; Su-Jong Jeong; Kenneth L. Clark; Nicholas S. Skowronski; Karina V. R. Schäfer

    2013-01-01

    Seasonal variation in photosynthetic capacity is an important part of the overall seasonal variability of temperate deciduous forests. However, it has only recently been introduced in a few terrestrial biosphere models, and many models still do not include it. The biases that result from this omission are not well understood. In this study, we use the Ecosystem...

  16. Effects of salt and water stress on plant biomass and photosynthetic ...

    African Journals Online (AJOL)

    Tamarix chinensis Lour. (Tamarisk) is regarded as a potential shrub that improves the marginal lands, and is conversely considered as an invasive species in many areas. This study conducted controlled experiments to investigate the biomass accumulation, allocation and photosynthetic responses of T. chinensis seedlings ...

  17. Regulation of photosynthetic electron flow in isolated chloroplasts by bicarbonate, formate and herbicides

    NARCIS (Netherlands)

    Snel, J.F.H.

    1985-01-01

    This thesis describes some efforts that were made to gain a better understanding of the processes involved in the regulation of photosynthetic electron flow by bicarbonate, formate and herbicides in chloroplasts. In the past decade a large amount of research has been devoted to get insight into the

  18. Response of the photosynthetic system to altered protein composition and changes in environmental conditions

    NARCIS (Netherlands)

    Tóth, T.

    2014-01-01

    The photosynthetic thylakoid membrane has a hierarchically ordered structure containing pigment-protein complexes that capture solar radiation and convert it into chemical energy. Its highly dynamic structure is capable to continuously respond to the altered environmental conditions, e.g., light

  19. [Analysis of photosynthetic characteristics and its influencing factors of medicinal plant Mirabilis himalaica].

    Science.gov (United States)

    Guo, Qi-Qiang; Quan, Hong; Lan, Xiao-Zhong; Li, Lian-Qiang; Li, Hui-E

    2014-07-01

    To study photosynthetic characteristics and its influencing factors in leaves of medicinal plant Mirabilis himalaica, and provide an evidence for guiding artificial planting and improving the quantity. The light-response and diurnal photosynthesis course of leaves at the booting stages of 1-3 year old M. himalaica were measured with LI-6400 system. The Results showed that the light response curves were fitted well by non rectangle hyperbola equation (R2 > or = 0.98). The values of the maximum photosynthetic rate (Pmax) and light use efficiency of three-year old M. himalaica leaves were higher than those of 1-2 year old individuals. The diurnal variation of net photosynthetic rate (Pn) and stomatal conductance (Gs) of 2-3 year old M. himalaica were typical double-peak curves determinately regulated by stomatal conductance. However, transpiration rate (Tr) of 1-3 year old plants leaves were single-peak curve, which was self-protection of harm reduction caused by the higher temperature at noontime. Correlation analysis showed that the changes between photosynthetic active radiation (PFD), air temperature (T ) and Pn, were significant positive related. Therefore, M. himalaica is a typical sun plant, which should be planted under the sufficient sunshine field and prolong the growing ages suitably in order to improve the yield.

  20. Leaf photosynthetic traits scale with hydraulic conductivity and wood density in Panamanian forest canopy trees.

    Science.gov (United States)

    L.S. Santiago; G. Goldstein; F.C. Meinzer; J.B. Fisher; K. Maehado; D. Woodruff; T. Jones

    2004-01-01

    We investigated how water transport capacity, wood density and wood anatomy were related to leaf photosynthetic traits in two lowland forests in Panama. Leaf-specific hydraulic conductivity (kL) of upper branches was positively correlated with maximum rates of net CO2, assimilation per unit leaf area (Aarea...

  1. Effect of nitrogen supply on leaf growth, leaf nitrogen economy and photosynthetic capacity in potato

    NARCIS (Netherlands)

    Vos, J.; Putten, van der P.E.L.

    1998-01-01

    Literature reports show little effect of nitrogen supply on radiation use efficiency in potato and in other dicotyledonous C3 species. This paper tests the hypothesis that potato reduces leaf size rather than leaf nitrogen concentration and photosynthetic capacity when nitrogen is in short supply.

  2. Two Cyanobacterial Photoreceptors Regulate Photosynthetic Light Harvesting by Sensing Teal, Green, Yellow, and Red Light

    Directory of Open Access Journals (Sweden)

    Lisa B. Wiltbank

    2016-02-01

    Full Text Available The genomes of many photosynthetic and nonphotosynthetic bacteria encode numerous phytochrome superfamily photoreceptors whose functions and interactions are largely unknown. Cyanobacterial genomes encode particularly large numbers of phytochrome superfamily members called cyanobacteriochromes. These have diverse light color-sensing abilities, and their functions and interactions are just beginning to be understood. One of the best characterized of these functions is the regulation of photosynthetic light-harvesting antenna composition in the cyanobacterium Fremyella diplosiphon by the cyanobacteriochrome RcaE in response to red and green light, a process known as chromatic acclimation. We have identified a new cyanobacteriochrome named DpxA that maximally senses teal (absorption maximum, 494 nm and yellow (absorption maximum, 568 nm light and represses the accumulation of a key light-harvesting protein called phycoerythrin, which is also regulated by RcaE during chromatic acclimation. Like RcaE, DpxA is a two-component system kinase, although these two photoreceptors can influence phycoerythrin expression through different signaling pathways. The peak responsiveness of DpxA to teal and yellow light provides highly refined color discrimination in the green spectral region, which provides important wavelengths for photosynthetic light harvesting in cyanobacteria. These results redefine chromatic acclimation in cyanobacteria and demonstrate that cyanobacteriochromes can coordinately impart sophisticated light color sensing across the visible spectrum to regulate important photosynthetic acclimation processes.

  3. A remotely sensed pigment index reveals photosynthetic phenology in evergreen conifers

    Science.gov (United States)

    John A. Gamon; K. Fred Huemmrich; Christopher Y. S. Wong; Ingo Ensminger; Steven Garrity; David Y. Hollinger; Asko Noormets; Josep Peñuelas

    2016-01-01

    In evergreen conifers, where the foliage amount changes little with season, accurate detection of the underlying “photosynthetic phenology” from satellite remote sensing has been difficult, presenting challenges for global models of ecosystem carbon uptake. Here, we report a close correspondence between seasonally changing foliar pigment levels, expressed as...

  4. Potential and limitations of inferring ecosystem photosynthetic capacity from leaf functional traits

    Science.gov (United States)

    Talie Musavi; Mirco Migliavacca; Martine Janet van de Weg; Jens Kattge; Georg Wohlfahrt; Peter M. van Bodegom; Markus Reichstein; Michael Bahn; Arnaud Carrara; Tomas F. Domingues; Michael Gavazzi; Damiano Gianelle; Cristina Gimeno; André Granier; Carsten Gruening; Kateřina Havránková; Mathias Herbst; Charmaine Hrynkiw; Aram Kalhori; Thomas Kaminski; Katja Klumpp; Pasi Kolari; Bernard Longdoz; Stefano Minerbi; Leonardo Montagnani; Eddy Moors; Walter C. Oechel; Peter B. Reich; Shani Rohatyn; Alessandra Rossi; Eyal Rotenberg; Andrej Varlagin; Matthew Wilkinson; Christian Wirth; Miguel D. Mahecha

    2016-01-01

    The aim of this study was to systematically analyze the potential and limitations of using plant functional trait observations from global databases versus in situ data to improve our understanding of vegetation impacts on ecosystem functional properties (EFPs). Using ecosystem photosynthetic capacity as an example, we first provide an objective approach to derive...

  5. A kinetic model for estimating net photosynthetic rates of cos lettuce leaves under pulsed light.

    Science.gov (United States)

    Jishi, Tomohiro; Matsuda, Ryo; Fujiwara, Kazuhiro

    2015-04-01

    Time-averaged net photosynthetic rate (P n) under pulsed light (PL) is known to be affected by the PL frequency and duty ratio, even though the time-averaged photosynthetic photon flux density (PPFD) is unchanged. This phenomenon can be explained by considering that photosynthetic intermediates (PIs) are pooled during light periods and then consumed by partial photosynthetic reactions during dark periods. In this study, we developed a kinetic model to estimate P n of cos lettuce (Lactuca sativa L. var. longifolia) leaves under PL based on the dynamics of the amount of pooled PIs. The model inputs are average PPFD, duty ratio, and frequency; the output is P n. The rates of both PI accumulation and consumption at a given moment are assumed to be dependent on the amount of pooled PIs at that point. Required model parameters and three explanatory variables (average PPFD, frequency, and duty ratio) were determined for the simulation using P n values under PL based on several combinations of the three variables. The model simulation for various PL levels with a wide range of time-averaged PPFDs, frequencies, and duty ratios further demonstrated that P n under PL with high frequencies and duty ratios was comparable to, but did not exceed, P n under continuous light, and also showed that P n under PL decreased as either frequency or duty ratio was decreased. The developed model can be used to estimate P n under various light environments where PPFD changes cyclically.

  6. The mechanisms by which phenanthrene affects the photosynthetic apparatus of cucumber leaves.

    Science.gov (United States)

    Jin, Liqiao; Che, Xingkai; Zhang, Zishan; Li, Yuting; Gao, Huiyuan; Zhao, Shijie

    2017-02-01

    Phenanthrene is a polycyclic aromatic hydrocarbon (PAH) that is widely distributed in the environment and seriously affects the growth and development of plants. To clarify the mechanisms of the direct effects of phenanthrene on the plant photosynthetic apparatus, we measured short-term phenanthrene-treated cucumber leaves. Phenanthrene inhibited Rubisco carboxylation activity, decreasing photosynthesis rates (Pn). And phenanthrene inhibited photosystem II (PSII) activity, thereby blocking photosynthetic electron transport. The inhibition of the light and dark reactions decreased the photosynthetic electron transport rate (ETR) and increased the excitation pressure (1-qP). Under high light, the maximum photochemical efficiency of photosystem II (Fv/Fm) in phenanthrene-treated cucumber leaves decreased significantly, but photosystem I (PSI) activity (Δ I/Io) did not. Phenanthrene also caused a J-point rise in the OJIP curve under high light, which indicated that the acceptor side of PSII QA to QB electron transfer was restricted. This was primarily due to the net degradation of D1 protein, which is caused by the accumulation of reactive oxygen species (ROS) in phenanthrene-treated cucumber leaves under high light. This study demonstrated that phenanthrene could directly inhibit photosynthetic electron transport and Rubisco carboxylation activity to decrease net Pn. Under high light, phenanthrene caused the accumulation of ROS, resulting in net increases in D1 protein degradation and consequently causing PSII photoinhibition. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. The effect of leaf age on the photosynthetic rate of Themeda triandra ...

    African Journals Online (AJOL)

    The apparent photosynthesis of progressively older leaves of Themeda triandra was recorded in a controlled environment by means of gas exchange measurements. Photosynthetic rate increased with increasing leaf age and was maximal in the third fully expanded leaf. Thereafter, photosynthesis dropped sharply, but the ...

  8. A comparative study of the photosynthetic capacity in two green tide macroalgae using chlorophyll fluorescence.

    Science.gov (United States)

    Wang, Ying; Qu, Tongfei; Zhao, Xinyu; Tang, Xianghai; Xiao, Hui; Tang, Xuexi

    2016-01-01

    Green tides have occurred in the Yellow Sea, China, every year from 2007 to 2015. The free-floating Ulva prolifera (Müller) J. Agardh was the causative macroalgal species. The co-occurring, attached U. intestinalis was also observed. Photosynthetic capacities were determined using chlorophyll fluorescence in situ and after 7 days lab acclimation, and a significant differences were noted. Pigment composition showed no obvious differences, but concentrations varied significantly, especially chlorophyll b in U. prolifera two times increase was observed after acclimation. The optimal photochemical efficiency of PS II (Fv/Fm) was significantly higher in U. prolifera. Photosynthetic rate (α), maximum relative electron transport rate (rETRmax), and minimum saturating irradiance (Ek), obtained from rapid light response curves (RLCs), showed almost the same photosynthetic physiological status as Fv/Fm. Quenching coefficients and low temperature (77 K) chlorophyll fluorescence emission spectra of thylakoid membranes analysis showed U. prolifera has a better recovery activity and plasticity of PSII than U. intestinalis. Furthermore, energy dissipation via non-photochemical quenching (NPQ) and state transitions showed efficacious photoprotection solution especially in U. prolifera suffered from the severe stresses. Results in the present study suggested that U. prolifera's higher photosynthetic capacity would contribute to its free-floating proliferation, and efficacious photoprotection in addition to favorable oceanographic conditions and high nutrient levels support its growth and aggregation.

  9. Tufted hairgrass (Deschampsia caespitosa) exhibits a lower photosynthetic plasticity than Antarctic hairgrass (D. antarctica).

    Science.gov (United States)

    Bystrzejewska-Piotrowska, Grazyna; Urban, Pawel L

    2009-06-01

    The aim of our work was to assess photosynthetic plasticity of two hairgrass species with different ecological origins (a temperate zone species, Deschampsia caespitosa (L.) Beauv. and an Antarctic species, D. antarctica) and to consider how the anticipated climate change may affect vitality of these plants. Measurements of chlorophyll fluorescence showed that the photosystem II (PSII) quantum efficiency of D. caespitosa decreased during 4 d of incubation at 4 degrees C but it remained stable in D. antarctica. The fluorescence half-rise times were almost always lower in D. caespitosa than in D. antarctica, irrespective of the incubation temperature. These results indicate that the photosynthetic apparatus of D. caespitosa has poorer performance in these conditions. D. caespitosa reached the maximum photosynthesis rate at a higher temperature than D. antarctica although the values obtained at 8 degrees C were similar in both species. The photosynthetic water-use efficiency (photosynthesis-to-transpiration ratio, P/E) emerges as an important factor demonstrating presence of mechanisms which facilitate functioning of a plant in non-optimal conditions. Comparison of the P/E values, which were higher in D. antarctica than in D. caespitosa at low and medium temperatures, confirms a high degree of adjustability of the photosynthetic apparatus in D. antarctica and unveils the lack of such a feature in D. caespitosa.

  10. Photosynthetic light response of flooded cherrybark oak (Quercus pagoda) seedlings grown in two light regimes

    Science.gov (United States)

    Emile S. Gardiner; Ken W. Krauss

    2001-01-01

    Two-year-old cherrybark oak (Quercus pagoda Raf.) seedlings raised in full or partial (27 percent) sunlight were flooded for 30 days to study the effects of light availability and root inundation on photosynthetic light response. Compared with seedlings receiving full sunlight, seedlings receiving partial sunlight developed leaves...

  11. Ethylene potentiates sulfur-mediated reversal of cadmium inhibited photosynthetic responses in mustard

    Directory of Open Access Journals (Sweden)

    Nafees A Khan

    2016-11-01

    Full Text Available The potential of exogenous ethylene and sulfur (S in reversal of cadmium (Cd-inhibited photosynthetic and growth responses in mustard (Brassica juncea L. cv. Pusa Jai Kisan were studied. Plants grown with 50 µM Cd showed increased superoxide and H2O2 accumulation and lipid peroxidation together with increased activity of 1-aminocyclopropane carboxylic acid synthase (ACS and ethylene production and inhibition of photosynthesis and growth. Application of 1 mM SO42− or 200 µL L−1 ethephon (ethylene source influenced photosynthetic and growth performance equally in presence or absence of Cd. However, their combined application synergistically improved photosynthetic performance more in presence of Cd and reduced oxidative stress (lower superoxide and H2O2 accumulation by decreasing ethylene and glucose sensitivity with the increase in cysteine and methionineand a non-proteinogenic thiol (reduced glutathione; GSH contents. The central role of ethylene in potentiating S-mediated reversal of Cd-induced oxidative stress was evident with the use ethylene action inhibitor, norbornadiene (NBD. The application of NBD resulted in decreased thiol production and photosynthetic responses. This suggests that ethylene promotes the effects of S in reversal of adverse effects of Cd, and thus, ethylene modulation may be considered as potential tool to substantiate the S effects in reversal of Cd inhibited photosynthesis and growth in mustard.

  12. An Energy Balance Model to Predict Chemical Partitioning in a Photosynthetic Microbial Mat

    Science.gov (United States)

    Hoehler, Tori M.; Albert, Daniel B.; DesMarais, David J.

    2006-01-01

    Studies of biosignature formation in photosynthetic microbial mat communities offer potentially useful insights with regards to both solar and extrasolar astrobiology. Biosignature formation in such systems results from the chemical transformation of photosynthetically fixed carbon by accessory microorganisms. This fixed carbon represents a source not only of reducing power, but also energy, to these organisms, so that chemical and energy budgets should be coupled. We tested this hypothesis by applying an energy balance model to predict the fate of photosynthetic productivity under dark, anoxic conditions. Fermentation of photosynthetically fixed carbon is taken to be the only source of energy available to cyanobacteria in the absence of light and oxygen, and nitrogen fixation is the principal energy demand. The alternate fate for fixed carbon is to build cyanobacterial biomass with Redfield C:N ratio. The model predicts that, under completely nitrogen-limited conditions, growth is optimized when 78% of fixed carbon stores are directed into fermentative energy generation, with the remainder allocated to growth. These predictions were compared to measurements made on microbial mats that are known to be both nitrogen-limited and populated by actively nitrogen-fixing cyanobacteria. In these mats, under dark, anoxic conditions, 82% of fixed carbon stores were diverted into fermentation. The close agreement between these independent approaches suggests that energy balance models may provide a quantitative means of predicting chemical partitioning within such systems - an important step towards understanding how biological productivity is ultimately partitioned into biosignature compounds.

  13. Enhanced photosynthetic activity in Spinacia oleracea by spectral modification with a photoluminescent light converting material.

    Science.gov (United States)

    Xia, Qi; Batentschuk, Miroslaw; Osvet, Andres; Richter, Peter; Häder, Donat P; Schneider, Juergen; Brabec, Christoph J; Wondraczek, Lothar; Winnacker, Albrecht

    2013-11-04

    The spectral conversion of incident sunlight by appropriate photoluminescent materials has been a widely studied issue for improving the efficiency of photovoltaic solar energy harvesting. By using phosphors with suitable excitation/emission properties, also the light conditions for plants can be adjusted to match the absorption spectra of chlorophyll dyes, in this way increasing the photosynthetic activity of the plant. Here, we report on the application of this principle to a high plant, Spinacia oleracea. We employ a calcium strontium sulfide phosphor doped with divalent europium (Ca0.4Sr0.6S:Eu(2+), CSSE) on a backlight conversion foil in photosynthesis experiments. We show that this phosphor can be used to effectively convert green to red light, centering at a wavelength of ~650 nm which overlaps the absorption peaks of chlorophyll a/b pigments. A measurement system was developed to monitor the photosynthetic activity, expressed as the CO2 assimilation rate of spinach leaves under various controlled light conditions. Results show that under identical external light supply which is rich in green photons, the CO2 assimilation rate can be enhanced by more than 25% when the actinic light is modified by the CSSE conversion foil as compared to a purely reflecting reference foil. These results show that the phosphor could be potentially applied to modify the solar spectrum by converting the green photons into photosynthetically active red photons for improved photosynthetic activity.

  14. Photosynthetic acclimation in relation to nitrogen allocation in cucumber leaves in response to changes in irradiance

    NARCIS (Netherlands)

    Trouwborst, G.; Hogewoning, S.W.; Harbinson, J.; Ieperen, van W.

    2011-01-01

    Leaves deep in canopies can suddenly be exposed to increased irradiances following e.g. gap formation in forests or pruning in crops. Studies on the acclimation of photosynthesis to increased irradiance have mainly focused on the changes in photosynthetic capacity (Amax), although actual irradiance

  15. Natural genetic variation for acclimation of photosynthetic light use efficiency to growth irradiance in Arabidopsis

    NARCIS (Netherlands)

    Rooijen, van R.; Aarts, M.G.M.; Harbinson, J.

    2015-01-01

    Plants are known to be able to acclimate their photosynthesis to the level of irradiance. Here we present the analysis of natural genetic variation for photosynthetic light use efficiency (FPSII) in response to five light environments among 12 genetically diverse Arabidopsis thaliana accessions. We

  16. Photosynthetic control of Arabidopsis leaf cytoplasmic translation initiation by protein phosphorylation.

    Directory of Open Access Journals (Sweden)

    Edouard Boex-Fontvieille

    Full Text Available Photosynthetic CO2 assimilation is the carbon source for plant anabolism, including amino acid production and protein synthesis. The biosynthesis of leaf proteins is known for decades to correlate with photosynthetic activity but the mechanisms controlling this effect are not documented. The cornerstone of the regulation of protein synthesis is believed to be translation initiation, which involves multiple phosphorylation events in Eukaryotes. We took advantage of phosphoproteomic methods applied to Arabidopsis thaliana rosettes harvested under controlled photosynthetic gas-exchange conditions to characterize the phosphorylation pattern of ribosomal proteins (RPs and eukaryotic initiation factors (eIFs. The analyses detected 14 and 11 new RP and eIF phosphorylation sites, respectively, revealed significant CO2-dependent and/or light/dark phosphorylation patterns and showed concerted changes in 13 eIF phosphorylation sites and 9 ribosomal phosphorylation sites. In addition to the well-recognized role of the ribosomal small subunit protein RPS6, our data indicate the involvement of eIF3, eIF4A, eIF4B, eIF4G and eIF5 phosphorylation in controlling translation initiation when photosynthesis varies. The response of protein biosynthesis to the photosynthetic input thus appears to be the result of a complex regulation network involving both stimulating (e.g. RPS6, eIF4B phosphorylation and inhibiting (e.g. eIF4G phosphorylation molecular events.

  17. Selecting microalgae with high lipid productivity and photosynthetic activity under nitrogen starvation

    NARCIS (Netherlands)

    Benvenuti, G.; Bosma, R.; Cuaresma Franco, M.; Janssen, M.G.J.; Barbosa, M.J.; Wijffels, R.H.

    2015-01-01

    An economically feasible microalgal lipid industry heavily relies on the selection of suitable strains. Because microalgae lipid content increases under a range of adverse conditions (e.g. nutrient deprivation, high light intensity), photosynthetic activity is usually strongly reduced. As a

  18. Hydrogen Production by Co-cultures of Rhizopus oryzae and a Photosynthetic Bacterium, Rhodobacter sphaeroides RV

    Science.gov (United States)

    Asada, Yasuo; Ishimi, Katsuhiro; Nagata, Yoko; Wakayama, Tatsuki; Miyake, Jun; Kohno, Hideki

    Hydrogen production with glucose by using co-immobilized cultures of a fungus, Rhizopus oryzae NBRC5384, and a photosynthetic bacterium, Rhodobacter sphaeroides RV, in agar gels was studied. The co-immobilized cultures converted glucose to hydrogen via lactate in a high molar yield of about 8moles of hydrogen per glucose at a maximum under illuminated conditions.

  19. Multiple genes of apparent algal origin suggest ciliates may once have been photosynthetic

    OpenAIRE

    Reyes-Prieto, Adrian; Moustafa, Ahmed; Bhattacharya, Debashish

    2008-01-01

    Plantae (sensu Cavalier-Smith 1981) [1] plastids evolved via primary endosymbiosis whereby a heterotrophic protist enslaved a photosynthetic cyanobacterium. This 'primary' plastid spread into other eukaryotes via secondary endosymbiosis. An important but contentious theory in algal evolution is the chromalveolate hypothesis that posits chromists (cryptophytes, haptophytes, and stramenopiles) and alveolates (ciliates, apicomplexans, and dinoflagellates) share a common ancestor that contained a...

  20. Internal and external factors affecting photosynthetic pigment composition in plants: a meta-analytical approach.

    Science.gov (United States)

    Esteban, Raquel; Barrutia, Oihana; Artetxe, Unai; Fernández-Marín, Beatriz; Hernández, Antonio; García-Plazaola, José Ignacio

    2015-04-01

    Photosynthetic pigment composition has been a major study target in plant ecophysiology during the last three decades. Although more than 2000 papers have been published, a comprehensive evaluation of the responses of photosynthetic pigment composition to environmental conditions is not yet available. After an extensive survey, we compiled data from 525 papers including 809 species (subkingdom Viridiplantae) in which pigment composition was described. A meta-analysis was then conducted to assess the ranges of photosynthetic pigment content. Calculated frequency distributions of pigments were compared with those expected from the theoretical pigment composition. Responses to environmental factors were also analysed. The results revealed that lutein and xanthophyll cycle pigments (VAZ) were highly responsive to the environment, emphasizing the high phenotypic plasticity of VAZ, whereas neoxanthin was very stable. The present meta-analysis supports the existence of relatively narrow limits for pigment ratios and also supports the presence of a pool of free 'unbound' VAZ. Results from this study provide highly reliable ranges of photosynthetic pigment contents as a framework for future research on plant pigments. © 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.