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Sample records for abundant photosynthetic organism

  1. Arsenic biomethylation by photosynthetic organisms

    PubMed Central

    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

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

    PubMed Central

    Lemloh, Marie-Louise; Fromont, Jane; Brümmer, Franz; Usher, Kayley M

    2009-01-01

    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 range of sponges in a wide range

  3. Regulation of Carotenoid Biosynthesis in Photosynthetic Organs.

    PubMed

    Llorente, Briardo

    2016-01-01

    A substantial proportion of the dazzling diversity of colors displayed by living organisms throughout the tree of life is determined by the presence of carotenoids, which most often provide distinctive yellow, orange and red hues. These metabolites play fundamental roles in nature that extend far beyond their importance as pigments. In photosynthetic lineages, carotenoids are essential to sustain life, since they have been exploited to maximize light harvesting and protect the photosynthetic machinery from photooxidative stress. Consequently, photosynthetic organisms have evolved several mechanisms that adjust the carotenoid metabolism to efficiently cope with constantly fluctuating light environments. This chapter will focus on the current knowledge concerning the regulation of the carotenoid biosynthetic pathway in leaves, which are the primary photosynthetic organs of most land plants. PMID:27485221

  4. Nitric oxide in marine photosynthetic organisms.

    PubMed

    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.

  5. Phosphofructokinase Activities in Photosynthetic Organisms 1

    PubMed Central

    Carnal, Nancy Wieland; Black, Clanton C.

    1983-01-01

    A pyrophosphate-dependent phosphofructokinase (PPi-PFK) activity is detectable in extracts of a wide variety of primitive and advanced plants, the Charalean algae, and in the photosynthetic bacterium, Rhodospirillum rubrum. Angiosperms with extractable PPi-PFK activities 4- to 70-fold higher than the respective ATP-PFK activities tend to be succulent and to exhibit CAM. Even though PPi-PFK activity is not detected in crude extracts of some well known CAM plants, e.g. plants in the Crassulaceae, gel filtration of the extract and/or inclusion of the PPi-PFK activator, fructose 2,6-bisphosphate, in the assay reveals that a PPi-PFK activity is present in these species. Fructose 2,6-bisphosphate likewise activates PPi-PFK activities in extracts of C3 and C4 plants. C3 and C4 plant PPi-PFK activities are roughly equivalent to ATP-PFK activities in the same species. PPi-PFK activity is also detected in some bryophytes, lower vascular plants, ferns, and gymnosperms. The Charophytes, advanced algae presumed to be similar to species ancestral to vascular plants, exhibit at least 4-fold higher PPi-PFK than ATP-PFK activities. R. rubrum also exhibits a much higher PPi-PFK activity than ATP-PFK activity. These data indicate that PPi-PFK may serve as an alternate enzyme to ATP-PFK in glycolysis in a wide range of photosynthetic organisms. PMID:16662776

  6. Quantifying Reversible Oxidation of Protein Thiols in Photosynthetic Organisms

    NASA Astrophysics Data System (ADS)

    Slade, William O.; Werth, Emily G.; McConnell, Evan W.; Alvarez, Sophie; Hicks, Leslie M.

    2015-04-01

    Photosynthetic organisms use dynamic post-translational modifications to survive and adapt, which include reversible oxidative modifications of protein thiols that regulate protein structure, function, and activity. Efforts to quantify thiol modifications on a global scale have relied upon peptide derivatization, typically using isobaric tags such as TMT, ICAT, or iTRAQ that are more expensive, less accurate, and provide less proteome coverage than label-free approaches—suggesting the need for improved experimental designs for studies requiring maximal coverage and precision. Herein, we present the coverage and precision of resin-assisted thiol enrichment coupled to label-free quantitation for the characterization of reversible oxidative modifications on protein thiols. Using C. reinhardtii and Arabidopsis as model systems for algae and plants, we quantified 3662 and 1641 unique cysteinyl peptides, respectively, with median coefficient of variation (CV) of 13% and 16%. Further, our method is extendable for the detection of protein abundance changes and stoichiometries of cysteine oxidation. Finally, we demonstrate proof-of-principle for our method, and reveal that exogenous hydrogen peroxide treatment regulates the C. reinhardtii redox proteome by increasing or decreasing the level of oxidation of 501 or 67 peptides, respectively. As protein activity and function is controlled by oxidative modifications on protein thiols, resin-assisted thiol enrichment coupled to label-free quantitation can reveal how intracellular and environmental stimuli affect plant survival and fitness through oxidative stress.

  7. Quantifying reversible oxidation of protein thiols in photosynthetic organisms.

    PubMed

    Slade, William O; Werth, Emily G; McConnell, Evan W; Alvarez, Sophie; Hicks, Leslie M

    2015-04-01

    Photosynthetic organisms use dynamic post-translational modifications to survive and adapt, which include reversible oxidative modifications of protein thiols that regulate protein structure, function, and activity. Efforts to quantify thiol modifications on a global scale have relied upon peptide derivatization, typically using isobaric tags such as TMT, ICAT, or iTRAQ that are more expensive, less accurate, and provide less proteome coverage than label-free approaches--suggesting the need for improved experimental designs for studies requiring maximal coverage and precision. Herein, we present the coverage and precision of resin-assisted thiol enrichment coupled to label-free quantitation for the characterization of reversible oxidative modifications on protein thiols. Using C. reinhardtii and Arabidopsis as model systems for algae and plants, we quantified 3662 and 1641 unique cysteinyl peptides, respectively, with median coefficient of variation (CV) of 13% and 16%. Further, our method is extendable for the detection of protein abundance changes and stoichiometries of cysteine oxidation. Finally, we demonstrate proof-of-principle for our method, and reveal that exogenous hydrogen peroxide treatment regulates the C. reinhardtii redox proteome by increasing or decreasing the level of oxidation of 501 or 67 peptides, respectively. As protein activity and function is controlled by oxidative modifications on protein thiols, resin-assisted thiol enrichment coupled to label-free quantitation can reveal how intracellular and environmental stimuli affect plant survival and fitness through oxidative stress. PMID:25698223

  8. Engineering photosynthetic organisms for the production of biohydrogen.

    PubMed

    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. PMID:24671643

  9. Automated systems to monitor space radiation effect on photosynthetic organisms

    NASA Astrophysics Data System (ADS)

    Esposito, D.; di Costa, F.; Faraloni, C.; Fasolo, F.; Pace, E.; Perosino, M.; Torzillo, G.; Touloupakis, E.; Zanini, A.; Giardi, M. T.

    We developed automated biodevices to obtain, automatically, measures about the space radiation effect on living photosynthetic organisms, which can be used as biomass and oxygen-producing system on shuttles or ISS. Vitality measurements were performed by optical devices (fluorimeters) measuring fluorescence emission. Fluorescence methodology is a well known applied technique for studying photosynthetic activity, and in particular the oxygen-evolving process of photosynthetic organisms. Different strains of unicellular green algae are properly immobilized on agar growth medium and kept under survial light. The biodevices are characterised by the sensibility and selectivity of the biological component response, together with easy use, versatility, miniature size and low cost. We performed experiments in some facilities, in order to understand separately the effect of radiation of different LET, on the biochemical activity (gamma rays at Joint Research Centre -Varese, Italy; fast neutrons at CERF -- SPS beam at CERN -Geneva, Switzerland). The exposure to different radiation beams of the automatic devices, allowed us to test them under stress condition. In one year, these instrument are expected to be sent to space, inside a spacecraft, in order to study the effect of ionising cosmic radiation during an ESA flight.

  10. Tangled evolutionary processes with commonality and diversity in plastidial glycolipid synthesis in photosynthetic organisms.

    PubMed

    Hori, Koichi; Nobusawa, Takashi; Watanabe, Tei; Madoka, Yuka; Suzuki, Hideyuki; Shibata, Daisuke; Shimojima, Mie; Ohta, Hiroyuki

    2016-09-01

    In photosynthetic organisms, the photosynthetic membrane constitutes a scaffold for light-harvesting complexes and photosynthetic reaction centers. Three kinds of glycolipids, namely monogalactosyldiacylglycerol, digalactosyldiacylglycerol, and sulfoquinovosyldiacylglycerol, constitute approximately 80-90% of photosynthetic membrane lipids and are well conserved from tiny cyanobacteria to the leaves of huge trees. These glycolipids perform a wide variety of functions beyond biological membrane formation. In particular, the capability of adaptation to harsh environments through regulation of membrane glycolipid composition is essential for healthy growth and development of photosynthetic organisms. The genome analysis and functional genetics of the model seed plant Arabidopsis thaliana have yielded many new findings concerning the biosynthesis, regulation, and functions of glycolipids. Nevertheless, it remains to be clarified how the complex biosynthetic pathways and well-organized functions of glycolipids evolved in early and primitive photosynthetic organisms, such as cyanobacteria, to yield modern photosynthetic organisms like land plants. Recently, genome data for many photosynthetic organisms have been made available as the fruit of the rapid development of sequencing technology. We also have reported the draft genome sequence of the charophyte alga Klebsormidium flaccidum, which is an intermediate organism between green algae and land plants. Here, we performed a comprehensive phylogenic analysis of glycolipid biosynthesis genes in oxygenic photosynthetic organisms including K. flaccidum. Based on the results together with membrane lipid analysis of this alga, we discuss the evolution of glycolipid synthesis in photosynthetic organisms. This article is part of a Special Issue entitled: Plant Lipid Biology edited by Kent D. Chapman and Ivo Feussner.

  11. Tangled evolutionary processes with commonality and diversity in plastidial glycolipid synthesis in photosynthetic organisms.

    PubMed

    Hori, Koichi; Nobusawa, Takashi; Watanabe, Tei; Madoka, Yuka; Suzuki, Hideyuki; Shibata, Daisuke; Shimojima, Mie; Ohta, Hiroyuki

    2016-09-01

    In photosynthetic organisms, the photosynthetic membrane constitutes a scaffold for light-harvesting complexes and photosynthetic reaction centers. Three kinds of glycolipids, namely monogalactosyldiacylglycerol, digalactosyldiacylglycerol, and sulfoquinovosyldiacylglycerol, constitute approximately 80-90% of photosynthetic membrane lipids and are well conserved from tiny cyanobacteria to the leaves of huge trees. These glycolipids perform a wide variety of functions beyond biological membrane formation. In particular, the capability of adaptation to harsh environments through regulation of membrane glycolipid composition is essential for healthy growth and development of photosynthetic organisms. The genome analysis and functional genetics of the model seed plant Arabidopsis thaliana have yielded many new findings concerning the biosynthesis, regulation, and functions of glycolipids. Nevertheless, it remains to be clarified how the complex biosynthetic pathways and well-organized functions of glycolipids evolved in early and primitive photosynthetic organisms, such as cyanobacteria, to yield modern photosynthetic organisms like land plants. Recently, genome data for many photosynthetic organisms have been made available as the fruit of the rapid development of sequencing technology. We also have reported the draft genome sequence of the charophyte alga Klebsormidium flaccidum, which is an intermediate organism between green algae and land plants. Here, we performed a comprehensive phylogenic analysis of glycolipid biosynthesis genes in oxygenic photosynthetic organisms including K. flaccidum. Based on the results together with membrane lipid analysis of this alga, we discuss the evolution of glycolipid synthesis in photosynthetic organisms. This article is part of a Special Issue entitled: Plant Lipid Biology edited by Kent D. Chapman and Ivo Feussner. PMID:27108062

  12. Function and distribution of bilin biosynthesis enzymes in photosynthetic organisms.

    PubMed

    Dammeyer, Thorben; Frankenberg-Dinkel, Nicole

    2008-10-01

    Bilins are open-chain tetrapyrrole molecules essential for light-harvesting and/or sensing in many photosynthetic organisms. While they serve as chromophores in phytochrome-mediated light-sensing in plants, they additionally function in light-harvesting in cyanobacteria, red algae and cryptomonads. Associated to phycobiliproteins a variety of bile pigments is responsible for the specific light-absorbance properties of the organisms enabling efficient photosynthesis under different light conditions. The initial step of bilin biosynthesis is the cleavage of heme by heme oxygenases (HO) to afford the first linear molecule biliverdin. This reaction is ubiquitously found also in non-photosynthetic organisms. Biliverdin is then further reduced by site specific reductases most of them belonging to the interesting family of ferredoxin-dependent bilin reductases (FDBRs)-a new family of radical oxidoreductases. In recent years much progress has been made in the field of heme oxygenases but even more in the widespread family of FDBRs, revealing novel biochemical FDBR activities, new crystal structures and new ecological aspects, including the discovery of bilin biosynthesis genes in wild marine phage populations. The aim of this review is to summarize and discuss the recent progress in this field and to highlight the new and remaining questions.

  13. High abundances of aerobic anoxygenic photosynthetic bacteria in the South Pacific Ocean.

    PubMed

    Lami, Raphaël; Cottrell, Matthew T; Ras, Joséphine; Ulloa, Osvaldo; Obernosterer, Ingrid; Claustre, Hervé; Kirchman, David L; Lebaron, Philippe

    2007-07-01

    Little is known about the abundance, distribution, and ecology of aerobic anoxygenic phototrophic (AAP) bacteria, particularly in oligotrophic environments, which represent 60% of the ocean. We investigated the abundance of AAP bacteria across the South Pacific Ocean, including the center of the gyre, the most oligotrophic water body of the world ocean. AAP bacteria, Prochlorococcus, and total prokaryotic abundances, as well as bacteriochlorophyll a (BChl a) and divinyl-chlorophyll a concentrations, were measured at several depths in the photic zone along a gradient of oligotrophic conditions. The abundances of AAP bacteria and Prochlorococcus were high, together accounting for up to 58% of the total prokaryotic community. The abundance of AAP bacteria alone was up to 1.94 x 10(5) cells ml(-1) and as high as 24% of the overall community. These measurements were consistent with the high BChl a concentrations (up to 3.32 x 10(-3) microg liter(-1)) found at all stations. However, the BChl a content per AAP bacterial cell was low, suggesting that AAP bacteria are mostly heterotrophic organisms. Interestingly, the biovolume and therefore biomass of AAP bacteria was on average twofold higher than that of other prokaryotic cells. This study demonstrates that AAP bacteria can be abundant in various oligotrophic conditions, including the most oligotrophic regime of the world ocean, and can account for a large part of the bacterioplanktonic carbon stock.

  14. RNA function and phosphorus use by photosynthetic organisms.

    PubMed

    Raven, John A

    2013-12-26

    Phosphorus (P) in RNA accounts for half or more of the total non-storage P in oxygenic photolithotrophs grown in either P-replete or P-limiting growth conditions. Since many natural environments are P-limited for photosynthetic primary productivity, and peak phosphorus fertilizer production is inevitable, the paper analyses what economies in P allocation to RNA could, in principle, increase P-use efficiency of growth (rate of dry matter production per unit organism P). The possibilities of decreasing P allocation to RNA without decreasing growth rate include (1) more widespread down-regulation of RNA production in P-limited organisms, (2) optimal allocation of P to RNA, both spatially among cell compartments and organs, and temporally depending on the stage of growth, and (3) a constant rate of protein synthesis through the diel cycle. Acting on these suggestions would, however, be technically demanding.

  15. RNA function and phosphorus use by photosynthetic organisms

    PubMed Central

    Raven, John A.

    2013-01-01

    Phosphorus (P) in RNA accounts for half or more of the total non-storage P in oxygenic photolithotrophs grown in either P-replete or P-limiting growth conditions. Since many natural environments are P-limited for photosynthetic primary productivity, and peak phosphorus fertilizer production is inevitable, the paper analyses what economies in P allocation to RNA could, in principle, increase P-use efficiency of growth (rate of dry matter production per unit organism P). The possibilities of decreasing P allocation to RNA without decreasing growth rate include (1) more widespread down-regulation of RNA production in P-limited organisms, (2) optimal allocation of P to RNA, both spatially among cell compartments and organs, and temporally depending on the stage of growth, and (3) a constant rate of protein synthesis through the diel cycle. Acting on these suggestions would, however, be technically demanding. PMID:24421782

  16. Engineering photosynthetic organisms for the production of biohydrogen

    DOE PAGES

    Dubini, Alexandra; Ghirardi, Maria L.

    2014-03-27

    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 greenmore » 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. Lastly we provide suggestions for future strategies and potential new techniques to be developed towards an integrated system with optimized hydrogen production.« less

  17. Engineering photosynthetic organisms for the production of biohydrogen

    SciTech Connect

    Dubini, Alexandra; Ghirardi, Maria L.

    2014-03-27

    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. Lastly we provide suggestions for future strategies and potential new techniques to be developed towards an integrated system with optimized hydrogen production.

  18. Distribution and abundance of organic thiols

    NASA Technical Reports Server (NTRS)

    Fahey, R.

    1985-01-01

    The role of glutathione (GSH) in protecting against the toxicity of oxygen and oxygen by products is well established for all eukaryotes studied except Entamoeba histolytica which lacks mitochrondria, chloroplasts, and microtubules. The GSH is not universal among prokaryotes. Entamoeba histolytica does not produce GSH or key enzymes of GSH metabolism. A general method of thiol analysis based upon fluorescent labeling with monobromobimane and HPLC separation of the resulting thiol derivatives was developed to determine the occurrence of GSH and other low molecular weight thiols in bacteria. Glutathione is the major thiol in cyanobacteria and in most bacteria closely related to the purple photosynthetic bacteria, but GSH was not found in archaebacteria, green bacteria, or GRAM positive bacteria. It suggested that glutathione metabolism was incorporated into eukaryotes at the time that mitochondria and chloroplasts were acquired by endosymbiosis. In Gram positive aerobes, coenzyme A occurs at millimolar levels and CoA disulfide reductases are identified. The CoA, rather than glutathione, may function in the oxygen detoxification processes of these organisms.

  19. The essential gene set of a photosynthetic organism.

    PubMed

    Rubin, Benjamin E; Wetmore, Kelly M; Price, Morgan N; Diamond, Spencer; Shultzaberger, Ryan K; Lowe, Laura C; Curtin, Genevieve; Arkin, Adam P; Deutschbauer, Adam; Golden, Susan S

    2015-12-01

    Synechococcus elongatus PCC 7942 is a model organism used for studying photosynthesis and the circadian clock, and it is being developed for the production of fuel, industrial chemicals, and pharmaceuticals. To identify a comprehensive set of genes and intergenic regions that impacts fitness in S. elongatus, we created a pooled library of ∼ 250,000 transposon mutants and used sequencing to identify the insertion locations. By analyzing the distribution and survival of these mutants, we identified 718 of the organism's 2,723 genes as essential for survival under laboratory conditions. The validity of the essential gene set is supported by its tight overlap with well-conserved genes and its enrichment for core biological processes. The differences noted between our dataset and these predictors of essentiality, however, have led to surprising biological insights. One such finding is that genes in a large portion of the TCA cycle are dispensable, suggesting that S. elongatus does not require a cyclic TCA process. Furthermore, the density of the transposon mutant library enabled individual and global statements about the essentiality of noncoding RNAs, regulatory elements, and other intergenic regions. In this way, a group I intron located in tRNA(Leu), which has been used extensively for phylogenetic studies, was shown here to be essential for the survival of S. elongatus. Our survey of essentiality for every locus in the S. elongatus genome serves as a powerful resource for understanding the organism's physiology and defines the essential gene set required for the growth of a photosynthetic organism.

  20. The essential gene set of a photosynthetic organism

    PubMed Central

    Rubin, Benjamin E.; Wetmore, Kelly M.; Price, Morgan N.; Diamond, Spencer; Shultzaberger, Ryan K.; Lowe, Laura C.; Curtin, Genevieve; Arkin, Adam P.; Deutschbauer, Adam; Golden, Susan S.

    2015-01-01

    Synechococcus elongatus PCC 7942 is a model organism used for studying photosynthesis and the circadian clock, and it is being developed for the production of fuel, industrial chemicals, and pharmaceuticals. To identify a comprehensive set of genes and intergenic regions that impacts fitness in S. elongatus, we created a pooled library of ∼250,000 transposon mutants and used sequencing to identify the insertion locations. By analyzing the distribution and survival of these mutants, we identified 718 of the organism’s 2,723 genes as essential for survival under laboratory conditions. The validity of the essential gene set is supported by its tight overlap with well-conserved genes and its enrichment for core biological processes. The differences noted between our dataset and these predictors of essentiality, however, have led to surprising biological insights. One such finding is that genes in a large portion of the TCA cycle are dispensable, suggesting that S. elongatus does not require a cyclic TCA process. Furthermore, the density of the transposon mutant library enabled individual and global statements about the essentiality of noncoding RNAs, regulatory elements, and other intergenic regions. In this way, a group I intron located in tRNALeu, which has been used extensively for phylogenetic studies, was shown here to be essential for the survival of S. elongatus. Our survey of essentiality for every locus in the S. elongatus genome serves as a powerful resource for understanding the organism’s physiology and defines the essential gene set required for the growth of a photosynthetic organism. PMID:26508635

  1. Methods and constructs for expression of foreign proteins in photosynthetic organisms

    DOEpatents

    Laible, Philip D.; Hanson, Deborah K.

    2002-01-01

    A method for expressing and purifying foreign proteins in photosynthetic organisms comprising the simultaneous expression of both the heterologous protein and a means for compartmentalizing or sequestering of the protein.

  2. Unexpected capacity for organic carbon assimilation by Thermosynechococcus elongatus, a crucial photosynthetic model organism.

    PubMed

    Zilliges, Yvonne; Dau, Holger

    2016-04-01

    Genetic modification of key residues of photosystems is essential to identify functionally crucial processes by spectroscopic and crystallographic investigation; the required protein stability favours use of thermophilic species. The currently unique thermophilic photosynthetic model organism is the cyanobacterial genus Thermosynechococcus. We report the ability of Thermosynechococcus elongatus to assimilate organic carbon, specifically D-fructose. Growth in the presence of a photosynthesis inhibitor opens the door towards crucial amino acid substitutions in photosystems by the rescue of otherwise lethal mutations. Yet depression of batch-culture growth after 7 days implies that additional developments are needed. PMID:26935247

  3. Biomineralization by photosynthetic organisms: evidence of coevolution of the organisms and their environment?

    PubMed

    Raven, J A; Giordano, M

    2009-03-01

    Biomineralization is widespread among photosynthetic organisms in the ocean, in inland waters and on land. The most quantitatively important biogeochemical role of land plants today in biomineralization is silica deposition in vascular plants, especially grasses. Terrestrial plants also increase the rate of weathering, providing the soluble substrates for biomineralization on land and in water bodies, a role that has had global biogeochemical impacts since the Devonian. The dominant photosynthetic biomineralizers in today's ocean are diatoms and radiolarians depositing silica and coccolithophores and foraminifera depositing calcium carbonate. Abiotic precipitation of silica from supersaturated seawater in the Precambrian preceded intracellular silicification dominated by sponges, then radiolarians and finally diatoms, with successive declines in the silicic acid concentration in the surface ocean, resulting in some decreases in the extent of silicification and, probably, increases in the silicic acid affinity of the active influx mechanisms. Calcium and bicarbonate concentrations in the surface ocean have generally been supersaturating with respect to the three common calcium carbonate biominerals through geological time, allowing external calcification as well as calcification in compartments within cells or organisms. The forms of calcium carbonate in biominerals, and presumably the evolution of the organisms that produce them, have been influenced by abiotic variations in calcium and magnesium concentrations in seawater, and calcium carbonate deposition has probably also been influenced by carbon dioxide concentration whose variations are in part biologically determined. Overall, there has been less biological feedback on the availability of substrates for calcification than is the case for silicification. PMID:19207569

  4. Abundance of complex organic molecules in comets

    NASA Astrophysics Data System (ADS)

    Biver, N.; Bockelée-Morvan, D.; Debout, V.; Crovisier, J.; Moreno, R.; Boissier, J.; Lis, D.; Colom, P.; Paubert, G.; Dello Russo, N.; Vervack, R.; Weaver, H.

    2014-07-01

    The IRAM-30m submillimetre radio telescope has now an improved sensitivity and versality thanks to its wide-band EMIR receivers and high-resolution FFT spectrometer. Since 2012, we have undertaken ~70 GHz wide spectral surveys in the 1-mm band in several comets: C/2009 P1 (Garradd), C/2011 L4 (PanSTARRS), C/2012 F6 (Lemmon), C/2012 S1 (ISON), and C/2013 R1 (Lovejoy). Since their discovery in comet C/1995 O1 (Hale-Bopp) in 1997 (Bockelée-Morvan et al. 2000, Crovisier et al. 2004a, 2004b), we have detected complex CHO(N)-molecules such as formic acid (HCOOH), formamide (NH_2CHO), acetaldehyde (CH_3CHO), and ethylene glycol ((CH_2OH)_2) in several other comets. HCOOH has now been detected in 6 other comets since 2004, and formamide, ethylene glycol, and acetaldehyde were re-detected for the first time in comets Lemmon or Lovejoy in 2013 (Biver et al. 2014). We will present the abundances relative to water we derive for these species, and the sensitive upper limits we obtain for other complex CHO-bearing molecules. We will discuss the implication of these findings on the origin of cometary material in comparison with observations of such molecules in the interstellar medium.

  5. [Effects of organic fertilizer application rate on leaf photosynthetic characteristics and grain yield of dryland maize].

    PubMed

    Wang, Xiao-Juan; Jia, Zhi-Kuan; Liang, Lian-You; Ding, Rui-Xia; Wang, Min; Li, Han

    2012-02-01

    A 4-year field experiment was conducted at the Heyang Research Station in Weibei dryland to study the effects of organic fertilizer application rate on the leaf photosynthetic characteristics and grain yield of dryland maize. Comparing with applying chemical fertilizer, applying organic fertilizer increased the leaf photosynthetic rate and stomatal conductance, but decreased the leaf intercellular CO2 concentration at each growth stage of maize significantly. With the increasing application rate of organic fertilizer, the leaf photosynthetic rate and stomatal conductance at each growth stage of maize had a gradual increase, while the leaf intercellular CO2 concentration had a gradual decrease. The leaf photosynthesis of maize at each growth stage was controlled by non-stomatal factors, and the application of organic fertilizer reduced the non-stomatal limitation on the photosynthesis performance significantly. The 4-year application of organic fertilizer improved soil nutrient status, and soil nutrients were no longer the main factors limiting the leaf photosynthetic rate and grain yield of maize. PMID:22586967

  6. [Effects of organic fertilizer application rate on leaf photosynthetic characteristics and grain yield of dryland maize].

    PubMed

    Wang, Xiao-Juan; Jia, Zhi-Kuan; Liang, Lian-You; Ding, Rui-Xia; Wang, Min; Li, Han

    2012-02-01

    A 4-year field experiment was conducted at the Heyang Research Station in Weibei dryland to study the effects of organic fertilizer application rate on the leaf photosynthetic characteristics and grain yield of dryland maize. Comparing with applying chemical fertilizer, applying organic fertilizer increased the leaf photosynthetic rate and stomatal conductance, but decreased the leaf intercellular CO2 concentration at each growth stage of maize significantly. With the increasing application rate of organic fertilizer, the leaf photosynthetic rate and stomatal conductance at each growth stage of maize had a gradual increase, while the leaf intercellular CO2 concentration had a gradual decrease. The leaf photosynthesis of maize at each growth stage was controlled by non-stomatal factors, and the application of organic fertilizer reduced the non-stomatal limitation on the photosynthesis performance significantly. The 4-year application of organic fertilizer improved soil nutrient status, and soil nutrients were no longer the main factors limiting the leaf photosynthetic rate and grain yield of maize.

  7. An insight into the mechanisms of nanoceria toxicity in aquatic photosynthetic organisms.

    PubMed

    Rodea-Palomares, Ismael; Gonzalo, Soledad; Santiago-Morales, Javier; Leganés, Francisco; García-Calvo, Eloy; Rosal, Roberto; Fernández-Piñas, Francisca

    2012-10-15

    The effect of nanoceria on two aquatic photosynthetic organisms of ecological relevance, a green alga and a cyanobacterium, is reported. The main bioenergetic process of these organisms, photosynthesis, was studied by measuring both oxygen evolution and chlorophyll a fluorescence emission parameters. Nanoceria significantly inhibited photosynthesis in the cyanobacterium in the entire range of concentrations tested (0.01-100 mg/L), while a dual effect of nanoceria was found in the green alga with slight stimulation at low concentrations and strong inhibition at the highest concentrations tested. Chlorophyll a fluorescence experiments indicated that nanoceria had a significant impact on the primary photochemical processes of photosystem II. The primary cause of the observed photosynthetic inhibition by nanoceria is an excessive level of ROS formation; the results indicated a strong generation of reactive oxygen species (ROS) which caused oxidative damage, as evidenced by lipid peroxidation in both photosynthetic organisms. It is proposed that nanoceria can increase the production of hydrogen peroxide (a normal ROS by-product of light-driven photosynthesis) in both the green alga and the cyanobacterium; through an oxidative reaction, these ROS cause lipid peroxidation, compromising membrane integrity and also seriously impairing photosynthetic performance, eventually leading to cell death.

  8. Did photosynthetic organisms take refuge in ice shadows during Snowball Earth events?

    NASA Astrophysics Data System (ADS)

    Campbell, A. J.; Warren, S. G.; Waddington, E. D.

    2014-12-01

    During the Snowball Earth glaciations of the Neoproterozoic, the Earth's oceans may have been completely covered with ice. Global ice cover, thick enough to block the transmission of light, would have prohibited the survival of photosynthetic eukaryotic organisms living under the ice cover. Fossil records indicate these organisms persisted during the Snowball Earth glaciations. The persistence of these organisms presents a complication to the Snowball Earth theory. If the Earth's oceans were unable to survive in planet's ocean during the Snowball Earth events, then in what environments did these organisms survive? Previously, our research has shown that narrow arms of the ocean, analogous to the modern Red Sea, could have been refugia for photosynthetic eukaryotes during Snowball Earth events. We have demonstrated that for a limited range of climate conditions, ice flow into an arm of the sea is restricted sufficiently to allow for the sea to remain partially free from sea-glacier penetration, a necessary condition for these regions to act as a refugia for photosynthetic eukaryotes during a Snowball Earth event. Presently, we demonstrate that thin-ice zones can form on the leeward sides of obstructions in channels. These thin-ice zones, which we call ice shadows, may have acted as refugia for photosynthetic eukaryotes during Snowball Earth events. We test the ability of ice shadows to form in channels where, in the absence of an obstruction, sea-glacier ice would be thick enough to prohibit the transmission of light. We find that ice shadows can form behind obstructions of various sizes and over a range of climate conditions. This research adds to the range of environments where photosynthetic eukaryotes may have survived during the Snowball Earth events.

  9. Dealing with light: the widespread and multitasking cryptochrome/photolyase family in photosynthetic organisms.

    PubMed

    Fortunato, Antonio Emidio; Annunziata, Rossella; Jaubert, Marianne; Bouly, Jean-Pierre; Falciatore, Angela

    2015-01-01

    Light is essential for the life of photosynthetic organisms as it is a source of energy and information from the environment. Light excess or limitation can be a cause of stress however. Photosynthetic organisms exhibit sophisticated mechanisms to adjust their physiology and growth to the local environmental light conditions. The cryptochrome/photolyase family (CPF) is composed of flavoproteins with similar structures that display a variety of light-dependent functions. This family encompasses photolyases, blue-light activated enzymes that repair ultraviolet-light induced DNA damage, and cryptochromes, known for their photoreceptor functions in terrestrial plants. For this review, we searched extensively for CPFs in the available genome databases to trace the distribution and evolution of this protein family in photosynthetic organisms. By merging molecular data with current knowledge from the functional characterization of CPFs from terrestrial and aquatic organisms, we discuss their roles in (i) photoperception, (ii) biological rhythm regulation and (iii) light-induced stress responses. We also explore their possible implication in light-related physiological acclimation and their distribution in phototrophs living in different environments. The outcome of this structure-function analysis reconstructs the complex scenarios in which CPFs have evolved, as highlighted by the novel functions and biochemical properties of the most recently described family members in algae. PMID:25087009

  10. Organization and expression of photosynthesis genes and operons in anoxygenic photosynthetic proteobacteria.

    PubMed

    Liotenberg, Sylviane; Steunou, Anne-Soisig; Picaud, Martine; Reiss-Husson, Françoise; Astier, Chantal; Ouchane, Soufian

    2008-09-01

    Genes belonging to the same metabolic route are usually organized in operons in microbial genomes. For instance, most genes involved in photosynthesis were found clustered and organized in operons in photosynthetic Alpha- and Betaproteobacteria. The discovery of Gammaproteobacteria with a conserved photosynthetic gene cluster revives the questions on the role and the maintenance of such organization in proteobacteria. In this paper, we report the analysis of the structure and expression of the 14 kb cluster (crtEF-bchCXYZ-pufBALMC-crtADC) in the photosynthetic betaproteobacterium Rubrivivax gelatinosus, with the purpose of understanding the reasons and the biological constraints that might have led to the clustering of photosynthesis genes. The genetic analyses are substantiated by reverse transcription-PCR data which reveal the presence of a transcript encompassing the 14 genes and provide evidence of a polycistronic 'super-operon' organization starting at crtE and ending 14 kb downstream at the crtC gene. Furthermore, genetic analyses suggest that one of the selection pressures that may have driven and maintained the photosynthesis operons/super-operons in proteobacteria could very likely be the coexpression and regulation of the clustered genes/operon.

  11. Diversity and regulation of ATP sulfurylase in photosynthetic organisms

    PubMed Central

    Prioretti, Laura; Gontero, Brigitte; Hell, Ruediger; Giordano, Mario

    2014-01-01

    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 ATPS 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 in algae. Special attention is given to algae ATPS proteins. The focus on algae is the consequence of the fact that a comprehensive investigation of ATPS 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. Remarkably, algal ATPS proteins show a great diversity of isoforms and a high content of cysteine residues, whose positions are often conserved. According to the occurrence of cysteine residues, the ATPS of eukaryotic algae is closer to that of marine cyanobacteria of the genera Synechococcus and Prochlorococcus and is more distant from that of 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. PMID:25414712

  12. Measuring indigenous photosynthetic organisms to detect chemical warefare agents in water

    DOEpatents

    Greenbaum, Elias; Sanders, Charlene A.

    2005-11-15

    A method of testing water to detect the presence of a chemical or biological warfare agent is disclosed. The method is carried out by establishing control data by providing control water containing indigenous organisms but substantially free of a chemical and a biological warfare agent. Then measuring photosynthetic activity of the control water with a fluorometer to obtain control data to compare with test data to detect the presence of the chemical or agent. The test data is gathered by providing test water comprising the same indigenous organisms as contained in the control water. Further, the test water is suspected of containing the chemical or agent to be tested for. Photosynthetic activity is also measured by fluorescence induction in the test water using a fluorometer.

  13. Thermoluminescence as a complementary technique for the toxicological evaluation of chemicals in photosynthetic organisms.

    PubMed

    Repetto, Guillermo; Zurita, Jorge L; Roncel, Mercedes; Ortega, José M

    2015-01-01

    Thermoluminescence is a simple technique very useful for studying electron transfer reactions on photosystem II (standard thermoluminescence) or the level of lipid peroxidation in membranes (high temperature thermoluminescence) in photosynthetic organisms. Both techniques were used to investigate the effects produced on Chlorella vulgaris cells by six compounds: the chemical intermediates bromobenzene and diethanolamine, the antioxidant propyl gallate, the semiconductor indium nitrate, the pesticide sodium monofluoroacetate and the antimalarial drug chloroquine. Electron transfer activity of the photosystem II significantly decreased after the exposure of Chlorella cells to all the six chemicals used. Lipid peroxidation was slightly decreased by the antioxidant propyl gallate, not changed by indium nitrate and very potently stimulated by diethanolamine, chloroquine, sodium monofluoroacetate and bromobenzene. For five of the chemicals studied (not bromobenzene) there is a very good correlation between the cytotoxic effects in Chlorella cells measured by the algal growth inhibition test, and the inhibition of photosystem II activity. The results suggest that one very important effect of these chemicals in Chlorella cells is the inhibition of photosynthetic metabolism by the blocking of photosystem II functionality. In the case of sodium monofluoroacetate, diethanolamine and chloroquine this inhibition seems to be related with the induction of high level of lipid peroxidation in cells that may alter the stability of photosystem II. The results obtained by both techniques supply information that can be used as a supplement to the growth inhibition test and allows a more complete assessment of the effects of a chemical in photosynthetic organisms of aquatic ecosystems.

  14. Light Modulates the Biosynthesis and Organization of Cyanobacterial Carbon Fixation Machinery through Photosynthetic Electron Flow.

    PubMed

    Sun, Yaqi; Casella, Selene; Fang, Yi; Huang, Fang; Faulkner, Matthew; Barrett, Steve; Liu, Lu-Ning

    2016-05-01

    Cyanobacteria have evolved effective adaptive mechanisms to improve photosynthesis and CO2 fixation. The central CO2-fixing machinery is the carboxysome, which is composed of an icosahedral proteinaceous shell encapsulating the key carbon fixation enzyme, Rubisco, in the interior. Controlled biosynthesis and ordered organization of carboxysomes are vital to the CO2-fixing activity of cyanobacterial cells. However, little is known about how carboxysome biosynthesis and spatial positioning are physiologically regulated to adjust to dynamic changes in the environment. Here, we used fluorescence tagging and live-cell confocal fluorescence imaging to explore the biosynthesis and subcellular localization of β-carboxysomes within a model cyanobacterium, Synechococcus elongatus PCC7942, in response to light variation. We demonstrated that β-carboxysome biosynthesis is accelerated in response to increasing light intensity, thereby enhancing the carbon fixation activity of the cell. Inhibition of photosynthetic electron flow impairs the accumulation of carboxysomes, indicating a close coordination between β-carboxysome biogenesis and photosynthetic electron transport. Likewise, the spatial organization of carboxysomes in the cell correlates with the redox state of photosynthetic electron transport chain. This study provides essential knowledge for us to modulate the β-carboxysome biosynthesis and function in cyanobacteria. In translational terms, the knowledge is instrumental for design and synthetic engineering of functional carboxysomes into higher plants to improve photosynthesis performance and CO2 fixation.

  15. Thermoluminescence as a complementary technique for the toxicological evaluation of chemicals in photosynthetic organisms.

    PubMed

    Repetto, Guillermo; Zurita, Jorge L; Roncel, Mercedes; Ortega, José M

    2015-01-01

    Thermoluminescence is a simple technique very useful for studying electron transfer reactions on photosystem II (standard thermoluminescence) or the level of lipid peroxidation in membranes (high temperature thermoluminescence) in photosynthetic organisms. Both techniques were used to investigate the effects produced on Chlorella vulgaris cells by six compounds: the chemical intermediates bromobenzene and diethanolamine, the antioxidant propyl gallate, the semiconductor indium nitrate, the pesticide sodium monofluoroacetate and the antimalarial drug chloroquine. Electron transfer activity of the photosystem II significantly decreased after the exposure of Chlorella cells to all the six chemicals used. Lipid peroxidation was slightly decreased by the antioxidant propyl gallate, not changed by indium nitrate and very potently stimulated by diethanolamine, chloroquine, sodium monofluoroacetate and bromobenzene. For five of the chemicals studied (not bromobenzene) there is a very good correlation between the cytotoxic effects in Chlorella cells measured by the algal growth inhibition test, and the inhibition of photosystem II activity. The results suggest that one very important effect of these chemicals in Chlorella cells is the inhibition of photosynthetic metabolism by the blocking of photosystem II functionality. In the case of sodium monofluoroacetate, diethanolamine and chloroquine this inhibition seems to be related with the induction of high level of lipid peroxidation in cells that may alter the stability of photosystem II. The results obtained by both techniques supply information that can be used as a supplement to the growth inhibition test and allows a more complete assessment of the effects of a chemical in photosynthetic organisms of aquatic ecosystems. PMID:25461748

  16. Elevated temperature altered photosynthetic products in wheat seedlings and organic compounds and biological activity in rhizopshere soil under cadmium stress

    PubMed Central

    Jia, Xia; Zhao, YongHua; Wang, WenKe; He, Yunhua

    2015-01-01

    The objective of this study was to investigate the effects of slightly elevated atmospheric temperature in the spring on photosynthetic products in wheat seedlings and on organic compounds and biological activity in rhizosphere soil under cadmium (Cd) stress. Elevated temperature was associated with increased soluble sugars, reducing sugars, starch, and total sugars, and with decreased amino acids in wheat seedlings under Cd stress. Elevated temperature improved total soluble sugars, free amino acids, soluble phenolic acids, and organic acids in rhizosphere soil under Cd stress. The activity of amylase, phenol oxidase, invertase, β-glucosidase, and l-asparaginase in rhizosphere soil was significantly improved by elevated temperature under Cd stress; while cellulase, neutral phosphatase, and urease activity significantly decreased. Elevated temperature significantly improved bacteria, fungi, actinomycetes, and total microorganisms abundance and fluorescein diacetate activity under Cd stress. In conclusion, slightly elevated atmospheric temperature in the spring improved the carbohydrate levels in wheat seedlings and organic compounds and biological activity in rhizosphere soil under Cd stress in the short term. In addition, elevated atmospheric temperature in the spring stimulated available Cd by affecting pH, DOC, phenolic acids, and organic acids in rhizosphere soil, which resulted in the improvement of the Cd uptake by wheat seedlings. PMID:26395070

  17. Elevated temperature altered photosynthetic products in wheat seedlings and organic compounds and biological activity in rhizopshere soil under cadmium stress.

    PubMed

    Jia, Xia; Zhao, YongHua; Wang, WenKe; He, Yunhua

    2015-01-01

    The objective of this study was to investigate the effects of slightly elevated atmospheric temperature in the spring on photosynthetic products in wheat seedlings and on organic compounds and biological activity in rhizosphere soil under cadmium (Cd) stress. Elevated temperature was associated with increased soluble sugars, reducing sugars, starch, and total sugars, and with decreased amino acids in wheat seedlings under Cd stress. Elevated temperature improved total soluble sugars, free amino acids, soluble phenolic acids, and organic acids in rhizosphere soil under Cd stress. The activity of amylase, phenol oxidase, invertase, β-glucosidase, and l-asparaginase in rhizosphere soil was significantly improved by elevated temperature under Cd stress; while cellulase, neutral phosphatase, and urease activity significantly decreased. Elevated temperature significantly improved bacteria, fungi, actinomycetes, and total microorganisms abundance and fluorescein diacetate activity under Cd stress. In conclusion, slightly elevated atmospheric temperature in the spring improved the carbohydrate levels in wheat seedlings and organic compounds and biological activity in rhizosphere soil under Cd stress in the short term. In addition, elevated atmospheric temperature in the spring stimulated available Cd by affecting pH, DOC, phenolic acids, and organic acids in rhizosphere soil, which resulted in the improvement of the Cd uptake by wheat seedlings.

  18. Elevated temperature altered photosynthetic products in wheat seedlings and organic compounds and biological activity in rhizopshere soil under cadmium stress

    NASA Astrophysics Data System (ADS)

    Jia, Xia; Zhao, Yonghua; Wang, Wenke; He, Yunhua

    2015-09-01

    The objective of this study was to investigate the effects of slightly elevated atmospheric temperature in the spring on photosynthetic products in wheat seedlings and on organic compounds and biological activity in rhizosphere soil under cadmium (Cd) stress. Elevated temperature was associated with increased soluble sugars, reducing sugars, starch, and total sugars, and with decreased amino acids in wheat seedlings under Cd stress. Elevated temperature improved total soluble sugars, free amino acids, soluble phenolic acids, and organic acids in rhizosphere soil under Cd stress. The activity of amylase, phenol oxidase, invertase, β-glucosidase, and L-asparaginase in rhizosphere soil was significantly improved by elevated temperature under Cd stress; while cellulase, neutral phosphatase, and urease activity significantly decreased. Elevated temperature significantly improved bacteria, fungi, actinomycetes, and total microorganisms abundance and fluorescein diacetate activity under Cd stress. In conclusion, slightly elevated atmospheric temperature in the spring improved the carbohydrate levels in wheat seedlings and organic compounds and biological activity in rhizosphere soil under Cd stress in the short term. In addition, elevated atmospheric temperature in the spring stimulated available Cd by affecting pH, DOC, phenolic acids, and organic acids in rhizosphere soil, which resulted in the improvement of the Cd uptake by wheat seedlings.

  19. Elevated temperature altered photosynthetic products in wheat seedlings and organic compounds and biological activity in rhizopshere soil under cadmium stress.

    PubMed

    Jia, Xia; Zhao, YongHua; Wang, WenKe; He, Yunhua

    2015-01-01

    The objective of this study was to investigate the effects of slightly elevated atmospheric temperature in the spring on photosynthetic products in wheat seedlings and on organic compounds and biological activity in rhizosphere soil under cadmium (Cd) stress. Elevated temperature was associated with increased soluble sugars, reducing sugars, starch, and total sugars, and with decreased amino acids in wheat seedlings under Cd stress. Elevated temperature improved total soluble sugars, free amino acids, soluble phenolic acids, and organic acids in rhizosphere soil under Cd stress. The activity of amylase, phenol oxidase, invertase, β-glucosidase, and l-asparaginase in rhizosphere soil was significantly improved by elevated temperature under Cd stress; while cellulase, neutral phosphatase, and urease activity significantly decreased. Elevated temperature significantly improved bacteria, fungi, actinomycetes, and total microorganisms abundance and fluorescein diacetate activity under Cd stress. In conclusion, slightly elevated atmospheric temperature in the spring improved the carbohydrate levels in wheat seedlings and organic compounds and biological activity in rhizosphere soil under Cd stress in the short term. In addition, elevated atmospheric temperature in the spring stimulated available Cd by affecting pH, DOC, phenolic acids, and organic acids in rhizosphere soil, which resulted in the improvement of the Cd uptake by wheat seedlings. PMID:26395070

  20. The xanthophyll cycle pigments, violaxanthin and zeaxanthin, modulate molecular organization of the photosynthetic antenna complex LHCII.

    PubMed

    Janik, Ewa; Bednarska, Joanna; Zubik, Monika; Sowinski, Karol; Luchowski, Rafal; Grudzinski, Wojciech; Matosiuk, Dariusz; Gruszecki, Wieslaw I

    2016-02-15

    The effect of violaxanthin and zeaxanthin, two main carotenoids of the xanthophyll cycle, on molecular organization of LHCII, the principal photosynthetic antenna complex of plants, was studied in a model system based on lipid-protein membranes, by means of analysis of 77 K chlorophyll a fluorescence and "native" electrophoresis. Violaxanthin was found to promote trimeric organization of LHCII, contrary to zeaxanthin which was found to destabilize trimeric structures. Moreover, violaxanthin was found to induce decomposition of oligomeric LHCII structures formed in the lipid phase and characterized by the fluorescence emission band at 715 nm. Both pigments promoted formation of two-component supramolecular structures of LHCII and xanthophylls. The violaxanthin-stabilized structures were composed mostly of LHCII trimers while, the zeaxanthin-stabilized supramolecular structures of LHCII showed more complex organization which depended periodically on the xanthophyll content. The effect of the xanthophyll cycle pigments on molecular organization of LHCII was analyzed based on the results of molecular modeling and discussed in terms of a physiological meaning of this mechanism. Supramolecular structures of LHCII stabilized by violaxanthin, prevent uncontrolled oligomerization of LHCII, potentially leading to excitation quenching, therefore can be considered as structures protecting the photosynthetic apparatus against energy loses at low light intensities.

  1. Chlamydomonas reinhardtii: the model of choice to study mitochondria from unicellular photosynthetic organisms.

    PubMed

    Funes, Soledad; Franzén, Lars-Gunnar; González-Halphen, Diego

    2007-01-01

    Chlamydomonas reinhardtii is a model organism to study photosynthesis, cellular division, flagellar biogenesis, and, more recently, mitochondrial function. It has distinct advantages in comparison to higher plants because it is unicellular, haploid, and amenable to tetrad analysis, and its three genomes are subject to specific transformation. It also has the possibility to grow either photoautotrophically or heterotrophically on acetate, making the assembly of the photosynthetic machinery not essential for cell viability. Methods developed allow the isolation of C. reinhardtii mitochondria free of thylakoid contaminants. We review the general procedures used for the biochemical characterization of mitochondria from this green alga.

  2. Designing artificial photosynthetic devices using hybrid organic-inorganic modules based on polyoxometalates.

    PubMed

    Symes, Mark D; Cogdell, Richard J; Cronin, Leroy

    2013-08-13

    Artificial photosynthesis aims at capturing solar energy and using it to produce storable fuels. However, while there is reason to be optimistic that such approaches can deliver higher energy conversion efficiencies than natural photosynthetic systems, many serious challenges remain to be addressed. Perhaps chief among these is the issue of device stability. Almost all approaches to artificial photosynthesis employ easily oxidized organic molecules as light harvesters or in catalytic centres, frequently in solution with highly oxidizing species. The 'elephant in the room' in this regard is that oxidation of these organic moieties is likely to occur at least as rapidly as oxidation of water, meaning that current device performance is severely curtailed. Herein, we discuss one possible solution to this problem: using self-assembling organic-polyoxometalate hybrid structures to produce compartments inside which the individual component reactions of photosynthesis can occur without such a high incidence of deleterious side reactions.

  3. Characterization of the photosynthetic apparatus of the Eustigmatophycean Nannochloropsis gaditana: evidence of convergent evolution in the supramolecular organization of photosystem I.

    PubMed

    Basso, Stefania; Simionato, Diana; Gerotto, Caterina; Segalla, Anna; Giacometti, Giorgio M; Morosinotto, Tomas

    2014-02-01

    Nannochloropsis gaditana belongs to Eustigmatophyceae, a class of eukaryotic algae resulting from a secondary endosymbiotic event. Species of this class have been poorly characterized thus far but are now raising increasing interest in the scientific community because of their possible application in biofuel production. Nannochloropsis species have a peculiar photosynthetic apparatus characterized by the presence of only chlorophyll a, with violaxanthin and vaucheriaxanthin esters as the most abundant carotenoids. In this study, the photosynthetic apparatus of this species was analyzed by purifying the thylakoids and isolating the different pigment-binding complexes upon mild solubilization. The results from the biochemical and spectroscopic characterization showed that the photosystem II antenna is loosely bound to the reaction center, whereas the association is stronger in photosystem I, with the antenna-reaction center super-complexes surviving purification. Such a supramolecular organization was found to be conserved in photosystem I from several other photosynthetic eukaryotes, even though these taxa are evolutionarily distant. A hypothesis on the possible selective advantage of different associations of the antenna complexes of photosystems I and II is discussed. PMID:24321505

  4. Efficient CO2 Fixation Pathways: Energy Plant: High Efficiency Photosynthetic Organisms

    SciTech Connect

    2012-01-01

    PETRO Project: UCLA is redesigning the carbon fixation pathways of plants to make them more efficient at capturing the energy in sunlight. Carbon fixation is the key process that plants use to convert carbon dioxide (CO2) from the atmosphere into higher energy molecules (such as sugars) using energy from the sun. UCLA is addressing the inefficiency of the process through an alternative biochemical pathway that uses 50% less energy than the pathway used by all land plants. In addition, instead of producing sugars, UCLA’s designer pathway will produce pyruvate, the precursor of choice for a wide variety of liquid fuels. Theoretically, the new biochemical pathway will allow a plant to capture 200% as much CO2 using the same amount of light. The pathways will first be tested on model photosynthetic organisms and later incorporated into other plants, thus dramatically improving the productivity of both food and fuel crops.

  5. 9th International Conference on Tetrapyrrole Photoreceptors of Photosynthetic Organisms (ICTPPO 2009): Meeting Proceedings

    SciTech Connect

    Lagarias, J. Clark

    2009-07-01

    Tetrapyrroles are strongly pigmented heterocyclic molecules that play key roles in the harvesting of light and in its efficient conversion into chemical energy by photosynthetic organisms, including agronomically important plant species. This grant provided financial support for the International Conference on Tetrapyrrole Photoreceptors of Photosynthetic Organisms (ICTPPO 2009), the ninth in the series of ad hoc biennial conferences focused on the structure, function and biotechnological applications of tetrapyrrole photoreceptors, held at Asilomar Conference Center, Monterey CA from July 26 to July 31, 2009. The goal of this meeting was to bring together leading experts in the field of tetrapyrrole photoreceptors and from associated fields with new investigators, to provide critical analyses of the current state of their fields, the challenges and opportunities therein and their most recent unpublished discoveries to stimulate new approaches to address key issues of agricultural and energy significance. Among the 80 participants included 40 PIs (including one Nobelist in chemistry, two members of the US National Academy of Science, and a recent inductee to the Royal Society), 8 senior scientists, 1 DOE program manager, 12 postdoctoral fellows and 20 graduate students representing 13 countries. One third of the formal lecture program was reserved for discussion, and these sessions particularly well supported the conference objectives. In the spirit of the Gordon Conference format adopted for this meeting, the conference proceedings were documented in a bound document available to all participants but were not distributed to the general public. The major output was the cross-breeding of scientists not previously associated with this meeting, both senior and junior, from the fields of photosynthesis/energy conversion, tetrapyrrole metabolism and bioinspired, tetrapyrrole-based light harvesting systems.

  6. PSII-LHCII supercomplex organizations in photosynthetic membrane by coarse-grained simulation.

    PubMed

    Lee, Cheng-Kuang; Pao, Chun-Wei; Smit, Berend

    2015-03-12

    Green plant photosystem II (PSII) and light-harvesting complex II (LHCII) in the stacked grana regions of thylakoid membranes can self-organize into various PSII-LHCII supercomplexes with crystalline or fluid-like supramolecular structures to adjust themselves with external stimuli such as high/low light and temperatures, rendering tunable solar light absorption spectrum and photosynthesis efficiencies. However, the mechanisms controlling the PSII-LHCII supercomplex organizations remain elusive. In this work, we constructed a coarse-grained (CG) model of the thylakoid membrane including lipid molecules and a PSII-LHCII supercomplex considering association/dissociation of moderately bound-LHCIIs. The CG interaction between CG beads were constructed based on electron microscope (EM) experimental results, and we were able to simulate the PSII-LHCII supramolecular organization of a 500 × 500 nm(2) thylakoid membrane, which is compatible with experiments. Our CGMD simulations can successfully reproduce order structures of PSII-LHCII supercomplexes under various protein packing fractions, free-LHCII:PSII ratios, and temperatures, thereby providing insights into mechanisms leading to PSII-LHCII supercomplex organizations in photosynthetic membranes.

  7. High light induced changes in organization, protein profile and function of photosynthetic machinery in Chlamydomonas reinhardtii.

    PubMed

    Nama, Srilatha; Madireddi, Sai Kiran; Devadasu, Elsin Raju; Subramanyam, Rajagopal

    2015-11-01

    The green alga Chlamydomonas (C.) reinhardtii is used as a model organism to understand the efficiency of photosynthesis along with the organization and protein profile of photosynthetic apparatus under various intensities of high light exposure for 1h. Chlorophyll (Chl) a fluorescence induction, OJIPSMT transient was decreased with increase in light intensity indicating the reduction in photochemical efficiency. Further, circular dichroism studies of isolated thylakoids from high light exposed cells showed considerable change in the pigment-pigment interactions and pigment-proteins interactions. Furthermore, the organization of supercomplexes from thylakoids is studied, in which, one of the hetero-trimer of light harvesting complex (LHC) II is affected significantly in comparison to other complexes of LHC's monomers. Also, other supercomplexes, photosystem (PS)II reaction center dimer and PSI complexes are reduced. Additionally, immunoblot analysis of thylakoid proteins revealed that PSII core proteins D1 and D2 were significantly decreased during high light treatment. Similarly, the PSI core proteins PsaC, PsaD and PsaG were drastically changed. Further, the LHC antenna proteins of PSI and PSII were differentially affected. From our results it is clear that LHCs are damaged significantly, consequently the excitation energy is not efficiently transferred to the reaction center. Thus, the photochemical energy transfer from PSII to PSI is reduced. The inference of the study deciphers the structural and functional changes driven by light may therefore provide plants/alga to regulate the light harvesting capacity in excess light conditions.

  8. Cyanide-resistant respiration in photosynthetic organs of freshwater aquatic plants. [Myriophyllum spicatum

    SciTech Connect

    Azcon-Bieto, J.; Murillo, J.; Penuelas, J.

    1987-07-01

    The rate and sensitivity to inhibitors (KCN and salicylhydroxamic acid(SHAM)) of respiratory oxygen uptake has been investigated in photosynthetic organs of several freshwater aquatic plant species. The oxygen uptake rates on a dry weigh basis of angiosperm leaves were generally higher than those of the corresponding stems. Leaves also had a higher chlorophyll content than stems. Respiration of leaves and stems of aquatic angiosperms was generally cyanide-resistant. The cyanide resistance of respiration of whole shoots of two aquatic bryophytes and an alga was lower. These results suggested that the photosynthetic tissues of aquatic plants have a considerable alternative pathway capacity. The angiosperm leaves generally showed the largest alternative path capacity. In all cases, the respiration rate of the aquatic plants studied was inhibited by SHAM alone by about 13 to 31%. These results were used for calculating the actual activities of the cytochrome and alternative pathways. These activities were generally higher in the leaves of angiosperms. The basal oxygen uptake rate of Myriophyllum spicatum leaves was greatly increased by CCCP, either in the presence or in the absence of substrates. These results suggest that respiration was limited by the adenylate system, and not by substrate availability. The increase in the respiratory rate by CCCP was due to a large increase in the activities of both the cytochrome and alternative pathways. The respiration rate of M. spicatum leaves in the presence of substrates was little inhibited by SHAM alone, but the SHAM-resistant rate (that is, the cytochrome path) was greatly stimulated by the further addition of CCCP. Similarly, the cyanide-resistant rate of O/sub 2/ uptake was also increased by the uncoupler.

  9. Glutathionylation in the photosynthetic model organism Chlamydomonas reinhardtii: a proteomic survey.

    PubMed

    Zaffagnini, Mirko; Bedhomme, Mariette; Groni, Hayam; Marchand, Christophe H; Puppo, Carine; Gontero, Brigitte; Cassier-Chauvat, Corinne; Decottignies, Paulette; Lemaire, Stéphane D

    2012-02-01

    Protein glutathionylation is a redox post-translational modification occurring under oxidative stress conditions and playing a major role in cell regulation and signaling. This modification has been mainly studied in nonphotosynthetic organisms, whereas much less is known in photosynthetic organisms despite their important exposure to oxidative stress caused by changes in environmental conditions. We report a large scale proteomic analysis using biotinylated glutathione and streptavidin affinity chromatography that allowed identification of 225 glutathionylated proteins in the eukaryotic unicellular green alga Chlamydomonas reinhardtii. Moreover, 56 sites of glutathionylation were also identified after peptide affinity purification and tandem mass spectrometry. The targets identified belong to a wide range of biological processes and pathways, among which the Calvin-Benson cycle appears to be a major target. The glutathionylation of four enzymes of this cycle, phosphoribulokinase, glyceraldehyde-3-phosphate dehydrogenase, ribose-5-phosphate isomerase, and phosphoglycerate kinase was confirmed by Western blot and activity measurements. The results suggest that glutathionylation could constitute a major mechanism of regulation of the Calvin-Benson cycle under oxidative stress conditions.

  10. Functions of tocopherols in the cells of plants and other photosynthetic organisms.

    PubMed

    Mokrosnop, V M

    2014-01-01

    Tocopherol synthesis has only been observed in photosynthetic organisms (plants, algae and some cyanobacteria). Tocopherol is synthesized in the inner membrane of chloroplasts and distributed between chloroplast membranes, thylakoids and plastoglobules. Physiological significance of tocopherols for human and animal is well-studied, but relatively little is known about their function in plant organisms. Among the best characterized functions oftocopherols in cells is their ability to scavenge and quench reactive oxygen species and fat-soluble by-products of oxidative stress. There are the data on the participation of different mechanisms of α-tocopherol action in protecting photosystem II (PS II) from photoinhibition both by deactivation of singlet oxygen produced by PSII and by reduction of proton permeability of thylakoid membranes, leading to acidification of lumen under high light conditions and activation of violaxanthin de-epoxidase. Additional biological activity of tocopherols, independent of its antioxidant functions have been demonstrated. Basic mechanisms for these effects are connected with the modulation of signal transduction pathways by specific tocopherols and, in some instances, by transcriptional activation of gene expression.

  11. Suitability of different photosynthetic organisms for an extraterrestrial biological life support system.

    PubMed

    Lehto, Kirsi M; Lehto, Harry J; Kanervo, Eira A

    2006-01-01

    In the present era of intensive space and planetary research, efficient life support systems (LSSs) are needed to maintain suitable living conditions when humans move into space, i.e. away from the Earth's atmosphere. Thus far, such suitable conditions on various space flights and on the space stations (Mir and the International Space Station) have been maintained solely via physical and chemical means (transport of O2, H2O and food from the Earth, cleaning and recycling of air and water). However, for long-duration missions to distant destinations, such as exploratory missions to Mars, biological life support systems (BLSSs) may be needed to convert local CO2 and H2O to O2, and to food. As on earth, this conversion process would need to be based on photosynthesis. Use of higher plants and microalgae as BLSS organisms has been intensively studied. Here we review the growth requirements of these two types of photosynthetic organisms, with particular attention to their suitability for use in harsh Martian conditions, i.e. low temperatures, low atmospheric pressure, high CO2 concentration, high UV radiation and dryness.

  12. Suitability of different photosynthetic organisms for an extraterrestrial biological life support system.

    PubMed

    Lehto, Kirsi M; Lehto, Harry J; Kanervo, Eira A

    2006-01-01

    In the present era of intensive space and planetary research, efficient life support systems (LSSs) are needed to maintain suitable living conditions when humans move into space, i.e. away from the Earth's atmosphere. Thus far, such suitable conditions on various space flights and on the space stations (Mir and the International Space Station) have been maintained solely via physical and chemical means (transport of O2, H2O and food from the Earth, cleaning and recycling of air and water). However, for long-duration missions to distant destinations, such as exploratory missions to Mars, biological life support systems (BLSSs) may be needed to convert local CO2 and H2O to O2, and to food. As on earth, this conversion process would need to be based on photosynthesis. Use of higher plants and microalgae as BLSS organisms has been intensively studied. Here we review the growth requirements of these two types of photosynthetic organisms, with particular attention to their suitability for use in harsh Martian conditions, i.e. low temperatures, low atmospheric pressure, high CO2 concentration, high UV radiation and dryness. PMID:16439102

  13. Important photosynthetic contribution from the non-foliar green organs in cotton at the late growth stage.

    PubMed

    Hu, Yuan-Yuan; Zhang, Ya-Li; Luo, Hong-Hai; Li, Wei; Oguchi, Riichi; Fan, Da-Yong; Chow, Wah Soon; Zhang, Wang-Feng

    2012-02-01

    Non-foliar green organs are recognized as important carbon sources after leaves. However, the contribution of each organ to total yield has not been comprehensively studied in relation to the time-course of changes in surface area and photosynthetic activity of different organs at different growth stages. We studied the contribution of leaves, main stem, bracts and capsule wall in cotton by measuring their time-course of surface area development, O(2) evolution capacity and photosynthetic enzyme activity. Because of the early senescence of leaves, non-foliar organs increased their surface area up to 38.2% of total at late growth stage. Bracts and capsule wall showed less ontogenetic decrease in O(2) evolution capacity per area and photosynthetic enzyme activity than leaves at the late growth stage. The total capacity for O(2) evolution of stalks and bolls (bracts plus capsule wall) was 12.7 and 23.7% (total ca. 36.4%), respectively, as estimated by multiplying their surface area by their O(2) evolution capacity per area. We also kept the bolls (from 15 days after anthesis) or main stem (at the early full bolling stage) in darkness for comparison with non-darkened controls. Darkening the bolls and main stem reduced the boll weight by 24.1 and 9%, respectively, and the seed weight by 35.9 and 16.3%, respectively. We conclude that non-foliar organs significantly contribute to the yield at the late growth stage.

  14. The role of peroxisomes in the integration of metabolism and evolutionary diversity of photosynthetic organisms.

    PubMed

    Igamberdiev, Abir U; Lea, Peter J

    2002-08-01

    The peroxisome is a metabolic compartment serving for the rapid oxidation of substrates, a process that is not coupled to energy conservation. In plants and algae, peroxisomes connect biosynthetic and oxidative metabolic routes and compartmentalize potentially lethal steps of metabolism such as the formation of reactive oxygen species and glyoxylate, thus preventing poisoning of the cell and futile recycling. Peroxisomes exhibit properties resembling inside-out vesicles and possess special systems for the import of specific proteins, which form multi-enzyme complexes (metabolons) linking numerous reactions to flavin-dependent oxidation, coupled to the decomposition of hydrogen peroxide by catalase. Hydrogen peroxide and superoxide originating in peroxisomes are important mediators in signal transduction pathways, particularly those involving salicylic acid. By contributing to the synthesis of oxalate, formate and other organic acids, peroxisomes regulate major fluxes of primary and secondary metabolism. The evolutionary diversity of algae has led to the presence of a wide range of enzymes in the peroxisomes that are only similar to higher plants in their direct predecessors, the Charophyceae. The appearance of seed plants was connected to the acquirement by storage tissues, of a peroxisomal fatty acid oxidation function linked to the glyoxylate cycle, which is induced during seed germination and maturation. Rearrangement of the peroxisomal photorespiratory function between different tissues of higher plants led to the appearance of different types of photosynthetic metabolism. The peroxisome may therefore have played a key role in the evolutionary formation of metabolic networks, via establishing interconnections between different metabolic compartments.

  15. Collapsing Aged Culture of the Cyanobacterium Synechococcus elongatus Produces Compound(s) Toxic to Photosynthetic Organisms

    PubMed Central

    Cohen, Assaf; Sendersky, Eleonora; Carmeli, Shmuel; Schwarz, Rakefet

    2014-01-01

    Phytoplankton mortality allows effective nutrient cycling, and thus plays a pivotal role in driving biogeochemical cycles. A growing body of literature demonstrates the involvement of regulated death programs in the abrupt collapse of phytoplankton populations, and particularly implicates processes that exhibit characteristics of metazoan programmed cell death. Here, we report that the cell-free, extracellular fluid (conditioned medium) of a collapsing aged culture of the cyanobacterium Synechococcus elongatus is toxic to exponentially growing cells of this cyanobacterium, as well as to a large variety of photosynthetic organisms, but not to eubacteria. The toxic effect, which is light-dependent, involves oxidative stress, as suggested by damage alleviation by antioxidants, and the very high sensitivity of a catalase-mutant to the conditioned medium. At relatively high cell densities, S. elongatus cells survived the deleterious effect of conditioned medium in a process that required de novo protein synthesis. Application of conditioned medium from a collapsing culture caused severe pigment bleaching not only in S. elongatus cells, but also resulted in bleaching of pigments in a cell free extract. The latter observation indicates that the elicited damage is a direct effect that does not require an intact cell, and therefore, is mechanistically different from the metazoan-like programmed cell death described for phytoplankton. We suggest that S. elongatus in aged cultures are triggered to produce a toxic compound, and thus, this process may be envisaged as a novel regulated death program. PMID:24959874

  16. Photoprotection conferred by changes in photosynthetic protein levels and organization during dehydration of a homoiochlorophyllous resurrection plant.

    PubMed

    Charuvi, Dana; Nevo, Reinat; Shimoni, Eyal; Naveh, Leah; Zia, Ahmad; Adam, Zach; Farrant, Jill M; Kirchhoff, Helmut; Reich, Ziv

    2015-04-01

    During desiccation, homoiochlorophyllous resurrection plants retain most of their photosynthetic apparatus, allowing them to resume photosynthetic activity quickly upon water availability. These plants rely on various mechanisms to prevent the formation of reactive oxygen species and/or protect their tissues from the damage they inflict. In this work, we addressed the issue of how homoiochlorophyllous resurrection plants deal with the problem of excessive excitation/electron pressures during dehydration using Craterostigma pumilum as a model plant. To investigate the alterations in the supramolecular organization of photosynthetic protein complexes, we examined cryoimmobilized, freeze-fractured leaf tissues using (cryo)scanning electron microscopy. These examinations revealed rearrangements of photosystem II (PSII) complexes, including a lowered density during moderate dehydration, consistent with a lower level of PSII proteins, as shown by biochemical analyses. The latter also showed a considerable decrease in the level of cytochrome f early during dehydration, suggesting that initial regulation of the inhibition of electron transport is achieved via the cytochrome b6f complex. Upon further dehydration, PSII complexes are observed to arrange into rows and semicrystalline arrays, which correlates with the significant accumulation of sucrose and the appearance of inverted hexagonal lipid phases within the membranes. As opposed to PSII and cytochrome f, the light-harvesting antenna complexes of PSII remain stable throughout the course of dehydration. Altogether, these results, along with photosynthetic activity measurements, suggest that the protection of retained photosynthetic components is achieved, at least in part, via the structural rearrangements of PSII and (likely) light-harvesting antenna complexes into a photochemically quenched state.

  17. Photoprotection Conferred by Changes in Photosynthetic Protein Levels and Organization during Dehydration of a Homoiochlorophyllous Resurrection Plant1

    PubMed Central

    Charuvi, Dana; Nevo, Reinat; Shimoni, Eyal; Naveh, Leah; Zia, Ahmad; Adam, Zach; Farrant, Jill M.; Kirchhoff, Helmut; Reich, Ziv

    2015-01-01

    During desiccation, homoiochlorophyllous resurrection plants retain most of their photosynthetic apparatus, allowing them to resume photosynthetic activity quickly upon water availability. These plants rely on various mechanisms to prevent the formation of reactive oxygen species and/or protect their tissues from the damage they inflict. In this work, we addressed the issue of how homoiochlorophyllous resurrection plants deal with the problem of excessive excitation/electron pressures during dehydration using Craterostigma pumilum as a model plant. To investigate the alterations in the supramolecular organization of photosynthetic protein complexes, we examined cryoimmobilized, freeze-fractured leaf tissues using (cryo)scanning electron microscopy. These examinations revealed rearrangements of photosystem II (PSII) complexes, including a lowered density during moderate dehydration, consistent with a lower level of PSII proteins, as shown by biochemical analyses. The latter also showed a considerable decrease in the level of cytochrome f early during dehydration, suggesting that initial regulation of the inhibition of electron transport is achieved via the cytochrome b6f complex. Upon further dehydration, PSII complexes are observed to arrange into rows and semicrystalline arrays, which correlates with the significant accumulation of sucrose and the appearance of inverted hexagonal lipid phases within the membranes. As opposed to PSII and cytochrome f, the light-harvesting antenna complexes of PSII remain stable throughout the course of dehydration. Altogether, these results, along with photosynthetic activity measurements, suggest that the protection of retained photosynthetic components is achieved, at least in part, via the structural rearrangements of PSII and (likely) light-harvesting antenna complexes into a photochemically quenched state. PMID:25713340

  18. Light Modulates the Biosynthesis and Organization of Cyanobacterial Carbon Fixation Machinery through Photosynthetic Electron Flow1[OPEN

    PubMed Central

    Sun, Yaqi; Casella, Selene

    2016-01-01

    Cyanobacteria have evolved effective adaptive mechanisms to improve photosynthesis and CO2 fixation. The central CO2-fixing machinery is the carboxysome, which is composed of an icosahedral proteinaceous shell encapsulating the key carbon fixation enzyme, Rubisco, in the interior. Controlled biosynthesis and ordered organization of carboxysomes are vital to the CO2-fixing activity of cyanobacterial cells. However, little is known about how carboxysome biosynthesis and spatial positioning are physiologically regulated to adjust to dynamic changes in the environment. Here, we used fluorescence tagging and live-cell confocal fluorescence imaging to explore the biosynthesis and subcellular localization of β-carboxysomes within a model cyanobacterium, Synechococcus elongatus PCC7942, in response to light variation. We demonstrated that β-carboxysome biosynthesis is accelerated in response to increasing light intensity, thereby enhancing the carbon fixation activity of the cell. Inhibition of photosynthetic electron flow impairs the accumulation of carboxysomes, indicating a close coordination between β-carboxysome biogenesis and photosynthetic electron transport. Likewise, the spatial organization of carboxysomes in the cell correlates with the redox state of photosynthetic electron transport chain. This study provides essential knowledge for us to modulate the β-carboxysome biosynthesis and function in cyanobacteria. In translational terms, the knowledge is instrumental for design and synthetic engineering of functional carboxysomes into higher plants to improve photosynthesis performance and CO2 fixation. PMID:26956667

  19. Organic carbon recovery and photosynthetic bacteria population in an anaerobic membrane photo-bioreactor treating food processing wastewater.

    PubMed

    Chitapornpan, S; Chiemchaisri, C; Chiemchaisri, W; Honda, R; Yamamoto, K

    2013-08-01

    Purple non-sulfur bacteria (PNSB) were cultivated by food industry wastewater in the anaerobic membrane photo-bioreactor. Organic removal and biomass production and characteristics were accomplished via an explicit examination of the long term performance of the photo-bioreactor fed with real wastewater. With the support of infra-red light transmitting filter, PNSB could survive and maintain in the system even under the continual fluctuations of influent wastewater characteristics. The average BOD and COD removal efficiencies were found at the moderate range of 51% and 58%, respectively. Observed photosynthetic biomass yield was 0.6g dried solid/g BOD with crude protein content of 0.41 g/g dried solid. Denaturing gradient gel electrophoretic analysis (DGGE) and 16S rDNA sequencing revealed the presence of Rhodopseudomonas palustris and significant changes in the photosynthetic bacterial community within the system. PMID:23489563

  20. Organic carbon recovery and photosynthetic bacteria population in an anaerobic membrane photo-bioreactor treating food processing wastewater.

    PubMed

    Chitapornpan, S; Chiemchaisri, C; Chiemchaisri, W; Honda, R; Yamamoto, K

    2013-08-01

    Purple non-sulfur bacteria (PNSB) were cultivated by food industry wastewater in the anaerobic membrane photo-bioreactor. Organic removal and biomass production and characteristics were accomplished via an explicit examination of the long term performance of the photo-bioreactor fed with real wastewater. With the support of infra-red light transmitting filter, PNSB could survive and maintain in the system even under the continual fluctuations of influent wastewater characteristics. The average BOD and COD removal efficiencies were found at the moderate range of 51% and 58%, respectively. Observed photosynthetic biomass yield was 0.6g dried solid/g BOD with crude protein content of 0.41 g/g dried solid. Denaturing gradient gel electrophoretic analysis (DGGE) and 16S rDNA sequencing revealed the presence of Rhodopseudomonas palustris and significant changes in the photosynthetic bacterial community within the system.

  1. Anatomy of a cluster IDP. Part 2: Noble gas abundances, trace element geochemistry, isotopic abundances, and trace organic chemistry of several fragments from L2008#5

    NASA Technical Reports Server (NTRS)

    Thomas, K. L.; Clemett, S. J.; Flynn, G. J.; Keller, L. P.; Mckay, David S.; Messenger, S.; Nier, A. O.; Schlutter, D. J.; Sutton, S. R.; Walker, R. M.

    1994-01-01

    The topics discussed include the following: noble gas content and release temperatures; trace element abundances; heating summary of cluster fragments; isotopic measurements; and trace organic chemistry.

  2. Designer organisms for photosynthetic production of ethanol from carbon dioxide and water

    DOEpatents

    Lee, James Weifu

    2011-07-05

    The present invention provides a revolutionary photosynthetic ethanol production technology based on designer transgenic plants, algae, or plant cells. The designer plants, designer algae, and designer plant cells are created such that the endogenous photosynthesis regulation mechanism is tamed, and the reducing power (NADPH) and energy (ATP) acquired from the photosynthetic water splitting and proton gradient-coupled electron transport process are used for immediate synthesis of ethanol (CH.sub.3CH.sub.2OH) directly from carbon dioxide (CO.sub.2) and water (H.sub.2O). The ethanol production methods of the present invention completely eliminate the problem of recalcitrant lignocellulosics by bypassing the bottleneck problem of the biomass technology. The photosynthetic ethanol-production technology of the present invention is expected to have a much higher solar-to-ethanol energy-conversion efficiency than the current technology and could also help protect the Earth's environment from the dangerous accumulation of CO.sub.2 in the atmosphere.

  3. Inhibitory effect of organic carbon on CO₂ fixing by non-photosynthetic microbial community isolated from the ocean.

    PubMed

    Hu, Jia-jun; Wang, Lei; Zhang, Shi-ping; Wang, Yuan-qing; Xi, Xue-fei

    2011-07-01

    The inhibitory effect of organic carbon on CO(2) fixation (CF) by the non-photosynthetic microbial community (NPMC) and its mechanism were studied. The results showed that different concentrations of glucose inhibited CF to some extent. However, when these microorganisms pre-cultured with glucose were re-cultured without organic carbon, their CF efficiency differed significantly from the control based on the glucose concentration in the pre-culture. ATP as bioenergy and NADH as reductant had no obvious inhibitory effect on CF; conversely, they improved CF efficiency to some extent, especially when both were present simultaneously. These results implied that not all organic materials inhibited CF by NPMC, and only those that acted as good carbon sources, such as glucose, inhibited CF. Moreover, some metabolites generated during the catabolism of glucose by heterotrophic metabolism of NPMC might inhibit CF, while other cumulated materials present in the cell interior, such as ATP and NADH, might improve CF.

  4. Automated Microscopy: Macro Language Controlling a Confocal Microscope and its External Illumination: Adaptation for Photosynthetic Organisms.

    PubMed

    Steinbach, Gábor; Kaňa, Radek

    2016-04-01

    Photosynthesis research employs several biophysical methods, including the detection of fluorescence. Even though fluorescence is a key method to detect photosynthetic efficiency, it has not been applied/adapted to single-cell confocal microscopy measurements to examine photosynthetic microorganisms. Experiments with photosynthetic cells may require automation to perform a large number of measurements with different parameters, especially concerning light conditions. However, commercial microscopes support custom protocols (through Time Controller offered by Olympus or Experiment Designer offered by Zeiss) that are often unable to provide special set-ups and connection to external devices (e.g., for irradiation). Our new system combining an Arduino microcontroller with the Cell⊕Finder software was developed for controlling Olympus FV1000 and FV1200 confocal microscopes and the attached hardware modules. Our software/hardware solution offers (1) a text file-based macro language to control the imaging functions of the microscope; (2) programmable control of several external hardware devices (light sources, thermal controllers, actuators) during imaging via the Arduino microcontroller; (3) the Cell⊕Finder software with ergonomic user environment, a fast selection method for the biologically important cells and precise positioning feature that reduces unwanted bleaching of the cells by the scanning laser. Cell⊕Finder can be downloaded from http://www.alga.cz/cellfinder. The system was applied to study changes in fluorescence intensity in Synechocystis sp. PCC6803 cells under long-term illumination. Thus, we were able to describe the kinetics of phycobilisome decoupling. Microscopy data showed that phycobilisome decoupling appears slowly after long-term (>1 h) exposure to high light. PMID:27050040

  5. Automated Microscopy: Macro Language Controlling a Confocal Microscope and its External Illumination: Adaptation for Photosynthetic Organisms.

    PubMed

    Steinbach, Gábor; Kaňa, Radek

    2016-04-01

    Photosynthesis research employs several biophysical methods, including the detection of fluorescence. Even though fluorescence is a key method to detect photosynthetic efficiency, it has not been applied/adapted to single-cell confocal microscopy measurements to examine photosynthetic microorganisms. Experiments with photosynthetic cells may require automation to perform a large number of measurements with different parameters, especially concerning light conditions. However, commercial microscopes support custom protocols (through Time Controller offered by Olympus or Experiment Designer offered by Zeiss) that are often unable to provide special set-ups and connection to external devices (e.g., for irradiation). Our new system combining an Arduino microcontroller with the Cell⊕Finder software was developed for controlling Olympus FV1000 and FV1200 confocal microscopes and the attached hardware modules. Our software/hardware solution offers (1) a text file-based macro language to control the imaging functions of the microscope; (2) programmable control of several external hardware devices (light sources, thermal controllers, actuators) during imaging via the Arduino microcontroller; (3) the Cell⊕Finder software with ergonomic user environment, a fast selection method for the biologically important cells and precise positioning feature that reduces unwanted bleaching of the cells by the scanning laser. Cell⊕Finder can be downloaded from http://www.alga.cz/cellfinder. The system was applied to study changes in fluorescence intensity in Synechocystis sp. PCC6803 cells under long-term illumination. Thus, we were able to describe the kinetics of phycobilisome decoupling. Microscopy data showed that phycobilisome decoupling appears slowly after long-term (>1 h) exposure to high light.

  6. Molecular bases and photobiological consequences of light intensity adaptation in photosynthetic organisms

    SciTech Connect

    Chen, Y-B.; Durnford, D.; Koblizek, M.; Falkowski, P. G.

    2003-02-10

    By applying a combination of light transitions, uncouplers, and inhibitors of photosynthetic electron transport inhibitors we modulate the redox poise of many components in the plastid and examine the pattern of expression of cab1 gene. This gene encodes the major light harvesting protein that services photosystem II. While our results have confirmed our own previous finding that light intensity regulation of cab1 gene expression is signaled by the redox state of the PQ pool, we have also identified additional sensor(s) located in the PET chain.

  7. The activated sludge ecosystem contains a core community of abundant organisms

    PubMed Central

    Saunders, Aaron M; Albertsen, Mads; Vollertsen, Jes; Nielsen, Per H

    2016-01-01

    Understanding the microbial ecology of a system requires that the observed population dynamics can be linked to their metabolic functions. However, functional characterization is laborious and the choice of organisms should be prioritized to those that are frequently abundant (core) or transiently abundant, which are therefore putatively make the greatest contribution to carbon turnover in the system. We analyzed the microbial communities in 13 Danish wastewater treatment plants with nutrient removal in consecutive years and a single plant periodically over 6 years, using Illumina sequencing of 16S ribosomal RNA amplicons of the V4 region. The plants contained a core community of 63 abundant genus-level operational taxonomic units (OTUs) that made up 68% of the total reads. A core community consisting of abundant OTUs was also observed within the incoming wastewater to three plants. The net growth rate for individual OTUs was quantified using mass balance, and it was found that 10% of the total reads in the activated sludge were from slow or non-growing OTUs, and that their measured abundance was primarily because of immigration with the wastewater. Transiently abundant organisms were also identified. Among them the genus Nitrotoga (class Betaproteobacteria) was the most abundant putative nitrite oxidizer in a number of activated sludge plants, which challenges previous assumptions that Nitrospira (phylum Nitrospirae) are the primary nitrite-oxidizers in activated sludge systems with nutrient removal. PMID:26262816

  8. Bird diversity and abundance in organic and conventional apple orchards in northern Japan

    PubMed Central

    Katayama, Naoki

    2016-01-01

    Many studies have investigated the benefits of agri-environmental schemes, such as organic farming, on biodiversity conservation in annual systems, but their effectiveness in perennial systems is less well understood, particularly in bird communities in temperate regions of Asia. This study examined the effects of organic farming practices on species richness and abundance of breeding birds in apple orchards in northern Japan. Bird counts were conducted in six pairs of organic and conventional orchards during the breeding season in April and May 2015. The total species richness of birds, estimated by sample- and coverage-based rarefaction and extrapolation curves, was greater in organic orchards than in conventional orchards. Among the three dietary guilds (insectivore, granivore, and omnivore), only insectivorous species were more abundant in organic orchards than in conventional ones. This study offers the first quantitative evidence that organic farming can be beneficial for enhancing the diversity of birds, particularly of insectivores, in fruit orchards in Japan. PMID:27677408

  9. Consequences of organic farming and landscape heterogeneity for species richness and abundance of farmland birds.

    PubMed

    Smith, Henrik G; Dänhardt, Juliana; Lindström, Ake; Rundlöf, Maj

    2010-04-01

    It has been suggested that organic farming may benefit farmland biodiversity more in landscapes that have lost a significant part of its former landscape heterogeneity. We tested this hypothesis by comparing bird species richness and abundance during the breeding season in organic and conventional farms, matched to eliminate all differences not directly linked to the farming practice, situated in either homogeneous plains with only a little semi-natural habitat or in heterogeneous farmland landscapes with abundant field borders and semi-natural grasslands. The effect of farm management on species richness interacted with landscape structure, such that there was a positive relationship between organic farming and diversity only in homogeneous landscapes. This pattern was mainly dependent on the species richness of passerine birds, in particular those that were invertebrate feeders. Species richness of non-passerines was positively related to organic farming independent of the landscape context. Bird abundance was positively related to landscape heterogeneity but not to farm management. This was mainly because the abundance of passerines, particularly invertebrate feeders, was positively related to landscape heterogeneity. We suggest that invertebrate feeders particularly benefit from organic farming because of improved foraging conditions through increased invertebrate abundances in otherwise depauperate homogeneous landscapes. Although many seed-eaters also benefit from increased insect abundance, they may also utilize crop seed resources in homogeneous landscapes and conventional farms. The occurrence of an interactive effect of organic farming and landscape heterogeneity on bird diversity will have consequences for the optimal allocation of resources to restore the diversity of farmland birds.

  10. Determination of photophysical parameters of chlorophyll α in photosynthetic organisms using the method of nonlinear laser fluorimetry

    NASA Astrophysics Data System (ADS)

    Gostev, T. S.; Fadeev, V. V.

    2011-05-01

    We study the possibility of solving the multiparameter inverse problem of nonlinear laser fluorimetry of molecular systems with high local concentration of fluorophores (by the example of chlorophyll α molecules in photosynthetic organisms). The algorithms are proposed that allow determination of up to four photophysical parameters of chlorophyll α from the experimental fluorescence saturation curves. The uniqueness and stability of the inverse problem solution obtained using the proposed algorithms were assessed numerically. The laser spectrometer, designed in the course of carrying out the work and aimed at nonlinear laser fluorimetry in the quasi-stationary and nonstationary excitation regimes is described. The algorithms, proposed in this paper, are tested on pure cultures of microalgae Chlorella pyrenoidosa and Chlamydomonas reinhardtii under different functional conditions.

  11. Determination of photophysical parameters of chlorophyll {alpha} in photosynthetic organisms using the method of nonlinear laser fluorimetry

    SciTech Connect

    Gostev, T S; Fadeev, V V

    2011-05-31

    We study the possibility of solving the multiparameter inverse problem of nonlinear laser fluorimetry of molecular systems with high local concentration of fluorophores (by the example of chlorophyll {alpha} molecules in photosynthetic organisms). The algorithms are proposed that allow determination of up to four photophysical parameters of chlorophyll {alpha} from the experimental fluorescence saturation curves. The uniqueness and stability of the inverse problem solution obtained using the proposed algorithms were assessed numerically. The laser spectrometer, designed in the course of carrying out the work and aimed at nonlinear laser fluorimetry in the quasi-stationary and nonstationary excitation regimes is described. The algorithms, proposed in this paper, are tested on pure cultures of microalgae Chlorella pyrenoidosa and Chlamydomonas reinhardtii under different functional conditions. (optical technologies in biophysics and medicine)

  12. Chemoselective single-site Earth-abundant metal catalysts at metal-organic framework nodes.

    PubMed

    Manna, Kuntal; Ji, Pengfei; Lin, Zekai; Greene, Francis X; Urban, Ania; Thacker, Nathan C; Lin, Wenbin

    2016-01-01

    Earth-abundant metal catalysts are critically needed for sustainable chemical synthesis. Here we report a simple, cheap and effective strategy of producing novel earth-abundant metal catalysts at metal-organic framework (MOF) nodes for broad-scope organic transformations. The straightforward metalation of MOF secondary building units (SBUs) with cobalt and iron salts affords highly active and reusable single-site solid catalysts for a range of organic reactions, including chemoselective borylation, silylation and amination of benzylic C-H bonds, as well as hydrogenation and hydroboration of alkenes and ketones. Our structural, spectroscopic and kinetic studies suggest that chemoselective organic transformations occur on site-isolated, electron-deficient and coordinatively unsaturated metal centres at the SBUs via σ-bond metathesis pathways and as a result of the steric environment around the catalytic site. MOFs thus provide a novel platform for the development of highly active and affordable base metal catalysts for the sustainable synthesis of fine chemicals.

  13. Chemoselective single-site Earth-abundant metal catalysts at metal-organic framework nodes

    NASA Astrophysics Data System (ADS)

    Manna, Kuntal; Ji, Pengfei; Lin, Zekai; Greene, Francis X.; Urban, Ania; Thacker, Nathan C.; Lin, Wenbin

    2016-08-01

    Earth-abundant metal catalysts are critically needed for sustainable chemical synthesis. Here we report a simple, cheap and effective strategy of producing novel earth-abundant metal catalysts at metal-organic framework (MOF) nodes for broad-scope organic transformations. The straightforward metalation of MOF secondary building units (SBUs) with cobalt and iron salts affords highly active and reusable single-site solid catalysts for a range of organic reactions, including chemoselective borylation, silylation and amination of benzylic C-H bonds, as well as hydrogenation and hydroboration of alkenes and ketones. Our structural, spectroscopic and kinetic studies suggest that chemoselective organic transformations occur on site-isolated, electron-deficient and coordinatively unsaturated metal centres at the SBUs via σ-bond metathesis pathways and as a result of the steric environment around the catalytic site. MOFs thus provide a novel platform for the development of highly active and affordable base metal catalysts for the sustainable synthesis of fine chemicals.

  14. SEASONAL ABUNDANCE OF ORGANIC MOLECULAR MARKERS IN URBAN PARTICULATE MATTER FROM PHILADELPHIA, PA

    EPA Science Inventory

    Organic molecular markers were measured in airborne particulate matter (PM10) from the City of Philadelphia North Broad Street air quality monitoring site to identify the seasonal abundances of key tracer compounds together with their dominant sources. Daily PM10...

  15. Effects of microgravityon the structural organization of Brassica rapa photosynthetic appartus

    NASA Astrophysics Data System (ADS)

    Adamchuk, N.; Kordyum, E.; Guikema, J.

    Leaf mesophyll cells of 13- and 15-day old Brassica rapa plants grown on board the space shuttle Columbia (STS-87) and in the ground control have been investigated using the methods of light and electron microscopy. 13-day old plants were fixed on orbit and 15-day old plants were fixed after landing. It was shown the essential differences in leaf mesophyll quantitative anatomical and ultrastructural characteristics between spaceflight and ground control variants. Both the volume of palisade parenchyma cells and a number of chloroplasts in those cells increased in spaceflight samples. Simultaneusly, a chloroplast size decreased together with increasing of a relative volume of stromal thylakoids, starch grains and plastoglobuli. It was also noted increasing of stromal thylakoid length. In the same time, both a total length of thylakoids in granae and the grana number diminished in space flight. In addition, the interthylakoid space could be expended and the thylakoid length was more variable in chloroplast granae on microgravity, that correlated with a shrinkage of thylakoids in granal stacks. The obtained data a er discussed with the questions on both the photosynthetic apparatus sensitivity to gravity and its adaptive possibility to microgravity.

  16. A device to study the effect of space radiation on photosynthetic organisms.

    PubMed

    Angelini, G; Ragni, P; Esposito, D; Giardi, P; Pompili, M L; Moscardelli, R; Giardi, M T

    2001-01-01

    This research concerns the study of the effects of ionising space radiation on the oxygen-evolving activity of algae and cyanobacteria, focusing our attention on Photosystem II (PS-II), the oxygen-evolving complex. These microorganisms as higher plants, can use light energy to split water molecules and evolve oxygen in a process that produce storable energy-rich products from atmospheric carbon dioxide. Algae and cyanobacteria which can grow in the presence of nutrients and carbonate are expected to be utilised to maintain an oxygen-atmosphere and to constitute biomass in space shuttles. Irradiation was performed in gamma 60Co-sources of different activities; fluorescence techniques in vivo and SDS-PAGE analysis in vitro were used to determine PS-II efficiency during radiation stress. We determined the radiation target on PS-II by immunoblot. We built a miniaturised growth box that preserves constant pressure and temperature to measure automatically photosynthetic activity by a fluorescence sensor, directly in space during a mission in an ASI balloon.

  17. Comparative Transcriptional Profiling Established the Awn as the Major Photosynthetic Organ of the Barley Spike while the Lemma and the Palea Primarily Protect the Seed

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The lemma, palea, and awn of barley are photosynthetic organs and supply the developing seed with carbohydrates. In addition, the lemma and the palea cover the seed and protect it from pathogens and insects. In spite of the important role they play, there is very little information about gene expr...

  18. Mannose-6-Phosphate Reductase, a Key Enzyme in Photoassimilate Partitioning, Is Abundant and Located in the Cytosol of Photosynthetically Active Cells of Celery (Apium graveolens L.) Source Leaves.

    PubMed

    Everard, J. D.; Franceschi, V. R.; Loescher, W. H.

    1993-06-01

    Mannitol, a major photosynthetic product and transport carbohydrate in many plants, accounts for approximately 50% of the carbon fixed by celery (Apium graveolens L.) leaves. Previous subfractionation studies of celery leaves indicated that the enzymes for mannitol synthesis were located in the cytosol, but these data are inconsistent with that published for the sites of sugar alcohol synthesis in other families and taxa, including apple (Malus) and a brown alga (Fucus). Using antibodies to a key synthetic enzyme, NADPH-dependent mannose-6-phosphate reductase (M6PR), and immunocytochemical techniques, we have resolved both the inter-cellular and intracellular sites of mannitol synthesis. In leaves, M6PR was found only in cells containing ribulose-1,5-bisphosphate carboxylase/oxygenase. M6PR was almost exclusively cytosolic in these cells, with the nucleus being the only organelle to show labeling. The key step in transport carbohydrate biosynthesis that is catalyzed by M6PR displays no apparent preferential association with vascular tissues or with the bundle sheath. These results show that M6PR and, thus, mannitol synthesis are closely associated with the distribution of photosynthetic carbon metabolism in celery leaves. The principal role of M6PR is, therefore, in the assimilation of carbon being exported from the chloroplast, and it seems unlikely that this enzyme plays even an indirect role in phloem loading of mannitol.

  19. Organic matter degradation drives benthic cyanobacterial mat abundance on Caribbean coral reefs.

    PubMed

    Brocke, Hannah J; Polerecky, Lubos; de Beer, Dirk; Weber, Miriam; Claudet, Joachim; Nugues, Maggy M

    2015-01-01

    Benthic cyanobacterial mats (BCMs) are impacting coral reefs worldwide. However, the factors and mechanisms driving their proliferation are unclear. We conducted a multi-year survey around the Caribbean island of Curaçao, which revealed highest BCM abundance on sheltered reefs close to urbanised areas. Reefs with high BCM abundance were also characterised by high benthic cover of macroalgae and low cover of corals. Nutrient concentrations in the water-column were consistently low, but markedly increased just above substrata (both sandy and hard) covered with BCMs. This was true for sites with both high and low BCM coverage, suggesting that BCM growth is stimulated by a localised, substrate-linked release of nutrients from the microbial degradation of organic matter. This hypothesis was supported by a higher organic content in sediments on reefs with high BCM coverage, and by an in situ experiment which showed that BCMs grew within days on sediments enriched with organic matter (Spirulina). We propose that nutrient runoff from urbanised areas stimulates phototrophic blooms and enhances organic matter concentrations on the reef. This organic matter is transported by currents and settles on the seabed at sites with low hydrodynamics. Subsequently, nutrients released from the organic matter degradation fuel the growth of BCMs. Improved management of nutrients generated on land should lower organic loading of sediments and other benthos (e.g. turf and macroalgae) to reduce BCM proliferation on coral reefs. PMID:25941812

  20. Organic Matter Degradation Drives Benthic Cyanobacterial Mat Abundance on Caribbean Coral Reefs

    PubMed Central

    Brocke, Hannah J.; Polerecky, Lubos; de Beer, Dirk; Weber, Miriam; Claudet, Joachim; Nugues, Maggy M.

    2015-01-01

    Benthic cyanobacterial mats (BCMs) are impacting coral reefs worldwide. However, the factors and mechanisms driving their proliferation are unclear. We conducted a multi-year survey around the Caribbean island of Curaçao, which revealed highest BCM abundance on sheltered reefs close to urbanised areas. Reefs with high BCM abundance were also characterised by high benthic cover of macroalgae and low cover of corals. Nutrient concentrations in the water-column were consistently low, but markedly increased just above substrata (both sandy and hard) covered with BCMs. This was true for sites with both high and low BCM coverage, suggesting that BCM growth is stimulated by a localised, substrate-linked release of nutrients from the microbial degradation of organic matter. This hypothesis was supported by a higher organic content in sediments on reefs with high BCM coverage, and by an in situ experiment which showed that BCMs grew within days on sediments enriched with organic matter (Spirulina). We propose that nutrient runoff from urbanised areas stimulates phototrophic blooms and enhances organic matter concentrations on the reef. This organic matter is transported by currents and settles on the seabed at sites with low hydrodynamics. Subsequently, nutrients released from the organic matter degradation fuel the growth of BCMs. Improved management of nutrients generated on land should lower organic loading of sediments and other benthos (e.g. turf and macroalgae) to reduce BCM proliferation on coral reefs. PMID:25941812

  1. Organic matter degradation drives benthic cyanobacterial mat abundance on Caribbean coral reefs.

    PubMed

    Brocke, Hannah J; Polerecky, Lubos; de Beer, Dirk; Weber, Miriam; Claudet, Joachim; Nugues, Maggy M

    2015-01-01

    Benthic cyanobacterial mats (BCMs) are impacting coral reefs worldwide. However, the factors and mechanisms driving their proliferation are unclear. We conducted a multi-year survey around the Caribbean island of Curaçao, which revealed highest BCM abundance on sheltered reefs close to urbanised areas. Reefs with high BCM abundance were also characterised by high benthic cover of macroalgae and low cover of corals. Nutrient concentrations in the water-column were consistently low, but markedly increased just above substrata (both sandy and hard) covered with BCMs. This was true for sites with both high and low BCM coverage, suggesting that BCM growth is stimulated by a localised, substrate-linked release of nutrients from the microbial degradation of organic matter. This hypothesis was supported by a higher organic content in sediments on reefs with high BCM coverage, and by an in situ experiment which showed that BCMs grew within days on sediments enriched with organic matter (Spirulina). We propose that nutrient runoff from urbanised areas stimulates phototrophic blooms and enhances organic matter concentrations on the reef. This organic matter is transported by currents and settles on the seabed at sites with low hydrodynamics. Subsequently, nutrients released from the organic matter degradation fuel the growth of BCMs. Improved management of nutrients generated on land should lower organic loading of sediments and other benthos (e.g. turf and macroalgae) to reduce BCM proliferation on coral reefs.

  2. Organic amendments enhance microbial diversity and abundance of functional genes in Australian Soils

    NASA Astrophysics Data System (ADS)

    Aldorri, Sind; McMillan, Mary; Pereg, Lily

    2016-04-01

    Food and cash crops play important roles in Australia's economy with black, grey and red clay soil, widely use for growing cotton, wheat, corn and other crops in rotation. While the majority of cotton growers use nitrogen and phosphate fertilizers only in the form of agrochemicals, a few experiment with the addition of manure or composted plant material before planting. We hypothesized that the use of such organic amendments would enhance the soil microbial function through increased microbial diversity and abundance, thus contribute to improved soil sustainability. To test the hypothesis we collected soil samples from two cotton-growing farms in close geographical proximity and with mostly similar production practices other than one grower has been using composted plants as organic amendment and the second farmer uses only agrochemicals. We applied the Biolog Ecoplate system to study the metabolic signature of microbial communities and used qPCR to estimate the abundance of functional genes in the soil. The soil treated with organic amendments clearly showed higher metabolic activity of a more diverse range of carbon sources as well as higher abundance of genes involved in the nitrogen and phosphorous cycles. Since microbes undertake a large number of soil functions, the use of organic amendments can contribute to the sustainability of agricultural soils.

  3. Toxicity of five antibiotics and their mixtures towards photosynthetic aquatic organisms: implications for environmental risk assessment.

    PubMed

    González-Pleiter, Miguel; Gonzalo, Soledad; Rodea-Palomares, Ismael; Leganés, Francisco; Rosal, Roberto; Boltes, Karina; Marco, Eduardo; Fernández-Piñas, Francisca

    2013-04-15

    The individual and combined toxicities of amoxicillin, erythromycin, levofloxacin, norfloxacin and tetracycline have been examined in two organisms representative of the aquatic environment, the cyanobacterium Anabaena CPB4337 as a target organism and the green alga Pseudokirchneriella subcapitata as a non-target organism. The cyanobacterium was more sensitive than the green alga to the toxic effect of antibiotics. Erythromycin was highly toxic for both organisms; tetracycline was more toxic to the green algae whereas the quinolones levofloxacin and norfloxacin were more toxic to the cyanobacterium than to the green alga. Amoxicillin also displayed toxicity to the cyanobacterium but showed no toxicity to the green alga. The toxicological interactions of antibiotics in the whole range of effect levels either in binary or multicomponent mixtures were analyzed using the Combination Index (CI) method. In most cases, synergism clearly predominated both for the green alga and the cyanobacterium. The CI method was compared with the classical models of additivity Concentration Addition (CA) and Independent Action (IA) finding that CI could accurately predict deviations from additivity. Risk assessment was performed by calculating the ratio between Measured Environmental Concentration (MEC) and the Predicted No Effect Concentration (PNEC). A MEC/PNEC ratio higher than 1 was found for the binary erythromycin and tetracycline mixture in wastewater effluents, a combination which showed a strong synergism at low effect levels in both organisms. From the tested antibiotic mixtures, it can be concluded that certain specific combinations may pose a potential ecological risk for aquatic ecosystems with the present environmentally measured concentrations. PMID:23399078

  4. Photosynthetic approaches to chemical biotechnology.

    PubMed

    Desai, Shuchi H; Atsumi, Shota

    2013-12-01

    National interest and environmental advocates encourage alternatives to petroleum-based products. Besides biofuels, many other valuable chemicals used in every-day life are petroleum derivatives or require petroleum for their production. A plausible alternative to production using petroleum for chemical production is to harvest the abundant carbon dioxide resources in the environment to produce valuable hydrocarbons. Currently, efforts are being made to utilize a natural biological system, photosynthetic microorganisms, to perform this task. Photosynthetic microorganisms are attractive to use for biochemical production because they utilize economical resources for survival: sunlight and carbon dioxide. This review examines the various compounds produced by photosynthetic microorganisms.

  5. Non-coding RNAs’ partitioning in the evolution of photosynthetic organisms via energy transduction and redox signaling

    PubMed Central

    Kotakis, Christos

    2015-01-01

    Ars longa, vita brevis —HippocratesChloroplasts and mitochondria are genetically semi-autonomous organelles inside the plant cell. These constructions formed after endosymbiosis and keep evolving throughout the history of life. Experimental evidence is provided for active non-coding RNAs (ncRNAs) in these prokaryote-like structures, and a possible functional imprinting on cellular electrophysiology by those RNA entities is described. Furthermore, updated knowledge on RNA metabolism of organellar genomes uncovers novel inter-communication bridges with the nucleus. This class of RNA molecules is considered as a unique ontogeny which transforms their biological role as a genetic rheostat into a synchronous biochemical one that can affect the energetic charge and redox homeostasis inside cells. A hypothesis is proposed where such modulation by non-coding RNAs is integrated with genetic signals regulating gene transfer. The implications of this working hypothesis are discussed, with particular reference to ncRNAs involvement in the organellar and nuclear genomes evolution since their integrity is functionally coupled with redox signals in photosynthetic organisms. PMID:25826417

  6. Non-coding RNAs' partitioning in the evolution of photosynthetic organisms via energy transduction and redox signaling.

    PubMed

    Kotakis, Christos

    2015-01-01

    Ars longa, vita brevis -Hippocrates Chloroplasts and mitochondria are genetically semi-autonomous organelles inside the plant cell. These constructions formed after endosymbiosis and keep evolving throughout the history of life. Experimental evidence is provided for active non-coding RNAs (ncRNAs) in these prokaryote-like structures, and a possible functional imprinting on cellular electrophysiology by those RNA entities is described. Furthermore, updated knowledge on RNA metabolism of organellar genomes uncovers novel inter-communication bridges with the nucleus. This class of RNA molecules is considered as a unique ontogeny which transforms their biological role as a genetic rheostat into a synchronous biochemical one that can affect the energetic charge and redox homeostasis inside cells. A hypothesis is proposed where such modulation by non-coding RNAs is integrated with genetic signals regulating gene transfer. The implications of this working hypothesis are discussed, with particular reference to ncRNAs involvement in the organellar and nuclear genomes evolution since their integrity is functionally coupled with redox signals in photosynthetic organisms. PMID:25826417

  7. Nanophase Iron Oxides as an Ultraviolet Sunscreen for Ancient Photosynthetic Microbes: A Possible Link Between Early Organisms, Banded-Iron Formations, and the Oxygenation of the Atmosphere

    NASA Technical Reports Server (NTRS)

    Bishop, Janice L.; Rothschild, Lynn J.; Rothschild, Lynn J.; Rogoff, Dana A.

    2006-01-01

    We propose that nanophase iron oxide-bearing materials provided important niches for ancient photosynthetic microbes on the early Earth that ultimately led to the oxygenation of the Earth s atmosphere and the formation of iron oxide deposits. Atmospheric oxygen and ozone attenuate UV radiation on the Earth today providing substantial protection for photosynthetic organisms. With ultraviolet radiation fluxes likely to have been even higher on the early Earth than today, accessing solar radiation was particularly risky for early organisms. Yet, we know that photosynthesis arose then and played a critical role in subsequent evolution. Of primary importance was protection at approx.250-290 nm, where peak nucleic acid (approx.260 nm) and protein (approx.280 nm) absorptions occur. Nanophase ferric oxide/oxyhydroxide minerals absorb, and thus block, the lethal UV radiation, while transmitting light through much of the visible and near-infrared regions of interest to photosynthesis (400 to 1100 nm). Further, they were available in early environments, and are synthesized by many organisms. Based on ferric oxide/oxyhydroxide spectral properties, likely geologic processes, and the results of experiments with the photosynthetic organisms, Euglena sp. and Chlumydomonus reinhardtii, we propose a scenario where photosynthesis, and ultimately the oxygenation of the atmosphere, depended on the protection of early microbes by nanophase ferric oxides/oxyhydroxides. The results of this study are also applicable to other potentially habitable iron-bearing planetary bodies because of the evolutionary pressure to utilize solar radiation when available as an energy source.

  8. Organic Nitrogen-Driven Stimulation of Arbuscular Mycorrhizal Fungal Hyphae Correlates with Abundance of Ammonia Oxidizers

    PubMed Central

    Bukovská, Petra; Gryndler, Milan; Gryndlerová, Hana; Püschel, David; Jansa, Jan

    2016-01-01

    Large fraction of mineral nutrients in natural soil environments is recycled from complex and heterogeneously distributed organic sources. These sources are explored by both roots and associated mycorrhizal fungi. However, the mechanisms behind the responses of arbuscular mycorrhizal (AM) hyphal networks to soil organic patches of different qualities remain little understood. Therefore, we conducted a multiple-choice experiment examining hyphal responses to different soil patches within the root-free zone by two AM fungal species (Rhizophagus irregularis and Claroideoglomus claroideum) associated with Medicago truncatula, a legume forming nitrogen-fixing root nodules. Hyphal colonization of the patches was assessed microscopically and by quantitative real-time PCR (qPCR) using AM taxon-specific markers, and the prokaryotic and fungal communities in the patches (pooled per organic amendment treatment) were profiled by 454-amplicon sequencing. Specific qPCR markers were then designed and used to quantify the abundance of prokaryotic taxa showing the strongest correlation with the pattern of AM hyphal proliferation in the organic patches as per the 454-sequencing. The hyphal density of both AM fungi increased due to nitrogen (N)-containing organic amendments (i.e., chitin, DNA, albumin, and clover biomass), while no responses as compared to the non-amended soil patch were recorded for cellulose, phytate, or inorganic phosphate amendments. Abundances of several prokaryotes, including Nitrosospira sp. (an ammonium oxidizer) and an unknown prokaryote with affiliation to Acanthamoeba endosymbiont, which were frequently recorded in the 454-sequencing profiles, correlated positively with the hyphal responses of R. irregularis to the soil amendments. Strong correlation between abundance of these two prokaryotes and the hyphal responses to organic soil amendments by both AM fungi was then confirmed by qPCR analyses using all individual replicate patch samples. Further

  9. Organic Nitrogen-Driven Stimulation of Arbuscular Mycorrhizal Fungal Hyphae Correlates with Abundance of Ammonia Oxidizers.

    PubMed

    Bukovská, Petra; Gryndler, Milan; Gryndlerová, Hana; Püschel, David; Jansa, Jan

    2016-01-01

    Large fraction of mineral nutrients in natural soil environments is recycled from complex and heterogeneously distributed organic sources. These sources are explored by both roots and associated mycorrhizal fungi. However, the mechanisms behind the responses of arbuscular mycorrhizal (AM) hyphal networks to soil organic patches of different qualities remain little understood. Therefore, we conducted a multiple-choice experiment examining hyphal responses to different soil patches within the root-free zone by two AM fungal species (Rhizophagus irregularis and Claroideoglomus claroideum) associated with Medicago truncatula, a legume forming nitrogen-fixing root nodules. Hyphal colonization of the patches was assessed microscopically and by quantitative real-time PCR (qPCR) using AM taxon-specific markers, and the prokaryotic and fungal communities in the patches (pooled per organic amendment treatment) were profiled by 454-amplicon sequencing. Specific qPCR markers were then designed and used to quantify the abundance of prokaryotic taxa showing the strongest correlation with the pattern of AM hyphal proliferation in the organic patches as per the 454-sequencing. The hyphal density of both AM fungi increased due to nitrogen (N)-containing organic amendments (i.e., chitin, DNA, albumin, and clover biomass), while no responses as compared to the non-amended soil patch were recorded for cellulose, phytate, or inorganic phosphate amendments. Abundances of several prokaryotes, including Nitrosospira sp. (an ammonium oxidizer) and an unknown prokaryote with affiliation to Acanthamoeba endosymbiont, which were frequently recorded in the 454-sequencing profiles, correlated positively with the hyphal responses of R. irregularis to the soil amendments. Strong correlation between abundance of these two prokaryotes and the hyphal responses to organic soil amendments by both AM fungi was then confirmed by qPCR analyses using all individual replicate patch samples. Further

  10. Chemoselective single-site Earth-abundant metal catalysts at metal-organic framework nodes.

    PubMed

    Manna, Kuntal; Ji, Pengfei; Lin, Zekai; Greene, Francis X; Urban, Ania; Thacker, Nathan C; Lin, Wenbin

    2016-01-01

    Earth-abundant metal catalysts are critically needed for sustainable chemical synthesis. Here we report a simple, cheap and effective strategy of producing novel earth-abundant metal catalysts at metal-organic framework (MOF) nodes for broad-scope organic transformations. The straightforward metalation of MOF secondary building units (SBUs) with cobalt and iron salts affords highly active and reusable single-site solid catalysts for a range of organic reactions, including chemoselective borylation, silylation and amination of benzylic C-H bonds, as well as hydrogenation and hydroboration of alkenes and ketones. Our structural, spectroscopic and kinetic studies suggest that chemoselective organic transformations occur on site-isolated, electron-deficient and coordinatively unsaturated metal centres at the SBUs via σ-bond metathesis pathways and as a result of the steric environment around the catalytic site. MOFs thus provide a novel platform for the development of highly active and affordable base metal catalysts for the sustainable synthesis of fine chemicals. PMID:27574182

  11. Chemoselective single-site Earth-abundant metal catalysts at metal–organic framework nodes

    PubMed Central

    Manna, Kuntal; Ji, Pengfei; Lin, Zekai; Greene, Francis X.; Urban, Ania; Thacker, Nathan C.; Lin, Wenbin

    2016-01-01

    Earth-abundant metal catalysts are critically needed for sustainable chemical synthesis. Here we report a simple, cheap and effective strategy of producing novel earth-abundant metal catalysts at metal–organic framework (MOF) nodes for broad-scope organic transformations. The straightforward metalation of MOF secondary building units (SBUs) with cobalt and iron salts affords highly active and reusable single-site solid catalysts for a range of organic reactions, including chemoselective borylation, silylation and amination of benzylic C–H bonds, as well as hydrogenation and hydroboration of alkenes and ketones. Our structural, spectroscopic and kinetic studies suggest that chemoselective organic transformations occur on site-isolated, electron-deficient and coordinatively unsaturated metal centres at the SBUs via σ-bond metathesis pathways and as a result of the steric environment around the catalytic site. MOFs thus provide a novel platform for the development of highly active and affordable base metal catalysts for the sustainable synthesis of fine chemicals. PMID:27574182

  12. High-resolution NMR of hydrogen in organic solids by DNP enhanced natural abundance deuterium spectroscopy.

    PubMed

    Rossini, Aaron J; Schlagnitweit, Judith; Lesage, Anne; Emsley, Lyndon

    2015-10-01

    We demonstrate that high field (9.4 T) dynamic nuclear polarization (DNP) at cryogenic (∼100 K) sample temperatures enables the rapid acquisition of natural abundance (1)H-(2)H cross-polarization magic angle spinning (CPMAS) solid-state NMR spectra of organic solids. Spectra were obtained by impregnating substrates with a solution of the stable DNP polarizing agent TEKPol in tetrachloroethane. Tetrachloroethane is a non-solvent for the solids, and the unmodified substrates are then polarized through spin diffusion. High quality natural abundance (2)H CPMAS spectra of histidine hydrochloride monohydrate, glycylglycine and theophylline were acquired in less than 2h, providing direct access to hydrogen chemical shifts and quadrupolar couplings. The spectral resolution of the (2)H solid-state NMR spectra is comparable to that of (1)H spectra obtained with state of the art homonuclear decoupling techniques.

  13. A human interactome in three quantitative dimensions organized by stoichiometries and abundances.

    PubMed

    Hein, Marco Y; Hubner, Nina C; Poser, Ina; Cox, Jürgen; Nagaraj, Nagarjuna; Toyoda, Yusuke; Gak, Igor A; Weisswange, Ina; Mansfeld, Jörg; Buchholz, Frank; Hyman, Anthony A; Mann, Matthias

    2015-10-22

    The organization of a cell emerges from the interactions in protein networks. The interactome is critically dependent on the strengths of interactions and the cellular abundances of the connected proteins, both of which span orders of magnitude. However, these aspects have not yet been analyzed globally. Here, we have generated a library of HeLa cell lines expressing 1,125 GFP-tagged proteins under near-endogenous control, which we used as input for a next-generation interaction survey. Using quantitative proteomics, we detect specific interactions, estimate interaction stoichiometries, and measure cellular abundances of interacting proteins. These three quantitative dimensions reveal that the protein network is dominated by weak, substoichiometric interactions that play a pivotal role in defining network topology. The minority of stable complexes can be identified by their unique stoichiometry signature. This study provides a rich interaction dataset connecting thousands of proteins and introduces a framework for quantitative network analysis. PMID:26496610

  14. High-resolution NMR of hydrogen in organic solids by DNP enhanced natural abundance deuterium spectroscopy

    NASA Astrophysics Data System (ADS)

    Rossini, Aaron J.; Schlagnitweit, Judith; Lesage, Anne; Emsley, Lyndon

    2015-10-01

    We demonstrate that high field (9.4 T) dynamic nuclear polarization (DNP) at cryogenic (∼100 K) sample temperatures enables the rapid acquisition of natural abundance 1H-2H cross-polarization magic angle spinning (CPMAS) solid-state NMR spectra of organic solids. Spectra were obtained by impregnating substrates with a solution of the stable DNP polarizing agent TEKPol in tetrachloroethane. Tetrachloroethane is a non-solvent for the solids, and the unmodified substrates are then polarized through spin diffusion. High quality natural abundance 2H CPMAS spectra of histidine hydrochloride monohydrate, glycylglycine and theophylline were acquired in less than 2 h, providing direct access to hydrogen chemical shifts and quadrupolar couplings. The spectral resolution of the 2H solid-state NMR spectra is comparable to that of 1H spectra obtained with state of the art homonuclear decoupling techniques.

  15. Fossilized intact polar lipids of photosynthetic organisms in ancient subsurface sediments

    NASA Astrophysics Data System (ADS)

    Bauersachs, T.; Schouten, S.; Hopmans, E. C.; Sinninghe Damsté, J. S.

    2009-12-01

    In recent years, the idea of a rich microbial biosphere in the marine sea floor has been widely accepted. This so-called “deep biosphere” is estimated to contain ca. 50 % of Earth’s total prokaryotic biomass with the overall order of magnitude of microbial cells in the sea floor being the same as the biomass of all surface plant life (Whitman et al. 1998). Evidence for the existence of a deep biosphere comes, among others, from the analysis of intact polar lipids (IPLs). This approach presumes that IPLs almost instantaneously lose their polar head group after cell death and thus do not preserve on geological timescales. Consequently, IPLs in the subsurface should derive from in situ production and hence indicate the presence of living prokaryotic cells. For example, in various oceanic subsurface sediments archaeal IPLs have been found, suggesting that Archaea constitute a major fraction of the deep biosphere biomass (Lipp et al. 2008). In this study, we found IPLs of heterocystous cyanobacteria in a number of ancient and deeply buried sediments. Heterocystous cyanobacteria are strictly photoautotrophic organisms that are a common constituent of the phytoplankton community in many freshwater and brackish environments but are also encountered in the marine realm as endosymbionts of diatom species. Under nitrogen-depleted conditions, these organisms carry out nitrogen fixation in specialized cells, known as heterocysts. These cells contain a suite of heterocyst glycolipids (HGs) that have not been identified in any other organism and are thus unique biological markers for nitrogen-fixing heterocystous cyanobacteria. Using high performance liquid chromatography coupled to electrospray ionisation tandem mass spectrometry (HPLC/ESI-MS/MS), we detected HGs in Pleistocene and Pliocene Mediterranean sapropels buried up to 60 m below the seafloor. In addition, these HGs were also found in lacustrine deposits of the Oligocene Lake Enspel (35 Ma), the Eocene Lake Messel

  16. Fabrication of Organic Light-Emitting Diodes Using Photosynthetic Pigments Extracted from Spinach

    NASA Astrophysics Data System (ADS)

    Ohtani, Naoki; Kitagawa, Natsuko; Matsuda, Takashi

    2011-01-01

    We fabricated organic light-emitting diodes (OLEDs) containing chlorophylls in the active region, which were extracted from spinach using a chemical method. Photoluminescence (PL) cannot be observed in the thin film of the extracted chlorophylls owing to concentration quenching. To overcome the concentration quenching, a host material, poly[(m-phenylenevinylene)-alt-(2,5-dihexyloxy-p-phenylenevinylene)] (PPV) was added in the active region. This leads to the observaton of electroluminescence (EL) signals originating from chlorophyll a. We also evaluated the lifetime of the PL and EL. Consequently, the OLEDs containing carotenoids in the active region exhibit the light-emission much longer time than that without carotenoidos. This is assigned to the antioxidant activities of carotenoids. OLEDs containing a large amount of carotenoids are resistant to the oxidation damage.

  17. Probabilisitc Geobiological Classification Using Elemental Abundance Distributions and Lossless Image Compression in Recent and Modern Organisms

    NASA Technical Reports Server (NTRS)

    Storrie-Lombardi, Michael C.; Hoover, Richard B.

    2005-01-01

    Last year we presented techniques for the detection of fossils during robotic missions to Mars using both structural and chemical signatures[Storrie-Lombardi and Hoover, 2004]. Analyses included lossless compression of photographic images to estimate the relative complexity of a putative fossil compared to the rock matrix [Corsetti and Storrie-Lombardi, 2003] and elemental abundance distributions to provide mineralogical classification of the rock matrix [Storrie-Lombardi and Fisk, 2004]. We presented a classification strategy employing two exploratory classification algorithms (Principal Component Analysis and Hierarchical Cluster Analysis) and non-linear stochastic neural network to produce a Bayesian estimate of classification accuracy. We now present an extension of our previous experiments exploring putative fossil forms morphologically resembling cyanobacteria discovered in the Orgueil meteorite. Elemental abundances (C6, N7, O8, Na11, Mg12, Ai13, Si14, P15, S16, Cl17, K19, Ca20, Fe26) obtained for both extant cyanobacteria and fossil trilobites produce signatures readily distinguishing them from meteorite targets. When compared to elemental abundance signatures for extant cyanobacteria Orgueil structures exhibit decreased abundances for C6, N7, Na11, All3, P15, Cl17, K19, Ca20 and increases in Mg12, S16, Fe26. Diatoms and silicified portions of cyanobacterial sheaths exhibiting high levels of silicon and correspondingly low levels of carbon cluster more closely with terrestrial fossils than with extant cyanobacteria. Compression indices verify that variations in random and redundant textural patterns between perceived forms and the background matrix contribute significantly to morphological visual identification. The results provide a quantitative probabilistic methodology for discriminating putatitive fossils from the surrounding rock matrix and &om extant organisms using both structural and chemical information. The techniques described appear applicable

  18. Nondestructive, in situ, cellular-scale mapping of elemental abundances including organic carbon in permineralized fossils

    PubMed Central

    Boyce, C. K.; Hazen, R. M.; Knoll, A. H.

    2001-01-01

    The electron microprobe allows elemental abundances to be mapped at the μm scale, but until now high resolution mapping of light elements has been challenging. Modifications of electron microprobe procedure permit fine-scale mapping of carbon. When applied to permineralized fossils, this technique allows simultaneous mapping of organic material, major matrix-forming elements, and trace elements with μm-scale resolution. The resulting data make it possible to test taphonomic hypotheses for the formation of anatomically preserved silicified fossils, including the role of trace elements in the initiation of silica precipitation and in the prevention of organic degradation. The technique allows one to understand the localization of preserved organic matter before undertaking destructive chemical analyses and, because it is nondestructive, offers a potentially important tool for astrobiological investigations of samples returned from Mars or other solar system bodies. PMID:11371632

  19. Self-Organized Photosynthetic Nanoparticle for Cell-free Hydrogen Production

    SciTech Connect

    Iwuchukwu, Ifeyinwa J; Vaughn, Michael D; Myers, Natalie; O'Neill, Hugh Michael; Frymier, Paul Dexter; Bruce, Barry

    2009-01-01

    There is considerable interest in making use of solar energy through photosynthesis to create alternative forms of fuel. Here, we show that photosystem I from a thermophilic bacterium and cytochrome-c6 can, in combination with a platinum catalyst, generate a stable supply of hydrogen in vitro upon illumination. The self-organized platinization of the photosystem I nanoparticles allows electron transport from sodium ascorbate to photosystem I via cytochrome-c{sub 6} and finally to the platinum catalyst, where hydrogen gas is formed. Our system produces hydrogen at temperatures up to 55 C and is temporally stable for >85 days with no decrease in hydrogen yield when tested intermittently. The maximum yield is {approx} 5.5 {micro}mol H{sub 2} h{sup -1} mg{sup -1} chlorophyll and is estimated to be {approx} 25-fold greater than current biomass-to-fuel strategies. Future work will further improve this yield by increasing the kinetics of electron transfer, extending the spectral response and replacing the platinum catalyst with a renewable hydrogenase.

  20. Light represses transcription of asparagine synthetase genes in photosynthetic and nonphotosynthetic organs of plants

    SciTech Connect

    Tsai, Fongying; Coruzzi, G. )

    1991-10-01

    Asparagine synthetase (AS) mRNA in Pisum sativum accumulates preferentially in plants grown in the dark. Nuclear run-on experiments demonstrate that expression of both the AS1 and AS2 genes is negatively regulated by light at the level of transcription. A decrease in the transcriptional rate of the AS1 gene can be detected as early as 20 min after exposure to light. Time course experiments reveal that the levels of AS mRNA fluctuate dramatically during a normal light/dark cycle. This is due to a direct effect of light and not to changes associated with circadian rhythm. A novel finding is that the light-repressed expression of the AS1 gene is as dramatic nonphotosynthetic organs such as roots as it is in leaves. Experiments demonstrate that the small amount of light which passes through the soil is sufficient to repress AS1 expression in roots, indicating that light has a direct effect on AS1 gene expression in roots. The negative regulation of AS gene expression by light was shown to be a general phenomenon in plants which also occurs in nonlegumes such as Nicotiana plumbaginifolia and Nicotiana tabacum. Thus, the AS genes can serve as a model with which to dissect the molecular basis for light-regulated transcriptional repression in plants.

  1. Evolution of the control of pigment and plastid development in photosynthetic organisms.

    PubMed

    Schiff, J A

    1981-01-01

    How do bioenergetic organelles relate to the cells they are in and how was this relationship established over the course of evolution? Plastids and mitochondria are viewed as prokaryotic residents in eukaryotic cells. These organelles are semiautonomous: they perpetuate themselves by division but regulate and are subject to regulation by the cell in which they are residents. Although these organelles are usually constitutive, their development is arrested in certain organisms when an inducing substrate is absent (light, for example, in the case of the chloroplast) with the formation of precursor organelles such as proplastids. Various trends in the evolution of photo-control systems are discussed including those concerned with photoperception and photomorphogenesis. The photocontrol of chloroplast development by blue and red light is discussed in relation to its possible evolutionary origins in a system for finding the right light for photosynthesis. Models for various types of cellular regulation by light during chloroplast development are discussed. Also considered is the evolution of plastid pigments in response to available light. A parallel evolution of accessory pigments and chlorophylls is suggested which led to chlorophyll reaction centers serving as energy sinks for light absorbed by accessory pigments and, therefore, having their absorptions pushed to the longest possible wavelengths as accessory pigments evolved to fill the middle of the spectrum in response to ecological selection. An endosymbiotic origin of bioenergetic organelles is suggested based on polyphyletic origins of chloroplasts from a number of oxygenic procaryotic precursors. The similarity between proplastids and these oxygenic procaryotes suggests that the original invading organelle may have resembled a modern proplastid rather than a mature chloroplast.

  2. Organic and mineral imprints in fossil photosynthetic mats of an East Antarctic lake.

    PubMed

    Lepot, K; Compère, P; Gérard, E; Namsaraev, Z; Verleyen, E; Tavernier, I; Hodgson, D A; Vyverman, W; Gilbert, B; Wilmotte, A; Javaux, E J

    2014-09-01

    spheres interpreted as coccoidal bacteria may represent fossils of intracellular calcification. These organo-mineral associations support organically driven nanocarbonate crystallization and stabilization, hence providing potential markers for microbial calcification in ancient rocks. PMID:25039968

  3. Orchid bees as bio-indicators for organic coffee farms in Costa Rica: does farm size affect their abundance?

    PubMed

    Hedström, Ingemar; Denzel, Andrew; Owens, Gareth

    2006-09-01

    The potential of Euglossini bees, especially Euglossa, as biological indicators of organic vs nonorganic coffee farms was studied in Atenas and San Isidro, Alajuela, Costa Rica using 1.8-cineole as lure. Observations were made for three days at each of four farms and complemented with data from a year of observations. Orchid bees were in greater abundance in the organic farms (t-Student test). However, lower abundances suggest that an organic farm may be negatively affected by the proximity of non-organic farms, depending on its size and distance. Orchid bees may be indicators of organic coffee farms.

  4. Genetic variability of respiratory complex abundance, organization, and activity in mouse brain

    PubMed Central

    Buck, Kari J.; Walter, Nicole A.R.; Denmark, Deaunne L.

    2013-01-01

    Mitochondrial dysfunction is implicated in the etiology and pathogenesis of numerous human disorders involving tissues with high energy demand. Murine models are widely used to elucidate genetic determinants of phenotypes relevant to human disease, with recent studies of C57BL/6J (B6), DBA/2J (D2) and B6xD2 populations implicating naturally occurring genetic variation in mitochondrial function/dysfunction. Using blue native polyacrylamide gel electrophoresis, immunoblots, and in-gel activity analyses of complexes I, II, IV and V, our studies are the first to assess abundance, organization, and catalytic activity of mitochondrial respiratory complexes and supercomplexes in mouse brain. Remarkable strain differences in supercomplex assembly and associated activity are evident, without differences in individual complexes I, II, III, or IV. Supercomplexes I1III2IV2-3 exhibit robust complex III immunoreactivity and complex I and IV activities in D2, but with little detected in B6 for I1III2IV2, and I1III2IV3 is not detected in B6. I1III2IV1 and I1III2 are abundant and catalytically active in both strains, but significantly more so in B6. Furthermore, while supercomplex III2IV1 is abundant in D2, none is detected in B6. In aggregate, these results indicate a shift toward more highly assembled supercomplexes in D2. Respiratory supercomplexes are thought to increase electron flow efficiency and individual complex stability, and to reduce electron leak and generation of reactive oxygen species. Our results provide a framework to begin assessing the role of respiratory complex suprastructure in genetic vulnerability and treatment for a wide variety of mitochondrial-related disorders. PMID:24164700

  5. Predators alter community organization of coral reef cryptofauna and reduce abundance of coral mutualists

    NASA Astrophysics Data System (ADS)

    Stier, A. C.; Leray, M.

    2014-03-01

    Coral reefs are the most diverse marine systems in the world, yet our understanding of the processes that maintain such extraordinary diversity remains limited and taxonomically biased toward the most conspicuous species. Cryptofauna that live deeply embedded within the interstitial spaces of coral reefs make up the majority of reef diversity, and many of these species provide important protective services to their coral hosts. However, we know very little about the processes governing the diversity and composition of these less conspicuous but functionally important species. Here, we experimentally quantify the role of predation in driving the community organization of small fishes and decapods that live embedded within Pocillopora eydouxi, a structurally complex, reef-building coral found widely across the Indo-Pacific. We use surveys to describe the natural distribution of predators, and then, factorially manipulate two focal predator species to quantify the independent and combined effects of predator density and identity on P. eydouxi-dwelling cryptofauna. Predators reduced abundance (34 %), species richness (20 %), and modified species composition. Rarefaction revealed that observed reductions in species richness were primarily driven by changes in abundance. Additionally, the two predator species uniquely affected the beta diversity and composition of the prey assemblage. Predators reduced the abundance and modified the composition of a number of mutualist fishes and decapods, whose benefit to the coral is known to be both diversity- and density-dependent. We predict that the density and identity of predators present within P. eydouxi may substantially alter coral performance in the face of an increased frequency and intensity of natural and anthropogenic stressors.

  6. Photosynthetic units.

    PubMed

    Schmid, G H; Gaffron, H

    1968-08-01

    Leaf tissues of aurea mutants of tobacco and Lespedeza have been shown to have higher photosynthetic capacity per molecule of chlorophyll, a higher saturation intensity, a simpler lamellar structure, and the same quantum yield as their dark green parents. Here we report on the values of photosynthetic units for both types of plants and some algae. The unit has been assumed to be about as uniform and steady in the plant world as the quantum efficiency. The number on which all theoretical discussions have been based so far is 2400 per O(2) evolved or CO(2) reduced. With dark green plants and algae our determinations of units by means of 40 microsec flashes superimposed on a steady rate of background photosynthesis at 900 ergs cm(-2) sec(-1) of red light yielded mostly numbers between 2000 and 2700. However, the photosynthetic unit turned out to be very variable, even in these objects. In aurea mutants the unit was distinctly smaller, averaging 600 chl/CO(2). By choosing the right combination of colors for flash and background light, units as low as 300 chl/CO(2) or 40 chl/e(-) could be measured consistently. We found five well-defined groups of units composed of multiples of its smallest member. These new findings are discussed in terms of structural entities that double or divide under the influence of far-red light.

  7. Targeted Access to the Genomes of Low Abundance Organisms in Complex Microbial Communities

    SciTech Connect

    Podar, Mircea; Abulencia, Carl; Walcher, Marion; Hutchinson, Don; Zengler, Karsten; Garcia, Joseph; Holland, Trevin; Cotton, Dave; Hauser, Loren John; Keller, Martin

    2007-01-01

    Current metagenomic approaches to the study of complex microbial consortia provide a glimpse into the community metabolism, and occasionally allow genomic assemblies for the most abundant organisms. However, little information is gained for the members of the community present at low frequency, especially those representing yet uncultured taxa-which includes the bulk of the diversity present in most environments. Here we used phylogenetically directed cell separation by fluorescence in situ hybridization and flow cytometry, followed by amplification and sequencing of a fraction of the genomic DNA of several bacterial cells that belong to the TM7 phylum. Partial genomic assembly allowed, for the first time, a look into the evolution and potential metabolism of a soil representative from this group of organisms for which there are no species in stable laboratory cultures. Genomic reconstruction from targeted cells of uncultured organisms directly isolated from the environment represents a powerful approach to access any specific members of a community and an alternative way to assess the community metabolic potential.

  8. Systems-wide analysis of acclimation responses to long-term heat stress and recovery in the photosynthetic model organism Chlamydomonas reinhardtii.

    PubMed

    Hemme, Dorothea; Veyel, Daniel; Mühlhaus, Timo; Sommer, Frederik; Jüppner, Jessica; Unger, Ann-Katrin; Sandmann, Michael; Fehrle, Ines; Schönfelder, Stephanie; Steup, Martin; Geimer, Stefan; Kopka, Joachim; Giavalisco, Patrick; Schroda, Michael

    2014-11-01

    We applied a top-down systems biology approach to understand how Chlamydomonas reinhardtii acclimates to long-term heat stress (HS) and recovers from it. For this, we shifted cells from 25 to 42°C for 24 h and back to 25°C for ≥8 h and monitored abundances of 1856 proteins/protein groups, 99 polar and 185 lipophilic metabolites, and cytological and photosynthesis parameters. Our data indicate that acclimation of Chlamydomonas to long-term HS consists of a temporally ordered, orchestrated implementation of response elements at various system levels. These comprise (1) cell cycle arrest; (2) catabolism of larger molecules to generate compounds with roles in stress protection; (3) accumulation of molecular chaperones to restore protein homeostasis together with compatible solutes; (4) redirection of photosynthetic energy and reducing power from the Calvin cycle to the de novo synthesis of saturated fatty acids to replace polyunsaturated ones in membrane lipids, which are deposited in lipid bodies; and (5) when sinks for photosynthetic energy and reducing power are depleted, resumption of Calvin cycle activity associated with increased photorespiration, accumulation of reactive oxygen species scavengers, and throttling of linear electron flow by antenna uncoupling. During recovery from HS, cells appear to focus on processes allowing rapid resumption of growth rather than restoring pre-HS conditions.

  9. Systems-Wide Analysis of Acclimation Responses to Long-Term Heat Stress and Recovery in the Photosynthetic Model Organism Chlamydomonas reinhardtii[W][OPEN

    PubMed Central

    Hemme, Dorothea; Veyel, Daniel; Mühlhaus, Timo; Sommer, Frederik; Jüppner, Jessica; Unger, Ann-Katrin; Sandmann, Michael; Fehrle, Ines; Schönfelder, Stephanie; Steup, Martin; Geimer, Stefan; Kopka, Joachim; Giavalisco, Patrick; Schroda, Michael

    2014-01-01

    We applied a top-down systems biology approach to understand how Chlamydomonas reinhardtii acclimates to long-term heat stress (HS) and recovers from it. For this, we shifted cells from 25 to 42°C for 24 h and back to 25°C for ≥8 h and monitored abundances of 1856 proteins/protein groups, 99 polar and 185 lipophilic metabolites, and cytological and photosynthesis parameters. Our data indicate that acclimation of Chlamydomonas to long-term HS consists of a temporally ordered, orchestrated implementation of response elements at various system levels. These comprise (1) cell cycle arrest; (2) catabolism of larger molecules to generate compounds with roles in stress protection; (3) accumulation of molecular chaperones to restore protein homeostasis together with compatible solutes; (4) redirection of photosynthetic energy and reducing power from the Calvin cycle to the de novo synthesis of saturated fatty acids to replace polyunsaturated ones in membrane lipids, which are deposited in lipid bodies; and (5) when sinks for photosynthetic energy and reducing power are depleted, resumption of Calvin cycle activity associated with increased photorespiration, accumulation of reactive oxygen species scavengers, and throttling of linear electron flow by antenna uncoupling. During recovery from HS, cells appear to focus on processes allowing rapid resumption of growth rather than restoring pre-HS conditions. PMID:25415976

  10. Reversed-phase HPLC determination of chlorophyll a' and phylloquinone in Photosystem I of oxygenic photosynthetic organisms. Universal existence of one chlorophyll a' molecule in Photosystem I.

    PubMed

    Nakamura, Akimasa; Akai, Masahiko; Yoshida, Emi; Taki, Takashi; Watanabe, Tadashi

    2003-06-01

    Chlorophyll (Chl) a', the C132-epimer of Chl a, is a constituent of the primary electron donor (P700) of Photosystem (PS) I of a thermophilic cyanobacterium Synechococcus (Thermosynechococcus) elongatus, as was recently demonstrated by X-ray crystallography. To determine whether PS I of oxygenic photosynthetic organisms universally contains one molecule of Chl a', pigment compositions of thylakoid membranes and PS I complexes isolated from the cyanobacteria T. elongatus and Synechocystis sp. PCC 6803, the green alga Chlamydomonas reinhardtii, and the green plant spinach, were examined by simultaneous detection of phylloquinone (the secondary electron acceptor of PS I) and Chl a' by reversed-phase HPLC. The results were compared with the Chl a/P700 ratio determined spectrophotometrically. The Chl a'/PS I ratios of thylakoid membranes and PS I were about 1 for all the organisms examined, and one Chl a' molecule was found in PS I even after most of the peripheral subunits were removed. Chl a' showed a characteristic extraction behaviour significantly different from the bulk Chl a in acetone/methanol extraction upon varying the mixing ratio. These findings confirm that a single Chl a' molecule in P700 is the universal feature of PS I of the Chl a-based oxygenic photosynthetic organisms.

  11. Abundance of potentially pathogenic micro-organisms in Penaeus monodon larvae rearing systems in India.

    PubMed

    Vaseeharan, Baskaralingam; Ramasamy, Palaniappan

    2003-01-01

    Monodon baculovirls (MBV), external fouling organisms (EFO) and bacteria (especially Vibrio species) were monitored during 1996-1997 at nine different Penaeus monodon rearing hatcheries in India. Total cultivable heterotrophic bacteria, Vibrio-like-bacteria, presumptive Vibrio harveyi, Vibrio anguillarum, Vibrio vulnificus counts were determined from shrimp eggs, post larvae, rearing tank water, source sea water, feed (Artemia nauplii and microencapsulated feed). The MBV infected post larvae and their environment showed higher Vibrio-like-bacteria than uninfected post larvae. An overwhelming predominance of presumptive Vibrio harveyi and Vibrio anguillarum was observed in post larval rearing tank water, MBV infected and uninfected post larvae. Vibrio-like-bacteria in Artemia nauplii clearly showed the possible source of these pathogenic bacteria in the hatchery environments. Quantitative analysis of Vibrio-like-bacteria in hatcheries revealed that when the Vibrio-like-bacteria increases to 2 x 10(2) CFU mortality of the post larvae occurs. Abundance of these micro-organisms in hatchery samples indicated that they are opportunistic pathogens which can invade the shrimp tissue, subsequently cause disease when the post larvae were under stressful conditions.

  12. Effects of multiple levels of social organization on survival and abundance.

    PubMed

    Ward, Eric J; Semmens, Brice X; Holmes, Elizabeth E; Balcomb Iii, Ken C

    2011-04-01

    Identifying how social organization shapes individual behavior, survival, and fecundity of animals that live in groups can inform conservation efforts and improve forecasts of population abundance, even when the mechanism responsible for group-level differences is unknown. We constructed a hierarchical Bayesian model to quantify the relative variability in survival rates among different levels of social organization (matrilines and pods) of an endangered population of killer whales (Orcinus orca). Individual killer whales often participate in group activities such as prey sharing and cooperative hunting. The estimated age-specific survival probabilities and survivorship curves differed considerably among pods and to a lesser extent among matrilines (within pods). Across all pods, males had lower life expectancy than females. Differences in survival between pods may be caused by a combination of factors that vary across the population's range, including reduced prey availability, contaminants in prey, and human activity. Our modeling approach could be applied to demographic rates for other species and for parameters other than survival, including reproduction, prey selection, movement, and detection probabilities. PMID:21054527

  13. Organic matter formed from hydrolysis of metal carbides of the iron peak of cosmic elemental abundance

    NASA Astrophysics Data System (ADS)

    Cataldo, Franco

    2003-01-01

    This work is a modern revisitation of an old idea of great chemists of the past such as Berthelot, Mendeleev, Cloez and Moissan: the formation of organic matter under pre-biotic conditions starting from the hydrolysis of metal carbides. This idea was originally proposed for the formation of petroleum in the Earth and was extended to other bodies of the solar system by Sokolov at the end of the 19th century. The reason for this revisitation lies in the fact that complex organic matter resembling a petroleum fraction may exist in certain protoplanetary nebulae. The present work starts with a survey of the theory of the inorganic origin of petroleum and reports on current evidence for its derivation from residues of formerly living matter, but also considers theories that admit both a biogenic and an abiogenic origin for petroleum. By considering the cosmic abundance of elements and the evidence concerning the presence of carbides in meteorites, we discuss the formation, structure and hydrolysis products derived from the metal carbides of the iron peak of cosmic elemental abundance. Chromium carbide (Cr3C2) has then been used as a model compound for all the key carbides of the iron peak of the cosmic abundance (Cr, Fe, Ni, V, Mn, Co) and it has been hydrolysed under different conditions and the hydrocarbons formed have been analysed using electronic spectroscopy, high-performance liquid chromatography with a diode-array detector (HPLC-DAD) and by Fourier-transform infrared (FT-IR) spectroscopy. Methane, a series of about 20 different alkenes with single and conjugated double bonds have been detected. Paraffins are formed simultaneously with the alkene series but no acetylenic hydrocarbons have been detected. This study confirms early works considering the easy hydrolysis of the carbides of Cr, Fe, Ni, Mn and Co with the formation of H2, a series of alkanes including methane and a series of alkenes including ethylene. The peculiar behaviour of copper carbide (copper is

  14. Adaptation of an abundant Roseobacter RCA organism to pelagic systems revealed by genomic and transcriptomic analyses.

    PubMed

    Voget, Sonja; Wemheuer, Bernd; Brinkhoff, Thorsten; Vollmers, John; Dietrich, Sascha; Giebel, Helge-Ansgar; Beardsley, Christine; Sardemann, Carla; Bakenhus, Insa; Billerbeck, Sara; Daniel, Rolf; Simon, Meinhard

    2015-02-01

    The RCA (Roseobacter clade affiliated) cluster, with an internal 16S rRNA gene sequence similarity of >98%, is the largest cluster of the marine Roseobacter clade and most abundant in temperate to (sub)polar oceans, constituting up to 35% of total bacterioplankton. The genome analysis of the first described species of the RCA cluster, Planktomarina temperata RCA23, revealed that this phylogenetic lineage is deeply branching within the Roseobacter clade. It shares not >65.7% of homologous genes with any other organism of this clade. The genome is the smallest of all closed genomes of the Roseobacter clade, exhibits various features of genome streamlining and encompasses genes for aerobic anoxygenic photosynthesis (AAP) and CO oxidation. In order to assess the biogeochemical significance of the RCA cluster we investigated a phytoplankton spring bloom in the North Sea. This cluster constituted 5.1% of the total, but 10-31% (mean 18.5%) of the active bacterioplankton. A metatranscriptomic analysis showed that the genome of P. temperata RCA23 was transcribed to 94% in the bloom with some variations during day and night. The genome of P. temperata RCA23 was also retrieved to 84% from metagenomic data sets from a Norwegian fjord and to 82% from stations of the Global Ocean Sampling expedition in the northwestern Atlantic. In this region, up to 6.5% of the total reads mapped on the genome of P. temperata RCA23. This abundant taxon appears to be a major player in ocean biogeochemistry. PMID:25083934

  15. Adaptation of an abundant Roseobacter RCA organism to pelagic systems revealed by genomic and transcriptomic analyses

    PubMed Central

    Voget, Sonja; Wemheuer, Bernd; Brinkhoff, Thorsten; Vollmers, John; Dietrich, Sascha; Giebel, Helge-Ansgar; Beardsley, Christine; Sardemann, Carla; Bakenhus, Insa; Billerbeck, Sara; Daniel, Rolf; Simon, Meinhard

    2015-01-01

    The RCA (Roseobacter clade affiliated) cluster, with an internal 16S rRNA gene sequence similarity of >98%, is the largest cluster of the marine Roseobacter clade and most abundant in temperate to (sub)polar oceans, constituting up to 35% of total bacterioplankton. The genome analysis of the first described species of the RCA cluster, Planktomarina temperata RCA23, revealed that this phylogenetic lineage is deeply branching within the Roseobacter clade. It shares not >65.7% of homologous genes with any other organism of this clade. The genome is the smallest of all closed genomes of the Roseobacter clade, exhibits various features of genome streamlining and encompasses genes for aerobic anoxygenic photosynthesis (AAP) and CO oxidation. In order to assess the biogeochemical significance of the RCA cluster we investigated a phytoplankton spring bloom in the North Sea. This cluster constituted 5.1% of the total, but 10–31% (mean 18.5%) of the active bacterioplankton. A metatranscriptomic analysis showed that the genome of P. temperata RCA23 was transcribed to 94% in the bloom with some variations during day and night. The genome of P. temperata RCA23 was also retrieved to 84% from metagenomic data sets from a Norwegian fjord and to 82% from stations of the Global Ocean Sampling expedition in the northwestern Atlantic. In this region, up to 6.5% of the total reads mapped on the genome of P. temperata RCA23. This abundant taxon appears to be a major player in ocean biogeochemistry. PMID:25083934

  16. The history of photosynthetic thermoluminescence.

    PubMed

    Vass, Imre

    2003-01-01

    A fundamental discovery of photosynthetis research in the 1950s was the detection of thermally stimulated light emission from preilluminated photosynthetic material [Arnold W and Sherwood H (1957) Proc Natl Acad Sci USA 43: 105-114]. This phenomenon, called thermoluminescence (TL), is characteristic of a wide range of materials (minerals, semiconductors, inorganic and organic crystals, and complex biological systems), which share the ability of storing radiant energy in thermally stabilized trap states. The original discovery of TL in dried chloroplasts later proved to be a phenomenon common to all photosynthetic organisms: photosynthetic bacteria, cyanobacteria, algae and higher plants, which can be observed in isolated membrane particles, intact chloroplasts and unicellular organisms, and whole leaves. Following the initial observations considerable effort has been devoted to the identification and characterization of photosynthetic TL components. This work has firmly established the participation of various oxidation states of the water-oxidizing complex, the redox-active tyrosines, and the quinone electron acceptors of Photosystem II (PS II) in the generation of photosynthetic glow curves. Since TL characteristics are very sensitive to subtle changes in the redox properties of the involved electron transport components, the TL method has become a powerful tool in probing a wide range of PS II redox reactions and their modifications by environmental stress effects. Here, the main milestones of research in photosynthetic TL are covered until the present day. PMID:16228589

  17. The occurrence of the psbS gene product in Chlamydomonas reinhardtii and in other photosynthetic organisms and its correlation with energy quenching.

    PubMed

    Bonente, Giulia; Passarini, Francesca; Cazzaniga, Stefano; Mancone, Carmine; Buia, Maria Cristina; Tripodi, Marco; Bassi, Roberto; Caffarri, Stefano

    2008-01-01

    To avoid photodamage, photosynthetic organisms have developed mechanisms to evade or dissipate excess energy. Lumen overacidification caused by light-induced electron transport triggers quenching of excited chlorophylls and dissipation of excess energy into heat. In higher plants participation of the PsbS protein as the sensor of low lumenal pH was clearly demonstrated. Although light-dependent energy quenching is a property of all photosynthetic organisms, large differences in amplitude and kinetics can be observed thus raising the question whether a single common mechanism is in action. We performed a detailed study of PsbS expression/accumulation in Chlamydomonas reinhardtii and investigated its accumulation in other algae and plants. We showed that PsbS cannot be detected in Chlamydomonas under a wide range of growth conditions. Overexpression of the endogenous psbs gene showed that the corresponding protein could not be addressed to the thylakoid membranes. Survey of different unicellular green algae showed no accumulation of anti-PsbS reactive proteins differently from multicellular species. Nevertheless, some unicellular species exhibit high energy quenching activity, suggesting that a PsbS-independent mechanism is activated. By correlating growth habitat and PsbS accumulation in different species, we suggest that during the evolution the light environment has been a determinant factor for the conservation/loss of the PsbS function. PMID:19067957

  18. The occurrence of the psbS gene product in Chlamydomonas reinhardtii and in other photosynthetic organisms and its correlation with energy quenching.

    PubMed

    Bonente, Giulia; Passarini, Francesca; Cazzaniga, Stefano; Mancone, Carmine; Buia, Maria Cristina; Tripodi, Marco; Bassi, Roberto; Caffarri, Stefano

    2008-01-01

    To avoid photodamage, photosynthetic organisms have developed mechanisms to evade or dissipate excess energy. Lumen overacidification caused by light-induced electron transport triggers quenching of excited chlorophylls and dissipation of excess energy into heat. In higher plants participation of the PsbS protein as the sensor of low lumenal pH was clearly demonstrated. Although light-dependent energy quenching is a property of all photosynthetic organisms, large differences in amplitude and kinetics can be observed thus raising the question whether a single common mechanism is in action. We performed a detailed study of PsbS expression/accumulation in Chlamydomonas reinhardtii and investigated its accumulation in other algae and plants. We showed that PsbS cannot be detected in Chlamydomonas under a wide range of growth conditions. Overexpression of the endogenous psbs gene showed that the corresponding protein could not be addressed to the thylakoid membranes. Survey of different unicellular green algae showed no accumulation of anti-PsbS reactive proteins differently from multicellular species. Nevertheless, some unicellular species exhibit high energy quenching activity, suggesting that a PsbS-independent mechanism is activated. By correlating growth habitat and PsbS accumulation in different species, we suggest that during the evolution the light environment has been a determinant factor for the conservation/loss of the PsbS function.

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

    NASA Technical Reports Server (NTRS)

    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.

  20. An obligately photosynthetic bacterial anaerobe from a deep-sea hydrothermal vent.

    PubMed

    Beatty, J Thomas; Overmann, Jörg; Lince, Michael T; Manske, Ann K; Lang, Andrew S; Blankenship, Robert E; Van Dover, Cindy L; Martinson, Tracey A; Plumley, F Gerald

    2005-06-28

    The abundance of life on Earth is almost entirely due to biological photosynthesis, which depends on light energy. The source of light in natural habitats has heretofore been thought to be the sun, thus restricting photosynthesis to solar photic environments on the surface of the Earth. If photosynthesis could take place in geothermally illuminated environments, it would increase the diversity of photosynthetic habitats both on Earth and on other worlds that have been proposed to possibly harbor life. Green sulfur bacteria are anaerobes that require light for growth by the oxidation of sulfur compounds to reduce CO2 to organic carbon, and are capable of photosynthetic growth at extremely low light intensities. We describe the isolation and cultivation of a previously unknown green sulfur bacterial species from a deep-sea hydrothermal vent, where the only source of light is geothermal radiation that includes wavelengths absorbed by photosynthetic pigments of this organism.

  1. Characterization of Antibiotic Resistance Gene Abundance and Microbiota Composition in Feces of Organic and Conventional Pigs from Four EU Countries

    PubMed Central

    Gerzova, Lenka; Babak, Vladimir; Sedlar, Karel; Faldynova, Marcela; Videnska, Petra; Cejkova, Darina; Jensen, Annette Nygaard; Denis, Martine; Kerouanton, Annaelle; Ricci, Antonia; Cibin, Veronica; Österberg, Julia; Rychlik, Ivan

    2015-01-01

    One of the recent trends in animal production is the revival of interest in organic farming. The increased consumer interest in organic animal farming is mainly due to concerns about animal welfare and the use of antibiotics in conventional farming. On the other hand, providing animals with a more natural lifestyle implies their increased exposure to environmental sources of different microorganisms including pathogens. To address these concerns, we determined the abundance of antibiotic resistance and diversity within fecal microbiota in pigs kept under conventional and organic farming systems in Sweden, Denmark, France and Italy. The abundance of sul1, sul2, strA, tet(A), tet(B) and cat antibiotic resistance genes was determined in 468 samples by real-time PCR and the fecal microbiota diversity was characterized in 48 selected samples by pyrosequencing of V3/V4 regions of 16S rRNA. Contrary to our expectations, there were no extensive differences between the abundance of tested antibiotic resistance genes in microbiota originating from organic or conventionally housed pigs within individual countries. There were also no differences in the microbiota composition of organic and conventional pigs. The only significant difference was the difference in the abundance of antibiotic resistance genes in the samples from different countries. Fecal microbiota in the samples originating from southern European countries (Italy, France) exhibited significantly higher antibiotic resistance gene abundance than those from northern parts of Europe (Denmark, Sweden). Therefore, the geographical location of the herd influenced the antibiotic resistance in the fecal microbiota more than farm’s status as organic or conventional. PMID:26218075

  2. Characterization of Antibiotic Resistance Gene Abundance and Microbiota Composition in Feces of Organic and Conventional Pigs from Four EU Countries.

    PubMed

    Gerzova, Lenka; Babak, Vladimir; Sedlar, Karel; Faldynova, Marcela; Videnska, Petra; Cejkova, Darina; Jensen, Annette Nygaard; Denis, Martine; Kerouanton, Annaelle; Ricci, Antonia; Cibin, Veronica; Österberg, Julia; Rychlik, Ivan

    2015-01-01

    One of the recent trends in animal production is the revival of interest in organic farming. The increased consumer interest in organic animal farming is mainly due to concerns about animal welfare and the use of antibiotics in conventional farming. On the other hand, providing animals with a more natural lifestyle implies their increased exposure to environmental sources of different microorganisms including pathogens. To address these concerns, we determined the abundance of antibiotic resistance and diversity within fecal microbiota in pigs kept under conventional and organic farming systems in Sweden, Denmark, France and Italy. The abundance of sul1, sul2, strA, tet(A), tet(B) and cat antibiotic resistance genes was determined in 468 samples by real-time PCR and the fecal microbiota diversity was characterized in 48 selected samples by pyrosequencing of V3/V4 regions of 16S rRNA. Contrary to our expectations, there were no extensive differences between the abundance of tested antibiotic resistance genes in microbiota originating from organic or conventionally housed pigs within individual countries. There were also no differences in the microbiota composition of organic and conventional pigs. The only significant difference was the difference in the abundance of antibiotic resistance genes in the samples from different countries. Fecal microbiota in the samples originating from southern European countries (Italy, France) exhibited significantly higher antibiotic resistance gene abundance than those from northern parts of Europe (Denmark, Sweden). Therefore, the geographical location of the herd influenced the antibiotic resistance in the fecal microbiota more than farm's status as organic or conventional.

  3. Effects of organic acids on the photosynthetic and antioxidant properties and accumulations of heavy metals of Melilotus officinalis grown in Cu tailing.

    PubMed

    Han, Yulin; Wu, Xue; Gu, Jiguang; Zhao, Jiuzhou; Huang, Suzhen; Yuan, Haiyan; Fu, Jiajia

    2016-09-01

    The effect of citric acid (CA), acetic acid (Ac), and ethylene diamine tetraacetic acid (EDTA) on the photosynthetic and antioxidant properties and the accumulation of some heavy metals (HMs) of Melilotus officinalis seedling growing in Cu mine tailings for 25 days were studied. Results showed that the formation of photosynthesizing cells of M. officinalis was inhibited by EDTA at 2 mmol/kg. Photosynthetic pigment contents under EDTA of 2 mmol/kg were reduced by 26, 40, and 19 %, respectively, compared to the control. The proline contents in aboveground and underground parts increased as the level of EDTA was enhanced. CA and Ac enhanced the activities of superoxide dismutase (SOD) and peroxidase (POD) in the aboveground parts and EDTA inhibited the activity of POD in the underground parts. The addition of CA promoted significantly the growth of M. officinalis, while the biomass decreased significantly under 2 mmol/kg EDTA. Cu contents in the aboveground parts treated with 0.5 and 2.0 mmol/kg EDTA reached 175.50 and 265.17 μg/g dry weight, respectively. Ac and EDTA treatments promoted Cd to translocate from root to aboveground parts. The result indicated that M. officinalis was a tolerant species of Cu tailing and can be used to remediate Cu contaminated environment, and rationally utilization of organic acids, especially EDTA, in the phytoremediation can improve the growth and metals accumulation of M. officinalis. PMID:27255310

  4. Effects of organic acids on the photosynthetic and antioxidant properties and accumulations of heavy metals of Melilotus officinalis grown in Cu tailing.

    PubMed

    Han, Yulin; Wu, Xue; Gu, Jiguang; Zhao, Jiuzhou; Huang, Suzhen; Yuan, Haiyan; Fu, Jiajia

    2016-09-01

    The effect of citric acid (CA), acetic acid (Ac), and ethylene diamine tetraacetic acid (EDTA) on the photosynthetic and antioxidant properties and the accumulation of some heavy metals (HMs) of Melilotus officinalis seedling growing in Cu mine tailings for 25 days were studied. Results showed that the formation of photosynthesizing cells of M. officinalis was inhibited by EDTA at 2 mmol/kg. Photosynthetic pigment contents under EDTA of 2 mmol/kg were reduced by 26, 40, and 19 %, respectively, compared to the control. The proline contents in aboveground and underground parts increased as the level of EDTA was enhanced. CA and Ac enhanced the activities of superoxide dismutase (SOD) and peroxidase (POD) in the aboveground parts and EDTA inhibited the activity of POD in the underground parts. The addition of CA promoted significantly the growth of M. officinalis, while the biomass decreased significantly under 2 mmol/kg EDTA. Cu contents in the aboveground parts treated with 0.5 and 2.0 mmol/kg EDTA reached 175.50 and 265.17 μg/g dry weight, respectively. Ac and EDTA treatments promoted Cd to translocate from root to aboveground parts. The result indicated that M. officinalis was a tolerant species of Cu tailing and can be used to remediate Cu contaminated environment, and rationally utilization of organic acids, especially EDTA, in the phytoremediation can improve the growth and metals accumulation of M. officinalis.

  5. The abundance and organization of polypeptides associated with antigens of the Rh blood group system.

    PubMed

    Gardner, B; Anstee, D J; Mawby, W J; Tanner, M J; von dem Borne, A E

    1991-06-01

    Twelve murine monoclonal antibodies, which react with human red cells of common Rh phenotype but give weak or negative reactions with Rh null erythrocytes, were used in quantitative binding assays and competitive binding assays to investigate the abundance and organization of polypeptides involved in the expression of antigens of the Rh blood group system. Antibodies of the R6A-type (R6A, BRIC-69, BRIC-207) and the 2D10-type (MB-2D10, LA18.18, LA23.40) recognize related structures and 100,000-200,000 molecules of each antibody bind maximally to erythrocytes of common Rh phenotype. Antibodies of the BRIC-125 type (BRICs 32, 122, 125, 126, 168, 211) recognize structures that are unrelated to those recognized by R6A-type and 2D10-type antibodies and between 10,000 and 50,000 antibody molecules bind maximally to erythrocytes of the common Rh phenotype. The binding of antibodies of the R6A-type and the 2D10-type, but not of antibodies of the BRIC-125-type could be partially inhibited by human anti-D antibodies (polyclonal and monoclonal) and a murine anti-e-like antibody. These results are consistent with evidence (Moore & Green 1987; Avent et al., 1988b) that the Rh blood group antigens are associated with a complex that comprises two groups of related polypeptides of M(r) 30,000 and M(r) 35,000-100,000, respectively, and suggest that there are 1-2 x 10(5) copies of this complex per erythrocyte. The polypeptide recognized by antibodies of the BRIC-125 type is likely to be associated with this complex. PMID:9259831

  6. The abundance and organization of polypeptides associated with antigens of the Rh blood group system.

    PubMed

    Gardner, B; Anstee, D J; Mawby, W J; Tanner, M J; von dem Borne, A E

    1991-06-01

    Twelve murine monoclonal antibodies, which react with human red cells of common Rh phenotype but give weak or negative reactions with Rh null erythrocytes, were used in quantitative binding assays and competitive binding assays to investigate the abundance and organization of polypeptides involved in the expression of antigens of the Rh blood group system. Antibodies of the R6A-type (R6A, BRIC-69, BRIC-207) and the 2D10-type (MB-2D10, LA18.18, LA23.40) recognize related structures and 100,000-200,000 molecules of each antibody bind maximally to erythrocytes of common Rh phenotype. Antibodies of the BRIC-125 type (BRICs 32, 122, 125, 126, 168, 211) recognize structures that are unrelated to those recognized by R6A-type and 2D10-type antibodies and between 10,000 and 50,000 antibody molecules bind maximally to erythrocytes of the common Rh phenotype. The binding of antibodies of the R6A-type and the 2D10-type, but not of antibodies of the BRIC-125-type could be partially inhibited by human anti-D antibodies (polyclonal and monoclonal) and a murine anti-e-like antibody. These results are consistent with evidence (Moore & Green 1987; Avent et al., 1988b) that the Rh blood group antigens are associated with a complex that comprises two groups of related polypeptides of M(r) 30,000 and M(r) 35,000-100,000, respectively, and suggest that there are 1-2 x 10(5) copies of this complex per erythrocyte. The polypeptide recognized by antibodies of the BRIC-125 type is likely to be associated with this complex.

  7. Tectonics and the photosynthetic habitable zone (Invited)

    NASA Astrophysics Data System (ADS)

    Sleep, N. H.

    2009-12-01

    The traditional habitable zone lies between an inner stellar radius where the surface of the planet becomes too hot for liquid water carbon-based life and on outer radius, where the surface freezes. It is effectively the zone where photosynthesis is feasible. The concept extends to putative life on objects with liquid methane at the surface, like Titan. As a practical matter, photosynthesis leaves detectable biosignatures in the geological record; black shale on the Earth indicates that sulfide and probably FeO based photosynthesis existed by 3.8 Ga. The hard crustal rocks and the mantle sequester numerous photosynthetic biosignatures. Photosynthesis can produce detectable free oxygen with ozone in the atmosphere of extrasolar planets. In contrast, there is no outer limit for subsurface life in large silicate objects. Pre-photosynthetic niches are dependable but meager and not very detectable at great antiquity or great distance, with global productivity less than 1e-3 of the photosynthetic ones. Photosynthetic organisms have bountiful energy that modifies their surface environment and even tectonics. For example, metamorphic rocks formed at the expense of thick black shale are highly radioactive and hence self-fluxing. Active tectonics with volcanism and metamorphism prevents volatiles from being sequestered in the subsurface as on Mars. A heat-pipe object, like a larger Io, differs from the Earth in that the volatiles return to the deep interior distributed within massive volcanic deposits rather than concentrated in the shallow oceanic crust. One the Earth, the return of water to the surface by arc volcanoes controls its mantle abundance at the transition between behaving as a trace element and behaving as a major element that affects melting. The ocean accumulates the water that the mantle and crust do not take. The Earth has the “right” amount of water that erosion/deposition and tectonics both tend to maintain near sea level surfaces. The mantle contains

  8. Hydrogen production by photosynthetic microorganisms

    SciTech Connect

    Akano, T.; Fukatsu, K.; Miyasaka, H. |

    1996-12-31

    Hydrogen is a clean energy alternative to the fossil fuels, the main source of greenhouse gas emissions. We developed a stable system for the conversion of solar energy into hydrogen using photosynthetic microorganisms. Our system consists of the following three stages: (1) Photosynthetic starch accumulation in green microalgae (400 L x2); (2) Dark anaerobic fermentation of the algal starch biomass to produce hydrogen and organic compounds (155 L x2); and (3) Further conversion of the organic compounds to produce hydrogen using photosynthetic bacteria (three types of reactors, parallel plate, raceway, and tubular). We constructed a test plant of this process at Nankoh power plant of Kansai Electric Power Company in Osaka, Japan, and carried out a series of tests using CO{sub 2} obtained from a chemical absorption pilot-plant. The photobiological hydrogen production process used a combination of a marine alga, Chlamydomonas sp. MGA 161 and marine photosynthetic bacterium, Rhodopseudomonas sp. W-1S. The dark anaerobic fermentation of algal starch biomass was also investigated. Sustained and stable starch accumulation, starch degradation in the algal cell, and hydrogen production from algal fermentation and photosynthetic bacteria in the light were demonstrated during several experiments. 3 refs., 12 figs., 1 tab.

  9. Engineered photosynthetic bacteria, method of manufacture of biofuels

    DOEpatents

    Laible, Philip D.; Snyder, Seth W.

    2016-09-13

    The invention provides for a novel type of biofuel; a method for cleaving anchors from photosynthetic organisms; and a method for producing biofuels using photosynthetic organisms, the method comprising identifying photosynthesis co-factors and their anchors in the organisms; modifying the organisms to increase production of the anchors; accumulating biomass of the organisms in growth media; and harvesting the anchors.

  10. Enzymatic activities and prokaryotic abundance in relation to organic matter along a West-East Mediterranean transect (TRANSMED cruise).

    PubMed

    Zaccone, R; Boldrin, A; Caruso, G; La Ferla, R; Maimone, G; Santinelli, C; Turchetto, M

    2012-07-01

    The distribution of extracellular enzymatic activities (EEA) [leucine aminopeptidase (LAP), ß-glucosidase (GLU), alkaline phosphatase (AP)], as well as that of prokaryotic abundance (PA) and biomass (PB), dissolved organic carbon (DOC), particulate organic carbon and particulate total nitrogen (POC, PTN), was determined in the epi-, meso-, and bathypelagic waters of the Mediterranean Sea along a West-East transect and at one Atlantic station located outside the Strait of Gibraltar. This study represents a synoptical evaluation of the microbial metabolism during early summer. Decreasing trends with depth were observed for most of the parameters (PA, PB, AP, DOC, POC, PTN). Significant differences between the western and eastern basins of the Mediterranean Sea were found, displaying higher rates of LAP and GLU and lower C/N ratios more in the eastern than in the western areas. Conversely, in the epipelagic layer, PA and PB were found to be higher in the western than in the eastern basins. PB was significantly related to DOC concentration (all data, n = 145, r = 0.53, P < 0.01), while significant correlations of EEA with POC and PTN were found in the epipelagic layer, indicating an active response of microbial metabolism to organic substrates. Specific enzyme activities normalized to cell abundance pointed out high values of LAP and GLU in the bathypelagic layer, especially in the eastern basin, while cell-specific AP was high in the epi- and bathypelagic zone of the eastern basin indicating a rapid regeneration of inorganic P for both prokaryotes and phytoplankton needs. Low activity and abundance characterized the Atlantic station, while opposite trends of these parameters were observed along the Mediterranean transect, showing the uncoupling between abundance and activity data. In the east Mediterranean Sea, decomposition processes increased probably in response to mesoscale structures which lead to organic matter downwelling. PMID:22349935

  11. Micro-scale in situ characterisation of the organic and mineral composition of modern, hypersaline, photosynthetic microbial mats

    NASA Astrophysics Data System (ADS)

    Gautret, P.; Ramboz, C.; de Wit, R.; Delarue, F.; Orange, F.; Sorieul, S.; Westall, F.

    2012-04-01

    Physico-chemical and biological micro-scale environmental parameters within microbial mats formed in hypersaline conditions favour the precipitation of minerals, such as carbonates. We used optical microscopy and the technique "Fluorescence Induction Relaxation » (FIRe) to differentiate the photosynthetic activity of oxygenic photosynthesisers (cyanobacteria) from anoxygenic photosynthesisers (Chloroflexus-like bacteria, CFB) in samples obtained in 2011. After this preliminary investigation, we characterised the elemental composition of the different species of microorganisms, their extracellular substances (EPS), and the minerals precipitated on their surface. This study was made in-situ by µ-PIXE using the nuclear microprobe of the AIFIRA platform (CEN Bordeaux-Gradignan ; protons of 1.5 or 3MeV). With this microprobe it is possible to map the distribution of elements occurring in quantities down to several ppm, a resolution that is particularly favourable for studying microorganisms. SEM observation of the same zones allowed us to localise exactly the microbial structures (cells, EPS) and minerals analysed by nuclear probe. We were thus able to document the differential S and P concentrations in the different microbial species, the CLB being richer in P. Note that the CLB filaments are < 1 µm in diameter. We were also able to demonstrate the anti-correlation of Ca and Mg in the minerals precipitated directly on the microorganisms and on their EPS. Thus we have shown the utility of these in situ, nano-scale methods in studying microbial structures consisting of different species with different metabolic activitie, and different functional groups on their cell walls and EPS implicated in the bioprecipitation of different kinds of minerals. Such features in ancient microbial mats could aid their interpretation and possibly the distinction between ancient oxygenic and anoxygenic mats.

  12. Nanophase iron oxides as a key ultraviolet sunscreen for ancient photosynthetic microbes

    NASA Astrophysics Data System (ADS)

    Bishop, Janice L.; Louris, Stephanie K.; Rogoff, Dana A.; Rothschild, Lynn J.

    2006-07-01

    We propose that nanophase iron-oxide-bearing materials provided important niches for ancient photosynthetic microbes on the Earth that ultimately led to the oxygenation of the Earth's atmosphere and the formation of iron-oxide deposits. Atmospheric oxygen and ozone attenuate ultraviolet radiation on the Earth today providing substantial protection for photosynthetic organisms. With ultraviolet radiation fluxes likely to have been even higher on the early Earth than today, accessing solar radiation was particularly risky for early organisms. Yet, we know that photosynthesis arose early and played a critical role in subsequent evolution. Of primary importance was protection below 290 nm, where peak nucleic acid (~260 nm) and protein (~280 nm) absorptions occur. Nanophase ferric oxide/oxyhydroxide minerals absorb, and thus block, the lethal ultraviolet radiation, while transmitting light through much of the visible and near-infrared regions of interest to photosynthesis (400 to 1100 nm). Furthermore, they were available in early environments, and are synthesized by many organisms. Based on experiments using nanophase ferric oxide/oxyhydroxide minerals as a sunscreen for photosynthetic microbes, we suggest that iron, an abundant element widely used in biological mechanisms, may have provided the protection that early organisms needed in order to be able to use photosynthetically active radiation while being protected from ultraviolet-induced damage. The results of this study are broadly applicable to astrobiology because of the abundance of iron in other potentially habitable bodies and the evolutionary pressure to utilize solar radiation when available as an energy source. This model could apply to a potential life form on Mars or other bodies where liquid water and ultraviolet radiation could have been present at significant levels. Based on ferric oxide/oxyhydroxide spectral properties, likely geologic processes, and the results of experiments with the

  13. Changes in Relative Thylakoid Protein Abundance Induced by Fluctuating Light in the Diatom Thalassiosira pseudonana.

    PubMed

    Grouneva, Irina; Muth-Pawlak, Dorota; Battchikova, Natalia; Aro, Eva-Mari

    2016-05-01

    One of the hallmarks of marine diatom biology is their ability to cope with rapid changes in light availability due to mixing of the water column and the lens effect. We investigated how irradiance fluctuations influence the relative abundance of key photosynthetic proteins in the centric diatom Thalassiosira pseudonana by means of mass-spectrometry-based approaches for relative protein quantitation. Most notably, fluctuating-light conditions lead to a substantial overall up-regulation of light-harvesting complex proteins as well as several subunits of photosystems II and I. Despite an initial delay in growth under FL, there were no indications of FL-induced photosynthesis limitation, in contrast to other photosynthetic organisms. Our findings further strengthen the notion that diatoms use a qualitatively different mechanism of photosynthetic regulation in which chloroplast-mitochondria interaction has overtaken crucial regulatory processes of photosynthetic light reactions that are typical for the survival of land plants, green algae, and cyanobacteria. PMID:27025989

  14. Factors controlling the abundance of organic sulfur in flash pyrolyzates of Upper Cretaceous kerogens from Sergipe Basin, Brazil

    USGS Publications Warehouse

    Carmo, A.M.; Stankiewicz, B.A.; Mastalerz, Maria; Pratt, L.M.

    1997-01-01

    The molecular and elemental composition of immature kerogens isolated from Upper Cretaceous marine carbonates from Sergipe Basin, Brazil were investigated using combined pyrolysis-gas chromatography/mass spectrometry and organic petrographic techniques. The kerogens are predominantly composed of reddish-fluorescing amorphous organic matter (AOM) and variable amounts of yellow-fluorescing alginite and liptodetrinite. The abundance of organic sulfur in the kerogens inferred from the ratio 2-ethyl-5-methylthiophene/(1,2-dimethylbenzene + dec-1-ene) in the pyrolyzates is variable and may be related to changes in the type of primary organic input and/or to variations in rates of bacterial sulfate reduction. A concomitant increase in S/C and O/C ratios determined in situ using the electron microprobe is observed in AOM and alginites and may be related to a progressive oxidation of the organic matter during sulfurization. The S/C ratio of the AOM is systematically higher than the S C ratio of the alginites. Combined with a thiophene distribution characteristic of pyrolyzates of Type II organic matter, the higher S/C of AOM in Sergipe kerogens suggests that sulfurization and incorporation of low-molecular weight lipids derived from normal marine organic matter into the kerogen structure predominated over direct sulfurization of highly aliphatic algal biomacromolecules.The molecular and elemental composition of immature kerogens isolated from Upper Cretaceous marine carbonates from Sergipe Basin, Brazil were investigated using combined pyrolysis-gas chromatography/mass spectrometry and organic petrographic techniques. The kerogens are predominantly composed of reddish-fluorescing amorphous organic matter (AOM) and variable amounts of yellow-fluorescing alginite and liptodetrinite. The abundance of organic sulfur in the kerogens inferred from the ratio 2-ethyl-5-methylthiophene/(1,2-dimethylbenzene+dec-1-ene) in the pyrolyzates is variable and may be related to changes in

  15. Formation kinetics and abundance of organic nitrates in α-pinene ozonolysis

    NASA Astrophysics Data System (ADS)

    Berkemeier, Thomas; Ammann, Markus; Pöschl, Ulrich; Shiraiwa, Manabu

    2016-04-01

    Formation of organic nitrates affects the total atmospheric budget of oxidized nitrogen (NOy) and alters the total aerosol mass yield from secondary sources. We investigated the formation of organic nitrate species during ozonolysis of α-pinene and subsequent formation of secondary organic aerosols (SOA) using the short-lived radioactive tracer 13N inside an aerosol flow reactor (Ammann et al., 2001). The results represent direct measurements of the organic nitrate content of α-pinene secondary aerosol and give insight into the kinetics of organic nitrate formation. Organic nitrates constituted up to 40 % of aerosol mass with a pronounced influence during the initial period of particle growth. Kinetic modelling, as well as additional experiments using OH scavengers and UV irradiation, suggests that organic peroxy radicals (RO2) from the reaction of α-pinene with secondarily produced OH are important intermediates in the organic nitrate formation process. Direct oxidation of α-pinene by NO3 was found to be a less efficient pathway for formation of particle phase nitrate. The organic nitrate content decreased very slightly with an increase of relative humidity on the experimental time scale. The experiments show a tight correlation between organic nitrate content and SOA number concentrations, implying that organic nitrates play an important role in nucleation and growth of nanoparticles. Since present in large amounts in organic aerosol, organic nitrates deposited in the lung might have implications for human health as they release nitric acid upon hydrolysis, especially in regions influenced by urban pollution and large sources of monoterpene SOA precursors. References Ammann et al. (2001) Radiochimica Acta 89, 831.

  16. Accounting for non-independent detection when estimating abundance of organisms with a Bayesian approach

    USGS Publications Warehouse

    Martin, Julien; Royle, J. Andrew; MacKenzie, Darryl I.; Edwards, Holly H.; Kery, Marc; Gardner, Beth

    2011-01-01

    Summary 1. Binomial mixture models use repeated count data to estimate abundance. They are becoming increasingly popular because they provide a simple and cost-effective way to account for imperfect detection. However, these models assume that individuals are detected independently of each other. This assumption may often be violated in the field. For instance, manatees (Trichechus manatus latirostris) may surface in turbid water (i.e. become available for detection during aerial surveys) in a correlated manner (i.e. in groups). However, correlated behaviour, affecting the non-independence of individual detections, may also be relevant in other systems (e.g. correlated patterns of singing in birds and amphibians). 2. We extend binomial mixture models to account for correlated behaviour and therefore to account for non-independent detection of individuals. We simulated correlated behaviour using beta-binomial random variables. Our approach can be used to simultaneously estimate abundance, detection probability and a correlation parameter. 3. Fitting binomial mixture models to data that followed a beta-binomial distribution resulted in an overestimation of abundance even for moderate levels of correlation. In contrast, the beta-binomial mixture model performed considerably better in our simulation scenarios. We also present a goodness-of-fit procedure to evaluate the fit of beta-binomial mixture models. 4. We illustrate our approach by fitting both binomial and beta-binomial mixture models to aerial survey data of manatees in Florida. We found that the binomial mixture model did not fit the data, whereas there was no evidence of lack of fit for the beta-binomial mixture model. This example helps illustrate the importance of using simulations and assessing goodness-of-fit when analysing ecological data with N-mixture models. Indeed, both the simulations and the goodness-of-fit procedure highlighted the limitations of the standard binomial mixture model for aerial

  17. Occurrence and abundance of carbohydrates and amino compounds in sequentially extracted labile soil organic matter fractions.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study aimed to investigate the content of carbohydrates and amino compounds in three labile fraction of soil organic matter (SOM). Soil samples were collected from two agricultural fields in southern Italy and the light fraction (LF), the 500–53-µm particulate organic matter (POM) and the mobil...

  18. Weed seed persistence and microbial abundance in long-term organic and conventional cropping systems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Weed seed persistence in soil can be influenced by many factors, including crop management. This research was conducted to determine whether organic management systems with higher organic amendments and soil microbial biomass could reduce weed seed persistence compared to conventional management sy...

  19. Soil compaction and organic matter affect conifer seedling nonmycorrhizal and ectomycorrhizal root tip abundance and diversity. Forest Service research paper

    SciTech Connect

    Amaranthus, M.P.; Page-Dumroese, D.; Harvey, A.; Cazares, E.; Bednar, L.F.

    1996-05-01

    Three levels of organic matter removal (bole only; bole and crowns; and bole, crowns, and forest floor) and three levels of mechanical soil compaction (no compaction, moderate compaction, and severe soil compaction) were studied as they influence Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco) and western white pine (Pinus monticola Dougl. ex D. Don) seedlings following outplanting. Moderate and severe soil compaction significantly reduced nonmycorrhizal root tip abundance on both Douglas-fir and western white pine seedlings (p less than or equal to 0.05). Ectomycorrhizal root tip abundance was significantly reduced on Douglas-fir seedlings in severely compacted areas with bole and crowns and bole, crowns, and forest floor removed. Ectomycorrhizal diversity also was significantly reduced on Douglas-fir seedlings in all severely compacted areas.

  20. Photosynthetic Pigments in Diatoms

    PubMed Central

    Kuczynska, Paulina; Jemiola-Rzeminska, Malgorzata; Strzalka, Kazimierz

    2015-01-01

    Photosynthetic pigments are bioactive compounds of great importance for the food, cosmetic, and pharmaceutical industries. They are not only responsible for capturing solar energy to carry out photosynthesis, but also play a role in photoprotective processes and display antioxidant activity, all of which contribute to effective biomass and oxygen production. Diatoms are organisms of a distinct pigment composition, substantially different from that present in plants. Apart from light-harvesting pigments such as chlorophyll a, chlorophyll c, and fucoxanthin, there is a group of photoprotective carotenoids which includes β-carotene and the xanthophylls, diatoxanthin, diadinoxanthin, violaxanthin, antheraxanthin, and zeaxanthin, which are engaged in the xanthophyll cycle. Additionally, some intermediate products of biosynthetic pathways have been identified in diatoms as well as unusual pigments, e.g., marennine. Marine algae have become widely recognized as a source of unique bioactive compounds for potential industrial, pharmaceutical, and medical applications. In this review, we summarize current knowledge on diatom photosynthetic pigments complemented by some new insights regarding their physico-chemical properties, biological role, and biosynthetic pathways, as well as the regulation of pigment level in the cell, methods of purification, and significance in industries. PMID:26389924

  1. The Photosynthetic Cycle

    DOE R&D Accomplishments Database

    Calvin, Melvin

    1955-03-21

    A cyclic sequence of transformations, including the carboxylation of RuDP (ribulose diphosphate) and its re-formation, has been deduced as the route for the creation of reduced carbon compounds in photosynthetic organisms. With the demonstration of RuDP as substrate for the carboxylation in a cell-free system, each of the reactions has now been carried out independently in vitro. Further purification of this last enzyme system has confirmed the deduction that the carboxylation of RuDP leads directly to the two molecules of PGA (phosphoglyceric acid) involving an internal dismutation and suggesting the name "carboxydismutase" for the enzyme. As a consequence of this knowledge of each of the steps in the photosynthetic CO{sub 2} reduction cycle, it is possible to define the reagent requirements to maintain it. The net requirement for the reduction of one molecule of CO{sub 2} is four equivalents of [H]and three molecules of ATP (adenine triphosphate). These must ultimately be supplied by the photochemical reaction. Some possible ways in which this may be accomplished are discussed.

  2. Distribution and abundance of benthic organisms in the Sacramento River, California

    USGS Publications Warehouse

    Ferreira, Rodger F.; Green, D. Brady

    1977-01-01

    General comparisons were made between benthic organism samples collected in 1960-61 and 1972-73 from five sites in the Sacramento River between Red Bluff and Knights Landing, Calif. The composition of benthic organisms from both collection periods was similar. The 1972-73 data showed variable patterns in monthly changes at each site and downstream changes each month with number of organisms per square meter, number of taxa per square meter, and diversity index. Generally, the mean number of taxa per square meter and diversity index for all sampling periods were higher in the upper reach than the lower reach of the Sacramento River. (Woodard-USGS)

  3. Photosynthetic reaction centers in bacteria

    SciTech Connect

    Norris, J.R. Univ. of Chicago, IL ); Schiffer, M. )

    1990-07-30

    The photochemistry of photosynthesis begins in complexes called reaction centers. These have become model systems to study the fundamental process by which plants and bacteria convert and store solar energy as chemical free energy. In green plants, photosynthesis occurs in two systems, each of which contains a different reaction center, working in series. In one, known as photosystem 1, oxidized nicotinamide adenine dinucleotide phosphate (NADP[sup +]) is reduced to NADPH for use in a series of dark reactions called the Calvin cycle, named for Nobel Laureate Melvin Calvin, by which carbon dioxide is converted into useful fuels such as carbohydrates and sugars. In the other half of the photosynthetic machinery of green plants, called photosystem 2, water is oxidized to produce molecular oxygen. A different form of photosynthesis occurs in photosynthetic bacteria, which typically live at the bottom of ponds and feed on organic debris. Two main types of photosynthetic bacteria exist: purple and green. Neither type liberates oxygen from water. Instead, the bacteria feed on organic media or inorganic materials, such as sulfides, which are easier to reduce or oxidize than carbon dioxide or water. Perhaps in consequence, their photosynthetic machinery is simpler than that of green, oxygen-evolving plants and their primary photochemistry is better understood.

  4. Prochlorococcus, a Marine Photosynthetic Prokaryote of Global Significance

    PubMed Central

    Partensky, F.; Hess, W. R.; Vaulot, D.

    1999-01-01

    The minute photosynthetic prokaryote Prochlorococcus, which was discovered about 10 years ago, has proven exceptional from several standpoints. Its tiny size (0.5 to 0.7 μm in diameter) makes it the smallest known photosynthetic organism. Its ubiquity within the 40°S to 40°N latitudinal band of oceans and its occurrence at high density from the surface down to depths of 200 m make it presumably the most abundant photosynthetic organism on Earth. Prochlorococcus typically divides once a day in the subsurface layer of oligotrophic areas, where it dominates the photosynthetic biomass. It also possesses a remarkable pigment complement which includes divinyl derivatives of chlorophyll a (Chl a) and Chl b, the so-called Chl a2 and Chl b2, and, in some strains, small amounts of a new type of phycoerythrin. Phylogenetically, Prochlorococcus has also proven fascinating. Recent studies suggest that it evolved from an ancestral cyanobacterium by reducing its cell and genome sizes and by recruiting a protein originally synthesized under conditions of iron depletion to build a reduced antenna system as a replacement for large phycobilisomes. Environmental constraints clearly played a predominant role in Prochlorococcus evolution. Its tiny size is an advantage for its adaptation to nutrient-deprived environments. Furthermore, genetically distinct ecotypes, with different antenna systems and ecophysiological characteristics, are present at depth and in surface waters. This vertical species variation has allowed Prochlorococcus to adapt to the natural light gradient occurring in the upper layer of oceans. The present review critically assesses the basic knowledge acquired about Prochlorococcus both in the ocean and in the laboratory. PMID:10066832

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

    PubMed

    Higuchi-Takeuchi, Mieko; Morisaki, Kumiko; Toyooka, Kiminori; Numata, Keiji

    2016-01-01

    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.

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

    PubMed Central

    Higuchi-Takeuchi, Mieko; Morisaki, Kumiko; Toyooka, Kiminori; Numata, Keiji

    2016-01-01

    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. PMID:27513570

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

    PubMed

    Higuchi-Takeuchi, Mieko; Morisaki, Kumiko; Toyooka, Kiminori; Numata, Keiji

    2016-01-01

    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. PMID:27513570

  8. Monte Carlo implementation of Schiff's approximation for estimating radiative properties of homogeneous, simple-shaped and optically soft particles: Application to photosynthetic micro-organisms

    NASA Astrophysics Data System (ADS)

    Charon, Julien; Blanco, Stéphane; Cornet, Jean-François; Dauchet, Jérémi; El Hafi, Mouna; Fournier, Richard; Abboud, Mira Kaissar; Weitz, Sebastian

    2016-03-01

    In the present paper, Schiff's approximation is applied to the study of light scattering by large and optically-soft axisymmetric particles, with special attention to cylindrical and spheroidal photosynthetic micro-organisms. This approximation is similar to the anomalous diffraction approximation but includes a description of phase functions. Resulting formulations for the radiative properties are multidimensional integrals, the numerical resolution of which requires close attention. It is here argued that strong benefits can be expected from a statistical resolution by the Monte Carlo method. But designing such efficient Monte Carlo algorithms requires the development of non-standard algorithmic tricks using careful mathematical analysis of the integral formulations: the codes that we develop (and make available) include an original treatment of the nonlinearity in the differential scattering cross-section (squared modulus of the scattering amplitude) thanks to a double sampling procedure. This approach makes it possible to take advantage of recent methodological advances in the field of Monte Carlo methods, illustrated here by the estimation of sensitivities to parameters. Comparison with reference solutions provided by the T-Matrix method is presented whenever possible. Required geometric calculations are closely similar to those used in standard Monte Carlo codes for geometric optics by the computer-graphics community, i.e. calculation of intersections between rays and surfaces, which opens interesting perspectives for the treatment of particles with complex shapes.

  9. Identification, abundance and origin of atmospheric organic particulate matter in a Portuguese rural area

    NASA Astrophysics Data System (ADS)

    Pio, C. A.; Alves, C. A.; Duarte, A. C.

    Respirable suspended particles high-volume samples were collected from a coastal-rural site in the centre of Portugal in August 1997 and their solvent-extractable organic compounds were subjected to characterisation by gas chromatography-mass spectrometry. Particles were also analysed by a thermal/optical technique in order to determine their black and organic carbon content. The total lipid extract yields ranged from 20 to 63 μg m -3, containing mainly aliphatic hydrocarbons such as n-alkanes, acids, alcohols, aldehydes, ketones and polycyclic aromatic hydrocarbons. The higher input of vascular plant wax components was demonstrated by the distribution patterns of the n-alkanes, n-alkanoic acids and n-alkanols homologous series, with C max at C 29, C 22/C 24 and C 30, respectively. The CPI values for these series were in the range 1.8-9.7, being indicative of recent biogenic input from microbial lipid residues and flora epicuticular components. Specific natural constituents (e.g. phytosterols, terpenes, etc.) were identified as molecular markers. Some oxidation products from volatile organic precursors were also present in the aerosols. In addition, all samples had a component of petroleum hydrocarbons representing urban and vehicular emissions probably transported from the nearest cities and from the motorway in the vicinity. This data set could be used to make a mass balance with organic carbon, organic extracts and elutable matter, permitting also the comparison with lipid signatures observed for other regions.

  10. In vivo estimation of pigment composition and optical absorption cross-section by spectroradiometry in four aquatic photosynthetic micro-organisms.

    PubMed

    Méléder, Vona; Laviale, Martin; Jesus, Bruno; Mouget, Jean Luc; Lavaud, Johann; Kazemipour, Farzaneh; Launeau, Patrick; Barillé, Laurent

    2013-12-01

    The objective of the present study was to estimate in vivo pigment composition and to retrieve absorption cross-section values, a(∗), of photosynthetic micro-organisms using a non-invasive technique of reflectance spectrometry. To test the methodology, organisms from different taxonomical groups and different pigment composition were used (Spirulina platensis a Cyanophyta, Porphyridium cruentum a Rhodophyta, Dunaliella tertiolecta a Chlorophyta and Entomoneis paludosa a Bacillariophyta) and photoacclimated to two different irradiance levels: 25 μmol photonm(-2)s(-1) (Low Light, LL) and 500 μmol photonm(-2)s(-1) (High Light, HL). Second derivative spectra from reflectance were used to identify pigment in vivo absorption bands that were linked to specific pigments detected by high performance liquid chromatography. Whereas some absorption bands such as those induced by Chlorophyll (Chl) a (416, 440, 625 and around 675 nm) were ubiquous, others were taxonomically specific (e.g. 636 nm for Chl c in E. paludosa) and/or photo-physiological dependent (e.g. 489 nm for zeaxanthin in the HL-acclimated S. platensis). The optical absorption cross-section, a(∗), was retrieved from reflectance data using a radiative transfer model previously developed for microphytobenthos. Despite the cellular Chl a decrease observed from LL to HL (up to 88% for S. platensis), the a(∗) increased, except for P. cruentum. This was attributed to a 'package effect' and to a greater absorption by photoprotective carotenoids that did not contribute to the energy transfer to the core Chl a.

  11. In vivo estimation of pigment composition and optical absorption cross-section by spectroradiometry in four aquatic photosynthetic micro-organisms.

    PubMed

    Méléder, Vona; Laviale, Martin; Jesus, Bruno; Mouget, Jean Luc; Lavaud, Johann; Kazemipour, Farzaneh; Launeau, Patrick; Barillé, Laurent

    2013-12-01

    The objective of the present study was to estimate in vivo pigment composition and to retrieve absorption cross-section values, a(∗), of photosynthetic micro-organisms using a non-invasive technique of reflectance spectrometry. To test the methodology, organisms from different taxonomical groups and different pigment composition were used (Spirulina platensis a Cyanophyta, Porphyridium cruentum a Rhodophyta, Dunaliella tertiolecta a Chlorophyta and Entomoneis paludosa a Bacillariophyta) and photoacclimated to two different irradiance levels: 25 μmol photonm(-2)s(-1) (Low Light, LL) and 500 μmol photonm(-2)s(-1) (High Light, HL). Second derivative spectra from reflectance were used to identify pigment in vivo absorption bands that were linked to specific pigments detected by high performance liquid chromatography. Whereas some absorption bands such as those induced by Chlorophyll (Chl) a (416, 440, 625 and around 675 nm) were ubiquous, others were taxonomically specific (e.g. 636 nm for Chl c in E. paludosa) and/or photo-physiological dependent (e.g. 489 nm for zeaxanthin in the HL-acclimated S. platensis). The optical absorption cross-section, a(∗), was retrieved from reflectance data using a radiative transfer model previously developed for microphytobenthos. Despite the cellular Chl a decrease observed from LL to HL (up to 88% for S. platensis), the a(∗) increased, except for P. cruentum. This was attributed to a 'package effect' and to a greater absorption by photoprotective carotenoids that did not contribute to the energy transfer to the core Chl a. PMID:24211563

  12. Carbon uptake in low dissolved inorganic carbon environments: the effect of limited carbon availability on photosynthetic organisms in thermal waters

    NASA Astrophysics Data System (ADS)

    Myers, K. D.; Omelon, C. R.; Bennett, P.

    2010-12-01

    Photosynthesis is the primary carbon fixation process in thermal waters below 70°C, but some hydrothermal waters have extremely low dissolved inorganic carbon (DIC), potentially limiting the growth of inorganic carbon fixing organisms such as algae and cyanobacteria. To address the issue of how carbon is assimilated by phototrophs in these environments, we conducted experiments to compare inorganic carbon uptake mechanisms by two phylogenetically distinct organisms collected from geographically distinct carbon limited systems: the neutral pH geothermal waters of El Tatio, Chile, and the acidic geothermal waters of Tantalus Creek in Norris Geyser Basin, Yellowstone National Park. Discharge waters at El Tatio have low total DIC concentrations (2 to 6 ppm) found mainly as HCO3-; this is in contrast to even lower measured DIC values in Tantalus Creek (as low as 0.13 ppm) that, due to a measured pH of 2.5, exists primarily as CO2. Cyanobacteria and algae are innately physiologically plastic, and we are looking to explore the possibility that carbon limitation in these environments is extreme enough to challenge that plasticity and lead to a suite of carbon uptake adaptations. We hypothesize that these microorganisms utilize adaptive modes of Ci uptake that allow them to survive under these limiting conditions. Cyanobacteria (primarily Synechococcus spp.) isolated from El Tatio can utilize either passive CO2 uptake or active HCO3- uptake mechanisms, in contrast to the eukaryotic alga Cyanidium spp. from Tantalus Creek, which is restricted to an energy-dependent CO2 uptake mechanism. To test this hypothesis, we conducted pH drift experiments (Omelon et al., 2008) to examine changes in pH and [DIC] under a range of pH and [DIC] culture conditions. This work provides baseline information upon which we will begin to investigate the effects of low [DIC] on the growth of phototrophs collected from these and other less carbon limited systems.

  13. Photosynthetic reaction center complexes from heliobacteria

    NASA Technical Reports Server (NTRS)

    Trost, J. T.; Vermaas, W. F. J.; Blankenship, R. E.

    1991-01-01

    Photosynthetic reaction centers are pigment-protein complexes that are responsible for the transduction of light energy into chemical energy. Considerable evidence indicates that photosynthetic organisms were present very early in the evolution of life on Earth. The goal of this project is to understand the early evolutionary development of photosynthesis by examining the properties of reaction centers isolated from certain contemporary organisms that appear to contain the simplest photosynthetic reaction centers. The major focus is on the family of newly discovered strictly anaerobic photosynthetic organisms that are grouped with the gram-positive phylum of bacteria. The properties of these reactions centers suggest that they may be the descendants of an ancestor that also gave rise to Photosystem 1 found in oxygen-evolving photosynthetic organisms. Photoactive reaction center-core antenna complexes were isolated from the photosynthetic bacteria, Heliobacillus mobilis and Heliobacterium gestii, by extraction of membranes with Deriphat 160C followed by differential centrifugation and sucrose density gradient centrifugation. Other aspects of this investigation are briefly discussed.

  14. Abundance and diversity of total and nitrifying prokaryotes as influenced by biochemical quality of organic inputs combined with mineral nitrogen

    NASA Astrophysics Data System (ADS)

    Muema, Esther; Vanlauwe, Bernard; Röhl, Carolin; Cadisch, Georg; Rasche, Frank

    2014-05-01

    Ammonia-oxidizing bacteria and archaea (AOB, AOA) co-exist in soil, but they respond differently to distinct fertilization strategies in agricultural soils. Accordingly, effects of organic inputs and combination with mineral nitrogen (N) on AOB and AOA remain poorly understood. The aim of this study was to compare soil amendment with contrasting quality of organic inputs (i.e., high quality Tithonia diversifolia (TD; C/N ratio: 13, Lignin: 8.9 %; Polyphenols: 1.7 %), intermediate quality Calliandra calothyrsus (CC; 13; 13; 9.4) and low quality Zea mays (ZM; 59; 5.4; 1.2)), and combination with mineral N on the abundance (i.e., DNA-based gene quantification) and community structure (i.e., T-RFLP analysis) of total bacterial and archaea (16S rRNA gene), as well as AOB and AOA (targeting the amoA gene) communities in a Humic Nitisol. Soils (0-15 cm depth) were sampled prior to the onset of the rainy season in March 2012 in a 10 years old field experiment established in the central highlands of Kenya in 2002. Since the start of the experiment, organic inputs were applied annually at a rate of 4 Mg C ha-1 and mineral N twice a year as calcium ammonium nitrate (5Ca(NO3)2NH4NO3) at a rate of 120 kg N ha-1 growing season-1. Quality of organic inputs posed only a significant effect on the AOB community structure between TD versus ZM and CC versus ZM. Moreover, TD significantly increased the size of AOB over ZM input, while higher abundances for total bacteria, total archaea and AOA were measured in ZM and TD over CC. This was explained by high and available N in TD, but low lignin and polyphenol contents in TD and ZM as opposed to CC. AOB responded sensitively (i.e., complete community structure separation) to mineral N, specifically when combined with low quality ZM. Hence, AOB community was specifically responsive to quality of organic inputs and combination of low organic input with mineral N over AOA and total prokaryotic communities in the studied soil. The results

  15. Abundance and Characterization of Dissolved Organic Carbon in Suburban Streams of Baltimore, Maryland, USA

    NASA Astrophysics Data System (ADS)

    Mora, G.; Fazekas, M.

    2014-12-01

    The contribution of streams and rivers to the carbon cycle is significant, transporting to the oceans ~1.4 Pg C/yr, with dissolved carbon corresponding to as much as 0.7 Pg C/yr. Changes in land use have the potential effect of modifying this flux, particularly in urban areas where impervious areas are common. To investigate the effect of urbanization on riverine carbon transport, we studied four first-order streams in Towson, a suburb of Baltimore, Maryland, USA. The watersheds from the studied streams exhibit different levels of urbanization as measured by the percentage of impervious areas. Samples from these four streams were taken weekly, and several chemical constituents were measured either in the field or in the laboratory. These constituents included nitrate, dissolved organic nitrogen, pH, dissolved organic carbon (DOC), total carbon, dissolved inorganic carbon (DIC), phosphate, the carbon isotopic compositions of DOC and DIC, and fluorescence intensity of the DOC. Results show that DOC concentrations were consistently below 5 mg C/L regardless of the level of imperviousness of the watershed. Similarly, carbon isotope ratios were consistent across the studied streams, with values centered around -26.4 per mil, thus suggesting a significant influx of soil-derived organic carbon originated from C3 plants that are common in the watersheds. Confirming this interpretation, fluorescence spectroscopy data suggest a humic-like origin for the DOC of the streams, thus pointing to the heterotrophic nature of the streams. The combined results suggest that the studied streams exhibit similar DOC concentrations, carbon isotopic values, and fluorescence spectra, despite their level of impervious surfaces in their watersheds.

  16. Abundance of organic compounds photochemically produced in the atmospheres of the Outer Planets

    NASA Technical Reports Server (NTRS)

    Raulin, F.; Bossard, A.; Toupance, G.; Ponnamperuma, C.

    1979-01-01

    Organic photochemical syntheses in the Jovian atmosphere was simulated by irradiating, at 147 nm, gaseous mixtures of methane and ammonia with varying amounts of hydrogen. Some results relevant to the photochemistry of the Jupiter atmosphere at several tens of kilometers above the clouds were obtained: (1) a favorable effect of the pressure of high amounts of H2 on the yield of hydrocarbon synthesis when NH3 is mixed with CH4; (2) a very low yield of synthesis of unsaturated hydrocarbons in such conditions; and (3) the possibility of formation of detectable amounts of HCN and CH3CN.

  17. Evidence for a Role of VIPP1 in the Structural Organization of the Photosynthetic Apparatus in Chlamydomonas[W][OA

    PubMed Central

    Nordhues, André; Schöttler, Mark Aurel; Unger, Ann-Katrin; Geimer, Stefan; Schönfelder, Stephanie; Schmollinger, Stefan; Rütgers, Mark; Finazzi, Giovanni; Soppa, Barbara; Sommer, Frederik; Mühlhaus, Timo; Roach, Thomas; Krieger-Liszkay, Anja; Lokstein, Heiko; Crespo, José Luis; Schroda, Michael

    2012-01-01

    The vesicle-inducing protein in plastids (VIPP1) was suggested to play a role in thylakoid membrane formation via membrane vesicles. As this functional assignment is under debate, we investigated the function of VIPP1 in Chlamydomonas reinhardtii. Using immunofluorescence, we localized VIPP1 to distinct spots within the chloroplast. In VIPP1-RNA interference/artificial microRNA cells, we consistently observed aberrant, prolamellar body-like structures at the origin of multiple thylakoid membrane layers, which appear to coincide with the immunofluorescent VIPP1 spots and suggest a defect in thylakoid membrane biogenesis. Accordingly, using quantitative shotgun proteomics, we found that unstressed vipp1 mutant cells accumulate 14 to 20% less photosystems, cytochrome b6f complex, and ATP synthase but 30% more light-harvesting complex II than control cells, while complex assembly, thylakoid membrane ultrastructure, and bulk lipid composition appeared unaltered. Photosystems in vipp1 mutants are sensitive to high light, which coincides with a lowered midpoint potential of the QA/QA− redox couple and increased thermosensitivity of photosystem II (PSII), suggesting structural defects in PSII. Moreover, swollen thylakoids, despite reduced membrane energization, in vipp1 mutants grown on ammonium suggest defects in the supermolecular organization of thylakoid membrane complexes. Overall, our data suggest a role of VIPP1 in the biogenesis/assembly of thylakoid membrane core complexes, most likely by supplying structural lipids. PMID:22307852

  18. Assessment of Hybrid Organic-Inorganic Antimony Sulfides for Earth-Abundant Photovoltaic Applications.

    PubMed

    Yang, Ruo Xi; Butler, Keith T; Walsh, Aron

    2015-12-17

    Hybrid organic-inorganic solar absorbers are currently the subject of intense interest; however, the highest-performing materials contain Pb. Here we assess the potential of three Sb-based semiconductors: (i) Sb2S3, (ii) Cs2Sb8S13, and (iii) (CH3NH3)2Sb8S13. While the crystal structure of Sb2S3 is composed of 1D chains, 2D layers are formed in the ternary cesium and hybrid methylammonium antimony sulfide compounds. In each case, a stereochemically active Sb 5s(2) lone pair is found, resulting in a distorted coordination environment for the Sb cations. The bandgap of the binary sulfide is found to increase, while the ionization potential also changes, upon transition to the more complex compounds. Based on the predicted electronic structure, device configurations are suggested to be suitable for photovoltaic applications. PMID:26624204

  19. Assessment of Hybrid Organic-Inorganic Antimony Sulfides for Earth-Abundant Photovoltaic Applications.

    PubMed

    Yang, Ruo Xi; Butler, Keith T; Walsh, Aron

    2015-12-17

    Hybrid organic-inorganic solar absorbers are currently the subject of intense interest; however, the highest-performing materials contain Pb. Here we assess the potential of three Sb-based semiconductors: (i) Sb2S3, (ii) Cs2Sb8S13, and (iii) (CH3NH3)2Sb8S13. While the crystal structure of Sb2S3 is composed of 1D chains, 2D layers are formed in the ternary cesium and hybrid methylammonium antimony sulfide compounds. In each case, a stereochemically active Sb 5s(2) lone pair is found, resulting in a distorted coordination environment for the Sb cations. The bandgap of the binary sulfide is found to increase, while the ionization potential also changes, upon transition to the more complex compounds. Based on the predicted electronic structure, device configurations are suggested to be suitable for photovoltaic applications.

  20. Effect of flagellates on free-living bacterial abundance in an organically contaminated aquifer.

    PubMed

    Kinner, N E; Harvey, R W; Kazmierkiewicz-Tabaka, M

    1997-07-01

    Little is known about the role of protists in the saturated subsurface. Porous media microcosms, containing bacteria and protists, were used to determine whether flagellates from an organically contaminated aquifer could substantively affect the number of free-living bacteria (FLB). When flagellates were present, the 3-40% maximum breakthrough of fluorescently labelled FLB injected into the microcosms was much lower than the 60-130% observed for killed controls. Grazing and clearance rates (3-27 FLB flag-1 h-1 and 12-23 nl flag-1 h-1, respectively) calculated from the data were in the range reported for flagellates in other aqueous environments. The data provide evidence that flagellate bacterivory is an important control on groundwater FLB populations.

  1. Effect of flagellates on free-living bacterial abundance in an organically contaminated aquifer

    USGS Publications Warehouse

    Kinner, N.E.; Harvey, R.W.; Kazmierkiewicz-Tabaka, M.

    1997-01-01

    Little is known about the role of protists in the saturated subsurface. Porous media microcosms containing bacteria and protists, were used to determine whether flagellates from an organically contaminated aquifer could substantively affect the number of free- living bacteria (FLB). When flagellates were present, the 3-40% maximum breakthrough of fluorescent y labelled FLB injected into the microcosms was much lower than the 60-130% observed for killed controls Grazing and clearance rates (3-27 FLB flag-1 h-1 and 12-23 nI flag-1 h-1, respectively) calculated from the data were in the range reported for flagellates in other aqueous environments. The data provide evidence that flagellate bacterivory is an important control on groundwater FLB populations.

  2. Bryophytes as Climate Indicators: moss and liverwort photosynthetic limitations and carbon isotope signals in organic material and peat deposits

    NASA Astrophysics Data System (ADS)

    Griffiths, H.; Royles, J.; Horwath, A.; Hodell, D. A.; Convey, P.; Hodgson, D.; Wingate, L.; Ogeé, J.

    2011-12-01

    Bryophytes make a significant contribution to carbon sequestration and storage in polar, boreal, temperate and tropical biomes, and yet there is limited understanding of the determinants of carbon isotope composition. Bryophytes are poikilohydric and lack stomata in the vegetative (gametophyte) stage, and lack of roots and reliance on liquid water to maintain hydration status also imposes diffusional limitations on CO2 uptake and extent of carbon isotope discrimination. Real-time gas exchange and instantaneous discrimination studies can be used to quantify responses to liquid phase limitation. Thus, wetted tissues show less negative δ13C signals due to liquid phase conductance and, as the thallus surface dries, maximum CO2 assimilation and discrimination are attained when the limitation is primarily the internal (mesophyll) conductance. Continued desiccation then leads to additional biochemical limitation in drought tolerant species, and low discrimination, although the carbon gain is low at this time. In this paper we explore the extent of carbon isotope discrimination in bulk organic material and cellulose as a function of climatic and environmental conditions, in temperate, tropical and Antarctic bryophytes. Field studies have been used to investigate seasonal variations in precipitation and water vapour inputs for cloud forest formations as a function of bryophyte biomass, diversity and isotope composition in epiphytes (particularly leafy liverworts) along an altitudinal gradient in Peru. In the Antarctic, moss banks sampled on Signy Island consisted of only two species, primarily Chorisodontium aciphyllum and some Polytrichum strictum, allowing the collection of shallow and deep cores representative of growth over the past 200 to 2000 years. The well-preserved peat has provided data on growth (14C) and stable isotopic proxies (13C, 18O) for material contemporary with recent anthropogenic climate forcing (over the past 200 years), for comparison with longer

  3. Changing CO2 and the evolution of terrestrial and marine photosynthetic organisms during the terrestrialization process in the Palaeozoic.

    NASA Astrophysics Data System (ADS)

    Vecoli, M.; Strother, P. K.; Servais, T.

    2009-04-01

    sequestration of Corg in organic matter trapped in plant biomass, litter, soils, and buried in sediments, adding up to the better known effect of increased weathering due to the evolution of deep rooting systems during late Devonian time onwards. In this study, we also examined the potential perturbations to the phytoplankton of the mid-Palaeozoic marine realm as CO2(aq) declined and as POM and DOM delivery to the shallow shelf increased nutrient flux to the oceans. We used the fossil record of acritarchs as a proxy for the large phytoplankton of the Palaeozoic. Our data show that the standing diversity of acritarchs (genus-level taxon richness) is highly correlated with the decline in Palaeozoic pCO2 as modelled by Berner and Kothavala (2001); the two curves show the same trends, the acritarch diversity curve being offset, on average, by a -10 my time lag. We propose that the gradual (and not catastrophic as previously assumed) decline in acritarch diversity observed during late Silurian - late Devonian times was causally linked to the decline in dissolved CO2 in the oceans and the associated increase in oceanic pH, which were in turn caused by the falling pCO2 in the atmosphere. These observations appear to link the decline of the acritarchs to the rise of the terrestrial biota through the effect of terrestrialization on pCO2.

  4. Determination of Natural 14C Abundances in Dissolved Organic Carbon in Organic-Rich Marine Sediment Porewaters by Thermal Sulfate Reduction

    NASA Astrophysics Data System (ADS)

    Johnson, L.; Komada, T.

    2010-12-01

    The abundances of natural 14C in dissolved organic carbon (DOC) in the marine environment hold clues regarding the processes that influence the biogeochemical cycling of this large carbon reservoir. At present, UV irradiation is the widely accepted method for oxidizing seawater DOC for determination of their 14C abundances. This technique yields precise and accurate values with low blanks, but it requires a dedicated vacuum line, and hence can be difficult to implement. As an alternative technique that can be conducted on a standard preparatory vacuum line, we modified and tested a thermal sulfate reduction method that was previously developed to determine δ13C values of marine DOC (Fry B. et al., 1996. Analysis of marine DOC using a dry combustion method. Mar. Chem., 54: 191-201.) to determine the 14C abundances of DOC in marine sediment porewaters. In this method, the sample is dried in a 100 ml round-bottom Pyrex flask in the presence of excess oxidant (K2SO4) and acid (H3PO4), and combusted at 550 deg.C. The combustion products are cryogenically processed to collect and quantify CO2 using standard procedures. Materials we have oxidized to date range from 6-24 ml in volume, and 95-1500 μgC in size. The oxidation efficiency of this method was tested by processing known amounts of reagent-grade dextrose and sucrose (as examples of labile organic matter), tannic acid and humic acid (as examples of complex natural organic matter), and porewater DOC extracted from organic-rich nearshore sediments. The carbon yields for all of these materials averaged 99±4% (n=18). The 14C abundances of standard materials IAEA C-6 and IAEA C-5 processed by this method using >1mgC aliquots were within error of certified values. The size and the isotopic value of the blank were determined by a standard dilution technique using IAEA C-6 and IAEA C-5 that ranged in size from 150 to 1500 μgC (n=4 and 2, respectively). This yielded a blank size of 6.7±0.7 μgC, and a blank isotopic

  5. Photosynthetic complex stoichiometry dynamics in higher plants: environmental acclimation and photosynthetic flux control

    PubMed Central

    Schöttler, Mark A.; Tóth, Szilvia Z.

    2014-01-01

    The composition of the photosynthetic apparatus of higher plants is dynamically adjusted to long-term changes in environmental conditions such as growth light intensity and light quality, and to changing metabolic demands for ATP and NADPH imposed by stresses and leaf aging. By changing photosynthetic complex stoichiometry, a long-term imbalance between the photosynthetic production of ATP and NADPH and their metabolic consumption is avoided, and cytotoxic side reactions are minimized. Otherwise, an excess capacity of the light reactions, relative to the demands of primary metabolism, could result in a disturbance of cellular redox homeostasis and an increased production of reactive oxygen species, leading to the destruction of the photosynthetic apparatus and the initiation of cell death programs. In this review, changes of the abundances of the different constituents of the photosynthetic apparatus in response to environmental conditions and during leaf ontogenesis are summarized. The contributions of the different photosynthetic complexes to photosynthetic flux control and the regulation of electron transport are discussed. PMID:24860580

  6. Photosynthetic water splitting

    SciTech Connect

    Greenbaum, E.

    1981-01-01

    The photosynthetic unit of hydrogen evolution, the turnover time of photosynthetic hydrogen production, and hydrogenic photosynthesis are discussed in the section on previous work. Recent results are given on simultaneous photoproduction of hydrogen and oxygen, kinetic studies, microscopic marine algae-seaweeds, and oxygen profiles.

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

    NASA Technical Reports Server (NTRS)

    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.

  8. Photosynthetic reaction center complexes from heliobacteria

    NASA Technical Reports Server (NTRS)

    Trost, J. T.; Vermaas, W. F. J.; Blankenship, R. E.

    1991-01-01

    The goal of this project is to understand the early evolutionary development of photosynthesis by examining the properties of reaction centers isolated from certain contemporary organisms that appear to contain the simplest photosynthetic reaction centers. The major focus of this project is the family of newly discovered strictly anaerobic photosynthetic organisms known as Heliobacteria. These organisms are the only known photosynthetic organisms that are grouped with the gram-positive phylum of bacteria. The properties of these reaction centers suggest that they might be the decendants of an ancestor that also gave rise to Photosystem 1 found in oxygen-evolving photosynthetic organisms. Photoactive reaction center-core antenna complexes have been isolated from the photosynthetic bacteria Heliobacillus mobilis and Heliobacterium gestii. The absorption and fluorescence properties of membranes and reaction centers are almost identical, suggesting that a single pigment-protein complex serves as both antenna and reaction center. Experiments in progress include sequence determination of the 48,000 Mr reaction center protein, and evolutionary comparisons with other reaction center proteins.

  9. [Regulation of alternative CO{sub 2} fixation pathways in prokaryotic and eukaryotic photosynthetic organisms]. Progress report, June 15, 1991--June 14, 1993

    SciTech Connect

    Tabita, R.

    1993-12-31

    The goal of this project to determine how photosynthetic microorganisms regulate the assimilation of CO{sub 2} via pathways alternative to the usual Calvin-Benson-Bassham reductive pentose phosphate scheme, particularly in the molecular basis for switches in CO{sub 2} metabolic paths. We have identified proteins on one-dimensional and two-dimensional SDS gels that appear differentially expressed in R. sphaeroides strain 16PHC which may be due to a mutation or change in some locus that controls the expression of several genes and their products. Similar observations were made relative to R. rubrum I-19 and the wild-type, namely that additional protein bands were observed in extracts of I-19 compared to the wild-type when both were grown photoheterotrophically with malate as electron donor and CO{sub 2} as the obligatory electron acceptor. The results of Tn5 mutagenesis of R. sphaeroides 16PHC resulted in the isolation of several strains that effectively changed back to the 16 phenotype; i.e., no malate-dependent phototrophic growth with CO{sub 2} as electron acceptor. We have found that both wild-type R. sphaeroides and R. rubrum, and the respective RubisCO negative mutant strains, are all capable of photolithoautotrophic growth using reduced sulfur compounds as electron donors and CO{sub 2} as the sole carbon source and electron acceptor. The fact that the RubisCO negative are capable of photoautotrophic growth is an exciting development for us because it proves that alternative or nonCalvin CO{sub 2} fixation pathways are extremely important to the overall carbon metabolism of these organisms. Moreover, wild-type strains turn off the synthesis of RubisCO under these cultural conditions. Thus, there appears to be separate autotrophic CO{sub 2} fixation pathways in these organisms, and a major emphasis has been placed to identify how these bacteria can grow autotrophically and fix CO{sub 2} in the absence of RubisCO.

  10. Clade-Specific Quantitative Analysis of Photosynthetic Gene Expression in Prochlorococcus

    PubMed Central

    Fernández-Pinos, María-Carmen; Casado, Marta; Caballero, Gemma; Zinser, Erik R.; Dachs, Jordi; Piña, Benjamin

    2015-01-01

    Newly designed primers targeting rbcL (CO2 fixation), psbA (photosystem II) and rnpB (reference) genes were used in qRT-PCR assays to assess the photosynthetic capability of natural communities of Prochlorococcus, the most abundant photosynthetic organism on Earth and a major contributor to primary production in oligotrophic oceans. After optimizing sample collection methodology, we analyzed a total of 62 stations from the Malaspina 2010 circumnavigation (including Atlantic, Pacific and Indian Oceans) at three different depths. Sequence and quantitative analyses of the corresponding amplicons showed the presence of high-light (HL) and low-light (LL) Prochlorococcus clades in essentially all 182 samples, with a largely uniform stratification of LL and HL sequences. Synechococcus cross-amplifications were detected by the taxon-specific melting temperatures of the amplicons. Laboratory exposure of Prochlorococcus MED4 (HL) and MIT9313 (LL) strains to organic pollutants (PAHs and organochlorine compounds) showed a decrease of rbcL transcript abundances, and of the rbcL to psbA ratios for both strains. We propose this technique as a convenient assay to evaluate effects of environmental stressors, including pollution, on the oceanic Prochlorococcus photosynthetic function. PMID:26244890

  11. Clade-Specific Quantitative Analysis of Photosynthetic Gene Expression in Prochlorococcus.

    PubMed

    Fernández-Pinos, María-Carmen; Casado, Marta; Caballero, Gemma; Zinser, Erik R; Dachs, Jordi; Piña, Benjamin

    2015-01-01

    Newly designed primers targeting rbcL (CO2 fixation), psbA (photosystem II) and rnpB (reference) genes were used in qRT-PCR assays to assess the photosynthetic capability of natural communities of Prochlorococcus, the most abundant photosynthetic organism on Earth and a major contributor to primary production in oligotrophic oceans. After optimizing sample collection methodology, we analyzed a total of 62 stations from the Malaspina 2010 circumnavigation (including Atlantic, Pacific and Indian Oceans) at three different depths. Sequence and quantitative analyses of the corresponding amplicons showed the presence of high-light (HL) and low-light (LL) Prochlorococcus clades in essentially all 182 samples, with a largely uniform stratification of LL and HL sequences. Synechococcus cross-amplifications were detected by the taxon-specific melting temperatures of the amplicons. Laboratory exposure of Prochlorococcus MED4 (HL) and MIT9313 (LL) strains to organic pollutants (PAHs and organochlorine compounds) showed a decrease of rbcL transcript abundances, and of the rbcL to psbA ratios for both strains. We propose this technique as a convenient assay to evaluate effects of environmental stressors, including pollution, on the oceanic Prochlorococcus photosynthetic function.

  12. Clade-Specific Quantitative Analysis of Photosynthetic Gene Expression in Prochlorococcus.

    PubMed

    Fernández-Pinos, María-Carmen; Casado, Marta; Caballero, Gemma; Zinser, Erik R; Dachs, Jordi; Piña, Benjamin

    2015-01-01

    Newly designed primers targeting rbcL (CO2 fixation), psbA (photosystem II) and rnpB (reference) genes were used in qRT-PCR assays to assess the photosynthetic capability of natural communities of Prochlorococcus, the most abundant photosynthetic organism on Earth and a major contributor to primary production in oligotrophic oceans. After optimizing sample collection methodology, we analyzed a total of 62 stations from the Malaspina 2010 circumnavigation (including Atlantic, Pacific and Indian Oceans) at three different depths. Sequence and quantitative analyses of the corresponding amplicons showed the presence of high-light (HL) and low-light (LL) Prochlorococcus clades in essentially all 182 samples, with a largely uniform stratification of LL and HL sequences. Synechococcus cross-amplifications were detected by the taxon-specific melting temperatures of the amplicons. Laboratory exposure of Prochlorococcus MED4 (HL) and MIT9313 (LL) strains to organic pollutants (PAHs and organochlorine compounds) showed a decrease of rbcL transcript abundances, and of the rbcL to psbA ratios for both strains. We propose this technique as a convenient assay to evaluate effects of environmental stressors, including pollution, on the oceanic Prochlorococcus photosynthetic function. PMID:26244890

  13. Resolving the influence of nitrogen abundances on sediment organic matter in macrophyte-dominated lakes, using fluorescence spectroscopy.

    PubMed

    Yao, Xin; Wang, Shengrui; Jiao, Lixin; Yan, Caihong; Jin, Xiangcan

    2015-01-01

    A controlled experiment was designed to resolve the influence of nitrogen abundance on sediment organic matters in macrophyte-dominated lakes using fluorescence analysis. Macrophyte biomass showed coincident growth trends with time, but different variation rates with nitrogen treatment. All plant growth indexes with nitrogen addition (N, NH4Cl 100, 200, 400mg/kg, respectively) were lower than those of the control group. Four humic-like components, two autochthonous tryptophan-like components, and one autochthonous tyrosine-like component were identified using the parallel factor analysis model. The results suggested that the relative component changes of fluorescence in the colonized sediments were in direct relation to the change of root biomass with time. In the experiment, the root formation parameters of the plants studied were significantly affected by adding N in sediments, which may be related to the reason that the root growth was affected by N addition. Adding a low concentration of N to sediments can play a part in supplying nutrients to the plants. However, the intensive uptake of NH4(+) may result in an increase in the intracellular concentration of ammonia, which is highly toxic to the plant cells. Hence, our experiment results manifested that organic matter cycling in the macrophyte-dominated sediment was influenced by nitrogen enrichment through influencing vegetation and relevant microbial activity. PMID:25597678

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

    DOEpatents

    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.

  15. Chronic hypoxia and VEGF differentially modulate abundance and organization of myosin heavy chain isoforms in fetal and adult ovine arteries.

    PubMed

    Hubbell, Margaret C; Semotiuk, Andrew J; Thorpe, Richard B; Adeoye, Olayemi O; Butler, Stacy M; Williams, James M; Khorram, Omid; Pearce, William J

    2012-11-15

    Chronic hypoxia increases vascular endothelial growth factor (VEGF) and thereby promotes angiogenesis. The present study explores the hypothesis that hypoxic increases in VEGF also remodel artery wall structure and contractility through phenotypic transformation of smooth muscle. Pregnant and nonpregnant ewes were maintained at sea level (normoxia) or 3,820 m (hypoxia) for the final 110 days of gestation. Common carotid arteries harvested from term fetal lambs and nonpregnant adults were denuded of endothelium and studied in vitro. Stretch-dependent contractile stresses were 32 and 77% of normoxic values in hypoxic fetal and adult arteries. Hypoxic hypocontractility was coupled with increased abundance of nonmuscle myosin heavy chain (NM-MHC) in fetal (+37%) and adult (+119%) arteries. Conversely, hypoxia decreased smooth muscle MHC (SM-MHC) abundance by 40% in fetal arteries but increased it 123% in adult arteries. Hypoxia decreased colocalization of NM-MHC with smooth muscle α-actin (SM-αA) in fetal arteries and decreased colocalization of SM-MHC with SM-αA in adult arteries. Organ culture with physiological concentrations (3 ng/ml) of VEGF-A(165) similarly depressed stretch-dependent stresses to 37 and 49% of control fetal and adult values. The VEGF receptor antagonist vatalanib ablated VEGF's effects in adult but not fetal arteries, suggesting age-dependent VEGF receptor signaling. VEGF replicated hypoxic decreases in colocalization of NM-MHC with SM-αA in fetal arteries and decreases in colocalization of SM-MHC with SM-αA in adult arteries. These results suggest that hypoxic increases in VEGF not only promote angiogenesis but may also help mediate hypoxic arterial remodeling through age-dependent changes in smooth muscle phenotype and contractility. PMID:22992677

  16. Chronic hypoxia and VEGF differentially modulate abundance and organization of myosin heavy chain isoforms in fetal and adult ovine arteries.

    PubMed

    Hubbell, Margaret C; Semotiuk, Andrew J; Thorpe, Richard B; Adeoye, Olayemi O; Butler, Stacy M; Williams, James M; Khorram, Omid; Pearce, William J

    2012-11-15

    Chronic hypoxia increases vascular endothelial growth factor (VEGF) and thereby promotes angiogenesis. The present study explores the hypothesis that hypoxic increases in VEGF also remodel artery wall structure and contractility through phenotypic transformation of smooth muscle. Pregnant and nonpregnant ewes were maintained at sea level (normoxia) or 3,820 m (hypoxia) for the final 110 days of gestation. Common carotid arteries harvested from term fetal lambs and nonpregnant adults were denuded of endothelium and studied in vitro. Stretch-dependent contractile stresses were 32 and 77% of normoxic values in hypoxic fetal and adult arteries. Hypoxic hypocontractility was coupled with increased abundance of nonmuscle myosin heavy chain (NM-MHC) in fetal (+37%) and adult (+119%) arteries. Conversely, hypoxia decreased smooth muscle MHC (SM-MHC) abundance by 40% in fetal arteries but increased it 123% in adult arteries. Hypoxia decreased colocalization of NM-MHC with smooth muscle α-actin (SM-αA) in fetal arteries and decreased colocalization of SM-MHC with SM-αA in adult arteries. Organ culture with physiological concentrations (3 ng/ml) of VEGF-A(165) similarly depressed stretch-dependent stresses to 37 and 49% of control fetal and adult values. The VEGF receptor antagonist vatalanib ablated VEGF's effects in adult but not fetal arteries, suggesting age-dependent VEGF receptor signaling. VEGF replicated hypoxic decreases in colocalization of NM-MHC with SM-αA in fetal arteries and decreases in colocalization of SM-MHC with SM-αA in adult arteries. These results suggest that hypoxic increases in VEGF not only promote angiogenesis but may also help mediate hypoxic arterial remodeling through age-dependent changes in smooth muscle phenotype and contractility.

  17. Molecular characterization of dissolved organic matter in glacial ice: coupling natural abundance 1H NMR and fluorescence spectroscopy.

    PubMed

    Pautler, Brent G; Woods, Gwen C; Dubnick, Ashley; Simpson, André J; Sharp, Martin J; Fitzsimons, Sean J; Simpson, Myrna J

    2012-04-01

    Glaciers and ice sheets are the second largest freshwater reservoir in the global hydrologic cycle, and the onset of global climate warming has necessitated an assessment of their contributions to sea-level rise and the potential release of nutrients to nearby aquatic environments. In particular, the release of dissolved organic matter (DOM) from glacier melt could stimulate microbial activity in both glacial ecosystems and adjacent watersheds, but this would largely depend on the composition of the material released. Using fluorescence and (1)H NMR spectroscopy, we characterize DOM at its natural abundance in unaltered samples from a number of glaciers that differ in geographic location, thermal regime, and sample depth. Parallel factor analysis (PARAFAC) modeling of DOM fluorophores identifies components in the ice that are predominantly proteinaceous in character, while (1)H NMR spectroscopy reveals a mixture of small molecules that likely originate from native microbes. Spectrofluorescence also reveals a terrestrial contribution that was below the detection limits of NMR; however, (1)H nuclei from levoglucosan was identified in Arctic glacier ice samples. This study suggests that the bulk of the DOM from these glaciers is a mixture of biologically labile molecules derived from microbes.

  18. "Candidatus Propionivibrio aalborgensis": A Novel Glycogen Accumulating Organism Abundant in Full-Scale Enhanced Biological Phosphorus Removal Plants.

    PubMed

    Albertsen, Mads; McIlroy, Simon J; Stokholm-Bjerregaard, Mikkel; Karst, Søren M; Nielsen, Per H

    2016-01-01

    Enhanced biological phosphorus removal (EBPR) is widely used to remove phosphorus from wastewater. The process relies on polyphosphate accumulating organisms (PAOs) that are able to take up phosphorus in excess of what is needed for growth, whereby phosphorus can be removed from the wastewater by wasting the biomass. However, glycogen accumulating organisms (GAOs) may reduce the EBPR efficiency as they compete for substrates with PAOs, but do not store excessive amounts of polyphosphate. PAOs and GAOs are thought to be phylogenetically unrelated, with the model PAO being the betaproteobacterial "Candidatus Accumulibacter phosphatis" (Accumulibacter) and the model GAO being the gammaproteobacterial "Candidatus Competibacter phosphatis". Here, we report the discovery of a GAO from the genus Propionivibrio, which is closely related to Accumulibacter. Propionivibrio sp. are targeted by the canonical fluorescence in situ hybridization probes used to target Accumulibacter (PAOmix), but do not store excessive amounts of polyphosphate in situ. A laboratory scale reactor, operated to enrich for PAOs, surprisingly contained co-dominant populations of Propionivibrio and Accumulibacter. Metagenomic sequencing of multiple time-points enabled recovery of near complete population genomes from both genera. Annotation of the Propionivibrio genome confirmed their potential for the GAO phenotype and a basic metabolic model is proposed for their metabolism in the EBPR environment. Using newly designed fluorescence in situ hybridization (FISH) probes, analyses of full-scale EBPR plants revealed that Propionivibrio is a common member of the community, constituting up to 3% of the biovolume. To avoid overestimation of Accumulibacter abundance in situ, we recommend the use of the FISH probe PAO651 instead of the commonly applied PAOmix probe set. PMID:27458436

  19. "Candidatus Propionivibrio aalborgensis": A Novel Glycogen Accumulating Organism Abundant in Full-Scale Enhanced Biological Phosphorus Removal Plants.

    PubMed

    Albertsen, Mads; McIlroy, Simon J; Stokholm-Bjerregaard, Mikkel; Karst, Søren M; Nielsen, Per H

    2016-01-01

    Enhanced biological phosphorus removal (EBPR) is widely used to remove phosphorus from wastewater. The process relies on polyphosphate accumulating organisms (PAOs) that are able to take up phosphorus in excess of what is needed for growth, whereby phosphorus can be removed from the wastewater by wasting the biomass. However, glycogen accumulating organisms (GAOs) may reduce the EBPR efficiency as they compete for substrates with PAOs, but do not store excessive amounts of polyphosphate. PAOs and GAOs are thought to be phylogenetically unrelated, with the model PAO being the betaproteobacterial "Candidatus Accumulibacter phosphatis" (Accumulibacter) and the model GAO being the gammaproteobacterial "Candidatus Competibacter phosphatis". Here, we report the discovery of a GAO from the genus Propionivibrio, which is closely related to Accumulibacter. Propionivibrio sp. are targeted by the canonical fluorescence in situ hybridization probes used to target Accumulibacter (PAOmix), but do not store excessive amounts of polyphosphate in situ. A laboratory scale reactor, operated to enrich for PAOs, surprisingly contained co-dominant populations of Propionivibrio and Accumulibacter. Metagenomic sequencing of multiple time-points enabled recovery of near complete population genomes from both genera. Annotation of the Propionivibrio genome confirmed their potential for the GAO phenotype and a basic metabolic model is proposed for their metabolism in the EBPR environment. Using newly designed fluorescence in situ hybridization (FISH) probes, analyses of full-scale EBPR plants revealed that Propionivibrio is a common member of the community, constituting up to 3% of the biovolume. To avoid overestimation of Accumulibacter abundance in situ, we recommend the use of the FISH probe PAO651 instead of the commonly applied PAOmix probe set.

  20. “Candidatus Propionivibrio aalborgensis”: A Novel Glycogen Accumulating Organism Abundant in Full-Scale Enhanced Biological Phosphorus Removal Plants

    PubMed Central

    Albertsen, Mads; McIlroy, Simon J.; Stokholm-Bjerregaard, Mikkel; Karst, Søren M.; Nielsen, Per H.

    2016-01-01

    Enhanced biological phosphorus removal (EBPR) is widely used to remove phosphorus from wastewater. The process relies on polyphosphate accumulating organisms (PAOs) that are able to take up phosphorus in excess of what is needed for growth, whereby phosphorus can be removed from the wastewater by wasting the biomass. However, glycogen accumulating organisms (GAOs) may reduce the EBPR efficiency as they compete for substrates with PAOs, but do not store excessive amounts of polyphosphate. PAOs and GAOs are thought to be phylogenetically unrelated, with the model PAO being the betaproteobacterial “Candidatus Accumulibacter phosphatis” (Accumulibacter) and the model GAO being the gammaproteobacterial “Candidatus Competibacter phosphatis”. Here, we report the discovery of a GAO from the genus Propionivibrio, which is closely related to Accumulibacter. Propionivibrio sp. are targeted by the canonical fluorescence in situ hybridization probes used to target Accumulibacter (PAOmix), but do not store excessive amounts of polyphosphate in situ. A laboratory scale reactor, operated to enrich for PAOs, surprisingly contained co-dominant populations of Propionivibrio and Accumulibacter. Metagenomic sequencing of multiple time-points enabled recovery of near complete population genomes from both genera. Annotation of the Propionivibrio genome confirmed their potential for the GAO phenotype and a basic metabolic model is proposed for their metabolism in the EBPR environment. Using newly designed fluorescence in situ hybridization (FISH) probes, analyses of full-scale EBPR plants revealed that Propionivibrio is a common member of the community, constituting up to 3% of the biovolume. To avoid overestimation of Accumulibacter abundance in situ, we recommend the use of the FISH probe PAO651 instead of the commonly applied PAOmix probe set. PMID:27458436

  1. How Cyanobacterial Distributions Reveal Flow and Irradiance Conditions of Photosynthetic Biofilm Formation

    NASA Technical Reports Server (NTRS)

    Prufert-Bebout, Lee; DeVincenzi, Donald L. (Technical Monitor)

    2001-01-01

    Microbial life on Earth is enormously abundant at sediment-water interfaces. The fossil record in fact contains abundant evidence of the preservation of life on such surfaces. It is therefore critical to our interpretation of early Earth history, and potentially to history of life on other planets, to be able to recognize life forms at these interfaces. On Earth this life often occurs as organized structures of microbes and their extracellular exudates known as biofilms. When such biofilms occur in areas receiving sunlight photosynthetic biofilms are the dominant form in natural ecosystems due to selective advantage inherent in their ability to utilize solar energy. Cyanobacteria are the dominant phototrophic microbes in most modern and ancient photosynthetic biofilms, microbial mats and stromatolites. Due to their long (3.5 billion year) evolutionary history, this group has extensively diversified resulting in an enormous array of morphologies and physiological abilities. This enormous diversity and specialization results in very specific selection for a particular cyanobacterium in each available photosynthetic niche. Furthermore these organisms can alter their spatial orientation, cell morphology, pigmentation and associations with heterotrophic organisms in order to fine tune their optimization to a given micro-niche. These adaptations can be detected, and if adequate knowledge of the interaction between environmental conditions and organism response is available, the detectable organism response can be used to infer the environmental conditions causing that response. This presentation will detail two specific examples which illustrate this point, Light and water are essential to photosynthesis in cyanobacteria and these organisms have specific detectable behavioural responses to these parameters. We will present cyanobacterial responses to quantified flow and irradiance to demonstrate the interpretative power of distribution and orientation information. This

  2. Regulation of Photosynthetic Electron Transport and Photoinhibition

    PubMed Central

    Roach, Thomas; Krieger-Liszkay, Anja Krieger

    2014-01-01

    Photosynthetic organisms and isolated photosystems are of interest for technical applications. In nature, photosynthetic electron transport has to work efficiently in contrasting environments such as shade and full sunlight at noon. Photosynthetic electron transport is regulated on many levels, starting with the energy transfer processes in antenna and ending with how reducing power is ultimately partitioned. This review starts by explaining how light energy can be dissipated or distributed by the various mechanisms of non-photochemical quenching, including thermal dissipation and state transitions, and how these processes influence photoinhibition of photosystem II (PSII). Furthermore, we will highlight the importance of the various alternative electron transport pathways, including the use of oxygen as the terminal electron acceptor and cyclic flow around photosystem I (PSI), the latter which seem particularly relevant to preventing photoinhibition of photosystem I. The control of excitation pressure in combination with the partitioning of reducing power influences the light-dependent formation of reactive oxygen species in PSII and in PSI, which may be a very important consideration to any artificial photosynthetic system or technical device using photosynthetic organisms. PMID:24678670

  3. Occurrence and forms of Kranz anatomy in photosynthetic organs and characterization of NAD-ME subtype C4 photosynthesis in Blepharis ciliaris (L.) B. L. Burtt (Acanthaceae).

    PubMed

    Akhani, Hossein; Ghasemkhani, Maraym; Chuong, Simon D X; Edwards, Gerald E

    2008-01-01

    Blepharis (Acanthaceae) is an Afroasiatic genus comprising 129 species which occur in arid and semi-arid habitats. This is the only genus in the family which is reported to have some C(4) species. Blepharis ciliaris (L.) B. L. Burtt. is a semi-desert species with distribution in Iran, Oman, and Pakistan. Its form of photosynthesis was investigated by studying different organs. C(4)-type carbon isotope composition, the presence of atriplicoid type Kranz anatomy, and compartmentation of starch all indicate performance of C(4) photosynthesis in cotyledons, leaves, and the lamina part of bracts. A continuous layer of distinctive bundle sheath cells (Kranz cells) encircle the vascular bundles in cotyledons and the lateral vascular bundles in leaves. In older leaves, there is extensive development of ground tissue in the midrib and the Kranz tissue becomes interrupted on the abaxial side, and then becomes completely absent in the mature leaf base. Cotyledons have 5-6 layers, and leaves 2-3 layers, of spongy chlorenchyma beneath the veins near the adaxial side of the leaf, indicating bifacial organization of chlorenchyma. As the plant matures, bracts and spines develop and contribute to carbon assimilation through an unusual arrangement of Kranz anatomy which depends on morphology and exposure to light. Stems do not contribute to carbon assimilation, as they lack chlorenchyma tissue and Kranz anatomy. Analysis of C(4) acid decarboxylases by western blot indicates B. ciliaris is an NAD-malic enzyme type C(4) species, which is consistent with the Kranz cells having chloroplasts with well-developed grana and abundant mitochondria.

  4. The abundance of a single domain cyclophilin in Solanaceae is regulated as a function of organ type and high temperature and not by other environmental constraints.

    PubMed

    Kiełbowicz-Matuk, Agnieszka; Rey, Pascal; Rorat, Tadeusz

    2007-11-01

    The abundance of a single domain cyclophilin (CyP), designated as SsCyP, was investigated in Solanum sogarandinum and Solanum tuberosum plants during development and in response to various environmental constraints. We show that under control conditions, SsCyP is distributed throughout the plant but in an organ-specific manner. In both Solanum species, the highest protein levels are observed in transporting organs and in tubers, and substantial amounts are noticed in open flowers and in stamens. We also show that the SsCyP abundance in leaves strongly decreases with age. In in vitro-grown plantlets of S. sogarandinum, the SsCyP gene is induced by low temperature at the transcript level but not at the protein level, indicating that post-transcriptional mechanisms control SsCyP expression under cold conditions. In in vivo-grown Solanum plants, the organ-dependent SsCyP protein distribution and abundance are not modified by cold, drought, salinity and photooxidative treatments. In contrast, the protein abundance substantially decreases in all organs of Solanum plants subjected to heat shock. We conclude that the SsCyP protein acts mainly during development and does not belong to the group of stress-induced CyPs.

  5. Terracidiphilus gabretensis gen. nov., sp. nov., an Abundant and Active Forest Soil Acidobacterium Important in Organic Matter Transformation

    PubMed Central

    García-Fraile, Paula; Benada, Oldrich; Cajthaml, Tomáš; Baldrian, Petr

    2015-01-01

    Understanding the activity of bacteria in coniferous forests is highly important, due to the role of these environments as a global carbon sink. In a study of the microbial biodiversity of montane coniferous forest soil in the Bohemian Forest National Park (Czech Republic), we succeeded in isolating bacterial strain S55T, which belongs to one of the most abundant operational taxonomic units (OTUs) in active bacterial populations, according to the analysis of RNA-derived 16S rRNA amplicons. The 16S rRNA gene sequence analysis showed that the species most closely related to strain S55T include Bryocella elongata SN10T (95.4% identity), Acidicapsa ligni WH120T (95.2% identity), and Telmatobacter bradus TPB6017T (95.0% identity), revealing that strain S55T should be classified within the phylum Acidobacteria, subdivision 1. Strain S55T is a rod-like bacterium that grows at acidic pH (3 to 6). Its phylogenetic, genotypic, phenotypic, and chemotaxonomic characteristics indicate that strain S55T corresponds to a new genus within the phylum Acidobacteria; thus, we propose the name Terracidiphilus gabretensis gen. nov., sp. nov. (strain S55T = NBRC 111238T = CECT 8791T). This strain produces extracellular enzymes implicated in the degradation of plant-derived biopolymers. Moreover, analysis of the genome sequence of strain S55T also reveals the presence of enzymatic machinery required for organic matter decomposition. Soil metatranscriptomic analyses found 132 genes from strain S55T being expressed in the forest soil, especially during winter. Our results suggest an important contribution of T. gabretensis S55T in the carbon cycle in the Picea abies coniferous forest. PMID:26546425

  6. Enhanced practical photosynthetic CO2 mitigation

    DOEpatents

    Bayless, David J.; Vis-Chiasson, Morgan L.; Kremer, Gregory G.

    2003-12-23

    This process is unique in photosynthetic carbon sequestration. An on-site biological sequestration system directly decreases the concentration of carbon-containing compounds in the emissions of fossil generation units. In this process, photosynthetic microbes are attached to a growth surface arranged in a containment chamber that is lit by solar photons. A harvesting system ensures maximum organism growth and rate of CO.sub.2 uptake. Soluble carbon and nitrogen concentrations delivered to the cyanobacteria are enhanced, further increasing growth rate and carbon utilization.

  7. Characterisation of antioxidants in photosynthetic and non-photosynthetic leaf tissues of variegated Pelargonium zonale plants.

    PubMed

    Vidović, M; Morina, F; Milić-Komić, S; Vuleta, A; Zechmann, B; Prokić, Lj; Veljović Jovanović, S

    2016-07-01

    Hydrogen peroxide is an important signalling molecule, involved in regulation of numerous metabolic processes in plants. The most important sources of H2 O2 in photosynthetically active cells are chloroplasts and peroxisomes. Here we employed variegated Pelargonium zonale to characterise and compare enzymatic and non-enzymatic components of the antioxidative system in autotrophic and heterotrophic leaf tissues at (sub)cellular level under optimal growth conditions. The results revealed that both leaf tissues had specific strategies to regulate H2 O2 levels. In photosynthetic cells, the redox regulatory system was based on ascorbate, and on the activities of thylakoid-bound ascorbate peroxidase (tAPX) and catalase. In this leaf tissue, ascorbate was predominantly localised in the nucleus, peroxisomes, plastids and mitochondria. On the other hand, non-photosynthetic cells contained higher glutathione content, mostly located in mitochondria. The enzymatic antioxidative system in non-photosynthetic cells relied on the ascorbate-glutathione cycle and both Mn and Cu/Zn superoxide dismutase. Interestingly, higher content of ascorbate and glutathione, and higher activities of APX in the cytosol of non-photosynthetic leaf cells compared to the photosynthetic ones, suggest the importance of this compartment in H2 O2 regulation. Together, these results imply different regulation of processes linked with H2 O2 signalling at subcellular level. Thus, we propose green-white variegated leaves as an excellent system for examination of redox signal transduction and redox communication between two cell types, autotrophic and heterotrophic, within the same organ.

  8. "PP2C7s", Genes Most Highly Elaborated in Photosynthetic Organisms, Reveal the Bacterial Origin and Stepwise Evolution of PPM/PP2C Protein Phosphatases.

    PubMed

    Kerk, David; Silver, Dylan; Uhrig, R Glen; Moorhead, Greg B G

    2015-01-01

    Mg+2/Mn+2-dependent type 2C protein phosphatases (PP2Cs) are ubiquitous in eukaryotes, mediating diverse cellular signaling processes through metal ion catalyzed dephosphorylation of target proteins. We have identified a distinct PP2C sequence class ("PP2C7s") which is nearly universally distributed in Eukaryotes, and therefore apparently ancient. PP2C7s are by far most prominent and diverse in plants and green algae. Combining phylogenetic analysis, subcellular localization predictions, and a distillation of publically available gene expression data, we have traced the evolutionary trajectory of this gene family in photosynthetic eukaryotes, demonstrating two major sequence assemblages featuring a succession of increasingly derived sub-clades. These display predominant expression moving from an ancestral pattern in photosynthetic tissues toward non-photosynthetic, specialized and reproductive structures. Gene co-expression network composition strongly suggests a shifting pattern of PP2C7 gene functions, including possible regulation of starch metabolism for one homologue set in Arabidopsis and rice. Distinct plant PP2C7 sub-clades demonstrate novel amino terminal protein sequences upon motif analysis, consistent with a shifting pattern of regulation of protein function. More broadly, neither the major events in PP2C sequence evolution, nor the origin of the diversity of metal binding characteristics currently observed in different PP2C lineages, are clearly understood. Identification of the PP2C7 sequence clade has allowed us to provide a better understanding of both of these issues. Phylogenetic analysis and sequence comparisons using Hidden Markov Models strongly suggest that PP2Cs originated in Bacteria (Group II PP2C sequences), entered Eukaryotes through the ancestral mitochondrial endosymbiosis, elaborated in Eukaryotes, then re-entered Bacteria through an inter-domain gene transfer, ultimately producing bacterial Group I PP2C sequences. A key evolutionary

  9. "PP2C7s", Genes Most Highly Elaborated in Photosynthetic Organisms, Reveal the Bacterial Origin and Stepwise Evolution of PPM/PP2C Protein Phosphatases

    PubMed Central

    Kerk, David; Silver, Dylan; Uhrig, R. Glen; Moorhead, Greg B. G.

    2015-01-01

    Mg+2/Mn+2-dependent type 2C protein phosphatases (PP2Cs) are ubiquitous in eukaryotes, mediating diverse cellular signaling processes through metal ion catalyzed dephosphorylation of target proteins. We have identified a distinct PP2C sequence class (“PP2C7s”) which is nearly universally distributed in Eukaryotes, and therefore apparently ancient. PP2C7s are by far most prominent and diverse in plants and green algae. Combining phylogenetic analysis, subcellular localization predictions, and a distillation of publically available gene expression data, we have traced the evolutionary trajectory of this gene family in photosynthetic eukaryotes, demonstrating two major sequence assemblages featuring a succession of increasingly derived sub-clades. These display predominant expression moving from an ancestral pattern in photosynthetic tissues toward non-photosynthetic, specialized and reproductive structures. Gene co-expression network composition strongly suggests a shifting pattern of PP2C7 gene functions, including possible regulation of starch metabolism for one homologue set in Arabidopsis and rice. Distinct plant PP2C7 sub-clades demonstrate novel amino terminal protein sequences upon motif analysis, consistent with a shifting pattern of regulation of protein function. More broadly, neither the major events in PP2C sequence evolution, nor the origin of the diversity of metal binding characteristics currently observed in different PP2C lineages, are clearly understood. Identification of the PP2C7 sequence clade has allowed us to provide a better understanding of both of these issues. Phylogenetic analysis and sequence comparisons using Hidden Markov Models strongly suggest that PP2Cs originated in Bacteria (Group II PP2C sequences), entered Eukaryotes through the ancestral mitochondrial endosymbiosis, elaborated in Eukaryotes, then re-entered Bacteria through an inter-domain gene transfer, ultimately producing bacterial Group I PP2C sequences. A key

  10. The relationship of metals, bifenthrin, physical habitat metrics, grain size, total organic carbon, dissolved oxygen and conductivity to Hyalella sp. abundance in urban California streams.

    PubMed

    Hall, Lenwood W; Anderson, Ronald D

    2013-01-01

    The objectives of this study were to determine the relationship between Hyalella sp. abundance in four urban California streams and the following parameters: (1) 8 bulk metals (As, Cd, Cr, Cu, Pb, Hg, Ni, and Zn) and their associated sediment Threshold Effect Levels (TELs); (2) bifenthrin sediment concentrations; (3) 10 habitat metrics and total score; (4) grain size (% sand, silt and clay); (5) Total Organic Carbon (TOC); (6) dissolved oxygen; and (7) conductivity. California stream data used for this study were collected from Kirker Creek (2006 and 2007), Pleasant Grove Creek (2006, 2007 and 2008), Salinas streams (2009 and 2010) and Arcade Creek (2009 and 2010). Hyalella abundance in the four California streams generally declined when metals concentrations were elevated beyond the TELs. There was also a statistically significant negative relationship between Hyalella abundance and % silt for these 4 California streams as Hyalella were generally not present in silt areas. No statistically significant relationships were reported between Hyalella abundance and metals concentrations, bifenthrin concentrations, habitat metrics, % sand, % clay, TOC, dissolved oxygen and conductivity. The results from this study highlight the complexity of assessing which factors are responsible for determining the abundance of amphipods, such as Hyalella sp., in the natural environment.

  11. [Influences of long-term application of organic and inorganic fertilizers on the composition and abundance of nirS-type denitrifiers in black soil].

    PubMed

    Yin, Chang; Fan, Fen-Liang; Li, Zhao-Jun; Song, A-Lin; Zhu, Ping; Peng, Chang; Liang, Yong-Chao

    2012-11-01

    The objectives of this study were to explore the effects of long-term organic and inorganic fertilizations on the composition and abundance of nirS-type denitrifiers in black soil. Soil samples were collected from 4 treatments (i. e. no fertilizer treatment, CK; organic manure treatment, OM; chemical fertilizer treatment (NPK) and combination of organic and chemical fertilizers treatment (MNPK)) in Gongzhuling Long-term Fertilization Experiment Station. Composition and abundance of nirS-type denitrifiers were analyzed with terminal restriction fragment length polymorphism (T-RFLP) and real-time quantitative PCR (Q-PCR), respectively. Denitrification enzyme activity (DEA) and soil properties were also measured. Application of organic fertilizers (OM and MNPK) significantly increased the DEAs of black soil, with the DEAs in OM and MNPK being 5.92 and 6.03 times higher than that in CK treatment, respectively, whereas there was no significant difference between NPK and CK. OM and MNPK treatments increased the abundances of nirS-type denitrifiers by 2.73 and 3.83 times relative to that of CK treatment, respectively. The abundance of nirS-type denitrifiers in NPK treatment was not significantly different from that of CK. The T-RFLP analysis of nirS genes showed significant differences in community composition between organic and inorganic treatments, with the emergence of a 79 bp T-RF, a significant decrease in relative abundance of the 84 bp T-RF and a loss of the 99 bp T-RF in all organic treatments. Phylogenetic analysis indicated that the airS-type denitrifiers in the black soil were mainly composed of alpha, beta and gamma-Proteobacteria. The 79 bp-type denitrifiers inhabiting exclusively in organic treatments (OM and MNPK) were affiliated to Pseudomonadaceae in gamma-Proteobacteria and Burkholderiales in beta-Proteobacteria. The 84 bp-types were related to Burkholderiales and Rhodocyclales. Correlation analysis indicated that pH, concentrations of total nitrogen

  12. Mapping the spectral variability in photosynthetic and non-photosynthetic vegetation, soils, and shade using AVIRIS

    NASA Technical Reports Server (NTRS)

    Roberts, Dar A.; Smith, Milton O.; Sabol, Donald E.; Adams, John B.; Ustin, Susan L.

    1992-01-01

    The primary objective of this research was to map as many spectrally distinct types of green vegetation (GV), non-photosynthetic vegetation (NPV), shade, and soil (endmembers) in an Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) scene as is warranted by the spectral variability of the data. Once determined, a secondary objective was to interpret these endmembers and their abundances spatially and spectrally in an ecological context.

  13. Determination of photosynthetic parameters in two seawater-tolerant vegetables

    NASA Astrophysics Data System (ADS)

    Qiu, Nianwei; Zhou, Feng; Liu, Qian; Zhao, Wenqian

    2016-03-01

    It is difficult to determine the photosynthetic parameters of non-flat leaves/green stems using photosynthetic instruments, due to the unusual morphology of both organs, especially for Suaeda salsa and Salicornia bigelovii as two seawater-tolerant vegetables. To solve the problem, we developed a simple, practical, and effective method to measure and calculate the photosynthetic parameters (such as P N, g s, E) based on unit fresh mass, instead of leaf area. The light/CO2/temperature response curves of the plants can also be measured by this method. This new method is more effective, stable, and reliable than conventional methods for plants with non-flat leaves. In addition, the relative notes on measurements and calculation of photosynthetic parameters were discussed in this paper. This method solves technical difficulties in photosynthetic parameter determination of the two seawater-tolerant vegetables and similar plants.

  14. Whiting events: biogenic origin due to the photosynthetic activity of cyanobacterial picoplankton

    NASA Technical Reports Server (NTRS)

    Thompson, J. B.; Schultze-Lam, S.; Beveridge, T. J.; Des Marais, D. J.

    1997-01-01

    An annual whiting event occurs each year in late May to early June in Fayetteville Green Lake, New York. The initiation of this event correlates with exponential growth of the Synechococcus population within the lake. Synechococcus is the dominant (by approximately 4 orders of magnitude) autotrophic organism owing to the oligotrophic condition of the lake. The delta 13C values of the dissolved inorganic C range seasonally from -9.5% in winter to -6.2% in summer due to photosynthetic activity. Calcite precipitates principally in the microenvironment surrounding Synechococcus because of a photosynthetically driven alkalization process and the availability of the cells as nucleation sites. This calcite has a heavier delta 13C value (>4%) than does the dissolved inorganic C of the lake water owing to the cells' preferential uptake of 12C. A conceptual model suggests that photosynthetic activity and cell surface chemistry, together with the substantial surface area that arises from the great abundance of micron-sized cells, allow Synechococcus to dominate the annual whiting events in Fayetteville Green Lake.

  15. Systems Analysis of the Response of Photosynthesis, Metabolism, and Growth to an Increase in Irradiance in the Photosynthetic Model Organism Chlamydomonas reinhardtii.

    PubMed

    Mettler, Tabea; Mühlhaus, Timo; Hemme, Dorothea; Schöttler, Mark-Aurel; Rupprecht, Jens; Idoine, Adam; Veyel, Daniel; Pal, Sunil Kumar; Yaneva-Roder, Liliya; Winck, Flavia Vischi; Sommer, Frederik; Vosloh, Daniel; Seiwert, Bettina; Erban, Alexander; Burgos, Asdrubal; Arvidsson, Samuel; Schönfelder, Stephanie; Arnold, Anne; Günther, Manuela; Krause, Ursula; Lohse, Marc; Kopka, Joachim; Nikoloski, Zoran; Mueller-Roeber, Bernd; Willmitzer, Lothar; Bock, Ralph; Schroda, Michael; Stitt, Mark

    2014-06-01

    We investigated the systems response of metabolism and growth after an increase in irradiance in the nonsaturating range in the algal model Chlamydomonas reinhardtii. In a three-step process, photosynthesis and the levels of metabolites increased immediately, growth increased after 10 to 15 min, and transcript and protein abundance responded by 40 and 120 to 240 min, respectively. In the first phase, starch and metabolites provided a transient buffer for carbon until growth increased. This uncouples photosynthesis from growth in a fluctuating light environment. In the first and second phases, rising metabolite levels and increased polysome loading drove an increase in fluxes. Most Calvin-Benson cycle (CBC) enzymes were substrate-limited in vivo, and strikingly, many were present at higher concentrations than their substrates, explaining how rising metabolite levels stimulate CBC flux. Rubisco, fructose-1,6-biosphosphatase, and seduheptulose-1,7-bisphosphatase were close to substrate saturation in vivo, and flux was increased by posttranslational activation. In the third phase, changes in abundance of particular proteins, including increases in plastidial ATP synthase and some CBC enzymes, relieved potential bottlenecks and readjusted protein allocation between different processes. Despite reasonable overall agreement between changes in transcript and protein abundance (R(2) = 0.24), many proteins, including those in photosynthesis, changed independently of transcript abundance.

  16. Systems Analysis of the Response of Photosynthesis, Metabolism, and Growth to an Increase in Irradiance in the Photosynthetic Model Organism Chlamydomonas reinhardtii[C][W][OPEN

    PubMed Central

    Mettler, Tabea; Mühlhaus, Timo; Hemme, Dorothea; Schöttler, Mark-Aurel; Rupprecht, Jens; Idoine, Adam; Veyel, Daniel; Pal, Sunil Kumar; Yaneva-Roder, Liliya; Winck, Flavia Vischi; Sommer, Frederik; Vosloh, Daniel; Seiwert, Bettina; Erban, Alexander; Burgos, Asdrubal; Arvidsson, Samuel; Schönfelder, Stephanie; Arnold, Anne; Günther, Manuela; Krause, Ursula; Lohse, Marc; Kopka, Joachim; Nikoloski, Zoran; Mueller-Roeber, Bernd; Willmitzer, Lothar; Bock, Ralph; Schroda, Michael; Stitt, Mark

    2014-01-01

    We investigated the systems response of metabolism and growth after an increase in irradiance in the nonsaturating range in the algal model Chlamydomonas reinhardtii. In a three-step process, photosynthesis and the levels of metabolites increased immediately, growth increased after 10 to 15 min, and transcript and protein abundance responded by 40 and 120 to 240 min, respectively. In the first phase, starch and metabolites provided a transient buffer for carbon until growth increased. This uncouples photosynthesis from growth in a fluctuating light environment. In the first and second phases, rising metabolite levels and increased polysome loading drove an increase in fluxes. Most Calvin-Benson cycle (CBC) enzymes were substrate-limited in vivo, and strikingly, many were present at higher concentrations than their substrates, explaining how rising metabolite levels stimulate CBC flux. Rubisco, fructose-1,6-biosphosphatase, and seduheptulose-1,7-bisphosphatase were close to substrate saturation in vivo, and flux was increased by posttranslational activation. In the third phase, changes in abundance of particular proteins, including increases in plastidial ATP synthase and some CBC enzymes, relieved potential bottlenecks and readjusted protein allocation between different processes. Despite reasonable overall agreement between changes in transcript and protein abundance (R2 = 0.24), many proteins, including those in photosynthesis, changed independently of transcript abundance. PMID:24894045

  17. Pulley reef: a deep photosynthetic coral reef on the West Florida Shelf, USA

    USGS Publications Warehouse

    Culter, J.K.; Ritchie, K.B.; Earle, S.A.; Guggenheim, D.E.; Halley, R.B.; Ciembronowicz, K.T.; Hine, A.C.; Jarrett, B.D.; Locker, S.D.; Jaap, W.C.

    2006-01-01

    Pulley Reef (24°50′N, 83°40′W) lies on a submerged late Pleistocene shoreline feature that formed during a sea-level stillstand from 13.8 to 14.5 ka (Jarrett et al. 2005). The reef is currently 60–75 m deep, exhibits 10–60% coral cover, and extends over approximately 160 km2 of the sea floor. Zooxanthellate corals are primarily Agaricia lamarcki, A. fragilis, Leptoseris cucullata, and less common Madracis formosa, M. pharensis, M. decactis, Montastraea cavernosa, Porites divaricata, Scolymia cubensis and Oculina tenella. Coralline algae are comparable in abundance to stony corals. Other macroalgae include Halimeda tuna, Dictyota divaricata, Lobophora variegata, Ventricatri ventricosa, Verdigelas pelas, and Kallymenia sp. Anadyomene menziesii is abundant. The reef provides a habitat for organisms typically observed at much shallower depths, and is the deepest known photosynthetic coral reef on the North America continental shelf (Fig. 1).

  18. Inorganic and organic fertilizers impact the abundance and proportion of antibiotic resistance and integron-integrase genes in agricultural grassland soil.

    PubMed

    Nõlvak, Hiie; Truu, Marika; Kanger, Kärt; Tampere, Mailiis; Espenberg, Mikk; Loit, Evelin; Raave, Henn; Truu, Jaak

    2016-08-15

    Soil fertilization with animal manure or its digestate may facilitate an important antibiotic resistance dissemination route from anthropogenic sources to the environment. This study examines the effect of mineral fertilizer (NH4NO3), cattle slurry and cattle slurry digestate amendment on the abundance and proportion dynamics of five antibiotic resistance genes (ARGs) and two classes of integron-integrase genes (intI1 and intI2) in agricultural grassland soil. Fertilization was performed thrice throughout one vegetation period. The targeted ARGs (sul1, tetA, blaCTX-M, blaOXA2 and qnrS) encode resistance to several major antibiotic classes used in veterinary medicine such as sulfonamides, tetracycline, cephalosporins, penicillin and fluoroquinolones, respectively. The non-fertilized grassland soil contained a stable background of tetA, blaCTX-M and sul1 genes. The type of applied fertilizer significantly affected ARGs and integron-integrase genes abundances and proportions in the bacterial community (p<0.001 in both cases), explaining 67.04% of the abundance and 42.95% of the proportion variations in the grassland soil. Both cattle slurry and cattle slurry digestate proved to be considerable sources of ARGs, especially sul1, as well as integron-integrases. Sul1, intI1 and intI2 levels in grassland soil were elevated in response to each organic fertilizer's application event, but this increase was followed by a stage of decrease, suggesting that microbes possessing these genes were predominantly entrained into soil via cattle slurry or its digestate application and had somewhat limited survival potential in a soil environment. However, the abundance of these three target genes did not decrease to a background level by the end of the study period. TetA was most abundant in mineral fertilizer treated soil and blaCTX-M in cattle slurry digestate amended soil. Despite significantly different abundances, the abundance dynamics of bacteria possessing these genes were

  19. Inorganic and organic fertilizers impact the abundance and proportion of antibiotic resistance and integron-integrase genes in agricultural grassland soil.

    PubMed

    Nõlvak, Hiie; Truu, Marika; Kanger, Kärt; Tampere, Mailiis; Espenberg, Mikk; Loit, Evelin; Raave, Henn; Truu, Jaak

    2016-08-15

    Soil fertilization with animal manure or its digestate may facilitate an important antibiotic resistance dissemination route from anthropogenic sources to the environment. This study examines the effect of mineral fertilizer (NH4NO3), cattle slurry and cattle slurry digestate amendment on the abundance and proportion dynamics of five antibiotic resistance genes (ARGs) and two classes of integron-integrase genes (intI1 and intI2) in agricultural grassland soil. Fertilization was performed thrice throughout one vegetation period. The targeted ARGs (sul1, tetA, blaCTX-M, blaOXA2 and qnrS) encode resistance to several major antibiotic classes used in veterinary medicine such as sulfonamides, tetracycline, cephalosporins, penicillin and fluoroquinolones, respectively. The non-fertilized grassland soil contained a stable background of tetA, blaCTX-M and sul1 genes. The type of applied fertilizer significantly affected ARGs and integron-integrase genes abundances and proportions in the bacterial community (p<0.001 in both cases), explaining 67.04% of the abundance and 42.95% of the proportion variations in the grassland soil. Both cattle slurry and cattle slurry digestate proved to be considerable sources of ARGs, especially sul1, as well as integron-integrases. Sul1, intI1 and intI2 levels in grassland soil were elevated in response to each organic fertilizer's application event, but this increase was followed by a stage of decrease, suggesting that microbes possessing these genes were predominantly entrained into soil via cattle slurry or its digestate application and had somewhat limited survival potential in a soil environment. However, the abundance of these three target genes did not decrease to a background level by the end of the study period. TetA was most abundant in mineral fertilizer treated soil and blaCTX-M in cattle slurry digestate amended soil. Despite significantly different abundances, the abundance dynamics of bacteria possessing these genes were

  20. On the evolution of the photosynthetic pigments.

    PubMed

    Evstigneev, V B

    1975-07-01

    During the course of terrestrial evolution, some organisms developed the capability of capturing and utilizing solar radiation. Colored compounds were undoubtedly incorporated within living forms from the earliest times, but during the transition from heterotrophic to a photoautotrophic metabolism only those pigments were selected that were components of the evolving photosynthetic apparatus and were able to catalyze reactions involving storage of light energy in chemical bonds. In this communication, some properties of tetrapyrroles with a closed porphyrin ring containing a metal ion in the center are discussed. These compounds are present in all principal contemporary photosynthetic pigments, and their synthesis has been demonstrated from simpler compounds under prebiotic conditions. It is probable that during intermediate stages in the evolution of photosynthesis, pigments with oxidizing potentials lower than that of chlorophyll were utilized to store light energy although they were not capable of removing electrons from water. The evolution and function of multiple forms of a given photosynthetic pigment in vivo are discussed. 'Accessory' pigments may be regarded as rudiments of the evolutionary development of the photosynthetic apparatus.

  1. Spatio-temporal distribution of organic and inorganic pollutants from Lake Geneva (Switzerland) reveals strong interacting effects of sewage treatment plant and eutrophication on microbial abundance.

    PubMed

    Thevenon, Florian; Graham, Neil D; Herbez, Aline; Wildi, Walter; Poté, John

    2011-07-01

    Variation with depth and time of organic matter (carbon, nitrogen, phosphorus), inorganic pollutant (mercury), as well as bacterial abundance and activity, were investigated for the first time in sediment profiles of different parts of Lake Geneva (Switzerland) over the last decades. The highest organic contents (about 32%), mercury concentration (27 mg kg(-1)), bacterial abundance (in order of 9×10(9) cell g(-1) dry sediment), and bacterial activity (1299 Relative Light Units (RLU)) were found in the highly polluted sediments contaminated by the waste water treatment plant (WWTP) discharge, which deposited during the period of cultural eutrophication. Such data, which contrast with the other sampled sites from deeper and more remote parts of the lake, prove that the organic matter and nutrients released from the municipal WWTP have considerable effects on bacterial abundance and activities in freshwater sediments. In fact, the relatively unpolluted deepwater sites and the coastal polluted site show large synchronous increases in bacterial densities linked to the anoxic conditions in the 1970s (lake eutrophication caused by external nutrient input) that subsequently increased the nutrient loading fluxes. These results show that the microbial activities response to natural or human-induced changing limnological conditions (e.g., nutrient supply, oxygen availability, redox conditions) constitutes a threat to the security of water resources, which in turn poses concerns for the world's freshwater resources in the context of global warming and the degradation of water quality (oxygen depletion in the bottom water due to reduced deep waters mixing). Moreover, the accumulation of inorganic pollutants such as high mercury (methyl-mercury) concentration may represent a significant source of toxicity for sediment dwelling organisms.

  2. Enhanced Practical Photosynthetic CO2 Mitigation

    SciTech Connect

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

    2004-10-13

    This report highlights significant achievements in the Enhanced Practical Photosynthetic CO{sub 2} Mitigation Project for the period ending 09/30/2004. The primary effort of this quarter was focused on mass transfer of carbon dioxide into the water film to study the potential effects on the photosynthetic organisms that depend on the carbon. Testing of the carbon dioxide scrubbing capability (mass transfer capability) of flowing water film appears to be relatively high and largely unaffected by transport of the gas through the bioreactor. The implications are that the transfer of carbon dioxide into the film is nearly at maximum and that it is sufficient to sustain photosynthesis at whatever rate the organisms can sustain. This finding is key to assuming that the process is an energy (photon) limited reaction and not a nutrient limited reaction.

  3. Flavodiiron Proteins in Oxygenic Photosynthetic Organisms: Photoprotection of Photosystem II by Flv2 and Flv4 in Synechocystis sp. PCC 6803

    PubMed Central

    Zhang, Pengpeng; Allahverdiyeva, Yagut; Eisenhut, Marion; Aro, Eva-Mari

    2009-01-01

    Background Flavodiiron proteins (FDPs) comprise a group of modular enzymes that function in oxygen and nitric oxide detoxification in Bacteria and Archaea. The FDPs in cyanobacteria have an extra domain as compared to major prokaryotic enzymes. The physiological role of cyanobacteria FDPs is mostly unknown. Of the four putative flavodiiron proteins (Flv1–4) in the cyanobacterium Synechocystis sp. PCC 6803, a physiological function in Mehler reaction has been suggested for Flv1 and Flv3. Principal Findings We demonstrate a novel and crucial function for Flv2 and Flv4 in photoprotection of photosystem II (PSII) in Synechocystis. It is shown that the expression of Flv2 and Flv4 is high under air level of CO2 and negligible at elevated CO2. Moreover, the rate of accumulation of flv2 and flv4 transcripts upon shift of cells from high to low CO2 is strongly dependent on light intensity. Characterization of FDP inactivation mutants of Synechocystis revealed a specific decline in PSII centers and impaired translation of the D1 protein in Δflv2 and Δflv4 when grown at air level CO2 whereas at high CO2 the Flvs were dispensable. Δflv2 and Δflv4 were also more susceptible to high light induced inhibition of PSII than WT or Δflv1 and Δflv3. Significance Analysis of published sequences revealed the presence of cyanobacteria-like FDPs also in some oxygenic photosynthetic eukaryotes like green algae, mosses and lycophytes. Our data provide evidence that Flv2 and Flv4 have an important role in photoprotection of water-splitting PSII against oxidative stress when the cells are acclimated to air level CO2. It is conceivable that the function of FDPs has changed during evolution from protection against oxygen in anaerobic microbes to protection against reactive oxygen species thus making the sustainable function of oxygen evolving PSII possible. Higher plants lack FDPs and distinctly different mechanisms have evolved for photoprotection of PSII. PMID:19390625

  4. A new approach for the photosynthetic antenna-reaction center complex with a model organized around an s-triazine linker.

    PubMed

    Kuhri, Susanne; Charalambidis, Georgios; Angaridis, Panagiotis A; Lazarides, Theodore; Pagona, Georgia; Tagmatarchis, Nikos; Coutsolelos, Athanassios G; Guldi, Dirk M

    2014-02-10

    Two new artificial mimics of the photosynthetic antenna-reaction center complex have been designed and synthesized (BDP-H2 P-C60 and BDP-ZnP-C60). The resulting electron-donor/acceptor conjugates contain a porphyrin (either in its free-base form (H2P) or as Zn-metalated complex (ZnP)), a boron dipyrrin (BDP), and a fulleropyrrolidine possessing, as substituent of the pyrrolidine nitrogen, an ethylene glycol chain terminating in an amino group C60-X-NH2 (X=spacer). In both cases, the three different components were connected by s-triazine through stepwise substitution reactions of cyanuric chloride. In addition to the facile synthesis, the star-type arrangement of the three photo- and redox-active components around the central s-triazine unit permits direct interaction between one another, in contrast to reported examples in which the three components are arranged in a linear fashion. The energy- and electron-transfer properties of the resulting electron-donor/acceptor conjugates were investigated by using UV/Vis absorption and emission spectroscopy, cyclic voltammetry, and femtosecond transient absorption spectroscopy. Comparison of the absorption spectra and cyclic voltammograms of BDP-H2P-C60 and BDP-ZnP-C60 with those of BDP-H2P, BDP-ZnP and BDP-C60, which were used as references, showed that the spectroscopic and electrochemical properties of the individual constituents are basically retained, although some appreciable shifts in terms of absorption indicate some interactions in the ground state. Fluorescence lifetime measurements and transient absorption experiments helped to elucidate the antenna function of BDP, which upon selective excitation undergoes a rapid and efficient energy transfer from BDP to H2P or ZnP. This is then followed by an electron transfer to C60, yielding the formation of the singlet charge-separated states, namely BDP-H2(·+) -C60(·-) and BDP-ZnP(·+)-C60(·-). As such, the sequence of energy transfer and electron transfer in the

  5. Anoxic carbon flux in photosynthetic microbial mats as revealed by metatranscriptomics

    PubMed Central

    Burow, Luke C; Woebken, Dagmar; Marshall, Ian PG; Lindquist, Erika A; Bebout, Brad M; Prufert-Bebout, Leslie; Hoehler, Tori M; Tringe, Susannah G; Pett-Ridge, Jennifer; Weber, Peter K; Spormann, Alfred M; Singer, Steven W

    2013-01-01

    Photosynthetic microbial mats possess extraordinary phylogenetic and functional diversity that makes linking specific pathways with individual microbial populations a daunting task. Close metabolic and spatial relationships between Cyanobacteria and Chloroflexi have previously been observed in diverse microbial mats. Here, we report that an expressed metabolic pathway for the anoxic catabolism of photosynthate involving Cyanobacteria and Chloroflexi in microbial mats can be reconstructed through metatranscriptomic sequencing of mats collected at Elkhorn Slough, Monterey Bay, CA, USA. In this reconstruction, Microcoleus spp., the most abundant cyanobacterial group in the mats, ferment photosynthate to organic acids, CO2 and H2 through multiple pathways, and an uncultivated lineage of the Chloroflexi take up these organic acids to store carbon as polyhydroxyalkanoates. The metabolic reconstruction is consistent with metabolite measurements and single cell microbial imaging with fluorescence in situ hybridization and NanoSIMS. PMID:23190731

  6. Anoxic carbon flux in photosynthetic microbial mats as revealed by metatranscriptomics.

    PubMed

    Burow, Luke C; Woebken, Dagmar; Marshall, Ian P G; Lindquist, Erika A; Bebout, Brad M; Prufert-Bebout, Leslie; Hoehler, Tori M; Tringe, Susannah G; Pett-Ridge, Jennifer; Weber, Peter K; Spormann, Alfred M; Singer, Steven W

    2013-04-01

    Photosynthetic microbial mats possess extraordinary phylogenetic and functional diversity that makes linking specific pathways with individual microbial populations a daunting task. Close metabolic and spatial relationships between Cyanobacteria and Chloroflexi have previously been observed in diverse microbial mats. Here, we report that an expressed metabolic pathway for the anoxic catabolism of photosynthate involving Cyanobacteria and Chloroflexi in microbial mats can be reconstructed through metatranscriptomic sequencing of mats collected at Elkhorn Slough, Monterey Bay, CA, USA. In this reconstruction, Microcoleus spp., the most abundant cyanobacterial group in the mats, ferment photosynthate to organic acids, CO2 and H2 through multiple pathways, and an uncultivated lineage of the Chloroflexi take up these organic acids to store carbon as polyhydroxyalkanoates. The metabolic reconstruction is consistent with metabolite measurements and single cell microbial imaging with fluorescence in situ hybridization and NanoSIMS. PMID:23190731

  7. Characterisation of antioxidants in photosynthetic and non-photosynthetic leaf tissues of variegated Pelargonium zonale plants.

    PubMed

    Vidović, M; Morina, F; Milić-Komić, S; Vuleta, A; Zechmann, B; Prokić, Lj; Veljović Jovanović, S

    2016-07-01

    Hydrogen peroxide is an important signalling molecule, involved in regulation of numerous metabolic processes in plants. The most important sources of H2 O2 in photosynthetically active cells are chloroplasts and peroxisomes. Here we employed variegated Pelargonium zonale to characterise and compare enzymatic and non-enzymatic components of the antioxidative system in autotrophic and heterotrophic leaf tissues at (sub)cellular level under optimal growth conditions. The results revealed that both leaf tissues had specific strategies to regulate H2 O2 levels. In photosynthetic cells, the redox regulatory system was based on ascorbate, and on the activities of thylakoid-bound ascorbate peroxidase (tAPX) and catalase. In this leaf tissue, ascorbate was predominantly localised in the nucleus, peroxisomes, plastids and mitochondria. On the other hand, non-photosynthetic cells contained higher glutathione content, mostly located in mitochondria. The enzymatic antioxidative system in non-photosynthetic cells relied on the ascorbate-glutathione cycle and both Mn and Cu/Zn superoxide dismutase. Interestingly, higher content of ascorbate and glutathione, and higher activities of APX in the cytosol of non-photosynthetic leaf cells compared to the photosynthetic ones, suggest the importance of this compartment in H2 O2 regulation. Together, these results imply different regulation of processes linked with H2 O2 signalling at subcellular level. Thus, we propose green-white variegated leaves as an excellent system for examination of redox signal transduction and redox communication between two cell types, autotrophic and heterotrophic, within the same organ. PMID:26712503

  8. Spatiotemporal variations in the abundance and composition of bulk and chromophoric dissolved organic matter in seasonally hypoxia-influenced Green Bay, Lake Michigan, USA.

    PubMed

    DeVilbiss, Stephen E; Zhou, Zhengzhen; Klump, J Val; Guo, Laodong

    2016-09-15

    Green Bay, Lake Michigan, USA, is the largest freshwater estuary in the Laurentian Great Lakes and receives disproportional terrestrial inputs as a result of a high watershed to bay surface area ratio. While seasonal hypoxia and the formation of "dead zones" in Green Bay have received increasing attention, there are no systematic studies on the dynamics of dissolved organic matter (DOM) and its linkage to the development of hypoxia. During summer 2014, bulk dissolved organic carbon (DOC) analysis, UV-vis spectroscopy, and fluorescence excitation-emission matrices (EEMs) coupled with PARAFAC analysis were used to quantify the abundance, composition and source of DOM and their spatiotemporal variations in Green Bay, Lake Michigan. Concentrations of DOC ranged from 202 to 571μM-C (average=361±73μM-C) in June and from 279 to 610μM-C (average=349±64μM-C) in August. In both months, absorption coefficient at 254nm (a254) was strongly correlated to bulk DOC and was most abundant in the Fox River, attesting a dominant terrestrial input. Non-chromophoric DOC comprised, on average, ~32% of bulk DOC in June with higher terrestrial DOM and ~47% in August with higher aquagenic DOM, indicating that autochthonous and more degraded DOM is of lower optical activity. PARAFAC modeling on EEM data resulted in four major fluorescent DOM components, including two terrestrial humic-like, one aquagenic humic-like, and one protein-like component. Variations in the abundance of DOM components further supported changes in DOM sources. Mixing behavior of DOM components also indicated that while bulk DOM behaved quasi-conservatively, significant compositional changes occurred during transport from the Fox River to the open bay.

  9. Constraints on hydrocarbon and organic acid abundances in hydrothermal fluids at the Von Damm vent field, Mid-Cayman Rise (Invited)

    NASA Astrophysics Data System (ADS)

    McDermott, J. M.; Seewald, J.; German, C. R.; Sylva, S. P.

    2013-12-01

    The generation of organic compounds in vent fluids has been of interest since the discovery of seafloor hydrothermal systems, due to implications for the sustenance of present-day microbial populations and their potential role in the origin of life on early Earth. Possible sources of organic compounds in hydrothermal systems include microbial production, thermogenic degradation of organic material, and abiotic synthesis. Abiotic organic synthesis reactions may occur during active circulation of seawater-derived fluids through the oceanic crust or within olivine-hosted fluid inclusions containing carbon-rich magmatic volatiles. H2-rich end-member fluids at the Von Damm vent field on the Mid-Cayman Rise, where fluid temperatures reach 226°C, provide an exciting opportunity to examine the extent of abiotic carbon transformations in a highly reducing system. Our results indicate multiple sources of carbon compounds in vent fluids at Von Damm. An ultramafic-influenced hydrothermal system located on the Mount Dent oceanic core complex at 2350 m depth, Von Damm vent fluids contain H2, CH4, and C2+ hydrocarbons in high abundance relative to basalt-hosted vent fields, and in similar abundance to other ultramafic-hosted systems, such as Rainbow and Lost City. The CO2 content and isotopic composition in end-member fluids are virtually identical to bottom seawater, suggesting that seawater DIC is unchanged during hydrothermal circulation of seawater-derived fluids. Accordingly, end-member CH4 that is present in slightly greater abundance than CO2 cannot be generated from reduction of aqueous CO2 during hydrothermal circulation. We postulate that CH4 and C2+ hydrocarbons that are abundantly present in Von Damm vent fluids reflect leaching of fluids from carbon- and H2-rich fluid inclusions hosted in plutonic rocks. Geochemical modeling of carbon speciation in the Von Damm fluids suggests that the relative abundances of CH4, C2+ hydrocarbons, and CO2 are consistent with

  10. How Cyanobacterial Distributions Reveal Flow and Irradiance Conditions of Photosynthetic Biofilm Formation

    NASA Technical Reports Server (NTRS)

    Prufert-Bebout, Lee

    2001-01-01

    Microbial life on Earth is enormously abundant at sediment-water interfaces. The fossil record in fact contains abundant evidence of the preservation of life on such surfaces. It is therefore critical to our interpretation of early Earth history, and potentially to history of life on other planets, to be able to recognize life forms at these interfaces. On Earth this life often occurs as organized structures of microbes and their extracellular exudates known as biofilms. When such biofilms occur in areas receiving sunlight photosynthetic biofilms are the dominant form in natural ecosystems due to selective advantage inherent in their ability to utilize solar energy. Cyanobacteria are the dominant phototrophic microbes in most modern and ancient photosynthetic biofilms, microbial mats and stromatolites. Due to their long (3.5 billion year) evolutionary history, this group has extensively diversified resulting in an enormous array of morphologies and physiological abilities. This enormous diversity and specialization results in very specific selection for a particular cyanobacterium in each available photosynthetic niche. Furthermore these organisms can alter their spatial orientation, cell morphology, pigmentation and associations with heterotrophic organisms in order to fine tune their optimization to a given micro-niche. These adaptations can be detected, and if adequate knowledge of the interaction between environmental conditions and organism response is available, the detectable organism response can be used to infer the environmental conditions causing that response. This presentation will detail two specific examples which illustrate this point. Light and water are essential to photosynthesis in cyanobacteria and these organisms have specific detectable behavioral responses to these parameters. We will present cyanobacterial responses to quantified flow and irradiance to demonstrate the interpretative power of distribution and orientation information. This

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

    PubMed

    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. PMID:20201533

  12. A new direction in effective accounting for the atmospheric CO 2 budget: Considering the combined action of carbonate dissolution, the global water cycle and photosynthetic uptake of DIC by aquatic organisms

    NASA Astrophysics Data System (ADS)

    Liu, Zaihua; Dreybrodt, Wolfgang; Wang, Haijing

    2010-05-01

    The magnitudes, variations, locations and mechanisms responsible for the global atmospheric CO 2 sink are uncertain and under continuing debate. Previous studies have focused mainly on the sinks in the oceans, and soil and vegetation on the continents. Here, we show, based on theoretical calculations and field monitoring evidence, that there is an important but previously underestimated sink for atmospheric CO 2 as DIC-dissolved inorganic carbon that results from the combined action of carbonate dissolution, the global water cycle and the photosynthetic uptake of DIC by aquatic organisms in ocean and land. The sink constitutes up to 0.8242 Pg C/a, amounting to 29.4% of the terrestrial CO 2 sink, or 10.4% of the total anthropogenic CO 2 emission. 0.244 Pg C/a are transferred to the sea via continental rivers and 0.2278 Pg C/a by meteoric precipitation over the seas. 0.119 Pg C/a is released back to the atmosphere again, and 0.2334 Pg C/a is stored in the continental aquatic ecosystem. Therefore, the net sink is estimated as 0.7052 Pg C/a. This sink may increase with an intensification of the global water cycle as a consequence of global warming, rising anthropogenic emissions of CO 2 and carbonate dust in atmosphere, and afforestation, which increases the soil pCO 2 and thus the carbonate dissolution. Fertilization with the elements N, P, C, Fe, Zn, and Si increases the organic matter storage/burial by aquatic organisms and thus decreases the CO 2 return to the atmosphere. Based on the ensemble mean projection of global warming for the year 2100 by IPCC, it is estimated that the atmospheric CO 2 sink will increase by 21%, or about 0.18 Pg C/a. However, the uncertainty in the estimation of this sink needs further exploration.

  13. Effect of petroleum products on the decomposition of soil organic matter as assessed by 13C natural abundance

    NASA Astrophysics Data System (ADS)

    Stelmach, Wioleta; Szarlip, Paweł; Trembaczowski, Andrzej; Bieganowski, Andrzej

    2016-04-01

    Petroleum products are common contaminants in soils due to human activities. They are toxic for microorganisms and threat their functions, including decomposition of soil organic matter (SOM). The direct estimation of altered SOM decomposition - based on the CO2 emission - is impossible after oil contamination, because oil decomposition also contributes to the CO2 release. We used the natural differences in the isotopic signature (δ13C) of SOM and of oil products to partition the total CO2 for both sources and to analyze the suppression of SOM decomposition. The dynamics of 13C fractionation during the mineralization of gasoline and diesel was measured during 42 days. The 13C fractionation varied between -8.8‰ and +3.6‰ within the first 10 days, and stabilized thereafter at about -5.3‰ for gasoline and +3.2‰ for diesel. These 13C fractionations and δ13C values of CO2 emitted from the soil were used for correct partitioning of the total CO2. Contamination with gasoline reduced the CO2 efflux from SOM decomposition by a factor of 25 (from 151 to 6 mg C-CO2 kg-1 soil during 42 days). The negative effect of diesel was much lower: the CO2 efflux from SOM was decreased by less than a factor of 2. The strong effect of gasoline versus diesel reflects the lower absorption of gasoline to mineral particles and the development of a thin film on water surfaces, leading to toxicity for microorganisms. We conclude that the small differences of 13C of SOM and of organic pollutants can be used to partition CO2 fluxes and analyze pollutant effects on SOM decomposition.

  14. Effect of petroleum products on the decomposition of soil organic matter as assessed by 13C natural abundance

    NASA Astrophysics Data System (ADS)

    Stelmach, Wioleta; Szarlip, Paweł; Trembaczowski, Andrzej; Bieganowski, Andrzej

    2016-04-01

    Petroleum products are common contaminants in soils due to human activities. They are toxic for microorganisms and threat their functions, including decomposition of soil organic matter (SOM). The direct estimation of altered SOM decomposition - based on the CO2 emission - is impossible after oil contamination, because oil decomposition also contributes to the CO2 release. We used the natural differences in the isotopic signature (δ13C) of SOM and of oil products to partition the total CO2 for both sources and to analyze the suppression of SOM decomposition. The dynamics of 13C fractionation during the mineralization of gasoline and diesel was measured during 42 days. The 13C fractionation varied between -8.8‰ and +3.6‰ within the first 10 days, and stabilized thereafter at about -5.3‰ for gasoline and +3.2‰ for diesel. These 13C fractionations and δ13C values of CO2 emitted from the soil were used for correct partitioning of the total CO2. Contamination with gasoline reduced the CO2 efflux from SOM decomposition by a factor of 25 (from 151 to 6 mg C-CO2 kg‑1 soil during 42 days). The negative effect of diesel was much lower: the CO2 efflux from SOM was decreased by less than a factor of 2. The strong effect of gasoline versus diesel reflects the lower absorption of gasoline to mineral particles and the development of a thin film on water surfaces, leading to toxicity for microorganisms. We conclude that the small differences of 13C of SOM and of organic pollutants can be used to partition CO2 fluxes and analyze pollutant effects on SOM decomposition.

  15. Photosynthetic proteins for technological applications.

    PubMed

    Giardi, Maria Teresa; Pace, Emanuela

    2005-05-01

    Photosynthetic proteins are a source of biological material well-suited to technological applications. They exhibit light-induced electron transfer across lipid membranes that can be exploited for the construction of photo-optical electrical devices. The structure and function of photosynthetic proteins differ across the photosynthetic evolutionary scale, allowing for their application in a range of technologies. Here we provide a general description of the basic and technical research in this sector and an overview of biochips and biosensors based on photochemical activity that have been developed for the bioassay of pollutants.

  16. Abundance and sources of hydrophilic and hydrophobic water-soluble organic carbon at an urban site in Korea in summer.

    PubMed

    Park, Seung Shik; Kim, Ja-Hyun; Jeong, Jae-Uk

    2012-01-01

    In this study, the characteristics of total water-soluble organic carbon (WSOC) and isolated WSOC fractions were examined to gain a better understanding of the pathway of organic aerosol production. 24 h PM(2.5) samples were collected during the summer (July 28-August 28, 2009) at an urban site in Korea. A glass column filled with XAD7HP resin was used to separate the filtered extracts into hydrophilic (WSOC(HPI)) and hydrophobic (WSOC(HPO)) fractions. The origins of air mass pathways arriving at the sampling site were mostly classified into three types, those originating over the East Sea of Korea that passed over the eastern inland urban and industrial regions (type I); those from the marine (western/southwestern/southern marine) and passed over the national industrial complex regions (type II); and those from northeastern China that passed through North Korea and metropolitan areas of South Korea (type III). Measurements showed an increase in the average WSOC fraction of total OC from the type II to III air mass (53 to 64%) periods. Also, higher SO(4)(2-)/SO(x) (=SO(2) + SO(4)(2-)) was observed in the type III air mass (0.70) than those in the types I (0.49) and II (0.43). According to the average values of WSOC/OC and SO(4)(2-)/SO(x), measurements suggest that the aerosols collected during the type III air mass period were more aged or photo-chemically processed than those during the types I and II air mass periods. The relationship between the SO(4)(2-)/SO(x) and WSOC/OC (R(2) = 0.64) suggests that a significant fraction of the observed WSOC at the site could be formed by an oxidation process similar to SO(4)(2-) aerosols, probably the oxidation process using OH radicals, or in-cloud processing. The photochemical production of WSOC(HPO) was also observed to significantly contribute to the total OC.

  17. Model-measurement comparison of functional group abundance in α-pinene and 1,3,5-trimethylbenzene secondary organic aerosol formation

    NASA Astrophysics Data System (ADS)

    Ruggeri, Giulia; Bernhard, Fabian A.; Henderson, Barron H.; Takahama, Satoshi

    2016-07-01

    Secondary organic aerosol (SOA) formed by α-pinene and 1,3,5-trimethylbenzene photooxidation under different NOx regimes is simulated using the Master Chemical Mechanism v3.2 (MCM) coupled with an absorptive gas-particle partitioning module. Vapor pressures for individual compounds are estimated with the SIMPOL.1 group contribution model for determining apportionment of reaction products to each phase. We apply chemoinformatic tools to harvest functional group (FG) composition from the simulations and estimate their contributions to the overall oxygen to carbon ratio. Furthermore, we compare FG abundances in simulated SOA to measurements of FGs reported in previous chamber studies using Fourier transform infrared spectroscopy. These simulations qualitatively capture the dynamics of FG composition of SOA formed from both α-pinene and 1,3,5-trimethylbenzene in low-NOx conditions, especially in the first hours after start of photooxidation. Higher discrepancies are found after several hours of simulation; the nature of these discrepancies indicates sources of uncertainty or types of reactions in the condensed or gas phase missing from current model implementation. Higher discrepancies are found in the case of α-pinene photooxidation under different NOx concentration regimes, which are reasoned through the domination by a few polyfunctional compounds that disproportionately impact the simulated FG abundance in the aerosol phase. This manuscript illustrates the usefulness of FG analysis to complement existing methods for model-measurement evaluation.

  18. Electrochemical and optical studies of model photosynthetic systems

    SciTech Connect

    Not Available

    1992-01-15

    The objective of this research is to obtain a better understanding of the relationship between the structural organization of photosynthetic pigments and their spectroscopic and electrochemical properties. Defined model systems were studied first. These included the least ordered (solutions) through the most highly ordered (Langmuir-Blodgett (LB) monolayers and self-assembled monolayers) systems containing BChl, BPheo, and UQ. Molecules other than the photosynthetic pigments and quinones were also examined, including chromophores (i.e. surface active cyanine dyes and phtahlocyanines) an redox active compounds (methyl viologen (MV) and surfactant ferrocenes), in order to develop the techniques needed to study the photosynthetic components. Because the chlorophylls are photosensitive and labile, it was easier first to develop procedures using stable species. Three different techniques were used to characterize these model systems. These included electrochemical techniques for determining the standard oxidation and reduction potentials of the photosynthetic components as well as methods for determining the heterogeneous electron transfer rate constants for BChl and BPheo at metal electrodes (Pt and Au). Resonance Raman (RR) and surface enhanced resonance Raman (SERR) spectroscopy were used to determine the spectra of the photosynthetic pigments and model compounds. SERRS was also used to study several types of photosynthetic preparations.

  19. Small organic solutes in sticky droplets from orb webs of the spider Zygiella atrica (Araneae; Araneidae): β-alaninamide is a novel and abundant component.

    PubMed

    Townley, Mark A; Pu, Qinglin; Zercher, Charles K; Neefus, Christopher D; Tillinghast, Edward K

    2012-10-01

    In northeastern North America, Zygiella atrica often build their orb webs near the ocean. We analyzed individual field-built Z. atrica webs to determine if organic low-molecular-mass solutes (LMM) in their sticky droplets showed any unusual features not previously seen in orb webs of other species living in less salty environments. While two of the three most abundant organic LMM (putrescine (butane-1,4-diamine) and GABamide (4-aminobutanamide)) are already well-known from webs of inland spiders, the third major LMM, β-alaninamide (3-aminopropanamide), a homolog of GABamide, has not been detected in sticky droplets from any other araneoid spiders (27 species). It remains to be established, however, whether or not use of β-alaninamide is related to proximity to saltwater. We observed variability in organic LMM composition in Z. atrica webs that appeared to be influenced more by an undetermined factor associated with different collecting locations and/or collection dates than by different genders or instars. Shifts in composition when adult females were transferred from the field to the laboratory were also observed. Structural similarities and inverse correlations among β-alaninamide, GABamide, and N-acetylputrescine suggest that they may form a series of LMM fulfilling essentially the same, as yet unknown, role in the webs of those species in which they occur.

  20. Small organic solutes in sticky droplets from orb webs of the spider Zygiella atrica (Araneae; Araneidae): β-alaninamide is a novel and abundant component.

    PubMed

    Townley, Mark A; Pu, Qinglin; Zercher, Charles K; Neefus, Christopher D; Tillinghast, Edward K

    2012-10-01

    In northeastern North America, Zygiella atrica often build their orb webs near the ocean. We analyzed individual field-built Z. atrica webs to determine if organic low-molecular-mass solutes (LMM) in their sticky droplets showed any unusual features not previously seen in orb webs of other species living in less salty environments. While two of the three most abundant organic LMM (putrescine (butane-1,4-diamine) and GABamide (4-aminobutanamide)) are already well-known from webs of inland spiders, the third major LMM, β-alaninamide (3-aminopropanamide), a homolog of GABamide, has not been detected in sticky droplets from any other araneoid spiders (27 species). It remains to be established, however, whether or not use of β-alaninamide is related to proximity to saltwater. We observed variability in organic LMM composition in Z. atrica webs that appeared to be influenced more by an undetermined factor associated with different collecting locations and/or collection dates than by different genders or instars. Shifts in composition when adult females were transferred from the field to the laboratory were also observed. Structural similarities and inverse correlations among β-alaninamide, GABamide, and N-acetylputrescine suggest that they may form a series of LMM fulfilling essentially the same, as yet unknown, role in the webs of those species in which they occur. PMID:23081916

  1. Energy transfer in real and artificial photosynthetic systems

    SciTech Connect

    Hindman, J.C.; Hunt, J.E.; Katz, J.J.

    1995-02-01

    Fluorescence emission from the photosynthetic organisms Tribonema aequale, Anacystis nidulau, and Chlorelia vulgais and from some chlorophyll model systems have been recorded as a function of excitation wavelength and temperature. Considerable similarity was observed in the effects of excitation wavelength and temperature on the fluorescence from intact photosynthetic organisms and the model systems. The parallelism in behavior suggest that self-assembly processes may occur in both the in vivo and in vitro systems that give rise to chlorophyll species at low temperature that may differ significantly from those present at ambient temperatures.

  2. Mineral vs. Organic Amendments: Microbial Community Structure, Activity and Abundance of Agriculturally Relevant Microbes Are Driven by Long-Term Fertilization Strategies.

    PubMed

    Francioli, Davide; Schulz, Elke; Lentendu, Guillaume; Wubet, Tesfaye; Buscot, François; Reitz, Thomas

    2016-01-01

    Soil management is fundamental to all agricultural systems and fertilization practices have contributed substantially to the impressive increases in food production. Despite the pivotal role of soil microorganisms in agro-ecosystems, we still have a limited understanding of the complex response of the soil microbiota to organic and mineral fertilization in the very long-term. Here, we report the effects of different fertilization regimes (mineral, organic and combined mineral and organic fertilization), carried out for more than a century, on the structure and activity of the soil microbiome. Organic matter content, nutrient concentrations, and microbial biomass carbon were significantly increased by mineral, and even more strongly by organic fertilization. Pyrosequencing revealed significant differences between the structures of bacterial and fungal soil communities associated to each fertilization regime. Organic fertilization increased bacterial diversity, and stimulated microbial groups (Firmicutes, Proteobacteria, and Zygomycota) that are known to prefer nutrient-rich environments, and that are involved in the degradation of complex organic compounds. In contrast, soils not receiving manure harbored distinct microbial communities enriched in oligotrophic organisms adapted to nutrient-limited environments, as Acidobacteria. The fertilization regime also affected the relative abundances of plant beneficial and detrimental microbial taxa, which may influence productivity and stability of the agroecosystem. As expected, the activity of microbial exoenzymes involved in carbon, nitrogen, and phosphorous mineralization were enhanced by both types of fertilization. However, in contrast to comparable studies, the highest chitinase and phosphatase activities were observed in the solely mineral fertilized soil. Interestingly, these two enzymes showed also a particular high biomass-specific activities and a strong negative relation with soil pH. As many soil parameters

  3. Mineral vs. Organic Amendments: Microbial Community Structure, Activity and Abundance of Agriculturally Relevant Microbes Are Driven by Long-Term Fertilization Strategies

    PubMed Central

    Francioli, Davide; Schulz, Elke; Lentendu, Guillaume; Wubet, Tesfaye; Buscot, François; Reitz, Thomas

    2016-01-01

    Soil management is fundamental to all agricultural systems and fertilization practices have contributed substantially to the impressive increases in food production. Despite the pivotal role of soil microorganisms in agro-ecosystems, we still have a limited understanding of the complex response of the soil microbiota to organic and mineral fertilization in the very long-term. Here, we report the effects of different fertilization regimes (mineral, organic and combined mineral and organic fertilization), carried out for more than a century, on the structure and activity of the soil microbiome. Organic matter content, nutrient concentrations, and microbial biomass carbon were significantly increased by mineral, and even more strongly by organic fertilization. Pyrosequencing revealed significant differences between the structures of bacterial and fungal soil communities associated to each fertilization regime. Organic fertilization increased bacterial diversity, and stimulated microbial groups (Firmicutes, Proteobacteria, and Zygomycota) that are known to prefer nutrient-rich environments, and that are involved in the degradation of complex organic compounds. In contrast, soils not receiving manure harbored distinct microbial communities enriched in oligotrophic organisms adapted to nutrient-limited environments, as Acidobacteria. The fertilization regime also affected the relative abundances of plant beneficial and detrimental microbial taxa, which may influence productivity and stability of the agroecosystem. As expected, the activity of microbial exoenzymes involved in carbon, nitrogen, and phosphorous mineralization were enhanced by both types of fertilization. However, in contrast to comparable studies, the highest chitinase and phosphatase activities were observed in the solely mineral fertilized soil. Interestingly, these two enzymes showed also a particular high biomass-specific activities and a strong negative relation with soil pH. As many soil parameters

  4. Mineral vs. Organic Amendments: Microbial Community Structure, Activity and Abundance of Agriculturally Relevant Microbes Are Driven by Long-Term Fertilization Strategies.

    PubMed

    Francioli, Davide; Schulz, Elke; Lentendu, Guillaume; Wubet, Tesfaye; Buscot, François; Reitz, Thomas

    2016-01-01

    Soil management is fundamental to all agricultural systems and fertilization practices have contributed substantially to the impressive increases in food production. Despite the pivotal role of soil microorganisms in agro-ecosystems, we still have a limited understanding of the complex response of the soil microbiota to organic and mineral fertilization in the very long-term. Here, we report the effects of different fertilization regimes (mineral, organic and combined mineral and organic fertilization), carried out for more than a century, on the structure and activity of the soil microbiome. Organic matter content, nutrient concentrations, and microbial biomass carbon were significantly increased by mineral, and even more strongly by organic fertilization. Pyrosequencing revealed significant differences between the structures of bacterial and fungal soil communities associated to each fertilization regime. Organic fertilization increased bacterial diversity, and stimulated microbial groups (Firmicutes, Proteobacteria, and Zygomycota) that are known to prefer nutrient-rich environments, and that are involved in the degradation of complex organic compounds. In contrast, soils not receiving manure harbored distinct microbial communities enriched in oligotrophic organisms adapted to nutrient-limited environments, as Acidobacteria. The fertilization regime also affected the relative abundances of plant beneficial and detrimental microbial taxa, which may influence productivity and stability of the agroecosystem. As expected, the activity of microbial exoenzymes involved in carbon, nitrogen, and phosphorous mineralization were enhanced by both types of fertilization. However, in contrast to comparable studies, the highest chitinase and phosphatase activities were observed in the solely mineral fertilized soil. Interestingly, these two enzymes showed also a particular high biomass-specific activities and a strong negative relation with soil pH. As many soil parameters

  5. Mineral vs. Organic Amendments: Microbial Community Structure, Activity and Abundance of Agriculturally Relevant Microbes Are Driven by Long-Term Fertilization Strategies

    PubMed Central

    Francioli, Davide; Schulz, Elke; Lentendu, Guillaume; Wubet, Tesfaye; Buscot, François; Reitz, Thomas

    2016-01-01

    Soil management is fundamental to all agricultural systems and fertilization practices have contributed substantially to the impressive increases in food production. Despite the pivotal role of soil microorganisms in agro-ecosystems, we still have a limited understanding of the complex response of the soil microbiota to organic and mineral fertilization in the very long-term. Here, we report the effects of different fertilization regimes (mineral, organic and combined mineral and organic fertilization), carried out for more than a century, on the structure and activity of the soil microbiome. Organic matter content, nutrient concentrations, and microbial biomass carbon were significantly increased by mineral, and even more strongly by organic fertilization. Pyrosequencing revealed significant differences between the structures of bacterial and fungal soil communities associated to each fertilization regime. Organic fertilization increased bacterial diversity, and stimulated microbial groups (Firmicutes, Proteobacteria, and Zygomycota) that are known to prefer nutrient-rich environments, and that are involved in the degradation of complex organic compounds. In contrast, soils not receiving manure harbored distinct microbial communities enriched in oligotrophic organisms adapted to nutrient-limited environments, as Acidobacteria. The fertilization regime also affected the relative abundances of plant beneficial and detrimental microbial taxa, which may influence productivity and stability of the agroecosystem. As expected, the activity of microbial exoenzymes involved in carbon, nitrogen, and phosphorous mineralization were enhanced by both types of fertilization. However, in contrast to comparable studies, the highest chitinase and phosphatase activities were observed in the solely mineral fertilized soil. Interestingly, these two enzymes showed also a particular high biomass-specific activities and a strong negative relation with soil pH. As many soil parameters

  6. Influence of pregnancy in mid-to-late gestation on circulating metabolites, visceral organ mass, and abundance of proteins relating to energy metabolism in mature beef cows.

    PubMed

    Wood, K M; Awda, B J; Fitzsimmons, C; Miller, S P; McBride, B W; Swanson, K C

    2013-12-01

    In mid-to-late gestation, nutrient demand increases to meet the growth requirements of the conceptus and cows may alter metabolism in response to energy demands of pregnancy. By better understanding the metabolic role of pregnancy, there may be opportunities to better understand maintenance energy costs and improve overall feed efficiency. Eighteen mature Simmental/Angus crossbred cows, pregnant (PREG; n = 9) and nonpregnant (OPEN; n = 9), were used to investigate the effect of pregnancy on BW change, carcass traits, visceral organ mass, and circulating serum metabolites. Cows were blocked by day of expected parturition such that each block was slaughtered 4 to 5 wk before parturition. Cows were individually fed for ad libitum intake using Calan gates for 89 to 105 d. Cows were weighed, ultrasounded for rib (over the 12th and 13th rib) and rump fat, and a serum sample obtained at d 1, 56, and 3 to 5 d before slaughter. At slaughter, organs were removed, trimmed of fat, and weighed. Serum was analyzed for β-hydroxybutyrate (BHBA), NEFA, glucose, urea, total cholesterol, and triiodothyronine (T3). Tissue samples from liver, kidney, sternomandibularis muscle, ruminal papillae, pancreas, and small intestinal mucosa were collected at slaughter and snap frozen in liquid N. Western blots were conducted to quantify abundance of: proliferating cell nuclear antigen (PCNA), ATP synthase, ubiquitin, and Na(+)/K+ ATPase for all tissues; PPARγ, PPARγ coactivator 1α (PGC1-α), 5'-adenosine monophosphate-activated protein kinase (AMPK) and phosphorylated-AMPK (pAMPK) for liver, muscle, and rumen; phosphoenolpyruvate carboxykinase (PEPCK) for liver and kidney; and uncoupling protein 2 (UCP2) for liver. Data were analyzed using PROC MIXED in SAS as a replicated randomized complete block. Liver weights (actual, relative to BW, relative to HCW) were heavier (P ≤ 0.02) in OPEN. Rumen mass and kidney fat weight, both relative to BW, were also greater (P ≤ 0.04) in OPEN. On d 56

  7. Redox regulation of photosynthetic gene expression

    PubMed Central

    Queval, Guillaume; Foyer, Christine H.

    2012-01-01

    Redox chemistry and redox regulation are central to the operation of photosynthesis and respiration. However, the roles of different oxidants and antioxidants in the regulation of photosynthetic or respiratory gene expression remain poorly understood. Leaf transcriptome profiles of a range of Arabidopsis thaliana genotypes that are deficient in either hydrogen peroxide processing enzymes or in low molecular weight antioxidant were therefore compared to determine how different antioxidant systems that process hydrogen peroxide influence transcripts encoding proteins targeted to the chloroplasts or mitochondria. Less than 10 per cent overlap was observed in the transcriptome patterns of leaves that are deficient in either photorespiratory (catalase (cat)2) or chloroplastic (thylakoid ascorbate peroxidase (tapx)) hydrogen peroxide processing. Transcripts encoding photosystem II (PSII) repair cycle components were lower in glutathione-deficient leaves, as were the thylakoid NAD(P)H (nicotinamide adenine dinucleotide (phosphate)) dehydrogenases (NDH) mRNAs. Some thylakoid NDH mRNAs were also less abundant in tAPX-deficient and ascorbate-deficient leaves. Transcripts encoding the external and internal respiratory NDHs were increased by low glutathione and low ascorbate. Regulation of transcripts encoding specific components of the photosynthetic and respiratory electron transport chains by hydrogen peroxide, ascorbate and glutathione may serve to balance non-cyclic and cyclic electron flow pathways in relation to oxidant production and reductant availability. PMID:23148274

  8. Clinorotation affects mesophyll photosynthetic cells in leaves of pea seedlings.

    PubMed

    Adamchuk, N I

    1998-07-01

    Experiments with autotrophs in altered gravity condition have a grate significant for development of space biology. The main results of investigation in the photosynthetic apparatus state under microgravity condition have based on the experiments with maturity plants and their differentiated cells. The structural and functional organization of photosynthetic cells in seedlings is poor understandable still. Along with chloroplasts preserving a native membrane system in palisade parenchyma cells of the 29-day pea plant leaves in microgravity, chloroplasts with fribly packed or damaged granae, whose thylakoids appeared as vesicles with an electrontransparent content, were also observed. The investigation of preceding process induced these effects have a sense. That is why, the goal of our experiments was to perform the study of a structural organization of the photosynthetic cells of 3-d pair of pea seedlings leaves under the influence of clinorotation.

  9. Counting Viruses and Bacteria in Photosynthetic Microbial Mats

    PubMed Central

    Staal, Marc; Middelboe, Mathias; Brussaard, Corina P. D.

    2015-01-01

    Viral abundances in benthic environments are the highest found in aquatic systems. Photosynthetic microbial mats represent benthic environments with high microbial activity and possibly high viral densities, yet viral abundances have not been examined in such systems. Existing extraction procedures typically used in benthic viral ecology were applied to the complex matrix of microbial mats but were found to inefficiently extract viruses. Here, we present a method for extraction and quantification of viruses from photosynthetic microbial mats using epifluorescence microscopy (EFM) and flow cytometry (FCM). A combination of EDTA addition, probe sonication, and enzyme treatment applied to a glutaraldehyde-fixed sample resulted in a substantially higher viral (5- to 33-fold) extraction efficiency and reduced background noise compared to previously published methods. Using this method, it was found that in general, intertidal photosynthetic microbial mats harbor very high viral abundances (2.8 × 1010 ± 0.3 × 1010 g−1) compared with benthic habitats (107 to 109 g−1). This procedure also showed 4.5- and 4-fold-increased efficacies of extraction of viruses and bacteria, respectively, from intertidal sediments, allowing a single method to be used for the microbial mat and underlying sediment. PMID:25595761

  10. Diurnal variations in pathways of photosynthetic carbon fixation in a freshwater cyanobacterium

    NASA Astrophysics Data System (ADS)

    Labiosa, R. G.; Arrigo, K. R.; Grossman, A.; Reddy, T. E.; Shrager, J.

    2003-04-01

    . Some increase more rapidly following daybreak than others and decrease at different rates after night fall. Early results from microarrays containing the full genome of the organism show that almost all genes display higher transcript abundances during the day (including photosynthetic genes), with a few notable exceptions, and a few others display higher transcript abundance at night than during the day.

  11. Natural strategies for photosynthetic light harvesting.

    PubMed

    Croce, Roberta; van Amerongen, Herbert

    2014-07-01

    Photosynthetic organisms are crucial for life on Earth as they provide food and oxygen and are at the basis of most energy resources. They have a large variety of light-harvesting strategies that allow them to live nearly everywhere where sunlight can penetrate. They have adapted their pigmentation to the spectral composition of light in their habitat, they acclimate to slowly varying light intensities and they rapidly respond to fast changes in light quality and quantity. This is particularly important for oxygen-producing organisms because an overdose of light in combination with oxygen can be lethal. Rapid progress is being made in understanding how different organisms maximize light harvesting and minimize deleterious effects. Here we summarize the latest findings and explain the main design principles used in nature. The available knowledge can be used for optimizing light harvesting in both natural and artificial photosynthesis to improve light-driven production processes.

  12. Stable carbon isotope ratios of rock varnish organic matter: a new paleoenvironmental indicator.

    PubMed

    Dorn, R I; Deniro, M J

    1985-03-22

    Stable carbon isotope ratios of organic matter in rock varnishes of Holocene age from western North America and the Middle East show a strong association with the environment. This isotopic variability reflects the abundance of plants with different photosynthetic pathways in adjacent vegetation. Analyses of different layers of varnish on late Pleistocene desert landforms indicate that the carbon isotopic composition of varnish organic matter is a paleoenvironmental indicator. PMID:17777781

  13. Stable carbon isotope ratios of rock varnish organic matter: a new paleoenvironmental indicator.

    PubMed

    Dorn, R I; Deniro, M J

    1985-03-22

    Stable carbon isotope ratios of organic matter in rock varnishes of Holocene age from western North America and the Middle East show a strong association with the environment. This isotopic variability reflects the abundance of plants with different photosynthetic pathways in adjacent vegetation. Analyses of different layers of varnish on late Pleistocene desert landforms indicate that the carbon isotopic composition of varnish organic matter is a paleoenvironmental indicator.

  14. Abundance of Soil-Borne Entomopathogenic Fungi in Organic and Conventional Fields in the Midwestern USA with an Emphasis on the Effect of Herbicides and Fungicides on Fungal Persistence.

    PubMed

    Clifton, Eric H; Jaronski, Stefan T; Hodgson, Erin W; Gassmann, Aaron J

    2015-01-01

    Entomopathogenic fungi (EPF) are widespread in agricultural fields and help suppress crop pests. These natural enemies may be hindered by certain agronomic practices associated with conventional agriculture including the use of pesticides. We tested whether the abundance of EPF differed between organic and conventional fields, and whether specific cropping practices and soil properties were correlated with their abundance. In one year of the survey, soil from organic fields and accompanying margins had significantly more EPF than conventional fields and accompanying margins. Regression analysis revealed that the percentage of silt and the application of organic fertilizer were positively correlated with EPF abundance; but nitrogen concentration, tillage, conventional fields, and margins of conventional fields were negatively correlated with EPF abundance. A greenhouse experiment in which fungicides and herbicides were applied to the soil surface showed no significant effect on EPF. Though organic fields were perceived to be more suitable environments for EPF, abiotic factors and cropping practices such as tillage may have greater impacts on the abundance of EPF. Also, fungicides and herbicides may not be as toxic to soil-borne EPF as originally thought. PMID:26191815

  15. Abundance of Soil-Borne Entomopathogenic Fungi in Organic and Conventional Fields in the Midwestern USA with an Emphasis on the Effect of Herbicides and Fungicides on Fungal Persistence.

    PubMed

    Clifton, Eric H; Jaronski, Stefan T; Hodgson, Erin W; Gassmann, Aaron J

    2015-01-01

    Entomopathogenic fungi (EPF) are widespread in agricultural fields and help suppress crop pests. These natural enemies may be hindered by certain agronomic practices associated with conventional agriculture including the use of pesticides. We tested whether the abundance of EPF differed between organic and conventional fields, and whether specific cropping practices and soil properties were correlated with their abundance. In one year of the survey, soil from organic fields and accompanying margins had significantly more EPF than conventional fields and accompanying margins. Regression analysis revealed that the percentage of silt and the application of organic fertilizer were positively correlated with EPF abundance; but nitrogen concentration, tillage, conventional fields, and margins of conventional fields were negatively correlated with EPF abundance. A greenhouse experiment in which fungicides and herbicides were applied to the soil surface showed no significant effect on EPF. Though organic fields were perceived to be more suitable environments for EPF, abiotic factors and cropping practices such as tillage may have greater impacts on the abundance of EPF. Also, fungicides and herbicides may not be as toxic to soil-borne EPF as originally thought.

  16. Abundance of Soil-Borne Entomopathogenic Fungi in Organic and Conventional Fields in the Midwestern USA with an Emphasis on the Effect of Herbicides and Fungicides on Fungal Persistence

    PubMed Central

    Clifton, Eric H.; Jaronski, Stefan T.; Hodgson, Erin W.; Gassmann, Aaron J.

    2015-01-01

    Entomopathogenic fungi (EPF) are widespread in agricultural fields and help suppress crop pests. These natural enemies may be hindered by certain agronomic practices associated with conventional agriculture including the use of pesticides. We tested whether the abundance of EPF differed between organic and conventional fields, and whether specific cropping practices and soil properties were correlated with their abundance. In one year of the survey, soil from organic fields and accompanying margins had significantly more EPF than conventional fields and accompanying margins. Regression analysis revealed that the percentage of silt and the application of organic fertilizer were positively correlated with EPF abundance; but nitrogen concentration, tillage, conventional fields, and margins of conventional fields were negatively correlated with EPF abundance. A greenhouse experiment in which fungicides and herbicides were applied to the soil surface showed no significant effect on EPF. Though organic fields were perceived to be more suitable environments for EPF, abiotic factors and cropping practices such as tillage may have greater impacts on the abundance of EPF. Also, fungicides and herbicides may not be as toxic to soil-borne EPF as originally thought. PMID:26191815

  17. Non-photosynthetic pigments as potential biosignatures

    NASA Astrophysics Data System (ADS)

    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.

  18. Abundance of volatile and organic species in intermediate temperature fluids from the Von Damm and Piccard deep sea hydrothermal fields, Mid-Cayman Rise

    NASA Astrophysics Data System (ADS)

    McDermott, J. M.; Seewald, J.; Reeves, E. P.; German, C. R.; Sylva, S. P.; Klein, F.

    2012-12-01

    vent fluids, and imply the presence of a CO2 sink. Von Damm fluid CO2/CH4 ratios are relatively constant at 1.0 to 1.5 (mol/mol) in the higher temperature fluids, and are low compared with CO2/CH4 ratios of 200 to 250 (mol/mol) in the higher temperature Piccard fluids. All vent fluids at Von Damm are enriched in CH4 and longer-chain n-alkanes. Von Damm fluid H2 and H2S abundances are consistent with those at Rainbow and other ultramafic-influenced systems. At the Von Damm vent field, H2 shows non-conservative behavior in intermediate fluids at temperatures ≤114 °C. Such behavior is consistent with previous studies, which attributed non-conservative H2 behavior in ~30 °C vent fluids to microbial consumption (e.g. Von Damm and Lilley, 2004). Similar activity may be occurring at Von Damm. At Piccard, H2 shows non-conservative mixing behavior at temperatures ≤149 °C. H2 depletion at Piccard occurs at higher temperatures than at Von Damm, in excess of the currently known limit for life at 122 °C (Takei et al., 2008), suggesting that abiotic as well as microbial processes may be affecting H2 abundance. Methylated organic compounds, including methanethiol and methanol, were also observed in vent fluids at Piccard and Von Damm, and further organic compound analyses are ongoing.

  19. Characterizing the Spatial and Temporal Variations in Organic Carbon Abundance and Stable Isotope Ratios in Lake Sediments Containing Evidence of Prehistoric Agriculture

    NASA Astrophysics Data System (ADS)

    Taylor, Z. P.; Finkelstein, D. B.; Horn, S. P.

    2009-12-01

    Intra-basin spatial variability in lake sediments has the potential to limit the utility of interpretations based on the analysis of a single sediment core. We analyzed a network of five sediment cores to assess geochemical and isotopic spatial variability across a lake in southern Costa Rica. Laguna Zoncho (8.813°N, 82.963°W) provides an excellent opportunity to detect spatial variability because it is a small lake (0.75 ha) with a known history of prehistoric maize agriculture in its watershed. During the agricultural period (1770-570 cal BP) at Zoncho, stable carbon isotope values in the five cores average -23 ‰ V-PDB; these values increase to -27 ‰ V-PDB during the subsequent period of forest recovery. In prior work at the lake, this forest recovery was assumed to have been initiated by the Spanish Conquest about AD 1500, but our new findings suggest it may have occurred earlier and have been driven by a different set of circumstances. We attribute the more positive values during the agricultural period to a greater abundance of C4 vegetation in the watershed as the result of agricultural activity that removed native C3 forest vegetation and created fields and disturbed environments that favor C4 plants. Organic carbon contents during the agricultural period average 5 % and increase to an average of 16 % post-Conquest. Molar C/N ratios range from 13 during the agricultural period to 16 after the cessation of agriculture in the watershed. The cores may indicate a non-simultaneous end to agriculture in the watershed. Stable carbon isotope values and organic carbon contents in three of the four cores collected closer to shore contain evidence of an abrupt end of agriculture around 1000 cal. BP. In these cores, stable carbon isotope values indicate a dramatic shift from C4 to C3 inputs and a rapid increase in organic contents. The fourth core shows this shift around 700 cal. BP. The core recovered from the center of the lake records a gradual end to

  20. Short interspersed nuclear elements (SINEs) are abundant in Solanaceae and have a family-specific impact on gene structure and genome organization.

    PubMed

    Seibt, Kathrin M; Wenke, Torsten; Muders, Katja; Truberg, Bernd; Schmidt, Thomas

    2016-05-01

    Short interspersed nuclear elements (SINEs) are highly abundant non-autonomous retrotransposons that are widespread in plants. They are short in size, non-coding, show high sequence diversity, and are therefore mostly not or not correctly annotated in plant genome sequences. Hence, comparative studies on genomic SINE populations are rare. To explore the structural organization and impact of SINEs, we comparatively investigated the genome sequences of the Solanaceae species potato (Solanum tuberosum), tomato (Solanum lycopersicum), wild tomato (Solanum pennellii), and two pepper cultivars (Capsicum annuum). Based on 8.5 Gbp sequence data, we annotated 82 983 SINE copies belonging to 10 families and subfamilies on a base pair level. Solanaceae SINEs are dispersed over all chromosomes with enrichments in distal regions. Depending on the genome assemblies and gene predictions, 30% of all SINE copies are associated with genes, particularly frequent in introns and untranslated regions (UTRs). The close association with genes is family specific. More than 10% of all genes annotated in the Solanaceae species investigated contain at least one SINE insertion, and we found genes harbouring up to 16 SINE copies. We demonstrate the involvement of SINEs in gene and genome evolution including the donation of splice sites, start and stop codons and exons to genes, enlargement of introns and UTRs, generation of tandem-like duplications and transduction of adjacent sequence regions.

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

    PubMed

    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. PMID:25536030

  2. Cyanobacteria as photosynthetic biocatalysts: a systems biology perspective.

    PubMed

    Gudmundsson, Steinn; Nogales, Juan

    2015-01-01

    The increasing need to replace oil-based products and to address global climate change concerns has triggered considerable interest in photosynthetic microorganisms. Cyanobacteria, in particular, have great potential as biocatalysts for fuels and fine-chemicals. During the last few years the biotechnological applications of cyanobacteria have experienced an unprecedented increase and the use of these photosynthetic organisms for chemical production is becoming a tangible reality. However, the field is still immature and many concerns about the economic feasibility of the biotechnological potential of cyanobacteria remain. In this review we describe recent successes in biofuel and fine-chemical production using cyanobacteria. We discuss the role of the photosynthetic metabolism and highlight the need for systems-level metabolic optimization in order to achieve the true potential of cyanobacterial biocatalysts.

  3. Superradiance Transition and Nonphotochemical Quenching in Photosynthetic Complexes

    SciTech Connect

    Berman, Gennady Petrovich; Nesterov, Alexander; Lopez, Gustavo; Sayre, Richard Thomas

    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.

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

    PubMed

    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.

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

    PubMed

    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. PMID:27262189

  6. Functional Implications of Photosystem II Crystal Formation in Photosynthetic Membranes.

    PubMed

    Tietz, Stefanie; Puthiyaveetil, Sujith; Enlow, Heather M; Yarbrough, Robert; Wood, Magnus; Semchonok, Dmitry A; Lowry, Troy; Li, Zhirong; Jahns, Peter; Boekema, Egbert J; Lenhert, Steven; Niyogi, Krishna K; Kirchhoff, Helmut

    2015-05-29

    The structural organization of proteins in biological membranes can affect their function. Photosynthetic thylakoid membranes in chloroplasts have the remarkable ability to change their supramolecular organization between disordered and semicrystalline states. Although the change to the semicrystalline state is known to be triggered by abiotic factors, the functional significance of this protein organization has not yet been understood. Taking advantage of an Arabidopsis thaliana fatty acid desaturase mutant (fad5) that constitutively forms semicrystalline arrays, we systematically test the functional implications of protein crystals in photosynthetic membranes. Here, we show that the change into an ordered state facilitates molecular diffusion of photosynthetic components in crowded thylakoid membranes. The increased mobility of small lipophilic molecules like plastoquinone and xanthophylls has implications for diffusion-dependent electron transport and photoprotective energy-dependent quenching. The mobility of the large photosystem II supercomplexes, however, is impaired, leading to retarded repair of damaged proteins. Our results demonstrate that supramolecular changes into more ordered states have differing impacts on photosynthesis that favor either diffusion-dependent electron transport and photoprotection or protein repair processes, thus fine-tuning the photosynthetic energy conversion.

  7. Functional Implications of Photosystem II Crystal Formation in Photosynthetic Membranes*

    PubMed Central

    Tietz, Stefanie; Puthiyaveetil, Sujith; Enlow, Heather M.; Yarbrough, Robert; Wood, Magnus; Semchonok, Dmitry A.; Lowry, Troy; Li, Zhirong; Jahns, Peter; Boekema, Egbert J.; Lenhert, Steven; Niyogi, Krishna K.; Kirchhoff, Helmut

    2015-01-01

    The structural organization of proteins in biological membranes can affect their function. Photosynthetic thylakoid membranes in chloroplasts have the remarkable ability to change their supramolecular organization between disordered and semicrystalline states. Although the change to the semicrystalline state is known to be triggered by abiotic factors, the functional significance of this protein organization has not yet been understood. Taking advantage of an Arabidopsis thaliana fatty acid desaturase mutant (fad5) that constitutively forms semicrystalline arrays, we systematically test the functional implications of protein crystals in photosynthetic membranes. Here, we show that the change into an ordered state facilitates molecular diffusion of photosynthetic components in crowded thylakoid membranes. The increased mobility of small lipophilic molecules like plastoquinone and xanthophylls has implications for diffusion-dependent electron transport and photoprotective energy-dependent quenching. The mobility of the large photosystem II supercomplexes, however, is impaired, leading to retarded repair of damaged proteins. Our results demonstrate that supramolecular changes into more ordered states have differing impacts on photosynthesis that favor either diffusion-dependent electron transport and photoprotection or protein repair processes, thus fine-tuning the photosynthetic energy conversion. PMID:25897076

  8. Regulatory RNAs in photosynthetic cyanobacteria.

    PubMed

    Kopf, Matthias; Hess, Wolfgang R

    2015-05-01

    Regulatory RNAs play versatile roles in bacteria in the coordination of gene expression during various physiological processes, especially during stress adaptation. Photosynthetic bacteria use sunlight as their major energy source. Therefore, they are particularly vulnerable to the damaging effects of excess light or UV irradiation. In addition, like all bacteria, photosynthetic bacteria must adapt to limiting nutrient concentrations and abiotic and biotic stress factors. Transcriptome analyses have identified hundreds of potential regulatory small RNAs (sRNAs) in model cyanobacteria such as Synechocystis sp. PCC 6803 or Anabaena sp. PCC 7120, and in environmentally relevant genera such as Trichodesmium, Synechococcus and Prochlorococcus. Some sRNAs have been shown to actually contain μORFs and encode short proteins. Examples include the 40-amino-acid product of the sml0013 gene, which encodes the NdhP subunit of the NDH1 complex. In contrast, the functional characterization of the non-coding sRNA PsrR1 revealed that the 131 nt long sRNA controls photosynthetic functions by targeting multiple mRNAs, providing a paradigm for sRNA functions in photosynthetic bacteria. We suggest that actuatons comprise a new class of genetic elements in which an sRNA gene is inserted upstream of a coding region to modify or enable transcription of that region.

  9. Photosynthetic carbon reduction by seagrasses exposed to ultraviolet A radiation

    NASA Technical Reports Server (NTRS)

    1979-01-01

    The seagrasses Halophila engelmannii, Halodule wrightii, and Syringodium filiforme were examined for their intrinsic sensitivity to ultraviolet-A-UV-A and ultraviolet-B-UV-B radiation. The effect of UV-A on photosynthetically active radiation (PAR) was also determined. Ultraviolet-A and ultraviolet-B were studied with emphasis on the greater respective environmental consequence in terms of seagrass distribution and abundance. Results indicate that an intrinsic sensitivity to UV-A alone is apparent only in Halophila, while net photosynthesis in Halodule and Syringodium seems unaffected by the level of UV-A provided. The sensitivity of Halophila to UV-A in the absense of (PAR) indicates that the photosynthetic reaction does not need to be in operation for damage to occur. Other significant results are reported.

  10. The making of a photosynthetic animal

    PubMed Central

    Rumpho, Mary E.; Pelletreau, Karen N.; Moustafa, Ahmed; Bhattacharya, Debashish

    2011-01-01

    Symbiotic animals containing green photobionts challenge the common perception that only plants are capable of capturing the sun's rays and converting them into biological energy through photoautotrophic CO2 fixation (photosynthesis). ‘Solar-powered’ sacoglossan molluscs, or sea slugs, have taken this type of symbiotic association one step further by solely harboring the photosynthetic organelle, the plastid (=chloroplast). One such sea slug, Elysia chlorotica, lives as a ‘plant’ when provided with only light and air as a result of acquiring plastids during feeding on its algal prey Vaucheria litorea. The captured plastids (kleptoplasts) are retained intracellularly in cells lining the digestive diverticula of the sea slug, a phenomenon sometimes referred to as kleptoplasty. Photosynthesis by the plastids provides E. chlorotica with energy and fixed carbon for its entire lifespan of ∼10 months. The plastids are not transmitted vertically (i.e. are absent in eggs) and do not undergo division in the sea slug. However, de novo protein synthesis continues, including plastid- and nuclear-encoded plastid-targeted proteins, despite the apparent absence of algal nuclei. Here we discuss current data and provide hypotheses to explain how long-term photosynthetic activity is maintained by the kleptoplasts. This fascinating ‘green animal’ provides a unique model to study the evolution of photosynthesis in a multicellular heterotrophic organism. PMID:21177950

  11. Micromachined microbial and photosynthetic fuel cells

    NASA Astrophysics Data System (ADS)

    Chiao, Mu; Lam, Kien B.; Lin, Liwei

    2006-12-01

    This paper presents two types of fuel cells: a miniature microbial fuel cell (µMFC) and a miniature photosynthetic electrochemical cell (µPEC). A bulk micromachining process is used to fabricate the fuel cells, and the prototype has an active proton exchange membrane area of 1 cm2. Two different micro-organisms are used as biocatalysts in the anode: (1) Saccharomyces cerevisiae (baker's yeast) is used to catalyze glucose and (2) Phylum Cyanophyta (blue-green algae) is used to produce electrons by a photosynthetic reaction under light. In the dark, the µPEC continues to generate power using the glucose produced under light. In the cathode, potassium ferricyanide is used to accept electrons and electric power is produced by the overall redox reactions. The bio-electrical responses of µMFCs and µPECs are characterized with the open-circuit potential measured at an average value of 300-500 mV. Under a 10 ohm load, the power density is measured as 2.3 nW cm-2 and 0.04 nW cm-2 for µMFCs and µPECs, respectively.

  12. Abundance of volatile organic compounds in white ash phloem and emerald ash borer larval frass does not attract Tetrastichus planipennisi in a Y-tube olfactometer.

    PubMed

    Chen, Yigen; Ulyshen, Michael D; Poland, Therese M

    2016-10-01

    Many natural enemies employ plant- and/or herbivore-derived signals for host/prey location. The larval parasitoid Tetrastichus planipennisi Yang (Hymenoptera: Eulophidae) is 1 of 3 biocontrol agents currently being released in an effort to control the emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coloeptera: Burprestidae) in North America. To enhance its efficiency, allelochemicals that attract it need to be assessed. In this study, ash phloem volatile organic compounds (VOCs) of black, green, and white ash, and EAB larval frass were compared. Foraging behavior of T. planipennisi females in response to VOCs of white ash or frass from EAB larvae feeding on white ash phloem was tested using a Y-tube olfactometer. Results indicated that the 3 ash species had similar VOC profiles. EAB larval frass generally contained greater levels of VOCs than phloem. Factor analysis indicated that the 11 VOCs could be broadly divided into 2 groups, with α-bisabolol, β-caryophyllene, (E)-2-hexenal, (Z)-3-hexenal, limonene, methyl benzoate, methyl indole-3-acetic acid, methyl jasmonate, methyl salicylate as the first group and the rest (i.e., methyl linoleate and methyl linolenate) as a second. Abundance of VOCs in white ash phloem tissue and frass, nevertheless, did not attract T. planipennisi females. The concealed feeding of EAB larvae might explain the selection for detectable and reliable virbrational signals, instead of undetectable and relatively unreliable VOC cues from phloem and frass, in short-range foraging by T. planipennisi. Alternatively, it is possible that T. planipennisi is not amenable to the Y-tube olfactometer assay employed. PMID:25879864

  13. The effects of the 2010 flood on the composition and abundance of the terrestrial organic matter in sediments along the inner-shelf off the Changjiang Estuary, China

    NASA Astrophysics Data System (ADS)

    Li, X.; Bianchi, T. S.; Allison, M. A.; Chapman, P.; Yang, G.

    2011-12-01

    Surface sediments were collected within the primary depositional pathway along the inner-shelf off the Changjiang Estuary in winter 2009 and fall 2010 - before and after the 2010 flood in the Changjiang River. Multiple proxies (stable isotopes, lignin-phenols, pigments, cutins) were analyzed to examine the influence of this flooding event on the composition and abundance of river-derived terrestrial organic matter in sediments off the Changjiang Estuary. Elemental and stable isotope analyses showed significantly higher molar C/N ratios and enriched δ13C signatures for 2010 samples, which likely reflected inputs of C4 vascular plant materials. Post-flood concentrations of lignin-phenols were significantly lower in concentration than pre-flood concentrations in 2009. Lignin-phenol acid/aldehyde (Ad/Al) ratios, the lignin degradation index, showed significantly more degraded lignin post-flood in 2010 than that in 2009, which suggests greater inputs of lignins that were likely associated more with degraded soils, due to enhanced erosion from the flood, than surface plant litter. This was also in good agreement with higher inputs of another lignin soil proxy, the 3,5-Bd (3,5-dihydroxybenzoic acid) /V. Lignin-phenol source plots showed no significant differences in pre-and post flood sources, with sources largely consisting of a mixture of woody and non-woody gymnosperm and angiosperm inputs. Short lived radionuclides such as 7Be, 234Th analysis showed no apparent short-term sediment accumulation. The lack of evidence for new sediments deposited to the inner shelf after the flood was likely influenced in part, by the effects of extensive upstream damming on the Changjiang, especially the more recently constructed Three Gorges Dam.

  14. Abundance of volatile organic compounds in white ash phloem and emerald ash borer larval frass does not attract Tetrastichus planipennisi in a Y-tube olfactometer.

    PubMed

    Chen, Yigen; Ulyshen, Michael D; Poland, Therese M

    2016-10-01

    Many natural enemies employ plant- and/or herbivore-derived signals for host/prey location. The larval parasitoid Tetrastichus planipennisi Yang (Hymenoptera: Eulophidae) is 1 of 3 biocontrol agents currently being released in an effort to control the emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coloeptera: Burprestidae) in North America. To enhance its efficiency, allelochemicals that attract it need to be assessed. In this study, ash phloem volatile organic compounds (VOCs) of black, green, and white ash, and EAB larval frass were compared. Foraging behavior of T. planipennisi females in response to VOCs of white ash or frass from EAB larvae feeding on white ash phloem was tested using a Y-tube olfactometer. Results indicated that the 3 ash species had similar VOC profiles. EAB larval frass generally contained greater levels of VOCs than phloem. Factor analysis indicated that the 11 VOCs could be broadly divided into 2 groups, with α-bisabolol, β-caryophyllene, (E)-2-hexenal, (Z)-3-hexenal, limonene, methyl benzoate, methyl indole-3-acetic acid, methyl jasmonate, methyl salicylate as the first group and the rest (i.e., methyl linoleate and methyl linolenate) as a second. Abundance of VOCs in white ash phloem tissue and frass, nevertheless, did not attract T. planipennisi females. The concealed feeding of EAB larvae might explain the selection for detectable and reliable virbrational signals, instead of undetectable and relatively unreliable VOC cues from phloem and frass, in short-range foraging by T. planipennisi. Alternatively, it is possible that T. planipennisi is not amenable to the Y-tube olfactometer assay employed.

  15. Nanoplankton and picoplankton in the Western English Channel: abundance and seasonality from 2007-2013

    NASA Astrophysics Data System (ADS)

    Tarran, Glen A.; Bruun, John T.

    2015-09-01

    The nano- and picoplankton community at Station L4 in the Western English Channel was studied between 2007 and 2013 by flow cytometry to quantify abundance and investigate seasonal cycles within these communities. Nanoplankton included both photosynthetic and heterotrophic eukaryotic single-celled organisms while the picoplankton included picoeukaryote phytoplankton, Synechococcus sp. cyanobacteria and heterotrophic bacteria. A Box-Jenkins Transfer Function climatology analysis of surface data revealed that Synechococcus sp., cryptophytes, and heterotrophic flagellates had bimodal annual cycles. Nanoeukaryotes and both high and low nucleic acid-containing bacteria (HNA and LNA, respectively) groups exhibited unimodal annual cycles. Phaeocystis sp., whilst having clearly defined abundance maxima in spring was not detectable the rest of the year. Coccolithophores exhibited a weak seasonal cycle, with abundance peaks in spring and autumn. Picoeukaryotes did not exhibit a discernable seasonal cycle at the surface. Timings of maximum group abundance varied through the year. Phaeocystis sp. and heterotrophic flagellates peaked in April/May. Nanoeukaryotes and HNA bacteria peaked in June/July and had relatively high abundance throughout the summer. Synechococcus sp., cryptophytes and LNA bacteria all peaked from mid to late September. The transfer function model techniques used represent a useful means of identifying repeating annual cycles in time series data with the added ability to detect trends and harmonic terms at different time scales from months to decades.

  16. Photosynthetic gene expression in higher plants.

    PubMed

    Berry, James O; Yerramsetty, Pradeep; Zielinski, Amy M; Mure, Christopher M

    2013-11-01

    Within the chloroplasts of higher plants and algae, photosynthesis converts light into biological energy, fueling the assimilation of atmospheric carbon dioxide into biologically useful molecules. Two major steps, photosynthetic electron transport and the Calvin-Benson cycle, require many gene products encoded from chloroplast as well as nuclear genomes. The expression of genes in both cellular compartments is highly dynamic and influenced by a diverse range of factors. Light is the primary environmental determinant of photosynthetic gene expression. Working through photoreceptors such as phytochrome, light regulates photosynthetic genes at transcriptional and posttranscriptional levels. Other processes that affect photosynthetic gene expression include photosynthetic activity, development, and biotic and abiotic stress. Anterograde (from nucleus to chloroplast) and retrograde (from chloroplast to nucleus) signaling insures the highly coordinated expression of the many photosynthetic genes between these different compartments. Anterograde signaling incorporates nuclear-encoded transcriptional and posttranscriptional regulators, such as sigma factors and RNA-binding proteins, respectively. Retrograde signaling utilizes photosynthetic processes such as photosynthetic electron transport and redox signaling to influence the expression of photosynthetic genes in the nucleus. The basic C3 photosynthetic pathway serves as the default form used by most of the plant species on earth. High temperature and water stress associated with arid environments have led to the development of specialized C4 and CAM photosynthesis, which evolved as modifications of the basic default expression program. The goal of this article is to explain and summarize the many gene expression and regulatory processes that work together to support photosynthetic function in plants.

  17. Pigmentation as a survival strategy for ancient and modern photosynthetic microbes under high ultraviolet stress on planetary surfaces

    NASA Astrophysics Data System (ADS)

    Wynn-Williams, D. D.; Edwards, H. G. M.; Newton, E. M.; Holder, J. M.

    2002-01-01

    Solar radiation is the primary energy source for surface planetary life, so that pigments are fundamental components of any surface-dwelling organism. They may therefore have evolved in some form on Mars as they did on Earth. Photosynthetic microbes are major primary producers on Earth, but are concurrently vulnerable to ultraviolet (UV) damage. Using non-intrusive laser Raman spectroscopy to recognize the component parts of biomolecules, we have shown not only the abundance of microbial photosynthetic and photoprotective pigments in situ, but also their spatial distribution within their microhabitat. This essential aspect of their screening or avoidance survival strategies is lost on extraction with solvents. This precise approach is eminently suited to analysis of epilithic (surface) and endolithic (within rocks) communities in Antarctic desert habitats, which are putative analogues of early Mars. Raman spectra for key biomolecules (e.g. the UV screen parietin and the antioxidant [beta]-carotene in epilithic lichens) enable not only the detection of organics in light-stratified habitats, but also the characterization of unknown pigments. Typical biomarkers of astrobiological relevance in our Raman spectral database include scytonemin (a UV screen), chlorophyll (primary photosynthetic pigment), phycocyanin (accessory pigment for shade adaptation) and a hopanoid extracted from 2.5 Gya microbial stromatolite from Australia. This compound dates from the same time period when a wetter Mars could have had a potentially flourishing surface microbial community of its own. Analyses with a laboratory Raman instrument have been extended to a novel miniature Raman spectrometer, operating at the same optimal excitation wavelength (1064 nm) via an In-Ga-As detector. After evaluation in Antarctica, this instrument will be space-qualified for a proposed Mars rover mission to detect biomolecules in the near-surface sediment profile of palaeolakes, using experience with Antarctic

  18. Photosynthetic water splitting

    NASA Astrophysics Data System (ADS)

    Greenbaum, E.

    It has been demonstrated that eukaryotic green algae (as represented by Chlamydomonas) are inherently rugged algae with respect to the biophotolysis of water. There also exists a potential for selecting subpropulations of wild-type algae with enhanced properties for hydrogen and oxygen production. Second, hydrogenase activity in macroscopic marine algae does not conform to the conventional dogma of the catalog of reactions that this enzyme is supposed to catalyze. A kinetic argument has been presented which suggests that, with respect to light activated reactions, hydrogenase in these organisms operates primarily in a hydrogen uptake mode. Third, the light saturation curves for the simultaneous photoproduction of hydrogen and oxygen do not have the same analytical shape. It is suggested that a Photosystem I-like hydrogen producing light reaction may be present in anaerobically adapted Scenedesmus which is uncoupled from the Z scheme.

  19. Effects of ultraviolet radiation (UVA+UVB) on young gametophytes of Gelidium floridanum: growth rate, photosynthetic pigments, carotenoids, photosynthetic performance, and ultrastructure.

    PubMed

    Simioni, Carmen; Schmidt, Eder C; Felix, Marthiellen R de L; Polo, Luz Karime; Rover, Ticiane; Kreusch, Marianne; Pereira, Debora T; Chow, Fungyi; Ramlov, Fernanda; Maraschin, Marcelo; Bouzon, Zenilda L

    2014-01-01

    This study investigated the effects of radiation (PAR+UVA+UVB) on the development and growth rates (GRs) of young gametophytes of Gelidium floridanum. In addition, photosynthetic pigments were quantified, carotenoids identified, and photosynthetic performance assessed. Over a period of 3 days, young gametophytes were cultivated under laboratory conditions and exposed to photosynthetically active radiation (PAR) at 80 μmol photons m(-2) s(-1) and PAR+UVA (0.70 W m(-2))+UVB (0.35 W m(-2)) for 3 h per day. The samples were processed for light and electron microscopy to analyze the ultrastructure features, as well as carry out metabolic studies of GRs, quantify the content of photosynthetic pigments, identify carotenoids and assess photosynthetic performance. PAR+UVA+UVB promoted increase in cell wall thickness, accumulation of floridean starch grains in the cytoplasm and disruption of chloroplast internal organization. Algae exposed to PAR+UVA+UVB also showed a reduction in GR of 97%. Photosynthetic pigments, in particular, phycoerythrin and allophycocyanin contents, decreased significantly from UV radiation exposure. This result agrees with the decrease in photosynthetic performance observed after exposure to ultraviolet radiation, as measured by a decrease in the electron transport rate (ETR), where values of ETRmax declined approximately 44.71%. It can be concluded that radiation is a factor that affects the young gametophytes of G. floridanum at this stage of development.

  20. Phytochromes in photosynthetically competent plants

    SciTech Connect

    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.

  1. Photosynthetic Machineries in Nano-Systems

    PubMed Central

    Nagy, László; Magyar, Melinda; Szabó, Tibor; Hajdu, Kata; Giotta, Livia; Dorogi, Márta; Milano, Francesco

    2014-01-01

    Photosynthetic reaction centres are membrane-spanning proteins, found in several classes of autotroph organisms, where a photoinduced charge separation and stabilization takes place with a quantum efficiency close to unity. The protein remains stable and fully functional also when extracted and purified in detergents thereby biotechnological applications are possible, for example, assembling it in nano-structures or in optoelectronic systems. Several types of bionanocomposite materials have been assembled by using reaction centres and different carrier matrices for different purposes in the field of light energy conversion (e.g., photovoltaics) or biosensing (e.g., for specific detection of pesticides). In this review we will summarize the current status of knowledge, the kinds of applications available and the difficulties to be overcome in the different applications. We will also show possible research directions for the close future in this specific field. PMID:24678673

  2. Photosynthetic machineries in nano-systems.

    PubMed

    Nagy, László; Magyar, Melinda; Szabó, Tibor; Hajdu, Kata; Giotta, Livia; Dorogi, Márta; Milano, Francesco

    2014-01-01

    Photosynthetic reaction centres are membrane-spanning proteins, found in several classes of autotroph organisms, where a photoinduced charge separation and stabilization takes place with a quantum efficiency close to unity. The protein remains stable and fully functional also when extracted and purified in detergents thereby biotechnological applications are possible, for example, assembling it in nano-structures or in optoelectronic systems. Several types of bionanocomposite materials have been assembled by using reaction centres and different carrier matrices for different purposes in the field of light energy conversion (e.g., photovoltaics) or biosensing (e.g., for specific detection of pesticides). In this review we will summarize the current status of knowledge, the kinds of applications available and the difficulties to be overcome in the different applications. We will also show possible research directions for the close future in this specific field.

  3. The secondary history of Sutter's Mill CM carbonaceous chondrite based on water abundance and the structure of its organic matter from two clasts

    NASA Astrophysics Data System (ADS)

    Beck, P.; Quirico, E.; Garenne, A.; Yin, Q.-Z.; Bonal, L.; Schmitt, B.; Montes-Hernandez, G.; Montagnac, G.; Chiriac, R.; Toche, F.

    2014-11-01

    Sutter's Mill is a regolith breccia composed of both heavily altered clasts and more reduced xenoliths. Here, we present a detailed investigation of fragments of SM18 and SM51. We have characterized the water content and the mineralogy by infrared (IR) and thermogravimetric analysis (TGA) and the structure of the organic compounds by Raman spectroscopy, to characterize the secondary history of the clasts, including aqueous alteration and thermal metamorphism. The three methods used in this study suggest that SM18 was significantly heated. The amount of water contained in phyllosilicates derived by TGA is estimated to be approximately 3.2 wt%. This value is quite low compared with other CM chondrites that typically range from 6 to 12 wt%. The infrared transmission spectra of SM18 show that the mineralogy of the sample is dominated by a mixture of phyllosilicate and olivine. SM18 shows an intense peak at 11.2 μm indicative of olivine (Fig. 1). If we compare SM18 with other CM and metamorphosed CM chondrites, it shows one of the most intense olivine signatures, and therefore a lower proportion of phyllosilicate minerals. The Raman results tend to support a short-duration heating hypothesis. In the ID/IG versus FWHM-D diagram, SM18 appears to be unusual compared to most CM samples, and close to the metamorphosed CM chondrites Pecora Escarpment (PCA) 91008 and PCA 02012. In the case of SM51, infrared spectroscopy reveals that olivine is less abundant than in SM18 and the 10 μm silicate feature is more similar to that of moderately altered CM chondrites (like Murchison or Queen Alexandra Range [QUE] 97990). Raman spectroscopy does not clearly point to a heating event for SM51 in the ID/IG versus FWHM-D diagram. However, TGA analysis suggests that SM51 was slightly dehydrated as the amount of water contained in phyllosilicates is approximately 3.7 wt%, which is higher than SM18, but still lower than phyllosilicate water contents in weakly altered CM chondrites

  4. Application of photosynthetic N(2)-fixing cyanobacteria to the CELSS program

    NASA Technical Reports Server (NTRS)

    Fry, Ian V.; Hrabeta, Jana; Dsouza, Joe; Packer, Lester

    1987-01-01

    The feasibility of using photosynthetic microalgae (cyanobacteria) as a subsystem component for the closed ecological life support system program, with particular emphasis on the manipulation of the biomass (protein/carbohydrate) was addressed. Using factors which retard growth rates, but not photosynthetic electron flux, the partitioning of photosynthetically derived reductant may be dictated towards CO2 fixation (carbohydrate formation) and away from N2 fixation (protein formation). Cold shock treatment of fairly dense cultures markedly increases the glycogen content from 1 to 35 percent (dry weight), and presents a useful technique to change the protein/carbohydrate ratio of these organisms to a more nutritionally acceptable form.

  5. Short-term acclimation of the photosynthetic electron transfer chain to changing light: a mathematical model.

    PubMed

    Ebenhöh, Oliver; Fucile, Geoffrey; Finazzi, Giovanni; Rochaix, Jean-David; Goldschmidt-Clermont, Michel

    2014-04-19

    Photosynthetic eukaryotes house two photosystems with distinct light absorption spectra. Natural fluctuations in light quality and quantity can lead to unbalanced or excess excitation, compromising photosynthetic efficiency and causing photodamage. Consequently, these organisms have acquired several distinct adaptive mechanisms, collectively referred to as non-photochemical quenching (NPQ) of chlorophyll fluorescence, which modulates the organization and function of the photosynthetic apparatus. The ability to monitor NPQ processes fluorometrically has led to substantial progress in elucidating the underlying molecular mechanisms. However, the relative contribution of distinct NPQ mechanisms to variable light conditions in different photosynthetic eukaryotes remains unclear. Here, we present a mathematical model of the dynamic regulation of eukaryotic photosynthesis using ordinary differential equations. We demonstrate that, for Chlamydomonas, our model recapitulates the basic fluorescence features of short-term light acclimation known as state transitions and discuss how the model can be iteratively refined by comparison with physiological experiments to further our understanding of light acclimation in different species.

  6. [Photosynthetic and water physiological characteristics of weedy rice in northern China].

    PubMed

    Gao, Qi; Ma, Dian-Rong; Kong, De-Xiu; Wang, Wen-Jia; Tong, Hui; Zhao, Ming-Hui; Xu, Zheng-Jin; Chen, Wen-Fu

    2013-11-01

    Weedy rice is an important germplasm source of rice, which has the characteristics of cold-, drought-, and barren tolerance. Taking 88 accessions of weedy rice and 4 varieties of cultivated rice in northern China as test materials, this paper studied the photosynthetic characteristics (photosynthetic rate, transpiration rate, and stomatal conductance), water physiological characteristics, and their interrelationships of weedy rice in northern China. There existed greater differences in the photosynthetic and water physiological characteristics among the weedy rice accessions, possessing abundant diversity. The photosynthetic rate of the accessions was from 12.47 micromol CO2 x m(-2) x s(-1) to 28.67 micromol CO2 X m(-2) x s(-1), and the instantaneous water use efficiency was from 1.39 mg x g(-1) to 3.40 mg x g(-1). Among the photosynthetic parameters, intercellular CO2 concentration had the smallest variable coefficient, while stomatal conductance had the largest one. The photosynthetic rate had significant conic relationships with transpiration rate and stomatal conductance, and had a linear relationship with intercellular CO2 concentration. The significant conic relationships also existed between the instantaneous water use efficiency and the transpiration rate and stomatal conductance. The excellent features of weedy rice could be used to improve the cultivated rice varieties.

  7. ENHANCED PRACTICAL PHOTOSYNTHETIC CO2 MITIGATION

    SciTech Connect

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

    2004-01-30

    This quarterly report documents significant achievements in the Enhanced Practical Photosynthetic CO{sub 2} Mitigation project during the period from 10/2/2003 through 1/1/2004. As indicated in the list of accomplishments below we have seen very encouraging results from the model scale tests in terms of organism growth rates and we have begun the final tests necessary to meet our project goals. Specific results and accomplishments for the fourth quarter of 2003 include: (1) Bioreactor support systems and test facilities--(A) The solar collector is working well and has survived the winter weather. (B) The improved high-flow CRF-2 test system has been used successfully to run several long-term growth tests with periodic harvesting events. The high flow harvesting system performed well. The mass measurement results after a 4-week test show 275% growth over the initial mass loading. This figure would have been higher had there been no leakage and handling losses. Carbon dating of biomass from this test is planned for carbon uptake estimation. The next test will include direct measurement of carbon uptake in addition to organism mass measurements. (C) Qualitative organism growth testing has begun in the pilot scale bioreactor. Some issues with uniformity of organism loading, fluid leakage and evaporation have surfaced and are currently being addressed, and quantitative testing will begin as soon as these problems are resolved. (2) Organisms and Growth Surfaces--(A) Montana State University (Subcontracted to do organism studies) submitted their final (3-year) project report. An abstract of the report in included in this quarterly report.

  8. Functional Relationship Between Phytoplankton and Aerobic Anoxygenic Photosynthetic Bacteria: Modes of Coexistence

    NASA Astrophysics Data System (ADS)

    Kolber, Z. S.; Haffa, A.; Klimov, D.

    2006-12-01

    Aerobic Anoxygenic Photosynthetic Bacteria (AAPs) are ubiquitously distributed in the upper ocean. Although they contain bacteriochlorophyll a (BChla), the main absorption bands in the near UV (370 nm) and infrared (800-850 nm) make this pigment impractical in light harvesting below the first few meters of the water column. Instead, they utilize carotenoids as major light harvesting pigments. Since these carotenoids absorb in the 430-550 nm range, phytoplankton and AAPs utilize a similar portion of the available light spectrum. As AAPs cannot utilize water as the electron donor, they transfer electrons between a range of organic/inorganic electron donors and electron acceptors, thus significantly participating in the redox cycle in the upper ocean. We have measured the vertical distribution and photosynthetic properties of both phytoplankton and AAPs in a highly oligotrophic region 800 km SW of Monterey Bay (34N, 129W), and we have consistently observed the presence of a BChla maximum about 30 to 40 meters above the chlorophyll maximum, indicating that phytoplankton and AAPs occupy different ecological niches in the water column. However, the abundance of AAPs generally displayed a maximum at dawn and a minimum at the dusk, indicating a high level of mortality. This diel cycle was observed in 5 micron and 3 micron size fractions, indicating active grazing by small protists. Incubation experiments with natural, mixed population of AAPs and phytoplankton results in an unusually high accumulation of AAPs in DCMU-treated samples, indicating that pigmented protists do contribute significantly to AAP grazing in a tightly-controlled microbial loop. On the other hand, AAP incubations in pure cultures indicate that they biomineralize sulfur, thus affecting the sulfur cycle. All of these observations indicate that the role of AAPs in the upper ocean ecology is defined by their relationship with phototrophic and heterotrophic communities, rather than by their relative

  9. ENHANCED PRACTICAL PHOTOSYNTHETIC CO2 MITIGATION

    SciTech Connect

    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.

  10. [Photosynthetic characteristics of Gynostemma pentaphyllum under shade].

    PubMed

    Huang, Chenglin; Wu, Zemin; Yao, Yongkang; Xu, Xiaoniu

    2004-11-01

    The study showed that under summer shade condition, the diurnal variation of net photosynthetic rate of Gynostemma pentaphyllum presented nontypical double apex, the first apex being 13.8 micromol CO2 x m(-2) x s(-1) at 11:00, and the diurnal net photosynthetic rate was about 176.97 micromol CO2 x m(-2), 3.1 times of that under full sunlight. There was a positive correlation between net photosynthetic rate and photon flux density (PFD), and relative humidity had a small effect on net photosynthetic rate. Under full sunlight, the typical "midday depression" of photosynthesis was observed, and the diurnal variation of net photosynthetic rate presented double apex, with the first apex being 3.0 micromol CO2 x m(-2) x s(-1) at 10:00 and the second being 1.25 micromol CO2 x m(-2) x s(-1) at 14:00. There was a positive correlation between net photosynthetic rate and relative humidity, and the latter had a strong effect on net photosynthetic rate. When PFD was higher than 700 micromol CO2 x m(-2) x s(-1), it had a negative correlation with net photosynthetic rate. Stoma conductance was the main factor affecting the transpiration rate of Gynostemma pentaphyllum. Therefore, Gynostemma pentaphyllum was a typical sciophytic plant, and light factor should be considered firstly in its cultivation. PMID:15707321

  11. ENHANCED PRACTICAL PHOTOSYNTHETIC CO2 MITIGATION

    SciTech Connect

    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.

  12. Ion antiport accelerates photosynthetic acclimation in fluctuating light environments

    PubMed Central

    Armbruster, Ute; Carrillo, L. Ruby; Venema, Kees; Pavlovic, Lazar; Schmidtmann, Elisabeth; Kornfeld, Ari; Jahns, Peter; Berry, Joseph A.; Kramer, David M.; Jonikas, Martin C.

    2014-01-01

    Many photosynthetic organisms globally, including crops, forests and algae, must grow in environments where the availability of light energy fluctuates dramatically. How photosynthesis maintains high efficiency despite such fluctuations in its energy source remains poorly understood. Here we show that Arabidopsis thaliana K+ efflux antiporter (KEA3) is critical for high photosynthetic efficiency under fluctuating light. On a shift from dark to low light, or high to low light, kea3 mutants show prolonged dissipation of absorbed light energy as heat. KEA3 localizes to the thylakoid membrane, and allows proton efflux from the thylakoid lumen by proton/potassium antiport. KEA3’s activity accelerates the downregulation of pH-dependent energy dissipation after transitions to low light, leading to faster recovery of high photosystem II quantum efficiency and increased CO2 assimilation. Our results reveal a mechanism that increases the efficiency of photosynthesis under fluctuating light. PMID:25451040

  13. Ion antiport accelerates photosynthetic acclimation in fluctuating light environments.

    PubMed

    Armbruster, Ute; Carrillo, L Ruby; Venema, Kees; Pavlovic, Lazar; Schmidtmann, Elisabeth; Kornfeld, Ari; Jahns, Peter; Berry, Joseph A; Kramer, David M; Jonikas, Martin C

    2014-11-13

    Many photosynthetic organisms globally, including crops, forests and algae, must grow in environments where the availability of light energy fluctuates dramatically. How photosynthesis maintains high efficiency despite such fluctuations in its energy source remains poorly understood. Here we show that Arabidopsis thaliana K(+) efflux antiporter (KEA3) is critical for high photosynthetic efficiency under fluctuating light. On a shift from dark to low light, or high to low light, kea3 mutants show prolonged dissipation of absorbed light energy as heat. KEA3 localizes to the thylakoid membrane, and allows proton efflux from the thylakoid lumen by proton/potassium antiport. KEA3's activity accelerates the downregulation of pH-dependent energy dissipation after transitions to low light, leading to faster recovery of high photosystem II quantum efficiency and increased CO2 assimilation. Our results reveal a mechanism that increases the efficiency of photosynthesis under fluctuating light.

  14. Influence of thermal light correlations on photosynthetic structures

    NASA Astrophysics Data System (ADS)

    de Mendoza, Adriana; Manrique, Pedro; Caycedo-Soler, Felipe; Johnson, Neil F.; Rodríguez, Ferney J.; Quiroga, Luis

    2014-03-01

    The thermal light from the sun is characterized by both classical and quantum mechanical correlations. These correlations have left a fingerprint on the natural harvesting structures developed through five billion years of evolutionary pressure, specially in photosynthetic organisms. In this work, based upon previous extensive studies of spatio-temporal correlations of light fields, we hypothesize that structures involving photosensitive pigments like those present in purple bacteria vesicles emerge as an evolutionary response to the different properties of incident light. By using burstiness and memory as measures that quantify higher moments of the photon arrival statistics, we generate photon-time traces. They are used to simulate absorption on detectors spatially extended over regions comparable to these light fields coherence length. Finally, we provide some insights into the connection between these photo-statistical features with the photosynthetic membrane architecture and the lights' spatial correlation. Facultad de Ciencias Uniandes.

  15. Ion antiport accelerates photosynthetic acclimation in fluctuating light environments.

    PubMed

    Armbruster, Ute; Carrillo, L Ruby; Venema, Kees; Pavlovic, Lazar; Schmidtmann, Elisabeth; Kornfeld, Ari; Jahns, Peter; Berry, Joseph A; Kramer, David M; Jonikas, Martin C

    2014-01-01

    Many photosynthetic organisms globally, including crops, forests and algae, must grow in environments where the availability of light energy fluctuates dramatically. How photosynthesis maintains high efficiency despite such fluctuations in its energy source remains poorly understood. Here we show that Arabidopsis thaliana K(+) efflux antiporter (KEA3) is critical for high photosynthetic efficiency under fluctuating light. On a shift from dark to low light, or high to low light, kea3 mutants show prolonged dissipation of absorbed light energy as heat. KEA3 localizes to the thylakoid membrane, and allows proton efflux from the thylakoid lumen by proton/potassium antiport. KEA3's activity accelerates the downregulation of pH-dependent energy dissipation after transitions to low light, leading to faster recovery of high photosystem II quantum efficiency and increased CO2 assimilation. Our results reveal a mechanism that increases the efficiency of photosynthesis under fluctuating light. PMID:25451040

  16. Pigment oligomers as natural and artificial photosynthetic antennas

    SciTech Connect

    Blankenship, R.E.

    1996-12-31

    Green photosynthetic bacteria contain antenna complexes known as chlorosomes. These complexes are appressed to the cytoplasmic side of the inner cell membrane and function to absorb light and transfer the energy to the photochemical reaction center, where photochemical energy storage takes place. Chlorosomes differ from all other known photosynthetic antenna complexes in that the geometrical arrangement of pigments is determined primarily by pigment-pigment interactions instead of pigment-protein interactions. The bacteriochlorophyll c, d or e pigments found in chlorosomes form large oligomers with characteristic spectral properties significantly perturbed from those exhibited by monomeric pigments. Because of their close spatial interaction, the pigments are thought to be strongly coupled electronically, and many of the optical properties result from exciton interactions. This presentation will summarize existing knowledge on the chemical composition and properties of chlorosomes, the evidence for the oligomeric nature of chlorosome pigment organization and proposed structures for the oligomers, and the kinetics and mechanisms of energy transfer in chlorosomes.

  17. An Investigation into the Physico-chemical Factors Affecting the Abundance and Diversity of Aquatic Insects in Organically Manured Aquadams and Their Utilization by Oreochromis mossambicus (Perciformes: Cichlidae).

    PubMed

    Rapatsa, M M; Moyo, N A G

    2015-08-01

    The interaction between the fish Oreochromis mossambicus (Percifomes: Cichlidae) and aquatic insects after application of chicken, cow, and pig manure was studied in 7,000-liter plastic aquadams. Principal component analysis showed that most of the variation in water quality after application of manure was accounted for by potassium, nitrogen, dissolved oxygen, phosphate, and alkalinity. Canonical correspondence analysis showed that Gyrinidae, Elminidae, Hydrophilidae, Hydraenidae, and Athericidae were associated with high nutrient levels (nitrogen, phosphorus, and potassium) characteristic of the chicken manure. However, the most abundant aquatic insects Gerridae, Notonectidae, and Culicidae were close to the centre of the ordination and not defined by any nutrient gradient. The Shannon-Wiener diversity was highest in the aquadams treated with chicken manure. The most frequently occurring aquatic insects in the diet of O. mossambicus were culicid mosquitoes in all the treatments. However, in the laboratory, Chironomidae were the most preferred because they lacked refuge. Notonectidae and Gerridae were not recorded in the diet of O. mossambicus despite their abundance. This may be because of their anti-predation strategies. Laboratory experiments showed that Notonectidae, Gyrinidae, and Gerridae fed on Chironomidae and Culicidae. This implies that aquatic predatory insects competed for food with O. mossambicus. PMID:26314044

  18. An Investigation into the Physico-chemical Factors Affecting the Abundance and Diversity of Aquatic Insects in Organically Manured Aquadams and Their Utilization by Oreochromis mossambicus (Perciformes: Cichlidae).

    PubMed

    Rapatsa, M M; Moyo, N A G

    2015-08-01

    The interaction between the fish Oreochromis mossambicus (Percifomes: Cichlidae) and aquatic insects after application of chicken, cow, and pig manure was studied in 7,000-liter plastic aquadams. Principal component analysis showed that most of the variation in water quality after application of manure was accounted for by potassium, nitrogen, dissolved oxygen, phosphate, and alkalinity. Canonical correspondence analysis showed that Gyrinidae, Elminidae, Hydrophilidae, Hydraenidae, and Athericidae were associated with high nutrient levels (nitrogen, phosphorus, and potassium) characteristic of the chicken manure. However, the most abundant aquatic insects Gerridae, Notonectidae, and Culicidae were close to the centre of the ordination and not defined by any nutrient gradient. The Shannon-Wiener diversity was highest in the aquadams treated with chicken manure. The most frequently occurring aquatic insects in the diet of O. mossambicus were culicid mosquitoes in all the treatments. However, in the laboratory, Chironomidae were the most preferred because they lacked refuge. Notonectidae and Gerridae were not recorded in the diet of O. mossambicus despite their abundance. This may be because of their anti-predation strategies. Laboratory experiments showed that Notonectidae, Gyrinidae, and Gerridae fed on Chironomidae and Culicidae. This implies that aquatic predatory insects competed for food with O. mossambicus.

  19. Hydrogen Biogeochemistry in Anaerobic and Photosynthetic Ecosystems

    NASA Technical Reports Server (NTRS)

    Hoehler, Tori M.; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    The simple biochemistry of molecular hydrogen is central to a large number of microbial processes, affecting the interaction of organisms with each other and with the environment. In anoxic sediments, a great majority of microbial redox processes involve hydrogen as a reactant, product or potential by-product. Accordingly, the energetics (thermodynamics) of each of these processes is affected by variations in local H2 concentrations. It has long been established that this effect is important in governing microbe-microbe interactions and there are multiple demonstrations that "interspecies hydrogen transfer" can alter the products of, inhibit/stimulate, or even reverse microbial metabolic reactions. In anoxic sediments, H2 concentrations themselves are thought to be controlled by the thermodynamics of the predominant H2-consuming microbial process. In sediments from Cape Lookout Bight, this relationship quantitatively describes the co-variation of H2 concentrations with temperature (for methanogens and sulfate reducers) and with sulfate concentration (for sulfate reducers). The quantitative aspect is import= for two reasons: 1) it permits the modeling of H2-sensitive biogeochemistry, such as anaerobic methane oxidation or pathways of organic matter remineralization, as a function of environmental controls; 2) for such a relationship to be observed requires that intracellular biochemistry and bioenergetics are being directly expressed in a component of the extracellular medium. H2 could therefore be utilized a non-invasive probe of cellular energetic function in intact microbial ecosystems. Based on the latter principle we have measured down-core profiles of H2 and other relevant physico-chemical parameters in order to calculate the metabolic energy yields (DG) that support microbial metabolism in Cape Lookout Bight sediments. Methanogens in this system apparently function with energy yields significantly smaller than the minimum requirements suggested by pure

  20. Abundance of Cosmogenic Noble Gases as a Marker of the Organic Degradation by Cosmic Rays in the Surface Martian Rocks. Implications to MSL and Mars 2020

    NASA Astrophysics Data System (ADS)

    Pavlov, A. A.; Vasilyev, G. I.; Ostryakov, V. M.; Pavlov, A. K.; Mahaffy, P.

    2014-07-01

    We conducted a modeling study which links the rates of cosmogenic isotopes production with the radiation accumulation rates on Mars. We calculated the degradation level of the organic molecules at Cumberland based on the observed cosmogenic isotopes.

  1. Elevated atmospheric CO2 affected photosynthetic products in wheat seedlings and biological activity in rhizosphere soil under cadmium stress.

    PubMed

    Jia, Xia; Liu, Tuo; Zhao, Yonghua; He, Yunhua; Yang, Mingyan

    2016-01-01

    The objective of this study was to investigate the effects of elevated CO2 (700 ± 23 μmol mol(-1)) on photosynthetic products in wheat seedlings and on organic compounds and biological activity in rhizosphere soil under cadmium (Cd) stress. Elevated CO2 was associated with decreased quantities of reducing sugars, starch, and soluble amino acids, and with increased quantities of soluble sugars, total sugars, and soluble proteins in wheat seedlings under Cd stress. The contents of total soluble sugars, total free amino acids, total soluble phenolic acids, and total organic acids in the rhizosphere soil under Cd stress were improved by elevated CO2. Compared to Cd stress alone, the activity of amylase, phenol oxidase, urease, L-asparaginase, β-glucosidase, neutral phosphatase, and fluorescein diacetate increased under elevated CO2 in combination with Cd stress; only cellulase activity decreased. Bacterial abundance in rhizosphere soil was stimulated by elevated CO2 at low Cd concentrations (1.31-5.31 mg Cd kg(-1) dry soil). Actinomycetes, total microbial abundance, and fungi decreased under the combined conditions at 5.31-10.31 mg Cd kg(-1) dry soil. In conclusion, increased production of soluble sugars, total sugars, and proteins in wheat seedlings under elevated CO2 + Cd stress led to greater quantities of organic compounds in the rhizosphere soil relative to seedlings grown under Cd stress only. Elevated CO2 concentrations could moderate the effects of heavy metal pollution on enzyme activity and microorganism abundance in rhizosphere soils, thus improving soil fertility and the microecological rhizosphere environment of wheat under Cd stress.

  2. Changes in partitioning of carbon amongst photosynthetic pico- and nano-plankton groups in the Sargasso Sea in response to changes in the North Atlantic Oscillation

    NASA Astrophysics Data System (ADS)

    Casey, John R.; Aucan, Jerome P.; Goldberg, Stacey R.; Lomas, Michael W.

    2013-09-01

    Picophytoplankton carbon biomass at the Bermuda Atlantic Time-series Study (BATS) site from June 2004 to December 2010 was estimated from the direct calibration of cellular carbon content and forward light scatter (via flow cytometry). Seasonality and interannual dynamics of Prochlorococcus, Synechococcus and small eukaryotic algae (<12 μm diameter) abundance, cellular carbon content (QC; particulate organic carbon; POC cell-1), and group-specific carbon biomass are reported. QC of individual taxa varied with depth and season by as much as an order of magnitude, roughly comparable to variability in abundance. During the time-series there were obvious shifts in the taxonomic distribution of photosynthetic carbon biomass; these interannual shifts in biomass were due to simultaneous changes in both QC and cell abundance. The observed pattern was not apparent from numerical abundance alone, highlighting the importance of QC measurements in place of using fixed conversion factors to better understand biological carbon dynamics. Changes in the phase of the North Atlantic Oscillation (NAO) from positive to negative modes correlated with shifts in biomass between picocyanobacteria and small eukaryotic algae, respectively. Thus, shifts in algal community structure are inferred to be associated with changes in light intensity and implied nutrient supply via mixing (i.e., patterns in upper ocean stability). These observed changes in phytoplankton biomass partitioning were correlated with the important ocean carbon cycle parameters of export flux, mesopelagic transfer efficiency, and elemental stoichiometry. Importantly, interannual relationships between these parameters and algal biomass were detected only when QC was considered as variable.

  3. [Effects of light quality on photosynthetic pigment contents and photosynthetic characteristics of peanut seedling leaves].

    PubMed

    Yan, Meng-Meng; Wang, Ming-Lun; Wang, Hong-Bo; Wang, Yue-Fu; Zhao, Chang-Xing

    2014-02-01

    This study explored the effects of different light quality on photosynthetic pigment contents and photosynthetic characteristics of peanut (Qinhua 6) seedling leaves. The results showed that, compared with natural light, blue light (445-470 nm) could significantly improve the specific leaf area (SLA), chlorophyll a/b value and carotenoid content of peanut seedlings. Meanwhile, the net photosynthetic rate, stomatal conductance, and transpiration rate were higher, the intercellular CO2 content was lower, and the photosynthetic efficiency was improved significantly under blue light. Red light (610-660 nm) could improve the chlorophyll content significantly, and reduce SLA, chlorophyll a/b value and carotenoid content, with a lower photosynthetic efficiency than natural light. Green light (515-520 nm) and yellow light (590-595 nm) were not conducive to photosynthetic pigment accumulation of leaves, and significantly inhibited leaf photosynthesis of peanut seedlings.

  4. Multiantenna artificial photosynthetic reaction center complex.

    PubMed

    Terazono, Yuichi; Kodis, Gerdenis; Liddell, Paul A; Garg, Vikas; Moore, Thomas A; Moore, Ana L; Gust, Devens

    2009-05-21

    In order to ensure efficient utilization of the solar spectrum, photosynthetic organisms use a variety of antenna chromophores to absorb light and transfer excitation to a reaction center, where photoinduced charge separation occurs. Reported here is a synthetic molecular heptad that features two bis(phenylethynyl)anthracene and two borondipyrromethene antennas linked to a hexaphenylbenzene core that also bears two zinc porphyrins. A fullerene electron acceptor self-assembles to both porhyrins via dative bonds. Excitation energy is transferred very efficiently from all four antennas to the porphyrins. Singlet-singlet energy transfer occurs both directly and by a stepwise funnel-like pathway wherein excitation moves down a thermodynamic gradient. The porphyrin excited states donate an electron to the fullerene with a time constant of 3 ps to generate a charge-separated state with a lifetime of 230 ps. The overall quantum yield is close to unity. In the absence of the fullerene, the porphyrin excited singlet state donates an electron to a borondipyrromethene on a slower time scale. This molecule demonstrates that by incorporating antennas, it is possible for a molecular system to harvest efficiently light throughout the visible from ultraviolet wavelengths out to approximately 650 nm.

  5. Photosynthetic lesions can trigger accelerated senescence in Arabidopsis thaliana.

    PubMed

    Wang, Jing; Leister, Dario; Bolle, Cordelia

    2015-11-01

    Senescence is a highly regulated process characterized by the active breakdown of cells, which ultimately leads to the death of plant organs or whole plants. In annual plants such as Arabidopsis thaliana senescence can be observed in each individual leaf. Whether deficiencies in photosynthesis promote the induction of senescence was investigated by monitoring chlorophyll degradation, photosynthetic parameters, and reactive oxygen species accumulation in photosynthetic mutants. Several mutations affecting components of the photosynthetic apparatus, including psal-2, psan-2, and psbs, were found to lead to premature or faster senescence, as did simultaneous inactivation of the STN7 and STN8 kinases. Premature senescence is apparently not directly linked to an overall reduction in photosynthesis but to perturbations in specific aspects of the process. Dark-induced senescence is accelerated in mutants affected in linear electron flow, especially psad2-1, psan-2, and pete2-1, as well as in stn7 and stn8 mutants and STN7 and STN8 overexpressor lines. Interestingly, no direct link with ROS production could be observed. PMID:26272903

  6. Early photosynthetic microorganisms and environmental evolution

    NASA Technical Reports Server (NTRS)

    Golubic, S.

    1980-01-01

    Microfossils which are preserved as shrivelled kerogenous residues provide little information about cellular organization and almost none about the metabolic properties of the organisms. The distinction between prokaryotic vs eukaryotic, and phototrophic vs chemo- and organotrophic fossil microorganisms rests entirely on morphological comparisons with recent counterparts. The residual nature of the microbial fossil record promotes the conclusion that it must be biased toward (a) most abundant organisms, (b) those most resistant to degradation, and (c) those inhabiting environments with high preservation potential e.g., stromatolites. These criteria support the cyanophyte identity of most Precambrian microbial fossils on the following grounds: (1) as primary producers they dominate prokaryotic communities in modern extreme environments, e.g., intertidal zone; (2) several morphological counterparts of modern cyanophytes and microbial fossils have been established based on structure, cell division patterns and degradation sequences. The impact of anaerobic and oxygenic microbial photosynthesis on the evolution of Precambrian environments is discussed.

  7. The Regulation of Photosynthetic Structure and Function during Nitrogen Deprivation in Chlamydomonas reinhardtii1[OPEN

    PubMed Central

    Juergens, Matthew T.; Deshpande, Rahul R.; Lucker, Ben F.; Park, Jeong-Jin; Wang, Hongxia; Gargouri, Mahmoud; Holguin, F. Omar; Disbrow, Bradley; Schaub, Tanner; Skepper, Jeremy N.; Kramer, David M.; Gang, David R.; Hicks, Leslie M.; Shachar-Hill, Yair

    2015-01-01

    The accumulation of carbon storage compounds by many unicellular algae after nutrient deprivation occurs despite declines in their photosynthetic apparatus. To understand the regulation and roles of photosynthesis during this potentially bioenergetically valuable process, we analyzed photosynthetic structure and function after nitrogen deprivation in the model alga Chlamydomonas reinhardtii. Transcriptomic, proteomic, metabolite, and lipid profiling and microscopic time course data were combined with multiple measures of photosynthetic function. Levels of transcripts and proteins of photosystems I and II and most antenna genes fell with differing trajectories; thylakoid membrane lipid levels decreased, while their proportions remained similar and thylakoid membrane organization appeared to be preserved. Cellular chlorophyll (Chl) content decreased more than 2-fold within 24 h, and we conclude from transcript protein and 13C labeling rates that Chl synthesis was down-regulated both pre- and posttranslationally and that Chl levels fell because of a rapid cessation in synthesis and dilution by cellular growth rather than because of degradation. Photosynthetically driven oxygen production and the efficiency of photosystem II as well as P700+ reduction and electrochromic shift kinetics all decreased over the time course, without evidence of substantial energy overflow. The results also indicate that linear electron flow fell approximately 15% more than cyclic flow over the first 24 h. Comparing Calvin-Benson cycle transcript and enzyme levels with changes in photosynthetic 13CO2 incorporation rates also pointed to a coordinated multilevel down-regulation of photosynthetic fluxes during starch synthesis before the induction of high triacylglycerol accumulation rates. PMID:25489023

  8. Phosphorylation stoichiometry determination in plant photosynthetic membranes.

    PubMed

    Ingelsson, Björn; Fristedt, Rikard; Turkina, Maria V

    2015-01-01

    This chapter describes different strategies for the study of phosphorylation dynamics and stoichiometry in photosynthetic membranes. Detailed procedures for the detection, large-scale identification, and quantification of phosphorylated proteins optimized for plant thylakoid proteins are given. PMID:25930698

  9. Hybrid system of semiconductor and photosynthetic protein.

    PubMed

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

    2014-08-29

    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.

  10. [(3) H]-L685,458 binding sites are abundant in multiple peripheral organs in rats: implications for safety assessment of putative γ-secretase targeting drugs.

    PubMed

    Yang, Zhi-Ying; Li, Jian-Ming; Xiao, Ling; Mou, Lin; Cai, Yan; Huang, He; Luo, Xue-Gang; Yan, Xiao-Xin

    2014-12-01

    γ-Secretase is a multimeric enzyme complex that carries out proteolytic processing to a variety of cellular proteins. It is currently explored as a therapeutic target for Alzheimer's disease (AD) and cancer. Mechanism-based toxicity needs to be thoroughly evaluated for γ-secretase inhibitory and/or modulatory drugs. This study comparatively assessed putative γ-secretase catalytic sites in rat peripheral tissues relative to brain and explored an effort of its pharmacological inhibition on hair regeneration. Using [(3) H]-labelled L685,458, a potent γ-secretase inhibitor, as probe, we found more abundant presence of γ-secretase binding sites in the liver, gastrointestinal tract, hair follicle, pituitary gland, ovary and testis, as compared to the brain. Local application of L658,458 delayed vibrissal regrowth following whisker removal. These results suggest that γ-secretase may execute important biological functions in many peripheral systems, as in the brain. The development of γ-secretase inhibitors/modulators for AD and cancer therapy should include close monitoring of toxicological panels for hepatic, gastrointestinal, endocrinal and reproductive functions. PMID:24861611

  11. [(3) H]-L685,458 binding sites are abundant in multiple peripheral organs in rats: implications for safety assessment of putative γ-secretase targeting drugs.

    PubMed

    Yang, Zhi-Ying; Li, Jian-Ming; Xiao, Ling; Mou, Lin; Cai, Yan; Huang, He; Luo, Xue-Gang; Yan, Xiao-Xin

    2014-12-01

    γ-Secretase is a multimeric enzyme complex that carries out proteolytic processing to a variety of cellular proteins. It is currently explored as a therapeutic target for Alzheimer's disease (AD) and cancer. Mechanism-based toxicity needs to be thoroughly evaluated for γ-secretase inhibitory and/or modulatory drugs. This study comparatively assessed putative γ-secretase catalytic sites in rat peripheral tissues relative to brain and explored an effort of its pharmacological inhibition on hair regeneration. Using [(3) H]-labelled L685,458, a potent γ-secretase inhibitor, as probe, we found more abundant presence of γ-secretase binding sites in the liver, gastrointestinal tract, hair follicle, pituitary gland, ovary and testis, as compared to the brain. Local application of L658,458 delayed vibrissal regrowth following whisker removal. These results suggest that γ-secretase may execute important biological functions in many peripheral systems, as in the brain. The development of γ-secretase inhibitors/modulators for AD and cancer therapy should include close monitoring of toxicological panels for hepatic, gastrointestinal, endocrinal and reproductive functions.

  12. Protection of the Photosynthetic Apparatus from Extreme Dehydration and Oxidative Stress in Seedlings of Transgenic Tobacco

    PubMed Central

    Personat, José-María; Tejedor-Cano, Javier; Lindahl, Marika; Diaz-Espejo, Antonio; Jordano, Juan

    2012-01-01

    A genetic program that in sunflower seeds is activated by Heat Shock transcription Factor A9 (HaHSFA9) has been analyzed in transgenic tobacco seedlings. The ectopic overexpression of the HSFA9 program protected photosynthetic membranes, which resisted extreme dehydration and oxidative stress conditions. In contrast, heat acclimation of seedlings induced thermotolerance but not resistance to the harsh stress conditions employed. The HSFA9 program was found to include the expression of plastidial small Heat Shock Proteins that accumulate only at lower abundance in heat-stressed vegetative organs. Photosystem II (PSII) maximum quantum yield was higher for transgenic seedlings than for non-transgenic seedlings, after either stress treatment. Furthermore, protection of both PSII and Photosystem I (PSI) membrane protein complexes was observed in the transgenic seedlings, leading to their survival after the stress treatments. It was also shown that the plastidial D1 protein, a labile component of the PSII reaction center, and the PSI core protein PsaB were shielded from oxidative damage and degradation. We infer that natural expression of the HSFA9 program during embryogenesis may protect seed pro-plastids from developmental desiccation. PMID:23227265

  13. Process for photosynthetically splitting water

    SciTech Connect

    Greenbaum, E.

    1982-01-28

    In one form of the invention, hydrogen is produced by providing a reactor containing a body of water. The water contains photolytic material, i.e., photoactive material containing a hydrogen-catalyst. The interior of the reactor is isolated from atmosphere and includes a volume for receiving gases evolved from the body of water. The photolytic material is exposed to light to effect photosynthetic splitting of the water into gaseous hydrogen and oxygen. The gas-receiving volume is continuously evacuated by pumping to promote evolution of gaseous hydrogen and oxygen into that volume and to withdraw them therefrom. In another form of the invention, separation of the hydrogen and oxygen is effected by selectively diffusing the hydrogen through a heated semipermeable membrane in a separation zone while maintaining across the zone a magnetic field gradient biasing the oxygen away from the membrane. In a third form of the invention, the withdrawn gas is contacted with a membrane blocking flow of water vapor to the region for effecting recovery of the hydrogen. In a fourth embodiment, the invention comprises a process for selectively recovering hydrogen from a gas mixture comprising hydrogen and oxygen. The process is conducted in a separation zone and comprises contacting the mixture with a semipermeable membrane effecting selective diffusion of hydrogen while maintaining across the zone a magnetic field gradient effecting movement of oxygen in a direction away from the membrane.

  14. Scytonemin and Photosynthetic Pigment Proxies for Late Pleistocene/Holocene Environmental Change in the Eastern Great Basin

    NASA Astrophysics Data System (ADS)

    Fulton, J. M.; Van Mooy, B. A. S.

    2015-12-01

    Sedimentary pigments are biomarkers of photosynthetic organisms, most commonly derived from aquatic bacteria and algae but also with potential terrigenous sources. We detected a diverse pigment assemblage with variable down-core distributions in Great Salt Lake (GSL) sediments deposited since ca. 280 ka (GLAD1-GSL00, core 4). The most abundant pigments included derivatives of chlorophyll a, most likely from algae or cyanobacteria, bacteriochlorophyll c from green sulfur bacteria, okenone from purple sulfur bacteria, and scytonemin from UV-exposed cyanobacteria. Scytonemin is a biomarker for colonial cyanobacteria exposed to UV-radiation. In GSL it has potential sources from bioherms on the shoreline or microbiotic soil crusts from the adjacent Great Basin Desert. Scytonemin concentration was highest in the Upper Salt and Sapropel (USS) unit, deposited between 11.5-10 ka in shallow water (ca. 10 m), following deep pluvial Lake Bonneville (30-18 cal ka), the Provo lake level (ca. 18-15 cal ka), and the Gilbert transgression (11.6 cal ka). Scytonemin concentration was very low in sediments deposited during the deep lake phases, even though bioherms were prominent shoreline features. The USS was deposited under hypersaline waters and contained remarkably low concentrations of photosynthetic pigment derivatives that would be expected in organic-matter-rich sediments deposited under productive surface waters or anoxic bottom waters. Stable carbon and nitrogen isotopic data point toward a desert soil crust source for scytonemin in the USS, similar to what we previously observed in the Holocene Black Sea sapropel. We propose that increased aridity supported the widespread occurrence and erosion of microbiotic soil crusts during deposition of the USS. This is consistent with interpretations of Great Salt Lake hydrology, pointing toward a broader regional aridity event. Holocene sediments above the USS also contain scytonemin at relatively high concentration, consistent with

  15. Sources of organic carbon for Rimicaris hybisae: Tracing individual fatty acids at two hydrothermal vent fields in the Mid-Cayman rise

    NASA Astrophysics Data System (ADS)

    Streit, Kathrin; Bennett, Sarah A.; Van Dover, Cindy L.; Coleman, Max

    2015-06-01

    Hydrothermal vents harbor ecosystems mostly decoupled from organic carbon synthesized with the energy of sunlight (photosynthetic carbon source) but fueled instead by oxidation of reduced compounds to generate a chemosynthetic carbon source. Our study aimed to disentangle photosynthetic and chemosynthetic organic carbon sources for the shrimp species Rimicaris hybisae, a primary consumer presumed to obtain its organic carbon mainly from ectosymbiotic chemoautotrophic bacteria living on its gill cover membrane. To provide ectosymbionts with ideal conditions for chemosynthesis, these shrimp live in dense clusters around vent chimneys; they are, however, also found sparsely distributed adjacent to diffuse vent flows, where they might depend on alternative food sources. Densely and sparsely distributed shrimp were sampled and dissected into abdominal tissue and gill cover membrane, covered with ectosymbiotic bacteria, at two hydrothermal vent fields in the Mid-Cayman rise that differ in vent chemistry. Fatty acids (FA) were extracted from shrimp tissues and their carbon isotopic compositions assessed. The FA data indicate that adult R. hybisae predominantly rely on bacteria for their organic carbon needs. Their FA composition is dominated by common bacterial FA of the n7 family (~41%). Bacterial FA of the n4 FA family are also abundant and found to constitute good biomarkers for gill ectosymbionts. Sparsely distributed shrimp contain fractions of n4 FA in gill cover membranes ~4% lower than densely packed ones (~18%) and much higher fractions of photosynthetic FA in abdominal tissues, ~4% more (compared with 1.6%), suggesting replacement of ectosymbionts along with exoskeletons (molt), while they take up alternative diets of partly photosynthetic organic carbon. Abdominal tissues also contain photosynthetic FA from a second source taken up presumably during an early dispersal phase and still present to c. 3% in adult shrimp. The contribution of photosynthetic carbon to

  16. Anaerobic energy metabolism in unicellular photosynthetic eukaryotes.

    PubMed

    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.

  17. N-15 NMR spectra of naturally abundant nitrogen in soil and aquatic natural organic matter samples of the International Humic Substances Society

    USGS Publications Warehouse

    Thorn, K.A.; Cox, L.G.

    2009-01-01

    The naturally abundant nitrogen in soil and aquatic NOM samples from the International Humic Substances Society has been characterized by solid state CP/MAS 15N NMR. Soil samples include humic and fulvic acids from the Elliot soil, Minnesota Waskish peat and Florida Pahokee peat, as well as the Summit Hill soil humic acid and the Leonardite humic acid. Aquatic samples include Suwannee River humic, fulvic and reverse osmosis isolates, Nordic humic and fulvic acids and Pony Lake fulvic acid. Additionally, Nordic and Suwannee River XAD-4 acids and Suwannee River hydrophobic neutral fractions were analyzed. Similar to literature reports, amide/aminoquinone nitrogens comprised the major peaks in the solid state spectra of the soil humic and fulvic acids, along with heterocyclic and amino sugar/terminal amino acid nitrogens. Spectra of aquatic samples, including the XAD-4 acids, contain resolved heterocyclic nitrogen peaks in addition to the amide nitrogens. The spectrum of the nitrogen enriched, microbially derived Pony Lake, Antarctica fulvic acid, appeared to contain resonances in the region of pyrazine, imine and/or pyridine nitrogens, which have not been observed previously in soil or aquatic humic substances by 15N NMR. Liquid state 15N NMR experiments were also recorded on the Elliot soil humic acid and Pony Lake fulvic acid, both to examine the feasibility of the techniques, and to determine whether improvements in resolution over the solid state could be realized. For both samples, polarization transfer (DEPT) and indirect detection (1H-15N gHSQC) spectra revealed greater resolution among nitrogens directly bonded to protons. The amide/aminoquinone nitrogens could also be observed by direct detection experiments.

  18. N-15 NMR spectra of naturally abundant nitrogen in soil and aquatic natural organic matter samples of the International Humic Substances Society

    SciTech Connect

    Thorn, Kevin A.; Cox, Larry G.

    2009-02-28

    The naturally abundant nitrogen in soil and aquatic NOM samples from the International Humic Substances Society has been characterized by solid state CP/MAS ¹⁵N NMR. Soil samples include humic and fulvic acids from the Elliot soil, Minnesota Waskish peat and Florida Pahokee peat, as well as the Summit Hill soil humic acid and the Leonardite humic acid. Aquatic samples include Suwannee River humic, fulvic and reverse osmosis isolates, Nordic humic and fulvic acids and Pony Lake fulvic acid. Additionally, Nordic and Suwannee River XAD-4 acids and Suwannee River hydrophobic neutral fractions were analyzed. Similar to literature reports, amide/aminoquinone nitrogens comprised the major peaks in the solid state spectra of the soil humic and fulvic acids, along with heterocyclic and amino sugar/terminal amino acid nitrogens. Spectra of aquatic samples, including the XAD-4 acids, contain resolved heterocyclic nitrogen peaks in addition to the amide nitrogens. The spectrum of the nitrogen enriched, microbially derived Pony Lake, Antarctica fulvic acid, appeared to contain resonances in the region of pyrazine, imine and/or pyridine nitrogens, which have not been observed previously in soil or aquatic humic substances by ¹⁵N NMR. Liquid state ¹⁵N NMR experiments were also recorded on the Elliot soil humic acid and Pony Lake fulvic acid, both to examine the feasibility of the techniques, and to determine whether improvements in resolution over the solid state could be realized. For both samples, polarization transfer (DEPT) and indirect detection (¹H–¹⁵N gHSQC) spectra revealed greater resolution among nitrogens directly bonded to protons. The amide/aminoquinone nitrogens could also be observed by direct detection experiments.

  19. Effects of earthworms and plants on the soil structure, the physical stabilization of soil organic matter and the microbial abundance and diversity in soil aggregates in a long term study

    NASA Astrophysics Data System (ADS)

    Zangerlé, Anne; Hissler, Christophe; Lavelle, Patrick

    2014-05-01

    Earthworms and plant roots, as ecosystem engineers, have large effects on biotic and abiotic properties of the soil system. They create biogenic soil macroaggregates (i.e. earthworm casts and root macroaggregates) with specific physical, chemical and microbiological properties. Research to date has mainly considered their impacts in isolation thereby ignoring potential interactions between these organisms. On the other hand, most of the existing studies focused on short to midterm time scale. We propose in this study to consider effect of earthworms and plants on aggregate dynamics at long time scale. A 24 months macrocosm experiment, under semi-controlled conditions, was conducted to assess the impacts of corn and endogeic plus anecic earthworms (Apporectodea caliginosa and Lumbricus terrestris) on soil structure, C stabilization and microbial abundance and biodiversity. Aggregate stability was assessed by wet-sieving. Macroaggregates (>2 mm) were also visually separated according to their biological origin (e.g., earthworms, roots). Total C and N contents were measured in aggregates of all size classes and origins. Natural abundances of 13C of corn, a C4 plant, were used as a supplemental marker of OM incorporation in aggregates. The genetic structure and the abundance of the bacterial and fungal communities were characterized by using respectively the B- and F-ARISA fingerprinting approach and quantitative PCR bacteria (341F/515R) and fungi (FF330/FR1). They significantly impacted the soil physical properties in comparison to the other treatments: lower bulk density in the first 10cm of the soil with 0.95 g/cm3 in absence of corn plants and 0.88 g/cm3 in presence of corn plants compared to control soil (1.21g/cm3). The presence of earthworms increased aggregate stability (mean weight diameter) by 7.6 %, while plants alone had no simple impacts on aggregation. A significant interaction revealed that earthworms increased aggregate stability in the presence of

  20. cPPB-aE is discovered from photosynthetic benthic dinoflagellates.

    PubMed

    Yamada, Norico; Tanaka, Ayumi; Horiguchi, Takeo

    2014-02-01

    Although chlorophyll degradation pathways in higher plants have been well studied, little is known about the mechanisms of chlorophyll degradation in microalgae. In this article, we report the occurrence of a chlorophyll a derivative that has never been discovered in photosynthetic organisms. This chlorophyll derivative emits no fluorescence and has a peculiar absorbance peak at 425, 451, 625, and 685 nm. From these features, it was identified as 13(2) ,17(3) -cyclopheophorbide a enol (cPPB-aE), reported as a degradation product of chlorophyll a derived from prey algal cells in heterotrophic protists. We discovered cPPB-aE in six benthic photosynthetic dinoflagellates that are phylogenetically separated into four clades based on SSU rDNA molecular phylogeny. This is the first report of this chlorophyll derivative in photosynthetic organisms and we suggest that the derivative is used to quench excess light energy.

  1. Evidence for only minor contributions from bacteria to sedimentary organic carbon

    NASA Technical Reports Server (NTRS)

    Hartgers, W. A.; Sinninghe Damste, J. S.; Requejo, A. G.; Allan, J.; Hayes, J. M.; de Leeuw, J. W.

    1994-01-01

    Because their molecular signatures are often prominent in extracts of sediments, bacteria are thought to be important contributors to petroleum source beds. It has been shown recently, however, that abundances of biomarkers do not always reflect relative contributions to sedimentary organic carbon (Corg). The contribution of photosynthetic green sulphur bacteria to sediments can be assessed effectively because the diagenetic products of distinctive carotenoids from these organisms occur widely and their biomass is isotopically labelled, being enriched in 13C. We show here that, although sediments and oils from the Western Canada and Williston basins contain prominent biomarkers of photosynthetic bacteria, the absence of 13C enrichment in the total Corg requires that the bacterial contribution is in fact minimal. Although the importance of bacterial reworking of sedimentary debris cannot be doubted, we argue that our findings, when considered in conjunction with those from other settings, suggest that bacterial biomass may commonly represent only a minor component of total Corg in carbonaceous rocks.

  2. Evidence for only minor contributions from bacteria to sedimentary organic carbon.

    PubMed

    Hartgers, W A; Sinninghe Damste, J S; Requejo, A G; Allan, J; Hayes, J M; de Leeuw, J W

    1994-05-19

    Because their molecular signatures are often prominent in extracts of sediments, bacteria are thought to be important contributors to petroleum source beds. It has been shown recently, however, that abundances of biomarkers do not always reflect relative contributions to sedimentary organic carbon (Corg). The contribution of photosynthetic green sulphur bacteria to sediments can be assessed effectively because the diagenetic products of distinctive carotenoids from these organisms occur widely and their biomass is isotopically labelled, being enriched in 13C. We show here that, although sediments and oils from the Western Canada and Williston basins contain prominent biomarkers of photosynthetic bacteria, the absence of 13C enrichment in the total Corg requires that the bacterial contribution is in fact minimal. Although the importance of bacterial reworking of sedimentary debris cannot be doubted, we argue that our findings, when considered in conjunction with those from other settings, suggest that bacterial biomass may commonly represent only a minor component of total Corg in carbonaceous rocks.

  3. Insect herbivory and photosynthetic pathways in old-field ecosystems

    SciTech Connect

    Pinder, J.E. III; Kroh, G.C.

    1987-04-01

    Three old-field communities of varying composition near Aiken, South Carolina, were used to test the hypothesis that phytophagous insects avoid consuming plants possessing the C/sub 4/ photosynthetic pathway and consume plants that possess only the C/sub 3/ pathway. The relative abundances of stable carbon isotopes in insect tissues, which indicate consumption of C/sub 3/ or C/sub 4/ plants, were used to determine if insects were consuming C/sub 3/ and C/sub 4/ plants in proportion to their abundance in the plant community. In one community, the carbon isotope ratio for insects was significantly less than that expected for proportional consumption and indicated avoidance of C/sub 4/ species. Insect consumption of C/sub 4/ plants was approx. = 50% of that expected if insects were consuming C/sub 3/ and C/sub 4/ plants in proportion to their abundance. In the other two communities, the differences between observed and expected isotopic ratios were not significant. Levels of insect consumption of C/sub 4/ plants in these two communities were, respectively, approx. = 82% and approx. = 126% of those expected for proportional consumption. The results suggest that the degree of avoidance varies among plant communities.

  4. A geographic information system on the potential distribution and abundance of Fasciola hepatica and F. gigantica in east Africa based on Food and Agriculture Organization databases.

    PubMed

    Malone, J B; Gommes, R; Hansen, J; Yilma, J M; Slingenberg, J; Snijders, F; Nachtergaele, F; Ataman, E

    1998-07-31

    distribution range of the two Fasciola species, regional variations in intensity and seasonal transmission patterns at different sites. Results further indicate that many of the methods used for crop productivity models can also be used to define the potential distribution and abundance of parasites.

  5. Solar abundance of osmium

    PubMed Central

    Jacoby, George; Aller, Lawrence H.

    1976-01-01

    The abundance parameter, log gfA, where g is the statistical weight of the lower level, f is the oscillator strength, and A is the abundance (by numbers of atoms with respect to hydrogen), has been derived for three lines of osmium by a method of spectrum synthesis. An apparent discordance of the derived abundance with that found from the carbonaceous chondrites is probably to be attributed primarily to errors in the f-values, and blending with unknown contributors. PMID:16592314

  6. PS2013 Satellite Workshop on Photosynthetic Light-Harvesting Systems

    SciTech Connect

    Niederman, Robert A.; Blankenship, Robert E.; Frank, Harry A.

    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

  7. Prioritization of copper for the use in photosynthetic electron transport in developing leaves of hybrid poplar

    PubMed Central

    Shahbaz, Muhammad; Ravet, Karl; Peers, Graham; Pilon, Marinus

    2015-01-01

    Plastocyanin (PC) is an essential and abundant copper (Cu) 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 PC. The Cu-microRNAs, which are up-regulated under Cu deficiency, down-regulate the expression of target Cu proteins other than PC, cytochrome-c oxidase and the ethylene receptors. It has been proposed that this mechanism saves Cu for PC 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 PC protein levels. Compared to older leaves, PC 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 PC. 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 PC in younger leaves, which is supported by Cu-microRNA expression. PMID:26089828

  8. High Efficiency Light Harvesting by Carotenoids in the LH2 Complex from Photosynthetic Bacteria: Unique Adaptation to Growth under Low-Light Conditions

    PubMed Central

    2015-01-01

    Rhodopin, rhodopinal, and their glucoside derivatives are carotenoids that accumulate in different amounts in the photosynthetic bacterium, Rhodoblastus (Rbl.) acidophilus strain 7050, depending on the intensity of the light under which the organism is grown. The different growth conditions also have a profound effect on the spectra of the bacteriochlorophyll (BChl) pigments that assemble in the major LH2 light-harvesting pigment–protein complex. Under high-light conditions the well-characterized B800-850 LH2 complex is formed and accumulates rhodopin and rhodopin glucoside as the primary carotenoids. Under low-light conditions, a variant LH2, denoted B800-820, is formed, and rhodopinal and rhodopinal glucoside are the most abundant carotenoids. The present investigation compares and contrasts the spectral properties and dynamics of the excited states of rhodopin and rhodopinal in solution. In addition, the systematic differences in pigment composition and structure of the chromophores in the LH2 complexes provide an opportunity to explore the effect of these factors on the rate and efficiency of carotenoid-to-BChl energy transfer. It is found that the enzymatic conversion of rhodopin to rhodopinal by Rbl. acidophilus 7050 grown under low-light conditions results in nearly 100% carotenoid-to-BChl energy transfer efficiency in the LH2 complex. This comparative analysis provides insight into how photosynthetic systems are able to adapt and survive under challenging environmental conditions. PMID:25171303

  9. High efficiency light harvesting by carotenoids in the LH2 complex from photosynthetic bacteria: unique adaptation to growth under low-light conditions.

    PubMed

    Magdaong, Nikki M; LaFountain, Amy M; Greco, Jordan A; Gardiner, Alastair T; Carey, Anne-Marie; Cogdell, Richard J; Gibson, George N; Birge, Robert R; Frank, Harry A

    2014-09-25

    Rhodopin, rhodopinal, and their glucoside derivatives are carotenoids that accumulate in different amounts in the photosynthetic bacterium, Rhodoblastus (Rbl.) acidophilus strain 7050, depending on the intensity of the light under which the organism is grown. The different growth conditions also have a profound effect on the spectra of the bacteriochlorophyll (BChl) pigments that assemble in the major LH2 light-harvesting pigment-protein complex. Under high-light conditions the well-characterized B800-850 LH2 complex is formed and accumulates rhodopin and rhodopin glucoside as the primary carotenoids. Under low-light conditions, a variant LH2, denoted B800-820, is formed, and rhodopinal and rhodopinal glucoside are the most abundant carotenoids. The present investigation compares and contrasts the spectral properties and dynamics of the excited states of rhodopin and rhodopinal in solution. In addition, the systematic differences in pigment composition and structure of the chromophores in the LH2 complexes provide an opportunity to explore the effect of these factors on the rate and efficiency of carotenoid-to-BChl energy transfer. It is found that the enzymatic conversion of rhodopin to rhodopinal by Rbl. acidophilus 7050 grown under low-light conditions results in nearly 100% carotenoid-to-BChl energy transfer efficiency in the LH2 complex. This comparative analysis provides insight into how photosynthetic systems are able to adapt and survive under challenging environmental conditions.

  10. ENHANCED PRACTICAL PHOTOSYNTHETIC CO2 MITIGATION

    SciTech Connect

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

    2002-10-15

    This report documents significant achievements in the Enhanced Practical Photosynthetic CO{sub 2} Mitigation project during the period from 10/2/2001 through 10/01/2002. This report marks the end of year 2 of a three-year project as well as the milestone date for completion of Phase I activities. This report includes our current status and defines the steps being taken to ensure that we meet the project goals by the end of year 3. As indicated in the list of accomplishments below our current efforts are focused on evaluating candidate organisms and growth surfaces, preparing to conduct long-term tests in the bench-scale bioreactor test systems, and scaling-up the test facilities from bench scale to pilot scale. Specific results and accomplishments for the third quarter of 2002 include: Organisms and Growth Surfaces: (1) Test results continue to indicate that thermophilic cyanobacteria have significant advantages as agents for practical photosynthetic CO{sub 2} mitigation before mesophilic forms. (2) Additional thermal features with developed cyanobacterial mats, which might be calcium resistant, were found in YNP. (3) Back to back tests show that there is no detectable difference in the growth of isolate 1.2 s.c. (2) in standard and Ca-modified BG-11 medium. The doubling time for both cases was about 12 hours. (4) The cultivation of cyanobacteria in Ca-BG medium should proceed in the pH range between 7 and 7.4, but this suggestion requires additional experiments. (5) Cyanobacteria can be grown in media where sodium is present at trace levels. (6) Ca{sup 2+} enriched medium can be used as a sink for CO{sub 2} under alkaline conditions. (7) Cyanobacteria are able to generate cones of filaments on travertine surfaces. [Travertine is a mixture of CaCO{sub 3} and CaSO{sub 4}]. We hypothesize that SO{sub 4}{sup 2-} stimulates the generation of such cones, because they are not almost generated on CaCO3 surface. On the other hand, we know that plant gas contains elevated

  11. Detection and structural identification of dissolved organic matter in Antarctic glacial ice at natural abundance by SPR-W5-WATERGATE 1H NMR spectroscopy.

    PubMed

    Pautler, Brent G; Simpson, André J; Simpson, Myrna J; Tseng, Li-Hong; Spraul, Manfred; Dubnick, Ashley; Sharp, Martin J; Fitzsimons, Sean J

    2011-06-01

    Dissolved organic matter (DOM) is ubiquitous in aquatic ecosystems and is derived from various inputs that control its turnover. Glaciers and ice sheets are the second largest water reservoir in the global hydrologic cycle, but little is known about glacial DOM composition or contributions to biogeochemical cycling. Here we employ SPR-W5-WATERGATE (1)H NMR spectroscopy to elucidate and quantify the chemical structures of DOM constituents in Antarctic glacial ice as they exist in their natural state (average DOC of 8 mg/L) without isolation or preconcentration. This Antarctic glacial DOM is predominantly composed of a mixture of small recognizable molecules differing from DOM in marine, lacustrine, and other terrestrial environments. The major constituents detected in three distinct types of glacial ice include lactic and formic acid, free amino acids, and a mixture of simple sugars and amino sugars with concentrations that vary between ice types. The detection of free amino acid and amino sugar monomer components of peptidoglycan within the ice suggests that Antarctic glacial DOM likely originates from in situ microbial activity. As these constituents are normally considered to be biologically labile (fast cycling) in nonglacial environments, accelerated glacier melt and runoff may result in a flux of nutrients into adjacent ecosystems.

  12. Oxygen concentration inside a functioning photosynthetic cell.

    PubMed

    Kihara, Shigeharu; Hartzler, Daniel A; Savikhin, Sergei

    2014-05-01

    The excess oxygen concentration in the photosynthetic membranes of functioning oxygenic photosynthetic cells was estimated using classical diffusion theory combined with experimental data on oxygen production rates of cyanobacterial cells. The excess oxygen concentration within the plesiomorphic cyanobacterium Gloeobactor violaceus is only 0.025 μM, or four orders of magnitude lower than the oxygen concentration in air-saturated water. Such a low concentration suggests that the first oxygenic photosynthetic bacteria in solitary form could have evolved ∼2.8 billion years ago without special mechanisms to protect them against reactive oxygen species. These mechanisms instead could have been developed during the following ∼500 million years while the oxygen level in the Earth's atmosphere was slowly rising. Excess oxygen concentrations within individual cells of the apomorphic cyanobacteria Synechocystis and Synechococcus are 0.064 and 0.25 μM, respectively. These numbers suggest that intramembrane and intracellular proteins in isolated oxygenic photosynthetic cells are not subjected to excessively high oxygen levels. The situation is different for closely packed colonies of photosynthetic cells. Calculations show that the excess concentration within colonies that are ∼40 μm or larger in diameter can be comparable to the oxygen concentration in air-saturated water, suggesting that species forming colonies require protection against reactive oxygen species even in the absence of oxygen in the surrounding atmosphere.

  13. Enhanced Practical Photosynthetic CO2 Mitigation

    SciTech Connect

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

    2003-10-15

    This quarterly report documents significant achievements in the Enhanced Practical Photosynthetic CO{sub 2} Mitigation project during the period from 7/2/2003 through 10/01/2003. As indicated in the list of accomplishments below we are preparing for the final tests necessary to meet our project goals. Specific results and accomplishments for the third quarter of 2003 include: (1) Bioreactor support systems and test facilities: (A) The solar collector used in the light delivery system showed signs of degradation and hence had to be replaced by ORNL. A set of light readings were taken after the new solar collector was installed. The readings showed an acceptable light profile. (B) 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. The improvements have been completed and the system is ready for testing. (C) The pilot scale bioreactor is ready for testing pending some information from the CRF-2 tests. (2) Organisms and Growth Surfaces: (A) The shape of the Chlorogloeopsis sp. cells (cyanobacteria) was found to be affected by environmental pH, which may be useful in culture quality control. Besides, the further investigation of this phenomenon suggested that the rate of cell adhesion to glass surface decreases upon medium alkalinization. Thus, harvesting effectiveness may be improved by increasing medium pH up to 9 before harvesting of cyanobacteria from a substratum.

  14. ENHANCED PRACTICAL PHOTOSYNTHETIC CO2 MITIGATION

    SciTech Connect

    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

  15. Short-term effects of tillage practices on soil organic carbon turnover assessed by δ13C abundance in particle-size fractions of black soils from northeast China.

    PubMed

    Liang, Aizhen; Chen, Shenglong; Zhang, Xiaoping; Chen, Xuewen

    2014-01-01

    The combination of isotope trace technique and SOC fractionation allows a better understanding of SOC dynamics. A five-year tillage experiment consisting of no-tillage (NT) and mouldboard plough (MP) was used to study the changes in particle-size SOC fractions and corresponding δ (13)C natural abundance to assess SOC turnover in the 0-20 cm layer of black soils under tillage practices. Compared to the initial level, total SOC tended to be stratified but showed a slight increase in the entire plough layer under short-term NT. MP had no significant impacts on SOC at any depth. Because of significant increases in coarse particulate organic carbon (POC) and decreases in fine POC, total POC did not remarkably decrease under NT and MP. A distinct increase in silt plus clay OC occurred in NT plots, but not in MP plots. However, the δ (13)C abundances of both coarse and fine POC increased, while those of silt plus clay OC remained almost the same under NT. The C derived from C3 plants was mainly associated with fine particles and much less with coarse particles. These results suggested that short-term NT and MP preferentially enhanced the turnover of POC, which was considerably faster than that of silt plus clay OC. PMID:25162052

  16. BOREAS TE-10 Photosynthetic Response Data

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Papagno, Andrea (Editor); Middleton, Elizabeth; Sullivan, Joseph

    2000-01-01

    The Boreal Ecosystem-Atmospheric Study (BOREAS) TE-10 (Terrestrial Ecology) team collected several data sets in support of its efforts to characterize and interpret information on the gas exchange, reflectance, transmittance, chlorophyll content, carbon content, hydrogen content, nitrogen content, and photosynthetic response of boreal vegetation. This data set contains measurements of quantitative parameters and leaf photosynthetic response to increases in light conducted in the SSA during the growing seasons of 1994 and 1996 using an oxygen electrode system. Leaf photosynthetic responses were not collected in 1996. The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

  17. Toward a photosynthetic microbial platform for terpenoid engineering.

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  19. Photosynthetic responses and accumulation of mesotrione in two freshwater algae.

    PubMed

    Ni, Yan; Lai, Jinhu; Wan, Jinbao; Chen, Lianshui

    2014-01-01

    Mesotrione is a herbicide used for killing annual grasses and broad-leaved weeds in maize. A recent investigation has shown that mesotrione has been detected as an organic contaminant in aquatic environments and may have a negative impact on aquatic organisms. To evaluate the eco-toxicity of mesotrione to algae, experiments focusing on photosynthetic responses and mesotrione accumulation in Microcystis sp. and Scenedesmus quadricauda were carried out. Both algae treated with mesotrione at 0.05-10 mg L(-1) for 7 days reduced the photosynthetic capacity. The fluorescence of chlorophyll a, the maximal PSII activity (Fv/Fm), and the parameters (Ik, α and ETRmax) of rapid light curves (RLCs) in both algae were decreased under mesotrione exposure. The 96 h EC50 values for mesotrione on S. quadricauda and Microcystis sp. were 4.41 and 6.19 mg L(-1), respectively. The latter shows more tolerance to mesotrione. Mesotrione was shown to be readily accumulated by both species. Such uptake of mesotrione led to the rapid removal of mesotrione from the medium. Overall, this study represents the initial comprehensive analyses of Microcystis sp. and S. quadricauda in adaptation to the mesotrione contaminated aquatic ecosystems. PMID:25059419

  20. Toward a photosynthetic microbial platform for terpenoid engineering.

    PubMed

    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. PMID:24510550

  1. Design criteria for optimal photosynthetic energy conversion

    NASA Astrophysics Data System (ADS)

    Fingerhut, Benjamin P.; Zinth, Wolfgang; de Vivie-Riedle, Regina

    2008-12-01

    Photochemical solar energy conversion is considered as an alternative of clean energy. For future light converting nano-machines photosynthetic reaction centers are used as prototypes optimized during evolution. We introduce a reaction scheme for global optimization and simulate the ultrafast charge separation in photochemical energy conversion. Multiple molecular charge carriers are involved in this process and are linked by Marcus-type electron transfer. In combination with evolutionary algorithms, we unravel the biological strategies for high quantum efficiency in photosynthetic reaction centers and extend these concepts to the design of artificial photochemical devices for energy conversion.

  2. ENHANCED PRACTICAL PHOTOSYNTHETIC CO2 MITIGATION

    SciTech Connect

    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 factors, most significantly the

  3. ENHANCED PRACTICAL PHOTOSYNTHETIC CO2 MITIGATION

    SciTech Connect

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

    2002-04-15

    This quarterly report documents significant achievements in the Enhanced Practical Photosynthetic CO{sub 2} Mitigation project during the period from 1/3/2001 through 4/02/2002. 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, we are continuing to evaluate candidate organisms and growth surfaces, and we are expanding the test facilities in preparation for scaled up system-level testing. Specific results and accomplishments for the first quarter of 2002 include: Organisms and Growth Surfaces: (1) Isolate 1.2 s.c. (2) has been selected for further investigations because of its favorable growth properties. (2) Research on optimal conditions for the growth of cyanobacterial isolates from YNP should be carried out using distilled water which has more stable chemical parameters, although tap water use may be permissible during full scale operations (at the cost of longer organism doubling times). (3) Tr. 9.4 WF is able to generate a biofilm on an Omnisil surface. Over the long term Omnisil does not inhibit the growth of TR 9.4 isolate, though it does elongate the lag phase of growth of this isolate. (4) Initial survivability tests for the TR 9.4 organism on Omnisil screens in the CRF2 modelscale bioreactor are underway. We have experienced problems keeping the organisms alive for more than three days, but we are currently investigating several possible causes for this unexpected result. (5) Accelerated materials testing have shown that Omnisil fabric has acceptable strength properties for use in a practical bioreactor system. Bioreactor support systems and test facilities: (1) Several CO{sub 2} scrubbing experiments have been completed in the translating slug flow test system, however the error introduced by the

  4. Microfluidic high-throughput selection of microalgal strains with superior photosynthetic productivity using competitive phototaxis.

    PubMed

    Kim, Jaoon Young Hwan; Kwak, Ho Seok; Sung, Young Joon; Choi, Hong Il; Hong, Min Eui; Lim, Hyun Seok; Lee, Jae-Hyeok; Lee, Sang Yup; Sim, Sang Jun

    2016-02-08

    Microalgae possess great potential as a source of sustainable energy, but the intrinsic inefficiency of photosynthesis is a major challenge to realize this potential. Photosynthetic organisms evolved phototaxis to find optimal light condition for photosynthesis. Here we report a microfluidic screening using competitive phototaxis of the model alga, Chlamydomonas reinhardtii, for rapid isolation of strains with improved photosynthetic efficiencies. We demonstrated strong relationship between phototaxis and photosynthetic efficiency by quantitative analysis of phototactic response at the single-cell level using a microfluidic system. Based on this positive relationship, we enriched the strains with improved photosynthetic efficiency by isolating cells showing fast phototactic responses from a mixture of 10,000 mutants, thereby greatly improving selection efficiency over 8 fold. Among 147 strains isolated after screening, 94.6% showed improved photoautotrophic growth over the parental strain. Two mutants showed much improved performances with up to 1.9- and 8.1-fold increases in photoautotrophic cell growth and lipid production, respectively, a substantial improvement over previous approaches. We identified candidate genes that might be responsible for fast phototactic response and improved photosynthesis, which can be useful target for further strain engineering. Our approach provides a powerful screening tool for rapid improvement of microalgal strains to enhance photosynthetic productivity.

  5. Microfluidic high-throughput selection of microalgal strains with superior photosynthetic productivity using competitive phototaxis

    PubMed Central

    Kim, Jaoon Young Hwan; Kwak, Ho Seok; Sung, Young Joon; Choi, Hong Il; Hong, Min Eui; Lim, Hyun Seok; Lee, Jae-Hyeok; Lee, Sang Yup; Sim, Sang Jun

    2016-01-01

    Microalgae possess great potential as a source of sustainable energy, but the intrinsic inefficiency of photosynthesis is a major challenge to realize this potential. Photosynthetic organisms evolved phototaxis to find optimal light condition for photosynthesis. Here we report a microfluidic screening using competitive phototaxis of the model alga, Chlamydomonas reinhardtii, for rapid isolation of strains with improved photosynthetic efficiencies. We demonstrated strong relationship between phototaxis and photosynthetic efficiency by quantitative analysis of phototactic response at the single-cell level using a microfluidic system. Based on this positive relationship, we enriched the strains with improved photosynthetic efficiency by isolating cells showing fast phototactic responses from a mixture of 10,000 mutants, thereby greatly improving selection efficiency over 8 fold. Among 147 strains isolated after screening, 94.6% showed improved photoautotrophic growth over the parental strain. Two mutants showed much improved performances with up to 1.9- and 8.1-fold increases in photoautotrophic cell growth and lipid production, respectively, a substantial improvement over previous approaches. We identified candidate genes that might be responsible for fast phototactic response and improved photosynthesis, which can be useful target for further strain engineering. Our approach provides a powerful screening tool for rapid improvement of microalgal strains to enhance photosynthetic productivity. PMID:26852806

  6. Engineering of cyanobacteria for the photosynthetic production of limonene from CO2.

    PubMed

    Kiyota, Hiroshi; Okuda, Yukiko; Ito, Michiho; Hirai, Masami Yokota; Ikeuchi, Masahiko

    2014-09-20

    Isoprenoids, major secondary metabolites in many organisms, are utilized in various applications. We constructed a model photosynthetic production system for limonene, a volatile isoprenoid, using a unicellular cyanobacterium that expresses the plant limonene synthase. This system produces limonene photosynthetically at a nearly constant rate and that can be efficiently recovered using a gas-stripping method. This production does not affect the growth of the cyanobacteria and is markedly enhanced by overexpression of three enzymes in the intrinsic pathway to provide the precursor of limonene, geranyl pyrophosphate. The photosynthetic production of limonene in our system is more or less sustained from the linear to stationary phase of cyanobacterial growth for up to 1 month.

  7. Photosynthetic potential of planets in 3 : 2 spin-orbit resonances

    NASA Astrophysics Data System (ADS)

    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.

  8. Contributions of photosynthetic and non-photosynthetic cell types to leaf respiration in Vicia faba L. and their responses to growth temperature.

    PubMed

    Long, Benedict M; Bahar, Nur H A; Atkin, Owen K

    2015-11-01

    In intact leaves, mitochondrial populations are highly heterogeneous among contrasting cell types; how such contrasting populations respond to sustained changes in the environment remains, however, unclear. Here, we examined respiratory rates, mitochondrial protein composition and response to growth temperature in photosynthetic (mesophyll) and non-photosynthetic (epidermal) cells from fully expanded leaves of warm-developed (WD) and cold-developed (CD) broad bean (Vicia faba L.). Rates of respiration were significantly higher in mesophyll cell protoplasts (MCPs) than epidermal cell protoplasts (ECPs), with both protoplast types exhibiting capacity for cytochrome and alternative oxidase activity. Compared with ECPs, MCPs contained greater relative quantities of porin, suggesting higher mitochondrial surface area in mesophyll cells. Nevertheless, the relative quantities of respiratory proteins (normalized to porin) were similar in MCPs and ECPs, suggesting that ECPs have lower numbers of mitochondria yet similar protein complement to MCP mitochondria (albeit with lower abundance serine hydroxymethyltransferase). Several mitochondrial proteins (both non-photorespiratory and photorespiratory) exhibited an increased abundance in response to cold in both protoplast types. Based on estimates of individual protoplast respiration rates, combined with leaf cell abundance data, epidermal cells make a small but significant (2%) contribution to overall leaf respiration which increases twofold in the cold. Taken together, our data highlight the heterogeneous nature of mitochondrial populations in leaves, both among contrasting cell types and in how those populations respond to growth temperature.

  9. Comparison of abundances, compositions and sources of elements, inorganic ions and organic compounds in atmospheric aerosols from Xi'an and New Delhi, two megacities in China and India.

    PubMed

    Li, Jianjun; Wang, Gehui; Aggarwal, Shankar G; Huang, Yao; Ren, Yanqin; Zhou, Bianhong; Singh, Khem; Gupta, Prabhat K; Cao, Junji; Zhang, Rong

    2014-04-01

    Wintertime TSP samples collected in the two megacities of Xi'an, China and New Delhi, India were analyzed for elements, inorganic ions, carbonaceous species and organic compounds to investigate the differences in chemical compositions and sources of organic aerosols. The current work is the first time comparing the composition of urban organic aerosols from China and India and discussing their sources in a single study. Our results showed that the concentrations of Ca, Fe, Ti, inorganic ions, EC, PAHs and hopanes in Xi'an are 1.3-2.9 times of those in New Delhi, which is ascribed to the higher emissions of dust and coal burning in Xi'an. In contrast, Cl(-), levoglucosan, n-alkanes, fatty alcohols, fatty acids, phthalates and bisphenol A are 0.4-3.0 times higher in New Delhi than in Xi'an, which is attributed to strong emissions from biomass burning and solid waste incineration. PAHs are carcinogenic while phthalates and bisphenol A are endocrine disrupting. Thus, the significant difference in chemical compositions of the above TSP samples may suggest that residents in Xi'an and New Delhi are exposed to environmental hazards that pose different health risks. Lower mass ratios of octadecenoic acid/octadecanoic acid (C18:1/C18:0) and benzo(a)pyrene/benzo(e)pyrene (BaP/BeP) demonstrate that aerosol particles in New Delhi are photochemically more aged. Mass closure reconstructions of the wintertime TSP indicate that crustal material is the most abundant component of ambient particles in Xi'an and New Delhi, accounting for 52% and 48% of the particle masses, respectively, followed by organic matter (24% and 23% in Xi'an and New Delhi, respectively) and secondary inorganic ions (sulfate, nitrate plus ammonium, 16% and 12% in Xi'an and New Delhi, respectively). PMID:24496022

  10. OXYGEN ABUNDANCES IN CEPHEIDS

    SciTech Connect

    Luck, R. E.; Andrievsky, S. M.; Korotin, S. N.; Kovtyukh, V. V. E-mail: serkor@skyline.od.ua E-mail: scan@deneb1.odessa.ua

    2013-07-01

    Oxygen abundances in later-type stars, and intermediate-mass stars in particular, are usually determined from the [O I] line at 630.0 nm, and to a lesser extent, from the O I triplet at 615.7 nm. The near-IR triplets at 777.4 nm and 844.6 nm are strong in these stars and generally do not suffer from severe blending with other species. However, these latter two triplets suffer from strong non-local thermodynamic equilibrium (NLTE) effects and thus see limited use in abundance analyses. In this paper, we derive oxygen abundances in a large sample of Cepheids using the near-IR triplets from an NLTE analysis, and compare those abundances to values derived from a local thermodynamic equilibrium (LTE) analysis of the [O I] 630.0 nm line and the O I 615.7 nm triplet as well as LTE abundances for the 777.4 nm triplet. All of these lines suffer from line strength problems making them sensitive to either measurement complications (weak lines) or to line saturation difficulties (strong lines). Upon this realization, the LTE results for the [O I] lines and the O I 615.7 nm triplet are in adequate agreement with the abundance from the NLTE analysis of the near-IR triplets.

  11. Interstellar Abundance Standards Revisited

    NASA Astrophysics Data System (ADS)

    Sofia, Ulysses J.; Meyer, David M.

    2001-06-01

    We evaluate the stellar abundances often used to represent the total (gas plus dust) composition of the interstellar medium. Published abundances for B stars, young later type (F and G) stars, and the Sun are compared to the modeled dust-phase and measured gas-phase compositions of the interstellar medium. This study uses abundances for the five most populous elements in dust grains-C, O, Mg, Si, and Fe-and the cosmically abundant element, N. We find that B stars have metal abundances that are too low to be considered valid representations of the interstellar medium. The commonly invoked interstellar standard that is two-thirds of the solar composition is also rejected by recent observations. Young (<=2 Gyr) F and G disk stars and the Sun, however, cannot be ruled out as reliable proxies for the total interstellar composition. If their abundances are valid representations of the interstellar medium, then the apparent underabundance of carbon with respect to that required by dust models, i.e., the carbon crisis, is substantially eased.

  12. Microbial abundance and community in subsurface flow constructed wetland microcosms: role of plant presence.

    PubMed

    Wang, Qian; Xie, Huijun; Ngo, Huu Hao; Guo, Wenshan; Zhang, Jian; Liu, Cui; Liang, Shuang; Hu, Zhen; Yang, Zhongchen; Zhao, Congcong

    2016-03-01

    In this research, the role of plants in improving microorganism growth conditions in subsurface flow constructed wetland (CW) microcosms was determined. In particular, microbial abundance and community were investigated during summer and winter in Phragmites australis-planted CW microcosms (PA) and unplanted CW microcosms (control, CT). Results revealed that the removal efficiencies of pollutants and microbial community structure varied in winter with variable microbial abundance. During summer, PA comprised more dominant phyla (e.g., Proteobacteria, Actinobacteria, and Bacteroidetes), whereas CT contained more Cyanobacteria and photosynthetic bacteria. During winter, the abundance of Proteobacteria was >40 % in PA but dramatically decreased in CT. Moreover, Cyanobacteria and photosynthetic bacterial dominance in CT decreased. In both seasons, bacteria were more abundant in root surfaces than in sand. Plant presence positively affected microbial abundance and community. The potential removal ability of CT, in which Cyanobacteria and photosynthetic bacteria were abundant during summer, was more significantly affected by temperature reduction than that of PA with plant presence. PMID:25772872

  13. Origin and evolution of photosynthetic reaction centers

    NASA Astrophysics Data System (ADS)

    Olson, John M.; Pierson, Beverly K.

    1987-09-01

    The prototype reaction center may have used protoporphyrin-IX associated with small peptides to transfer electrons or protons across the primitive cell membrane. The precursor of all contemporary reaction centers contained chlorophylla molecules as both primary electron donor and initial electron acceptor and an Fe-S center as secondary acceptor (RC-1 type). The biosynthetic pathway for chlorophylla evolved along with the evolution of a better organized reaction center associated with cytochromes and quinones in a primitive cyclic electron transport system. This reaction center probably functioned initially in photoassimilation, but was easily adapted to CO2 fixation using H2 and H2S as reductants. During this phase bacteriochlorophyllg may have evolved from chlorophylla in response to competition for light, and thereby initiated the gram-positive line of eubacteria. A second reaction center (RC-2) evolved from RC-1 between 3.5 and 2.5 Ga ago in response to the competition for reductants for CO2 fixation. The new organism containing RC-2 in series with RC-1 would have been able to use poor reducing agents such as the abundant aqueous ferrous ion in place of H2 and H2S. This new organism is proposed to be the common ancestor of all phototrophic eubacteria except those related to the gram-positive bacteria. All organisms containing bacteriochlorophylla lost either RC-1 or RC-2, while those organisms containing chlorophylla (ancestors of cyanobacteria) added a water-splitting enzyme to RC-2 between 3.0 and 2.5 Ga ago in order to use H2O in place of hydrated ferrous ion as electron donor for autotrophic photosynthesis.

  14. Adaptation and Acclimation of Photosynthetic Microorganisms to Permanently Cold Environments

    PubMed Central

    Morgan-Kiss, Rachael M.; Priscu, John C.; Pocock, Tessa; Gudynaite-Savitch, Loreta; Huner, Norman P. A.

    2006-01-01

    Persistently cold environments constitute one of our world's largest ecosystems, and microorganisms dominate the biomass and metabolic activity in these extreme environments. The stress of low temperatures on life is exacerbated in organisms that rely on photoautrophic production of organic carbon and energy sources. Phototrophic organisms must coordinate temperature-independent reactions of light absorption and photochemistry with temperature-dependent processes of electron transport and utilization of energy sources through growth and metabolism. Despite this conundrum, phototrophic microorganisms thrive in all cold ecosystems described and (together with chemoautrophs) provide the base of autotrophic production in low-temperature food webs. Psychrophilic (organisms with a requirement for low growth temperatures) and psychrotolerant (organisms tolerant of low growth temperatures) photoautotrophs rely on low-temperature acclimative and adaptive strategies that have been described for other low-temperature-adapted heterotrophic organisms, such as cold-active proteins and maintenance of membrane fluidity. In addition, photoautrophic organisms possess other strategies to balance the absorption of light and the transduction of light energy to stored chemical energy products (NADPH and ATP) with downstream consumption of photosynthetically derived energy products at low temperatures. Lastly, differential adaptive and acclimative mechanisms exist in phototrophic microorganisms residing in low-temperature environments that are exposed to constant low-light environments versus high-light- and high-UV-exposed phototrophic assemblages. PMID:16524924

  15. Coral bleaching independent of photosynthetic activity.

    PubMed

    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.

  16. Enhanced Practical Photosynthetic CO2 Mitigation

    SciTech Connect

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

    2004-07-15

    This report highlights significant achievements in the Enhanced Practical Photosynthetic CO{sub 2} Mitigation Project for the period ending 06/30/2004. The major accomplishment was the modification of the header and harvesting work, with a system designed to distribute algae at startup, sustain operations and harvest in one unit.

  17. Longitudinal photosynthetic gradient in crust lichens' thalli.

    PubMed

    Wu, Li; Zhang, Gaoke; Lan, Shubin; Zhang, Delu; Hu, Chunxiang

    2014-05-01

    In order to evaluate the self-shading protection for inner photobionts, the photosynthetic activities of three crust lichens were detected using Microscope-Imaging-PAM. The false color images showed that longitudinal photosynthetic gradient was found in both the green algal lichen Placidium sp. and the cyanolichen Peltula sp. In longitudinal direction, all the four chlorophyll fluorescence parameters Fv/Fm, Yield, qP, and rETR gradually decreased with depth in the thalli of both of these two lichens. In Placidium sp., qN values decreased with depth, whereas an opposite trend was found in Peltula sp. However, no such photosynthetic heterogeneity was found in the thalli of Collema sp. in longitudinal direction. Microscope observation showed that photobiont cells are compactly arranged in Placidium sp. and Peltula sp. while loosely distributed in Collema sp. It was considered that the longitudinal photosynthetic heterogeneity was ascribed to the result of gradual decrease of incidence caused by the compact arrangement of photobiont cells in the thalli. The results indicate a good protection from the self-shading for the inner photobionts against high radiation in crust lichens.

  18. Photosynthetic strategies of two Mojave Desert shrubs

    SciTech Connect

    Kleinkopf, G.E.; Hartsock, T.L.; Wallace, A.; Romney, E.M.

    1980-01-01

    Photosynthetic production of two Mojave Desert shrubs was measured under natural growing conditions. Measurements of photosynthesis, transpiration, resistances to water vapor flux, soil moisture potential, and tissue water potential were made. Atriplex canescens (Pursh) Nutt., a member of the C/sub 4/ biochemical carbon dioxide fixation group was highly competitive in growth rate and production during conditions of adequate soil moisture. As soil moisture conditions declined to minus 40 bars, the net photosynthetic rate of Atriplex decreased to zero. However, the C/sub 3/ shrub species Larrea tridentata (Sesse and Moc. ex DC.) Cov. was able to maintain positive net photosynthetic production during conditions of high temperature and extreme low soil moisture through the major part of the season. The comparative advantages of the C/sub 4/ versus the C/sub 3/ pathway of carbon fixation was lost between these two species as the soil moisture potential declined to minus 40 bars. Desert plants have diffferent strategies for survival, one of the strategies being the C/sub 4/ biochemical carbon fixation pathway. However, many of the plants are members of the C/sub 3/ group. In this instance, the C/sub 4/ fixation pathway does not confer an added advantage to the productivity of the species in the Mojave Desert. Species distribution based on comparative photosynthetic production is discussed

  19. Hydrogen metabolism of photosynthetic bacteria and algae

    SciTech Connect

    Kumazawa, S.; Mitsui, A.

    1982-01-01

    The metabolism, metabolic pathways and biochemistry of hydrogen in photosynthetic bacteria and algae are reviewed. Detailed information on the occurrence and measurement of hydrogenase activity is presented. Hydrogen production rates for different species of algae and bacteria are presented. 173 references, 1 figure, 7 tables.

  20. Comparative analysis of plastid genomes of non-photosynthetic Ericaceae and their photosynthetic relatives.

    PubMed

    Logacheva, Maria D; Schelkunov, Mikhail I; Shtratnikova, Victoria Y; Matveeva, Maria V; Penin, Aleksey A

    2016-07-25

    Although plastid genomes of flowering plants are typically highly conserved regarding their size, gene content and order, there are some exceptions. Ericaceae, a large and diverse family of flowering plants, warrants special attention within the context of plastid genome evolution because it includes both non-photosynthetic and photosynthetic species with rearranged plastomes and putative losses of "essential" genes. We characterized plastid genomes of three species of Ericaceae, non-photosynthetic Monotropa uniflora and Hypopitys monotropa and photosynthetic Pyrola rotundifolia, using high-throughput sequencing. As expected for non-photosynthetic plants, M. uniflora and H. monotropa have small plastid genomes (46 kb and 35 kb, respectively) lacking genes related to photosynthesis, whereas P. rotundifolia has a larger genome (169 kb) with a gene set similar to other photosynthetic plants. The examined genomes contain an unusually high number of repeats and translocations. Comparative analysis of the expanded set of Ericaceae plastomes suggests that the genes clpP and accD that are present in the plastid genomes of almost all plants have not been lost in this family (as was previously thought) but rather persist in these genomes in unusual forms. Also we found a new gene in P. rotundifolia that emerged as a result of duplication of rps4 gene.

  1. Comparative analysis of plastid genomes of non-photosynthetic Ericaceae and their photosynthetic relatives.

    PubMed

    Logacheva, Maria D; Schelkunov, Mikhail I; Shtratnikova, Victoria Y; Matveeva, Maria V; Penin, Aleksey A

    2016-01-01

    Although plastid genomes of flowering plants are typically highly conserved regarding their size, gene content and order, there are some exceptions. Ericaceae, a large and diverse family of flowering plants, warrants special attention within the context of plastid genome evolution because it includes both non-photosynthetic and photosynthetic species with rearranged plastomes and putative losses of "essential" genes. We characterized plastid genomes of three species of Ericaceae, non-photosynthetic Monotropa uniflora and Hypopitys monotropa and photosynthetic Pyrola rotundifolia, using high-throughput sequencing. As expected for non-photosynthetic plants, M. uniflora and H. monotropa have small plastid genomes (46 kb and 35 kb, respectively) lacking genes related to photosynthesis, whereas P. rotundifolia has a larger genome (169 kb) with a gene set similar to other photosynthetic plants. The examined genomes contain an unusually high number of repeats and translocations. Comparative analysis of the expanded set of Ericaceae plastomes suggests that the genes clpP and accD that are present in the plastid genomes of almost all plants have not been lost in this family (as was previously thought) but rather persist in these genomes in unusual forms. Also we found a new gene in P. rotundifolia that emerged as a result of duplication of rps4 gene. PMID:27452401

  2. Comparative analysis of plastid genomes of non-photosynthetic Ericaceae and their photosynthetic relatives

    PubMed Central

    Logacheva, Maria D.; Schelkunov, Mikhail I.; Shtratnikova, Victoria Y.; Matveeva, Maria V.; Penin, Aleksey A.

    2016-01-01

    Although plastid genomes of flowering plants are typically highly conserved regarding their size, gene content and order, there are some exceptions. Ericaceae, a large and diverse family of flowering plants, warrants special attention within the context of plastid genome evolution because it includes both non-photosynthetic and photosynthetic species with rearranged plastomes and putative losses of “essential” genes. We characterized plastid genomes of three species of Ericaceae, non-photosynthetic Monotropa uniflora and Hypopitys monotropa and photosynthetic Pyrola rotundifolia, using high-throughput sequencing. As expected for non-photosynthetic plants, M. uniflora and H. monotropa have small plastid genomes (46 kb and 35 kb, respectively) lacking genes related to photosynthesis, whereas P. rotundifolia has a larger genome (169 kb) with a gene set similar to other photosynthetic plants. The examined genomes contain an unusually high number of repeats and translocations. Comparative analysis of the expanded set of Ericaceae plastomes suggests that the genes clpP and accD that are present in the plastid genomes of almost all plants have not been lost in this family (as was previously thought) but rather persist in these genomes in unusual forms. Also we found a new gene in P. rotundifolia that emerged as a result of duplication of rps4 gene. PMID:27452401

  3. Biogeography of Photosynthetic Light-Harvesting Genes in Marine Phytoplankton

    PubMed Central

    Bibby, Thomas S.; Zhang, Yinan; Chen, Min

    2009-01-01

    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 in the iron

  4. Photosynthetic oxygen evolution is not reversed at high oxygen pressures

    PubMed Central

    Kolling, Derrick R. J.; Brown, Tyler S.; Ananyev, Gennady; Dismukes, G. Charles

    2009-01-01

    We investigated the effects of elevated O2 pressure on the production of O2 by photosynthetic organisms in several species of plants, algae, and a cyanobacterium. Using a non-invasive fluorometry technique to monitor sequential turnover of the Photosystem II (PSII) reaction center as a function of O2 pressures, we showed that none of the reactions of water oxidation are affected by elevated O2 pressures up to 50-fold greater than atmospheric conditions. Thus, the terminal step of O2 release from the water oxidation complex (S4 → S0 + O2 + nH+) is not reversible in whole cells, leaves, or isolated thylakoid membranes containing PSII, in contrast to reports using detergent-extracted PSII complexes. This implies that there is no thermodynamically accessible intermediate that can be populated by preventing or reversing the O2 release step with atmospheric O2. To assess the sensitivity of PSII charge recombination to O2 pressure we quantitatively modeled the consequences of two putative perturbations to the catalytic cycle of water oxidation within the framework of the Kok model. Based on the breadth of oxygenic phototrophs examined in this study, we conclude that O2 accumulation in cells or the atmosphere does not suppress photosynthetic productivity through the reversal of water oxidation in contemporary phototrophs, and would have been unlikely to influence the evolution of oxygenic photosynthesis. PMID:19166323

  5. Primary Photosynthetic Energy Conversion in Bacterial Reaction Centers

    NASA Astrophysics Data System (ADS)

    Zinth, Wolfgang; Wachtveitl, J.

    The development of human societies is strongly influenced by the available energetic resources. In a period where the limitations of conventional fossil energy carriers become as evident as the often uncontrollable dangers of nuclear energy, one has to reconsider regenerative energy resources. Here photovoltaic or photochemical use of solar energy is an important approach. Since the early days of evolution some two billion years ago, the dominant energetic input into the life system on earth occurs via the conversion of solar energy performed in photosynthetic organisms. The fossil energy carriers that we use and waste today have been produced by photosynthesis over millions of years. In the race for an extended and versatile use of solar energy, semiconductorbased photovoltaic devices have been developed. However, even after decades of intense engineering they cannot serve as a competitive alternative to fossil energy. Under these circumstances new alternatives are required. One line of scientific development may use the operational principles of photosynthesis since photosynthesis is still our main energy source. In this respect, we will present results on the basic concepts of energy conversion in photosynthetic bacteria, which could be used as a guideline to alternative light energy conversion systems.

  6. Photosynthetic circadian rhythmicity patterns of Symbiodium, the coral endosymbiotic algae

    PubMed Central

    Sorek, Michal; Yacobi, Yosef Z.; Roopin, Modi; Berman-Frank, Ilana; Levy, Oren

    2013-01-01

    Biological clocks are self-sustained endogenous timers that enable organisms (from cyanobacteria to humans) to anticipate daily environmental rhythms, and adjust their physiology and behaviour accordingly. Symbiotic corals play a central role in the creation of biologically rich ecosystems based on mutualistic symbioses between the invertebrate coral and dinoflagellate protists from the genus Symbiodinium. In this study, we experimentally establish that Symbiodinium photosynthesis, both as a free-living unicellular algae and as part of the symbiotic association with the coral Stylophora pistillata, is ‘wired’ to the circadian clock mechanism with a ‘free-run’ cycle close to 24 h. Associated photosynthetic pigments also showed rhythmicity under light/dark conditions and under constant light conditions, while the expression of the oxygen-evolving enhancer 1 gene (within photosystem II) coincided with photosynthetically evolved oxygen in Symbiodinium cultures. Thus, circadian regulation of the Symbiodinium photosynthesis is, however, complicated as being linked to the coral/host that have probably profound physiochemical influence on the intracellular environment. The temporal patterns of photosynthesis demonstrated here highlight the physiological complexity and interdependence of the algae circadian clock associated in this symbiosis and the plasticity of algae regulatory mechanisms downstream of the circadian clock. PMID:23554392

  7. An Inexpensive Apparatus for Growing Photosynthetic Microorganisms in Exotic Atmospheres

    NASA Astrophysics Data System (ADS)

    Thomas, David J.; Herbert, Stephen K.

    2005-02-01

    Given the need for a light source, cyanobacteria and other photosynthetic microorganisms can be difficult and expensive to grow in large quantities. Lighted growth chambers and incubators typically cost 50-100% more than standard microbiological incubators. Self-shading of cells in liquid cultures prevents the growth of dense suspensions. Growing liquid cultures on a shaker table or lighted shaker incubator achieves greater cell densities, but adds considerably to the cost. For experiments in which gases other than air are required, the cost for conventional incubators increases even more. We describe an apparatus for growing photosynthetic organisms in exotic atmospheres that can be built relatively inexpensively (approximately $100 U.S.) using parts available from typical hardware or department stores (e.g., Wal-mart or K-mart). The apparatus uses microfiltered air (or other gases) to aerate, agitate, and mix liquid cultures, thus achieving very high cell densities (A750 > 3). Because gases are delivered to individual culture tubes, a variety of gas mixes can be used without the need for enclosed chambers. The apparatus works with liquid cultures of unicellular and filamentous species, and also works with agar slants.

  8. An inexpensive apparatus for growing photosynthetic microorganisms in exotic atmospheres.

    PubMed

    Thomas, David J; Herbert, Stephen K

    2005-02-01

    Given the need for a light source, cyanobacteria and other photosynthetic microorganisms can be difficult and expensive to grow in large quantities. Lighted growth chambers and incubators typically cost 50-100% more than standard microbiological incubators. Self-shading of cells in liquid cultures prevents the growth of dense suspensions. Growing liquid cultures on a shaker table or lighted shaker incubator achieves greater cell densities, but adds considerably to the cost. For experiments in which gases other than air are required, the cost for conventional incubators increases even more. We describe an apparatus for growing photosynthetic organisms in exotic atmospheres that can be built relatively inexpensively (approximately 100 dollars U.S.) using parts available from typical hardware or department stores (e.g., Wal-mart or K-mart). The apparatus uses microfiltered air (or other gases) to aerate, agitate, and mix liquid cultures, thus achieving very high cell densities (A750 > 3). Because gases are delivered to individual culture tubes, a variety of gas mixes can be used without the need for enclosed chambers. The apparatus works with liquid cultures of unicellular and filamentous species, and also works with agar slants. PMID:15711171

  9. ENHANCED PRACTICAL PHOTOSYNTHETIC CO2 MITIGATION

    SciTech Connect

    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

  10. Solar abundance of platinum

    PubMed Central

    Burger, Harry; Aller, Lawrence H.

    1975-01-01

    Three lines of neutral platinum, located at λ 2997.98 Å, λ 3064.71 Å, and λ 3301.86 Å have been used to determine the solar platinum abundance by the method of spectral synthesis. On the scale, log A(H) = 12.00, the thus-derived solar platinum abundance is 1.75 ± 0.10, in fair accord with Cameron's value of log A(Pt) = 1.69 derived by Mason from carbonaceous chondrites and calculated on the assumption that log A(Si) = 7.55 in the sun. PMID:16592278

  11. Mechanism and analyses for extracting photosynthetic electrons using exogenous quinones - what makes a good extraction pathway?

    PubMed

    Longatte, G; Rappaport, F; Wollman, F-A; Guille-Collignon, M; Lemaître, F

    2016-08-01

    Plants or algae take many benefits from oxygenic photosynthesis by converting solar energy into chemical energy through the synthesis of carbohydrates from carbon dioxide and water. However, the overall yield of this process is rather low (about 4% of the total energy available from sunlight is converted into chemical energy). This is the principal reason why recently many studies have been devoted to extraction of photosynthetic electrons in order to produce a sustainable electric current. Practically, the electron transfer occurs between the photosynthetic organism and an electrode and can be assisted by an exogenous mediator, mainly a quinone. In this regard, we recently reported on a method involving fluorescence measurements to estimate the ability of different quinones to extract photosynthetic electrons from a mutant of Chlamydomonas reinhardtii. In the present work, we used the same kind of methodology to establish a zone diagram for predicting the most suitable experimental conditions to extract photoelectrons from intact algae (quinone concentration and light intensity) as a function of the purpose of the study. This will provide further insights into the extraction mechanism of photosynthetic electrons using exogenous quinones. Indeed fluorescence measurements allowed us to model the capacity of photosynthetic algae to donate electrons to an exogenous quinone by considering a numerical parameter called "open center ratio" which is related to the Photosystem II acceptor redox state. Then, using it as a proxy for investigating the extraction of photosynthetic electrons by means of an exogenous quinone, 2,6-DCBQ, we suggested an extraction mechanism that was globally found consistent with the experimentally extracted parameters.

  12. Mechanism and analyses for extracting photosynthetic electrons using exogenous quinones - what makes a good extraction pathway?

    PubMed

    Longatte, G; Rappaport, F; Wollman, F-A; Guille-Collignon, M; Lemaître, F

    2016-08-01

    Plants or algae take many benefits from oxygenic photosynthesis by converting solar energy into chemical energy through the synthesis of carbohydrates from carbon dioxide and water. However, the overall yield of this process is rather low (about 4% of the total energy available from sunlight is converted into chemical energy). This is the principal reason why recently many studies have been devoted to extraction of photosynthetic electrons in order to produce a sustainable electric current. Practically, the electron transfer occurs between the photosynthetic organism and an electrode and can be assisted by an exogenous mediator, mainly a quinone. In this regard, we recently reported on a method involving fluorescence measurements to estimate the ability of different quinones to extract photosynthetic electrons from a mutant of Chlamydomonas reinhardtii. In the present work, we used the same kind of methodology to establish a zone diagram for predicting the most suitable experimental conditions to extract photoelectrons from intact algae (quinone concentration and light intensity) as a function of the purpose of the study. This will provide further insights into the extraction mechanism of photosynthetic electrons using exogenous quinones. Indeed fluorescence measurements allowed us to model the capacity of photosynthetic algae to donate electrons to an exogenous quinone by considering a numerical parameter called "open center ratio" which is related to the Photosystem II acceptor redox state. Then, using it as a proxy for investigating the extraction of photosynthetic electrons by means of an exogenous quinone, 2,6-DCBQ, we suggested an extraction mechanism that was globally found consistent with the experimentally extracted parameters. PMID:27411477

  13. Organizations.

    ERIC Educational Resources Information Center

    Aviation/Space, 1980

    1980-01-01

    This is a list of aerospace organizations and other groups that provides educators with assistance and information in specific areas. Both government and nongovernment organizations are included. (Author/SA)

  14. Using AVIRIS images to measure temporal trends in abundance of photosynthetic and nonphotosynthetic canopy components

    NASA Technical Reports Server (NTRS)

    Ustin, Susan L.; Smith, Milton O.; Roberts, Dar; Gamon, John A.; Field, Christopher B.

    1992-01-01

    The Jasper Ridge Biological Preserve, Stanford, California is a good example of hardwood rangeland ecosystems in California. Structurally, it is composed of a mosaic of serpentine grasslands, oak savannah, coastal chaparral, and mixed evergreen woodland, representing a broad cross-section of physiognomic classes. The Mediterranean climate produces an extended seasonal drought lasting throughout most of the growing season and has significant impact on the expression of divergent phenological patterns related to contrasting ecological strategies of these taxa. The region is well understood biologically due to the rich history of ecological research at the site. Thus, community characteristics, physiological characteristics, phenology, and temporal dynamics are reasonably well understood for many of the dominant species. Because of its proximity to NASA Ames Research Center, it has been subject to a large number of aircraft data acquisitions over many years. A more complete examination of this database would provide an opportunity to test current remote sensing hypotheses for measurement and detection of ecological attributes, particularly those involving canopy chemistry and physiology. Better definition of ecological rules might permit development of remotely sensed surrogate variables for biological properties that cannot be directly measured or measured with sufficient accuracy.

  15. RuBisCO in Non-Photosynthetic Alga Euglena longa: Divergent Features, Transcriptomic Analysis and Regulation of Complex Formation.

    PubMed

    Záhonová, Kristína; Füssy, Zoltán; Oborník, Miroslav; Eliáš, Marek; Yurchenko, Vyacheslav

    2016-01-01

    Euglena longa, a close relative of the photosynthetic model alga Euglena gracilis, possesses an enigmatic non-photosynthetic plastid. Its genome has retained a gene for the large subunit of the enzyme RuBisCO (rbcL). Here we provide new data illuminating the putative role of RuBisCO in E. longa. We demonstrated that the E. longa RBCL protein sequence is extremely divergent compared to its homologs from the photosynthetic relatives, suggesting a possible functional shift upon the loss of photosynthesis. Similarly to E. gracilis, E. longa harbors a nuclear gene encoding the small subunit of RuBisCO (RBCS) as a precursor polyprotein comprising multiple RBCS repeats, but one of them is highly divergent. Both RBCL and the RBCS proteins are synthesized in E. longa, but their abundance is very low compared to E. gracilis. No RBCS monomers could be detected in E. longa, suggesting that processing of the precursor polyprotein is inefficient in this species. The abundance of RBCS is regulated post-transcriptionally. Indeed, blocking the cytoplasmic translation by cycloheximide has no immediate effect on the RBCS stability in photosynthetically grown E. gracilis, but in E. longa, the protein is rapidly degraded. Altogether, our results revealed signatures of evolutionary degradation (becoming defunct) of RuBisCO in E. longa and suggest that its biological role in this species may be rather unorthodox, if any. PMID:27391690

  16. RuBisCO in Non-Photosynthetic Alga Euglena longa: Divergent Features, Transcriptomic Analysis and Regulation of Complex Formation

    PubMed Central

    Záhonová, Kristína; Füssy, Zoltán; Oborník, Miroslav; Eliáš, Marek

    2016-01-01

    Euglena longa, a close relative of the photosynthetic model alga Euglena gracilis, possesses an enigmatic non-photosynthetic plastid. Its genome has retained a gene for the large subunit of the enzyme RuBisCO (rbcL). Here we provide new data illuminating the putative role of RuBisCO in E. longa. We demonstrated that the E. longa RBCL protein sequence is extremely divergent compared to its homologs from the photosynthetic relatives, suggesting a possible functional shift upon the loss of photosynthesis. Similarly to E. gracilis, E. longa harbors a nuclear gene encoding the small subunit of RuBisCO (RBCS) as a precursor polyprotein comprising multiple RBCS repeats, but one of them is highly divergent. Both RBCL and the RBCS proteins are synthesized in E. longa, but their abundance is very low compared to E. gracilis. No RBCS monomers could be detected in E. longa, suggesting that processing of the precursor polyprotein is inefficient in this species. The abundance of RBCS is regulated post-transcriptionally. Indeed, blocking the cytoplasmic translation by cycloheximide has no immediate effect on the RBCS stability in photosynthetically grown E. gracilis, but in E. longa, the protein is rapidly degraded. Altogether, our results revealed signatures of evolutionary degradation (becoming defunct) of RuBisCO in E. longa and suggest that its biological role in this species may be rather unorthodox, if any. PMID:27391690

  17. Predicting the Dynamics of Protein Abundance

    PubMed Central

    Mehdi, Ahmed M.; Patrick, Ralph; Bailey, Timothy L.; Bodén, Mikael

    2014-01-01

    Protein synthesis is finely regulated across all organisms, from bacteria to humans, and its integrity underpins many important processes. Emerging evidence suggests that the dynamic range of protein abundance is greater than that observed at the transcript level. Technological breakthroughs now mean that sequencing-based measurement of mRNA levels is routine, but protocols for measuring protein abundance remain both complex and expensive. This paper introduces a Bayesian network that integrates transcriptomic and proteomic data to predict protein abundance and to model the effects of its determinants. We aim to use this model to follow a molecular response over time, from condition-specific data, in order to understand adaptation during processes such as the cell cycle. With microarray data now available for many conditions, the general utility of a protein abundance predictor is broad. Whereas most quantitative proteomics studies have focused on higher organisms, we developed a predictive model of protein abundance for both Saccharomyces cerevisiae and Schizosaccharomyces pombe to explore the latitude at the protein level. Our predictor primarily relies on mRNA level, mRNA–protein interaction, mRNA folding energy and half-life, and tRNA adaptation. The combination of key features, allowing for the low certainty and uneven coverage of experimental observations, gives comparatively minor but robust prediction accuracy. The model substantially improved the analysis of protein regulation during the cell cycle: predicted protein abundance identified twice as many cell-cycle-associated proteins as experimental mRNA levels. Predicted protein abundance was more dynamic than observed mRNA expression, agreeing with experimental protein abundance from a human cell line. We illustrate how the same model can be used to predict the folding energy of mRNA when protein abundance is available, lending credence to the emerging view that mRNA folding affects translation

  18. Electrochemical and optical studies of model photosynthetic systems. Final progress report, July 1, 1984--August 31, 1989

    SciTech Connect

    Not Available

    1992-01-15

    The objective of this research is to obtain a better understanding of the relationship between the structural organization of photosynthetic pigments and their spectroscopic and electrochemical properties. Defined model systems were studied first. These included the least ordered (solutions) through the most highly ordered (Langmuir-Blodgett (LB) monolayers and self-assembled monolayers) systems containing BChl, BPheo, and UQ. Molecules other than the photosynthetic pigments and quinones were also examined, including chromophores (i.e. surface active cyanine dyes and phtahlocyanines) an redox active compounds (methyl viologen (MV) and surfactant ferrocenes), in order to develop the techniques needed to study the photosynthetic components. Because the chlorophylls are photosensitive and labile, it was easier first to develop procedures using stable species. Three different techniques were used to characterize these model systems. These included electrochemical techniques for determining the standard oxidation and reduction potentials of the photosynthetic components as well as methods for determining the heterogeneous electron transfer rate constants for BChl and BPheo at metal electrodes (Pt and Au). Resonance Raman (RR) and surface enhanced resonance Raman (SERR) spectroscopy were used to determine the spectra of the photosynthetic pigments and model compounds. SERRS was also used to study several types of photosynthetic preparations.

  19. Abundances of light elements.

    PubMed Central

    Pagel, B E

    1993-01-01

    Recent developments in the study of abundances of light elements and their relevance to cosmological nucleosynthesis are briefly reviewed. The simplest model, based on standard cosmology and particle physics and assuming homogeneous baryon density at the relevant times, continues to stand up well. PMID:11607388

  20. [Engineering photosynthetic cyanobacterial chassis: a review].

    PubMed

    Wu, Qin; Chen, Lei; Wang, Jiangxin; Zhang, Weiwen

    2013-08-01

    Photosynthetic cyanobacteria possess a series of good properties, such as their abilities to capture solar energy for CO2 fixation, low nutritional requirements for growth, high growth rate, and relatively simple genetic background. Due to the high oil price and increased concern of the global warming in recent years, cyanobacteria have attracted widespread attention because they can serve as an 'autotrophic microbial factory' for producing renewable biofuels and fine chemicals directly from CO2. Particularly, significant progress has been made in applying synthetic biology techniques and strategies to construct and optimize cyanobacteria chassis. In this article, we critically summarized recent advances in developing new methods to optimize cyanobacteria chassis, improving cyanobacteria photosynthetic efficiency, and in constructing cyanobacteria chassis tolerant to products or environmental stresses. In addition, various industrial applications of cyanobacteria chassis are also discussed.

  1. BOREAS TE-9 NSA Photosynthetic Response Data

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G.; Curd, Shelaine (Editor); Dang, Qinglai; Margolis, Hank; Coyea, Marie

    2000-01-01

    The Boreal Ecosystem-Atmospheric Study (BOREAS) TE-9 (Terrestrial Ecology) team collected several data sets related to chemical and photosynthetic properties of leaves. This data set describes: (1) the response of leaf and shoot-level photosynthesis to ambient and intercellular CO2 concentration, temperature, and incident photosynthetically active radiation (PAR) for black spruce, jack pine, and aspen during the three intensive field campaigns (IFCs) in 1994 in the Northern Study Area (NSA); (2) the response of stomatal conductance to vapor pressure difference throughout the growing season of 1994; and (3) a range of shoot water potentials (controlled in the laboratory) for black spruce and jack pine. The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

  2. Photosynthetic hydrogen and oxygen production - Kinetic studies

    NASA Astrophysics Data System (ADS)

    Greenbaum, E.

    1982-01-01

    The simultaneous photoproduction of hydrogen and oxygen was measured in a study of the steady-state turnover times of two biological systems, by driving them into the steady state with repetitive, single-turnover flash illumination. The systems were: (1) in vitro, isolated chloroplasts, ferredoxin and hydrogenase; and (2) the anaerobically-adapted green alga Chlamydomonas reinhardtii. It is found that the turnover times for production of both oxygen and hydrogen in photosynthetic water splitting are in milliseconds, and either equal to, or less than, the turnover time for carbon dioxide reduction in intact algal cells. There is therefore mutual compatibility between hydrogen and oxygen turnover times, and partial compatibility with the excitation rate of the photosynthetic reaction centers under solar irradiation conditions.

  3. ENHANCED PRACTICAL PHOTOSYNTHETIC CO2 MITIGATION

    SciTech Connect

    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.

  4. Enhanced Practical Photosynthetic CO2 Mitigation

    SciTech Connect

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

    2005-01-13

    This report highlights significant achievements in the Enhanced Practical Photosynthetic CO{sub 2} Mitigation Project during the ending 12/31/2004. Specific results and accomplishments for the program include review of pilot scale testing and design of a new bioreactor. Testing confirmed that algae can be grown in a sustainable fashion in the pilot bioreactor, even with intermittent availability of sunlight. The pilot-scale tests indicated that algal growth rate followed photon delivery during productivity testing.

  5. Enhanced Practical Photosynthetic CO2 Mitigation

    SciTech Connect

    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 ''3.2.2 S.C.1 Positive'' migrated

  6. Genes involved in the biosynthesis of photosynthetic pigments in the purple sulfur photosynthetic bacterium Thiocapsa roseopersicina.

    PubMed

    Kovács, Akos T; Rákhely, Gábor; Kovács, Kornél L

    2003-06-01

    A pigment mutant strain of the purple sulfur photosynthetic bacterium Thiocapsa roseopersicina BBS was isolated by plasposon mutagenesis. Nineteen open reading frame, most of which are thought to be genes involved in the biosynthesis of carotenoids, bacteriochlorophyll, and the photosynthetic reaction center, were identified surrounding the plasposon in a 22-kb-long chromosomal locus. The general arrangement of the photosynthetic genes was similar to that in other purple photosynthetic bacteria; however, the locations of a few genes occurring in this region were unusual. Most of the gene products showed the highest similarity to the corresponding proteins in Rubrivivax gelatinosus. The plasposon was inserted into the crtD gene, likely inactivating crtC as well, and the carotenoid composition of the mutant strain corresponded to the aborted spirilloxanthin pathway. Homologous and heterologous complementation experiments indicated a conserved function of CrtC and CrtD in the purple photosynthetic bacteria. The crtDC and crtE genes were shown to be regulated by oxygen, and a role of CrtJ in aerobic repression was suggested.

  7. Photosynthetic carbon metabolism in Enteromorpha compressa (Chlorophyta)

    SciTech Connect

    Beer, S.; Shragge, B.

    1987-12-01

    The intertidal macroalga Enteromorpha compressa showed the ability to use HCO/sub 3//sup -/, as an exogenous inorganic carbon (Ci) source for photosynthesis. However, although the natural sea water concentration of this carbon form was saturating, additional CO/sub 2/ above ambient Ci levels doubled net photosynthetic rates. Therefore, the productivity of this alga, when submerged, is likely to be limited by Ci. When plants were exposed to air, photosynthetic rates saturated at air-levels of CO/sub 2/ during mild desiccation. Based on carbon fixing enzyme activities and Ci pulse-chase incorporation patterns, it was found that Enteromorpha is a C/sub 3/ plant. However, this alga did not show O/sub 2/ inhibited photosynthetic rates at natural sea water Ci conditions. It is suggested that such a C/sub 4/-like gas exchange response is due to the HCO/sub 3//sup -/ utilization system concentrating CO/sub 2/ intracellularly, thus alleviating apparent photorespiration.

  8. Improving photosynthetic efficiency for greater yield.

    PubMed

    Zhu, Xin-Guang; Long, Stephen P; Ort, Donald R

    2010-01-01

    Increasing the yield potential of the major food grain crops has contributed very significantly to a rising food supply over the past 50 years, which has until recently more than kept pace with rising global demand. Whereas improved photosynthetic efficiency has played only a minor role in the remarkable increases in productivity achieved in the last half century, further increases in yield potential will rely in large part on improved photosynthesis. Here we examine inefficiencies in photosynthetic energy transduction in crops from light interception to carbohydrate synthesis, and how classical breeding, systems biology, and synthetic biology are providing new opportunities to develop more productive germplasm. Near-term opportunities include improving the display of leaves in crop canopies to avoid light saturation of individual leaves and further investigation of a photorespiratory bypass that has already improved the productivity of model species. Longer-term opportunities include engineering into plants carboxylases that are better adapted to current and forthcoming CO(2) concentrations, and the use of modeling to guide molecular optimization of resource investment among the components of the photosynthetic apparatus, to maximize carbon gain without increasing crop inputs. Collectively, these changes have the potential to more than double the yield potential of our major crops. PMID:20192734

  9. BIOGEOCHEMICAL STUDIES OF PHOTOSYNTHETIC MICROBIAL MATS AND THEIR BIOTA

    NASA Technical Reports Server (NTRS)

    DesMarais, David; Discipulo, M.; Turk, K.; Londry, K. L.

    2005-01-01

    Photosynthetic microbial mats offer an opportunity to define holistic functionality at the millimeter scale. At the same time. their biogeochemistry contributes to environmental processes on a planetary scale. These mats are possibly direct descendents of the most ancient biological communities; communities in which oxygenic photosynthesis might have been invented. Mats provide one of the best natural systems to study how microbial populations associate to control dynamic biogeochemical gradients. These are self- sustaining, complete ecosystems in which light energy absorbed over a dial (24 hour) cycle drives the synthesis of spatially-organized, diverse biomass. Tightly-coupled microorganisms in the mat have specialized metabolisms that catalyze transformations of carbon, nitrogen, sulfur, and a host of other elements.

  10. Photosynthetic microorganisms in cold environments

    NASA Astrophysics Data System (ADS)

    Kviderova, Jana; Hajek, Josef; Elster, Josef; Bartak, Milos; Vaczi, Peter; Nedbalova, Linda

    The polar regions are considered as a model of extraterrestrial ecosystems. Depending on the average temperature, temperature variation and water availability, these conditions could be used as a model of Mars or Europa (e.g. (Elster and Benson, 2004). Two cases are presented: 1) Stable temperature and water availability The environment of cryosestic communities, i.e. organisms living in snow, is characterized by very stable temperature; the diurnal variations do not exceed 1 -2 ° C (Kváderová, 2010) and a are not usually exposed to freeze/thaw. Water is not usually limiting since the water content could reach up to 54 % (Nedbalová et al., 2008). The windblown sediments are important a source of nutrient and could provide protection against the excess of radiation. The nutrient concentrations in the snow are low are depleted rapidly when massive algal blooms forms. Such environment could be found near Mars polar caps or in Europa ice cover. The snow algae are the most important primary producers in snow. Their adaptation strategy is dependent on the developmental stages; the motile stages avoid the harsh conditions (e.g. high light) and sessile stages acclimatize to actual conditions. The main genera Chlamydomonas and Chloromonas (both Chlorophyta) are psychrophilic. Their growth optimum temperature is lower than 15 ° C and their growth is inhibited at temperatures above 20 ° C. 2) Unstable temperature and water availability The deglaciated surfaces, inhabited by lichen communities, are typical by variation in temper-ature and moisture. The temperature could range several tens ° C within a short time and the water availability is usually very limited. Due to temperature variation, the lichens are subjected to many freeze/thaw cycles. Such environments could be found in Martian deserts. The lichens are symbotic organisms composed of a mycobiont (heterotrophic fungi) and photo-bionts (algae and/or cyanobacteria). Majority of lichens are dehydrated in the field

  11. Complete fluorescent fingerprints of extremophilic and photosynthetic microbes

    NASA Astrophysics Data System (ADS)

    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.

  12. ENHANCED PRACTICAL PHOTOSYNTHETIC CO2 MITIGATION

    SciTech Connect

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

    2003-01-15

    This quarterly report documents significant achievements in the Enhanced Practical Photosynthetic CO{sub 2} Mitigation project during the period from 10/2/2001 through 1/01/2003. As indicated in the list of accomplishments below our current efforts are focused on evaluating candidate organisms and growth surfaces, preparing to conduct long-term tests in the bench-scale bioreactor test systems, and scaling-up the test facilities from bench scale to pilot scale. Specific results and accomplishments for the first quarter of 2003 include: Organisms and Growth Surfaces: (1) Additional thermal features with developed cyanobacterial mats, which might be calcium resistant, were found in the West Thumb area of YNP. New samples were isolated and are being cultured in glass tubes. (2) We checked the motile ability of 8.2.1 Synechococcus s.c. (10) and 3.2.2 Synechococcus s.c. 6. It was found that unicellular isolates 8.2.1 Synechococcus s.c. (10) and 3.2.2 Synechococcus s.c. 1 are phototaxic. Isolate 3.2.2 Synechococcus s.c. 1 currently consists of two populations: one population appears to be positive phototaxic, and second population appears negative phototaxis to the same level of light. This means that the character of screen illumination should be uniform and reasonable for cyanobacterial cells. (3) The aeration of growth media with 5% CO{sub 2} in air stimulates cyanobacterial growth 10-20 times over that with air alone. It is possible the rate of the stimulation of cyanobacterial growth in CRF will be higher because cyanobacteria will be grown as a biofilm. We plan to increase the concentration to 15% CO{sub 2} in air. (4) We are continuing the organizing of our collection of the thermophilic cyanobacteria isolated from Yellowstone National Park. During this reporting period we transferred about 160 samples and discarded about 80 samples with weak growth in standard media as BG-11, D or DH. As result of this work we currently have 13 unialgal cultures of thermophilic

  13. Solar abundance of iridium

    PubMed Central

    Drake, Stephen; Aller, Lawrence H.

    1976-01-01

    By a method of spectrum synthesis, which yields log gfA, where g is the statistical weight of the lower level, f is the oscillator strength, and A is the abundance, an attempt is made to deduce the solar iridium abundance from one relatively unblended, but fairly weak IrI line, λ 3220.78 Å. If the Corliss-Bozman f-value for this line is adopted, we find log A(Ir) = 0.82 on the scale log A(H) = 12.00. The discordance with the value found from carbonaceous chondrites may arise from faulty f-values or from difficulties arising from line blending in this far ultraviolet domain of the solar spectrum. PMID:16578735

  14. Organics.

    ERIC Educational Resources Information Center

    Chian, Edward S. K.; DeWalle, Foppe B.

    1978-01-01

    Presents water analysis literature for 1978. This review is concerned with organics, and it covers: (1) detergents and surfactants; (2) aliphatic and aromatic hydrocarbons; (3) pesticides and chlorinated hydrocarbons; and (4) naturally occurring organics. A list of 208 references is also presented. (HM)

  15. Organizers.

    ERIC Educational Resources Information Center

    Callison, Daniel

    2000-01-01

    Focuses on "organizers," tools or techniques that provide identification and classification along with possible relationships or connections among ideas, concepts, and issues. Discusses David Ausubel's research and ideas concerning advance organizers; the implications of Ausubel's theory to curriculum and teaching; "webbing," a specific…

  16. An Energy Balance Model to Predict Chemical Partitioning in a Photosynthetic Microbial Mat

    NASA Technical Reports Server (NTRS)

    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.

  17. [Photosynthetic characteristics of five arbor species in Shenyang urban area].

    PubMed

    Li, Hai-Me; He, Xing-Yuan; Wang, Kui-Ling; Chen, Wei

    2007-08-01

    By using LI-6400 infrared gas analyzer, this paper studied the diurnal and seasonal variations of the photosynthetic rate of main arbor species (Populus alba x P. berolinensis, Salix matsudana, Ulmus pumila, Robinia pseudoacacia and Prunus davidiana) in Shenyang urban area. The correlations between net photosynthetic rate and environmental factors (photosynthetic active radiation, temperature, and stomatal conductance) were assessed by multivariate regression analysis, and related equations were constructed. The results showed that for test arbor species, the diurnal variation of photosynthetic rate mainly presented a single peak curve, and the seasonal variation was in the order of summer > autumn > spring. The major factors affecting the photosynthetic rate were photosynthetic active radiation, stomatal conductance, and intercellular CO2 concentration.

  18. Photosynthetic parameters of northern gulf of California phytoplankton

    NASA Astrophysics Data System (ADS)

    Alvarez-Borrego, Saul; Gaxiola-Castro, Gilberto

    1988-01-01

    At the end of autumn, 1981, and end of spring-beginning of summer, 1982, we generated photosynthesis-irradiance curves for phytoplankton from five locations, in each cruise, of the northern Gulf of California. In general, photosynthetic parameters, phytoplankton abundance and chlorophyll a had large vertical changes within the euphotic zone, even in cases where thermohaline vertical homogeneity indicated high instability. Nutrient concentrations were very high. The assimilation number ( PmB), in general, decreased with depth due to conditioning of phytoplankton to lower irradiances. Surface ( PmB) values had a range of 2-15 mg C ( mg Chla) -1h -1. Where the bottom of the euphotic zone was within the thermocline, PmB was 4-15% of the values for surface waters; and where it was within the mixed layer, PmB was 25-85% of the values for surface waters. This was due to greater residence time of phytoplankton at depth in the first case. Very strong turbulence by storm winds caused relatively low PmB values in a December station, possibly because of mixing of the near-surface phytoplankton with relatively deep populations conditioned to low irradiances. Our data indicate that in the Gulf moderate turbulence causes higher PmB values than strong turbulence or stratification.

  19. Enhanced Practical Photosynthetic CO2 Mitigation

    SciTech Connect

    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

  20. Harnessing Solar Energy Using Photosynthetic and Organic Pigments

    NASA Astrophysics Data System (ADS)

    Fitzsimons, Toby Ryan

    Fossil fuels are a finite energy resource that must be supplemented or replaced by more stable forms of electrical energy. Solar technology research strives to supplement and provide eventual replacement for fossil fuel technology. This experiment focused on the use of natural pigments as photo-sensitizers in the current generation of solar cells called dye sensitized solar cells (DSSCs). Pigments from purified chlorophyll a, chlorophyll b, chlorophyll a/b, crude spinach (Spinacia oleracea) extract, phycocyanin, and chlorophyllin were used to construct DSSCs and evaluated, along with a control containing no pigment, for solar energy conversion. The anode of the solar cells consisted of titanium dioxide (TiO2) plates soaked in pigment solutions for twenty-four hours. The plates were assembled, along with an electrolyte sandwiched between cells, and a platinum-coated counter plate that functioned as the cathode. A gasket seal was placed between the plates and held together with rubber bands. The DSSCs were each tested for a maximum power (Pmax) point and a resistor was selected that corresponded to the resistance at that point. The cells were randomly placed into a power block assembly located in an environmental chamber with lighting that provided an average of 27,590 lumens at the surface of DSSCs. With appropriate resistors in place, the cells were subjected to twelve-hour days and twelve-hour nights for ten days, and measurements were recorded every ten minutes. Data were collected to obtain values for voltage in millivolts (mV), current in microamps (microA), and power in microwatts (microW), as well as beginning and ending efficiencies in converting light to usable energy. Voltages were substantially higher during the day than at night for all pigments, except for the control, indicating that the pigments functioned as DSSCs. Hence, only daytime values were used for data analysis. Voltage during the ten-day experiment ranged from 3.99 to 274 mV; current ranged from 0.0180 to 41.9 microA, and power ranged from 0.00 to 11.3 microW. Chlorophyllin had the highest peak and least voltage (274 and 161 mV), highest peak and least current (41.9 and 21.8 microA), and highest peak and least power (11.3 and 4.84 microW). The ranking of the pigments for peak voltage was: Chlorophyllin = Crude Extract ≥ Chlorophyll a = Chlorophyll a/b ≥ Phycocyanin = Chlorophyll b > Control. The ranking for least voltage was: Chlorophyllin > Phycocyanin ≥ Chlorophyll a/b ≥ Crude Extract ≥ Chlorophyll b ≥ Chlorophyll a ≥ Control. Ranking for peak and least values were similar for current and power. Solar energy conversion (efficiency in converting light energy to usable energy in watts per square meter) for all treatments ranged from 0.000595 to 0.0217% at the beginning of the experiment, and was highest in cells constructed with chlorophyllin. Based on rankings from peak and ending voltage values, as well as other measurements, it was concluded that DSSCs constructed with chlorophyllin performed the best and lasted the longest as photo-sensitizers, compared to other pigments used in this investigation. The DSSCs constructed with crude extract performed almost as well as those constructed with chlorophyllin at the beginning of the experiment, but degradation of this naturally-made pigment may have prevented these cells from sustaining solar energy conversion for more than a few days. Other pigments demonstrated conversion values higher than those of control DSSCs which contained no pigments. The results from this project provide evidence that DSSCs can produce useable energy. More research is needed to enhance and prolong the efficiency of DSSCs in solar energy conversion.

  1. Hydrogen production using hydrogenase-containing oxygenic photosynthetic organisms

    DOEpatents

    Melis, Anastasios; Zhang, Liping; Benemann, John R.; Forestier, Marc; Ghirardi, Maria; Seibert, Michael

    2006-01-24

    A reversible physiological process provides for the temporal separation of oxygen evolution and hydrogen production in a microorganism, which includes the steps of growing a culture of the microorganism in medium under illuminated conditions to accumulate an endogenous substrate, depleting from the medium a nutrient selected from the group consisting of sulfur, iron, and/or manganese, sealing the culture from atmospheric oxygen, incubating the culture in light whereby a rate of light-induced oxygen production is equal to or less than a rate of respiration, and collecting an evolved gas. The process is particularly useful to accomplish a sustained photobiological hydrogen gas production in cultures of microorganisms, such as Chlamydomonas reinhardtii.

  2. Hydrogen Production Using Hydrogenase-Containing Oxygenic Photosynthetic Organisms

    DOEpatents

    Melis, A.; Zhang, L.; Benemann, J. R.; Forestier, M.; Ghirardi, M.; Seibert, M.

    2006-01-24

    A reversible physiological process provides for the temporal separation of oxygen evolution and hydrogen production in a microorganism, which includes the steps of growing a culture of the microorganism in medium under illuminated conditions to accumulate an endogenous substrate, depleting from the medium a nutrient selected from the group consisting of sulfur, iron, and/or manganese, sealing the culture from atmospheric oxygen, incubating the culture in light whereby a rate of light-induced oxygen production is equal to or less than a rate of respiration, and collecting an evolved gas. The process is particularly useful to accomplish a sustained photobiological hydrogen gas production in cultures of microorganisms, such as Chlamydomonas reinhardtii.

  3. Hybrid artificial photosynthetic systems comprising semiconductors as light harvesters and biomimetic complexes as molecular cocatalysts.

    PubMed

    Wen, Fuyu; Li, Can

    2013-11-19

    Solar fuel production through artificial photosynthesis may be a key to generating abundant and clean energy, thus addressing the high energy needs of the world's expanding population. As the crucial components of photosynthesis, the artificial photosynthetic system should be composed of a light harvester (e.g., semiconductor or molecular dye), a reduction cocatalyst (e.g., hydrogenase mimic, noble metal), and an oxidation cocatalyst (e.g., photosystem II mimic for oxygen evolution from water oxidation). Solar fuel production catalyzed by an artificial photosynthetic system starts from the absorption of sunlight by the light harvester, where charge separation takes place, followed by a charge transfer to the reduction and oxidation cocatalysts, where redox reaction processes occur. One of the most challenging problems is to develop an artificial photosynthetic solar fuel production system that is both highly efficient and stable. The assembly of cocatalysts on the semiconductor (light harvester) not only can facilitate the charge separation, but also can lower the activation energy or overpotential for the reactions. An efficient light harvester loaded with suitable reduction and oxidation cocatalysts is the key for high efficiency of artificial photosynthetic systems. In this Account, we describe our strategy of hybrid photocatalysts using semiconductors as light harvesters with biomimetic complexes as molecular cocatalysts to construct efficient and stable artificial photosynthetic systems. We chose semiconductor nanoparticles as light harvesters because of their broad spectral absorption and relatively robust properties compared with a natural photosynthesis system. Using biomimetic complexes as cocatalysts can significantly facilitate charge separation via fast charge transfer from the semiconductor to the molecular cocatalysts and also catalyze the chemical reactions of solar fuel production. The hybrid photocatalysts supply us with a platform to study the

  4. Solar coronal and photospheric abundances from solar energetic particle measurements

    NASA Technical Reports Server (NTRS)

    Breneman, H. H.; Stone, E. C.

    1985-01-01

    Solar energetic particle (SEP) elemental abundance data from the cosmic ray subsystem (CRS) aboard the Voyager 1 and 2 spacecraft are used to derive unfractionated coronal and photospheric abundances for elements with Z = 6-30. It is found that the ionic charge-to-mass ratio (Q/M) is the principal organizing parameter for the fractionation of SEPs by acceleration and propagation processes and for flare-to-flare variability, making possible a single-parameter Q/M-dependent correction to the average SEP abundances to obtain unfractionated coronal abundances. A further correction based on first ionization potential allows the determination of unfractionated photospheric abundances.

  5. Solar Coronal and photospheric abundances from solar energetic particle measurements

    NASA Technical Reports Server (NTRS)

    Breneman, H.; Stone, E. C.

    1985-01-01

    Solar energetic particle (SEP) elemental abundance data from the cosmic ray subsystem (CRS) aboard the Voyager 1 and 2 spacecraft are used to derive unfractionated coronal and photospheric abundances for elements with 3 Z or = 30. It is found that the ionic charge-to-mass ratio (Q/M) is the principal organizing parameter for the fractionation of SEPs by acceleration and propagation processes and for flare-to-flare variability, making possible a single-parameter Q/M-dependent correction to the average SEP abundances to obtain unfractionated coronal abundances. A further correction based on first ionization potential allows the determination of unfractionated photospheric abundances.

  6. Solar coronal and photospheric abundances from solar energetic particle measurements

    NASA Technical Reports Server (NTRS)

    Breneman, H.; Stone, E. C.

    1985-01-01

    Solar energetic particle (SEP) elemental abundance data from the Cosmic Ray Subsystem (CRS) aboard the Voyager 1 and 2 spacecraft are used to derive unfractionated coronal and photospheric abundances for elements with 3 = or Z or = 30. The ionic charge-to-mass ratio (Q/M) is the principal organizing parameter for the fractionation of SEPs by acceleration and propagation processes and for flare-to-flare variability, making possible a single-parameter Q/M-dependent correction to the average SEP abundances to obtain unfractionated coronal abundances. A further correction based on first ionization potential allows the determination of unfractionated photospheric abundances.

  7. Abundance of field galaxies

    NASA Astrophysics Data System (ADS)

    Klypin, Anatoly; Karachentsev, Igor; Makarov, Dmitry; Nasonova, Olga

    2015-12-01

    We present new measurements of the abundance of galaxies with a given circular velocity in the Local Volume: a region centred on the Milky Way Galaxy and extending to distance ˜10 Mpc. The sample of ˜750 mostly dwarf galaxies provides a unique opportunity to study the abundance and properties of galaxies down to absolute magnitudes MB ≈ -10 and virial masses M_vir= 109{ M_{⊙}}. We find that the standard Λ cold dark matter (ΛCDM) model gives remarkably accurate estimates for the velocity function of galaxies with circular velocities V ≳ 70 kms-1 and corresponding virial masses M_vir≳ 5× 10^{10}{ M_{⊙}}, but it badly fails by overpredicting ˜5 times the abundance of large dwarfs with velocities V = 30-40 kms-1. The warm dark matter (WDM) models cannot explain the data either, regardless of mass of WDM particle. Just as in previous observational studies, we find a shallow asymptotic slope dN/dlog V ∝ Vα, α ≈ -1 of the velocity function, which is inconsistent with the standard ΛCDM model that predicts the slope α = -3. Though reminiscent to the known overabundance of satellite problem, the overabundance of field galaxies is a much more difficult problem. For the standard ΛCDM model to survive, in the 10 Mpc radius of the Milky Way there should be 1000 not yet detected galaxies with virial mass M_vir≈ 10^{10}{ M_{⊙}}, extremely low surface brightness and no detectable H I gas. So far none of this type of galaxies have been discovered.

  8. Late embryogenesis abundant proteins

    PubMed Central

    Olvera-Carrillo, Yadira; Reyes, José Luis

    2011-01-01

    Late Embryogenesis Abundant (LEA) proteins accumulate at the onset of seed desiccation and in response to water deficit in vegetative plant tissues. The typical LEA proteins are highly hydrophilic and intrinsically unstructured. They have been classified in different families, each one showing distinctive conserved motifs. In this manuscript we present and discuss some of the recent findings regarding their role in plant adaptation to water deficit, as well as those concerning to their possible function, and how it can be related to their intrinsic structural flexibility. PMID:21447997

  9. Application of photosynthetic N2-fixing cyanobacteria to the CELSS program

    NASA Technical Reports Server (NTRS)

    Packer, L.; Fry, I.; Belkin, S.

    1986-01-01

    Commercially available air lift fermentors were used to simultaneously monitor biomass production, N2-fixation, photosynthesis, respiration, and sensitivity to oxidative damage during growth under various nutritional and light regimes, to establish a data base for the integration of these organisms into a Closed Ecological Life Support System (CELSS) program. Certain cyanobacterial species have the unique ability to reduce atmospheric N2 to organic nitrogen. These organisms combine the ease of cultivation characteristics of prokaryotes with the fully developed photosynthetic apparatus of higher plants. This, along with their ability to adapt to changes in their environment by modulation of certain biochemical pathways, make them attractive candidates for incorporation into the CELSS program.

  10. Temperature response of Antarctic cryptoendolithic photosynthetic microorganisms

    NASA Technical Reports Server (NTRS)

    Ocampo-Friedmann, R.; Meyer, M. A.; Chen, M.; Friedmann, E. I.

    1988-01-01

    Growth responses to temperatures between 12.5 [degrees] C and 25 degrees C were determined for five photosynthetic microorganisms isolated from the Ross Desert cryptoendolithic community. Among eukaryotic algae, two strains of Trebouxia sp. have an upper temperature limit of 20 degrees C, and two strains of Hemichloris antarctica of 25 degrees C. The cyanobacterium Chroococcidiopsis sp., in contrast, grows at temperatures above 25 degrees C. These and earlier studies suggest that the eukaryotic algae of the Antarctic cryptoendolithic community have an upper temperature limit near 25 degrees C.

  11. Culturing photosynthetic bacteria through surface plasmon resonance

    SciTech Connect

    Ooms, Matthew D.; Bajin, Lauren; Sinton, David

    2012-12-17

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

  12. Engineering cyanobacteria as photosynthetic feedstock factories.

    PubMed

    Hays, Stephanie G; Ducat, Daniel C

    2015-03-01

    Carbohydrate feedstocks are at the root of bioindustrial production and are needed in greater quantities than ever due to increased prioritization of renewable fuels with reduced carbon footprints. Cyanobacteria possess a number of features that make them well suited as an alternative feedstock crop in comparison to traditional terrestrial plant species. Recent advances in genetic engineering, as well as promising preliminary investigations of cyanobacteria in a number of distinct production regimes have illustrated the potential of these aquatic phototrophs as biosynthetic chassis. Further improvements in strain productivities and design, along with enhanced understanding of photosynthetic metabolism in cyanobacteria may pave the way to translate cyanobacterial theoretical potential into realized application.

  13. Microspectroscopy of the photosynthetic compartment of algae.

    PubMed

    Evangelista, Valtere; Frassanito, Anna Maria; Passarelli, Vincenzo; Barsanti, Laura; Gualtieri, Paolo

    2006-01-01

    We performed microspectroscopic evaluation of the pigment composition of the photosynthetic compartments of algae belonging to different taxonomic divisions and higher plants. The feasibility of microspectroscopy for discriminating among species and/or phylogenetic groups was tested on laboratory cultures. Gaussian bands decompositions and a fitting algorithm, together with fourth-derivative transformation of absorbance spectra, provided a reliable discrimination among chlorophylls a, b and c, phycobiliproteins and carotenoids. Comparative analysis of absorption spectra highlighted the evolutionary grouping of the algae into three main lineages in accordance with the most recent endosymbiotic theories.

  14. Culturing photosynthetic bacteria through surface plasmon resonance

    NASA Astrophysics Data System (ADS)

    Ooms, Matthew D.; Bajin, Lauren; Sinton, David

    2012-12-01

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

  15. Temperature response of Antarctic cryptoendolithic photosynthetic microorganisms.

    PubMed

    Ocampo-Friedmann, R; Meyer, M A; Chen, M; Friedmann, E I

    1988-01-01

    Growth responses to temperatures between 12.5 [degrees] C and 25 degrees C were determined for five photosynthetic microorganisms isolated from the Ross Desert cryptoendolithic community. Among eukaryotic algae, two strains of Trebouxia sp. have an upper temperature limit of 20 degrees C, and two strains of Hemichloris antarctica of 25 degrees C. The cyanobacterium Chroococcidiopsis sp., in contrast, grows at temperatures above 25 degrees C. These and earlier studies suggest that the eukaryotic algae of the Antarctic cryptoendolithic community have an upper temperature limit near 25 degrees C.

  16. Electron Paramagnetic Resonance Study of a Photosynthetic Microbial Mat and Comparison with Archean Cherts

    NASA Astrophysics Data System (ADS)

    Bourbin, M.; Derenne, S.; Gourier, D.; Rouzaud, J.-N.; Gautret, P.; Westall, F.

    2012-12-01

    Organic radicals in artificially carbonized biomass dominated by oxygenic and non-oxygenic photosynthetic bacteria, Microcoleus chthonoplastes-like and Chloroflexus-like bacteria respectively, were studied by Electron Paramagnetic Resonance (EPR) spectroscopy. The two bacteria species were sampled in mats from a hypersaline lake. They underwent accelerated ageing by cumulative thermal treatments to induce progressive carbonization of the biological material, mimicking the natural maturation of carbonaceous material of Archean age. For thermal treatments at temperatures higher than 620 °C, a drastic increase in the EPR linewidth is observed in the carbonaceous matter from oxygenic photosynthetic bacteria and not anoxygenic photosynthetic bacteria. This selective EPR linewidth broadening reflects the presence of a catalytic element inducing formation of radical aggregates, without affecting the molecular structure or the microstructure of the organic matter, as shown by Raman spectroscopy and Transmission Electron Microscopy. For comparison, we carried out an EPR study of organic radicals in silicified carbonaceous rocks (cherts) from various localities, of different ages (0.42 to 3.5 Gyr) and having undergone various degrees of metamorphism, i.e. various degrees of natural carbonization. EPR linewidth dispersion for the most primitive samples was quite significant, pointing to a selective dipolar broadening similar to that observed for carbonized bacteria. This surprising result merits further evaluation in the light of its potential use as a marker of past bacterial metabolisms, in particular oxygenic photosynthesis, in Archean cherts.

  17. Electron paramagnetic resonance study of a photosynthetic microbial mat and comparison with Archean cherts.

    PubMed

    Bourbin, M; Derenne, S; Gourier, D; Rouzaud, J-N; Gautret, P; Westall, F

    2012-12-01

    Organic radicals in artificially carbonized biomass dominated by oxygenic and non-oxygenic photosynthetic bacteria, Microcoleus chthonoplastes-like and Chloroflexus-like bacteria respectively, were studied by Electron Paramagnetic Resonance (EPR) spectroscopy. The two bacteria species were sampled in mats from a hypersaline lake. They underwent accelerated ageing by cumulative thermal treatments to induce progressive carbonization of the biological material, mimicking the natural maturation of carbonaceous material of Archean age. For thermal treatments at temperatures higher than 620 °C, a drastic increase in the EPR linewidth is observed in the carbonaceous matter from oxygenic photosynthetic bacteria and not anoxygenic photosynthetic bacteria. This selective EPR linewidth broadening reflects the presence of a catalytic element inducing formation of radical aggregates, without affecting the molecular structure or the microstructure of the organic matter, as shown by Raman spectroscopy and Transmission Electron Microscopy. For comparison, we carried out an EPR study of organic radicals in silicified carbonaceous rocks (cherts) from various localities, of different ages (0.42 to 3.5 Gyr) and having undergone various degrees of metamorphism, i.e. various degrees of natural carbonization. EPR linewidth dispersion for the most primitive samples was quite significant, pointing to a selective dipolar broadening similar to that observed for carbonized bacteria. This surprising result merits further evaluation in the light of its potential use as a marker of past bacterial metabolisms, in particular oxygenic photosynthesis, in Archean cherts.

  18. Electron paramagnetic resonance study of a photosynthetic microbial mat and comparison with Archean cherts.

    PubMed

    Bourbin, M; Derenne, S; Gourier, D; Rouzaud, J-N; Gautret, P; Westall, F

    2012-12-01

    Organic radicals in artificially carbonized biomass dominated by oxygenic and non-oxygenic photosynthetic bacteria, Microcoleus chthonoplastes-like and Chloroflexus-like bacteria respectively, were studied by Electron Paramagnetic Resonance (EPR) spectroscopy. The two bacteria species were sampled in mats from a hypersaline lake. They underwent accelerated ageing by cumulative thermal treatments to induce progressive carbonization of the biological material, mimicking the natural maturation of carbonaceous material of Archean age. For thermal treatments at temperatures higher than 620 °C, a drastic increase in the EPR linewidth is observed in the carbonaceous matter from oxygenic photosynthetic bacteria and not anoxygenic photosynthetic bacteria. This selective EPR linewidth broadening reflects the presence of a catalytic element inducing formation of radical aggregates, without affecting the molecular structure or the microstructure of the organic matter, as shown by Raman spectroscopy and Transmission Electron Microscopy. For comparison, we carried out an EPR study of organic radicals in silicified carbonaceous rocks (cherts) from various localities, of different ages (0.42 to 3.5 Gyr) and having undergone various degrees of metamorphism, i.e. various degrees of natural carbonization. EPR linewidth dispersion for the most primitive samples was quite significant, pointing to a selective dipolar broadening similar to that observed for carbonized bacteria. This surprising result merits further evaluation in the light of its potential use as a marker of past bacterial metabolisms, in particular oxygenic photosynthesis, in Archean cherts. PMID:23254854

  19. Chemical abundance of comets

    NASA Technical Reports Server (NTRS)

    Wyckoff, Susan; Wehinger, Peter

    1988-01-01

    Observations of NH2, (OI) and molecular ion spectra in comets represent virtually all of the volatile fraction of a comet nucleus. Their study leads to the N2, NH3, H2O, CO2, CO content of the nucleus, and thus to important constraints on models of comet formation and chemical processing in the primitive solar nebula. The observations of Comet Halley provide the opportunity for the first comprehensive determination of the abundances in a comet nucleus. The carbon isotope abundance ratio 12 C/13 C = 65 plus or minus 8 has been determined for Comet Halley from resolved rotational line structure in the CN B-X (0,0) band. The ratio is approximately 30 pct lower than the solar system value, 89, indicating either an enhancement of 13CN or a depletion of 12CN in the comet. Scenarios consistent with the observed carbon isotope ratio are: (1) formation of the comet at the periphery of the solar nebula in a fractionation-enriched 13CN region, or hidden from 12CN enrichment sources, and (2) capture of an interestellar comet. Long-slit charge coupled device (CCD) spectra obtained at the time of the spacecraft encounter of Comet Halley have also been analyzed. Scale lengths, production rates and column densities of CH, CN, C2 and NH2 were determined.

  20. Flare Plasma Iron Abundance

    NASA Technical Reports Server (NTRS)

    Dennis, Brian R.; Dan, Chau; Jain, Rajmal; Schwartz, Richard A.; Tolbert, Anne K.

    2008-01-01

    The equivalent width of the iron-line complex at 6.7 keV seen in flare X-ray spectra suggests that the iron abundance of the hottest plasma at temperatures >approx.10 MK may sometimes be significantly lower than the nominal coronal abundance of four times the photospheric value that is commonly assumed. This conclusion is based on X-ray spectral observations of several flares seen in common with the Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and the Solar X-ray Spectrometer (SOXS) on the second Indian geostationary satellite, GSAT-2. The implications of this will be discussed as it relates to the origin of the hot flare plasma - either plasma already in the corona that is directly heated during the flare energy release process or chromospheric plasma that is heated by flare-accelerated particles and driven up into the corona. Other possible explanations of lower-than-expected equivalent widths of the iron-line complex will also be discussed.

  1. Toward understanding as photosynthetic biosignatures: light harvesting and energy transfer calculation

    NASA Astrophysics Data System (ADS)

    Komatsu, Y.; Umemura, M.; Shoji, M.; Shiraishi, K.; Kayanuma, M.; Yabana, K.

    2014-03-01

    Among several proposed biosignatures, red edge is a direct evidence of photosynthetic life if it is detected (Kiang et al 2007). Red edge is a sharp change in reflectance spectra of vegetation in NIR region (about 700-750 nm). The sign of red edge is observed by Earthshine or remote sensing (Wolstencroft & Raven 2002, Woolf et al 2002). But, why around 700-750 nm? The photosynthetic organisms on Earth have evolved to optimize the sunlight condition. However, if we consider about photosynthetic organism on extrasolar planets, they should have developed to utilize the spectra of its principal star. Thus, it is not strange even if it shows different vegetation spectra. In this study, we focused on the light absorption mechanism of photosynthetic organisms on Earth and investigated the fundamental properties of the light harvesting mechanisms, which is the first stage for the light absorption. Light harvesting complexes contain photosynthetic pigments like chlorophylls. Effective light absorption and the energy transfer are accomplished by the electronic excitations of collective photosynthetic pigments. In order to investigate this mechanism, we constructed an energy transfer model by using a dipole-dipole approximation for the interactions between electronic excitations. Transition moments and transition energies of each pigment are calculated at the time-dependent density functional theory (TDDFT) level (Marques & Gross 2004). Quantum dynamics simulation for the excitation energy transfer was calculated by the Liouvelle's equation. We adopted the model to purple bacteria, which has been studied experimentally and known to absorb lower energy. It is meaningful to focus on the mechanism of this bacteria, since in the future mission, M planets will become a important target. We calculated the oscillator strengths in one light harvesting complex and confirmed the validity by comparing to the experimental data. This complex is made of an inner and an outer ring. The

  2. [Effect of different substrates on photosynthetic characteristics of Iris pseudacorus L. and the capacity of purify wastewater].

    PubMed

    Xu, De-Fu; Li, Ying-Xue; Zheng, Jian-Wei; Fang, Hua; Zhao, Xiao-Li

    2011-09-01

    The effect of the different substrates on the photosynthetic characteristics, transpiration rate and SPAD value, and capacity of purify wastewater was investigated by pot experiment, based on five ordinary substrates (soil, sand, mixture of soil and sand, mixture of sand and organic matter, and mixture sand, soil and organic matter). Results showed that the photosynthetic characteristics and transpiration rate of Iris pseudacorus L. were influenced by different substrates. The order of the photosynthetic and transpiration rate of Iris pseudacorus L. in soil was high, and that of Iris pseudacorus L. in sand was the lowest. The value of photosynthetic characteristics and transpiration rate of Iris pseudacorus L. in soil were 11.67 micromol x (m2 x s)(-1) and 9.18 mmol x (m2 x s) (-1) respectively, and that of Iris pseudacorus L. in sand were 8.38 micromol x (m2 x s)(-1) and 4.55 mmol x (m2 x s)(-1), respectively. The photosynthetic characteristics and transpiration rate of Iris pseudacorus L. were significantly correlated with the removal rate of permanganate index, NH4(+) -N and NO3(-) -N (p < 0.05). The SPAD value of Iris pseudacorus L. was also influenced by substrates, and SPAD value of Iris pseudacorus L. in soil was high (58.92), followed by mixture soil, sand and organic matter, that of Iris pseudacorus L. in sand was the lowest (51.14). The significant correlation between the SPAD value of Iris pseudacorus L. and the photosynthetic characteristics, transpiration rate, NH(+) -N was also found (p < 0.05). The SPAD vale of Iris pseudacorus L. in different substrates was different, which was used to monitored operation condition of the removal rate of nitrogen in constructed wetland.

  3. The impact of cell-specific absorption properties on the correlation of electron transport rates measured by chlorophyll fluorescence and photosynthetic oxygen production in planktonic algae.

    PubMed

    Blache, Ulrich; Jakob, Torsten; Su, Wanwen; Wilhelm, Christian

    2011-08-01

    Photosynthesis-irradiance (P-E)-curves describe the photosynthetic performance of autotrophic organisms. From these P-E-curves the photosynthetic parameters α-slope, P(max), and E(k) can be deduced which are often used to characterize and to compare different organisms or organisms in acclimation to different environmental conditions. Particularly, for in situ-measurements of P-E curves of phytoplankton the analysis of variable chlorophyll fluorescence proved its potential as a sensitive and rapid method. By using Chlorella vulgaris (Trebouxiophyceae), Nannochloropsis salina (Eustigmatophyceae), Skeletonema costatum and Cyclotella meneghiniana (Bacillariophyceae), the present study investigated the influence of cellular bio-optical properties on the correlation of the photosynthetic parameters derived from fluorescence-based P-E-curves with photosynthetic parameters obtained from the measurement of oxygen evolution. It is demonstrated that small planktonic algae show a wide range of cellular absorptivity which was subject to species-specifity, growth stage and environmental conditions, e.g. nutrient limitation. This variability in bio-optical properties resulted in a great deviation of relative electron transport rates (rETRs) from oxygen-based photosynthesis rates. Thus, the photosynthetic parameters α-slope and P(max) derived from rETRs strongly depend on the specific cellular absorptivity and cannot be used to compare the photosynthetic performance of cells with different optical properties. However, it was shown that E(k) is independent of cellular absorptivity and could be used to compare samples with unknown optical properties. PMID:21571541

  4. The impact of cell-specific absorption properties on the correlation of electron transport rates measured by chlorophyll fluorescence and photosynthetic oxygen production in planktonic algae.

    PubMed

    Blache, Ulrich; Jakob, Torsten; Su, Wanwen; Wilhelm, Christian

    2011-08-01

    Photosynthesis-irradiance (P-E)-curves describe the photosynthetic performance of autotrophic organisms. From these P-E-curves the photosynthetic parameters α-slope, P(max), and E(k) can be deduced which are often used to characterize and to compare different organisms or organisms in acclimation to different environmental conditions. Particularly, for in situ-measurements of P-E curves of phytoplankton the analysis of variable chlorophyll fluorescence proved its potential as a sensitive and rapid method. By using Chlorella vulgaris (Trebouxiophyceae), Nannochloropsis salina (Eustigmatophyceae), Skeletonema costatum and Cyclotella meneghiniana (Bacillariophyceae), the present study investigated the influence of cellular bio-optical properties on the correlation of the photosynthetic parameters derived from fluorescence-based P-E-curves with photosynthetic parameters obtained from the measurement of oxygen evolution. It is demonstrated that small planktonic algae show a wide range of cellular absorptivity which was subject to species-specifity, growth stage and environmental conditions, e.g. nutrient limitation. This variability in bio-optical properties resulted in a great deviation of relative electron transport rates (rETRs) from oxygen-based photosynthesis rates. Thus, the photosynthetic parameters α-slope and P(max) derived from rETRs strongly depend on the specific cellular absorptivity and cannot be used to compare the photosynthetic performance of cells with different optical properties. However, it was shown that E(k) is independent of cellular absorptivity and could be used to compare samples with unknown optical properties.

  5. Thermal responses of Symbiodinium photosynthetic carbon assimilation

    NASA Astrophysics Data System (ADS)

    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.

  6. Laser remote monitoring of plant photosynthetic activity

    NASA Astrophysics Data System (ADS)

    Barbini, Roberto; Colao, Francesco; Fantoni, Roberta; Palucci, Antonio; Ribezzo, Sergio

    1995-11-01

    Laboratory measurements of laser induced chlorophyll fluorescence kinetics (Kautsky effect) on dark-adapted vegetation targets (maize, pine-tree) have been performed with a lidar fluorosensor by superimposing probe pulses upon an actinic light. The collected induction curves (fast rise and slow decline) have been used to reveal the occurrence of stresses and the damage produced by a pine-tree parasite. A new two-pulse LIF (laser induced fluorescence) methodology has been investigated both theoretically and experimentally, in view of remotely monitoring the plant photosynthetic activity. This technique may yield information upon the in-vivo photosynthetic processes of plants, revealing a possible stress status (nutrients depletion, presence of herbicides, photoinhibition, etc.). The lidar apparatus used contains two laser sources in order to differentially measure the chlorophyll fluorescence by means of a laser pump-and-probe technique. In fact LIF signals in the red chlorophyll band 690 nm may provide in-vivo information upon photosynthesis process in high order plants and algae. Laser pump-and-probe experimental tests, with excitation 355 nm or 532 nm, already detect the presence of herbicides, and the effects of plant exposure to thermal stresses and to low levels of gaseous pollutants. Laser measured fluorescence yields (Y) have been found to be consistent with those obtained by an in-situ fluorimeter (PAM). With proper choices of experimental parameters (pump and probe laser intensities), Y approaches the theoretical value expected for a healthy dark-adapted plant.

  7. Respiratory processes in non-photosynthetic plastids

    PubMed Central

    Renato, Marta; Boronat, Albert; Azcón-Bieto, Joaquín

    2015-01-01

    Chlororespiration is a respiratory process located in chloroplast thylakoids which consists in an electron transport chain from NAD(P)H to oxygen. This respiratory chain involves the NAD(P)H dehydrogenase complex, the plastoquinone pool and the plastid terminal oxidase (PTOX), and it probably acts as a safety valve to prevent the over-reduction of the photosynthetic machinery in stress conditions. The existence of a similar respiratory activity in non-photosynthetic plastids has been less studied. Recently, it has been reported that tomato fruit chromoplasts present an oxygen consumption activity linked to ATP synthesis. Etioplasts and amyloplasts contain several electron carriers and some subunits of the ATP synthase, so they could harbor a similar respiratory process. This review provides an update on the study about respiratory processes in chromoplasts, identifying the major gaps that need to be addressed in future research. It also reviews the proteomic data of etioplasts and amyloplasts, which suggest the presence of a respiratory electron transport chain in these plastids. PMID:26236317

  8. Photosynthetic water splitting: 1987 annual report

    SciTech Connect

    Greenbaum, E.

    1988-01-01

    This document is an annual report of photosynthetic water splitting for the production of hydrogen and oxygen. Unicellular green algae are capable of evolving molecular hydrogen in the presence of carbon dioxide. Controlling factors that determine hydrogen evolution are either temperature or light intensity. Also, mutants of the green alga Chlamydomonas are capable of evolving hydrogen in the presence of carbon dioxide. The significance of these discoveries is that the presence of carbon dioxide (or bicarbonate) is a key factor in determining the activity of the Photosystem II water splitting complex. Second, a new advance in oxygen sensor technology has been made that, for the first time, allows the absolute measurement of photosynthetically evolved oxygen from a single colony of microalgae growing on a solidified agar medium. The key aspect of this electrochemical sensor is the utilization of ultra-pure potassium hydroxide as the electrolyte and a recognition of the role that electrolyte impurities play in contributing to base line noise. 9 refs., 8 figs., 2 tabs.

  9. Respiratory processes in non-photosynthetic plastids.

    PubMed

    Renato, Marta; Boronat, Albert; Azcón-Bieto, Joaquín

    2015-01-01

    Chlororespiration is a respiratory process located in chloroplast thylakoids which consists in an electron transport chain from NAD(P)H to oxygen. This respiratory chain involves the NAD(P)H dehydrogenase complex, the plastoquinone pool and the plastid terminal oxidase (PTOX), and it probably acts as a safety valve to prevent the over-reduction of the photosynthetic machinery in stress conditions. The existence of a similar respiratory activity in non-photosynthetic plastids has been less studied. Recently, it has been reported that tomato fruit chromoplasts present an oxygen consumption activity linked to ATP synthesis. Etioplasts and amyloplasts contain several electron carriers and some subunits of the ATP synthase, so they could harbor a similar respiratory process. This review provides an update on the study about respiratory processes in chromoplasts, identifying the major gaps that need to be addressed in future research. It also reviews the proteomic data of etioplasts and amyloplasts, which suggest the presence of a respiratory electron transport chain in these plastids.

  10. Abundance and patterns of transparent exopolymer particles (TEP) in Arctic floodplain lakes of the Mackenzie River Delta

    NASA Astrophysics Data System (ADS)

    Chateauvert, C. Adam; Lesack, Lance F. W.; Bothwell, Max L.

    2012-12-01

    The Mackenzie River Delta is a lake-rich arctic floodplain that receives high inputs of dissolved organic matter (DOM) and suspended particulates from allochthonous and autochthonous sources, and may transfer carbon from dissolved to particulate phase via in situ formation of transparent exopolymer particles (TEP). TEP provides food for grazers, surfaces for bacteria, and increased potential for aggregation and sedimentation of organic matter. During open water 2006, we tracked TEP abundances in three Delta lakes representing gradients that include declining river-to-lake connection times, increasing levels of dissolved organic carbon (DOC), and declining chromophoric-DOM (CDOM). Unexpectedly, TEP abundances were highest immediately after the flood, when autochthonous autotrophic production was at a seasonal low and CDOM a seasonal high. Moreover, the lake with the strongest riverine influence and lowest levels of autochthonous autotrophic production had the highest mean TEP-carbon (TEP-C) concentrations among the lakes. The mean proportion of particulate organic carbon (POC) represented by TEP-C increased with increasing river connection time, and appears to represent a substantial proportion of POC in Mackenzie Delta Lakes. Unexpectedly, the TEP gradient was most strongly related to CDOM (river water source) rather than overall DOC. Variations in CDOM accounted for 53% of TEP-C variation among the lakes, indicating allochthonous matter was the most important source of TEP. DOC release from in situ macrophytes during periods of high photosynthesis may contribute to TEP formation in the lake with lowest riverine influence, but pH levels >9.5 driven by the high photosynthetic rates complicate the interpretation of results from this lake.

  11. Functional Inactivation of Putative Photosynthetic Electron Acceptor Ferredoxin C2 (FdC2) Induces Delayed Heading Date and Decreased Photosynthetic Rate in Rice.

    PubMed

    Zhao, Juan; Qiu, Zhennan; Ruan, Banpu; Kang, Shujing; He, Lei; Zhang, Sen; Dong, Guojun; Hu, Jiang; Zeng, Dali; Zhang, Guangheng; Gao, Zhenyu; Ren, Deyong; Hu, Xingming; Chen, Guang; Guo, Longbiao; Qian, Qian; Zhu, Li

    2015-01-01

    Ferredoxin (Fd) protein as unique electron acceptor, involved in a variety of fundamental metabolic and signaling processes, which is indispensable for plant growth. The molecular mechanisms of Fd such as regulation of electron partitioning, impact of photosynthetic rate and involvement in the carbon fixing remain elusive in rice. Here we reported a heading date delay and yellowish leaf 1 (hdy1) mutant derived from Japonica rice cultivar "Nipponbare" subjected to EMS treatment. In the paddy field, the hdy1 mutant appeared at a significantly late heading date and had yellow-green leaves during the whole growth stage. Further investigation indicated that the abnormal phenotype of hdy1 was connected with depressed pigment content and photosynthetic rate. Genetic analysis results showed that the hdy1 mutant phenotype was caused by a single recessive nuclear gene mutation. Map-based cloning revealed that OsHDY1 is located on chromosome 3 and encodes an ortholog of the AtFdC2 gene. Complementation and overexpression, transgenic plants exhibited the mutant phenotype including head date, leaf color and the transcription levels of the FdC2 were completely rescued by transformation with OsHDY1. Real-time PCR revealed that the expression product of OsHDY1 was detected in almost all of the organs except root, whereas highest expression levels were observed in seeding new leaves. The lower expression levels of HDY1 and content of iron were detected in hdy1 than WT's. The FdC2::GFP was detected in the chloroplasts of rice. Real-time PCR results showed that the expression of many photosynthetic electron transfer related genes in hdy1 were higher than WT. Our results suggest that OsFdC2 plays an important role in photosynthetic rate and development of heading date by regulating electron transfer and chlorophyll content in rice.

  12. Functional Inactivation of Putative Photosynthetic Electron Acceptor Ferredoxin C2 (FdC2) Induces Delayed Heading Date and Decreased Photosynthetic Rate in Rice.

    PubMed

    Zhao, Juan; Qiu, Zhennan; Ruan, Banpu; Kang, Shujing; He, Lei; Zhang, Sen; Dong, Guojun; Hu, Jiang; Zeng, Dali; Zhang, Guangheng; Gao, Zhenyu; Ren, Deyong; Hu, Xingming; Chen, Guang; Guo, Longbiao; Qian, Qian; Zhu, Li

    2015-01-01

    Ferredoxin (Fd) protein as unique electron acceptor, involved in a variety of fundamental metabolic and signaling processes, which is indispensable for plant growth. The molecular mechanisms of Fd such as regulation of electron partitioning, impact of photosynthetic rate and involvement in the carbon fixing remain elusive in rice. Here we reported a heading date delay and yellowish leaf 1 (hdy1) mutant derived from Japonica rice cultivar "Nipponbare" subjected to EMS treatment. In the paddy field, the hdy1 mutant appeared at a significantly late heading date and had yellow-green leaves during the whole growth stage. Further investigation indicated that the abnormal phenotype of hdy1 was connected with depressed pigment content and photosynthetic rate. Genetic analysis results showed that the hdy1 mutant phenotype was caused by a single recessive nuclear gene mutation. Map-based cloning revealed that OsHDY1 is located on chromosome 3 and encodes an ortholog of the AtFdC2 gene. Complementation and overexpression, transgenic plants exhibited the mutant phenotype including head date, leaf color and the transcription levels of the FdC2 were completely rescued by transformation with OsHDY1. Real-time PCR revealed that the expression product of OsHDY1 was detected in almost all of the organs except root, whereas highest expression levels were observed in seeding new leaves. The lower expression levels of HDY1 and content of iron were detected in hdy1 than WT's. The FdC2::GFP was detected in the chloroplasts of rice. Real-time PCR results showed that the expression of many photosynthetic electron transfer related genes in hdy1 were higher than WT. Our results suggest that OsFdC2 plays an important role in photosynthetic rate and development of heading date by regulating electron transfer and chlorophyll content in rice. PMID:26598971

  13. Influence of the Quantity and Quality of Light on Photosynthetic Periodicity in Coral Endosymbiotic Algae

    PubMed Central

    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. New bio-inorganic photo-electronic devices based on photosynthetic proteins

    NASA Astrophysics Data System (ADS)

    Lebedev, Nikolai; Spano, Anthony; Trammell, Scott; Griva, Igor; Tsoi, Stanislav; Schnur, Joel M.

    2007-09-01

    Construction of efficient devices for light energy conversion, including photo-electronic and photovoltaic (PV) devices, is a big challenge for the current science and technology that will have important economic consequences. Most of the modern photovoltaic devices are based on silicon. An innovative approach to the construction of photovoltaic devices is the utilization of biological systems and principles designed for similar purposes by Nature. Biological electronic devices, proteins, have extremely high efficiency, precise spatial organization, and are inexpensive in fabrication. They can be fused with inorganic and organic materials such as conductors, semiconductors, conductive polymers, or quantum dots. The photosynthetic reaction center protein (RC) is one of the most advanced photo-electronic devices developed by Nature. It has nearly 100% quantum yield of primary charge separation, an extremely fast operation time (about 10 -9 s, or operation frequency of ~10 9 Hz), and a very efficient stabilization of separated charges (ratio of charge separation rate to that of charge recombination is about 10 4). The charge separation and stabilization takes place in a complex of 7 nm size and leads to the formation of a local electric field of about 10 6 V/cm. A coupling of photosynthetic RC to inorganic electrodes is attractive for the identification of the mechanisms of inter-protein electron transfer (ET) and for the possible applications in the construction of protein-based innovative photoelectronic and photovoltaic devices. In this presentation we describe a new type of hybrid bio-inorganic photoelectronic devices based on photosynthetic proteins and inorganic materials. Using genetically engineered bacterial RCs and specifically synthesized organic linkers, we were able to construct self-assembled and aligned protein complexes with various metals and semiconductors, including gold, indium tin oxide (ITO), nanoporous TiO II, highly ordered pyrolytic graphite

  15. Relevance of the photosynthetic reaction center from purple bacteria to the structure of photosystem II

    SciTech Connect

    Michel, H.; Deisenhofer, J.

    1988-01-12

    Photosynthetic organisms are able to oxidize organic or inorganic compounds upon the absorption of light, and they use the extracted electron for the fixation of carbon dioxide. The most important oxidation product is oxygen due to the splitting of water. In eukaryotes these processes occur in photosystem II of chloroplasts. Among prokaryotes photosynthetic oxygen evolution is restricted to cyanobacteria and prochloron-type organisms. How water is split in the oxygen-evolving complex of photosystem II belongs to the most important question to be answered. The primary charge separation occurs in the reaction center of photosystem II. This reaction center is a complex consisting of peripheral and integral membrane proteins, several chlorophyll A molecules, two pheophytin A molecules, two and three plastoquinone molecules, and one non-heme iron atom. The location of the photosystem II reaction center is still a matter of debate. Nakatani et al. (l984) concluded from fluorescence measurements that a protein of apparent molecular weight 47,000 (CP47) is the apoprotein of the photosystem II reaction center. A different view emerged from work with the photosynthetic reaction centers from the purple bacteria. The amino acid sequence of the M subunit of the reaction center from Phodopseudomonas (Rps.) sphaeroides has sequence homologies with the D1 protein from spinach. A substantial amount of structural information can be obtained with the reaction center from Rhodopseudomonas viridis, which can be crystallized. Here the authors discuss the structure of the photosynthetic reaction center from the purple bacterium Rps. viridis and describe the role of those amino acids that are conserved between the bacterial and photosystem II reaction center.

  16. Abundances in Sagittarius Stars

    NASA Astrophysics Data System (ADS)

    Bonifacio, P.; Zaggia, S.; Sbordone, L.; Santin, P.; Monaco, L.; Monai, S.; Molaro, P.; Marconi, G.; Girardi, L.; Ferraro, F.; di Marcantonio, P.; Caffau, E.; Bellazzini, M.

    The Sagittarius dwarf spheroidal is a very complex galaxy, which has undergone prolonged star formation. From the very first high resolution chemical analysis of Sgr stars, conducted using spectra obtained during the commissioning of UVES at VLT, it was clear that the star had undergone a high level of chemical processing, at variance with most of the other Local Group dwarf spheroidals. Thanks to FLAMES at VLT we now have accurate metallicities and abundances of alpha-chain elements for about 150 stars, which provide the first reliable metallicity distribution for this galaxy. Besides the already known high metallicity tail the existence of a metal-poor population has also been highlighted, although an assessment of the fraction of Sgr stars which belong to this population requires a larger sample. From our data it is also obvious that Sagittarius is a nucleated galaxy and that the centre of the nucleus coincides with M54, as already shown by Monaco et al.

  17. Self-assembly and structural-functional flexibility of oxygenic photosynthetic machineries: personal perspectives.

    PubMed

    Garab, Győző

    2016-01-01

    This short review, with a bit of historical aspect and a strong personal bias and emphases on open questions, is focusing on the (macro-)organization and structural-functional flexibilities of the photosynthetic apparatus of oxygenic photosynthetic organisms at different levels of the structural complexity-selected problems that have attracted most my attention in the past years and decades. These include (i) the anisotropic organization of the pigment-protein complexes and photosynthetic membranes-a basic organizing principle of living matter, which can, and probably should be adopted to intelligent materials; (ii) the organization of protein complexes into chiral macrodomains, large self-assembling highly organized but structurally flexible entities with unique spectroscopic fingerprints-structures, where, important, high-level regulatory functions appear to 'reside'; (iii) a novel, dissipation-assisted mechanism of structural changes, based on a thermo-optic effect: ultrafast thermal transients in the close vicinity of dissipation of unused excitation energy, which is capable of inducing elementary structural changes; it makes plants capable of responding to excess excitation with reaction rates proportional to the overexcitation above the light-saturation of photosynthesis; (iv) the 3D ultrastructure of the granum-stroma thylakoid membrane assembly and other multilamellar membrane systems, and their remodelings-associated with regulatory mechanisms; (v) the molecular organization and structural-functional plasticity of the main light-harvesting complex of plants, in relation to their crystal structure and different in vivo and in vitro states; and (vi) the enigmatic role of non-bilayer lipids and lipid phases in the bilayer thylakoid membrane-warranting its high protein content and contributing to its structural flexibility. PMID:26494196

  18. Structure and Excitation Transfer Pathways in the Chlorophyll-Carotenoid Aggregate of the Photosynthetic Unit of Purple Bacteria

    NASA Astrophysics Data System (ADS)

    Schulten, Klaus

    1998-03-01

    The absorption of light by light harvesting complexes and transfer of electronic excitation to the photosynthetic reaction center (RC) has been investigated on the basis of an atomic level model of the so-called photosynthetic unit of the photosynthetic bacterium Rb. sphaeroides. The photosynthetic unit combines in the intracytoplasmic membrane a nanometric (20-100 nm) assembly of three protein complexes: (i) the photosynthetic reaction center, (ii) a ring-shaped light harvesting complex LH-I, and (iii) multiple copies of a similar complex, LH-II. The unit has been modeled using the known structure of LH-II of Rs. molischianum. The lecture describes in detail the organization of chromophores involved in primary light absorption and excitation transfer: a hierarchy of ring-shaped chlorophyl aggregates with attached carotenoids. A quantum-mechanical description of the entire light harvesting process is developed employing electron structure calculations of individual and aggregated chlorophylls and carotenoids and associated effective Hamiltonian descriptions. The transfer times calculated, ranging between 100 fs and 100 ps for various processes, are found in close agreement with measured transfer rates. The results suggest that excitons are the key carriers of the excitation transfered. The photoprotection of chlorophylls by chlorophylls through triplet excitation transfer is also described.

  19. Comparative genomic analysis of the Hsp70s from five diverse photosynthetic eukaryotes

    PubMed Central

    Renner, Tanya; Waters, Elizabeth R.

    2007-01-01

    We have identified 24 members of the DnaK subfamily of heat shock 70 proteins (Hsp70s) in the complete genomes of 5 diverse photosynthetic eukaryotes. The Hsp70s are a ubiquitous protein family that is highly conserved across all domains of life. Eukaryotic Hsp70s are found in a number of subcellular compartments in the cell: cytoplasm, mitochondrion (MT), chloroplast (CP), and endoplasmic reticulum (ER). Although the Hsp70s have been the subject of intense study in model organisms, very little is known of the Hsp70s from early diverging photosynthetic lineages. The sequencing of the complete genomes of Thalassiosira pseudonana (a diatom), Cyanidioschyzon merolae (a red alga), and 3 green algae (Chlamydomonas reinhardtii, Ostreococcus lucimarinus, Ostreococcus tauri) allow us to conduct comparative genomics of the Hsp70s present in these diverse photosynthetic eukaryotes. We have found that the distinct lineages of Hsp70s (MT, CP, ER, and cytoplasmic) each have different evolutionary histories. In general, evolutionary patterns of the mitochondrial and endoplasmic reticulum Hsp70s are relatively stable even among very distantly related organisms. This is not true of the chloroplast Hsp70s and we discuss the distinct evolutionary patterns between “green” and “red” plastids. Finally, we find that, in contrast to the angiosperms Arabidopsis thaliana and Oryza sativa that have numerous cytoplasmic Hsp70, the 5 algal species have only 1 cytoplasmic Hsp70 each. The evolutionary and functional implications of these differences are discussed. PMID:17688196

  20. [Influence of photosynthetic parameters on leaf longevity].

    PubMed

    Vasfilov, S P

    2015-01-01

    Higher plants show a wide range of leaf lifespan (LL) variability. LL is calculated as a sum of functional LL(f) (corresponding to the time of active photosynthesis and CO2 accumulation in the leaf) and nonfunctional LL(n) (the time of photosynthetic activity absence). For evergreen species of boreal zones, LL(n) corresponds to the period of winter rest. Photosynthetic potential of leaf (PPL), interpreted as the maximum possible amount of CO2 that can be fixed during its life, can be estimated on the basis of maximum photosynthesis rate (P(a)) dynamics during LL(f); the maximum (P(a max)) being achieved in mature leaf. Photosynthetic potential depends on LL(f) more strongly than on P(a max). The PPL/LL(f) ratio is indicative of the rate of PPL realization over leaf lifespan. As LL(f) shows strong positive correlation with LL, the latter parameter can also characterize the rate of PPL realization. Long LL(f) in evergreen species provides higher PPL, which is advantageous by comparison with deciduous ones. In evergreen species, the PPL itself is realized slower than in deciduous ones. The increase in LL(f) and LL is accompanied by the increase in leaf constructional cost (LCC(a)) as well as the decrease in photosynthesis rate. At that, photosynthesis rate per unit of dry weight (P(m)) decreases much faster than that per unit of leaf area (P(a)). Apparently, when considering dry leaf weight, the apoplast share seems to be much higher in long-living leaves of evergreen species than in short-living leaves of deciduous species. The leaf payback (LP) may be stabilized by unidirectional shifts in PPL and LCC(a). Species with short/long LL(f) and high/low PPL realization rate are typical for early/late succession stages and for habitats with the environmental conditions favorable/adverse for photosynthesis and growth. If the conditions for photosynthesis and growth are favorable, high PPL realization rate provides advantage in competition. The PPL realization rate is

  1. New bio-inorganic photo-electronic devices based on photosynthetic proteins

    NASA Astrophysics Data System (ADS)

    Lebedev, Nikolai; Trammell, Scott; Griva, Igor; Spano, Anthony

    2006-10-01

    The photosynthetic reaction center (RC) is one of the most advanced light sensing and energy converting materials developed by Nature. Its coupling with inorganic surfaces is attractive for the identification of the mechanisms of interprotein electron transfer (ET) and for the possible applications for the construction of protein-based innovative photoelectronic and photovoltaic devices. Using genetically engineered bacterial RC proteins and specifically synthesized organic linkers, we were able to construct self-assembled and aligned biomolecular surfaces on various electrodes, including gold, carbon, indium tin oxide (ITO), highly ordered pyrrolytic graphite (HOPG) and carbon nanotube (CNT) arrays. Our results show that, after immobilization on the electrodes, the photosynthetic RC can operate as a highly efficient photosensor, optical switch, and photovoltaic device.

  2. Mobile hydrogen carbonate acts as proton acceptor in photosynthetic water oxidation

    PubMed Central

    Koroidov, Sergey; Shevela, Dmitriy; Shutova, Tatiana; Samuelsson, Göran; Messinger, Johannes

    2014-01-01

    Cyanobacteria, algae, and plants oxidize water to the O2 we breathe, and consume CO2 during the synthesis of biomass. Although these vital processes are functionally and structurally well separated in photosynthetic organisms, there is a long-debated role for CO2/ in water oxidation. Using membrane-inlet mass spectrometry we demonstrate that acts as a mobile proton acceptor that helps to transport the protons produced inside of photosystem II by water oxidation out into the chloroplast’s lumen, resulting in a light-driven production of O2 and CO2. Depletion of from the media leads, in the absence of added buffers, to a reversible down-regulation of O2 production by about 20%. These findings add a previously unidentified component to the regulatory network of oxygenic photosynthesis and conclude the more than 50-y-long quest for the function of CO2/ in photosynthetic water oxidation. PMID:24711433

  3. Heterologous expression of Arabidopsis phytochrome B in transgenic potato influences photosynthetic performance and tuber development

    SciTech Connect

    Thiele, A.; Herold, M.; Lenk, I.; Gatz, C. . Albrecht von Haller Inst. fuer Pflanzenwissenschaften); Quail, P.H. )

    1999-05-01

    Transgenic potato (Solanum tuberosum) plants expressing Arabidopsis phytochrome B were characterized morphologically and physiologically under white light in a greenhouse to explore their potential for improved photosynthesis and higher tuber yields. As expected, overexpression of functional phytochrome B caused pleiotropic effects such as semidwarfism, decreased apical dominance, a higher number of smaller but thicker leaves, and increased pigmentation. Because of increased numbers of chloroplasts in elongated palisade cells, photosynthesis per leaf area and in each individual plant increased. In addition, photosynthesis was less sensitive to photoinactivation under prolonged light stress. The beginning of senescence was not delayed, but deceleration of chlorophyll degradation extended the lifetime of photosynthetically active plants. Both the higher photosynthetic performance and the longer lifespan of the transgenic plants allowed greater biomass production, resulting in extended underground organs with increased tuber yields.

  4. Structure, Function, and Regulation of Antenna Complexes of Green Photosynthetic Bacteria

    SciTech Connect

    Robert E. Blankenship

    2001-04-27

    This project is concerned with the structure and function of the chlorosome antennas found in green photosynthetic bacteria. Chlorosomes are ellipsoidal structures attached to the cytoplasmic side of the inner cell membrane. These antenna complexes provide a very large absorption cross section for light capture. Evidence is overwhelming that the chlorosome represents a very different type of antenna from that found in any other photosynthetic system yet studied. It is now clear that chlorosomes do not contain traditional pigment-proteins, in which the pigments bind to specific sites on proteins. Instead, the chlorosome pigments are organized in vivo into pigment oligomers in which direct pigment-pigment interactions are of dominant importance. Our group has used a multidisciplinary approach to investigate this unique system, including model systems, ultrafast spectroscopy, molecular biology, protein chemistry and X-ray crystallography.

  5. Mobile hydrogen carbonate acts as proton acceptor in photosynthetic water oxidation.

    PubMed

    Koroidov, Sergey; Shevela, Dmitriy; Shutova, Tatiana; Samuelsson, Göran; Messinger, Johannes

    2014-04-29

    Cyanobacteria, algae, and plants oxidize water to the O2 we breathe, and consume CO2 during the synthesis of biomass. Although these vital processes are functionally and structurally well separated in photosynthetic organisms, there is a long-debated role for CO2/ in water oxidation. Using membrane-inlet mass spectrometry we demonstrate that acts as a mobile proton acceptor that helps to transport the protons produced inside of photosystem II by water oxidation out into the chloroplast's lumen, resulting in a light-driven production of O2 and CO2. Depletion of from the media leads, in the absence of added buffers, to a reversible down-regulation of O2 production by about 20%. These findings add a previously unidentified component to the regulatory network of oxygenic photosynthesis and conclude the more than 50-y-long quest for the function of CO2/ in photosynthetic water oxidation. PMID:24711433

  6. Actinide abundances in ordinary chondrites

    NASA Technical Reports Server (NTRS)

    Hagee, B.; Bernatowicz, T. J.; Podosek, F. A.; Johnson, M. L.; Burnett, D. S.

    1990-01-01

    Measurements of actinide and light REE (LREE) abundances and of phosphate abundances in equilibrated ordinary chondrites were obtained and were used to define the Pu abundance in the solar system and to determine the degree of variation of actinide and LREE abundances. The results were also used to compare directly the Pu/U ratio with the earlier obtained ratio determined indirectly, as (Pu/Nd)x(Nd/U), assuming that Pu behaves chemically as a LREE. The data, combined with high-accuracy isotope-dilution data from the literature, show that the degree of gram-scale variability of the Th, U, and LREE abundances for equilibrated ordinary chondrites is a factor of 2-3 for absolute abundances and up to 50 percent for relative abundances. The observed variations are interpreted as reflecting the differences in the compositions and/or proportions of solar nebula components accreted to ordinary chondrite parent bodies.

  7. Energy Transfer Dynamics in an RC-LH1-PufX Tubular Photosynthetic Membrane

    PubMed Central

    Hsin, Jen; Strümpfer, Johan; Sener, Melih; Qian, Pu; Hunter, C. Neil; Schulten, Klaus

    2010-01-01

    Light absorption and the subsequent transfer of excitation energy are the first two steps of the photosynthetic process, carried out by protein-bound pigments, mainly bacteriochlorophylls (BChls), in photosynthetic bacteria. BChls are anchored in light-harvesting (LH) complexes, such as light-harvesting complex I (LH1), which directly associates with the reaction center (RC), forming the RC-LH1 core complex. In Rhodobacter sphaeroides, RC-LH1 core complexes contain an additional protein, PufX, and assemble into dimeric RC-LH1-PufX core complexes. In the absence of light-harvesting complexes II, the former complexes can aggregate into a helically ordered tubular photosynthetic membrane. We examined the excitation transfer dynamics in a single RC-LH1-PufX core complex dimer using the hierarchical equations of motion for dissipative quantum dynamics that accurately, yet computationally costly, treat the coupling between BChls and their protein environment. A widely employed description, generalized Förster theory, was also used to calculate the transfer rates of the same excitonic system in order to verify the accuracy of this computationally cheap method. Additionally, in light of the structural uncertainties in the Rhodobacter sphaeroides RC-LH1-PufX core complex, geometrical alterations were introduced in the BChl organization. It is shown that the energy transfer dynamics is not affected by the considered changes in the BChl organization, and that generalized Förster theory provides accurate transfer rates. An all-atom model for a tubular photosynthetic membrane is then constructed on the basis of electron microscopy data, and the overall energy transfer properties of this membrane are computed. PMID:21152381

  8. Structural basis of photosynthetic water-splitting

    SciTech Connect

    Shen, Jian-Ren; Kawakami, Keisuke; Kamiya, Nobuo

    2013-12-10

    Photosynthetic water-splitting takes place in photosystem II (PSII), a membrane protein complex consisting of 20 subunits with an overall molecular mass of 350 kDa. The light-induced water-splitting reaction catalyzed by PSII not only converts light energy into biologically useful chemical energy, but also provides us with oxygen indispensible for sustaining oxygenic life on the earth. We have solved the structure of PSII at a 1.9 Å resolution, from which, the detailed structure of the Mn{sub 4}CaO{sub 5}-cluster, the catalytic center for water-splitting, became clear. Based on the structure of PSII at the atomic resolution, possible mechanism of light-induced water-splitting was discussed.

  9. Bioinspired hollow semiconductor nanospheres as photosynthetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Sun, Jianhua; Zhang, Jinshui; Zhang, Mingwen; Antonietti, Markus; Fu, Xianzhi; Wang, Xinchen

    2012-10-01

    Natural photosynthesis occurs in the thylakoid membrane where functional proteins and electron carriers are precisely arranged to efficiently convert sunlight into a chemical potential between the two membrane sides, via charge separation and electron transport chains, for use in oxygen generation and CO2 fixation. These light-harvesting complexes and cofactors have been actively mimicked using dyes, semiconductors and catalytic nanoparticles. However, the photosynthetic scaffold that optimizes both the capture and distribution of light and separates both the oxidative and reductive species has been mimicked much less often, especially using polymer substances. Here we report the synthesis of hollow nanospheres sized in the optical range and made of a robust semiconductor, melon or carbon-nitride polymer. These hollow nanospheres are shown to function as both light-harvesting antennae and nanostructured scaffolds that improve photoredox catalysis, which was determined to have a 7.5% apparent quantum yield via a hydrogen-generation assay.

  10. Hydrogen productivity by photosynthetic water splitting

    SciTech Connect

    Greenbaum, E.

    1990-01-01

    This paper reviews recent progress in the field of hydrogen production by photosynthetic water splitting for both in vitro and in vivo systems. Absolute thermodynamic efficiencies of conversion of light energy into energy of molecular hydrogen by intact microalgae have been measured with an original physical measuring technique using a tin-oxide semiconducting gas sensor. Thin films of microalgae comprising 5-20 cellular monolayers have been entrapped on filter paper, thereby constraining them in a well-defined circular geometry. Based on absolute light absorption of visible polychromatic illumination in the low-intensity region of the light saturation curve, conversion efficiencies of 6 to 24% have been obtained. These values are the highest ever measured for hydrogen evolution by green algae. 34 refs., 7 figs., 1 tab.

  11. Phytoplankton Strategies for Photosynthetic Energy Allocation

    NASA Astrophysics Data System (ADS)

    Halsey, Kimberly H.; Jones, Bethan M.

    2015-01-01

    Phytoplankton physiology is dynamic and highly responsive to the environment. Phytoplankton acclimate to changing environmental conditions by a complex reallocation of carbon and energy through metabolic pathways to optimize growth. Considering the tremendous diversity of phytoplankton, it is not surprising that different phytoplankton taxa use different strategies to partition carbon and energy resources. It has therefore been satisfying to discover that general principles of energetic stoichiometry appear to govern these complex processes and can be broadly applied to interpret phytoplankton distributions, productivity, and food web dynamics. The expectation of future changes in aquatic environments brought on by climate change warrants gathering knowledge about underlying patterns of photosynthetic energy allocation and their impacts on community structure and ecosystem productivity.

  12. Structure and function of isozymes: Evolutionary aspects and role of oxygen in eucaryotic organisms

    NASA Technical Reports Server (NTRS)

    Satyanarayana, T.

    1985-01-01

    Oxygen is not only one of the most abundant elements on the Earth, but it is also one of the most important elements for life. In terms of composition, the feature of the atmosphere that most distinguishes Earth from other planets is the presence of abundant amounts of oxygen. The first forms of life may have been similar to present day anaerobic bacteria such as clostridium. The relationship between prokaryotes and eukaryotes, if any, has been a topic of much speculation. With only a few exceptions eukaryotes are oxygen-utilizing organisms. This research eukaryotes or eukaryotic biochemical processes requiring oxygen, could have arisen quite early in evolution and utilized the small quantities of photocatalytically produced oxygen which are thought to have been present on the Earth prior to the evolution of massive amounts of photosynthetically-produced oxygen.

  13. Blue-light-regulated transcription factor, Aureochrome, in photosynthetic stramenopiles.

    PubMed

    Takahashi, Fumio

    2016-03-01

    During the course of evolution through various endosymbiotic processes, diverse photosynthetic eukaryotes acquired blue light (BL) responses that do not use photosynthetic pathways. Photosynthetic stramenopiles, which have red algae-derived chloroplasts through secondary symbiosis, are principal primary producers in aquatic environments, and play important roles in ecosystems and aquaculture. Through secondary symbiosis, these taxa acquired BL responses, such as phototropism, chloroplast photo-relocation movement, and photomorphogenesis similar to those which green plants acquired through primary symbiosis. Photosynthetic stramenopile BL receptors were undefined until the discovery in 2007, of a new type of BL receptor, the aureochrome (AUREO), from the photosynthetic stramenopile alga, Vaucheria. AUREO has a bZIP domain and a LOV domain, and thus BL-responsive transcription factor. AUREO orthologs are only conserved in photosynthetic stramenopiles, such as brown algae, diatoms, and red tide algae. Here, a brief review is presented of the role of AUREOs as photoreceptors for these diverse BL responses and their biochemical properties in photosynthetic stramenopiles.

  14. Carbon Gain and Photosynthetic Response of Chrysanthemum to Photosynthetic Photon Flux Density Cycles 1

    PubMed Central

    Stoop, Johan M. H.; Willits, Dan H.; Peet, Mary M.; Nelson, Paul V.

    1991-01-01

    Most models of carbon gain as a function of photosynthetic irradiance assume an instantaneous response to increases and decreases in irradiance. High- and low-light-grown plants differ, however, in the time required to adjust to increases and decreases in irradiance. In this study the response to a series of increases and decreases in irradiance was observed in Chrysanthemum × morifolium Ramat. “Fiesta” and compared with calculated values assuming an instantaneous response. There were significant differences between high- and low-light-grown plants in their photosynthetic response to four sequential photosynthetic photon flux density (PPFD) cycles consisting of 5-minute exposures to 200 and 400 micromoles per square meter per second (μmol m−2s−1). The CO2 assimilation rate of high-light-grown plants at the cycle peak increased throughout the PPFD sequence, but the rate of increase was similar to the increase in CO2 assimilation rate observed under continuous high-light conditions. Low-light leaves showed more variability in their response to light cycles with no significant increase in CO2 assimilation rate at the cycle peak during sequential cycles. Carbon gain and deviations from actual values (percentage carbon gain over- or underestimation) based on assumptions of instantaneous response were compared under continuous and cyclic light conditions. The percentage carbon gain overestimation depended on the PPFD step size and growth light level of the leaf. When leaves were exposed to a large PPFD increase, the carbon gain was overestimated by 16 to 26%. The photosynthetic response to 100 μmol m−2 s−1 PPFD increases and decreases was rapid, and the small overestimation of the predicted carbon gain, observed during photosynthetic induction, was almost entirely negated by the carbon gain underestimation observed after a decrease. If the PPFD cycle was 200 or 400 μmol m−2 s−1, high- and low-light leaves showed a carbon gain overestimation of 25

  15. The post-Paleozoic chronology and mechanism of 13C depletion in primary marine organic matter

    NASA Technical Reports Server (NTRS)

    Popp, B. N.; Takigiku, R.; Hayes, J. M.; Louda, J. W.; Baker, E. W.

    1989-01-01

    Carbon-isotopic compositions of geoporphyrins have been measured from marine sediments of Mesozoic and Cenozoic age in order to elucidate the timing and extent of depletion of 13C in marine primary producers. These results indicate that the difference in isotopic composition of coeval marine carbonates and marine primary photosynthate was approximately 5 to 7 permil greater during the Mesozoic and early Cenozoic than at present. In contrast to the isotopic record of marine primary producers, isotopic compositions of terrestrial organic materials have remained approximately constant for this same interval of time. This difference in the isotopic records of marine and terrestrial organic matter is considered in terms of the mechanisms controlling the isotopic fractionation associated with photosynthetic fixation of carbon. We show that the decreased isotopic fractionation between marine carbonates and organic matter from the Early to mid-Cenozoic may record variations in the abundance of atmospheric CO2.

  16. Modelling occurrence and abundance of species when detection is imperfect

    USGS Publications Warehouse

    Royle, J. Andrew; Nichols, J.D.; Kery, M.

    2005-01-01

    Relationships between species abundance and occupancy are of considerable interest in metapopulation biology and in macroecology. Such relationships may be described concisely using probability models that characterize variation in abundance of a species. However, estimation of the parameters of these models in most ecological problems is impaired by imperfect detection. When organisms are detected imperfectly, observed counts are biased estimates of true abundance, and this induces bias in stated occupancy or occurrence probability. In this paper we consider a class of models that enable estimation of abundance/occupancy relationships from counts of organisms that result from surveys in which detection is imperfect. Under such models, parameter estimation and inference are based on conventional likelihood methods. We provide an application of these models to geographically extensive breeding bird survey data in which alternative models of abundance are considered that include factors that influence variation in abundance and detectability. Using these models, we produce estimates of abundance and occupancy maps that honor important sources of spatial variation in avian abundance and provide clearly interpretable characterizations of abundance and occupancy adjusted for imperfect detection.

  17. The Arabidopsis Thylakoid Chloride Channel AtCLCe Functions in Chloride Homeostasis and Regulation of Photosynthetic Electron Transport.

    PubMed

    Herdean, Andrei; Nziengui, Hugues; Zsiros, Ottó; Solymosi, Katalin; Garab, Győző; Lundin, Björn; Spetea, Cornelia

    2016-01-01

    Chloride ions can be translocated across cell membranes through Cl(-) channels or Cl(-)/H(+) exchangers. The thylakoid-located member of the Cl(-) channel CLC family in Arabidopsis thaliana (AtCLCe) was hypothesized to play a role in photosynthetic regulation based on the initial photosynthetic characterization of clce mutant lines. The reduced nitrate content of Arabidopsis clce mutants suggested a role in regulation of plant nitrate homeostasis. In this study, we aimed to further investigate the role of AtCLCe in the regulation of ion homeostasis and photosynthetic processes in the thylakoid membrane. We report that the size and composition of proton motive force were mildly altered in two independent Arabidopsis clce mutant lines. Most pronounced effects in the clce mutants were observed on the photosynthetic electron transport of dark-adapted plants, based on the altered shape and associated parameters of the polyphasic OJIP kinetics of chlorophyll a fluorescence induction. Other alterations were found in the kinetics of state transition and in the macro-organization of photosystem II supercomplexes, as indicated by circular dichroism measurements. Pre-treatment with KCl but not with KNO3 restored the wild-type photosynthetic phenotype. Analyses by transmission electron microscopy revealed a bow-like arrangement of the thylakoid network and a large thylakoid-free stromal region in chloroplast sections from the dark-adapted clce plants. Based on these data, we propose that AtCLCe functions in Cl(-) homeostasis after transition from light to dark, which affects chloroplast ultrastructure and regulation of photosynthetic electron transport.

  18. A compendium of temperature responses of Rubisco kinetic traits: variability among and within photosynthetic groups and impacts on photosynthesis modeling.

    PubMed

    Galmés, Jeroni; Hermida-Carrera, Carmen; Laanisto, Lauri; Niinemets, Ülo

    2016-09-01

    The present study provides a synthesis of the in vitro and in vivo temperature responses of Rubisco Michaelis-Menten constants for CO2 (Kc) and O2 (Ko), specificity factor (Sc,o) and maximum carboxylase turnover rate (kcatc) for 49 species from all the main photosynthetic kingdoms of life. Novel correction routines were developed for in vitro data to remove the effects of study-to-study differences in Rubisco assays. The compilation revealed differences in the energy of activation (∆Ha) of Rubisco kinetics between higher plants and other photosynthetic groups, although photosynthetic bacteria and algae were under-represented and very few species have been investigated so far. Within plants, the variation in Rubisco temperature responses was related to species' climate and photosynthetic mechanism, with differences in ∆Ha for kcatc among C3 plants from cool and warm environments, and in ∆Ha for kcatc and Kc among C3 and C4 plants. A negative correlation was observed among ∆Ha for Sc/o and species' growth temperature for all data pooled, supporting the convergent adjustment of the temperature sensitivity of Rubisco kinetics to species' thermal history. Simulations of the influence of varying temperature dependences of Rubisco kinetics on Rubisco-limited photosynthesis suggested improved photosynthetic performance of C3 plants from cool habitats at lower temperatures, and C3 plants from warm habitats at higher temperatures, especially at higher CO2 concentration. Thus, variation in Rubisco kinetics for different groups of photosynthetic organisms might need consideration to improve prediction of photosynthesis in future climates. Comparisons between in vitro and in vivo data revealed common trends, but also highlighted a large variability among both types of Rubisco kinetics currently used to simulate photosynthesis, emphasizing the need for more experimental work to fill in the gaps in Rubisco datasets and improve scaling from enzyme kinetics to realized

  19. A compendium of temperature responses of Rubisco kinetic traits: variability among and within photosynthetic groups and impacts on photosynthesis modeling.

    PubMed

    Galmés, Jeroni; Hermida-Carrera, Carmen; Laanisto, Lauri; Niinemets, Ülo

    2016-09-01

    The present study provides a synthesis of the in vitro and in vivo temperature responses of Rubisco Michaelis-Menten constants for CO2 (Kc) and O2 (Ko), specificity factor (Sc,o) and maximum carboxylase turnover rate (kcatc) for 49 species from all the main photosynthetic kingdoms of life. Novel correction routines were developed for in vitro data to remove the effects of study-to-study differences in Rubisco assays. The compilation revealed differences in the energy of activation (∆Ha) of Rubisco kinetics between higher plants and other photosynthetic groups, although photosynthetic bacteria and algae were under-represented and very few species have been investigated so far. Within plants, the variation in Rubisco temperature responses was related to species' climate and photosynthetic mechanism, with differences in ∆Ha for kcatc among C3 plants from cool and warm environments, and in ∆Ha for kcatc and Kc among C3 and C4 plants. A negative correlation was observed among ∆Ha for Sc/o and species' growth temperature for all data pooled, supporting the convergent adjustment of the temperature sensitivity of Rubisco kinetics to species' thermal history. Simulations of the influence of varying temperature dependences of Rubisco kinetics on Rubisco-limited photosynthesis suggested improved photosynthetic performance of C3 plants from cool habitats at lower temperatures, and C3 plants from warm habitats at higher temperatures, especially at higher CO2 concentration. Thus, variation in Rubisco kinetics for different groups of photosynthetic organisms might need consideration to improve prediction of photosynthesis in future climates. Comparisons between in vitro and in vivo data revealed common trends, but also highlighted a large variability among both types of Rubisco kinetics currently used to simulate photosynthesis, emphasizing the need for more experimental work to fill in the gaps in Rubisco datasets and improve scaling from enzyme kinetics to realized

  20. The Arabidopsis Thylakoid Chloride Channel AtCLCe Functions in Chloride Homeostasis and Regulation of Photosynthetic Electron Transport

    PubMed Central

    Herdean, Andrei; Nziengui, Hugues; Zsiros, Ottó; Solymosi, Katalin; Garab, Győző; Lundin, Björn; Spetea, Cornelia

    2016-01-01

    Chloride ions can be translocated across cell membranes through Cl− channels or Cl−/H+ exchangers. The thylakoid-located member of the Cl− channel CLC family in Arabidopsis thaliana (AtCLCe) was hypothesized to play a role in photosynthetic regulation based on the initial photosynthetic characterization of clce mutant lines. The reduced nitrate content of Arabidopsis clce mutants suggested a role in regulation of plant nitrate homeostasis. In this study, we aimed to further investigate the role of AtCLCe in the regulation of ion homeostasis and photosynthetic processes in the thylakoid membrane. We report that the size and composition of proton motive force were mildly altered in two independent Arabidopsis clce mutant lines. Most pronounced effects in the clce mutants were observed on the photosynthetic electron transport of dark-adapted plants, based on the altered shape and associated parameters of the polyphasic OJIP kinetics of chlorophyll a fluorescence induction. Other alterations were found in the kinetics of state transition and in the macro-organization of photosystem II supercomplexes, as indicated by circular dichroism measurements. Pre-treatment with KCl but not with KNO3 restored the wild-type photosynthetic phenotype. Analyses by transmission electron microscopy revealed a bow-like arrangement of the thylakoid network and a large thylakoid-free stromal region in chloroplast sections from the dark-adapted clce plants. Based on these data, we propose that AtCLCe functions in Cl− homeostasis after transition from light to dark, which affects chloroplast ultrastructure and regulation of photosynthetic electron transport. PMID:26904077

  1. A compendium of temperature responses of Rubisco kinetic traits: variability among and within photosynthetic groups and impacts on photosynthesis modeling

    PubMed Central

    Galmés, Jeroni; Hermida-Carrera, Carmen; Laanisto, Lauri; Niinemets, Ülo

    2016-01-01

    The present study provides a synthesis of the in vitro and in vivo temperature responses of Rubisco Michaelis–Menten constants for CO2 (Kc) and O2 (Ko), specificity factor (Sc,o) and maximum carboxylase turnover rate (kcatc) for 49 species from all the main photosynthetic kingdoms of life. Novel correction routines were developed for in vitro data to remove the effects of study-to-study differences in Rubisco assays. The compilation revealed differences in the energy of activation (∆Ha) of Rubisco kinetics between higher plants and other photosynthetic groups, although photosynthetic bacteria and algae were under-represented and very few species have been investigated so far. Within plants, the variation in Rubisco temperature responses was related to species’ climate and photosynthetic mechanism, with differences in ∆Ha for kcatc among C3 plants from cool and warm environments, and in ∆Ha for kcatc and Kc among C3 and C4 plants. A negative correlation was observed among ∆Ha for Sc/o and species’ growth temperature for all data pooled, supporting the convergent adjustment of the temperature sensitivity of Rubisco kinetics to species’ thermal history. Simulations of the influence of varying temperature dependences of Rubisco kinetics on Rubisco-limited photosynthesis suggested improved photosynthetic performance of C3 plants from cool habitats at lower temperatures, and C3 plants from warm habitats at higher temperatures, especially at higher CO2 concentration. Thus, variation in Rubisco kinetics for different groups of photosynthetic organisms might need consideration to improve prediction of photosynthesis in future climates. Comparisons between in vitro and in vivo data revealed common trends, but also highlighted a large variability among both types of Rubisco kinetics currently used to simulate photosynthesis, emphasizing the need for more experimental work to fill in the gaps in Rubisco datasets and improve scaling from enzyme kinetics to

  2. Spatial patterns of photosynthesis in thin- and thick-leaved epiphytic orchids: unravelling C3–CAM plasticity in an organ-compartmented way

    PubMed Central

    Rodrigues, Maria Aurineide; Matiz, Alejandra; Cruz, Aline Bertinatto; Matsumura, Aline Tiemi; Takahashi, Cassia Ayumi; Hamachi, Leonardo; Félix, Lucas Macedo; Pereira, Paula Natália; Latansio-Aidar, Sabrina Ribeiro; Aidar, Marcos Pereira Marinho; Demarco, Diego; Freschi, Luciano; Mercier, Helenice; Kerbauy, Gilberto Barbante

    2013-01-01

    Background and Aims A positive correlation between tissue thickness and crassulacean acid metabolism (CAM) expression has been frequently suggested. Therefore, this study addressed the question of whether water availability modulates photosynthetic plasticity in different organs of two epiphytic orchids with distinct leaf thickness. Methods Tissue morphology and photosynthetic mode (C3 and/or CAM) were examined in leaves, pseudobulbs and roots of a thick-leaved (Cattleya walkeriana) and a thin-leaved (Oncidium ‘Aloha’) epiphytic orchid. Morphological features were studied comparing the drought-induced physiological responses observed in each organ after 30 d of either drought or well-watered treatments. Key Results Cattleya walkeriana, which is considered a constitutive CAM orchid, displayed a clear drought-induced up-regulation of CAM in its thick leaves but not in its non-leaf organs (pseudobulbs and roots). The set of morphological traits of Cattleya leaves suggested the drought-inducible CAM up-regulation as a possible mechanism of increasing water-use efficiency and carbon economy. Conversely, although belonging to an orchid genus classically considered as performing C3 photosynthesis, Oncidium ‘Aloha’ under drought seemed to express facultative CAM in its roots and pseudobulbs but not in its leaves, indicating that such photosynthetic responses might compensate for the lack of capacity to perform CAM in its thin leaves. Morphological features of Oncidium leaves also indicated lower efficiency in preventing water and CO2 losses, while aerenchyma ducts connecting pseudobulbs and leaves suggested a compartmentalized mechanism of nighttime carboxylation via phosphoenolpyruvate carboxylase (PEPC) (pseudobulbs) and daytime carboxylation via Rubisco (leaves) in drought-exposed Oncidium plants. Conclusions Water availability modulated CAM expression in an organ-compartmented manner in both orchids studied. As distinct regions of the same orchid could perform

  3. Abundance coefficients, a new method for measuring microorganism relative abundance

    USGS Publications Warehouse

    Forester, R.M.

    1977-01-01

    A new method of measuring the relative abundance of microorganisms by using a set of interrelated coefficients, termed 'abundance coefficients' or 'AC', is proposed. These coefficients provide a means of recording abundance for geometric density categories, and each density measurement represents an approximation of the Poisson parameter ??t. The AC is the natural logarithm of a 'characteristic value,' which is a particular number for each geometric density category. The 'characteristic values' are based upon a probabilistic error statement derived from the Poisson formula, and they present evidence for separation of the geometric category boundaries by e = 2.71828. The proposed AC provide a means for recording species abundance in a manner suitable for arithmetic manipulation, for population structure studies, and for the determination of practical limits for defining the presence or absence of a species. Further, these coefficients provide for both intrasample and intersample abundance comparisons. ?? 1977 Plenum Publishing Corporation.

  4. Mimicking the Role of the Antenna in Photosynthetic Photoprotection

    SciTech Connect

    Terazono, Yuichi; Kodis, Gerdenis; Bhushan, Kul; Zaks, Julia; Madden, Christopher; Moore, Ana L.; Moore, Thomas A.; Fleming, Graham R.; Gust, Devens

    2011-03-09

    One mechanism used by plants to protect against damage from excess sunlight is called nonphotochemical quenching (NPQ). Triggered by low pH in the thylakoid lumen, NPQ leads to conversion of excess excitation energy in the antenna system to heat before it can initiate production of harmful chemical species by photosynthetic reaction centers. Here we report a synthetic hexad molecule that functionally mimics the role of the antenna in NPQ. When the hexad is dissolved in an organic solvent, five zinc porphyrin antenna moieties absorb light, exchange excitation energy, and ultimately decay by normal photophysical processes. Their excited-state lifetimes are long enough to permit harvesting of the excitation energy for photoinduced charge separation or other work. However, when acid is added, a pH-sensitive dye moiety is converted to a form that rapidly quenches the first excited singlet states of all five porphyrins, converting the excitation energy to heat and rendering the porphyrins kinetically incompetent to readily perform useful photochemistry.

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

    PubMed

    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. PMID:26925812

  6. Thermal Quantum Correlations in Photosynthetic Light-Harvesting Complexes

    NASA Astrophysics Data System (ADS)

    Mahdian, M.; Kouhestani, H.

    2015-08-01

    Photosynthesis is one of the ancient biological processes, playing crucial role converting solar energy to cellular usable currency. Environmental factors and external perturbations has forced nature to choose systems with the highest efficiency and performance. Recent theoretical and experimental studies have proved the presence of quantum properties in biological systems. Energy transfer systems like Fenna-Matthews-Olson (FMO) complex shows quantum entanglement between sites of Bacteriophylla molecules in protein environment and presence of decoherence. Complex biological systems implement more truthful mechanisms beside chemical-quantum correlations to assure system's efficiency. In this study we investigate thermal quantum correlations in FMO protein of the photosynthetic apparatus of green sulfur bacteria by quantum discord measure. The results confirmed existence of remarkable quantum correlations of of BChla pigments in room temperature. This results approve involvement of quantum correlation mechanisms for information storage and retention in living organisms that could be useful for further evolutionary studies. Inspired idea of this study is potentially interesting to practice by the same procedure in genetic data transfer mechanisms.

  7. Dissecting pigment architecture of individual photosynthetic antenna complexes in solution.

    PubMed

    Wang, Quan; Moerner, W E

    2015-11-10

    Oligomerization plays a critical role in shaping the light-harvesting properties of many photosynthetic pigment-protein complexes, but a detailed understanding of this process at the level of individual pigments is still lacking. To study the effects of oligomerization, we designed a single-molecule approach to probe the photophysical properties of individual pigment sites as a function of protein assembly state. Our method, based on the principles of anti-Brownian electrokinetic trapping of single fluorescent proteins, step-wise photobleaching, and multiparameter spectroscopy, allows pigment-specific spectroscopic information on single multipigment antennae to be recorded in a nonperturbative aqueous environment with unprecedented detail. We focus on the monomer-to-trimer transformation of allophycocyanin (APC), an important antenna protein in cyanobacteria. Our data reveal that the two chemically identical pigments in APC have different roles. One (α) is the functional pigment that red-shifts its spectral properties upon trimer formation, whereas the other (β) is a "protective" pigment that persistently quenches the excited state of α in the prefunctional, monomer state of the protein. These results show how subtleties in pigment organization give rise to functionally important aspects of energy transfer and photoprotection in antenna complexes. The method developed here should find immediate application in understanding the emergent properties of other natural and artificial light-harvesting systems.

  8. Dissecting pigment architecture of individual photosynthetic antenna complexes in solution

    PubMed Central

    Wang, Quan; Moerner, W. E.

    2015-01-01

    Oligomerization plays a critical role in shaping the light-harvesting properties of many photosynthetic pigment−protein complexes, but a detailed understanding of this process at the level of individual pigments is still lacking. To study the effects of oligomerization, we designed a single-molecule approach to probe the photophysical properties of individual pigment sites as a function of protein assembly state. Our method, based on the principles of anti-Brownian electrokinetic trapping of single fluorescent proteins, step-wise photobleaching, and multiparameter spectroscopy, allows pigment-specific spectroscopic information on single multipigment antennae to be recorded in a nonperturbative aqueous environment with unprecedented detail. We focus on the monomer-to-trimer transformation of allophycocyanin (APC), an important antenna protein in cyanobacteria. Our data reveal that the two chemically identical pigments in APC have different roles. One (α) is the functional pigment that red-shifts its spectral properties upon trimer formation, whereas the other (β) is a “protective” pigment that persistently quenches the excited state of α in the prefunctional, monomer state of the protein. These results show how subtleties in pigment organization give rise to functionally important aspects of energy transfer and photoprotection in antenna complexes. The method developed here should find immediate application in understanding the emergent properties of other natural and artificial light-harvesting systems. PMID:26438850

  9. Communication: Coherences observed in vivo in photosynthetic bacteria using two-dimensional electronic spectroscopy

    PubMed Central

    Dahlberg, Peter D.; Norris, Graham J.; Wang, Cheng; Viswanathan, Subha; Singh, Ved P.; Engel, Gregory S.

    2015-01-01

    Energy transfer through large disordered antenna networks in photosynthetic organisms can occur with a quantum efficiency of nearly 100%. This energy transfer is facilitated by the electronic structure of the photosynthetic antennae as well as interactions between electronic states and the surrounding environment. Coherences in time-domain spectroscopy provide a fine probe of how a system interacts with its surroundings. In two-dimensional electronic spectroscopy, coherences can appear on both the ground and excited state surfaces revealing detailed information regarding electronic structure, system-bath coupling, energy transfer, and energetic coupling in complex chemical systems. Numerous studies have revealed coherences in isolated photosynthetic pigment-protein complexes, but these coherences have not been observed in vivo due to the small amplitude of these signals and the intense scatter from whole cells. Here, we present data acquired using ultrafast video-acquisition gradient-assisted photon echo spectroscopy to observe quantum beating signals from coherences in vivo. Experiments were conducted on isolated light harvesting complex II (LH2) from Rhodobacter sphaeroides, whole cells of R. sphaeroides, and whole cells of R. sphaeroides grown in 30% deuterated media. A vibronic coherence was observed following laser excitation at ambient temperature between the B850 and the B850∗ states of LH2 in each of the 3 samples with a lifetime of ∼40-60 fs. PMID:26373989

  10. Functional and structural analysis of the photosynthetic apparatus of Rhodobacter veldkampii.

    PubMed

    Gubellini, Francesca; Francia, Francesco; Busselez, Johan; Venturoli, Giovanni; Lévy, Daniel

    2006-09-01

    In the widely studied purple bacterium Rhodobacter sphaeroides, a small transmembrane protein, named PufX, is required for photosynthetic growth and is involved in the supramolecular dimeric organization of the core complex. We performed a structural and functional analysis of the photosynthetic apparatus of Rhodobacter veldkampii, a related species which evolved independently. Time-resolved optical spectroscopy of R. veldkampii chromatophores showed that the reaction center shares with R. sphaeroides spectral and redox properties and interacts with a cytochrome bc(1) complex through a Q-cycle mechanism. Kinetic analysis of flash-induced cytochrome b(561) reduction indicated a fast delivery of the reduced quinol produced by the reaction center to the cytochrome bc(1) complex. A core complex, along with two light-harvesting LH2 complexes significantly different in size, was purified and analyzed by sedimentation, size exclusion chromatography, mass spectroscopy, and electron microscopy. A PufX subunit identified by MALDI-TOF was found to be associated with the core complex. However, as shown by sedimentation and single-particle analysis by electron microscopy, the core complex is monomeric, suggesting that in R. veldkampii, PufX is involved in the photosynthetic growth but is unable to induce the dimerization of the core complex.

  11. Survival potential and photosynthetic activity of lichens under Mars-like conditions: a laboratory study.

    PubMed

    de Vera, Jean-Pierre; Möhlmann, Diedrich; Butina, Frederike; Lorek, Andreas; Wernecke, Roland; Ott, Sieglinde

    2010-03-01

    Lichens were repetitively exposed over 22 days to thermophysical Mars-like conditions at low-and mid-latitudes. The simulated parameters and the experimental setup are described. Natural samples of the lichen Xanthoria elegans were used to investigate their ability to survive the applied Mars-like conditions. The effects of atmospheric pressure, CO(2) concentration, low temperature, water availability, and light on Mars were also studied. The results of these experiments indicate that no significant decrease in the vitality of the lichen occurred after exposure to simulated martian conditions, which was demonstrated by confocal laser scanning microscopy analysis, and a 95% CO(2) atmosphere with 100% humidity, low pressure (partial pressure of CO(2) was 600 Pa), and low temperature has a balancing effect on photosynthetic activity as a function of temperature. This means a starting low photosynthetic activity at high CO(2) concentrations with Earth-like pressure has a reduction of 60%. But, if the simulated atmospheric pressure is reduced to Mars-like conditions with the maintenance of the same Mars-like 95% CO(2) concentration, the photosynthetic activity increases and again reaches similar values as those exhibited under terrestrial atmospheric pressure and concentration. Based on these results, we presume that, in any region on Mars where liquid water might be available, even for short periods of time, a eukaryotic symbiotic organism would have the ability to survive, at least over weeks, and to temporarily photosynthesize.

  12. Redundant roles of photoreceptors and cytokinins in regulating photosynthetic acclimation to canopy density

    PubMed Central

    Boonman, A.; Prinsen, E.; Voesenek, L. A. C. J.; Pons, T. L.

    2009-01-01

    The regulation of photosynthetic acclimation to canopy density was investigated in tobacco canopies and in tobacco and Arabidopsis plants with part of their foliage experimentally shaded. Both species acclimated to canopy light gradients and partial shading by allocating photosynthetic capacity to leaves in high light and adjusting chloroplast organization to the local light conditions. An investigation was carried out to determine whether signalling mediated by photoreceptors, sugars, cytokinin, and nitrate is involved in and necessary for proper photosynthetic acclimation. No evidence was found for a role for sugars, or for nitrate. The distribution of cytokinins in tobacco stands of contrasting density could be explained in part by irradiance-dependent delivery of cytokinins through the transpiration stream. Functional studies using a comprehensive selection of Arabidopsis mutants and transgenics showed that normal wild-type responses to partial shading were retained when signalling mediated by photoreceptors or cytokinins was disrupted. This indicates that these pathways probably operate in a redundant manner. However, the reduction of the chlorophyll a/b ratio in response to local shade was completely absent in the Arabidopsis Ws-2 accession mutated in PHYTOCHROME D and in the triple phyAphyCphyD mutant. Moreover, cytokinin receptor mutants also showed a reduced response, suggesting a previously unrecognized function of phyD and cytokinins. PMID:19240103

  13. Communication: Coherences observed in vivo in photosynthetic bacteria using two-dimensional electronic spectroscopy

    NASA Astrophysics Data System (ADS)

    Dahlberg, Peter D.; Norris, Graham J.; Wang, Cheng; Viswanathan, Subha; Singh, Ved P.; Engel, Gregory S.

    2015-09-01

    Energy transfer through large disordered antenna networks in photosynthetic organisms can occur with a quantum efficiency of nearly 100%. This energy transfer is facilitated by the electronic structure of the photosynthetic antennae as well as interactions between electronic states and the surrounding environment. Coherences in time-domain spectroscopy provide a fine probe of how a system interacts with its surroundings. In two-dimensional electronic spectroscopy, coherences can appear on both the ground and excited state surfaces revealing detailed information regarding electronic structure, system-bath coupling, energy transfer, and energetic coupling in complex chemical systems. Numerous studies have revealed coherences in isolated photosynthetic pigment-protein complexes, but these coherences have not been observed in vivo due to the small amplitude of these signals and the intense scatter from whole cells. Here, we present data acquired using ultrafast video-acquisition gradient-assisted photon echo spectroscopy to observe quantum beating signals from coherences in vivo. Experiments were conducted on isolated light harvesting complex II (LH2) from Rhodobacter sphaeroides, whole cells of R. sphaeroides, and whole cells of R. sphaeroides grown in 30% deuterated media. A vibronic coherence was observed following laser excitation at ambient temperature between the B850 and the B850∗ states of LH2 in each of the 3 samples with a lifetime of ˜40-60 fs.

  14. Communication: Coherences observed in vivo in photosynthetic bacteria using two-dimensional electronic spectroscopy

    SciTech Connect

    Dahlberg, Peter D.; Norris, Graham J.; Wang, Cheng; Viswanathan, Subha; Singh, Ved P.; Engel, Gregory S.

    2015-09-14

    Energy transfer through large disordered antenna networks in photosynthetic organisms can occur with a quantum efficiency of nearly 100%. This energy transfer is facilitated by the electronic structure of the photosynthetic antennae as well as interactions between electronic states and the surrounding environment. Coherences in time-domain spectroscopy provide a fine probe of how a system interacts with its surroundings. In two-dimensional electronic spectroscopy, coherences can appear on both the ground and excited state surfaces revealing detailed information regarding electronic structure, system-bath coupling, energy transfer, and energetic coupling in complex chemical systems. Numerous studies have revealed coherences in isolated photosynthetic pigment-protein complexes, but these coherences have not been observed in vivo due to the small amplitude of these signals and the intense scatter from whole cells. Here, we present data acquired using ultrafast video-acquisition gradient-assisted photon echo spectroscopy to observe quantum beating signals from coherences in vivo. Experiments were conducted on isolated light harvesting complex II (LH2) from Rhodobacter sphaeroides, whole cells of R. sphaeroides, and whole cells of R. sphaeroides grown in 30% deuterated media. A vibronic coherence was observed following laser excitation at ambient temperature between the B850 and the B850{sup ∗} states of LH2 in each of the 3 samples with a lifetime of ∼40-60 fs.

  15. Monophyly of primary photosynthetic eukaryotes: green plants, red algae, and glaucophytes.

    PubMed

    Rodríguez-Ezpeleta, Naiara; Brinkmann, Henner; Burey, Suzanne C; Roure, Béatrice; Burger, Gertraud; Löffelhardt, Wolfgang; Bohnert, Hans J; Philippe, Hervé; Lang, B Franz

    2005-07-26

    Between 1 and 1.5 billion years ago, eukaryotic organisms acquired the ability to convert light into chemical energy through endosymbiosis with a Cyanobacterium (e.g.,). This event gave rise to "primary" plastids, which are present in green plants, red algae, and glaucophytes ("Plantae" sensu Cavalier-Smith). The widely accepted view that primary plastids arose only once implies two predictions: (1) all plastids form a monophyletic group, as do (2) primary photosynthetic eukaryotes. Nonetheless, unequivocal support for both predictions is lacking (e.g.,). In this report, we present two phylogenomic analyses, with 50 genes from 16 plastid and 15 cyanobacterial genomes and with 143 nuclear genes from 34 eukaryotic species, respectively. The nuclear dataset includes new sequences from glaucophytes, the less-studied group of primary photosynthetic eukaryotes. We find significant support for both predictions. Taken together, our analyses provide the first strong support for a single endosymbiotic event that gave rise to primary photosynthetic eukaryotes, the Plantae. Because our dataset does not cover the entire eukaryotic diversity (but only four of six major groups in), further testing of the monophyly of Plantae should include representatives from eukaryotic lineages for which currently insufficient sequence information is available.

  16. A new perspective on hydrogen production by photosynthetic water-splitting

    SciTech Connect

    Lee, J.W.; Greenbaum, E.

    1996-05-01

    Present energy systems are heavily dependent on fossil fuels. This will eventually lead to the foreseeable depletion of fossil energy resources and, according to some reports, global climate changes due to the emission of carbon dioxide. In principle, hydrogen production by biophotolysis of water can be an ideal solar energy conversion system for sustainable development of human activities in harmony with the global environment. In photosynthetic hydrogen production research, there are currently two main efforts: (1) Direct photoevolution of hydrogen and oxygen by photosynthetic water splitting using the ferredoxin/hydrogenase pathway; (2) Dark hydrogen production by fermentation of organic reserves such as starch that are generated by photosynthesis during the light period. In this chapter, the advantages and challenges of the two approaches for hydrogen production will be discussed, in relation to a new opportunity brought by our recent discovery of a new photosynthetic water-splitting reaction which, potentially, has twice the energy efficiency of conventional watersplitting via the two light reaction Z-scheme of photosynthesis.

  17. Radiative energy budget reveals high photosynthetic efficiency in symbiont-bearing corals

    PubMed Central

    Brodersen, Kasper Elgetti; Lichtenberg, Mads; Ralph, Peter J.; Kühl, Michael; Wangpraseurt, Daniel

    2014-01-01

    The light field on coral reefs varies in intensity and spectral composition, and is the key regulating factor for phototrophic reef organisms, for example scleractinian corals harbouring microalgal symbionts. However, the actual efficiency of light utilization in corals and the mechanisms affecting the radiative energy budget of corals are underexplored. We present the first balanced light energy budget for a symbiont-bearing coral based on a fine-scale study of the microenvironmental photobiology of the massive coral Montastrea curta. The majority (more than 96%) of the absorbed light energy was dissipated as heat, whereas the proportion of the absorbed light energy used in photosynthesis was approximately 4.0% under an irradiance of 640 µmol photons m−2 s−1. With increasing irradiance, the proportion of heat dissipation increased at the expense of photosynthesis. Despite such low energy efficiency, we found a high photosynthetic efficiency of the microalgal symbionts showing high gross photosynthesis rates and quantum efficiencies (QEs) of approximately 0.1 O2 photon−1 approaching theoretical limits under moderate irradiance levels. Corals thus appear as highly efficient light collectors with optical properties enabling light distribution over the corallite/tissue microstructural canopy that enables a high photosynthetic QE of their photosynthetic microalgae in hospite. PMID:24478282

  18. Formation and stability of oxygen-rich bubbles that shape photosynthetic mats.

    PubMed

    Bosak, T; Bush, J W M; Flynn, M R; Liang, B; Ono, S; Petroff, A P; Sim, M S

    2010-01-01

    Gas release in photic-zone microbialites can lead to preservable morphological biosignatures. Here, we investigate the formation and stability of oxygen-rich bubbles enmeshed by filamentous cyanobacteria. Sub-millimetric and millimetric bubbles can be stable for weeks and even months. During this time, lithifying organic-rich laminae surrounding the bubbles can preserve the shape of bubbles. Cm-scale unstable bubbles support the growth of centimetric tubular towers with distinctly laminated mineralized walls. In environments that enable high photosynthetic rates, only small stable bubbles will be enclosed by a dense microbial mesh, while in deep waters extensive microbial mesh will cover even larger photosynthetic bubbles, increasing their preservation potential. Stable photosynthetic bubbles may be preserved as sub-millimeter and millimeter-diameter features with nearly circular cross-sections in the crests of some Proterozoic conical stromatolites, while centrimetric tubes formed around unstable bubbles provide a model for the formation of tubular carbonate microbialites that are not markedly depleted in (13)C.

  19. Redundant roles of photoreceptors and cytokinins in regulating photosynthetic acclimation to canopy density.

    PubMed

    Boonman, A; Prinsen, E; Voesenek, L A C J; Pons, T L

    2009-01-01

    The regulation of photosynthetic acclimation to canopy density was investigated in tobacco canopies and in tobacco and Arabidopsis plants with part of their foliage experimentally shaded. Both species acclimated to canopy light gradients and partial shading by allocating photosynthetic capacity to leaves in high light and adjusting chloroplast organization to the local light conditions. An investigation was carried out to determine whether signalling mediated by photoreceptors, sugars, cytokinin, and nitrate is involved in and necessary for proper photosynthetic acclimation. No evidence was found for a role for sugars, or for nitrate. The distribution of cytokinins in tobacco stands of contrasting density could be explained in part by irradiance-dependent delivery of cytokinins through the transpiration stream. Functional studies using a comprehensive selection of Arabidopsis mutants and transgenics showed that normal wild-type responses to partial shading were retained when signalling mediated by photoreceptors or cytokinins was disrupted. This indicates that these pathways probably operate in a redundant manner. However, the reduction of the chlorophyll a/b ratio in response to local shade was completely absent in the Arabidopsis Ws-2 accession mutated in PHYTOCHROME D and in the triple phyAphyCphyD mutant. Moreover, cytokinin receptor mutants also showed a reduced response, suggesting a previously unrecognized function of phyD and cytokinins. PMID:19240103

  20. Photosynthetic recovery following desiccation of desert green algae (Chlorophyta) and their aquatic relatives.

    PubMed

    Gray, Dennis W; Lewis, Louise A; Cardon, Zoe G

    2007-10-01

    Recent molecular data suggest that desert green algae have evolved from freshwater ancestors at least 14 times in three major classes (Chlorophyceae, Trebouxiophyceae and Charophyceae), offering a unique opportunity to study the adaptation of photosynthetic organisms to life on land in a comparative phylogenetic framework. We examined the photorecovery of phylogenetically matched desert and aquatic algae after desiccation in darkness and under illumination. Desert algae survived desiccation for at least 4 weeks when dried in darkness, and recovered high levels of photosynthetic quantum yield within 1 h of rehydration in darkness. However, when 4 weeks of desiccation was accompanied by illumination, three of six desert taxa lost their ability to recover quantum yield during rehydration in the dark. Aquatic algae, in contrast, recovered very little during dark rehydration following even just 24 h of desiccation. Re-illuminating rehydrated algae produced a nearly complete recovery of quantum yield in all desert and two of five aquatic taxa. These contrasts provide physiological evidence that desert green algae possess mechanisms for photosynthetic recovery after desiccation distinct from those in aquatic relatives, corroborating molecular evidence that they are not happenstance, short-term visitors from aquatic environments. Photosensitivity during desiccation among desert algae further suggests that they may reside in protected microsites within crusts, and species specificity of photosensitivity suggests that disturbances physically disrupting crusts could lead to shifts or losses of taxonomic diversity within these habitats.

  1. Comparing photosynthetic characteristics of Isoetes sinensis Palmer under submerged and terrestrial conditions

    PubMed Central

    Yang, Tao; Liu, Xing

    2015-01-01

    Crassulacean acid metabolism (CAM) is widespread in terrestrial and aquatic species, plastic in response to environmental changes. Isoetes L. is one of the earliest basal vascular plants and CAM is popular in this genus. Isoetes sinensis Palmer is an amphibious species, alternating frequently between terrestrial and aquatic environments. Given this, we investigated and compared photosynthetic characteristics over a diurnal cycle under submerged condition (SC) and terrestrial condition (TC). The results suggest that I. sinensis possesses a stronger CAM capacity under SC. Compared with under TC, titratable acidity levels and organic acid concentrations were more enriched under SC, whereas soluble sugar or starch and protein levels were lower under SC. Transcript analyses for nine photosynthetic genes revealed that CAM-associated genes possessed high transcripts under SC, but C3-related transcripts were highly expressed under TC. In addition, the enzyme activity measurements demonstrated that PEPC activity over a diurnal cycle was slightly higher under SC, whereas Rubisco activity during the daytime was greater under TC. This comprehensive study probably facilitates general understandings about the CAM photosynthetic characteristics of Isoetes in response to the environmental changes. PMID:26634994

  2. Structure, Function and Reconstitution of Antenna Complexes of Green Photosynthetic Bacteria

    SciTech Connect

    Blankenship, Robert E.

    2005-06-10

    Most chlorophyll-type pigments in a photosynthetic organism function as an antenna, absorbing light and transferring excitations to a photochemical reaction center where energy storage takes place by a series of chemical reactions. The green photosynthetic bacteria are characterized by large antenna complexes known as chlorosomes, in which pigment-pigment interactions are of dominant importance. The overall objective of this project is to determine the mechanisms of excitation transfer and regulation of this unique antenna system, including how it is integrated into the rest of the photosynthetic energy transduction apparatus. Techniques that are being used in this research include biochemical analysis, spectroscopy, microscopy, X-ray structural studies, and reconstitution from purified components. Our recent results indicate that the chlorosome baseplate structure, which is the membrane attachment site for the chlorosome to the membrane, is a unique pigment-protein that contains large amounts of carotenoids and small amounts of bacteriochlorophyll a. Reconstitution of directed energy transfer in chlorosomes will be carried out using purified baseplates and oligomeric pigments. The integral membrane B808-866 antenna complex from Chloroflexus aurantiacus and the Fenna-Matthews-Olson protein-reaction center complex from green sulfur bacteria will be characterized by spectroscopic and structural techniques.

  3. Sensor Needs for Effective Measurement of Non-Photosynthetic Vegetation

    NASA Astrophysics Data System (ADS)

    Serbin, G.; Hunt, E. R.; Daughtry, C. S.; Doraiswamy, P. C.

    2009-12-01

    Non-photosynthetic vegetation (NPV) is an important carbon pool in agricultural and non-agricultural environments. In cultivated agricultural environments, NPV manifests itself in the form of crop residues, or the stems, cobs, leaves and other plant parts left in the field after harvest. Modern conservation tillage systems leave substantial quantities of crop residues on the soil surface in comparison with conventional intensive tillage systems, which plow residues under the soil surface. Crop residue cover is an important parameter in agricultural carbon cycle and water quality models. These crop residues, when left intact on the surface, protect the soil from wind and water erosion, reduce evaporation, recycle nutrients, and add organic carbon to the soil surface when they decompose. However, crop residues can be harvested for biofuel feedstock or animal feed and fodder, even in tillage systems which minimally disturb the underlying soil. In rangelands, non-photosynthetic vegetation is an important indicator of rangeland health and soil quality. In non-agricultural settings, NPV can serve as fuel for brush files. As such, the removal of NPV can result in the erosion and transport of soils, and thus, SOC. Current ground-based methods of NPV estimation are tedious and not well-suited for estimating over large areas. Current multispectral spaceborne platforms are not well-suited for estimation of NPV as they lack the appropriate spectral bands in the shortwave infrared (SWIR) portion of the electromagnetic spectrum. The ideal system for measurement of NPV utilizes the Cellulose Absorption Index (CAI), requiring three SWIR bands. Alternatively, estimation of NPV is possible with the Shortwave Infrared Normalized Difference Residue Index (SINDRI) utilizing ASTER bands 6 and 7. While SINDRI is not as effective as CAI, it outperforms the remaining NPV indices and is not as expensive to implement as CAI. SINDRI can also be applied to existing ASTER imagery acquired prior

  4. Abundance models improve spatial and temporal prioritization of conservation resources.

    PubMed

    Johnston, Alison; Fink, Daniel; Reynolds, Mark D; Hochachka, Wesley M; Sullivan, Brian L; Bruns, Nicholas E; Hallstein, Eric; Merrifield, Matt S; Matsumoto, Sandi; Kelling, Steve

    2015-10-01

    Conservation prioritization requires knowledge about organism distribution and density. This information is often inferred from models that estimate the probability of species occurrence rather than from models that estimate species abundance, because abundance data are harder to obtain and model. However, occurrence and abundance may not display similar patterns and therefore development of robust, scalable, abundance models is critical to ensuring that scarce conservation resources are applied where they can have the greatest benefits. Motivated by a dynamic land conservation program, we develop and assess a general method for modeling relative abundance using citizen science monitoring data. Weekly estimates of relative abundance and occurrence were compared for prioritizing times and locations of conservation actions for migratory waterbird species in California, USA. We found that abundance estimates consistently provided better rankings of observed counts than occurrence estimates. Additionally, the relationship between abundance and occurrence was nonlinear and varied by species and season. Across species, locations prioritized by occurrence models had only 10-58% overlap with locations prioritized by abundance models, highlighting that occurrence models will not typically identify the locations of highest abundance that are vital for conservation of populations.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  6. Towards autotrophic tissue engineering: Photosynthetic gene therapy for regeneration.

    PubMed

    Chávez, Myra Noemi; Schenck, Thilo Ludwig; Hopfner, Ursula; Centeno-Cerdas, Carolina; Somlai-Schweiger, Ian; Schwarz, Christian; Machens, Hans-Günther; Heikenwalder, Mathias; Bono, María Rosa; Allende, Miguel L; Nickelsen, Jörg; Egaña, José Tomás

    2016-01-01

    The use of artificial tissues in regenerative medicine is limited due to hypoxia. As a strategy to overcome this drawback, we have shown that photosynthetic biomaterials can produce and provide oxygen independently of blood perfusion by generating chimeric animal-plant tissues during dermal regeneration. In this work, we demonstrate the safety and efficacy of photosynthetic biomaterials in vivo after engraftment in a fully immunocompetent mouse skin defect model. Further, we show that it is also possible to genetically engineer such photosynthetic scaffolds to deliver other key molecules in addition to oxygen. As a proof-of-concept, biomaterials were loaded with gene modified microalgae expressing the angiogenic recombinant protein VEGF. Survival of the algae, growth factor delivery and regenerative potential were evaluated in vitro and in vivo. This work proposes the use of photosynthetic gene therapy in regenerative medicine and provides scientific evidence for the use of engineered microalgae as an alternative to deliver recombinant molecules for gene therapy. PMID:26474040

  7. Towards autotrophic tissue engineering: Photosynthetic gene therapy for regeneration.

    PubMed

    Chávez, Myra Noemi; Schenck, Thilo Ludwig; Hopfner, Ursula; Centeno-Cerdas, Carolina; Somlai-Schweiger, Ian; Schwarz, Christian; Machens, Hans-Günther; Heikenwalder, Mathias; Bono, María Rosa; Allende, Miguel L; Nickelsen, Jörg; Egaña, José Tomás

    2016-01-01

    The use of artificial tissues in regenerative medicine is limited due to hypoxia. As a strategy to overcome this drawback, we have shown that photosynthetic biomaterials can produce and provide oxygen independently of blood perfusion by generating chimeric animal-plant tissues during dermal regeneration. In this work, we demonstrate the safety and efficacy of photosynthetic biomaterials in vivo after engraftment in a fully immunocompetent mouse skin defect model. Further, we show that it is also possible to genetically engineer such photosynthetic scaffolds to deliver other key molecules in addition to oxygen. As a proof-of-concept, biomaterials were loaded with gene modified microalgae expressing the angiogenic recombinant protein VEGF. Survival of the algae, growth factor delivery and regenerative potential were evaluated in vitro and in vivo. This work proposes the use of photosynthetic gene therapy in regenerative medicine and provides scientific evidence for the use of engineered microalgae as an alternative to deliver recombinant molecules for gene therapy.

  8. Erratum: Interstellar Abundance Standards Revisited

    NASA Astrophysics Data System (ADS)

    Sofia, U. J.; Meyer, D. M.

    2001-09-01

    In the Letter ``Interstellar Abundance Standards Revisited'' by U. J. Sofia and D. M. Meyer (ApJ, 554, L221 [2001]), Table 2 and its footnotes contain several typographical errors. The corrected table is shown below. We note that the solar reference standard now implies a positive abundance of nitrogen in halo dust.

  9. Unique role for translation initiation factor 3 in the light color regulation of photosynthetic gene expression.

    PubMed

    Gutu, Andrian; Nesbit, April D; Alverson, Andrew J; Palmer, Jeffrey D; Kehoe, David M

    2013-10-01

    Light-harvesting antennae are critical for collecting energy from sunlight and providing it to photosynthetic reaction centers. Their abundance and composition are tightly regulated to maintain efficient photosynthesis in changing light conditions. Many cyanobacteria alter their light-harvesting antennae in response to changes in ambient light-color conditions through the process of chromatic acclimation. The control of green light induction (Cgi) pathway is a light-color-sensing system that controls the expression of photosynthetic genes during chromatic acclimation, and while some evidence suggests that it operates via transcription attenuation, the components of this pathway have not been identified. We provide evidence that translation initiation factor 3 (IF3), an essential component of the prokaryotic translation initiation machinery that binds the 30S subunit and blocks premature association with the 50S subunit, is part of the control of green light induction pathway. Light regulation of gene expression has not been previously described for any translation initiation factor. Surprisingly, deletion of the IF3-encoding gene infCa was not lethal in the filamentous cyanobacterium Fremyella diplosiphon, and its genome was found to contain a second, redundant, highly divergent infC gene which, when deleted, had no effect on photosynthetic gene expression. Either gene could complement an Escherichia coli infC mutant and thus both encode bona fide IF3s. Analysis of prokaryotic and eukaryotic genome databases established that multiple infC genes are present in the genomes of diverse groups of bacteria and land plants, most of which do not undergo chromatic acclimation. This suggests that IF3 may have repeatedly evolved important roles in the regulation of gene expression in both prokaryotes and eukaryotes.

  10. Production of bioplastics and hydrogen gas by photosynthetic microorganisms

    NASA Astrophysics Data System (ADS)

    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

  11. Fluctuating Two-State Light Harvesting in a Photosynthetic Membrane

    SciTech Connect

    Pan, Duohai; Hu, Dehong; Liu, Ruchuan; Zeng, Xiaohua; Kaplan, Samuel; Lu, H. Peter

    2007-06-28

    How light is converted into chemical energy in a natural photosynthetic system is of great interest in energy sciences. Using single-molecule and single-vesicle fluorescence spectroscopy and imaging, we have observed fluctuating inter-molecular protein energy transfers in the photosynthetic membranes of R. sphaeroides. Our results suggest that there are dynamic coupled and non-coupled states in the light-harvesting protein assembly.

  12. Dynamic Environmental Photosynthetic Imaging Reveals Emergent Phenotypes.

    PubMed

    Cruz, Jeffrey A; Savage, Linda J; Zegarac, Robert; Hall, Christopher C; Satoh-Cruz, Mio; Davis, Geoffry A; Kovac, William Kent; Chen, Jin; Kramer, David M

    2016-06-22

    Understanding and improving the productivity and robustness of plant photosynthesis requires high-throughput phenotyping under environmental conditions that are relevant to the field. Here we demonstrate the dynamic environmental photosynthesis imager (DEPI), an experimental platform for integrated, continuous, and high-throughput measurements of photosynthetic parameters during plant growth under reproducible yet dynamic environmental conditions. Using parallel imagers obviates the need to move plants or sensors, reducing artifacts and allowing simultaneous measurement on large numbers of plants. As a result, DEPI can reveal phenotypes that are not evident under standard laboratory conditions but emerge under progressively more dynamic illumination. We show examples in mutants of Arabidopsis of such "emergent phenotypes" that are highly transient and heterogeneous, appearing in different leaves under different conditions and depending in complex ways on both environmental conditions and plant developmental age. These emergent phenotypes appear to be caused by a range of phenomena, suggesting that such previously unseen processes are critical for plant responses to dynamic environments. PMID:27336966

  13. ENHANCED PRACTICAL PHOTOSYNTHETIC CO2 MITIGATION

    SciTech Connect

    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.

  14. Photosynthetic light harvesting: excitons and coherence

    PubMed Central

    Fassioli, Francesca; Dinshaw, Rayomond; Arpin, Paul C.; Scholes, Gregory D.

    2014-01-01

    Photosynthesis begins with light harvesting, where specialized pigment–protein complexes transform sunlight into electronic excitations delivered to reaction centres to initiate charge separation. There is evidence that quantum coherence between electronic excited states plays a role in energy transfer. In this review, we discuss how quantum coherence manifests in photosynthetic light harvesting and its implications. We begin by examining the concept of an exciton, an excited electronic state delocalized over several spatially separated molecules, which is the most widely available signature of quantum coherence in light harvesting. We then discuss recent results concerning the possibility that quantum coherence between electronically excited states of donors and acceptors may give rise to a quantum coherent evolution of excitations, modifying the traditional incoherent picture of energy transfer. Key to this (partially) coherent energy transfer appears to be the structure of the environment, in particular the participation of non-equilibrium vibrational modes. We discuss the open questions and controversies regarding quantum coherent energy transfer and how these can be addressed using new experimental techniques. PMID:24352671

  15. Renewable hydrogen production by photosynthetic water splitting

    SciTech Connect

    Greenbaum, E.; Lee, J.W.

    1998-06-01

    This mission-oriented research project is focused on the production of renewable hydrogen. The authors have demonstrated that certain unicellular green algae are capable of sustained simultaneous photoproduction of hydrogen and oxygen by light-activated photosynthetic water splitting. It is the goal of this project to develop a practical chemical engineering system for the development of an economic process that can be used to produce renewable hydrogen. There are several fundamental problems that need to be solved before the application of this scientific knowledge can be applied to the development a practical process: (I) maximizing net thermodynamic conversion efficiency of light energy into hydrogen energy, (2) development of oxygen-sensitive hydrogenase-containing mutants, and (3) development of bioreactors that can be used in a real-world chemical engineering process. The authors are addressing each of these problems here at ORNL and in collaboration with their research colleagues at the National Renewable Energy Laboratory, the University of California, Berkeley, and the University of Hawaii. This year the authors have focused on item 1 above. In particular, they have focused on the question of how many light reactions are required to split water to molecular hydrogen and oxygen.

  16. Photosynthetic light harvesting: excitons and coherence.

    PubMed

    Fassioli, Francesca; Dinshaw, Rayomond; Arpin, Paul C; Scholes, Gregory D

    2014-03-01

    Photosynthesis begins with light harvesting, where specialized pigment-protein complexes transform sunlight into electronic excitations delivered to reaction centres to initiate charge separation. There is evidence that quantum coherence between electronic excited states plays a role in energy transfer. In this review, we discuss how quantum coherence manifests in photosynthetic light harvesting and its implications. We begin by examining the concept of an exciton, an excited electronic state delocalized over several spatially separated molecules, which is the most widely available signature of quantum coherence in light harvesting. We then discuss recent results concerning the possibility that quantum coherence between electronically excited states of donors and acceptors may give rise to a quantum coherent evolution of excitations, modifying the traditional incoherent picture of energy transfer. Key to this (partially) coherent energy transfer appears to be the structure of the environment, in particular the participation of non-equilibrium vibrational modes. We discuss the open questions and controversies regarding quantum coherent energy transfer and how these can be addressed using new experimental techniques.

  17. Virtual intermediates in photosynthetic electron transfer.