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Sample records for cyanobacterium gloeobacter violaceus

  1. The Plasma Membrane of the Cyanobacterium Gloeobacter violaceus Contains Segregated Bioenergetic Domains C W

    E-print Network

    Roegner, Matthias

    The Plasma Membrane of the Cyanobacterium Gloeobacter violaceus Contains Segregated Bioenergetic of oxygenic photosynthesis almost invariably take place in the thylakoid membranes, a highly specialized internal membrane system located in the stroma of chloroplasts and the cytoplasm of cyanobacteria. The only

  2. Directed evolution of Gloeobacter violaceus rhodopsin spectral properties.

    PubMed

    Engqvist, Martin K M; McIsaac, R Scott; Dollinger, Peter; Flytzanis, Nicholas C; Abrams, Michael; Schor, Stanford; Arnold, Frances H

    2015-01-16

    Proton-pumping rhodopsins (PPRs) are photoactive retinal-binding proteins that transport ions across biological membranes in response to light. These proteins are interesting for light-harvesting applications in bioenergy production, in optogenetics applications in neuroscience, and as fluorescent sensors of membrane potential. Little is known, however, about how the protein sequence determines the considerable variation in spectral properties of PPRs from different biological niches or how to engineer these properties in a given PPR. Here we report a comprehensive study of amino acid substitutions in the retinal-binding pocket of Gloeobacter violaceus rhodopsin (GR) that tune its spectral properties. Directed evolution generated 70 GR variants with absorption maxima shifted by up to ±80nm, extending the protein's light absorption significantly beyond the range of known natural PPRs. While proton-pumping activity was disrupted in many of the spectrally shifted variants, we identified single tuning mutations that incurred blue and red shifts of 42nm and 22nm, respectively, that did not disrupt proton pumping. Blue-shifting mutations were distributed evenly along the retinal molecule while red-shifting mutations were clustered near the residue K257, which forms a covalent bond with retinal through a Schiff base linkage. Thirty eight of the identified tuning mutations are not found in known microbial rhodopsins. We discovered a subset of red-shifted GRs that exhibit high levels of fluorescence relative to the WT (wild-type) protein. PMID:24979679

  3. The Primitive Thylakoid-Less Cyanobacterium Gloeobacter Is a Common Rock-Dwelling Organism.

    PubMed

    Mareš, Jan; Hrouzek, Pavel; Ka?a, Radek; Ventura, Stefano; Strunecký, Otakar; Komárek, Ji?í

    2013-01-01

    Cyanobacteria are an ancient group of photosynthetic prokaryotes, which are significant in biogeochemical cycles. The most primitive among living cyanobacteria, Gloeobacter violaceus, shows a unique ancestral cell organization with a complete absence of inner membranes (thylakoids) and an uncommon structure of the photosynthetic apparatus. Numerous phylogenetic papers proved its basal position among all of the organisms and organelles capable of plant-like photosynthesis (i.e., cyanobacteria, chloroplasts of algae and plants). Hence, G. violaceus has become one of the key species in evolutionary study of photosynthetic life. It also numbers among the most widely used organisms in experimental photosynthesis research. Except for a few related culture isolates, there has been little data on the actual biology of Gloeobacter, being relegated to an "evolutionary curiosity" with an enigmatic identity. Here we show that members of the genus Gloeobacter probably are common rock-dwelling cyanobacteria. On the basis of morphological, ultrastructural, pigment, and phylogenetic comparisons of available Gloeobacter strains, as well as on the basis of three new independent isolates and historical type specimen, we have produced strong evidence as to the close relationship of Gloeobacter to a long known rock-dwelling cyanobacterial morphospecies Aphanothece caldariorum. Our results bring new clues to solving the 40 year old puzzle of the true biological identity of Gloeobacter violaceus, a model organism with a high value in several biological disciplines. A probable broader distribution of Gloeobacter in common wet-rock habitats worldwide is suggested by our data, and its ecological meaning is discussed taking into consideration the background of cyanobacterial evolution. We provide observations of previously unknown genetic variability and phenotypic plasticity, which we expect to be utilized by experimental and evolutionary researchers worldwide. PMID:23823729

  4. Cultivation and Complete Genome Sequencing of Gloeobacter kilaueensis sp. nov., from a Lava Cave in K?lauea Caldera, Hawai'i

    PubMed Central

    Saw, Jimmy H. W.; Schatz, Michael; Brown, Mark V.; Kunkel, Dennis D.; Foster, Jamie S.; Shick, Harry; Christensen, Stephanie; Hou, Shaobin; Wan, Xuehua; Donachie, Stuart P.

    2013-01-01

    The ancestor of Gloeobacter violaceus PCC 7421T is believed to have diverged from that of all known cyanobacteria before the evolution of thylakoid membranes and plant plastids. The long and largely independent evolutionary history of G. violaceus presents an organism retaining ancestral features of early oxygenic photoautotrophs, and in whom cyanobacteria evolution can be investigated. No other Gloeobacter species has been described since the genus was established in 1974 (Rippka et al., Arch Microbiol 100:435). Gloeobacter affiliated ribosomal gene sequences have been reported in environmental DNA libraries, but only the type strain's genome has been sequenced. However, we report here the cultivation of a new Gloeobacter species, G. kilaueensis JS1T, from an epilithic biofilm in a lava cave in K?lauea Caldera, Hawai'i. The strain's genome was sequenced from an enriched culture resembling a low-complexity metagenomic sample, using 9 kb paired-end 454 pyrosequences and 400 bp paired-end Illumina reads. The JS1T and G. violaceus PCC 7421T genomes have little gene synteny despite sharing 2842 orthologous genes; comparing the genomes shows they do not belong to the same species. Our results support establishing a new species to accommodate JS1T, for which we propose the name Gloeobacter kilaueensis sp. nov. Strain JS1T has been deposited in the American Type Culture Collection (BAA-2537), the Scottish Marine Institute's Culture Collection of Algae and Protozoa (CCAP 1431/1), and the Belgian Coordinated Collections of Microorganisms (ULC0316). The G. kilaueensis holotype has been deposited in the Algal Collection of the US National Herbarium (US# 217948). The JS1T genome sequence has been deposited in GenBank under accession number CP003587. The G+C content of the genome is 60.54 mol%. The complete genome sequence of G. kilaueensis JS1T may further understanding of cyanobacteria evolution, and the shift from anoxygenic to oxygenic photosynthesis. PMID:24194836

  5. Geographic variation in thermal physiological performance of the intertidal crab Petrolisthes violaceus along a latitudinal gradient.

    PubMed

    Gaitán-Espitia, Juan Diego; Bacigalupe, Leonardo D; Opitz, Tania; Lagos, Nelson A; Timmermann, Tania; Lardies, Marco A

    2014-12-15

    Environmental temperature has profound effects on the biological performance and biogeographical distribution of ectothermic species. Variation of this abiotic factor across geographic gradients is expected to produce physiological differentiation and local adaptation of natural populations depending on their thermal tolerances and physiological sensitivities. Here, we studied geographic variation in whole-organism thermal physiology of seven populations of the porcelain crab Petrolisthes violaceus across a latitudinal gradient of 3000 km, characterized by a cline of thermal conditions. Our study found that populations of P. violaceus show no differences in the limits of their thermal performance curves and demonstrate a negative correlation of their optimal temperatures with latitude. Additionally, our findings show that high-latitude populations of P. violaceus exhibit broader thermal tolerances, which is consistent with the climatic variability hypothesis. Interestingly, under a future scenario of warming oceans, the thermal safety margins of P. violaceus indicate that lower latitude populations can physiologically tolerate the ocean-warming scenarios projected by the IPCC for the end of the twenty-first century. PMID:25394627

  6. Production and characterization of intergeneric somatic hybrids between Brassica napus and Orychophragmus violaceus and their backcrossing progenies.

    PubMed

    Zhao, Zhi-gang; Hu, Ting-ting; Ge, Xian-Hong; Du, Xue-zhu; Ding, Li; Li, Zai-yun

    2008-10-01

    Alien chromosome addition lines have been widely used for identifying gene linkage groups, assigning species-specific characters to a particular chromosome and comparing gene synteny between related species. In plant breeding, their utilization lies in introgressing characters of agronomic value. The present investigation reports the production of intergeneric somatic hybrids Brassica napus (2n = 38) + Orychophragmus violaceus (2n = 24) through asymmetric fusions of mesophyll protoplasts and subsequent development of B. napus-O. violaceous chromosome addition lines. Somatic hybrids showed variations in morphology and fertility and were mixoploids (2n = 51-67) with a range of 19-28 O. violaceus chromosomes identified by genomic in situ hybridization (GISH). After pollinated with B. napus parent and following embryo rescue, 20 BC(1) plants were obtained from one hybrid. These exhibited typical serrated leaves of O. violaceus or B. napus-type leaves. All BC(1) plants were partially male fertile but female sterile because of abnormal ovules. These were mixoploids (2n = 41-54) with 9-16 chromosomes from O. violaceus. BC(2) plants showed segregations for female fertility, leaf shape and still some chromosome variation (2n = 39-43) with 2-5 O. violaceus chromosomes, but mainly containing the whole complement from B. napus. Among the selfed progenies of BC(2) plants, monosomic addition lines (2n = 39, AACC + 1O) with or without the serrated leaves of O. violaceus or female sterility were established. The complete set of additions is expected from this investigation. In addition, O. violaceus plants at diploid and tetraploid levels with some variations in morphology and chromosome numbers were regenerated from the pretreated protoplasts by iodoacetate and UV-irradiation. PMID:18626647

  7. Complex relationship between multiple measures of cognitive ability and male mating success in satin bowerbirds, Ptilonorhynchus violaceus

    E-print Network

    Borgia, Gerald

    Complex relationship between multiple measures of cognitive ability and male mating success ability mating success Ptilonorhynchus violaceus satin bowerbird sexual selection Many animal species have of these tasks, males with better scores for two integrative measures of these cognitive tasks had higher mating

  8. Synergistic allelochemicals from a freshwater cyanobacterium

    PubMed Central

    Leão, Pedro N.; Pereira, Alban R.; Liu, Wei-Ting; Ng, Julio; Pevzner, Pavel A.; Dorrestein, Pieter C.; König, Gabriele M.; Vasconcelos, Vitor M.; Gerwick, William H.

    2010-01-01

    The ability of cyanobacteria to produce complex secondary metabolites with potent biological activities has gathered considerable attention due to their potential therapeutic and agrochemical applications. However, the precise physiological or ecological roles played by a majority of these metabolites have remained elusive. Several studies have shown that cyanobacteria are able to interfere with other organisms in their communities through the release of compounds into the surrounding medium, a phenomenon usually referred to as allelopathy. Exudates from the freshwater cyanobacterium Oscillatoria sp. had previously been shown to inhibit the green microalga Chlorella vulgaris. In this study, we observed that maximal allelopathic activity is highest in early growth stages of the cyanobacterium, and this provided sufficient material for isolation and chemical characterization of active compounds that inhibited the growth of C. vulgaris. Using a bioassay-guided approach, we isolated and structurally characterized these metabolites as cyclic peptides containing several unusually modified amino acids that are found both in the cells and in the spent media of Oscillatoria sp. cultures. Strikingly, only the mixture of the two most abundant metabolites in the cells was active toward C. vulgaris. Synergism was also observed in a lung cancer cell cytotoxicity assay. The binary mixture inhibited other phytoplanktonic organisms, supporting a natural function of this synergistic mixture of metabolites as allelochemicals. PMID:20534563

  9. Genomes of diverse isolates of the marine cyanobacterium Prochlorococcus

    E-print Network

    Berube, Paul M.

    The marine cyanobacterium Prochlorococcus is the numerically dominant photosynthetic organism in the oligotrophic oceans, and a model system in marine microbial ecology. Here we report 27 new whole genome sequences (2 ...

  10. Analysis of photoregulation in a cyanobacterium through reverse genetics 

    E-print Network

    Cogdell, David Earl

    1997-01-01

    Synechococcus sp. strain PCC 7942, a unicellular cyanobacterium which utilizes a plant-like photosynthetic apparatus, was the model organism in a search for regulators of photosynthesis genes. Cyanobacteria share with plants and algea the need...

  11. Radiation characteristics and optical properties of filamentous cyanobacterium Anabaena cylindrica

    E-print Network

    Pilon, Laurent

    based on a genetic algorithm. The microorganisms were modeled as infinitely long and ran- domly oriented cyanobacteria. Filamentous heterocystous cyanobacterium Anabaena cylindrica was chosen as a model organism. Its change and rising sea levels [1]. Petroleum has been used to produce (i) gasoline for transportation, (ii

  12. A primitive cyanobacterium as pioneer microorganism for terraforming Mars.

    PubMed

    Friedmann, E I; Ocampo-Friedmann, R

    1995-03-01

    The primitive characteristics of the cyanobacterium Chroococcidiopsis suggest that it represents a very ancient type of the group. Its morphology is simple but shows a wide range of variability, and it resembles certain Proterozoic microfossils. Chroococcidiopsis is probably the most desiccation-resistant cyanobacterium, the sole photosynthetic organism in extreme arid habitats. It is also present in a wide range of other extreme environments, from Antarctic rocks to thermal springs and hypersaline habitats, but it is unable to compete with more specialized organisms. Genetic evidence suggests that all forms belong to a single species. Its remarkable tolerance of environmental extremes makes Chroococcidiopsis a prime candidate for use as a pioneer photosynthetic microorganism for terraforming of Mars. The hypolithic microbial growth form (which lives under stones of a desert pavement) could be used as a model for development of technologies for large-scale Martian farming. PMID:11539232

  13. Draft Genome Sequence of Exopolysaccharide-Producing Cyanobacterium Aphanocapsa montana BDHKU 210001

    PubMed Central

    Bhattacharyya, Sourav; Chandrababunaidu, Mathu Malar; Sen, Deeya; Panda, Arijit; Ghorai, Arpita; Bhan, Sushma; Sanghi, Neha

    2015-01-01

    We report for the first time the draft genome sequence of Aphanocapsa montana BDHKU 210001, a halotolerant cyanobacterium isolated from India. This is a marine exopolysaccharide (EPS)-producing cyanobacterium. The genome of this species is assembled into 11.50 million bases, with 296 scaffolds carrying approximately 7,296 protein-coding genes. PMID:25744997

  14. Chemokinetic motility responses of the cyanobacterium oscillatoria terebriformis

    NASA Technical Reports Server (NTRS)

    Richardson, Laurie L.; Castenholz, Richard W.

    1989-01-01

    Oscillatoria terebriformis, a gliding, filamentous, thermophilic cyanobacterium, exhibited an inhibition of gliding motility upon exposure to fructose. The observed response was transient, and the duration of nonmotility was directly proportional to the concentration of fructose. Upon resumption of motility, the rate of motility was also inversely proportional to the concentration of fructose. Sulfide caused a similar response. The effect of sulfide was specific and not due to either anoxia or negative redox potential. Exposure to glucose, acetate, lactate, or mat interstitial water did not elicit any motility response.

  15. Photosynthetic production of glycerol by a recombinant cyanobacterium.

    PubMed

    Savakis, Philipp; Tan, Xiaoming; Du, Wei; Branco dos Santos, Filipe; Lu, Xuefeng; Hellingwerf, Klaas J

    2015-02-10

    Cyanobacteria are prokaryotic organisms capable of oxygenic photosynthesis. Glycerol is an important commodity chemical. Introduction of phosphoglycerol phosphatase 2 from Saccharomyces cerevisiae into the model cyanobacterium Synechocystis sp. PCC6803 resulted in a mutant strain that produced a considerable amount of glycerol from light, water and COPhotosynthetic production . Mild salt stress (200 mM NaCl) on the cells led to an increase of the extracellular glycerol concentration of more than 20%. Under these conditions the mutant accumulated glycerol to an extracellular concentration of 14.3 mM after 17 days of culturing. PMID:25541461

  16. Effect of 1.7 MHz ultrasound on a gas-vacuolate cyanobacterium and a gas-vacuole negative cyanobacterium.

    PubMed

    Tang, Jiao Wen; Wu, Qing Yu; Hao, Hong Wei; Chen, Yifang; Wu, Minsheng

    2004-07-15

    Ultrasonic signals propagated through medium were directly applied to unicellular cyanobacterium cell surfaces to investigate the biological effects induced by ultrasound. The gas-vacuolate cyanobacterium Microcystis aeruginosa and the gas-vacuole negative cyanobacterium Synechococcus PCC 7942 responded differently to ultrasound. When M. aeruginosa was irradiated by 1.7 MHz ultrasound at 0.6 W cm(-2) every day, it showed a decrease of nearly 65% in biomass increment, and this group's generation time increased twice as much as the control. While Synechococcus culture irradiated every day still grew as fast as the control, and its final biomass was as much as the control. The value of the electric conductivity change (Deltasigma) sharply increased in Microcystis suspension during the exposure process, which revealed more ultrasonic cavitation yield in liquid related to the gas-vacuolate cyanobacteria. The relative malondialdehyde (MDA) content, a quantitative indicator of lipid peroxidation, increased by 65% in Microcystis cells and 9% in Synechoccus cells after ultrasonic irradiation. Moreover, the membrane permeability, quantified by measuring the relative amount of electrolyte leaking out of cells, increased to more than 60% in the Microcystis cells. The results indicated that Microcystis cells were susceptible to ultrasonic stress. According to Rayleigh-Plesset's bubble activation theory, 1.7 MHz ultrasound approached the eigenfrequency of gas-vacuolate cells. The present investigation suggested the importance of the cavitational effect relative to intracellular gas-vacuoles in the loss of cell viability. In summary, 1.7 MHz ultrasonic irradiation was effective in preventing water-bloom forming cyanobacteria from growing rapidly due to changes in the functioning and integrity of cellular and subcellular structures. PMID:15261016

  17. Cyanobacterium sp. host cell and vector for production of chemical compounds in cyanobacterial cultures

    DOEpatents

    Piven, Irina; Friedrich, Alexandra; Duhring, Ulf; Uliczka, Frank; Baier, Kerstin; Inaba, Masami; Shi, Tuo; Wang, Kui; Enke, Heike; Kramer, Dan

    2014-09-30

    A cyanobacterial host cell, Cyanobacterium sp., that harbors at least one recombinant gene for the production of a chemical compounds is provided, as well as vectors derived from an endogenous plasmid isolated from the cell.

  18. Mössbauer study of cobalt and iron in the cyanobacterium (blue green alga)

    NASA Astrophysics Data System (ADS)

    Ambe, Shizuko

    1990-07-01

    Mössbauer emission and absorption studies have been performed on cobalt and iron in the cyanobacterium (blue-green alga). The Mössbauer spectrum of the cyanobacterium cultivated with57Co is decomposed into two doublets. The parameters of the major doublet are in good agreement with those of cyanocobalamin (vitamin B12) labeled with57Co. The other minor doublet has parameters close to those of Fe(II) coordinated with six nitrogen atoms. These suggest that cobalt is used for the biosynthesis of vitamin B12 or its analogs in the cyanobacterium. The spectra of the cyanobacterium grown with57Fe show that iron is in the high-spin trivalent state and possibly in the form of ferritin, iron storage protein.

  19. Genetic manipulation of a cyanobacterium for heavy metal detoxivication

    SciTech Connect

    McCormick, P.; Cannon, G.; Heinhorst, S.

    1995-12-31

    Increasing heavy metal contamination of soil and water has produced a need for economical and effective methods to reduce toxic buildup of these materials. Biological systems use metallothionein proteins to sequester such metals as Cu, Cd, and Zn. Studies are underway to genetically engineer a cyanobacteria strain with increased ability for metallothionein production and increased sequestration capacity. Cyanobacteria require only sunlight and CO{sub 2}. Vector constructs are being developed in a naturally competent, unicellular cyanobacterium Anacystis nidulans R2. Closed copies of a yeast copper metallothionein gene have been inserted into a cyanobacterial shuttle vector as well as a vector designed for genomic integration. Transformation studies have produced recombinant cyanobacteria from both of these systems, and work is currently underway to assess the organism`s ability to withstand increasing Cu, Cd, and Zn concentrations.

  20. A New Lyngbyatoxin from the Hawaiian Cyanobacterium Moorea producens

    PubMed Central

    Jiang, Weina; Zhou, Wei; Uchida, Hajime; Kikumori, Masayuki; Irie, Kazuhiro; Watanabe, Ryuichi; Suzuki, Toshiyuki; Sakamoto, Bryan; Kamio, Michiya; Nagai, Hiroshi

    2014-01-01

    Lyngbyatoxin A from the marine cyanobacterium Moorea producens (formerly Lyngbya majuscula) is known as the causative agent of “swimmer’s itch” with its highly inflammatory effect. A new toxic compound was isolated along with lyngbyatoxin A from an ethyl acetate extract of M. producens collected from Hawaii. Analyses of HR-ESI-MS and NMR spectroscopies revealed the isolated compound had the same planar structure with that of lyngbyatoxin A. The results of optical rotation and CD spectra indicated that the compound was a new lyngbyatoxin A derivative, 12-epi-lyngbyatoxin A (1). While 12-epi-lyngbyatoxin A showed comparable toxicities with lyngbyatoxin A in cytotoxicity and crustacean lethality tests, it showed more than 100 times lower affinity for protein kinase C? (PKC?) using the PKC?-C1B peptide when compared to lyngbyatoxin A. PMID:24824022

  1. Thermal denaturation of glutathione reductase from cyanobacterium Spirulina maxima.

    PubMed

    Rojo-Domínguez, A; Hernández-Arana, A; Mendoza-Hernández, G; Rendón, J L

    1997-07-01

    The thermal unfolding of glutathione reductase (NAD[P]H:GSSG oxidoreductase EC 1.6.4.2.) from cyanobacterium Spirulina maxima was monitored by differential scanning calorimetry and circular dichroism at neutral pH. Covalent cross-linking of enzyme at different temperatures revealed dimer as the species undergoing the thermal transition. A single endotherm was observed, but its thermodynamic parameters showed dependence on the scan rate. In the transition zone, aggregation of the dimeric species was observed. Analysis of the enzyme heated at 80 degrees C revealed that the resultant species retained a high content of secondary structure. The addition of low concentrations of guanidinium hydrochloride resulted in a full cooperative thermal transition. A model in which the dimeric protein undergoes a partial unfolding in a kinetically controlled fashion is proposed, such that the experimental value of delta H(cal) results from the simultaneous occurrence of endothermic and exothermic events. PMID:9247721

  2. Genomes of diverse isolates of the marine cyanobacterium Prochlorococcus

    PubMed Central

    Biller, Steven J.; Berube, Paul M.; Berta-Thompson, Jessie W.; Kelly, Libusha; Roggensack, Sara E.; Awad, Lana; Roache-Johnson, Kathryn H.; Ding, Huiming; Giovannoni, Stephen J.; Rocap, Gabrielle; Moore, Lisa R.; Chisholm, Sallie W.

    2014-01-01

    The marine cyanobacterium Prochlorococcus is the numerically dominant photosynthetic organism in the oligotrophic oceans, and a model system in marine microbial ecology. Here we report 27 new whole genome sequences (2 complete and closed; 25 of draft quality) of cultured isolates, representing five major phylogenetic clades of Prochlorococcus. The sequenced strains were isolated from diverse regions of the oceans, facilitating studies of the drivers of microbial diversity—both in the lab and in the field. To improve the utility of these genomes for comparative genomics, we also define pre-computed clusters of orthologous groups of proteins (COGs), indicating how genes are distributed among these and other publicly available Prochlorococcus genomes. These data represent a significant expansion of Prochlorococcus reference genomes that are useful for numerous applications in microbial ecology, evolution and oceanography. PMID:25977791

  3. Lipopeptides from the Tropical Marine Cyanobacterium Symploca sp.

    PubMed Central

    2015-01-01

    A collection of the tropical marine cyanobacterium Symploca sp., collected near Kimbe Bay, Papua New Guinea, previously yielded several new metabolites including kimbeamides A–C, kimbelactone A, and tasihalide C. Investigations into a more polar cytotoxic fraction yielded three new lipopeptides, tasiamides C–E (1–3). The planar structures were deduced by 2D NMR spectroscopy and tandem mass spectrometry, and their absolute configurations were determined by a combination of Marfey’s and chiral-phase GC-MS analysis. These new metabolites are similar to several previously isolated compounds, including tasiamide (4), grassystatins (5, 6), and symplocin A, all of which were isolated from similar filamentous marine cyanobacteria. PMID:24588245

  4. Crossbyanols A-D, Toxic Brominated Polyphenyl Ethers from the Hawai'ian Bloom-Forming Cyanobacterium Leptolyngbya crossbyana

    E-print Network

    Smith, Jennifer E.

    (release of symbiotic zooxanthellae) and showed general signs of stress. To date, however, there have been cyanobacterium Leptolyngbya crossbyana forms extensive blooms on Hawai'ian coral reefs and results in significant damage to the subtending corals. Additionally, corals near mats of this cyanobacterium, but not directly

  5. Bloom of the cyanobacterium Moorea bouillonii on the gorgonian coral Annella reticulata in Japan

    PubMed Central

    Yamashiro, Hideyuki; Isomura, Naoko; Sakai, Kazuhiko

    2014-01-01

    Coral populations are in decline due to environmental changes and biological attacks by predators and infectious diseases. Here, we report a localized bloom of the benthic filamentous cyanobacterium Moorea bouillonii (formerly Lyngbya bouillonii) observed exclusively on the gorgonian (sea fan) coral Annella reticulata at around 20?m depth in Japan. The degree of infection has reached 26% among different sizes of Annella colonies. Thick and continuous growth of Moorea may be sustained partly by symbiotic alpheid shrimp, which affix Moorea filaments to gorgonian corals for use as food and shelter. Most filaments get entangled on the coral colony, some penetrate into the stem of the coral with a swollen end like a root hair, which appears to function as an anchor in Annella. In addition to the cyanobacterium–shrimp interaction, the new trait of anchoring by the cyanobacterium into gorgonian coral may contribute to persistence of this bloom. PMID:25112498

  6. Purification and properties of nitrogenase from the cyanobacterium, Anabaena cylindrica.

    PubMed

    Hallenbeck, P C; Kostel, P J; Benemann

    1979-07-01

    The nitrogenase complex was isolated from nitrogen-starved cultures of Anabaema cylindrica. Sodium dithionite, photochemically reduced ferredoxin, and NADPH were found to be effective election donors to nitro genase in crude extracts whereas hydrogen and pyruvate were not. The Km for acetylene in vivo is ten-fold higher than the Km in vitro, whereas this pattern does not hold for the non-heterocystous cyanobacterium, Plectonema boryanum. This indicates that at least one mechanism of oxygen protection in vivo involves a gas diffusion barrier presented by the heterocyst cell wall. The Mo-Fe component was purified to homogeneity. Its molecular weight (220,000), subunit composition, isoelectric point (4.8), Mo, Fe, and S2- content (2, 20 and 20 mol/mol component), and amino acid composition indicate that this component has similar properties to Mo-Fe-containing components isolated from other bacterial sources. The isolated components from A. cylindrica were found to cross-react, to varying degrees, with components isolated from Azotobacter vinelandii, Rhodospirillum rubrum, and P. boryanum. PMID:111934

  7. Mutations affecting chromatic adaptation in the cyanobacterium Fremyella diplosiphon.

    PubMed Central

    Cobley, J G; Miranda, R D

    1983-01-01

    The chromatically adapting cyanobacterium, Fremyella diplosiphon, when grown in cool white fluorescent light, contains phycoerythrin as its predominant phycobiliprotein. When grown on agar plates with cool white illumination, mutant colonies deficient or devoid of phycoerythrin can be visibly distinguished from the wild type. A total of 25 anomalously pigmented strains were isolated and examined for their ability to chromatically adapt. Based on absorption spectra of cell extracts and on fluorescence emission spectra of intact filaments, we assigned each mutant to one of three classes. In green mutants (16 strains), the photoinduction of phycoerythrin synthesis by green light was lost or impaired, whereas the photorepression of phycocyanin synthesis by green light still functioned as in the wild type. In blue mutants (eight strains), both the ability to photoinduce phycoerythrin synthesis and the ability to photorepress phycocyanin synthesis were lost or impaired. Filaments of blue mutants exhibited a high fluorescence emission at 660 nm. A black mutant (one strain) exhibited partial induction of phycoerythrin and partial repression of phycocyanin in both red and cool white light. From the data, we suggest that in information transduction for chromatic adaptation, early events are common to both phycoerythrin and phycocyanin regulation and that blue mutants possess lesions in these early events. The lesions in green mutants occur in a subsequent branch of the information transduction pathway which is specific for phycoerythrin photoinduction. PMID:6402499

  8. Export of Extracellular Polysaccharides Modulates Adherence of the Cyanobacterium Synechocystis

    SciTech Connect

    Fisher, ML; Allen, R; Luo, YQ; Curtiss, R

    2013-09-10

    The field of cyanobacterial biofuel production is advancing rapidly, yet we know little of the basic biology of these organisms outside of their photosynthetic pathways. We aimed to gain a greater understanding of how the cyanobacterium Synechocystis PCC 6803 (Synechocystis, hereafter) modulates its cell surface. Such understanding will allow for the creation of mutants that autoflocculate in a regulated way, thus avoiding energy intensive centrifugation in the creation of biofuels. We constructed mutant strains lacking genes predicted to function in carbohydrate transport or synthesis. Strains with gene deletions of slr0977 (predicted to encode a permease component of an ABC transporter), slr0982 (predicted to encode an ATP binding component of an ABC transporter) and slr1610 (predicted to encode a methyltransferase) demonstrated flocculent phenotypes and increased adherence to glass. Upon bioinformatic inspection, the gene products of slr0977, slr0982, and slr1610 appear to function in O-antigen (OAg) transport and synthesis. However, the analysis provided here demonstrated no differences between OAg purified from wild-type and mutants. However, exopolysaccharides (EPS) purified from mutants were altered in composition when compared to wild-type. Our data suggest that there are multiple means to modulate the cell surface of Synechocystis by disrupting different combinations of ABC transporters and/or glycosyl transferases. Further understanding of these mechanisms may allow for the development of industrially and ecologically useful strains of cyanobacteria. Additionally, these data imply that many cyanobacterial gene products may possess as-yet undiscovered functions, and are meritorious of further study.

  9. Multiphase calcification associated with the atmophytic cyanobacterium Scytonema julianum

    NASA Astrophysics Data System (ADS)

    Jones, Brian; Peng, Xiaotong

    2014-11-01

    Scytonema julianum, which is an atmophytic cyanobacterium that lives in small clusters in shaded vadose settings throughout the world, is prone to rapid calcification. Specimens found on cavity walls in an inactive spring tower located in Shiqiang (Stone Wall) in China and cavity walls in a breccia that fills sinkholes in dolostones of the Cayman Formation (Miocene) on Grand Cayman are morphologically identical. The microbes (4-11 ?m diameter) are encased with thick, well-developed calcified sheaths with external diameters of 11 to 25 ?m, which developed through the sequential precipitation of amorphous CaCO3 (ACC), acicular calcite crystals, triradiate calcite crystals, and dendrite calcite crystals. The paragenetic relationship of these precipitates to the skeletal rhombic crystals that cover some specimens is unknown. Precipitation probably took place in the extracellular polymeric substances (EPS) that covered the microbes when they were alive. Critically, the type of crystal evident on the surface of the sheath depends on the thickness of the calcified sheath, which is in accord with the sequential development of the different crystal forms. Available evidence indicates that precipitation was largely "microbially influenced" rather than "environment influenced" and also demonstrates that crystals commonly morphed from one crystal form into another as precipitation progressed. There is, for example, clear evidence that the dendrite crystals developed from the triradiate crystals. S. julianum can play a significant role in the development of microbialites in vadose settings by acting as nuclei for CaCO3 precipitation.

  10. Gene Transfer to the Desiccation-Tolerant Cyanobacterium Chroococcidiopsis

    PubMed Central

    Billi, Daniela; Friedmann, E. Imre; Helm, Richard F.; Potts, Malcolm

    2001-01-01

    The coccoid cyanobacterium Chroococcidiopsis dominates microbial communities in the most extreme arid hot and cold deserts. These communities withstand constraints that result from multiple cycles of drying and wetting and/or prolonged desiccation, through mechanisms which remain poorly understood. Here we describe the first system for genetic manipulation of Chroococcidiopsis. Plasmids pDUCA7 and pRL489, based on the pDU1 replicon of Nostoc sp. strain PCC 7524, were transferred to different isolates of Chroococcidiopsis via conjugation and electroporation. This report provides the first evidence that pDU1 replicons can be maintained in cyanobacteria other than Nostoc and Anabaena. Following conjugation, both plasmids replicated in Chroococcidiopsis sp. strains 029, 057, and 123 but not in strains 171 and 584. Both plasmids were electroporated into strains 029 and 123 but not into strains 057, 171, and 584. Expression of PpsbA-luxAB on pRL489 was visualized through in vivo luminescence. Efficiencies of conjugative transfer for pDUCA7 and pRL489 into Chroococcidiopsis sp. strain 029 were approximately 10?2 and 10?4 transconjugants per recipient cell, respectively. Conjugative transfer occurred with a lower efficiency into strains 057 and 123. Electrotransformation efficiencies of about 10?4 electrotransformants per recipient cell were achieved with strains 029 and 123, using either pDUCA7 or pRL489. Extracellular deoxyribonucleases were associated with each of the five strains. Phylogenetic analysis, based upon the V6 to V8 variable regions of 16S rRNA, suggests that desert strains 057, 123, 171, and 029 are distinct from the type species strain Chroococcidiopsis thermalis PCC 7203. The high efficiency of conjugative transfer of Chroococcidiopsis sp. strain 029, from the Negev Desert, Israel, makes this a suitable experimental strain for genetic studies on desiccation tolerance. PMID:11244070

  11. Draft genome sequence of a novel culturable marine chroococcalean cyanobacterium from the South atlantic ocean.

    PubMed

    Rigonato, Janaina; Alvarenga, Danillo O; Branco, Luis H Z; Varani, Alessandro M; Brandini, Frederico P; Fiore, Marli F

    2015-01-01

    The novel chroococcalean cyanobacterium strain CENA595 was isolated from the deep chlorophyll maximum layer of the continental shelf of the South Atlantic Ocean. Here, we report the draft genome sequence for this strain, consisting of 60 contigs containing a total of 5,265,703 bp and 3,276 putative protein-coding genes. PMID:25908150

  12. Draft Genome Sequence of Cyanobacterium Hassallia byssoidea Strain VB512170, Isolated from Monuments in India

    PubMed Central

    Singh, Deeksha; Chandrababunaidu, Mathu Malar; Panda, Arijit; Sen, Diya; Bhattacharyya, Sourav

    2015-01-01

    The draft genome assembly of Hassallia byssoidea strain VB512170 with a genome size of ~13 Mb and 10,183 protein-coding genes in 62 scaffolds is reported here for the first time. This is a terrestrial hydrophobic cyanobacterium isolated from monuments in India. We report several copies of luciferase and antibiotic genes in this organism. PMID:25745001

  13. Deciphering the Genome Sequences of the Hydrophobic Cyanobacterium Scytonema tolypothrichoides VB-61278

    PubMed Central

    Das, Abhishek; Panda, Arijit; Singh, Deeksha; Chandrababunaidu, Mathu Malar; Mishra, Gyan Prakash; Bhan, Sushma

    2015-01-01

    Scytonema tolypothrichoides VB-61278, a terrestrial cyanobacterium, can be exploited to produce commercially important products. Here, we report for the first time a 10-Mb draft genome assembly of S. tolypothrichoides VB-61278, with 214 scaffolds and 7,148 putative protein-coding genes. PMID:25838486

  14. Draft Genome Sequence of the Brazilian Toxic Bloom-Forming Cyanobacterium Microcystis aeruginosa Strain SPC777

    PubMed Central

    Alvarenga, Danillo O.; Varani, Alessandro M.; Hoff-Risseti, Caroline; Crespim, Elaine; Ramos, Rommel T. J.; Silva, Artur; Schaker, Patricia D. C.; Heck, Karina; Rigonato, Janaina; Schneider, Maria Paula C.

    2013-01-01

    Microcystis aeruginosa strain SPC777 is an important toxin-producing cyanobacterium, isolated from a water bloom of the Billings reservoir (São Paulo State, Brazil). Here, we report the draft genome sequence and initial findings from a preliminary analysis of strain SPC777, including several gene clusters involved in nonribosomal and ribosomal synthesis of secondary metabolites. PMID:23908289

  15. Effects of iron limitation on the expression of metabolic genes in the marine cyanobacterium

    E-print Network

    Falkowski, Paul G.

    ). Iron is also a key element for the synthesis of several cellular compounds, e.g. ribonucleotides, haem iron is the most abundant transition element in the Earth's crust, the exceediEffects of iron limitation on the expression of metabolic genes in the marine cyanobacterium

  16. CRISPR-Cas Systems in the Cyanobacterium Synechocystis sp. PCC6803 Exhibit Distinct Processing

    E-print Network

    Will, Sebastian

    CRISPR-Cas Systems in the Cyanobacterium Synechocystis sp. PCC6803 Exhibit Distinct Processing, University of Freiburg, Freiburg, Germany Abstract The CRISPR-Cas (Clustered Regularly Interspaced Short Palindrome Repeats ­ CRISPR associated proteins) system provides adaptive immunity in archaea and bacteria

  17. Genome Sequence of the Thermophilic Cyanobacterium Thermosynechococcus sp. Strain NK55a.

    SciTech Connect

    Stolyar, Sergey; Liu, Zhenfeng; Thiel, Vera; Tomsho, Lynn P.; Pinel, Nicolas; Nelson, William C.; Lindemann, Stephen R.; Romine, Margaret F.; Haruta, Shin; Schuster, Stephan C.; Bryant, Donald A.; Fredrickson, Jim K.

    2014-01-02

    The genome of the unicellular cyanobacterium, Thermosynechococcus sp. strain NK55a, isolated from Nakabusa hot spring, comprises a single, circular, 2.5-Mb chromosome. The genome is predicted to encode 2358 protein coding genes, including genes for all typical cyanobacterial photosynthetic and metabolic functions. No genes encoding hydrogenases or nitrogenase were identified.

  18. Diversity of the marine cyanobacterium Trichodesmium : characterization of the Woods Hole culture collection and quantification of field populations

    E-print Network

    Hynes, Annette Michelle

    2009-01-01

    Trichodesmium is a colonial, N2-fixing cyanobacterium found in tropical oceans. Species of Trichodesmium are genetically similar but several species exist together in the same waters. In order to coexist, Trichodesmium ...

  19. TEM Study of Manganese Biosorption by Cyanobacterium Synechocystis 6803

    SciTech Connect

    Dohnalkova, Alice; Bilskis, Christina L.; Kennedy, David W.

    2006-09-01

    The capture of solar energy and its conversion into chemical energy in photosynthetic organisms involves a series of charge reactions across photosynthetic membranes. Oxygen is generated by a proton-electron coupling in photosystem II (PSII) during a water oxidation process where hydrogen is extracted from water terminally bound to a Mn4Ca1Clx inorganic cluster [1]. Manganese is, therefore, an essential catalytic element for photosynthetic growth in cyanobacteria and plants. Since bioavailability of this micronutrient largely depends on the Mn concentration in natural environments, cells have to manage its uptake in order to endure Mn fluctuations. Previous studies have shown that metal biosorption in cyanobacteria can occur by passive adsorption to their outer membrane (pool A), and by metabolically mediated internal uptake [2]. The fresh water cyanobacterium Synechocystis 6803 has been widely used as a model organism for studying photosynthetic processes. This Gram-negative organism has an intricate architecture of internal thylakoid membranes where photosynthetic electron transfer takes place. Here we report on the spatial distribution of Mn biosorbed by cells in both external pool A and intracellular pool B, as observed and analyzed by methods of TEM. The Synechocystis 6803 cells were cultured in BG11 medium at 30 C with continuous irradiance and constant air bubbling. To determine the influence of solid or liquid Mn substrate and its oxidation state on the cell biosorption ability, cells were exposed to two Mn substrates: 1mM solution of MnCl2, and 0.5mM suspension of nanocrystalline MnO2. Cells were incubated with the respective Mn solutions for 48 hours, harvested, and processed using a modified protocol for plastic embedding of bacterial samples containing minerals that was developed in our laboratory [3]. In order to preserve the fragile redox conditions within the cells, all the common heavy metal-based fixatives and stains were omitted, resulting in cells with very low contrast produced principally by electron-dense manganese precipitates. Thin sections were imaged and analyzed using JEOL 2010 HRTEM coupled with EDS (Oxford) and EELS (Gatan) systems. Manganese uptake was measured using a colorimetric method. Cells incubated with Mn solutions were able to take up about 150uM of Mn(II) or Mn(IV) in 48 hours. The predominant accumulation of Mn was associated with the outer membrane for both Mn substrates. Massive deposits seemed to be related in a large extent to the external polymeric substances (EPS) as shown in Fig. 1A-C. Elemental analyses of these precipitates revealed a signal consistent with manganese phosphate. The potential of EPS such as polysaccharides for biosorption or reduction of metals has been described [4], however, the fact that Mn bound to the EPS withstood multiple washes during TEM sample processing is remarkable. From our work with Gram-negative soil bacteria, we hypothesized that the periplasm, an area between the outer and plasma membrane, might be the storage space for internal Mn in pool B. This phenomenon was not observed at any time point for either culture exposed to the Mn. Instead, thin layers of Mn deposits were often found lining the outer and plasma membrane (F). In the MnCl2 solution only, we also observed fine deposits of Mn precipitates along the thylakoid membranes deep inside the cells (Fig. E). Localization of Mn precipitation sites in Synechocystis has important implications for better understanding of the Mn transport and storage processes within cyanobacterial cells, as well as of metal precipitation, solubilization and cycling in the environment.

  20. Genetic manipulation of a metabolic enzyme and a transcriptional regulator increasing succinate excretion from unicellular cyanobacterium

    PubMed Central

    Osanai, Takashi; Shirai, Tomokazu; Iijima, Hiroko; Nakaya, Yuka; Okamoto, Mami; Kondo, Akihiko; Hirai, Masami Y.

    2015-01-01

    Succinate is a building block compound that the U.S. Department of Energy (DOE) has declared as important in biorefineries, and it is widely used as a commodity chemical. Here, we identified the two genes increasing succinate production of the unicellular cyanobacterium Synechocystis sp. PCC 6803. Succinate was excreted under dark, anaerobic conditions, and its production level increased by knocking out ackA, which encodes an acetate kinase, and by overexpressing sigE, which encodes an RNA polymerase sigma factor. Glycogen catabolism and organic acid biosynthesis were enhanced in the mutant lacking ackA and overexpressing sigE, leading to an increase in succinate production reaching five times of the wild-type levels. Our genetic and metabolomic analyses thus demonstrated the effect of genetic manipulation of a metabolic enzyme and a transcriptional regulator on succinate excretion from this cyanobacterium with the data based on metabolomic technique. PMID:26500619

  1. Interaction of fructose with the glucose permease of the cyanobacterium Synechocystis sp. strain PCC 6803

    SciTech Connect

    Flores, E.; Schmetterer, G.

    1986-05-01

    Fructose was bactericidal for the cyanobacterium Synechocystis sp. strain PCC 6803. Each of ten independently isolated fructose-resistant mutants had an alteration of the glucose transport system, measured as uptake of glucose or of 3-0-methyl-D-glucose. In the presence of the analog, the wild-type Synechocystis strain was protected against fructose. Two mutants altered in photoautotrophy were also isolated.

  2. Auxotrophic mutant of the cyanobacterium Nostoc muscorum showing absolute requirement of Cs+ or Rb+ for diazotrophy and autotrophy.

    PubMed

    Bhargava, Santosh; Chauhan, Rajendra; Patil, Pramod K; Singh, Sarva Daman

    2006-01-01

    Caesium-resistant (Cs(+)-R) mutant clones of the cyanobacterium Nostoc muscorum were characterized for diazotrophic growth in a medium devoid of Cs(+) or Rb(+) or both. Cs(+)-R phenotype suffered severe genetic damage of a pleiotropic nature affecting diazotrophic growth, chlorophyll a content, nitrogenase activity and photosynthetic O(2) evolution. Mutation leading to development of Cs(+)-R phenotype could be overcome by availability of Cs(+)/Rb(+). Parent and mutant strains were similar with respect to their Cs(+)/Rb(+) uptake. Available data suggests operation of an efficient coupling of the two incompatible reactions viz. oxygenic photosynthesis and oxygen sensitive N(2) fixation in this cyanobacterium. PMID:16847829

  3. Glyceraldehyde-3-phosphate dehydrogenase gene diversity in eubacteria and eukaryotes: evidence for intra- and inter-kingdom gene transfer.

    PubMed

    Figge, R M; Schubert, M; Brinkmann, H; Cerff, R

    1999-04-01

    Cyanobacteria contain up to three highly divergent glyceraldehyde-3-phosphate dehydrogenase (GAPDH) genes: gap1, gap2, and gap3. Genes gap1 and gap2 are closely related at the sequence level to the nuclear genes encoding cytosolic and chloroplast GAPDH of higher plants and have recently been shown to play distinct key roles in catabolic and anabolic carbon flow, respectively, of the unicellular cyanobacterium Synechocystis sp. PCC6803. In the present study, sequences of 10 GAPDH genes distributed across the cyanobacteria Prochloron didemni, Gloeobacter violaceus PCC7421, and Synechococcus PCC7942 and the alpha-proteobacterium Paracoccus denitrificans and the beta-proteobacterium Ralstonia solanacearum were determined. Prochloron didemni possesses homologs to the gap2 and gap3 genes from Anabaena, Gloeobacter harbors gap1 and gap2 homologs, and Synechococcus possesses gap1, gap2, and gap3. Paracoccus harbors two highly divergent gap genes that are related to gap3, and Ralstonia possesses a homolog of the gap1 gene. Phylogenetic analyses of these sequences in the context of other eubacterial and eukaryotic GAPDH genes reveal that divergence across eubacterial gap1, and gap2, and gap3 genes is greater than that between eubacterial gap1 and eukaroytic glycolytic GapC or between eubacterial gap2 and eukaryotic Calvin cycle GapAB. These data strongly support previous analyses which suggested that eukaryotes acquired their nuclear genes for GapC and GapAB via endosymbiotic gene transfer from the antecedents of mitochondria and chloroplasts, and extend the known range of sequence diversity of the antecedent eubacterial genes. Analyses of available GAPDH sequences from other eubacterial sources indicate that the glycosomal gap gene from trypanosomes (cytosolic in Euglena) and the gap gene from the spirochete Treponema pallidum are each other's closest relatives. This specific relationship can therefore not reflect organismal evolution but must be the result of an interkingdom gene transfer, the direction of which cannot be determined with certainty at present. Contrary to this, the origin of the cytosolic Gap gene from trypanosomes can now be clearly defined as gamma-proteobacterial, since the newly established Ralstonia sequence (beta-proteobacteria) branches basally to the gamma-proteobacterial/trypanosomal assemblage. PMID:10331270

  4. A new chlorophyll d-containing cyanobacterium: evidence for niche adaptation in the genus Acaryochloris.

    PubMed

    Mohr, Remus; Voss, Björn; Schliep, Martin; Kurz, Thorsten; Maldener, Iris; Adams, David G; Larkum, Anthony D W; Chen, Min; Hess, Wolfgang R

    2010-11-01

    Chlorophyll d is a photosynthetic pigment that, based on chemical analyses, has only recently been recognized to be widespread in oceanic and lacustrine environments. However, the diversity of organisms harbouring this pigment is not known. Until now, the unicellular cyanobacterium Acaryochloris marina is the only characterized organism that uses chlorophyll d as a major photopigment. In this study we describe a new cyanobacterium possessing a high amount of chlorophyll d, which was isolated from waters around Heron Island, Great Barrier Reef (23° 26' 31.2? S, 151° 54' 50.4? E). The 16S ribosomal RNA is 2% divergent from the two previously described isolates of A. marina, which were isolated from waters around the Palau islands (Pacific Ocean) and the Salton Sea lake (California), suggesting that it belongs to a different clade within the genus Acaryochloris. An overview sequence analysis of its genome based on Illumina technology yielded 871 contigs with an accumulated length of 8?371?965?nt. Their analysis revealed typical features associated with Acaryochloris, such as an extended gene family for chlorophyll-binding proteins. However, compared with A. marina MBIC11017, distinct genetic, morphological and physiological differences were observed. Light saturation is reached at lower light intensities, Chl d/a ratios are less variable with light intensity and the phycobiliprotein phycocyanin is lacking, suggesting that cyanobacteria of the genus Acaryochloris occur in distinct ecotypes. These data characterize Acaryochloris as a niche-adapted cyanobacterium and show that more rigorous attempts are worthwhile to isolate, cultivate and analyse chlorophyll d-containing cyanobacteria for understanding the ecophysiology of these organisms. PMID:20505751

  5. Macrolactone Nuiapolide, Isolated from a Hawaiian Marine Cyanobacterium, Exhibits Anti-Chemotactic Activity

    PubMed Central

    Mori, Shogo; Williams, Howard; Cagle, Davey; Karanovich, Kristopher; Horgen, F. David; Smith, Roger; Watanabe, Coran M. H.

    2015-01-01

    A new bioactive macrolactone, nuiapolide (1) was identified from a marine cyanobacterium collected off the coast of Niihau, near Lehua Rock. The natural product exhibits anti-chemotactic activity at concentrations as low as 1.3 ?M against Jurkat cells, cancerous T lymphocytes, and induces a G2/M phase cell cycle shift. Structural characterization of the natural product revealed the compound to be a 40-membered macrolactone with nine hydroxyl functional groups and a rare tert-butyl carbinol residue. PMID:26473885

  6. Intramolecular Modulation of Serine Protease Inhibitor Activity in a Marine Cyanobacterium with Antifeedant Properties

    PubMed Central

    Matthew, Susan; Ratnayake, Ranjala; Becerro, Mikel A.; Ritson-Williams, Raphael; Paul, Valerie J.; Luesch, Hendrik

    2010-01-01

    Extracts of the Floridian marine cyanobacterium Lyngbya cf. confervoides were found to deter feeding by reef fish and sea urchins (Diadema antillarum). This antifeedant activity may be a reflection of the secondary metabolite content, known to be comprised of many serine protease inhibitors. Further chemical and NMR spectroscopic investigation led us to isolate and structurally characterize a new serine protease inhibitor 1 that is formally derived from an intramolecular condensation of largamide D (2). The cyclization resulted in diminished activity, but to different extents against two serine proteases tested. This finding suggests that cyanobacteria can endogenously modulate the activity of their protease inhibitors. PMID:20631871

  7. Macrolactone Nuiapolide, Isolated from a Hawaiian Marine Cyanobacterium, Exhibits Anti-Chemotactic Activity.

    PubMed

    Mori, Shogo; Williams, Howard; Cagle, Davey; Karanovich, Kristopher; Horgen, F David; Iii, Roger Smith; Watanabe, Coran M H

    2015-10-01

    A new bioactive macrolactone, nuiapolide (1) was identified from a marine cyanobacterium collected off the coast of Niihau, near Lehua Rock. The natural product exhibits anti-chemotactic activity at concentrations as low as 1.3 ?M against Jurkat cells, cancerous T lymphocytes, and induces a G2/M phase cell cycle shift. Structural characterization of the natural product revealed the compound to be a 40-membered macrolactone with nine hydroxyl functional groups and a rare tert-butyl carbinol residue. PMID:26473885

  8. Net light-induced oxygen evolution in photosystem I deletion mutants of the cyanobacterium Synechocystis sp. PCC 6803

    E-print Network

    Govindjee

    Net light-induced oxygen evolution in photosystem I deletion mutants of the cyanobacterium of net light-induced O2 evo- lution in vivo. The net light-induced O2 evolution requires glucose and can assimilate more CO2 in the light compared to the dark. However, the rate of the light-minus-dark CO2

  9. Complete Genome Sequence of Microcystis aeruginosa NIES-2549, a Bloom-Forming Cyanobacterium from Lake Kasumigaura, Japan

    PubMed Central

    Suzuki, Shigekatsu; Tanabe, Yuuhiko; Osana, Yasunori; Shimura, Yohei; Ishida, Ken-ichiro; Kawachi, Masanobu

    2015-01-01

    Microcystis aeruginosa NIES-2549 is a freshwater bloom-forming cyanobacterium isolated from Lake Kasumigaura, Japan. We report the complete 4.29-Mbp genome sequence of NIES-2549 and its annotation and discuss the genetic diversity of M. aeruginosa strains. This is the third genome sequence of M. aeruginosa isolated from Lake Kasumigaura. PMID:26021928

  10. Draft Genome Sequence of Calothrix Strain 336/3, a Novel H2-Producing Cyanobacterium Isolated from a Finnish Lake

    PubMed Central

    Isojärvi, Janne; Shunmugam, Sumathy; Sivonen, Kaarina; Allahverdiyeva, Yagut; Aro, Eva-Mari

    2015-01-01

    We announce the draft genome sequence of Calothrix strain 336/3, an N2-fixing heterocystous filamentous cyanobacterium isolated from a natural habitat. Calothrix 336/3 produces higher levels of hydrogen than Nostoc punctiforme PCC 73102 and Anabaena strain PCC 7120 and, therefore, is of interest for potential technological applications. PMID:25614574

  11. Extreme Sensory Complexity Encoded in the 10-Megabase Draft Genome Sequence of the Chromatically Acclimating Cyanobacterium Tolypothrix sp. PCC 7601

    PubMed Central

    Yerrapragada, Shaila; Shukla, Animesh; Hallsworth-Pepin, Kymberlie; Choi, Kwangmin; Wollam, Aye; Clifton, Sandra; Qin, Xiang; Muzny, Donna; Raghuraman, Sriram; Ashki, Haleh; Uzman, Akif; Highlander, Sarah K.; Fryszczyn, Bartlomiej G.; Fox, George E.; Tirumalai, Madhan R.; Liu, Yamei; Kim, Sun

    2015-01-01

    Tolypothrix sp. PCC 7601 is a freshwater filamentous cyanobacterium with complex responses to environmental conditions. Here, we present its 9.96-Mbp draft genome sequence, containing 10,065 putative protein-coding sequences, including 305 predicted two-component system proteins and 27 putative phytochrome-class photoreceptors, the most such proteins in any sequenced genome. PMID:25953173

  12. Genome of the cyanobacterium Microcoleus vaginatus FGP-2, a photosynthetic ecosystem engineer of arid land soil biocrusts worldwide.

    PubMed

    Starkenburg, Shawn R; Reitenga, Krista G; Freitas, Tracey; Johnson, Shannon; Chain, Patrick S G; Garcia-Pichel, Ferran; Kuske, Cheryl R

    2011-09-01

    The filamentous cyanobacterium Microcoleus vaginatusis found in arid land soils worldwide. The genome of M. vaginatus strain FGP-2 allows exploration of genes involved in photosynthesis, desiccation tolerance, alkane production, and other features contributing to this organism's ability to function as a major component of biological soil crusts in arid lands. PMID:21705610

  13. Genome of the Cyanobacterium Microcoleus vaginatusFGP-2, a Photosynthetic Ecosystem Engineer of Arid Land Soil Biocrusts Worldwide?

    PubMed Central

    Starkenburg, Shawn R.; Reitenga, Krista G.; Freitas, Tracey; Johnson, Shannon; Chain, Patrick S. G.; Garcia-Pichel, Ferran; Kuske, Cheryl R.

    2011-01-01

    The filamentous cyanobacterium Microcoleus vaginatusis found in arid land soils worldwide. The genome of M. vaginatusstrain FGP-2 allows exploration of genes involved in photosynthesis, desiccation tolerance, alkane production, and other features contributing to this organism's ability to function as a major component of biological soil crusts in arid lands. PMID:21705610

  14. Draft Genome Sequence of Alteromonas macleodii Strain MIT1002, Isolated from an Enrichment Culture of the Marine Cyanobacterium Prochlorococcus

    PubMed Central

    Coe, Allison; Martin-Cuadrado, Ana-Belen

    2015-01-01

    Alteromonas spp. are heterotrophic gammaproteobacteria commonly found in marine environments. We present here the draft genome sequence of Alteromonas macleodii MIT1002, which was isolated from an enrichment culture of the marine cyanobacterium Prochlorococcus NATL2A. This genome contains a mixture of features previously seen only within either the “surface” or “deep” Alteromonas ecotype. PMID:26316635

  15. New Structural Variants of Aeruginosin Produced by the Toxic Bloom Forming Cyanobacterium Nodularia spumigena

    PubMed Central

    Paukku, Eeva; Österholm, Julia; Wahlsten, Matti; Permi, Perttu; Aitio, Olli; Rouhiainen, Leo; Gomez-Saez, Gonzalo V.; Sivonen, Kaarina

    2013-01-01

    Nodularia spumigena is a filamentous diazotrophic cyanobacterium that forms blooms in brackish water bodies. This cyanobacterium produces linear and cyclic peptide protease inhibitors which are thought to be part of a chemical defense against grazers. Here we show that N. spumigena produces structurally novel members of the aeruginosin family of serine protease inhibitors. Extensive chemical analyses including NMR demonstrated that the aeruginosins are comprised of an N-terminal short fatty acid chain, L-Tyr, L-Choi and L-argininal and in some cases pentose sugar. The genome of N. spumigena CCY9414 contains a compact 18-kb aeruginosin gene cluster encoding a peptide synthetase with a reductive release mechanism which offloads the aeruginosins as reactive peptide aldehydes. Analysis of the aeruginosin and spumigin gene clusters revealed two different strategies for the incorporation of N-terminal protecting carboxylic acids. These results demonstrate that strains of N. spumigena produce aeruginosins and spumigins, two families of structurally similar linear peptide aldehydes using separate peptide synthetases. The aeruginosins were chemically diverse and we found 11 structural variants in 16 strains from the Baltic Sea and Australia. Our findings broaden the known structural diversity of the aeruginosin peptide family to include peptides with rare N-terminal short chain (C2–C10) fatty acid moieties. PMID:24040002

  16. Unique Thylakoid Membrane Architecture of a Unicellular N2-Fixing Cyanobacterium Revealed by Electron Tomography

    SciTech Connect

    Liberton, Michelle L.; Austin, Jotham R.; Berg, R. H.; Pakrasi, Himadri B.

    2011-04-01

    Cyanobacteria, descendants of the endosymbiont that gave rise to modern-day chloroplasts, are vital contributors to global biological energy conversion processes. A thorough understanding of the physiology of cyanobacteria requires detailed knowledge of these organisms at the level of cellular architecture and organization. In these prokaryotes, the large membrane protein complexes of the photosynthetic and respiratory electron transport chains function in the intracellular thylakoid membranes. Like plants, the architecture of the thylakoid membranes in cyanobacteria has direct impact on cellular bioenergetics, protein transport, and molecular trafficking. However, whole-cell thylakoid organization in cyanobacteria is not well understood. Here we present, by using electron tomography, an in-depth analysis of the architecture of the thylakoid membranes in a unicellular cyanobacterium, Cyanothece sp. ATCC 51142. Based on the results of three-dimensional tomographic reconstructions of near-entire cells, we determined that the thylakoids in Cyanothece 51142 form a dense and complex network that extends throughout the entire cell. This thylakoid membrane network is formed from the branching and splitting of membranes and encloses a single lumenal space. The entire thylakoid network spirals as a peripheral ring of membranes around the cell, an organization that has not previously been described in a cyanobacterium. Within the thylakoid membrane network are areas of quasi-helical arrangement with similarities to the thylakoid membrane system in chloroplasts. This cyanobacterial thylakoid arrangement is an efficient means of packing a large volume of membranes in the cell while optimizing intracellular transport and trafficking.

  17. Unique thylakoid membrane architecture of a unicellular N2-fixing cyanobacterium revealed by electron tomography

    SciTech Connect

    Liberton, Michelle; Austin II, Jotham R; Berg, R. Howard; Pakrasi, Himadri B

    2011-04-01

    Cyanobacteria, descendants of the endosymbiont that gave rise to modern-day chloroplasts, are vital contributors to global biological energy conversion processes. A thorough understanding of the physiology of cyanobacteria requires detailed knowledge of these organisms at the level of cellular architecture and organization. In these prokaryotes, the large membrane protein complexes of the photosynthetic and respiratory electron transport chains function in the intracellular thylakoid membranes. Like plants, the architecture of the thylakoid membranes in cyanobacteria has direct impact on cellular bioenergetics, protein transport, and molecular trafficking. However, whole-cell thylakoid organization in cyanobacteria is not well understood. Here we present, by using electron tomography, an in-depth analysis of the architecture of the thylakoid membranes in a unicellular cyanobacterium, Cyanothece sp. ATCC 51142. Based on the results of three-dimensional tomographic reconstructions of near-entire cells, we determined that the thylakoids in Cyanothece 51142 form a dense and complex network that extends throughout the entire cell. This thylakoid membrane network is formed from the branching and splitting of membranes and encloses a single lumenal space. The entire thylakoid network spirals as a peripheral ring of membranes around the cell, an organization that has not previously been described in a cyanobacterium. Within the thylakoid membrane network are areas of quasi-helical arrangement with similarities to the thylakoid membrane system in chloroplasts. This cyanobacterial thylakoid arrangement is an efficient means of packing a large volume of membranes in the cell while optimizing intracellular transport and trafficking.

  18. Differential proteomes of the cyanobacterium Cyanothece sp. CCY 0110 upon exposure to heavy metals

    PubMed Central

    Mota, Rita; Pereira, Sara B.; Meazzini, Marianna; Fernandes, Rui; Santos, Arlete; Evans, Caroline A.; De Philippis, Roberto; Wright, Phillip C.; Tamagnini, Paula

    2015-01-01

    The proteomes of the highly efficient extracellular polymeric substances (EPS)-producer cyanobacterium Cyanothece sp. CCY 0110, grown in medium supplemented with an essential metal (Cu2+) or a non-essential metal (Cd2+),were compared using iTRAQ technology. The data were obtained within a larger study that evaluated the overall effects of different heavy metals on growth/survival, EPS production and ultrastructure of this cyanobacterium [1]. To allow a broader understanding of the strategies triggered to coupe with toxic effects of the metals, Cyanothece?s proteomes were evaluated after chronic and acute exposure to Cu2+ and Cd2+ in two independent 8-plex iTRAQ studies. For the chronic exposure 0.1 mg/l of Cu2+ or 5 mg/l of Cd2+ were used for 10 and 20 days, while in the acute experiments the cells were exposed to 10× these concentrations for 24 h. 202 and 268 proteins were identified and quantified for studies 1 (Cu2+) and 2 (Cd2+), respectively. The majority of the proteins with significant fold changes were associated with photosynthesis, CO2 fixation and carbohydrate metabolism, translation, and nitrogen and amino acid metabolism. PMID:26217780

  19. Dynamics of the Toxin Cylindrospermopsin and the Cyanobacterium Chrysosporum (Aphanizomenon) ovalisporum in a Mediterranean Eutrophic Reservoir

    PubMed Central

    Fadel, Ali; Atoui, Ali; Lemaire, Bruno J.; Vinçon-Leite, Brigitte; Slim, Kamal

    2014-01-01

    Chrysosporum ovalisporum is a cylindrospermopsin toxin producing cyanobacterium that was reported in several lakes and reservoirs. Its growth dynamics and toxin distribution in field remain largely undocumented. Chrysosporum ovalisporum was reported in 2009 in Karaoun Reservoir, Lebanon. We investigated the factors controlling the occurrence of this cyanobacterium and vertical distribution of cylindrospermopsin in Karaoun Reservoir. We conducted bi-weekly sampling campaigns between May 2012 and August 2013. Results showed that Chrysosporum ovalisporum is an ecologically plastic species that was observed in all seasons. Unlike the high temperatures, above 26 °C, which is associated with blooms of Chrysosporum ovalisporum in Lakes Kinneret (Israel), Lisimachia and Trichonis (Greece) and Arcos Reservoir (Spain), Chrysosporum ovalisporum in Karaoun Reservoir bloomed in October 2012 at a water temperature of 22 °C during weak stratification. Cylindrospermopsin was detected in almost all water samples even when Chrysosporum ovalisporum was not detected. Chrysosporum ovalisporum biovolumes and cylindrospermopsin concentrations were not correlated (n = 31, r2 = ?0.05). Cylindrospermopsin reached a maximum concentration of 1.7 µg L?1. The vertical profiles of toxin concentrations suggested its possible degradation or sedimentation resulting in its disappearance from the water column. The field growth conditions of Chrysosporum ovalisporum in this study revealed that it can bloom at the subsurface water temperature of 22 °C increasing the risk of its development and expansion in lakes located in temperate climate regions. PMID:25354130

  20. The distribution of a phage-related insertion sequence element in the cyanobacterium, Microcystis aeruginosa.

    PubMed

    Kuno, Sotaro; Yoshida, Takashi; Kamikawa, Ryoma; Hosoda, Naohiko; Sako, Yoshihiko

    2010-01-01

    The cyanophage Ma-LMM01, specifically-infecting Microcystis aeruginosa, has an insertion sequence (IS) element that we named IS607-cp showing high nucleotide similarity to a counterpart in the genome of the cyanobacterium Cyanothece sp. We tested 21 strains of M. aeruginosa for the presence of IS607-cp using PCR and detected the element in strains NIES90, NIES112, NIES604, and RM6. Thermal asymmetric interlaced PCR (TAIL-PCR) revealed each of these strains has multiple copies of IS607-cp. Some of the ISs were classified into three types based on their inserted positions; IS607-cp-1 is common in strains NIES90, NIES112 and NIES604, whereas IS607-cp-2 and IS607-cp-3 are specific to strains NIES90 and RM6, respectively. This multiplicity may reflect the replicative transposition of IS607-cp. The sequence of IS607-cp in Ma-LMM01 showed robust affinity to those found in M. aeruginosa and Cyanothece spp. in a phylogenetic tree inferred from counterparts of various bacteria. This suggests the transfer of IS607-cp between the cyanobacterium and its cyanophage. We discuss the potential role of Ma-LMM01-related phages as donors of IS elements that may mediate the transfer of IS607-cp; and thereby partially contribute to the genome plasticity of M. aeruginosa. PMID:21576885

  1. 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

  2. Live Cell Chemical Profiling of Temporal Redox Dynamics in a Photoautotrophic Cyanobacterium

    SciTech Connect

    Sadler, Natalie C.; Melnicki, Matthew R.; Serres, Margrethe H.; Merkley, Eric D.; Chrisler, William B.; Hill, Eric A.; Romine, Margaret F.; Kim, Sangtae; Zink, Erika M.; Datta, Suchitra; Smith, Richard D.; Beliaev, Alex S.; Konopka, Allan; Wright, Aaron T.

    2014-01-01

    Protein reduction-oxidation (redox) modification is an important mechanism that allows microorganisms to sense environmental changes and initiate cellular responses. We have developed a quantitative chemical probe approach for live cell labeling of proteins that are sensitive to redox modifications. We utilize this in vivo strategy to identify 176 proteins undergoing ~5-10 fold dynamic redox change in response to nutrient limitation and subsequent replenishment in the photoautotrophic cyanobacterium, Synechococcus sp. PCC 7002. We detect redox changes in as little as 30 seconds after nutrient perturbation, and oscillations in reduction and oxidation for 60 minutes following the perturbation. Many of the proteins undergoing dynamic redox transformations participate in the major components for the production (photosystems and electron transport chains) or consumption (Calvin-Benson cycle and protein synthesis) of reductant and/or energy in photosynthetic organisms. Thus, our in vivo approach reveals new redox-susceptible proteins, in addition to validating those previously identified in vitro.

  3. Live cell chemical profiling of temporal redox dynamics in a photoautotrophic cyanobacterium.

    PubMed

    Sadler, Natalie C; Melnicki, Matthew R; Serres, Margrethe H; Merkley, Eric D; Chrisler, William B; Hill, Eric A; Romine, Margaret F; Kim, Sangtae; Zink, Erika M; Datta, Suchitra; Smith, Richard D; Beliaev, Alexander S; Konopka, Allan; Wright, Aaron T

    2014-01-17

    Protein reduction-oxidation (redox) modification is an important mechanism that allows microorganisms to sense environmental changes and initiate cellular responses. We have developed a quantitative chemical probe approach for live cell labeling and imaging of proteins that are sensitive to redox modifications. We utilize this in vivo strategy to identify 176 proteins undergoing ?5-10-fold dynamic redox change in response to nutrient limitation and subsequent replenishment in the photoautotrophic cyanobacterium Synechococcus sp. PCC 7002. We detect redox changes in as little as 30 s after nutrient perturbation and oscillations in reduction and oxidation for 60 min following the perturbation. Many of the proteins undergoing dynamic redox transformations participate in the major components for the production (photosystems and electron transport chains) or consumption (Calvin-Benson cycle and protein synthesis) of reductant and/or energy in photosynthetic organisms. Thus, our in vivo approach reveals new redox-susceptible proteins and validates those previously identified in vitro. PMID:24168666

  4. Genetically modified cyanobacterium Nostoc muscorum overproducing proline in response to salinity and osmotic stresses.

    PubMed

    Bhargava, Santosh

    2006-06-01

    In the parent Nostoc muscorum an active proline oxidase enzyme is required to assimilate exogenous proline as a fixed nitrogen source. Cyanobacterial mutants, resistant to growth inhibitory action of proline analogue L-azetidine-2-carboxylate (Ac-R), were deficient in proline oxidase activity, and were over-accumulators of proline. Proline over-accumulation, resulting either from mutational acquisition of the Ac-R phenotype, or from salinity-induced uptake of exogenous proline, confirmed enhanced salinity/osmotic tolerance in the mutant strain. The nitrogenase activity and photosynthetic O 2 evolution of the parent were sensitive to both salinity as well as osmotic stresses than of Ac-R mutant strain. In addition, the mutation to Ac-resistant phenotype showed no alteration in salinity inducible potassium transport system in the cyanobacterium. PMID:16809859

  5. Oxidative stress management in the filamentous, heterocystous, diazotrophic cyanobacterium, Anabaena PCC7120.

    PubMed

    Banerjee, Manisha; Raghavan, Prashanth S; Ballal, Anand; Rajaram, Hema; Apte, S K

    2013-10-10

    Reactive oxygen species (ROS) are inevitably generated as by-products of respiratory/photosynthetic electron transport in oxygenic photoautotrophs. Unless effectively scavenged, these ROS can damage all cellular components. The filamentous, heterocystous, nitrogen-fixing strains of the cyanobacterium, Anabaena, serve as naturally abundant contributors of nitrogen biofertilizers in tropical rice paddy fields. Anabaena strains are known to tolerate several abiotic stresses, such as heat, UV, gamma radiation, desiccation, etc., that are known to generate ROS. ROS are detoxified by specific antioxidant enzymes like superoxide dismutases (SOD), catalases and peroxiredoxins. The genome of Anabaena PCC7120 encodes two SODs, two catalases and seven peroxiredoxins, indicating the presence of an elaborate antioxidant enzymatic machinery to defend its cellular components from ROS. This article summarizes recent findings and depicts important perspectives in oxidative stress management in Anabaena PCC7120. PMID:24122336

  6. Strategy to obtain axenic cultures from field-collected samples of the cyanobacterium Phormidium animalis.

    PubMed

    Vázquez-Martínez, Guadalupe; Rodriguez, Mario H; Hernández-Hernández, Fidel; Ibarra, Jorge E

    2004-04-01

    An efficient strategy, based on a combination of procedures, was developed to obtain axenic cultures from field-collected samples of the cyanobacterium Phormidium animalis. Samples were initially cultured in solid ASN-10 medium, and a crude separation of major contaminants from P. animalis filaments was achieved by washing in a series of centrifugations and resuspensions in liquid medium. Then, manageable filament fragments were obtained by probe sonication. Fragmentation was followed by forceful washing, using vacuum-driven filtration through an 8-microm pore size membrane and an excess of water. Washed fragments were cultured and treated with a sequential exposure to four different antibiotics. Finally, axenic cultures were obtained from serial dilutions of treated fragments. Monitoring under microscope examination and by inoculation in Luria-Bertani (LB) agar plates indicated either axenicity or the degree of contamination throughout the strategy. PMID:15003694

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

  8. Physiological effects of nickel chloride on the freshwater cyanobacterium Synechococcus sp. IU 625

    PubMed Central

    Nohomovich, Brian; Nguyen, Bao T.; Quintanilla, Michael; Lee, Lee H.; Murray, Sean R.; Chu, Tin-Chun

    2013-01-01

    Harmful algal blooms (HABs) are a serious environmental problem globally. The ability of cyanobacteria, one of the major causative agents of HABs, to grow in heavy metal polluted areas is proving a challenge to environmental restoration initiatives. Some cyanobacteria secrete toxins, such as microcystin, that are potentially dangerous to animals and humans. In this study, the physiology of a cyanobacterium was assessed to nickel chloride exposure. Cell growths were monitored throughout the study with various nickel chloride concentrations (0, 10, 25 or 50 mg/L). Morphological abnormalities were observed with microscopic image analyses. Inductively coupled plasma mass spectrometry (ICP-MS) was carried out to trace the distribution of nickel during the growth period. This study provides insight on potential nickel response mechanisms in freshwater cyanobacteria, which may lead to effective HAB prevention strategy development. PMID:24073357

  9. Local Expansion of a Panmictic Lineage of Water Bloom-Forming Cyanobacterium Microcystis aeruginosa

    PubMed Central

    Tanabe, Yuuhiko; Watanabe, Makoto M.

    2011-01-01

    In previous studies, we have demonstrated that the population structure of the bloom-forming cyanobacterium Microcystis aeruginosa is clonal. Expanded multilocus sequence typing analysis of M. aeruginosa using 412 isolates identified five intraspecific lineages suggested to be panmictic while maintaining overall clonal structure probably due to a reduced recombination rate between lineages. Interestingly, since 2005 most strains belonging to one of these panmictic clusters (group G) have been found in a particular locality (Lake Kasumigaura Basin) in Japan. In this locality, multiple, similar but distinct genotypes of this lineage predominated in the bloom, a pattern that is unprecedented for M. aeruginosa. The population structure underlying blooms associated with this lineage is comparable to epidemics of pathogens. Our results may reveal an expansion of the possible adaptive lineage in a localized aquatic environment, providing us with a unique opportunity to investigate its ecological and biogeographical consequences. PMID:21390221

  10. Back from the dead; the curious tale of the predatory cyanobacterium Vampirovibrio chlorellavorus

    PubMed Central

    Soo, Rochelle M.; Woodcroft, Ben J.; Parks, Donovan H.; Tyson, Gene W.

    2015-01-01

    An uncultured non-photosynthetic basal lineage of the Cyanobacteria, the Melainabacteria, was recently characterised by metagenomic analyses of aphotic environmental samples. However, a predatory bacterium, Vampirovibrio chlorellavorus, originally described in 1972 appears to be the first cultured representative of the Melainabacteria based on a 16S rRNA sequence recovered from a lyophilised co-culture of the organism. Here, we sequenced the genome of V. chlorellavorus directly from 36 year-old lyophilised material that could not be resuscitated confirming its identity as a member of the Melainabacteria. We identified attributes in the genome that likely allow V. chlorellavorus to function as an obligate predator of the microalga Chlorella vulgaris, and predict that it is the first described predator to use an Agrobacterium tumefaciens-like conjugative type IV secretion system to invade its host. V. chlorellavorus is the first cyanobacterium recognised to have a predatory lifestyle and further supports the assertion that Melainabacteria are non-photosynthetic. PMID:26038723

  11. Isolation, purification and characterization of the ATPase complex from the thermophilic cyanobacterium Synechococcus 6716.

    PubMed

    Lubberding, H J; Zimmer, G; van Walraven, H S; Schrickx, J; Kraayenhof, R

    1983-12-01

    The ATPase complex is isolated and purified from membrane vesicles of the thermophilic cyanobacterium Synechococcus 6716 by octyl glucoside and cholic acid by a modification of the procedure for its extraction from spinach chloroplasts. The complex is purified by differential centrifugation and ammonium sulfate precipitation and by gel filtration on Sepharose 6B. The purified fraction, without any phycocyanin contamination, shows ATP hydrolysis activity and Pi/ATP exchange activity of 1564 and 350 nmol X min-1 X mg protein-1, respectively. N,N'-Dicyclohexylcarbodiimide inhibits the ATP hydrolysis activity of this purified fraction. On polyacrylamide gels most typical F1 ATPase polypeptides are identified, but the low-molecular weight polypeptides visible cannot be ascribed to the F0 part of the complex with certainty; non-identified bands around 30 kDa are also present. PMID:6197306

  12. Synthetic Biology Toolbox for Controlling Gene Expression in the Cyanobacterium Synechococcus sp. strain PCC 7002

    PubMed Central

    2015-01-01

    The application of synthetic biology requires characterized tools to precisely control gene expression. This toolbox of genetic parts previously did not exist for the industrially promising cyanobacterium, Synechococcus sp. strain PCC 7002. To address this gap, two orthogonal constitutive promoter libraries, one based on a cyanobacterial promoter and the other ported from Escherichia coli, were built and tested in PCC 7002. The libraries demonstrated 3 and 2.5 log dynamic ranges, respectively, but correlated poorly with E. coli expression levels. These promoter libraries were then combined to create and optimize a series of IPTG inducible cassettes. The resultant induction system had a 48-fold dynamic range and was shown to out-perform Ptrc constructs. Finally, a RBS library was designed and tested in PCC 7002. The presented synthetic biology toolbox will enable accelerated engineering of PCC 7002. PMID:25216157

  13. Natural Products Chemistry and Taxonomy of the Marine Cyanobacterium Blennothrix cantharidosmum

    PubMed Central

    Clark, Benjamin R.; Engene, Niclas; Teasdale, Margaret E.; Rowley, David C.; Matainaho, Teatulohi; Valeriote, Frederick A.; Gerwick, William H.

    2009-01-01

    A Papua New Guinea field collection of the marine cyanobacterium Blennothrix cantharidosmum was investigated for its cytotoxic constituents. Bioassay-guided isolation defined the cytotoxic components as the known compounds lyngbyastatins 1 and 3. However, six new acyl proline derivatives, tumonoic acids D-I, plus the known tumonoic acid A, were also isolated. Their planar structures were defined from NMR and MS data while their stereostructures followed from a series of chiral chromatographies, degradation sequences and synthetic approaches. The new compounds were tested in an array of assays, but showed only modest antimalarial and inhibition of quorum sensing activities. Nevertheless, these are the first natural products to be reported from this genus, and this inspired a detailed morphologic and 16S rDNA-based phylogenetic analysis of the producing organism. PMID:18698821

  14. Effects of Iron Starvation on the Ultrastructure of the Cyanobacterium Agmenellum quadruplicatum

    PubMed Central

    Hardie, L. P.; Balkwill, D. L.; Stevens, S. E.

    1983-01-01

    The effects of iron starvation on the ultrastructure of the unicellular cyanobacterium Agmenellum quadruplicatum were studied by using thin sectioning and transmission electron microscopy. Intracellular polysaccharide began to accumulate at the onset of iron limitation. This was followed by degradation of ribosomes and (later) degradation of the thylakoid membranes, both of which were virtually absent by 200 h. The thylakoids underwent structural modifications and rearrangements before they actually began to break down. Iron starvation did not appear to affect carboxysomes or the extracellular glyocalyx. On the other hand, polyphosphate bodies may have been partially degraded, and an electrontransparent gap eventually appeared between the cell wall and the cytoplasmic membrane. All of these changes were reversed when iron was added back to 200-h starved cultures. The sequence of ultrastructural changes observed during iron starvation clearly differed from those previously reported to occur during nitrogen, phosphorous, or carbon limitation. Images PMID:16346226

  15. Sacrolide A, a new antimicrobial and cytotoxic oxylipin macrolide from the edible cyanobacterium Aphanothece sacrum.

    PubMed

    Oku, Naoya; Matsumoto, Miyako; Yonejima, Kohsuke; Tansei, Keijiroh; Igarashi, Yasuhiro

    2014-01-01

    Macroscopic gelatinous colonies of freshwater cyanobacterium Aphanothece sacrum, a luxury ingredient for Japanese cuisine, were found to contain a new oxylipin-derived macrolide, sacrolide A (1), as an antimicrobial component. The configuration of two chiral centers in 1 was determined by a combination of chiral anisotropy analysis and conformational analysis of different ring-opened derivatives. Compound 1 inhibited the growth of some species of Gram-positive bacteria, yeast Saccharomyces cerevisiae and fungus Penicillium chrysogenum, and was also cytotoxic to 3Y1 rat fibroblasts. Concern about potential food intoxication caused by accidental massive ingestion of A. sacrum was dispelled by the absence of 1 in commercial products. A manual procedure for degrading 1 in raw colonies was also developed, enabling a convenient on-site detoxification at restaurants or for personal consumption. PMID:25161741

  16. Composition and occurrence of lipid droplets in the cyanobacterium Nostoc punctiforme

    PubMed Central

    Peramuna, Anantha; Summers, Michael L.

    2014-01-01

    Inclusions of neutral lipids termed lipid droplets (LDs) located throughout the cell were identified in the cyanobacterium Nostoc punctiforme by staining with lipophyllic fluorescent dyes. LDs increased in number upon entry into stationary phase and addition of exogenous fructose indicating a role for carbon storage, whereas high-light stress did not increase LD numbers. LD accumulation increased when nitrate was used as the nitrogen source during exponential growth as compared to added ammonia or nitrogen–fixing conditions. Analysis of isolated LDs revealed enrichment of triacylglycerol (TAG), - tochopherol, and C17 alkanes. LD TAG from exponential phase growth contained mainly saturated C16 and C18 fatty acids whereas stationary phase LD TAG had additional unsaturated fatty acids characteristic of whole cells. This is the first characterization of cyanobacterial LD composition and conditions leading to their production. Based upon their abnormally large size and atypical location these structures represent a novel sub-organelle in cyanobacteria. PMID:25135835

  17. Detection of bioactive exometabolites produced by the filamentous marine cyanobacterium Geitlerinema sp.

    PubMed

    Caicedo, Nelson H; Kumirska, Jolanta; Neumann, Jennifer; Stolte, Stefan; Thöming, Jorg

    2012-08-01

    Marine cyanobacteria are noted for their ability to excrete metabolites with biotic properties. This paper focuses on such exometabolites obtained from the culture of the marine filamentous cyanobacterium Geitlerinema sp. strain, their purification and subsequent analyses. By this means the recoveries of the active compounds, a prerequisite for properly determining their concentration, are quantified here for the first time. We demonstrate a new procedure using Amberlite XAD-1180 resin in combination with the eluent isopropanol for extraction of the culture media and gas chromatography as simplified chemical analysis. This procedure reduced necessary bacteria cultivation time (from 150 to 21 days) at low volumes of culture media (300 mL) required for identification of two selected bioactive compounds: 4,4'-dihydroxybiphenyl and harmane. PMID:22160344

  18. Temporal Gene Expression of the Cyanobacterium Arthrospira in Response to Gamma Rays

    PubMed Central

    Badri, Hanène; Monsieurs, Pieter; Coninx, Ilse; Nauts, Robin; Wattiez, Ruddy; Leys, Natalie

    2015-01-01

    The edible cyanobacterium Arthrospira is resistant to ionising radiation. The cellular mechanisms underlying this radiation resistance are, however, still largely unknown. Therefore, additional molecular analysis was performed to investigate how these cells can escape from, protect against, or repair the radiation damage. Arthrospira cells were shortly exposed to different doses of 60Co gamma rays and the dynamic response was investigated by monitoring its gene expression and cell physiology at different time points after irradiation. The results revealed a fast switch from an active growth state to a kind of 'survival modus' during which the cells put photosynthesis, carbon and nitrogen assimilation on hold and activate pathways for cellular protection, detoxification, and repair. The higher the radiation dose, the more pronounced this global emergency response is expressed. Genes repressed during early response, suggested a reduction of photosystem II and I activity and reduced tricarboxylic acid (TCA) and Calvin-Benson-Bassham (CBB) cycles, combined with an activation of the pentose phosphate pathway (PPP). For reactive oxygen species detoxification and restoration of the redox balance in Arthrospira cells, the results suggested a powerful contribution of the antioxidant molecule glutathione. The repair mechanisms of Arthrospira cells that were immediately switched on, involve mainly proteases for damaged protein removal, single strand DNA repair and restriction modification systems, while recA was not induced. Additionally, the exposed cells showed significant increased expression of arh genes, coding for a novel group of protein of unknown function, also seen in our previous irradiation studies. This observation confirms our hypothesis that arh genes are key elements in radiation resistance of Arthrospira, requiring further investigation. This study provides new insights into phasic response and the cellular pathways involved in the radiation resistance of microbial cells, in particularly for photosynthetic organisms as the cyanobacterium Arthrospira. PMID:26308624

  19. Largamides A–C, Tiglic Acid-Containing Cyclodepsipeptides with Elastase-Inhibitory Activity from the Marine Cyanobacterium Lyngbya confervoides

    PubMed Central

    Matthew, Susan; Paul, Valerie J.; Luesch, Hendrik

    2009-01-01

    Three unusual tiglic acid-containing cyclodepsipeptides, possessing the revised regioisomeric structures for largamides A–C (1–3),have been isolated from the marine cyanobacterium Lyngbya confervoides collected from southeastern Florida. The two-dimensional structures were determined by NMR spectroscopy and the absolute configurations by chiral HPLC analysis of degradation products. Compounds 1–3 are moderate inhibitors of mammalian elastase activity in vitro with IC50 values ranging from 0.53 to 1.41 ?M. PMID:19214948

  20. Effects of Cylindrospermopsin Producing Cyanobacterium and Its Crude Extracts on a Benthic Green Alga—Competition or Allelopathy?

    PubMed Central

    B-Béres, Viktória; Vasas, Gábor; Dobronoki, Dalma; Gonda, Sándor; Nagy, Sándor Alex; Bácsi, István

    2015-01-01

    Cylindrospermopsin (CYN) is a toxic secondary metabolite produced by filamentous cyanobacteria which could work as an allelopathic substance, although its ecological role in cyanobacterial-algal assemblages is mostly unclear. The competition between the CYN-producing cyanobacterium Chrysosporum (Aphanizomenon) ovalisporum, and the benthic green alga Chlorococcum sp. was investigated in mixed cultures, and the effects of CYN-containing cyanobacterial crude extract on Chlorococcum sp. were tested by treatments with crude extracts containing total cell debris, and with cell debris free crude extracts, modelling the collapse of a cyanobacterial water bloom. The growth inhibition of Chlorococcum sp. increased with the increasing ratio of the cyanobacterium in mixed cultures (inhibition ranged from 26% to 87% compared to control). Interestingly, inhibition of the cyanobacterium growth also occurred in mixed cultures, and it was more pronounced than it was expected. The inhibitory effects of cyanobacterial crude extracts on Chlorococcum cultures were concentration-dependent. The presence of C. ovalisporum in mixed cultures did not cause significant differences in nutrient content compared to Chlorococcum control culture, so the growth inhibition of the green alga could be linked to the presence of CYN and/or other bioactive compounds. PMID:26528991

  1. Responses of a rice-field cyanobacterium Anabaena siamensis TISTR-8012 upon exposure to PAR and UV radiation.

    PubMed

    Rastogi, Rajesh P; Incharoensakdi, Aran; Madamwar, Datta

    2014-10-15

    The effects of PAR and UV radiation and subsequent responses of certain antioxidant enzymatic and non-enzymatic defense systems were studied in a rice field cyanobacterium Anabaena siamensis TISTR 8012. UV radiation resulted in a decline in growth accompanied by a decrease in chlorophyll a and photosynthetic efficiency. Exposure of cells to UV radiation significantly affected the differentiation of vegetative cells into heterocysts or akinetes. UV-B radiation caused the fragmentation of the cyanobacterial filaments conceivably due to the observed oxidative stress. A significant increase of reactive oxygen species in vivo and DNA strand breaks were observed in UV-B exposed cells followed by those under UV-A and PAR radiation, respectively. The UV-induced oxidative damage was alleviated due to an induction of antioxidant enzymatic/non-enzymatic defense systems. In response to UV irradiation, the studied cyanobacterium exhibited a significant increase in antioxidative enzyme activities of superoxide dismutase, catalase and peroxidase. Moreover, the cyanobacterium also synthesized some UV-absorbing/screening substances. HPLC coupled with a PDA detector revealed the presence of three compounds with UV-absorption maxima at 326, 331 and 345 nm. The induction of the biosynthesis of these UV-absorbing compounds was found under both PAR and UV radiation, thus suggesting their possible function as an active photoprotectant. PMID:25128787

  2. Effects of Cylindrospermopsin Producing Cyanobacterium and Its Crude Extracts on a Benthic Green Alga-Competition or Allelopathy?

    PubMed

    B-Béres, Viktória; Vasas, Gábor; Dobronoki, Dalma; Gonda, Sándor; Nagy, Sándor Alex; Bácsi, István

    2015-01-01

    Cylindrospermopsin (CYN) is a toxic secondary metabolite produced by filamentous cyanobacteria which could work as an allelopathic substance, although its ecological role in cyanobacterial-algal assemblages is mostly unclear. The competition between the CYN-producing cyanobacterium Chrysosporum (Aphanizomenon) ovalisporum, and the benthic green alga Chlorococcum sp. was investigated in mixed cultures, and the effects of CYN-containing cyanobacterial crude extract on Chlorococcum sp. were tested by treatments with crude extracts containing total cell debris, and with cell debris free crude extracts, modelling the collapse of a cyanobacterial water bloom. The growth inhibition of Chlorococcum sp. increased with the increasing ratio of the cyanobacterium in mixed cultures (inhibition ranged from 26% to 87% compared to control). Interestingly, inhibition of the cyanobacterium growth also occurred in mixed cultures, and it was more pronounced than it was expected. The inhibitory effects of cyanobacterial crude extracts on Chlorococcum cultures were concentration-dependent. The presence of C. ovalisporum in mixed cultures did not cause significant differences in nutrient content compared to Chlorococcum control culture, so the growth inhibition of the green alga could be linked to the presence of CYN and/or other bioactive compounds. PMID:26528991

  3. Lab-Scale Study of the Calcium Carbonate Dissolution and Deposition by Marine Cyanobacterium Phormidium subcapitatum

    NASA Technical Reports Server (NTRS)

    Karakis, S. G.; Dragoeva, E. G.; Lavrenyuk, T. I.; Rogochiy, A.; Gerasimenko, L. M.; McKay, D. S.; Brown, I. I.

    2006-01-01

    Suggestions that calcification in marine organisms changes in response to global variations in seawater chemistry continue to be advanced (Wilkinson, 1979; Degens et al. 1985; Kazmierczak et al. 1986; R. Riding 1992). However, the effect of [Na+] on calcification in marine cyanobacteria has not been discussed in detail although [Na+] fluctuations reflect both temperature and sea-level fluctuations. The goal of these lab-scale studies therefore was to study the effect of environmental pH and [Na+] on CaCO3 deposition and dissolution by marine cyanobacterium Phormidium subcapitatum. Marine cyanobacterium P. subcapitatum has been cultivated in ASN-III medium. [Ca2+] fluctuations were monitored with Ca(2+) probe. Na(+) concentrations were determined by the initial solution chemistry. It was found that the balance between CaCO3 dissolution and precipitation induced by P. subcapitatum grown in neutral ASN III medium is very close to zero. No CaCO3 precipitation induced by cyanobacterial growth occurred. Growth of P. subcapitatum in alkaline ASN III medium, however, was accompanied by significant oscillations in free Ca(2+) concentration within a Na(+) concentration range of 50-400 mM. Calcium carbonate precipitation occurred during the log phase of P. subcapitatum growth while carbonate dissolution was typical for the stationary phase of P. subcapitatum growth. The highest CaCO3 deposition was observed in the range of Na(+) concentrations between 200-400 mM. Alkaline pH also induced the clamping of P. subcapitatum filaments, which appeared to have a strong affinity to envelop particles of chemically deposited CaCO3 followed by enlargement of those particles size. EDS analysis revealed the presence of Mg-rich carbonate (or magnesium calcite) in the solution containing 10-100 mM Na(+); calcite in the solution containing 200 mM Na(+); and aragonite in the solution containing with 400 mM Na(+). Typical present-day seawater contains xxmM Na(+). Early (Archean) seawater was likely less saline. The division of marine cyanobacterium P. subcapitatum is associated with periodic deposition and dissolution of CaCO3, the rhythms and intensity of which are dependent on concentrations of both OH(-) and Na(+). Thus, the role of present-day marine cyanobacteria in the global carbonate cycle might be reduced to aggregation and recrystallization of available CaCO3 particles in marine water rather than long-term precipitation and accumulation of CaCO3 deposits. For lower Na(+) concentrations, precipitation of carbonates by cyanobacteria would be even less significant. These results suggest that the lack of calcified cyanobacteria in stromatalite-bearing Precambrian sequences can be explained not only by high dissolved inorganic carbon concentrations but also by lower salinity, as well as possible lower pH compared to present-day oceans.

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

    NASA Astrophysics Data System (ADS)

    Badri, Hanène; Leys, Natalie; Wattiez, Ruddy

    Arthrospira (Spirulina) is a photosynthetic cyanobacterium able to use sunlight to release oxygen from water and remove carbon dioxide and nitrate from water. In addition, it is suited for human consumption (edible). For these traits, the cyanobacterium Arthrospira sp. PCC 8005 was selected by the European Space Agency (ESA) as part of the life support system MELiSSA for recycling oxygen, water, and food during future long-haul space missions. However, during such extended missions, Arthrospira sp. PCC 8005 will be exposed to continuous artificial illumination and harmful cosmic radiation. The aim of this study was to investigate how Arthrospira will react and behave when exposed to such stress environment. The cyanobacterium Arthrospira sp. PCC 8005 was exposed to high gamma rays doses in order to unravel in details the response of this bacterium following such stress. Test results showed that after acute exposure to high doses of 60Co gamma radiation upto 3200 Gy, Arthrospira filaments were still able to restart photosynthesis and proliferate normally. Doses above 3200 Gy, did have a detrimental effect on the cells, and delayed post-irradiation proliferation. The photosystem activity, measured as the PSII quantum yield immediately after irradiation, decreased significantly at radiation doses above 3200 Gy. Likewise through pigment content analysis a significant decrease in phycocyanin was observed following exposure to 3200 Gy. The high tolerance of this bacterium to 60Co gamma rays (i.e. ca. 1000x more resistant than human cells for example) raised our interest to investigate in details the cellular and molecular mechanisms behind this amazing resistance. Optimised DNA, RNA and protein extraction methods and a new microarray chip specific for Arthrospira sp. PCC 8005 were developed to identify the global cellular and molecular response following exposure to 3200 Gy and 5000 Gy A total of 15,29 % and 30,18 % genes were found differentially expressed in RNA following respectively 3200 Gy and 5000 Gy. Furthermore proteomics analysis confirmed the presence of proteins for a set of the genes overexpressed in mRNA level. The results allowed to identify the network of genes, involved in antioxidant production and damage repair, and to map the mechanistic response used by Arthrospira sp. PCC8005 to cope with high doses ionizing radiation. This advanced integration between transcriptomic data and proteomics analysis, allowed also the identification of new set of conserved proteins which were never reported or described, and which were found to be expressed in a dose dependent manner upon exposure to ionising radiation in Arthrospira sp. PCC8005. The exact role of this new set of genes and proteins in the radiation resistance of Arthrospira needs to be further elucidated. Nevertheless, this finding of high radiation resistance of an edible bacterium, that can also be used for life support, is peculiar and opens new horizons to perused further research into its possible function in radiation protection. This work was supported by the European Space Agency (ESA-PRODEX) and the Belgian Science Policy (Belspo) through the ARTEMISS project, which is part of the MELiSSA program.

  5. The role of potassium as an ionic signal in the regulation of cyanobacterium Nostoc muscorum response to salinity and osmotic stress.

    PubMed

    Bhargava, Santosh

    2005-01-01

    Spontaneously occurring thallium-resistant (Tl+ -R) mutant of diazotrophic, heterocystous cyanobacterium Nostoc muscorum is described in which Tl+ -R phenotype is the cause of defective salinity-inducible K+ uptake activity and proline uptake activity. The results indicate that mutant strain is more sensitive to salinity and osmotic stresses than its parent. The mutational inactivation of salinity-inducible proline uptake was found associated with increased sensitivity of the cyanobacterial photosynthetic O2 evolution and nitrogenase activity under salinity and osmotic stresses. It is suggested that in the cyanobacterium Nostoc muscorum K+ functions as a primary osmolyte which is associated with salinity-inducible proline uptake leading to the acquisition of salt tolerance in the cyanobacterium. PMID:15900550

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

    PubMed Central

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

    2014-01-01

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

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

    PubMed Central

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

    2015-01-01

    Cyanobacteria are an important group of organisms that carry out oxygenic photosynthesis and play vital roles in both the carbon and nitrogen cycles of the Earth. The annotated genome of Synechococcus sp. PCC 7002, as an ideal model cyanobacterium, is available. A series of transcriptomic and proteomic studies of Synechococcus sp. PCC 7002 cells grown under different conditions have been reported. However, no database of such integrated omics studies has been constructed. Here we present CyanOmics, a database based on the results of Synechococcus sp. PCC 7002 omics studies. CyanOmics comprises one genomic dataset, 29 transcriptomic datasets and one proteomic dataset and should prove useful for systematic and comprehensive analysis of all those data. Powerful browsing and searching tools are integrated to help users directly access information of interest with enhanced visualization of the analytical results. Furthermore, Blast is included for sequence-based similarity searching and Cluster 3.0, as well as the R hclust function is provided for cluster analyses, to increase CyanOmics’s usefulness. To the best of our knowledge, it is the first integrated omics analysis database for cyanobacteria. This database should further understanding of the transcriptional patterns, and proteomic profiling of Synechococcus sp. PCC 7002 and other cyanobacteria. Additionally, the entire database framework is applicable to any sequenced prokaryotic genome and could be applied to other integrated omics analysis projects. Database URL: http://lag.ihb.ac.cn/cyanomics PMID:25632108

  8. Molybdenum independence of nitrogenase component synthesis in the non-heterocystous cyanobacterium Plectonema.

    PubMed Central

    Nagatani, H H; Haselkorn, R

    1978-01-01

    The cyanobacterium Plectonema boryanum (IU 594-UTEX 594) fixes N2 only in the absence of combined N and of O2. We induced nitrogenase by transfer to anaerobic N-free medium and studied the effect of Mo starvation on nitrogenase activity and synthesis. Activity was first detected within 3 h after transfer by the acetylene reduction assay in controls, increasing for at least 25 h. Cells grown on nitrate and Mo and then transferred to N-free, Mo-free medium produced 8% of the control nitrogenase activity. Addition of W to the Mo-free medium reduced the activity to 0.5%. Under both Mo starvation conditions, nitrogenase protein components were synthesized. Component II of the cyanobacterial enzyme was detected by in vitro complementation with Mo-containing component I from Klebsiella pneumoniae or Azotobacter vinelandii but not Clostridium pasteurianum. Component I activity was restored by addition of Mo to cultures in which new enzyme synthesis was blocked by chloramphenicol. Acidified extracts of Plectonema induced in Mo-containing medium contained the Fe-Mo cofactor required to activate extracts of the Azotobacter mutant UW45 in vitro, but they did not activate extracts of Mo-starved Plectonema. Analysis of 35SO4(2-)-labeled proteins by polyacrylamide gel electrophoresis suggested that Mo is required for the conversion of a high-molecular-weight precursor to component I in Plectonema. Images PMID:96092

  9. Mathematical study of pattern formation accompanied by heterocyst differentiation in multicellular cyanobacterium.

    PubMed

    Ishihara, Jun-ichi; Tachikawa, Masashi; Iwasaki, Hideo; Mochizuki, Atsushi

    2015-04-21

    The filamentous cyanobacterium, Anabaena sp. PCC 7120, is one of the simplest models of a multicellular system showing cellular differentiation. In nitrogen-deprived culture, undifferentiated vegetative cells differentiate into heterocysts at ~10-cell intervals along the cellular filament. As undifferentiated cells divide, the number of cells between heterocysts (segment length) increases, and a new heterocyst appears in the intermediate region. To understand how the heterocyst pattern is formed and maintained, we constructed a one-dimensional cellular automaton (CA) model of the heterocyst pattern formation. The dynamics of vegetative cells is modeled by a stochastic transition process including cell division, differentiation and increase of cell age (maturation). Cell division and differentiation depend on the time elapsed after the last cell division, the "cell age". The model dynamics was mathematically analyzed by a two-step Markov approximation. In the first step, we determined steady state of cell age distribution among vegetative cell population. In the second step, we determined steady state distribution of segment length among segment population. The analytical solution was consistent with the results of numerical simulations. We then compared the analytical solution with the experimental data, and quantitatively estimated the immeasurable intercellular kinetics. We found that differentiation is initially independent of cellular maturation, but becomes dependent on maturation as the pattern formation evolves. Our mathematical model and analysis enabled us to quantify the internal cellular dynamics at various stages of the heterocyst pattern formation. PMID:25665721

  10. Composition of the carbohydrate granules of the cyanobacterium, Cyanothece sp. strain ATCC 51142

    NASA Technical Reports Server (NTRS)

    Schneegurt, M. A.; Sherman, D. M.; Sherman, L. A.; Mitchell, C. A. (Principal Investigator)

    1997-01-01

    Cyanothece sp. strain ATCC 51142 is an aerobic, unicellular, diazotrophic cyanobacterium that temporally separates O2-sensitive N2 fixation from oxygenic photosynthesis. The energy and reducing power needed for N2 fixation appears to be generated by an active respiratory apparatus that utilizes the contents of large interthylakoidal carbohydrate granules. We report here on the carbohydrate and protein composition of the granules of Cyanothece sp. strain ATCC 51142. The carbohydrate component is a glucose homopolymer with branches every nine residues and is chemically identical to glycogen. Granule-associated protein fractions showed temporal changes in the number of proteins and their abundance during the metabolic oscillations observed under diazotrophic conditions. There also were temporal changes in the protein pattern of the granule-depleted supernatant fractions from diazotrophic cultures. None of the granule-associated proteins crossreacted with antisera directed against several glycogen-metabolizing enzymes or nitrogenase, although these proteins were tentatively identified in supernatant fractions. It is suggested that the granule-associated proteins are structural proteins required to maintain a complex granule architecture.

  11. Intercellular transfer along the trichomes of the invasive terminal heterocyst forming cyanobacterium Cylindrospermopsis raciborskii CS-505.

    PubMed

    Plominsky, Álvaro M; Delherbe, Nathalie; Mandakovic, Dinka; Riquelme, Brenda; González, Karen; Bergman, Birgitta; Mariscal, Vicente; Vásquez, Mónica

    2015-03-01

    Cylindrospermopsis raciborskii CS-505 is an invasive freshwater filamentous cyanobacterium that when grown diazotrophically may develop trichomes of up to 100 vegetative cells while differentiating only two end heterocysts, the sole sites for their N2-fixation process. We examined the diazotrophic growth and intercellular transfer mechanisms in C. raciborskii CS-505. Subjecting cultures to a combined-nitrogen-free medium to elicit N2 fixation, the trichome length remained unaffected while growth rates decreased. The structures and proteins for intercellular communication showed that while a continuous periplasmic space was apparent along the trichomes, the putative septal junction sepJ gene is divided into two open reading frames and lacks several transmembrane domains unlike the situation in Anabaena, differentiating a 5-fold higher frequency of heterocysts. FRAP analyses also showed that the dyes calcein and 5-CFDA were taken up by heterocysts and vegetative cells, and that the transfer from heterocysts and 'terminal' vegetative cells showed considerably higher transfer rates than that from vegetative cells located in the middle of the trichomes. The data suggest that C. raciborskii CS-505 compensates its low-frequency heterocyst phenotype by a highly efficient transfer of the fixed nitrogen towards cells in distal parts of the trichomes (growing rapidly) while cells in central parts suffers (slow growth). PMID:25757729

  12. Hfq Is Required for Optimal Nitrate Assimilation in the Cyanobacterium Anabaena sp. Strain PCC 7120 ?

    PubMed Central

    Puerta-Fernández, Elena; Vioque, Agustín

    2011-01-01

    Hfq is an RNA binding protein involved in posttranscriptional regulation of gene expression in bacteria. It acts by binding to regulatory small RNAs (sRNAs), which confer specificity for the regulation. Recently, orthologues of the Hfq protein were annotated in cyanobacterial genomes, although its capacity to regulate gene expression by interacting with sRNAs has not been yet demonstrated. Anabaena sp. strain PCC 7120 is a filamentous cyanobacterium that, in the absence of combined nitrogen, is able to fix atmospheric nitrogen by differentiating specialized cells called heterocysts. We have generated an hfq knockout mutant of Anabaena sp. PCC 7120. Deletion of this gene results in differentiation of heterocysts in the presence of nitrate, suggesting a defect in nitrate assimilation. We show that hfq mutant cells are affected in transport and use of nitrate and nitrite. An analysis of the expression of several genes in the nir operon, encoding different elements of the nitrate assimilation pathway, demonstrates a downregulation of their transcription in mutant cells. We also observed that genes ntcB and cnaT, involved in the regulation of the nir operon, show a lower expression in cells lacking Hfq. Finally, when hfq was reintroduced in the mutant, heterocyst differentiation was no longer observed in the presence of nitrate. Therefore, our results indicate that the RNA chaperone Hfq is involved in the regulation of the nir operon, although the mechanism for this regulation is still unknown. PMID:21602329

  13. Compartmentalized cyanophycin metabolism in the diazotrophic filaments of a heterocyst-forming cyanobacterium.

    PubMed

    Burnat, Mireia; Herrero, Antonia; Flores, Enrique

    2014-03-11

    Heterocyst-forming cyanobacteria are multicellular organisms in which growth requires the activity of two metabolically interdependent cell types, the vegetative cells that perform oxygenic photosynthesis and the dinitrogen-fixing heterocysts. Vegetative cells provide the heterocysts with reduced carbon, and heterocysts provide the vegetative cells with fixed nitrogen. Heterocysts conspicuously accumulate polar granules made of cyanophycin [multi-L-arginyl-poly (L-aspartic acid)], which is synthesized by cyanophycin synthetase and degraded by the concerted action of cyanophycinase (that releases ?-aspartyl-arginine) and isoaspartyl dipeptidase (that produces aspartate and arginine). Cyanophycin synthetase and cyanophycinase are present at high levels in the heterocysts. Here we created a deletion mutant of gene all3922 encoding isoaspartyl dipeptidase in the model heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120. The mutant accumulated cyanophycin and ?-aspartyl-arginine, and was impaired specifically in diazotrophic growth. Analysis of an Anabaena strain bearing an All3922-GFP (green fluorescent protein) fusion and determination of the enzyme activity in specific cell types showed that isoaspartyl dipeptidase is present at significantly lower levels in heterocysts than in vegetative cells. Consistently, isolated heterocysts released substantial amounts of ?-aspartyl-arginine. These observations imply that ?-aspartyl-arginine produced from cyanophycin in the heterocysts is transferred intercellularly to be hydrolyzed, producing aspartate and arginine in the vegetative cells. Our results showing compartmentalized metabolism of cyanophycin identify the nitrogen-rich molecule ?-aspartyl-arginine as a nitrogen vehicle in the unique multicellular system represented by the heterocyst-forming cyanobacteria. PMID:24550502

  14. Compartmentalized cyanophycin metabolism in the diazotrophic filaments of a heterocyst-forming cyanobacterium

    PubMed Central

    Burnat, Mireia; Herrero, Antonia; Flores, Enrique

    2014-01-01

    Heterocyst-forming cyanobacteria are multicellular organisms in which growth requires the activity of two metabolically interdependent cell types, the vegetative cells that perform oxygenic photosynthesis and the dinitrogen-fixing heterocysts. Vegetative cells provide the heterocysts with reduced carbon, and heterocysts provide the vegetative cells with fixed nitrogen. Heterocysts conspicuously accumulate polar granules made of cyanophycin [multi-L-arginyl-poly (L-aspartic acid)], which is synthesized by cyanophycin synthetase and degraded by the concerted action of cyanophycinase (that releases ?-aspartyl-arginine) and isoaspartyl dipeptidase (that produces aspartate and arginine). Cyanophycin synthetase and cyanophycinase are present at high levels in the heterocysts. Here we created a deletion mutant of gene all3922 encoding isoaspartyl dipeptidase in the model heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120. The mutant accumulated cyanophycin and ?-aspartyl-arginine, and was impaired specifically in diazotrophic growth. Analysis of an Anabaena strain bearing an All3922-GFP (green fluorescent protein) fusion and determination of the enzyme activity in specific cell types showed that isoaspartyl dipeptidase is present at significantly lower levels in heterocysts than in vegetative cells. Consistently, isolated heterocysts released substantial amounts of ?-aspartyl-arginine. These observations imply that ?-aspartyl-arginine produced from cyanophycin in the heterocysts is transferred intercellularly to be hydrolyzed, producing aspartate and arginine in the vegetative cells. Our results showing compartmentalized metabolism of cyanophycin identify the nitrogen-rich molecule ?-aspartyl-arginine as a nitrogen vehicle in the unique multicellular system represented by the heterocyst-forming cyanobacteria. PMID:24550502

  15. Ultradian metabolic rhythm in the diazotrophic cyanobacterium Cyanothece sp. ATCC 51142

    PubMed Central

    ?ervený, Jan; Sinetova, Maria A.; Valledor, Luis; Sherman, Louis A.; Nedbal, Ladislav

    2013-01-01

    The unicellular cyanobacterium Cyanothece sp. American Type Culture Collection (ATCC) 51142 is capable of performing oxygenic photosynthesis during the day and microoxic nitrogen fixation at night. These mutually exclusive processes are possible only by temporal separation by circadian clock or another cellular program. We report identification of a temperature-dependent ultradian metabolic rhythm that controls the alternating oxygenic and microoxic processes of Cyanothece sp. ATCC 51142 under continuous high irradiance and in high CO2 concentration. During the oxygenic photosynthesis phase, nitrate deficiency limited protein synthesis and CO2 assimilation was directed toward glycogen synthesis. The carbohydrate accumulation reduced overexcitation of the photosynthetic reactions until a respiration burst initiated a transition to microoxic N2 fixation. In contrast to the circadian clock, this ultradian period is strongly temperature-dependent: 17 h at 27 °C, which continuously decreased to 10 h at 39 °C. The cycle was expressed by an oscillatory modulation of net O2 evolution, CO2 uptake, pH, fluorescence emission, glycogen content, cell division, and culture optical density. The corresponding ultradian modulation was also observed in the transcription of nitrogenase-related nifB and nifH genes and in nitrogenase activities. We propose that the control by the newly identified metabolic cycle adds another rhythmic component to the circadian clock that reflects the true metabolic state depending on the actual temperature, irradiance, and CO2 availability. PMID:23878254

  16. Fur-type transcriptional repressors and metal homeostasis in the cyanobacterium Synechococcus sp. PCC 7002

    PubMed Central

    Ludwig, Marcus; Chua, Tiing Tiing; Chew, Chyue Yie; Bryant, Donald A.

    2015-01-01

    Metal homeostasis is a crucial cellular function for nearly all organisms. Some heavy metals (e.g., Fe, Zn, Co, Mo) are essential because they serve as cofactors for enzymes or metalloproteins, and chlorophototrophs such as cyanobacteria have an especially high demand for iron. At excessive levels, however, metals become toxic to cyanobacteria. Therefore, a tight control mechanism is essential for metal homeostasis. Metal homeostasis in microorganisms comprises two elements: metal acquisition from the environment and detoxification or excretion of excess metal ions. Different families of metal-sensing regulators exist in cyanobacteria and each addresses a more or less specific set of target genes. In this study the regulons of three Fur-type and two ArsR-SmtB-type regulators were investigated in a comparative approach in the cyanobacterium Synechococcus sp. PCC 7002. One Fur-type regulator controls genes for iron acquisition (Fur); one controls genes for zinc acquisition (Zur); and the third controls two genes involved in oxidative stress (Per). Compared to other well-investigated cyanobacterial strains, however, the set of target genes for each regulator is relatively small. Target genes for the two ArsR-SmtB transcriptional repressors (SmtB (SYNPCC7002_A2564) and SYNPCC7002_A0590) are involved in zinc homeostasis in addition to Zur. Their target genes, however, are less specific for zinc and point to roles in a broader heavy metal detoxification response. PMID:26582412

  17. Nostopeptolide plays a governing role during cellular differentiation of the symbiotic cyanobacterium Nostoc punctiforme.

    PubMed

    Liaimer, Anton; Helfrich, Eric J N; Hinrichs, Katrin; Guljamow, Arthur; Ishida, Keishi; Hertweck, Christian; Dittmann, Elke

    2015-02-10

    Nostoc punctiforme is a versatile cyanobacterium that can live either independently or in symbiosis with plants from distinct taxa. Chemical cues from plants and N. punctiforme were shown to stimulate or repress, respectively, the differentiation of infectious motile filaments known as hormogonia. We have used a polyketide synthase mutant that accumulates an elevated amount of hormogonia as a tool to understand the effect of secondary metabolites on cellular differentiation of N. punctiforme. Applying MALDI imaging to illustrate the reprogramming of the secondary metabolome, nostopeptolides were identified as the predominant difference in the pks2(-) mutant secretome. Subsequent differentiation assays and visualization of cell-type-specific expression of nostopeptolides via a transcriptional reporter strain provided evidence for a multifaceted role of nostopeptolides, either as an autogenic hormogonium-repressing factor or as a chemoattractant, depending on its extracellular concentration. Although nostopeptolide is constitutively expressed in the free-living state, secreted levels dynamically change before, during, and after the hormogonium differentiation phase. The metabolite was found to be strictly down-regulated in symbiosis with Gunnera manicata and Blasia pusilla, whereas other metabolites are up-regulated, as demonstrated via MALDI imaging, suggesting plants modulate the fine-balanced cross-talk network of secondary metabolites within N. punctiforme. PMID:25624477

  18. Nostopeptolide plays a governing role during cellular differentiation of the symbiotic cyanobacterium Nostoc punctiforme

    PubMed Central

    Liaimer, Anton; Helfrich, Eric J. N.; Hinrichs, Katrin; Guljamow, Arthur; Ishida, Keishi; Hertweck, Christian; Dittmann, Elke

    2015-01-01

    Nostoc punctiforme is a versatile cyanobacterium that can live either independently or in symbiosis with plants from distinct taxa. Chemical cues from plants and N. punctiforme were shown to stimulate or repress, respectively, the differentiation of infectious motile filaments known as hormogonia. We have used a polyketide synthase mutant that accumulates an elevated amount of hormogonia as a tool to understand the effect of secondary metabolites on cellular differentiation of N. punctiforme. Applying MALDI imaging to illustrate the reprogramming of the secondary metabolome, nostopeptolides were identified as the predominant difference in the pks2? mutant secretome. Subsequent differentiation assays and visualization of cell-type-specific expression of nostopeptolides via a transcriptional reporter strain provided evidence for a multifaceted role of nostopeptolides, either as an autogenic hormogonium-repressing factor or as a chemoattractant, depending on its extracellular concentration. Although nostopeptolide is constitutively expressed in the free-living state, secreted levels dynamically change before, during, and after the hormogonium differentiation phase. The metabolite was found to be strictly down-regulated in symbiosis with Gunnera manicata and Blasia pusilla, whereas other metabolites are up-regulated, as demonstrated via MALDI imaging, suggesting plants modulate the fine-balanced cross-talk network of secondary metabolites within N. punctiforme. PMID:25624477

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

    SciTech Connect

    Vermaas, Willem F.J.

    2006-03-14

    The broader goal of this project was to merge knowledge from genomic, metabolic, ultrastructural and other perspectives to understand how cyanobacteria live, adapt and are regulated. This understanding aids in metabolic engineering and synthetic biology efforts using this group of organisms that contribute greatly to global photosynthetic CO2 fixation and that are closely related to the ancestors of chloroplasts. This project focused on photosynthesis and respiration in the cyanobacterium Synechocystis sp. PCC 6803, which is spontaneously transformable and has a known genome sequence. Modification of these fundamental processes in this organism can lead to improved carbon sequestration and hydrogen production, as well as to generation of high-quality biomass. In our GTL-supported studies at Arizona State University we focus on cell structure and cell physiology in Synechocystis, with particular emphasis on thylakoid membrane formation and on metabolism related to photosynthesis and respiration. Results on (a) thylakoid membrane biogenesis, (b) fluxes through central carbon utilization pathways, and (c) distribution mechanisms between carbon storage compounds are presented. Together, these results help pave the way for metabolic engineering efforts that are likely to result in improved solar-powered carbon sequestration and bioenergy conversion. Fueled by the very encouraging results obtained in this project, we already have attracted interest from major companies in the use of cyanobacteria for biofuel production.

  20. Sequential splicing of a group II twintron in the marine cyanobacterium Trichodesmium.

    PubMed

    Pfreundt, Ulrike; Hess, Wolfgang R

    2015-01-01

    The marine cyanobacterium Trichodesmium is unusual in its genomic architecture as 40% of the genome is occupied by non-coding DNA. Although the majority of it is transcribed into RNA, it is not well understood why such a large non-coding genome fraction is maintained. Mobile genetic elements can contribute to genome expansion. Many bacteria harbor introns whereas twintrons, introns-in-introns, are rare and not known to interrupt protein-coding genes in bacteria. Here we show the sequential in vivo splicing of a 5400 nt long group II twintron interrupting a highly conserved gene that is associated with RNase HI in some cyanobacteria, but free-standing in others, including Trichodesmium erythraeum. We show that twintron splicing results in a putatively functional mRNA. The full genetic arrangement was found conserved in two geospatially distinct metagenomic datasets supporting its functional relevance. We further show that splicing of the inner intron yields the free intron as a true circle. This reaction requires the spliced exon reopening (SER) reaction to provide a free 5' exon. The fact that Trichodesmium harbors a functional twintron fits in well with the high intron load of these genomes, and suggests peculiarities in its genetic machinery permitting such arrangements. PMID:26577185

  1. Crystal Structure of Allophycocyanin from Marine Cyanobacterium Phormidium sp. A09DM

    PubMed Central

    Gupta, Gagan Deep; Madamwar, Datta

    2015-01-01

    Isolated phycobilisome (PBS) sub-assemblies have been widely subjected to X-ray crystallography analysis to obtain greater insights into the structure-function relationship of this light harvesting complex. Allophycocyanin (APC) is the phycobiliprotein always found in the PBS core complex. Phycocyanobilin (PCB) chromophores, covalently bound to conserved Cys residues of ?- and ?- subunits of APC, are responsible for solar energy absorption from phycocyanin and for transfer to photosynthetic apparatus. In the known APC structures, heterodimers of ?- and ?- subunits (known as ?? monomers) assemble as trimer or hexamer. We here for the first time report the crystal structure of APC isolated from a marine cyanobacterium (Phormidium sp. A09DM). The crystal structure has been refined against all the observed data to the resolution of 2.51 Å to Rwork (Rfree) of 0.158 (0.229) with good stereochemistry of the atomic model. The Phormidium protein exists as a trimer of ?? monomers in solution and in crystal lattice. The overall tertiary structures of ?- and ?- subunits, and trimeric quaternary fold of the Phormidium protein resemble the other known APC structures. Also, configuration and conformation of the two covalently bound PCB chromophores in the marine APC are same as those observed in fresh water cyanobacteria and marine red algae. More hydrophobic residues, however, constitute the environment of the chromophore bound to ?-subunit of the Phormidium protein, owing mainly to amino acid substitutions in the marine protein. PMID:25923120

  2. A biliverdin-binding cyanobacteriochrome from the chlorophyll d-bearing cyanobacterium Acaryochloris marina.

    PubMed

    Narikawa, Rei; Nakajima, Takahiro; Aono, Yuki; Fushimi, Keiji; Enomoto, Gen; Ni-Ni-Win; Itoh, Shigeru; Sato, Moritoshi; Ikeuchi, Masahiko

    2015-01-01

    Cyanobacteriochromes (CBCRs) are linear tetrapyrrole-binding photoreceptors in cyanobacteria that absorb visible and near-ultraviolet light. CBCRs are divided into two types based on the type of chromophore they contain: phycocyanobilin (PCB) or phycoviolobilin (PVB). PCB-binding CBCRs reversibly photoconvert at relatively long wavelengths, i.e., the blue-to-red region, whereas PVB-binding CBCRs reversibly photoconvert at shorter wavelengths, i.e., the near-ultraviolet to green region. Notably, prior to this report, CBCRs containing biliverdin (BV), which absorbs at longer wavelengths than do PCB and PVB, have not been found. Herein, we report that the typical red/green CBCR AM1_1557 from the chlorophyll d-bearing cyanobacterium Acaryochloris marina can bind BV almost comparable to PCB. This BV-bound holoprotein reversibly photoconverts between a far red light-absorbing form (Pfr, ?max = 697?nm) and an orange light-absorbing form (Po, ?max = 622?nm). At room temperature, Pfr fluoresces with a maximum at 730?nm. These spectral features are red-shifted by 48~77?nm compared with those of the PCB-bound domain. Because the absorbance of chlorophyll d is red-shifted compared with that of chlorophyll a, the BV-bound AM1_1557 may be a physiologically relevant feature of A. marina and is potentially useful as an optogenetic switch and/or fluorescence imager. PMID:25609645

  3. Crystal Structure of Allophycocyanin from Marine Cyanobacterium Phormidium sp. A09DM.

    PubMed

    Sonani, Ravi Raghav; Gupta, Gagan Deep; Madamwar, Datta; Kumar, Vinay

    2015-01-01

    Isolated phycobilisome (PBS) sub-assemblies have been widely subjected to X-ray crystallography analysis to obtain greater insights into the structure-function relationship of this light harvesting complex. Allophycocyanin (APC) is the phycobiliprotein always found in the PBS core complex. Phycocyanobilin (PCB) chromophores, covalently bound to conserved Cys residues of ?- and ?- subunits of APC, are responsible for solar energy absorption from phycocyanin and for transfer to photosynthetic apparatus. In the known APC structures, heterodimers of ?- and ?- subunits (known as ?? monomers) assemble as trimer or hexamer. We here for the first time report the crystal structure of APC isolated from a marine cyanobacterium (Phormidium sp. A09DM). The crystal structure has been refined against all the observed data to the resolution of 2.51 Å to Rwork (Rfree) of 0.158 (0.229) with good stereochemistry of the atomic model. The Phormidium protein exists as a trimer of ?? monomers in solution and in crystal lattice. The overall tertiary structures of ?- and ?- subunits, and trimeric quaternary fold of the Phormidium protein resemble the other known APC structures. Also, configuration and conformation of the two covalently bound PCB chromophores in the marine APC are same as those observed in fresh water cyanobacteria and marine red algae. More hydrophobic residues, however, constitute the environment of the chromophore bound to ?-subunit of the Phormidium protein, owing mainly to amino acid substitutions in the marine protein. PMID:25923120

  4. Response of multiple herbicide resistant strain of diazotrophic cyanobacterium, Anabaena variabilis, exposed to atrazine and DCMU.

    PubMed

    Singh, Surendra; Datta, Pallavi; Tirkey, Archna

    2011-04-01

    Effect of two photosynthetic inhibitor herbicides, atrazine (both purified and formulated) and [3-(3,4-dichlorophenyl)-1,1-dimethyl urea] (DCMU), on the growth, macromolecular contents, heterocyst frequency, photosynthetic O2 evolution and dark O2 uptake of wild type and multiple herbicide resistant (MHR) strain of diazotrophic cyanobacterium A. variabilis was studied. Cyanobacterial strains showed gradual inhibition in growth with increasing dosage of herbicides. Both wild type and MHR strain tolerated < 6.0 mg L(-1) of atrazine (purified), < 2.0 mg L(-1) of atrazine (formulated) and < 0.4 mg L(-1) of DCMU indicating similar level of herbicide tolerance. Atrazine (pure) (8.0 mg L(-1)) and 4.0 mg L(-1) of atrazine (formulated) were growth inhibitory concentrations (lethal) for both wild type and MHR strain indicating formulated atrazine was more toxic than the purified form. Comparatively lower concentrations of DCMU were found to be lethal for wild type and MHR strain, respectively. Thus, between the two herbicides tested DCMU was more growth toxic than atrazine. At sublethal dosages of herbicides, photosynthetic O2 evolution showed highest inhibition followed by chlorophyll a, phycobhiliproteins and heterocyst differentiation as compared to carotenoid, protein and respiratory O2 uptake. PMID:21614895

  5. Sequential splicing of a group II twintron in the marine cyanobacterium Trichodesmium

    PubMed Central

    Pfreundt, Ulrike; Hess, Wolfgang R.

    2015-01-01

    The marine cyanobacterium Trichodesmium is unusual in its genomic architecture as 40% of the genome is occupied by non-coding DNA. Although the majority of it is transcribed into RNA, it is not well understood why such a large non-coding genome fraction is maintained. Mobile genetic elements can contribute to genome expansion. Many bacteria harbor introns whereas twintrons, introns-in-introns, are rare and not known to interrupt protein-coding genes in bacteria. Here we show the sequential in vivo splicing of a 5400 nt long group II twintron interrupting a highly conserved gene that is associated with RNase HI in some cyanobacteria, but free-standing in others, including Trichodesmium erythraeum. We show that twintron splicing results in a putatively functional mRNA. The full genetic arrangement was found conserved in two geospatially distinct metagenomic datasets supporting its functional relevance. We further show that splicing of the inner intron yields the free intron as a true circle. This reaction requires the spliced exon reopening (SER) reaction to provide a free 5? exon. The fact that Trichodesmium harbors a functional twintron fits in well with the high intron load of these genomes, and suggests peculiarities in its genetic machinery permitting such arrangements. PMID:26577185

  6. A Gene Cluster Involved in Metal Homeostasis in the Cyanobacterium Synechocystis sp. Strain PCC 6803

    PubMed Central

    García-Domínguez, Mario; Lopez-Maury, Luis; Florencio, Francisco J.; Reyes, José C.

    2000-01-01

    A gene cluster composed of nine open reading frames (ORFs) involved in Ni2+, Co2+, and Zn2+ sensing and tolerance in the cyanobacterium Synechocystis sp. strain PCC 6803 has been identified. The cluster includes an Ni2+ response operon and a Co2+ response system, as well as a Zn2+ response system previously described. Expression of the Ni2+ response operon (nrs) was induced in the presence of Ni2+ and Co2+. Reduced Ni2+ tolerance was observed following disruption of two ORFs of the operon (nrsA and nrsD). We also show that the nrsD gene encodes a putative Ni2+ permease whose carboxy-terminal region is a metal binding domain. The Co2+ response system is composed of two divergently transcribed genes, corR and corT, mutants of which showed decreased Co2+ tolerance. Additionally, corR mutants showed an absence of Co2+-dependent induction of corT, indicating that CorR is a transcriptional activator of corT. To our knowledge, CorR is the first Co2+-sensing transcription factor described. Our data suggest that this region of the Synechocystis sp. strain PCC 6803 genome is involved in sensing and homeostasis of Ni2+, Co2+, and Zn2+. PMID:10692354

  7. Hydrogen sulfide can inhibit and enhance oxygenic photosynthesis in a cyanobacterium from sulfidic springs.

    PubMed

    Klatt, Judith M; Haas, Sebastian; Yilmaz, Pelin; de Beer, Dirk; Polerecky, Lubos

    2015-09-01

    We used microsensors to investigate the combinatory effect of hydrogen sulfide (H2 S) and light on oxygenic photosynthesis in biofilms formed by a cyanobacterium from sulfidic springs. We found that photosynthesis was both positively and negatively affected by H2 S: (i) H2 S accelerated the recovery of photosynthesis after prolonged exposure to darkness and anoxia. We suggest that this is possibly due to regulatory effects of H2 S on photosystem I components and/or on the Calvin cycle. (ii) H2 S concentrations of up to 210??M temporarily enhanced the photosynthetic rates at low irradiance. Modelling showed that this enhancement is plausibly based on changes in the light-harvesting efficiency. (iii) Above a certain light-dependent concentration threshold H2 S also acted as an inhibitor. Intriguingly, this inhibition was not instant but occurred only after a specific time interval that decreased with increasing light intensity. That photosynthesis is most sensitive to inhibition at high light intensities suggests that H2 S inactivates an intermediate of the oxygen evolving complex that accumulates with increasing light intensity. We discuss the implications of these three effects of H2 S in the context of cyanobacterial photosynthesis under conditions with diurnally fluctuating light and H2 S concentrations, such as those occurring in microbial mats and biofilms. PMID:25630511

  8. Photosynthetic performance of a helical tubular photobioreactor incorporating the cyanobacterium spirulina platensis.

    PubMed

    Watanabe, Y; de la Noüe, J; Hall, D O

    1995-07-20

    The photosynthetic performance of a helical tubular photobioreactor ("Biocoil"), incorporating the filamentous cyanobacterium Spirulina platensis, was investigated. The photobioreactor was constructed in a cylindrical shape (0.9 m high) with a 0.25-m(2)basal area and a photostage comprising 60 m of transparent PVC tubing of 1.6-cm inner diameter (volume = 12.1 L). The inner surface of the cylinder (area = 1.32 m(2)) was illuminated with cool white fluorescent lamps; the energy input of photosynthetically active radiation(PAR, 400 to 700 nm) into the photobioreactor was 2920 kJ per day. An air-lift system ncorporating 4%CO(2) was used to circulate the growth medium in the tubing. The maximum productivity achieved in batch culture was 7.18 g dry biomass per day [0.51 g . d biomass/L . day, or 5.44 g . d biomass/m(2)(inner surface of cylindrical shape)/day] which corresponded to a photosynthetic (PAR) efficiency of 5.45%. The CO(2) was efficiently removed from the gaseous stream; monitoring the CO(2) the outlet and inlet gas streams showed a 70% removal of CO(2) from the inlet gas over an 8-h period with almost maximum growth rate. (c) 1995 John Wiley & Sons, Inc. PMID:18623400

  9. Paired cloning vectors for complementation of mutations in the cyanobacterium Anabaena sp. strain PCC 7120

    SciTech Connect

    Wolk, C. Peter Wolk; Fan, Qing; Zhou, Ruanbao; Huang, Guocun; Lechno-Yossef, Sigal; Kuritz, Tanya; Wojciuch, Elizabeth

    2007-01-01

    The clones generated in a sequencing project represent a resource for subsequent analysis of the organism whose genome has been sequenced. We describe an interrelated group of cloning vectors that either integrate into the genome or replicate, and that enhance the utility, for developmental and other studies, of the clones used to determine the genomic sequence of the cyanobacterium, Anabaena sp. strain PCC 7120. One integrating vector is a mobilizable BAC vector that was used both to generate bridging clones and to complement transposon mutations. Upon addition of a cassette that permits mobilization and selection, pUC-based sequencing clones can also integrate into the genome and thereupon complement transposon mutations. The replicating vectors are based on cyanobacterial plasmid pDU1, whose sequence we report, and on broad-host-range plasmid RSF1010. The RSF1010- and pDU1-based vectors provide the opportunity to express different genes from either cell-type-specific or -generalist promoters, simultaneously from different plasmids in the same cyanobacterial cells. We show that pDU1 ORF4 and its upstream region play an essential role in the replication and copy number of pDU1, and that ORFs alr2887 and alr3546 (hetF{sub A}) of Anabaena sp. are required specifically for fixation of dinitrogen under oxic conditions.

  10. Exposure of mallards (Anas platyrhynchos) to the hepatotoxic cyanobacterium Nodularia spumigena

    USGS Publications Warehouse

    Sipia, V.O.; Franson, J.C.; Sjovall, O.; Pflugmacher, S.; Shearn-Bochsler, V.; Rocke, T.E.; Meriluoto, J.A.O.

    2008-01-01

    Nodularin (NODLN) is a cyclic pentapeptide hepatotoxin produced by the cyanobacterium Nodularia spumigena, which forms extensive blooms during the summer in the Baltic Sea. Nodularin was detected in liver, muscle and/or feather samples of several common eiders (Somateria mollissima) from the Gulf of Finland (northern Baltic Sea) in 2002-2005. Published information on the adverse effects of NODLN in marine birds is scarce. The aim of this study was to evaluate the toxicity of NODLN, and determine the concentrations of NODLN in liver and muscle tissue in mallards (Anas platyrhynchos) exposed to N. spumigena. Mallards received a single or multiple exposure via oral gavage with an aqueous slurry containing toxic N. spumigena. Dosages ranged from 200 to 600 ??g NODLN per kg body weight (bw). There were minimal histopathological changes in liver tissue, and brain cholinesterase activity did not differ among treatment groups. Concentrations of NODLN measured by LC-MS in liver varied between approximately 3-120 ??g kg-1 dry weight (dw) and ducks receiving multiple exposures had significantly greater liver toxin levels than ducks receiving the two lowest single exposures. In muscle, NODLN concentrations were approximately 2-6 ??g kg-1 dw, but did not differ significantly among exposure groups. This is the first in vivo lab study examining the effects and bioaccumulation of NODLN from N. spumigena in birds. The mallards in this study were resistant to adverse effects and did not bioaccumulate substantial levels of NODLN at the doses given. ?? 2008 Taylor & Francis.

  11. Release of ecologically relevant metabolites by the cyanobacterium Synechococcus elongatus?CCMP 1631.

    PubMed

    Fiore, Cara L; Longnecker, Krista; Kido Soule, Melissa C; Kujawinski, Elizabeth B

    2015-10-01

    Photoautotrophic plankton in the surface ocean release organic compounds that fuel secondary production by heterotrophic bacteria. Here we show that an abundant marine cyanobacterium, Synechococcus elongatus, contributes a variety of nitrogen-rich and sulfur-containing compounds to dissolved organic matter. A combination of targeted and untargeted metabolomics and genomic tools was used to characterize the intracellular and extracellular metabolites of S.?elongatus. Aromatic compounds, such as 4-hydroxybenzoic acid and phenylalanine, as well as nucleosides (e.g. thymidine, 5'-methylthioadenosine, xanthosine), the organosulfur compound 3-mercaptopropionate, and the plant auxin indole 3-acetic acid, were released by S.?elongatus at multiple time points during its growth. Further, the amino acid kynurenine was found to accumulate in the media even though it was not present in the predicted metabolome of S.?elongatus. This indicates that some metabolites, including those not predicted by an organism's genome, are likely excreted into the environment as waste; however, these molecules may have broader ecological relevance if they are labile to nearby microbes. The compounds described herein provide excellent targets for quantitative analysis in field settings to assess the source and lability of dissolved organic matter in situ. PMID:25970745

  12. Anaerobic biosynthesis of unsaturated fatty acids in the cyanobacterium, Oscillatoria limnetica

    NASA Technical Reports Server (NTRS)

    Jahnke, L. L.; Lee, B.; Sweeney, M. J.; Klein, H. P.

    1989-01-01

    The mechanism for synthesis of monounsaturated fatty acids under aerobic and anaerobic conditions was studied in the facultative anaerobic cyanobacterium, Oscillatoria limnetica. The hexadecenoic acid (C16:1) of aerobically grown O. limnetica was shown to contain both the delta 7 (79%) and delta 9 (21%) isomers, while the octadecenoic (C18:1) acid was entirely the delta 9 acid. Incorporation of [2-14C] acetate into the fatty acids under aerobic conditions resulted in synthesis of the delta 7 and delta 9 C16:1 and the delta 9 C18:1. Synthesis of unsaturated fatty acids in the presence of DCMU required sulfide. Anaerobic incubations in the presence of DCMU and sulfide (less than 0.003% atmospheric oxygen) resulted in a two-fold increase in monounsaturated fatty acids of both delta 7 and delta 9 C16:1 and delta 9 and delta 11 C18:1. The synthesis of these is characteristic of a bacterial-type, anaerobic pathway.

  13. Interplay between gold nanoparticle biosynthesis and metabolic activity of cyanobacterium Synechocystis sp. PCC 6803

    NASA Astrophysics Data System (ADS)

    Focsan, Monica; Ardelean, Ioan I.; Craciun, Constantin; Astilean, Simion

    2011-12-01

    Many microorganisms have long been known to be able to synthesize nanoparticles either in extracellular media or inside cells but the biochemical mechanisms involved in biomineralization are still poorly understood. In this paper we report the intracellular synthesis of gold nanoparticles (GNPs) by the cyanobacterium Synechocystis sp. PCC 6803 exposed to an aqueous solution of chloroauric acid. We assess the interplay between the biomineralization process and the metabolic activities (i.e. photosynthesis and respiration) of cyanobacteria cells by correlating the GNP synthesis yield with the amount of respiratory and photosynthetic oxygen exchange. The biogenic GNPs are compared in terms of their internalization and biological effects to GNPs synthesized by a standard citrate reduction procedure (cGNPs). The TEM analysis, in conjunction with spectroscopic measurements (i.e. surface plasmon resonance, fluorescence quenching and surface-enhanced Raman scattering, SERS), reveals the localization of biogenic GNPs at the level of intracytoplasmic membranes whereas the pre-formed cGNPs are located at the level of external cellular membrane. Our findings have implications for better understanding the process of biomineralization and assessing the potential risks associated with the accumulation of nanomaterials by various biological systems.

  14. Characterization of red-shifted phycobilisomes isolated from the chlorophyll f-containing cyanobacterium Halomicronema hongdechloris.

    PubMed

    Li, Yaqiong; Lin, Yuankui; Garvey, Christopher J; Birch, Debra; Corkery, Robert W; Loughlin, Patrick C; Scheer, Hugo; Willows, Robert D; Chen, Min

    2016-01-01

    Phycobilisomes are the main light-harvesting protein complexes in cyanobacteria and some algae. It is commonly accepted that these complexes only absorb green and orange light, complementing chlorophyll absorbance. Here, we present a new phycobilisome derived complex that consists only of allophycocyanin core subunits, having red-shifted absorption peaks of 653 and 712nm. These red-shifted phycobiliprotein complexes were isolated from the chlorophyll f-containing cyanobacterium, Halomicronema hongdechloris, grown under monochromatic 730nm-wavelength (far-red) light. The 3D model obtained from single particle analysis reveals a double disk assembly of 120-145Å with two ?/? allophycocyanin trimers fitting into the two separated disks. They are significantly smaller than typical phycobilisomes formed from allophycocyanin subunits and core-membrane linker proteins, which fit well with a reduced distance between thylakoid membranes observed from cells grown under far-red light. Spectral analysis of the dissociated and denatured phycobiliprotein complexes grown under both these light conditions shows that the same bilin chromophore, phycocyanobilin, is exclusively used. Our findings show that red-shifted phycobilisomes are required for assisting efficient far-red light harvesting. Their discovery provides new insights into the molecular mechanisms of light harvesting under extreme conditions for photosynthesis, as well as the strategies involved in flexible chromatic acclimation to diverse light conditions. PMID:26514405

  15. Diazotrophic specific cytochrome c oxidase required to overcome light stress in the cyanobacterium Nostoc muscorum.

    PubMed

    Bhargava, Santosh; Chouhan, Shweta

    2016-01-01

    Diazotrophic, filamentous and heterocystous cyanobacterium Nostoc muscorum perform photosynthesis in vegetative whereas nitrogen fixation occurs in heterocyst only. However, despite their metabolic plasticity, respiration takes place both in vegetative cells and heterocysts. The role of the respiratory electron transport system and terminal oxidases under light stress is not evident so far. As compared to the diazotrophically grown cultures, the non-diazotrophically grown cultures of the N. muscorum show a slight decrease in their growth, chlorophyll a contents and photosynthetic O2 evolution under light stress. Whereas respiratory O2 uptake under identical stress condition increases several fold. Likewise, nitrogen fixing enzyme i.e. nitrogenase over-expresses itself under light stress condition. The terminal enzyme of respiratory electron transport chain i.e. cytochrome c oxidase shows more activity under light stress, whilst light stress has no impact on Ca(++)-dependent ATPase activity. This leads to the conclusion that under light stress, cytochrome c oxidase plays a vital role in mitigating given light stress. PMID:26712617

  16. Anoxygenic Photosynthesis Controls Oxygenic Photosynthesis in a Cyanobacterium from a Sulfidic Spring

    PubMed Central

    Al-Najjar, Mohammad A. A.; Yilmaz, Pelin; Lavik, Gaute; de Beer, Dirk; Polerecky, Lubos

    2015-01-01

    Before the Earth's complete oxygenation (0.58 to 0.55 billion years [Ga] ago), the photic zone of the Proterozoic oceans was probably redox stratified, with a slightly aerobic, nutrient-limited upper layer above a light-limited layer that tended toward euxinia. In such oceans, cyanobacteria capable of both oxygenic and sulfide-driven anoxygenic photosynthesis played a fundamental role in the global carbon, oxygen, and sulfur cycle. We have isolated a cyanobacterium, Pseudanabaena strain FS39, in which this versatility is still conserved, and we show that the transition between the two photosynthetic modes follows a surprisingly simple kinetic regulation controlled by this organism's affinity for H2S. Specifically, oxygenic photosynthesis is performed in addition to anoxygenic photosynthesis only when H2S becomes limiting and its concentration decreases below a threshold that increases predictably with the available ambient light. The carbon-based growth rates during oxygenic and anoxygenic photosynthesis were similar. However, Pseudanabaena FS39 additionally assimilated NO3? during anoxygenic photosynthesis. Thus, the transition between anoxygenic and oxygenic photosynthesis was accompanied by a shift of the C/N ratio of the total bulk biomass. These mechanisms offer new insights into the way in which, despite nutrient limitation in the oxic photic zone in the mid-Proterozoic oceans, versatile cyanobacteria might have promoted oxygenic photosynthesis and total primary productivity, a key step that enabled the complete oxygenation of our planet and the subsequent diversification of life. PMID:25576611

  17. Outdoor cultivation of a nitrogen-fixing marine cyanobacterium, Anabaena sp. ATCC 33047.

    PubMed

    Moreno, José; Vargas, M Angeles; Rodríguez, Herminia; Rivas, Joaquín; Guerrero, Miguel G

    2003-07-01

    Optimization of conditions for outdoor production of the nitrogen-fixing cyanobacterium Anabaena sp. ATCC 33047 has been pursued. In open ponds operated under semi-continuous regime biomass productivity values achieved ranged from 9 g (dry weight) m(-2) per day, in winter, to over 20 g m(-2) per day, in summer, provided that key operation parameters, including cell density, were optimized. Under these conditions the efficiency of solar energy conversion by the cells was fairly constant throughout the year, with photosynthetic efficiency values higher than 2%. The cyanobacterial biomass was rich in high-value phycobiliproteins, namely allophycocyanin and phycocyanin, for which open cultures of marine Anabaena represent a most interesting production system. The performance of Anabaena cultures operated under continuous regime in a closed tubular reactor has also been assessed outdoors, in winter. Biomass productivity values similar to those obtained in the ponds have been recorded for the closed system. Additionally, under these conditions, the cells excreted to the medium large amounts of a previously characterized exopolysaccharide, at production rates as high as 35 g m(-2) per day (1.4 g l(-1) per day). Properly operated closed cultures of this strain of Anabaena appear most suitable for outdoor mass production of valuable extracellular polysaccharides. PMID:12919797

  18. Proteome-Wide Analysis and Diel Proteomic Profiling of the Cyanobacterium Arthrospira platensis PCC 8005

    PubMed Central

    Matallana-Surget, Sabine; Derock, Jérémy; Leroy, Baptiste; Badri, Hanène; Deschoenmaeker, Frédéric; Wattiez, Ruddy

    2014-01-01

    The filamentous cyanobacterium Arthrospira platensis has a long history of use as a food supply and it has been used by the European Space Agency in the MELiSSA project, an artificial microecosystem which supports life during long-term manned space missions. This study assesses progress in the field of cyanobacterial shotgun proteomics and light/dark diurnal cycles by focusing on Arthrospira platensis. Several fractionation workflows including gel-free and gel-based protein/peptide fractionation procedures were used and combined with LC-MS/MS analysis, enabling the overall identification of 1306 proteins, which represents 21% coverage of the theoretical proteome. A total of 30 proteins were found to be significantly differentially regulated under light/dark growth transition. Interestingly, most of the proteins showing differential abundance were related to photosynthesis, the Calvin cycle and translation processes. A novel aspect and major achievement of this work is the successful improvement of the cyanobacterial proteome coverage using a 3D LC-MS/MS approach, based on an immobilized metal affinity chromatography, a suitable tool that enabled us to eliminate the most abundant protein, the allophycocyanin. We also demonstrated that cell growth follows a light/dark cycle in A. platensis. This preliminary proteomic study has highlighted new characteristics of the Arthrospira platensis proteome in terms of diurnal regulation. PMID:24914774

  19. Primary structure of the peptidoglycan from the unicellular cyanobacterium Synechocystis sp. strain PCC 6714.

    PubMed Central

    Jürgens, U J; Drews, G; Weckesser, J

    1983-01-01

    A peptidoglycan fraction free of non-peptidoglycan components was isolated from the unicellular cyanobacterium Synechocystis sp. strain PCC 6714. Hydrofluoric acid treatment (48%, 0 degrees C, 48 h) cleaved off from the peptidoglycan non-peptidoglycan glucosamine, mannosamine, and mannose. The purified peptidoglycan consists of N-acetyl muramic acid, N-acetyl glucosamine, L-alanine, D-alanine, D-glutamic acid, and meso-diaminopimelic acid in approximately equimolar amounts. At least partial amidation of carboxy groups in the peptide subunits is indicated. Peptide analyses and 2,4-dinitrophenyl studies of partial acid hydrolysates revealed the structure of the Synechocystis sp. strain PCC 6714 peptidoglycan to belong to the A1 gamma type (direct cross-linkage) of peptidoglycan classification. The degree of cross-linkage is about 56% and thus is in the range of that found in gram-positive bacteria. Some of the peptide units are present as tripeptides lacking the carboxy-terminal D-alanine. Images PMID:6131881

  20. Proteome-wide analysis and diel proteomic profiling of the cyanobacterium Arthrospira platensis PCC 8005.

    PubMed

    Matallana-Surget, Sabine; Derock, Jérémy; Leroy, Baptiste; Badri, Hanène; Deschoenmaeker, Frédéric; Wattiez, Ruddy

    2014-01-01

    The filamentous cyanobacterium Arthrospira platensis has a long history of use as a food supply and it has been used by the European Space Agency in the MELiSSA project, an artificial microecosystem which supports life during long-term manned space missions. This study assesses progress in the field of cyanobacterial shotgun proteomics and light/dark diurnal cycles by focusing on Arthrospira platensis. Several fractionation workflows including gel-free and gel-based protein/peptide fractionation procedures were used and combined with LC-MS/MS analysis, enabling the overall identification of 1306 proteins, which represents 21% coverage of the theoretical proteome. A total of 30 proteins were found to be significantly differentially regulated under light/dark growth transition. Interestingly, most of the proteins showing differential abundance were related to photosynthesis, the Calvin cycle and translation processes. A novel aspect and major achievement of this work is the successful improvement of the cyanobacterial proteome coverage using a 3D LC-MS/MS approach, based on an immobilized metal affinity chromatography, a suitable tool that enabled us to eliminate the most abundant protein, the allophycocyanin. We also demonstrated that cell growth follows a light/dark cycle in A. platensis. This preliminary proteomic study has highlighted new characteristics of the Arthrospira platensis proteome in terms of diurnal regulation. PMID:24914774

  1. Cytoplasmic membrane changes during adaptation of the fresh water cyanobacterium Synechococcus 6311 to salinity

    NASA Technical Reports Server (NTRS)

    Lefort-Tran, M.; Pouphile, M.; Spath, S.; Packer, L.

    1988-01-01

    In this investigation, changes were characterized in cell structure and cytoplasmic membrane organization that occur when the freshwater cyanobacterium Synechococcus 6311 is transferred from 'low salt' (0.03 molar NaCl) to 'high salt' (0.5 molar NaCl) media (i.e. sea water concentration). Cells were examined at several time points after the imposition of the salt stress and compared to control cells, in thin sections and freeze fracture electron microscopy, and by flow cytometry. One minute after exposure to high salt, i.e. 'salt shock', virtually all intracellular granules disappeared, the density of the cytoplasm decreased, and the appearance of DNA material was changed. Glycogen and other granules, however, reappeared by 4 hours after salt exposure. The organization of the cytoplasmic membrane undergoes major reorganization following salt shock. Freeze-fracture electron microscopy showed that small intramembrane particles (diameter 7.5 and 8.5 nanometers) are reduced in number by two- to fivefold, whereas large particles, (diameters 14.5 and 17.5 nanometers) increase two- to fourfold in frequency, compared to control cells grown in low salt medium. The changes in particle size distribution suggest synthesis of new membrane proteins, in agreement with the known increases in respiration, cytochrome oxidase, and sodium proton exchange activity of the cytoplasmic membrane.

  2. Changes in photosynthesis and pigmentation in an agp deletion mutant of the cyanobacterium Synechocystis sp.

    PubMed

    Miao, Xiaoling; Wu, Qingyu; Wu, Guifang; Zhao, Nanming

    2003-03-01

    The agp gene encoding ADP-glucose pyrophosphorylase is involved in cyanobacterial glycogen synthesis. By in vitro DNA recombination technology, agp deletion mutant (agp-) of cyanobacterium Synechocystis sp. PCC 6803 was constructed. This mutation led to a complete absence of glycogen biosynthesis. As compared with WT (wild type), a 60% decrease in ratio of the c-phycocyanine/chlorophyll a and no significant change in the carotenoid/chlorophyll a were observed in agp- cells. The agp- mutant had 38% less photosynthetic capacity when grown in light over 600 micromol m(-2) s(-1). Under lower light intensity, the final biomass of the mutant strain was only 1.1 times of that of the WT strain under mixotrophic condition after 6 d culture. Under higher light intensity, however, the final biomass of the WT strain under mixotrophic conditions was 3 times that of the mutant strain after 6 d culture and 1.5 times under photoautotrophic conditions. The results indicate that there is a minimum requirement for glycogen synthesis for normal growth and development in cyanobacteria. PMID:12882559

  3. Draft genome sequence of Rubidibacter lacunae strain KORDI 51-2T, a cyanobacterium isolated from seawater of Chuuk lagoon

    PubMed Central

    Choi, Dong Han; Ryu, Jee-Youn; Kwon, Kae-Kyoung; Lee, Jung-Hyun; Kim, Changhoon; Lee, Charity M.

    2013-01-01

    A photoautotrophic cyanobacterium, Rubidibacter lacunae was reported in 2008 for the first time. The type strain, KORDI 51-2T, was isolated from seawater of Chuuk lagoon located in a tropical area. Although it belonged to a clade exclusively comprised of extremely halotolerant strains by phylogenetic analyses, R. lacunae is known to be incapable of growth at high salt concentration over 10%. Here we report the main features of the genome of R. lacunae strain KORDI 51-2T. The genome of R. lacunae contains a gene cluster for phosphonate utilization encoding three transporters, one regulator and eight C-P lyase subunits. PMID:24501656

  4. Cloning of a copper resistance gene cluster from the cyanobacterium Synechocystis sp. PCC 6803 by recombineering recovery.

    PubMed

    Gittins, John R

    2015-07-01

    A copper resistance gene cluster (6 genes, ?8.2 kb) was isolated from the cyanobacterium Synechocystis sp. PCC 6803 by recombineering recovery (RR). Following integration of a narrow-host-range plasmid vector adjacent to the target region in the Synechocystis genome (pSYSX), DNA was isolated from transformed cells and the plasmid plus flanking sequence circularized by recombineering to precisely clone the gene cluster. Complementation of a copper-sensitive Escherichia coli mutant demonstrated the functionality of the pcopM gene encoding a copper-binding protein. RR provides a novel alternative method for cloning large DNA fragments from species that can be transformed by homologous recombination. PMID:25980606

  5. Effects of a Simulated Martian UV Flux on the Cyanobacterium, Chroococcidiopsis sp. 029

    NASA Astrophysics Data System (ADS)

    Cockell, Charles S.; Schuerger, Andrew C.; Billi, Daniela; Imre Friedmann, E.; Panitz, Corinna

    2005-06-01

    Dried monolayers of Chroococcidiopsis sp. 029, a desiccation-tolerant, endolithic cyanobacterium, were exposed to a simulated martian-surface UV and visible light flux, which may also approximate to the worst-case scenario for the Archean Earth. After 5 min, there was a 99% loss of cell viability, and there were no survivors after 30 min. However, this survival was approximately 10 times higher than that previously reported for Bacillus subtilis. We show that under 1 mm of rock, Chroococcidiopsis sp. could survive (and potentially grow) under the high martian UV flux if water and nutrient requirements for growth were met. In isolated cells, phycobilisomes and esterases remained intact hours after viability was lost. Esterase activity was reduced by 99% after a 1-h exposure, while 99% loss of autofluorescence required a 4-h exposure. However, cell morphology was not changed, and DNA was still detectable by 4',6-diamidino-2-phenylindole staining after an 8-h exposure (equivalent to approximately 1 day on Mars at the equator). Under 1 mm of simulant martian soil or gneiss, the effect of UV radiation could not be detected on esterase activity or autofluorescence after 4 h. These results show that under the intense martian UV flux the morphological signatures of life can persist even after viability, enzymatic activity, and pigmentation have been destroyed. Finally, the global dispersal of viable, isolated cells of even this desiccation-tolerant, ionizing-radiation-resistant microorganism on Mars is unlikely as they are killed quickly by unattenuated UV radiation when in a desiccated state. These findings have implications for the survival of diverse microbial contaminants dispersed during the course of human exploratory class missions on the surface of Mars.

  6. Increase of Nitrogenase Activity in the Blue-Green Alga Nostoc muscorum (Cyanobacterium)

    PubMed Central

    Scherer, Siegfried; Kerfin, Wolfgang; Böger, Peter

    1980-01-01

    Preincubation of the blue-green alga (cyanobacterium) Nostoc muscorum under hydrogen or argon (nongrowing conditions, neither CO2 nor N2 or bound nitrogen present) in the light resulted in a two- to fourfold increase of light-induced hydrogen evolution and a 30% increase of acetylene reduction. Preincubation under the same gases in the dark led to a decrease of both activities. Cultivation of algae under a hydrogen-containing atmosphere (N2, H2, CO2) increased neither hydrogen nor ethylene evolution by the cells. Formation of both ethylene and hydrogen is due to nitrogenase activity, which apparently was induced by the absence of N2 or bound nitrogen and not by the presence of hydrogen. Inhibitors of protein biosynthesis prevented the increase of nitrogenase activity. Hydrogen uptake by the cells was almost unaffected under all of these conditions. With either ammonia or chloramphenicol present, nitrogenase activity decreased under growing conditions (i.e., an atmosphere of N2 and CO2). The kinetics of decrease were the same with ammonia or chloramphenicol, which was interpreted as being due to rapid protein breakdown with a half-life of approximately 4 h. The decay of nitrogenase activity caused by chloramphenicol could be counteracted by nitrogenase-inducing conditions, i.e., by the absence of N2 or bound nitrogen. A cell-free system from preconditioned algae with an adenosine 5?-triphosphate-generating system exhibited the same increase or decrease of nitrogenase activity as the intact cell filaments, indicating that this effect resided in the nitrogenase complex only. We tentatively assume that not the whole nitrogenase complex, but merely a subunit or a special protein with regulatory function, is susceptible to fast turnover. PMID:6777364

  7. Purification, characterization and function of bacterioferritin from the cyanobacterium Synechocystis P.C.C. 6803.

    PubMed Central

    Laulhère, J P; Labouré, A M; Van Wuytswinkel, O; Gagnon, J; Briat, J F

    1992-01-01

    Storage and buffering of iron is achieved by a class of proteins, the ferritins, widely distributed throughout the living kingdoms. All ferritins have in common their three-dimensional structure and their ability to store large amounts of iron in their central cavity. However, eukaryotic ferritins from plants and animals and bacterioferritins have no sequence similarity, and besides non-haem iron bacterioferritins contain haem residues whereas eukaryotic ferritins do not. In this paper we report the first purification and characterization of a bacterioferritin from a cyanobacterium. It has a molecular mass of 400 kDa and is built up from 19 kDa subunits. Its N-terminal sequence shows 73% identity with that of the Escherichia coli bacterioferritin subunit. It contains 2300 atoms of iron and 1500 molecules of phosphate per ferritin molecule and 0.25 haem residue per subunit; the alpha-peak of the cytochrome has its maximum at 559 nm. In contrast with what is known for eukaryotic ferritins, we found that bacterioferritin from Synechocystis is not inducible by iron under the conditions that we have tested and that it has a constant concentration whatever the iron status of the cells, even at very low iron concentration. Bacterioferritin from Synechocystis P.C.C. 6803 is fully assembled in vivo and it is shown by labelling with 59Fe that it is able to load iron in vitro as well as in vivo. Bacterioferritin from Synechocystis is shown to have an iron-buffering function while the bulk of cellular iron is found associated with a pool of low-molecular-mass electronegative molecules. The role of Synechocystis bacterioferritin in iron metabolism is discussed. Images Fig. 2. Fig. 3. Fig. 4. Fig. 8. Fig. 9. PMID:1536655

  8. The complete amino-acid sequence of C-phycoerythrin from the cyanobacterium Fremyella diplosiphon.

    PubMed

    Sidler, W; Kumpf, B; Rüdiger, W; Zuber, H

    1986-07-01

    The amino-acid sequences of both subunits of C-phycoerythrin from the cyanobacterium Fremyella diplosiphon have been determined. The alpha-subunit contains 164 amino acid residues, two phycoerythrobilin (PEB) chromophores and has a molecular mass of 18,368 Da (protein: 17,192 Da + 2 PEB, one PEB accounting for 588 Da). The beta-subunit consists of 184 residues, three PEB chromophores and has a molecular mass of 20,931 Da (protein: 19,168 Da and 3 PEB: 1,764 Da). The five PEB chromophores (open chain tetrapyrroles) are covalently bound to six cysteine residues (one of them doubly bound to two cysteine residues). On the alpha-subunit, the first chromophore was found at position 84, homologous to the chromophore binding site of the other biliproteins APC, PC and PEC. The second chromophore, unique for the alpha-subunit of PE, is inserted together with a pentapeptide at position 143 a. On the beta-subunit, a doubly bound chromophore is attached to cysteine residues 50 and 61, similar to the rhodophytan phycoerythrins (B-PE and R-PE). The second and third chromophores were found at positions 84 and 155, homologous to the other biliproteins. A unique peptide insertion of 14 amino acid residues (without chromophore) was found at position 141 a-o in the beta-subunit and probably is located in the three-dimensional model near the additional chromophores of the C-PE alpha- and beta-subunits. Both additional chromophores of the C-PE alpha- and beta-subunit may be located at the periphery of the C-PE-trimer. The amino-acid sequence homology between C-PE alpha- and beta-subunit is 26% and to the alpha- and beta-subunits of C-PC from Mastigocladus laminosus 49% and 48%, respectively. PMID:3092842

  9. Characterization of the Response to Zinc Deficiency in the Cyanobacterium Anabaena sp. Strain PCC 7120

    PubMed Central

    Napolitano, Mauro; Rubio, Miguel Ángel; Santamaría-Gómez, Javier; Olmedo-Verd, Elvira; Robinson, Nigel J.

    2012-01-01

    Zur regulators control zinc homeostasis by repressing target genes under zinc-sufficient conditions in a wide variety of bacteria. This paper describes how part of a survey of duplicated genes led to the identification of the open reading frame all2473 as the gene encoding the Zur regulator of the cyanobacterium Anabaena sp. strain PCC 7120. All2473 binds to DNA in a zinc-dependent manner, and its DNA-binding sequence was characterized, which allowed us to determine the relative contribution of particular nucleotides to Zur binding. A zur mutant was found to be impaired in the regulation of zinc homeostasis, showing sensitivity to elevated concentrations of zinc but not other metals. In an effort to characterize the Zur regulon in Anabaena, 23 genes containing upstream putative Zur-binding sequences were identified and found to be regulated by Zur. These genes are organized in six single transcriptional units and six operons, some of them containing multiple Zur-regulated promoters. The identities of genes of the Zur regulon indicate that Anabaena adapts to conditions of zinc deficiency by replacing zinc metalloproteins with paralogues that fulfill the same function but presumably with a lower zinc demand, and with inducing putative metallochaperones and membrane transport systems likely being involved in the scavenging of extracellular zinc, including plasma membrane ABC transport systems and outer membrane TonB-dependent receptors. Among the Zur-regulated genes, the ones showing the highest induction level encode proteins of the outer membrane, suggesting a primary role for components of this cell compartment in the capture of zinc cations from the extracellular medium. PMID:22389488

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

    PubMed

    Giner-Lamia, Joaquin; López-Maury, Luis; Florencio, Francisco J

    2014-01-01

    Copper is an essential element involved in fundamental processes like respiration and photosynthesis. However, it becomes toxic at high concentration, which has forced organisms to control its cellular concentration. We have recently described a copper resistance system in the cyanobacterium Synechocystis sp. PCC 6803, which is mediated by the two-component system, CopRS, a RND metal transport system, CopBAC and a protein of unknown function, CopM. Here, we report the transcriptional responses to copper additions at non-toxic (0.3 µM) and toxic concentrations (3 µM) in the wild type and in the copper sensitive copR mutant strain. While 0.3 µM copper slightly stimulated metabolism and promoted the exchange between cytochrome c6 and plastocyanin as soluble electron carriers, the addition of 3 µM copper catalyzed the formation of ROS, led to a general stress response and induced expression of Fe-S cluster biogenesis genes. According to this, a double mutant strain copRsufR, which expresses constitutively the sufBCDS operon, tolerated higher copper concentration than the copR mutant strain, suggesting that Fe-S clusters are direct targets of copper toxicity in Synechocystis. In addition we have also demonstrated that InrS, a nickel binding transcriptional repressor that belong to the CsoR family of transcriptional factor, was involved in heavy metal homeostasis, including copper, in Synechocystis. Finally, global gene expression analysis of the copR mutant strain suggested that CopRS only controls the expression of copMRS and copBAC operons in response to copper. PMID:25268225

  11. Global Transcriptional Profiles of the Copper Responses in the Cyanobacterium Synechocystis sp. PCC 6803

    PubMed Central

    Giner-Lamia, Joaquin; López-Maury, Luis; Florencio, Francisco J.

    2014-01-01

    Copper is an essential element involved in fundamental processes like respiration and photosynthesis. However, it becomes toxic at high concentration, which has forced organisms to control its cellular concentration. We have recently described a copper resistance system in the cyanobacterium Synechocystis sp. PCC 6803, which is mediated by the two-component system, CopRS, a RND metal transport system, CopBAC and a protein of unknown function, CopM. Here, we report the transcriptional responses to copper additions at non-toxic (0.3 µM) and toxic concentrations (3 µM) in the wild type and in the copper sensitive copR mutant strain. While 0.3 µM copper slightly stimulated metabolism and promoted the exchange between cytochrome c6 and plastocyanin as soluble electron carriers, the addition of 3 µM copper catalyzed the formation of ROS, led to a general stress response and induced expression of Fe-S cluster biogenesis genes. According to this, a double mutant strain copRsufR, which expresses constitutively the sufBCDS operon, tolerated higher copper concentration than the copR mutant strain, suggesting that Fe-S clusters are direct targets of copper toxicity in Synechocystis. In addition we have also demonstrated that InrS, a nickel binding transcriptional repressor that belong to the CsoR family of transcriptional factor, was involved in heavy metal homeostasis, including copper, in Synechocystis. Finally, global gene expression analysis of the copR mutant strain suggested that CopRS only controls the expression of copMRS and copBAC operons in response to copper. PMID:25268225

  12. Intercellular Diffusion of a Fluorescent Sucrose Analog via the Septal Junctions in a Filamentous Cyanobacterium

    PubMed Central

    Nürnberg, Dennis J.; Mariscal, Vicente; Bornikoel, Jan; Nieves-Morión, Mercedes; Krauß, Norbert; Herrero, Antonia

    2015-01-01

    ABSTRACT Many filamentous cyanobacteria produce specialized nitrogen-fixing cells called heterocysts, which are located at semiregular intervals along the filament with about 10 to 20 photosynthetic vegetative cells in between. Nitrogen fixation in these complex multicellular bacteria depends on metabolite exchange between the two cell types, with the heterocysts supplying combined-nitrogen compounds but dependent on the vegetative cells for photosynthetically produced carbon compounds. Here, we used a fluorescent tracer to probe intercellular metabolite exchange in the filamentous heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120. We show that esculin, a fluorescent sucrose analog, is incorporated by a sucrose import system into the cytoplasm of Anabaena cells. The cytoplasmic esculin is rapidly and reversibly exchanged across vegetative-vegetative and vegetative-heterocyst cell junctions. Our measurements reveal the kinetics of esculin exchange and also show that intercellular metabolic communication is lost in a significant fraction of older heterocysts. SepJ, FraC, and FraD are proteins located at the intercellular septa and are suggested to form structures analogous to gap junctions. We show that a ?sepJ ?fraC ?fraD triple mutant shows an altered septum structure with thinner septa but a denser peptidoglycan layer. Intercellular diffusion of esculin and fluorescein derivatives is impaired in this mutant, which also shows a greatly reduced frequency of nanopores in the intercellular septal cross walls. These findings suggest that FraC, FraD, and SepJ are important for the formation of junctional structures that constitute the major pathway for feeding heterocysts with sucrose. PMID:25784700

  13. DL-7-azatryptophan and citrulline metabolism in the cyanobacterium Anabaena sp. strain 1F

    SciTech Connect

    Chen, C.H.; Van Baalen, C.; Tabita, F.R.

    1987-03-01

    An alternative route for the primary assimilation of ammonia proceeds via glutamine synthetase-carbamyl phosphate synthetase and its inherent glutaminase activity in Anabaena sp. strain 1F, a marine filamentous, heterocystous cyanobacterium. Evidence for the presence of this possible alternative route to glutamate was provided by the use of amino acid analogs as specific enzyme inhibitors, enzymological studies, and radioistopic labeling experiments. The amino acid pool patterns of continuous cultures of Anabaena sp. strain 1F were markedly influenced by the nitrogen source. A relatively high concentration of glutamate was maintained in the amino acid pools of all cultures irrespective of the nitrogen source, reflecting the central role of glutamate in nitrogen metabolism. The addition of 1.0 microM azaserine increased the intracellular pools of glutamate and glutamine. All attempts to detect any enzymatic activity for glutamate synthase by measuring the formation of L-(/sup 14/C)glutamate from 2-keto-(1-/sup 14/C)glutarate and glutamine failed. The addition of 10 microM DL-7-azatryptophan caused a transient accumulation of intracellular citrulline and alanine which was not affected by the presence of chloramphenicol. The in vitro activity of carbamyl phosphate synthetase and glutaminase increased severalfold in the presence of azatryptophan. Results from radioisotopic labeling experiments with (/sup 14/C)bicarbonate and L-(1-/sup 14/C)ornithine also indicated that citrulline was formed via carbamyl phosphate synthetase and ornithine transcarbamylase. In addition to its effects on nitrogen metabolism, azatryptophan also affected carbon metabolism by inhibiting photosynthetic carbon assimilation and photosynthetic oxygen evolution.

  14. Ultrafast dynamics of phytochrome from the cyanobacterium synechocystis, reconstituted with phycocyanobilin and phycoerythrobilin.

    PubMed Central

    Heyne, Karsten; Herbst, Johannes; Stehlik, Dietmar; Esteban, Berta; Lamparter, Tilman; Hughes, Jon; Diller, Rolf

    2002-01-01

    Femtosecond time-resolved transient absorption spectroscopy was employed to characterize for the first time the primary photoisomerization dynamics of a bacterial phytochrome system in the two thermally stable states of the photocycle. The 85-kDa phytochrome Cph1 from the cyanobacterium Synechocystis PCC 6803 expressed in Escherichia coli was reconstituted with phycocyanobilin (Cph1-PCB) and phycoerythrobilin (Cph1-PEB). The red-light-absorbing form Pr of Cph1-PCB shows an approximately 150 fs relaxation in the S(1) state after photoexcitation at 650 nm. The subsequent Z-E isomerization between rings C and D of the linear tetrapyrrole-chromophore is best described by a distribution of rate constants with the first moment at (16 ps)(-1). Excitation at 615 nm leads to a slightly broadened distribution. The reverse E-Z isomerization, starting from the far-red-absorbing form Pfr, is characterized by two shorter time constants of 0.54 and 3.2 ps. In the case of Cph1-PEB, double-bond isomerization does not take place, and the excited-state lifetime extends into the nanosecond regime. Besides a stimulated emission rise time between 40 and 150 fs, no fast relaxation processes are observed. This suggests that the chromophore-protein interaction along rings A, B, and C does not contribute much to the picosecond dynamics observed in Cph1-PCB but rather the region around ring D near the isomerizing C(15) [double bond] C(16) double bond. The primary reaction dynamics of Cph1-PCB at ambient temperature is found to exhibit very similar features as those described for plant type A phytochrome, i.e., a relatively slow Pr, and a fast Pfr, photoreaction. This suggests that the initial reactions were established already before evolution of plant phytochromes began. PMID:11806940

  15. Low temperature delays timing and enhances the cost of nitrogen fixation in the unicellular cyanobacterium Cyanothece

    PubMed Central

    Brauer, Verena S; Stomp, Maayke; Rosso, Camillo; van Beusekom, Sebastiaan AM; Emmerich, Barbara; Stal, Lucas J; Huisman, Jef

    2013-01-01

    Marine nitrogen-fixing cyanobacteria are largely confined to the tropical and subtropical ocean. It has been argued that their global biogeographical distribution reflects the physiologically feasible temperature range at which they can perform nitrogen fixation. In this study we refine this line of argumentation for the globally important group of unicellular diazotrophic cyanobacteria, and pose the following two hypotheses: (i) nitrogen fixation is limited by nitrogenase activity at low temperature and by oxygen diffusion at high temperature, which is manifested by a shift from strong to weak temperature dependence of nitrogenase activity, and (ii) high respiration rates are required to maintain very low levels of oxygen for nitrogenase, which results in enhanced respiratory cost per molecule of fixed nitrogen at low temperature. We tested these hypotheses in laboratory experiments with the unicellular cyanobacterium Cyanothece sp. BG043511. In line with the first hypothesis, the specific growth rate increased strongly with temperature from 18 to 30?°C, but leveled off at higher temperature under nitrogen-fixing conditions. As predicted by the second hypothesis, the respiratory cost of nitrogen fixation and also the cellular C:N ratio rose sharply at temperatures below 21?°C. In addition, we found that low temperature caused a strong delay in the onset of the nocturnal nitrogenase activity, which shortened the remaining nighttime available for nitrogen fixation. Together, these results point at a lower temperature limit for unicellular nitrogen-fixing cyanobacteria, which offers an explanation for their (sub)tropical distribution and suggests expansion of their biogeographical range by global warming. PMID:23823493

  16. Using oxidized liquid and solid human waste as nutrients for Chlorella vulgaris and cyanobacterium Oscillatoria deflexa

    NASA Astrophysics Data System (ADS)

    Trifonov, Sergey V.; Kalacheva, Galina; Tirranen, Lyalya; Gribovskaya, Iliada

    At stationary terrestrial and space stations with closed and partially closed substance exchange not only plants, but also algae can regenerate atmosphere. Their biomass can be used for feeding Daphnia and Moina species, which, in their turn, serve as food for fish. In addition, it is possible to use algae for production of biological fuel. We suggested two methods of human waste mineralization: dry (evaporation with subsequent incineration in a muffle furnace) and wet (oxidation in a reactor using hydrogen peroxide). The research task was to prepare nutrient media for green alga Chlorella vulgaris and cyanobacterium Oscillatoria deflexa using liquid human waste mineralized by dry method, and to prepare media for chlorella on the basis of 1) liquid and 2) liquid and solid human waste mineralized by wet method. The algae were grown in batch culture in a climate chamber with the following parameters: illumination 7 klx, temperature 27-30 (°) C, culture density 1-2 g/l of dry weight. The control for chlorella was Tamiya medium, pH-5, and for oscillstoria — Zarrouk medium, pH-10. Maximum permissible concentrations of NaCl, Cl, urea (NH _{2}) _{2}CO, and native urine were established for algae. Missing ingredients (such as salts and acids) for experimental nutrient media were determined: their addition made it possible to obtain the biomass production not less than that in the control. The estimation was given of the mineral and biochemical composition of algae grown on experimental media. Microbiological test revealed absence of foreign microbial flora in experimental cultures.

  17. Regulation of Three Nitrogenase Gene Clusters in the Cyanobacterium Anabaena variabilis ATCC 29413

    PubMed Central

    Thiel, Teresa; Pratte, Brenda S.

    2014-01-01

    The filamentous cyanobacterium Anabaena variabilis ATCC 29413 fixes nitrogen under aerobic conditions in specialized cells called heterocysts that form in response to an environmental deficiency in combined nitrogen. Nitrogen fixation is mediated by the enzyme nitrogenase, which is very sensitive to oxygen. Heterocysts are microxic cells that allow nitrogenase to function in a filament comprised primarily of vegetative cells that produce oxygen by photosynthesis. A. variabilis is unique among well-characterized cyanobacteria in that it has three nitrogenase gene clusters that encode different nitrogenases, which function under different environmental conditions. The nif1 genes encode a Mo-nitrogenase that functions only in heterocysts, even in filaments grown anaerobically. The nif2 genes encode a different Mo-nitrogenase that functions in vegetative cells, but only in filaments grown under anoxic conditions. An alternative V-nitrogenase is encoded by vnf genes that are expressed only in heterocysts in an environment that is deficient in Mo. Thus, these three nitrogenases are expressed differentially in response to environmental conditions. The entire nif1 gene cluster, comprising at least 15 genes, is primarily under the control of the promoter for the first gene, nifB1. Transcriptional control of many of the downstream nif1 genes occurs by a combination of weak promoters within the coding regions of some downstream genes and by RNA processing, which is associated with increased transcript stability. The vnf genes show a similar pattern of transcriptional and post-transcriptional control of expression suggesting that the complex pattern of regulation of the nif1 cluster is conserved in other cyanobacterial nitrogenase gene clusters. PMID:25513762

  18. Lack of Phylogeographic Structure in the Freshwater Cyanobacterium Microcystis aeruginosa Suggests Global Dispersal

    PubMed Central

    van Gremberghe, Ineke; Vanormelingen, Pieter; Van der Gucht, Katleen; Debeer, Ann-Eline; Lacerot, Gissell; De Meester, Luc; Vyverman, Wim

    2011-01-01

    Background Free-living microorganisms have long been assumed to have ubiquitous distributions with little biogeographic signature because they typically exhibit high dispersal potential and large population sizes. However, molecular data provide contrasting results and it is far from clear to what extent dispersal limitation determines geographic structuring of microbial populations. We aimed to determine biogeographical patterns of the bloom-forming freshwater cyanobacterium Microcystis aeruginosa. Being widely distributed on a global scale but patchily on a regional scale, this prokaryote is an ideal model organism to study microbial dispersal and biogeography. Methodology/Principal Findings The phylogeography of M. aeruginosa was studied based on a dataset of 311 rDNA internal transcribed spacer (ITS) sequences sampled from six continents. Richness of ITS sequences was high (239 ITS types were detected). Genetic divergence among ITS types averaged 4% (maximum pairwise divergence was 13%). Preliminary analyses revealed nearly completely unresolved phylogenetic relationships and a lack of genetic structure among all sequences due to extensive homoplasy at multiple hypervariable sites. After correcting for this, still no clear phylogeographic structure was detected, and no pattern of isolation by distance was found on a global scale. Concomitantly, genetic differentiation among continents was marginal, whereas variation within continents was high and was mostly shared with all other continents. Similarly, no genetic structure across climate zones was detected. Conclusions/Significance The high overall diversity and wide global distribution of common ITS types in combination with the lack of phylogeographic structure suggest that intercontinental dispersal of M. aeruginosa ITS types is not rare, and that this species might have a truly cosmopolitan distribution. PMID:21573169

  19. Diurnal rhythm of a unicellular diazotrophic cyanobacterium under mixotrophic conditions and elevated carbon dioxide.

    PubMed

    Gaudana, Sandeep B; Alagesan, Swathi; Chetty, Madhu; Wangikar, Pramod P

    2013-11-01

    Mixotrophic cultivation of cyanobacteria in wastewaters with flue gas sparging has the potential to simultaneously sequester carbon content from gaseous and aqueous streams and convert to biomass and biofuels. Therefore, it was of interest to study the effect of mixotrophy and elevated CO2 on metabolism, morphology and rhythm of gene expression under diurnal cycles. We chose a diazotrophic unicellular cyanobacterium Cyanothece sp. ATCC 51142 as a model, which is a known hydrogen producer with robust circadian rhythm. Cyanothece 51142 grows faster with nitrate and/or an additional carbon source in the growth medium and at 3 % CO2. Intracellular glycogen contents undergo diurnal oscillations with greater accumulation under mixotrophy. While glycogen is exhausted by midnight under autotrophic conditions, significant amounts remain unutilized accompanied by a prolonged upregulation of nifH gene under mixotrophy. This possibly supports nitrogen fixation for longer periods thereby leading to better growth. To gain insights into the influence of mixotrophy and elevated CO2 on circadian rhythm, transcription of core clock genes kaiA, kaiB1 and kaiC1, the input pathway, cikA, output pathway, rpaA and representatives of key metabolic pathways was analyzed. Clock genes' transcripts were lower under mixotrophy suggesting a dampening effect exerted by an external carbon source such as glycerol. Nevertheless, the genes of the clock and important metabolic pathways show diurnal oscillations in expression under mixotrophic and autotrophic growth at ambient and elevated CO2, respectively. Taken together, the results indicate segregation of light and dark associated reactions even under mixotrophy and provide important insights for further applications. PMID:23881383

  20. Isolation and in silico analysis of Fe-superoxide dismutase in the cyanobacterium Nostoc commune.

    PubMed

    Kesheri, Minu; Kanchan, Swarna; Richa; Sinha, Rajeshwar P

    2014-12-15

    Cyanobacteria are known to endure various stress conditions due to the inbuilt potential for oxidative stress alleviation owing to the presence of an array of antioxidants. The present study shows that Antarctic cyanobacterium Nostoc commune possesses two antioxidative enzymes viz., superoxide dismutase (SOD) and catalase that jointly cope with environmental stresses prevailing at its natural habitat. Native-PAGE analysis illustrates the presence of a single prominent isoform recognized as Fe-SOD and three distinct isoforms of catalase. The protein sequence of Fe-SOD in N. commune retrieved from NCBI protein sequence database was used for in silico analysis. 3D structure of N. commune was predicted by comparative modeling using MODELLER 9v11. Further, this model was validated for its quality by Ramachandran plot, ERRAT, Verify 3D and ProSA-web which revealed good structure quality of the model. Multiple sequence alignment showed high conservation in N and C-terminal domain regions along with all metal binding positions in Fe-SOD which were also found to be highly conserved in all 28 cyanobacterial species under study, including N. commune. In silico prediction of isoelectric point and molecular weight of Fe-SOD was found to be 5.48 and 22,342.98Da respectively. The phylogenetic tree revealed that among 28 cyanobacterial species, Fe-SOD in N. commune was the closest evolutionary homolog of Fe-SOD in Nostoc punctiforme as evident by strong bootstrap value. Thus, N. commune may serve as a good biological model for studies related to survival of life under extreme conditions prevailing at the Antarctic region. Moreover cyanobacteria may be exploited for biochemical and biotechnological applications of enzymatic antioxidants. PMID:25303871

  1. The genome of Cyanothece 51142, a unicellular diazotrophic cyanobacterium important in the marine nitrogen cycle

    SciTech Connect

    Welsh, Eric A.; Liberton, Michelle L.; Stockel, Jana; Loh, Thomas; Elvitigala, Thanura R.; Wang, Chunyan; Wollam, Aye; Fulton, Robert S.; Clifton, Sandra W.; Jacobs, Jon M.; Aurora, Rajeev; Ghosh, Bijoy K.; Sherman, Louis A.; Smith, Richard D.; Wilson, Richard K.; Pakrasi, Himadri B.

    2008-09-30

    Cyanobacteria are oxygenic photosynthetic bacteria that have significant roles in global biological carbon sequestration and oxygen production. They occupy a diverse range of habitats, from open ocean, to hot springs, deserts, and arctic waters. Cyanobacteria are known as the progenitors of the chloroplasts of plants and algae, and are the simplest known organisms to exhibit circadian behavior4. Cyanothece sp. ATCC 51142 is a unicellular marine cyanobacterium capable of N2-fixation, a process that is biochemically incompatible with oxygenic photosynthesis. To resolve this problem, Cyanothece performs photosynthesis during the day and nitrogen fixation at night, thus temporally separating these processes in the same cell. The genome of Cyanothece 51142 was completely sequenced and found to contain a unique arrangement of one large circular chromosome, four small plasmids, and one linear chromosome, the first report of such a linear element in a photosynthetic bacterium. Annotation of the Cyanothece genome was aided by the use of highthroughput proteomics data, enabling the reclassification of 25% of the proteins with no informative sequence homology. Phylogenetic analysis suggests that nitrogen fixation is an ancient process that arose early in evolution and has subsequently been lost in many cyanobacterial strains. In cyanobacterial cells, the circadian clock influences numerous processes, including carbohydrate synthesis, nitrogen fixation, photosynthesis, respiration, and the cell division cycle. During a diurnal period, Cyanothece cells actively accumulate and degrade different storage inclusion bodies for the products of photosynthesis and N2-fixation. This ability to utilize metabolic compartmentalization and energy storage makes Cyanothece an ideal system for bioenergy research, as well as studies of how a unicellular organism balances multiple, often incompatible, processes in the same cell.

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

    PubMed Central

    Spät, Philipp; Ma?ek, Boris; Forchhammer, Karl

    2015-01-01

    Cyanobacteria have shaped the earth's biosphere as the first oxygenic photoautotrophs and still play an important role in many ecosystems. The ability to adapt to changing environmental conditions is an essential characteristic in order to ensure survival. To this end, numerous studies have shown that bacteria use protein post-translational modifications such as Ser/Thr/Tyr phosphorylation in cell signaling, adaptation, and regulation. Nevertheless, our knowledge of cyanobacterial phosphoproteomes and their dynamic response to environmental stimuli is relatively limited. In this study, we applied gel-free methods and high accuracy mass spectrometry toward the detection of Ser/Thr/Tyr phosphorylation events in the model cyanobacterium Synechocystis sp. PCC 6803. We could identify over 300 phosphorylation events in cultures grown on nitrate as exclusive nitrogen source. Chemical dimethylation labeling was applied to investigate proteome and phosphoproteome dynamics during nitrogen starvation. Our dataset describes the most comprehensive (phospho)proteome of Synechocystis to date, identifying 2382 proteins and 183 phosphorylation events and quantifying 2111 proteins and 148 phosphorylation events during nitrogen starvation. Global protein phosphorylation levels were increased in response to nitrogen depletion after 24 h. Among the proteins with increased phosphorylation, the PII signaling protein showed the highest fold-change, serving as positive control. Other proteins with increased phosphorylation levels comprised functions in photosynthesis and in carbon and nitrogen metabolism. This study reveals dynamics of Synechocystis phosphoproteome in response to environmental stimuli and suggests an important role of protein Ser/Thr/Tyr phosphorylation in fundamental mechanisms of homeostatic control in cyanobacteria. PMID:25873915

  3. Dependence of the Cyanobacterium Prochlorococcus on Hydrogen Peroxide Scavenging Microbes for Growth at the Ocean's Surface

    PubMed Central

    Morris, J. Jeffrey; Johnson, Zackary I.; Szul, Martin J.; Keller, Martin; Zinser, Erik R.

    2011-01-01

    The phytoplankton community in the oligotrophic open ocean is numerically dominated by the cyanobacterium Prochlorococcus, accounting for approximately half of all photosynthesis. In the illuminated euphotic zone where Prochlorococcus grows, reactive oxygen species are continuously generated via photochemical reactions with dissolved organic matter. However, Prochlorococcus genomes lack catalase and additional protective mechanisms common in other aerobes, and this genus is highly susceptible to oxidative damage from hydrogen peroxide (HOOH). In this study we showed that the extant microbial community plays a vital, previously unrecognized role in cross-protecting Prochlorococcus from oxidative damage in the surface mixed layer of the oligotrophic ocean. Microbes are the primary HOOH sink in marine systems, and in the absence of the microbial community, surface waters in the Atlantic and Pacific Ocean accumulated HOOH to concentrations that were lethal for Prochlorococcus cultures. In laboratory experiments with the marine heterotroph Alteromonas sp., serving as a proxy for the natural community of HOOH-degrading microbes, bacterial depletion of HOOH from the extracellular milieu prevented oxidative damage to the cell envelope and photosystems of co-cultured Prochlorococcus, and facilitated the growth of Prochlorococcus at ecologically-relevant cell concentrations. Curiously, the more recently evolved lineages of Prochlorococcus that exploit the surface mixed layer niche were also the most sensitive to HOOH. The genomic streamlining of these evolved lineages during adaptation to the high-light exposed upper euphotic zone thus appears to be coincident with an acquired dependency on the extant HOOH-consuming community. These results underscore the importance of (indirect) biotic interactions in establishing niche boundaries, and highlight the impacts that community-level responses to stress may have in the ecological and evolutionary outcomes for co-existing species. PMID:21304826

  4. Sustained H2 Production Driven by Photosynthetic Water Splitting in a Unicellular Cyanobacterium

    PubMed Central

    Melnicki, Matthew R.; Pinchuk, Grigoriy E.; Hill, Eric A.; Kucek, Leo A.; Fredrickson, Jim K.; Konopka, Allan; Beliaev, Alexander S.

    2012-01-01

    ABSTRACT The relationship between dinitrogenase-driven H2 production and oxygenic photosynthesis was investigated in a unicellular cyanobacterium, Cyanothece sp. ATCC 51142, using a novel custom-built photobioreactor equipped with advanced process control. Continuously illuminated nitrogen-deprived cells evolved H2 at rates up to 400 µmol ? mg Chl?1 ? h?1 in parallel with uninterrupted photosynthetic O2 production. Notably, sustained coproduction of H2 and O2 occurred over 100 h in the presence of CO2, with both gases displaying inverse oscillations which eventually dampened toward stable rates of 125 and 90 µmol ? mg Chl?1 ? h?1, respectively. Oscillations were not observed when CO2 was omitted, and instead H2 and O2 evolution rates were positively correlated. The sustainability of the process was further supported by stable chlorophyll content, maintenance of baseline protein and carbohydrate levels, and an enhanced capacity for linear electron transport as measured by chlorophyll fluorescence throughout the experiment. In situ light saturation analyses of H2 production displayed a strong dose dependence and lack of O2 inhibition. Inactivation of photosystem II had substantial long-term effects but did not affect short-term H2 production, indicating that the process is also supported by photosystem I activity and oxidation of endogenous glycogen. However, mass balance calculations suggest that carbohydrate consumption in the light may, at best, account for no more than 50% of the reductant required for the corresponding H2 production over that period. Collectively, our results demonstrate that uninterrupted H2 production in unicellular cyanobacteria can be fueled by water photolysis without the detrimental effects of O2 and have important implications for sustainable production of biofuels. PMID:22872781

  5. Competition and facilitation between the marine nitrogen-fixing cyanobacterium Cyanothece and its associated bacterial community

    PubMed Central

    Brauer, Verena S.; Stomp, Maayke; Bouvier, Thierry; Fouilland, Eric; Leboulanger, Christophe; Confurius-Guns, Veronique; Weissing, Franz J.; Stal, LucasJ.; Huisman, Jef

    2014-01-01

    N2-fixing cyanobacteria represent a major source of new nitrogen and carbon for marine microbial communities, but little is known about their ecological interactions with associated microbiota. In this study we investigated the interactions between the unicellular N2-fixing cyanobacterium Cyanothece sp. Miami BG043511 and its associated free-living chemotrophic bacteria at different concentrations of nitrate and dissolved organic carbon and different temperatures. High temperature strongly stimulated the growth of Cyanothece, but had less effect on the growth and community composition of the chemotrophic bacteria. Conversely, nitrate and carbon addition did not significantly increase the abundance of Cyanothece, but strongly affected the abundance and species composition of the associated chemotrophic bacteria. In nitrate-free medium the associated bacterial community was co-dominated by the putative diazotroph Mesorhizobium and the putative aerobic anoxygenic phototroph Erythrobacter and after addition of organic carbon also by the Flavobacterium Muricauda. Addition of nitrate shifted the composition toward co-dominance by Erythrobacter and the Gammaproteobacterium Marinobacter. Our results indicate that Cyanothece modified the species composition of its associated bacteria through a combination of competition and facilitation. Furthermore, within the bacterial community, niche differentiation appeared to play an important role, contributing to the coexistence of a variety of different functional groups. An important implication of these findings is that changes in nitrogen and carbon availability due to, e.g., eutrophication and climate change are likely to have a major impact on the species composition of the bacterial community associated with N2-fixing cyanobacteria. PMID:25642224

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

    PubMed

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

    2015-12-15

    Arsenic, a ubiquitous toxic substance, exists mainly as inorganic forms in the environment. It is perceived that organoarsenicals can be demethylated and degraded into inorganic arsenic by microorganisms. Few studies have focused on the mechanism of arsenic demethylation in bacteria. Here, we investigated arsenic demethylation in a typical freshwater cyanobacterium Nostoc sp. PCC 7120. This bacterium was able to demethylate monomethylarsenite [MAs(III)] rapidly to arsenite [As(III)] and also had the ability to demethylate monomethylarsenate [MAs(V)] to As(III). The NsarsI encoding a C·As lyase responsible for MAs(III) demethylation was cloned from Nostoc sp. PCC 7120 and heterologously expressed in an As-hypersensitive strain Escherichia coli AW3110 (?arsRBC). Expression of NsarsI was shown to confer MAs(III) resistance through arsenic demethylation. The purified NsArsI was further identified and functionally characterized in vitro. NsArsI existed mainly as the trimeric state, and the kinetic data were well-fit to the Hill equation with K0.5 = 7.55 ± 0.33 ?M for MAs(III), Vmax = 0.79 ± 0.02 ?M min(-1), and h = 2.7. Both of the NsArsI truncated derivatives lacking the C-terminal 10 residues (ArsI10) or 23 residues (ArsI23) had a reduced ability of MAs(III) demethylation. These results provide new insights for understanding the important role of cyanobacteria in arsenic biogeochemical cycling in the environment. PMID:26544154

  7. A Nostoc punctiforme Sugar Transporter Necessary to Establish a Cyanobacterium-Plant Symbiosis1[C][W

    PubMed Central

    Ekman, Martin; Picossi, Silvia; Campbell, Elsie L.; Meeks, John C.; Flores, Enrique

    2013-01-01

    In cyanobacteria-plant symbioses, the symbiotic nitrogen-fixing cyanobacterium has low photosynthetic activity and is supplemented by sugars provided by the plant partner. Which sugars and cyanobacterial sugar uptake mechanism(s) are involved in the symbiosis, however, is unknown. Mutants of the symbiotically competent, facultatively heterotrophic cyanobacterium Nostoc punctiforme were constructed bearing a neomycin resistance gene cassette replacing genes in a putative sugar transport gene cluster. Results of transport activity assays using 14C-labeled fructose and glucose and tests of heterotrophic growth with these sugars enabled the identification of an ATP-binding cassette-type transporter for fructose (Frt), a major facilitator permease for glucose (GlcP), and a porin needed for the optimal uptake of both fructose and glucose. Analysis of green fluorescent protein fluorescence in strains of N. punctiforme bearing frt::gfp fusions showed high expression in vegetative cells and akinetes, variable expression in hormogonia, and no expression in heterocysts. The symbiotic efficiency of N. punctiforme sugar transport mutants was investigated by testing their ability to infect a nonvascular plant partner, the hornwort Anthoceros punctatus. Strains that were specifically unable to transport glucose did not infect the plant. These results imply a role for GlcP in establishing symbiosis under the conditions used in this work. PMID:23463784

  8. Does 2-phosphoglycolate serve as an internal signal molecule of inorganic carbon deprivation in the cyanobacterium Synechocystis sp. PCC 6803?

    PubMed

    Haimovich-Dayan, Maya; Lieman-Hurwitz, Judy; Orf, Isabel; Hagemann, Martin; Kaplan, Aaron

    2015-05-01

    Cyanobacteria possess CO2 -concentrating mechanisms (CCM) that functionally compensate for the poor affinity of their ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) to CO2 . It was proposed that 2-phosphoglycolate (2PG), produced by the oxygenase activity of Rubisco and metabolized via photorespiratory routes, serves as a signal molecule for the induction of CCM-related genes under limiting CO2 level (LC) conditions. However, in vivo evidence is still missing. Since 2PG does not permeate the cells, we manipulated its internal concentration. Four putative phosphoglycolate phosphatases (PGPases) encoding genes (slr0458, sll1349, slr0586 and slr1762) were identified in the cyanobacterium Synechocystis?PCC 6803. Expression of slr0458 in Escherichia coli led to a significant rise in PGPase activity. A Synechocystis mutant overexpressing (OE) slr0458 was constructed. Compared with the wild type (WT), the mutant grew slower under limiting CO2 concentration and the intracellular 2PG level was considerably smaller than in the wild type, the transcript abundance of LC-induced genes including cmpA, sbtA and ndhF3 was reduced, and the OE cells acclimated slower to LC - indicated by the delayed rise in the apparent photosynthetic affinity to inorganic carbon. Data obtained here implicated 2PG in the acclimation of this cyanobacterium to LC but also indicated that other, yet to be identified components, are involved. PMID:25297829

  9. Pathway-Level Acceleration of Glycogen Catabolism by a Response Regulator in the Cyanobacterium Synechocystis Species PCC 68031[W

    PubMed Central

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

    2014-01-01

    Response regulators of two-component systems play pivotal roles in the transcriptional regulation of responses to environmental signals in bacteria. Rre37, an OmpR-type response regulator, is induced by nitrogen depletion in the unicellular cyanobacterium Synechocystis species PCC 6803. Microarray and quantitative real-time polymerase chain reaction analyses revealed that genes related to sugar catabolism and nitrogen metabolism were up-regulated by rre37 overexpression. Protein levels of GlgP(slr1367), one of the two glycogen phosphorylases, in the rre37-overexpressing strain were higher than those of the parental wild-type strain under both nitrogen-replete and nitrogen-depleted conditions. Glycogen amounts decreased to less than one-tenth by rre37 overexpression under nitrogen-replete conditions. Metabolome analysis revealed that metabolites of the sugar catabolic pathway and amino acids were altered in the rre37-overexpressing strain after nitrogen depletion. These results demonstrate that Rre37 is a pathway-level regulator that activates the metabolic flow from glycogen to polyhydroxybutyrate and the hybrid tricarboxylic acid and ornithine cycle, unraveling the mechanism of the transcriptional regulation of primary metabolism in this unicellular cyanobacterium. PMID:24521880

  10. Arabinogalactan proteins occur in the free-living cyanobacterium genus Nostoc and in plant-Nostoc symbioses.

    PubMed

    Jackson, Owen; Taylor, Oliver; Adams, David G; Knox, J Paul

    2012-10-01

    Arabinogalactan proteins (AGP) are a diverse family of proteoglycans associated with the cell surfaces of plants. AGP have been implicated in a wide variety of plant cell processes, including signaling in symbioses. This study investigates the existence of putative AGP in free-living cyanobacterial cultures of the nitrogen-fixing, filamentous cyanobacteria Nostoc punctiforme and Nostoc sp. strain LBG1 and at the symbiotic interface in the symbioses between Nostoc spp. and two host plants, the angiosperm Gunnera manicata (in which the cyanobacterium is intracellular) and the liverwort Blasia pusilla (in which the cyanobacterium is extracellular). Enzyme-linked immunosorbent assay, immunoblotting, and immunofluorescence analyses demonstrated that three AGP glycan epitopes (recognized by monoclonal antibodies LM14, MAC207, and LM2) are present in free-living Nostoc cyanobacterial species. The same three AGP glycan epitopes are present at the Gunnera-Nostoc symbiotic interface and the LM2 epitope is detected during the establishment of the Blasia-Nostoc symbiosis. Bioinformatic analysis of the N. punctiforme genome identified five putative AGP core proteins that are representative of AGP classes found in plants. These results suggest a possible involvement of AGP in cyanobacterial-plant symbioses and are also suggestive of a cyanobacterial origin of AGP. PMID:22670754

  11. Ethoxyzolamide Inhibition of CO(2)-Dependent Photosynthesis in the Cyanobacterium Synechococcus PCC7942.

    PubMed

    Price, G D; Badger, M R

    1989-01-01

    Cells of the cyanobacterium, Synechococcus PCC7942, grown under high inorganic carbon (C(i)) conditions (1% CO(2); pH 8) were found to be photosynthetically dependent on exogenous CO(2). This was judged by the fact that they had a similar photosynthetic affinity for CO(2) (K(0.5)[CO(2)] of 3.4-5.4 micromolar) over the pH range 7 to 9 and that the low photosynthetic affinity for C(i) measured in dense cell suspensions was improved by the addition of exogenous carbonic anhydrase (CA). The CA inhibitor, ethoxyzolamide (EZ), was shown to reduce photosynthetic affinity for CO(2) in high C(i) cells. The addition of 200 micromolar EZ to high C(i) cells increased K(0.5)(CO(2)) from 4.6 micromolar to more than 155 micromolar at pH 8.0, whereas low C(i) cells (grown at 30 microliters CO(2) per liter of air) were less sensitive to EZ. EZ inhibition in high and low C(i) cells was largely relieved by increasing exogenous C(i) up to 100 millimolar. Lipid soluble CA inhibitors such as EZ and chlorazolamide were shown to be the most effective inhibitors of CO(2) usage, whereas water soluble CA inhibitors such as methazolamide and acetazolamide had little or no effect. EZ was found to cause a small drop in photosystem II activity, but this level of inhibition was not sufficient to explain the large effect that EZ had on CO(2) usage. High C(i) cells of Anabaena variabilis M3 and Synechocystis PCC6803 were also found to be sensitive to 200 micromolar EZ. We discuss the possibility that the inhibitory effect of EZ on CO(2) usage in high C(i) cells of Synechococcus PCC7942 may be due to inhibition of a ;CA-like' function associated with the CO(2) utilizing C(i) pump or due to inhibition of an internal CA activity, thus affecting CO(2) supply to ribulose bisphosphate carboxylase-oxygenase. PMID:16666544

  12. Metabolic rhythms of the cyanobacterium Cyanothece sp. ATCC 51142 correlate with modeled dynamics of circadian clock.

    PubMed

    Cervený, Jan; Nedbal, Ladislav

    2009-08-01

    These experiments aim to reveal the dynamic features that occur during the metabolism of the unicellular, nitrogen fixing cyanobacterium Cyanothece sp. when exposed to diverse circadian forcing patterns (LD 16:8, LD 12:12, LD 8:16, LD 6:6). The chlorophyll concentration grew rapidly from subjective morning when first illuminated to around noon, then remained stable from later in the afternoon and throughout the night. The optical density measured at 735 nm was stable during the morning chlorophyll accumulation, then increased in the early afternoon toward a peak, followed at dusk by a rapid decline toward the late night steady state. The authors propose that these dynamics largely reflect accumulation and subsequent consumption of glycogen granules. This hypothesis is consistent with the sharp peak of respiration that coincides with the putative hydrocarbon catabolism. In the long-day regimen (LD 16:8), these events may mark the transition from the aerobic photosynthetic metabolism to microaerobic nitrogen metabolism that occurs at dusk, and thus cannot be triggered by the darkness that comes later. Rather, control is likely to originate in the circadian clock signaling an approaching night. To explore the dynamics of the link between respiration and circadian oscillations, the authors extrapolated an earlier model of the KaiABC oscillator from Synechococcus elongatus to Cyanothece sp. The measured peak of respiratory activity at dusk correlated strongly in its timing and time width with the modeled peak in accumulation of the KaiB(4) complex, which marks the late afternoon phase of the circadian clock. The authors propose a hypothesis that high levels of KaiB(4) (or of its Cyanothece sp. analog) trigger the glycogen catabolism that is reflected in the experiments in the respiratory peak. The degree of the correlation between the modeled KaiB(4) dynamics and the dynamics of experimentally measured peaks of respiratory activity was further tested during the half-circadian regimen (LD 6:6). The model predicted an irregular pattern of the KaiABC oscillator, quite unlike mechanical or electrical clock pacemakers that are strongly damped when driven at double their endogenous frequency. This highly unusual dynamic pattern was confirmed experimentally, supporting strongly the validity of the circadian model and of the proposed direct link to respiration. PMID:19625731

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

    PubMed Central

    Kothari, Ankita; Vaughn, Michael; Garcia-Pichel, Ferran

    2013-01-01

    The filamentous, non-heterocystous cyanobacterium Lyngbya aestuarii is an important contributor to marine intertidal microbial mats system worldwide. The recent isolate L. aestuarii BL J, is an unusually powerful hydrogen producer. Here we report a morphological, ultrastructural, and genomic characterization of this strain to set the basis for future systems studies and applications of this organism. The filaments contain circa 17 ?m wide trichomes, composed of stacked disk-like short cells (2 ?m long), encased in a prominent, laminated exopolysaccharide sheath. Cellular division occurs by transversal centripetal growth of cross-walls, where several rounds of division proceed simultaneously. Filament division occurs by cell self-immolation of one or groups of cells (necridial cells) at the breakage point. Short, sheath-less, motile filaments (hormogonia) are also formed. Morphologically and phylogenetically L. aestuarii belongs to a clade of important cyanobacteria that include members of the marine Trichodesmiun and Hydrocoleum genera, as well as terrestrial Microcoleus vaginatus strains, and alkalyphilic strains of Arthrospira. A draft genome of strain BL J was compared to those of other cyanobacteria in order to ascertain some of its ecological constraints and biotechnological potential. The genome had an average GC content of 41.1%. Of the 6.87 Mb sequenced, 6.44 Mb was present as large contigs (>10,000 bp). It contained 6515 putative protein-encoding genes, of which, 43% encode proteins of known functional role, 26% corresponded to proteins with domain or family assignments, 19.6% encode conserved hypothetical proteins, and 11.3% encode apparently unique hypothetical proteins. The strain's genome reveals its adaptations to a life of exposure to intense solar radiation and desiccation. It likely employs the storage compounds, glycogen, and cyanophycin but no polyhydroxyalkanoates, and can produce the osmolytes, trehalose, and glycine betaine. According to its genome, BL J strain also has the potential to produce a plethora of products of biotechnological interest such as Curacin A, Barbamide, Hemolysin-type calcium-binding toxin, the suncreens scytonemin, and mycosporines, as well as heptadecane and pentadecane alkanes. With respect to hydrogen production, initial comparisons of the genetic architecture and sequence of relevant genes and loci, and a comparative model of protein structure of the NiFe bidirectional hydrogenase, did not reveal conspicuous differences that could explain its unusual hydrogen producing capacity. PMID:24376438

  14. Photoautotrophic production of D-lactic acid in an engineered cyanobacterium

    PubMed Central

    2013-01-01

    Background The world faces the challenge to develop sustainable technologies to replace thousands of products that have been generated from fossil fuels. Microbial cell factories serve as promising alternatives for the production of diverse commodity chemicals and biofuels from renewable resources. For example, polylactic acid (PLA) with its biodegradable properties is a sustainable, environmentally friendly alternative to polyethylene. At present, PLA microbial production is mainly dependent on food crops such as corn and sugarcane. Moreover, optically pure isomers of lactic acid are required for the production of PLA, where D-lactic acid controls the thermochemical and physical properties of PLA. Henceforth, production of D-lactic acid through a more sustainable source (CO2) is desirable. Results We have performed metabolic engineering on Synechocystis sp. PCC 6803 for the phototrophic synthesis of optically pure D-lactic acid from CO2. Synthesis of optically pure D-lactic acid was achieved by utilizing a recently discovered enzyme (i.e., a mutated glycerol dehydrogenase, GlyDH*). Significant improvements in D-lactic acid synthesis were achieved through codon optimization and by balancing the cofactor (NADH) availability through the heterologous expression of a soluble transhydrogenase. We have also discovered that addition of acetate to the cultures improved lactic acid production. More interestingly, 13C-pathway analysis revealed that acetate was not used for the synthesis of lactic acid, but was mainly used for synthesis of certain biomass building blocks (such as leucine and glutamate). Finally, the optimal strain was able to accumulate 1.14 g/L (photoautotrophic condition) and 2.17 g/L (phototrophic condition with acetate) of D-lactate in 24 days. Conclusions We have demonstrated the photoautotrophic production of D-lactic acid by engineering a cyanobacterium Synechocystis 6803. The engineered strain shows an excellent D-lactic acid productivity from CO2. In the late growth phase, the lactate production rate by the engineered strain reached a maximum of ~0.19 g D-lactate/L/day (in the presence of acetate). This study serves as a good complement to the recent metabolic engineering work done on Synechocystis 6803 for L-lactate production. Thereby, our study may facilitate future developments in the use of cyanobacterial cell factories for the commercial production of high quality PLA. PMID:24274114

  15. Growth inhibition of bloom forming cyanobacterium Microcystis aeruginosa by green route fabricated copper oxide nanoparticles.

    PubMed

    Sankar, Renu; Prasath, Barathan Balaji; Nandakumar, Ravichandran; Santhanam, Perumal; Shivashangari, Kanchi Subramanian; Ravikumar, Vilwanathan

    2014-12-01

    The cyanobacterium Microcystis aeruginosa can potentially proliferate in a wide range of freshwater bionetworks and create extensive secondary metabolites which are harmful to human and animal health. The M. aeruginosa release toxic microcystins that can create a wide range of health-related issues to aquatic animals and humans. It is essential to eliminate them from the ecosystem with convenient method. It has been reported that engineered metal nanoparticles are potentially toxic to pathogenic organisms. In the present study, we examined the growth inhibition effect of green synthesized copper oxide nanoparticles against M. aeruginosa. The green synthesized copper oxide nanoparticles exhibit an excitation of surface plasmon resonance (SPR) at 270 nm confirmed using UV-visible spectrophotometer. The dynamic light scattering (DLS) analysis revealed that synthesized nanoparticles are colloidal in nature and having a particle size of 551 nm with high stability at -26.6 mV. The scanning electron microscopy (SEM) analysis shows that copper oxide nanoparticles are spherical, rod and irregular in shape, and consistently distributed throughout the solution. The elemental copper and oxide peak were confirmed using energy dispersive x-ray analysis (EDAX). Fourier-transform infrared (FT-IR) spectroscopy indicates the presence of functional groups which is mandatory for the reduction of copper ions. Besides, green synthesized copper oxide nanoparticles shows growth inhibition against M. aeruginosa. The inhibition efficiency was 31.8 % at lower concentration and 89.7 % at higher concentration of copper oxide nanoparticles, respectively. The chlorophyll (a and b) and carotenoid content of M. aeruginosa declined in dose-dependent manner with respect to induction of copper oxide nanoparticles. Furthermore, we analyzed the mechanism behind the cytotoxicity of M. aeruginosa induced by copper oxide nanoparticles through evaluating membrane integrity, reactive oxygen species (ROS), and mitochondrial membrane potential (??m) level. The results expose that there is a loss in membrane integrity with ROS formation that leads to alteration in the ??m, which ends up with severe mitochondrial injury in copper oxide nanoparticles treated cells. Hence, green way synthesized copper oxide nanoparticles may be a useful selective biological agent for the control of M. aeruginosa. PMID:25074832

  16. Genetic variability associated with photosynthetic pigment concentration, and photochemical and nonphotochemical quenching, in strains of the cyanobacterium Microcystis aeruginosa.

    PubMed

    Bañares-España, Elena; López-Rodas, Victoria; Costas, Eduardo; Salgado, Concepción; Flores-Moya, Antonio

    2007-06-01

    Although populations of cyanobacteria are usually considered to be clonal, their capacity to survive environmental changes suggests intrapopulation genetic variation. We therefore estimated the genetic variability on the basis of two processes important for any photoautotroph - photochemical and nonphotochemical quenching - as well as photosynthetic pigment concentrations. For this purpose, two parameters related to photochemical and nonphotochemical quenching were measured using specific experimental and statistical procedures, in 25 strains of the cyanobacterium Microcystis aeruginosa, along with their contents of chlorophyll a, total carotenoids and phycocyanin. The experimental procedure allowed discrimination between genetic and nongenetic (or residual) variability among strains. The high genetic variability found in photosynthetic pigments and both photosynthetic parameters denotes large differences even among strains isolated from the same community. The high genetic diversity within a population could be important for the evolutionary success of cyanobacteria. PMID:17374127

  17. Influence of mixotrophic growth on rhythmic oscillations in expression of metabolic pathways in diazotrophic cyanobacterium Cyanothece sp. ATCC 51142.

    PubMed

    Krishnakumar, S; Gaudana, Sandeep B; Digmurti, Madhuri G; Viswanathan, Ganesh A; Chetty, Madhu; Wangikar, Pramod P

    2015-07-01

    This study investigates the influence of mixotrophy on physiology and metabolism by analysis of global gene expression in unicellular diazotrophic cyanobacterium Cyanothece sp. ATCC 51142 (henceforth Cyanothece 51142). It was found that Cyanothece 51142 continues to oscillate between photosynthesis and respiration in continuous light under mixotrophy with cycle time of ? 13 h. Mixotrophy is marked by an extended respiratory phase compared with photoautotrophy. It can be argued that glycerol provides supplementary energy for nitrogen fixation, which is derived primarily from the glycogen reserves during photoautotrophy. The genes of NDH complex, cytochrome c oxidase and ATP synthase are significantly overexpressed in mixotrophy during the day compared to autotrophy with synchronous expression of the bidirectional hydrogenase genes possibly to maintain redox balance. However, nitrogenase complex remains exclusive to nighttime metabolism concomitantly with uptake hydrogenase. This study throws light on interrelations between metabolic pathways with implications in design of hydrogen producer strains. PMID:25736893

  18. Mutations that affect structure and assembly of light-harvesting proteins in the cyanobacterium Synechocystis sp. strain 6701

    SciTech Connect

    Anderson, L.K.; Rayner, M.C.; Eiserling, F.A.

    1987-01-01

    The unicellular cyanobacterium Synechocystis sp. strain 6701 was mutagenized with UV irradiation and screened for pigment changes that indicated genetic lesions involving the light-harvesting proteins of the phycobilisome. A previous examination of the pigment mutant UV16 showed an assembly defect in the phycocyanin component of the phycobilisome. Mutagenesis of UV16 produced an additional double mutant, UV16-40, with decreased phycoerythrin content. Phycocyanin and phycoerythrin were isolated from UV16-40 and compared with normal biliproteins. The results suggested that the UV16 mutation affected the alpha subunit of phycocyanin, while the phycoerythrin beta subunit from UV16-40 had lost one of its three chromophores. Characterization of the unassembled phycobilisome components in these mutants suggests that these strains will be useful for probing in vivo the regulated expression and assembly of phycobilisomes.

  19. Establishment of a Pure Culture of the Hitherto Uncultured Unicellular Cyanobacterium Aphanothece sacrum, and Phylogenetic Position of the Organism

    PubMed Central

    Fujishiro, Tsuneo; Ogawa, Takahira; Matsuoka, Masayoshi; Nagahama, Kazuhiro; Takeshima, Yasunobu; Hagiwara, Hideaki

    2004-01-01

    Aphanothece sacrum, an edible freshwater unicellular cyanobacterium, was isolated by using novel synthetic media (designated AST and AST-5xNP). The media were designed on the basis of the ratio of inorganic elements contained in A. sacrum cells cultured in a natural pond. The isolated strain exhibits unicellular rod-shaped cells ?6 ?m in length that are scattered in an exopolysaccharide matrix, a feature similar to that of natural A. sacrum. DNA analysis of the isolated strain revealed that it carried two ferredoxin genes whose deduced amino acid sequences were almost identical to previously published sequences of ferredoxins from natural A. sacrum. Analysis of the 16S rRNA gene and ferredoxin genes revealed that A. sacrum occupies a phylogenetically unique position among the cyanobacteria. PMID:15184129

  20. The leaves of green plants as well as a cyanobacterium, a red alga, and fungi contain insulin-like antigens.

    PubMed

    Silva, L B; Santos, S S S; Azevedo, C R; Cruz, M A L; Venâncio, T M; Cavalcante, C P; Uchôa, A F; Astolfi Filho, S; Oliveira, A E A; Fernandes, K V S; Xavier-Filho, J

    2002-03-01

    We report the detection of insulin-like antigens in a large range of species utilizing a modified ELISA plate assay and Western blotting. We tested the leaves or aerial parts of species of Rhodophyta (red alga), Bryophyta (mosses), Psilophyta (whisk ferns), Lycopodophyta (club mosses), Sphenopsida (horsetails), gymnosperms, and angiosperms, including monocots and dicots. We also studied species of fungi and a cyanobacterium, Spirulina maxima. The wide distribution of insulin-like antigens, which in some cases present the same electrophoretic mobility as bovine insulin, together with results recently published by us on the amino acid sequence of an insulin isolated from the seed coat of jack bean (Canavalia ensiformis) and from the developing fruits of cowpea (Vigna unguiculata), suggests that pathways depending on this hormone have been conserved through evolution. PMID:11887207

  1. Draft genome of Myxosarcina sp. strain GI1, a baeocytous cyanobacterium associated with the marine sponge Terpios hoshinota

    PubMed Central

    2015-01-01

    To date, genome sequences (complete or in draft form) from only six baeocytous cyanobacteria in four genera have been reported: Xenococcus, Chroococcidiopsis, Pleurocapsa, and Stanieria. To expand our knowledge on the diversity of baeocytous cyanobacteria, this study sequenced the genome of GI1, which is a Myxosarcina-like baeocytous cyanobacterium. GI1 is of interest not only because of its phylogenetic niche, but also because it is a cyanobiont isolated from the marine cyanobacteriosponge Terpios hoshinota, which has been shown to cause the death of corals. The ~7 Mb draft GI1 genome contains 6,891 protein-coding genes and 62 RNA genes. A comparison of genomes among the sequenced baeocytous cyanobacterial strains revealed the existence or absence of numerous discrete genes involved in nitrogen metabolism. It will be interesting to determine whether these genes are important for cyanobacterial adaptations and interactions between cyanobionts and their marine sponge hosts. PMID:26203339

  2. Phosphorus addition reverses the positive effect of zebra mussels (Dreissena polymorpha) on the toxic cyanobacterium, Microcystis aeruginosa.

    PubMed

    Sarnelle, Orlando; White, Jeffrey D; Horst, Geoffrey P; Hamilton, Stephen K

    2012-07-01

    We tested the hypothesis that zebra mussels (Dreissena polymorpha) have positive effects on the toxin-producing cyanobacterium, Microcystis aeruginosa, at low phosphorus (P) concentrations, but negative effects on M. aeruginosa at high P, with a large-scale enclosure experiment in an oligotrophic lake. After three weeks, mussels had a significantly positive effect on M. aeruginosa at ambient P (total phosphorus, TP ?10 ?g L?¹), and a significantly negative effect at high P (simulating a TP of ?40 ?g L?¹ in lakes). Positive and negative effects were strong and very similar in magnitude. Thus, we were able to ameliorate a negative effect of Dreissena invasion on water quality (i.e., promotion of Microcystis) by adding P to water from an oligotrophic lake. Our results are congruent with many field observations of Microcystis response to Dreissena invasion across ecosystems of varying P availability. PMID:22507249

  3. Protein synthesis and proteolysis in immobilized cells of the cyanobacterium Nostoc commune UTEX 584 exposed to matric water stress.

    PubMed Central

    Potts, M

    1985-01-01

    Cells of the cyanobacterium Nostoc commune UTEX 584 in exponential growth were subjected to acute water stress by immobilizing them on solid supports and drying them at a matric water potential (psi m) of -99.5 MPa. Cells which had been grown in the presence of Na235SO4 before immobilization and rapid drying continued to incorporate 35S into protein for 90 min. This incorporation was inhibited by chloramphenicol. No unique proteins appeared to be synthesized during this time. Upon further drying, the level of incorporation of 35S in protein began to decrease. In contrast, there was an apparent increase in the level of certain phycobiliprotein subunits in solubilized protein extracts of these cells. Extensive proteolysis was detected after prolonged desiccation (17 days) of the cells in the light, although they still remained intact. Phycobilisomes became dissociated in both light- and dark-stored desiccated material. Images PMID:3934134

  4. High iron requirement for growth, photosynthesis, and low-light acclimation in the coastal cyanobacterium Synechococcus bacillaris.

    PubMed

    Sunda, William G; Huntsman, Susan A

    2015-01-01

    Iron limits carbon fixation in much of the modern ocean due to the very low solubility of ferric iron in oxygenated ocean waters. We examined iron-limitation of growth rate under varying light intensities in the coastal cyanobacterium Synechococcus bacillaris, a descendent of the oxygenic phototrophs that evolved ca. 3 billion years ago when the ocean was reducing and iron was present at much higher concentrations as soluble Fe(II). Decreasing light intensity increased the cellular iron:carbon (Fe:C) ratio needed to support a given growth rate, indicating that iron and light may co-limit the growth of Synechococcus in the ocean, as shown previously for eukaryotic phytoplankton. The cellular Fe:C ratios needed to support a given growth rate were 5- to 8-fold higher than ratios for coastal eukaryotic algae growing under the same light conditions. The higher iron requirements for growth in the coastal cyanobacterium may be largely caused by the high demand for iron in photosynthesis, and to higher ratios of iron-rich photosystem I to iron-poor photosystem II in Synechococcus than in eukaryotic algae. This high iron requirement may also be vestigial and represent an adaptation to the much higher iron levels in the ancient reducing ocean. Due to the high cellular iron requirement for photosynthesis and growth, and for low light acclimation, Synechococcus may be excluded from many low-iron and low-light environments. Indeed, it decreases rapidly with depth within the ocean's deep chlorophyll maximum (DCM) where iron and light levels are low, and lower-iron requiring picoeukaryotes typically dominate the biomass of phytoplankton community within the mid to lower DCM. PMID:26150804

  5. Changes in gene expression, cell physiology and toxicity of the harmful cyanobacterium Microcystis aeruginosa at elevated CO2.

    PubMed

    Sandrini, Giovanni; Cunsolo, Serena; Schuurmans, J Merijn; Matthijs, Hans C P; Huisman, Jef

    2015-01-01

    Rising CO2 concentrations may have large effects on aquatic microorganisms. In this study, we investigated how elevated pCO2 affects the harmful freshwater cyanobacterium Microcystis aeruginosa. This species is capable of producing dense blooms and hepatotoxins called microcystins. Strain PCC 7806 was cultured in chemostats that were shifted from low to high pCO2 conditions. This resulted in a transition from a C-limited to a light-limited steady state, with a ~2.7-fold increase of the cyanobacterial biomass and ~2.5-fold more microcystin per cell. Cells increased their chlorophyll a and phycocyanin content, and raised their PSI/PSII ratio at high pCO2. Surprisingly, cells had a lower dry weight and contained less carbohydrates, which might be an adaptation to improve the buoyancy of Microcystis when light becomes more limiting at high pCO2. Only 234 of the 4691 genes responded to elevated pCO2. For instance, expression of the carboxysome, RuBisCO, photosystem and C metabolism genes did not change significantly, and only a few N assimilation genes were expressed differently. The lack of large-scale changes in the transcriptome could suit a buoyant species that lives in eutrophic lakes with strong CO2 fluctuations very well. However, we found major responses in inorganic carbon uptake. At low pCO2, cells were mainly dependent on bicarbonate uptake, whereas at high pCO2 gene expression of the bicarbonate uptake systems was down-regulated and cells shifted to CO2 and low-affinity bicarbonate uptake. These results show that the need for high-affinity bicarbonate uptake systems ceases at elevated CO2. Moreover, the combination of an increased cyanobacterial abundance, improved buoyancy, and higher toxin content per cell indicates that rising atmospheric CO2 levels may increase the problems associated with the harmful cyanobacterium Microcystis in eutrophic lakes. PMID:25999931

  6. Group 3 sigma factors in the marine cyanobacterium Synechococcus sp. strain PCC 7002 are required for growth at low temperature.

    PubMed

    Inoue-Sakamoto, Kaori; Gruber, Tanja M; Christensen, Suzanne K; Arima, Hiromi; Sakamoto, Toshio; Bryant, Donald A

    2007-04-01

    Three genes, sigF, sigG and sigH, encoding group 3 sigma factors have been cloned and characterized in the marine cyanobacterium Synechococcus sp. strain PCC 7002. The sigF gene product was similar to sigma factors involved in general stress response and sporulation in other organisms, and the sigG and sigH gene products were similar to extracytoplasmic function (ECF) sigma factors. The sigG and sigH genes were associated with the putative regulatory genes and the sizes of transcripts for sigG and sigH genes were large enough to be cotranscribed with the associated downstream genes. The sigG downstream gene was designated sapG (sigG-associated protein), and yeast two-hybrid analysis demonstrated that SigG and SapG interact when produced in yeast cells. Null mutants of these three group 3 sigma factor genes were created by interposon mutagenesis. The growth of the sigF mutant strain was much slower than the wild-type strain at 15 degrees C, although the growth rates at 22 degrees C and 38 degrees C were identical to those of the wild-type strain. The sigG mutant could not grow continuously at 22 degrees C, and no growth occurred at 15 degrees C. Since SigG and SapG interact in yeast cells and the sigG and sapG mutants showed a similar growth phenotype, SapG is likely to be a regulatory protein for SigG involved in the same pathway in transcriptional regulation in this cyanobacterium. PMID:17575449

  7. High iron requirement for growth, photosynthesis, and low-light acclimation in the coastal cyanobacterium Synechococcus bacillaris

    PubMed Central

    Sunda, William G.; Huntsman, Susan A.

    2015-01-01

    Iron limits carbon fixation in much of the modern ocean due to the very low solubility of ferric iron in oxygenated ocean waters. We examined iron-limitation of growth rate under varying light intensities in the coastal cyanobacterium Synechococcus bacillaris, a descendent of the oxygenic phototrophs that evolved ca. 3 billion years ago when the ocean was reducing and iron was present at much higher concentrations as soluble Fe(II). Decreasing light intensity increased the cellular iron:carbon (Fe:C) ratio needed to support a given growth rate, indicating that iron and light may co-limit the growth of Synechococcus in the ocean, as shown previously for eukaryotic phytoplankton. The cellular Fe:C ratios needed to support a given growth rate were 5- to 8-fold higher than ratios for coastal eukaryotic algae growing under the same light conditions. The higher iron requirements for growth in the coastal cyanobacterium may be largely caused by the high demand for iron in photosynthesis, and to higher ratios of iron-rich photosystem I to iron-poor photosystem II in Synechococcus than in eukaryotic algae. This high iron requirement may also be vestigial and represent an adaptation to the much higher iron levels in the ancient reducing ocean. Due to the high cellular iron requirement for photosynthesis and growth, and for low light acclimation, Synechococcus may be excluded from many low-iron and low-light environments. Indeed, it decreases rapidly with depth within the ocean’s deep chlorophyll maximum (DCM) where iron and light levels are low, and lower-iron requiring picoeukaryotes typically dominate the biomass of phytoplankton community within the mid to lower DCM. PMID:26150804

  8. Global Transcriptional Responses of the Toxic Cyanobacterium, Microcystis aeruginosa, to Nitrogen Stress, Phosphorus Stress, and Growth on Organic Matter

    PubMed Central

    Harke, Matthew J.; Gobler, Christopher J.

    2013-01-01

    Whole transcriptome shotgun sequencing (RNA-seq) was used to assess the transcriptomic response of the toxic cyanobacterium Microcystis aeruginosa during growth with low levels of dissolved inorganic nitrogen (low N), low levels of dissolved inorganic phosphorus (low P), and in the presence of high levels of high molecular weight dissolved organic matter (HMWDOM). Under low N, one third of the genome was differentially expressed, with significant increases in transcripts observed among genes within the nir operon, urea transport genes (urtBCDE), and amino acid transporters while significant decreases in transcripts were observed in genes related to photosynthesis. There was also a significant decrease in the transcription of the microcystin synthetase gene set under low N and a significant decrease in microcystin content per Microcystis cell demonstrating that N supply influences cellular toxicity. Under low P, 27% of the genome was differentially expressed. The Pho regulon was induced leading to large increases in transcript levels of the alkaline phosphatase phoX, the Pst transport system (pstABC), and the sphX gene, and transcripts of multiple sulfate transporter were also significantly more abundant. While the transcriptional response to growth on HMWDOM was smaller (5–22% of genes differentially expressed), transcripts of multiple genes specifically associated with the transport and degradation of organic compounds were significantly more abundant within HMWDOM treatments and thus may be recruited by Microcystis to utilize these substrates. Collectively, these findings provide a comprehensive understanding of the nutritional physiology of this toxic, bloom-forming cyanobacterium and the role of N in controlling microcystin synthesis. PMID:23894552

  9. Potential effects of UV radiation on photosynthetic structures of the bloom-forming cyanobacterium Cylindrospermopsis raciborskii CYRF-01

    PubMed Central

    Noyma, Natália P.; Silva, Thiago P.; Chiarini-Garcia, Hélio; Amado, André M.; Roland, Fábio; Melo, Rossana C. N.

    2015-01-01

    Cyanobacteria are aquatic photosynthetic microorganisms. While of enormous ecological importance, they have also been linked to human and animal illnesses around the world as a consequence of toxin production by some species. Cylindrospermopsis raciborskii, a filamentous nitrogen-fixing cyanobacterium, has attracted considerable attention due to its potential toxicity and ecophysiological adaptability. We investigated whether C. raciborskii could be affected by ultraviolet (UV) radiation. Non-axenic cultures of C. raciborskii were exposed to three UV treatments (UVA, UVB, or UVA + UVB) over a 6 h period, during which cell concentration, viability and ultrastructure were analyzed. UVA and UVA + UVB treatments showed significant negative effects on cell concentration (decreases of 56.4 and 64.3%, respectively). This decrease was directly associated with cell death as revealed by a cell viability fluorescent probe. Over 90% of UVA + UVB- and UVA-treated cells died. UVB did not alter cell concentration, but reduced cell viability in almost 50% of organisms. Transmission electron microscopy (TEM) revealed a drastic loss of thylakoids, membranes in which cyanobacteria photosystems are localized, after all treatments. Moreover, other photosynthetic- and metabolic-related structures, such as accessory pigments and polyphosphate granules, were damaged. Quantitative TEM analyses revealed a 95.8% reduction in cell area occupied by thylakoids after UVA treatment, and reduction of 77.6 and 81.3% after UVB and UVA + UVB treatments, respectively. Results demonstrated clear alterations in viability and photosynthetic structures of C. raciborskii induced by various UV radiation fractions. This study facilitates our understanding of the subcellular organization of this cyanobacterium species, identifies specific intracellular targets of UVA and UVB radiation and reinforces the importance of UV radiation as an environmental stressor. PMID:26579108

  10. Changes in gene expression, cell physiology and toxicity of the harmful cyanobacterium Microcystis aeruginosa at elevated CO2

    PubMed Central

    Sandrini, Giovanni; Cunsolo, Serena; Schuurmans, J. Merijn; Matthijs, Hans C. P.; Huisman, Jef

    2015-01-01

    Rising CO2 concentrations may have large effects on aquatic microorganisms. In this study, we investigated how elevated pCO2 affects the harmful freshwater cyanobacterium Microcystis aeruginosa. This species is capable of producing dense blooms and hepatotoxins called microcystins. Strain PCC 7806 was cultured in chemostats that were shifted from low to high pCO2 conditions. This resulted in a transition from a C-limited to a light-limited steady state, with a ~2.7-fold increase of the cyanobacterial biomass and ~2.5-fold more microcystin per cell. Cells increased their chlorophyll a and phycocyanin content, and raised their PSI/PSII ratio at high pCO2. Surprisingly, cells had a lower dry weight and contained less carbohydrates, which might be an adaptation to improve the buoyancy of Microcystis when light becomes more limiting at high pCO2. Only 234 of the 4691 genes responded to elevated pCO2. For instance, expression of the carboxysome, RuBisCO, photosystem and C metabolism genes did not change significantly, and only a few N assimilation genes were expressed differently. The lack of large-scale changes in the transcriptome could suit a buoyant species that lives in eutrophic lakes with strong CO2 fluctuations very well. However, we found major responses in inorganic carbon uptake. At low pCO2, cells were mainly dependent on bicarbonate uptake, whereas at high pCO2 gene expression of the bicarbonate uptake systems was down-regulated and cells shifted to CO2 and low-affinity bicarbonate uptake. These results show that the need for high-affinity bicarbonate uptake systems ceases at elevated CO2. Moreover, the combination of an increased cyanobacterial abundance, improved buoyancy, and higher toxin content per cell indicates that rising atmospheric CO2 levels may increase the problems associated with the harmful cyanobacterium Microcystis in eutrophic lakes. PMID:25999931

  11. Photosystem Trap Energies and Spectrally-Dependent Energy-Storage Efficiencies in the Chl d-Utilizing Cyanobacterium, Acaryochloris Marina

    NASA Technical Reports Server (NTRS)

    Mielke, Steven P.; Kiang, Nancy Y.; Blankenship, Robert E.; Mauzerall, David

    2012-01-01

    Acaryochloris marina is the only species known to utilize chlorophyll (Chl) d as a principal photopigment. The peak absorption wavelength of Chl d is redshifted approx. 40 nm in vivo relative to Chl a, enabling this cyanobacterium to perform oxygenic phototrophy in niche environments enhanced in far-red light. We present measurements of the in vivo energy-storage (E-S) efficiency of photosynthesis in A. marina, obtained using pulsed photoacoustics (PA) over a 90-nm range of excitation wavelengths in the red and far-red. Together with modeling results, these measurements provide the first direct observation of the trap energies of PSI and PSII, and also the photosystem-specific contributions to the total E-S efficiency. We find the maximum observed efficiency in A. marina (40+/-1% at 735 nm) is higher than in the Chl a cyanobacterium Synechococcus leopoliensis (35+/-1% at 690 nm). The efficiency at peak absorption wavelength is also higher in A. marina (36+/-1% at 710 nm vs. 31+/-1% at 670 nm). In both species, the trap efficiencies are approx. 40% (PSI) and approx. 30% (PSII). The PSI trap in A. marina is found to lie at 740+/-5 nm, in agreement with the value inferred from spectroscopic methods. The best fit of the model to the PA data identifies the PSII trap at 723+/-3 nm, supporting the view that the primary electron-donor is Chl d, probably at the accessory (ChlD1) site. A decrease in efficiency beyond the trap wavelength, consistent with uphill energy transfer, is clearly observed and fit by the model. These results demonstrate that the E-S efficiency in A. marina is not thermodynamically limited, suggesting that oxygenic photosynthesis is viable in even redder light environments.

  12. Microenvironmental Ecology of the Chlorophyll b-Containing Symbiotic Cyanobacterium Prochloron in the Didemnid Ascidian Lissoclinum patella

    PubMed Central

    Kühl, Michael; Behrendt, Lars; Trampe, Erik; Qvortrup, Klaus; Schreiber, Ulrich; Borisov, Sergey M.; Klimant, Ingo; Larkum, Anthony W. D.

    2012-01-01

    The discovery of the cyanobacterium Prochloron was the first finding of a bacterial oxyphototroph with chlorophyll (Chl) b, in addition to Chl a. It was first described as Prochloron didemni but a number of clades have since been described. Prochloron is a conspicuously large (7–25??m) unicellular cyanobacterium living in a symbiotic relationship, primarily with (sub-) tropical didemnid ascidians; it has resisted numerous cultivation attempts and appears truly obligatory symbiotic. Recently, a Prochloron draft genome was published, revealing no lack of metabolic genes that could explain the apparent inability to reproduce and sustain photosynthesis in a free-living stage. Possibly, the unsuccessful cultivation is partly due to a lack of knowledge about the microenvironmental conditions and ecophysiology of Prochloron in its natural habitat. We used microsensors, variable chlorophyll fluorescence imaging and imaging of O2 and pH to obtain a detailed insight to the microenvironmental ecology and photobiology of Prochloron in hospite in the didemnid ascidian Lissoclinum patella. The microenvironment within ascidians is characterized by steep gradients of light and chemical parameters that change rapidly with varying irradiances. The interior zone of the ascidians harboring Prochloron thus became anoxic and acidic within a few minutes of darkness, while the same zone exhibited O2 super-saturation and strongly alkaline pH after a few minutes of illumination. Photosynthesis showed lack of photoinhibition even at high irradiances equivalent to full sunlight, and photosynthesis recovered rapidly after periods of anoxia. We discuss these new insights on the ecological niche of Prochloron and possible interactions with its host and other microbes in light of its recently published genome and a recent study of the overall microbial diversity and metagenome of L. patella. PMID:23226144

  13. The freshwater cyanobacterium Anabaena doliolum transformed with ApGSMT-DMT exhibited enhanced salt tolerance and protection to nitrogenase activity, but became halophilic.

    PubMed

    Singh, Meenakshi; Sharma, Naveen K; Prasad, Shyam Babu; Yadav, Suresh Singh; Narayan, Gopeshwar; Rai, Ashwani K

    2013-03-01

    Glycine betaine (GB) is an important osmolyte synthesized in response to different abiotic stresses, including salinity. The two known pathways of GB synthesis involve: 1) two step oxidation of choline (choline ? betaine aldehyde ? GB), generally found in plants, microbes and animals; and 2) three step methylation of glycine (glycine ? sarcosine ? dimethylglycine ? GB), mainly found in halophilic archaea, sulphur bacteria and the cyanobacterium Aphanothece (Ap.) halophytica. Here, we transformed a salt-sensitive freshwater diazotrophic filamentous cyanobacterium Anabaena (An.) doliolum with N-methyltransferase genes (ApGSMT-DMT) from Ap. halophytica using the triparental conjugation method. The transformed An. doliolum synthesized and accumulated GB in cells, and showed increased salt tolerance and protection to nitrogenase activity. The salt responsiveness of the transformant was also apparent as GB synthesis increased with increasing concentrations of NaCl in the nutrient solution, and maximal [12.92 µmol (g dry weight)(-1)] in cells growing at 0.5 M NaCl. Therefore, the transformed cyanobacterium has changed its behaviour from preferring freshwater to halophily. This study may have important biotechnological implications for the development of stress tolerant nitrogen-fixing cyanobacteria as biofertilizers for sustainable agriculture. PMID:23329680

  14. Different phycobilin antenna organisations affect the balance between light use and growth rate in the cyanobacterium Microcystis aeruginosa and in the cryptophyte Cryptomonas ovata.

    PubMed

    Kunath, Christfried; Jakob, Torsten; Wilhelm, Christian

    2012-03-01

    During the recent years, wide varieties of methodologies have been developed up to the level of commercial use to measure photosynthetic electron transport by modulated chlorophyll a-in vivo fluorescence. It is now widely accepted that the ratio between electron transport rates and new biomass (P (Fl)/B (C)) is not fixed and depends on many factors that are also taxonomically variable. In this study, the balance between photon absorption and biomass production has been measured in two phycobilin-containing phototrophs, namely, a cyanobacterium and a cryptophyte, which differ in their antenna organization. It is demonstrated that the different antenna organization exerts influence on the regulation of the primary photosynthetic reaction and the dissipation of excessively absorbed radiation. Although, growth rates and the quantum efficiency of biomass production of both phototrophs were comparable, the ratio P (Fl)/B (C) was twice as high in the cryptophyte in comparison to the cyanobacterium. It is assumed that this discrepancy is because of differences in the metabolic regulation of cell growth. In the cryptophyte, absorbed photosynthetic energy is used to convert assimilated carbon directly into proteins and lipids, whereas in the cyanobacterium, the photosynthetic energy is preferentially stored as carbohydrates. PMID:22183802

  15. The non-ribosomal assembly and frequent occurrence of the protease inhibitors spumigins in the bloom-forming cyanobacterium Nodularia spumigena.

    PubMed

    Fewer, David P; Jokela, Jouni; Rouhiainen, Leo; Wahlsten, Matti; Koskenniemi, Kerttu; Stal, Lucas J; Sivonen, Kaarina

    2009-09-01

    Nodularia spumigena is a filamentous nitrogen-fixing cyanobacterium that forms toxic blooms in brackish water bodies worldwide. Spumigins are serine protease inhibitors reported from a single strain of N. spumigena isolated from the Baltic Sea. These linear tetrapeptides contain non-proteinogenic amino acids including a C-terminal alcohol derivative of arginine. However, very little is known about these compounds despite the ecological importance of N. spumigena. We show that spumigins are assembled by two non-ribosomal peptide synthetases encoded in a 21 kb biosynthetic gene cluster. The compact non-ribosomal peptide synthetase features a reductive loading and release mechanism. Our analyses demonstrate that the bulk of spumigins produced by N. spumigena are released as peptide aldehydes in contrast to earlier findings. The main spumigin E variant contains an argininal residue and is a potent trypsin inhibitor. Spumigins were present in all of the N. spumigena strains isolated from the Baltic Sea and comprised up to 1% of the dry weight of the cyanobacterium. Our results demonstrate that bloom-forming N. spumigena strains produce a cocktail of enzyme inhibitors, which may explain in part the ecological success of this cyanobacterium in brackish water bodies worldwide. PMID:19691450

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

    PubMed Central

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

    2015-01-01

    Water use assessment is important for bioproduction using cyanobacteria. For eco-friendly reasons, seawater should preferably be used for cyanobacteria cultivation instead of freshwater. In this study, we demonstrated that the freshwater unicellular cyanobacterium Synechocystis sp. PCC 6803 could be grown in a medium based on seawater. The Synechocystis wild-type strain grew well in an artificial seawater (ASW) medium supplemented with nitrogen and phosphorus sources. The addition of HEPES buffer improved cell growth overall, although the growth in ASW medium was inferior to that in the synthetic BG-11 medium. The levels of proteins involved in sugar metabolism changed depending on the culture conditions. The biosynthesis of several amino acids including aspartate, glutamine, glycine, proline, ornithine, and lysine, was highly up-regulated by cultivation in ASW. Two types of natural seawater (NSW) were also made available for the cultivation of Synechocystis cells, with supplementation of both nitrogen and phosphorus sources. These results revealed the potential use of seawater for the cultivation of freshwater cyanobacteria, which would help to reduce freshwater consumption during biorefinery using cyanobacteria. PMID:25954257

  17. Photoacclimation of cultured strains of the cyanobacterium Microcystis aeruginosa to high-light and low-light conditions.

    PubMed

    Bañares-España, Elena; Kromkamp, Jacco C; López-Rodas, Victoria; Costas, Eduardo; Flores-Moya, Antonio

    2013-03-01

    The cyanobacterium Microcystis aeruginosa forms blooms that can consist of colonies. We have investigated how M. aeruginosa acclimatizes to changing light conditions such as can occur during blooms. Three different strains were exposed to two irradiance levels: lower (LL) and higher (HL) than the irradiance-onset saturation parameter. We measured the photosynthetic pigment concentrations, PSII photochemical efficiency, electron transport rate (ETR), irradiance-saturated ETR and ETR efficiency. The relationship between ETR and photosynthetic oxygen production and the excess in PSII capacity were also studied for one strain. Higher values of chlorophyll a and phycocyanin and lower values of total carotenoids were found under LL conditions in the three strains. The strains showed clear differences in the irradiance-saturated ETR and in ETR efficiency under both LL and HL treatments. No differences were found in the linear relationship between ETR and photosynthetic oxygen production under both irradiance treatments. LL-acclimated cells showed higher PSII excess capacity than HL ones, possibly because their higher pigment content could result in a higher light stress than HL cells when forming surface blooms. The fact that the genetically different strains show different photosynthetic physiologies suggests that the very dynamic light climate observed in lakes may allow their coexistence. PMID:23057858

  18. In-Situ Optical and Acoustical Measurements of the Buoyant Cyanobacterium P. Rubescens: Spatial and Temporal Distribution Patterns

    PubMed Central

    Hofmann, Hilmar; Peeters, Frank

    2013-01-01

    Optical (fluorescence) and acoustic in-situ techniques were tested in their ability to measure the spatial and temporal distribution of plankton in freshwater ecosystems with special emphasis on the harmful and buoyant cyanobacterium P. rubescens. Fluorescence was measured with the multi-spectral FluoroProbe (Moldaenke FluoroProbe, MFP) and a Seapoint Chlorophyll Fluorometer (SCF). In-situ measurements of the acoustic backscatter strength (ABS) were conducted with three different acoustic devices covering multiple acoustic frequencies (614 kHz ADCP, 2 MHz ADP, and 6 MHz ADV). The MFP provides a fast and reliable technique to measure fluorescence at different wavelengths in situ, which allows discriminating between P. rubescens and other phytoplankton species. All three acoustic devices are sensitive to P. rubescens even if other scatterers, e.g., zooplankton or suspended sediment, are present in the water column, because P. rubescens containing gas vesicles has a strong density difference and hence acoustic contrast to the ambient water and other scatterers. After calibration, the combination of optical and acoustical measurements not only allows qualitative and quantitative observation of P. rubescens, but also distinction between P. rubescens, other phytoplankton, and zooplankton. As the measuring devices can sample in situ at high rates they enable assessment of plankton distributions at high temporal (minutes) and spatial (decimeters) resolution or covering large temporal (seasonal) and spatial (basin scale) scales. PMID:24303028

  19. Gene expression of a two-component regulatory system associated with sunscreen biosynthesis in the cyanobacterium Nostoc punctiforme ATCC 29133.

    PubMed

    Janssen, Jacob; Soule, Tanya

    2016-01-01

    Long-wavelength ultraviolet radiation (UVA) can damage cells through photooxidative stress, leading to harmful photosensitized proteins and pigments in cyanobacteria. To mitigate damage, some cyanobacteria secrete the UVA-absorbing pigment scytonemin into their extracellular sheath. Comparative genomic analyses suggest that scytonemin biosynthesis is regulated by the two-component regulatory system (TCRS) proteins encoded by Npun_F1277 and Npun_F1278 in the cyanobacterium Nostoc punctiforme ATCC 29133. To understand the dynamics of these genes, their expression was measured following exposure to UVA, UVB, high visible (VIS) irradiance and oxidative stress for 20, 40 and 60 min. Overall, both genes had statistically similar patterns of expression for all four conditions and were generally upregulated, except for those exposed to UVB by 60 min and for the cells under oxidative stress. The greatest UVA response was an upregulation by 20 min, while the response to UVB was the most dramatic and persisted through 40 min. High VIS irradiance resulted in a modest upregulation, while oxidative stress caused a slight downregulation. Both genes were also found to occur on the same transcript. These results demonstrate that these genes are positively responding to several light-associated conditions, which suggests that this TCRS may regulate more than just scytonemin biosynthesis under UVA stress. PMID:26656542

  20. Oscillating behavior of carbohydrate granule formation and dinitrogen fixation in the cyanobacterium Cyanothece sp. strain ATCC 51142

    NASA Technical Reports Server (NTRS)

    Schneegurt, M. A.; Sherman, D. M.; Nayar, S.; Sherman, L. A.; Mitchell, C. A. (Principal Investigator)

    1994-01-01

    It has been shown that some aerobic, unicellular, diazotrophic cyanobacteria temporally separate photosynthetic O2 evolution and oxygen-sensitive N2 fixation. Cyanothece sp. ATCC strain 51142 is an aerobic, unicellular, diazotrophic cyanobacterium that fixes N2 during discrete periods of its cell cycle. When the bacteria are maintained under diurnal light-dark cycles, N2 fixation occurs in the dark. Similar cycling is observed in continuous light, implicating a circadian rhythm. Under N2-fixing conditions, large inclusion granules form between the thylakoid membranes. Maximum granulation, as observed by electron microscopy, occurs before the onset of N2 fixation, and the granules decrease in number during the period of N2 fixation. The granules can be purified from cell homogenates by differential centrifugation. Biochemical analyses of the granules indicate that these structures are primarily carbohydrate, with some protein. Further analyses of the carbohydrate have shown that it is a glucose polymer with some characteristics of glycogen. It is proposed that N2 fixation is driven by energy and reducing power stored in these inclusion granules. Cyanothece sp. strain ATCC 51142 represents an excellent experimental organism for the study of the protective mechanisms of nitrogenase, metabolic events in cyanobacteria under normal and stress conditions, the partitioning of resources between growth and storage, and biological rhythms.

  1. Consortium of the 'bichlorophyllous' cyanobacterium Prochlorothrix hollandica and chemoheterotrophic partner bacteria: culture and metagenome-based description.

    PubMed

    Velichko, Natalia; Chernyaeva, Ekaterina; Averina, Svetlana; Gavrilova, Olga; Lapidus, Alla; Pinevich, Alexander

    2015-08-01

    'Bacterial consortium' sensu lato applies to mutualism or syntrophy-based systems consisting of unrelated bacteria. Consortia of cyanobacteria have been preferentially studied on Anabaena epibioses; non-photosynthetic satellites of other filamentous or unicellular cyanobacteria were also considered although structure-functional data are few. At the same time, information about consortia of cyanobacteria which have light-harvesting antennae distinct from standard phycobilisome was missing. In this study, we characterized first, via a polyphasic approach, the cultivable consortium of Prochlorothrix hollandica?CCAP 1490/1 (filamentous cyanobacterium which contains chlorophylls a, b/carotenoid/protein complex in the absence of phycobilisome) and non-photosynthetic heterotrophic bacteria. The strains of most abundant satellites were isolated and identified. Consortium metagenome reconstructed via 454-pyro and Illumina sequencing was shown to include, except for P.?hollandica, several phylotypes of Proteobacteria and Bacteroidetes. The ratio of consortium members was essentially stable irrespective of culture age, and restored after artificially imposed imbalance. The consortium had a complex spatial arrangement as demonstrated by FISH and SEM images of the association, epibiosis, and biofilm type. Preliminary data of metagenome annotation agreed with the hypothesis that satellite bacteria contribute to P.?hollandica protection from reactive oxygen species (ROS). PMID:25990300

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

    PubMed

    Pernil, Rafael; Picossi, Silvia; Herrero, Antonia; Flores, Enrique; Mariscal, Vicente

    2015-01-01

    Anabaena sp. strain PCC 7120 is a filamentous cyanobacterium that can use inorganic compounds such as nitrate or ammonium as nitrogen sources. In the absence of combined nitrogen, it can fix N2 in differentiated cells called heterocysts. Anabaena also shows substantial activities of amino acid uptake, and three ABC-type transporters for amino acids have been previously characterized. Seven new loci encoding predicted amino acid transporters were identified in the Anabaena genomic sequence and inactivated. Two of them were involved in amino acid uptake. Locus alr2535-alr2541 encodes the elements of a hydrophobic amino acid ABC-type transporter that is mainly involved in the uptake of glycine. ORF all0342 encodes a putative transporter from the dicarboxylate/amino acid:cation symporter (DAACS) family whose inactivation resulted in an increased uptake of a broad range of amino acids. An assay to study amino acid release from Anabaena filaments to the external medium was set up. Net release of the alanine analogue ?-aminoisobutyric acid (AIB) was observed when transport system N-I (a hydrophobic amino acid ABC-type transporter) was engaged in the uptake of a specific substrate. The rate of AIB release was directly proportional to the intracellular AIB concentration, suggesting leakage from the cells by diffusion. PMID:25915115

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

    PubMed Central

    Pernil, Rafael; Picossi, Silvia; Herrero, Antonia; Flores, Enrique; Mariscal, Vicente

    2015-01-01

    Anabaena sp. strain PCC 7120 is a filamentous cyanobacterium that can use inorganic compounds such as nitrate or ammonium as nitrogen sources. In the absence of combined nitrogen, it can fix N2 in differentiated cells called heterocysts. Anabaena also shows substantial activities of amino acid uptake, and three ABC-type transporters for amino acids have been previously characterized. Seven new loci encoding predicted amino acid transporters were identified in the Anabaena genomic sequence and inactivated. Two of them were involved in amino acid uptake. Locus alr2535-alr2541 encodes the elements of a hydrophobic amino acid ABC-type transporter that is mainly involved in the uptake of glycine. ORF all0342 encodes a putative transporter from the dicarboxylate/amino acid:cation symporter (DAACS) family whose inactivation resulted in an increased uptake of a broad range of amino acids. An assay to study amino acid release from Anabaena filaments to the external medium was set up. Net release of the alanine analogue ?-aminoisobutyric acid (AIB) was observed when transport system N-I (a hydrophobic amino acid ABC-type transporter) was engaged in the uptake of a specific substrate. The rate of AIB release was directly proportional to the intracellular AIB concentration, suggesting leakage from the cells by diffusion. PMID:25915115

  4. Redox regulation of glycogen biosynthesis in the cyanobacterium Synechocystis sp. PCC 6803: analysis of the AGP and glycogen synthases.

    PubMed

    Díaz-Troya, Sandra; López-Maury, Luis; Sánchez-Riego, Ana María; Roldán, Miguel; Florencio, Francisco J

    2014-01-01

    Glycogen constitutes the major carbon storage source in cyanobacteria, as starch in algae and higher plants. Glycogen and starch synthesis is linked to active photosynthesis and both of them are degraded to glucose in the dark to maintain cell metabolism. Control of glycogen biosynthesis in cyanobacteria could be mediated by the regulation of the enzymes involved in this process, ADP-glucose pyrophosphorylase (AGP) and glycogen synthase, which were identified as putative thioredoxin targets. We have analyzed whether both enzymes were subjected to redox modification using purified recombinant enzymes or cell extracts in the model cyanobacterium Synechocystis sp. PCC 6803. Our results indicate that both AGP and glycogen synthases are sensitive to copper oxidation. However, only AGP exhibits a decrease in its enzymatic activity, which is recovered after reduction by DTT or reduced thioredoxin (TrxA), suggesting a redox control of AGP. In order to elucidate the role in redox control of the cysteine residues present on the AGP sequence (C45, C185, C320, and C337), they were replaced with serine. All AGP mutant proteins remained active when expressed in Synechocystis, although they showed different electrophoretic mobility profiles after copper oxidation, reflecting a complex pattern of cysteines interaction. PMID:24121290

  5. Heterocyst-specific flavodiiron protein Flv3B enables oxic diazotrophic growth of the filamentous cyanobacterium Anabaena sp. PCC 7120.

    PubMed

    Ermakova, Maria; Battchikova, Natalia; Richaud, Pierre; Leino, Hannu; Kosourov, Sergey; Isojärvi, Janne; Peltier, Gilles; Flores, Enrique; Cournac, Laurent; Allahverdiyeva, Yagut; Aro, Eva-Mari

    2014-07-29

    Flavodiiron proteins are known to have crucial and specific roles in photoprotection of photosystems I and II in cyanobacteria. The filamentous, heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120 contains, besides the four flavodiiron proteins Flv1A, Flv2, Flv3A, and Flv4 present in vegetative cells, two heterocyst-specific flavodiiron proteins, Flv1B and Flv3B. Here, we demonstrate that Flv3B is responsible for light-induced O2 uptake in heterocysts, and that the absence of the Flv3B protein severely compromises the growth of filaments in oxic, but not in microoxic, conditions. It is further demonstrated that Flv3B-mediated photosynthetic O2 uptake has a distinct role in heterocysts which cannot be substituted by respiratory O2 uptake in the protection of nitrogenase from oxidative damage and, thus, in an efficient provision of nitrogen to filaments. In line with this conclusion, the ?flv3B strain has reduced amounts of nitrogenase NifHDK subunits and shows multiple symptoms of nitrogen deficiency in the filaments. The apparent imbalance of cytosolic redox state in ?flv3B heterocysts also has a pronounced influence on the amounts of different transcripts and proteins. Therefore, an O2-related mechanism for control of gene expression is suggested to take place in heterocysts. PMID:25002499

  6. Requirement of Fra proteins for communication channels between cells in the filamentous nitrogen-fixing cyanobacterium Anabaena sp. PCC 7120.

    PubMed

    Omairi-Nasser, Amin; Mariscal, Vicente; Austin, Jotham R; Haselkorn, Robert

    2015-08-11

    The filamentous nitrogen-fixing cyanobacterium Anabaena sp. PCC 7120 differentiates specialized cells, heterocysts, that fix atmospheric nitrogen and transfer the fixed nitrogen to adjacent vegetative cells. Reciprocally, vegetative cells transfer fixed carbon to heterocysts. Several routes have been described for metabolite exchange within the filament, one of which involves communicating channels that penetrate the septum between adjacent cells. Several fra gene mutants were isolated 25 y ago on the basis of their phenotypes: inability to fix nitrogen and fragmentation of filaments upon transfer from N+ to N- media. Cryopreservation combined with electron tomography were used to investigate the role of three fra gene products in channel formation. FraC and FraG are clearly involved in channel formation, whereas FraD has a minor part. Additionally, FraG was located close to the cytoplasmic membrane and in the heterocyst neck, using immunogold labeling with antibody raised to the N-terminal domain of the FraG protein. PMID:26216997

  7. Sustained photoproduction of ammonia from dinitrogen and water by the nitrogen-fixing cyanobacterium Anabaena sp. strain ATCC33047

    SciTech Connect

    Ramos, J.L.; Guerrero, M.G.; Losada, M.

    1984-07-01

    Conditions have been developed that lengthen the time during which photosynthetic dinitrogen fixation by filaments of the cyanobacterium Anabaena sp. strain ATCC 33047 proceeds freely, whereas the subsequent conversion of ammonia into organic nitrogen remains blocked, with the resulting ammonia released to the outer medium. When L-methionine-DL-sulfoximine was added every 20 h, maximal rates of ammonia production (25 to 30 ..mu..mol/mg of chlorophyll per h) were maintained for about 50 h. After this time, ammonia production ceased due to a deficiency of glutamine and other nitrogenous compounds in the filaments, conditions which finally led to cell lysis. The effective ammonia production period could be further extended to about 7 days by adding a small amount of glutamine at the end of a 40-h production period or by allowing the cells to recover for 8 h in the absence of L-methionine-DL-sulfoximine after every 40-h period in the presence of the inhibitor. A more prolonged steady production of ammonia, lasting for longer than 2 weeks, was achieved by alternating treatments with the glutamine synthetase inhibitors L-methionine-DL-sulfoximine and phosphinothricin, provided that 8-h recovery periods in the absence of either compound were also alternated throughout. The biochemically manipulated cyanobacterial filaments thus represent a system that is relatively stable with time for the conversion of light energy into chemical energy, with the net generation of a valuable fuel and fertilizer through the photoreduction of dinitrogen to ammonia.

  8. Ecological physiology of Synechococcus sp. strain SH-94-5, a naturally occurring cyanobacterium deficient in nitrate assimilation

    NASA Technical Reports Server (NTRS)

    Miller, S. R.; Castenholz, R. W.

    2001-01-01

    Synechococcus sp. strain SH-94-5 is a nitrate assimilation-deficient cyanobacterium which was isolated from an ammonium-replete hot spring in central Oregon. While this clone could grow on ammonium and some forms of organic nitrogen as sole nitrogen sources, it could not grow on either nitrate or nitrite, even under conditions favoring passive diffusion. It was determined that this clone does not express functional nitrate reductase or nitrite reductase and that the lack of activity of either enzyme is not due to inactivation of the cyanobacterial nitrogen control protein NtcA. A few other naturally occurring cyanobacterial strains are also nitrate assimilation deficient, and phylogenetic analyses indicated that the ability to utilize nitrate has been independently lost at least four times during the evolutionary history of the cyanobacteria. This phenotype is associated with the presence of environmental ammonium, a negative regulator of nitrate assimilation gene expression, which may indicate that natural selection to maintain functional copies of nitrate assimilation genes has been relaxed in these habitats. These results suggest how the evolutionary fates of conditionally expressed genes might differ between environments and thereby effect ecological divergence and biogeographical structure in the microbial world.

  9. Ecological Physiology of Synechococcus sp. Strain SH-94-5, a Naturally Occurring Cyanobacterium Deficient in Nitrate Assimilation

    PubMed Central

    Miller, Scott R.; Castenholz, Richard W.

    2001-01-01

    Synechococcus sp. strain SH-94-5 is a nitrate assimilation-deficient cyanobacterium which was isolated from an ammonium-replete hot spring in central Oregon. While this clone could grow on ammonium and some forms of organic nitrogen as sole nitrogen sources, it could not grow on either nitrate or nitrite, even under conditions favoring passive diffusion. It was determined that this clone does not express functional nitrate reductase or nitrite reductase and that the lack of activity of either enzyme is not due to inactivation of the cyanobacterial nitrogen control protein NtcA. A few other naturally occurring cyanobacterial strains are also nitrate assimilation deficient, and phylogenetic analyses indicated that the ability to utilize nitrate has been independently lost at least four times during the evolutionary history of the cyanobacteria. This phenotype is associated with the presence of environmental ammonium, a negative regulator of nitrate assimilation gene expression, which may indicate that natural selection to maintain functional copies of nitrate assimilation genes has been relaxed in these habitats. These results suggest how the evolutionary fates of conditionally expressed genes might differ between environments and thereby effect ecological divergence and biogeographical structure in the microbial world. PMID:11425713

  10. Characterization of the chemical diversity of glycosylated mycosporine-like amino acids in the terrestrial cyanobacterium Nostoc commune.

    PubMed

    Nazifi, Ehsan; Wada, Naoki; Asano, Tomoya; Nishiuchi, Takumi; Iwamuro, Yoshiaki; Chinaka, Satoshi; Matsugo, Seiichi; Sakamoto, Toshio

    2015-01-01

    Mycosporine-like amino acids (MAAs) are UV-absorbing pigments, and structurally unique glycosylated MAAs are found in the terrestrial cyanobacterium Nostoc commune. In this study, we examined two genotypes of N.commune colonies with different water extract UV-absorption spectra. We found structurally distinct MAAs in each genotype. The water extract from genotype A showed a UV-absorbing spectrum with an absorption maximum at 335nm. The extract contained the following compounds: 7-O-(?-arabinopyranosyl)-porphyra-334 (478Da), pentose-bound shinorine (464Da), hexose-bound porphyra-334 (508Da) and porphyra-334 (346Da). The water extract from genotype B showed a characteristic UV-absorbing spectrum with double absorption maxima at 312 and 340nm. The extract contained hybrid MAAs (1050Da and 880Da) with two distinct chromophores of 3-aminocyclohexen-1-one and 1,3-diaminocyclohexen linked to 2-O-(?-xylopyranosyl)-?-galactopyranoside. A novel 273-Da MAA with an absorption maximum at 310nm was also identified in genotype B. The MAA consisted of a 3-aminocyclohexen-1-one linked to a ?-aminobutyric acid chain. These MAAs had potent radical scavenging activities in vitro and the results confirmed that the MAAs have multiple roles as a UV protectant and an antioxidant relevant to anhydrobiosis in N. commune. The two genotypes of N. commune exclusively produced their own characteristic glycosylated MAAs, which supports that MAA composition could be a chemotaxonomic marker for the classification of N. commune. PMID:25543549

  11. PilB localization correlates with the direction of twitching motility in the cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Schuergers, Nils; Nürnberg, Dennis J; Wallner, Thomas; Mullineaux, Conrad W; Wilde, Annegret

    2015-05-01

    Twitching motility depends on the adhesion of type IV pili (T4P) to a substrate, with cell movement driven by extension and retraction of the pili. The mechanism of twitching motility, and the events that lead to a reversal of direction, are best understood in rod-shaped bacteria such as Myxococcus xanthus. In M. xanthus, the direction of movement depends on the unipolar localization of the pilus extension and retraction motors PilB and PilT to opposite cell poles. Reversal of direction results from relocalization of PilB and PilT. Some cyanobacteria utilize twitching motility for phototaxis. Here, we examine twitching motility in the cyanobacterium Synechocystis sp. PCC 6803, which has a spherical cell shape without obvious polarity. We use a motile Synechocystis sp. PCC 6803 strain expressing a functional GFP-tagged PilB1 protein to show that PilB1 tends to localize in 'crescents' adjacent to a specific region of the cytoplasmic membrane. Crescents are more prevalent under the low-light conditions that favour phototactic motility, and the direction of motility strongly correlates with the orientation of the crescent. We conclude that the direction of twitching motility in Synechocystis sp. PCC 6803 is controlled by the localization of the T4P apparatus, as it is in M. xanthus. The PilB1 crescents in the spherical cells of Synechocystis can be regarded as being equivalent to the leading pole in the rod-shaped cells. PMID:25721851

  12. Hydrogen Generation through Indirect Biophotolysis in Batch Cultures of the Non-Heterocystous Nitrogen-Fixing Cyanobacterium Plectonema boryanum

    SciTech Connect

    Huesemann, Michael H.; Hausmann, Tom S.; Carter, Blaine M.; Gerschler, Jared J.; Benemann, John R.

    2010-09-01

    The nitrogen-fixing non-heterocystous cyanobacterium Plectonema boryanum was used as a model organism to study hydrogen generation by indirect biophotolysis in nitrogen-limited batch cultures that were continuously illuminated and sparged with argon/CO2 to maintain anaerobiosis. The highest hydrogen production rate (i.e., 0.18 mL/mg?day or 7.3 ?mol/mg?day) ) was observed in cultures with an initial medium nitrate concentration of 1 mM at a light intensity of 100 ?mol/m2?sec. The addition of photosystem II inhibitor DCMU did not reduce hydrogen production rates relative to unchallenged controls for 50 to 150 hours, and intracellular glycogen concentrations decreased significantly during the hydrogen generation period. The insensitivity of the hydrogen production process to DCMU is indicative of the fact that hydrogen was not derived from water splitting at photosystem II (i.e., direct biophotolysis) but rather from electrons provided by intracellular glycogen reserves (i.e., indirect biophotolysis). It was shown that hydrogen generation could be sustained for long time periods by subjecting the cultures to alternating cycles of aerobic, nitrogen-limited growth and anaerobic hydrogen production.

  13. Genetic diversity along the life cycle of the cyanobacterium Microcystis: highlight on the complexity of benthic and planktonic interactions.

    PubMed

    Sabart, Marion; Misson, Benjamin; Jobard, Marlène; Bronner, Gisèle; Donnadieu-Bernard, Florence; Duffaud, Emilie; Salençon, Marie-José; Amblard, Christian; Latour, Delphine

    2015-03-01

    Microcystis is a toxic freshwater cyanobacterium with an annual life cycle characterized by the alternation of a planktonic proliferation stage in summer and a benthic resting stage in winter. Given the importance of both stages for the development and the survival of the population, we investigated the genotypic composition of the planktonic and benthic Microcystis subpopulations from the Grangent reservoir (France) during two distinct proliferation periods. Our results showed a succession of different dominant genotypes in the sediment as well as in the water all along the study periods with some common genotypes to both compartments. Analysis of molecular variance and UniFrac analysis confirmed the similarity between some benthic and planktonic samples, thus evidencing exchanges of genotypes between water and sediment. Thanks to these data, recruitment and sedimentation were proven not to be restricted to spring and autumn, contrary to what was previously thought. Finally, genetic diversity was significantly higher in the sediment than in the water (P?

  14. Acclimation of the Global Transcriptome of the Cyanobacterium Synechococcus sp. Strain PCC 7002 to Nutrient Limitations and Different Nitrogen Sources

    PubMed Central

    Ludwig, Marcus; Bryant, Donald A.

    2012-01-01

    The unicellular, euryhaline cyanobacterium Synechococcus sp. strain PCC 7002 is a model organism for laboratory-based studies of cyanobacterial metabolism and is a potential platform for biotechnological applications. Two of its most notable properties are its exceptional tolerance of high-light intensity and very rapid growth under optimal conditions. In this study, transcription profiling by RNAseq has been used to perform an integrated study of global changes in transcript levels in cells subjected to limitation for the major nutrients CO2, nitrogen, sulfate, phosphate, and iron. Transcriptional patterns for cells grown on nitrate, ammonia, and urea were also studied. Nutrient limitation caused strong decreases of transcript levels of the genes encoding major metabolic pathways, especially for components of the photosynthetic apparatus, CO2 fixation, and protein biosynthesis. Uptake mechanisms for the respective nutrients were strongly up-regulated. The transcription data further suggest that major changes in the composition of the NADH dehydrogenase complex occur upon nutrient limitation. Transcripts for flavoproteins increased strongly when CO2 was limiting. Genes involved in protection from oxidative stress generally showed high, constitutive transcript levels, which possibly explains the high-light tolerance of this organism. The transcriptomes of cells grown with ammonia or urea as nitrogen source showed increased transcript levels for components of the CO2 fixation machinery compared to cells grown with nitrate, but in general transcription differences in cells grown on different N-sources exhibited surprisingly minor differences. PMID:22514553

  15. Discovery of Rare and Highly Toxic Microcystins from Lichen-Associated Cyanobacterium Nostoc sp. Strain IO-102-I

    PubMed Central

    Oksanen, Ilona; Jokela, Jouni; Fewer, David P.; Wahlsten, Matti; Rikkinen, Jouko; Sivonen, Kaarina

    2004-01-01

    The production of hepatotoxic cyclic heptapeptides, microcystins, is almost exclusively reported from planktonic cyanobacteria. Here we show that a terrestrial cyanobacterium Nostoc sp. strain IO-102-I isolated from a lichen association produces six different microcystins. Microcystins were identified with liquid chromatography-UV mass spectrometry by their retention times, UV spectra, mass fragmentation, and comparison to microcystins from the aquatic Nostoc sp. strain 152. The dominant microcystin produced by Nostoc sp. strain IO-102-I was the highly toxic [ADMAdda5]microcystin-LR, which accounted for ca. 80% of the total microcystins. We assigned a structure of [DMAdda5]microcystin-LR and [d-Asp3,ADMAdda5]microcystin-LR and a partial structure of three new [ADMAdda5]-XR type of microcystin variants. Interestingly, Nostoc spp. strains IO-102-I and 152 synthesized only the rare ADMAdda and DMAdda subfamilies of microcystin variants. Phylogenetic analyses demonstrated congruence between genes involved directly in microcystin biosynthesis and the 16S rRNA and rpoC1 genes of Nostoc sp. strain IO-102-I. Nostoc sp. strain 152 and the Nostoc sp. strain IO-102-I are distantly related, revealing a sporadic distribution of toxin production in the genus Nostoc. Nostoc sp. strain IO-102-I is closely related to Nostoc punctiforme PCC 73102 and other symbiotic Nostoc strains and most likely belongs to this species. Together, this suggests that other terrestrial and aquatic strains of the genus Nostoc may have retained the genes necessary for microcystin biosynthesis. PMID:15466511

  16. [NiFe]-hydrogenase is essential for cyanobacterium Synechocystis sp. PCC 6803 aerobic growth in the dark

    PubMed Central

    De Rosa, Edith; Checchetto, Vanessa; Franchin, Cinzia; Bergantino, Elisabetta; Berto, Paola; Szabò, Ildikò; Giacometti, Giorgio M.; Arrigoni, Giorgio; Costantini, Paola

    2015-01-01

    The cyanobacterium Synechocystis sp. PCC 6803 has a bidirectional [NiFe]-hydrogenase (Hox hydrogenase) which reversibly reduces protons to H2. This enzyme is composed of a hydrogenase domain and a diaphorase moiety, which is distinctly homologous to the NADH input module of mitochondrial respiratory Complex I. Hox hydrogenase physiological function is still unclear, since it is not required for Synechocystis fitness under standard growth conditions. We analyzed the phenotype under prolonged darkness of three Synechocystis knock-out strains, lacking either Hox hydrogenase (?HoxE-H) or one of the proteins responsible for the assembly of its NiFe active site (?HypA1 and ?HypB1). We found that Hox hydrogenase is required for Synechocystis growth under this condition, regardless of the functional status of its catalytic site, suggesting an additional role beside hydrogen metabolism. Moreover, quantitative proteomic analyses revealed that the expression levels of several subunits of the respiratory NADPH/plastoquinone oxidoreductase (NDH-1) are reduced when Synechocystis is grown in the dark. Our findings suggest that the Hox hydrogenase could contribute to electron transport regulation when both photosynthetic and respiratory pathways are down-regulated, and provide a possible explanation for the close evolutionary relationship between mitochondrial respiratory Complex I and cyanobacterial [NiFe]-hydrogenases. PMID:26215212

  17. Growth, photosynthesis, active oxygen species and antioxidants responses of paddy field cyanobacterium Plectonema boryanum to endosulfan stress.

    PubMed

    Prasad, Sheo Mohan; Kumar, Deelip; Zeeshan, Mohd

    2005-04-01

    The present paper deals with the insecticide endosulfan (5, 10 and 20 microg/ml)-induced changes in physiological and biochemical parameters related to photosynthesis and defense systems in paddy field cyanobacterium Plectonema boryanum grown under laboratory conditions. Growth and photosynthetic pigments, i.e., chlorophyll a, carotenoids and phycocyanin, were adversely affected by endosulfan treatment and the inhibition was found to be dose dependent. The toxic effect of endosulfan was more pronounced on phycocyanin; however, a considerable reduction in chlorophyll a and carotenoids was also noticed. 14C-fixation appeared to be more sensitive to insecticide than whole cell oxygen evolution. Spheroplasts treated with endosulfan exhibited a severe effect on PSII activity which was mainly due to blocking of the electron flow at the water oxidation side. In contrast to this, similar doses of endosulfan caused the least effect on PSI activity (DCPIP/ASC-->MV). Furthermore, endosulfan with increasing doses accelerated the formation of active oxygen species, i.e., O2- and H2O2, in cells progressively, whereby an enhanced peroxidation of lipid and leakage of cell membrane were noticed. As a consequence of active oxygen species (AOS) generation in endosulfan-treated cells, the activity of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) was enhanced considerably. Besides the accelerated action of enzymatic defense systems, chemical antioxidant ascorbate showed a decreasing trend with the rising concentration of endosulfan (5, 10 and 20 microg/ml). PMID:15942872

  18. Inactivation of the Deg protease family in the cyanobacterium Synechocystis sp. PCC 6803 has impact on the outer cell layers.

    PubMed

    Cheregi, Otilia; Miranda, Hélder; Gröbner, Gerhard; Funk, Christiane

    2015-11-01

    The serine type Deg/HtrA proteases are distributed in a wide range of organisms from Escherichia coli to humans. The cyanobacterium Synechocystis sp. PCC 6803 possesses three Deg protease orthologues: HtrA, HhoA and HhoB. Previously we compared Synechocystis 6803 wild type cells exposed to mild or severe stress conditions with a mutant lacking all three Deg proteases and demonstrated that stress had strong impact on the proteomes and metabolomes [1]. To identify the biochemical processes, which this protease family is involved in, here we compared Synechocystis sp. PCC 6803 wild type cells with a mutant lacking all three Deg proteases grown under normal growth conditions (30°C and 40?molphotonsm(-2)s(-1)). Deletion of the Deg proteases lead to the down-regulation of proteins related to the biosynthesis of outer cell layers (e.g. the GDP mannose 4,6-dehydratase) and affected protein secretion. During the late growth phase of the culture Deg proteases were found to be secreted to the extracellular medium of the Synechocystis sp. PCC 6803 wild type strain. While cyanobacterial Deg proteases seem to act mainly in the periplasmic space, deletion of the three proteases influences the proteome and metabolome of the whole cell. Impairments in the outer cell layers of the triple mutant might explain the higher sensitivity toward light and oxidative stress, which was observed earlier by Barker and coworkers [2]. PMID:26051963

  19. Genomic DNA Microarray Analysis: Identification of New Genes Regulated by Light Color in the Cyanobacterium Fremyella diplosiphon

    PubMed Central

    Stowe-Evans, Emily L.; Ford, James; Kehoe, David M.

    2004-01-01

    Many cyanobacteria use complementary chromatic adaptation to efficiently utilize energy from both green and red regions of the light spectrum during photosynthesis. Although previous studies have shown that acclimation to changing light wavelengths involves many physiological responses, research to date has focused primarily on the expression and regulation of genes that encode proteins of the major photosynthetic light-harvesting antennae, the phycobilisomes. We have used two-dimensional gel electrophoresis and genomic DNA microarrays to expand our understanding of the physiology of acclimation to light color in the cyanobacterium Fremyella diplosiphon. We found that the levels of nearly 80 proteins are altered in cells growing in green versus red light and have cloned and positively identified 17 genes not previously known to be regulated by light color in any species. Among these are homologs of genes present in many bacteria that encode well-studied proteins lacking clearly defined functions, such as tspO, which encodes a tryptophan-rich sensory protein, and homologs of genes encoding proteins of clearly defined function in many species, such as nblA and chlL, encoding phycobilisome degradation and chlorophyll biosynthesis proteins, respectively. Our results suggest novel roles for several of these gene products and highly specialized, unique uses for others. PMID:15205436

  20. Soft x-ray imaging of intracellular granules of filamentous cyanobacterium generating musty smell in Lake Biwa

    NASA Astrophysics Data System (ADS)

    Takemoto, K.; Mizuta, G.; Yamamoto, A.; Yoshimura, M.; Ichise, S.; Namba, H.; Kihara, H.

    2013-10-01

    A planktonic blue-green algae, which are currently identified as Phormidium tenue, was observed by a soft x-ray microscopy (XM) for comparing a musty smell generating green strain (PTG) and a non-smell brown strain (PTB). By XM, cells were clearly imaged, and several intracellular granules which could not be observed under a light microscope were visualized. The diameter of granules was about 0.5-1 ?m, and one or a few granules were seen in a cell. XM analyses showed that width of cells and sizes of intracellular granules were quite different between PTG and PTB strains. To study the granules observed by XM, transmission in more detail, transmission electron microscopy (TEM) and indirect fluorescent-antibody technique (IFA) were applied. By TEM, carboxysomes, thylakoids and polyphosphate granules were observed. IFA showed the presence of carboxysomes. Results lead to the conclusion that intracellular granules observed under XM are carboxysomes or polyphosphate granules. These results demonstrate that soft XM is effective for analyzing fine structures of small organisms such as cyanobacterium, and for discriminating the strains which generates musty smells from others.

  1. Contribution of a Sodium Ion Gradient to Energy Conservation during Fermentation in the Cyanobacterium Arthrospira (Spirulina) maxima CS-328 ? †

    PubMed Central

    Carrieri, Damian; Ananyev, Gennady; Lenz, Oliver; Bryant, Donald A.; Dismukes, G. Charles

    2011-01-01

    Sodium gradients in cyanobacteria play an important role in energy storage under photoautotrophic conditions but have not been well studied during autofermentative metabolism under the dark, anoxic conditions widely used to produce precursors to fuels. Here we demonstrate significant stress-induced acceleration of autofermentation of photosynthetically generated carbohydrates (glycogen and sugars) to form excreted organic acids, alcohols, and hydrogen gas by the halophilic, alkalophilic cyanobacterium Arthrospira (Spirulina) maxima CS-328. When suspended in potassium versus sodium phosphate buffers at the start of autofermentation to remove the sodium ion gradient, photoautotrophically grown cells catabolized more intracellular carbohydrates while producing 67% higher yields of hydrogen, acetate, and ethanol (and significant amounts of lactate) as fermentative products. A comparable acceleration of fermentative carbohydrate catabolism occurred upon dissipating the sodium gradient via addition of the sodium-channel blocker quinidine or the sodium-ionophore monensin but not upon dissipating the proton gradient with the proton-ionophore dinitrophenol (DNP). The data demonstrate that intracellular energy is stored via a sodium gradient during autofermentative metabolism and that, when this gradient is blocked, the blockage is compensated by increased energy conversion via carbohydrate catabolism. PMID:21890670

  2. Heterocyst-specific flavodiiron protein Flv3B enables oxic diazotrophic growth of the filamentous cyanobacterium Anabaena sp. PCC 7120

    PubMed Central

    Ermakova, Maria; Battchikova, Natalia; Richaud, Pierre; Leino, Hannu; Kosourov, Sergey; Isojärvi, Janne; Peltier, Gilles; Flores, Enrique; Cournac, Laurent; Allahverdiyeva, Yagut; Aro, Eva-Mari

    2014-01-01

    Flavodiiron proteins are known to have crucial and specific roles in photoprotection of photosystems I and II in cyanobacteria. The filamentous, heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120 contains, besides the four flavodiiron proteins Flv1A, Flv2, Flv3A, and Flv4 present in vegetative cells, two heterocyst-specific flavodiiron proteins, Flv1B and Flv3B. Here, we demonstrate that Flv3B is responsible for light-induced O2 uptake in heterocysts, and that the absence of the Flv3B protein severely compromises the growth of filaments in oxic, but not in microoxic, conditions. It is further demonstrated that Flv3B-mediated photosynthetic O2 uptake has a distinct role in heterocysts which cannot be substituted by respiratory O2 uptake in the protection of nitrogenase from oxidative damage and, thus, in an efficient provision of nitrogen to filaments. In line with this conclusion, the ?flv3B strain has reduced amounts of nitrogenase NifHDK subunits and shows multiple symptoms of nitrogen deficiency in the filaments. The apparent imbalance of cytosolic redox state in ?flv3B heterocysts also has a pronounced influence on the amounts of different transcripts and proteins. Therefore, an O2-related mechanism for control of gene expression is suggested to take place in heterocysts. PMID:25002499

  3. Effects of Hydrogen Peroxide and Ultrasound on Biomass Reduction and Toxin Release in the Cyanobacterium, Microcystis aeruginosa

    PubMed Central

    Lürling, Miquel; Meng, Debin; Faassen, Elisabeth J.

    2014-01-01

    Cyanobacterial blooms are expected to increase, and the toxins they produce threaten human health and impair ecosystem services. The reduction of the nutrient load of surface waters is the preferred way to prevent these blooms; however, this is not always feasible. Quick curative measures are therefore preferred in some cases. Two of these proposed measures, peroxide and ultrasound, were tested for their efficiency in reducing cyanobacterial biomass and potential release of cyanotoxins. Hereto, laboratory assays with a microcystin (MC)-producing cyanobacterium (Microcystis aeruginosa) were conducted. Peroxide effectively reduced M. aeruginosa biomass when dosed at 4 or 8 mg L?1, but not at 1 and 2 mg L?1. Peroxide dosed at 4 or 8 mg L?1 lowered total MC concentrations by 23%, yet led to a significant release of MCs into the water. Dissolved MC concentrations were nine-times (4 mg L?1) and 12-times (8 mg L?1 H2O2) higher than in the control. Cell lysis moreover increased the proportion of the dissolved hydrophobic variants, MC-LW and MC-LF (where L = Leucine, W = tryptophan, F = phenylalanine). Ultrasound treatment with commercial transducers sold for clearing ponds and lakes only caused minimal growth inhibition and some release of MCs into the water. Commercial ultrasound transducers are therefore ineffective at controlling cyanobacteria. PMID:25513892

  4. Global Proteomics Reveal An Atypical Strategy for Carbon/Nitrogen Assimilation by a Cyanobacterium Under Diverse Environmental Perturbations

    SciTech Connect

    Wegener, Kimberly M.; Singh, Abhay K.; Jacobs, Jon M.; Elvitigala, Thanura R.; Welsh, Eric A.; Keren, Nir S.; Gritsenko, Marina A.; Ghosh, Bijoy K.; Camp, David G.; Smith, Richard D.; Pakrasi, Himadri B.

    2010-12-01

    Cyanobacteria, the only prokaryotes capable of oxygenic photosynthesis, are present in diverse ecological niches and play crucial roles in global carbon and nitrogen cycles. To proliferate in nature, cyanobacteria utilize a host of stress responses to accommodate periodic changes in environmental conditions. A detailed knowledge of the composition of, as well as the dynamic changes in, the proteome is necessary to gain fundamental insights into such stress responses. Toward this goal, we have performed a largescale proteomic analysis of the widely studied model cyanobacterium Synechocystis sp. PCC 6803 under 33 different environmental conditions. The resulting high-quality dataset consists of 22,318 unique peptides corresponding to 1,955 proteins, a coverage of 53% of the predicted proteome. Quantitative determination of protein abundances has led to the identification of 1,198 differentially regulated proteins. Notably, our analysis revealed that a common stress response under various environmental perturbations, irrespective of amplitude and duration, is the activation of atypical pathways for the acquisition of carbon and nitrogen from urea and arginine. In particular, arginine is catabolized via putrescine to produce succinate and glutamate, sources of carbon and nitrogen, respectively. This study provides the most comprehensive functional and quantitative analysis of the Synechocystis proteome to date, and shows that a significant stress response of cyanobacteria involves an uncommon mode of acquisition of carbon and nitrogen. Oxygenic phototrophic prokaryotes, the progenitors of the chloroplast, are crucial to global oxygen production and worldwide carbon and nitrogen cycles. These microalgae are robust organisms capable carbon neutral biofuel production. Synechocystis sp. PCC 6803 has historically been a model cyanobacterium for photosynthetic research and is emerging as a promising biofuel platform. Cellular responses are severely modified by environmental conditions, such as temperature and nutrient availability. However the global protein responses of Synechocystis 6803 under physiological relevant environmental stresses have not been characterized. Here we present the first global proteome analysis of a photoautotrophic bacteria and the most complete coverage to date of a photosynthetic prokaryotic proteome. To obtain a more complete description of the protein components of Synechocystis 6803, we have performed an in-depth proteome analysis of this organism utilizing the Accurate Mass and Time (AMT) tag approach1 utilizing 33 growth conditions and timepoints. The resulting proteome consists of 22,318 unique peptides, corresponding to 2,369 unique proteins, covering 65% of the predicted proteins. Quantitative analysis of protein abundance ratios under nutrient stress revealed that Synechocystis 6803 resorts to a universal mechanism for nitrogen utilization under phosphate, sulfate, iron, and nitrogen depletion. Comparison of this proteomic data with previously published microarray studies under similar environmental conditions showed that the general response predicted by both types of analyses are common but that the actual levels of protein expression can not be inferred from gene expression data. Our results demonstrate a global nitrogen response to multiple stressors that may be similar to that used by other cyanobacteria under various stress conditions. We anticipate that this protein expression data will be a foundation for the photosynthetic and biofuel communities to better understand metabolic changes under physiological conditions relevant to global productivity. Further more, this comparison of correlation between gene and protein expression data provides deeper insight into the ongoing debate as to whether gene expression can be used to infer cellular response.

  5. Reversal in competitive dominance of a toxic versus non-toxic cyanobacterium in response to rising CO2.

    PubMed

    Van de Waal, Dedmer B; Verspagen, Jolanda M H; Finke, Jan F; Vournazou, Vasiliki; Immers, Anne K; Kardinaal, W Edwin A; Tonk, Linda; Becker, Sven; Van Donk, Ellen; Visser, Petra M; Huisman, Jef

    2011-09-01

    Climate change scenarios predict a doubling of the atmospheric CO(2) concentration by the end of this century. Yet, how rising CO(2) will affect the species composition of aquatic microbial communities is still largely an open question. In this study, we develop a resource competition model to investigate competition for dissolved inorganic carbon in dense algal blooms. The model predicts how dynamic changes in carbon chemistry, pH and light conditions during bloom development feed back on competing phytoplankton species. We test the model predictions in chemostat experiments with monocultures and mixtures of a toxic and non-toxic strain of the freshwater cyanobacterium Microcystis aeruginosa. The toxic strain was able to reduce dissolved CO(2) to lower concentrations than the non-toxic strain, and became dominant in competition at low CO(2) levels. Conversely, the non-toxic strain could grow at lower light levels, and became dominant in competition at high CO(2) levels but low light availability. The model captured the observed reversal in competitive dominance, and was quantitatively in good agreement with the results of the competition experiments. To assess whether microcystins might have a role in this reversal of competitive dominance, we performed further competition experiments with the wild-type strain M. aeruginosa PCC 7806 and its mcyB mutant impaired in microcystin production. The microcystin-producing wild type had a strong selective advantage at low CO(2) levels but not at high CO(2) levels. Our results thus demonstrate both in theory and experiment that rising CO(2) levels can alter the community composition and toxicity of harmful algal blooms. PMID:21390081

  6. Gene Transfer in Leptolyngbya sp. Strain BL0902, a Cyanobacterium Suitable for Production of Biomass and Bioproducts

    PubMed Central

    Taton, Arnaud; Lis, Ewa; Adin, Dawn M.; Dong, Guogang; Cookson, Scott; Kay, Steve A.; Golden, Susan S.; Golden, James W.

    2012-01-01

    Current cyanobacterial model organisms were not selected for their growth traits or potential for the production of renewable biomass, biofuels, or other products. The cyanobacterium strain BL0902 emerged from a search for strains with superior growth traits. Morphology and 16S rRNA sequence placed strain BL0902 in the genus Leptolyngbya. Leptolyngbya sp. strain BL0902 (hereafter Leptolyngbya BL0902) showed robust growth at temperatures from 22°C to 40°C and tolerated up to 0.5 M NaCl, 32 mM urea, high pH, and high solar irradiance. Its growth rate under outdoor conditions rivaled Arthrospira (“pirulina” strains. Leptolyngbya BL0902 accumulated higher lipid content and a higher proportion of monounsaturated fatty acids than Arthrospira strains. In addition to these desirable qualities, Leptolyngbya BL0902 is amenable to genetic engineering that is reliable, efficient, and stable. We demonstrated conjugal transfer from Escherichia coli of a plasmid based on RSF1010 and expression of spectinomycin/streptomycin resistance and yemGFP reporter transgenes. Conjugation efficiency was investigated in biparental and triparental matings with and without a “elper”plasmid that carries DNA methyltransferase genes, and with two different conjugal plasmids. We also showed that Leptolyngbya BL0902 is amenable to transposon mutagenesis with a Tn5 derivative. To facilitate genetic manipulation of Leptolyngbya BL0902, a conjugal plasmid vector was engineered to carry a trc promoter upstream of a Gateway recombination cassette. These growth properties and genetic tools position Leptolyngbya BL0902 as a model cyanobacterial production strain. PMID:22292073

  7. Hydrogen production from organic substrates in an aerobic nitrogen-fixing marine unicellular cyanobacterium Synechococcus sp. strain Miami BG 043511

    SciTech Connect

    Luo, Y.H.; Mitsui, A. )

    1994-11-20

    Synechococcus sp. strain Miami BG 043511 exhibits very high H[sub 2] photoproduction from water, but the H[sub 2] photo-production capability is lost rapidly with the age of the batch culture. The decrease of the capability coincides with the decrease of cellular glucose content. However, H[sub 2] photoproduction capability can be restored by the addition of organic substrates. Among 40 organic compounds tested, carbohydrates such as glucose, fructose, maltose, and sucrose were effective electron donors. Among organic acids tested, only pyruvate was an effective electron donor. Among alcohols tested, glycerol was a good electron donor, whereas ethanol was a poor but positive electron donor. These results demonstrate that this unicellular cyanobacterium exhibits a wide substrate specificity for H[sub 2] photoproduction but has a different substrate specificity compared to photosynthetic bacteria. The maximum rates of H[sub 2] photoproduction from a 6-day-old batch culture with 25 mmol of pyruvate, glucose, maltose, sucrose, fructose, and glycerol were 1.11, 0.62, 0.05, 0.47, 0.30, and 0.39 [mu]moles per mg cell dry weight per hour respectively. Therefore, this cyanobacterial strain may have a potential significance in removing organic materials from the wastewater and simultaneously transforming them to H[sub 2] gas, a pollution-free energy. The activity of nitrogenase, which catalyzes hydrogen production, completely disappeared when intracellular glucose was used up, but it could be restored by the addition of organic substrates such as glucose and pyruvate.

  8. The ? Subunit of RNA Polymerase Is Essential for Thermal Acclimation of the Cyanobacterium Synechocystis Sp. PCC 6803

    PubMed Central

    Gunnelius, Liisa; Kurkela, Juha; Hakkila, Kaisa; Koskinen, Satu; Parikainen, Marjaana; Tyystjärvi, Taina

    2014-01-01

    The rpoZ gene encodes the small ? subunit of RNA polymerase. A ?rpoZ strain of the cyanobacterium Synechocystis sp. PCC 6803 grew well in standard conditions (constant illumination at 40 µmol photons m?2 s?1; 32°C; ambient CO2) but was heat sensitive and died at 40°C. In the control strain, 71 genes were at least two-fold up-regulated and 91 genes down-regulated after a 24-h treatment at 40°C, while in ?rpoZ 394 genes responded to heat. Only 62 of these heat-responsive genes were similarly regulated in both strains, and 80% of heat-responsive genes were unique for ?rpoZ. The RNA polymerase core and the primary ? factor SigA were down-regulated in the control strain at 40°C but not in ?rpoZ. In accordance with reduced RNA polymerase content, the total RNA content of mild-heat-stress-treated cells was lower in the control strain than in ?rpoZ. Light-saturated photosynthetic activity decreased more in ?rpoZ than in the control strain upon mild heat stress. The amounts of photosystem II and rubisco decreased at 40°C in both strains while PSI and the phycobilisome antenna protein allophycocyanin remained at the same level as in standard conditions. The phycobilisome rod proteins, phycocyanins, diminished during the heat treatment in ?rpoZ but not in the control strain, and the nblA1 and nblA2 genes (encode NblA proteins required for phycobilisome degradation) were up-regulated only in ?rpoZ. Our results show that the ? subunit of RNAP is essential in heat stress because it is required for heat acclimation of diverse cellular processes. PMID:25386944

  9. Application of real-time PCR for quantification of microcystin genotypes in a population of the toxic cyanobacterium Microcystis sp.

    PubMed

    Kurmayer, Rainer; Kutzenberger, Thomas

    2003-11-01

    The cyanobacterium Microcystis sp. frequently develops water blooms consisting of organisms with different genotypes that either produce or lack the hepatotoxin microcystin. In order to monitor the development of microcystin (mcy) genotypes during the seasonal cycle of the total population, mcy genotypes were quantified by means of real-time PCR in Lake Wannsee (Berlin, Germany) from June 1999 to October 2000. Standard curves were established by relating cell concentrations to the threshold cycle (the PCR cycle number at which the fluorescence passes a set threshold level) determined by the Taq nuclease assay (TNA) for two gene regions, the intergenic spacer region within the phycocyanin (PC) operon to quantify the total population and the mcyB gene, which is indicative of microcystin synthesis. In laboratory batch cultures, the cell numbers inferred from the standard curve by TNA correlated significantly with the microscopically determined cell numbers on a logarithmic scale. The TNA analysis of 10 strains revealed identical amplification efficiencies for both genes. In the field, the proportion of mcy genotypes made up the smaller part of the PC genotypes, ranging from 1 to 38%. The number of mcyB genotypes was one-to-one related to the number of PC genotypes, and parallel relationships between cell numbers estimated via the inverted microscope technique and TNA were found for both genes. It is concluded that the mean proportion of microcystin genotypes is stable from winter to summer and that Microcystis cell numbers could be used to infer the mean proportion of mcy genotypes in Lake Wannsee. PMID:14602633

  10. Balticidins A-D, antifungal hassallidin-like lipopeptides from the Baltic Sea cyanobacterium Anabaena cylindrica Bio33.

    PubMed

    Bui, Thanh-Huong; Wray, Victor; Nimtz, Manfred; Fossen, Torgils; Preisitsch, Michael; Schröder, Gudrun; Wende, Kristian; Heiden, Stefan E; Mundt, Sabine

    2014-06-27

    Balticidins A-D (1-4), four new antifungal lipopeptides, were isolated from the laboratory-cultivated cyanobacterium Anabaena cylindrica strain Bio33 isolated from a water sample collected from the Baltic Sea, Rügen Island, Germany. Fractionation of the 50% aqueous MeOH extract was performed by bioassay-guided silica gel column chromatography followed by SPE and repeated reversed-phase HPLC. The main fraction containing the compounds exhibited a strong and specific antifungal activity with inhibition zones in an agar-diffusion assay from 21 to 32 mm against Candida albicans, Candida krusei, Candida maltosa, Aspergillus fumigatus, Microsporum gypseum, Mucor sp., and Microsporum canis. The structures were elucidated by multidimensional (1)H and (13)C NMR spectroscopy, HRESIMS, amino acid analysis, and sugar analysis. Spectroscopic data analysis afforded an unambiguous sequence of R.CHO(S1).CHOH.CONH-Thr(1)-Thr(2)-Thr(3)-HOTyr(4)-Dhb(5)-D-Gln(6)-Gly(7)-NMeThr(8)(S2)-L-Gln COOH(9), in which Dhb is dehydroaminobutyric acid, S1 is d(-)-arabinose-(3-1)-D-(+)-galacturonic acid, S2 is D-(+)-mannose, and R is the aliphatic residue -C13H26Cl or -C13H27. Besides NMeThr, D-allo-Thr, D-Thr, and L-Thr were identified, but the position of the enantiomers in the sequence is not clear. The four balticidins differ in their cyclic (2, 4)/linear (1, 3) core and the presence (1, 2)/absence (3, 4) of chlorine in the aliphatic unit. PMID:24937366

  11. Cluster of genes that encode positive and negative elements influencing filament length in a heterocyst-forming cyanobacterium.

    PubMed

    Merino-Puerto, Victoria; Herrero, Antonia; Flores, Enrique

    2013-09-01

    The filamentous, heterocyst-forming cyanobacteria perform oxygenic photosynthesis in vegetative cells and nitrogen fixation in heterocysts, and their filaments can be hundreds of cells long. In the model heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120, the genes in the fraC-fraD-fraE operon are required for filament integrity mainly under conditions of nitrogen deprivation. The fraC operon transcript partially overlaps gene all2395, which lies in the opposite DNA strand and ends 1 bp beyond fraE. Gene all2395 produces transcripts of 1.35 kb (major transcript) and 2.2 kb (minor transcript) that overlap fraE and whose expression is dependent on the N-control transcription factor NtcA. Insertion of a gene cassette containing transcriptional terminators between fraE and all2395 prevented production of the antisense RNAs and resulted in an increased length of the cyanobacterial filaments. Deletion of all2395 resulted in a larger increase of filament length and in impaired growth, mainly under N2-fixing conditions and specifically on solid medium. We denote all2395 the fraF gene, which encodes a protein restricting filament length. A FraF-green fluorescent protein (GFP) fusion protein accumulated significantly in heterocysts. Similar to some heterocyst differentiation-related proteins such as HglK, HetL, and PatL, FraF is a pentapeptide repeat protein. We conclude that the fraC-fraD-fraE?fraF gene cluster (where the arrow indicates a change in orientation), in which cis antisense RNAs are produced, regulates morphology by encoding proteins that influence positively (FraC, FraD, FraE) or negatively (FraF) the length of the filament mainly under conditions of nitrogen deprivation. This gene cluster is often conserved in heterocyst-forming cyanobacteria. PMID:23813733

  12. Cell Envelope Components Influencing Filament Length in the Heterocyst-Forming Cyanobacterium Anabaena sp. Strain PCC 7120

    PubMed Central

    Burnat, Mireia; Schleiff, Enrico

    2014-01-01

    Heterocyst-forming cyanobacteria grow as chains of cells (known as trichomes or filaments) that can be hundreds of cells long. The filament consists of individual cells surrounded by a cytoplasmic membrane and peptidoglycan layers. The cells, however, share a continuous outer membrane, and septal proteins, such as SepJ, are important for cell-cell contact and filament formation. Here, we addressed a possible role of cell envelope components in filamentation, the process of producing and maintaining filaments, in the model cyanobacterium Anabaena sp. strain PCC 7120. We studied filament length and the response of the filaments to mechanical fragmentation in a number of strains with mutations in genes encoding cell envelope components. Previously published peptidoglycan- and outer membrane-related gene mutants and strains with mutations in two genes (all5045 and alr0718) encoding class B penicillin-binding proteins isolated in this work were used. Our results show that filament length is affected in most cell envelope mutants, but the filaments of alr5045 and alr2270 gene mutants were particularly fragmented. All5045 is a dd-transpeptidase involved in peptidoglycan elongation during cell growth, and Alr2270 is an enzyme involved in the biosynthesis of lipid A, a key component of lipopolysaccharide. These results indicate that both components of the cell envelope, the murein sacculus and the outer membrane, influence filamentation. As deduced from the filament fragmentation phenotypes of their mutants, however, none of these elements is as important for filamentation as the septal protein SepJ. PMID:25201945

  13. Cluster of Genes That Encode Positive and Negative Elements Influencing Filament Length in a Heterocyst-Forming Cyanobacterium

    PubMed Central

    Merino-Puerto, Victoria; Herrero, Antonia

    2013-01-01

    The filamentous, heterocyst-forming cyanobacteria perform oxygenic photosynthesis in vegetative cells and nitrogen fixation in heterocysts, and their filaments can be hundreds of cells long. In the model heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120, the genes in the fraC-fraD-fraE operon are required for filament integrity mainly under conditions of nitrogen deprivation. The fraC operon transcript partially overlaps gene all2395, which lies in the opposite DNA strand and ends 1 bp beyond fraE. Gene all2395 produces transcripts of 1.35 kb (major transcript) and 2.2 kb (minor transcript) that overlap fraE and whose expression is dependent on the N-control transcription factor NtcA. Insertion of a gene cassette containing transcriptional terminators between fraE and all2395 prevented production of the antisense RNAs and resulted in an increased length of the cyanobacterial filaments. Deletion of all2395 resulted in a larger increase of filament length and in impaired growth, mainly under N2-fixing conditions and specifically on solid medium. We denote all2395 the fraF gene, which encodes a protein restricting filament length. A FraF-green fluorescent protein (GFP) fusion protein accumulated significantly in heterocysts. Similar to some heterocyst differentiation-related proteins such as HglK, HetL, and PatL, FraF is a pentapeptide repeat protein. We conclude that the fraC-fraD-fraE?fraF gene cluster (where the arrow indicates a change in orientation), in which cis antisense RNAs are produced, regulates morphology by encoding proteins that influence positively (FraC, FraD, FraE) or negatively (FraF) the length of the filament mainly under conditions of nitrogen deprivation. This gene cluster is often conserved in heterocyst-forming cyanobacteria. PMID:23813733

  14. Cell envelope components influencing filament length in the heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120.

    PubMed

    Burnat, Mireia; Schleiff, Enrico; Flores, Enrique

    2014-12-01

    Heterocyst-forming cyanobacteria grow as chains of cells (known as trichomes or filaments) that can be hundreds of cells long. The filament consists of individual cells surrounded by a cytoplasmic membrane and peptidoglycan layers. The cells, however, share a continuous outer membrane, and septal proteins, such as SepJ, are important for cell-cell contact and filament formation. Here, we addressed a possible role of cell envelope components in filamentation, the process of producing and maintaining filaments, in the model cyanobacterium Anabaena sp. strain PCC 7120. We studied filament length and the response of the filaments to mechanical fragmentation in a number of strains with mutations in genes encoding cell envelope components. Previously published peptidoglycan- and outer membrane-related gene mutants and strains with mutations in two genes (all5045 and alr0718) encoding class B penicillin-binding proteins isolated in this work were used. Our results show that filament length is affected in most cell envelope mutants, but the filaments of alr5045 and alr2270 gene mutants were particularly fragmented. All5045 is a dd-transpeptidase involved in peptidoglycan elongation during cell growth, and Alr2270 is an enzyme involved in the biosynthesis of lipid A, a key component of lipopolysaccharide. These results indicate that both components of the cell envelope, the murein sacculus and the outer membrane, influence filamentation. As deduced from the filament fragmentation phenotypes of their mutants, however, none of these elements is as important for filamentation as the septal protein SepJ. PMID:25201945

  15. Dual stoichiometry and subunit organization in the ClpP1/P2 protease from the cyanobacterium Synechococcus elongatus

    PubMed Central

    Mikhailov, Victor A.; Ståhlberg, Frida; Clarke, Adrian K.; Robinson, Carol V.

    2015-01-01

    The Clp protease is conserved among eubacteria and most eukaryotes, and uses ATP to drive protein substrate unfolding and translocation into a chamber of sequestered proteolytic active sites. To investigate the proteolytic core of the ClpXP1/P2 protease from the cyanobacterium Synechococcus elongatus we have used a non-denaturing mass spectrometry approach. We show that the proteolytic core is a double ring tetradecamer consisting of an equal number of ClpP1 and ClpP2 subunits with masses of 21.70 and 23.44 kDa, respectively. Two stoichiometries are revealed for the heptameric rings: 4ClpP1 + 3ClpP2 and 3ClpP1 + 4ClpP2. When combined in the double ring the stoichiometries are (4ClpP1 + 3ClpP2) + (3ClpP1 + 4ClpP2) and 2 × (3ClpP1 + 4ClpP2) with a low population of a 2 × (4ClpP1 + 3ClpP2) tetradecamer. The assignment of the stoichiometries is confirmed by collision-induced dissociation of selected charge states of the intact heptamer and tetradecamer. Presence of the heterodimers, heterotetramers and heterohexamers, and absence of the mono-oligomers, in the mass spectra of the partially denatured protease indicates that the ring complex consists of a chain of ClpP1/ClpP2 heterodimers with the ring completed by an additional ClpP1 or ClpP2 subunit. PMID:26525362

  16. Differential Transcriptional Analysis of the Cyanobacterium Cyanothece sp. Strain ATCC 51142 during Light-Dark and Continuous-Light Growth

    SciTech Connect

    Toepel, Jorg; Welsh, Eric A.; Summerfield, Tina; Pakrasi, Himadri B.; Sherman, Louis A.

    2008-06-01

    We analyzed the metabolic rhythms and differential gene transcription in the unicellular, diazotrophic cyanobacterium Cyanothece sp. ATCC51142 under N?-fixing conditions with 12h light-12h dark cycles followed by 36 h continuous light. Cultures were grown in a 6-L bioreactor that was specially designed for photosynthetic microorganisms and that permitted continuous monitoring of parameters such as pH and dissolved oxygen. Our main objective was to determine the strategies used by these cells to perform N? fixation under normal day-night conditions, as well as under greater stress caused by continuous light. Our results strongly suggested that the level of N? fixation is dependent upon respiration for energy production and for removal of intracellular O?. We determined that N? fixation cycled in continuous light, but that the N? fixation peak was lower and that glycogen degradation and respiration were also lower under these conditions. We also demonstrated that nifH (the gene encoding the Fe protein) and nifB and nifX were strongly induced in the continuous light; this is consistent with the mode of operation of these proteins relative to the MoFe protein and suggested that any regulation of N? fixation was at a posttranscriptional level. Also, many soluble electron carriers (e.g., ferredoxins), as well as redox carriers (e.g., thioredoxin and glutathione) were strongly induced during N? fixation in continuous light. We suggest that these carriers were required to generate enhanced cyclic electron transport and phosphorylation for energy production and to maintain appropriate redox levels in the presence of enhanced O?, respectively.

  17. Characterization of five putative aspartate aminotransferase genes in the N2-fixing heterocystous cyanobacterium Anabaena sp. strain PCC 7120.

    PubMed

    Xu, Xinyi; Gu, Liping; He, Ping; Zhou, Ruanbao

    2015-06-01

    Aspartate and glutamate are two key amino acids used in biosynthesis of many amino acids that play vital role in cellular metabolism. Aspartate aminotransferases (AspATs) are required for channelling nitrogen (N(2)) between Glu and Asp in all life forms. Biochemical and genetic characterization of AspATs have been lacking in N(2)-fixing cyanobacteria. In this report, five putative AspAT genes (alr1039, all2340, alr2765, all4327 and alr4853) were identified in the N(2)-fixing heterocystous cyanobacterium Anabaena sp. PCC 7120. Five recombinant C-terminal hexahistidine-tagged AspATs (AspAT-H(6)) were overexpressed in Escherichia coli and purified to homogeneity. Biochemical analysis demonstrated that these five putative AspATs have authentic AspAT activity in vitro using aspartate as an amino donor. However, the enzymic activities of the five AspATs differed in vitro. Alr4853-H(6) showed the highest AspAT activity, while the enzymic activity for the other four AspATs ranged from 6.5 to 53.7?% activity compared to Alr4853 (100?%). Genetic characterization of the five AspAT genes was also performed by inactivating each individual gene. All of the five AspAT knockout mutants exhibited reduced diazotrophic growth, and alr4853 was further identified to be a Fox gene (requiring fixed N(2) for growth in the presence of oxygen). Four out of five P(aspAT)-gfp transcriptional fusions were constitutively expressed in both diazotrophic and nitrate-dependent growth conditions. Quantitative reverse transcriptase PCR showed that alr4853 expression was increased by 2.3-fold after 24?h of N(2) deprivation. Taken together, these findings add to our understanding of the role of AspATs in N(2)-fixing within heterocystous cyanobacteria. PMID:25808172

  18. The Uptake Hydrogenase in the Unicellular Diazotrophic Cyanobacterium Cyanothece sp. Strain PCC 7822 Protects Nitrogenase from Oxygen Toxicity

    PubMed Central

    Zhang, Xiaohui; Sherman, Debra M.

    2014-01-01

    Cyanothece sp. strain PCC 7822 is a unicellular, diazotrophic cyanobacterium that can produce large quantities of H2 when grown diazotrophically. This strain is also capable of genetic manipulations and can represent a good model for improving H2 production from cyanobacteria. To this end, a knockout mutation was made in the hupL gene (?hupL), and we determined how this would affect the amount of H2 produced. The ?hupL mutant demonstrated virtually no nitrogenase activity or H2 production when grown under N2-fixing conditions. To ensure that this mutation only affected the hupL gene, a complementation strain was constructed readily with wild-type properties; this indicated that the original insertion was only in hupL. The mutant had no uptake hydrogenase activity but had increased bidirectional hydrogenase (Hox) activity. Western blotting and immunocytochemistry under the electron microscope indicated that the mutant had neither HupL nor NifHDK, although the nif genes were transcribed. Interestingly, biochemical analysis demonstrated that both HupL and NifH could be membrane associated. The results indicated that the nif genes were transcribed but that NifHDK was either not translated or was translated but rapidly degraded. We hypothesized that the Nif proteins were made but were unusually susceptible to O2 damage. Thus, we grew the mutant cells under anaerobic conditions and found that they grew well under N2-fixing conditions. We conclude that in unicellular diazotrophs, like Cyanothece sp. strain PCC 7822, the HupLS complex helps remove oxygen from the nitrogenase, and that this is a more important function than merely oxidizing the H2 produced by the nitrogenase. PMID:24317398

  19. Bentazon triggers the promotion of oxidative damage in the Portuguese ricefield cyanobacterium Anabaena cylindrica: response of the antioxidant system.

    PubMed

    Galhano, Victor; Peixoto, Francisco; Gomes-Laranjo, José

    2010-10-01

    Rice fields are frequently exposed to environmental contamination by herbicides and cyanobacteria, as primary producers of these aquatic ecosystems, are adversely affected. Anabaena cylindrica is a cyanobacterium with a significantly widespread occurrence in Portuguese rice fields. This strain was studied throughout 72 h in laboratory conditions for its stress responses to sublethal concentrations (0.75-2 mM) of bentazon, a selective postemergence herbicide recommended for integrated weed management in rice, with special reference to oxidative stress, role of proline and intracellular antioxidant enzymes in herbicide-induced free radicals detoxification. Activities of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione S-transferase (GST) increased in a time- and herbicide dose-response manner and were higher than those in the control samples after 72 h. A time- and concentration-dependent increase of malondialdehyde (MDA) levels and the enhanced cell membrane leakage following bentazon exposure are indicative of lipid peroxidation, free radicals formation, and oxidative damage, while increased amounts of SOD, CAT, APX, GST, and proline indicated their involvement in free radical scavenging mechanisms. The appreciable decline in the reduced glutathione (GSH) pool after 72 h at higher bentazon concentrations could be explained by the reduction of the NADPH-dependent glutathione reductase (GR) activity. The obtained results suggested that the alterations of antioxidant systems in A. cylindrica might be useful biomarkers of bentazon exposure. As the toxic mechanism of bentazon is a complex phenomenon, this study also adds relevant findings to explain the oxidative stress pathways of bentazon promoting oxidative stress in cyanobacteria. PMID:20549627

  20. Transcriptional analysis of the unicellular, diazotrophic cyanobacterium Cyanothece sp. ATCC 51142 grown under short day/night cycles

    SciTech Connect

    Toepel, Jorg; McDermott, Jason E.; Summerfield, Tina; Sherman, Louis A.

    2009-06-01

    Cyanothece sp. strain ATCC 51142 is a unicellular, diazotrophic cyanobacterium that demonstrates extensive metabolic periodicities of photosynthesis, respiration and nitrogen fixation when grown under N2-fixing conditions. We have performed a global transcription analysis of this organism using 6 h light/dark cycles in order to determine the response of the cell to these conditions and to differentiate between diurnal and circadian regulated genes. In addition, we used a context-likelihood of relatedness (CLR) analysis with this data and those from two-day light/dark and light-dark plus continuous light experiments to better differentiate between diurnal and circadian regulated genes. Cyanothece sp. adapted in several ways to growth under short light/dark conditions. Nitrogen was fixed in every second dark period and only once in each 24 h period. Nitrogen fixation was strongly correlated to the energy status of the cells and glycogen breakdown and high respiration rates were necessary to provide appropriate energy and anoxic conditions for this process. We conclude that glycogen breakdown is a key regulatory step within these complex processes. Our results demonstrated that the main metabolic genes involved in photosynthesis, respiration, nitrogen fixation and central carbohydrate metabolism have strong (or total) circadian-regulated components. The short light/dark cycles enable us to identify transcriptional differences among the family of psbA genes, as well as the differing patterns of the hup genes, which follow the same pattern as nitrogenase genes, relative to the hox genes which displayed a diurnal, dark-dependent gene expression.

  1. Dual stoichiometry and subunit organization in the ClpP1/P2 protease from the cyanobacterium Synechococcus elongatus.

    PubMed

    Mikhailov, Victor A; Ståhlberg, Frida; Clarke, Adrian K; Robinson, Carol V

    2015-12-01

    The Clp protease is conserved among eubacteria and most eukaryotes, and uses ATP to drive protein substrate unfolding and translocation into a chamber of sequestered proteolytic active sites. To investigate the proteolytic core of the ClpXP1/P2 protease from the cyanobacterium Synechococcus elongatus we have used a non-denaturing mass spectrometry approach. We show that the proteolytic core is a double ring tetradecamer consisting of an equal number of ClpP1 and ClpP2 subunits with masses of 21.70 and 23.44kDa, respectively. Two stoichiometries are revealed for the heptameric rings: 4ClpP1+3ClpP2 and 3ClpP1+4ClpP2. When combined in the double ring the stoichiometries are (4ClpP1+3ClpP2)+(3ClpP1+4ClpP2) and 2×(3ClpP1+4ClpP2) with a low population of a 2×(4ClpP1+3ClpP2) tetradecamer. The assignment of the stoichiometries is confirmed by collision-induced dissociation of selected charge states of the intact heptamer and tetradecamer. Presence of the heterodimers, heterotetramers and heterohexamers, and absence of the mono-oligomers, in the mass spectra of the partially denatured protease indicates that the ring complex consists of a chain of ClpP1/ClpP2 heterodimers with the ring completed by an additional ClpP1 or ClpP2 subunit. PMID:26525362

  2. Comparative genomics reveals diversified CRISPR-Cas systems of globally distributed Microcystis aeruginosa, a freshwater bloom-forming cyanobacterium

    PubMed Central

    Yang, Chen; Lin, Feibi; Li, Qi; Li, Tao; Zhao, Jindong

    2015-01-01

    Microcystis aeruginosa is one of the most common and dominant bloom-forming cyanobacteria in freshwater lakes around the world. Microcystis cells can produce toxic secondary metabolites, such as microcystins, which are harmful to human health. Two M. aeruginosa strains were isolated from two highly eutrophic lakes in China and their genomes were sequenced. Comparative genomic analysis was performed with the 12 other available M. aeruginosa genomes and closely related unicellular cyanobacterium. Each genome of M. aeruginosa containing at least one clustered regularly interspaced short palindromic repeat (CRISPR) locus and total 71 loci were identified, suggesting it is ubiquitous in M. aeruginosa genomes. In addition to the previously reported subtype I-D cas gene sets, three CAS subtypes I-A, III-A and III-B were identified and characterized in this study. Seven types of CRISPR direct repeat have close association with CAS subtype, confirming that different and specific secondary structures of CRISPR repeats are important for the recognition, binding and process of corresponding cas gene sets. Homology search of the CRISPR spacer sequences provides a history of not only resistance to bacteriophages and plasmids known to be associated with M. aeruginosa, but also the ability to target much more exogenous genetic material in the natural environment. These adaptive and heritable defense mechanisms play a vital role in keeping genomic stability and self-maintenance by restriction of horizontal gene transfer. Maintaining genomic stability and modulating genomic plasticity are both important evolutionary strategies for M. aeruginosa in adaptation and survival in various habitats. PMID:26029174

  3. Optimization of Metabolic Capacity and Flux through Environmental Cues To Maximize Hydrogen Production by the Cyanobacterium “Arthrospira (Spirulina) maxima”? †

    PubMed Central

    Ananyev, Gennady; Carrieri, Damian; Dismukes, G. Charles

    2008-01-01

    Environmental and nutritional conditions that optimize the yield of hydrogen (H2) from water using a two-step photosynthesis/fermentation (P/F) process are reported for the hypercarbonate-requiring cyanobacterium “Arthrospira maxima.” Our observations lead to four main conclusions broadly applicable to fermentative H2 production by bacteria: (i) anaerobic H2 production in the dark from whole cells catalyzed by a bidirectional [NiFe] hydrogenase is demonstrated to occur in two temporal phases involving two distinct metabolic processes that are linked to prior light-dependent production of NADPH (photosynthetic) and dark/anaerobic production of NADH (fermentative), respectively; (ii) H2 evolution from these reductants represents a major pathway for energy production (ATP) during fermentation by regenerating NAD+ essential for glycolysis of glycogen and catabolism of other substrates; (iii) nitrate removal during fermentative H2 evolution is shown to produce an immediate and large stimulation of H2, as nitrate is a competing substrate for consumption of NAD(P)H, which is distinct from its slower effect of stimulating glycogen accumulation; (iv) environmental and nutritional conditions that increase anaerobic ATP production, prior glycogen accumulation (in the light), and the intracellular reduction potential (NADH/NAD+ ratio) are shown to be the key variables for elevating H2 evolution. Optimization of these conditions and culture age increases the H2 yield from a single P/F cycle using concentrated cells to 36 ml of H2/g (dry weight) and a maximum 18% H2 in the headspace. H2 yield was found to be limited by the hydrogenase-mediated H2 uptake reaction. PMID:18676712

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

    NASA Astrophysics Data System (ADS)

    Swanner, Elizabeth; Wu, Wenfang; Hao, Likai; Wuestner, Marina; Obst, Martin; Moran, Dawn; McIlvin, Matthew; Saito, Mak; Kappler, Andreas

    2015-10-01

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

  5. Structural and functional characterization of a macrophage migration inhibitory factor homologue from the marine cyanobacterium Prochlorococcus marinus .

    PubMed

    Wasiel, Anna A; Rozeboom, Henriëtte J; Hauke, Doreen; Baas, Bert-Jan; Zandvoort, Ellen; Quax, Wim J; Thunnissen, Andy-Mark W H; Poelarends, Gerrit J

    2010-09-01

    Macrophage migration inhibitory factor (MIF) is a multifunctional mammalian cytokine, which exhibits tautomerase and oxidoreductase activity. MIF homologues with pairwise sequence identities to human MIF ranging from 31% to 41% have been detected in various cyanobacteria. The gene encoding the MIF homologue from the marine cyanobacterium Prochlorococcus marinus strain MIT9313 has been cloned and the corresponding protein (PmMIF) overproduced, purified, and subjected to functional and structural characterization. Kinetic and (1)H NMR spectroscopic studies show that PmMIF tautomerizes phenylenolpyruvate and (p-hydroxyphenyl)enolpyruvate at low levels. The N-terminal proline of PmMIF is critical for these reactions because the P1A mutant has strongly reduced tautomerase activities. PmMIF shows high structural homology with mammalian MIFs as revealed by a crystal structure of PmMIF at 1.63 A resolution. MIF contains a Cys-X-X-Cys motif that mediates oxidoreductase activity, which is lacking from PmMIF. Engineering of the motif into PmMIF did not result in oxidoreductase activity but increased the tautomerase activity 8-fold. The shared tautomerase activities and the conservation of the beta-alpha-beta structural fold and key functional groups suggest that eukaryotic MIFs and cyanobacterial PmMIF are related by divergent evolution from a common ancestor. While several MIF homologues have been identified in eukaryotic parasites, where they are thought to play a role in modulating the host immune response, PmMIF is the first nonparasitic, bacterial MIF-like protein characterized in detail. This work sets the stage for future studies which could address the question whether a MIF-like protein from a free-living bacterium possesses immunostimulatory features similar to those of mammalian MIFs and MIF-like proteins found in parasitic nematodes and protozoa. PMID:20715791

  6. Harvesting Far-Red Light by Chlorophyll f in Photosystems I and II of Unicellular Cyanobacterium strain KC1.

    PubMed

    Itoh, Shigeru; Ohno, Tomoki; Noji, Tomoyasu; Yamakawa, Hisanori; Komatsu, Hirohisa; Wada, Katsuhiro; Kobayashi, Masami; Miyashita, Hideaki

    2015-10-01

    Cells of a unicellular cyanobacterium strain KC1, which were collected from Japanese fresh water Lake Biwa, formed chlorophyll (Chl) f at 6.7%, Chl a' at 2.0% and pheophytin a at 0.96% with respect to Chl a after growth under 740 nm light. The far-red-acclimated cells (Fr cells) formed extra absorption bands of Chl f at 715 nm in addition to the major Chl a band. Fluorescence lifetimes were measured. The 405-nm laser flash, which excites mainly Chl a in photosystem I (PSI), induced a fast energy transfer to multiple fluorescence bands at 720-760 and 805 nm of Chl f at 77 K in Fr cells with almost no PSI-red-Chl a band. The 630-nm laser flash, which mainly excited photosystem II (PSII) through phycocyanin, revealed fast energy transfer to another set of Chl f bands at 720-770 and 810 nm as well as to the 694-nm Chl a fluorescence band. The 694-nm band did not transfer excitation energy to Chl f. Therefore, Chl a in PSI, and phycocyanin in PSII of Fr cells transferred excitation energy to different sets of Chl f molecules. Multiple Chl f forms, thus, seem to work as the far-red antenna both in PSI and PSII. A variety of cyanobacterial species, phylogenically distant from each other, seems to use a Chl f antenna in far-red environments, such as under dense biomats, in colonies, or under far-red LED light. PMID:26320210

  7. Changes in primary metabolism under light and dark conditions in response to overproduction of a response regulator RpaA in the unicellular cyanobacterium Synechocystis sp. PCC 6803

    PubMed Central

    Iijima, Hiroko; Shirai, Tomokazu; Okamoto, Mami; Kondo, Akihiko; Hirai, Masami Yokota; Osanai, Takashi

    2015-01-01

    The study of the primary metabolism of cyanobacteria in response to light conditions is important for environmental biology because cyanobacteria are widely distributed among various ecological niches. Cyanobacteria uniquely possess circadian rhythms, with central oscillators consisting from three proteins, KaiA, KaiB, and KaiC. The two-component histidine kinase SasA/Hik8 and response regulator RpaA transduce the circadian signal from KaiABC to control gene expression. Here, we generated a strain overexpressing rpaA in a unicellular cyanobacterium Synechocystis sp. PCC 6803. The rpaA-overexpressing strain showed pleiotropic phenotypes, including slower growth, aberrant degradation of an RNA polymerase sigma factor SigE after the light-to-dark transition, and higher accumulation of sugar catabolic enzyme transcripts under dark conditions. Metabolome analysis revealed delayed glycogen degradation, decreased sugar phosphates and organic acids in the tricarboxylic acid cycle, and increased amino acids under dark conditions. The current results demonstrate that in this cyanobacterium, RpaA is a regulator of primary metabolism and involved in adaptation to changes in light conditions. PMID:26379657

  8. Inactivation of agmatinase expressed in vegetative cells alters arginine catabolism and prevents diazotrophic growth in the heterocyst-forming cyanobacterium Anabaena.

    PubMed

    Burnat, Mireia; Flores, Enrique

    2014-10-01

    Arginine decarboxylase produces agmatine, and arginase and agmatinase are ureohydrolases that catalyze the production of ornithine and putrescine from arginine and agmatine, respectively, releasing urea. In the genome of the filamentous, heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120, ORF alr2310 putatively encodes an ureohydrolase. Cells of Anabaena supplemented with [(14) C]arginine took up and catabolized this amino acid generating a set of labeled amino acids that included ornithine, proline, and glutamate. In an alr2310 deletion mutant, an agmatine spot appeared and labeled glutamate increased with respect to the wild type, suggesting that Alr2310 is an agmatinase rather than an arginase. As determined in cell-free extracts, agmatinase activity could be detected in the wild type but not in the mutant. Thus, alr2310 is the Anabaena speB gene encoding agmatinase. The ?alr2310 mutant accumulated large amounts of cyanophycin granule polypeptide, lacked nitrogenase activity, and did not grow diazotrophically. Growth tests in solid media showed that agmatine is inhibitory for Anabaena, especially under diazotrophic conditions, suggesting that growth of the mutant is inhibited by non-metabolized agmatine. Measurements of incorporation of radioactivity from [(14) C]leucine into macromolecules showed, however, a limited inhibition of protein synthesis in the ?alr2310 mutant. Analysis of an Anabaena strain producing an Alr2310-GFP (green fluorescent protein) fusion showed expression in vegetative cells but much less in heterocysts, implying compartmentalization of the arginine decarboxylation pathway in the diazotrophic filaments of this heterocyst-forming cyanobacterium. PMID:25209059

  9. Inactivation of agmatinase expressed in vegetative cells alters arginine catabolism and prevents diazotrophic growth in the heterocyst-forming cyanobacterium Anabaena

    PubMed Central

    Burnat, Mireia; Flores, Enrique

    2014-01-01

    Arginine decarboxylase produces agmatine, and arginase and agmatinase are ureohydrolases that catalyze the production of ornithine and putrescine from arginine and agmatine, respectively, releasing urea. In the genome of the filamentous, heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120, ORF alr2310 putatively encodes an ureohydrolase. Cells of Anabaena supplemented with [14C]arginine took up and catabolized this amino acid generating a set of labeled amino acids that included ornithine, proline, and glutamate. In an alr2310 deletion mutant, an agmatine spot appeared and labeled glutamate increased with respect to the wild type, suggesting that Alr2310 is an agmatinase rather than an arginase. As determined in cell-free extracts, agmatinase activity could be detected in the wild type but not in the mutant. Thus, alr2310 is the Anabaena speB gene encoding agmatinase. The ?alr2310 mutant accumulated large amounts of cyanophycin granule polypeptide, lacked nitrogenase activity, and did not grow diazotrophically. Growth tests in solid media showed that agmatine is inhibitory for Anabaena, especially under diazotrophic conditions, suggesting that growth of the mutant is inhibited by non-metabolized agmatine. Measurements of incorporation of radioactivity from [14C]leucine into macromolecules showed, however, a limited inhibition of protein synthesis in the ?alr2310 mutant. Analysis of an Anabaena strain producing an Alr2310-GFP (green fluorescent protein) fusion showed expression in vegetative cells but much less in heterocysts, implying compartmentalization of the arginine decarboxylation pathway in the diazotrophic filaments of this heterocyst-forming cyanobacterium. PMID:25209059

  10. Nitrate and amino acid availability affects glycine betaine and mycosporine-2-glycine in response to changes of salinity in a halotolerant cyanobacterium Aphanothece halophytica.

    PubMed

    Waditee-Sirisattha, Rungaroon; Kageyama, Hakuto; Fukaya, Minoru; Rai, Vandna; Takabe, Teruhiro

    2015-12-01

    A halotolerant cyanobacterium Aphanothece halophytica thrives in extreme salinity with accumulation of a potent osmoprotectant glycine betaine. Recently, this cyanobacterium was shown to accumulate sunscreen molecule mycosporine-2-glycine significantly at high salinity. In this study, we investigated effects of nitrate and amino acid provision on the accumulation of glycine betaine and mycosporine-2-glycine. With elevated nitrate concentrations at high salinity, intracellular levels of both metabolites were enhanced. Six-fold high nitrate concentration increased the relative amounts of glycine betaine and mycosporine-2-glycine to be 1.5 and 2.0 folds compared with control condition : Increased levels were time- and dose-dependent manner. Exogenous supply of glycine/serine at high salinity resulted in the similar trends as observed in excess nitrate experiment. Intracellular level of glycine betaine increased ?1.6 folds with glycine/serine supplementation. These supplementations also caused the increased level of mycosporine-2-glycine, namely 1.4 and 2 folds by glycine and serine, respectively. The transcription of glycine betaine and mycosporine-2-glycine biosynthetic genes was strongly induced under high-nitrate-salt condition. These results suggest the dependence of glycine betaine and mycosporine-2-glycine productions on substrate availability, and the effect of nitrate was possibly associated with stimulation of osmoprotectant increment in this extremophile. PMID:26474598

  11. Red-shifted red/green-type cyanobacteriochrome AM1_1870g3 from the chlorophyll d-bearing cyanobacterium Acaryochloris marina.

    PubMed

    Narikawa, Rei; Fushimi, Keiji; Ni-Ni-Win; Ikeuchi, Masahiko

    2015-05-29

    Cyanobacteriochromes (CBCRs) are diverse photoreceptors that are found only from cyanobacteria and cover wide range of light qualities. CBCRs are divided into two types regarding the chromophore species they contain: phycocyanobilin (PCB) and phycoviolobilin. Red/green-type CBCRs are widely distributed subfamily among the PCB-binding CBCRs and photoconvert between a red-absorbing thermostable form and a green-absorbing metastable form. Our recent study discovered that a red/green-type CBCR, AM1_1557g2, from a cyanobacterium Acaryochloris marina covalently binds not only PCB but also biliverdin (BV). BV-binding AM1_1557g2 photoconverts between a far-red absorbing form and an orange-absorbing form. We report, herein, that another red/green-type CBCR, AM1_1870g3, from the cyanobacterium A. marina also bound both PCB and BV. PCB- and BV-binding ones showed red/green and far-red/orange reversible photoconversions, respectively. Unexpectedly, absorbing wavelengths are 10-20 nm red-shifted compared with those of AM1_1557g2. These red-shifted characteristics may be useful for optogenetic light switches that work in various organisms. PMID:25892514

  12. Antagonism at combined effects of chemical fertilizers and carbamate insecticides on the rice-field N2-fixing cyanobacterium Cylindrospermum sp. in vitro

    PubMed Central

    Nayak, Nabakishore; Rath, Shakti

    2014-01-01

    Effects of chemical fertilizers (urea, super phosphate and potash) on toxicities of two carbamate insecticides, carbaryl and carbofuran, individually to the N2-fixing cyanobacterium, Cylindrospermum sp. were studied in vitro at partially lethal levels (below highest permissive concentrations) of each insecticide. The average number of vegetative cells between two polar heterocysts was 16.3 in control cultures, while the mean value of filament length increased in the presence of chemical fertilizers, individually. Urea at the 10 ppm level was growth stimulatory and at the 50 ppm level it was growth inhibitory in control cultures, while at 100 ppm it was antagonistic, i.e. toxicity-enhancing along with carbaryl, individually to the cyanobacterium, antagonism was recorded. Urea at 50 ppm had toxicity reducing effect with carbaryl or carbofuran. At 100 and 250 ppm carbofuran levels, 50 ppm urea only had a progressive growth enhancing effect, which was marked well at 250 ppm carbofuran level, a situation of synergism. Super phosphate at the 10 ppm level only was growth promoting in control cultures, but it was antagonistic at its higher levels (50 and 100 ppm) along with both insecticides, individually. Potash (100, 200, 300 and 400 ppm) reduced toxicity due to carbaryl 20 and carbofuran 250 ppm levels, but potash was antagonistic at the other insecticide levels. The data clearly showed that the chemical fertilizers used were antagonistic with both the insecticides during toxicity to Cylindrospermum sp. PMID:26038669

  13. Insights into the Physiology and Ecology of the Brackish-Water-Adapted Cyanobacterium Nodularia spumigena CCY9414 Based on a Genome-Transcriptome Analysis

    PubMed Central

    Voß, Björn; Bolhuis, Henk; Fewer, David P.; Kopf, Matthias; Möke, Fred; Haas, Fabian; El-Shehawy, Rehab; Hayes, Paul; Bergman, Birgitta; Sivonen, Kaarina; Dittmann, Elke; Scanlan, Dave J.; Hagemann, Martin; Stal, Lucas J.; Hess, Wolfgang R.

    2013-01-01

    Nodularia spumigena is a filamentous diazotrophic cyanobacterium that dominates the annual late summer cyanobacterial blooms in the Baltic Sea. But N. spumigena also is common in brackish water bodies worldwide, suggesting special adaptation allowing it to thrive at moderate salinities. A draft genome analysis of N. spumigena sp. CCY9414 yielded a single scaffold of 5,462,271 nucleotides in length on which genes for 5,294 proteins were annotated. A subsequent strand-specific transcriptome analysis identified more than 6,000 putative transcriptional start sites (TSS). Orphan TSSs located in intergenic regions led us to predict 764 non-coding RNAs, among them 70 copies of a possible retrotransposon and several potential RNA regulators, some of which are also present in other N2-fixing cyanobacteria. Approximately 4% of the total coding capacity is devoted to the production of secondary metabolites, among them the potent hepatotoxin nodularin, the linear spumigin and the cyclic nodulapeptin. The transcriptional complexity associated with genes involved in nitrogen fixation and heterocyst differentiation is considerably smaller compared to other Nostocales. In contrast, sophisticated systems exist for the uptake and assimilation of iron and phosphorus compounds, for the synthesis of compatible solutes, and for the formation of gas vesicles, required for the active control of buoyancy. Hence, the annotation and interpretation of this sequence provides a vast array of clues into the genomic underpinnings of the physiology of this cyanobacterium and indicates in particular a competitive edge of N. spumigena in nutrient-limited brackish water ecosystems. PMID:23555932

  14. Persistent phytoplankton bloom in Lake St. Lucia (iSimangaliso Wetland Park, South Africa) caused by a cyanobacterium closely associated with the genus Cyanothece (Synechococcaceae, Chroococcales).

    PubMed

    Muir, David G; Perissinotto, Renzo

    2011-09-01

    Lake St. Lucia, iSimangaliso Wetland Park, South Africa, is the largest estuarine lake in Africa. Extensive use and manipulation of the rivers flowing into it have reduced freshwater inflow, and the lake has also been subject to a drought of 10 years. For much of this time, the estuary has been closed to the Indian Ocean, and salinities have progressively risen throughout the system, impacting the biotic components of the ecosystem, reducing zooplankton and macrobenthic biomass and diversity in particular. In June 2009, a bloom of a red/orange planktonic microorganism was noted throughout the upper reaches of Lake St. Lucia. The bloom persisted for at least 18 months, making it the longest such bloom on record. The causative organism was characterized by light and electron microscopy and by 16S rRNA sequencing and was shown to be a large, unicellular cyanobacterium most strongly associated with the genus Cyanothece. The extent and persistence of the bloom appears to be unique to Lake St. Lucia, and it is suggested that the organism's resistance to high temperatures, to intense insolation, and to hypersalinity as well as the absence of grazing pressure by salinity-sensitive zooplankton all contributed to its persistence as a bloom organism until a freshwater influx, due to exceptionally heavy summer rains in 2011, reduced the salinity for a sufficient length of time to produce a crash in the cyanobacterium population as a complex, low-salinity biota redeveloped. PMID:21742912

  15. Elucidation of Insertion Elements Carried on Plasmids and In Vitro Construction of Shuttle Vectors from the Toxic Cyanobacterium Planktothrix

    PubMed Central

    Christiansen, Guntram; Goesmann, Alexander

    2014-01-01

    Several gene clusters that are responsible for toxin synthesis in bloom-forming cyanobacteria have been found to be associated with transposable elements (TEs). In particular, insertion sequence (IS) elements were shown to play a role in the inactivation or recombination of the genes responsible for cyanotoxin synthesis. Plasmids have been considered important vectors of IS element distribution to the host. In this study, we aimed to elucidate the IS elements propagated on the plasmids and the chromosome of the toxic cyanobacterium Planktothrix agardhii NIVA-CYA126/8 by means of high-throughput sequencing. In total, five plasmids (pPA5.5, pPA14, pPA50, pPA79, and pPA115, of 5, 6, 50, 79, and 120 kbp, respectively) were elucidated, and two plasmids (pPA5.5, pPA115) were found to propagate full IS element copies. Large stretches of shared DNA information between plasmids were constituted of TEs. Two plasmids (pPA5.5, pPA14) were used as candidates to engineer shuttle vectors (named pPA5.5SV and pPA14SV, respectively) in vitro by PCR amplification and the subsequent transposition of the Tn5 cat transposon containing the R6K? origin of replication of Escherichia coli. While pPA5.5SV was found to be fully segregated, pPA14SV consistently co-occurred with its wild-type plasmid even under the highest selective pressure. Interestingly, the Tn5 cat transposon became transferred by homologous recombination into another plasmid, pPA50. The availability of shuttle vectors is considered to be of relevance in investigating genome plasticity as a consequence of homologous recombination events. Combining the potential of high-throughput sequencing and in vitro production of shuttle vectors makes it simple to produce species-specific shuttle vectors for many cultivable prokaryotes. PMID:24907328

  16. Proteomic Analysis of the Marine Cyanobacterium Synechococcus WH8102 and Implications for Estimates of the Cellular Iron Content

    NASA Astrophysics Data System (ADS)

    Saito, M. A.; Bertrand, E. M.; Bulygin, V.; Moran, D.; Waterbury, J. B.

    2008-12-01

    The proteome of the marine cyanobacterium Synechococcus WH8102 was analyzed by nanospray liquid chromatography mass spectrometry (nLC-MS) with two major goals: to provide a first examination of the relative abundance of the most abundant proteins in this important microbe and to provide the necessary mass spectra for future quantification of biogeochemically significant proteins. Analyses of 37 nLC-MS runs of whole cell tryptic digestions and SDS-PAGE gel separated tryptic digestions resulted in a total of 636 proteins identified, 376 identified with two or more tryptic peptides. The identifications used the Sequest algorithm with stringent data filters on 54003 observed peptides, 3066 of which were unique, with a false positive rate of 2.2%. These measured proteins represent ~ 25.2% (14.8% with >= 2 peptides) of the open reading frames (ORFs) in the genome, similar to or higher than the percentage found in other cyanobacterial proteome studies thus far. The relative abundance of the more abundant proteins in the proteome was examined using the exponentially modified protein abundance index from a single nLC-MS run that identified 372 proteins (14.7% of the ORFs) from 7743 observed peptides (1224 unique peptides). Estimates of the relative abundance showed the photosynthesis and respiration category contributing approximately 32% of the total detected protein, hypothetical proteins contributing about 16%, and translation about 12%. Of biogeochemical interest, multiple types of nitrogen assimilation systems were observed to be simultaneously expressed as proteins, only 5 of the 21 B12 biosynthesis proteins were identified likely due to low abundance, and the metalloproteins metallothionein and nickel superoxide dismutase were relatively abundant. In contrast to previous predictions of a high photosystem I: photosystem II ratio of approximately 3 in the cyanobacteria and a resultant high cellular iron content, the ratio of the average relative abundances of all detected proteins in each photosystem was only 1.2, and the median was only 0.72 based on the median. These results contradict the earlier predication of a biochemical basis for a high cellular iron in Synechococcus and may extend to the marine cyanobacteria in general.

  17. Fluorescence induction in the phycobilisome-containing cyanobacterium Synechococcus sp PCC 7942: analysis of the slow fluorescence transient.

    PubMed

    Stamatakis, Kostas; Tsimilli-Michael, Merope; Papageorgiou, George C

    2007-06-01

    At room temperature, the chlorophyll (Chl) a fluorescence induction (FI) kinetics of plants, algae and cyanobacteria go through two maxima, P at approximately 0.2-1 and M at approximately 100-500 s, with a minimum S at approximately 2-10 s in between. Thus, the whole FI kinetic pattern comprises a fast OPS transient (with O denoting origin) and a slower SMT transient (with T denoting terminal state). Here, we examined the phenomenology and the etiology of the SMT transient of the phycobilisome (PBS)-containing cyanobacterium Synechococcus sp PCC 7942 by modifying PBS-->Photosystem (PS) II excitation transfer indirectly, either by blocking or by maximizing the PBS-->PS I excitation transfer. Blocking the PBS-->PS I excitation transfer route with N-ethyl-maleimide [NEM; A. N. Glazer, Y. Gindt, C. F. Chan, and K.Sauer, Photosynth. Research 40 (1994) 167-173] increases both the PBS excitation share of PS II and Chl a fluorescence. Maximizing it, on the other hand, by suspending cyanobacterial cells in hyper-osmotic media [G. C. Papageorgiou, A. Alygizaki-Zorba, Biochim. Biophys. Acta 1335 (1997) 1-4] diminishes both the PBS excitation share of PS II and Chl a fluorescence. Here, we show for the first time that, in either case, the slow SMT transient of FI disappears and is replaced by continuous P-->T fluorescence decay, reminiscent of the typical P-->T fluorescence decay of higher plants and algae. A similar P-->T decay was also displayed by DCMU-treated Synechococcus cells at 2 degrees C. To interpret this phenomenology, we assume that after dark adaptation cyanobacteria exist in a low fluorescence state (state 2) and transit to a high fluorescence state (state 1) when, upon light acclimation, PS I is forced to run faster than PS II. In these organisms, a state 2-->1 fluorescence increase plus electron transport-dependent dequenching processes dominate the SM rise and maximal fluorescence output is at M which lies above the P maximum of the fast FI transient. In contrast, dark-adapted plants and algae exist in state 1 and upon illumination they display an extended P-->T decay that sometimes is interrupted by a shallow SMT transient, with M below P. This decay is dominated by a state 1-->2 fluorescence lowering, as well as by electron transport-dependent quenching processes. When the regulation of the PBS-->PS I electronic excitation transfer is eliminated (as for example in hyper-osmotic suspensions, after NEM treatment and at low temperature), the FI pattern of Synechococcus becomes plant-like. PMID:17448439

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

    NASA Astrophysics Data System (ADS)

    Morin, Nicolas

    The MELGEN activity (MELiSSA Genetic Stability Study) mainly covers the molecular aspects of the regenerative life-support system MELiSSA (Micro-Ecological Life Support System Alternative) of the European Space Agency (ESA). The general objective of MELGEN is to establish and validate methods and the related hardware in order to detect genetic instability and microbial contaminants in the MELISSA compartments. This includes (1) a genetic description of the MELISSA strains, (2) studies of microbial behavior and genetic stability in bioreactors and (3) the detection of chemical, genetical and biological contamination and their effect on microbial metabolism. Selected as oxygen producer and complementary food source, the cyanobacterium Arthrospira sp. PCC8005 plays a major role within the MELiSSA loop. As the genomic information on this organism was insufficient, sequencing of its genome was proposed at the French National Sequencing Center, Genoscope, as a joint effort between ESA and different laboratories. So far, a preliminary assembly of 16 contigs representing circa 6.3 million basepairs was obtained. Even though the finishing of the genome is on its way, automatic annotation of the contigs has already been performed on the MaGe annotation platform, and curation of the sequence is currently being carried out, with a special focus on biosynthesis pathways, photosynthesis, and maintenance processes of the cell. According to the index of repetitiveness described by Haubold and Wiehe (2006), we discovered that the genome of Arthrospira sp. is among the 50 most repeated bacterial genomes sequenced to date. Thanks to the sequencing project, we have identified and catalogued mobile genetics elements (MGEs) dispersed throughout the unique chromosome of this cyanobacterium. They represent a quite large proportion of the genome, as genes identified as putative transposases are indeed found in circa 5 Results : We currently have a first draft of the complete genome of Arthrospira sp. PCC 8005, fully annotated. This genomic information opens the gates to a better understanding of the biology of this cyanobacterium and will be a key to the development of appropriate derivatives that provide enhanced performances (e.g. radiation resistance, genetic stability, photosynthesis and nutritive properties).

  19. Identification of Specific Variations in a Non-Motile Strain of Cyanobacterium Synechocystis sp. PCC 6803 Originated from ATCC 27184 by Whole Genome Resequencing

    PubMed Central

    Ding, Qinglong; Chen, Gu; Wang, Yuling; Wei, Dong

    2015-01-01

    Cyanobacterium Synechocystis sp. PCC 6803 is a widely used model organism in basic research and biofuel biotechnology application. Here, we report the genomic sequence of chromosome and seven plasmids of a glucose-tolerant, non-motile strain originated from ATCC 27184, GT-G, in use at Guangzhou. Through high-throughput genome re-sequencing and verification by Sanger sequencing, eight novel variants were identified in its chromosome and plasmids. The eight novel variants, especially the five non-silent mutations might have interesting effects on the phenotype of GT-G strains, for example the truncated Sll1895 and Slr0322 protein. These resequencing data provide background information for further research and application based on the GT-G strain and also provide evidence to study the evolution and divergence of Synechocystis 6803 globally. PMID:26473841

  20. Investigation and modeling of biomass decay rate in the dark and its potential influence on net productivity of solar photobioreactors for microalga Chlamydomonas reinhardtii and cyanobacterium Arthrospira platensis.

    PubMed

    Le Borgne, François; Pruvost, Jérémy

    2013-06-01

    Biomass decay rate (BDR) in the dark was investigated for Chlamydomonas reinhardtii (microalga) and Arthrospira platensis (cyanobacterium). A specific setup based on a torus photobioreactor with online gas analysis was validated, enabling us to follow the time course of the specific BDR using oxygen monitoring and mass balance. Various operating parameters that could limit respiration rates, such as culture temperature and oxygen deprivation, were then investigated. C. reinhardtii was found to present a higher BDR in the dark than A. platensis, illustrating here the difference between eukaryotic and prokaryotic cells. In both cases, temperature proved an influential parameter, and the Arrhenius law was found to efficiently relate specific BDR to culture temperature. The utility of decreasing temperature at night to increase biomass productivity in a solar photobioreactor is also illustrated. PMID:23619140

  1. Regulation of Genes Involved in Heterocyst Differentiation in the Cyanobacterium Anabaena sp. Strain PCC 7120 by a Group 2 Sigma Factor SigC

    PubMed Central

    Ehira, Shigeki; Miyazaki, Shogo

    2015-01-01

    The filamentous cyanobacterium Anabaena sp. strain PCC 7120 differentiates specialized cells for nitrogen fixation called heterocysts upon limitation of combined nitrogen in the medium. During heterocyst differentiation, expression of approximately 500 genes is upregulated with spatiotemporal regulation. In the present study, we investigated the functions of sigma factors of RNA polymerase in the regulation of heterocyst differentiation. The transcript levels of sigC, sigE, and sigG were increased during heterocyst differentiation, while expression of sigJ was downregulated. We carried out DNA microarray analysis to identify genes regulated by SigC, SigE, and SigG. It was indicated that SigC regulated the expression of genes involved in heterocyst differentiation and functions. Moreover, genes regulated by SigC partially overlapped with those regulated by SigE, and deficiency of SigC was likely to be compensated by SigE. PMID:25692906

  2. Severe hepatotoxicity caused by the tropical cyanobacterium (blue-green alga) Cylindrospermopsis raciborskii (Woloszynska) Seenaya and Subba Raju isolated from a domestic water supply reservoir.

    PubMed Central

    Hawkins, P R; Runnegar, M T; Jackson, A R; Falconer, I R

    1985-01-01

    Cylindrospermopsis raciborskii, a tropical blooming species of cyanobacterium (blue-green alga), was isolated from the domestic water supply reservoir on Palm Island, a continental island off the tropical northeast coast of Australia. This species, not previously known to be toxic, was shown to be severely hepatotoxic for mice. The 50% lethal dose at 24 h after injection was found to be 64 +/- 5 mg of freeze-dried culture per kg of mouse. The principal lesion produced was centrilobular to massive hepatocyte necrosis, but various degrees of injury were also seen in the kidneys, adrenal glands, lungs, and intestine. The possible implication of this finding in relation to an incident of hepatoenteritis in humans living on the island is discussed. Images PMID:3937492

  3. Two Cytotoxic Stereoisomers of Malyngamide C, 8-Epi-Malyngamide C and 8-O-Acetyl-8-epi-Malyngamide C, from the Marine Cyanobacterium Lyngbya majuscula

    PubMed Central

    Gross, Harald; McPhail, Kerry L.; Goeger, Douglas E.; Valeriote, Frederick A.; Gerwick, William H.

    2010-01-01

    Two new epimers of malyngamide C, 8-O-acetyl-8-epi-malyngamide C (1) and 8-epi-malyngamide C (3) have been isolated along with known compounds 6-O-acetylmalyngamide F (5), H (6), J (7) K (8), and characterized from a Grenada field collection of the marine cyanobacterium Lyngbya majuscula. The planar structures of these compounds were deduced by 1D- and 2D-NMR and mass spectral data interpretation. The absolute configurations were determined by a combination of CD-spectroscopy, chemical degradation and the variable temperature Mosher’s method. Compounds 1–5, 7 and 8 displayed moderate cytotoxicity to NCI-H460 human lung tumor and neuro-2a cancer cell lines, with IC50 values ranging between 0.5 and 20 ?g/mL. PMID:20701935

  4. Efficiency of Photosynthesis in a Chl d-Utilizing Cyanobacterium is Comparable to or Higher than that in Chl a-Utilizing Oxygenic Species

    NASA Technical Reports Server (NTRS)

    Mielke, S. P.; Kiang, N. Y.; Blankenship, R. E.; Gunner, M. R.; Mauzerall, D.

    2011-01-01

    The cyanobacterium Acaryochloris marina uses chlorophyll d to carry out oxygenic photosynthesis in environments depleted in visible and enhanced in lower-energy, far-red light. However, the extent to which low photon energies limit the efficiency of oxygenic photochemistry in A. marina is not known. Here, we report the first direct measurements of the energy-storage efficiency of the photosynthetic light reactions in A. marina whole cells,and find it is comparable to or higher than that in typical, chlorophyll a-utilizing oxygenic species. This finding indicates that oxygenic photosynthesis is not fundamentally limited at the photon energies employed by A. marina, and therefore is potentially viable in even longer-wavelength light environments.

  5. Symplocin A, a Linear Peptide from the Bahamian Cyanobacterium Symploca sp. Configurational Analysis of N,N-Dimethylamino Acids by Chiral-Phase HPLC of Naphthacyl Esters†

    PubMed Central

    Molinski, Tadeusz F.; Reynolds, Kirk A.; Morinaka, Brandon I.

    2012-01-01

    The absolute stereostructures of the components of symplocin A (3), a new N,N-dimethyl-terminated peptide from the Bahamian cyanobacterium, Symploca sp., were assigned from spectroscopic analysis, including MS and 2D NMR and Marfey’s analysis. The complete absolute configuration of symplocin A, including the unexpected D-configurations of the terminal N,N-dimethylisoleucine and valic acid residues, were assigned by chiral-phase HPLC of the corresponding 2-naphthacyl esters, a highly sensitive, complementary strategy for assignment of N-blocked peptide residues where Marfey’s method is ineffectual, or other methods fall short. Symplocin A exhibited potent activity as an inhibitor of cathepsin E (IC50 300 pM). PMID:22360587

  6. ?pH-dependent non-photochemical quenching (qE) of excited chlorophylls in the photosystem II core complex of the freshwater cyanobacterium Synechococcus sp PCC 7942.

    PubMed

    Stamatakis, Kostas; Papageorgiou, George C

    2014-08-01

    Light-induced and lumen acidity-dependent quenching (qE) of excited chlorophylls (Chl) in vivo has been amply documented in plants and algae, but not in cyanobacteria, using primarily the saturation pulse method of quenching analysis which is applied to continuously illuminated samples. This method is unsuitable for cyanobacteria because the background illumination elicits in them a very large Chl a fluorescence signal, due to a state 2 to state 1 transition, which masks fluorescence changes due to other causes. We investigated the qE problem in the cyanobacterium Synechococcus sp. PCC 7942 using a kinetic method (Chl a fluorescence induction) with which qE can be examined before the onset of the state 2 to state 1 transition and the attendant rise of Chl a fluorescence. Our results confirm the existence of a qE mechanism that operates on excited Chls a in Photosystem II core complexes of cyanobacteria. PMID:24793104

  7. Detection of reactive oxygen species (ROS) by the oxidant-sensing probe 2',7'-dichlorodihydrofluorescein diacetate in the cyanobacterium Anabaena variabilis PCC 7937

    SciTech Connect

    Rastogi, Rajesh P.; Laboratory of Photobiology and Molecular Microbiology, Centre of Advanced Study in Botany, Banaras Hindu University, Varanasi 221005 ; Singh, Shailendra P.; Haeder, Donat-P.; Sinha, Rajeshwar P.

    2010-07-02

    The generation of reactive oxygen species (ROS) under simulated solar radiation (UV-B: 0.30 Wm{sup -2}, UV-A: 25.70 Wm{sup -2} and PAR: 118.06 Wm{sup -2}) was studied in the cyanobacterium Anabaena variabilis PCC 7937 using the oxidant-sensing fluorescent probe 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA). DCFH-DA is a nonpolar dye, converted into the polar derivative DCFH by cellular esterases that are nonfluorescent but switched to highly fluorescent DCF when oxidized by intracellular ROS and other peroxides. The images obtained from the fluorescence microscope after 12 h of irradiation showed green fluorescence from cells covered with 295, 320 or 395 nm cut-off filters, indicating the generation of ROS in all treatments. However, the green/red fluorescence ratio obtained from fluorescence microscopic analysis showed the highest generation of ROS after UV-B radiation in comparison to PAR or UV-A radiation. Production of ROS was also measured by a spectrofluorophotometer and results obtained supported the results of fluorescence microscopy. Low levels of ROS were detected at the start (0 h) of the experiment showing that they are generated even during normal metabolism. This study also showed that UV-B radiation causes the fragmentation of the cyanobacterial filaments which could be due to the observed oxidative stress. This is the first report for the detection of intracellular ROS in a cyanobacterium by fluorescence microscopy using DCFH-DA and thereby suggesting the applicability of this method in the study of in vivo generation of ROS.

  8. Influence of extractive solvents on lipid and fatty acids content of edible freshwater algal and seaweed products, the green Microalga Chlorella kessleri and the Cyanobacterium Spirulina platensis.

    PubMed

    Ambrozova, Jarmila Vavra; Misurcova, Ladislava; Vicha, Robert; Machu, Ludmila; Samek, Dusan; Baron, Mojmir; Mlcek, Jiri; Sochor, Jiri; Jurikova, Tunde

    2014-01-01

    Total lipid contents of green (Chlorella pyrenoidosa, C), red (Porphyra tenera, N; Palmaria palmata, D), and brown (Laminaria japonica, K; Eisenia bicyclis, A; Undaria pinnatifida, W, WI; Hizikia fusiformis, H) commercial edible algal and cyanobacterial (Spirulina platensis, S) products, and autotrophically cultivated samples of the green microalga Chlorella kessleri (CK) and the cyanobacterium Spirulina platensis (SP) were determined using a solvent mixture of methanol/chloroform/water (1:2:1, v/v/v, solvent I) and n-hexane (solvent II). Total lipid contents ranged from 0.64% (II) to 18.02% (I) by dry weight and the highest total lipid content was observed in the autotrophically cultivated cyanobacterium Spirulina platensis. Solvent mixture I was found to be more effective than solvent II. Fatty acids were determined by gas chromatography of their methyl esters (% of total FAMEs). Generally, the predominant fatty acids (all results for extractions with solvent mixture I) were saturated palmitic acid (C16:0; 24.64%-65.49%), monounsaturated oleic acid (C18:1(n-9); 2.79%-26.45%), polyunsaturated linoleic acid (C18:2(n-6); 0.71%-36.38%), ?-linolenic acid (C18:3(n-3); 0.00%-21.29%), ?-linolenic acid (C18:3(n-6); 1.94%-17.36%), and arachidonic acid (C20:4(n-6); 0.00%-15.37%). The highest content of ?-3 fatty acids (21.29%) was determined in Chlorella pyrenoidosa using solvent I, while conversely, the highest content of ?-6 fatty acids (41.42%) was observed in Chlorella kessleri using the same solvent. PMID:24566307

  9. Optical characterization of the oceanic unicellular cyanobacterium Synechococcus grown under a day-night cycle in natural irradiance

    NASA Technical Reports Server (NTRS)

    Stramski, Dariusz; Shalapyonok, Alexi; Reynolds, Rick A.

    1995-01-01

    The optical properties of the ocenanic cyanobacterium Synechococcus (clone WH8103) were examined in a nutrient-replete laboratory culture grown under a day-night cycle in natural irradiance. Measurements of the spectral absorption and beam attenuation coefficients, the size distribution of cells in suspension, and microscopic analysis of samples were made at intervals of 2-4 hours for 2 days. These measurements were used to calculate the optical properties at the level of a single 'mean' cell representative of the acutal population, specifically, the optical cross sections for spectral absorption bar-(sigma(sub a)), scattering bar-sigma(sub b))(lambda), and attentuation bar-(sigma(sub c))(lambda). In addition, concurrent determinations of chlorophyll a and particulate organic carbon allowed calculation of the Chl a- and C-specific optical coefficients. The refractive index of cells was derived from the observed data using a theory of light absorption and scattering by homogeneous spheres. Low irradiance because of cloudy skies resulted in slow division rates of cells in the culture. The percentage of dividing cells was unusually high (greater than 30%) throughout the experiment. The optical cross sections varied greatly over a day-night cycle, with a minimum near dawn or midmorning and maximum near dusk. During daylight hours, bar-(sigma(sub b)) and bar-(sigma(sub c)) can increase more than twofold and bar-(sigma(sub a) by as much as 45%. The real part of the refractive index n increaed during the day; changes in n had equal or greater effect than the varying size distribution on changes in bar-(sigma(sub c)) and bar-(sigma(sub b)). The contribution of changes in n to the increase of bar-(sigma(sub c))(660) during daylight hours was 65.7% and 45.1% on day 1 and 2, respectively. During the dark period, when bar-(sigma(sub c))(660) decreased by a factor of 2.9, the effect of decreasing n was dominant (86.3%). With the exception of a few hours during the second light period, the imaginary part of the refractive index n' showed little variation over a day-night cycle, and bar-(sigma(sub a)) was largely controlled by variations in cell size. The real part of the refractive index at lambda = 660 nm was correlated with the intracellular C concentration and the imaginary part at lambda = 678 nm with the intracellular Chl a concentration. The C-specfic attenuation coefficient showed significant diel variability, which has implications for the estimation of oceanic primary production from measurements of diel variability in beam attenuation. This study provides strong evidence that diel variability is an important component of the optical characterization of marine phytoplankton.

  10. Genome-scale modeling of light-driven reductant partitioning and carbon fluxes in diazotrophic unicellular cyanobacterium Cyanothece sp. ATCC 51142

    SciTech Connect

    Vu, Trang; Stolyar, Sergey; Pinchuk, Grigoriy E.; Hill, Eric A.; Kucek, Leo A.; Brown, Roslyn N.; Lipton, Mary S.; Osterman, Andrei L.; Fredrickson, Jim K.; Konopka, Allan; Beliaev, Alex S.; Reed, Jennifer L.

    2012-04-05

    Genome-scale metabolic models have proven useful for answering fundamental questions about metabolic capabilities of a variety of microorganisms, as well as informing their metabolic engineering. However, only a few models are available for oxygenic photosynthetic microorganisms, particularly in cyanobacteria in which photosynthetic and respiratory electron transport chains (ETC) share components. We addressed the complexity of cyanobacterial ETC by developing a genome-scale model for the diazotrophic cyanobacterium, Cyanothece sp. ATCC 51142. The resulting metabolic reconstruction, iCce806, consists of 806 genes associated with 667 metabolic reactions and includes a detailed representation of the ETC and a biomass equation based on experimental measurements. Both computational and experimental approaches were used to investigate light-driven metabolism in Cyanothece sp. ATCC 51142, with a particular focus on reductant production and partitioning within the ETC. The simulation results suggest that growth and metabolic flux distributions are substantially impacted by the relative amounts of light going into the individual photosystems. When photosystem II flux is high, terminal oxidases of respiratory electron transport are predicted to be an important mechanism for removing excess electrons. When photosystem I flux is high cyclic electron transport becomes important. Model predictions of growth rates were in good quantitative agreement with measured growth rates, and predictions of reaction usage were qualitatively consistent with protein and mRNA expression data, when these latter datasets were used to constrain the model.

  11. Genome-Scale Modeling of Light-Driven Reductant Partitioning and Carbon Fluxes in Diazotrophic Unicellular Cyanobacterium Cyanothece sp. ATCC 51142

    SciTech Connect

    Vu, Trang; Stolyar, Sergey; Pinchuk, Grigoriy E.; Hill, Eric A.; Kucek, Leo A.; Brown, Roslyn N.; Lipton, Mary S.; Osterman, Andrei L.; Fredrickson, Jim K.; Konopka, Allan; Beliaev, Alex S.; Reed, Jennifer L.

    2012-04-05

    Genome-scale metabolic models have proven useful for answering fundamental questions about metabolic capabilities of a variety of microorganisms, as well as informing their metabolic engineering. However, only a few models are available for oxygenic photosynthetic microorganisms, particularly in cyanobacteria in which photosynthetic and respiratory electron transport chains (ETC) share components. We addressed the complexity of cyanobacterial ETC by developing a genome-scale model for the diazotrophic cyanobacterium, Cyanothece sp. ATCC 51142. The resulting metabolic reconstruction, iCce806, consists of 806 genes associated with 667 metabolic reactions and includes a detailed representation of the ETC and a biomass equation based on experimental measurements. Both computational and experimental approaches were used to investigate light-driven metabolism in Cyanothece sp. ATCC 51142, with a particular focus on reductant production and partitioning within the ETC. The simulation results suggest that growth and metabolic flux distributions are substantially impacted by the relative amounts of light going into the individual photosystems. When photosystem II flux is high, terminal oxidases of respiratory electron transport are predicted to be an important mechanism for removing excess electrons. When photosystem I flux is high cyclic electron transport becomes important. Model predictions of growth rates were in good quantitative agreement with measured growth rates, and predictions of reaction usage were ualitatively consistent with protein and mRNA expression data, when these latter datasets were used to constrain the model.

  12. Evolutionary changes in growth rate and toxin production in the cyanobacterium Microcystis aeruginosa under a scenario of eutrophication and temperature increase.

    PubMed

    Rouco, Mónica; López-Rodas, Victoria; Flores-Moya, Antonio; Costas, Eduardo

    2011-08-01

    Toxic blooms of the cyanobacterium Microcystis aeruginosa affect humans and animals in inland water systems worldwide, and it has been hypothesized that the development of these blooms will increase under the future scenario of global change, considering eutrophication and temperature increase as two important consequences. The importance of genetic adaptation, chance and history on evolution of growth rate, and toxin production of M. aeruginosa was studied under these new conditions. The experiment followed the idea of "replaying life's tape" by means of the simultaneous propagation of 15 independent isolates of three M. aeruginosa strains, which were grown under doubled nutrient concentration and temperature during c. 87 generations. Adaptation by new mutations that resulted in the enhancement of growth rate arose during propagation of derived cultures under the new environmental conditions was the main component of evolution; however, chance also contributed in a lesser extension to evolution of growth rate. Mutations were selected, displacing the wild-type ancestral genotypes. In contrast, the effect of selection on mutations affecting microcystin production was neutral. Chance and history were the pacemakers in evolution of toxin production. Although this study might be considered an oversimplification of the reality, it suggest that a future scenario of global change might lead to an increase in M. aeruginosa bloom frequency, but no predictions about the frequency of toxicity can be made. PMID:21271244

  13. Transduction of the light signal during complementary chromatic adaptation in the cyanobacterium Calothrix sp. PCC 7601: DNA-binding proteins and modulation by phosphorylation.

    PubMed Central

    Sobczyk, A; Schyns, G; Tandeau de Marsac, N; Houmard, J

    1993-01-01

    The cyanobacterium Calothrix sp. PCC 7601 can adapt its pigment content in response to changes in the incident light wavelength. It synthesizes, as major light-harvesting pigments, either phycocyanin 2 (PC2, encoded by the cpc2 operon) under red light or phycoerythrin (PE, encoded by the cpeBA operon) under green light conditions. The last step of the signal transduction pathway is characterized by a transcriptional control of the expression of these operons. Partially purified protein extracts were used in gel retardation assays and DNase I footprinting experiments to identify the factors that interact with the promoter region of the cpeBA operon. We found that two proteins, RcaA and RcaB, only detected in extracts of cells grown under green light, behave as positive transcriptional factors for the expression of the cpeBA operon. Treatment of the fractions containing RcaA and RcaB with alkaline phosphatase prevents the binding of RcaA but not of RcaB to the cpeBA promoter region. A post-translational modification of RcaA thus modulates its affinity for DNA. Images PMID:8458347

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

    PubMed

    Aguirre von Wobeser, Eneas; Ibelings, Bas W; Bok, Jasper; Krasikov, Vladimir; Huisman, Jef; Matthijs, Hans C P

    2011-03-01

    Physiological adaptation and genome-wide expression profiles of the cyanobacterium Synechocystis sp. strain PCC 6803 in response to gradual transitions between nitrogen-limited and light-limited growth conditions were measured in continuous cultures. Transitions induced changes in pigment composition, light absorption coefficient, photosynthetic electron transport, and specific growth rate. Physiological changes were accompanied by reproducible changes in the expression of several hundred open reading frames, genes with functions in photosynthesis and respiration, carbon and nitrogen assimilation, protein synthesis, phosphorus metabolism, and overall regulation of cell function and proliferation. Cluster analysis of the nearly 1,600 regulated open reading frames identified eight clusters, each showing a different temporal response during the transitions. Two large clusters mirrored each other. One cluster included genes involved in photosynthesis, which were up-regulated during light-limited growth but down-regulated during nitrogen-limited growth. Conversely, genes in the other cluster were down-regulated during light-limited growth but up-regulated during nitrogen-limited growth; this cluster included several genes involved in nitrogen uptake and assimilation. These results demonstrate complementary regulation of gene expression for two major metabolic activities of cyanobacteria. Comparison with batch-culture experiments revealed interesting differences in gene expression between batch and continuous culture and illustrates that continuous-culture experiments can pick up subtle changes in cell physiology and gene expression. PMID:21205618

  15. Exploring the size limit of protein diffusion through the periplasm in cyanobacterium Anabaena sp. PCC 7120 using the 13 kDa iLOV fluorescent protein.

    PubMed

    Zhang, Li-Chen; Risoul, Véronique; Latifi, Amel; Christie, John M; Zhang, Cheng-Cai

    2013-09-01

    In the filamentous heterocyst-forming cyanobacterium Anabaena PCC 7120, vegetative cells and heterocysts are interdependent on each other and engaged in exchanges of metabolites for survival when grown under diazotrophic conditions. In this organism, the periplasm appears to be continuous along each filament, with a shared outer membrane; however, barriers exist preventing free diffusion of the fluorescent protein GFP (27 kDa) targeted into the periplasmic space. Here we expressed a smaller fluorescent protein iLOV (? 13 kDa) fused to the All3333 (a putative homologue of NrtA) signal sequence corresponding to those recognized by the TAT protein translocation system, which exports iLOV to the periplasm of either heterocysts or vegetative cells. Fluorescence microscopy and immunoblot analysis indicated that the iLOV protein is translocated into the periplasm of the producing cell and properly processed, but does not diffuse to neighboring cells via the periplasm. Thus, periplasmic barriers appear to block diffusion of molecules with a size of 13 kDa, the minimum size tested thus far. Assuming that the physical barrier is the peptidoglycan sacculus, its pores might allow diffusion of molecules within the size range between the PatS pentapeptide and iLOV, thus between 0.53 kDa and 13 kDa. PMID:23748014

  16. Biochemical and Molecular Phylogenetic Study of Agriculturally Useful Association of a Nitrogen-Fixing Cyanobacterium and Nodule Sinorhizobium with Medicago sativa L.

    PubMed Central

    Karaushu, E. V.; Kravzova, T. R.; Vorobey, N. A.; Kiriziy, D. A.; Olkhovich, O. P.; Taran, N. Yu.; Kots, S. Ya.; Omarova, E.

    2015-01-01

    Seed inoculation with bacterial consortium was found to increase legume yield, providing a higher growth than the standard nitrogen treatment methods. Alfalfa plants were inoculated by mono- and binary compositions of nitrogen-fixing microorganisms. Their physiological and biochemical properties were estimated. Inoculation by microbial consortium of Sinorhizobium meliloti T17 together with a new cyanobacterial isolate Nostoc PTV was more efficient than the single-rhizobium strain inoculation. This treatment provides an intensification of the processes of biological nitrogen fixation by rhizobia bacteria in the root nodules and an intensification of plant photosynthesis. Inoculation by bacterial consortium stimulates growth of plant mass and rhizogenesis and leads to increased productivity of alfalfa and to improving the amino acid composition of plant leaves. The full nucleotide sequence of the rRNA gene cluster and partial sequence of the dinitrogenase reductase (nifH) gene of Nostoc PTV were deposited to GenBank (JQ259185.1, JQ259186.1). Comparison of these gene sequences of Nostoc PTV with all sequences present at the GenBank shows that this cyanobacterial strain does not have 100% identity with any organisms investigated previously. Phylogenetic analysis showed that this cyanobacterium clustered with high credibility values with Nostoc muscorum. PMID:26114100

  17. On recording the true absorption spectrum and the scattering spectrum of a turbid sample: application to cell suspensions of the cyanobacterium Anabaena variabilis.

    PubMed

    Merzlyak, M N; Naqvi, K R

    2000-11-01

    An integrating sphere is often used for recording the absorption spectrum of a turbid sample. If the sample is placed inside the sphere, scattering losses are eliminated, but the recorded spectrum suffers from other distortions. These distortions can be avoided by positioning the sample outside the sphere; but, since some of the scattered light escapes the detector, the recorded spectrum suffers from residual scattering losses. A method proposed by Latimer and Eubanks more than 30 years ago (Arch. Biochem. Biophys. 98 (1962) 274), is put to a quantitative examination, which has shown that one can obtain, by recording two spectra at different distances from the sphere, not only the true absorption spectrum but also the scattering spectra of the sample. Conditions for the validity of the basic assumption underlying the method are investigated by examining suspensions containing various concentrations of cells of the cyanobacterium Anabaena variabilis, and it is shown that the calculated absorbance is proportional to the number density of the cells. The application of the method for quantitative spectrophotometric analysis of pigments in cell suspensions is discussed. PMID:11233639

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

    PubMed

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

    2014-08-01

    The integrase of actinophage R4, which belongs to the large serine-recombinase family, catalyzes site-specific recombination between two distinct attachment site sequences of the phage (attP) and actinomycete Streptomyces parvulus 2297 chromosome (attB). We previously reported that R4 integrase (Sre) catalyzed site-specific recombination both in vivo and in vitro. In the present study, a Sre-based system was developed for the stepwise site-specific integration of multiple genes into the chromosome of cyanobacterium Synechocystis sp. PCC 6803 (hereafter PCC 6803). A transgene-integrated plasmid with two attP sites and a non-replicative sre-containing plasmid were co-introduced into attB-inserted PCC 6803 cells. The transiently expressed Sre catalyzed highly efficient site-specific integration between one of the two attP sites on the integration plasmid and the attB site on the chromosome of PCC 6803. A second transgene-integrated plasmid with an attB site was integrated into the residual attP site on the chromosome by repeating site-specific recombination. The transformation frequencies (%) of the first and second integrations were approximately 5.1 × 10(-5) and 8.2 × 10(-5), respectively. Furthermore, the expression of two transgenes was detected. This study is the first to apply the multiple gene site-specific integration system based on R4 integrase to cyanobacteria. PMID:24638932

  19. Dynamics and Cell-Type Specificity of the DNA Double-Strand Break Repair Protein RecN in the Developmental Cyanobacterium Anabaena sp. Strain PCC 7120

    PubMed Central

    Hu, Sheng; Wang, Jinglan; Wang, Li; Zhang, Cheng-Cai; Chen, Wen-Li

    2015-01-01

    DNA replication and repair are two fundamental processes required in life proliferation and cellular defense and some common proteins are involved in both processes. The filamentous cyanobacterium Anabaena sp. strain PCC 7120 is capable of forming heterocysts for N2 fixation in the absence of a combined-nitrogen source. This developmental process is intimately linked to cell cycle control. In this study, we investigated the localization of the DNA double-strand break repair protein RecN during key cellular events, such as chromosome damaging, cell division, and heterocyst differentiation. Treatment by a drug causing DNA double-strand breaks (DSBs) induced reorganization of the RecN focus preferentially towards the mid-cell position. RecN-GFP was absent in most mature heterocysts. Furthermore, our results showed that HetR, a central player in heterocyst development, was involved in the proper positioning and distribution of RecN-GFP. These results showed the dynamics of RecN in DSB repair and suggested a differential regulation of DNA DSB repair in vegetative cell and heterocysts. The absence of RecN in mature heterocysts is compatible with the terminal nature of these cells. PMID:26431054

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

    PubMed

    Drath, Miriam; Baier, Kerstin; Forchhammer, Karl

    2009-05-01

    Methionine aminopeptidases (MetAPs or MAPs, encoded by map genes) are ubiquitous and pivotal enzymes for protein maturation in all living organisms. Whereas most bacteria harbour only one map gene, many cyanobacterial genomes contain two map paralogues, the genome of Synechocystis sp. PCC 6803 even three. The physiological function of multiple map paralogues remains elusive so far. This communication reports for the first time differential MetAP function in a cyanobacterium. In Synechocystis sp. PCC 6803, the universally conserved mapC gene (sll0555) is predominantly expressed in exponentially growing cells and appears to be a housekeeping gene. By contrast, expression of mapA (slr0918) and mapB (slr0786) genes increases during stress conditions. The mapB paralogue is only transiently expressed, whereas the widely distributed mapA gene appears to be the major MetAP during stress conditions. A mapA-deficient Synechocystis mutant shows a subtle impairment of photosystem II properties even under non-stressed conditions. In particular, the binding site for the quinone Q(B) is affected, indicating specific N-terminal methionine processing requirements of photosystem II components. MAP-A-specific processing becomes essential under certain stress conditions, since the mapA-deficient mutant is severely impaired in surviving conditions of prolonged nitrogen starvation and high light exposure. PMID:19359320

  1. Replacement of chlorophyll with di-vinyl chlorophyll in the antenna and reaction center complexes of the cyanobacterium Synechocystis sp. PCC 6803: characterization of spectral and photochemical properties.

    PubMed

    Tomo, Tatsuya; Akimoto, Seiji; Ito, Hisashi; Tsuchiya, Tohru; Fukuya, Michitaka; Tanaka, Ayumi; Mimuro, Mamoru

    2009-03-01

    Chlorophyll (Chl) a in a cyanobacterium Synechocystis sp. PCC 6803 was replaced with di-vinyl (DV)-Chl a by knock-out of the specific gene (slr1923), responsible for the reduction of a 8-vinyl group, and optical and photochemical properties of purified photosystem (PS) II complexes (DV-PS II) were investigated. We observed differences in the peak wavelengths of absorption and fluorescence spectra; however, replacement of Chl a with DV-Chl a had limited effects. On the contrary, photochemical reactions were highly sensitive to high-light treatments in the mutant. Specifically, DV-Chl a was rapidly bleached under high-light conditions, and we detected significant dissociation of complexes and degradation of D1 proteins (PsbA). By comparing the SDS-PAGE patterns observed in this study to those observed in spinach chloroplasts, this degradation is assigned to the acceptor-side photoinhibition. The delayed fluorescence in the nanosecond time region at 77 K was suppressed in DV-PS II, possibly increasing triplet formation of Chl molecules. Our findings provide insight into the evolutionary processes of cyanobacteria. The effects of pigment replacement on the optimization of reactions are discussed. PMID:19168027

  2. NADPH fluorescence in the cyanobacterium Synechocystis sp. PCC 6803: a versatile probe for in vivo measurements of rates, yields and pools.

    PubMed

    Kauny, Jocelyn; Sétif, Pierre

    2014-06-01

    We measured the kinetics of light-induced NADPH formation and subsequent dark consumption by monitoring in vivo its fluorescence in the cyanobacterium Synechocystis PCC 6803. Spectral data allowed the signal changes to be attributed to NAD(P)H and signal linearity vs the chlorophyll concentration was shown to be recoverable after appropriate correction. Parameters associated to reduction of NADP(+) to NADPH by ferredoxin-NADP(+)-oxidoreductase were determined: After single excitation of photosystem I, half of the signal rise is observed in 8ms; Evidence for a kinetic limitation which is attributed to an enzyme bottleneck is provided; After two closely separated saturating flashes eliciting two photosystem I turnovers in less than 2ms, more than 50% of the cytoplasmic photoreductants (reduced ferredoxin and photosystem I acceptors) are diverted from NADPH formation by competing processes. Signal quantitation in absolute NADPH concentrations was performed by adding exogenous NADPH to the cell suspensions and by estimating the enhancement factor of in vivo fluorescence (between 2 and 4). The size of the visible (light-dependent) NADP (NADP(+)+NADPH) pool was measured to be between 1.4 and 4 times the photosystem I concentration. A quantitative discrepancy is found between net oxygen evolution and NADPH consumption by the light-activated Calvin-Benson cycle. The present study shows that NADPH fluorescence is an efficient probe for studying in vivo the energetic metabolism of cyanobacteria which can be used for assessing multiple phenomena occurring over different time scales. PMID:24463053

  3. Distribution of a consortium between unicellular algae and the N2 fixing cyanobacterium UCYN-A in the North Atlantic Ocean.

    PubMed

    Krupke, Andreas; Lavik, Gaute; Halm, Hannah; Fuchs, Bernhard M; Amann, Rudolf I; Kuypers, Marcel M M

    2014-10-01

    The globally abundant, uncultured unicellular cyanobacterium UCYN-A was recently discovered living in association with a eukaryotic cell closely related to a prymnesiophyte. Here, we established a double CAtalysed Reporter Deposition-Fluorescence In Situ Hybridization (CARD-FISH) approach to identify both partners and provided quantitative information on their distribution and abundance across distinct water masses along a transect in the North Atlantic Ocean. The N2 fixation activity coincided with the detection of UCYN-A cells and was only observed in oligotrophic (?18°C) surface waters. Parallel 16S ribosomal RNA gene analyses among unicellular diazotrophs indicated that only UCYN-A cells were present. UCYN-A cells were associated with an algal partner or non-associated using the double CARD-FISH approach. We demonstrated that UCYN-A cells living in association with Haptophyta were the dominant form (87.0?±?6.1%), whereas non-associated UCYN-A cells represented only a minor fraction (5.2?±?3.9%). Interestingly, UCYN-A cells were also detected living in association with unknown single-celled eukaryotes in small amounts (7.8?±?5.2%), presumably Alveolata. The proposed ecological niche of UCYN-A as an oligotrophic, mesophilic and obligate symbiotic nitrogen-fixing microorganism is evident for the North Atlantic Ocean. PMID:24612325

  4. Molecular Cloning and Biochemical Characterization of the Iron Superoxide Dismutase from the Cyanobacterium Nostoc punctiforme ATCC 29133 and Its Response to Methyl Viologen-Induced Oxidative Stress.

    PubMed

    Moirangthem, Lakshmipyari Devi; Ibrahim, Kalibulla Syed; Vanlalsangi, Rebecca; Stensjö, Karin; Lindblad, Peter; Bhattacharya, Jyotirmoy

    2015-12-01

    Superoxide dismutase (SOD) detoxifies cell-toxic superoxide radicals and constitutes an important component of antioxidant machinery in aerobic organisms, including cyanobacteria. The iron-containing SOD (SodB) is one of the most abundant soluble proteins in the cytosol of the nitrogen-fixing cyanobacterium Nostoc punctiforme ATCC 29133, and therefore, we investigated its biochemical properties and response to oxidative stress. The putative SodB-encoding open reading frame Npun_R6491 was cloned and overexpressed in Escherichia coli as a C-terminally hexahistidine-tagged protein. The purified recombinant protein had a SodB specific activity of 2560 ± 48 U/mg protein at pH 7.8 and was highly thermostable. The presence of a characteristic iron absorption peak at 350 nm, and its sensitivity to H2O2 and azide, confirmed that the SodB is an iron-containing SOD. Transcript level of SodB in nitrogen-fixing cultures of N. punctiforme decreased considerably (threefold) after exposure to an oxidative stress-generating herbicide methyl viologen for 4 h. Furthermore, in-gel SOD activity analysis of such cultures grown at increasing concentrations of methyl viologen also showed a loss of SodB activity. These results suggest that SodB is not the primary scavenger of superoxide radicals induced by methyl viologen in N. punctiforme. PMID:26438488

  5. Genomic Survey and Biochemical Analysis of Recombinant Candidate Cyanobacteriochromes Reveals Enrichment for Near UV/Violet Sensors in the Halotolerant and Alkaliphilic Cyanobacterium Microcoleus IPPAS B353.

    PubMed

    Cho, Sung Mi; Jeoung, Sae Chae; Song, Ji-Young; Kupriyanova, Elena V; Pronina, Natalia A; Lee, Bong-Woo; Jo, Seong-Whan; Park, Beom-Seok; Choi, Sang-Bong; Song, Ji-Joon; Park, Youn-Il

    2015-11-20

    Cyanobacteriochromes (CBCRs), which are exclusive to and widespread among cyanobacteria, are photoproteins that sense the entire range of near-UV and visible light. CBCRs are related to the red/far-red phytochromes that utilize linear tetrapyrrole (bilin) chromophores. Best characterized from the unicellular cyanobacterium Synechocystis sp. PCC 6803 and the multicellular heterocyst forming filamentous cyanobacteria Nostoc punctiforme ATCC 29133 and Anabaena sp. PCC 7120, CBCRs have been poorly investigated in mat-forming, nonheterocystous cyanobacteria. In this study, we sequenced the genome of one of such species, Microcoleus IPPAS B353 (Microcoleus B353), and identified two phytochromes and seven CBCRs with one or more bilin-binding cGMP-specific phosphodiesterase, adenylyl cyclase and FhlA (GAF) domains. Biochemical and spectroscopic measurements of 23 purified GAF proteins from phycocyanobilin (PCB) producing recombinant Escherichia coli indicated that 13 of these proteins formed near-UV and visible light-absorbing covalent adducts: 10 GAFs contained PCB chromophores, whereas three contained the PCB isomer, phycoviolobilin (PVB). Furthermore, the complement of Microcoleus B353 CBCRs is enriched in near-UV and violet sensors, but lacks red/green and green/red CBCRs that are widely distributed in other cyanobacteria. We hypothesize that enrichment in short wavelength-absorbing CBCRs is critical for acclimation to high-light environments where this organism is found. PMID:26405033

  6. Plasmid Stability in Dried Cells of the Desert Cyanobacterium Chroococcidiopsis and its Potential for GFP Imaging of Survivors on Earth and in Space

    NASA Astrophysics Data System (ADS)

    Billi, Daniela

    2012-06-01

    Two GFP-based plasmids, namely pTTQ18-GFP-pDU1mini and pDUCA7-GFP, of about 7 kbp and 15 kbp respectively, able to replicate in Chroococcidiopsis sp. CCMEE 029 and CCMEE 123, were developed. Both plasmids were maintained in Chroococcidiopsis cells after 18 months of dry storage as demonstrated by colony PCR, plasmid restriction analysis, GFP imaging and colony-forming ability under selection of dried transformants; thus suggesting that strategies employed by this cyanobacterium to stabilize dried chromosomal DNA, must have protected plasmid DNA. The suitability of pDU1mini-plasmid for GFP tagging in Chroococcidiopsis was investigated by using the RecA homolog of Synechocystis sp. PCC 6803. After 2 months of dry storage, the presence of dried cells with a GFP-RecASyn distribution resembling that of hydrated cells, supported its capability of preventing desiccation-induced genome damage, whereas the rewetted cells with filamentous GFP-RecASyn structures revealed sub-lethal DNA damage. The long-term stability of plasmid DNA in dried Chroococcidiopsis has implication for space research, for example when investigating the recovery of dried cells after Martian and space simulations or when developing life support systems based on phototrophs with genetically enhanced stress tolerance and stored in the dry state for prolonged periods.

  7. Toxicity and partial structure of a hepatotoxic peptide produced by the cyanobacterium Nodularia spumigena Mertens emend. L575 from New Zealand.

    PubMed Central

    Carmichael, W W; Eschedor, J T; Patterson, G M; Moore, R E

    1988-01-01

    A clonal isolate, termed L575, of the filamentous brackish-water cyanobacterium Nodularia spumigena Mertens emend. was found to produce a potent hepatotoxic peptide (50% lethal intraperitoneal dose for the mouse, 60 micrograms/kg) with chemical and toxicological properties similar to those of the hepatotoxic heptapeptides produced by other freshwater planktonic cyanobacteria. The isolate was made from a water sample collected in Lake Ellesmere, New Zealand, in 1980. The toxin, isolated and purified by high-performance liquid chromatography (HPLC) and analyzed by HPLC amino acid analysis, contained glutamic acid, beta-methyla-spartic acid, and arginine units in equivalent amounts. The fast-atom-bombardment mass spectrum of the toxin indicated the molecular weight to be 824. Batch cultures of strain L575 showed that the toxin content varied between 1.96 and 2.99 mg/g of cells and that a positive correlation between toxin content and chlorophyll a, but not biomass, was present. Images PMID:3142356

  8. Sucrose Synthesis in the Nitrogen-Fixing Cyanobacterium Anabaena sp. Strain PCC 7120 Is Controlled by the Two-Component Response Regulator OrrA

    PubMed Central

    Kimura, Satoshi; Miyazaki, Shogo; Ohmori, Masayuki

    2014-01-01

    The filamentous, nitrogen-fixing cyanobacterium Anabaena sp. strain PCC 7120 accumulates sucrose as a compatible solute against salt stress. Sucrose-phosphate synthase activity, which is responsible for the sucrose synthesis, is increased by salt stress, but the mechanism underlying the regulation of sucrose synthesis remains unknown. In the present study, a response regulator, OrrA, was shown to control sucrose synthesis. Expression of spsA, which encodes a sucrose-phosphate synthase, and susA and susB, which encode sucrose synthases, was induced by salt stress. In the orrA disruptant, salt induction of these genes was completely abolished. The cellular sucrose level of the orrA disruptant was reduced to 40% of that in the wild type under salt stress conditions. Moreover, overexpression of orrA resulted in enhanced expression of spsA, susA, and susB, followed by accumulation of sucrose, without the addition of NaCl. We also found that SigB2, a group 2 sigma factor of RNA polymerase, regulated the early response to salt stress under the control of OrrA. It is concluded that OrrA controls sucrose synthesis in collaboration with SigB2. PMID:25002430

  9. Identification of the correct form of the mis-annotated response regulator Rre1 from the cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Vidal, Rebeca

    2015-04-01

    Two-component systems have been extensively described in the control of gene expression in response to different environmental signals in the cyanobacterium Synechocystis sp. PCC 6803. The Hik34-Rre1 two-component system has been shown to regulate a set of genes under certain stress conditions. Some evidence indicates that another histidine kinase, probably Hik2, is acting upstream of Rre1 in the regulation of some genes in response to hyperosmotic and salt stress. In the present study, a mis-annotation of the Rre1 protein has been identified and the correct version has been functionally characterized in vitro. By using EMSA assays, we have demonstrated that phosphorylation of Rre1 by Hik2 increases the affinity of the response regulator for the adhA promoter region, a gene that has been demonstrated previously to be specifically regulated by the Hik34-Rre1 system. These results suggest that Hik2 might cooperate with Hik34 in the regulation of the adhA gene by transferring the phosphoryl group to Rre1 under salt and hyperosmotic stress conditions. PMID:25714549

  10. Plasmid stability in dried cells of the desert cyanobacterium Chroococcidiopsis and its potential for GFP imaging of survivors on Earth and in space.

    PubMed

    Billi, Daniela

    2012-06-01

    Two GFP-based plasmids, namely pTTQ18-GFP-pDU1(mini) and pDUCA7-GFP, of about 7 kbp and 15 kbp respectively, able to replicate in Chroococcidiopsis sp. CCMEE 029 and CCMEE 123, were developed. Both plasmids were maintained in Chroococcidiopsis cells after 18 months of dry storage as demonstrated by colony PCR, plasmid restriction analysis, GFP imaging and colony-forming ability under selection of dried transformants; thus suggesting that strategies employed by this cyanobacterium to stabilize dried chromosomal DNA, must have protected plasmid DNA. The suitability of pDU1(mini)-plasmid for GFP tagging in Chroococcidiopsis was investigated by using the RecA homolog of Synechocystis sp. PCC 6803. After 2 months of dry storage, the presence of dried cells with a GFP-RecA(Syn) distribution resembling that of hydrated cells, supported its capability of preventing desiccation-induced genome damage, whereas the rewetted cells with filamentous GFP-RecA(Syn) structures revealed sub-lethal DNA damage. The long-term stability of plasmid DNA in dried Chroococcidiopsis has implication for space research, for example when investigating the recovery of dried cells after Martian and space simulations or when developing life support systems based on phototrophs with genetically enhanced stress tolerance and stored in the dry state for prolonged periods. PMID:22638838

  11. D1 protein turnover is involved in protection of Photosystem II against UV-B induced damage in the cyanobacterium Arthrospira (Spirulina) platensis.

    PubMed

    Wu, Hongyan; Abasova, Leyla; Cheregi, Otilia; Deák, Zsuzsanna; Gao, Kunshan; Vass, Imre

    2011-01-01

    By using two strains of Arthrospira (Spirulina)platensis, an economically important filamentous cyanobacterium, we compared the impairment of PSII activity and loss of D1 protein content under UV-B radiation. Our study showed that UV-B radiation induced a gradual loss of the oxygen-evolving activity to about 56% after 180 min UV-B irradiation both in strains 439 and D-0083, which have been kept under indoor and an outdoor culturing conditions, respectively for a prolonged period of time. The loss of oxygen evolution was accelerated in both strains in the presence of lincomycin, an inhibitor of protein synthesis, and the amount of D1 protein showed a decrease comparable to that of oxygen evolution during the UV-B exposure. However, the UV-B induced loss of oxygen-evolving activity and D1 protein amount was largely prevented when A. platensis cells were exposed to UV-B irradiance supplemented with visible light. Comparison of the two strains also showed a smaller extent of D1 protein synthesis dependent PSII repair in the indoor strain. Our results show that turnover of the D1 protein is an important defense mechanism to counteract the UV-B induced damage of PSII in A. platensis, and also that visible light plays an important role in maintaining the function of PSII under simultaneous exposure to UV-B and visible light. PMID:21300555

  12. Role of RNA Secondary Structure and Processing in Stability of the nifH1 Transcript in the Cyanobacterium Anabaena variabilis

    PubMed Central

    Pratte, Brenda S.; Ungerer, Justin

    2015-01-01

    ABSTRACT In the cyanobacterium Anabaena variabilis ATCC 29413, aerobic nitrogen fixation occurs in micro-oxic cells called heterocysts. Synthesis of nitrogenase in heterocysts requires expression of the large nif1 gene cluster, which is primarily under the control of the promoter for the first gene, nifB1. Strong expression of nifH1 requires the nifB1 promoter but is also controlled by RNA processing, which leads to increased nifH1 transcript stability. The processing of the primary nifH1 transcript occurs at the base of a predicted stem-loop structure that is conserved in many heterocystous cyanobacteria. Mutations that changed the predicted secondary structure or changed the sequence of the stem-loop had detrimental effects on the amount of nifH1 transcript, with mutations that altered or destabilized the structure having the strongest effect. Just upstream from the transcriptional processing site for nifH1 was the promoter for a small antisense RNA, sava4870.1. This RNA was more strongly expressed in cells grown in the presence of fixed nitrogen and was downregulated in cells 24 h after nitrogen step down. A mutant strain lacking the promoter for sava4870.1 showed delayed nitrogen fixation; however, that phenotype might have resulted from an effect of the mutation on the processing of the nifH1 transcript. The nifH1 transcript was the most abundant and most stable nif1 transcript, while nifD1 and nifK1, just downstream of nifH1, were present in much smaller amounts and were less stable. The nifD1 and nifK1 transcripts were also processed at sites just upstream of nifD1 and nifK1. IMPORTANCE In the filamentous cyanobacterium Anabaena variabilis, the nif1 cluster, encoding the primary Mo nitrogenase, functions under aerobic growth conditions in specialized cells called heterocysts that develop in response to starvation for fixed nitrogen. The large cluster comprising more than a dozen nif1 genes is transcribed primarily from the promoter for the first gene, nifB1; however, this does not explain the large amount of transcript for the structural genes nifH1, nifD1, and nifK1, which are also under the control of the distant nifB1 promoter. Here, we demonstrate the importance of a predicted stem-loop structure upstream of nifH1 that controls the abundance of nifH1 transcript through transcript processing and stabilization and show that nifD1 and nifK1 transcripts are also controlled by transcript processing. PMID:25666132

  13. Strains of the Harmful Cyanobacterium Microcystis aeruginosa Differ in Gene Expression and Activity of Inorganic Carbon Uptake Systems at Elevated CO2 Levels.

    PubMed

    Sandrini, Giovanni; Jakupovic, Dennis; Matthijs, Hans C P; Huisman, Jef

    2015-11-15

    Cyanobacteria are generally assumed to be effective competitors at low CO2 levels because of their efficient CO2-concentrating mechanism (CCM), and yet how bloom-forming cyanobacteria respond to rising CO2 concentrations is less clear. Here, we investigate changes in CCM gene expression at ambient CO2 (400 ppm) and elevated CO2 (1,100 ppm) in six strains of the harmful cyanobacterium Microcystis. All strains downregulated cmpA encoding the high-affinity bicarbonate uptake system BCT1, whereas both the low- and high-affinity CO2 uptake genes were expressed constitutively. Four strains downregulated the bicarbonate uptake genes bicA and/or sbtA, whereas two strains showed constitutive expression of the bicA-sbtA operon. In one of the latter strains, a transposon insert in bicA caused low bicA and sbtA transcript levels, which made this strain solely dependent on BCT1 for bicarbonate uptake. Activity measurements of the inorganic carbon (Ci) uptake systems confirmed the CCM gene expression results. Interestingly, genes encoding the RuBisCO enzyme, structural carboxysome components, and carbonic anhydrases were not regulated. Hence, Microcystis mainly regulates the initial uptake of inorganic carbon, which might be an effective strategy for a species experiencing strongly fluctuating Ci concentrations. Our results show that CCM gene regulation of Microcystis varies among strains. The observed genetic and phenotypic variation in CCM responses may offer an important template for natural selection, leading to major changes in the genetic composition of harmful cyanobacterial blooms at elevated CO2. PMID:26319871

  14. Enhancement of human adaptive immune responses by administration of a high-molecular-weight polysaccharide extract from the cyanobacterium Arthrospira platensis.

    PubMed

    Løbner, Morten; Walsted, Anette; Larsen, Rune; Bendtzen, Klaus; Nielsen, Claus Henrik

    2008-06-01

    The effect of consumption of Immulina, a high-molecular-weight polysaccharide extract from the cyanobacterium Arthrospira platensis, on adaptive immune responses was investigated by evaluation of changes in leukocyte responsiveness to two foreign recall antigens, Candida albicans (CA) and tetanus toxoid (TT), in vitro. Consumption of Immulina by 11 healthy male volunteers caused an immediate, but temporary, increase of CA-induced CD4+ T-helper (Th) cell proliferation (P < .02). TT-induced Th cell proliferation was increased in individuals over 50 years of age (P < .05) and correlated with age (P < .02). Consumption for 8 days enhanced the CA-induced B cell proliferation (P < .02), but after 56 days a diminution was seen (P < .03). The CA-elicited production of the Th1 cytokines tumor necrosis factor (TNF)-alpha, interleukin (IL)-2, and interferon (IFN)-gamma was increased after Immunlina administration for 3 days (P < .001, < .03, and < .007, respectively), and increased IL-2 production persisted after 56 days (P < .004). The TNF-alpha, IFN-gamma, and IL-6 responses to TT were enhanced after 8 and 14 days (P < .002-.05), while IL-5 responses increased significantly within 3 days (P < .04) and fell below baseline levels after 14 days (P < .008). Conversely, consumption for 3 days inhibited the IL-4 responses to both CA and TT (P < .008 and P < .03, respectively). No effects on IL-10 responses were observed. Upon addition to normal mononuclear cells in vitro, Immulina elicited strong TNF-alpha, IL-1beta, and IL-6 responses, indicating that it acts by inducing a pro-inflammatory state. Taken together, the data suggest that Immulina causes an age-dependent, temporary enhancement of adaptive immune responses. PMID:18598175

  15. The Peptidoglycan-Binding Protein SjcF1 Influences Septal Junction Function and Channel Formation in the Filamentous Cyanobacterium Anabaena

    PubMed Central

    Rudolf, Mareike; Tetik, Nalan; Ramos-León, Félix; Flinner, Nadine; Ngo, Giang; Stevanovic, Mara; Burnat, Mireia; Pernil, Rafael; Flores, Enrique

    2015-01-01

    ABSTRACT Filamentous, heterocyst-forming cyanobacteria exchange nutrients and regulators between cells for diazotrophic growth. Two alternative modes of exchange have been discussed involving transport either through the periplasm or through septal junctions linking adjacent cells. Septal junctions and channels in the septal peptidoglycan are likely filled with septal junction complexes. While possible proteinaceous factors involved in septal junction formation, SepJ (FraG), FraC, and FraD, have been identified, little is known about peptidoglycan channel formation and septal junction complex anchoring to the peptidoglycan. We describe a factor, SjcF1, involved in regulation of septal junction channel formation in the heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120. SjcF1 interacts with the peptidoglycan layer through two peptidoglycan-binding domains and is localized throughout the cell periphery but at higher levels in the intercellular septa. A strain with an insertion in sjcF1 was not affected in peptidoglycan synthesis but showed an altered morphology of the septal peptidoglycan channels, which were significantly wider in the mutant than in the wild type. The mutant was impaired in intercellular exchange of a fluorescent probe to a similar extent as a sepJ deletion mutant. SjcF1 additionally bears an SH3 domain for protein-protein interactions. SH3 binding domains were identified in SepJ and FraC, and evidence for interaction of SjcF1 with both SepJ and FraC was obtained. SjcF1 represents a novel protein involved in structuring the peptidoglycan layer, which links peptidoglycan channel formation to septal junction complex function in multicellular cyanobacteria. Nonetheless, based on its subcellular distribution, this might not be the only function of SjcF1. PMID:26126850

  16. Analysis of spontaneous suppressor mutants from the photomixotrophically grown pmgA-disrupted mutant in the cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Nishijima, Yoshiki; Kanesaki, Yu; Yoshikawa, Hirofumi; Ogawa, Takako; Sonoike, Kintake; Nishiyama, Yoshitaka; Hihara, Yukako

    2015-12-01

    The pmgA-disrupted (?pmgA) mutant in the cyanobacterium Synechocystis sp. PCC 6803 suffers severe growth inhibition under photomixotrophic conditions. In order to elucidate the key factors enabling the cells to grow under photomixotrophic conditions, we isolated spontaneous suppressor mutants from the ?pmgA mutant derived from a single colony. When the ?pmgA mutant was spread on a BG11 agar plate supplemented with glucose, colonies of suppressor mutants appeared after the bleaching of the background cells. We identified the mutation site of these suppressor mutants and found that 11 mutants out of 13 had a mutation in genes related to the type 1 NAD(P)H dehydrogenase (NDH-1) complex. Among them, eight mutants had mutations within the ndhF3 (sll1732) gene: R32stop, W62stop, V147I, G266V, G354W, G586C, and deletion of 7 bp within the coding region. One mutant had one base insertion in the putative -10 box of the ndhC (slr1279) gene, leading to the decrease in the transcripts of the ndhCKJ operon. Two mutants had one base insertion and deletion in the coding region of cupA (sll1734), which is co-transcribed with ndhF3 and ndhD3 and comprises together a form of NDH-1 complex (NDH-1MS complex) involved in inducible high-affinity CO2 uptake. The results indicate that the loss of the activity of this complex effectively rescues the ?pmgA mutant under photomixotrophic condition with 1 % CO2. However, little difference among WT and mutants was observed in the activities ascribed to the NDH-1MS complex, i.e., CO2 uptake and cyclic electron transport. This may suggest that the NDH-1MS complex has the third, currently unknown function under photomixotrophic conditions. PMID:25869635

  17. Excitation energy transfer and electron-vibrational coupling in phycobiliproteins of the cyanobacterium Acaryochloris marina investigated by site-selective spectroscopy.

    PubMed

    Gryliuk, G; Rätsep, M; Hildebrandt, S; Irrgang, K-D; Eckert, H-J; Pieper, J

    2014-09-01

    In adaption to its specific environmental conditions, the cyanobacterium Acaryochloris marina developed two different types of light-harvesting complexes: chlorophyll-d-containing membrane-intrinsic complexes and phycocyanobilin (PCB) - containing phycobiliprotein (PBP) complexes. The latter complexes are believed to form a rod-shaped structure comprising three homo-hexamers of phycocyanin (PC), one hetero-hexamer of phycocyanin and allophycocyanin (APC) and probably a linker protein connecting the PBPs to the reaction centre. Excitation energy transfer and electron-vibrational coupling in PBPs have been investigated by selectively excited fluorescence spectra. The data reveal a rich spectral substructure with a total of five low-energy electronic states with fluorescence bands at 635nm, 645nm, 654nm, 659nm and a terminal emitter at about 673 nm. The electronic states at ~635 and 645 nm are tentatively attributed to PC and APC, respectively, while an apparent heterogeneity among PC subunits may also play a role. The other fluorescence bands may be associated with three different isoforms of the linker protein. Furthermore, a large number of vibrational features can be identified for each electronic state with intense phonon sidebands peaking at about 31 to 37cm?¹, which are among the highest phonon frequencies observed for photosynthetic antenna complexes. The corresponding Huang-Rhys factors S fall in the range between 0.98 (terminal emitter), 1.15 (APC), and 1.42 (PC). Two characteristic vibronic lines at about 1580 and 1634cm?¹ appear to reflect CNH? and CC stretching modes of the PCB chromophore, respectively. The exact phonon and vibrational frequencies vary with electronic state implying that the respective PCB chromophores are bound to different protein environments. This article is part of a special issue entitled: photosynthesis research for sustainability: keys to produce clean energy. PMID:24560813

  18. ChIP analysis unravels an exceptionally wide distribution of DNA binding sites for the NtcA transcription factor in a heterocyst-forming cyanobacterium

    PubMed Central

    2014-01-01

    Background The CRP-family transcription factor NtcA, universally found in cyanobacteria, was initially discovered as a regulator operating N control. It responds to the N regime signaled by the internal 2-oxoglutarate levels, an indicator of the C to N balance of the cells. Canonical NtcA-activated promoters bear an NtcA-consensus binding site (GTAN8TAC) centered at about 41.5 nucleotides upstream from the transcription start point. In strains of the Anabaena/Nostoc genera NtcA is pivotal for the differentiation of heterocysts in response to N stress. Results In this study, we have used chromatin immunoprecipitation followed by high-throughput sequencing to identify the whole catalog of NtcA-binding sites in cells of the filamentous, heterocyst-forming cyanobacterium Anabaena sp. PCC 7120 three hours after the withdrawal of combined N. NtcA has been found to bind to 2,424 DNA regions in the genome of Anabaena, which have been ascribed to 2,153 genes. Interestingly, only a small proportion of those genes are involved in N assimilation and metabolism, and 65% of the binding regions were located intragenically. Conclusions The distribution of NtcA-binding sites identified here reveals the largest bacterial regulon described to date. Our results show that NtcA has a much wider role in the physiology of the cell than it has been previously thought, acting both as a global transcriptional regulator and possibly also as a factor influencing the superstructure of the chromosome (and plasmids). PMID:24417914

  19. Levels of Daily Light Doses Under Changed Day-Night Cycles Regulate Temporal Segregation of Photosynthesis and N2 Fixation in the Cyanobacterium Trichodesmium erythraeum IMS101

    PubMed Central

    Cai, Xiaoni; Gao, Kunshan

    2015-01-01

    While the diazotrophic cyanobacterium Trichodesmium is known to display inverse diurnal performances of photosynthesis and N2 fixation, such a phenomenon has not been well documented under different day-night (L-D) cycles and different levels of light dose exposed to the cells. Here, we show differences in growth, N2 fixation and photosynthetic carbon fixation as well as photochemical performances of Trichodesmium IMS101 grown under 12L:12D, 8L:16D and 16L:8D L-D cycles at 70 ?mol photons m-2 s-1 PAR (LL) and 350 ?mol photons m-2 s-1 PAR (HL). The specific growth rate was the highest under LL and the lowest under HL under 16L:8D, and it increased under LL and decreased under HL with increased levels of daytime light doses exposed under the different light regimes, respectively. N2 fixation and photosynthetic carbon fixation were affected differentially by changes in the day-night regimes, with the former increasing directly under LL with increased daytime light doses and decreased under HL over growth-saturating light levels. Temporal segregation of N2 fixation from photosynthetic carbon fixation was evidenced under all day-night regimes, showing a time lag between the peak in N2 fixation and dip in carbon fixation. Elongation of light period led to higher N2 fixation rate under LL than under HL, while shortening the light exposure to 8 h delayed the N2 fixation peaking time (at the end of light period) and extended it to night period. Photosynthetic carbon fixation rates and transfer of light photons were always higher under HL than LL, regardless of the day-night cycles. Conclusively, diel performance of N2 fixation possesses functional plasticity, which was regulated by levels of light energy supplies either via changing light levels or length of light exposure. PMID:26258473

  20. Characterization of thylakoid membrane in a heterocystous cyanobacterium and green alga with dual-detector fluorescence lifetime imaging microscopy with a systematic change of incident laser power.

    PubMed

    Nozue, Shuho; Mukuno, Akira; Tsuda, Yumi; Shiina, Takashi; Terazima, Masahide; Kumazaki, Shigeichi

    2016-01-01

    Fluorescence Lifetime Imaging Microscopy (FLIM) has been applied to plants, algae and cyanobacteria, in which excitation laser conditions affect the chlorophyll fluorescence lifetime due to several mechanisms. However, the dependence of FLIM data on input laser power has not been quantitatively explained by absolute excitation probabilities under actual imaging conditions. In an effort to distinguish between photosystem I and photosystem II (PSI and PSII) in microscopic images, we have obtained dependence of FLIM data on input laser power from a filamentous cyanobacterium Anabaena variabilis and single cellular green alga Parachlorella kessleri. Nitrogen-fixing cells in A. variabilis, heterocysts, are mostly visualized as cells in which short-lived fluorescence (?0.1ns) characteristic of PSI is predominant. The other cells in A. variabilis (vegetative cells) and P. kessleri cells show a transition in the status of PSII from an open state with the maximal charge separation rate at a weak excitation limit to a closed state in which charge separation is temporarily prohibited by previous excitation(s) at a relatively high laser power. This transition is successfully reproduced by a computer simulation with a high fidelity to the actual imaging conditions. More details in the fluorescence from heterocysts were examined to assess possible functions of PSII in the anaerobic environment inside the heterocysts for the nitrogen-fixing enzyme, nitrogenase. Photochemically active PSII:PSI ratio in heterocysts is tentatively estimated to be typically below our detection limit or at most about 5% in limited heterocysts in comparison with that in vegetative cells. PMID:26474523

  1. Association of High Light-Inducible HliA/HliB Stress Proteins with Photosystem 1 Trimers and Monomers of the Cyanobacterium Synechocystis PCC 6803.

    PubMed

    Akulinkina, D V; Bolychevtseva, Yu V; Elanskaya, I V; Karapetyan, N V; Yurina, N P

    2015-10-01

    Hlip (high light-inducible proteins) are important for protection of the photosynthetic apparatus of cyanobacteria from light stress. However, the interaction of these proteins with chlorophyll-protein complexes of thylakoids remains unclear. The association of HliA/HliB stress proteins with photosystem 1 (PS1) complexes of the cyanobacterium Synechocystis PCC 6803 was studied to understand their function. Western blotting demonstrated that stress-induced HliA/HliB proteins are associated with PS1 trimers in wild-type cells grown under moderate light condition (40 µmol photons/m(2) per sec). The content of these proteins increased 1.7-fold after light stress (150 µmol photons/m(2) per sec) for 1 h. In the absence of PS1 trimers (?psaL mutant), the HliA/HliB proteins are associated with PS1 monomers and the PS2 complex. HliA/HliB proteins are associated with PS1 monomers but not with PS1 trimers in Synechocystis PS2-deficient mutant grown at 5 µmol photons/m(2) per sec; the content of Hli proteins associated with PS1 monomers increased 1.2-fold after light stress. The HliA/HliB proteins were not detected in wild-type cells of cyanobacteria grown in glucose-supplemented medium at 5 µmol photons/m(2) per sec, but light stress induces the synthesis of stress proteins associated with PS1 trimers. Thus, for the first time, the association of HliA/HliB proteins not only with PS1 trimers, but also with PS1 monomers is shown, which suggests a universal role of these proteins in the protection of the photosynthetic apparatus from excess light. PMID:26567568

  2. Psb28 protein is involved in the biogenesis of the photosystem II inner antenna CP47 (PsbB) in the cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Dobáková, Marika; Sobotka, Roman; Tichý, Martin; Komenda, Josef

    2009-02-01

    The role of the Psb28 protein in the structure and function of the photosystem II (PSII) complex has been studied in the cyanobacterium Synechocystis sp. PCC 6803. The protein was localized in the membrane fraction and, whereas most of the protein was detected as an unassembled protein, a small portion was found in the PSII core complex lacking the CP43 antenna (RC47). The association of Psb28 with RC47 was further confirmed by preferential isolation of RC47 from the strain containing a histidine-tagged derivative of Psb28 using nickel-affinity chromatography. However, the affinity-purified fraction also contained a small amount of the unassembled PSII inner antenna CP47 bound to Psb28-histidine, indicating a structural relationship between Psb28 and CP47. A psb28 deletion mutant exhibited slower autotrophic growth than wild type, although the absence of Psb28 did not affect the functional properties of PSII. The mutant showed accelerated turnover of the D1 protein, faster PSII repair, and a decrease in the cellular content of PSI. Radioactive labeling revealed a limitation in the synthesis of both CP47 and the PSI subunits PsaA/PsaB in the absence of Psb28. The mutant cells contained a high level of magnesium protoporphyrin IX methylester, a decreased level of protochlorophyllide, and released large quantities of protoporphyrin IX into the medium, indicating inhibition of chlorophyll (Chl) biosynthesis at the cyclization step yielding the isocyclic ring E. Overall, our results show the importance of Psb28 for synthesis of Chls and/or apoproteins of Chl-binding proteins CP47 and PsaA/PsaB. PMID:19036835

  3. Synthesis of ZnO nanoparticles using the cell extract of the cyanobacterium, Anabaena strain L31 and its conjugation with UV-B absorbing compound shinorine.

    PubMed

    Singh, Garvita; Babele, Piyoosh K; Kumar, Ashok; Srivastava, Anup; Sinha, Rajeshwar P; Tyagi, Madhu B

    2014-09-01

    In the present work, we describe a cheap, unexplored and simple procedure for the synthesis of zinc oxide nanoparticles (ZnONPs) using the cell extract of the cyanobacterium, Anabaena strain L31. An attempt was also made to conjugate synthesized ZnONPs with a UV-absorbing water soluble compound shinorine. UV-vis spectroscopy, X-ray diffraction (XRD), Fourier transform infra-red (FTIR) spectroscopy, transmission electron microscopy (TEM) and TEM-selected area electron diffraction (SAED) analyses were made to elucidate the formation and characterization of ZnONPs and ZnONPs-shinorine conjugate. The synthesized ZnONPs were characterized by a sharp peak at 370 nm in UV-vis spectrum. TEM images showed the formation of spherical shaped nanoparticles with an average size of 80 nm. Results of selective area electron diffraction (SAED) pattern showed a set of rings which suggested uniform shape with hexagonal structure of ZnONPs. XRD spectra confirmed the crystalline structure of particles. Conjugation of ZnONPs with shinorine was successfully achieved at pH 7.0 and 10mM concentration of shinorine. The conjugate showed a zeta potential value of -3.75 mV as compared to +30.25 mV of ZnONPs. The change in zeta potential value of ZnONPs-shinorine conjugate was attributed to the changes in the surface functionalities after conjugation. The generation of in vivo reactive oxygen species (ROS) by Anabaena strain L31 with treatment of ZnONPs-shinorine conjugate showed approximately 75% less ROS generation as compared to ZnONPs. Properties exhibited by the ZnONPs-shinorine conjugate suggest that it may be used as a potential agent in developing environmental-friendly sunscreen filters of biological origin. PMID:24911272

  4. The Tryptophan-Rich Sensory Protein (TSPO) is Involved in Stress-Related and Light-Dependent Processes in the Cyanobacterium Fremyella diplosiphon

    PubMed Central

    Busch, Andrea W. U.; Montgomery, Beronda L.

    2015-01-01

    The tryptophan-rich sensory protein (TSPO) is a membrane protein, which is a member of the 18 kDa translocator protein/peripheral-type benzodiazepine receptor (MBR) family of proteins that is present in most organisms and is also referred to as Translocator protein 18 kDa. Although TSPO is associated with stress- and disease-related processes in organisms from bacteria to mammals, full elucidation of the functional role of the TSPO protein is lacking for most organisms in which it is found. In this study, we describe the regulation and function of a TSPO homolog in the cyanobacterium Fremyella diplosiphon, designated FdTSPO. Accumulation of the FdTSPO transcript is upregulated by green light and in response to nutrient deficiency and stress. A F. diplosiphon TSPO deletion mutant (i.e., ?FdTSPO) showed altered responses compared to the wild type (WT) strain under stress conditions, including salt treatment, osmotic stress, and induced oxidative stress. Under salt stress, the FdTSPO transcript is upregulated and a ?FdTSPO mutant accumulates lower levels of reactive oxygen species (ROS) and displays increased growth compared to WT. In response to osmotic stress, FdTSPO transcript levels are upregulated and ?FdTSPO mutant cells exhibit impaired growth compared to the WT. By comparison, methyl viologen-induced oxidative stress results in higher ROS levels in the ?FdTSPO mutant compared to the WT strain. Taken together, our results provide support for the involvement of membrane-localized FdTSPO in mediating cellular responses to stress in F. diplosiphon and represent detailed functional analysis of a cyanobacterial TSPO. This study advances our understanding of the functional roles of TSPO homologs in vivo. PMID:26696996

  5. Salt stress induces a decrease in excitation energy transfer from phycobilisomes to photosystem II but an increase to photosystem I in the cyanobacterium Spirulina platensis.

    PubMed

    Zhang, Tao; Gong, Hongmei; Wen, Xiaogang; Lu, Congming

    2010-08-15

    The effects of salt stress (0-0.8M NaCl) on excitation energy transfer from phycobilisomes to photosystem I (PSI) and photosystem II (PSII) in the cyanobacterium Spirulina platensis were investigated. Salt stress resulted in a significant decrease in photosynthetic oxygen evolution activity and PSII electron transport activity, but a significant increase in PSI electron transport activity. Analyses of the polyphasic fluorescence transients (OJIP) showed that, with an increase in salt concentration, the fluorescence yield at the phases J, I and P declined considerably and the transient almost leveled off at 0.8M NaCl. Analyses of the JIP test demonstrated that salt stress led to a decrease in the maximal efficiency of PSII photochemistry, the probability of electron transfer beyond Q(A), and the yield of electron transport beyond Q(A). In addition, salt stress resulted in a decrease in the electron transport per PSII reaction center, but an increase in the absorption per PSII reaction center. However, there was no significant change in the trapping per PSII reaction center. Furthermore, there was a decrease in the concentration of the active PSII reaction centers. Analyses of 77K chlorophyll fluorescence emission spectra excited either at 436 or 580nm showed that salt stress inhibited excitation energy transfer from phycobilisomes to PSII but induced an increase in the efficiency of energy transfer from phycobilisomes to PSI. Based on these results, it is suggested that, through a down-regulation of PSII reaction centers and a shift of excitation energy transfer in favor of PSI, the PSII apparatus was protected from excess excitation energy. PMID:20417984

  6. Is Monoglucosyldiacylglycerol a Precursor to Monogalactosyldiacylglycerol in All Cyanobacteria?

    PubMed

    Sato, Naoki

    2015-10-01

    Monogalactosyldiacylglycerol (MGDG) is ubiquitous in the photosynthetic membranes of cyanobacteria and chloroplasts. It is synthesized by galactosylation of diacylglycerol (DAG) in the chloroplasts, whereas it is produced by epimerization of monoglucosyldiacylglycerol (GlcDG) in at least several cyanobacteria that have been analyzed such as Synechocystis sp. PCC 6803. A previous study, however, showed that the mgdE gene encoding the epimerase is absent in some cyanobacteria such as Gloeobacter violaceus, Thermosynechococcus elongatus and Acaryochloris marina. In addition, the N-terminal 'fatty acid hydroxylase' domain is lacking in the MgdE protein of Prochlorococcus marinus. These problems may cast doubt upon the general (or exclusive) role of MgdE in the epimerization of GlcDG to MGDG in cyanobacteria. In addition, GlcDG is usually present at a very low level, and the structural determination of endogenous GlcDG has not been accomplished with cyanobacterial samples. In this study, I determined the structure of GlcDG from Anabaena variabilis by (1)H- and (13)C-nuclear magnetic resonance (NMR) spectroscopy. I then showed that G. violaceus, T. elongatus, A. marina and P. marinus contain GlcDG. In all cases, GlcDG consisted of fewer unsaturated molecular species than MGDG, providing further evidence that GlcDG is a precursor to MGDG. The conversion of GlcDG to MGDG was also demonstrated by radiolabeling and chase experiments in G. violaceus and P. marinus. These results demonstrate that all the analyzed cyanobacteria contain GlcDG, which is converted to MGDG, and suggest that an alternative epimerase is required for MGDG synthesis in these cyanobacteria. PMID:26276824

  7. HYDROGEN PRODUCTION BY THE CYANOBACTERIUM PLECTONEMA BORYANUM: EFFECTS OF INITIAL NITRATE CONCENTRATION, LIGHT INTENSITY, AND INHIBITION OF PHOTOSYSTEM II BY DCMU

    SciTech Connect

    Carter, B.; Huesemann, M.

    2008-01-01

    The alarming rate at which atmospheric carbon dioxide levels are increasing due to the burning of fossil fuels will have incalculable consequences if disregarded. Fuel cells, a source of energy that does not add to carbon dioxide emissions, have become an important topic of study. Although signifi cant advances have been made related to fuel cells, the problem of cheap and renewable hydrogen production still remains. The cyanobacterium Plectonema boryanum has demonstrated potential as a resolution to this problem by producing hydrogen under nitrogen defi cient growing conditions. Plectonema boryanum cultures were tested in a series of experiments to determine the effects of light intensity, initial nitrate concentration, and photosystem II inhibitor DCMU (3-(3,4- dichlorophenyl)-1,1-dimethylurea) upon hydrogen production. Cultures were grown in sterile Chu. No. 10 medium within photobioreactors constantly illuminated by halogen lights. Because the enzyme responsible for hydrogen production is sensitive to oxygen, the medium was continuously sparged with argon/CO2 (99.7%/0.3% vol/vol) by gas dispersion tubes immersed in the culture. Hydrogen production was monitored by using a gas chromatograph equipped with a thermal conductivity detector. In the initial experiment, the effects of initial nitrate concentration were tested and results revealed cumulative hydrogen production was maximum at an initial nitrate concentration of 1 mM. A second experiment was then conducted at an initial nitrate concentration of 1 mM to determine the effects of light intensity at 50, 100, and 200 ?mole m-2 s-1. Cumulative hydrogen production increased with increasing light intensity. A fi nal experiment, conducted at an initial nitrate concentration of 2 mM, tested the effects of high light intensity at 200 and 400 ?mole m-2 s-1. Excessive light at 400 ?mole m-2 s-1 decreased cumulative hydrogen production. Based upon all experiments, cumulative hydrogen production rates were optimal at an initial nitrate concentration of 1 mM and a light intensity of 100 ?mole m-2 s-1. DCMU was shown in all experiments to severely decrease hydrogen production as time progressed. With the information acquired so far, future experiments with reducing substances could determine maximum rates of hydrogen production. If maximum hydrogen production rates proved to be large enough, Plectonema boryanum could be grown on an industrial scale to provide hydrogen gas as a renewable fuel.

  8. Extracellular polymeric substances buffer against the biocidal effect of H2O2 on the bloom-forming cyanobacterium Microcystis aeruginosa.

    PubMed

    Gao, Lei; Pan, Xiangliang; Zhang, Daoyong; Mu, Shuyong; Lee, Duu-Jong; Halik, Umut

    2015-02-01

    H2O2 is an emerging biocide for bloom-forming cyanobacteria. It is important to investigate the H2O2 scavenging ability of extracellular polymeric substances (EPS) of cyanobacteria because EPS with strong antioxidant activity may "waste" considerable amounts of H2O2 before it kills the cells. In this study, the buffering capacity against H2O2 of EPS from the bloom-forming cyanobacterium Microcystis aeruginosa was investigated. IC50 values for the ability of EPS and vitamin C (VC) to scavenge 50% of the initial H2O2 concentration were 0.097 and 0.28 mg mL(-1), respectively, indicating the higher H2O2 scavenging activity of EPS than VC. Both proteins and polysaccharides are significantly decomposed by H2O2 and the polysaccharides were more readily decomposed than proteins. H2O2 consumed by the EPS accounted for 50% of the total amount of H2O2 consumed by the cells. Cell growth and photosynthesis were reduced more for EPS-free cells than EPS coated cells when the cells were treated with 0.1 or 0.2 mg mL(-1) H2O2, and the maximum photochemical efficiency Fv/Fm of EPS coated cells recovered to higher values than EPS-free cells. Concentrations of H2O2 above 0.3 mg mL(-1) completely inhibited photosynthesis and no recovery was observed for both EPS-free and EPS coated cells. This shows that EPS has some buffering capacity against the killing effect of H2O2 on cyanobacterial cells. Such a strong H2O2 scavenging ability of EPS is not favorable for killing bloom-forming cyanobacteria. The high H2O2 scavenging capacity means considerable amounts of H2O2 have to be used to break through the EPS barrier before H2O2 exerts any killing effects on the cells. It is therefore necessary to determine the H2O2 scavenging capacity of the EPS of various bloom-forming cyanobacteria so that the cost-effective amount of H2O2 needed to be used for killing the cyanobacteria can be estimated. PMID:25463931

  9. Transcript Profiling Reveals New Insights into the Acclimation of the Mesophilic Fresh-Water Cyanobacterium Synechococcus elongatus PCC 7942 to Iron Starvation1[W

    PubMed Central

    Nodop, Anke; Pietsch, Daniel; Höcker, Ralf; Becker, Anke; Pistorius, Elfriede K.; Forchhammer, Karl; Michel, Klaus-Peter

    2008-01-01

    The regulatory network for acclimation of the obligate photoautotrophic fresh water cyanobacterium Synechococcus elongatus PCC 7942 to iron (Fe) limitation was studied by transcript profiling with an oligonucleotide whole genome DNA microarray. Six regions on the chromosome with several Fe-regulated genes each were identified. The irpAB and fut region encode putative Fe uptake systems, the suf region participates in [Fe-sulfur] cluster assembly under oxidative stress and Fe limitation, the isiAB region encodes CP43? and flavodoxin, the idiCB region encodes the NuoE-like electron transport associated protein IdiC and the transcriptional activator IdiB, and the ackA/pgam region encodes an acetate kinase and a phosphoglycerate mutase. We also investigated the response of two S. elongatus PCC 7942 mutants to Fe starvation. These were mutant K10, lacking IdiB but containing IdiC, and mutant MuD, representing a idiC-merodiploid mutant with a strongly reduced amount of IdiC as well as IdiB. The absence of IdiB in mutant K10 or the strongly reduced amount of IdiB in mutant MuD allowed for the identification of additional members of the Fe-responsive IdiB regulon. Besides idiA and the irpAB operon somB(1), somA(2), ftr1, ackA, pgam, and nat also seem to be regulated by IdiB. In addition to the reduced amount of IdiB in MuD, the low concentration of IdiC may be responsible for a number of additional changes in the abundance of mainly photosynthesis-related transcripts as compared to the wild type and mutant K10. This fact may explain why it has been impossible to obtain a fully segregated IdiC-free mutant, whereas it was possible to obtain a fully segregated IdiB-free mutant. PMID:18424627

  10. Exposure of the cyanobacterium Nostoc muscorum from Portuguese rice fields to Molinate (Ordram(®)): Effects on the antioxidant system and fatty acid profile.

    PubMed

    Galhano, Victor; Gomes-Laranjo, José; Peixoto, Francisco

    2011-01-25

    Herbicide contamination of aquatic ecosystems is a serious global environmental concern. Several herbicides enhance the intracellular formation of reactive oxygen species, and can lead to the damage of macromolecules and to a decrease of oxidant defenses in a wide range of non-target microorganisms including cyanobacteria. The effects of molinate (a thiocarbamate herbicide used for controlling grassy weeds in rice fields) on the activities of antioxidant enzymes such as superoxide dismutase, catalase, ascorbate peroxidase, glutathione reductase, and glutathione S-transferase were evaluated in Nostoc muscorum, a freshwater cyanobacterium with a significant spread in Portuguese rice fields. These were determined in N. muscorum cultures acutely (72h) exposed to concentrations ranging from 0.75 to 2mM of molinate. This study also analyzed the effects of molinate on: (1) the nonenzymatic antioxidant contents (reduced and oxidized glutathione, carotenoids, and proline), (2) the oxidative cell damage measured in terms of lipid peroxidation (MDA level) and electrolyte leakage (intactness of plasma membrane), and (3) the total fatty acid profile. The results showed that the activities of all antioxidant enzymes decreased dramatically with the rising concentration of molinate after 72h. Time-dependent and concentration-dependent increase in MDA and enhanced cell membrane leakage were indicative of lipid peroxidation, formation of free radicals and oxidative damage. Compared to control, 72-h herbicide exposure increased lipid peroxidation by 5.4%, 19% and 28% with 0.75, 1.5 and 2mM of molinate, respectively. Similarly, herbicide stress induced an increase in electrolyte leakage (5.8%, 29.5% and 30.2% above control, with 0.75, 1.5 and 2mM of molinate, respectively). The increased production of proline at higher molinate concentrations (the values rose above control by 45%, 95% and 156% with 0.75, 1.5 and 2mM, respectively) indicated the involvement of this osmoprotectant in a free radical scavenging mechanism. Moreover, a radical decline in both glutathione pool, carotenoids and saturated fatty acids were also observed. The results of the present study lead us to conclude that: (1) both enzymatic and nonenzymatic antioxidative defense system of N. muscorum are dramatically affected by molinate, (2) the herbicide induces peroxidation, (3) it contributes to an increase of the unsaturation level of cell membrane fatty acids. These evidences should be taken in account when using N. muscorum as an environmental indicator species in studies of herbicide biotransformation and biomarker response as well as in environmental monitoring programmes. PMID:21216347

  11. First record of a Mermithidae (Nematoda) from the meloid beetle Meloe violaceus Marsham, 1802 (Coleoptera: Meloidae).

    PubMed

    Lückmann, Johannes; Poinar, George O

    2003-05-01

    A new record of nematode parasitism of meloid beetles is reported and all earlier records are summarised. Rates of parasitism could be influenced by the toxic compound cantharidin that these beetles possess. PMID:12743809

  12. 2-epi-5-epi-Valiolone synthase activity is essential for maintaining phycobilisome composition in the cyanobacterium Anabaena variabilis ATCC 29413 when grown in the presence of a carbon source.

    PubMed

    Spence, Edward; Bryan, Samantha J; Lisfi, Mohamed; Cullum, John; Dunlap, Walter C; Shick, J Malcolm; Mullineaux, Conrad W; Long, Paul F

    2013-09-01

    The cyclase 2-epi-5-epi-valiolone synthase (EVS) is reported to be a key enzyme for biosynthesis of the mycosporine-like amino acid shinorine in the cyanobacterium Anabaena variabilis ATCC 29413. Subsequently, we demonstrated that an in-frame complete deletion of the EVS gene had little effect on in vivo production of shinorine. Complete segregation of the EVS gene deletion mutant proved difficult and was achieved only when the mutant was grown in the dark and in a medium supplemented with fructose. The segregated mutant showed a striking colour change from native blue-green to pale yellow-green, corresponding to substantial loss of the photosynthetic pigment phycocyanin, as evinced by combinations of absorbance and emission spectra. Transcriptional analysis of the mutant grown in the presence of fructose under dark or light conditions revealed downregulation of the cpcA gene that encodes the alpha subunit of phycocyanin, whereas the gene encoding nblA, a protease chaperone essential for phycobilisome degradation, was not expressed. We propose that the substrate of EVS (sedoheptulose 7-phosphate) or possibly lack of its EVS-downstream products, represses transcription of cpcA to exert a hitherto unknown control over photosynthesis in this cyanobacterium. The significance of this finding is enhanced by phylogenetic analyses revealing horizontal gene transfer of the EVS gene of cyanobacteria to fungi and dinoflagellates. It is also conceivable that the EVS gene has been transferred from dinoflagellates, as evident in the host genome of symbiotic corals. A role of EVS in regulating sedoheptulose 7-phosphate concentrations in the photophysiology of coral symbiosis is yet to be determined. PMID:23857509

  13. The BOSS and BIOMEX space experiments on the EXPOSE-R2 mission: Endurance of the desert cyanobacterium Chroococcidiopsis under simulated space vacuum, Martian atmosphere, UVC radiation and temperature extremes.

    NASA Astrophysics Data System (ADS)

    Baqué, Mickael; de Vera, Jean-Pierre; Rettberg, Petra; Billi, Daniela

    2013-10-01

    The proposed space experiments BOSS (Biofilm Organisms Surfing Space) and BIOMEX (BIOlogy and Mars experiment) will take place on the space exposure facility EXPOSE-R2 on the International Space Station (ISS), which is set to be launched in 2014. In BOSS the hypothesis to be tested is that microorganisms grown as biofilms, hence embedded in self-produced extracellular polymeric substances, are more tolerant to space and Martian conditions compared to their planktonic counterparts. Various microbial biofilms have been developed including those obtained from the cyanobacterium Chroococcidiopsis isolated from hot and cold deserts. The prime objective of BIOMEX is to evaluate to what extent biomolecules are resistant to, and can maintain their stability under, space and Mars-like conditions; therefore a variety of pigments and cell components are under investigation to establish a biosignature data base; e.g. a Raman spectral library to be used for extraterrestrial life biosignatures. The secondary objective of BIOMEX is to investigate the endurance of extremophiles, focusing on their interactions with Lunar and Martian mineral analogues. Ground-based studies are currently being carried out in the framework of EVTs (Experiment Verification Tests) by exposing selected organisms to space and Martian simulations. Results on a desert strain of Chroococcidiopsis obtained from the first set of EVT, e.g. space vacuum, Mars atmosphere, UVC radiation, temperature cycles and extremes, suggested that dried biofilms exhibited an enhanced survival compared to planktonic lifestyle. Moreover the protection provided by a Martian mineral analogue (S-MRS) to the sub-cellular integrities of Chroococcidiopsis against UVC radiation supports the endurance of this cyanobacterium under extraterrestrial conditions and its relevance in the development of life detection strategies.

  14. Identification of two homologous genes, chlAI and chlAII, that are differentially involved in isocyclic ring formation of chlorophyll a in the cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Minamizaki, Kei; Mizoguchi, Tadashi; Goto, Takeaki; Tamiaki, Hitoshi; Fujita, Yuichi

    2008-02-01

    The isocyclic ring (E-ring) is a common structural feature of chlorophylls. The E-ring is formed by two structurally unrelated Mg-protoporphyrin IX monomethylester (MPE) cyclase systems, oxygen-dependent (AcsF), and oxygen-independent (BchE) systems, which involve incorporation of an oxygen atom from molecular oxygen and water into the C-13(1) position of MPE, respectively. Which system operates in cyanobacteria that can thrive in a variety of anaerobic environments remains an open question. The cyanobacterium Synechocystis sp. PCC 6803 has two acsF-like genes, sll1214 (chlA(I)) and sll1874 (chlA(II)), and three bchE-like genes, slr0905, sll1242, and slr0309. Five mutants lacking one of these genes were isolated. The DeltachlA(I) mutant failed to grow under aerobic conditions with anomalous accumulation of a pigment with fluorescence emission peak at 595 nm, which was identified 3,8-divinyl MPE by high-performance liquid chromatography-mass spectrometry analysis. The growth defect of DeltachlA(I) was restored by the cultivation under oxygen-limited (micro-oxic) conditions. MPE accumulation was also detected in DeltachlA(II) grown under microoxic conditions, but not in any of the bchE mutants. The phenotype was consistent with the expression pattern of two chlA genes: chlA(II) was induced under micro-oxic conditions in contrast to the constitutive expression of chlA(I). These findings suggested that ChlA(I) is the sole MPE cyclase system under aerobic conditions and that the induced ChlA(II) operates together with ChlA(I) under micro-oxic conditions. In addition, the accumulation of 3,8-divinyl MPE in the DeltachlA mutants suggested that the reduction of 8-vinyl group occurs after the formation of E-ring in Synechocystis sp. PCC 6803. PMID:18039649

  15. Isoflurane alters the structure and dynamics of GLIC.

    PubMed

    Willenbring, Dan; Liu, Lu Tian; Mowrey, David; Xu, Yan; Tang, Pei

    2011-10-19

    Pentameric ligand-gated ion channels are targets of general anesthetics. Although the search for discrete anesthetic binding sites has achieved some degree of success, little is known regarding how anesthetics work after the events of binding. Using the crystal structures of the bacterial Gloeobacter violaceus pentameric ligand-gated ion channel (GLIC), which is sensitive to a variety of general anesthetics, we performed multiple molecular dynamics simulations in the presence and absence of the general anesthetic isoflurane. Isoflurane bound to several locations within GLIC, including the transmembrane pocket identified crystallographically, the extracellular (EC) domain, and the interface of the EC and transmembrane domains. Isoflurane also entered the channel after the pore was dehydrated in one of the simulations. Isoflurane disrupted the quaternary structure of GLIC, as evidenced in a striking association between the binding and breakage of intersubunit salt bridges in the EC domain. The pore-lining helix experienced lateral and inward radial tilting motion that contributed to the channel closure. Isoflurane binding introduced strong anticorrelated motions between different subunits of GLIC. The demonstrated structural and dynamical modulations by isoflurane aid in the understanding of the underlying mechanism of anesthetic inhibition of GLIC and possibly other homologous pentameric ligand-gated ion channels. PMID:22004744

  16. Multisite Binding of a General Anesthetic to the Prokaryotic Pentameric Erwinia chrysanthemi Ligand-gated Ion Channel (ELIC)*

    PubMed Central

    Spurny, Radovan; Billen, Bert; Howard, Rebecca J.; Brams, Marijke; Debaveye, Sarah; Price, Kerry L.; Weston, David A.; Strelkov, Sergei V.; Tytgat, Jan; Bertrand, Sonia; Bertrand, Daniel; Lummis, Sarah C. R.; Ulens, Chris

    2013-01-01

    Pentameric ligand-gated ion channels (pLGICs), such as nicotinic acetylcholine, glycine, ?-aminobutyric acid GABAA/C receptors, and the Gloeobacter violaceus ligand-gated ion channel (GLIC), are receptors that contain multiple allosteric binding sites for a variety of therapeutics, including general anesthetics. Here, we report the x-ray crystal structure of the Erwinia chrysanthemi ligand-gated ion channel (ELIC) in complex with a derivative of chloroform, which reveals important features of anesthetic recognition, involving multiple binding at three different sites. One site is located in the channel pore and equates with a noncompetitive inhibitor site found in many pLGICs. A second transmembrane site is novel and is located in the lower part of the transmembrane domain, at an interface formed between adjacent subunits. A third site is also novel and is located in the extracellular domain in a hydrophobic pocket between the ?7–?10 strands. Together, these results extend our understanding of pLGIC modulation and reveal several specific binding interactions that may contribute to modulator recognition, further substantiating a multisite model of allosteric modulation in this family of ion channels. PMID:23364792

  17. Isoflurane Alters the Structure and Dynamics of GLIC

    PubMed Central

    Willenbring, Dan; Liu, Lu Tian; Mowrey, David; Xu, Yan; Tang, Pei

    2011-01-01

    Pentameric ligand-gated ion channels are targets of general anesthetics. Although the search for discrete anesthetic binding sites has achieved some degree of success, little is known regarding how anesthetics work after the events of binding. Using the crystal structures of the bacterial Gloeobacter violaceus pentameric ligand-gated ion channel (GLIC), which is sensitive to a variety of general anesthetics, we performed multiple molecular dynamics simulations in the presence and absence of the general anesthetic isoflurane. Isoflurane bound to several locations within GLIC, including the transmembrane pocket identified crystallographically, the extracellular (EC) domain, and the interface of the EC and transmembrane domains. Isoflurane also entered the channel after the pore was dehydrated in one of the simulations. Isoflurane disrupted the quaternary structure of GLIC, as evidenced in a striking association between the binding and breakage of intersubunit salt bridges in the EC domain. The pore-lining helix experienced lateral and inward radial tilting motion that contributed to the channel closure. Isoflurane binding introduced strong anticorrelated motions between different subunits of GLIC. The demonstrated structural and dynamical modulations by isoflurane aid in the understanding of the underlying mechanism of anesthetic inhibition of GLIC and possibly other homologous pentameric ligand-gated ion channels. PMID:22004744

  18. Poles Apart: Arctic and Antarctic Octadecabacter strains Share High Genome Plasticity and a New Type of Xanthorhodopsin

    PubMed Central

    Vollmers, John; Voget, Sonja; Dietrich, Sascha; Gollnow, Kathleen; Smits, Maike; Meyer, Katja; Brinkhoff, Thorsten; Simon, Meinhard; Daniel, Rolf

    2013-01-01

    The genus Octadecabacter is a member of the ubiquitous marine Roseobacter clade. The two described species of this genus, Octadecabacter arcticus and Octadecabacter antarcticus, are psychrophilic and display a bipolar distribution. Here we provide the manually annotated and finished genome sequences of the type strains O. arcticus 238 and O. antarcticus 307, isolated from sea ice of the Arctic and Antarctic, respectively. Both genomes exhibit a high genome plasticity caused by an unusually high density and diversity of transposable elements. This could explain the discrepancy between the low genome synteny and high 16S rRNA gene sequence similarity between both strains. Numerous characteristic features were identified in the Octadecabacter genomes, which show indications of horizontal gene transfer and may represent specific adaptations to the habitats of the strains. These include a gene cluster encoding the synthesis and degradation of cyanophycin in O. arcticus 238, which is absent in O. antarcticus 307 and unique among the Roseobacter clade. Furthermore, genes representing a new subgroup of xanthorhodopsins as an adaptation to icy environments are present in both Octadecabacter strains. This new xanthorhodopsin subgroup differs from the previously characterized xanthorhodopsins of Salinibacter ruber and Gloeobacter violaceus in phylogeny, biogeography and the potential to bind 4-keto-carotenoids. Biochemical characterization of the Octadecabacter xanthorhodopsins revealed that they function as light-driven proton pumps. PMID:23671678

  19. A chimeric prokaryotic pentameric ligand-gated channel reveals distinct pathways of activation.

    PubMed

    Schmandt, Nicolaus; Velisetty, Phanindra; Chalamalasetti, Sreevatsa V; Stein, Richard A; Bonner, Ross; Talley, Lauren; Parker, Mark D; Mchaourab, Hassane S; Yee, Vivien C; Lodowski, David T; Chakrapani, Sudha

    2015-10-01

    Recent high resolution structures of several pentameric ligand-gated ion channels have provided unprecedented details of their molecular architecture. However, the conformational dynamics and structural rearrangements that underlie gating and allosteric modulation remain poorly understood. We used a combination of electrophysiology, double electron-electron resonance (DEER) spectroscopy, and x-ray crystallography to investigate activation mechanisms in a novel functional chimera with the extracellular domain (ECD) of amine-gated Erwinia chrysanthemi ligand-gated ion channel, which is activated by primary amines, and the transmembrane domain of Gloeobacter violaceus ligand-gated ion channel, which is activated by protons. We found that the chimera was independently gated by primary amines and by protons. The crystal structure of the chimera in its resting state, at pH 7.0 and in the absence of primary amines, revealed a closed-pore conformation and an ECD that is twisted with respect to the transmembrane region. Amine- and pH-induced conformational changes measured by DEER spectroscopy showed that the chimera exhibits a dual mode of gating that preserves the distinct conformational changes of the parent channels. Collectively, our findings shed light on both conserved and divergent features of gating mechanisms in this class of channels, and will facilitate the design of better allosteric modulators. PMID:26415570

  20. Proton gradients in intact cyanobacteria

    NASA Technical Reports Server (NTRS)

    Belkin, S.; Mehlhorn, R. J.; Packer, L.

    1987-01-01

    The internal pH values of two unicellular cyanobacterial strains were determined with electron spin resonance probes, over an external pH range of 6 to 9, in the light and in the dark. The slow growing, thylakoid-lacking Gloeobacter violaceus was found to have a low capacity for maintaining a constant internal pH. The distribution pattern of weak acid and amine nitroxide spin probes across the cell membranes of this organism, in the light and in the dark, was consistent with the assumption that it contains a single intracellular compartment. At an external pH of 7.0, intracellular pH was 6.8 in the dark and 7.2 in the light. The cells of Agmenellum quadruplicatum, a marine species, were found to contain two separate compartments; in the dark, the pH of the cytoplasmic and the intrathylakoid spaces were calculated to be 7.2 and 5.5, respectively. Upon illumination, the former increased and the latter decreased by about 0.5 pH units.

  1. Experimental determination of the vertical alignment between the second and third transmembrane segments of muscle nicotinic acetylcholine receptors

    PubMed Central

    Mnatsakanyan, Nelli; Jansen, Michaela

    2013-01-01

    Nicotinic acetylcholine receptors (nAChR) are members of the Cys-loop ligand-gated ion channel superfamily. Muscle nAChR are heteropentamers that assemble from two ?, and one each of ?, ?, and ? subunits. Each subunit is composed of three domains, extracellular, transmembrane and intracellular. The transmembrane domain consists of four ?-helical segments (M1–M4). Pioneering structural information was obtained using electronmicroscopy of Torpedo nAChR. The recently-solved X-ray structure of the first eukaryotic Cys-loop receptor, a truncated (intracellular domain missing) glutamate-gated chloride channel ? (GluCl?)showed the same overall architecture . However, a significant difference with regard to the vertical alignment between the channel-lining segment M2 and segment M3 was observed. Here we used functional studies utilizing disulfide trapping experiments in muscle nAChR to determine the spatial orientation between M2 and M3. Our results are in agreement with the vertical alignment as obtained when using the GluCl? structure as a template to homology model muscle nAChR, however, they cannot be reconciled with the current Torpedo nAChR model. The vertical M2–M3 alignments as observed in X-ray structures of prokaryotic Gloeobacter violaceus ligand-gated ion channel (GLIC) and GluCl? are in agreement. Our results further confirm that this alignment in Cys-loop receptors is conserved between prokaryotes and eukaryotes. PMID:23565737

  2. Structural basis for potentiation by alcohols and anaesthetics in a ligand-gated ion channel

    PubMed Central

    Sauguet, Ludovic; Howard, Rebecca J.; Malherbe, Laurie; Lee, Ui S.; Corringer, Pierre-Jean; Harris, R. Adron; Delarue, Marc

    2014-01-01

    Ethanol alters nerve signalling by interacting with proteins in the central nervous system, particularly pentameric ligand-gated ion channels. A recent series of mutagenesis experiments on Gloeobacter violaceus ligand-gated ion channel, a prokaryotic member of this family, identified a single-site variant that is potentiated by pharmacologically relevant concentrations of ethanol. Here we determine crystal structures of the ethanol-sensitized variant in the absence and presence of ethanol and related modulators, which bind in a transmembrane cavity between channel subunits and may stabilize the open form of the channel. Structural and mutagenesis studies defined overlapping mechanisms of potentiation by alcohols and anaesthetics via the inter-subunit cavity. Furthermore, homology modelling show this cavity to be conserved in human ethanol-sensitive glycine and GABA(A) receptors, and to involve residues previously shown to influence alcohol and anaesthetic action on these proteins. These results suggest a common structural basis for ethanol potentiation of an important class of targets for neurological actions of ethanol. PMID:23591864

  3. Mutational analysis of photosystem I polypeptides in the cyanobacterium Synechocystis sp. PCC 6803. Targeted inactivation of psaI reveals the function of psaI in the structural organization of psaL

    NASA Technical Reports Server (NTRS)

    Xu, Q.; Hoppe, D.; Chitnis, V. P.; Odom, W. R.; Guikema, J. A.; Chitnis, P. R.; Spooner, B. S. (Principal Investigator)

    1995-01-01

    We cloned, characterized, and inactivated the psaI gene encoding a 4-kDa hydrophobic subunit of photosystem I from the cyanobacterium Synechocystis sp. PCC 6803. The psaI gene is located 90 base pairs downstream from psaL, and is transcribed on 0.94- and 0.32-kilobase transcripts. To identify the function of PsaI, we generated a cyanobacterial strain in which psaI has been interrupted by a gene for chloramphenicol resistance. The wild-type and the mutant cells showed comparable rates of photoautotrophic growth at 25 degrees C. However, the mutant cells grew slower and contained less chlorophyll than the wild-type cells, when grown at 40 degrees C. The PsaI-less membranes from cells grown at either temperature showed a small decrease in NADP+ photoreduction rate when compared to the wild-type membranes. Inactivation of psaI led to an 80% decrease in the PsaL level in the photosynthetic membranes and to a complete loss of PsaL in the purified photosystem I preparations, but had little effect on the accumulation of other photosystem I subunits. Upon solubilization with nonionic detergents, photosystem I trimers could be obtained from the wild-type, but not from the PsaI-less membranes. The PsaI-less photosystem I monomers did not contain detectable levels of PsaL. Therefore, a structural interaction between PsaL and PsaI may stabilize the association of PsaL with the photosystem I core. PsaL in the wild-type and PsaI-less membranes showed equal resistance to removal by chaotropic agents. However, PsaL in the PsaI-less strain exhibited an increased susceptibility to proteolysis. From these data, we conclude that PsaI has a crucial role in aiding normal structural organization of PsaL within the photosystem I complex and the absence of PsaI alters PsaL organization, leading to a small, but physiologically significant, defect in photosystem I function.

  4. Phosphorus physiology of the marine cyanobacterium Trichodesmium

    E-print Network

    Orchard, Elizabeth Duncan

    2010-01-01

    Primary producers play a critical role in the oceanic food chain and the global cycling of carbon. The marine diazotroph Trichodesmium is a major contributor to both primary production and nitrogen fixation in the tropical ...

  5. Anesthetic Binding in a Pentameric Ligand-Gated Ion Channel: GLIC

    PubMed Central

    Chen, Qiang; Cheng, Mary Hongying; Xu, Yan; Tang, Pei

    2010-01-01

    Cys-loop receptors are molecular targets of general anesthetics, but the knowledge of anesthetic binding to these proteins remains limited. Here we investigate anesthetic binding to the bacterial Gloeobacter violaceus pentameric ligand-gated ion channel (GLIC), a structural homolog of cys-loop receptors, using an experimental and computational hybrid approach. Tryptophan fluorescence quenching experiments showed halothane and thiopental binding at three tryptophan-associated sites in the extracellular (EC) domain, transmembrane (TM) domain, and EC-TM interface of GLIC. An additional binding site at the EC-TM interface was predicted by docking analysis and validated by quenching experiments on the N200W GLIC mutant. The binding affinities (KD) of 2.3 ± 0.1 mM and 0.10 ± 0.01 mM were derived from the fluorescence quenching data of halothane and thiopental, respectively. Docking these anesthetics to the original GLIC crystal structure and the structures relaxed by molecular dynamics simulations revealed intrasubunit sites for most halothane binding and intersubunit sites for thiopental binding. Tryptophans were within reach of both intra- and intersubunit binding sites. Multiple molecular dynamics simulations on GLIC in the presence of halothane at different sites suggested that anesthetic binding at the EC-TM interface disrupted the critical interactions for channel gating, altered motion of the TM23 linker, and destabilized the open-channel conformation that can lead to inhibition of GLIC channel current. The study has not only provided insights into anesthetic binding in GLIC, but also demonstrated a successful fusion of experiments and computations for understanding anesthetic actions in complex proteins. PMID:20858424

  6. Molecular Dynamics and Brownian Dynamics Investigation of Ion Permeation and Anesthetic Halothane Effects on a Proton-gated Ion Channel

    PubMed Central

    Cheng, Mary Hongying; Coalson, Rob D.; Tang, Pei

    2011-01-01

    Bacterial Gloeobacter violaceus pentameric ligand-gated ion channel (GLIC) is activated to cation permeation upon lowering the solution pH. Its function can be modulated by anesthetic halothane. In the present work we integrate molecular dynamics (MD) and Brownian dynamics (BD) simulations to elucidate the ion conduction, charge selectivity and halothane modulation mechanisms in GLIC, based on recently resolved x-ray crystal structures of the open-channel GLIC. MD calculations of the potential mean force (PMF) for a Na+ revealed two energy barriers in the extracellular domain (R109 and K38) and at the hydrophobic gate of transmembrane domain (I233), respectively. An energy well for Na+ was near the intracellular entrance: the depth of this energy well was modulated strongly by the protonation state of E222. The energy barrier for Cl? was found to be 3–4 times higher than that for Na+. Ion permeation characteristics were determined through BD simulations using a hybrid MD/continuum electrostatics approach to evaluate the energy profiles governing the ion movement. The resultant channel conductance and a near-zero permeability ratio (PCl/PNa) were comparable to experimental data. Based on these calculations we suggest that a ring of five E222 residues may act as an electrostatic gate. In addition, the hydrophobic gate region may play a role in charge selectivity due to a higher dehydration energy barrier for Cl? ions. The effect of halothane on the Na+ PMF was also evaluated. Halothane was found to perturb salt bridges in GLIC that may be crucial for channel gating and open-channel stability, but had no significant impact on the single ion PMF profiles. PMID:20979415

  7. Macroscopic Kinetics of Pentameric Ligand Gated Ion Channels: Comparisons between Two Prokaryotic Channels and One Eukaryotic Channel

    PubMed Central

    Laha, Kurt T.; Ghosh, Borna; Czajkowski, Cynthia

    2013-01-01

    Electrochemical signaling in the brain depends on pentameric ligand-gated ion channels (pLGICs). Recently, crystal structures of prokaryotic pLGIC homologues from Erwinia chrysanthemi (ELIC) and Gloeobacter violaceus (GLIC) in presumed closed and open channel states have been solved, which provide insight into the structural mechanisms underlying channel activation. Although structural studies involving both ELIC and GLIC have become numerous, thorough functional characterizations of these channels are still needed to establish a reliable foundation for comparing kinetic properties. Here, we examined the kinetics of ELIC and GLIC current activation, desensitization, and deactivation and compared them to the GABAA receptor, a prototypic eukaryotic pLGIC. Outside-out patch-clamp recordings were performed with HEK-293T cells expressing ELIC, GLIC, or ?1?2?2L GABAA receptors, and ultra-fast ligand application was used. In response to saturating agonist concentrations, we found both ELIC and GLIC current activation were two to three orders of magnitude slower than GABAA receptor current activation. The prokaryotic channels also had slower current desensitization on a timescale of seconds. ELIC and GLIC current deactivation following 25 s pulses of agonist (cysteamine and pH 4.0 buffer, respectively) were relatively fast with time constants of 24.9±5.1 ms and 1.2±0.2 ms, respectively. Surprisingly, ELIC currents evoked by GABA activated very slowly with a time constant of 1.3±0.3 s and deactivated even slower with a time constant of 4.6±1.2 s. We conclude that the prokaryotic pLGICs undergo similar agonist-mediated gating transitions to open and desensitized states as eukaryotic pLGICs, supporting their use as experimental models. Their uncharacteristic slow activation, slow desensitization and rapid deactivation time courses are likely due to differences in specific structural elements, whose future identification may help uncover mechanisms underlying pLGIC gating transitions. PMID:24260369

  8. Assessment of Homology Templates and an Anesthetic Binding Site within the ?-Aminobutyric Acid Receptor

    PubMed Central

    Bertaccini, Edward J.; Yoluk, Ozge; Lindahl, Erik R.; Trudell, James R.

    2013-01-01

    Background Anesthetics mediate portions of their activity via modulation of the ?-aminobutyric acid receptor (GABAaR). While its molecular structure remains unknown, significant progress has been made towards understanding its interactions with anesthetics via molecular modeling. Methods The structure of the torpedo acetylcholine receptor (nAChR?), the structures of the ?4 and ?2 subunits of the human nAChR, the structures of the eukaryotic glutamate-gated chloride channel (GluCl), and the prokaryotic pH sensing channels, from Gloeobacter violaceus and Erwinia chrysanthemi, were aligned with the SAlign and 3DMA algorithms. A multiple sequence alignment from these structures and those of the GABAaR was performed with ClustalW. The Modeler and Rosetta algorithms independently created three-dimensional constructs of the GABAaR from the GluCl template. The CDocker algorithm docked a congeneric series of propofol derivatives into the binding pocket and scored calculated binding affinities for correlation with known GABAaR potentiation EC50’s. Results Multiple structure alignments of templates revealed a clear consensus of residue locations relevant to anesthetic effects except for torpedo nAChR. Within the GABAaR models generated from GluCl, the residues notable for modulating anesthetic action within transmembrane segments 1, 2, and 3 converged on the intersubunit interface between alpha and beta subunits. Docking scores of a propofol derivative series into this binding site showed strong linear correlation with GABAaR potentiation EC50. Conclusion Consensus structural alignment based on homologous templates revealed an intersubunit anesthetic binding cavity within the transmembrane domain of the GABAaR, which showed correlation of ligand docking scores with experimentally measured GABAaR potentiation. PMID:23770602

  9. Ion Selectivity Mechanism in a Bacterial Pentameric Ligand-Gated Ion Channel

    SciTech Connect

    Fritsch, Sebastian M; Ivanov, Ivaylo N; Wang, Hailong; Cheng, Xiaolin

    2011-01-01

    The proton-gated ion channel from Gloeobacter violaceus (GLIC) is a prokaryotic homolog of the eukaryotic nicotinic acetylcholine receptor (nAChR) that responds to the binding of neurotransmitter acetylcholine and mediates fast signal transmission. Recent emergence of a high resolution crystal structure of GLIC captured in a potentially open state allowed detailed, atomic-level insight into ion conduction and selectivity mechanisms in these channels. Herein, we have examined the barriers to ion conduction and origins of ion selectivity in the GLIC channel by the construction of potential of mean force (PMF) profiles for sodium and chloride ions inside the transmembrane region. Our calculations reveal that the GLIC channel is open for a sodium ion to transport, but presents a ~10 kcal/mol free energy barrier for a chloride ion, which arises primarily from the unfavorable interactions with a ring of negatively charged glutamate residues (E-2 ) at the intracellular end and a ring of hydrophobic residues (I9 ) in the middle of the transmembrane domain. Our collective findings further suggest that the charge selection mechanism can, to a large extent, be attributed to the narrow intracellular end and a ring of glutamate residues in this position their strong negative electrostatics and ability to bind cations. By contrast, E19 at the extracellular entrance only plays a minor role in ion selectivity of GLIC. In addition to electrostatics, both ion hydration and protein dynamics are found to be crucial for ion conduction as well, which explains why a chloride ion experiences a much greater barrier than a sodium ion in the hydrophobic region of the pore.

  10. Ion Selectivity Mechanism in a Bacterial Pentameric Ligand-Gated Ion Channel

    SciTech Connect

    Fritsch, Sebastian; Ivanov, Ivaylo; Wang, Hailong; Cheng, Xiaolin

    2010-01-01

    The proton-gated ion channel from Gloeobacter violaceus (GLIC) is a prokaryotic homolog of the eukaryotic nicotinic acetylcholine receptor that responds to the binding of neurotransmitter acetylcholine and mediates fast signal transmission. Recent emergence of a high-resolution crystal structure of GLIC captured in a potentially open state allowed detailed, atomic-level insight into ion conduction and selectivity mechanisms in these channels. Herein, we have examined the barriers to ion conduction and origins of ion selectivity in the GLIC channel by the construction of potential-of-mean-force profiles for sodium and chloride ions inside the transmembrane region. Our calculations reveal that the GLIC channel is open for a sodium ion to transport, but presents a 11 kcal/mol free energy barrier for a chloride ion. Our collective findings identify three distinct contributions to the observed preference for the permeant ions. First, there is a substantial contribution due to a ring of negatively charged glutamate residues (E-2 ) at the narrow intracellular end of the channel. The negative electrostatics of this region and the ability of the glutamate side chains to directly bind cations would strongly favor the passage of sodium ions while hindering translocation of chloride ions. Second, our results imply a significant hydrophobic contribution to selectivity linked to differences in the desolvation penalty for the sodium versus chloride ions in the central hydrophobic region of the pore. This hydrophobic contribution is evidenced by the large free energy barriers experienced by Cl in the middle of the pore for both GLIC and the E-2 A mutant. Finally, there is a distinct contribution arising from the overall negative electrostatics of the channel.

  11. Trichodesmium – a widespread marine cyanobacterium with unusual nitrogen fixation properties

    PubMed Central

    Bergman, Birgitta; Sandh, Gustaf; Lin, Senjie; Larsson, John; Carpenter, Edward J

    2013-01-01

    The last several decades have witnessed dramatic advances in unfolding the diversity and commonality of oceanic diazotrophs and their N2-fixing potential. More recently, substantial progress in diazotrophic cell biology has provided a wealth of information on processes and mechanisms involved. The substantial contribution by the diazotrophic cyanobacterial genus Trichodesmium to the nitrogen influx of the global marine ecosystem is by now undisputable and of paramount ecological importance, while the underlying cellular and molecular regulatory physiology has only recently started to unfold. Here, we explore and summarize current knowledge, related to the optimization of its diazotrophic capacity, from genomics to ecophysiological processes, via, for example, cellular differentiation (diazocytes) and temporal regulations, and suggest cellular research avenues that now ought to be explored. PMID:22928644

  12. Salt Tolerance and Polyphyly in the Cyanobacterium Chroococcidiopsis (Pleurocapsales)1

    NASA Technical Reports Server (NTRS)

    Cumbers, John Robert; Rothschild, Lynn J.

    2014-01-01

    Chroococcidiopsis Geitler (Geitler 1933) is a genus of cyanobacteria containing desiccation and radiation resistant species. Members of the genus live in habitats ranging from hot and cold deserts to fresh and saltwater environments. Morphology and cell division pattern have historically been used to define the genus. To better understand the genetic and phenotypic diversity of the genus, 15 species were selected that had been previously isolated from different locations, including salt and freshwater environments. Four markers were sequenced from these 15 species, the 16S rRNA, rbcL, desC1 and gltX genes. Phylogenetic trees were generated which identified two distinct clades, a salt-tolerant clade and a freshwater clade. This study demonstrates that the genus is polyphyletic based on saltwater and freshwater phenotypes. To understand the resistance to salt in more details, species were grown on a range of sea salt concentrations which demonstrated that the freshwater species were salt-intolerant whilst the saltwater species required salt for growth. This study shows an increased resolution of the phylogeny of Chroococcidiopsis and provides further evidence that the genus is polyphyletic and should be reclassified to improve clarity in the literature.

  13. Transatlantic abundance of the N2-fixing colonial cyanobacterium Trichodesmium.

    PubMed

    Davis, Cabell S; McGillicuddy, Dennis J

    2006-06-01

    Colonial diazotrophic cyanobacteria of the genus Trichodesmium are thought to play a significant role in the input of new nitrogen to upper layers of the tropical and subtropical oceanic ecosystems that cover nearly half of Earth's surface. Here we describe results of a transatlantic survey in which a noninvasive underwater digital microscope (the video plankton recorder), was towed across the North Atlantic at 6 meters per second while undulating between the surface and 130 meters. Colony abundance had a basin-scale trend, a clear association with anticyclonic eddies, and was not affected by hurricane-forced mixing. Subsurface abundance was higher than previously reported, which has important implications for the global ocean nitrogen cycle. PMID:16763148

  14. Functional genomics of the unicellular cyanobacterium Synechococcus elongatus PCC 7942 

    E-print Network

    Chen, You

    2009-05-15

    and characteristic features of the genome are discussed in this dissertation. More than 95% of the PCC 7942 genome has been mutagenized and mutants affected in approximately 30% of loci have been screened for defects in circadian function. Approximately 70 new clock...

  15. Almiramide D, cytotoxic peptide from the marine cyanobacterium Oscillatoria nigroviridis.

    PubMed

    Quintana, Jairo; Bayona, Lina M; Castellanos, Leonardo; Puyana, Mónica; Camargo, Paola; Aristizábal, Fabio; Edwards, Christine; Tabudravu, Jioji N; Jaspars, Marcel; Ramos, Freddy A

    2014-12-15

    Marine benthic cyanobacteria are widely known as a source of toxic and potentially useful compounds.These microorganisms have been studied from many Caribbean locations, which recently include locations in the Colombian Caribbean Sea. In the present study, six lipopeptides named almiramides D to H, together with the known almiramide B are identified from a mat characterized as Oscillatoria nigroviridis collected at the Island of Providence (Colombia, S.W. Caribbean Sea). The most abundant compounds, almiramides B and D were characterized by NMR and HRESIMS, while the structures of the minor compounds almiramides E to H were proposed by the analysis of their HRESIMS and MS2 spectra. Almiramides B and D were tested against six human cell lines including a gingival fibroblast cell line and five human tumor cell lines (A549, MDA-MB231, MCF-7, HeLa and PC3) showing a strong but not selective toxicity. PMID:25468043

  16. Host/virus interactions in the marine cyanobacterium prochlorococcus

    E-print Network

    Frois-Moniz, Katya

    2014-01-01

    Bacterial viruses shape the diversity, metabolic function, and community dynamics of their microbial hosts. As microbes drive many major biogeochemical cycles, viral infection is therefore a phenomenon of global significance. ...

  17. Dinitrogen fixation in a unicellular chlorophyll d-containing cyanobacterium

    PubMed Central

    Pfreundt, Ulrike; Stal, Lucas J; Voß, Björn; Hess, Wolfgang R

    2012-01-01

    Marine cyanobacteria of the genus Acaryochloris are the only known organisms that use chlorophyll d as a photosynthetic pigment. However, based on chemical sediment analyses, chlorophyll d has been recognized to be widespread in oceanic and lacustrine environments. Therefore it is highly relevant to understand the genetic basis for different physiologies and possible niche adaptation in this genus. Here we show that unlike all other known isolates of Acaryochloris, the strain HICR111A, isolated from waters around Heron Island, Great Barrier Reef, possesses a unique genomic region containing all the genes for the structural and enzymatically active proteins of nitrogen fixation and cofactor biosynthesis. Their phylogenetic analysis suggests a close relation to nitrogen fixation genes from certain other marine cyanobacteria. We show that nitrogen fixation in Acaryochloris sp. HICR111A is regulated in a light–dark-dependent fashion. We conclude that nitrogen fixation, one of the most complex physiological traits known in bacteria, might be transferred among oceanic microbes by horizontal gene transfer more often than anticipated so far. Our data show that the two powerful processes of oxygenic photosynthesis and nitrogen fixation co-occur in one and the same cell also in this branch of marine microbes and characterize Acaryochloris as a physiologically versatile inhabitant of an ecological niche, which is primarily driven by the absorption of far-red light. PMID:22237545

  18. Oxygen Concentration Inside a Functioning Photosynthetic Cell

    PubMed Central

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

    2014-01-01

    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 ?M, 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 ?M, 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 ?m 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. PMID:24806920

  19. Revision of the genus Procoryphaeus Mazur, 1984 (Coleoptera: Histeridae: Histerinae: Exosternini).

    PubMed

    Lackner, Tomáš

    2015-01-01

    The genus Procoryphaeus Mazur, 1984 is revised herein. It contains three species: Procoryphaeus violaceus (Lewis, 1905) from Thailand: Tenasserim Mountains; Malaysia: Borneo: Sabah; Indonesia: Java, Sumatra and Papua, Procoryphaeus pilosus (Lewis, 1893) from Tanimbar Island, Indonesia and Procoryphaeus wallacei (Marseul, 1864) from Indonesia: Papua. All type specimens are figured, and male genitalia of P. violaceus are drawn. Lectotypes of Pachycraerus (Coryphaeus) wallacei Marseul, 1864, Coryphaeus violaceus Lewis, 1905 and Coryphaeus pilosus Lewis, 1893 are designated. The exact identities of P. violaceus and P. wallacei species remain unclear since they are morphologically very similar and both respective type specimens are females. A key to species is given. PMID:26624713

  20. Sustained H2 Production Driven by Photosynthetic Water Splitting in a Unicellular Cyanobacterium

    SciTech Connect

    Melnicki, Matthew R.; Pinchuk, Grigoriy E.; Hill, Eric A.; Kucek, Leo A.; Fredrickson, Jim K.; Konopka, Allan; Beliaev, Alex S.

    2012-08-07

    Continuously illuminated nitrogen-deprived Cyanothece sp. ATCC 51142 evolved H2 via dinitrogenase at rates up to 400 ?mol•mg Chl-1•h-1 in parallel with photosynthetic O2 production. Notably, sustained co-production of H2 and O2 occurred over 100 h in the presence of CO2, with both gases displaying inverse oscillations which eventually dampened to stable rates. Oscillations were not observed when CO2 was omitted, while H2 and O2 evolution rates were positively correlated. In situ light saturation analyses of H2 production displayed dose-dependence and lack of O2 inhibition. Inactivation of photosystem II had substantial long-term effects but did not affect the short-term H2 production indicating that the process is also supported by photosystem I activity and oxidation of endogenous glycogen. Collectively, our results demonstrate that uninterrupted H2 production in unicellular diazotrophic cyanobacteria can be fueled by water photolysis without the detrimental effects of O2 and have important implications for sustainable production of biofuels.

  1. Regulation of the Nitrogen Fixation Genes in the Heterocystous Cyanobacterium Anabaena sp. Strain PCC 7120 

    E-print Network

    Kumar, Krithika

    2012-02-14

    . In cyanobacteria, 2-oxoglutarate, an intermediate in the Krebs cycle, constitutes the signal for nitrogen deprivation (103, 198). The Krebs cycle in cyanobacteria is incomplete because of the lack of 2-oxoglutarate dehydrogenase. As a result, 2-oxoglutarate?s...

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

    PubMed

    Zhang, Shuyi; Bryant, Donald A

    2015-05-29

    Cyanobacteria are important photoautotrophic bacteria with extensive but variable metabolic capacities. The existence of the glyoxylate cycle, a variant of the TCA cycle, is still poorly documented in cyanobacteria. Previous studies reported the activities of isocitrate lyase and malate synthase, the key enzymes of the glyoxylate cycle in some cyanobacteria, but other studies concluded that these enzymes are missing. In this study the genes encoding isocitrate lyase and malate synthase from Chlorogloeopsis fritschii PCC 9212 were identified, and the recombinant enzymes were biochemically characterized. Consistent with the presence of the enzymes of the glyoxylate cycle, C. fritschii could assimilate acetate under both light and dark growth conditions. Transcript abundances for isocitrate lyase and malate synthase increased, and C. fritschii grew faster, when the growth medium was supplemented with acetate. Adding acetate to the growth medium also increased the yield of poly-3-hydroxybutyrate. When the genes encoding isocitrate lyase and malate synthase were expressed in Synechococcus sp. PCC 7002, the acetate assimilation capacity of the resulting strain was greater than that of wild type. Database searches showed that the genes for the glyoxylate cycle exist in only a few other cyanobacteria, all of which are able to fix nitrogen. This study demonstrates that the glyoxylate cycle exists in a few cyanobacteria, and that this pathway plays an important role in the assimilation of acetate for growth in one of those organisms. The glyoxylate cycle might play a role in coordinating carbon and nitrogen metabolism under conditions of nitrogen fixation. PMID:25869135

  3. Cellular Dynamics Drives the Emergence of Supracellular Structure in the Cyanobacterium, Phormidium sp. KS

    PubMed Central

    Sato, Naoki; Katsumata, Yutaro; Sato, Kaoru; Tajima, Naoyuki

    2014-01-01

    Motile filamentous cyanobacteria, such as Oscillatoria, Phormidium and Arthrospira, are ubiquitous in terrestrial and aquatic environments. As noted by Nägeli in 1860, many of them form complex three-dimensional or two-dimensional structures, such as biofilm, weed-like thalli, bundles of filaments and spirals, which we call supracellular structures. In all of these structures, individual filaments incessantly move back and forth. The structures are, therefore, macroscopic, dynamic structures that are continuously changing their microscopic arrangement of filaments. In the present study, we analyzed quantitatively the movement of individual filaments of Phormidium sp. KS grown on agar plates. Junctional pores, which have been proposed to drive cell movement by mucilage/slime secretion, were found to align on both sides of each septum. The velocity of movement was highest just after the reversal of direction and, then, attenuated exponentially to a final value before the next reversal of direction. This kinetics is compatible with the “slime gun” model. A higher agar concentration restricts the movement more severely and, thus, resulted in more spiral formation. The spiral is a robust form compatible with non-homogeneous movements of different parts of a long filament. We propose a model of spiral formation based on the microscopic movement of filaments. PMID:25460162

  4. A Cyanobacterium Lacking Iron Superoxide Dismutase Is Sensitized to Oxidative Stress Induced with Methyl

    E-print Network

    Thomas, Dave

    ), hydrogen peroxide (H2O2), and the highly destructive hydroxyl radical ( OH). O2 and 1 O2* mainly occur and carotenoid contents and catalase activity, but the wild type had a faster growth rate and higher cyclic significant reactive oxygen species include excited singlet-state oxygen (1 O2*), the su- peroxide ion (O2

  5. Combined effects of different CO2 levels and N sources on the diazotrophic cyanobacterium Trichodesmium.

    PubMed

    Eichner, Meri; Kranz, Sven A; Rost, Björn

    2014-10-01

    To predict effects of climate change and possible feedbacks, it is crucial to understand the mechanisms behind CO2 responses of biogeochemically relevant phytoplankton species. Previous experiments on the abundant N2 fixers Trichodesmium demonstrated strong CO2 responses, which were attributed to an energy reallocation between its carbon (C) and nitrogen (N) acquisition. Pursuing this hypothesis, we manipulated the cellular energy budget by growing Trichodesmium erythraeum IMS101 under different CO2 partial pressure (pCO2 ) levels (180, 380, 980 and 1400?µatm) and N sources (N2 and NO3 (-) ). Subsequently, biomass production and the main energy-generating processes (photosynthesis and respiration) and energy-consuming processes (N2 fixation and C acquisition) were measured. While oxygen fluxes and chlorophyll fluorescence indicated that energy generation and its diurnal cycle was neither affected by pCO2 nor N source, cells differed in production rates and composition. Elevated pCO2 increased N2 fixation and organic C and N contents. The degree of stimulation was higher for nitrogenase activity than for cell contents, indicating a pCO2 effect on the transfer efficiency from N2 to biomass. pCO2 -dependent changes in the diurnal cycle of N2 fixation correlated well with C affinities, confirming the interactions between N and C acquisition. Regarding effects of the N source, production rates were enhanced in NO3 (-) grown cells, which we attribute to the higher N retention and lower ATP demand compared with N2 fixation. pCO2 effects on C affinity were less pronounced in NO3 (-) users than N2 fixers. Our study illustrates the necessity to understand energy budgets and fluxes under different environmental conditions for explaining indirect effects of rising pCO2 . PMID:24547877

  6. Polyphasic Characterization of a Thermotolerant Siderophilic Filamentous Cyanobacterium That Produces Intracellular Iron Deposits ? †

    PubMed Central

    Brown, Igor I.; Bryant, Donald A.; Casamatta, Dale; Thomas-Keprta, Kathie L.; Sarkisova, Svetlana A.; Shen, Gaozhong; Graham, Joel E.; Boyd, Eric S.; Peters, John W.; Garrison, Daniel H.; McKay, David S.

    2010-01-01

    Despite the high potential for oxidative stress stimulated by reduced iron, contemporary iron-depositing hot springs with circum-neutral pH are intensively populated with cyanobacteria. Therefore, studies of the physiology, diversity, and phylogeny of cyanobacteria inhabiting iron-depositing hot springs may provide insights into the contribution of cyanobacteria to iron redox cycling in these environments and new mechanisms of oxidative stress mitigation. In this study the morphology, ultrastructure, physiology, and phylogeny of a novel cyanobacterial taxon, JSC-1, isolated from an iron-depositing hot spring, were determined. The JSC-1 strain has been deposited in ATCC under the name Marsacia ferruginose, accession number BAA-2121. Strain JSC-1 represents a new operational taxonomical unit (OTU) within Leptolyngbya sensu lato. Strain JSC-1 exhibited an unusually high ratio between photosystem (PS) I and PS II, was capable of complementary chromatic adaptation, and is apparently capable of nitrogen fixation. Furthermore, it synthesized a unique set of carotenoids, but only chlorophyll a. Strain JSC-1 not only required high levels of Fe for growth (?40 ?M), but it also accumulated large amounts of extracellular iron in the form of ferrihydrite and intracellular iron in the form of ferric phosphates. Collectively, these observations provide insights into the physiological strategies that might have allowed cyanobacteria to develop and proliferate in Fe-rich, circum-neutral environments. PMID:20709851

  7. Compositional and toxicological evaluation of the diazotrophic cyanobacterium, Cyanothece sp. strain ATCC 51142

    NASA Technical Reports Server (NTRS)

    Schneegurt, M. A.; Arieli, B.; McKeehen, J. D.; Stephens, S. D.; Nielsen, S. S.; Saha, P. R.; Trumbo, P. R.; Sherman, L. A.; Mitchell, C. A. (Principal Investigator)

    1995-01-01

    Compositional analyses of Cyanothece sp. strain ATCC 51142 showed high protein (50-60%) and low fat (0.4-1%) content, and the ability to synthesize vitamin B12. The amino acid profile indicated that Cyanothece sp. was a balanced protein source. Fatty acids of the 18:3n-3 type were also present. Mineral analyses indicated that the cellular biomass may be a good source of Fe, Zn and Na. Caloric content was 4.5 to 5.1 kcal g dry weight-1 and the carbon content was approximately 40% on a dry weight basis. Nitrogen content was 8 to 9% on a dry weight basis and total nucleic acids were 1.3% on a dry weight basis. Short-term feeding studies in rats followed by histopathology found no toxicity or dietary incompatibility problems. The level of uric acid and allantoin in urine and tissues was low, suggesting no excess of nucleic acids, as sometimes reported in the past for a cyanobacteria-containing diet. The current work discusses the potential implications of these results for human nutrition applications.

  8. Dimeric chlorite dismutase from the nitrogen-fixing cyanobacterium Cyanothece sp. PCC7425.

    PubMed

    Schaffner, Irene; Hofbauer, Stefan; Krutzler, Michael; Pirker, Katharina F; Bellei, Marzia; Stadlmayr, Gerhard; Mlynek, Georg; Djinovic-Carugo, Kristina; Battistuzzi, Gianantonio; Furtmüller, Paul G; Daims, Holger; Obinger, Christian

    2015-06-01

    It is demonstrated that cyanobacteria (both azotrophic and non-azotrophic) contain heme b oxidoreductases that can convert chlorite to chloride and molecular oxygen (incorrectly denominated chlorite 'dismutase', Cld). Beside the water-splitting manganese complex of photosystem II, this metalloenzyme is the second known enzyme that catalyses the formation of a covalent oxygen-oxygen bond. All cyanobacterial Clds have a truncated N-terminus and are dimeric (i.e. clade 2) proteins. As model protein, Cld from Cyanothece sp. PCC7425 (CCld) was recombinantly produced in Escherichia coli and shown to efficiently degrade chlorite with an activity optimum at pH 5.0 [kcat 1144 ± 23.8 s(-1), KM 162 ± 10.0 ?M, catalytic efficiency (7.1 ± 0.6) × 10(6) M(-1) s(-1)]. The resting ferric high-spin axially symmetric heme enzyme has a standard reduction potential of the Fe(III)/Fe(II) couple of -126 ± 1.9 mV at pH 7.0. Cyanide mediates the formation of a low-spin complex with k(on) ?=?(1.6 ± 0.1) × 10(5) M(-1) s(-1) and k(off) = 1.4 ± 2.9 s(-1) (KD ? 8.6 ?M). Both, thermal and chemical unfolding follows a non-two-state unfolding pathway with the first transition being related to the release of the prosthetic group. The obtained data are discussed with respect to known structure-function relationships of Clds. We ask for the physiological substrate and putative function of these O2 -producing proteins in (nitrogen-fixing) cyanobacteria. PMID:25732258

  9. A Tribute to Disorder in the Genome of the Bloom-Forming Freshwater Cyanobacterium Microcystis aeruginosa

    PubMed Central

    Humbert, Jean-François; Barbe, Valérie; Latifi, Amel; Gugger, Muriel; Calteau, Alexandra; Coursin, Therese; Lajus, Aurélie; Castelli, Vanina; Oztas, Sophie; Samson, Gaëlle; Longin, Cyrille; Medigue, Claudine; de Marsac, Nicole Tandeau

    2013-01-01

    Microcystis aeruginosa is one of the most common bloom-forming cyanobacteria in freshwater ecosystems worldwide. This species produces numerous secondary metabolites, including microcystins, which are harmful to human health. We sequenced the genomes of ten strains of M. aeruginosa in order to explore the genomic basis of their ability to occupy varied environments and proliferate. Our findings show that M. aeruginosa genomes are characterized by having a large open pangenome, and that each genome contains similar proportions of core and flexible genes. By comparing the GC content of each gene to the mean value of the whole genome, we estimated that in each genome, around 11% of the genes seem to result from recent horizontal gene transfer events. Moreover, several large gene clusters resulting from HGT (up to 19 kb) have been found, illustrating the ability of this species to integrate such large DNA molecules. It appeared also that all M. aeruginosa displays a large genomic plasticity, which is characterized by a high proportion of repeat sequences and by low synteny values between the strains. Finally, we identified 13 secondary metabolite gene clusters, including three new putative clusters. When comparing the genomes of Microcystis and Prochlorococcus, one of the dominant picocyanobacteria living in marine ecosystems, our findings show that they are characterized by having almost opposite evolutionary strategies, both of which have led to ecological success in their respective environments. PMID:23950996

  10. Draft Genome Sequence of Bioactive-Compound-Producing Cyanobacterium Tolypothrix campylonemoides Strain VB511288

    PubMed Central

    Das, Subhadeep; Singh, Deeksha; Madduluri, Madhavi; Chandrababunaidu, Mathu Malar; Gupta, Akash

    2015-01-01

    We report here the draft genome sequence of Tolypothrix campylonemoides VB511288, isolated from building facades in Santiniketan, India. The members of this genus produce several compounds of commercial importance. The draft assembly is 10,627,177 bases in 135 scaffolds, and it contains 7,886 protein-coding genes, 994 pseudogenes, 18 rRNA genes, and 76 tRNA genes. PMID:25838485

  11. Protein Network Signatures Associated with Exogenous Biofuels Treatments in Cyanobacterium Synechocystis sp. PCC 6803

    PubMed Central

    Pei, Guangsheng; Chen, Lei; Wang, Jiangxin; Qiao, Jianjun; Zhang, Weiwen

    2014-01-01

    Although recognized as a promising microbial cell factory for producing biofuels, current productivity in cyanobacterial systems is low. To make the processes economically feasible, one of the hurdles, which need to be overcome is the low tolerance of hosts to toxic biofuels. Meanwhile, little information is available regarding the cellular responses to biofuels stress in cyanobacteria, which makes it challenging for tolerance engineering. Using large proteomic datasets of Synechocystis under various biofuels stress and environmental perturbation, a protein co-expression network was first constructed and then combined with the experimentally determined protein–protein interaction network. Proteins with statistically higher topological overlap in the integrated network were identified as common responsive proteins to both biofuels stress and environmental perturbations. In addition, a weighted gene co-expression network analysis was performed to distinguish unique responses to biofuels from those to environmental perturbations and to uncover metabolic modules and proteins uniquely associated with biofuels stress. The results showed that biofuel-specific proteins and modules were enriched in several functional categories, including photosynthesis, carbon fixation, and amino acid metabolism, which may represent potential key signatures for biofuels stress responses in Synechocystis. Network-based analysis allowed determination of the responses specifically related to biofuels stress, and the results constituted an important knowledge foundation for tolerance engineering against biofuels in Synechocystis. PMID:25405149

  12. Crystal structures of virus-like photosystem I complexes from the mesophilic cyanobacterium Synechocystis PCC 6803

    PubMed Central

    Mazor, Yuval; Nataf, Daniel; Toporik, Hila; Nelson, Nathan

    2014-01-01

    Oxygenic photosynthesis supports virtually all life forms on earth. Light energy is converted by two photosystems—photosystem I (PSI) and photosystem II (PSII). Globally, nearly 50% of photosynthesis takes place in the Ocean, where single cell cyanobacteria and algae reside together with their viruses. An operon encoding PSI was identified in cyanobacterial marine viruses. We generated a PSI that mimics the salient features of the viral complex, named PSIPsaJF. PSIPsaJF is promiscuous for its electron donors and can accept electrons from respiratory cytochromes. We solved the structure of PSIPsaJF and a monomeric PSI, with subunit composition similar to the viral PSI, providing for the first time a detailed description of the reaction center and antenna system from mesophilic cyanobacteria, including red chlorophylls and cofactors of the electron transport chain. Our finding extends the understanding of PSI structure, function and evolution and suggests a unique function for the viral PSI. DOI: http://dx.doi.org/10.7554/eLife.01496.001 PMID:24473073

  13. An Integrative Approach to Energy Carbon and Redox Metabolism In Cyanobacterium Synechocystis

    SciTech Connect

    Dr. Ross Overbeek

    2003-06-30

    The main objectives for the first year were to produce a detailed metabolic reconstruction of synechocystis sp.pcc6803 especially in interrelated arrears of photosynthesis respiration and central carbon metabolism to support a more complete understanding and modeling of this organism. Additionally, IG, Inc. provided detailed bioinformatic analysis of selected functional systems related to carbon and energy generation and utilization, and of the corresponding pathways functional roles and individual genes to support wet lab experiments by collaborators.

  14. Elevated CO2 causes changes in the photosynthetic apparatus of a toxic cyanobacterium, Cylindrospermopsis raciborskii.

    PubMed

    Pierangelini, Mattia; Stojkovic, Slobodanka; Orr, Philip T; Beardall, John

    2014-07-15

    We studied the physiological acclimation of growth, photosynthesis and CO2-concentrating mechanism (CCM) in Cylindrospermopsis raciborskii exposed to low (present day; L-CO2) and high (1300ppm; H-CO2) pCO2. Results showed that under H-CO2 the cell specific division rate (?c) was higher and the CO2- and light-saturated photosynthetic rates (Vmax and Pmax) doubled. The cells' photosynthetic affinity for CO2 (K0.5CO2) was halved compared to L-CO2 cultures. However, no significant differences were found in dark respiration rates (Rd), pigment composition and light harvesting efficiency (?). In H-CO2 cells, non-photochemical quenching (NPQ), associated with state transitions of the electron transport chain (ETC), was negligible. Simultaneously, a reorganisation of PSII features including antenna connectivity (JconPSII?), heterogeneity (PSII?/?) and effective absorption cross sectional area (?PSII?/?) was observed. In relation to different activities of the CCM, our findings suggest that for cells grown under H-CO2: (1) there is down-regulation of CCM activity; (2) the ability of cells to use the harvested light energy is altered; (3) the occurrence of state transitions is likely to be associated with changes of electron flow (cyclic vs linear) through the ETC; (4) changes in PSII characteristics are important in regulating state transitions. PMID:24878143

  15. First evidence of palytoxin and 42-hydroxy-palytoxin in the marine cyanobacterium Trichodesmium.

    PubMed

    Kerbrat, Anne Sophie; Amzil, Zouher; Pawlowiez, Ralph; Golubic, Stjepko; Sibat, Manoella; Darius, Helene Taiana; Chinain, Mireille; Laurent, Dominique

    2011-01-01

    Marine pelagic diazotrophic cyanobacteria of the genus Trichodesmium (Oscillatoriales) are widespread throughout the tropics and subtropics, and are particularly common in the waters of New Caledonia. Blooms of Trichodesmium are suspected to be a potential source of toxins in the ciguatera food chain and were previously reported to contain several types of paralyzing toxins. The toxicity of water-soluble extracts of Trichodesmium spp. were analyzed by mouse bioassay and Neuroblastoma assay and their toxic compounds characterized using liquid chromatography coupled with tandem mass spectrometry techniques. Here, we report the first identification of palytoxin and one of its derivatives, 42-hydroxy-palytoxin, in field samples of Trichodesmium collected in the New Caledonian lagoon. The possible role played by Trichodesmium blooms in the development of clupeotoxism, this human intoxication following the ingestion of plankton-eating fish and classically associated with Ostreopsis blooms, is also discussed. PMID:21731549

  16. ARSENATE UPTAKE, SEQUESTRATION AND REDUCTION BY A FRESHWATER CYANOBACTERIUM: A POTENTIAL BIOLOGIC CONTROL

    E-print Network

    Herbert, Bruce

    . I am thankful for the help provided by Dr. David Zuberer, with both his knowledge and his cell-counting:P ratios has minimal effect on net arsenate uptake over an 18 day period. However, cyanobacteria were shown donation of the cyanobacteria. Thanks, also, to Dr. Ethan Grossman for his help early in my graduate career

  17. Simple method for a cell count of the colonial Cyanobacterium, Microcystis sp.

    PubMed

    Joung, Seung-Hyun; Kim, Choong-Jae; Ahn, Chi-Yong; Jang, Kam-Yong; Boo, Sung Min; Oh, Hee-Mock

    2006-10-01

    The cell counting of colonial Microcystis spp. is a rather difficult and error-prone proposition, as this genus forms irregularly-shaped and irregularly-sized colonies, which are packed with cells. Thus, in order to facilitate a cell count, four methods of dividing the colonies into single cells were compared, including vortexing, sonication, TiO2 treatment, and boiling. As a result, the boiling method was determined to generate the greatest number of single cells from a colony, and all colonies were found to have divided completely after only 6 min of treatment. Furthermore, no significant cell destruction, which might alter the actual cell density, was detected in conjunction with the boiling method (P = 0.158). In order to compute the cell number more simply, the relationship between the colony size and the cell number was determined, via the boiling method. The colony volume, rather than the area or diameter was correlated more closely with the cell number (r2 = 0.727), thereby suggesting that the cell numbers of colonial Microcystis sp. can also be estimated effectively from their volumes. PMID:17082751

  18. Paralytic Shellfish Poisoning Toxin-Producing Cyanobacterium Aphanizomenon gracile in Northeast Germany? †

    PubMed Central

    Ballot, Andreas; Fastner, Jutta; Wiedner, Claudia

    2010-01-01

    Neurotoxic paralytic shellfish poisoning (PSP) toxins, anatoxin-a (ATX), and hepatotoxic cylindrospermopsin (CYN) have been detected in several lakes in northeast Germany during the last 2 decades. They are produced worldwide by members of the nostocalean genera Anabaena, Cylindrospermopsis, and Aphanizomenon. Although no additional sources of PSP toxins and ATX have been identified in German water bodies to date, the observed CYN concentrations cannot be produced solely by Aphanizomenon flos-aquae, the only known CYN producer in Germany. Therefore, we attempted to identify PSP toxin, ATX, and CYN producers by isolating and characterizing 92 Anabaena, Aphanizomenon, and Anabaenopsis strains from five lakes in northeast Germany. In a polyphasic approach, all strains were morphologically and phylogenetically classified and then tested for PSP toxins, ATX, and CYN by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and enzyme-linked immunosorbent assay (ELISA) and screened for the presence of PSP toxin- and CYN-encoding gene fragments. As demonstrated by ELISA and LC-MS, 14 Aphanizomenon gracile strains from Lakes Melang and Scharmützel produced four PSP toxin variants (gonyautoxin 5 [GTX5], decarbamoylsaxitoxin [dcSTX], saxitoxin [STX], and neosaxitoxin [NEO]). GTX5 was the most prevalent PSP toxin variant among the seven strains from Lake Scharmützel, and NEO was the most prevalent among the seven strains from Lake Melang. The sxtA gene, which is part of the saxitoxin gene cluster, was found in the 14 PSP toxin-producing A. gracile strains and in 11 non-PSP toxin-producing Aphanizomenon issatschenkoi, A. flos-aquae, Anabaena planktonica, and Anabaenopsis elenkinii strains. ATX and CYN were not detected in any of the isolated strains. This study is the first confirming the role of A. gracile as a PSP toxin producer in German water bodies. PMID:20048055

  19. Growth and Photosynthesis of the Cyanobacterium Synechococcus leopoliensis in HCO3?-Limited Chemostats 1

    PubMed Central

    Miller, Anthony G.; Turpin, David H.; Canvin, David T.

    1984-01-01

    Synechococcus leopoliensis was grown in HCO3?-limited chemostats. Growth at 50% the maximum rate occurred when the inorganic carbon concentration was 10 to 15 micromolar (or 5.6 to 8.4 nanomolar CO2). The O2 to CO2 ratios during growth were as high as 192,000 to 1. At growth rates below 80% the maximum rate, essentially all the supplied inorganic carbon was converted to organic carbon, and the cells were carbon limited. Carbon-limited cells used HCO3? rather than CO2 for growth. They also exhibited a very high photosynthetic affinity for inorganic carbon in short-term experiments. Cells growing at greater than 80% maximum growth rate, in the presence of high dissolved inorganic carbon, were termed carbon sufficient. These cells had photosynthetic affinities that were about 1000-fold lower than HCO3?-limited cells and also had a reduced capacity for HCO3? transport. HCO3?-limited cells are reminiscent of the air-grown cells of batch culture studies while the carbon sufficient cells are reminiscent of high-CO2 grown cells. However, the low affinity cells of the present study were growing at CO2 concentrations less than air saturation. This suggests that supranormal levels of CO2 not required to induce the physiological changes usually ascribed to high CO2 cells. PMID:16663735

  20. Heavy metal removal from multicomponent system by the cyanobacterium Nostoc muscorum: kinetics and interaction study.

    PubMed

    Roy, Arindam Sinha; Hazarika, Jayeeta; Manikandan, N Arul; Pakshirajan, Kannan; Syiem, Mayashree B

    2015-04-01

    In this study, Nostoc muscorum, a native cyanobacterial species isolated from a coal mining site, was employed to remove Cu(II), Zn(II), Pb(II) and Cd(II) from aqueous solution containing these metals in the mixture. In this multicomponent study, carried out as per the statistically valid Plackett-Burman design of experiments, the results revealed a maximum removal of both Pb(II) (96.3 %) and Cu(II) (96.42 %) followed by Cd(II) (80.04 %) and Zn(II) (71.3 %) at the end of the 60-h culture period. Further, the removal of these metals was attributed to both passive biosorption and accumulation by the actively growing N. muscorum biomass. Besides, the specific removal rate of these metals by N. muscorum was negatively correlated to its specific growth rate. For a better understanding of the effect of these metals on each other's removal by the cyanobacteria, the results were statistically analyzed in the form of analysis of variance (ANOVA) and Student's t test. ANOVA of the metal bioremoval revealed that the main (individual) effect due to the metals was highly significant (P value <0.05) on each other's removal. Student's t test results revealed that both Zn(II) and Pb(II) strongly inhibited both Cu(II) removal (P value <0.01) and Cd(II) removal (P value <0.02). All these results not only demonstrated a very good potential of the cyanobacteria in the bioremoval of these metals but also the effect of individual metals on each other's removal in the multicomponent system. PMID:25725800

  1. Genomic Responses to Arsenic in the Cyanobacterium Synechocystis sp. PCC 6803

    PubMed Central

    Sánchez-Riego, Ana María; López-Maury, Luis; Florencio, Francisco Javier

    2014-01-01

    Arsenic is a ubiquitous contaminant and a toxic metalloid which presents two main redox states in nature: arsenite [AsIII] and arsenate [AsV]. Arsenic resistance in Synechocystis sp. strain PCC 6803 is mediated by the arsBHC operon and two additional arsenate reductases encoded by the arsI1 and arsI2 genes. Here we describe the genome-wide responses to the presence of arsenate and arsenite in wild type and mutants in the arsenic resistance system. Both forms of arsenic produced similar responses in the wild type strain, including induction of several stress related genes and repression of energy generation processes. These responses were transient in the wild type strain but maintained in time in an arsB mutant strain, which lacks the arsenite transporter. In contrast, the responses observed in a strain lacking all arsenate reductases were somewhat different and included lower induction of genes involved in metal homeostasis and Fe-S cluster biogenesis, suggesting that these two processes are targeted by arsenite in the wild type strain. Finally, analysis of the arsR mutant strain revealed that ArsR seems to only control 5 genes in the genome. Furthermore, the arsR mutant strain exhibited hypersentivity to nickel, copper and cadmium and this phenotype was suppressed by mutation in arsB but not in arsC gene suggesting that overexpression of arsB is detrimental in the presence of these metals in the media. PMID:24797411

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

    PubMed Central

    Sánchez-Riego, Ana M.; López-Maury, Luis; Florencio, Francisco J.

    2013-01-01

    Glutaredoxins are small redox proteins able to reduce disulfides and mixed disulfides between GSH and proteins. Synechocystis sp. PCC 6803 contains three genes coding for glutaredoxins: ssr2061 (grxA) and slr1562 (grxB) code for dithiolic glutaredoxins while slr1846 (grxC) codes for a monothiolic glutaredoxin. We have analyzed the expression of these glutaredoxins in response to different stresses, such as high light, H2O2 and heat shock. Analysis of the mRNA levels showed that grxA is only induced by heat while grxC is repressed by heat shock and is induced by high light and H2O2. In contrast, grxB expression was maintained almost constant under all conditions. Analysis of GrxA and GrxC protein levels by western blot showed that GrxA increases in response to high light, heat or H2O2 while GrxC is only induced by high light and H2O2, in accordance with its mRNA levels. In addition, we have also generated mutants that have interrupted one, two, or three glutaredoxin genes. These mutants were viable and did not show any different phenotype from the WT under standard growth conditions. Nevertheless, analysis of these mutants under several stress conditions revealed that single grxA mutants grow slower after H2O2, heat and high light treatments, while mutants in grxB are indistinguishable from WT. grxC mutants were hypersensitive to treatments with H2O2, heat, high light and metals. A double grxAgrxC mutant was found to be even more sensitive to H2O2 than each corresponding single mutants. Surprisingly a mutation in grxB suppressed totally or partially the phenotypes of grxA and grxC mutants except the H2O2 sensitivity of the grxC mutant. This suggests that grxA and grxC participate in independent pathways while grxA and grxB participate in a common pathway for H2O2 resistance. The data presented here show that glutaredoxins are essential for stress adaptation in cyanobacteria, although their targets and mechanism of action remain unidentified. PMID:24204369

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

    PubMed

    Sánchez-Riego, Ana María; López-Maury, Luis; Florencio, Francisco Javier

    2014-01-01

    Arsenic is a ubiquitous contaminant and a toxic metalloid which presents two main redox states in nature: arsenite [As(III)] and arsenate [As(V)]. Arsenic resistance in Synechocystis sp. strain PCC 6803 is mediated by the arsBHC operon and two additional arsenate reductases encoded by the arsI1 and arsI2 genes. Here we describe the genome-wide responses to the presence of arsenate and arsenite in wild type and mutants in the arsenic resistance system. Both forms of arsenic produced similar responses in the wild type strain, including induction of several stress related genes and repression of energy generation processes. These responses were transient in the wild type strain but maintained in time in an arsB mutant strain, which lacks the arsenite transporter. In contrast, the responses observed in a strain lacking all arsenate reductases were somewhat different and included lower induction of genes involved in metal homeostasis and Fe-S cluster biogenesis, suggesting that these two processes are targeted by arsenite in the wild type strain. Finally, analysis of the arsR mutant strain revealed that ArsR seems to only control 5 genes in the genome. Furthermore, the arsR mutant strain exhibited hypersentivity to nickel, copper and cadmium and this phenotype was suppressed by mutation in arsB but not in arsC gene suggesting that overexpression of arsB is detrimental in the presence of these metals in the media. PMID:24797411

  4. Coupling of Solar Energy to Hydrogen Peroxide Production in the Cyanobacterium Anacystis nidulans

    PubMed Central

    Roncel, Mercedes; Navarro, José A.; De la Rosa, Miguel A.

    1989-01-01

    Hydrogen peroxide production by blue-green algae (cyanobacteria) under photoautotrophic conditions is of great interest as a model system for the bioconversion of solar energy. Our experimental system was based on the photosynthetic reduction of molecular oxygen with electrons from water by Anacystis nidulans 1402-1 as the biophotocatalyst and methyl viologen as a redox intermediate. It has been demonstrated that the metabolic conditions of the algae in their different growth stages strongly influence the capacity for hydrogen peroxide photoproduction, and so the initial formation rate and net peroxide yield became maximum in the mid-log phase of growth. The overall process can be optimized in the presence of certain metabolic inhibitors such as iodoacetamide and p-hydroxymercuribenzoate, as well as by permeabilization of the cellular membrane after drastic temperature changes and by immobilization of the cells in inert supports such as agar and alginate. PMID:16347855

  5. The cyanobacterium Mastigocladus fulfills the nitrogen demand of a terrestrial hot spring microbial mat.

    PubMed

    Estrella Alcamán, María; Fernandez, Camila; Delgado, Antonio; Bergman, Birgitta; Díez, Beatriz

    2015-10-01

    Cyanobacteria from Subsection V (Stigonematales) are important components of microbial mats in non-acidic terrestrial hot springs. Despite their diazotrophic nature (N2 fixers), their impact on the nitrogen cycle in such extreme ecosystems remains unknown. Here, we surveyed the identity and activity of diazotrophic cyanobacteria in the neutral hot spring of Porcelana (Northern Patagonia, Chile) during 2009 and 2011-2013. We used 16S rRNA and the nifH gene to analyze the distribution and diversity of diazotrophic cyanobacteria. Our results demonstrate the dominance of the heterocystous genus Mastigocladus (Stigonematales) along the entire temperature gradient of the hot spring (69-38?°C). In situ nitrogenase activity (acetylene reduction), nitrogen fixation rates (cellular uptake of (15)N2) and nifH transcription levels in the microbial mats showed that nitrogen fixation and nifH mRNA expression were light-dependent. Nitrogen fixation activities were detected at temperatures ranging from 58?°C to 46?°C, with maximum daily rates of 600?nmol C2H4 cm(-2) per day and 94.1?nmol N?cm(-2) per day. These activity patterns strongly suggest a heterocystous cyanobacterial origin and reveal a correlation between nitrogenase activity and nifH gene expression during diurnal cycles in thermal microbial mats. N and C fixation in the mats contributed ~3?g N?m(-2) per year and 27?g C?m(-2) per year, suggesting that these vital demands are fully met by the diazotrophic and photoautotrophic capacities of the cyanobacteria in the Porcelana hot spring. PMID:26230049

  6. Effect of a combination of two rice herbicides on the cyanobacterium, Nostoc spongiaeforme

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cyanobacteria grow in California rice fields where they form large mats that may smoother seedlings or cause them to dislodge, resulting in yield loss. The most troublesome species is Nostoc spongiaeforme. It is very difficult to control using currently accepted methods, i.e., aerial applications of...

  7. Complete genome of a nonphotosynthetic cyanobacterium in a diatom reveals recent adaptations to an intracellular lifestyle.

    PubMed

    Nakayama, Takuro; Kamikawa, Ryoma; Tanifuji, Goro; Kashiyama, Yuichiro; Ohkouchi, Naohiko; Archibald, John M; Inagaki, Yuji

    2014-08-01

    The evolution of mitochondria and plastids from bacterial endosymbionts were key events in the origin and diversification of eukaryotic cells. Although the ancient nature of these organelles makes it difficult to understand the earliest events that led to their establishment, the study of eukaryotic cells with recently evolved obligate endosymbiotic bacteria has the potential to provide important insight into the transformation of endosymbionts into organelles. Diatoms belonging to the family Rhopalodiaceae and their endosymbionts of cyanobacterial origin (i.e., "spheroid bodies") are emerging as a useful model system in this regard. The spheroid bodies, which appear to enable rhopalodiacean diatoms to use gaseous nitrogen, became established after the divergence of extant diatom families. Here we report what is, to our knowledge, the first complete genome sequence of a spheroid body, that of the rhopalodiacean diatom Epithemia turgida. The E. turgida spheroid body (EtSB) genome was found to possess a gene set for nitrogen fixation, as anticipated, but is reduced in size and gene repertoire compared with the genomes of their closest known free-living relatives. The presence of numerous pseudogenes in the EtSB genome suggests that genome reduction is ongoing. Most strikingly, our genomic data convincingly show that the EtSB has lost photosynthetic ability and is metabolically dependent on its host cell, unprecedented characteristics among cyanobacteria, and cyanobacterial symbionts. The diatom-spheroid body endosymbiosis is thus a unique system for investigating the processes underlying the integration of a bacterial endosymbiont into eukaryotic cells. PMID:25049384

  8. Isolation of Regulated Genes of the Cyanobacterium Synechocystis sp. Strain PCC 6803 by Differential Display†

    PubMed Central

    Bhaya, Devaki; Vaulot, Daniel; Amin, Pinky; Takahashi, Akiko Watanabe; Grossman, Arthur R.

    2000-01-01

    Global identification of differentially regulated genes in prokaryotes is constrained because the mRNA does not have a 3? polyadenylation extension; this precludes specific separation of mRNA from rRNA and tRNA and synthesis of cDNAs from the entire mRNA population. Knowledge of the entire genome sequence of Synechocystis sp. strain PCC 6803 has enabled us to develop a differential display procedure that takes advantage of a short palindromic sequence that is dispersed throughout the Synechocystis sp. strain PCC 6803 genome. This sequence, designated the HIP (highly iterated palindrome) element, occurs in approximately half of the Synechocystis sp. strain PCC 6803 genes but is absent in rRNA and tRNA genes. To determine the feasibility of exploiting the HIP element, alone or in combination with specific primer subsets, for analyzing differential gene expression, we used HIP-based primers to identify light intensity-regulated genes. Several gene fragments, including those encoding ribosomal proteins and phycobiliprotein subunits, were differentially amplified from RNA templates derived from cells grown in low light or exposed to high light for 3 h. One novel finding was that expression of certain genes of the pho regulon, which are under the control of environmental phosphate levels, were markedly elevated in high light. High-light activation of pho regulon genes correlated with elevated growth rates that occur when the cells are transferred from low to high light. These results suggest that in high light, the rate of growth of Synechocystis sp. strain PCC 6803 exceeds its capacity to assimilate phosphate, which, in turn, may trigger a phosphate starvation response and activation of the pho regulon. PMID:11004166

  9. Carbon, nitrogen and O2 fluxes associated with the cyanobacterium Nodularia spumigena in the Baltic Sea

    PubMed Central

    Ploug, Helle; Adam, Birgit; Musat, Niculina; Kalvelage, Tim; Lavik, Gaute; Wolf-Gladrow, Dieter; Kuypers, Marcel M M

    2011-01-01

    Photosynthesis, respiration, N2 fixation and ammonium release were studied directly in Nodularia spumigena during a bloom in the Baltic Sea using a combination of microsensors, stable isotope tracer experiments combined with nanoscale secondary ion mass spectrometry (nanoSIMS) and fluorometry. Cell-specific net C- and N2-fixation rates by N. spumigena were 81.6±6.7 and 11.4±0.9?fmol N per cell per h, respectively. During light, the net C:N fixation ratio was 8.0±0.8. During darkness, carbon fixation was not detectable, but N2 fixation was 5.4±0.4?fmol N per cell per h. Net photosynthesis varied between 0.34 and 250?nmol O2?h?1 in colonies with diameters ranging between 0.13 and 5.0?mm, and it reached the theoretical upper limit set by diffusion of dissolved inorganic carbon to colonies (>1?mm). Dark respiration of the same colonies varied between 0.038 and 87?nmol O2?h?1, and it reached the limit set by O2 diffusion from the surrounding water to colonies (>1?mm). N2 fixation associated with N. spumigena colonies (>1?mm) comprised on average 18% of the total N2 fixation in the bulk water. Net NH4+ release in colonies equaled 8–33% of the estimated gross N2 fixation during photosynthesis. NH4+ concentrations within light-exposed colonies, modeled from measured net NH4+ release rates, were 60-fold higher than that of the bulk. Hence, N. spumigena colonies comprise highly productive microenvironments and an attractive NH4+ microenvironment to be utilized by other (micro)organisms in the Baltic Sea where dissolved inorganic nitrogen is limiting growth. PMID:21390075

  10. Growth rate regulation of rRNA content of a marine Synechococcus (cyanobacterium) strain

    SciTech Connect

    Binder, B.J.; Liu, Y.C.

    1998-09-01

    The relationship between growth rate and rRNA content in a marine Synechococcus strain was examined. A combination of flow cytometry and whole-cell hybridization with fluorescently labeled 16S rRNA-targeted oligonucleotide probes was used to measure the rRNA content of Synechococcus strain WH8101 cells grown at a range of light-limited growth rates. The sensitivity of this approach was sufficient for the analysis of rRNA even in very slowly growing Synechococcus cells. The relationship between growth rate and cellular rRNA content comprised three phases: (1) at low growth rates, rRNA cell{sup {minus}1} remained approximately constant; (2) at intermediate rates, rRNA cell{sup {minus}1} increased proportionally with growth rate; and (3) at the highest, light-saturated rates, rRNA cell{sup {minus}1} dropped abruptly. Total cellular RNA was well correlated with the probe-based measure of rRNA and varied in a similar manner with growth rate. Mean cell volume and rRNA concentration were related to growth rate in a manner similar to rRNA cell{sup {minus}1}, although the overall magnitude linear increase in ribosome efficiency with increasing growth rate, which is consistent with the prevailing prokaryotic model at low growth rates. Taken together, these results support the notion that measurements of cellular rRNA content might be useful for estimating in situ growth rates in natural Synechococcus populations.

  11. PHYSIOLOGICAL ROLES OF SUPEROXIDE DISMUTASES IN THE CYANOBACTERIUM, Synechococcus sp. STRAIN PCC7942

    E-print Network

    Thomas, Dave

    --accepted position), NASA Space Life Sciences Training Program, Florida A&M University, Tallahassee, FL superoxide dismutase, designated sodB- , was characterized by its growth rate, photosynthetic pigments and catalase activity, but the wild type had a slightly faster growth rate and higher cyclic photosynthetic

  12. First Evidence of Palytoxin and 42-Hydroxy-palytoxin in the Marine Cyanobacterium Trichodesmium

    PubMed Central

    Kerbrat, Anne Sophie; Amzil, Zouher; Pawlowiez, Ralph; Golubic, Stjepko; Sibat, Manoella; Darius, Helene Taiana; Chinain, Mireille; Laurent, Dominique

    2011-01-01

    Marine pelagic diazotrophic cyanobacteria of the genus Trichodesmium (Oscillatoriales) are widespread throughout the tropics and subtropics, and are particularly common in the waters of New Caledonia. Blooms of Trichodesmium are suspected to be a potential source of toxins in the ciguatera food chain and were previously reported to contain several types of paralyzing toxins. The toxicity of water-soluble extracts of Trichodesmium spp. were analyzed by mouse bioassay and Neuroblastoma assay and their toxic compounds characterized using liquid chromatography coupled with tandem mass spectrometry techniques. Here, we report the first identification of palytoxin and one of its derivatives, 42-hydroxy-palytoxin, in field samples of Trichodesmium collected in the New Caledonian lagoon. The possible role played by Trichodesmium blooms in the development of clupeotoxism, this human intoxication following the ingestion of plankton-eating fish and classically associated with Ostreopsis blooms, is also discussed. PMID:21731549

  13. Dynamic proteomic profiling of a unicellular cyanobacterium Cyanothece ATCC51142 across light-dark diurnal cycles

    SciTech Connect

    Aryal, Uma K.; Stockel, Jana; Krovvidi, Ravi K.; Gritsenko, Marina A.; Monroe, Matthew E.; Moore, Ronald J.; Koppenaal, David W.; Smith, Richard D.; Pakrasi, Himadri B.; Jacobs, Jon M.

    2011-12-01

    Unicellular cyanobacteria of the genus Cyanothece are recognized for their ability to execute nitrogen (N2)-fixation in the dark and photosynthesis in the light. Systems-wide dynamic proteomic profiling with mass spectrometry (MS) analysis reveals fundamental insights into the control and regulation of these functions. To expand upon the current knowledge of protein expression patterns in Cyanothece ATCC51142, we performed quantitative proteomic analysis using partial ("unsaturated") metabolic labeling and high mass accuracy LC-MS analysis. This dynamic proteomic profiling identified 721 actively synthesized proteins with significant temporal changes in expression throughout the light-dark cycles, of which 425 proteins matched with previously characterized cycling transcripts. The remaining 296 proteins contained a cluster of proteins uniquely involved in DNA replication and repair, protein degradation, tRNA synthesis and modification, transport and binding, and regulatory functions. Analysis of protein functions revealed that the expression of nitrogenase in the dark is mediated by higher respiration and glycogen metabolism. We have also shown that Cyanothece ATCC51142 utilizes alternative pathways for carbon (C) and nitrogen (N) acquisition, particularly, aspartic acid and glutamate as substrates of C and N, respectively. Utilization of phosphoketolase (PHK) pathway for the conversion of xylulose-5P to pyruvate and acetyl-P likely constitutes an alternative strategy to compensate higher ATP and NADPH demand. In conclusion, this study provides a deeper insight into how Cyanothece ATCC51142 modulates cellular functions to accommodate photosynthesis and N2-fixation within the single cell.

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

    SciTech Connect

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

    2005-02-15

    The team of the Fellowship for Interpretation of Genomes (FIG) under the leadership of Ross Overbeek, began working on this Project in November 2003. During the previous year, the Project was performed at Integrated Genomics Inc. A transition from the industrial environment to the public domain prompted us to adjust some aspects of the Project. Notwithstanding the challenges, we believe that these adjustments had a strong positive impact on our deliverables. Most importantly, the work of the research team led by R. Overbeek resulted in the deployment of a new open source genomic platform, the SEED (Specific Aim 1). This platform provided a foundation for the development of CyanoSEED a specialized portal to comparative analysis and metabolic reconstruction of all available cyanobacterial genomes (Specific Aim 3). The SEED represents a new generation of software for genome analysis. Briefly, it is a portable and extendable system, containing one of the largest and permanently growing collections of complete and partial genomes. The complete system with annotations and tools is freely available via browsing or via installation on a user's Mac or Linux computer. One of the important unique features of the SEED is the support of metabolic reconstruction and comparative genome analysis via encoding and projection of functional subsystems. During the project period, the FIG research team has validated the new software by developing a significant number of core subsystems, covering many aspects of central metabolism (Specific Aim 2), as well as metabolic areas specific for cyanobacteria and other photoautotrophic organisms (Specific Aim 3). In addition to providing a proof of technology and a starting point for further community-based efforts, these subsystems represent a valuable asset. An extensive coverage of central metabolism provides the bulk of information required for metabolic modeling in Synechocystis sp.PCC 6803. Detailed analysis of several subsystems covering energy, carbon, and redox metabolism in the Synechocystis sp. PCC 6803 and other cyanobacteria has been performed (Specific Aim 4). The main objectives for this year (adjusted to reflect a new, public domain, setting of the Project research team) were: Aim 1. To develop, test, and deploy a new open source system, the SEED, for integrating community-based annotation, and comparative analysis of all publicly available microbial genomes. Develop a comprehensive genomic database by integrating within SEED all publicly available complete and nearly complete genome sequences with special emphasis on genomes of cyanobacteria, phototrophic eukaryotes, and anoxygenic phototrophic bacteria--invaluable for comparative genomic studies of energy and carbon metabolism in Synechocystis sp. PCC 6803. Aim 2. To develop the SEED's biological content in the form of a collection of encoded Subsystems largely covering the conserved cellular machinery in prokaryotes (and central metabolic machinery in eukaryotes). Aim 3. To develop, utilizing core SEED technology, the CyanoSEED--a specialized WEB portal for community-based annotation, and comparative analysis of all publicly available cyanobacterial genomes. Encode the set of additional subsystems representing key metabolic transformations in cyanobacteria and other photoautotrophs. We envisioned this resource as complementary to other public access databases for comparative genomic analysis currently available to the cyanobacterial research community. Aim 4. Perform in-depth analysis of several subsystems covering energy, carbon, and redox metabolism in the Synechocystis sp. PCC 6803 and all other cyanobacteria with available genome sequences. Reveal inconsistencies and gaps in the current knowledge of these subsystems. Use functional and genome context analysis tools in CyanoSEED to predict, whenever possible, candidate genes for inferred functional roles. To disseminate freely these conjectures and predictions by publishing them on CyanoSEED (http://cyanoseed.thefig.info/) and the Subsystems Forum (http://brucella.uchicago.edu/Su

  15. Regulation of Nitrogenase Gene Expression by Transcript Stability in the Cyanobacterium Anabaena variabilis

    PubMed Central

    Pratte, Brenda S.

    2014-01-01

    The nitrogenase gene cluster in cyanobacteria has been thought to comprise multiple operons; however, in Anabaena variabilis, the promoter for the first gene in the cluster, nifB1, appeared to be the primary promoter for the entire nif cluster. The structural genes nifHDK1 were the most abundant transcripts; however, their abundance was not controlled by an independent nifH1 promoter, but rather, by RNA processing, which produced a very stable nifH1 transcript and a moderately stable nifD1 transcript. There was also no separate promoter for nifEN1. In addition to the nifB1 promoter, there were weak promoters inside the nifU1 gene and inside the nifE1 gene, and both promoters were heterocyst specific. In an xisA mutant, which effectively separated promoters upstream of an 11-kb excision element in nifD1 from the downstream genes, the internal nifE1 promoter was functional. Transcription of the nif1 genes downstream of the 11-kb element, including the most distant genes, hesAB1 and fdxH1, was reduced in the xisA mutant, indicating that the nifB1 promoter contributed to their expression. However, with the exception of nifK1 and nifE1, which had no expression, the downstream genes showed low to moderate levels of transcription in the xisA mutant. The hesA1 gene also had a promoter, but the fdxH gene had a processing site just upstream of the gene. The processing of transcripts at sites upstream of nifH1 and fdxH1 correlated with increased stability of these transcripts, resulting in greater amounts than transcripts that were not close to processing sites. PMID:25092030

  16. Abstract The unicellular cyanobacterium Synechoc-cocus leopoliensis is used in a micro-electrochemical

    E-print Network

    Carpentier, Robert

    . This is the case for several quinone-type herbicides such as phe- nol, urea, and triazine derivatives (Pfister et- propriate potential (Agostiano et al. 1992; Goetze and Carpentier 1990) L. Croisetière · R. Carpentier 5057 R. Rouillon Université de Perpignan,

  17. Molecular investigation of the radiation resistance of edible cyanobacterium Arthrospira sp. PCC 8005

    PubMed Central

    Badri, Hanène; Monsieurs, Pieter; Coninx, Ilse; Wattiez, Ruddy; Leys, Natalie

    2015-01-01

    The aim of this work was to characterize in detail the response of Arthrospira to ionizing radiation, to better understand its radiation resistance capacity. Live cells of Arthrospira sp. PCC 8005 were irradiated with 60Co gamma rays. This study is the first, showing that Arthrospira is highly tolerant to gamma rays, and can survive at least 6400 Gy (dose rate of 527 Gy h?1), which identified Arthrospira sp. PCC 8005 as a radiation resistant bacterium. Biochemical, including proteomic and transcriptomic, analysis after irradiation with 3200 or 5000 Gy showed a decline in photosystem II quantum yield, reduced carbon fixation, and reduced pigment, lipid, and secondary metabolite synthesis. Transcription of photo-sensing and signaling pathways, and thiol-based antioxidant systems was induced. Transcriptomics did show significant activation of ssDNA repair systems and mobile genetic elements (MGEs) at the RNA level. Surprisingly, the cells did not induce the classical antioxidant or DNA repair systems, such superoxide dismutase (SOD) enzyme and the RecA protein. Arthrospira cells lack the catalase gene and the LexA repressor. Irradiated Arthrospira cells did induce strongly a group of conserved proteins, of which the function in radiation resistance remains to be elucidated, but which are a promising novel routes to be explored. This study revealed the radiation resistance of Arthrospira, and the molecular systems involved, paving the way for its further and better exploitation. PMID:25678338

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

    PubMed Central

    Zhang, Yanan; Niu, Xiangfeng; Shi, Mengliang; Pei, Guangsheng; Zhang, Xiaoqing; Chen, Lei; Zhang, Weiwen

    2015-01-01

    Cyanobacteria have been engineered to produce ethanol through recent synthetic biology efforts. However, one major challenge to the cyanobacterial systems for high-efficiency ethanol production is their low tolerance to the ethanol toxicity. With a major goal to identify novel transporters involved in ethanol tolerance, we constructed gene knockout mutants for 58 transporter-encoding genes of Synechocystis sp. PCC 6803 and screened their tolerance change under ethanol stress. The efforts allowed discovery of a mutant of slr0982 gene encoding an ATP-binding cassette transporter which grew poorly in BG11 medium supplemented with 1.5% (v/v) ethanol when compared with the wild type, and the growth loss could be recovered by complementing slr0982 in the ?slr0982 mutant, suggesting that slr0982 is involved in ethanol tolerance in Synechocystis. To decipher the tolerance mechanism involved, a comparative metabolomic and network-based analysis of the wild type and the ethanol-sensitive ?slr0982 mutant was performed. The analysis allowed the identification of four metabolic modules related to slr0982 deletion in the ?slr0982 mutant, among which metabolites like sucrose and L-pyroglutamic acid which might be involved in ethanol tolerance, were found important for slr0982 deletion in the ?slr0982 mutant. This study reports on the first transporter related to ethanol tolerance in Synechocystis, which could be a useful target for further tolerance engineering. In addition, metabolomic and network analysis provides important findings for better understanding of the tolerance mechanism to ethanol stress in Synechocystis. PMID:26052317

  19. Abstract Nostoc punctiforme is a phenotypically com-plex, filamentous, nitrogen-fixing cyanobacterium, whose

    E-print Network

    Summers, Michael L.

    . punctiforme ideal for detailed molecular characterization of a bacterium with a complex life cycle. Vegetative developmental direction is deter- mined by environmental signals. The vegetative cell cycle is maintained when. Phosphate limita- tion induces the transient differentiation of akinetes, spore-like cells resistant to cold

  20. Potassium uptake in the unicellular cyanobacterium Synechocystis sp. strain PCC 6803 mainly depends on

    E-print Network

    Roegner, Matthias

    defective in kdpA and ntpJ were generated and characterized to address the role of the Kdp and KtrAB systems at limiting potassium, but a vvkdpAvvntpJ double mutant is not viable, indicating a role of Kdp for potas-a/nity potassium pump of bacteria is the Kdp-ATPase, studied extensively in E. coli [1,7,8]. The four subunits

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

    PubMed Central

    Cassier-Chauvat, Corinne; Chauvat, Franck

    2014-01-01

    Ferredoxins (Fed), occurring in most organisms, are small proteins that use their iron-sulfur cluster to distribute electrons to various metabolic pathways, likely including hydrogen production. Here, we summarize the current knowledge on ferredoxins in cyanobacteria, the prokaryotes regarded as important producers of the oxygenic atmosphere and biomass for the food chain, as well as promising cell factories for biofuel production. Most studies of ferredoxins were performed in the model strain, Synechocystis PCC6803, which possesses nine highly-conserved ferredoxins encoded by monocistronic or operonic genes, some of which are localized in conserved genome regions. Fed1, encoded by a light-inducible gene, is a highly abundant protein essential to photosynthesis. Fed2-Fed9, encoded by genes differently regulated by trophic conditions, are low-abundant proteins that play prominent roles in the tolerance to environmental stresses. Concerning the selectivity/redundancy of ferredoxin, we report that Fed1, Fed7 and Fed9 belong to ferredoxin-glutaredoxin-thioredoxin crosstalk pathways operating in the protection against oxidative and metal stresses. Furthermore, Fed7 specifically interacts with a DnaJ-like protein, an interaction that has been conserved in photosynthetic eukaryotes in the form of a composite protein comprising DnaJ- and Fed7-like domains. Fed9 specifically interacts with the Flv3 flavodiiron protein acting in the photoreduction of O2 to H2O. PMID:25387163

  2. Cloning and gene arrangement of PSAC, NDHE and NDHD from the cyanobacterium Synechocystis sp. PCC 6803

    SciTech Connect

    Anderson, S.L.; McIntosh, L. )

    1990-05-01

    In higher plants the psaC gene, which encodes the 9 kDa 2(Fe-4S) containing Photosystem I subunit, is located in the small single copy region of the chloroplast DNA between two ORF's with homology to genes encoding subunits of the mitochondrial NADH Dehydrogenase complex. The psaC gene has been cloned from Synechocystis and analysis of the flanking sequences has shown the 5'ndhE-psaCndhD3{prime} arrangement of higher plants is only partially conserved in Synechocystis. An open reading frame 5{prime} to psaC has 79% identity to the maize ndhE gene. Downstream of psaC there is an open reading frame of only 273 bp with 48% identity to the 5{prime} end of the maize ndhD gene (1,545 bp). Southern analysis shows that psaC, ndhE and the region of homology to ndhD are present in only a single copy in the Synechocystis genome. Probes to the 3{prime} portion of the wheat ndhD gene did not hybridize to Synechocystis or Anabaena genomic DNA, but did hybridize to Oenothera chloroplast DNA, indicating the entire ndhD gene is not present in these cyanobacteria.

  3. Genetic studies on a nitrogen-fixing cyanobacterium. [Anabaena; Escherichi coli

    SciTech Connect

    Wolk, C.P.; Cardemil, L.; Elhai, J.; Flores, E.; Murry, M.; Schmetterer, G.; Schrautemeier, B.

    1987-04-01

    Mutants of Anabaena PCC7120 capable of aerobic growth with NO/sub 3//sup -/ but not N/sub 2/, and capable of microaerobic reduction of C/sub 2/H/sub 2/, were isolated by penicillin enrichment after UV irradiation. Heterocysts of two mutants lack the principal envelope glycolipid, those of EF116 have a non-cohesive envelope polysaccharide, and those of other strains have other defects. A Nm/sup r/ cosmid library of DNA from wild type Anabaena PCC7120 was established in Escherichia coli bearing the Ap helper plasmid pDS4101. A conjugative plasmid was introduced, and the bacteria replicated to lawns of individual mutant strains of Anabaena. After one day of non-selective growth, selection was applied for Nm/sup r/ and nitrogen fixation. Overlapping cosmids complementing EF116 and one complementing another mutant have been mapped. The complementing genes are thought to act early in differentiation. Inclusion, in an E. coli donor of an appropriate methylase gene enhanced, by a factor of 10/sup 2/ to 10/sup 3/, transfer to Anabaena PCC7120 of a plasmid containing numerous sites for the Anabaena restriction endonuclease, AvaII.

  4. Ionizing-radiation resistance in the desiccation-tolerant cyanobacterium Chroococcidiopsis

    NASA Technical Reports Server (NTRS)

    Billi, D.; Friedmann, E. I.; Hofer, K. G.; Caiola, M. G.; Ocampo-Friedmann, R.

    2000-01-01

    The effect of X-ray irradiation on cell survival, induction, and repair of DNA damage was studied by using 10 Chroococcidiopsis strains isolated from desert and hypersaline environments. After exposure to 2.5 kGy, the percentages of survival for the strains ranged from 80 to 35%. In the four most resistant strains, the levels of survival were reduced by 1 or 2 orders of magnitude after irradiation with 5 kGy; viable cells were recovered after exposure to 15 kGy but not after exposure to 20 kGy. The severe DNA damage evident after exposure to 2.5 kGy was repaired within 3 h, and the severe DNA damage evident after exposure to 5 kGy was repaired within 24 h. The increase in trichloroacetic acid-precipitable radioactivity in the culture supernatant after irradiation with 2.5 kGy might have been due to cell lysis and/or an excision process involved in DNA repair. The radiation resistance of Chroococcidiopsis strains may reflect the ability of these cyanobacteria to survive prolonged desiccation through efficient repair of the DNA damage that accumulates during dehydration.

  5. Iron Superoxide Dismutase Protects against Chilling Damage in the Cyanobacterium Synechococcus species PCC79421

    E-print Network

    Thomas, Dave

    of the Calvin cycle and other soluble enzymes with- out causing a concomitant decrease in light harvesting2. Produc- tion of H2O2 from O2 further inhibits specific enzymes of the Calvin cycle (Kaiser, 1979

  6. A Model of Cyclic Transcriptomic Behavior in Cyanobacterium Cyanothece sp. ATCC 51142

    SciTech Connect

    McDermott, Jason E.; Oehmen, Christopher S.; McCue, Lee Ann; Hill, Eric A.; Choi, Daniel M.; Stockel, Jana; Liberton, Michelle L.; Pakrasi, Himadri B.; Sherman, Louis A.

    2011-07-01

    Systems biology attempts to reconcile large amounts of disparate data with existing knowledge to provide models of functioning biological systems. Useful and predictive models aim to summarize complex and dynamic processes and represent the relationships between these processes. The cyanobacterial Cyanothece species Strain sp. ATCC 51142 is an excellent candidate for such systems studies because: (i) it displays tight functional regulation as it must separate the opposing processes of oxygen-generating photosynthesis and oxygen-sensitive nitrogen fixation temporally in the same cell, ; (ii) it has robust cyclic patterns at the genetic, protein and metabolomic levels, ; and (iii) and it has potential applications for bioenergy and carbon sequestration, and thus a predictive model of its function is of practical use. We have represented the transcriptomic data from Cyanothece 51142 under diurnal light/dark cycles as a high-level functional abstraction and describe development of a predictive in silico model of diurnal and circadian behavior in terms of regulatory and metabolic processes in Cyanothece 51142. Our model provides a way to integrate disparate data types into a framework that can be used to explain behavior, generate high-quality predictions for validation, and to suggest future experiments. We show that incorporating network topology into the model improves performance in terms of our ability to explain the behavior of the system under new conditions. The model presented robustly describes transcriptomic behavior of Cyanothece 51142 under different cyclic and non-cyclic growth conditions robustly, and represents a significant advance in the understanding of gene regulation in this important organism.

  7. Expanding the Described Metabolome of the Marine Cyanobacterium Moorea producens JHB through Orthogonal Natural Products Workflows

    PubMed Central

    Boudreau, Paul D.; Monroe, Emily A.; Mehrotra, Suneet; Desfor, Shane; Korobeynikov, Anton; Sherman, David H.; Murray, Thomas F.; Gerwick, Lena; Dorrestein, Pieter C.; Gerwick, William H.

    2015-01-01

    Moorea producens JHB, a Jamaican strain of tropical filamentous marine cyanobacteria, has been extensively studied by traditional natural products techniques. These previous bioassay and structure guided isolations led to the discovery of two exciting classes of natural products, hectochlorin (1) and jamaicamides A (2) and B (3). In the current study, mass spectrometry-based ‘molecular networking’ was used to visualize the metabolome of Moorea producens JHB, and both guided and enhanced the isolation workflow, revealing additional metabolites in these compound classes. Further, we developed additional insight into the metabolic capabilities of this strain by genome sequencing analysis, which subsequently led to the isolation of a compound unrelated to the jamaicamide and hectochlorin families. Another approach involved stimulation of the biosynthesis of a minor jamaicamide metabolite by cultivation in modified media, and provided insights about the underlying biosynthetic machinery as well as preliminary structure-activity information within this structure class. This study demonstrated that these orthogonal approaches are complementary and enrich secondary metabolomic coverage even in an extensively studied bacterial strain. PMID:26222584

  8. Occurrence of the hepatotoxic cyanobacterium Nodularia spumigena in the Baltic Sea and structure of the toxin.

    PubMed Central

    Sivonen, K; Kononen, K; Carmichael, W W; Dahlem, A M; Rinehart, K L; Kiviranta, J; Niemela, S I

    1989-01-01

    Water blooms formed by potentially toxic species of cyanobacteria are a common phenomenon in the Baltic Sea in late summer. Twenty-five cyanobacterial bloom samples were collected from open and coastal waters of the Baltic Sea during 1985 to 1987, and their toxicity was determined by mouse bioassay. All of 5 bloom samples from the southern Baltic Sea, 6 of 6 from the open northern Baltic Sea (Gulf of Finland), and 7 of 14 Finnish coastal samples were found to contain hepatotoxic cyanobacteria. Nodularia spumigena and Aphanizomenon flos-aquae occurred together in high amounts in blooms from the open-sea areas. In addition, coastal samples contained the species Anabaena lemmermannii, Microcystis aeruginosa, and Oscillatoria agardhii. Eighteen hepatotoxic N. spumigena cultures were isolated from water bloom and open-sea water samples. High-pressure liquid chromatographic analysis of both hepatotoxic bloom samples and Nodularia strains showed a single toxic fraction. The toxin concentrations of the blooms were less than or equal to 2.4 mg/g of freeze-dried material, and those of laboratory-grown cultures were 2.5 to 8.0 mg/g of freeze-dried cells. A single toxin was isolated from three N. spumigena-containing bloom samples and three N. spumigena laboratory isolates. Amino acid analysis and low- and high-resolution fast-atom bombardment mass spectroscopy indicated that the toxin from all of the sources was a cyclic pentapeptide (molecular weight, 824) containing glutamic acid, beta-methylaspartic acid, arginine, N-methyldehydrobutyrine, and 3-amino-9-methoxy-2,6,8-trimethyl-10-phenyl-4,6-decadienoic acid.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2506812

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

    SciTech Connect

    Welkie, David G.; Sherman, Debra M.; Chrisler, William B.; Orr, Galya; Sherman, Louis A.

    2013-10-19

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

  10. A novel periplasmic protein (Slr0280) tunes photomixotrophic growth of the cyanobacterium, Synechocystis sp. PCC 6803.

    PubMed

    Dong, Liang-Liang; Li, Qing-Dong; Wu, Dong; Sun, Ya-Fang; Zhou, Ming; Zhao, Kai-Hong

    2016-01-10

    Cyanobacteria are among the main contributors to global photosynthesis and show a high degree of metabolic plasticity. Synechocystis sp. PCC 6803 can grow under photoautotrophic, photomixotrophic or photoheterotrophic conditions. We have characterized a novel periplasmic protein (Slr0280) that tunes the photomixotrophic growth of Synechocystis sp. PCC 6803. Slr0280 is a multi-domain protein consisting mainly of ?-sheets. Several proteins that interact with Slr0280 were identified via bacterial two-hybrid screening. Slr0280 may interact through its DUF2233 domain with partners that participate in sugar metabolism, thereby coordinating the respective regulations. When slr0280 was deleted, the mutant grew more slowly than wild-type in the presence of glucose, which is ascribed to the down-regulation of glycolysis, glycogen catabolism, oxidative pentose phosphate pathway, Calvin cycle and glucose utilization. A positive regulation of Slr0280 on these sugar catabolic enzymes was confirmed by transcript (qPCR) analyses. Based on these findings, we proposed a speculative model that Slr0280 plays a coordinating regulatory role in sugar metabolism. PMID:26367329

  11. Lyngbyabellins K-N from Two Palmyra Atoll Collections of the Marine Cyanobacterium Moorea bouillonii

    PubMed Central

    Byrum, Tara; Valeriote, Frederick A.; Gerwick, William H.

    2014-01-01

    Five lipopeptides of the lyngbyabellin structure class, four cyclic (1-3, and 5) and one linear (4), were isolated from the extracts of two collections of filamentous marine cyanobacteria obtained from Palmyra Atoll in the Central Pacific Ocean. Their planar structures and absolute configurations were elucidated by combined spectroscopic and chromatographic analyses as well as chemical synthesis of fragments. In addition to structural features typical of the lyngbyabellins, such as two thiazole rings and a chlorinated 2-methyloctanoate residue, these new compounds possess several unique aspects. Of note, metabolites 2 and 3 possessed rare mono-chlorination on the 3-acyloxy-2-methyloctanoate residue while lyngbyabellin N (5) had an unusual N,N-dimethylvaline terminus. Lyngbyabellin N also possessed a leucine statine residue, and showed strong cytotoxic activity against HCT116 colon cancer cell line (IC50 = 40.9 ± 3.3 nM). PMID:24574859

  12. Lyngbyabellins K-N from Two Palmyra Atoll Collections of the Marine Cyanobacterium Moorea bouillonii.

    PubMed

    Choi, Hyukjae; Mevers, Emily; Byrum, Tara; Valeriote, Frederick A; Gerwick, William H

    2012-09-01

    Five lipopeptides of the lyngbyabellin structure class, four cyclic (1-3, and 5) and one linear (4), were isolated from the extracts of two collections of filamentous marine cyanobacteria obtained from Palmyra Atoll in the Central Pacific Ocean. Their planar structures and absolute configurations were elucidated by combined spectroscopic and chromatographic analyses as well as chemical synthesis of fragments. In addition to structural features typical of the lyngbyabellins, such as two thiazole rings and a chlorinated 2-methyloctanoate residue, these new compounds possess several unique aspects. Of note, metabolites 2 and 3 possessed rare mono-chlorination on the 3-acyloxy-2-methyloctanoate residue while lyngbyabellin N (5) had an unusual N,N-dimethylvaline terminus. Lyngbyabellin N also possessed a leucine statine residue, and showed strong cytotoxic activity against HCT116 colon cancer cell line (IC50 = 40.9 ± 3.3 nM). PMID:24574859

  13. 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

    Understanding phytoplankton photosynthesis is critical to several fields including ecology and global biogeochemistry. The efficiency with which phytoplankton fix carbon depends upon the ambient light field, which is in turn dependent upon sun angle and the depth of mixing in the water column. In this pilot project, Synechocystis PCC 6803 was chosen as a model organism with which to study the molecular and physiological responses of phytoplankton to diurnal changes in light levels. Advantages of using this organism include that its genome has been sequenced, allowing the use of microarray technology, that it is readily grown as single colonies on plates and in liquid cultures, and that it is easy to manipulate genetically (generate and complement mutants). Axenic cultures of Synechocystis were grown under precisely controlled conditions in a "cyclodyne", a chemostat in which the light intensity cycles to mimic diurnal changes in light level, where the light consisted of sinusoidal daylight (400 ? mol photons m-2 s-1 at noon) followed by 12 hours of darkness for several weeks. After one week to allow the cells to acclimate to the light conditions, the cultures were sampled and extracted for RNA analysis every two hours over the course of several days. At these time points, absorption spectra, light scattering and chlorophyll a concentrations were determined. Initial results from Northern Blot hybridizations (examining RNA levels for individual genes) indicate that, the transcripts encoding photosynthetic proteins (i.e., PsbA2, PsaA and CpcB, in photosystem II, photosystem I, and phycobilisomes, respectively) are highest during the light. Initial results show that in the middle of the night, the psbA2 transcripts are 2-fold less while the psaA and cpcB are greater than 4-fold less than in the middle of the day. For the most part, the transcripts encoding photosynthetic proteins track the light cycle, although with different trends at daybreak and after night falls. 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.

  14. Structural Basis for the Thermostability of Ferredoxin from the Cyanobacterium Mastigocladus laminosus

    E-print Network

    Lebendiker, Mario

    , algae, and photosynthetic bacteria, denoted as plant-type ferredoxins, have a single [2Fe-2S] cluster The Department of Plant Sciences, The Institute of Life Sciences, The Hebrew University of Jerusalem, Givat Ram, Israel Plant-type ferredoxins (Fds) carry a single [2Fe-2S] cluster and serve as electron acceptors

  15. Novel Thermotolerant Siderophilic Filamentous Cyanobacterium that Produces Intracellular Iron-Rich Phases

    NASA Technical Reports Server (NTRS)

    Broun, Igor I.; Bryant, Donald A.; Casamatta, Dale; Thomas-Keprta, Kathie L.; Sarkisova, Svetlana A.; Shen, Gaozhang; Graham, Joel E.; Boyd, Eric S.; Peters, John W.; Garrison, Daniel H.; McKay, David S.

    2010-01-01

    Cyanobacteria are the main producers of organic compounds in iron-depositing hot springs despite photosynthetically generated-oxygen and the abundance of reduced iron (Fe2+) that likely leads to enormous oxidative stress within cyanobacterial cells. Therefore, the study of cyanobacterial diversity, phylogeny, and biogeochemical activity in iron-depositing hot springs will not only provide insights into the contribution of CB to iron redox cycling in these environments, but it could also provide insights into CB evolution. This study characterizes the phylogeny, morphology, and physiology of isolate JSC-1, a novel filamentous CB isolated from an iron-depositing hot spring. While isolate JSC-1 is morphologically similar to the CB genus Leptolyngbya, 16S rDNA sequence data indicated that it shares 95 percent sequence similarity to the type strain L. boryanum. Strain JSC-1 fixes N2 and exhibited an unusually high ratio between photosystem (PS) I and PS II and was capable of complementary chromatic adaptation. Further, it synthesized only chlorophyll a and a unique set of carotenoids. Strain JSC-1 not only required high levels of Fe for growth (greater than or equal to 40 microM), but it also accumulated large amounts of extracellular ferrihydrite and generated intracellular ferric phosphates. Strain JSC-1 was found to secrete 2-oxoglutaric acid and possesses one ortholog and one paralog of bacterioferritin. Surprisingly, the latter has 70.13 % identity with a bacterioferritin in marine-proteobacterium HTCC 2080 and has joint node with bacterioferritins found in enterobacteria. Collectively, these observations provide insights into the physiological strategies that might have allowed CB to develop and proliferate in Fe-rich environments. Based on its genotypic and phenotypic characterization of strain, JSC-1 represents a new operational taxonomical unit (OTU) JSC-1.

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

    PubMed Central

    2014-01-01

    Background The production of biofuels in photosynthetic microalgae and cyanobacteria is a promising alternative to the generation of fuels from fossil resources. To be economically competitive, producer strains need to be established that synthesize the targeted product at high yield and over a long time. Engineering cyanobacteria into forced fuel producers should considerably interfere with overall cell homeostasis, which in turn might counteract productivity and sustainability of the process. Therefore, in-depth characterization of the cellular response upon long-term production is of high interest for the targeted improvement of a desired strain. Results The transcriptome-wide response to continuous ethanol production was examined in Synechocystis sp. PCC6803 using high resolution microarrays. In two independent experiments, ethanol production rates of 0.0338% (v/v) ethanol d-1 and 0.0303% (v/v) ethanol d-1 were obtained over 18 consecutive days, measuring two sets of biological triplicates in fully automated photobioreactors. Ethanol production caused a significant (~40%) delay in biomass accumulation, the development of a bleaching phenotype and a down-regulation of light harvesting capacity. However, microarray analyses performed at day 4, 7, 11 and 18 of the experiment revealed only three mRNAs with a strongly modified accumulation level throughout the course of the experiment. In addition to the overexpressed adhA (slr1192) gene, this was an approximately 4 fold reduction in cpcB (sll1577) and 3 to 6 fold increase in rps8 (sll1809) mRNA levels. Much weaker modifications of expression level or modifications restricted to day 18 of the experiment were observed for genes involved in carbon assimilation (Ribulose bisphosphate carboxylase and Glutamate decarboxylase). Molecular analysis of the reduced cpcB levels revealed a post-transcriptional processing of the cpcBA operon mRNA leaving a truncated mRNA cpcA* likely not competent for translation. Moreover, western blots and zinc-enhanced bilin fluorescence blots confirmed a severe reduction in the amounts of both phycocyanin subunits, explaining the cause of the bleaching phenotype. Conclusions Changes in gene expression upon induction of long-term ethanol production in Synechocystis sp. PCC6803 are highly specific. In particular, we did not observe a comprehensive stress response as might have been expected. PMID:24502290

  17. First report of saxitoxin production by a species of the freshwater benthic cyanobacterium, Scytonema Agardh.

    PubMed

    Smith, Francine M J; Wood, Susanna A; van Ginkel, Roel; Broady, Paul A; Gaw, Sally

    2011-03-15

    Saxitoxins or paralytic shellfish poisons (PSP) are neurotoxins produced by some species of freshwater cyanobacteria and marine dinoflagellates. Samples collected from the metaphyton of a drinking-water supply's pre-treatment reservoir and a small eutrophic lake in New Zealand returned positive results when screened using a Jellett PSP Rapid Test Kit. The dominant species in the sample was identified as Scytonema cf. crispum. A non-axenic clonal culture (UCFS10) was isolated from the lake. The partial 16S rRNA gene sequence shared only a 91% or less sequence similarity with other Scytonema species, indicating that it is unlikely that this genus is monophyletic and that further in-depth phylogenetic re-evaluation is required. The sxtA gene, which is known to be involved in saxitoxin production, was detected in UCFS10. Saxitoxin concentrations were determined from the lake samples and from UCFS10 using pre-column oxidation high performance liquid chromatography with fluorescence detection. Saxitoxin was the only variant detected and this was found at concentrations of 65.6 ?g g?¹ dry weight in the lake sample and 119.4 ?g g?¹ dry weight or 1.3 pg cell?¹ in UCFS10. This is the first confirmation of a saxitoxin-producing species in New Zealand and the first report of saxitoxin production by a species of Scytonema. PMID:21223973

  18. Biodegradation of polychlorinated biphenyls (PCBs) by the novel identified cyanobacterium Anabaena PD-1

    PubMed Central

    Zhang, Hangjun; Jiang, Xiaojun; Lu, Liping; Xiao, Wenfeng

    2015-01-01

    Polychlorinated biphenyls (PCBs), a class of hazardous pollutants, are difficult to dissipate in the natural environment. In this study, a cyanobacterial strain Anabaena PD-1 showed good resistance against PCB congeners. Compared to a control group, chlorophyll a content decreased 3.7% and 11.7% when Anabaena PD-1 was exposed to 2 and 5 mg/L PCBs for 7 d. This cyanobacterial strain was capable of decomposing PCB congeners which was conclusively proved by determination of chloride ion concentrations in chlorine-free medium. After 7 d, the chloride ion concentrations in PCB-treated groups (1, 2, 5 mg/L) were 3.55, 3.05, and 2.25 mg/L, respectively. The genetic information of strain PD-1 was obtained through 16S rRNA sequencing analysis. The GenBank accession number of 16S rRNA of Anabaena PD-1 was KF201693.1. Phylogenetic tree analysis clearly indicated that Anabaena PD-1 belonged to the genus Anabaena. The degradation half-life of Aroclor 1254 by Anabaena PD-1 was 11.36 d; the total degradation rate for Aroclor 1254 was 84.4% after 25 d. Less chlorinated PCB congeners were more likely to be degraded by Anabaena PD-1 in comparison with highly chlorinated congeners. Meta- and para-chlorines in trichlorodiphenyls and tetrachlorobiphenyls were more susceptible to dechlorination than ortho-chlorines during the PCB-degradation process by Anabaena PD-1. Furthermore, Anabaena PD-1 can decompose dioxin-like PCBs. The percent biodegradation of 12 dioxin-like PCBs by strain PD-1 ranged from 37.4% to 68.4% after 25 days. Results above demonstrate that Anabaena PD-1 is a PCB-degrader with great potential for the in situ bioremediation of PCB-contaminated paddy soils. PMID:26177203

  19. Genomic insights into the physiology and ecology of the marine filamentous cyanobacterium Lyngbya majuscula

    PubMed Central

    Jones, Adam C.; Monroe, Emily A.; Podell, Sheila; Hess, Wolfgang R.; Klages, Sven; Esquenazi, Eduardo; Niessen, Sherry; Hoover, Heather; Rothmann, Michael; Lasken, Roger S.; Yates, John R.; Reinhardt, Richard; Kube, Michael; Burkart, Michael D.; Allen, Eric E.; Dorrestein, Pieter C.; Gerwick, William H.; Gerwick, Lena

    2011-01-01

    Filamentous cyanobacteria of the genus Lyngbya are important contributors to coral reef ecosystems, occasionally forming dominant cover and impacting the health of many other co-occurring organisms. Moreover, they are extraordinarily rich sources of bioactive secondary metabolites, with 35% of all reported cyanobacterial natural products deriving from this single pantropical genus. However, the true natural product potential and life strategies of Lyngbya strains are poorly understood because of phylogenetic ambiguity, lack of genomic information, and their close associations with heterotrophic bacteria and other cyanobacteria. To gauge the natural product potential of Lyngbya and gain insights into potential microbial interactions, we sequenced the genome of Lyngbya majuscula 3L, a Caribbean strain that produces the tubulin polymerization inhibitor curacin A and the molluscicide barbamide, using a combination of Sanger and 454 sequencing approaches. Whereas ?293,000 nucleotides of the draft genome are putatively dedicated to secondary metabolism, this is far too few to encode a large suite of Lyngbya metabolites, suggesting Lyngbya metabolites are strain specific and may be useful in species delineation. Our analysis revealed a complex gene regulatory network, including a large number of sigma factors and other regulatory proteins, indicating an enhanced ability for environmental adaptation or microbial associations. Although Lyngbya species are reported to fix nitrogen, nitrogenase genes were not found in the genome or by PCR of genomic DNA. Subsequent growth experiments confirmed that L. majuscula 3L is unable to fix atmospheric nitrogen. These unanticipated life history characteristics challenge current views of the genus Lyngbya. PMID:21555588

  20. Genomic insights into the physiology and ecology of the marine filamentous cyanobacterium Lyngbya majuscula.

    PubMed

    Jones, Adam C; Monroe, Emily A; Podell, Sheila; Hess, Wolfgang R; Klages, Sven; Esquenazi, Eduardo; Niessen, Sherry; Hoover, Heather; Rothmann, Michael; Lasken, Roger S; Yates, John R; Reinhardt, Richard; Kube, Michael; Burkart, Michael D; Allen, Eric E; Dorrestein, Pieter C; Gerwick, William H; Gerwick, Lena

    2011-05-24

    Filamentous cyanobacteria of the genus Lyngbya are important contributors to coral reef ecosystems, occasionally forming dominant cover and impacting the health of many other co-occurring organisms. Moreover, they are extraordinarily rich sources of bioactive secondary metabolites, with 35% of all reported cyanobacterial natural products deriving from this single pantropical genus. However, the true natural product potential and life strategies of Lyngbya strains are poorly understood because of phylogenetic ambiguity, lack of genomic information, and their close associations with heterotrophic bacteria and other cyanobacteria. To gauge the natural product potential of Lyngbya and gain insights into potential microbial interactions, we sequenced the genome of Lyngbya majuscula 3L, a Caribbean strain that produces the tubulin polymerization inhibitor curacin A and the molluscicide barbamide, using a combination of Sanger and 454 sequencing approaches. Whereas ? 293,000 nucleotides of the draft genome are putatively dedicated to secondary metabolism, this is far too few to encode a large suite of Lyngbya metabolites, suggesting Lyngbya metabolites are strain specific and may be useful in species delineation. Our analysis revealed a complex gene regulatory network, including a large number of sigma factors and other regulatory proteins, indicating an enhanced ability for environmental adaptation or microbial associations. Although Lyngbya species are reported to fix nitrogen, nitrogenase genes were not found in the genome or by PCR of genomic DNA. Subsequent growth experiments confirmed that L. majuscula 3L is unable to fix atmospheric nitrogen. These unanticipated life history characteristics challenge current views of the genus Lyngbya. PMID:21555588

  1. Changes in membrane lipid composition during saline growth of the fresh water cyanobacterium Synechococcus 6311

    NASA Technical Reports Server (NTRS)

    Huflejt, M. E.; Tremolieres, A.; Pineau, B.; Lang, J. K.; Hatheway, J.; Packer, L.

    1990-01-01

    Growth of Synechococcus 6311 in the presence of 0.5 molar NaCl is accompanied by significant changes in membrane lipid composition. Upon transfer of the cells from a low salt' (0.015 molar NaCl) to high salt' (0.5 molar NaCl) growth medium at different stages of growth, a rapid decrease in palmitoleic acid (C16:1 delta 9) content was accompanied by a concomitant increase in the amount of the two C18:1 acids (C18:1 delta 9, C18:1 delta 11), with the higher increase in oleic acid C18:1 delta 9 content. These changes began to occur within the first hour after the sudden elevation of NaCl and progressed for about 72 hours. The percentage of palmitic acid (C16:0) and stearic acid (C18:0) remained almost unchanged in the same conditions. High salt-dependent changes within ratios of polar lipid classes also occurred within the first 72 hours of growth. The amount of monogalactosyl diacylglycerol (bilayer-destabilizing lipid) decreased and that of the digalactosyl diacylglycerol (bilayer-stabilizing lipid) increased. Consequently, in the three day old cells, the ratio of monogalactosyl diacylglycerol to digalactosyl diacylglycerol in the membranes of high salt-grown cells was about half of that in the membranes of low salt-grown cells. The total content of anionic lipids (phosphatidylglycerol and sulfoquinovosyl diacylglycerol) was always higher in the isolated membranes and the whole cells from high salt-grown cultures compared to that in the cells and membranes from low salt-grown cultures. All the observed rearrangements in the lipid environment occurred in both thylakoid and cytoplasmic membranes. Similar lipid composition changes, however, to a much lesser extent, were also observed in the aging, low salt-grown cultures. The observed changes in membrane fatty acids and lipids composition correlate with the alterations in electron and ion transport activities, and it is concluded that the rearrangement of the membrane lipid environment is an essential part of the process by which cells control membrane function and stability.

  2. Cytology of long-term desiccation in the desert cyanobacterium Chroococcidiopsis (Chroococcales)

    NASA Technical Reports Server (NTRS)

    Caiola, M. G.; Ocampo-Friedmann, R.; Friedmann, E. I.

    1993-01-01

    Young and old cultures (up to 66 months) of two Chroococcidiopsis sp. strains isolated from the Negev desert, Israel, were examined by epifluorescence and electron microscopy. In old cultures, cell viability and autofluorescence were lower than in young cultures. An increase was seen with age in the polysaccharide content of the sheaths of nanocytes and nanocyte mother cells, and a decrease of phycobiliproteins was also seen. In the oldest cultures most of the cells were dead and in various stages of degeneration. Single living cells were scattered among the dead ones. No resting cells were formed in the oldest cultures, but many cell groups showed highly electron-dense sheaths and, in the cytoplasm, ribosomes and glycogen. These changes in cell structure may have a role in preventing water loss from the cell.

  3. Characterization of carotenogenesis genes in the cyanobacterium Anabaena sp. PCC 7120.

    PubMed

    Masukawa, Hajime; Mochimaru, Mari; Takaichi, Shinichi

    2012-01-01

    Cyanobacteria produce many kinds of carotenoids for light harvesting and light protection in photosynthesis. To elucidate the biosynthetic pathways of carotenoids in Anabaena sp. PCC 7120 (also known as Nostoc sp. PCC 7120), we have produced gene-disruption mutants lacking selected proposed carotenoid biosynthetic enzymes. Here we describe the construction of mutants by triparental mating. A cargo plasmid, bearing a target gene interrupted by an antibiotic-resistant cassette, is transformed to E. coli donor containing a helper plasmid, and is introduced into Anabaena cells by conjugation. Double-reciprocal recombination replaces the target genes in Anabaena genome with mutated ones on the plasmid. Carotenoids in the selected double recombinants are identified using high-performance liquid chromatography. PMID:22623311

  4. Impairment of O-antigen production confers resistance to grazing in a model amoeba–cyanobacterium predator–prey system

    PubMed Central

    Simkovsky, Ryan; Daniels, Emy F.; Tang, Karen; Huynh, Stacey C.; Golden, Susan S.; Brahamsha, Bianca

    2012-01-01

    The grazing activity of predators on photosynthetic organisms is a major mechanism of mortality and population restructuring in natural environments. Grazing is also one of the primary difficulties in growing cyanobacteria and other microalgae in large, open ponds for the production of biofuels, as contaminants destroy valuable biomass and prevent stable, continuous production of biofuel crops. To address this problem, we have isolated a heterolobosean amoeba, HGG1, that grazes upon unicellular and filamentous freshwater cyanobacterial species. We have established a model predator–prey system using this amoeba and Synechococcus elongatus PCC 7942. Application of amoebae to a library of mutants of S. elongatus led to the identification of a grazer-resistant knockout mutant of the wzm ABC O-antigen transporter gene, SynPCC7942_1126. Mutations in three other genes involved in O-antigen synthesis and transport also prevented the expression of O-antigen and conferred resistance to HGG1. Complementation of these rough mutants returned O-antigen expression and susceptibility to amoebae. Rough mutants are easily identifiable by appearance, are capable of autoflocculation, and do not display growth defects under standard laboratory growth conditions, all of which are desired traits for a biofuel production strain. Thus, preventing the production of O-antigen is a pathway for producing resistance to grazing by certain amoebae. PMID:23012457

  5. Sequence of the nifD gene coding for the ? subunit of dinitrogenase from the cyanobacterium Anabaena

    PubMed Central

    Lammers, Peter J.; Haselkorn, Robert

    1983-01-01

    The nucleotide sequence of nifD, the structural gene for the ? subunit of dinitrogenase from Anabaena 7120, has been determined. The coding sequence contains 1,440 nucleotides, which predict an amino acid sequence of 480 residues and Mr of 54,283. The predicted sequence contains eight cysteines, of which five are conserved with respect to adjoining sequences and position relative to the ? subunits of dinitrogenase from Azotobacter, Clostridium, and Klebsiella. Because there are also five conserved cysteines in the ? subunit of Anabaena dinitrogenase [Mazur, B. J. & Chiu, C.-F. (1982) Proc. Natl. Acad. Sci. USA 79, 6782-6786], the number of cysteine residues participating as ligands to FeS clusters is likely to be 20 per ?2?2 tetramer. This number is sufficient to accommodate the known four Fe4S4 clusters, leaving at least four cysteines to be shared among the two FeMo cofactors and the more poorly characterized two-iron center. Although the ?- and ?-subunit gene sequences are not recognizably homologous, their secondary structures, predicted from the sequences, indicate similar domains around three of the conserved cysteine residues. PMID:16593347

  6. Effect of lambda cyhalothrin on Calothrix sp. (GUEco 1001), an autochthonous cyanobacterium of rice fields of Brahmaputra floodplain.

    PubMed

    Gupta, Kiran; Baruah, P P

    2015-12-01

    Pesticide contamination in the rice fields has manifested into a serious global environmental concern. Application of pesticides in the rice fields has deleterious effects on non-target organisms including nitrogen-fixing cyanobacteria which help to maintain the rice field fertility. In the present research endeavor, the effect of lambda cyhalothrin (5 % EC), a synthetic pyrethroid insecticide, has been studied on the growth and pigments content of Calothrix sp. (GUEco 1001), an indigenous strain isolated from rice grown areas of Brahmaputra floodplain. To study the toxic effect of lambda cyhalothrin, the test organism was exposed to varying concentrations of the insecticide i.e., 20 ppm, 40 ppm, 80 ppm, and 160 ppm based upon the determination of LC50 for a period of 20 days. The result obtained in the laboratory showed a progressive decrease in the growth and pigments content by the test organism with increasing concentrations of the lambda cyhalothrin against time dose-dependent manner. At high dose (160 ppm), the test organism showed significant decrease in dry weight biomass (54.5 %), chlorophyll-a (68 %), carotenoids (38 %), phycocyanin (80 %), and nitrogen contents (55 %) over the control. A little but insignificant stimulatory effect on growth and chlorophyll-a contents was recorded in 20 ppm treatment of the insecticide that, however, was reversed in case of carotenoids and phycocyanin contents. PMID:26377968

  7. Temporal variations in the dynamics of potentially microcystin-producing strains in a bloom-forming Planktothrix agardhii (Cyanobacterium) population.

    PubMed

    Briand, Enora; Gugger, Muriel; François, Jean-Christophe; Bernard, Cécile; Humbert, Jean-François; Quiblier, Catherine

    2008-06-01

    The concentration of microcystins (MCs) produced during blooms depends on variations in both the proportion of strains containing the genes involved in MC production and the MC cell quota (the ratio between the MC concentration and the density of cells with the mcyA genotype) for toxic strains. In order to assess the dynamics of MC-producing and non-MC-producing strains and to identify the impact of environmental factors on the relative proportions of these two subpopulations, we performed a 2-year survey of a perennial bloom of Planktothrix agardhii (cyanobacteria). Applying quantitative real-time PCR to the mcyA and phycocyanin genes, we found that the proportion of cells with the mcyA genotype varied considerably over time (ranging from 30 to 80% of the population). The changes in the proportion of cells with the mcyA genotype appeared to be inversely correlated to changes in the density of P. agardhii cells and also, to a lesser extent, to the availability of certain nutrients and the abundance of cladocerans. Among toxic cells, the MC cell quota varied throughout the survey. However, a negative correlation between the MC cell quota and the mcyA cell number during two short periods characterized by marked changes in the cyanobacterial biomass was found. Finally, only 54% of the variation in the MC concentrations measured in the lake can be explained by the dynamics of the density of cells with the MC producer genotype, suggesting that this measurement is not a satisfactory method for use in monitoring programs intended to predict the toxic risk associated with cyanobacterial proliferation. PMID:18441113

  8. Carbon assimilation and accumulation of cyanophycin during the development of dormant cells (akinetes) in the cyanobacterium Aphanizomenon ovalisporum

    PubMed Central

    Sukenik, Assaf; Maldener, Iris; Delhaye, Thomas; Viner-Mozzini, Yehudit; Sela, Dotan; Bormans, Myriam

    2015-01-01

    Akinetes are spore-like non-motile cells that differentiate from vegetative cells of filamentous cyanobacteria from the order Nostocales. They play a key role in the survival and distribution of these species and contribute to their perennial blooms. Here, we demonstrate variations in cellular ultrastructure during akinete formation concomitant with accumulation of cyanophycin; a copolymer of aspartate and arginine that forms storage granules. Cyanophycin accumulation is initiated in vegetative cells few days post-exposure to akinete inducing conditions. This early accumulated cyanophycin pool in vegetative cells disappears as a nearby cell differentiates to an akinete and stores large pool of cyanophycin. During the akinete maturation, the cyanophycin pool is further increased and comprise up to 2% of the akinete volume. The cellular pattern of photosynthetic activity during akinete formation was studied by a nano-metric scale secondary ion mass spectrometry (NanoSIMS) analysis in 13C-enriched cultures. Quantitative estimation of carbon assimilation in vegetative cells and akinetes (filament-attached and -free) indicates that vegetative cells maintain their basal activity while differentiating akinetes gradually reduce their activity. Mature-free akinetes practically lost their photosynthetic activity although small fraction of free akinetes were still photosynthetically active. Additional 13C pulse-chase experiments indicated rapid carbon turnover during akinete formation and de novo synthesis of cyanophycin in vegetative cells 4 days post-induction of akinete differentiation. PMID:26483781

  9. Construction of an obligate photoheterotrophic mutant of the cyanobacterium Synechocystis 6803: inactivation of the psbA gene family

    SciTech Connect

    Jansson, C.; Debus, R.J.; Osiewacz, H.D.; Gurevitz, M.; McIntosh, L.

    1987-10-01

    psbA in Synechocystis 6803 was found to belong to a small multigene family with three copies. The psbA gene family was inactivated in vitro by insertion of bacterial drug resistance markers. Inactivation of all three genes resulted in a transformant that is unable to grow photosynthetically but can be cultured photoheterotrophically. This mutant lacks oxygen evolving capacity but retains photosystem I activity. Room temperature measurements of chlorophyll a fluorescence induction demonstrated that the transformant exhibits a high fluorescence yield with little or no variable fluorescence. Immunoblot analyses showed complete loss of the psbA gene product (the DI polypeptide) from thylakoid membranes in the transformant. However, the extrinsic 33 kilodalton polypeptide of the water-splitting complex of photosystem II, is still present. The results indicate that assembly of a partial photosystem II complex may occur even in the absence of the intrinsic D1 polypeptide, a protein implicated as a crucial component of the photosystem II reaction center.

  10. Energy transfer in the chlorophyll f-containing cyanobacterium, Halomicronema hongdechloris, analyzed by time-resolved fluorescence spectroscopies.

    PubMed

    Akimoto, Seiji; Shinoda, Toshiyuki; Chen, Min; Allakhverdiev, Suleyman I; Tomo, Tatsuya

    2015-08-01

    We prepared thylakoid membranes from Halomicronema hongdechloris cells grown under white fluorescent light or light from far-red (740 nm) light-emitting diodes, and observed their energy-transfer processes shortly after light excitation. Excitation-relaxation processes were examined by steady-state and time-resolved fluorescence spectroscopies. Two time-resolved fluorescence techniques were used: time-correlated single photon counting and fluorescence up-conversion methods. The thylakoids from the cells grown under white light contained chlorophyll (Chl) a of different energies, but were devoid of Chl f. At room temperature, the excitation energy was equilibrated among the Chl a pools with a time constant of 6.6 ps. Conversely, the thylakoids from the cells grown under far-red light possessed both Chl a and Chl f. Two energy-transfer pathways from Chl a to Chl f were identified with time constants of 1.3 and 5.0 ps, and the excitation energy was equilibrated between the Chl a and Chl f pools at room temperature. We also examined the energy-transfer pathways from phycobilisome to the two photosystems under white-light cultivation. PMID:25648637

  11. Powerful fermentative hydrogen evolution of photosynthate in the cyanobacterium Lyngbya aestuarii BL J mediated by a bidirectional hydrogenase

    PubMed Central

    Kothari, Ankita; Parameswaran, Prathap; Garcia-Pichel, Ferran

    2014-01-01

    Cyanobacteria are considered good models for biohydrogen production because they are relatively simple organisms with a demonstrable ability to generate H2 under certain physiological conditions. However, most produce only little H2, revert readily to H2 consumption, and suffer from hydrogenase sensitivity to O2. Strains of the cyanobacteria Lyngbya aestuarii and Microcoleus chthonoplastes obtained from marine intertidal cyanobacterial mats were recently found to display much better H2 production potential. Because of their ecological origin in environments that become quickly anoxic in the dark, we hypothesized that this differential ability may have evolved to serve a role in the fermentation of the photosynthate. Here we show that, when forced to ferment internal substrate, these cyanobacteria display desirable characteristics of physiological H2 production. Among them, the strain L. aestuarii BL J had the fastest specific rates and attained the highest H2 concentrations during fermentation of photosynthate, which proceeded via a mixed acid fermentation pathway to yield acetate, ethanol, lactate, H2, CO2, and pyruvate. Contrary to expectations, the H2 yield per mole of glucose was only average compared to that of other cyanobacteria. Thermodynamic analyses point to the use of electron donors more electronegative than NAD(P)H in Lyngbya hydrogenases as the basis for its strong H2 production ability. In any event, the high specific rates and H2 concentrations coupled with the lack of reversibility of the enzyme, at the expense of internal, photosynthetically generated reductants, makes L. aestuarii BL J and/or its enzymes, a potentially feasible platform for large-scale H2 production. PMID:25540642

  12. Divisome-dependent subcellular localization of cell-cell joining protein SepJ in the filamentous cyanobacterium Anabaena.

    PubMed

    Ramos-León, Félix; Mariscal, Vicente; Frías, José E; Flores, Enrique; Herrero, Antonia

    2015-05-01

    Heterocyst-forming cyanobacteria are multicellular organisms that grow as filaments that can be hundreds of cells long. Septal junction complexes, of which SepJ is a possible component, appear to join the cells in the filament. SepJ is a cytoplasmic membrane protein that contains a long predicted periplasmic section and localizes not only to the cell poles in the intercellular septa but also to a position similar to a Z ring when cell division starts suggesting a relation with the divisome. Here, we created a mutant of Anabaena sp. strain PCC 7120 in which the essential divisome gene ftsZ is expressed from a synthetic NtcA-dependent promoter, whose activity depends on the nitrogen source. In the presence of ammonium, low levels of FtsZ were produced, and the subcellular localization of SepJ, which was investigated by immunofluorescence, was impaired. Possible interactions of SepJ with itself and with divisome proteins FtsZ, FtsQ and FtsW were investigated using the bacterial two-hybrid system. We found SepJ self-interaction and a specific interaction with FtsQ, confirmed by co-purification and involving parts of the SepJ and FtsQ periplasmic sections. Therefore, SepJ can form multimers, and in Anabaena, the divisome has a role beyond cell division, localizing a septal protein essential for multicellularity. PMID:25644579

  13. Catabolic Function of Compartmentalized Alanine Dehydrogenase in the Heterocyst-Forming Cyanobacterium Anabaena sp. Strain PCC 7120?

    PubMed Central

    Pernil, Rafael; Herrero, Antonia; Flores, Enrique

    2010-01-01

    In the diazotrophic filaments of heterocyst-forming cyanobacteria, an exchange of metabolites takes place between vegetative cells and heterocysts that results in a net transfer of reduced carbon to the heterocysts and of fixed nitrogen to the vegetative cells. Open reading frame alr2355 of the genome of Anabaena sp. strain PCC 7120 is the ald gene encoding alanine dehydrogenase. A strain carrying a green fluorescent protein (GFP) fusion to the N terminus of Ald (Ald-N-GFP) showed that the ald gene is expressed in differentiating and mature heterocysts. Inactivation of ald resulted in a lack of alanine dehydrogenase activity, a substantially decreased nitrogenase activity, and a 50% reduction in the rate of diazotrophic growth. Whereas production of alanine was not affected in the ald mutant, in vivo labeling with [14C]alanine (in whole filaments and isolated heterocysts) or [14C]pyruvate (in whole filaments) showed that alanine catabolism was hampered. Thus, alanine catabolism in the heterocysts is needed for normal diazotrophic growth. Our results extend the significance of a previous work that suggested that alanine is transported from vegetative cells into heterocysts in the diazotrophic Anabaena filament. PMID:20675483

  14. Factors affecting the photoproduction of ammonia from dinitrogen and water by the cyanobacterium Anabaena sp. strain ATCC 33047

    SciTech Connect

    Ramos, J.L.; Guerrero, M.G.; Losada, M.

    1987-04-01

    Synthesis of ammonia from dinitrogen and water by suspensions of Anabaena sp. strain ATCC 33047 treated with the glutamine synthetase inhibitor L-methionine-D,L-sulfoximine is strictly dependent on light. Under otherwise optimal conditions, the yield of ammonia production is influenced by irradiance, as well as by the density, depth, and turbulence of the cell suspension. The interaction among these factors seems to determine the actual amount of light available to each single cell or filament in the suspension for the photoproduction process. Under convenient illumination, the limiting factor in the synthesis of ammonia seems to be the cellular nitrogenase activity level, but under limiting light conditions the limiting factor could, however, be the assimilatory power required for nitrogen fixation. Photosynthetic ammonia production from atmospheric nitrogen and water can operate with an efficiency of ca. 10% of its theoretical maximum, representing a remarkable process for the conversion of light energy into chemical energy.

  15. A DNA fragment from the cyanobacterium Synechocystis sp. PCC 6803 mediates gene expression inducible by osmotic stress in E. coli.

    PubMed

    Milkowski, C; Quinones, A; Hagemann, M

    1998-08-01

    Fragments of Synechocystis-DNA driving salt-induced gene expression in E. coli were isolated with translational fusions to a 'lacZ gene. One fragment (fragment 19) showed a NaCl-dependent activation of betaGal expression with the maximum of a ninefold increase in enzyme activity. A similar induction was triggered by the nonionic osmolyte sucrose, indicating an osmotically dependent activation. On the contrary, transcriptional activity of the DNA fragment 19 was only slightly enhanced under salt stress conditions, suggesting a posttranscriptional mechanism of induction. Primer extension assay was performed to identify the transcription initiation site. Upstream regions share weak homology to the "-10" hexamer consensus of E. coli sigma70 promoters. The most thermodynamically stable secondary structure for the nontranslated part of the mRNA indicated that potential translation initiation sites might be blocked, leading to a low basal translation, whereas osmotic stress-induced changes of mRNA structure could be involved to increase translation. In order to analyze the function of fragment 19 in Synechocystis, promoter-probe plasmids were constructed allowing the stable integration of transcriptional and translational reporter gene fusions into the cyanobacterial chromosome. Quantitative assessment of reporter gene expression revealed a weak constitutive promoter activity of fragment 19 in Synechocystis. Sequence analysis showed that fragment 19 comprises 223 bp of the ORF sll0747 of the Synechocystis genome. PMID:9662610

  16. The cyanobacterium Synechococcus sp. strain PCC 7942 contains a second alkaline phosphatase encoded by phoV.

    PubMed

    Wagner, K U; Masepohl, B; Pistorius, E K

    1995-12-01

    A gene (phoV) encoding an alkaline phosphatase from Synechococcus sp. strain PCC 7942 was isolated by screening a plasmid gene bank for expression of alkaline phosphatase activity in Escherichia coli JM103. Two independent clones carrying the same alkaline-phosphatase-encoding gene were isolated. One of these clones (pKW1) was further analysed and the nucleotide sequence of a contiguous 3234 bp DNA fragment was determined. Two complete open reading frames (ORF1 and phoV) and an incomplete ORF3 were identified reading in the same direction. The deduced phoV gene product showed 34% identity to the alkaline phosphatase PhoA from Zymomonas mobilis, and the N-terminal part of the putative ORF3 protein exhibited 57% identity to a protein of unknown function from Frankia sp. Insertional inactivation of the Synechococcus PCC 7942 phoV gene failed, indicating an essential role for either the phoV or the ORF3 gene product. PhoV consists of 550 amino acid residues, resulting in a molecular mass of 61.3 kDa. To overexpress the Synechococcus PCC 7942 phoV gene in E. coli, plasmid pKW1 was transformed into a phoA mutant of E. coli (CC118). In E. coli strain CC118(pKW1) PhoV was expressed constitutively with high rates of activity, and was shown to be membrane associated in the periplasmic space. After partial purification of the recombinant PhoV, it was shown that, like other alkaline phosphatases, the Synechococcus PhoV had a broad pH optimum in the alkaline region and a broad substrate specificity for phosphomonoesters, required Zn2+ for activity, and was inhibited by phosphate. In contrast to several other alkaline phosphatases, PhoV was inhibited by Mn2+. Due to the lack of a Synechococcus PCC 7942 phoV mutant strain, the function of PhoV remains uncertain. However, the present results show that Synechococcus PCC 7942 has a second, probably phosphate-irrepressible, alkaline phosphatase (PhoV, 61.3 kDa) in addition to the phosphate-repressible enzyme (PhoA, 145 kDa) already described. PMID:8574398

  17. Management of a toxic cyanobacterium bloom (Planktothrix rubescens) affecting an Italian drinking water basin: a case study.

    PubMed

    Bogialli, Sara; Nigro di Gregorio, Federica; Lucentini, Luca; Ferretti, Emanuele; Ottaviani, Massimo; Ungaro, Nicola; Abis, Pier Paolo; Cannarozzi de Grazia, Matteo

    2013-01-01

    An extraordinary bloom of Planktothrix rubescens, which can produce microcystins (MCs), was observed in early 2009 in the Occhito basin, used even as a source of drinking water in Southern Italy. Several activities, coordinated by a task force, were implemented to assess and manage the risk associated to drinking water contaminated by cyanobacteria. Main actions were: evaluation of analytical protocols for screening and confirmatory purpose, monitoring the drinking water supply chain, training of operators, a dedicated web site for risk communication. ELISA assay was considered suitable for health authorities as screening method for MCs and to optimize frequency of sampling according to alert levels, and as internal control for the water supplier. A liquid chromatography-tandem mass spectrometric method able to quantify 9 MCs was optimized with the aim of supporting health authorities in a comprehensive risk evaluation based on the relative toxicity of different congeners. Short, medium, and long-term corrective actions were implemented to mitigate the health risk. Preoxidation with chlorine dioxide followed by flocculation and settling have been shown to be effective in removing MCs in the water treatment plant. Over two years, despite the high levels of cyanobacteria (up to 160 × 10(6) cells/L) and MCs (28.4 ?g/L) initially reached in surface waters, the drinking water distribution was never limited. PMID:23167492

  18. Expression profiling of the bloom-forming cyanobacterium Nodularia CCY9414 under light and oxidative stress conditions.

    PubMed

    Kopf, Matthias; Möke, Fred; Bauwe, Hermann; Hess, Wolfgang R; Hagemann, Martin

    2015-10-01

    Massive blooms of toxic cyanobacteria frequently occur in the central Baltic Sea during the summer. In the surface scum, cyanobacterial cells are exposed to high light (HL) intensity, high oxygen partial pressure and other stresses. To mimic these conditions, cultures of Nodularia spumigena CCY9414, which is a strain isolated from a cyanobacterial summer bloom in the Baltic Sea, were incubated at a HL intensity of 1200 ?mol photons m(-2) s(-1) or a combination of HL and increased oxygen partial pressure. Using differential RNA sequencing, we compared the global primary transcriptomes of control and stressed cells. The combination of oxidative and light stresses induced the expression of twofold more genes compared with HL stress alone. In addition to the induction of known stress-responsive genes, such as psbA, ocp and sodB, Nodularia cells activated the expression of genes coding for many previously unknown light- and oxidative stress-related proteins. In addition, the expression of non-protein-coding RNAs was found to be stimulated by these stresses. Among them was an antisense RNA to the phycocyanin-encoding mRNA cpcBAC and the trans-encoded regulator of photosystem I, PsrR1. The large genome capacity allowed Nodularia to harbor more copies of stress-relevant genes such as psbA and small chlorophyll-binding protein genes, combined with the coordinated induction of these and many additional genes for stress acclimation. Our data provide a first insight on how N. spumigena became adapted to conditions relevant for a cyanobacterial bloom in the Baltic Sea. PMID:25689027

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  20. Draft Genome Sequence of Alteromonas Macleodii Strain MIT1002, Isolated from an Enrichment Culture of the Marine Cyanobacterium Prochlorococcus

    E-print Network

    Coe, Allison

    Alteromonas spp. are heterotrophic gammaproteobacteria commonly found in marine environments. We present here the draft genome sequence of Alteromonas macleodii MIT1002, which was isolated from an enrichment culture of the ...

  1. Coupling of Cellular Processes and Their Coordinated Oscillations under Continuous Light in Cyanothece sp. ATCC 51142, a Diazotrophic Unicellular Cyanobacterium

    PubMed Central

    Vinh, Nguyen X.; Viswanathan, Ganesh A.; Chetty, Madhu; Wangikar, Pramod P.

    2015-01-01

    Unicellular diazotrophic cyanobacteria such as Cyanothece sp. ATCC 51142 (henceforth Cyanothece), temporally separate the oxygen sensitive nitrogen fixation from oxygen evolving photosynthesis not only under diurnal cycles (LD) but also in continuous light (LL). However, recent reports demonstrate that the oscillations in LL occur with a shorter cycle time of ~11 h. We find that indeed, majority of the genes oscillate in LL with this cycle time. Genes that are upregulated at a particular time of day under diurnal cycle also get upregulated at an equivalent metabolic phase under LL suggesting tight coupling of various cellular events with each other and with the cell’s metabolic status. A number of metabolic processes get upregulated in a coordinated fashion during the respiratory phase under LL including glycogen degradation, glycolysis, oxidative pentose phosphate pathway, and tricarboxylic acid cycle. These precede nitrogen fixation apparently to ensure sufficient energy and anoxic environment needed for the nitrogenase enzyme. Photosynthetic phase sees upregulation of photosystem II, carbonate transport, carbon concentrating mechanism, RuBisCO, glycogen synthesis and light harvesting antenna pigment biosynthesis. In Synechococcus elongates PCC 7942, a non-nitrogen fixing cyanobacteria, expression of a relatively smaller fraction of genes oscillates under LL condition with the major periodicity being 24 h. In contrast, the entire cellular machinery of Cyanothece orchestrates coordinated oscillation in anticipation of the ensuing metabolic phase in both LD and LL. These results may have important implications in understanding the timing of various cellular events and in engineering cyanobacteria for biofuel production. PMID:25973856

  2. Isolation and Biological Evaluation of 8-epi-Malyngamide C from the Floridian Marine Cyanobacterium Lyngbya majuscula†

    PubMed Central

    Kwan, Jason C.; Teplitski, Max; Gunasekera, Sarath P.; Paul, Valerie J.; Luesch, Hendrik

    2010-01-01

    A new stereoisomer of malyngamide C, 8-epi-malyngamide C (1), and the known compound lyngbic acid [(4E,7S)-7-methoxytetradec-4-enoic acid] were isolated from a sample of Lyngbya majuscula collected near Bush Key, Dry Tortugas, Florida. The structure of 1 was determined by NMR and MS experiments. The absolute configuration of 1 was determined by selective Mitsunobu inversion of C-8 to give malyngamide C, as determined by NMR, MS, and comparison of specific rotation. Both 1 and malyngamide C were found to be cytotoxic to HT29 colon cancer cells (IC50 15.4 ?M and 5.2 ?M, respectively) and to inhibit bacterial quorum sensing in a reporter gene assay. PMID:20166701

  3. Arsenate uptake, sequestration and reduction by a freshwater cyanobacterium: a potenial biologic control of arsenic in South Texas 

    E-print Network

    Markley, Christopher Thomas

    2005-08-29

    The toxicity and adverse health effects of arsenic are widely known. It is generally accepted that sorption/desorption reactions with oxy-hydroxide minerals (iron, manganese) control the fate and transport of inorganic arsenic in surface waters...

  4. A photoelectrochemical cell for detecting pollutant-induced effects on the activity of immobilized cyanobacterium Synechococcus sp.

    E-print Network

    Carpentier, Robert

    A photoelectrochemical cell for detecting pollutant-induced effects on the activity of immobilized solution containing 20 mM sodium phosphate, 0.15 mM NaCI, and 1 mM MgCI2. The best conditions of use are p could be inhibited by pollutants such as diuron and mercuric chloride. After entrapment the detection

  5. Effect of environmental factors on the synthesis of scytonemin, a UV-screening pigment, in a cyanobacterium (Chroococcidiopsis sp.).

    PubMed

    Dillon, Jesse G; Tatsumi, Cecelia M; Tandingan, Patrick G; Castenholz, Richard W

    2002-04-01

    Abstract. The UV-screening pigment scytonemin is found in many species of ensheathed cyanobacteria. Past work has shown that the pigment is synthesized in response to exposure to UV-A irradiance. This study investigated the effect of other correlated stress factors including heat, osmotic and oxidative stress on the synthesis of scytonemin in a clonal cyanobacterial isolate ( Chroococcidiopsis sp.) from an epilithic desert crust. Stress experiments were carried out both in conjunction with UV-A irradiance and in isolation. Increases in both temperature and photooxidative conditions in conjunction with UV-A caused a synergistic increase in the rate of scytonemin production. In contrast, increased salt concentration under UV-A irradiance inhibited scytonemin synthesis. However, unlike the responses to temperature and oxidative stress, cells synthesized low levels of scytonemin under osmotic stress in the absence of scytonemin-inducing irradiance. These results suggest that scytonemin induction may be regulated as a part of a complex stress response pathway in which multiple environmental signals affect its synthesis. PMID:11889486

  6. Potential Use of Rice Field Cyanobacterium Nostoc muscorum in the Evaluation of Butachlor Induced Toxicity and their Degradation.

    PubMed

    Anees, Sumaiya; Suhail, Shazia; Pathak, Neelam; Zeeshan, Mohd

    2014-01-01

    In the present study, butachlor (5, 10, 20, 40 and 80 ppm) induced toxicity in Nostoc muscorum and their degradation was evaluated. The dose of butachlor dependent decreased in the cell survival and growth of N. muscorum was noticed. Scanning electron microscopy revealed the adverse impact on the cell size and shapes. Low concentrations of butachlor (10 and 20 ppm) induced the over expression of a polypeptides of 31.0 K Da and 42.7 K Da, respectively which could be responsible for developing resistance in the organism up to certain level. Further, the degradation product of butachlor as a result of metabolic activities of N. muscorum, identified by GC-MS analysis includes phenols and benzene dicarboxylic acid indicating the utilization of herbicide during active growth. PMID:25097380

  7. Potential Use of Rice Field Cyanobacterium Nostoc muscorum in the Evaluation of Butachlor Induced Toxicity and their Degradation

    PubMed Central

    Anees, Sumaiya; Suhail, Shazia; Pathak, Neelam; Zeeshan, Mohd

    2014-01-01

    In the present study, butachlor (5, 10, 20, 40 and 80 ppm) induced toxicity in Nostoc muscorum and their degradation was evaluated. The dose of butachlor dependent decreased in the cell survival and growth of N. muscorum was noticed. Scanning electron microscopy revealed the adverse impact on the cell size and shapes. Low concentrations of butachlor (10 and 20 ppm) induced the over expression of a polypeptides of 31.0 K Da and 42.7 K Da, respectively which could be responsible for developing resistance in the organism up to certain level. Further, the degradation product of butachlor as a result of metabolic activities of N. muscorum, identified by GC-MS analysis includes phenols and benzene dicarboxylic acid indicating the utilization of herbicide during active growth. PMID:25097380

  8. A Method for DNA Extraction from the Desert Cyanobacterium Chroococcidiopsis and Its Application to Identification of ftsZ

    PubMed Central

    Billi, Daniela; Grilli Caiola, Maria; Paolozzi, Luciano; Ghelardini, Patrizia

    1998-01-01

    A method was developed for extraction of DNA from Chroococcidiopsis that overcomes obstacles posed by bacterial contamination and the presence of a thick envelope surrounding the cyanobacterial cells. The method is based on the resistance of Chroococcidiopsis to lysozyme and consists of a lysozyme treatment followed by osmotic shock that reduces the bacterial contamination by 3 orders of magnitude. Then DNase treatment is performed to eliminate DNA from the bacterial lysate. Lysis of Chroococcidiopsis cells is achieved by grinding with glass beads in the presence of hot phenol. Extracted DNA is further purified by cesium-chloride density gradient ultracentrifugation. This method permitted the first molecular approach to the study of Chroococcidiopsis, and a 570-bp fragment of the gene ftsZ was cloned and sequenced. PMID:9758840

  9. Genome-derived insights into the biology of the hepatotoxic bloom-forming cyanobacterium Anabaena sp. strain 90

    PubMed Central

    2012-01-01

    Background Cyanobacteria can form massive toxic blooms in fresh and brackish bodies of water and are frequently responsible for the poisoning of animals and pose a health risk for humans. Anabaena is a genus of filamentous diazotrophic cyanobacteria commonly implicated as a toxin producer in blooms in aquatic ecosystems throughout the world. The biology of bloom-forming cyanobacteria is poorly understood at the genome level. Results Here, we report the complete sequence and comprehensive annotation of the bloom-forming Anabaena sp. strain 90 genome. It comprises two circular chromosomes and three plasmids with a total size of 5.3 Mb, encoding a total of 4,738 genes. The genome is replete with mobile genetic elements. Detailed manual annotation demonstrated that almost 5% of the gene repertoire consists of pseudogenes. A further 5% of the genome is dedicated to the synthesis of small peptides that are the products of both ribosomal and nonribosomal biosynthetic pathways. Inactivation of the hassallidin (an antifungal cyclic peptide) biosynthetic gene cluster through a deletion event and a natural mutation of the buoyancy-permitting gvpG gas vesicle gene were documented. The genome contains a large number of genes encoding restriction-modification systems. Two novel excision elements were found in the nifH gene that is required for nitrogen fixation. Conclusions Genome analysis demonstrated that this strain invests heavily in the production of bioactive compounds and restriction-modification systems. This well-annotated genome provides a platform for future studies on the ecology and biology of these important bloom-forming cyanobacteria. PMID:23148582

  10. Myxoxanthophyll Is Required for Normal Cell Wall Structure and Thylakoid Organization in the Cyanobacterium Synechocystis sp. Strain PCC 6803

    PubMed Central

    Mohamed, Hatem E.; van de Meene, Allison M. L.; Roberson, Robert W.; Vermaas, Wim F. J.

    2005-01-01

    Myxoxanthophyll is a carotenoid glycoside in cyanobacteria that is of unknown biological significance. The sugar moiety of myxoxanthophyll in Synechocystis sp. strain PCC 6803 was identified as dimethyl fucose. The open reading frame sll1213 encoding a fucose synthetase orthologue was deleted to probe the role of fucose and to determine the biological significance of myxoxanthophyll in Synechocystis sp. strain PCC 6803. Upon deletion of sll1213, a pleiotropic phenotype was obtained: when propagated at 0.5 ?mol photons m?2 s?1, photomixotrophic growth of cells lacking sll1213 was poor. When grown at 40 ?mol photons m?2 s?1, growth was comparable to that of the wild type, but cells showed a severe reduction in or loss of the glycocalyx (S-layer). As a consequence, cells aggregated in liquid as well as on plates. At both light intensities, new carotenoid glycosides accumulated, but myxoxanthophyll was absent. New carotenoid glycosides may be a consequence of less-specific glycosylation reactions that gained prominence upon the disappearance of the native sugar moiety (fucose) of myxoxanthophyll. In the mutant, the N-storage compound cyanophycin accumulated, and the organization of thylakoid membranes was altered. Altered cell wall structure and thylakoid membrane organization and increased cyanophycin accumulation were also observed for ?slr0940K, a strain lacking ?-carotene desaturase and thereby all carotenoids but retaining fucose. Therefore, lack of myxoxanthophyll and not simply of fucose results in most of the phenotypic effects described here. It is concluded that myxoxanthophyll contributes significantly to the vigor of cyanobacteria, as it stabilizes thylakoid membranes and is critical for S-layer formation. PMID:16199557

  11. Article published in Nucleic Acids Research 2001, Vol. 29, No. 7 DNA methyltransferases of the cyanobacterium Anabaena PCC 7120

    E-print Network

    Elhai, Jeff

    restriction enzymes (AvaI, AvaII, AvaIII, and the newly recognized inactive AvaIV), and five are not restriction. These enzymes, sometimes called orphans, will be termed solitary MTases to emphasize restriction enzyme (8), led us to speculate that these cyanobacteria carry at least two solitary MTases. Type

  12. Carbon-13 NMR studies of salt shock-induced carbohydrate turnover in the marine cyanobacterium Agmenellum quadruplicatum

    NASA Technical Reports Server (NTRS)

    Tel-Or, E.; Spath, S.; Packer, L.; Mehlhorn, R. J.

    1986-01-01

    Carbon turnover in response to abrupt changes in salinity, including the mobilization of glycogen for use in osmoregulation was studied with pulse-chase strategies utilizing nuclear magnetic resonance (NMR)-silent and NMR-detectable 12C and 13C isotopes, respectively. Growth of Agmenellum quadruplicatum in 30%-enriched 13C bicarbonate provided sufficient NMR-detectability of intracellular organic osmoregulants for these studies. A comparison of NMR spectra of intact cells and their ethanol extracts showed that the intact cell data were suitable for quantitative work, and, when combined with ESR measurements of cell volumes, yielded intracellular glucosylglycerol concentrations without disrupting the cells. NMR pulse-chase experiments were used to show that 13C-enriched glycogen, which had previously been accumulated by the cells under nitrogen-limited growth at low salinities, could be utilized for the synthesis of glucosylglycerol when the cells were abruptly transferred to hypersaline media, but only in the light. It was also shown that the accumulation of glucosylglycerol in the light occurred on a time scale similar to that of cell doubling. Depletion of glucosylglycerol when cells abruptly transferred to lower salinities appeared to be rapid--the intracellular pool of this osmoregulant was decreased 2-fold within 2 hours of hypotonic shock.

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed

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

    2015-12-01

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

  15. Photo- and heterotrophic nitrogenase activity by the cyano-bacterium Nostoc in symbiosis with the bryophyte Anthoceros

    SciTech Connect

    Steinberg, N.A.; Meeks, J.C.

    1987-04-01

    In symbiosis with Anthoceros, Nostoc is thought to do little or no photosynthesis. However, light-dependent /sup 14/CO/sub 2/ fixation by symbiotic Nostoc, freshly isolated from pure cultures of the reconstituted Anthoceros-Nostoc association, was 16% of that by free-living Nostoc. A DCMU-resistant mutant of Nostoc was isolated that fixed CO/sub 2/ at rates comparable to wild-type in both symbiotic and free-living growth states. To determine if symbiotic Nostoc can use its photosynthate directly to fix nitrogen, acetylene reduction by Anthoceros associations reconstituted with wild-type Nostoc was compared to associations with the DCMU-resistant mutant. In wild-type Anthoceros-Nostoc acetylene reduction was inhibited 97% by 5 ..mu..M DCMU, while inhibition of the DCMU-resistant Nostoc association was only 63%. Additions of glucose, fructose, maltose or sucrose to wild-type associations completely restored DCMU-inhibited acetylene reduction in the light. Acetylene reduction in the dark was stimulated by glucose, attaining 84% of the uninhibited light-dependent value. The authors conclude that symbiotic Nostoc maintains a pool of photosynthate which supports nitrogenase activity. The pool can also be supplemented from plant sources.

  16. Enhancing the light-driven production of d-lactate by engineering cyanobacterium using a combinational strategy

    PubMed Central

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

    2015-01-01

    It is increasingly attractive to engineer cyanobacteria for bulk production of chemicals from CO2. However, cofactor bias of cyanobacteria is different from bacteria that prefer NADH, which hampers cyanobacterial strain engineering. In this study, the key enzyme d-lactate dehydrogenase (LdhD) from Lactobacillus bulgaricus ATCC11842 was engineered to reverse its favored cofactor from NADH to NADPH. Then, the engineered enzyme was introduced into Synechococcus elongatus PCC7942 to construct an efficient light-driven system that produces d-lactic acid from CO2. Mutation of LdhD drove a fundamental shift in cofactor preference towards NADPH, and increased d-lactate productivity by over 3.6-fold. We further demonstrated that introduction of a lactic acid transporter and bubbling CO2-enriched air also enhanced d-lactate productivity. Using this combinational strategy, increased d-lactate concentration and productivity were achieved. The present strategy may also be used to engineer cyanobacteria for producing other useful chemicals. PMID:25940225

  17. Biofilm and planktonic lifestyles differently support the resistance of the desert cyanobacterium Chroococcidiopsis under space and Martian simulations.

    PubMed

    Baqué, Mickael; Scalzi, Giuliano; Rabbow, Elke; Rettberg, Petra; Billi, Daniela

    2013-10-01

    When Chroococcidiopsis sp. strain CCMEE 057 from the Sinai Desert and strain CCMEE 029 from the Negev Desert were exposed to space and Martian simulations in the dried status as biofilms or multilayered planktonic samples, the biofilms exhibited an enhanced rate of survival. Compared to strain CCMEE 029, biofilms of strain CCME 057 better tolerated UV polychromatic radiation (5 × 10(5) kJ/m(2) attenuated with a 0.1% neutral density filter) combined with space vacuum or Martian atmosphere of 780 Pa. CCMEE 029, on the other hand, failed to survive UV polychromatic doses higher than 1.5 × 10(3) kJ/m(2). The induced damage to genomic DNA, plasma membranes and photosynthetic apparatus was quantified and visualized by means of PCR-based assays and CLSM imaging. Planktonic samples of both strains accumulated a higher amount of damage than did the biofilms after exposure to each simulation; CLSM imaging showed that photosynthetic pigment bleaching, DNA fragmentation and damaged plasma membranes occurred in the top 3-4 cell layers of both biofilms and of multilayered planktonic samples. Differences in the EPS composition were revealed by molecular probe staining as contributing to the enhanced endurance of biofilms compared to that of planktonic samples. Our results suggest that compared to strain CCMEE 029, biofilms of strain CCMEE 057 might better tolerate 1 year's exposure in space during the next EXPOSE-R2 mission. PMID:23955666

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

    SciTech Connect

    Overbeek, R.

    2003-06-30

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

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

    PubMed Central

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

    1994-01-01

    Growth of Synechococcus sp. strain PCC 7942 in iron-deficient media leads to the accumulation of an approximately 34-kDa protein. The gene encoding this protein, mapA (membrane-associated protein A), has been cloned and sequenced (GenBank accession number, L01621). The mapA transcript is not detectable in normally grown cultures but is stably accumulated by cells grown in iron-deficient media. However, the promoter sequence for this gene does not resemble other bacterial iron-regulated promoters described to date. The carboxyl-terminal region of the derived amino acid sequence of MapA resembles bacterial proteins involved in iron acquisition, whereas the amino-terminal end of MapA has a high degree of amino acid identity with the abundant, chloroplast envelope protein E37. An approach employing improved cellular fractionation techniques as well as electron microscopy and immunocytochemistry was essential in localizing MapA protein to the cytoplasmic membrane of Synechococcus sp. strain PCC 7942. When these cells were grown under iron-deficient conditions, a significant fraction of MapA could also be localized to the thylakoid membranes. Images PMID:8051004

  20. Factors Affecting Carbohydrate Production and the Formation of Transparent Exopolymer Particles (TEP) by Diatoms 

    E-print Network

    Chen, Jie

    2014-03-25

    cyanobacterium (Synechococcus elongates). For some diatoms (Thalassiosira weissflogii and Skeletonema marinoi) and the cyanobacterium Synechococcus elongatus, TEP formation was associated with permeable cells. Greater TEP production was observed in cultures...

  1. Synthesis of Water-soluble 9,10-Anthraquinone Analogues with Potent Cyanobactericidal Activity Toward the Musty-Odor Cyanobacterium Oscillatoria perornata

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A series of water-soluble 9,10-anthraquinone analogs were prepared and evaluated for their selective toxicity towards Oscillatoria perornata which grows in catfish production ponds and causes “musty” off-flavor in channel catfish Ictalurus punctatus. Water-soluble mono- and dicationic salts were pre...

  2. Transcriptomic and proteomic dynamics in the metabolism of a diazotrophic cyanobacterium, Cyanothece sp. PCC 7822 during a diurnal light–dark cycle

    DOE PAGESBeta

    Welkie, David; Zhang, Xiaohui; Markillie, Meng; Taylor, Ronald; Orr, Galya; Jacobs, Jon; Bhide, Ketaki; Thimmapuram, Jyothi; Gritsenko, Marina; Mitchell, Hugh; et al

    2014-12-29

    Cyanothece sp. PCC 7822 is an excellent cyanobacterial model organism with great potential to be applied as a biocatalyst for the production of high value compounds. Like other unicellular diazotrophic cyanobacterial species, it has a tightly regulated metabolism synchronized to the light-dark cycle. Utilizing transcriptomic and proteomic methods, we were able to quantify the relationships between transcription and translation underlying central and secondary metabolism in response to nitrogen free, 12 hour light and 12 hour dark conditions.

  3. High cell-specific rates of nitrogen and carbon fixation by the cyanobacterium Aphanizomenon sp. at low temperatures in the Baltic Sea.

    PubMed

    Svedén, Jennie B; Adam, Birgit; Walve, Jakob; Nahar, Nurun; Musat, Niculina; Lavik, Gaute; Whitehouse, Martin J; Kuypers, Marcel M M; Ploug, Helle

    2015-12-01

    Aphanizomenon is a widespread genus of nitrogen (N2)-fixing cyanobacteria in lakes and estuaries, accounting for a large fraction of the summer N2-fixation in the Baltic Sea. However, information about its cell-specific carbon (C)- and N2-fixation rates in the early growth season has not previously been reported. We combined various methods to study N2-fixation, photosynthesis and respiration in field-sampled Baltic Sea Aphanizomenon sp. during early summer at 10°C. Stable isotope incubations at in situ light intensities during 24 h combined with cell-specific secondary ion mass spectrometry showed an average net N2-fixation rate of 55 fmol N cell(-1) day(-1). Dark net N2-fixation rates over a course of 12 h were 20% of those measured in light. C-fixation, but not N2-fixation, was inhibited by high ambient light intensities during daytime. Consequently, the C:N fixation ratio varied substantially over the diel cycle. C- and N2-fixation rates were comparable to those reported for Aphanizomenon sp. in August at 19°C, using the same methods. High respiration rates (23% of gross photosynthesis) were measured with (14)C-incubations and O2-microsensors, and presumably reflect the energy needed for high N2-fixation rates. Hence, Aphanizomenon sp. is an important contributor to N2-fixation at low in situ temperatures in the early growth season. PMID:26511856

  4. Influence of a non-copper algicide on the cyanobacterium, Nostoc spongiaeforme, and the green alga, Hydrodictyon reticulatum, in field and laboratory experiments

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cyanobacteria grow in California rice fields where they form large mats that may smoother seedlings or cause them to dislodge, resulting in yield loss. The most troublesome species is Nostoc spongiaeforme. It is very difficult to control using currently accepted methods, i.e., aerial applications of...

  5. Identification of pathways, gene networks and paralogous gene families in Daphnia pulex responding to exposure to the toxic cyanobacterium Microcystis aeruginosa

    PubMed Central

    Asselman, Jana; De Coninck, Dieter IM; Glaholt, Stephen; Colbourne, John K; Janssen, Colin R; Shaw, Joseph R; De Schamphelaere, Karel AC

    2013-01-01

    Although cyanobacteria produce a wide range of natural toxins that impact aquatic organisms, food webs and water quality, the mechanisms of toxicity are still insufficiently understood. Here, we implemented a whole-genome expression microarray to identify pathways, gene networks and paralogous gene families responsive to Microcystis stress in Daphnia pulex. Therefore, neonates of a sensitive isolate were given a diet contaminated with Microcystis to contrast with those given a control diet for sixteen days. The microarray revealed 2247 differentially expressed (DE) genes (7.6% of the array) in response to Microcystis, of which 17% are lineage specific( i.e., these genes have no detectable homology to any other gene in currently available databases) and 49% are gene duplicates (paralogs). We identified four pathways/gene networks and eight paralogous gene families affected by Microcystis. Differential regulation of the ribosome, including 3 paralogous gene families encoding 40S, 60S and mitochondrial ribosomal proteins, suggests an impact of Microcystis on protein synthesis of D. pulex. In addition, differential regulation of the oxidative phosphorylation pathway (including the NADH ubquinone oxidoreductase gene family) and the trypsin paralogous gene family (a major component of the digestive system in D. pulex) could explain why fitness is reduced based on energy budget considerations. PMID:22799445

  6. Evidence for an Ionic Intermediate in the Transformation of Fatty Acid Hydroperoxide by a Catalase-related Allene Oxide Synthase from the Cyanobacterium Acaryochloris marina*

    PubMed Central

    Gao, Benlian; Boeglin, William E.; Zheng, Yuxiang; Schneider, Claus; Brash, Alan R.

    2009-01-01

    Allene oxides are reactive epoxides biosynthesized from fatty acid hydroperoxides by specialized cytochrome P450s or by catalase-related hemoproteins. Here we cloned, expressed, and characterized a gene encoding a lipoxygenase-catalase/peroxidase fusion protein from Acaryochloris marina. We identified novel allene oxide synthase (AOS) activity and a by-product that provides evidence of the reaction mechanism. The fatty acids 18.4?3 and 18.3?3 are oxygenated to the 12R-hydroperoxide by the lipoxygenase domain and converted to the corresponding 12R,13-epoxy allene oxide by the catalase-related domain. Linoleic acid is oxygenated to its 9R-hydroperoxide and then, surprisingly, converted ?70% to an epoxyalcohol identified spectroscopically and by chemical synthesis as 9R,10S-epoxy-13S-hydroxyoctadeca-11E-enoic acid and only ?30% to the 9R,10-epoxy allene oxide. Experiments using oxygen-18-labeled 9R-hydroperoxide substrate and enzyme incubations conducted in H218O indicated that ?72% of the oxygen in the epoxyalcohol 13S-hydroxyl arises from water, a finding that points to an ionic intermediate (epoxy allylic carbocation) during catalysis. AOS and epoxyalcohol synthase activities are mechanistically related, with a reacting intermediate undergoing a net hydrogen abstraction or hydroxylation, respectively. The existence of epoxy allylic carbocations in fatty acid transformations is widely implicated although for AOS reactions, without direct experimental support. Our findings place together in strong association the reactions of allene oxide synthesis and an ionic reaction intermediate in the AOS-catalyzed transformation. PMID:19531485

  7. Crystallization and preliminary X-ray diffraction analyses of the homodimeric glycine decarboxylase (P-protein) from the cyanobacterium Synechocystis sp. PCC 6803

    PubMed Central

    Hasse, Dirk; Hagemann, Martin; Andersson, Inger; Bauwe, Hermann

    2010-01-01

    Glycine decarboxylase, or P-protein, is a major enzyme that is involved in the C1 metabolism of all organisms and in the photorespiratory pathway of plants and cyanobacteria. The protein from Synechocystis sp. PCC 6803 is a homodimer with a mass of 215?kDa. Recombinant glycine decarboxylase was expressed in Escherichia coli and purified by metal-affinity, ion-exchange and gel-filtration chromatography. Crystals of P-protein that diffracted to a resolution of 2.1?Å were obtained using the hanging-drop vapour-diffusion method at 291?K. X-ray diffraction data were collected from cryocooled crystals using synchrotron radiation. The crystals belonged to space group P212121, with unit-cell parameters a = 96.30, b = 135.81, c = 179.08?Å. PMID:20124719

  8. A Major Facilitator Superfamily Protein, HepP, Is Involved in Formation of the Heterocyst Envelope Polysaccharide in the Cyanobacterium Anabaena sp. Strain PCC 7120

    PubMed Central

    López-Igual, Rocío; Lechno-Yossef, Sigal; Fan, Qing; Herrero, Antonia; Wolk, C. Peter

    2012-01-01

    Some filamentous cyanobacteria such as Anabaena sp. strain PCC 7120 produce cells, termed heterocysts, specialized in nitrogen fixation. Heterocysts bear a thick envelope containing an inner layer of glycolipids and an outer layer of polysaccharide that restrict the diffusion of air (including O2) into the heterocyst. Anabaena sp. mutants impaired in production of either of those layers show a Fox? phenotype (requiring fixed nitrogen for growth under oxic conditions). We have characterized a set of transposon-induced Fox? mutants in which transposon Tn5-1063 was inserted into the Anabaena sp. chromosome open reading frame all1711 which encodes a predicted membrane protein that belongs to the major facilitator superfamily (MFS). These mutants showed higher nitrogenase activities under anoxic than under oxic conditions and altered sucrose uptake. Electron microscopy and alcian blue staining showed a lack of the heterocyst envelope polysaccharide (Hep) layer. Northern blot and primer extension analyses showed that, in a manner dependent on the nitrogen-control transcription factor NtcA, all1711 was strongly induced after nitrogen step-down. Confocal microscopy of an Anabaena sp. strain producing an All1711-green fluorescent protein (All1711-GFP) fusion protein showed induction in all cells of the filament but at higher levels in differentiating heterocysts. All1711-GFP was located in the periphery of the cells, consistent with All1711 being a cytoplasmic membrane protein. Expression of all1711 from the PglnA promoter in a multicopy plasmid led to production of a presumptive exopolysaccharide by vegetative cells. These results suggest that All1711, which we denote HepP, is involved in transport of glycoside(s), with a specific physiological role in production of Hep. PMID:22753066

  9. The CopRS Two-Component System Is Responsible for Resistance to Copper in the Cyanobacterium Synechocystis sp. PCC 68031[C][W][OA

    PubMed Central

    Giner-Lamia, Joaquín; López-Maury, Luis; Reyes, José C.; Florencio, Francisco J.

    2012-01-01

    Photosynthetic organisms need copper for cytochrome oxidase and for plastocyanin in the fundamental processes of respiration and photosynthesis. However, excess of free copper is detrimental inside the cells and therefore organisms have developed homeostatic mechanisms to tightly regulate its acquisition, sequestration, and efflux. Herein we show that the CopRS two-component system (also known as Hik31-Rre34) is essential for copper resistance in Synechocystis sp. PCC 6803. It regulates expression of a putative heavy-metal efflux-resistance nodulation and division type copper efflux system (encoded by copBAC) as well as its own expression (in the copMRS operon) in response to the presence of copper in the media. Mutants in this two-component system or the efflux system render cells more sensitive to the presence of copper in the media and accumulate more intracellular copper than the wild type. Furthermore, CopS periplasmic domain is able to bind copper, suggesting that CopS could be able to detect copper directly. Both operons (copMRS and copBAC) are also induced by the photosynthetic inhibitor 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone but this induction requires the presence of copper in the media. The reduced response of two mutant strains to copper, one lacking plastocyanin and a second one impaired in copper transport to the thylakoid, due to the absence of the PI-type ATPases PacS and CtaA, suggests that CopS can detect intracellular copper. In addition, a tagged version of CopS with a triple HA epitope localizes to both the plasma and the thylakoid membranes, suggesting that CopS could be involved in copper detection in both the periplasm and the thylakoid lumen. PMID:22715108

  10. The combined effects of UV-C radiation and H2O2 on Microcystis aeruginosa, a bloom-forming cyanobacterium.

    PubMed

    Wang, Binliang; Wang, Xi; Hu, Yiwei; Chang, Mingxian; Bi, Yonghong; Hu, Zhengyu

    2015-12-01

    In order to get insight into the impacts of UVC/H2O2 on Microcystis aeruginosa, physiological and morphological changes as well as toxicity were detected under different UVC/H2O2 treatments. In the presence of sole UVC or H2O2, the net oxygen evolution rate decreased significantly (p<0.05) since activity of photosystem II (PSII) was inhibited. Meanwhile, increase of intracellular reactive oxygen species (ROS), degradation of microcystin (MC) and ultrastructure destructions were observed. Under sole UVC treatment, no changes happened in the activity of photosystem I (PSI), but the degradation of D1 protein was observed. Under sole H2O2 treatment, an increase of malondialdehyde, aggregation of D1 protein and deformation of the thylakoid membrane were observed. ROS content under H2O2 treatment was about 5 times than that under UVC treatment. Combined use of UVC and H2O2, as well as 20mJcm(-2) UVC and 60?M H2O2, showed high synergetic effects. Obvious damage to membrane systems, the marked degradation of MC and inhibition of the photosystems were observed. It could be deduced that UVC worked on intracellular membrane components directly and the damaged oxygen-evolving complex, which was followed by the D1 protein degradation. H2O2 oxidised the membrane lipids via an ROS-mediated process, with thylakoid injury and the aggregation of D1 protein being the lethal mechanisms, and both PSII and PSI being the attacking targets. With regard towards the effective inactivation of M. aeruginosa and high removal of MC, UVC/H2O2 proposed a novel practical method in controlling cyanobacterial blooms. PMID:26092198

  11. Establishment of the forward genetic analysis of the chlorophyll d-dominated cyanobacterium Acaryochloris marina MBIC 11017 by applying in vivo transposon mutagenesis system.

    PubMed

    Watabe, Kazuyuki; Mimuro, Mamoru; Tsuchiya, Tohru

    2015-08-01

    Acaryochloris marina MBIC 11017 possesses chlorophyll (Chl) d as a major Chl, which enables this organism to utilize far-red light for photosynthesis. Thus, the adaptation mechanism of far-red light utilization, including Chl d biosynthesis, has received much attention, though a limited number of reports on this subject have been published. To identify genes responsible for Chl d biosynthesis and adaptation to far-red light, molecular genetic analysis of A. marina was required. We developed a transformation system for A. marina and introduced expression vectors into A. marina. In this study, the high-frequency in vivo transposon mutagenesis system recently established by us was applied to A. marina. As a result, we obtained mutants with the transposon in their genomic DNA at various positions. By screening transposon-tagged mutants, we isolated a mutant (Y1 mutant) that formed a yellow colony on agar medium. In the Y1 mutant, the transposon was inserted into the gene encoding molybdenum cofactor biosynthesis protein A (MoaA). The Y1 mutant was functionally complemented by introducing the moaA gene or increasing the ammonium ion in the medium. These results indicate that the mutation of the moaA gene reduced nitrate reductase activity, which requires molybdenum cofactor, in the Y1 mutant. This is the first successful forward genetic analysis of A. marina, which will lead to the identification of genes responsible for adaptation to far-red light. PMID:25596846

  12. Thylakoid Terminal Oxidases Are Essential for the Cyanobacterium Synechocystis sp. PCC 6803 to Survive Rapidly Changing Light Intensities1[C][W][OA

    PubMed Central

    Lea-Smith, David J.; Ross, Nic; Zori, Maria; Bendall, Derek S.; Dennis, John S.; Scott, Stuart A.; Smith, Alison G.; Howe, Christopher J.

    2013-01-01

    Cyanobacteria perform photosynthesis and respiration in the thylakoid membrane, suggesting that the two processes are interlinked. However, the role of the respiratory electron transfer chain under natural environmental conditions has not been established. Through targeted gene disruption, mutants of Synechocystis sp. PCC 6803 were generated that lacked combinations of the three terminal oxidases: the thylakoid membrane-localized cytochrome c oxidase (COX) and quinol oxidase (Cyd) and the cytoplasmic membrane-localized alternative respiratory terminal oxidase. All strains demonstrated similar growth under continuous moderate or high light or 12-h moderate-light/dark square-wave cycles. However, under 12-h high-light/dark square-wave cycles, the COX/Cyd mutant displayed impaired growth and was completely photobleached after approximately 2 d. In contrast, use of sinusoidal light/dark cycles to simulate natural diurnal conditions resulted in little photobleaching, although growth was slower. Under high-light/dark square-wave cycles, the COX/Cyd mutant suffered a significant loss of photosynthetic efficiency during dark periods, a greater level of oxidative stress, and reduced glycogen degradation compared with the wild type. The mutant was susceptible to photoinhibition under pulsing but not constant light. These findings confirm a role for thylakoid-localized terminal oxidases in efficient dark respiration, reduction of oxidative stress, and accommodation of sudden light changes, demonstrating the strong selective pressure to maintain linked photosynthetic and respiratory electron chains within the thylakoid membrane. To our knowledge, this study is the first to report a phenotypic difference in growth between terminal oxidase mutants and wild-type cells and highlights the need to examine mutant phenotypes under a range of conditions. PMID:23463783

  13. The high-energy radiation protectant extracellular sheath pigment scytonemin and its reduced counterpart in the cyanobacterium Scytonema sp. R77DM.

    PubMed

    Rastogi, Rajesh P; Sonani, Ravi R; Madamwar, Datta

    2014-11-01

    A cyanobacterial extracellular sheath pigment from Scytonema sp. R77DM was partially characterized and investigated for its increased production under abiotic factors, and UV-screening function. HPLC with PDA detection, and ion trap liquid chromatography/mass spectrometry analysis revealed the presence of a pigment scytonemin and its reduced counterpart. Ultraviolet radiation showed more stimulative effects on scytonemin production. A significant synergistic enhancement of scytonemin synthesis was observed under combined stress of heat and UV radiation. Scytonemin also exhibited efficient UV-screening function by reducing the in vivo production of reactive oxygen species (ROS) and cyclobutane thymine dimer. UV-induced formation of ROS and thymine dimer was also reduced upon exposure of cyanobacterial cells to exogenous antioxidant, ascorbic acid; however, the effect was more significant when both scytonemin and ascorbic acid were applied in combination. Moreover, the results indicate the potential role of scytonemin pigment as natural photoprotectant against high energy solar insolation. PMID:25226055

  14. Exploration of using stripped ammonia and ash from poultry litter for the cultivation of the cyanobacterium Arthrospira platensis and the green microalga Chlorella vulgaris.

    PubMed

    Markou, Giorgos; Iconomou, Dimitris; Sotiroudis, Theodore; Israilides, Cleanthes; Muylaert, Koenraad

    2015-11-01

    Herein a new approach of exploiting poultry litter (PL) is demonstrated. The suggested method includes drying of PL with simultaneously striping and recovery of ammonia, followed by the direct combustion of dried PL. The generated ash after the combustion, and the striped ammonia consequently, could be used as nutrient source for the cultivation of microalgae or cyanobacteria to produce feed additives. The present study explored the application of PL ash and recovered ammonia for the cultivation of Arthrospira platensis and Chlorella vulgaris. For a simultaneously 90% dissolution of ash potassium and phosphorus, a ratio of acid to ash of 0.02mol-H(+)/g was required. The optimum mass of ash required was 0.07-0.08g/g dry biomass, while the addition of ammoniac nitrogen of 8-9mgN per g of dry biomass per day was adequate for a satisfactory production of A. platensis and C. vulgaris. PMID:26280098

  15. Heme oxygenase 2 of the cyanobacterium Synechocystis sp. PCC 6803 is induced under a microaerobic atmosphere and is required for microaerobic growth at high light intensity.

    PubMed

    Yilmaz, Mete; Kang, Ilgu; Beale, Samuel I

    2010-01-01

    Cyanobacteria, red algae, and cryptomonad algae utilize phycobilin chromophores that are attached to phycobiliproteins to harvest solar energy. Heme oxygenase (HO) in these organisms catalyzes the first step in phycobilin formation through the conversion of heme to biliverdin IXalpha, CO, and iron. The Synechocystis sp. PCC 6803 genome contains two open reading frames, ho1 (sll1184) and ho2 (sll1875), whose products have in vitro HO activity. We report that HO2, the protein encoded by ho2, was induced in the cells growing under a microaerobic atmosphere [0.2% (v/v) O(2)], whereas HO1 was constitutively expressed under both aerobic and microaerobic atmospheres. Light intensity did not have an effect on the expression of both the HOs. Cells, in which ho2 was disrupted, were unable to grow microaerobically at a light intensity of 40 micromol m(-2) s(-1), but did grow microaerobically at 10 micromol m(-2) s(-1) light intensity. These cells grew normally aerobically at both light intensities. Comparative analysis of complete cyanobacterial genomes revealed that possession of two HOs is common in cyanobacteria. In phylogenetic analysis of their amino acid sequences, cyanobacterial HO1 and HO2 homologs formed distinct clades. HO sequences of cyanobacteria that have only one isoform were most similar to HO1 sequences. We propose that HO2 might be the more ancient HO homolog that functioned under low O(2) tension, whereas the derived HO1 can better accommodate increased O(2) tension in the environment. PMID:19937118

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

    PubMed Central

    Lei, Haijin; Chen, Gu; Wang, Yuling; Ding, Qinglong; Wei, Dong

    2014-01-01

    Site-2-proteases (S2Ps) mediated proteolysis of transmembrane transcriptional regulators is a conserved mechanism to regulate transmembrane signaling. The universal presence of S2P homologs in different cyanobacterial genomes suggest conserved and fundamental functions, though limited data has been available. Here we provide the first evidence that Sll0528, a site-2-protease in Synechocystis sp. PCC 6803 is crucial for salt, cold and hyperosmotic stress acclimation. Remarkable induction of sll0528 gene expression was observed under salt, cold and hyperosmotic stress, much higher than induction of the other three S2Ps. Knock-out of sll0528 gene in wild type Synechocystis sp. PCC 6803 increased their sensitivity to salt, cold and hyperosmotic stress, as revealed by retarded growth, reduced pigments and disrupted photosystems. The sll0528 gene was induced to a much smaller extent by high light and mixotrophic growth with glucose. Similar growth responses of the sll0528 knockout mutant and wild type under high light and mixotrophic growth indicated that sll0528 was dispensable for these conditions. Recombinant Sll0528 protein could cleave beta-casein into smaller fragments. These results together suggest that the Sll0528 metalloprotease plays a role in the stress response and lays the foundation for further investigation of its mechanism, as well as providing hints for the functional analysis of other S2Ps in cyanobacteria. PMID:25493476

  17. Comparative analysis of kdp and ktr mutants reveals distinct roles of the potassium transporters in the model cyanobacterium Synechocystis sp. strain PCC 6803.

    PubMed

    Nanatani, Kei; Shijuku, Toshiaki; Takano, Yousuke; Zulkifli, Lalu; Yamazaki, Tomoko; Tominaga, Akira; Souma, Satoshi; Onai, Kiyoshi; Morishita, Megumi; Ishiura, Masahiro; Hagemann, Martin; Suzuki, Iwane; Maruyama, Hisataka; Arai, Fumihito; Uozumi, Nobuyuki

    2015-02-15

    Photoautotrophic bacteria have developed mechanisms to maintain K(+) homeostasis under conditions of changing ionic concentrations in the environment. Synechocystis sp. strain PCC 6803 contains genes encoding a well-characterized Ktr-type K(+) uptake transporter (Ktr) and a putative ATP-dependent transporter specific for K(+) (Kdp). The contributions of each of these K(+) transport systems to cellular K(+) homeostasis have not yet been defined conclusively. To verify the functionality of Kdp, kdp genes were expressed in Escherichia coli, where Kdp conferred K(+) uptake, albeit with lower rates than were conferred by Ktr. An on-chip microfluidic device enabled monitoring of the biphasic initial volume recovery of single Synechocystis cells after hyperosmotic shock. Here, Ktr functioned as the primary K(+) uptake system during the first recovery phase, whereas Kdp did not contribute significantly. The expression of the kdp operon in Synechocystis was induced by extracellular K(+) depletion. Correspondingly, Kdp-mediated K(+) uptake supported Synechocystis cell growth with trace amounts of external potassium. This induction of kdp expression depended on two adjacent genes, hik20 and rre19, encoding a putative two-component system. The circadian expression of kdp and ktr peaked at subjective dawn, which may support the acquisition of K(+) required for the regular diurnal photosynthetic metabolism. These results indicate that Kdp contributes to the maintenance of a basal intracellular K(+) concentration under conditions of limited K(+) in natural environments, whereas Ktr mediates fast potassium movements in the presence of greater K(+) availability. Through their distinct activities, both Ktr and Kdp coordinate the responses of Synechocystis to changes in K(+) levels under fluctuating environmental conditions. PMID:25313394

  18. Comparative Analysis of kdp and ktr Mutants Reveals Distinct Roles of the Potassium Transporters in the Model Cyanobacterium Synechocystis sp. Strain PCC 6803

    PubMed Central

    Nanatani, Kei; Shijuku, Toshiaki; Takano, Yousuke; Zulkifli, Lalu; Yamazaki, Tomoko; Tominaga, Akira; Souma, Satoshi; Onai, Kiyoshi; Morishita, Megumi; Ishiura, Masahiro; Hagemann, Martin; Suzuki, Iwane; Maruyama, Hisataka; Arai, Fumihito

    2014-01-01

    Photoautotrophic bacteria have developed mechanisms to maintain K+ homeostasis under conditions of changing ionic concentrations in the environment. Synechocystis sp. strain PCC 6803 contains genes encoding a well-characterized Ktr-type K+ uptake transporter (Ktr) and a putative ATP-dependent transporter specific for K+ (Kdp). The contributions of each of these K+ transport systems to cellular K+ homeostasis have not yet been defined conclusively. To verify the functionality of Kdp, kdp genes were expressed in Escherichia coli, where Kdp conferred K+ uptake, albeit with lower rates than were conferred by Ktr. An on-chip microfluidic device enabled monitoring of the biphasic initial volume recovery of single Synechocystis cells after hyperosmotic shock. Here, Ktr functioned as the primary K+ uptake system during the first recovery phase, whereas Kdp did not contribute significantly. The expression of the kdp operon in Synechocystis was induced by extracellular K+ depletion. Correspondingly, Kdp-mediated K+ uptake supported Synechocystis cell growth with trace amounts of external potassium. This induction of kdp expression depended on two adjacent genes, hik20 and rre19, encoding a putative two-component system. The circadian expression of kdp and ktr peaked at subjective dawn, which may support the acquisition of K+ required for the regular diurnal photosynthetic metabolism. These results indicate that Kdp contributes to the maintenance of a basal intracellular K+ concentration under conditions of limited K+ in natural environments, whereas Ktr mediates fast potassium movements in the presence of greater K+ availability. Through their distinct activities, both Ktr and Kdp coordinate the responses of Synechocystis to changes in K+ levels under fluctuating environmental conditions. PMID:25313394

  19. Effects of PAR and UV Radiation on the Structural and Functional Integrity of Phycocyanin, Phycoerythrin and Allophycocyanin Isolated from the Marine Cyanobacterium Lyngbya sp. A09DM.

    PubMed

    Rastogi, Rajesh Prasad; Sonani, Ravi Raghav; Madamwar, Datta

    2015-01-01

    An in vitro analysis of the effects of photosynthetically active and ultraviolet radiations was executed to assess the photostability of biologically relevant pigments phycocyanin (PC), phycoerythrin (PE) and allophycocyanin (APC) isolated from Lyngbya sp. A09DM. Ultraviolet (UV) irradiances significantly affected the integrity of PC, PE and APC; however, PAR showed least effect. UV radiation affected the bilin chromophores covalently attached to phycobiliproteins (PBPs). Almost complete elimination of the chromophore bands associated with ?- and ?-subunit of PE and APC occurred after 4 h of UV-B exposure. After 5 h of UV-B exposure, the content of PC, PE and APC decreased by 51.65%, 96.8% and 96.53%, respectively. Contrary to PAR and UV-A radiation, a severe decrease in fluorescence of all PBPs was observed under UV-B irradiation. The fluorescence activity of extracted PBP was gradually inhibited immediately after 15-30 min of UV-B exposure. In comparison to the PC, the fluorescence properties of PE and APC were severely lost under UV-B radiation. Moreover, the present study indicates that UV-B radiation can damage the structural and functional integrity of phycobiliproteins leading to the loss of their ecological and biological functions. PMID:25763657

  20. Effects of irradiation and pH on fluorescence properties and flocculation of extracellular polymeric substances from the cyanobacterium Chroococcus minutus.

    PubMed

    Song, Wenjuan; Zhao, Chenxi; Mu, Shuyong; Pan, Xiangliang; Zhang, Daoyong; Al-Misned, Fahad A; Mortuza, M Golam

    2015-04-01

    Microbial extracellular polymeric substances (EPS) may flocculate or be decomposed when environmental factors change, which significantly influences nutrient cycling and transport of heavy metals. However, little information is available on the stability of EPS in natural environments. Fluorescence and flocculation properties of EPS from Chroococcus minutus under different irradiation and pH conditions were studied. Two aromatic protein-like fluorescence peaks and one tyrosine protein-like peak were identified from the excitation-emission-matrix (EEM) fluorescence spectra of EPS. UVB (ultraviolet B) and solar irradiation increased the fluorescence intensity of all the three peaks while UVC (ultraviolet C) irradiation had little effect. EPS formed unstable flocs after exposure to UV (ultraviolet) irradiation and formed stable flocs under solar irradiation. EPS were prone to flocculation under highly acidic conditions and minimal fluorescence of peaks was observed. The fluorophores in EPS were relatively stable under neutral and alkaline conditions. These findings are helpful for understanding the behavior of EPS in aquatic environments and their role in biogeochemical cycles of the elements. PMID:25731101

  1. Proteome Analyses of Strains ATCC 51142 and PCC 7822 of the Diazotrophic Cyanobacterium Cyanothece sp under Culture Conditions Resulting in Enhanced H-2 Production

    SciTech Connect

    Aryal, Uma K.; Callister, Stephen J.; Mishra, Sujata; Zhang, Xiaohui; Shutthanandan, Janani I.; Angel, Thomas E.; Shukla, Anil K.; Monroe, Matthew E.; Moore, Ronald J.; Koppenaal, David W.; Smith, Richard D.; Sherman, Louis

    2013-02-01

    Cultures of the cyanobacterial genus Cyanothece have been shown to produce high levels of biohydrogen. These strains are diazotrophic and undergo pronounced diurnal cycles when grown under N2-fixing conditions in light-dark cycles. We seek to better understand the way in which proteins respond to these diurnal changes and we performed quantitative proteome analysis of Cyanothece ATCC 51142 and PCC 7822 grown under 8 different nutritional conditions. Nitrogenase expression was limited to N2-fixing conditions, and in the absence of glycerol, nitrogenase gene expression was linked to the dark period. However, glycerol induced expression of nitrogenase during part of the light period, together with cytochrome c oxidase (Cox), glycogen phosphorylase (Glp), and glycolytic and pentose-phosphate pathway (PPP) enzymes. This indicated that nitrogenase expression in the light was facilitated via higher respiration and glycogen breakdown. Key enzymes of the Calvin cycle were inhibited in Cyanothece ATCC 51142 in the presence of glycerol under H2 producing conditions, suggesting a competition between these sources of carbon. However, in Cyanothece PCC 7822, the Calvin cycle still played a role in cofactor recycling during H2 production. Our data comprise the first comprehensive profiling of proteome changes in Cyanothece PCC 7822, and allows an in-depth comparative analysis of major physiological and biochemical processes that influence H2-production in both the strains. Our results revealed many previously uncharacterized proteins that may play a role in nitrogenase activity and in other metabolic pathways and may provide suitable targets for genetic manipulation that would lead to improvement of large scale H2 production.

  2. In Vivo Regulation of Glutamine Synthetase Activity in the Marine Chlorophyll b-Containing Cyanobacterium Prochlorococcus sp. Strain PCC 9511 (Oxyphotobacteria)†

    PubMed Central

    El Alaoui, Sabah; Diez, Jesús; Humanes, Lourdes; Toribio, Fermín; Partensky, Frédéric; García-Fernández, José Manuel

    2001-01-01

    The physiological regulation of glutamine synthetase (GS; EC 6.3.1.2) in the axenic Prochlorococcus sp. strain PCC 9511 was studied. GS activity and antigen concentration were measured using the transferase and biosynthetic assays and the electroimmunoassay, respectively. GS activity decreased when cells were subjected to nitrogen starvation or cultured with oxidized nitrogen sources, which proved to be nonusable for Prochlorococcus growth. The GS activity in cultures subjected to long-term phosphorus starvation was lower than that in equivalent nitrogen-starved cultures. Azaserine, an inhibitor of glutamate synthase, provoked an increase in enzymatic activity, suggesting that glutamine is not involved in GS regulation. Darkness did not affect GS activity significantly, while the addition of diuron provoked GS inactivation. GS protein determination showed that azaserine induces an increase in the concentration of the enzyme. The unusual responses to darkness and nitrogen starvation could reflect adaptation mechanisms of Prochlorococcus for coping with a light- and nutrient-limited environment. PMID:11319101

  3. Comparative Analysis of Ultrafast Excitation Energy-Transfer Pathways in Three Strains of Divinyl Chlorophyll a/b-Containing Cyanobacterium, Prochlorococcus marinus.

    PubMed

    Hamada, Fumiya; Murakami, Akio; Akimoto, Seiji

    2015-12-24

    Prochlorococcus, a unique marine picocyanobacterium, contains the divinyl- (DV-) type chlorophylls (Chls), DV-Chl a and DV-Chl b, as its photosynthetic pigments. We comprehensively investigated the light-harvesting mechanisms in three strains of Prochlorococcus marinus (P. marinus) at physiological temperature (293 K) by ultrafast time-resolved fluorescence (TRF), steady-state fluorescence, and absorption measurements. These strains differ in their relative amounts of DV-Chl a, DV-Chl b, and carotenoids and in the pigment coupling conditions. All of the strains showed ultrafast excitation energy transfer from DV-Chl b to DV-Chl a, and the low-light-adapted strains, P. marinus CCMP1375 and CCMP2773, exhibited relatively higher DV-Chl b contents than P. marinus CCMP1986. It appears that carotenoid is another important antenna pigment, especially in the low-light-adapted strains (CCMP1375 and CCMP2773), that transfers the excitation energy to lower-energy DV-Chl a. PMID:26631221

  4. The small CAB-like proteins of the cyanobacterium Synechocystis sp. PCC 6803: Their involvement in chlorophyll biogenesis for Photosystem II

    E-print Network

    Futschik, Matthias E.

    in chlorophyll biogenesis for Photosystem II Miguel A. Hernandez-Prieto a,1 , Tania Tibiletti a , Leyla Abasova b-harvesting-like proteins Synechocystis sp. PCC 6803 High-light inducible proteins Chlorophyll The five small CAB. As previously described, the lack of SCPs affects the chlorophyll biosynthesis (Vavilin, D., Brune, D. C

  5. A Cyanobacterium Lacking Iron Superoxide Dismutase Is Sensitized to Oxidative Stress Induced with Methyl Viologen but Is Not Sensitized to Oxidative Stress Induced with Norflurazon1

    PubMed Central

    Thomas, David J.; Avenson, Thomas J.; Thomas, Jannette B.; Herbert, Stephen K.

    1998-01-01

    A strain of Synechococcus sp. strain PCC 7942 with no functional Fe superoxide dismutase (SOD), designated sodB?, was characterized by its growth rate, photosynthetic pigments, and cyclic photosynthetic electron transport activity when treated with methyl viologen or norflurazon (NF). In their unstressed conditions, both the sodB? and wild-type strains had similar chlorophyll and carotenoid contents and catalase activity, but the wild type had a faster growth rate and higher cyclic electron transport activity. The sodB? was very sensitive to methyl viologen, indicating a specific role for the FeSOD in protection against superoxide generated in the cytosol. In contrast, the sodB? mutant was less sensitive than the wild type to oxidative stress imposed with NF. This suggests that the FeSOD does not protect the cell from excited singlet-state oxygen generated within the thylakoid membrane. Another up-regulated antioxidant, possibly the MnSOD, may confer protection against NF in the sodB? strain. These results support the hypothesis that different SODs have specific protective functions within the cell. PMID:9536078

  6. A single arginyl residue in plastocyanin and in cytochrome c(6) from the cyanobacterium Anabaena sp. PCC 7119 is required for efficient reduction of photosystem I.

    PubMed

    Molina-Heredia, F P; Hervás, M; Navarro, J A; De la Rosa, M A

    2001-01-01

    Positively charged plastocyanin from Anabaena sp. PCC 7119 was investigated by site-directed mutagenesis. The reactivity of its mutants toward photosystem I was analyzed by laser flash spectroscopy. Replacement of arginine at position 88, which is adjacent to the copper ligand His-87, by glutamine and, in particular, by glutamate makes plastocyanin reduce its availability for transferring electrons to photosystem I. Such a residue in the copper protein thus appears to be isofunctional with Arg-64 (which is close to the heme group) in cytochrome c(6) from Anabaena (Molina-Heredia, F. P., Diaz-Quintana, A., Hervás, M., Navarro, J. A., and De la Rosa, M. A. (1999) J. Biol. Chem. 274, 33565-33570) and Synechocystis (De la Cerda, B., Diaz-Quintana, A., Navarro, J. A. , Hervás, M., and De la Rosa, M. A. (1999) J. Biol. Chem. 274, 13292-13297). Other mutations concern specific residues of plastocyanin either at its positively charged east face (D49K, H57A, H57E, K58A, K58E, Y83A, and Y83F) or at its north hydrophobic pole (L12A, K33A, and K33E). Mutations altering the surface electrostatic potential distribution allow the copper protein to modulate its kinetic efficiency: the more positively charged the interaction site, the higher the rate constant. Whereas replacement of Tyr-83 by either alanine or phenylalanine has no effect on the kinetics of photosystem I reduction, Leu-12 and Lys-33 are essential for the reactivity of plastocyanin. PMID:11013249

  7. Increased risk of exposure to microcystins in the scum of the filamentous cyanobacterium Aphanizomenon flos-aquae accumulated on the western shoreline of the Curonian Lagoon.

    PubMed

    Šul?ius, Sigitas; Pilkaityt?, Renata; Mazur-Marzec, Hanna; Kasperovi?ien?, J?rat?; Ezhova, Elena; B?aszczyk, Agata; Paškauskas, Ri?ardas

    2015-10-15

    Concentration of toxic cyanobacteria blooms on the downwind shore of high recreational amenity water bodies with largely increases the risk of exposure to cyanotoxins. In this study analysis of phytoplankton structure, cyanotoxin composition and concentration was performed on cyanobacteria scum material, high- and low-density bloom samples in the Curonian Lagoon. We found that the concentration of cyanotoxins in the scum material increased from ?30 to ?300-fold compared to bloom samples. In Microcystis aeruginosa dominated samples microcystin-LR was present at the highest concentration, while the dominance of Planktothrix agardhii was associated with the occurrence of dmMC-RR as the major microcystin variant. The toxicological potential of cyanobacterial scums in the Curonian Lagoon is emphasized, and management by removal of these scums is proposed. PMID:26234611

  8. A Hybrid Non-Ribosomal Peptide/Polyketide Synthetase Containing Fatty-Acyl Ligase (FAAL) Synthesizes the ?-Amino Fatty Acid Lipopeptides Puwainaphycins in the Cyanobacterium Cylindrospermum alatosporum

    PubMed Central

    Mareš, Jan; Hájek, Jan; Urajová, Petra; Kopecký, Ji?í; Hrouzek, Pavel

    2014-01-01

    A putative operon encoding the biosynthetic pathway for the cytotoxic cyanobacterial lipopeptides puwainphycins was identified in Cylindrospermum alatosporum. Bioinformatics analysis enabled sequential prediction of puwainaphycin biosynthesis; this process is initiated by the activation of a fatty acid residue via fatty acyl-AMP ligase and continued by a multidomain non-ribosomal peptide synthetase/polyketide synthetase. High-resolution mass spectrometry and nuclear magnetic resonance spectroscopy measurements proved the production of puwainaphycin F/G congeners differing in FA chain length formed by either 3-amino-2-hydroxy-4-methyl dodecanoic acid (4-methyl-Ahdoa) or 3-amino-2-hydroxy-4-methyl tetradecanoic acid (4-methyl-Ahtea). Because only one puwainaphycin operon was recovered in the genome, we suggest that the fatty acyl-AMP ligase and one of the amino acid adenylation domains (Asn/Gln) show extended substrate specificity. Our results provide the first insight into the biosynthesis of frequently occurring ?-amino fatty acid lipopeptides in cyanobacteria, which may facilitate analytical assessment and development of monitoring tools for cytotoxic cyanobacterial lipopeptides. PMID:25369527

  9. J. Avian Biol. 42: 8084, 2011 doi: 10.1111/j.1600-048X.2010.05128.x

    E-print Network

    Borgia, Gerald

    color is important in satin bowerbird Ptilonorhynchus violaceus display Jean-Franc¸ois Savard, Jason Keagy and Gerald Borgia J-F. Savard (jsavard@umd.edu) and Gerald Borgia, Dept of Biology, Biology/Psychology, Ecology, Evolution and Systematics (BEES), Biology/Psychology Building, Univ. of Maryland, College Park

  10. Effects of PipX on NtcA-dependent promoters and characterization of the cox3 promoter region in the heterocyst-forming cyanobacterium Anabaena sp. PCC 7120.

    PubMed

    Camargo, Sergio; Valladares, Ana; Forchhammer, Karl; Herrero, Antonia

    2014-05-01

    In Anabaena, the pipX gene is induced in the cells differentiating into heterocysts, being the PipX factor required for full expression of late heterocyst-specific genes. Here we show that PipX has a positive effect on in vitro binding of the transcription factor NtcA to DNA, as well as on transcript production, in different NtcA-dependent promoters. We found that the cox3 operon, encoding a heterocyst-specific terminal respiratory oxidase, is expressed from three nitrogen-regulated promoters to which NtcA binds. At the three sites, NtcA binding is potentiated by PipX. Thus, PipX has a direct effect on gene expression influencing the activity of NtcA. PMID:24685693

  11. Characterization of an alcohol dehydrogenase from the Cyanobacterium Synechocystis sp. strain PCC 6803 that responds to environmental stress conditions via the Hik34-Rre1 two-component system.

    PubMed

    Vidal, Rebeca; López-Maury, Luis; Guerrero, Miguel G; Florencio, Francisco J

    2009-07-01

    The slr1192 (adhA) gene from Synechocystis sp. strain PCC 6803 encodes a member of the medium-chain alcohol dehydrogenase/reductase family. The gene product AdhA exhibits NADP-dependent alcohol dehydrogenase activity, acting on a broad variety of aromatic and aliphatic primary alcohols and aldehydes but not on secondary alcohols or ketones. It exhibits superior catalytic efficiency for aldehyde reduction compared to that for alcohol oxidation. The enzyme is a cytosolic protein present in photoautotrophically grown Synechocystis cells. The expression of AdhA is enhanced upon the exposure of cells to different environmental stresses, although it is not essential for survival even under such stress conditions. The induction of the expression of the adhA gene is dependent on the Hik34-Rre1 two-component system, as it is severely impaired in mutant strains lacking either the histidine kinase Hik34 or the response regulator Rre1. In vitro DNA-protein interaction analysis reveals that the response regulator Rre1 binds specifically to the promoter region of the adhA gene. PMID:19411329

  12. Utilization of the terrestrial cyanobacteria

    NASA Astrophysics Data System (ADS)

    Katoh, Hiroshi; Tomita-Yokotani, Kaori; Furukawa, Jun; Kimura, Shunta; Yokoshima, Mika; Yamaguchi, Yuji; Takenaka, Hiroyuki

    The terrestrial, N _{2}-fixing cyanobacterium, Nostoc commune has expected to utilize for agriculture, food and terraforming cause of its extracellular polysaccharide, desiccation tolerance and nitrogen fixation. Previously, the first author indicated that desiccation related genes were analyzed and the suggested that the genes were related to nitrogen fixation and metabolisms. In this report, we suggest possibility of agriculture, using the cyanobacterium. Further, we also found radioactive compounds accumulated N. commune (cyanobacterium) in Fukushima, Japan after nuclear accident. Thus, it is investigated to decontaminate radioactive compounds from the surface soil by the cyanobacterium and showed to accumulate radioactive compounds using the cyanobacterium. We will discuss utilization of terrestrial cyanobacteria under closed environment. Keyword: Desiccation, terrestrial cyanobacteria, bioremediation, agriculture

  13. More than one way to be an herbivore: convergent evolution of herbivory using different digestive strategies in prickleback fishes (Stichaeidae).

    PubMed

    German, Donovan P; Sung, Aaron; Jhaveri, Parth; Agnihotri, Ritika

    2015-06-01

    In fishes, the evolution of herbivory has occured within a spectrum of digestive strategies, with two extremes on opposite ends: (i) a rate-maximization strategy characterized by high intake, rapid throughput of food through the gut, and little reliance on microbial digestion or (ii) a yield-maximization strategy characterized by measured intake, slower transit of food through the gut, and more of a reliance on microbial digestion in the hindgut. One of these strategies tends to be favored within a given clade of fishes. Here, we tested the hypothesis that rate or yield digestive strategies can arise in convergently evolved herbivores within a given lineage. In the family Stichaeidae, convergent evolution of herbivory occured in Cebidichthys violaceus and Xiphister mucosus, and despite nearly identical diets, these two species have different digestive physiologies. We found that C. violaceus has more digesta in its distal intestine than other gut regions, has comparatively high concentrations (>11 mM) of short-chain fatty acids (SCFA, the endpoints of microbial fermentation) in its distal intestine, and a spike in ?-glucosidase activity in this gut region, findings that, when coupled to long retention times (>20 h) of food in the guts of C. violaceus, suggest a yield-maximizing strategy in this species. X. mucosus showed none of these features and was more similar to its sister taxon, the omnivorous Xiphister atropurpureus, in terms of digestive enzyme activities, gut content partitioning, and concentrations of SCFA in their distal intestines. We also contrasted these herbivores and omnivores with other sympatric stichaeid fishes, Phytichthys chirus (omnivore) and Anoplarchus purpurescens (carnivore), each of which had digestive physiologies consistent with the consumption of animal material. This study shows that rate- and yield-maximizing strategies can evolve in closely related fishes and suggests that resource partitioning can play out on the level of digestive physiology in sympatric, closely related herbivores. PMID:25769813

  14. Late summer food habits of three heron species in northeastern Louisiana

    USGS Publications Warehouse

    Niethammer, K.R.; Kaiser, M.S.

    1983-01-01

    Yellow-crowned Night-Herons (Nycticorax violaceus), Little Blue Herons (Egretta caerulea), and Green-backed Herons (Butorides striatus) collected in northeastern Louisiana from July-September 1980 exhibited different diets. Yellow-crowned Night-Herons fed mostly on crayfish (74% by weight) and Green-backed Herons fed primarily on fish (93% by weight). The diet of Little Blue Herons was diverse, including fish (61%), crustaceans (11%), insects (13%), and arachnids (14%). Yellow-crowned Night-Herons captured larger prey than did either of the smaller herons. Green-backed Herons took larger prey and a greater range of prey sizes than did the larger Little Blue Herons.

  15. THE PHYTOCHROMES: A BIOCHEMICAL MECHANISM OF SIGNALING IN SIGHT?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The biochemical mechanism by which the phytochrome family of plant sensory photoreceptors transmit perceived informational light signals downstream to transduction pathway components is undetermined. However, the recent sequencing of the entire genome of the cyanobacterium Synechocystis has reveale...

  16. Cylindrospermopsis in Lake Erie: Testing its association with other cyanobacterial genera and major limnological parameters

    EPA Science Inventory

    We report the first documented observation of the potentially toxic cyanobacterium Cylindrospermopsis in lake Erie and Sandusky Bay in 2005 and quantify the physical and chemical parameters and the cyanobacterial community composition contemporaneous to its occurrence. We hypothe...

  17. ProPortal: a resource for integrated systems biology of Prochlorococcus and its phage

    E-print Network

    Kelly, Libusha

    ProPortal (http://proportal.mit.edu/) is a database containing genomic, metagenomic, transcriptomic and field data for the marine cyanobacterium Prochlorococcus. Our goal is to provide a source of cross-referenced data ...

  18. The spontaneous mutation frequencies of Prochlorococcus strains are commensurate with those of other bacteria

    E-print Network

    Osburne, Marcia

    The marine cyanobacterium Prochlorococcus, the smallest and most abundant oxygenic phototroph, has an extremely streamlined genome and a high rate of protein evolution. High-light adapted strains of Prochlorococcus in ...

  19. Widespread metabolic potential for nitrite and nitrate assimilation among Prochlorococcus ecotypes

    E-print Network

    Kathuria, Satish

    The marine cyanobacterium Prochlorococcus is the most abundant photosynthetic organism in oligotrophic regions of the oceans. The inability to assimilate nitrate is considered an important factor underlying the distribution ...

  20. Prochlorococcus genetic transformation and genomics of nitrogen metabolism

    E-print Network

    Tolonen, Andrew Carl

    2005-01-01

    Prochlorococcus, a unicellular cyanobacterium, is the most abundant phytoplankton in the oligotrophic, oceanic gyres where major plant nutrients such as nitrogen (N) and phosphorus (P) are at nanomolar concentrations. ...

  1. Genetic diversity and its consequences for light adaptation in Prochlorococcus

    E-print Network

    Kettler, Gregory C. (Gregory Carl)

    2011-01-01

    When different cells thrive across diverse environments, their genetic differences can reveal what genes are essential to survival in a particular environment. Prochlorococcus, a cyanobacterium that dominates the open ...

  2. Bioassay-guided Isolation of Anti-Algal Constituents from Inula Helenium and Limonium Myrianthum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Over 70 crude plant extracts, primarily from Kazakhstan, were screened against the freshwater phytoplanktons Oscillatoria perornata and Selenastrum capricornutum. Extracts from Limonium myrianthum and Inula helenium both demonstrated selective inhibition against the odor-producing cyanobacterium O....

  3. Choreography of the transcriptome, photophysiology, and cell cycle of a minimal photoautotroph, prochlorococcus

    E-print Network

    Zinser, Erik R.

    The marine cyanobacterium Prochlorococcus MED4 has the smallest genome and cell size of all known photosynthetic organisms. Like all phototrophs at temperate latitudes, it experiences predictable daily variation in available ...

  4. Encoded Fiber-Optic Microsphere Arrays for Probing ProteinCarbohydrate Interactions**

    E-print Network

    Ratner, Daniel M.

    for studying protein­carbohydrate interactions, we examined two systems: the mannose-binding lectin the cyanobacterium Nostoc ellipsosporum with spe- cificity for with a high mannose oligosaccharides.[5] Mannose 1 and

  5. Prochlorococcus: the structure and function of collective diversity

    E-print Network

    Berube, Paul M.

    The marine cyanobacterium Prochlorococcus is the smallest and most abundant photosynthetic organism on Earth. In this Review, we summarize our understanding of the diversity of this remarkable phototroph and describe its ...

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

    E-print Network

    Cox, Alysia D.

    Synechococcus sp. WH 8102 is a motile marine cyanobacterium isolated originally from the Sargasso Sea. To test the response of this organism to cadmium (Cd), generally considered a toxin, cultures were grown in a matrix ...

  7. Transcriptome and Proteome Dynamics of a Light-Dark Synchronized Bacterial Cell Cycle

    E-print Network

    Chisholm, Sallie (Penny)

    Growth of the ocean's most abundant primary producer, the cyanobacterium Prochlorococcus, is tightly synchronized to the natural 24-hour light-dark cycle. We sought to quantify the relationship between transcriptome and ...

  8. Publications for Yaqiong Li Li, Y., Chen, M. (2015). Novel chlorophylls and new directions

    E-print Network

    Müller, Dietmar

    2015-01-01

    in photosynthesis research. Functional Plant Biology, 42(6), 493-501. containing chlorophyll f. Frontiers in Plant Science, 5(FEB), 1- 12. ). A Novel Epiphytic Chlorophyll d- containing Cyanobacterium Isolated from a Mangrove- associated Red Alga

  9. Structure and dynamics of genome-wide diversity in Prochlorococcus

    E-print Network

    Coleman, Maureen Lynn

    2008-01-01

    The capability of microbes to thrive in myriad environments has its foundation in the diversity of microbial genomes. Here we explore adaptation and diversification through the lens of the marine cyanobacterium Prochlorococcus, ...

  10. Production and secretion of glucose in photosynthetic prokaryotes (cyanobacteria)

    DOEpatents

    Nobles, Jr., David R. (Austin, TX), Brown, Jr., R. Malcolm (Austin, TX)

    2010-09-28

    The present invention includes compositions and methods for making and using an isolated cyanobacterium that includes a portion of an exogenous bacterial cellulose operon sufficient to express bacterial cellulose, whereby the cyanobacterium produces extracellular glucose. The compositions and methods of the present invention may be used as a new global crop for the manufacture of cellulose, CO.sub.2 fixation, for the production of alternative sources of conventional cellulose as well as a biofuel and precursors thereof.

  11. Redescription of Atopospira galeata (Kahl, 1927) nov. comb. and A. violacea (Kahl, 1926) nov. comb. with redefinition of Atopospira Jankowski, 1964 nov. stat. and Brachonella Jankowski, 1964 (Ciliophora, Armophorida).

    PubMed

    Bourland, William A; Wendell, Laura

    2014-08-01

    The taxonomy of the Metopidae (Ciliophora, Armophorida) remains poorly understood since most of its members have not been studied by modern morphologic and molecular methods. Recent molecular investigations have indicated that the two most species-rich genera, Metopus and Brachonella, are likely nonmonophyletic with at least one well-supported 18S rDNA clade comprised of a species from each of these genera (Brachonella galeata and Metopus violaceus). We investigated these two species with silver impregnation and scanning electron microscopy. Both taxa share important morphologic characteristics not described in other species of Metopus or Brachonella. These synapomorphies include: (1) a diplostichomonad paroral membrane, (2) a bipartite adoral zone with a short buccal part composed of ordinary membranelles and a longer distal part composed of much smaller membranelles bearing a single cilium or none and extending the same length as the perzonal ciliary stripe. We transfer Brachonella galeata (Kahl, 1927) Jankowski, 1964 and Metopus violaceus Kahl, 1926 to genus Atopospira Jankowski, 1964 nov. stat. Pending detailed morphologic and molecular characterization, Brachonella campanula, B. cydonia and B. pyriforma, B. intercedens, and B. lemani remain in Brachonella Jankowski 1964. PMID:25129835

  12. Evolution of ontogenetic dietary shifts and associated gut features in prickleback fishes (Teleostei: Stichaeidae).

    PubMed

    German, D P; Gawlicka, A K; Horn, M H

    2014-02-01

    We tested the hypothesis that an ontogenetic dietary shift from carnivory to herbivory or omnivory, and concomitant changes in the gut facilitating digestion of algae, are synapomorphies of the tribes Xiphisterini and Esselenichthyini in the family Stichaeidae (pricklebacks). Previous investigations have revealed that two xiphisterine pricklebacks-Xiphister mucosus and Xiphister atropurpureus-become herbivorous or omnivorous, respectively, as their bodies grow larger, and that their guts show related changes in length and function. In this study we found that, with increase in size, the basal member of the Xiphisterini, Phytichthys chirus, showed an increased proportion of algae in its diet, increased activity of ?-amylase and decreased activity of aminopeptidase, all of which support the synapomorphy hypothesis. Cebidichthys violaceus, a herbivore in the Esselenichthyini, shows similar ontogenetic changes in diet and digestive tract length and physiology, but these features were not observed in two derived carnivores, Dictyosoma burgeri and Dictyosoma rubrimaculatum, within the clade. These results suggest that herbivory is isolated to C. violaceus within the Esselenichthyini. Allometric relationships of gut length as a function of body size generally follow diet within the Xiphisterini and Esselenichthyini, with herbivores having the longest guts, which become disproportionately longer than body size as the fishes grow, omnivores intermediate gut lengths, and carnivores the shortest. A carnivore from an adjacent clade, Anoplarchus purpurescens, had the shortest gut, which did not change in length relative to body length as the fish grew. Overall, our results clarify the patterns of dietary evolution within the Stichaeidae and lay the foundation for more detailed studies of dietary and digestive specialization in fishes in the family. PMID:24269211

  13. Sequence and expression of an ?-amylase gene in four related species of prickleback fishes (Teleostei: Stichaeidae): ontogenetic, dietary, and species-level effects.

    PubMed

    Kim, Kelly H; Horn, Michael H; Sosa, Abraham E; German, Donovan P

    2014-02-01

    Partial ?-amylase gene sequences were determined and ?-amylase gene expression was quantified in four species of carnivorous, omnivorous, and herbivorous prickleback fishes (family Stichaeidae) to assess the effects of ontogeny, diet, and species on expression of this gene. Pairwise comparison of ?-amylase nucleotide sequences revealed 96-98 % identity, and comparison of amino acid portions revealed 93-95 % similarity among the four prickleback species. Expression was determined using in situ hybridization and intensity of expression quantified using image analysis. Alpha-amylase expression level was compared in three feeding categories of the four species: (1) small, wild-caught carnivorous juveniles; (2) larger, wild-caught juveniles of the carnivorous species and the three that had shifted to herbivory or omnivory; and (3) larger, juveniles produced by feeding a low-starch artificial diet to small juveniles until they reached the size of the larger wild-caught juveniles. The results showed no dietary effect in any species but significant ontogenetic and species-level effects in Cebidichthys violaceus, as well as in the sister species Xiphister mucosus and X. atropurpureus. Based on a phylogeny for the Stichaeidae produced for this study using two mtDNA genes and one nuclear gene, the ontogenetic dietary shifts to herbivory/omnivory evolved independently in C. violaceus and in the clade containing the two species of Xiphister. All three of these species increased ?-amylase gene expression with increase in size and had higher expression than Anoplarchus purpurescens, which is a member of a third, stichaeid clade comprising carnivores. These results show the importance of ?-amylase in the herbivores and omnivores. PMID:24136006

  14. Cold-activation of Brassica napus BN115 promoter is mediated by structural changes in membranes and

    E-print Network

    Dhindsa, Rajinder

    Cold-activation of Brassica napus BN115 promoter is mediated by structural changes in membranes-mail RDHINDSA@Bio1.LAN.MCGILL.CA). Summary Previous studies on cold-triggered events leading to Ca2+ in¯ux during cold acclimatization have been conducted on either unicellular cyanobacterium Synechocystis

  15. Draft Genome Sequence of Tolypothrix boutellei Strain VB521301

    PubMed Central

    Chandrababunaidu, Mathu Malar; Singh, Deeksha; Sen, Diya; Bhan, Sushma; Das, Subhadeep; Gupta, Akash

    2015-01-01

    We report here the draft genome sequence of the filamentous nitrogen-fixing cyanobacterium Tolypothrix boutellei strain VB521301. The organism is lipid rich and hydrophobic and produces polyunsaturated fatty acids which can be harnessed for industrial purpose. The draft genome sequence assembled into 11,572,263 bp with 70 scaffolds and 7,777 protein coding genes. PMID:25700407

  16. Draft Genome Sequence of the Picocyanobacterium Synechococcus sp. Strain GFB01, Isolated from a Freshwater Lagoon in the Brazilian Amazon

    PubMed Central

    Leão, Tiago Ferreira; de Melo, Aline Grasielle Costa; Ramos, Rommel Thiago Jucá; Silva, Artur; Fiore, Marli Fatima; Schneider, Maria Paula Cruz

    2015-01-01

    We present the draft genome of the cyanobacterium strain Synechococcus sp. GFB01, the first genome sequencing of this genus isolated from South America. This draft genome consists of 125 contigs with a total size of 2,339,812 bp. Automatic annotation identified several genes involved with heavy metal resistance and natural transformation. PMID:26272565

  17. Using "Fremyella Diplosiphon" as a Model Organism for Genetics-Based Laboratory Exercises

    ERIC Educational Resources Information Center

    Montgomery, Beronda L.

    2011-01-01

    In this pilot study, a genetics-based laboratory exercise using the cyanobacterium Fremyella diplosiphon was developed and trialled with thirteen Natural Sciences undergraduates. Despite most students only having limited prior exposure to molecular genetics laboratory methods, this cohort confirmed that they were able to follow the protocol and…

  18. Ideal Osmotic Spaces for Chlorobionts or Cyanobionts Are Differentially Realized by Lichenized Fungi1[W][OPEN

    PubMed Central

    Kosugi, Makiko; Shizuma, Ryoko; Moriyama, Yufu; Koike, Hiroyuki; Fukunaga, Yuko; Takeuchi, Akihisa; Uesugi, Kentaro; Suzuki, Yoshio; Imura, Satoshi; Kudoh, Sakae; Miyazawa, Atsuo; Kashino, Yasuhiro; Satoh, Kazuhiko

    2014-01-01

    Lichens result from symbioses between a fungus and either a green alga or a cyanobacterium. They are known to exhibit extreme desiccation tolerance. We investigated the mechanism that makes photobionts biologically active under severe desiccation using green algal lichens (chlorolichens), cyanobacterial lichens (cyanolichens), a cephalodia-possessing lichen composed of green algal and cyanobacterial parts within the same thallus, a green algal photobiont, an aerial green alga, and a terrestrial cyanobacterium. The photosynthetic response to dehydration by the cyanolichen was almost the same as that of the terrestrial cyanobacterium but was more sensitive than that of the chlorolichen or the chlorobiont. Different responses to dehydration were closely related to cellular osmolarity; osmolarity was comparable between the cyanolichen and a cyanobacterium as well as between a chlorolichen and a green alga. In the cephalodium-possessing lichen, osmolarity and the effect of dehydration on cephalodia were similar to those exhibited by cyanolichens. The green algal part response was similar to those exhibited by chlorolichens. Through the analysis of cellular osmolarity, it was clearly shown that photobionts retain their original properties as free-living organisms even after lichenization. PMID:25056923

  19. Cellular Function and Localization of Circadian Clock Proteins in Cyanobacteria 

    E-print Network

    Dong, Guogang

    2011-08-08

    The cyanobacterium Synechococcus elongatus builds a circadian clock on an oscillator comprised of three proteins, KaiA, KaiB, and KaiC, which can recapitulate a circadian rhythm of KaiC phosphorylation in vitro. The molecular structures of all three proteins... ..............................................................................................xiv CHAPTER I INTRODUCTION .............................................................................1 Circadian Rhythms ......................................................................................1 Synechococcus elongatus PCC 7942 as a...

  20. Nostoc sphaeroides Kütz, a candidate producer par excellence for CELSS

    NASA Astrophysics Data System (ADS)

    Wang, Gaohong; Hao, Zongjie; Liu, Yongding

    A lot of aquatic organisms could be regarded as suitable candidates par excellence in the establishment of CELSS, since they are relatively easy and fast to grow and resistant to changes in environmental condition as well as providing nutritious, protein-and vitamin-rich foods for the crew, which can fulfill the main functions of CELSS, including supplying oxygen, water and food, removing carbon dioxide and making daily life waste reusable. Our labotory has developed mass culture of Nostoc sphaeroides Kütz, which is one of traditional healthy food in China and. The oxygen evolution rate of the cyanobacterium is about 150 molO2.mg-1.h-1, and it usually grows into colony with size between 2-20mm, which is easy to be harvested. It also can be cultured with high density, which show that the productivity of the cyanobacterium in limited volume is higher than other microalgae. We had measured the nutrient content of the cyanobacterium and developed some Chinese Dishes and Soups with Nostoc sphaeroides Kütz, which showed that it was a good food for crew. Using remote sensing technique, we also investigated its growth in Closed System under microgravity by SHENZHOU-2 spacecraft in January 2001. We plan to develop suitable bioreactor with the cyanobacterium for supplying oxygen and food to crew in future.

  1. Spatial and temporal distribution of Trichodesmium blooms in the world's oceans

    E-print Network

    Siegel, David A.

    in the oceanic N cycle through its conversion of dissolved gaseous N (N2) to combined nitrogen. Estimated rates December 2006. [1] Nitrogen fixing organisms, such as the cyanobacterium Trichodesmium, directly affect the oceanic nutrient inventory through the addition of new nitrogen to the ocean ecosystem and therefore have

  2. JOURNAL OF BACTERIOLOGY, July 2007, p. 52475256 Vol. 189, No. 14 0021-9193/07/$08.00 0 doi:10.1128/JB.00360-07

    E-print Network

    Summers, Michael L.

    cyanobacterium Nostoc punctiforme can differentiate into three mutually exclusive cell types: nitrogen- plete nutrients, including a source of combined nitrogen such as ammonium, light, and CO2 or in the dark with glucose or fructose as a source of reduced carbon, a permissive vegetative cell cycle consisting of growth

  3. PUBLISHED ONLINE: 5 JANUARY 2015 | DOI: 10.1038/NGEO2327 Modulation of oxygen production in Archaean

    E-print Network

    Konhauser, Kurt

    photosynthesis, such as the toxicity of oxygen to the organisms who first produced it7 , or that a paucity of key nutrient for oxygenic photosynthesis in modern, oxic oceans, and enhanced Fe fluxes to the surface ocean cyanobacterium Synechococcus PCC 7002 to examine the effects of Fe(II) on oxygenic photosynthesis (see

  4. Collaborative Understanding of Cyanobacteria in Lake Ecosystems

    ERIC Educational Resources Information Center

    Greer, Meredith L.; Ewing, Holly A.; Cottingham, Kathryn L.; Weathers, Kathleen C.

    2013-01-01

    We describe a collaboration between mathematicians and ecologists studying the cyanobacterium "Gloeotrichia echinulata" and its possible role in eutrophication of New England lakes. The mathematics includes compartmental modeling, differential equations, difference equations, and testing models against high-frequency data. The ecology…

  5. The light-harvesting function of carotenoids in the cyanobacterial stress-inducible IsiA complex

    E-print Network

    van Stokkum, Ivo

    Available online xxxx Keywords: Carotenoids Light harvesting Ultrafast spectroscopy Cyanobacteria a b s t r in aggregates of the IsiA pigment­protein complex of the cyanobacterium Synechocystis PCC 6803. The results show the same extent as in the related pigment­protein complexes CP43 and CP47. Selective excitation at the red

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

    DOE PAGESBeta

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

    2014-10-18

    The model alga Chlamydomonas reinhardtii requires acetate as a co-substrate for optimal production of lipids, and the addition of acetate to culture media has practical and economic implications for algal biofuel production. We demonstrate the growth of C. reinhardtii on acetate provided by mutant strains of the cyanobacterium Synechococcus sp. PCC7002.

  7. Comparative Toxicity of the Phytotoxins (8R,16R)-(-)-Pyrenophorin and (5S,8R,13S,16R)-(-)-Pyrenophorol on Aquatic Organisms

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The acute toxicities of the fungal phytotoxins (8R,16R)-(-)-pyrenophorin and (5S,8R,13S,16R)-(-)-pyrenophorol on five aquatic organisms were estimated. The evaluation was based on bioluminescence inhibition of Microtox® bacterium Vibrio fischeri and the growth of the cyanobacterium Oscillatoria pero...

  8. Temperature Effect on Entrainment, Phase Shifting, and Amplitude of Circadian Clocks

    E-print Network

    Hinze, Thomas

    Temperature Effect on Entrainment, Phase Shifting, and Amplitude of Circadian Clocks and its a series of input pathways a series of output pathways circadian clocks July 7, 2014Maria Prauße 3 #12 cyanobacterium one of the evolutionary oldest species, which has a circadian clock characteristics: well

  9. Genetically engineering cyanobacteria to convert CO?, water, and light into the long-chain hydrocarbon farnesene.

    PubMed

    Halfmann, Charles; Gu, Liping; Gibbons, William; Zhou, Ruanbao

    2014-12-01

    Genetically engineered cyanobacteria offer a shortcut to convert CO2 and H2O directly into biofuels and high value chemicals for societal benefits. Farnesene, a long-chained hydrocarbon (C15H24), has many applications in lubricants, cosmetics, fragrances, and biofuels. However, a method for the sustainable, photosynthetic production of farnesene has been lacking. Here, we report the photosynthetic production of farnesene by the filamentous cyanobacterium Anabaena sp. PCC 7120 using only CO2, mineralized water, and light. A codon-optimized farnesene synthase gene was chemically synthesized and then expressed in the cyanobacterium, enabling it to synthesize farnesene through its endogenous non-mevalonate (MEP) pathway. Farnesene excreted from the engineered cyanobacterium volatilized into the flask head space and was recovered by adsorption in a resin column. The maximum photosynthetic productivity of farnesene was 69.1?±?1.8 ?g·L(-1)·O.D.(-1)·d(-1). Compared to the wild type, the farnesene-producing cyanobacterium also exhibited a 60 % higher PSII activity under high light, suggesting increased farnesene productivity in such conditions. We envision genetically engineered cyanobacteria as a bio-solar factory for photosynthetic production of a wide range of biofuels and commodity chemicals. PMID:25301585

  10. Bibliography on CO2 Effects on Vegetation and Ecosystems: 1990-1999 Literature Michael H. Jones and Peter S. Curtis, editors

    E-print Network

    . Schiewer. 1993. Ammonium rhythm in cultures of the cyanobacterium microcystis- firma. Physiologia Plantarum technique that could be suitable for soybean plants (Glycine max [L.] Merr.), and to study the effect of long-term injection of sucrose on the growth of soybean plants. An injection setup comprising

  11. SECONDARY METABOLITES FROM PLANTS AND MARINE ORGANISMS AS SELECTIVE ANTI-CYANOBACTERIAL AGENTS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Extracts of more than one thousand species of plants and marine organisms were evaluated for selective algicidal activity against the musty-odor cyanobacterium (blue-green alga) Oscillatoria perornata. Bioassay-guided fractionation yielded anti-cyanobacterial compounds from the tropical marine brow...

  12. Proc. Natl. Acad. Sci. USA Vol. 92, pp. 175-179, January 1995

    E-print Network

    Roegner, Matthias

    ) complexes, isolated from spinach and the thermophilic cyanobacterium Synecho- coccus elongatus, were complexes from spinach and Synechococcus having molecular masses of about 450 kDa and dimensions of "17.2 x image analysis of oxygen-evolving monomeric cores of PSII isolated from spinach and Synechococcus having

  13. Rapid Electron Transfer to Photosystem I and Unusual Spectral Features of Cytochrome c6 in Synechococcus sp. PCC 7002 in Vivo

    E-print Network

    c6 proteins. Rapid oxidation of cytochrome c6 by PS I in vivo results in a unique, asymmetric cytochrome c6 to PS I in this cyanobacterium in vivo, indicating prefixation of the reduced donor protein oxidation spectrum, which differs significantly from the spectra obtained for cytochrome c6 in solution

  14. In Vitro Oligomerization of a Membrane Protein Complex LIPOSOME-BASED RECONSTITUTION OF TRIMERIC PHOTOSYSTEM I FROM ISOLATED MONOMERS*

    E-print Network

    Roegner, Matthias

    the Faculty of Biology, Plant Biochemistry, Ruhr-University Bochum, D-44780 Bochum, Germany and §A. N. Bakh nor its biological role are known at present. In the filamentous cyanobacterium Spirulina platensis I is one of the two light-driven electron pumps involved in oxygenic photosynthesis of green plants

  15. Structure of the dual-function fructose-1,6/sedoheptulose-1,7-bisphosphatase from Thermosynechococcus elongatus bound with sedoheptulose-7-phosphate.

    PubMed

    Cotton, Charles A R; Kabasakal, Burak V; Miah, Nishat A; Murray, James W

    2015-10-01

    The dual-function fructose-1,6/sedoheptulose-1,7-bisphosphatase (FBP/SBPase) in cyanobacteria carries out two activities in the Calvin cycle. Structures of this enzyme from the cyanobacterium Synechocystis sp. PCC 6803 exist, but only with adenosine monophosphate (AMP) or fructose-1,6-bisphosphate and AMP bound. The mechanisms which control both selectivity between the two sugars and the structural mechanisms for redox control are still unresolved. Here, the structure of the dual-function FBP/SBPase from the thermophilic cyanobacterium Thermosynechococcus elongatus is presented with sedoheptulose-7-phosphate bound and in the absence of AMP. The structure is globally very similar to the Synechocystis sp. PCC 6803 enzyme, but highlights features of selectivity at the active site and loop ordering at the AMP-binding site. Understanding the selectivity and control of this enzyme is critical for understanding the Calvin cycle in cyanobacteria and for possible biotechnological application in plants. PMID:26457528

  16. Phormidium animalis (Cyanobacteria: Oscillatoriaceae) supports larval development of Anopheles albimanus.

    PubMed

    Vázquez-Martínez, M Guadalupe; Rodríguez, Mario H; Arredondo-Jiménez, Juan I; Méndez-Sánchez, José D

    2003-06-01

    The capability of Phormidium animalis, a cyanobacterium commonly found in larval habitats of Anopheles albimanus in southern Mexico, to support larval development of this mosquito was investigated. First-stage larvae were reared under insectary conditions with P. animalis ad libitum and their development was compared with larvae fed with wheat germ. The time of pupation and adult mosquito size, assessed by wing length, were similar in both groups, but fewer adult mosquitoes were obtained from larvae fed with the cyanobacteria. Nevertheless, these observations indicate that P. animalis is ingested and assimilated by larval An. albimanus, making this cyanobacterium a good candidate for genetic engineering for the introduction of mosquitocidal toxins for malaria control in the region. PMID:12825668

  17. Removal of triazine herbicides from freshwater systems using photosynthetic microorganisms.

    PubMed

    González-Barreiro, O; Rioboo, C; Herrero, C; Cid, A

    2006-11-01

    The uptake of the triazine herbicides, atrazine and terbutryn, was determined for two freshwater photosynthetic microorganisms, the green microalga Chlorella vulgaris and the cyanobacterium Synechococcus elongatus. An extremely rapid uptake of both pesticides was recorded, although uptake rate was lower for the cyanobacterium, mainly for atrazine. Other parameters related to the herbicide bioconcentration capacity of these microorganisms were also studied. Growth rate, biomass, and cell viability in cultures containing herbicide were clearly affected by herbicide uptake. Herbicide toxicity and microalgae sensitivity were used to determine the effectiveness of the bioconcentration process and the stability of herbicide removal. C. vulgaris showed higher bioconcentration capability for these two triazine herbicides than S. elongatus, especially with regard to terbutryn. This study supports the usefulness of such microorganisms, as a bioremediation technique in freshwater systems polluted with triazine herbicides. PMID:16488522

  18. Synechococcus elongatus UTEX 2973, a fast growing cyanobacterial chassis for biosynthesis using light and CO2

    DOE PAGESBeta

    Yu, Jingjie; Liberton, Michelle; Cliften, Paul F.; Head, Richard D.; Jacobs, Jon M.; Smith, Richard D.; Koppenaal, David W.; Brand, Jerry J.; Pakrasi, Himadri B.

    2015-01-30

    Photosynthetic microbes are of emerging interest as production organisms in biotechnology because they can grow autotrophically using sunlight, an abundant energy source, and CO2, a greenhouse gas. Important traits for such microbes are fast growth and amenability to genetic manipulation. Here we describe Synechococcus elongatus UTEX 2973, a unicellular cyanobacterium capable of rapid autotrophic growth, comparable to heterotrophic industrial hosts such as yeast. Synechococcus 2973 can be readily transformed for facile generation of desired knockout and knock-in mutations. Genome sequencing coupled with global proteomics studies revealed that Synechococcus 2973 is a close relative of the widely studied cyanobacterium Synechococcus elongatusmore »PCC 7942, an organism that grows more than two times slower. A small number of nucleotide changes are the only significant differences between the genomes of these two cyanobacterial strains. Thus, our study has unraveled genetic determinants necessary for rapid growth of cyanobacterial strains of significant industrial potential.« less

  19. Synechococcus elongatus UTEX 2973, a fast growing cyanobacterial chassis for biosynthesis using light and CO2

    SciTech Connect

    Yu, Jingjie; Liberton, Michelle; Cliften, Paul F.; Head, Richard D.; Jacobs, Jon M.; Smith, Richard D.; Koppenaal, David W.; Brand, Jerry J.; Pakrasi, Himadri B.

    2015-01-30

    Photosynthetic microbes are of emerging interest as production organisms in biotechnology because they can grow autotrophically using sunlight, an abundant energy source, and CO2, a greenhouse gas. Important traits for such microbes are fast growth and amenability to genetic manipulation. Here we describe Synechococcus elongatus UTEX 2973, a unicellular cyanobacterium capable of rapid autotrophic growth, comparable to heterotrophic industrial hosts such as yeast. Synechococcus 2973 can be readily transformed for facile generation of desired knockout and knock-in mutations. Genome sequencing coupled with global proteomics studies revealed that Synechococcus 2973 is a close relative of the widely studied cyanobacterium Synechococcus elongatus PCC 7942, an organism that grows more than two times slower. A small number of nucleotide changes are the only significant differences between the genomes of these two cyanobacterial strains. Thus, our study has unraveled genetic determinants necessary for rapid growth of cyanobacterial strains of significant industrial potential.

  20. Evaluation of functional substances in the selected food materials for space agriculture

    NASA Astrophysics Data System (ADS)

    Tomita-Yokotani, Kaori; Kimura, Yasuko; Yamashita, Masamichi; Kimura, Shunta; Sato, Seigo; Katoh, Hiroshi; Abe, Yusuke; Ajioka, Reiko

    We have been studying the useful life-support system in closed bio-ecosystem for space agriculture. We have already proposed the several species as food material, such as Nostoc sp. HK-01 and Prunnus sp., cyanobacterium and Japanese cherry tree, respectively. The cyanobacterium, Nostoc sp Hk-01, has high tolerances to several space environment. Furthermore, the woody plant materials have useful utilization elements in our habitation environment. The studies of woody plants under a space-environment in the vegetable kingdom have a high contribution to the study of various and exotic environmental responses, too. We have already found that they can produce the important functional substances for human. Here, we will show the evaluation of functional substances in the selected food materials under the possible conditions for space agriculture after cooking.