Science.gov

Sample records for green algae evidence

  1. Blue-green algae

    MedlinePlus

    ... conditions, cancer, fatty liver disease, hepatitis C, and arsenic poisoning. Blue-green algae are applied inside the mouth ... people with insulin resistance due to HIV medication. Arsenic poisoning. Early research shows that taking 250 mg of ...

  2. Evidence for land plant cell wall biosynthetic mechanisms in charophyte green algae

    PubMed Central

    Mikkelsen, Maria D.; Harholt, Jesper; Ulvskov, Peter; Johansen, Ida E.; Fangel, Jonatan U.; Doblin, Monika S.; Bacic, Antony; Willats, William G. T.

    2014-01-01

    Background and Aims The charophyte green algae (CGA) are thought to be the closest living relatives to the land plants, and ancestral CGA were unique in giving rise to the land plant lineage. The cell wall has been suggested to be a defining structure that enabled the green algal ancestor to colonize land. These cell walls provide support and protection, are a source of signalling molecules, and provide developmental cues for cell differentiation and elongation. The cell wall of land plants is a highly complex fibre composite, characterized by cellulose cross-linked by non-cellulosic polysaccharides, such as xyloglucan, embedded in a matrix of pectic polysaccharides. How the land plant cell wall evolved is currently unknown: early-divergent chlorophyte and prasinophyte algae genomes contain a low number of glycosyl transferases (GTs), while land plants contain hundreds. The number of GTs in CGA is currently unknown, as no genomes are available, so this study sought to give insight into the evolution of the biosynthetic machinery of CGA through an analysis of available transcriptomes. Methods Available CGA transcriptomes were mined for cell wall biosynthesis GTs and compared with GTs characterized in land plants. In addition, gene cloning was employed in two cases to answer important evolutionary questions. Key Results Genetic evidence was obtained indicating that many of the most important core cell wall polysaccharides have their evolutionary origins in the CGA, including cellulose, mannan, xyloglucan, xylan and pectin, as well as arabino-galactan protein. Moreover, two putative cellulose synthase-like D family genes (CSLDs) from the CGA species Coleochaete orbicularis and a fragment of a putative CSLA/K-like sequence from a CGA Spirogyra species were cloned, providing the first evidence that all the cellulose synthase/-like genes present in early-divergent land plants were already present in CGA. Conclusions The results provide new insights into the evolution of

  3. Evidence for land plant cell wall biosynthetic mechanisms in charophyte green algae.

    PubMed

    Mikkelsen, Maria D; Harholt, Jesper; Ulvskov, Peter; Johansen, Ida E; Fangel, Jonatan U; Doblin, Monika S; Bacic, Antony; Willats, William G T

    2014-10-01

    The charophyte green algae (CGA) are thought to be the closest living relatives to the land plants, and ancestral CGA were unique in giving rise to the land plant lineage. The cell wall has been suggested to be a defining structure that enabled the green algal ancestor to colonize land. These cell walls provide support and protection, are a source of signalling molecules, and provide developmental cues for cell differentiation and elongation. The cell wall of land plants is a highly complex fibre composite, characterized by cellulose cross-linked by non-cellulosic polysaccharides, such as xyloglucan, embedded in a matrix of pectic polysaccharides. How the land plant cell wall evolved is currently unknown: early-divergent chlorophyte and prasinophyte algae genomes contain a low number of glycosyl transferases (GTs), while land plants contain hundreds. The number of GTs in CGA is currently unknown, as no genomes are available, so this study sought to give insight into the evolution of the biosynthetic machinery of CGA through an analysis of available transcriptomes. Available CGA transcriptomes were mined for cell wall biosynthesis GTs and compared with GTs characterized in land plants. In addition, gene cloning was employed in two cases to answer important evolutionary questions. Genetic evidence was obtained indicating that many of the most important core cell wall polysaccharides have their evolutionary origins in the CGA, including cellulose, mannan, xyloglucan, xylan and pectin, as well as arabino-galactan protein. Moreover, two putative cellulose synthase-like D family genes (CSLDs) from the CGA species Coleochaete orbicularis and a fragment of a putative CSLA/K-like sequence from a CGA Spirogyra species were cloned, providing the first evidence that all the cellulose synthase/-like genes present in early-divergent land plants were already present in CGA. The results provide new insights into the evolution of cell walls and support the notion that the CGA were

  4. Evidence for equal size cell divisions during gametogenesis in a marine green alga Monostroma angicava

    PubMed Central

    Togashi, Tatsuya; Horinouchi, Yusuke; Sasaki, Hironobu; Yoshimura, Jin

    2015-01-01

    In cell divisions, relative size of daughter cells should play fundamental roles in gametogenesis and embryogenesis. Differences in gamete size between the two mating types underlie sexual selection. Size of daughter cells is a key factor to regulate cell divisions during cleavage. In cleavage, the form of cell divisions (equal/unequal in size) determines the developmental fate of each blastomere. However, strict validation of the form of cell divisions is rarely demonstrated. We cannot distinguish between equal and unequal cell divisions by analysing only the mean size of daughter cells, because their means can be the same. In contrast, the dispersion of daughter cell size depends on the forms of cell divisions. Based on this, we show that gametogenesis in the marine green alga, Monostroma angicava, exhibits equal size cell divisions. The variance and the mean of gamete size (volume) of each mating type measured agree closely with the prediction from synchronized equal size cell divisions. Gamete size actually takes only discrete values here. This is a key theoretical assumption made to explain the diversified evolution of isogamy and anisogamy in marine green algae. Our results suggest that germ cells adopt equal size cell divisions during gametogenesis. PMID:26333414

  5. PPR proteins of green algae

    PubMed Central

    Tourasse, Nicolas J; Choquet, Yves; Vallon, Olivier

    2013-01-01

    Using the repeat finding algorithm FT-Rep, we have identified 154 pentatricopeptide repeat (PPR) proteins in nine fully sequenced genomes from green algae (with a total of 1201 repeats) and grouped them in 47 orthologous groups. All data are available in a database, PPRdb, accessible online at http://giavap-genomes.ibpc.fr/ppr. Based on phylogenetic trees generated from the repeats, we propose evolutionary scenarios for PPR proteins. Two PPRs are clearly conserved in the entire green lineage: MRL1 is a stabilization factor for the rbcL mRNA, while HCF152 binds in plants to the psbH-petB intergenic region. MCA1 (the stabilization factor for petA) and PPR7 (a short PPR also acting on chloroplast mRNAs) are conserved across the entire Chlorophyta. The other PPRs are clade-specific, with evidence for gene losses, duplications, and horizontal transfer. In some PPR proteins, an additional domain found at the C terminus provides clues as to possible functions. PPR19 and PPR26 possess a methyltransferase_4 domain suggesting involvement in RNA guanosine methylation. PPR18 contains a C-terminal CBS domain, similar to the CBSPPR1 protein found in nucleoids. PPR16, PPR29, PPR37, and PPR38 harbor a SmR (MutS-related) domain similar to that found in land plants pTAC2, GUN1, and SVR7. The PPR-cyclins PPR3, PPR4, and PPR6, in addition, contain a cyclin domain C-terminal to their SmR domain. PPR31 is an unusual PPR-cyclin containing at its N terminus an OctotricoPeptide Repeat (OPR) and a RAP domain. We consider the possibility that PPR proteins with a SmR domain can introduce single-stranded nicks in the plastid chromosome. PMID:24021981

  6. Experimental evidence that evolutionary relatedness does not affect the ecological mechanisms of coexistence in freshwater green algae.

    PubMed

    Narwani, Anita; Alexandrou, Markos A; Oakley, Todd H; Carroll, Ian T; Cardinale, Bradley J

    2013-11-01

    The coexistence of competing species depends on the balance between their fitness differences, which determine their competitive inequalities, and their niche differences, which stabilise their competitive interactions. Darwin proposed that evolution causes species' niches to diverge, but the influence of evolution on relative fitness differences, and the importance of both niche and fitness differences in determining coexistence have not yet been studied together. We tested whether the phylogenetic distances between species of green freshwater algae determined their abilities to coexist in a microcosm experiment. We found that niche differences were more important in explaining coexistence than relative fitness differences, and that phylogenetic distance had no effect on either coexistence or on the sizes of niche and fitness differences. These results were corroborated by an analysis of the frequency of the co-occurrence of 325 pairwise combinations of algal taxa in > 1100 lakes across North America. Phylogenetic distance may not explain the coexistence of freshwater green algae.

  7. Evidence of Coexistence of C3 and C4 Photosynthetic Pathways in a Green-Tide-Forming Alga, Ulva prolifera

    PubMed Central

    Zhang, Xiaowen; Xu, Dong; Mou, Shanli; Cao, Shaona; Zheng, Zhou; Miao, Jinlai; Ye, Naihao

    2012-01-01

    Ulva prolifera, a typical green-tide-forming alga, can accumulate a large biomass in a relatively short time period, suggesting that photosynthesis in this organism, particularly its carbon fixation pathway, must be very efficient. Green algae are known to generally perform C3 photosynthesis, but recent metabolic labeling and genome sequencing data suggest that they may also perform C4 photosynthesis, so C4 photosynthesis might be more wide-spread than previously anticipated. Both C3 and C4 photosynthesis genes were found in U. prolifera by transcriptome sequencing. We also discovered the key enzymes of C4 metabolism based on functional analysis, such as pyruvate orthophosphate dikinase (PPDK), phosphoenolpyruvate carboxylase (PEPC), and phosphoenolpyruvate carboxykinase (PCK). To investigate whether the alga operates a C4-like pathway, the expression of rbcL and PPDK and their enzyme activities were measured under various forms and intensities of stress (differing levels of salinity, light intensity, and temperature). The expression of rbcL and PPDK and their enzyme activities were higher under adverse circumstances. However, under conditions of desiccation, the expression of rbcL and ribulose-1, 5-biphosphate carboxylase (RuBPCase) activity was lower, whereas that of PPDK was higher. These results suggest that elevated PPDK activity may alter carbon metabolism and lead to a partial operation of C4-type carbon metabolism in U. prolifera, probably contributing to its wide distribution and massive, repeated blooms in the Yellow Sea. PMID:22616009

  8. Evidence of coexistence of C₃ and C₄ photosynthetic pathways in a green-tide-forming alga, Ulva prolifera.

    PubMed

    Xu, Jianfang; Fan, Xiao; Zhang, Xiaowen; Xu, Dong; Mou, Shanli; Cao, Shaona; Zheng, Zhou; Miao, Jinlai; Ye, Naihao

    2012-01-01

    Ulva prolifera, a typical green-tide-forming alga, can accumulate a large biomass in a relatively short time period, suggesting that photosynthesis in this organism, particularly its carbon fixation pathway, must be very efficient. Green algae are known to generally perform C₃ photosynthesis, but recent metabolic labeling and genome sequencing data suggest that they may also perform C₄ photosynthesis, so C₄ photosynthesis might be more wide-spread than previously anticipated. Both C₃ and C₄ photosynthesis genes were found in U. prolifera by transcriptome sequencing. We also discovered the key enzymes of C₄ metabolism based on functional analysis, such as pyruvate orthophosphate dikinase (PPDK), phosphoenolpyruvate carboxylase (PEPC), and phosphoenolpyruvate carboxykinase (PCK). To investigate whether the alga operates a C₄-like pathway, the expression of rbcL and PPDK and their enzyme activities were measured under various forms and intensities of stress (differing levels of salinity, light intensity, and temperature). The expression of rbcL and PPDK and their enzyme activities were higher under adverse circumstances. However, under conditions of desiccation, the expression of rbcL and ribulose-1, 5-biphosphate carboxylase (RuBPCase) activity was lower, whereas that of PPDK was higher. These results suggest that elevated PPDK activity may alter carbon metabolism and lead to a partial operation of C₄-type carbon metabolism in U. prolifera, probably contributing to its wide distribution and massive, repeated blooms in the Yellow Sea.

  9. Deep Transcriptome Sequencing of Two Green Algae, Chara vulgaris and Chlamydomonas reinhardtii, Provides No Evidence of Organellar RNA Editing

    PubMed Central

    Cahoon, A. Bruce; Nauss, John A.; Stanley, Conner D.; Qureshi, Ali

    2017-01-01

    Nearly all land plants post-transcriptionally modify specific nucleotides within RNAs, a process known as RNA editing. This adaptation allows the correction of deleterious mutations within the asexually reproducing and presumably non-recombinant chloroplast and mitochondrial genomes. There are no reports of RNA editing in any of the green algae so this phenomenon is presumed to have originated in embryophytes either after the invasion of land or in the now extinct algal ancestor of all land plants. This was challenged when a recent in silico screen for RNA edit sites based on genomic sequence homology predicted edit sites in the green alga Chara vulgaris, a multicellular alga found within the Streptophyta clade and one of the closest extant algal relatives of land plants. In this study, the organelle transcriptomes of C. vulgaris and Chlamydomonas reinhardtii were deep sequenced for a comprehensive assessment of RNA editing. Initial analyses based solely on sequence comparisons suggested potential edit sites in both species, but subsequent high-resolution melt analysis, RNase H-dependent PCR (rhPCR), and Sanger sequencing of DNA and complementary DNAs (cDNAs) from each of the putative edit sites revealed them to be either single-nucleotide polymorphisms (SNPs) or spurious deep sequencing results. The lack of RNA editing in these two lineages is consistent with the current hypothesis that RNA editing evolved after embryophytes split from its ancestral algal lineage. PMID:28230734

  10. Effect of ferrate on green algae removal.

    PubMed

    Kubiňáková, Emília; Híveš, Ján; Gál, Miroslav; Fašková, Andrea

    2017-08-05

    Green algae Cladophora aegagropila, present in cooling water of thermal power plants, causes many problems and complications, especially during summer. However, algae and its metabolites are rarely eliminated by common removal methods. In this work, the elimination efficiency of electrochemically prepared potassium ferrate(VI) on algae from cooling water was investigated. The influence of experimental parameters, such as Fe(VI) dosage, application time, pH of the system, temperature and hydrodynamics of the solution on removal efficiency, was optimized. This study demonstrates that algae C. aegagropila can be effectively removed from cooling water by ferrate. Application of ferrate(VI) at the optimized dosage and under the suitable conditions (temperature, pH) leads to 100% removal of green algae Cladophora from the system. Environmentally friendly reduction products (Fe(III)) and coagulation properties favour the application of ferrate for the treatment of water contaminated with studied microorganisms compared to other methods such as chlorination and use of permanganate, where harmful products are produced.

  11. Hydrogen production by photosynthetic green algae.

    PubMed

    Ghirardi, Maria L

    2006-08-01

    Oxygenic photosynthetic organisms such as cyanobacteria, green algae and diatoms are capable of absorbing light and storing up to 10-13% of its energy into the H-H bond of hydrogen gas. This process, which takes advantage of the photosynthetic apparatus of these organisms to convert sunlight into chemical energy, could conceivably be harnessed for production of significant amounts of energy from a renewable resource, water. The harnessed energy could then be coupled to a fuel cell for electricity generation and recycling of water molecules. In this review, current biochemical understanding of this reaction in green algae, and some of the major challenges facing the development of future commercial algal photobiological systems for H2 production have been discussed.

  12. The problems of Prochloron. [evolution of green algae

    NASA Technical Reports Server (NTRS)

    Lewin, R. A.

    1983-01-01

    Prokaryotic green algae (prochlorophytes), which contain chlorophylls a and b but no bilin pigments, may be phylogenetically related to ancestral chloroplasts if symbiogenesis occurred. They may be otherwise related to eukaryotic chlorophytes. They could have evolved from cyanophytes by loss of phycobilin and gain of chlorophyll b synthesis. These possibilities are briefly discussed. Relevant evidence from biochemical studies in many collaborative laboratories is now becoming available for the resolution of such questions.

  13. The problems of Prochloron. [evolution of green algae

    NASA Technical Reports Server (NTRS)

    Lewin, R. A.

    1983-01-01

    Prokaryotic green algae (prochlorophytes), which contain chlorophylls a and b but no bilin pigments, may be phylogenetically related to ancestral chloroplasts if symbiogenesis occurred. They may be otherwise related to eukaryotic chlorophytes. They could have evolved from cyanophytes by loss of phycobilin and gain of chlorophyll b synthesis. These possibilities are briefly discussed. Relevant evidence from biochemical studies in many collaborative laboratories is now becoming available for the resolution of such questions.

  14. Comparison of plastid 16S rRNA (rrn16) genes from Helicosporidium spp.: evidence supporting the reclassification of Helicosporidia as green algae (Chlorophyta).

    PubMed

    Tartar, Aurélien; Boucias, Drion G; Becnel, James J; Adams, Byron J

    2003-11-01

    The Helicosporidia are invertebrate pathogens that have recently been identified as non-photosynthetic green algae (Chlorophyta). In order to confirm the algal nature of the genus Helicosporidium, the presence of a retained chloroplast genome in Helicosporidia cells was investigated. Fragments homologous to plastid 16S rRNA (rrn16) genes were amplified successfully from cellular DNA extracted from two different Helicosporidium isolates. The fragment sequences are 1269 and 1266 bp long, are very AT-rich (60.7 %) and are similar to homologous genes sequenced from non-photosynthetic green algae. Maximum-parsimony, maximum-likelihood and neighbour-joining methods were used to infer phylogenetic trees from an rrn16 sequence alignment. All trees depicted the Helicosporidia as sister taxa to the non-photosynthetic, pathogenic alga Prototheca zopfii. Moreover, the trees identified Helicosporidium spp. as members of a clade that included the heterotrophic species Prototheca spp. and the mesotrophic species Chlorella protothecoides. The clade is always strongly supported by bootstrap values, suggesting that all these organisms share a most recent common ancestor. Phylogenetic analyses inferred from plastid 16S rRNA genes confirmed that the Helicosporidia are non-photosynthetic green algae, close relatives of the genus Prototheca (Chlorophyta, Trebouxiophyceae). Such phylogenetic affinities suggest that Helicosporidium spp. are likely to possess Prototheca-like organelles and organelle genomes.

  15. [Allelopathic effect of artemisinin on green algae].

    PubMed

    Wu, Ye-Kuan; Yuan, Ling; Huang, Jian-Guo; Li, Long-Yun

    2013-05-01

    To study the growth effects of differing concentrations of artemisinin on green algae and to evaluate the ecological risk. The effects of artemisinin on the growth and the content change of chlorophyll, protein, oxygen, conductivity, SOD, CAT, MDA in Chlorella pyrenoidosa and Scenedesmus oblique were studied through 96 h toxicity tests. Artemisinin accelerated the growth of algae at a lower concentration ( <40 microg . L-1) with content increase of chlorophyll or protein and so on, and it inhibited the growth of algae at higher concentration ( >80 microg . L-1). The content of chlorophyll or protein in algae cells reduced with the increasing concentration of artemisinin, exhibiting the good concentration-effect relationship. SOD and CAT activity was stimulated at low concentrations ( <40 microg . L-1 ) and inhibited at high concentrations ( >80 microg . L- 1). However, MDA content increased significantly with the increase of concentration. According to the seven kinds of indicators changes, the time-response and dose-response suggested that the surfactant first hurt in Ch. pyrenoidosa was damaging membrane by changing membrane lipid molecules soluble. And primary mechanism on Chlorophyta cells might be related to the oxidation damage of lipid and other biological large molecules caused by artemisinin. The large-scale intensive planting of Artemisia annua may reduce the surrounding water productivity.

  16. Chloroplast Phylogenomic Inference of Green Algae Relationships.

    PubMed

    Sun, Linhua; Fang, Ling; Zhang, Zhenhua; Chang, Xin; Penny, David; Zhong, Bojian

    2016-02-05

    The green algal phylum Chlorophyta has six diverse classes, but the phylogenetic relationship of the classes within Chlorophyta remains uncertain. In order to better understand the ancient Chlorophyta evolution, we have applied a site pattern sorting method to study compositional heterogeneity and the model fit in the green algal chloroplast genomic data. We show that the fastest-evolving sites are significantly correlated with among-site compositional heterogeneity, and these sites have a much poorer fit to the evolutionary model. Our phylogenomic analyses suggest that the class Chlorophyceae is a monophyletic group, and the classes Ulvophyceae, Trebouxiophyceae and Prasinophyceae are non-monophyletic groups. Our proposed phylogenetic tree of Chlorophyta will offer new insights to investigate ancient green algae evolution, and our analytical framework will provide a useful approach for evaluating and mitigating the potential errors of phylogenomic inferences.

  17. Chloroplast Phylogenomic Inference of Green Algae Relationships

    PubMed Central

    Sun, Linhua; Fang, Ling; Zhang, Zhenhua; Chang, Xin; Penny, David; Zhong, Bojian

    2016-01-01

    The green algal phylum Chlorophyta has six diverse classes, but the phylogenetic relationship of the classes within Chlorophyta remains uncertain. In order to better understand the ancient Chlorophyta evolution, we have applied a site pattern sorting method to study compositional heterogeneity and the model fit in the green algal chloroplast genomic data. We show that the fastest-evolving sites are significantly correlated with among-site compositional heterogeneity, and these sites have a much poorer fit to the evolutionary model. Our phylogenomic analyses suggest that the class Chlorophyceae is a monophyletic group, and the classes Ulvophyceae, Trebouxiophyceae and Prasinophyceae are non-monophyletic groups. Our proposed phylogenetic tree of Chlorophyta will offer new insights to investigate ancient green algae evolution, and our analytical framework will provide a useful approach for evaluating and mitigating the potential errors of phylogenomic inferences. PMID:26846729

  18. Freshwater Cyanobacteria (Blue-Green Algae) Toxins: Isolation and Characterization

    DTIC Science & Technology

    1990-05-01

    division Cyanophyta , commonly called blue -green algae cr cyanobacteria . Although cyanobacteria are found in almost any environment ranging from hot...p ecst Available Copy ~’ COPy Ni AD FRESHWATER CYANOBACTERIA ( BLUE -GREEN ALGAE ) TOXINS:’ I ISOLATION AND CHARACTERIZATION < DTIC ANNUAL/FINAL...AA I 78 11. TITLE (In•.ju . ’,curry Ci.si fication) Freshwater Cyanobacteria ( blue -green algae ) Toxins: Isolatior and CharacteriZation 12. PERSONAL

  19. Freshwater Cyanobacteria (Blue-Green Algae) Toxins: Isolation and Characterization

    DTIC Science & Technology

    1989-01-15

    exclusively caused by strains of species that are members of the L division Cyanophyta , commonly called blue -green algae or cyanobacteria . Although...0 0 Lfl (NAD FRESHWATER CYANOBACTERIA ( BLUE -GREEN ALGAE ) TOXINS: ISOLATION AND CHARACTERIZATION ANNCUAL REPORT Wayne W. Carmichael Sarojini Bose...Frederick, Maryland 21701-5012 62770A 6277GA871 AA 378 11 TITLE &who* Secwn~y C11mrfaon) Freshwater Cyanobacteria ( blue -green algae ) Toxins: Isolation

  20. Antibody Production in Plants and Green Algae.

    PubMed

    Yusibov, Vidadi; Kushnir, Natasha; Streatfield, Stephen J

    2016-04-29

    Monoclonal antibodies (mAbs) have a wide range of modern applications, including research, diagnostic, therapeutic, and industrial uses. Market demand for mAbs is high and continues to grow. Although mammalian systems, which currently dominate the biomanufacturing industry, produce effective and safe recombinant mAbs, they have a limited manufacturing capacity and high costs. Bacteria, yeast, and insect cell systems are highly scalable and cost effective but vary in their ability to produce appropriate posttranslationally modified mAbs. Plants and green algae are emerging as promising production platforms because of their time and cost efficiencies, scalability, lack of mammalian pathogens, and eukaryotic posttranslational protein modification machinery. So far, plant- and algae-derived mAbs have been produced predominantly as candidate therapeutics for infectious diseases and cancer. These candidates have been extensively evaluated in animal models, and some have shown efficacy in clinical trials. Here, we review ongoing efforts to advance the production of mAbs in plants and algae.

  1. Evidence for a light-induced H(+) conductance in the eye of the green alga Chlamydomonas reinhardtii.

    PubMed

    Ehlenbeck, Sabine; Gradmann, Dietrich; Braun, Franz-Josef; Hegemann, Peter

    2002-02-01

    Rhodopsin-mediated photoreceptor currents, I(P), of the unicellular alga Chlamydomonas reinhardtii were studied under neutral and acidic conditions. We characterized the kinetically overlapping components of the first, flash-induced inward current recorded from the eye, I(P1), as a low- and high-intensity component, I(P1a) and I(P1b), respectively. They peak between 1 and 10 ms after the light-flash and are both likely to be carried by Ca(2+). I(P1a) and I(P1b) exhibit half-maximal photon flux densities, Q(1/2), of approximately 0.14 and 58 microE m(-2), and maximal amplitudes of approximately 4.9 and 38 pA, respectively. At acidic extracellular pH values (pH 3-5), both I(P1) currents are followed by distinct H(+) currents, I(P2a) and I(P2b), with maxima after approximately 5 and 100 ms, respectively. Because the Q(1/2) values of I(P1b) and I(P2b) virtually coincide with Q(1/2) of rhodopsin bleaching, we suggest that the respective conductances G(1b) and G(2b) are closely coupled to the rhodopsin, whereas the low light-saturating conductances G(1a) and G(2a) reflect transducer-activated states of a second rhodopsin photoreceptor system.

  2. Sterols from the Green Alga Ulva australis.

    PubMed

    Li, Guo-Liang; Guo, Wei-Jie; Wang, Guang-Bao; Wang, Rong-Rong; Hou, Yu-Xue; Liu, Kun; Liu, Yang; Wang, Wei

    2017-09-28

    Three new sterols, (24R)-5,28-stigmastadiene-3β,24-diol-7-one (1), (24S)-5,28-stigmastadiene-3β,24-diol-7-one (2), and 24R and 24S-vinylcholesta-3β,5α,6β,24-tetraol (3), together with three known sterols (4-6) were isolated from the green alga Ulva australis. The structures of the new compounds (1-3) were elucidated through 1D and 2D nuclear magnetic resonance spectroscopy as well as mass spectrometry. Compounds 4-6 were identified as isofucoterol (4), 24R,28S and 24S,28R-epoxy-24-ethylcholesterol (5), and (24S)-stigmastadiene-3β,24-diol (6) on the basis of spectroscopic data analyses and comparison with those reported in the literature. Compounds 4-6 were isolated from U. australis for the first time. These compounds, together with the previously isolated secondary metabolites of this alga, were investigated for their inhibitory effects on human recombinant aldose reductase in vitro. Of the compounds, 24R,28S and 24S,28R-epoxy-24-ethylcholesterol (5), 1-O-palmitoyl-3-O-(6'-sulfo-α-d-quinovopyranosyl) glycerol, (2S)-1-O-palmitoyl-3-O-[α-d-galactopyranosyl(1→2)β-d-galactopyranosyl] glycerol, 4-hydroxybenzoic acid, 4-hydroxyphenylacetic acid, and 8-hydroxy-(6E)-octenoic acid weakly inhibited the enzyme, while the three new sterols, 1-3, were almost inactive.

  3. Shared ancestry influences community stability by altering competitive interactions: evidence from a laboratory microcosm experiment using freshwater green algae.

    PubMed

    Venail, Patrick A; Alexandrou, Markos A; Oakley, Todd H; Cardinale, Bradley J

    2013-10-07

    The impact of biodiversity on the stability of ecological communities has been debated among biologists for more than a century. Recently summarized empirical evidence suggests that biodiversity tends to enhance the temporal stability of community-level properties such as biomass; however, the underlying mechanisms driving this relationship remain poorly understood. Here, we report the results of a microcosm study in which we used simplified systems of freshwater microalgae to explore how the phylogenetic relatedness of species influences the temporal stability of community biomass by altering the nature of their competitive interactions. We show that combinations of two species that are more evolutionarily divergent tend to have lower temporal stability of biomass. In part, this is due to negative 'selection effects' in which bicultures composed of distantly related species are more likely to contain strong competitors that achieve low biomass. In addition, bicultures of distantly related species had on average weaker competitive interactions, which reduced compensatory dynamics and decreased the stability of community biomass. Our results demonstrate that evolutionary history plays a key role in controlling the mechanisms, which give rise to diversity-stability relationships. As such, patterns of shared ancestry may help us predict the ecosystem-level consequences of biodiversity loss.

  4. Shared ancestry influences community stability by altering competitive interactions: evidence from a laboratory microcosm experiment using freshwater green algae

    PubMed Central

    Venail, Patrick A.; Alexandrou, Markos A.; Oakley, Todd H.; Cardinale, Bradley J.

    2013-01-01

    The impact of biodiversity on the stability of ecological communities has been debated among biologists for more than a century. Recently summarized empirical evidence suggests that biodiversity tends to enhance the temporal stability of community-level properties such as biomass; however, the underlying mechanisms driving this relationship remain poorly understood. Here, we report the results of a microcosm study in which we used simplified systems of freshwater microalgae to explore how the phylogenetic relatedness of species influences the temporal stability of community biomass by altering the nature of their competitive interactions. We show that combinations of two species that are more evolutionarily divergent tend to have lower temporal stability of biomass. In part, this is due to negative ‘selection effects’ in which bicultures composed of distantly related species are more likely to contain strong competitors that achieve low biomass. In addition, bicultures of distantly related species had on average weaker competitive interactions, which reduced compensatory dynamics and decreased the stability of community biomass. Our results demonstrate that evolutionary history plays a key role in controlling the mechanisms, which give rise to diversity–stability relationships. As such, patterns of shared ancestry may help us predict the ecosystem-level consequences of biodiversity loss. PMID:23945692

  5. Evidence for a facultative mutualist nutritional relationship between the green coccoid alga Bracteacoccus sp. (Chlorophyceae) and the zoosporic fungus Rhizidium phycophilum (Chytridiomycota).

    PubMed

    Picard, Kathryn T; Letcher, Peter M; Powell, Martha J

    2013-05-01

    Symbiotic interactions between fungi and photosynthetic partners are common among derived fungal lineages. The only fungal-phototroph interactions thus far reported from the early diverging zoosporic fungi are parasitic in nature. Rhizidium phycophilum is a terrestrial, saprotrophic chytrid, which appears to be able to enter a facultative mutualism with a coccoid green alga in the absence of refractory organic material, such as pollen and chitin. Liquid and solid culturing methods were used in a series of differential fitness experiments in conjunction with microscopic analyses to characterize the interaction between R. phycophilum and the alga. The alga in this partnership is identified as a member of the genus Bracteacoccus. Under certain culturing conditions, algal cells grown in coculture with R. phycophilum were shown to grow larger and more prolifically than when cultured axenically under the same conditions. Additionally, dialysis experiments demonstrate that R. phycophilum does not parasitize Bracteacoccus sp., and can be cultured in media infused with unknown algal exudates. Rhizidium phycophilum and Bracteacoccus sp. represent the first facultative positive interaction between a zoosporic fungus and a photoautotroph and may prove a tractable system for modelling interactions between early fungi and plants. Copyright © 2013 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.

  6. Phosphorus-limited growth of a green alga and a blue-green alga

    SciTech Connect

    Lang, D.S.; Brown, E.J.

    1981-12-01

    The phosphorus-limited growth kinetics of the chlorophyte Scenedesmus quadricauda and the cyanophyte Synechococcus Nageli were studied by using batch and continuous culturing techniques. The steady-state phosphate transport capability and the phosphorus storage capacity is higher in S. Nageli than in S. quadricauda. Synechococcus Nageli can also deplete phosphate to much lower levels than can S. quadricauda. These results, along with their morphological characteristics, were used to construct partial physiological profiles for each organism. The profiles indicate that this unicellular cyanophyte (cyanobacterium) is better suited for growth in phosphorus-limited oligotrophic niches than is this chlorophyte (green alga). (Refs. 44).

  7. Phosphorus-Limited Growth of a Green Alga and a Blue-Green Alga

    PubMed Central

    Lang, Douglas S.; Brown, Edward J.

    1981-01-01

    The phosphorus-limited growth kinetics of the chlorophyte Scenedesmus quadricauda and the cyanophyte Synechococcus Nägeli were studied by using batch and continuous culturing techniques. The steady-state phosphate transport capability and the phosphorus storage capacity is higher in S. Nägeli than in S. quadricauda. Synechococcus Nägeli can also deplete phosphate to much lower levels than can S. quadricauda. These results, along with their morphological characteristics, were used to construct partial physiological profiles for each organism. The profiles indicate that this unicellular cyanophyte (cyanobacterium) is better suited for growth in phosphorus-limited oligotrophic niches than is this chlorophyte (green alga). PMID:16345896

  8. Effects of zinc oxide and titanium dioxide nanoparticles on green algae under visible, UVA, and UVB irradiations: no evidence of enhanced algal toxicity under UV pre-irradiation.

    PubMed

    Lee, Woo-Mi; An, Youn-Joo

    2013-04-01

    Some metal oxide nanoparticles are photoreactive, thus raising concerns regarding phototoxicity. This study evaluated ecotoxic effects of zinc oxide nanoparticles and titanium dioxide nanoparticles to the green algae Pseudokirchneriella subcapitata under visible, UVA, and UVB irradiation conditions. The nanoparticles were prepared in algal test medium, and the test units were pre-irradiated by UV light in a photoreactor. Algal assays were also conducted with visible, UVA or UVB lights only without nanoparticles. Algal growth was found to be inhibited as the nanoparticle concentration increased, and ZnO NPs caused destabilization of the cell membranes. We also noted that the inhibitory effects on the growth of algae were not enhanced under UV pre-irradiation conditions. This phenomenon was attributed to the photocatalytic activities of ZnO NPs and TiO2 NPs in both the visible and UV regions. The toxicity of ZnO NPs was almost entirely the consequence of the dissolved free zinc ions. This study provides us with an improved understanding of toxicity of photoreactive nanoparticles as related to the effects of visible and UV lights.

  9. Phycobiliproteins: A Novel Green Tool from Marine Origin Blue-Green Algae and Red Algae.

    PubMed

    Chandra, Rashmi; Parra, Roberto; Iqbal, Hafiz M N

    2017-01-01

    Marine species are comprising about a half of the whole global biodiversity; the sea offers an enormous resource for novel bioactive compounds. Several of the marine origin species show multifunctional bioactivities and characteristics that are useful for a discovery and/or reinvention of biologically active compounds. For millennia, marine species that includes cyanobacteria (blue-green algae) and red algae have been targeted to explore their enormous potential candidature status along with a wider spectrum of novel applications in bio- and non-bio sectors of the modern world. Among them, cyanobacteria are photosynthetic prokaryotes, phylogenetically a primitive group of Gramnegative prokaryotes, ranging from Arctic to Antarctic regions, capable of carrying out photosynthesis and nitrogen fixation. In the recent decade, a great deal of research attention has been paid on the pronouncement of bio-functional proteins along with novel peptides, vitamins, fine chemicals, renewable fuel and bioactive compounds, e.g., phycobiliproteins from marine species, cyanobacteria and red algae. Interestingly, they are extensively commercialized for natural colorants in food and cosmetics, antimicrobial, antioxidant, anti-inflammatory, neuroprotective, hepatoprotective agents and fluorescent neo-glycoproteins as probes for single particle fluorescence imaging fluorescent applications in clinical and immunological analysis. However, a comprehensive knowledge and technological base for augmenting their commercial utilities are lacking. Therefore, this paper will provide an overview of the phycobiliproteins-based research literature from marine cyanobacteria and red algae. This review is also focused towards analyzing global and commercial activities with application oriented-based research. Towards the end, the information is also given on the potential biotechnological and biomedical applications of phycobiliproteins. Copyright© Bentham Science Publishers; For any queries, please

  10. The Chloroplast Genome of the Green Alga Schizomeris leibleinii (Chlorophyceae) Provides Evidence for Bidirectional DNA Replication from a Single Origin in the Chaetophorales

    PubMed Central

    Brouard, Jean-Simon; Otis, Christian; Lemieux, Claude; Turmel, Monique

    2011-01-01

    In the Chlorophyceae, the chloroplast genome is extraordinarily fluid in architecture and displays unique features relative to other groups of green algae. For the Chaetophorales, 1 of the 5 major lineages of the Chlorophyceae, it has been shown that the distinctive architecture of the 223,902-bp genome of Stigeoclonium helveticum is consistent with bidirectional DNA replication from a single origin. Here, we report the 182,759-bp chloroplast genome sequence of Schizomeris leibleinii, a member of the earliest diverging lineage of the Chaetophorales. Like its Stigeoclonium homolog, the Schizomeris genome lacks a large inverted repeat encoding the rRNA operon and displays a striking bias in coding regions that is associated with a bias in base composition along each strand. Our results support the notion that these two chaetophoralean genomes replicate bidirectionally from a putative origin located in the vicinity of the small subunit ribosomal RNA gene. Their shared structural characteristics were most probably inherited from the common ancestor of all chaetophoralean algae. Short dispersed repeats account for most of the 41-kb size variation between the Schizomeris and Stigeoclonium genomes, and there is no indication that homologous recombination between these repeated elements led to the observed gene rearrangements. A comparison of the extent of variation sustained by the Stigeoclonium and Schizomeris chloroplast DNAs (cpDNAs) with that observed for the cpDNAs of the chlamydomonadalean Chlamydomonas and Volvox suggests that gene rearrangements as well as changes in the abundance of intergenic and intron sequences occurred at a slower pace in the Chaetophorales than in the Chlamydomonadales. PMID:21546564

  11. Inhibition of green algae growth by corrole-based photosensitizers.

    PubMed

    Pohl, J; Saltsman, I; Mahammed, A; Gross, Z; Röder, B

    2015-02-01

    This study was performed to examine the potential of photodynamic inactivation for growth inhibition of green algae through generation of singlet oxygen. Two cationic and two anionic corroles were investigated according to their photoinhibitive effect on two strains of green algae using visible light for photoexcitation. The development of biomass over the experimental period of 18 days was followed using absorptive properties of the algae samples. The anionic photosensitizers showed no significant phototoxicity, whereas the cationic photosensitizers caused a drastic reduction of biomass on a short time scale and also displayed long-term inhibition of algae growth. In general, it was proven that photodynamic inactivation of green algae is possible. Concluding from the results of this study, cationic photosensitizers are favourable for this task, while anionic photosensitizers are not suited. Phototrophic biofilms are an important factor in biofouling and biodeterioration of building materials, causing great damage to historic and contemporary constructions. Growth inhibition of phototrophic organisms using photodynamic inactivation could pose an alternative to the use of biocides. To this end, successful application of this approach on green algae is a vital step in the development of suitable photosensitizers. © 2014 The Society for Applied Microbiology.

  12. Hyperspectral imaging of snow algae and green algae from aeroterrestrial habitats.

    PubMed

    Holzinger, Andreas; Allen, Michael C; Deheyn, Dimitri D

    2016-09-01

    Snow algae and green algae living in aeroterrestrial habitats are ideal objects to study adaptation to high light irradiation. Here, we used a detailed description of the spectral properties as a proxy for photo-acclimation/protection in snow algae (Chlamydomonas nivalis, Chlainomonas sp. and Chloromonas sp.) and charophyte green algae (Zygnema sp., Zygogonium ericetorum and Klebsormidium crenulatum). The hyperspectral microscopic mapping and imaging technique allowed us to acquire total absorption spectra of these microalgae in the waveband of 400-900nm. Particularly in Chlamydomonas nivalis and Chlainomonas sp., a high absorbance between 400-550nm was observed, due to naturally occurring secondary carotenoids; in Chloromonas sp. and in the charopyhte algae this high absorbance was missing, the latter being close relatives to land plants. To investigate if cellular water loss has an influence on the spectral properties, the cells were plasmolysed in sorbitol or desiccated at ambient air. While in snow algae, these treatments did hardly change the spectral properties, in the charopyhte algae the condensation of the cytoplasm and plastids increased the absorbance in the lower waveband of 400-500nm. These changes might be ecologically relevant and photoprotective, as aeroterrestrial algae are naturally exposed to occasional water limitation, leading to desiccation, which are conditions usually occurring together with higher irradiation.

  13. Hyperspectral imaging of snow algae and green algae from aeroterrestrial habitats

    PubMed Central

    Holzinger, Andreas; Allen, Michael C.; Deheyn, Dimitri D.

    2016-01-01

    Snow algae and green algae living in aeroterrestrial habitats are ideal obbjects to study adaptation to high light irradiation. Here, we used a detailed description of the spectral properties as a proxy for photo-acclimation/protection in snow algae (Chlamydomonas nivalis, Chlainomonas sp. and Chloromonas sp.) and charopyhte green algae (Zygnema sp., Zygogonium ericetorum and Klebsormidium crenulatum). The hyperspectral microscopic mapping and imaging technique allowed us to acquire total absorbance spectra of these microalgae in the waveband of 400-900 nm. Particularly in Chlamydomonas nivalis and Chlainomonas sp., a high absorbance in the wave band of 400-550 nm was observed, due to naturally occurring secondary carotenoids; in Chloromonas sp. and in the charopyhte algae this was missing, the latter being close relatives to land plants. To investigate if cellular water loss has an influence on the spectral properties, the cells were plasmolysed in sorbitol or desiccated at ambient air. While in snow algae, these treatments did not change the spectral properties, in the charopyhte algae the condensation of the cytoplasm and plastids increased the absorbance in the lower waveband of 400 – 500 nm. These changes might be ecologically relevant and photoprotective, as aeroterrestrial algae are naturally exposed to occasional water limitation, leading to desiccation, which are conditions usually occurring together with higher irradiation. PMID:27442511

  14. Evaluation of filamentous green algae as feedstocks for biofuel production.

    PubMed

    Zhang, Wei; Zhao, Yonggang; Cui, Binjie; Wang, Hui; Liu, Tianzhong

    2016-11-01

    Compared with unicellular microalgae, filamentous algae have high resistance to grazer-predation and low-cost recovery in large-scale production. Green algae, as the most diverse group of algae, included numerous filamentous genera and species. In this study, records of filamentous genera and species in green algae were firstly censused and classified. Then, seven filamentous strains subordinated in different genera were cultivated in bubbled-column to investigate their growth rate and energy molecular (lipid and starch) capacity. Four strains including Stigeoclonium sp., Oedogonium nodulosum, Hormidium sp. and Zygnema extenue were screened out due to their robust growth. And they all could accumulate triacylglycerols and starch in their biomass, but with different capacity. After nitrogen starvation, Hormidium sp. and Oedogonium nodulosum respectively exhibited high capacity of lipid (45.38% in dry weight) and starch (46.19% in dry weight) accumulation, which could be of high potential as feedstocks for biodiesel and bioethanol production.

  15. Photosynthetic recovery following desiccation of desert green algae (Chlorophyta) and their aquatic relatives.

    PubMed

    Gray, Dennis W; Lewis, Louise A; Cardon, Zoe G

    2007-10-01

    Recent molecular data suggest that desert green algae have evolved from freshwater ancestors at least 14 times in three major classes (Chlorophyceae, Trebouxiophyceae and Charophyceae), offering a unique opportunity to study the adaptation of photosynthetic organisms to life on land in a comparative phylogenetic framework. We examined the photorecovery of phylogenetically matched desert and aquatic algae after desiccation in darkness and under illumination. Desert algae survived desiccation for at least 4 weeks when dried in darkness, and recovered high levels of photosynthetic quantum yield within 1 h of rehydration in darkness. However, when 4 weeks of desiccation was accompanied by illumination, three of six desert taxa lost their ability to recover quantum yield during rehydration in the dark. Aquatic algae, in contrast, recovered very little during dark rehydration following even just 24 h of desiccation. Re-illuminating rehydrated algae produced a nearly complete recovery of quantum yield in all desert and two of five aquatic taxa. These contrasts provide physiological evidence that desert green algae possess mechanisms for photosynthetic recovery after desiccation distinct from those in aquatic relatives, corroborating molecular evidence that they are not happenstance, short-term visitors from aquatic environments. Photosensitivity during desiccation among desert algae further suggests that they may reside in protected microsites within crusts, and species specificity of photosensitivity suggests that disturbances physically disrupting crusts could lead to shifts or losses of taxonomic diversity within these habitats.

  16. A pyruvate formate lyase-deficient Chlamydomonas reinhardtii strain provides evidence for a link between fermentation and hydrogen production in green algae.

    PubMed

    Philipps, Gabriele; Krawietz, Danuta; Hemschemeier, Anja; Happe, Thomas

    2011-04-01

    The green alga Chlamydomonas reinhardtii has a complex anaerobic metabolism characterized by a plastidic hydrogenase (HYD1) coupled to photosynthesis and a bacterial-type fermentation system in which pyruvate formate lyase (PFL1) is the central fermentative enzyme. To identify mutant strains with altered hydrogen metabolism, a C. reinhardtii nuclear transformant library was screened. Mutant strain 48F5 showed lower light-dependent hydrogen (H₂) evolution rates and reduced in vitro hydrogenase activity, and fermentative H₂ production in the dark was enhanced. The transformant has a single integration of the paromomycin resistance cassette within the PFL1 gene, and is unable to synthesize PFL1 protein. 48F5 secretes no formate, but produces more ethanol, D-lactate and CO₂ than the wild type. Moreover, HYD1 transcript and HYD1 protein levels were lower in the pfl1 mutant strain. Complementation of strain 48F5 with an intact copy of the PFL1 gene restored formate excretion and hydrogenase activity to the wild type level. This analysis shows that the PFL1 pathway has a significant impact on hydrogen metabolism in C. reinhardtii. © 2011 The Authors. The Plant Journal © 2011 Blackwell Publishing Ltd.

  17. Carbon Partitioning in Green Algae (Chlorophyta) and the Enolase Enzyme

    PubMed Central

    Polle, Jürgen E. W.; Neofotis, Peter; Huang, Andy; Chang, William; Sury, Kiran; Wiech, Eliza M.

    2014-01-01

    The exact mechanisms underlying the distribution of fixed carbon within photoautotrophic cells, also referred to as carbon partitioning, and the subcellular localization of many enzymes involved in carbon metabolism are still unknown. In contrast to the majority of investigated green algae, higher plants have multiple isoforms of the glycolytic enolase enzyme, which are differentially regulated in higher plants. Here we report on the number of gene copies coding for the enolase in several genomes of species spanning the major classes of green algae. Our genomic analysis of several green algae revealed the presence of only one gene coding for a glycolytic enolase [EC 4.2.1.11]. Our predicted cytosolic localization would require export of organic carbon from the plastid to provide substrate for the enolase and subsequent re-import of organic carbon back into the plastids. Further, our comparative sequence study of the enolase and its 3D-structure prediction may suggest that the N-terminal extension found in green algal enolases could be involved in regulation of the enolase activity. In summary, we propose that the enolase represents one of the crucial regulatory bottlenecks in carbon partitioning in green algae. PMID:25093929

  18. Carbon partitioning in green algae (chlorophyta) and the enolase enzyme.

    PubMed

    Polle, Jürgen E W; Neofotis, Peter; Huang, Andy; Chang, William; Sury, Kiran; Wiech, Eliza M

    2014-08-04

    The exact mechanisms underlying the distribution of fixed carbon within photoautotrophic cells, also referred to as carbon partitioning, and the subcellular localization of many enzymes involved in carbon metabolism are still unknown. In contrast to the majority of investigated green algae, higher plants have multiple isoforms of the glycolytic enolase enzyme, which are differentially regulated in higher plants. Here we report on the number of gene copies coding for the enolase in several genomes of species spanning the major classes of green algae. Our genomic analysis of several green algae revealed the presence of only one gene coding for a glycolytic enolase [EC 4.2.1.11]. Our predicted cytosolic localization would require export of organic carbon from the plastid to provide substrate for the enolase and subsequent re-import of organic carbon back into the plastids. Further, our comparative sequence study of the enolase and its 3D-structure prediction may suggest that the N-terminal extension found in green algal enolases could be involved in regulation of the enolase activity. In summary, we propose that the enolase represents one of the crucial regulatory bottlenecks in carbon partitioning in green algae.

  19. MicroRNAs in a multicellular green alga Volvox carteri.

    PubMed

    Li, Jingrui; Wu, Yang; Qi, Yijun

    2014-01-01

    microRNAs (miRNAs) have emerged as key components in the eukaryotic gene regulatory network. We and others have previously identified many miRNAs in a unicellular green alga, Chlamydomonas reinhardtii. To investigate whether miRNA-mediated gene regulation is a general mechanism in green algae and how miRNAs have been evolved in the green algal lineage, we examined small RNAs in Volvox carteri, a multicellular species in the same family with Chlamydomonas reinhardtii. We identified 174 miRNAs in Volvox, with many of them being highly enriched in gonidia or somatic cells. The targets of the miRNAs were predicted and many of them were subjected to miRNA-mediated cleavage in vivo, suggesting that miRNAs play regulatory roles in the biology of green algae. Our catalog of miRNAs and their targets provides a resource for further studies on the evolution, biological functions, and genomic properties of miRNAs in green algae.

  20. Development of Green Fuels From Algae - The University of Tulsa

    SciTech Connect

    Crunkleton, Daniel; Price, Geoffrey; Johannes, Tyler; Cremaschi, Selen

    2012-12-03

    The general public has become increasingly aware of the pitfalls encountered with the continued reliance on fossil fuels in the industrialized world. In response, the scientific community is in the process of developing non-fossil fuel technologies that can supply adequate energy while also being environmentally friendly. In this project, we concentrate on green fuels which we define as those capable of being produced from renewable and sustainable resources in a way that is compatible with the current transportation fuel infrastructure. One route to green fuels that has received relatively little attention begins with algae as a feedstock. Algae are a diverse group of aquatic, photosynthetic organisms, generally categorized as either macroalgae (i.e. seaweed) or microalgae. Microalgae constitute a spectacularly diverse group of prokaryotic and eukaryotic unicellular organisms and account for approximately 50% of global organic carbon fixation. The PI's have subdivided the proposed research program into three main research areas, all of which are essential to the development of commercially viable algae fuels compatible with current energy infrastructure. In the fuel development focus, catalytic cracking reactions of algae oils is optimized. In the species development project, genetic engineering is used to create microalgae strains that are capable of high-level hydrocarbon production. For the modeling effort, the construction of multi-scaled models of algae production was prioritized, including integrating small-scale hydrodynamic models of algae production and reactor design and large-scale design optimization models.

  1. Photosynthetic H2 metabolism in Chlamydomonas reinhardtii (unicellular green algae).

    PubMed

    Melis, Anastasios

    2007-10-01

    Unicellular green algae have the ability to operate in two distinctly different environments (aerobic and anaerobic), and to photosynthetically generate molecular hydrogen (H2). A recently developed metabolic protocol in the green alga Chlamydomonas reinhardtii permitted separation of photosynthetic O2-evolution and carbon accumulation from anaerobic consumption of cellular metabolites and concomitant photosynthetic H2-evolution. The H2 evolution process was induced upon sulfate nutrient deprivation of the cells, which reversibly inhibits photosystem-II and O2-evolution in their chloroplast. In the absence of O2, and in order to generate ATP, green algae resorted to anaerobic photosynthetic metabolism, evolved H2 in the light and consumed endogenous substrate. This study summarizes recent advances on green algal hydrogen metabolism and discusses avenues of research for the further development of this method. Included is the mechanism of a substantial tenfold starch accumulation in the cells, observed promptly upon S-deprivation, and the regulated starch and protein catabolism during the subsequent H2-evolution. Also discussed is the function of a chloroplast envelope-localized sulfate permease, and the photosynthesis-respiration relationship in green algae as potential tools by which to stabilize and enhance H2 metabolism. In addition to potential practical applications of H2, approaches discussed in this work are beginning to address the biochemistry of anaerobic H2 photoproduction, its genes, proteins, regulation, and communication with other metabolic pathways in microalgae. Photosynthetic H2 production by green algae may hold the promise of generating a renewable fuel from nature's most plentiful resources, sunlight and water. The process potentially concerns global warming and the question of energy supply and demand.

  2. [Use of blue-green algae for biogas production].

    PubMed

    Shmandiĭ, B M; Nikiforov, V V; Alferov, V P; Kharlamova, E V; Pronin, V A

    2010-01-01

    Perspectives for nature protection and energy-saving, by using blue-green algae, are discussed. Utilization of their phyto biomass for biogas manufacture will lead to the environmental normalization of the Transdniestria and allow one to have about 19,000,000 m3 of methane only from the water area of only one Kremenchug water basin each vegetative period (70 days).

  3. Fatty acid amides from freshwater green alga Rhizoclonium hieroglyphicum.

    PubMed

    Dembitsky, V M; Shkrob, I; Rozentsvet, O A

    2000-08-01

    Freshwater green algae Rhizoclonium hieroglyphicum growing in the Ural Mountains were examined for their fatty acid amides using capillary gas chromatography-mass spectrometry (GC-MS). Eight fatty acid amides were identified by GC-MS. (Z)-9-octadecenamide was found to be the major component (2.26%).

  4. Oleosin of subcellular lipid droplets evolved in green algae.

    PubMed

    Huang, Nan-Lan; Huang, Ming-Der; Chen, Tung-Ling L; Huang, Anthony H C

    2013-04-01

    In primitive and higher plants, intracellular storage lipid droplets (LDs) of triacylglycerols are stabilized with a surface layer of phospholipids and oleosin. In chlorophytes (green algae), a protein termed major lipid-droplet protein (MLDP) rather than oleosin on LDs was recently reported. We explored whether MLDP was present directly on algal LDs and whether algae had oleosin genes and oleosins. Immunofluorescence microscopy revealed that MLDP in the chlorophyte Chlamydomonas reinhardtii was associated with endoplasmic reticulum subdomains adjacent to but not directly on LDs. In C. reinhardtii, low levels of a transcript encoding an oleosin-like protein (oleolike) in zygotes-tetrads and a transcript encoding oleosin in vegetative cells transferred to an acetate-enriched medium were found in transcriptomes and by reverse transcription-polymerase chain reaction. The C. reinhardtii LD fraction contained minimal proteins with no detectable oleolike or oleosin. Several charophytes (advanced green algae) possessed low levels of transcripts encoding oleosin but not oleolike. In the charophyte Spirogyra grevilleana, levels of oleosin transcripts increased greatly in cells undergoing conjugation for zygote formation, and the LD fraction from these cells contained minimal proteins, two of which were oleosins identified via proteomics. Because the minimal oleolike and oleosins in algae were difficult to detect, we tested their subcellular locations in Physcomitrella patens transformed with the respective algal genes tagged with a Green Fluorescent Protein gene and localized the algal proteins on P. patens LDs. Overall, oleosin genes having weak and cell/development-specific expression were present in green algae. We present a hypothesis for the evolution of oleosins from algae to plants.

  5. Effect of Interactions Among Algae on Nitrogen Fixation by Blue-Green Algae (Cyanobacteria) in Flooded Soils

    PubMed Central

    Wilson, John T.; Greene, Sarah; Alexander, Martin

    1979-01-01

    Nitrogen fixation (C2H2 reduction) by algae in flooded soil was limited by interactions within the algal community. Nitrogen fixation by either indigenous algae or Tolypothrix tenuis was reduced severalfold by a dense suspension of the green alga Nephrocytium sp. Similarly, interactions between the nitrogen-fixing alga (cyanobacterium) Aulosira 68 and natural densities of indigenous algae limited nitrogen-fixing activity in one of two soils examined. This was demonstrated by developing a variant of Aulosira 68 that was resistant to the herbicide simetryne at concentrations that prevented development of indigenous algae. More nitrogen was fixed by the resistant variant in flooded soil containing herbicide than was fixed in herbicide-free soil by either the indigenous algae or indigenous algae plus the parent strain of Aulosira. Interference from indigenous algae may hamper the development of nitrogen-fixing algae introduced into rice fields in attempts to increase biological nitrogen fixation. PMID:16345463

  6. Fitness Effects of Spontaneous Mutations in Picoeukaryotic Marine Green Algae

    PubMed Central

    Krasovec, Marc; Eyre-Walker, Adam; Grimsley, Nigel; Salmeron, Christophe; Pecqueur, David; Piganeau, Gwenael; Sanchez-Ferandin, Sophie

    2016-01-01

    Estimates of the fitness effects of spontaneous mutations are important for understanding the adaptive potential of species. Here, we present the results of mutation accumulation experiments over 265–512 sequential generations in four species of marine unicellular green algae, Ostreococcus tauri RCC4221, Ostreococcus mediterraneus RCC2590, Micromonas pusilla RCC299, and Bathycoccus prasinos RCC1105. Cell division rates, taken as a proxy for fitness, systematically decline over the course of the experiment in O. tauri, but not in the three other species where the MA experiments were carried out over a smaller number of generations. However, evidence of mutation accumulation in 24 MA lines arises when they are exposed to stressful conditions, such as changes in osmolarity or exposure to herbicides. The selection coefficients, estimated from the number of cell divisions/day, varies significantly between the different environmental conditions tested in MA lines, providing evidence for advantageous and deleterious effects of spontaneous mutations. This suggests a common environmental dependence of the fitness effects of mutations and allows the minimum mutation/genome/generation rates to be inferred at 0.0037 in these species. PMID:27175016

  7. Fitness Effects of Spontaneous Mutations in Picoeukaryotic Marine Green Algae.

    PubMed

    Krasovec, Marc; Eyre-Walker, Adam; Grimsley, Nigel; Salmeron, Christophe; Pecqueur, David; Piganeau, Gwenael; Sanchez-Ferandin, Sophie

    2016-07-07

    Estimates of the fitness effects of spontaneous mutations are important for understanding the adaptive potential of species. Here, we present the results of mutation accumulation experiments over 265-512 sequential generations in four species of marine unicellular green algae, Ostreococcus tauri RCC4221, Ostreococcus mediterraneus RCC2590, Micromonas pusilla RCC299, and Bathycoccus prasinos RCC1105. Cell division rates, taken as a proxy for fitness, systematically decline over the course of the experiment in O. tauri, but not in the three other species where the MA experiments were carried out over a smaller number of generations. However, evidence of mutation accumulation in 24 MA lines arises when they are exposed to stressful conditions, such as changes in osmolarity or exposure to herbicides. The selection coefficients, estimated from the number of cell divisions/day, varies significantly between the different environmental conditions tested in MA lines, providing evidence for advantageous and deleterious effects of spontaneous mutations. This suggests a common environmental dependence of the fitness effects of mutations and allows the minimum mutation/genome/generation rates to be inferred at 0.0037 in these species.

  8. Studies on the hormonal relationships of algae in pure culture : I. The effect of indole-3-acetic acid on the growth of blue-green and green algae.

    PubMed

    Ahmad, M R; Winter, A

    1968-09-01

    Indole-3-acetic acid (IAA) stimulated the growth (increase in dry weight) of the blue-green algae Anacystis nidulans, Chlorogloea fritschii, Phormidium foveolarum, Nostoc muscorum, Anabaena cylindrica, and Tolypothrix tenuis and the green algae Chlorella pyrenoidosa, Ankistrodesmus falcatus and Scenedesmus obliquus growing under as sterile conditions as possible. The optimum concentration varied from species to species; in the blue-green algae it ranged from 10(-5) to 10(-9) M and in the green algae it was 10(-3) M. These results are discussed in the light of present studies in this field.

  9. Cycloartane triterpenes from marine green alga Cladophora fascicularis

    NASA Astrophysics Data System (ADS)

    Huang, Xinping; Zhu, Xiaobin; Deng, Liping; Deng, Zhiwei; Lin, Wenhan

    2006-12-01

    Six cycloartanes were isolated from ethanol extract of marine green alga Cladophora fascicularis by column chromatography. Procedure of isolation and description of these compounds are given in this paper. The structures were elucidated as (1). 24-hydroperoxycycloart-25- en-3β-ol; (2). cycloart-25-en-3β 24-diol; (3). 25-hydroperoxycycloart-23-en-3β-ol; (4). cycloart-23-en-3β, 25-diol; (5). cycloart-23, 25-dien-3β-ol; and (6). cycloart-24-en-3β-ol by spectroscopic (MS, ID and 2D NMR) data analysis. Cycloartane derivatives are widely distributed in terrestrial plants, but only few were obtained in the alga. All these compounds that have been isolated from terrestrial plants, were found in the marine alga for the first time.

  10. Hydrogenases in green algae: do they save the algae's life and solve our energy problems?

    PubMed

    Happe, Thomas; Hemschemeier, Anja; Winkler, Martin; Kaminski, Annette

    2002-06-01

    Green algae are the only known eukaryotes with both oxygenic photosynthesis and a hydrogen metabolism. Recent physiological and genetic discoveries indicate a close connection between these metabolic pathways. The anaerobically inducible hydA genes of algae encode a special type of highly active [Fe]-hydrogenase. Electrons from reducing equivalents generated during fermentation enter the photosynthetic electron transport chain via the plastoquinone pool. They are transferred to the hydrogenase by photosystem I and ferredoxin. Thus, the [Fe]-hydrogenase is an electron 'valve' that enables the algae to survive under anaerobic conditions. During sulfur deprivation, illuminated algal cultures evolve large quantities of hydrogen gas, and this promises to be an alternative future energy source.

  11. Green Algae as Model Organisms for Biological Fluid Dynamics*

    PubMed Central

    Goldstein, Raymond E.

    2015-01-01

    In the past decade the volvocine green algae, spanning from the unicellular Chlamydomonas to multicellular Volvox, have emerged as model organisms for a number of problems in biological fluid dynamics. These include flagellar propulsion, nutrient uptake by swimming organisms, hydrodynamic interactions mediated by walls, collective dynamics and transport within suspensions of microswimmers, the mechanism of phototaxis, and the stochastic dynamics of flagellar synchronization. Green algae are well suited to the study of such problems because of their range of sizes (from 10 μm to several millimetres), their geometric regularity, the ease with which they can be cultured and the availability of many mutants that allow for connections between molecular details and organism-level behavior. This review summarizes these recent developments and highlights promising future directions in the study of biological fluid dynamics, especially in the context of evolutionary biology, that can take advantage of these remarkable organisms. PMID:26594068

  12. Green Algae as Model Organisms for Biological Fluid Dynamics

    NASA Astrophysics Data System (ADS)

    Goldstein, Raymond E.

    2015-01-01

    In the past decade, the volvocine green algae, spanning from the unicellular Chlamydomonas to multicellular Volvox, have emerged as model organisms for a number of problems in biological fluid dynamics. These include flagellar propulsion, nutrient uptake by swimming organisms, hydrodynamic interactions mediated by walls, collective dynamics and transport within suspensions of microswimmers, the mechanism of phototaxis, and the stochastic dynamics of flagellar synchronization. Green algae are well suited to the study of such problems because of their range of sizes (from 10 μm to several millimeters), their geometric regularity, the ease with which they can be cultured, and the availability of many mutants that allow for connections between molecular details and organism-level behavior. This review summarizes these recent developments and highlights promising future directions in the study of biological fluid dynamics, especially in the context of evolutionary biology, that can take advantage of these remarkable organisms.

  13. Green Algae as Model Organisms for Biological Fluid Dynamics.

    PubMed

    Goldstein, Raymond E

    2015-01-01

    In the past decade the volvocine green algae, spanning from the unicellular Chlamydomonas to multicellular Volvox, have emerged as model organisms for a number of problems in biological fluid dynamics. These include flagellar propulsion, nutrient uptake by swimming organisms, hydrodynamic interactions mediated by walls, collective dynamics and transport within suspensions of microswimmers, the mechanism of phototaxis, and the stochastic dynamics of flagellar synchronization. Green algae are well suited to the study of such problems because of their range of sizes (from 10 μm to several millimetres), their geometric regularity, the ease with which they can be cultured and the availability of many mutants that allow for connections between molecular details and organism-level behavior. This review summarizes these recent developments and highlights promising future directions in the study of biological fluid dynamics, especially in the context of evolutionary biology, that can take advantage of these remarkable organisms.

  14. Multicellularity in green algae: upsizing in a walled complex.

    PubMed

    Domozych, David S; Domozych, Catherine E

    2014-01-01

    Modern green algae constitute a large and diverse taxonomic assemblage that encompasses many multicellular phenotypes including colonial, filamentous, and parenchymatous forms. In all multicellular green algae, each cell is surrounded by an extracellular matrix (ECM), most often in the form of a cell wall. Volvocalean taxa like Volvox have an elaborate, gel-like, hydroxyproline rich glycoprotein covering that contains the cells of the colony. In "ulvophytes," uronic acid-rich and sulfated polysaccharides are the likely adhesion agents that maintain the multicellular habit. Charophytes also produce polysaccharide-rich cell walls and in late divergent taxa, pectin plays a critical role in cell adhesion in the multicellular complex. Cell walls are products of coordinated interaction of membrane trafficking, cytoskeletal dynamics and the cell's signal transduction machinery responding both to precise internal clocks and external environmental cues. Most often, these activities must be synchronized with the secretion, deposition and remodeling of the polymers of the ECM. Rapid advances in molecular genetics, cell biology and cell wall biochemistry of green algae will soon provide new insights into the evolution and subcellular processes leading to multicellularity.

  15. Bioaccumulation and catabolism of prometryne in green algae.

    PubMed

    Jin, Zhen Peng; Luo, Kai; Zhang, Shuang; Zheng, Qi; Yang, Hong

    2012-04-01

    Investigation on organic xenobiotics bioaccumulation/biodegradation in green algae is of great importance from environmental point of view because widespread distribution of these compounds in agricultural areas has become one of the major problems in aquatic ecosystem. Also, new technology needs to be developed for environmental detection and re-usage of the compounds as bioresources. Prometryne as a herbicide is widely used for killing annual grasses in China and other developing countries. However, overuse of the pesticide results in high risks to contamination to aquatic environments. In this study, we focused on analysis of bioaccumulation and degradation of prometryne in Chlamydomonas reinhardtii, a green alga, along with its adaptive response to prometryne toxicity. C. reinhardtii treated with prometryne at 2.5-12.5 μg L(-1) for 4 d or 7.5 μg L(-1) for 1-6 d accumulated a large quantity of prometryne, with more than 2 mg kg(-1) fresh weight in cells exposed to 10 μg L(-1) prometryne. Moreover, it showed a great ability to degrade simultaneously the cell-accumulated prometryne. Such uptake and catabolism of prometryne led to the rapid removal of prometryne from media. Physiological and molecular analysis revealed that toxicology was associated with accumulation of prometryne in the cells. The biological processes of degradation can be interpreted as an internal tolerance mechanism. These results suggest that the green alga is useful in bioremediation of prometryne-contaminated aquatic ecosystems.

  16. Multicellularity in green algae: upsizing in a walled complex

    PubMed Central

    Domozych, David S.; Domozych, Catherine E.

    2014-01-01

    Modern green algae constitute a large and diverse taxonomic assemblage that encompasses many multicellular phenotypes including colonial, filamentous, and parenchymatous forms. In all multicellular green algae, each cell is surrounded by an extracellular matrix (ECM), most often in the form of a cell wall. Volvocalean taxa like Volvox have an elaborate, gel-like, hydroxyproline rich glycoprotein covering that contains the cells of the colony. In “ulvophytes,” uronic acid-rich and sulfated polysaccharides are the likely adhesion agents that maintain the multicellular habit. Charophytes also produce polysaccharide-rich cell walls and in late divergent taxa, pectin plays a critical role in cell adhesion in the multicellular complex. Cell walls are products of coordinated interaction of membrane trafficking, cytoskeletal dynamics and the cell’s signal transduction machinery responding both to precise internal clocks and external environmental cues. Most often, these activities must be synchronized with the secretion, deposition and remodeling of the polymers of the ECM. Rapid advances in molecular genetics, cell biology and cell wall biochemistry of green algae will soon provide new insights into the evolution and subcellular processes leading to multicellularity. PMID:25477895

  17. Phytotoxicity, bioaccumulation and degradation of isoproturon in green algae.

    PubMed

    Bi, Yan Fang; Miao, Shan Shan; Lu, Yi Chen; Qiu, Chong Bin; Zhou, You; Yang, Hong

    2012-12-01

    Isoproturon (IPU) is a pesticide used for protection of land crops from weed or pathogen attack. Recent survey shows that IPU has been detected as a contaminant in aquatic systems and may have negative impact on aquatic organisms. To understand the phytotoxicity and potential accumulation and degradation of IPU in algae, a comprehensive study was performed with the green alga Chlamydomonas reinhardtii. Algae exposed to 5-50 μg L(-1) IPU for 3d displayed progressive inhibition of cell growth and reduced chlorophyll fluorescence. Time-course experiments with 25 μg L(-1) IPU for 6d showed similar growth responses. The 72 h EC50 value for IPU was 43.25 μg L(-1), NOEC was 5 μg L(-1) and LOEC was 15 μg L(-1). Treatment with IPU induced oxidative stress. This was validated by a group of antioxidant enzymes, whose activities were promoted by IPU exposure. The up-regulation of several genes coding for the enzymes confirmed the observation. IPU was shown to be readily accumulated by C. reinhardtii. However, the alga showed a weak ability to degrade IPU accumulated in its cells, which was best presented at the lower concentration (5 μg L(-1)) of IPU in the medium. The imbalance of accumulation and degradation of IPU may be the cause that resulted in the detrimental growth and cellular damage.

  18. Sexual reproduction and sex determination in green algae.

    PubMed

    Sekimoto, Hiroyuki

    2017-05-01

    The sexual reproductive processes of some representative freshwater green algae are reviewed. Chlamydomonas reinhardtii is a unicellular volvocine alga having two mating types: mating type plus (mt(+)) and mating type minus (mt(-)), which are controlled by a single, complex mating-type locus. Sexual adhesion between the gametes is mediated by sex-specific agglutinin molecules on their flagellar membranes. Cell fusion is initiated by an adhesive interaction between the mt(+) and mt(-) mating structures, followed by localized membrane fusion. The loci of sex-limited genes and the conformation of sex-determining regions have been rearranged during the evolution of volvocine algae; however, the essential function of the sex-determining genes of the isogamous unicellular Chlamydomonas reinhardtii is conserved in the multicellular oogamous Volvox carteri. The sexual reproduction of the unicellular charophycean alga, Closterium peracerosum-strigosum-littorale complex, is also focused on here. The sexual reproductive processes of heterothallic strains are controlled by two multifunctional sex pheromones, PR-IP and PR-IP Inducer, which independently promote multiple steps in conjugation at the appropriate times through different induction mechanisms. The molecules involved in sexual reproduction and sex determination have also been characterized.

  19. Lysis of Blue-Green Algae by Myxobacter

    PubMed Central

    Shilo, Miriam

    1970-01-01

    Enrichment from local fishponds led to the isolation of a bacterium capable of lysing many species of unicellular and filamentous blue-green algae, as well as certain bacteria. The isolate is an aflagellate, motile rod which moves in a gliding, flexuous manner; the organism is capable of digesting starch and agar, but not cellulose and gelatin. Its deoxyribonucleic acid base pair composition (per cent guanine plus cytosine ∼70) shows a close resemblance to that of the fruiting myxobacteria. Algae in lawns on agar plates were lysed rapidly by the myxobacter, but only limited and slow lysis occurred in liquid media, and no lysis took place when liquid cultures were shaken. No diffusible lytic factors would be demonstrated. Continuous observation of the lytic process under a phase-contrast microscope suggested that a close contact between the polar tip of the myxobacter and the alga is necessary for lysis. The lytic action is limited to the vegetative cells of the algae, whereas heterocysts are not affected. The gas vacuoles of the algal host are the only remnant visible after completion of digestion by the myxobacter. Images PMID:4990764

  20. Intracellular invasion of green algae in a salamander host

    PubMed Central

    Kerney, Ryan; Kim, Eunsoo; Hangarter, Roger P.; Heiss, Aaron A.; Bishop, Cory D.; Hall, Brian K.

    2011-01-01

    The association between embryos of the spotted salamander (Ambystoma maculatum) and green algae (“Oophila amblystomatis” Lamber ex Printz) has been considered an ectosymbiotic mutualism. We show here, however, that this symbiosis is more intimate than previously reported. A combination of imaging and algal 18S rDNA amplification reveals algal invasion of embryonic salamander tissues and cells during development. Algal cells are detectable from embryonic and larval Stages 26–44 through chlorophyll autofluorescence and algal 18S rDNA amplification. Algal cell ultrastructure indicates both degradation and putative encystment during the process of tissue and cellular invasion. Fewer algal cells were detected in later-stage larvae through FISH, suggesting that the decline in autofluorescent cells is primarily due to algal cell death within the host. However, early embryonic egg capsules also contained encysted algal cells on the inner capsule wall, and algal 18S rDNA was amplified from adult reproductive tracts, consistent with oviductal transmission of algae from one salamander generation to the next. The invasion of algae into salamander host tissues and cells represents a unique association between a vertebrate and a eukaryotic alga, with implications for research into cell–cell recognition, possible exchange of metabolites or DNA, and potential congruence between host and symbiont population structures. PMID:21464324

  1. Effect of tetramethyl lead on freshwater green algae.

    PubMed

    Silverberg, B A; Wong, P T; Chau, Y K

    1977-01-01

    The toxicity of tetramethyl lead (Me4Pb) towards freshwater algae was studied by bubbling biologically generated Me4Pb from one flask containing 5 mg of Pb 1-1 as Me3PbOAc into the culture medium in another flask where a test alga Scenedesmus quadricauda was grown. As Me4Pb is not soluble in water and is volatile, the exposure of an alga to this lead compound was only momentary. It was estimated that less than 0.5 mg of Pb(Me4Pb) had passed through the culture medium. The primary productivity and cell growth (determined by dry weight), however, decreased by 85% and 32% respectively, as compared with the controls without exposure to Me4Pb. Furthermore, cells exposed to Me4Pb tended to clump together and striking alterations in cell fine-structure were observed. An electron microscopic analysis by an energy dispersive spectrometer revealed that Pb ions had penetrated the cell and were deposited within concretion bodies. Similar results were obtained with the green algae Ankistrodesmus falcatus and Chlorella pyrenoidosa.

  2. Towards tradable permits for filamentous green algae pollution.

    PubMed

    de Lange, W J; Botha, A M; Oberholster, P J

    2016-09-01

    Water pollution permit systems are challenging to design and implement. Operational systems that has maintained functionality remains few and far between, particularly in developing countries. We present current progress towards developing such a system for nutrient enrichment based water pollution, mainly from commercial agriculture. We applied a production function approach to first estimate the monetary value of the impact of the pollution, which is then used as reference point for establishing a reserve price for pollution permits. The subsequent market making process is explained according to five steps including permit design, terms, conditions and transactional protocol, the monitoring system, piloting and implementation. The monetary value of the impact of pollution was estimated at R1887 per hectare per year, which not only provide a "management budget" for filamentous green algae mitigation strategies in the study area, but also enabled the calculation of a reserve price for filamentous green algae pollution permits, which was estimated between R2.25 and R111 per gram filamentous algae and R8.99 per gram at the preferred state. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Characterization of phosphoethanolamine-N-methyltransferases in green algae.

    PubMed

    Hirashima, Takashi; Toyoshima, Masakazu; Moriyama, Takashi; Nakamura, Yuki; Sato, Naoki

    2017-06-17

    Phosphatidylcholine (PtdCho) is a common and abundant phospholipid in most eukaryotic organisms. Although it has been known that the model green alga Chlamydomonas reinhardtii lacks PtdCho, we recently detected PtdCho in four Chlamydomonas species. Homology search of draft genomic sequences of the four PtdCho-containing algae suggested existence of phosphoethanolamine-N-methyltransferase (PEAMT) in C. applanata and C. asymmetrica, which is the key enzyme in PtdCho biosynthesis in land plants. Here we analyzed the putative genes encoding PEAMT in C. applanata and C. asymmetrica, named CapPEAMT and CasPEAMT, respectively. In vitro assays with recombinant CapPEAMT and CasPEAMT indicated that they have the methylation activity for phosphoethanolamine, but not the methylation activity for phosphomonomethylethanolamine, in contrast with land plant PEAMTs, that possess the three successive methylation activities. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Crystal structure of plastocyanin from a green alga, Enteromorpha prolifera.

    PubMed

    Collyer, C A; Guss, J M; Sugimura, Y; Yoshizaki, F; Freeman, H C

    1990-02-05

    The crystal structure of the Cu-containing protein plastocyanin (Mr 10,500) from the green alga Enteromorpha prolifera has been solved by molecular replacement. The structure was refined by constrained-restrained and restrained reciprocal space least-squares techniques. The refined model includes 111 solvent sites. There is evidence for alternate conformers at eight residues. The residual is 0.12 for a data set comprising 74% of all observations accessible at 1.85 A resolution. The beta-sandwich structure of the algal plastocyanin is effectively the same as that of poplar leaf (Populus nigra var. italica) plastocyanin determined at 1.6 A resolution. The sequence homology between the two proteins is 56%. Differences between the contacts in the hydrophobic core create some significant (0.5 to 1.2 A) movements of the polypeptide backbone, resulting in small differences between the orientations and separations of corresponding beta-strands. These differences are most pronounced at the end of the molecule remote from the Cu site. The largest structural differences occur in the single non-beta strand, which includes the sole turn of helix in the molecule: two of the residues in a prominent kink of the poplar plastocyanin backbone are missing from the algal plastocyanin sequence, and there is a significant change in the position of the helical segment in relation to the beta-sandwich. Several other small but significant structural differences can be correlated with intermolecular contacts in the crystals. An intramolecular carboxyl-carboxylate hydrogen bond in the algal plastocyanin may be associated with an unusually high pKa. The dimensions of the Cu site in the two plastocyanins are, within the limits of precision, identical.

  5. Unearthing the molecular phylodiversity of desert soil green algae (Chlorophyta).

    PubMed

    Lewis, Louise A; Lewis, Paul O

    2005-12-01

    Deserts are not usually considered biodiversity hotspots, but desert microbiotic crust communities exhibit a rich diversity of both eukaryotic and prokaryotic life forms. Like many communities dominated by microscopic organisms, they defy characterization by traditional species-counting approaches to assessing biodiversity. Here we use exclusive molecular phylodiversity (E) to quantify the amount of evolutionary divergence unique to desert-dwelling green algae (Chlorophyta) in microbiotic crust communities. Given a phylogenetic tree with branch lengths expressed in units of expected substitutions per site, E is the total length of all tree segments representing exclusively desert lineages. Using MCMC to integrate over tree topologies and branch lengths provides 95% Bayesian credible intervals for phylodiversity measures. We found substantial exclusive molecular phylodiversity based on 18S rDNA data, showing that desert lineages are distantly related to their nearest aquatic relatives. Our results challenge conventional wisdom, which holds that there was a single origin of terrestrial green plants and that green algae are merely incidental visitors rather than indigenous components of desert communities. We identify examples of lineage diversification within deserts and at least 12 separate transitions from aquatic to terrestrial life apart from the most celebrated transition leading to the embryophyte land plants. [Bayesian phylogenetics; biodiversity; exclusive molecular phylodiversity; microbiotic crusts.].

  6. PCD and autophagy in the unicellular green alga Micrasterias denticulata.

    PubMed

    Affenzeller, Matthias Josef; Darehshouri, Anza; Andosch, Ancuela; Lütz, Cornelius; Lütz-Meindl, Ursula

    2009-08-01

    Programmed cell death (PCD) plays a central role in normal plant development and is also induced by various biotic and abiotic stress factors. In the unicellular freshwater green alga Micrasterias denticulata morphological and biochemical hallmarks such as the appearance of autophagosomes, increased production of ROS and degradation of genomic DNA into small fragments ("DNA laddering") indicate PCD. Our data not only demonstrate that Micrasterias is capable of performing PCD under salt stress, but also that it is triggered by the ionic and not osmotic component of salinity. Additionally, results from the present and previous studies suggest that different inducers may lead to different cell death pathways in one and the same organism.

  7. Interaction of organic solvents with the green alga Chlorella pyrenoidosa

    SciTech Connect

    Stratton, G.W.; Smith, T.M. )

    1988-06-01

    Solvents are often a component of bioassay systems when water-insoluble toxicants are being tested. These solvents must also be considered as xenobiotics and therefore, as potential toxicants in the bioassay. However, the effects of solvents on the organisms being tested and their possible interaction with the test compound are often overlooked by researchers. The purpose of the present study was to compare the inhibitory effects of six solvents commonly used in pesticide bioassays towards growth of the common green alga Chlorella pyrenoidosa, and to examine the occurrence of solvent-pesticide interactions with this organism.

  8. Substitution rate calibration of small subunit ribosomal RNA identifies chlorarachniophyte endosymbionts as remnants of green algae.

    PubMed Central

    Van de Peer, Y; Rensing, S A; Maier, U G; De Wachter, R

    1996-01-01

    Chlorarachniophytes are amoeboid algae with chlorophyll a and b containing plastids that are surrounded by four membranes instead of two as in plants and green algae. These extra membranes form important support for the hypothesis that chlorarachniophytes have acquired their plastids by the ingestion of another eukaryotic plastid-containing alga. Chlorarachniophytes also contain a small nucleus-like structure called the nucleomorph situated between the two inner and the two outer membranes surrounding the plastid. This nucleomorph is a remnant of the endosymbiont's nucleus and encodes, among other molecules, small subunit ribosomal RNA. Previous phylogenetic analyses on the basis of this molecule provided unexpected and contradictory evidence for the origin of the chlorarachniophyte endosymbiont. We developed a new method for measuring the substitution rates of the individual nucleotides of small subunit ribosomal RNA. From the resulting substitution rate distribution, we derived an equation that gives a more realistic relationship between sequence dissimilarity and evolutionary distance than equations previously available. Phylogenetic trees constructed on the basis of evolutionary distances computed by this new method clearly situate the chlorarachniophyte nucleomorphs among the green algae. Moreover, this relationship is confirmed by transversion analysis of the Chlorarachnion plastid small subunit ribosomal RNA. PMID:8755544

  9. Solar-driven hydrogen production in green algae.

    PubMed

    Burgess, Steven J; Tamburic, Bojan; Zemichael, Fessehaye; Hellgardt, Klaus; Nixon, Peter J

    2011-01-01

    The twin problems of energy security and global warming make hydrogen an attractive alternative to traditional fossil fuels with its combustion resulting only in the release of water vapor. Biological hydrogen production represents a renewable source of the gas and can be performed by a diverse range of microorganisms from strict anaerobic bacteria to eukaryotic green algae. Compared to conventional methods for generating H(2), biological systems can operate at ambient temperatures and pressures without the need for rare metals and could potentially be coupled to a variety of biotechnological processes ranging from desalination and waste water treatment to pharmaceutical production. Photobiological hydrogen production by microalgae is particularly attractive as the main inputs for the process (water and solar energy) are plentiful. This chapter focuses on recent developments in solar-driven H(2) production in green algae with emphasis on the model organism Chlamydomonas reinhardtii. We review the current methods used to achieve sustained H(2) evolution and discuss possible approaches to improve H(2) yields, including the optimization of culturing conditions, reducing light-harvesting antennae and targeting auxiliary electron transport and fermentative pathways that compete with the hydrogenase for reductant. Finally, industrial scale-up is discussed in the context of photobioreactor design and the future prospects of the field are considered within the broader context of a biorefinery concept. Copyright © 2011 Elsevier Inc. All rights reserved.

  10. Photosynthetic hydrogen and oxygen production by green algae

    SciTech Connect

    Greenbaum, E.; Lee, J.W.

    1997-12-31

    An overview of photosynthetic hydrogen and oxygen production by green algae in the context of its potential as a renewable chemical feed stock and energy carrier is presented. Beginning with its discovery by Gaffron and Rubin in 1942, motivated by curiosity-driven laboratory research, studies were initiated in the early 1970s that focused on photosynthetic hydrogen production from an applied perspective. From a scientific and technical point of view, current research is focused on optimizing net thermodynamic conversion efficiencies represented by the Gibbs Free Energy of molecular hydrogen. The key research questions of maximizing hydrogen and oxygen production by light-activated water splitting in green algae are (1) removing the oxygen sensitivity of algal hydrogenases; (2) linearizing the light saturation curves of photosynthesis throughout the entire range of terrestrial solar irradiance--including the role of bicarbonate and carbon dioxide in optimization of photosynthetic electron transport and (3) the minimum number of light reactions that are required to split water to elemental hydrogen and oxygen. Each of these research topics is being actively addressed by the photobiological hydrogen research community.

  11. Photosynthetic Hydrogen and Oxygen Production by Green Algae

    SciTech Connect

    Greenbaum, E.; Lee, J.W.

    1999-08-22

    Photosynthesis research at Oak Ridge National Laboratory is focused on hydrogen and oxygen production by green algae in the context of its potential as a renewable fuel and chemical feed stock. Beginning with its discovery by Gaffron and Rubin in 1942, motivated by curiosity-driven laboratory research, studies were initiated in the early 1970s that focused on photosynthetic hydrogen production from an applied perspective. From a scientific and technical point of view, current research is focused on optimizing net thermodynamic conversion efficiencies represented by the Gibbs Free Energy of molecular hydrogen. The key research questions of maximizing hydrogen and oxygen production by light-activated water splitting in green algae are: (1) removing the oxygen sensitivity of algal hydrogenases; (2) linearizing the light saturation curves of hotosynthesis throughout the entire range of terrestrial solar irradiance-including the role of bicarbonate and carbon dioxide in optimization of photosynthetic electron transpor;t and (3) constructing real-world bioreactors, including the generation of hydrogen and oxygen against workable back pressures of the photoproduced gases.

  12. The Effects of Ultraviolet Irradiation on a Coccoid Blue-Green Alga: Survival, Photosynthesis, and Photoreactivation 1

    PubMed Central

    Van Baalen, Chase

    1968-01-01

    The effects of UV irradiation (254 mμ) on a coccoid blue-green alga Agmenellum quadruplicatum, Strain PR-6, have been examined in terms of the survival curve and measurement of short time photosynthetic rates. From study of survival evidence has been found for a strong photoreactivation centered near 430 mμ. Measurements of photosynthetic rate suggest that there is a correlation between decay of photosynthesis and survival after UV exposure. The UV induced decay in photosynthetic activity is reversed by the identical photoreactivation conditions that increase the survival level. The photosynthetic data are interpreted as demonstrating a photoreactivation of photosynthesis in blue-green algae. PMID:16656955

  13. The effects of graphene oxide on green algae Raphidocelis subcapitata.

    PubMed

    Nogueira, P F M; Nakabayashi, D; Zucolotto, V

    2015-09-01

    Graphene represents a new class of nanomaterials that has attracted great interest due to its unique electrical, thermal, and mechanical properties. Once disposed in the environment, graphene can interact with biological systems and is expected to exhibit toxicological effects. The ecotoxicity of graphene and its derivatives, viz.: graphene oxide (GO) depends on their physicochemical properties, including purity, diameter, length, surface charge, functionalization and aggregation state. In this study we evaluated the effects of graphene oxide (GO) on green algae Raphidocelis subcapitata. The algae were exposed to different concentrations of GO pre-equilibrated for 24h with oligotrophic freshwater medium (20ml) during incubation in a growth chamber under controlled conditions: 120μEm(-2)s(-1) illumination; 12:12h light dark cycle and constant temperature of 22±2°C. Algal growth was monitored daily for 96h by direct cell counting. Reactive oxygen species level (ROS), membrane damage (cell viability) and autofluorescence (chl-a fluorescence) were evaluated using fluorescent staining and further analyzed by flow cytometry. The toxic effects from GO, as observed in algal density and autofluorescence, started at concentrations from 20 and 10μgmL(-1), respectively. Such toxicity is probably the result of ROS generation and membrane damage (cell viability). The shading effect caused by GO agglomeration in culture medium may also contribute to reduce algal density. The results reported here provide knowledge regarding the GO toxicity on green algae, contributing to a better understanding of its environmental behavior and impacts. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Analytical approaches to photobiological hydrogen production in unicellular green algae.

    PubMed

    Hemschemeier, Anja; Melis, Anastasios; Happe, Thomas

    2009-01-01

    Several species of unicellular green algae, such as the model green microalga Chlamydomonas reinhardtii, can operate under either aerobic photosynthesis or anaerobic metabolism conditions. A particularly interesting metabolic condition is that of "anaerobic oxygenic photosynthesis", whereby photosynthetically generated oxygen is consumed by the cell's own respiration, causing anaerobiosis in the culture in the light, and induction of the cellular "hydrogen metabolism" process. The latter entails an alternative photosynthetic electron transport pathway, through the oxygen-sensitive FeFe-hydrogenase, leading to the light-dependent generation of molecular hydrogen in the chloroplast. The FeFe-hydrogenase is coupled to the reducing site of photosystem-I via ferredoxin and is employed as an electron-pressure valve, through which electrons are dissipated, thus permitting a sustained electron transport in the thylakoid membrane of photosynthesis. This hydrogen gas generating process in the cells offers testimony to the unique photosynthetic metabolism that can be found in many species of green microalgae. Moreover, it has attracted interest by the biotechnology and bioenergy sectors, as it promises utilization of green microalgae and the process of photosynthesis in renewable energy production. This article provides an overview of the principles of photobiological hydrogen production in microalgae and addresses in detail the process of induction and analysis of the hydrogen metabolism in the cells. Furthermore, methods are discussed by which the interaction of photosynthesis, respiration, cellular metabolism, and H(2) production in Chlamydomonas can be monitored and regulated.

  15. Deep Transcriptome Sequencing of Two Green Algae, Chara vulgaris and Chlamydomonas reinhardtii,  Provides No Evidence of Organellar RNA Editing.

    PubMed

    Cahoon, A Bruce; Nauss, John A; Stanley, Conner D; Qureshi, Ali

    2017-02-20

    Nearly all land plants post-transcriptionally modify specific nucleotides within RNAs, a process known as RNA editing. This adaptation allows the correction of deleterious mutations within the asexually reproducing and presumably non-recombinant chloroplast and mitochondrial genomes. There are no reports of RNA editing in any of the green algae so this phenomenon is presumed to have originated in embryophytes either after the invasion of land or in the now extinct algal ancestor of all land plants. This was challenged when a recent in silico screen for RNA edit sites based on genomic sequence homology predicted edit sites in the green alga Chara vulgaris, a multicellular alga found within the Streptophyta clade and one of the closest extant algal relatives of land plants. In this study, the organelle transcriptomes of C. vulgaris and Chlamydomonas reinhardtii were deep sequenced for a comprehensive assessment of RNA editing. Initial analyses based solely on sequence comparisons suggested potential edit sites in both species, but subsequent high-resolution melt analysis, RNase H-dependent PCR (rhPCR), and Sanger sequencing of DNA and complementary DNAs (cDNAs) from each of the putative edit sites revealed them to be either single-nucleotide polymorphisms (SNPs) or spurious deep sequencing results. The lack of RNA editing in these two lineages is consistent with the current hypothesis that RNA editing evolved after embryophytes split from its ancestral algal lineage.

  16. Defined Media for Growth and Gamete Production by the Green Alga, Oedogonium cardiacum.

    PubMed

    Hill, G J; Machlis, L

    1970-08-01

    Defined media consisting of inorganic salts and vitamin B(12) are described for the male and female filaments of the green alga, Oedogonium cardiacum. These media provide for a maximal growth rate and for the induction of oogonia and antheridia under the prescribed conditions. The maximal amounts of growth, based on dry weight measurements, compare favorably with other green algae.

  17. Developing Molecular Genetic Tools to Facilitate Economic Production in Green Algae

    DTIC Science & Technology

    2012-09-10

    species they are not readily available for algae that are being identified as potential biofuel production strains . Our work was focused on developing...the genetic tools required to enable green algae to become efficient biofuel production strains . Being able to efficiently apply genetic...transformation techniques to green algae species will allow us to generate strains that contain ideal traits for maximally efficient fuel production, and will

  18. Cellular response of freshwater green algae to perfluorooctanoic acid toxicity.

    PubMed

    Xu, Dongmei; Li, Chandan; Chen, Hong; Shao, Bo

    2013-02-01

    Perfluorooctanoic acid (PFOA) is a kind of persistent organic pollutants and its aquatic eco-toxicity has attracted wide attention; however, the mechanism involved in its toxicity as well as the cell response against PFOA have not been well established. Herein, using single-celled green algae Chlorella pyrenoidosa and Selenastrum capricornutum at the logarithmic growth stage as test organisms, we studied the toxic effects of PFOA on the cell permeability, The 96 h-EC(50) values of PFOA for C. pyrenoidosa and S. capricornutum were 207.46 mg L(-1) and 190.99 mg L(-1), respectively, lower than the 96 h-EC(50) values reported in the literatures. After 96 h of PFOA exposure, the permeability of the cell membranes of both algae was significantly decreased, and the chlorophyll concentration mirrored the trends of algal growth. In both algal species, after a 192-h exposure to a low concentration of PFOA, the activities of superoxide dismutase and catalase were greater than those of the control. At higher concentrations of PFOA, activities of superoxide dismutase and catalase were strongly inhibited. These results indicate that long-term exposure to low levels of PFOA may induce excessive generation of reactive oxygen species in algal cells, causing oxidative damage to cells.

  19. Enhanced Genetic Tools for Engineering Multigene Traits into Green Algae

    PubMed Central

    Rasala, Beth A.; Chao, Syh-Shiuan; Pier, Matthew; Barrera, Daniel J.; Mayfield, Stephen P.

    2014-01-01

    Transgenic microalgae have the potential to impact many diverse biotechnological industries including energy, human and animal nutrition, pharmaceuticals, health and beauty, and specialty chemicals. However, major obstacles to sophisticated genetic and metabolic engineering in algae have been the lack of well-characterized transformation vectors to direct engineered gene products to specific subcellular locations, and the inability to robustly express multiple nuclear-encoded transgenes within a single cell. Here we validate a set of genetic tools that enable protein targeting to distinct subcellular locations, and present two complementary methods for multigene engineering in the eukaryotic green microalga Chlamydomonas reinhardtii. The tools described here will enable advanced metabolic and genetic engineering to promote microalgae biotechnology and product commercialization. PMID:24710110

  20. Amidic and acetonic cryoprotectants improve cryopreservation of volvocine green algae.

    PubMed

    Nakazawa, A; Nishii, I

    2012-01-01

    A number of volvocalean green algae species were subjected to a two-step cryopreservation protocol with various cryoprotectants. Potential cryoprotectants were methanol (DMSO), N,N-dimethylformamide (DMF), N,N-dimethylacetamide, N-methylformamide, and hydroxyacetone (HA). We confirmed prior reports that MeOH was effective for cryopreserving Chlamydomonas, but did not work well for larger volvocaleans such as Volvox. In contrast, DMF and HA were effective for both unicellular and multicellular representatives. When we used a cold-inducible transposon to probe Southern blots of Volvox DNA samples taken before and after storage for one month in LN, we could detect no differences, indicating that the genome had remained relatively stable and that the transposon had not been induced by the cryopreservation procedure. We believe these methods will facilitate long-term storage of several volvocine algal species, including Volvox strains harboring transposon-induced mutations of developmental interest.

  1. [Epiphase carotenoids of the blue-green alga Anabaena variabilia].

    PubMed

    Pakhlavuni, I K; Vasil'eva, V E; Gusev, M V

    1977-01-01

    Epiphase carotenoids were studied in the cells of the obligate phototrophous blue-green alga Anabaena variabilis. Ten pigment zones were detected by column chromatography on alumina and by TLC on cellulose and Silufol UV-254 plates. TLC in the B layer and paper chromatography did not reveal all pigment zones obtained on a column. The data of TLC on cellulose and on Silufol plates confirmed the purity and individual character of the fractions obtained on a column. These data showed also that the pigments obtained upon the separation of the extract on a column were not the products of its interaction with an active adsorbent. Absorption spectra of the isolated pigments were determined in various solvents, and speculations were made concerning the structure of the carotenoids.

  2. Enhanced genetic tools for engineering multigene traits into green algae.

    PubMed

    Rasala, Beth A; Chao, Syh-Shiuan; Pier, Matthew; Barrera, Daniel J; Mayfield, Stephen P

    2014-01-01

    Transgenic microalgae have the potential to impact many diverse biotechnological industries including energy, human and animal nutrition, pharmaceuticals, health and beauty, and specialty chemicals. However, major obstacles to sophisticated genetic and metabolic engineering in algae have been the lack of well-characterized transformation vectors to direct engineered gene products to specific subcellular locations, and the inability to robustly express multiple nuclear-encoded transgenes within a single cell. Here we validate a set of genetic tools that enable protein targeting to distinct subcellular locations, and present two complementary methods for multigene engineering in the eukaryotic green microalga Chlamydomonas reinhardtii. The tools described here will enable advanced metabolic and genetic engineering to promote microalgae biotechnology and product commercialization.

  3. Antiherpetic activities of sulfated polysaccharides from green algae.

    PubMed

    Lee, Jung-Bum; Hayashi, Kyoko; Maeda, Masaakira; Hayashi, Toshimitsu

    2004-09-01

    In order to evaluate the potency of novel antiviral drugs, 11 natural sulfated polysaccharides (SPs) from 10 green algae ( Enteromorpha compressa, Monostroma nitidum, Caulerpa brachypus, C. okamurai, C. scapelliformis, Chaetomorpha crassa, C. spiralis, Codium adhaerens, C. fragille, and C. latum) and 4 synthetic sulfated xylans (SXs) prepared from the beta-(1,3)-xylan of C. brachypus, were assayed for anti-Herpes simplex virus type 1 (HSV-1) activity. Except for one from E. compressa, all SPs showed potent anti-HSV-1 activities with 50 % inhibitory concentrations (IC (50)) of 0.38 - 8.5 microg/mL, while having low cytotoxicities with 50 % inhibitory concentrations of >2900 microg/mL. Anti-HSV-1 activities of SXs were dependent on their degrees of sulfation. To delineate the drug-sensitive phase, 4 polysaccharides, which showed potent anti-HSV-1 activities, were applied to time-of-addition experiments. Among the polysaccharides tested, 3 polysaccharides (SX4, SP4 from C. brachypus, and SP11 from C. latum) showed strong anti-HSV-1 activities with IC (50) of 6.0, 7.5, and 6.9 microg/mL, respectively, even when added to the medium 8 h post-infection. These experiments demonstrated that some sulfated polysaccharides not only inhibited the early stages of HSV-1 replication, such as virus binding to and penetration into host cells, but also interfered with late steps of virus replication. These results revealed that some sulfated polysaccharides from green algae should be promising candidates of antiviral agents which might act on different stages in the virus replication cycle.

  4. A Lack of Parasitic Reduction in the Obligate Parasitic Green Alga Helicosporidium

    PubMed Central

    Pombert, Jean-François; Blouin, Nicolas Achille; Lane, Chris; Boucias, Drion; Keeling, Patrick J.

    2014-01-01

    The evolution of an obligate parasitic lifestyle is often associated with genomic reduction, in particular with the loss of functions associated with increasing host-dependence. This is evident in many parasites, but perhaps the most extreme transitions are from free-living autotrophic algae to obligate parasites. The best-known examples of this are the apicomplexans such as Plasmodium, which evolved from algae with red secondary plastids. However, an analogous transition also took place independently in the Helicosporidia, where an obligate parasite of animals with an intracellular infection mechanism evolved from algae with green primary plastids. We characterised the nuclear genome of Helicosporidium to compare its transition to parasitism with that of apicomplexans. The Helicosporidium genome is small and compact, even by comparison with the relatively small genomes of the closely related green algae Chlorella and Coccomyxa, but at the functional level we find almost no evidence for reduction. Nearly all ancestral metabolic functions are retained, with the single major exception of photosynthesis, and even here reduction is not complete. The great majority of genes for light-harvesting complexes, photosystems, and pigment biosynthesis have been lost, but those for other photosynthesis-related functions, such as Calvin cycle, are retained. Rather than loss of whole function categories, the predominant reductive force in the Helicosporidium genome is a contraction of gene family complexity, but even here most losses affect families associated with genome maintenance and expression, not functions associated with host-dependence. Other gene families appear to have expanded in response to parasitism, in particular chitinases, including those predicted to digest the chitinous barriers of the insect host or remodel the cell wall of Helicosporidium. Overall, the Helicosporidium genome presents a fascinating picture of the early stages of a transition from free

  5. Green Algae and the Origins of Multicellularity in the Plant Kingdom

    PubMed Central

    Umen, James G.

    2014-01-01

    The green lineage of chlorophyte algae and streptophytes form a large and diverse clade with multiple independent transitions to produce multicellular and/or macroscopically complex organization. In this review, I focus on two of the best-studied multicellular groups of green algae: charophytes and volvocines. Charophyte algae are the closest relatives of land plants and encompass the transition from unicellularity to simple multicellularity. Many of the innovations present in land plants have their roots in the cell and developmental biology of charophyte algae. Volvocine algae evolved an independent route to multicellularity that is captured by a graded series of increasing cell-type specialization and developmental complexity. The study of volvocine algae has provided unprecedented insights into the innovations required to achieve multicellularity. PMID:25324214

  6. Green algae and the origins of multicellularity in the plant kingdom.

    PubMed

    Umen, James G

    2014-10-16

    The green lineage of chlorophyte algae and streptophytes form a large and diverse clade with multiple independent transitions to produce multicellular and/or macroscopically complex organization. In this review, I focus on two of the best-studied multicellular groups of green algae: charophytes and volvocines. Charophyte algae are the closest relatives of land plants and encompass the transition from unicellularity to simple multicellularity. Many of the innovations present in land plants have their roots in the cell and developmental biology of charophyte algae. Volvocine algae evolved an independent route to multicellularity that is captured by a graded series of increasing cell-type specialization and developmental complexity. The study of volvocine algae has provided unprecedented insights into the innovations required to achieve multicellularity. Copyright © 2014 Cold Spring Harbor Laboratory Press; all rights reserved.

  7. [The cultivation of Vibrio cholerae with green algae in an experiment].

    PubMed

    Titova, S V

    2000-01-01

    Relationships between Vibrio cholerae of different origin and some serogroups with green algae Scenedesmus quadricauda in mineral medium at two temperatures have been experimentally studied. Differences in the relationships of various strains with green algae under the above-mentioned experimental conditions have been established. The study has shown that a decrease in the concentration and the death of vct+ and vct- vibrios of all strains under study occur in the linear phase of the development of algae. 3 V. cholerae strains, serogroups O139 (vct+) and O50 (vct-), have been shown to be capable of survival under the conditions mix cultivation with algae for 50-100 days. The perish of green algae is supposed to increase the survival time and multiplication of V. cholerae under experimental conditions.

  8. The Cell Walls of Green Algae: A Journey through Evolution and Diversity.

    PubMed

    Domozych, David S; Ciancia, Marina; Fangel, Jonatan U; Mikkelsen, Maria Dalgaard; Ulvskov, Peter; Willats, William G T

    2012-01-01

    The green algae represent a large group of morphologically diverse photosynthetic eukaryotes that occupy virtually every photic habitat on the planet. The extracellular coverings of green algae including cell walls are also diverse. A recent surge of research in green algal cell walls fueled by new emerging technologies has revealed new and critical insight concerning these coverings. For example, the late divergent taxa of the Charophycean green algae possess cell walls containing assemblages of polymers with notable similarity to the cellulose, pectins, hemicelluloses, arabinogalactan proteins (AGPs), extensin, and lignin present in embryophyte walls. Ulvophycean seaweeds have cell wall components whose most abundant fibrillar constituents may change from cellulose to β-mannans to β-xylans and during different life cycle phases. Likewise, these algae produce complex sulfated polysaccharides, AGPs, and extensin. Chlorophycean green algae produce a wide array of walls ranging from cellulose-pectin complexes to ones made of hydroxyproline-rich glycoproteins. Larger and more detailed surveys of the green algal taxa including incorporation of emerging genomic and transcriptomic data are required in order to more fully resolve evolutionary trends within the green algae and in relationship with higher plants as well as potential applications of wall components in the food and pharmaceutical industries.

  9. The Cell Walls of Green Algae: A Journey through Evolution and Diversity

    PubMed Central

    Domozych, David S.; Ciancia, Marina; Fangel, Jonatan U.; Mikkelsen, Maria Dalgaard; Ulvskov, Peter; Willats, William G. T.

    2012-01-01

    The green algae represent a large group of morphologically diverse photosynthetic eukaryotes that occupy virtually every photic habitat on the planet. The extracellular coverings of green algae including cell walls are also diverse. A recent surge of research in green algal cell walls fueled by new emerging technologies has revealed new and critical insight concerning these coverings. For example, the late divergent taxa of the Charophycean green algae possess cell walls containing assemblages of polymers with notable similarity to the cellulose, pectins, hemicelluloses, arabinogalactan proteins (AGPs), extensin, and lignin present in embryophyte walls. Ulvophycean seaweeds have cell wall components whose most abundant fibrillar constituents may change from cellulose to β-mannans to β-xylans and during different life cycle phases. Likewise, these algae produce complex sulfated polysaccharides, AGPs, and extensin. Chlorophycean green algae produce a wide array of walls ranging from cellulose–pectin complexes to ones made of hydroxyproline-rich glycoproteins. Larger and more detailed surveys of the green algal taxa including incorporation of emerging genomic and transcriptomic data are required in order to more fully resolve evolutionary trends within the green algae and in relationship with higher plants as well as potential applications of wall components in the food and pharmaceutical industries. PMID:22639667

  10. Hepatopathy following consumption of a commercially available blue-green algae dietary supplement in a dog.

    PubMed

    Bautista, Adrienne C; Moore, Caroline E; Lin, Yanping; Cline, Martha G; Benitah, Noemi; Puschner, Birgit

    2015-06-19

    Dietary supplement use in both human and animals to augment overall health continues to increase and represents a potential health risk due to the lack of safety regulations imposed on the manufacturers. Because there are no requirements for demonstrating safety and efficacy prior to marketing, dietary supplements may contain potentially toxic contaminants such as hepatotoxic microcystins produced by several species of blue-green algae. An 11-year-old female spayed 8.95 kg Pug dog was initially presented for poor appetite, lethargy polyuria, polydipsia, and an inability to get comfortable. Markedly increased liver enzyme activities were detected with no corresponding abnormalities evident on abdominal ultrasound. A few days later the liver enzyme activities were persistently increased and the dog was coagulopathic indicating substantial liver dysfunction. The dog was hospitalized for further care consisting of oral S-adenosylmethionine, silybin, vitamin K, and ursodeoxycholic acid, as well as intravenous ampicillin sodium/sulbactam sodium, dolasetron, N-acetylcysteine, metoclopramide, and intravenous fluids. Improvement of the hepatopathy and the dog's clinical status was noted over the next three days. Assessment of the dog's diet revealed the use of a commercially available blue-green algae dietary supplement for three-and-a-half weeks prior to hospitalization. The supplement was submitted for toxicology testing and revealed the presence of hepatotoxic microcystins (MCs), MC-LR and MC-LA. Use of the supplement was discontinued and follow-up evaluation over the next few weeks revealed a complete resolution of the hepatopathy. To the authors' knowledge, this is the first case report of microcystin intoxication in a dog after using a commercially available blue-green algae dietary supplement. Veterinarians should recognize the potential harm that these supplements may cause and know that with intervention, recovery is possible. In addition, more prudent oversight of

  11. Complete Chloroplast Genome Sequence of the Early Diverging Green Alga Palmophyllum crassum

    PubMed Central

    Furukawa, Ryo; Kunugi, Motoshi; Ihara, Kunio; Tanaka, Ayumi

    2017-01-01

    ABSTRACT Palmophyllum crassum is a little-known green alga, with a unique evolutionary position and distinctive photosynthetic features. Here, we present the complete chloroplast genome sequence of Palmophyllum crassum. PMID:28280029

  12. Aluminum bioavailability to the green alga Chlorella pyrenoidosa in acidified synthetic soft water

    SciTech Connect

    Parent, L.; Campbell, P.G.C. )

    1994-04-01

    A unicellular green alga, Chlorella pyrenoidosa, was exposed to inorganic Al under controlled experimental conditions to determine whether the biological response elicited by the dissolved metal could be predicted from the free-metal ion concentration, [Al[sup 3+

  13. Production and release of selenocyanate by different green freshwater algae in environmental and laboratory samples.

    PubMed

    LeBlanc, Kelly L; Smith, Matthew S; Wallschläger, Dirk

    2012-06-05

    In a previous study, selenocyanate was tentatively identified as a biotransformation product when green algae were exposed to environmentally relevant concentrations of selenate. In this follow-up study, we confirm conclusively the presence of selenocyanate in Chlorella vulgaris culture medium by electrospray mass spectrometry, based on selenium's known isotopic pattern. We also demonstrate that the observed phenomenon extends to other green algae (Chlorella kesslerii and Scenedesmus obliquus) and at least one species of blue-green algae (Synechococcus leopoliensis). Further laboratory experiments show that selenocyanate production by algae is enhanced by addition of nitrate, which appears to serve as a source of cyanide produced in the algae. Ultimately, this biotransformation process was confirmed in field experiments where trace amounts of selenocyanate (0.215 ± 0.010 ppb) were observed in a eutrophic, selenium-impacted river with massive algal blooms, which consisted of filamentous green algae (Cladophora genus) and blue-green algae (Anabaena genus). Selenocyanate abundance was low despite elevated selenium concentrations, apparently due to suppression of selenate uptake by sulfate, and insufficient nitrogen concentrations. Finally, trace levels of several other unidentified selenium-containing compounds were observed in these river water samples; preliminary suggestions for their identities include thioselenate and small organic Se species.

  14. Production of carbonate sediments by a unicellular green alga

    USGS Publications Warehouse

    Yates, K.K.; Robbins, L.L.

    1998-01-01

    This study investigates the ability of the unicellular green alga Natmochloris atoimis to precipitate CaCO3, quantifies mineral precipitation rates, estimates sediment production in a N. atomiis bloom, and discusses the implications of microbial calcification for carbonate sediment deposition. A series of N. atomus cultures, isolated from Lake Reeve, Australia, were incubated at various pH and calcium concentrations to determine environmental parameters for calcification. Rates of calcification were calculated from initial and postincubation alkalinity, pH, and calcium measurements. Replicate experiments and controls consisting of non-calcifying cultures, uninoculated media, and dead cell cultures were performed using environmental culture parameters determined in series cultures. Average calcification rates from replicate experiments were used to predict daily sediment production rates in a small bloom of N. atomus. N. atomus precipitates 0.138 g/L of calcite in approximately 4 h when incubated at pH 8.5, 14.24 mM calcium concentration, 33 ??C, 100 ??E/m2/s light intensity, and a cell population density of 107 cells/mL. Assuming continuous precipitation, this corresponds to a maximum estimated sediment production rate of 1.6 ?? 106 kg of CaCO3, per 12 h day in a single bloom of 3.2 ?? 109 L. Our results suggest that microbial calcification contributes significantly to the carbonate sediment budget.

  15. Microfiltration for separation of green algae from water.

    PubMed

    Hung, M T; Liu, J C

    2006-08-15

    Cross-flow microfiltration was used for separation of green algae, Chlorella sp., from freshwater. The transmembrane pressure (TMP) was adjusted at 40, 50 and 60 kPa, respectively. The cross-flow velocity was set at 0.43 m/s for laminar flow and 0.84 m/s for turbulent flow, respectively. The results showed that flux increased as TMP increased from 40 to 50 kPa. But drastic flux decline was observed when operating at TMP of 60 kPa. Raising cross-flow velocity increased the initial flux of MF under TMP of 60 kPa. Nevertheless, implementing turbulent cross-flow did not improve the drastic flux decline under the highest TMP. Preozonation increased the dissolved organic carbon, decreased algal viability and made the size of algal cells smaller. It also increased dissolved polysaccharide that derived from extracellular organic matter (EOM). Different effects of preozonation on flux behavior of MF were observed when utilizing hydrophobic and hydrophilic membrane. Generally speaking, preozonation improved performance of microfiltration by reducing cake compressibility and the biomass loading when both membranes were used. However, dissolved polysaccharide released during preozonation was adsorbed onto the hydrophobic membrane. Consequently, fouling resistance of the hydrophobic membrane became higher. These arguments were verified by classification of hydrodynamic resistances.

  16. Penicillinase (beta-lactamase) formation by blue-green algae.

    PubMed

    Kushner, D J; Breuil, C

    1977-03-01

    Beta-Lactamase (penicillinase) activity was found in a number of strains of blue-green algea. In some cases, this enzyme permitted algae to overcome the inhibitory effects of penicillin. Production and localization of beta-lactamase were studied in a unicellular species, Coccochloris elabens (strain 7003), and in a filamentous, nitrogen-fixing Anabaena species (strain 7120). When cells were grown in a neutral medium with NaNO3 as N source, the pH rose during growth; at a pH of about 10, most of the enzyme was expressed equally well in intact or disrupted cells. If the pH was kept near neutrality during growth by gassing with CO2 in N2 or by growth under conditions of N2 fixation, the enzyme remained cell-bound and cryptic for most of the growth phase, being measurable only after cells were disrupted. The enzymes from strains 7003 and 7120 had greater activity on benzyl penicillin and other penicillins than on cephalosporins. Some differences were observed in the "substrate proliles" of penicillinases from the two strains against different penicillins.

  17. Homogentisate phytyltransferase from the unicellular green alga Chlamydomonas reinhardtii.

    PubMed

    Gálvez-Valdivieso, Gregorio; Cardeñosa, Rosa; Pineda, Manuel; Aguilar, Miguel

    2015-09-01

    Homogentisate phytyltransferase (HPT) (EC 2.5.1.-) catalyzes the first committed step of tocopherol biosynthesis in all photosynthetic organisms. This paper presents the molecular characterization and expression analysis of HPT1 gene, and a study on the accumulation of tocopherols under different environmental conditions in the unicellular green alga Chlamydomonas reinhardtii. The Chlamydomonas HPT1 protein conserves all the prenylphosphate- and divalent cation-binding sites that are found in polyprenyltransferases and all the amino acids that are essential for its catalytic activity. Its hydrophobicity profile confirms that HPT is a membrane-bound protein. Chlamydomonas genomic DNA analysis suggests that HPT is encoded by a single gene, HPT1, whose promoter region contains multiple motifs related to regulation by jasmonate, abscisic acid, low temperature and light, and an ATCTA motif presents in genes involved in tocopherol biosynthesis and some photosynthesis-related genes. Expression analysis revealed that HPT1 is strongly regulated by dark and low-temperature. Under the same treatments, α-tocopherol increased in cultures exposed to darkness or heat, whereas γ-tocopherol did it in low temperature. The regulatory expression pattern of HPT1 and the changes of tocopherol abundance support the idea that different tocopherols play specific functions, and suggest a role for γ-tocopherol in the adaptation to growth under low-temperature.

  18. In situ evaluation of cadmium biomarkers in green algae.

    PubMed

    Simon, Dana F; Davis, Thomas A; Tercier-Waeber, Mary-Lou; England, Roxane; Wilkinson, Kevin J

    2011-10-01

    In situ measurements provide data that are the highly representative of the natural environment. In this paper, laboratory-determined biomarkers of Cd stress that were previously identified for the green alga Chlamydomonas reinhardtii, were tested in two French rivers: a contaminated site on the Riou Mort River and an "uncontaminated" reference site on the Lot River. Transcript abundance levels were determined by real time qPCR for biomarkers thought to be Cd sensitive. Transcript levels were significantly higher (>5 fold) for organisms exposed to the contaminated site as compared to those exposed at the uncontaminated site. Biomarker mRNA levels were best correlated to free Cd (Cd(2+)) rather than intracellular Cd, suggesting that they may be useful indicators of in situ stress. The paper shows that biomarker expression levels increased with time, were sensitive to metal levels and metal speciation and were higher in the "contaminated" as opposed to the "reference" site. Copyright © 2011 Elsevier Ltd. All rights reserved.

  19. Toxicity Assessment of Expired Pesticides to Green Algae Pseudokirchneriella subcapitata

    PubMed Central

    Satyavani, G.; Chandrasehar, G.; Varma, K. Krishna; Goparaju, A.; Ayyappan, S.; Reddy, P. Neelakanta; Murthy, P. Balakrishna

    2012-01-01

    In order to investigate the effect of expired pesticides on the yield and growth rate of green algae Pseudokirchneriella subcapitata, a study was conducted as per the Organisation for Economic Cooperation and Development (OECD) guideline number 201. Fifteen expired pesticide formulations, most commonly used in Indian agriculture, were tested in comparison with their unexpired counterparts. The expired pesticide formulations studied belonged to various class and functional groups: organophosphate, pyrethroid-based insecticides; azole-based fungicides; acetamide, propionate, acetic acid-based herbicides; fungicides mixtures containing two actives—azole and dithiocarbamate. The toxicity endpoints of yield (EyC50: 0–72 h) and growth rate (ErC50: 0–72 h) of Pseudokirchneriella subcapitata for each pesticide formulation (both expired and unexpired pesticides) were determined statistically using TOXSTAT 3.5 version software. The results pointed out that some expired pesticide formulations exhibited higher toxicity to tested algal species, as compared to the corresponding unexpired pesticides. These data thus stress the need for greater care to dispose expired pesticides to water bodies, to avoid the effects on aquatic ecospecies tested. PMID:23762633

  20. Phycobilisomes from Blue-Green and Red Algae

    PubMed Central

    Gantt, Elisabeth; Lipschultz, Claudia A.; Grabowski, Joseph; Zimmerman, Burke K.

    1979-01-01

    A general procedure for the isolation of functionally intact phycobilisomes was devised, based on modifications of previously used procedures. It has been successful with numerous species of red and blue-green algae (Anabaena variabilis, Anacystis nidulans, Agmenellum quadruplicatum, Fremyella diplosiphon, Glaucosphaera vacuolata, Griffithsia pacifica, Nemalion multifidum, Nostoc sp., Phormidium persicinum, Porphyridium cruentum, P. sordidum, P. aerugineum, Rhodosorus marinus). Isolation was carried out in 0.75 molar K-phosphate (pH 6.8 to 7.0) at 20 to 23 C on sucrose step gradients. Lower temperature (4 to 10 C) was usually unfavorable resulting in uncoupling of energy transfer and partial dissociation of the phycobilisomes, sometimes with complete loss of allophycocyanin. Intact phycobilisomes were characterized by fluorescence emission peaks of 670 to 675 nanometers at room temperature, and 678 to 685 nanometers at liquid nitrogen temperature. Uncoupling and subsequent dissociation of phycobilisomes, in lowered ionic conditions, varied with the species and the degree of dissociation but occurred preferentially between phycocyanin and allophycocyanin, or between phycocyanin and phycoerythrin. PMID:16660778

  1. Volvoxrhodopsin, a light-regulated sensory photoreceptor of the spheroidal green alga Volvox carteri.

    PubMed Central

    Ebnet, E; Fischer, M; Deininger, W; Hegemann, P

    1999-01-01

    Somatic cells of the multicellular alga Volvox carteri contain a visual rhodopsin that controls the organism's phototactic behavior via two independent photoreceptor currents. Here, we report the identification of an opsinlike gene, designated as volvoxopsin (vop). The encoded protein exhibits homologies to the opsin of the unicellular alga Chlamydomonas reinhardtii (chlamyopsin) and to the entire animal opsin family, thus providing new perspectives on opsin evolution. Volvoxopsin accumulates within the eyes of somatic cells. However, the vop transcript is detectable only in the reproductive eyeless gonidia and embryos. vop mRNA levels increase 400-fold during embryogenesis, when embryos develop in darkness, whereas the vop transcript does not accumulate when embryos develop in the light. An antisense transformant, T3, was generated. This transformant produces 10 times less volvoxopsin than does the wild type. In T3, the vop transcript is virtually absent, whereas the antisense transcript is predominant and light regulated. It follows that vop expression is under light-dependent transcriptional control but that volvoxopsin itself is not the regulatory photoreceptor. Transformant T3 is phototactic, but its phototactic sensitivity is reduced 10-fold relative to the parental wild-type strain HK10. Thus, we offer definitive genetic evidence that a rhodopsin serves as the photoreceptor for phototaxis in a green alga. PMID:10449581

  2. The charophycean green algae provide insights into the early origins of plant cell walls.

    PubMed

    Sørensen, Iben; Pettolino, Filomena A; Bacic, Antony; Ralph, John; Lu, Fachuang; O'Neill, Malcolm A; Fei, Zhangzhun; Rose, Jocelyn K C; Domozych, David S; Willats, William G T

    2011-10-01

    Numerous evolutionary innovations were required to enable freshwater green algae to colonize terrestrial habitats and thereby initiate the evolution of land plants (embryophytes). These adaptations probably included changes in cell-wall composition and architecture that were to become essential for embryophyte development and radiation. However, it is not known to what extent the polymers that are characteristic of embryophyte cell walls, including pectins, hemicelluloses, glycoproteins and lignin, evolved in response to the demands of the terrestrial environment or whether they pre-existed in their algal ancestors. Here we show that members of the advanced charophycean green algae (CGA), including the Charales, Coleochaetales and Zygnematales, but not basal CGA (Klebsormidiales and Chlorokybales), have cell walls that are comparable in several respects to the primary walls of embryophytes. Moreover, we provide both chemical and immunocytochemical evidence that selected Coleochaete species have cell walls that contain small amounts of lignin or lignin-like polymers derived from radical coupling of hydroxycinnamyl alcohols. Thus, the ability to synthesize many of the components that characterize extant embryophyte walls evolved during divergence within CGA. Our study provides new insight into the evolutionary window during which the structurally complex walls of embryophytes originated, and the significance of the advanced CGA during these events.

  3. Chloroplast gene arrangement variation within a closely related group of green algae (Trebouxiophyceae, Chlorophyta).

    PubMed

    Letsch, Molly R; Lewis, Louise A

    2012-09-01

    The 22 published chloroplast genomes of green algae, representing sparse taxonomic sampling of diverse lineages that span over one billion years of evolution, each possess a unique gene arrangement. In contrast, many of the >190 published embryophyte (land plant) chloroplast genomes have relatively conserved architectures. To determine the phylogenetic depth at which chloroplast gene rearrangements occur in green algae, a 1.5-4 kb segment of the chloroplast genome was compared across nine species in three closely related genera of Trebouxiophyceae (Chlorophyta). In total, four distinct gene arrangements were obtained for the three genera Elliptochloris, Hemichloris, and Coccomyxa. In Elliptochloris, three distinct chloroplast gene arrangements were detected, one of which is shared with members of its sister genus Hemichloris. Both species of Coccomyxa examined share the fourth arrangement of this genome region, one characterized by very long spacers. Next, the order of genes found in this segment of the chloroplast genome was compared across green algae and land plants. As taxonomic ranks are not equivalent among different groups of organisms, the maximum molecular divergence among taxa sharing a common gene arrangement in this genome segment was compared. Well-supported clades possessing a single gene order had similar phylogenetic depth in green algae and embryophytes. When the dominant gene order of this chloroplast segment in embryophytes was assumed to be ancestral for land plants, the maximum molecular divergence was found to be over two times greater in embryophytes than in trebouxiophyte green algae. This study greatly expands information about chloroplast genome variation in green algae, is the first to demonstrate such variation among congeneric green algae, and further illustrates the fluidity of green algal chloroplast genome architecture in comparison to that of many embryophytes. Copyright © 2012 Elsevier Inc. All rights reserved.

  4. Sterols in red and green algae: quantification, phylogeny, and relevance for the interpretation of geologic steranes.

    PubMed

    Kodner, R B; Pearson, A; Summons, R E; Knoll, A H

    2008-08-01

    Steroids, a class of triterpenoid lipids with high preservation potential, are widely distributed in sedimentary rocks. All eukaryotes have a physiological requirement for these molecules, making steroids important biomarkers for aiding our understanding of eukaryote molecular evolution and geologic history. C(26)-C(30) sterols are the molecules most commonly incorporated or synthesized by eukaryotes, and correspond to C(26)-C(30) steranes ubiquitously and abundantly preserved in petroleums and sedimentary bitumens. Because these sterols occur in evolutionarily diverse taxa, it can be difficult to associate any particular compound with a single group of organisms. Nevertheless, geochemists have still been able to draw parallels between the empirical patterns in geologic sterane abundances and the age of petroleum source rocks. Paleobiologists have also used sterane data, in particular the patterns in C(29) and C(28) steranes, to support fossil evidence of an early radiation of green algae in latest Proterozoic and Paleozoic and the succession of the major modern phytoplankton groups in the Mesozoic. Although C(29) sterols are found in many eukaryotes, organisms that produce them in proportional abundances comparable to those preserved in Proterozoic and Paleozoic rocks are limited. Based on a large, phylogenetically based survey of sterol profiles from the kingdom Plantae, we conclude that modern ulvophyte and early diverging prasinophyte green algae produce high abundances of C(29) relative to C(27) and C(28) sterols most consistent with the sterane profiles observed in Paleozoic rocks. Our analysis also suggests that ancestral stem groups among the Plantae, including the glaucocystophytes and early divergent red algae are also plausible candidates.

  5. Assimilatory nitrate reductase from the green alga Ankistrodesmus braunii.

    PubMed

    De la Rosa, M A

    1983-01-01

    Assimilatory nitrate reductase (NAD(P)H-nitrate oxidoreductase, EC 1.6.6.2) from the green alga Ankistrodesmus braunii can be purified to homogeneity by dye-ligand chromatography on blue-Sepharose. The purified enzyme, whose turnover number is 623 s-1, presents an optimum pH of 7.5 and Km values of 13 microM, 23 microM and 0.15 mM for NADH, NADPH and nitrate, respectively. The NADH-nitrate reductase activity exhibits an iso ping pong bi bi kinetic mechanism. The molecular weight of the native nitrate reductase is 467 400, while that of its subunits is 58 750. These values suggest an octameric structure for the enzyme, which has been confirmed by electron microscopy. As deduced from spectrophotometric and fluorimetric studies, the enzyme contains FAD and cytochrome b-557 as prosthetic groups. FAD is not covalently bound to the protein and is easily dissociated in diluted solutions from the enzyme. Its apparent Km value is 4 nM, indicative of a high affinity of the enzyme for FAD. The results of the quantitative analyses of prosthetic groups indicate that nitrate reductase contains four molecules of flavin, four heme irons, and two atoms of molybdenum. The three components act sequentially transferring electrons from reduced pyridine nucleotides to nitrate, thus forming a short electron transport chain along the protein. A mechanism is proposed for the redox interconversion of the nitrate reductase activity. Inactivation seems to occur by formation of a stable complex of reduced enzyme with cyanide or superoxide, while reactivation is a consequence of reoxidation of the inactive enzyme. Both reactions imply the transfer of only one electron.

  6. Selenocystamine improves protein accumulation in chloroplasts of eukaryotic green algae.

    PubMed

    Ferreira-Camargo, Livia S; Tran, Miller; Beld, Joris; Burkart, Michael D; Mayfield, Stephen P

    2015-12-01

    Eukaryotic green algae have become an increasingly popular platform for recombinant proteins production. In particular, Chlamydomonas reinhardtii, has garnered increased attention for having the necessary biochemical machinery to produce vaccines, human antibodies and next generation cancer targeting immunotoxins. While it has been shown that chloroplasts contain chaperones, peptidyl prolylisomerases and protein disulfide isomerases that facilitate these complex proteins folding and assembly, little has been done to determine which processes serve as rate-limiting steps for protein accumulation. In other expression systems, as Escherichia coli, Chinese hamster ovary cells, and insect cells, recombinant protein accumulation can be hampered by cell's inability to fold the target polypeptide into the native state, resulting in aggregation and degradation. To determine if chloroplasts' ability to oxidize proteins that require disulfide bonds into a stable conformation is a rate-limiting step of protein accumulation, three recombinant strains, each expressing a different recombinant protein, were analyzed. These recombinant proteins included fluorescent GFP, a reporter containing no disulfide bonds; Gaussia princeps luciferase, a luminescent reporter containing disulfide bonds; and an immunotoxin, an antibody-fusion protein containing disulfide bonds. Each strain was analyzed for its ability to accumulate proteins when supplemented with selenocystamine, a small molecule capable of catalyzing the formation of disulfide bonds. Selenocystamine supplementation led to an increase in luciferase and immunotoxin but not GFP accumulation. These results demonstrated that selenocystamine can increase the accumulation of proteins containing disulfide bonds and suggests that a rate-limiting step in chloroplast protein accumulation is the disulfide bonds formation in recombinant proteins native structure.

  7. How the green alga Chlamydomonas reinhardtii keeps time.

    PubMed

    Schulze, Thomas; Prager, Katja; Dathe, Hannes; Kelm, Juliane; Kiessling, Peter; Mittag, Maria

    2010-08-01

    The unicellular green alga Chlamydomonas reinhardtii has two flagella and a primitive visual system, the eyespot apparatus, which allows the cell to phototax. About 40 years ago, it was shown that the circadian clock controls its phototactic movement. Since then, several circadian rhythms such as chemotaxis, cell division, UV sensitivity, adherence to glass, or starch metabolism have been characterized. The availability of its entire genome sequence along with homology studies and the analysis of several sub-proteomes render C. reinhardtii as an excellent eukaryotic model organism to study its circadian clock at different levels of organization. Previous studies point to several potential photoreceptors that may be involved in forwarding light information to entrain its clock. However, experimental data are still missing toward this end. In the past years, several components have been functionally characterized that are likely to be part of the oscillatory machinery of C. reinhardtii since alterations in their expression levels or insertional mutagenesis of the genes resulted in defects in phase, period, or amplitude of at least two independent measured rhythms. These include several RHYTHM OF CHLOROPLAST (ROC) proteins, a CONSTANS protein (CrCO) that is involved in parallel in photoperiodic control, as well as the two subunits of the circadian RNA-binding protein CHLAMY1. The latter is also tightly connected to circadian output processes. Several candidates including a significant number of ROCs, CrCO, and CASEIN KINASE1 whose alterations of expression affect the circadian clock have in parallel severe effects on the release of daughter cells, flagellar formation, and/or movement, indicating that these processes are interconnected in C. reinhardtii. The challenging task for the future will be to get insights into the clock network and to find out how the clock-related factors are functionally connected. In this respect, system biology approaches will certainly

  8. Hidden genetic diversity in the green alga Spirogyra (Zygnematophyceae, Streptophyta)

    PubMed Central

    2012-01-01

    Background The unbranched filamentous green alga Spirogyra (Streptophyta, Zygnemataceae) is easily recognizable based on its vegetative morphology, which shows one to several spiral chloroplasts. This simple structure falsely points to a low genetic diversity: Spirogyra is commonly excluded from phylogenetic analyses because the genus is known as a long-branch taxon caused by a high evolutionary rate. Results We focused on this genetic diversity and sequenced 130 Spirogyra small subunit nuclear ribosomal DNA (SSU rDNA) strands of different origin. The resulting SSU rDNA sequences were used for phylogenetic analyses using complex evolutionary models (posterior probability, maximum likelihood, neighbor joining, and maximum parsimony methods). The sequences were between 1672 and 1779 nucleotides long. Sequence comparisons revealed 53 individual clones, but our results still support monophyly of the genus. Our data set did not contain a single slow-evolving taxon that would have been placed on a shorter branch compared to the remaining sequences. Out of 130 accessions analyzed, 72 showed a secondary loss of the 1506 group I intron, which formed a long-branched group within the genus. The phylogenetic relationship to the genus Spirotaenia was not resolved satisfactorily. The genetic distance within the genus Spirogyra exceeded the distances measured within any other genus of the remaining Zygnemataceae included in this study. Conclusion Overall, we define eight distinct clades of Spirogyra, one of them including the genus Sirogonium. A large number of non-homoplasious synapomorphies (NHS; 114 NHS in total) was found for Spirogyra (41 NHS) and for each clade (totaling 73 NHS). This emphasizes the high genetic diversity of this genus and the distance to the remaining Zygnematophyceae. PMID:22655677

  9. The influence of nitrogen on heterocyst production in blue-green algae

    USGS Publications Warehouse

    Ogawa, Roann E.; Carr, John F.

    1969-01-01

    A series of experiments on heterocyst production in Anabaena variabilis provides some strong indirect evidence for the role of heterocysts in nitrogen fixation. Of the algae tested (Anabaena variabilis, A. inaequalis, A. cylindrica, A. flos-aquae, Tolypothrix distorta, Gloeotrichia echinulata, Aphanizomenon flos-aquae, Oscillatoria sp., and Microcystis aeruginosa), only those with heterocysts grew in a nitrate-free medium. Growth in the nitrate-free medium was accompanied by an increase in heterocysts. Heterocyst formation in A. variabilis was evident 24 hr after transfer from a nitrate-containing to a nitrate-free medium. The number of heterocysts was altered by changes in the nitrogen source. Numbers were lowest when NH4-N was used as a nitrogen source and highest when nitrogen (N2-N) was derived from the atmosphere. Heterocyst numbers could also be regulated by controlling the concentration of NO3-N in the medium. Heterocyst production depended on the absence of combined nitrogen and the presence of phosphate. Data are presented on the occurrence of blue-green algae (with heterocysts) in Lake Erie and the environmental conditions apparently necessary for them to become dominant.

  10. Development of Singlet Oxygen Luminescence Kinetics during the Photodynamic Inactivation of Green Algae.

    PubMed

    Bornhütter, Tobias; Pohl, Judith; Fischer, Christian; Saltsman, Irena; Mahammed, Atif; Gross, Zeev; Röder, Beate

    2016-04-13

    Recent studies show the feasibility of photodynamic inactivation of green algae as a vital step towards an effective photodynamic suppression of biofilms by using functionalized surfaces. The investigation of the intrinsic mechanisms of photodynamic inactivation in green algae represents the next step in order to determine optimization parameters. The observation of singlet oxygen luminescence kinetics proved to be a very effective approach towards understanding mechanisms on a cellular level. In this study, the first two-dimensional measurement of singlet oxygen kinetics in phototrophic microorganisms on surfaces during photodynamic inactivation is presented. We established a system of reproducible algae samples on surfaces, incubated with two different cationic, antimicrobial potent photosensitizers. Fluorescence microscopy images indicate that one photosensitizer localizes inside the green algae while the other accumulates along the outer algae cell wall. A newly developed setup allows for the measurement of singlet oxygen luminescence on the green algae sample surfaces over several days. The kinetics of the singlet oxygen luminescence of both photosensitizers show different developments and a distinct change over time, corresponding with the differences in their localization as well as their photosensitization potential. While the complexity of the signal reveals a challenge for the future, this study incontrovertibly marks a crucial, inevitable step in the investigation of photodynamic inactivation of biofilms: it shows the feasibility of using the singlet oxygen luminescence kinetics to investigate photodynamic effects on surfaces and thus opens a field for numerous investigations.

  11. Cytoplasmic inheritance in green algae: patterns, mechanisms and relation to sex type.

    PubMed

    Miyamura, Shinichi

    2010-03-01

    Cytological and genetic investigations of two major groups of green algae, chlorophyte and streptophyte green algae, show a predominance of uniparental inheritance of the plastid and mitochondrial genomes in most species. However, in some crosses of isogamous species of Ulva compressa, these genomes are transmitted from mt+, mt(-), and both parents. In species with uniparental organelle inheritance, various mechanisms can eliminate organelles and their DNA during male gametogenesis or after fertilization. Concerning plastid inheritance, two major mechanisms are widespread in green algae: (1) digestion of plastid DNA during male gametogenesis, during fertilization, or after fertilization; and (2) disintegration or fusion of the plastid in the zygote. The first mechanism also eliminates the mitochondrial DNA in anisogamous and oogamous species. These mechanisms would ensure the predominantly uniparental inheritance of organelle genomes in green algae. To trace the evolutionary history of cytoplasmic inheritance in green algae, the relations between uniparental inheritance and sex type were considered in isogamous, anisogamous, and oogamous species using sex-specific features that might be nearly universal among Chlorophyta.

  12. Tracing floating green algae blooms in the Yellow Sea and the East China Sea using Lagrangian transport simulations

    NASA Astrophysics Data System (ADS)

    Park, Young-Gyu; Son, Young Baek; Choi, Byoung-Ju; Kim, Yong Hoon

    2014-05-01

    Lagrangian particle tracking experiments were conducted to understand the pathway of the floating green algae patches observed in the Yellow Sea (YS) and East China Sea (ECS) in summer 2011. The numerical simulation results indicated that dominant southerly winds during June and July 2011 were related to offshore movement of the floating green algae, especially their eastward extension in the YS/ECS. An infrequent and unusual event occurred in June 2011: a severe Tropical Strom MEARI, caused the green algae to detach from the coast and initiated movement to the east. After the typhoon event, sea surface temperature recovered rapidly enough to grow the floating green algae, and wind and local current controlled the movement of the massive floating algae patches (coastal accumulation or offshore advection in the area). Analysis of the floating green algae movement using satellite images during passage of Typhoon MAON in July 2011 revealed that the floating green algae patches were significantly controlled by both ocean currents and enhanced winds. These findings suggest that the floating green algae bloom off Qingdao, China and in the middle of the YS and ECS in the summer of 2011 occurred due to the combined effects of recent rapid expansion of seaweed aquaculture, strong winds, and the wind patterns in blooming regions. Our combined approach, using satellite data and numerical simulations, provides a robust estimate for tracing and monitoring changes in green algae blooms on a regional scale.

  13. AlgaePath: comprehensive analysis of metabolic pathways using transcript abundance data from next-generation sequencing in green algae.

    PubMed

    Zheng, Han-Qin; Chiang-Hsieh, Yi-Fan; Chien, Chia-Hung; Hsu, Bo-Kai Justin; Liu, Tsung-Lin; Chen, Ching-Nen Nathan; Chang, Wen-Chi

    2014-03-14

    Algae are important non-vascular plants that have many research applications, including high species diversity, biofuel sources, and adsorption of heavy metals and, following processing, are used as ingredients in health supplements. The increasing availability of next-generation sequencing (NGS) data for algae genomes and transcriptomes has made the development of an integrated resource for retrieving gene expression data and metabolic pathway essential for functional analysis and systems biology. In a currently available resource, gene expression profiles and biological pathways are displayed separately, making it impossible to easily search current databases to identify the cellular response mechanisms. Therefore, in this work the novel AlgaePath database was developed to retrieve transcript abundance profiles efficiently under various conditions in numerous metabolic pathways. AlgaePath is a web-based database that integrates gene information, biological pathways, and NGS datasets for the green algae Chlamydomonas reinhardtii and Neodesmus sp. UTEX 2219-4. Users can search this database to identify transcript abundance profiles and pathway information using five query pages (Gene Search, Pathway Search, Differentially Expressed Genes (DEGs) Search, Gene Group Analysis, and Co-expression Analysis). The transcript abundance data of 45 and four samples from C. reinhardtii and Neodesmus sp. UTEX 2219-4, respectively, can be obtained directly on pathway maps. Genes that are differentially expressed between two conditions can be identified using Folds Search. The Gene Group Analysis page includes a pathway enrichment analysis, and can be used to easily compare the transcript abundance profiles of functionally related genes on a map. Finally, the Co-expression Analysis page can be used to search for co-expressed transcripts of a target gene. The results of the searches will provide a valuable reference for designing further experiments and for elucidating critical

  14. Clinical and pathologic findings of blue-green algae (Microcystis aeruginosa) intoxication in a dog.

    PubMed

    DeVries, S E; Galey, F D; Namikoshi, M; Woo, J C

    1993-07-01

    A healthy dog developed signs of lethargy and vomiting after ingesting water from a tide pool containing blue-green algae. Fulminant hepatic failure occurred, and the dog was euthanized 52 hours later. At necropsy, the liver was large, friable, and discolored a dark red. Histopathology showed hepatocyte dissociation, degeneration, and necrosis. The alga was identified as Microcystis aeruginosa, a known hepatotoxin. The intraperitoneal administration of lyophilized cell material from the bloom caused hepatic necrosis in mice.

  15. Isolation and cultivation of endosymbiotic algae from green hydra and phylogenetic analysis of 18S rDNA sequences.

    PubMed

    Kovacević, Goran; Franjević, Damjan; Jelencić, Biserka; Kalafatić, Mirjana

    2010-01-01

    Symbiotic associations are of wide significance in evolution and biodiversity. The green hydra is a typical example of endosymbiosis. In its gastrodermal myoepithelial cells it harbors the individuals of a unicellular green algae. Endosymbiotic algae from green hydra have been successfully isolated and permanently maintained in a stable clean lab culture for the first time. We reconstructed the phylogeny of isolated endosymbiotic algae using the 18S rRNA gene to clarify its current status and to validate the traditional inclusion of these endosymbiotic algae within the Chlorella genus. Molecular analyses established that different genera and species of unicellular green algae could be present as symbionts in green hydra, depending on the natural habitat of a particular strain of green hydra.

  16. Equilibrium and kinetics studies of heavy metal ions biosorption on green algae waste biomass.

    PubMed

    Bulgariu, Dumitru; Bulgariu, Laura

    2012-01-01

    The biosorption of Pb(II), Cd(II), and Co(II), respectively, from aqueous solution on green algae waste biomass was investigated. The green algae waste biomass was obtained from marine green algae after extraction of oil, and was used as low-cost biosorbent. Batch shaking experiments were performed to examine the effects of initial solution pH, contact time and temperature. The equilibrium biosorption data were analyzed using two isotherm models (Langmuir and Freundlich) and two kinetics models (pseudo-first order and pseudo-second order). The results indicate that Langmuir model provide best correlation of experimental data, and the pseudo-second order kinetic equation could best describe the biosorption kinetics of considered heavy metals. Copyright © 2011 Elsevier Ltd. All rights reserved.

  17. Optical Remote Sensing Method to Estimate Green Tide Biomass Based on Floating Algae Index

    NASA Astrophysics Data System (ADS)

    Hu, Lianbo; Hu, Chuanmin; He, Mingxia

    2014-11-01

    Floating Algae Index (FAI) has been developed to detect various floating algae in open ocean environments using the medium-resolution (250- and 500-m) data from operational MODIS (Moderate Resolution Imaging Spectroradiometer) instruments. FAI method has been routinely used to identify and calculate the covering area of green tide in the Yellow Sea (YS) since 2009. In addition to green tide covering area, knowledge of the biomass is also important in studying green tide recycling, nutrient load, carbon cycling and for government management. In this study, in situ experiments were conducted to simultaneously measure the biomass and reflectance spectra of green tide on the sea surface in coastal waters off Qingdao on 9 and 11 June 2013. The in situ measurements showed high correlation between green tide biomass and FAI, from which an empirical method to estimate biomass using FAI could be developed.

  18. Genotoxic effects of commercial formulations of Chlorpyrifos and Tebuconazole on green algae.

    PubMed

    Martinez, Ricardo Santiago; Di Marzio, Walter Darío; Sáenz, María Elena

    2015-01-01

    The alkaline single-cell gel electrophoresis assay (comet assay) was used for the study of the genotoxic effects of insecticide Chlorpyrifos and fungicide Tebuconazole (commercial formulations) on two freshwater green algae species, Pseudokirchneriella subcapitata and Nannocloris oculata, after 24 h of exposure. The percentage of DNA in tail of migrating nucleoids was taken as an endpoint of DNA impairment. Cell viability was measured by fluorometric detection of chlorophyll "a" in vivo and the determination of cell auto-fluorescence. Only the higher concentration of Chlorpyrifos tested resulted to affect significantly the cell viability of P. subcapitata, whereas cells of N. oculata were not affected. Tebuconazole assayed concentrations (3 and 6 mg/l) did not affect cell viability of both species. The results of comet assay on P. subcapitata showed that Chlorpyrifos concentration evaluated (0.8 mg/l) exerted a genotoxic effects; while for the other specie a concentration of 10 mg/l was needed. Tebuconazole was genotoxic at 3 and 6 mg/l for both species. The comet assay evidenced damage at the level of DNA simple strains molecule at pesticide concentrations were cytotoxicity was not evident, demonstrating that algae are models to take into account in ecological risk assessments for aquatic environments.

  19. Effects of artificial sweeteners on metal bioconcentration and toxicity on a green algae Scenedesmus obliquus.

    PubMed

    Hu, Hongwei; Deng, Yuanyuan; Fan, Yunfei; Zhang, Pengfei; Sun, Hongwen; Gan, Zhiwei; Zhu, Hongkai; Yao, Yiming

    2016-05-01

    The ecotoxicity of heavy metals depends much on their speciation, which is influenced by other co-existing substances having chelating capacity. In the present study, the toxic effects of Cd(2+) and Cu(2+) on a green algae Scenedesmus obliquus were examined in the presence of two artificial sweeteners (ASs), acesulfame (ACE) and sucralose (SUC) by comparing the cell specific growth rate μ and pulse-amplitude-modulated (PAM) parameters (maximal photosystem II photochemical efficiency Fv/Fm, actual photochemical efficiency Yield, and non-photochemical quenching NPQ) of the algae over a 96-h period. Simultaneously, the bioconcentration of the metals by the algal cells in the presence of the ASs was measured. The presence of ACE enhanced the growth of S. obliquus and promoted the bioconcentration of Cd(2+) in S. obliquus, while the impacts of SUC were not significant. Meanwhile, EC50 values of Cd(2+) on the growth of S. obliquus increased from 0.42 mg/L to 0.54 mg/L and 0.48 mg/L with the addition of 1.0 mg/L ACE and SUC, respectively. As for Cu(2+), EC50 values increased from 0.13 mg/L to 0.17 mg/L and 0.15 mg/L with the addition of 1.0 mg/L ACE and SUC, respectively. In summary, the two ASs reduced the toxicity of the metals on the algae, with ACE showing greater effect than SUC. Although not as sensitive as the cell specific growth rate, PAM parameters could disclose the mechanisms involved in metal toxicity at subcellular levels. This study provides the first evidence for the possible impact of ASs on the ecotoxicity of heavy metals. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Green algae in alpine biological soil crust communities: acclimation strategies against ultraviolet radiation and dehydration.

    PubMed

    Karsten, Ulf; Holzinger, Andreas

    2014-01-01

    Green algae are major components of biological soil crusts in alpine habitats. Together with cyanobacteria, fungi and lichens, green algae form a pioneer community important for the organisms that will succeed them. In their high altitudinal habitat these algae are exposed to harsh and strongly fluctuating environmental conditions, mainly intense irradiation, including ultraviolet radiation, and lack of water leading to desiccation. Therefore, green algae surviving in these environments must have evolved with either avoidance or protective strategies, as well as repair mechanisms for damage. In this review we have highlighted these mechanisms, which include photoprotection, photochemical quenching, and high osmotic values to avoid water loss, and in some groups flexibility of secondary cell walls to maintain turgor pressure even in water-limited situations. These highly specialized green algae will serve as good model organisms to study desiccation tolerance or photoprotective mechanisms, due to their natural capacity to withstand unfavorable conditions. We point out the urgent need for modern phylogenetic approaches in characterizing these organisms, and molecular methods for analyzing the metabolic changes involved in their adaptive strategies.

  1. Bioelectricity generation and microcystins removal in a blue-green algae powered microbial fuel cell.

    PubMed

    Yuan, Yong; Chen, Qing; Zhou, Shungui; Zhuang, Li; Hu, Pei

    2011-03-15

    Bioelectricity production from blue-green algae was examined in a single chamber tubular microbial fuel cell (MFC). The blue-green algae powered MFC produced a maximum power density of 11 4 mW/m(2) at a current density of 0.55 mA/m(2). Coupled with the bioenergy generation, high removal efficiencies of chemical oxygen demand (COD) and nitrogen were also achieved in MFCs. Over 78.9% of total chemical oxygen demand (TCOD), 80.0% of soluble chemical oxygen demand (SCOD), 91.0% of total nitrogen (total-N) and 96.8% ammonium-nitrogen (NH(3)-N) were removed under closed circuit conditions in 12 days, which were much more effective than those under open circuit and anaerobic reactor conditions. Most importantly, the MFC showed great ability to remove microcystins released from blue-green algae. Over 90.7% of MC-RR and 91.1% of MC-LR were removed under closed circuit conditions (500Ω). This study showed that the MFC could provide a potential means for electricity production from blue-green algae coupling algae toxins removal.

  2. Isolation of plasmid from the blue-green alga Spirulina platensis

    NASA Astrophysics Data System (ADS)

    Qin, Song; Tong, Shun; Zhang, Peijun; Tseng, C. K.

    1993-09-01

    CCC plasmid was isolated from an economically important blue-green alga — Spirulina platensis (1.7×106 dalton from the S6 strain and 1.2×106 dalton from the F3 strain) using a rapid method based on ultrasonic disruption of algal cells and alkaline removal of chromosomal DNA. The difference in the molecular weight of the CCC DNAs from the two strains differing in form suggests that plasmid may be related with the differentiation of algal form. This modified method, which does not use any lysozyme, is a quick and effective method of plasmid isolation, especially for filamentous blue-green algae.

  3. Pectin metabolism and assembly in the cell wall of the charophyte green alga Penium margaritaceum.

    PubMed

    Domozych, David S; Sørensen, Iben; Popper, Zoë A; Ochs, Julie; Andreas, Amanda; Fangel, Jonatan U; Pielach, Anna; Sacks, Carly; Brechka, Hannah; Ruisi-Besares, Pia; Willats, William G T; Rose, Jocelyn K C

    2014-05-01

    The pectin polymer homogalacturonan (HG) is a major component of land plant cell walls and is especially abundant in the middle lamella. Current models suggest that HG is deposited into the wall as a highly methylesterified polymer, demethylesterified by pectin methylesterase enzymes and cross-linked by calcium ions to form a gel. However, this idea is based largely on indirect evidence and in vitro studies. We took advantage of the wall architecture of the unicellular alga Penium margaritaceum, which forms an elaborate calcium cross-linked HG-rich lattice on its cell surface, to test this model and other aspects of pectin dynamics. Studies of live cells and microscopic imaging of wall domains confirmed that the degree of methylesterification and sufficient levels of calcium are critical for lattice formation in vivo. Pectinase treatments of live cells and immunological studies suggested the presence of another class of pectin polymer, rhamnogalacturonan I, and indicated its colocalization and structural association with HG. Carbohydrate microarray analysis of the walls of P. margaritaceum, Physcomitrella patens, and Arabidopsis (Arabidopsis thaliana) further suggested the conservation of pectin organization and interpolymer associations in the walls of green plants. The individual constituent HG polymers also have a similar size and branched structure to those of embryophytes. The HG-rich lattice of P. margaritaceum, a member of the charophyte green algae, the immediate ancestors of land plants, was shown to be important for cell adhesion. Therefore, the calcium-HG gel at the cell surface may represent an early evolutionary innovation that paved the way for an adhesive middle lamella in multicellular land plants.

  4. Modeling the Role of Zebra Mussels in the Proliferation of Blue-green Algae in Saginaw Bay, Lake Huron

    EPA Science Inventory

    Under model assumptions from Saginaw Bay 1991, selective rejection of blue-green algae by zebra mussels appears to be a necessary factor in the enhancement of blue-green algae production in the presence of zebra mussels. Enhancement also appears to depend on the increased sedime...

  5. Modeling the Role of Zebra Mussels in the Proliferation of Blue-green Algae in Saginaw Bay, Lake Huron

    EPA Science Inventory

    Under model assumptions from Saginaw Bay 1991, selective rejection of blue-green algae by zebra mussels appears to be a necessary factor in the enhancement of blue-green algae production in the presence of zebra mussels. Enhancement also appears to depend on the increased sedime...

  6. The rapid quantitation of the filamentous blue-green alga plectonema boryanum by the luciferase assay for ATP

    NASA Technical Reports Server (NTRS)

    Bush, V. N.

    1974-01-01

    Plectonema boryanum is a filamentous blue green alga. Blue green algae have a procaryotic cellular organization similar to bacteria, but are usually obligate photoautotrophs, obtaining their carbon and energy from photosynthetic mechanism similar to higher plants. This research deals with a comparison of three methods of quantitating filamentous populations: microscopic cell counts, the luciferase assay for ATP and optical density measurements.

  7. Uptake and Retention of Cs137 by a Blue-Green Alga in Continuous Flow and Batch Culture Systems

    SciTech Connect

    Watts, J.R.

    2003-02-18

    Since routine monitoring data show that blue-green algae concentrate radioactivity from water by factors as great as 10,000, this study was initiated to investigate the uptake and retention patterns of specific radionuclides by the dominant genera of blue-green algae in the reactor effluents. Plectonema purpureum was selected for this study.

  8. Resurrection kinetics of photosynthesis in desiccation-tolerant terrestrial green algae (Chlorophyta) on tree bark.

    PubMed

    Lüttge, U; Büdel, B

    2010-05-01

    The rough bark of orchard trees (Malus) around Darmstadt is predominantly covered in red to purple-brown layers (biofilms) of epiphytic terrestrial alga of Trentepohlia umbrina. The smooth bark of forest trees (Fagus sylvatica L. and Acer sp.) in the same area is covered by bright green biofilms composed of the green algae Desmococcus, Apatococcus and Trebouxia, with a few cells of Coccomyxa and 'Chlorella' trebouxioides between them. These algae are desiccation tolerant. After samples of bark with the biofilms were kept in dry air in darkness for various periods of time, potential quantum yield of PSII, F(v)/F(m), recovered during rehydration upon rewetting. The kinetics and degree of recovery depended on the length of time that the algae were kept in dry air in the desiccated state. Recovery was better for green biofilm samples, i.e. quite good even after 80 days of desiccation (F(v)/F(m) = ca. 50% of initial value), than the red samples, where recovery was only adequate up to ca. 30-40 days of desiccation (F(v)/F(m) = ca. 20-55% of initial value). It is concluded that the different bark types constitute different ecophysiological niches that can be occupied by the algae and that can be distinguished by their capacity to recover from desiccation after different times in the dry state.

  9. Desiccation stress and tolerance in green algae: consequences for ultrastructure, physiological and molecular mechanisms

    PubMed Central

    Holzinger, Andreas; Karsten, Ulf

    2013-01-01

    Although most green algae typically occur in aquatic ecosystems, many species also live partly or permanently under aeroterrestrial conditions, where the cells are exposed to the atmosphere and hence regularly experience dehydration. The ability of algal cells to survive in an air-dried state is termed desiccation tolerance. The mechanisms involved in desiccation tolerance of green algae are still poorly understood, and hence the aim of this review is to summarize recent findings on the effects of desiccation and osmotic water loss. Starting from structural changes, physiological, and biochemical consequences of desiccation will be addressed in different green-algal lineages. The available data clearly indicate a range of strategies, which are rather different in streptophycean and non-streptophycean green algae. While members of the Trebouxiophyceae exhibit effective water loss-prevention mechanisms based on the biosynthesis and accumulation of particular organic osmolytes such as polyols, these compounds are so far not reported in representatives of the Streptophyta. In members of the Streptophyta such as Klebsormidium, the most striking observation is the appearance of cross-walls in desiccated samples, which are strongly undulating, suggesting a high degree of mechanical flexibility. This aids in maintaining structural integrity in the dried state and allows the cell to maintain turgor pressure for a prolonged period of time during the dehydration process. Physiological strategies in aeroterrestrial green algae generally include a rapid reduction of photosynthesis during desiccation, but also a rather quick recovery after rewetting, whereas aquatic species are sensitive to drying. The underlying mechanisms such as the affected molecular components of the photosynthetic machinery are poorly understood in green algae. Therefore, modern approaches based on transcriptomics, proteomics, and/or metabolomics are urgently needed to better understand the molecular

  10. Desiccation stress and tolerance in green algae: consequences for ultrastructure, physiological and molecular mechanisms.

    PubMed

    Holzinger, Andreas; Karsten, Ulf

    2013-01-01

    Although most green algae typically occur in aquatic ecosystems, many species also live partly or permanently under aeroterrestrial conditions, where the cells are exposed to the atmosphere and hence regularly experience dehydration. The ability of algal cells to survive in an air-dried state is termed desiccation tolerance. The mechanisms involved in desiccation tolerance of green algae are still poorly understood, and hence the aim of this review is to summarize recent findings on the effects of desiccation and osmotic water loss. Starting from structural changes, physiological, and biochemical consequences of desiccation will be addressed in different green-algal lineages. The available data clearly indicate a range of strategies, which are rather different in streptophycean and non-streptophycean green algae. While members of the Trebouxiophyceae exhibit effective water loss-prevention mechanisms based on the biosynthesis and accumulation of particular organic osmolytes such as polyols, these compounds are so far not reported in representatives of the Streptophyta. In members of the Streptophyta such as Klebsormidium, the most striking observation is the appearance of cross-walls in desiccated samples, which are strongly undulating, suggesting a high degree of mechanical flexibility. This aids in maintaining structural integrity in the dried state and allows the cell to maintain turgor pressure for a prolonged period of time during the dehydration process. Physiological strategies in aeroterrestrial green algae generally include a rapid reduction of photosynthesis during desiccation, but also a rather quick recovery after rewetting, whereas aquatic species are sensitive to drying. The underlying mechanisms such as the affected molecular components of the photosynthetic machinery are poorly understood in green algae. Therefore, modern approaches based on transcriptomics, proteomics, and/or metabolomics are urgently needed to better understand the molecular

  11. Genome-wide analysis of tandem repeats in plants and green algae.

    PubMed

    Zhao, Zhixin; Guo, Cheng; Sutharzan, Sreeskandarajan; Li, Pei; Echt, Craig S; Zhang, Jie; Liang, Chun

    2014-01-10

    Tandem repeats (TRs) extensively exist in the genomes of prokaryotes and eukaryotes. Based on the sequenced genomes and gene annotations of 31 plant and algal species in Phytozome version 8.0 (http://www.phytozome.net/), we examined TRs in a genome-wide scale, characterized their distributions and motif features, and explored their putative biological functions. Among the 31 species, no significant correlation was detected between the TR density and genome size. Interestingly, green alga Chlamydomonas reinhardtii (42,059 bp/Mbp) and castor bean Ricinus communis (55,454 bp/Mbp) showed much higher TR densities than all other species (13,209 bp/Mbp on average). In the 29 land plants, including 22 dicots, 5 monocots, and 2 bryophytes, 5'-UTR and upstream intergenic 200-nt (UI200) regions had the first and second highest TR densities, whereas in the two green algae (C. reinhardtii and Volvox carteri) the first and second highest densities were found in intron and coding sequence (CDS) regions, respectively. In CDS regions, trinucleotide and hexanucleotide motifs were those most frequently represented in all species. In intron regions, especially in the two green algae, significantly more TRs were detected near the intron-exon junctions. Within intergenic regions in dicots and monocots, more TRs were found near both the 5' and 3' ends of genes. GO annotation in two green algae revealed that the genes with TRs in introns are significantly involved in transcriptional and translational processing. As the first systematic examination of TRs in plant and green algal genomes, our study showed that TRs displayed nonrandom distribution for both intragenic and intergenic regions, suggesting that they have potential roles in transcriptional or translational regulation in plants and green algae.

  12. Evaluation of sample extraction methods for proteomics analysis of green algae Chlorella vulgaris.

    PubMed

    Gao, Yan; Lim, Teck Kwang; Lin, Qingsong; Li, Sam Fong Yau

    2016-05-01

    Many protein extraction methods have been developed for plant proteome analysis but information is limited on the optimal protein extraction method from algae species. This study evaluated four protein extraction methods, i.e. direct lysis buffer method, TCA-acetone method, phenol method, and phenol/TCA-acetone method, using green algae Chlorella vulgaris for proteome analysis. The data presented showed that phenol/TCA-acetone method was superior to the other three tested methods with regards to shotgun proteomics. Proteins identified using shotgun proteomics were validated using sequential window acquisition of all theoretical fragment-ion spectra (SWATH) technique. Additionally, SWATH provides protein quantitation information from different methods and protein abundance using different protein extraction methods was evaluated. These results highlight the importance of green algae protein extraction method for subsequent MS analysis and identification. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Harvesting green algae from eutrophic reservoir by electroflocculation and post-use for biodiesel production.

    PubMed

    Valero, Enrique; Álvarez, Xana; Cancela, Ángeles; Sánchez, Ángel

    2015-01-01

    Each year there are more frequent blooms of green algae and cyanobacteria, representing a serious environmental problem of eutrophication. Electroflocculation (EF) was studied to harvest the algae which are present in reservoirs, as well as different factors which may influence on the effectiveness of the process: the voltage applied to the culture medium, run times, electrodes separation and natural sedimentation. Finally, the viability of its use to obtain biodiesel was studied by direct transesterification. The EF process carried out at 10V for 1min, with an electrode separation of 5.5cm and a height of 4cm in culture vessel, obtained a recovery efficiency greater than 95%, and octadecenoic and palmitic acids were obtained as the fatty acid methyl esters (FAMEs). EF is an effective method to harvest green algae during the blooms, obtaining the greatest amount of biomass for subsequent use as a source of biodiesel.

  14. Toxicity of 13 different antibiotics towards freshwater green algae Pseudokirchneriella subcapitata and their modes of action.

    PubMed

    Fu, Ling; Huang, Tao; Wang, Shuo; Wang, Xiaohong; Su, Limin; Li, Chao; Zhao, Yuanhui

    2017-02-01

    Although modes of action (MOAs) play a key role in the understanding of the toxic mechanism of chemicals, the MOAs have not been investigated for antibiotics to green algae. This paper is to discriminate excess toxicity from baseline level and investigate the MOAs of 13 different antibiotics to algae by using the determined toxicity values. Comparison of the toxicities shows that the inhibitors of protein synthesis to bacteria, such as azithromycin, doxycycline, florfenicol and oxytetracycline, exhibit significantly toxic effects to algae. On the other hand, the cell wall synthesis inhibitors, such as cefotaxime and amoxicillin, show relatively low toxic effects to the algae. The concentrations determined by HPLC indicate that quinocetone and amoxicillin can be easily photodegraded or hydrolyzed during the toxic tests. The toxic effects of quinocetone and amoxicillin to the algae are attributed to not only their parent compounds, but also their metabolites. Investigation on the mode of action shows that, except rifampicin, all the tested antibiotics exhibit excess toxicity to Pseudokirchneriella subcapitata (P. subcapitata). These antibiotics can be identified as reactive modes of action to the algae. They act as electrophilic mechanism of action to P. subcapitata. These results are valuable for the understanding of the toxic mechanism to algae.

  15. Drifting trajectories of green algae in the western Yellow Sea during the spring and summer of 2012

    NASA Astrophysics Data System (ADS)

    Bao, Min; Guan, Weibing; Yang, Yang; Cao, Zhenyi; Chen, Qi

    2015-09-01

    The northward drift of green algae (Ulva prolifera) from Subei Shoal in the western Yellow Sea, China, during the spring and summer of 2012, was investigated using satellite data and numerical modeling. Past studies have suggested that the green algae, documented offshore of Shandong province since 2007, originate in Subei Shoal region of the Yellow Sea. To test this hypothesis, drift bottles and satellite-tracked surface drifters were released from Subei Shoal and used to investigate the trajectories of green algae. Subei Shoal is characterized by complex bathymetry such as broad tidal flats and radial sand ridges. To identify processes that drive drift of the green algae around the shoal, a coastal ocean model based on the Finite Volume Coastal Ocean Model (FVCOM) was used. This model is forced by tides and surface winds, and has sufficient resolution to include tidal flats and sand ridges during both wetting and drying. The results of numerical experiments indicated that sand ridges limit the trajectory of particles. Without wind, particles scattered from their initial positions displayed a tendency to move northward, but were unable to move out of Subei Shoal. When a southerly wind was introduced to the model, particles traveled further north, out of the shallow waters. After leaving Subei Shoal, drifters remained limited by tide and topography until reaching 34°30.0‧N. North of 34°30.0‧N, 33% of the trajectory vectors can be explained by Ekman theory, and the remainder are probably controlled by the strong baroclinic processes in this area. For the six surface-following drifters deployed, the mean drift speed was 11.1 cm s-1 (288.8 km month-1), close to the speed observed for patches of U. prolifera. Numerical models and the results from drifter bottles demonstrated that green algae could leave Subei Shoal, but only when aided by a southerly wind. Satellite-tracked drifters provided strong evidence that if floating particles do leave Subei Shoal, they

  16. Sulfated phenolic acids from Dasycladales siphonous green algae.

    PubMed

    Kurth, Caroline; Welling, Matthew; Pohnert, Georg

    2015-09-01

    Sulfated aromatic acids play a central role as mediators of chemical interactions and physiological processes in marine algae and seagrass. Among others, Dasycladus vermicularis (Scopoli) Krasser 1898 uses a sulfated hydroxylated coumarin derivative as storage metabolite for a protein cross linker that can be activated upon mechanical disruption of the alga. We introduce a comprehensive monitoring technique for sulfated metabolites based on fragmentation patterns in liquid chromatography/mass spectrometry and applied it to Dasycladales. This allowed the identification of two new aromatic sulfate esters 4-(sulfooxy)phenylacetic acid and 4-(sulfooxy)benzoic acid. The two metabolites were synthesized to prove the mass spectrometry-based structure elucidation in co-injections. We show that both metabolites are transformed to the corresponding desulfated phenols by sulfatases of bacteria. In biofouling experiments with Escherichia coli and Vibrio natriegens the desulfated forms were more active than the sulfated ones. Sulfatation might thus represent a measure of detoxification that enables the algae to store inactive forms of metabolites that are activated by settling organisms and then act as defense. Copyright © 2015. Published by Elsevier Ltd.

  17. Oleosin of Subcellular Lipid Droplets Evolved in Green Algae1[W][OA

    PubMed Central

    Huang, Nan-Lan; Huang, Ming-Der; Chen, Tung-Ling L.; Huang, Anthony H.C.

    2013-01-01

    In primitive and higher plants, intracellular storage lipid droplets (LDs) of triacylglycerols are stabilized with a surface layer of phospholipids and oleosin. In chlorophytes (green algae), a protein termed major lipid-droplet protein (MLDP) rather than oleosin on LDs was recently reported. We explored whether MLDP was present directly on algal LDs and whether algae had oleosin genes and oleosins. Immunofluorescence microscopy revealed that MLDP in the chlorophyte Chlamydomonas reinhardtii was associated with endoplasmic reticulum subdomains adjacent to but not directly on LDs. In C. reinhardtii, low levels of a transcript encoding an oleosin-like protein (oleolike) in zygotes-tetrads and a transcript encoding oleosin in vegetative cells transferred to an acetate-enriched medium were found in transcriptomes and by reverse transcription-polymerase chain reaction. The C. reinhardtii LD fraction contained minimal proteins with no detectable oleolike or oleosin. Several charophytes (advanced green algae) possessed low levels of transcripts encoding oleosin but not oleolike. In the charophyte Spirogyra grevilleana, levels of oleosin transcripts increased greatly in cells undergoing conjugation for zygote formation, and the LD fraction from these cells contained minimal proteins, two of which were oleosins identified via proteomics. Because the minimal oleolike and oleosins in algae were difficult to detect, we tested their subcellular locations in Physcomitrella patens transformed with the respective algal genes tagged with a Green Fluorescent Protein gene and localized the algal proteins on P. patens LDs. Overall, oleosin genes having weak and cell/development-specific expression were present in green algae. We present a hypothesis for the evolution of oleosins from algae to plants. PMID:23391579

  18. The influence of extracellular compounds produced by selected Baltic cyanobacteria, diatoms and dinoflagellates on growth of green algae Chlorella vulgaris

    NASA Astrophysics Data System (ADS)

    Żak, Adam; Kosakowska, Alicja

    2015-12-01

    Secondary metabolites produced by bacteria, fungi, algae and plants could affect the growth and development of biological and agricultural systems. This natural process that occurs worldwide is known as allelopathy. The main goal of this work was to investigate the influence of metabolites obtained from phytoplankton monocultures on the growth of green algae Chlorella vulgaris. We selected 6 species occurring in the Baltic Sea from 3 different taxonomic groups: cyanobacteria (Aphanizomenon flos-aquae; Planktothrix agardhii), diatoms (Thalassiosira pseudonana; Chaetoceros wighamii) and dinoflagellates (Alexandrium ostenfeldii; Prorocentrum minimum). In this study we have demonstrated that some of selected organisms caused allelopathic effects against microalgae. Both the negative and positive effects of collected cell-free filtrates on C. vulgaris growth, chlorophyll a concentration and fluorescence parameters (OJIP, QY, NPQ) have been observed. No evidence has been found for the impact on morphology and viability of C. vulgaris cells.

  19. The occurrence and biosynthesis of gamma-linolenic acid in a blue-green alga,Spirulina platensis.

    PubMed

    Nichols, B W; Wood, B J

    1968-01-01

    The acyl-lipid and fatty acid composition of six blue-green algae, namely,Spirulina platensis, Myxosarcina chroococcoides, Chlorogloea fritschii, Anabaena cylindrica, Anabaena flos-aquae, and Mastigocladus laminosus is reported.All contain major proportions of mono-and digalactosyl diglyceride, sulfoquinovosyl diglyceride, and phosphatidyl glycerol, but none possess lecithin, phophatidyl ethanolamine, or phosphatidyl inositol. Trans-3-hexadecenoic acid was absent from all extracts.The analyses provide further evidence that there is no general chemical or physical requirement for any specific fatty acid in photosynthesis. S. platensis is unique among photoautotrophic organisms so far studied, containing major quantities of gamma-linolenic acid (6,9,12-octadecatrienoic acid). This acid is synthesized by the alga by direct desaturation of linoleic acid and is primarily located in the mono- and digalactosyl diglyceride fractions.The possible phylogenetic relationship betweenS. platensis and other plant forms is discussed.

  20. Effect propagation in a toxicokinetic/toxicodynamic model explains delayed effects on the growth of unicellular green algae Scenedesmus vacuolatus.

    PubMed

    Vogs, Carolina; Bandow, Nicole; Altenburger, Rolf

    2013-04-01

    Ecotoxicological standard tests assess toxic effects by exposing an organism to high concentrations over defined periods of time. To evaluate toxicity under field conditions such as fluctuating and pulsed exposures, process-based toxicokinetic/toxicodynamic (TK/TD) models may be used for extrapolation from the existing evidence. A TK/TD model was developed that simulates the effect on growth of the green algae Scenedesmus vacuolatus continuously exposed to the model chemicals norflurazon, triclosan, and N-phenyl-2-naphthylamine. A pharmacological time-response model describing the effects of anticancer treatments on cancer cell growth was adapted and modified to model the affected growth of synchronized algae cells. The TK/TD model simulates the temporal effect course by linking the ambient concentration of a chemical to the observable adverse effect via an internal concentration and a sequence of biological events in the organism. The parameters of the toxicodynamic model are related to the growth characteristics of algae cells, a no effect concentration, the chemical efficacy as well as the ability of recovery and repair, and the delay during damage propagation. The TK/TD model fits well to the observed algae growth. The effect propagation through cumulative cell damage explained the observed delayed responses better than just the toxicokinetics. The TK/TD model could facilitate the link between several effect levels within damage propagation, which prospectively may be helpful to model adverse outcome pathways and time-dependent mixture effects.

  1. From algae to angiosperms-inferring the phylogeny of green plants (Viridiplantae) from 360 plastid genomes.

    PubMed

    Ruhfel, Brad R; Gitzendanner, Matthew A; Soltis, Pamela S; Soltis, Douglas E; Burleigh, J Gordon

    2014-02-17

    Next-generation sequencing has provided a wealth of plastid genome sequence data from an increasingly diverse set of green plants (Viridiplantae). Although these data have helped resolve the phylogeny of numerous clades (e.g., green algae, angiosperms, and gymnosperms), their utility for inferring relationships across all green plants is uncertain. Viridiplantae originated 700-1500 million years ago and may comprise as many as 500,000 species. This clade represents a major source of photosynthetic carbon and contains an immense diversity of life forms, including some of the smallest and largest eukaryotes. Here we explore the limits and challenges of inferring a comprehensive green plant phylogeny from available complete or nearly complete plastid genome sequence data. We assembled protein-coding sequence data for 78 genes from 360 diverse green plant taxa with complete or nearly complete plastid genome sequences available from GenBank. Phylogenetic analyses of the plastid data recovered well-supported backbone relationships and strong support for relationships that were not observed in previous analyses of major subclades within Viridiplantae. However, there also is evidence of systematic error in some analyses. In several instances we obtained strongly supported but conflicting topologies from analyses of nucleotides versus amino acid characters, and the considerable variation in GC content among lineages and within single genomes affected the phylogenetic placement of several taxa. Analyses of the plastid sequence data recovered a strongly supported framework of relationships for green plants. This framework includes: i) the placement of Zygnematophyceace as sister to land plants (Embryophyta), ii) a clade of extant gymnosperms (Acrogymnospermae) with cycads + Ginkgo sister to remaining extant gymnosperms and with gnetophytes (Gnetophyta) sister to non-Pinaceae conifers (Gnecup trees), and iii) within the monilophyte clade (Monilophyta), Equisetales

  2. From algae to angiosperms–inferring the phylogeny of green plants (Viridiplantae) from 360 plastid genomes

    PubMed Central

    2014-01-01

    Background Next-generation sequencing has provided a wealth of plastid genome sequence data from an increasingly diverse set of green plants (Viridiplantae). Although these data have helped resolve the phylogeny of numerous clades (e.g., green algae, angiosperms, and gymnosperms), their utility for inferring relationships across all green plants is uncertain. Viridiplantae originated 700-1500 million years ago and may comprise as many as 500,000 species. This clade represents a major source of photosynthetic carbon and contains an immense diversity of life forms, including some of the smallest and largest eukaryotes. Here we explore the limits and challenges of inferring a comprehensive green plant phylogeny from available complete or nearly complete plastid genome sequence data. Results We assembled protein-coding sequence data for 78 genes from 360 diverse green plant taxa with complete or nearly complete plastid genome sequences available from GenBank. Phylogenetic analyses of the plastid data recovered well-supported backbone relationships and strong support for relationships that were not observed in previous analyses of major subclades within Viridiplantae. However, there also is evidence of systematic error in some analyses. In several instances we obtained strongly supported but conflicting topologies from analyses of nucleotides versus amino acid characters, and the considerable variation in GC content among lineages and within single genomes affected the phylogenetic placement of several taxa. Conclusions Analyses of the plastid sequence data recovered a strongly supported framework of relationships for green plants. This framework includes: i) the placement of Zygnematophyceace as sister to land plants (Embryophyta), ii) a clade of extant gymnosperms (Acrogymnospermae) with cycads + Ginkgo sister to remaining extant gymnosperms and with gnetophytes (Gnetophyta) sister to non-Pinaceae conifers (Gnecup trees), and iii) within the monilophyte clade

  3. Temporal and spatial distributions of green algae micro-propagules in the coastal waters of the Subei Shoal, China

    NASA Astrophysics Data System (ADS)

    Song, Wei; Li, Yan; Fang, Song; Wang, Zongling; Xiao, Jie; Li, Ruixiang; Fu, Mingzhu; Zhu, Mingyuan; Zhang, Xuelei

    2015-09-01

    The blooms of large-scale green tides in the Yellow Sea have become a focus of marine research in China. Micro-propagules, as the propagule source of green algae, played an important role in the formation of green tides. In this study, monthly surveys in the coastal area of the Subei Shoal were conducted from October 2010 to October 2011. The temporal and spatial distributions of green algae micro-propagules in the water column and sediment were investigated. Green algae micro-propagules were widely distributed in the waters and sediments throughout the year, and their distribution significantly corresponded to Porphyra aquaculture activities. The abundance of the micro-propagules decreased gradually from inshore to offshore. The average number of micro-propagules reached a maximum in late April and was low during the winter and summer. The source of the micro-propagules was the green algae attached to the Porphyra aquaculture rafts. The green algae micro-propagules might serve as the seed stock of the raft-attached green algae and provide the initial conditions for the formation of green tides.

  4. Grazing on green algae by the periwinkle Littorina littorea in the Wadden Sea

    NASA Astrophysics Data System (ADS)

    Wilhelmsen, U.; Reise, K.

    1994-06-01

    On sedimentary tidal flats in the Wadden Sea near the Island of Sylt, the periwinkle Littorina littorea occurred preferentially on clusters and beds of mussels and on shell beds (100 to 350 m-2), achieved moderate densities on green algal patches or mats (20 to 50 m-2), and remained rare on bare sediments (<5 m-2). Green algae covering>10% of sediment surface appeared in summer on approximately one third of the tidal zone, mainly in the upper and sheltered parts and almost never on mussel and shell beds. In feeding experiments, L. littorea ingested more of the dominant alge, Enteromorpha, than of Ulva, irrespective of whether or not algae were fresh or decaying. The tough thalli of Chaetomorpha were hardly consumed. Snails feeding on Enteromorpha produced fecal pellets from which new growth of Enteromorpha started. In the absence of periwinkles, Enteromorpha developed on mussels and the attached fucoids. Experimentally increased snail densities on sediments prevented green algal development, but the snails were unable to graze down established algal mats. It is concluded that natural densities of L. littorea hardly affect the ephemeral mass development of green algae on sediments. However, where the snails occur at high densities, i.e. on mussel beds, green algal development may be prevented.

  5. Algae.

    PubMed

    Raven, John A; Giordano, Mario

    2014-07-07

    Algae frequently get a bad press. Pond slime is a problem in garden pools, algal blooms can produce toxins that incapacitate or kill animals and humans and even the term seaweed is pejorative - a weed being a plant growing in what humans consider to be the wrong place. Positive aspects of algae are generally less newsworthy - they are the basis of marine food webs, supporting fisheries and charismatic marine megafauna from albatrosses to whales, as well as consuming carbon dioxide and producing oxygen. Here we consider what algae are, their diversity in terms of evolutionary origin, size, shape and life cycles, and their role in the natural environment and in human affairs.

  6. Origin of land plants: Do conjugating green algae hold the key?

    PubMed Central

    2011-01-01

    Background The terrestrial habitat was colonized by the ancestors of modern land plants about 500 to 470 million years ago. Today it is widely accepted that land plants (embryophytes) evolved from streptophyte algae, also referred to as charophycean algae. The streptophyte algae are a paraphyletic group of green algae, ranging from unicellular flagellates to morphologically complex forms such as the stoneworts (Charales). For a better understanding of the evolution of land plants, it is of prime importance to identify the streptophyte algae that are the sister-group to the embryophytes. The Charales, the Coleochaetales or more recently the Zygnematales have been considered to be the sister group of the embryophytes However, despite many years of phylogenetic studies, this question has not been resolved and remains controversial. Results Here, we use a large data set of nuclear-encoded genes (129 proteins) from 40 green plant taxa (Viridiplantae) including 21 embryophytes and six streptophyte algae, representing all major streptophyte algal lineages, to investigate the phylogenetic relationships of streptophyte algae and embryophytes. Our phylogenetic analyses indicate that either the Zygnematales or a clade consisting of the Zygnematales and the Coleochaetales are the sister group to embryophytes. Conclusions Our analyses support the notion that the Charales are not the closest living relatives of embryophytes. Instead, the Zygnematales or a clade consisting of Zygnematales and Coleochaetales are most likely the sister group of embryophytes. Although this result is in agreement with a previously published phylogenetic study of chloroplast genomes, additional data are needed to confirm this conclusion. A Zygnematales/embryophyte sister group relationship has important implications for early land plant evolution. If substantiated, it should allow us to address important questions regarding the primary adaptations of viridiplants during the conquest of land. Clearly

  7. Origin of land plants: do conjugating green algae hold the key?

    PubMed

    Wodniok, Sabina; Brinkmann, Henner; Glöckner, Gernot; Heidel, Andrew J; Philippe, Hervé; Melkonian, Michael; Becker, Burkhard

    2011-04-18

    The terrestrial habitat was colonized by the ancestors of modern land plants about 500 to 470 million years ago. Today it is widely accepted that land plants (embryophytes) evolved from streptophyte algae, also referred to as charophycean algae. The streptophyte algae are a paraphyletic group of green algae, ranging from unicellular flagellates to morphologically complex forms such as the stoneworts (Charales). For a better understanding of the evolution of land plants, it is of prime importance to identify the streptophyte algae that are the sister-group to the embryophytes. The Charales, the Coleochaetales or more recently the Zygnematales have been considered to be the sister group of the embryophytes However, despite many years of phylogenetic studies, this question has not been resolved and remains controversial. Here, we use a large data set of nuclear-encoded genes (129 proteins) from 40 green plant taxa (Viridiplantae) including 21 embryophytes and six streptophyte algae, representing all major streptophyte algal lineages, to investigate the phylogenetic relationships of streptophyte algae and embryophytes. Our phylogenetic analyses indicate that either the Zygnematales or a clade consisting of the Zygnematales and the Coleochaetales are the sister group to embryophytes. Our analyses support the notion that the Charales are not the closest living relatives of embryophytes. Instead, the Zygnematales or a clade consisting of Zygnematales and Coleochaetales are most likely the sister group of embryophytes. Although this result is in agreement with a previously published phylogenetic study of chloroplast genomes, additional data are needed to confirm this conclusion. A Zygnematales/embryophyte sister group relationship has important implications for early land plant evolution. If substantiated, it should allow us to address important questions regarding the primary adaptations of viridiplants during the conquest of land. Clearly, the biology of the Zygnematales

  8. Cryptochrome photoreceptors in green algae: Unexpected versatility of mechanisms and functions.

    PubMed

    Kottke, Tilman; Oldemeyer, Sabine; Wenzel, Sandra; Zou, Yong; Mittag, Maria

    2017-10-01

    Green algae have a highly complex and diverse set of cryptochrome photoreceptor candidates including members of the following subfamilies: plant, plant-like, animal-like, DASH and cryptochrome photolyase family 1 (CPF1). While some green algae encode most or all of them, others lack certain members. Here we present an overview about functional analyses of so far investigated cryptochrome photoreceptors from the green algae Chlamydomonas reinhardtii (plant and animal-like cryptochromes) and Ostreococcus tauri (CPF1) with regard to their biological significance and spectroscopic properties. Cryptochromes of both algae have been demonstrated recently to be involved to various extents in circadian clock regulation and in Chlamydomonas additionally in life cycle control. Moreover, CPF1 even performs light-driven DNA repair. The plant cryptochrome and CPF1 are UVA/blue light receptors, whereas the animal-like cryptochrome responds to almost the whole visible spectrum including red light. Accordingly, plant cryptochrome, animal-like cryptochrome and CPF1 differ fundamentally in their structural response to light as revealed by their visible and infrared spectroscopic signatures, and in the role of the flavin neutral radical acting as dark form or signaling state. Copyright © 2017 Elsevier GmbH. All rights reserved.

  9. A novel ether-linked phytol-containing digalactosylglycerolipid in the marine green alga, Ulva pertusa

    SciTech Connect

    Ishibashi, Yohei; Nagamatsu, Yusuke; Miyamoto, Tomofumi; Matsunaga, Naoyuki; Okino, Nozomu; Yamaguchi, Kuniko; Ito, Makoto

    2014-10-03

    Highlights: • Alkaline-resistant galactolipid, AEGL, was found in marine algae. • The sugar moiety of AEGL is identical to that of digalactosyldiacylglycerol. • AEGL is the first identified glycolipid that possesses an ether-linked phytol. • AEGL is ubiquitously distributed in green, red and brown marine algae. - Abstract: Galactosylglycerolipids (GGLs) and chlorophyll are characteristic components of chloroplast in photosynthetic organisms. Although chlorophyll is anchored to the thylakoid membrane by phytol (tetramethylhexadecenol), this isoprenoid alcohol has never been found as a constituent of GGLs. We here described a novel GGL, in which phytol was linked to the glycerol backbone via an ether linkage. This unique GGL was identified as an Alkaline-resistant and Endogalactosylceramidase (EGALC)-sensitive GlycoLipid (AEGL) in the marine green alga, Ulva pertusa. EGALC is an enzyme that is specific to the R-Galα/β1-6Galβ1-structure of galactolipids. The structure of U. pertusa AEGL was determined following its purification to 1-O-phytyl-3-O-Galα1-6Galβ1-sn-glycerol by mass spectrometric and nuclear magnetic resonance analyses. AEGLs were ubiquitously distributed in not only green, but also red and brown marine algae; however, they were rarely detected in terrestrial plants, eukaryotic phytoplankton, or cyanobacteria.

  10. PHYLOGENY OF THE CONJUGATING GREEN ALGAE BASED ON CHLOROPLAST AND MITOCHONDRIAL NUCLEOTIDE SEQUENCE DATA(1).

    PubMed

    Hall, John D; Karol, Kenneth G; McCourt, Richard M; Delwiche, Charles F

    2008-04-01

    The conjugating green algae represent a lineage of charophyte green algae known for their structural diversity and unusual mode of sexual reproduction, conjugation. These algae are ubiquitous in freshwater environments, where they are often important primary producers, but few studies have investigated evolutionary relationships in a molecular systematic context. A 109-taxon data set consisting of three gene fragments (two from the chloroplast and one from the mitochondrial genome) was used to estimate the phylogeny of the genera of the conjugating green algae. Maximum likelihood (ML), maximum parsimony (MP), and Bayesian inference (BI) were used to estimate relationships from the 4,047 alignable nucleotides. This study confirmed the polyphyly of the Zygnemataceae and Mesotaeniaceae with respect to one another. The Peniaceae were determined to be paraphyletic, and two genera traditionally classified among the Zygnematales appear to belong to the lineage that gave rise to the Desmidiales. Six genera, Euastrum, Cosmarium, Cylindrocystis, Mesotaenium, Spondylosium, and Staurodesmus, were polyphyletic in this analysis. These findings have important implications for the evolution of structural characteristics in the group and will require some taxonomic changes. More work will be required to delineate lineages of Zygnematales in particular and to identify structural synapomorphies for some of the newly identified clades. © 2008 Phycological Society of America.

  11. Identification of cypermethrin induced protein changes in green algae by iTRAQ quantitative proteomics.

    PubMed

    Gao, Yan; Lim, Teck Kwang; Lin, Qingsong; Li, Sam Fong Yau

    2016-04-29

    Cypermethrin (CYP) is one of the most widely used pesticides in large scale for agricultural and domestic purpose and the residue often seriously affects aquatic system. Environmental pollutant-induced protein changes in organisms could be detected by proteomics, leading to discovery of potential biomarkers and understanding of mode of action. While proteomics investigations of CYP stress in some animal models have been well studied, few reports about the effects of exposure to CYP on algae proteome were published. To determine CYP effect in algae, the impact of various dosages (0.001μg/L, 0.01μg/L and 1μg/L) of CYP on green algae Chlorella vulgaris for 24h and 96h was investigated by using iTRAQ quantitative proteomics technique. A total of 162 and 198 proteins were significantly altered after CYP exposure for 24h and 96h, respectively. Overview of iTRAQ results indicated that the influence of CYP on algae protein might be dosage-dependent. Functional analysis of differentially expressed proteins showed that CYP could induce protein alterations related to photosynthesis, stress responses and carbohydrate metabolism. This study provides a comprehensive view of complex mode of action of algae under CYP stress and highlights several potential biomarkers for further investigation of pesticide-exposed plant and algae.

  12. Relationship between water solubility of chlorobenzenes and their effects on a freshwater green alga

    SciTech Connect

    Wong, P.T.S.; Chau, Y.K.; Rhamey, J.S.; Docker, M.

    1984-01-01

    The effective concentrations of benzene and 12 chlorobenzenes that reduced 50% of the primary productivity (EC/sub 50/) of a freshwater green alga, Ankistrodesmus falcatus, were determined. Benzene was the least toxic chemical and the toxicity increased as the degree of chlorine substitution in the aromatic ring increased. No EC/sub 50/ value could be obtained for HCB. A quantitative relationship was found to exist between water solubility, lipophilicity and the EC/sub 50/. A good correlation was also observed between the EC/sub 50/ for this alga and other toxicity data for various aquatic biota.

  13. Mixotrophy in the terrestrial green alga Apatococcus lobatus (Trebouxiophyceae, Chlorophyta).

    PubMed

    Gustavs, Lydia; Schumann, Rhena; Karsten, Ulf; Lorenz, Maike

    2016-04-01

    The green microalga Apatococcus lobatus is widely distributed in terrestrial habitats throughout many climatic zones. It dominates green biofilms on natural and artificial substrata in temperate latitudes and is regarded as a key genus of obligate terrestrial consortia. Until now, its isolation, cultivation and application as a terrestrial model organism has been hampered by slow growth rates and low growth capacities. A mixotrophic culturing approach clearly enhanced the accumulation of biomass, thereby permitting the future application of A. lobatus in different types of bio-assays necessary for material and biofilm research. The ability of A. lobatus to grow mixotrophically is assumed as a competitive advantage in terrestrial habitats.

  14. [Evolutional relationships of endemic green algae Draparnaldioides simplex from Lake Baikal with nonbaicalian taxa of family Chaetoforaceae (Chlorophyta)].

    PubMed

    Mincheva, E V; Peretolchina, T E; Izhboldina, L A; Kravtsova, L S; Shcherbakov, D Iu

    2013-01-01

    Phylogenetic relationships between the endemic baicalian green algae Draparnaldioides simplex C. meyer et Skabitsch, 1976 and holarctic taxa of green algae were studied using the fragment of 18S rDNA and internal transcribed spacers ITS1 and ITS2 of nuclear DNA. We showed that the baicalian genus Draparnaldioides is a separate taxon. The genetic difference between Draparnaldioides and nonbaicalian taxa of the sister groups of the green algae are small enough to indicate relative youth of the genus Draparnaldioides and its recent radiation from a common ancestor with Draparnaldia and Chaetophora.

  15. The complete mitochondrial DNA sequences of Nephroselmis olivacea and Pedinomonas minor. Two radically different evolutionary patterns within green algae.

    PubMed Central

    Turmel, M; Lemieux, C; Burger, G; Lang, B F; Otis, C; Plante, I; Gray, M W

    1999-01-01

    Green plants appear to comprise two sister lineages, Chlorophyta (classes Chlorophyceae, Ulvophyceae, Trebouxiophyceae, and Prasinophyceae) and Streptophyta (Charophyceae and Embryophyta, or land plants). To gain insight into the nature of the ancestral green plant mitochondrial genome, we have sequenced the mitochondrial DNAs (mtDNAs) of Nephroselmis olivacea and Pedinomonas minor. These two green algae are presumptive members of the Prasinophyceae. This class is thought to include descendants of the earliest diverging green algae. We find that Nephroselmis and Pedinomonas mtDNAs differ markedly in size, gene content, and gene organization. Of the green algal mtDNAs sequenced so far, that of Nephroselmis (45,223 bp) is the most ancestral (minimally diverged) and occupies the phylogenetically most basal position within the Chlorophyta. Its repertoire of 69 genes closely resembles that in the mtDNA of Prototheca wickerhamii, a later diverging trebouxiophycean green alga. Three of the Nephroselmis genes (nad10, rpl14, and rnpB) have not been identified in previously sequenced mtDNAs of green algae and land plants. In contrast, the 25,137-bp Pedinomonas mtDNA contains only 22 genes and retains few recognizably ancestral features. In several respects, including gene content and rate of sequence divergence, Pedinomonas mtDNA resembles the reduced mtDNAs of chlamydomonad algae, with which it is robustly affiliated in phylogenetic analyses. Our results confirm the existence of two radically different patterns of mitochondrial genome evolution within the green algae. PMID:10488238

  16. MACROALGAL VOLUME: A SURROGATE FOR BIOMASS IN SOME GREEN ALGAE

    EPA Science Inventory

    Two green algal morphotypes, filamentous species (e.g., Chaetomorpha spp.) and flattened or tubular (e.g.,Ulva spp. and Enteromorpha spp.) were collected from 63 sites within the Yaquina Bay estuary (Newport, OR) and used to compare an in situ volumetric biomass estimator to the...

  17. MACROALGAL VOLUME: A SURROGATE FOR BIOMASS IN SOME GREEN ALGAE

    EPA Science Inventory

    Two green algal morphotypes, filamentous species (e.g., Chaetomorpha spp.) and flattened or tubular (e.g.,Ulva spp. and Enteromorpha spp.) were collected from 63 sites within the Yaquina Bay estuary (Newport, OR) and used to compare an in situ volumetric biomass estimator to the...

  18. The effect of low temperature on Antarctic endolithic green algae

    NASA Technical Reports Server (NTRS)

    Meyer, M. A.; Morris, G. J.; Friedmann, E. I.

    1988-01-01

    Laboratory experiments show that undercooling to about -5 degrees C occurs in colonized Beacon sandstones of the Ross Desert, Antarctica. High-frequency temperature oscillations between 5 degrees C and -5 degrees C or -10 degrees C (which occur in nature on the rock surface) did not damage Hemichloris antarctica. In a cryomicroscope, H. antarctica appeared to be undamaged after slow or rapid cooling to -50 degrees C. 14CO2 incorporation after freezing to -20 degrees C was unaffected in H. antarctica or in Trebouxia sp. but slightly depressed in Stichococcus sp. (isolated from a less extreme Antarctic habitat). These results suggest that the freezing regime in the Antarctic desert is not injurious to endolithic algae. It is likely that the freezing-point depression inside the rock makes available liquid water for metabolic activity at subzero temperatures. Freezing may occur more frequently on the rock surface and contribute to the abiotic nature of the surface.

  19. The effect of low temperature on Antarctic endolithic green algae

    NASA Technical Reports Server (NTRS)

    Meyer, M. A.; Morris, G. J.; Friedmann, E. I.

    1988-01-01

    Laboratory experiments show that undercooling to about -5 degrees C occurs in colonized Beacon sandstones of the Ross Desert, Antarctica. High-frequency temperature oscillations between 5 degrees C and -5 degrees C or -10 degrees C (which occur in nature on the rock surface) did not damage Hemichloris antarctica. In a cryomicroscope, H. antarctica appeared to be undamaged after slow or rapid cooling to -50 degrees C. 14CO2 incorporation after freezing to -20 degrees C was unaffected in H. antarctica or in Trebouxia sp. but slightly depressed in Stichococcus sp. (isolated from a less extreme Antarctic habitat). These results suggest that the freezing regime in the Antarctic desert is not injurious to endolithic algae. It is likely that the freezing-point depression inside the rock makes available liquid water for metabolic activity at subzero temperatures. Freezing may occur more frequently on the rock surface and contribute to the abiotic nature of the surface.

  20. Phylogenetic and morphological characterisation of the green algae infesting blue mussel Mytilus edulis in the North and South Atlantic oceans.

    PubMed

    Rodríguez, Francisco; Feist, Stephen W; Guillou, Laure; Harkestad, Lisbeth S; Bateman, Kelly; Renault, Tristan; Mortensen, Stein

    2008-09-24

    Blue mussels Mytilus edulis with shell deformations and green pustules containing parasitic algae were collected at 3 coastal sites (Burøy, Norway; Bockholm, Denmark; Goose Green, Falkland Islands). A comparative study, including mussel histopathology, algal morphology, ultrastructure and phylogenetic position was performed. Green pustules were mainly located in the posterior portion of the mantle and gonad tissues and the posterior adductor muscle. Electron microscopy confirmed the presence of algal cells with similar morphology to Coccomyxa parasitica. Algae were oval shaped with a single nucleus and chloroplast, 1 or 2 mitochondria and a dense granular cytoplasm with a lipid inclusion body, Golgi apparatus and small vesicles. Partial small subunit (SSU) rRNA phylogeny confirmed the inclusion of parasitic algae into the Coccomyxa clade. However, the sequence identity between almost full SSU rRNA sequences of parasitic algae and others in this clade yielded an unexpected result. Green algae from mussels were distant from C. parasitica Culture Collection of Algae and Protozoa (CCAP) strain 216/18 (94% identity), but very similar (99% identity) to C. glaronensis (a lichen endosymbiont) and green endophytes from the tree Ginkgo biloba. The CCAP strain 216/18 was a sister sequence to Nannochloris algae, far from the Coccomyxa clade. These results suggest a misidentification or outgrowth of the original CCAP strain 216/18 by a different 'Nannochloris-like' trebouxiophycean organism. In contrast, our sequences directly obtained from infested mussels could represent the true C. parasitica responsible for the green pustules in blue mussels.

  1. Effects of removing symbiotic green algae on the response of Hydra viridissima (Pallas 1776) to metals.

    PubMed

    Karntanut, W; Pascoe, D

    2005-03-01

    Hydra viridissima is distinctively green due to symbiotic algae within the endodermal cells. The current investigation was designed to see if these algae influenced the response of Hydra to pollutants, by comparing the toxicity of copper, cadmium, and zinc to both symbiotic and aposymbiotic (free of their endosymbiotic algae) H. viridissima. The results demonstrated that the toxicity of the metals was generally similar for both groups of Hydra. However, at the lowest copper concentrations there was a difference between the two group of polyps, with aposymbiotic animals dying at concentrations where symbiotic Hydra survived. The lowest observed effect concentrations were 0.0068 and 0.016 mg/L for aposymbiotic and symbiotic Hydra, respectively. It is suggested that the symbiotic Hydra derive benefits from the association that enable them to better tolerate the toxicant. This work demonstrated that experimental manipulation of symbionts can help to explain their complex interactions and the ways in which they respond to pollutants.

  2. Effects of DCMU on chlorophyll fluorescence ratio F685/F735 in marine red, brown and green algae

    NASA Astrophysics Data System (ADS)

    Wu, Bao-Gan; Zuo, Dong-Mei; Zang, Ru-Bo

    1996-03-01

    The chlorophyll fluorescence ratio F685/F735 in vivo can be a useful indicator for stress detection in higher plants and seaweeds. DCMU [3-(3,4-dichlorophenyl)-1, 1-dimethylurea] treatment influences this ratio. The effets of DCMU on F685/F735 of marine red, brown and green algae under excitation light of different wavelengths were investigated. In the brown algae, Laminaria japonica and Undaria pinnatifida, DCMU did not increase this ratio under blue light excitation but increased the ratio slightly under excitation by green light. For the red algae, Halymenia sinensis, DCMU increased the ratio markedly under both blue and green light excitation. The percentage increase could reach 50% (under green light excitation) and was due to unequal enhancement at the two emission maxima by DCMU. A fraction of chlorophyll which contributed to fluorescence in the 735 nm region was less sensitive to DCMU and was likely from photosystem I of red algae. In the green alga, Ulva pertusa, DCMU caused a slight increase in F685/F735 value under blue, green and red light. Green light excitation during DCMU treatment increased the ratio most (16%) but induced the lowest ratio in the control (without DCMU). It is proposed that a considerable fraction of fluorescence from the 735 nm region at room temperature may be emitted by the chlorophyll of photosystem I in red algae.

  3. Genome-wide characterization of genetic variation in the unicellular, green alga Chlamydomonas reinhardtii.

    PubMed

    Jang, Hyosik; Ehrenreich, Ian M

    2012-01-01

    Chlamydomonas reinhardtii is a model system for studying cilia, photosynthesis, and other core features of eukaryotes, and is also an emerging source of biofuels. Despite its importance to basic and applied biological research, the level and pattern of genetic variation in this haploid green alga has yet to be characterized on a genome-wide scale. To improve understanding of C. reinhardtii's genetic variability, we generated low coverage whole genome resequencing data for nearly all of the available isolates of this species, which were sampled from a number of sites in North America over the past ∼70 years. Based on the analysis of more than 62,000 single nucleotide polymorphisms, we identified two groups of isolates that represent geographical subpopulations of the species. We also found that measurements of genetic diversity were highly variable throughout the genome, in part due to technical factors. We studied the level and pattern of linkage disequilibrium (LD), and observed one chromosome that exhibits elevated LD. Furthermore, we detected widespread evidence of recombination across the genome, which implies that outcrossing occurs in natural populations of this species. In summary, our study provides multiple insights into the sequence diversity of C. reinhardtii that will be useful to future studies of natural genetic variation in this organism.

  4. Class XIII myosins from the green alga Acetabularia: driving force in organelle transport and tip growth?

    PubMed

    Vugrek, Oliver; Sawitzky, Heiko; Menzel, Diedrik

    2003-01-01

    The green alga Acetabularia cliftonii (Dasycladales) contains at least two myosin genes, which already have been assigned class XIII of the myosin superfamily (Cope et al., 1996, Structure 4: 969-987). Here we report a complete analysis of their gene structure and their corresponding transcripts Aclmyo1 and Aclmyo2. Despite promising Northern blot data no evidence for alternative splicing could be found. Dissecting the primary structure at complementary deoxyribonucleic acid (cDNA) level we found a myosin typical organization in head, neck and variable tail region. Most striking is the extremely short tail region of Aclmyo1 with only 18 residues and the maximum number of 7 IQ motifs in Aclmyo2. Probing Acetabularia protein extracts with an antibody raised to a synthetic peptide derived from the amino terminal region in Alcmyo1 showed cross-reactivity to a polypeptide with a molecular mass of approximately 100 kD. This corresponds to the predicted molecular weight of Aclmyo1, which is 106 kD as deduced from the amino acid sequence. Additionally, the same cross-reactive protein is capable of binding F-actin as indicated by a co-sedimentation assay. Confocal laser scanning microscopy with raised antibody revealed co-localization with organelles, the budding region of lateral whorls and the cell apex suggesting involvement of putative Acetabularia myosin in organelle transport and tip growth.

  5. [Phototaxis of the green algae: the new class of rhodopsin receptors].

    PubMed

    Govorunova, E G; Jung, K H; Sineshchekov, O A

    2004-01-01

    Photomotility behavior in green flagellate algae is mediated by rhodopsin-like receptors, which was initially suggested on the basis of physiological evidence. The cascade of rapid Ca(2+)-dependent electrical responses in the plasma membrane plays a key role in the signal transduction chain during both phototaxis and the photophobic response. The photoreceptor current through the plasma membrane is the earliest detectable event upon photoexcitation of the photoreceptors. Analysis of this current revealed that it consists of at least two components with different characteristics. Genes encoding two archaeal-type rhodopsins (type I rhodopsins) were recently identified in the genome of Chlamydomonas reinhardtii and named (Chlamydomonas Sensory Rhodopsins A and B CSRA and CSRB). The measurements of photoelectric and motor responses in genetic transformants of C. reinhardtii enriched in each of these receptor proteins showed that the two components of the photoreceptor current are mediated by the two rhodopsins, and that both CSRA and CSRB are involved in phototaxis and the photophobic response. The CSRA-mediated current dominates at high light intensities and contributes primarily to the photophobic response. The CSRB-initiated transduction involves an efficient amplification cascade and mediates the highly sensitive phototaxis at low light intensities. CSRA and CSRB expressed heterologously in oocytes of Xenopus laevis act as light-gated proton channels, although it is unclear whether this channel activity plays a functional role in the initiation of motor responses and/or occurs in the native system.

  6. Biosorptive removal of malachite green from aqueous solution using chemically modified brown marine alga Sargassum swartzii.

    PubMed

    Jerold, M; Sivasubramanian, V

    2017-02-01

    Sargassum swartzii, marine macro brown alga, showed a high malachite green (MG) biosorption capacity in batch mode of operation. The analytical evidence from Fourier transform infrared spectra confirmed the involvement of amine group in the biosorption of MG and electrostatic interaction type of mechanism was proposed to occur between the amine group of dye and the cationic MG dye solution. Scanning electron micrograph shows the morphological features and the attachment of dye onto the biosorbent. pH edge experiment shows that biosorption capacity was maximum at pH 10. The effect of biosorbent concentration, pH, temperature, adsorption time was studied for the biosorption of MG using S. swartzii. Langmuir, Freundlich and Temkin models were used to describe the isotherm data, of which Langmuir model described the isotherm data with high coefficient of determination R(2) = 0.999. The maximum dye uptake of 111.1 mg/g was reported at pH 10 based on Langmuir model. Kinetics and temperature profiles were evaluated and reported. Desorption study was carried out with 0.1 M HCl. Efforts were also made to continuously treat MG bearing wastewater using up-flow packed column. Investigations proved that S. swartzii is an excellent biosorbent for the sequestration of MG in aqueous media.

  7. Horizontal Gene Transfer of Phytochelatin Synthases from Bacteria to Extremophilic Green Algae.

    PubMed

    Olsson, Sanna; Penacho, Vanessa; Puente-Sánchez, Fernando; Díaz, Silvia; Gonzalez-Pastor, José Eduardo; Aguilera, Angeles

    2017-01-01

    Transcriptomic sequencing together with bioinformatic analyses and an automated annotation process led us to identify novel phytochelatin synthase (PCS) genes from two extremophilic green algae (Chlamydomonas acidophila and Dunaliella acidophila). These genes are of intermediate length compared to known PCS genes from eukaryotes and PCS-like genes from prokaryotes. A detailed phylogenetic analysis gives new insight into the complicated evolutionary history of PCS genes and provides evidence for multiple horizontal gene transfer events from bacteria to eukaryotes within the gene family. A separate subgroup containing PCS-like genes within the PCS gene family is not supported since the PCS genes are monophyletic only when the PCS-like genes are included. The presence and functionality of the novel genes in the organisms were verified by genomic sequencing and qRT-PCR. Furthermore, the novel PCS gene in Chlamydomonas acidophila showed very strong induction by cadmium. Cloning and expression of the gene in Escherichia coli clearly improves its cadmium resistance. The gene in Dunaliella was not induced, most likely due to gene duplication.

  8. Chlapsin, a chloroplastidial aspartic proteinase from the green algae Chlamydomonas reinhardtii.

    PubMed

    Almeida, Carla Malaquias; Pereira, Cláudia; da Costa, Diana Soares; Pereira, Susana; Pissarra, José; Simões, Isaura; Faro, Carlos

    2012-07-01

    Aspartic proteinases have been extensively characterized in land plants but up to now no evidences for their presence in green algae group have yet been reported in literature. Here we report on the identification of the first (and only) typical aspartic proteinase from Chlamydomonas reinhardtii. This enzyme, named chlapsin, was shown to maintain the primary structure organization of typical plant aspartic proteinases but comprising distinct features, such as similar catalytic motifs DTG/DTG resembling those from animal and microbial counterparts, and an unprecedentedly longer plant specific insert domain with an extra segment of 80 amino acids, rich in alanine residues. Our results also demonstrated that chlapsin accumulates in Chlamydomonas chloroplast bringing this new enzyme to a level of uniqueness among typical plant aspartic proteinases. Chlapsin was successfully expressed in Escherichia coli and it displayed the characteristic enzymatic properties of typical aspartic proteinases, like optimum activity at acidic pH and complete inhibition by pepstatin A. Another difference to plant aspartic proteinases emerged as chlapsin was produced in an active form without its putative prosegment domain. Moreover, recombinant chlapsin showed a restricted enzymatic specificity and a proteolytic activity influenced by the presence of redox agents and nucleotides, further differentiating it from typical plant aspartic proteinases and anticipating a more specialized/regulated function for this Chlamydomonas enzyme. Taken together, our results revealed a pattern of complexity for typical plant aspartic proteinases in what concerns sequence features, localization and biochemical properties, raising new questions on the evolution and function of this vast group of plant enzymes.

  9. Laccase-like enzyme activities from chlorophycean green algae with potential for bioconversion of phenolic pollutants.

    PubMed

    Otto, Benjamin; Beuchel, Carl; Liers, Christiane; Reisser, Werner; Harms, Hauke; Schlosser, Dietmar

    2015-06-01

    In order to explore the abundance and potential environmental functions of green algal laccases, we screened various algae for extracellular laccase-like activities, characterized basic features of these activities in selected species and exemplarily studied the transformation of environmental pollutants and complex natural compounds by the laccase of Tetracystis aeria. Oxidation of the classical laccase substrate ABTS was found to be widespread in chlorophycean algae. The oxidation activity detected in members of the 'Scenedesmus' clade was caused by an unknown thermostable low-molecular-mass compound. In contrast, species of the Moewusinia, including Chlamydomonas moewusii and T. aeria, excreted putative 'true' laccases. Phenolic substrates were oxidized by these enzymes optimally at neutral to alkaline pH. The Tetracystis laccase efficiently transformed bisphenol A, 17α-ethinylestradiol, nonylphenol and triclosan in the presence of ABTS as redox mediator, while anthracene, veratrylalcohol and adlerol were not attacked. Lignosulfonate and humic acid underwent slight (de)polymerization reactions in the presence of the laccase and mediator(s), probably involving the oxidation of phenolic constituents. Possible natural functions of the enzymes, such as the synthesis of complex polymers or detoxification processes, may assist the survival of the algae in adverse environments. In contaminated surface waters, laccase-producing green algae might contribute to the environmental breakdown of phenolic pollutants. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  10. A MOLECULAR PHYLOGENY OF ACROCHAETE AND OTHER ENDOPHYTIC GREEN ALGAE (ULVALES, CHLOROPHYTA)(1).

    PubMed

    Rinkel, Barbara E; Hayes, Paul; Gueidan, Cécile; Brodie, Juliet

    2012-08-01

    A molecular phylogeny was reconstructed from a culture collection of >150 isolates of epi-endophytic and endophytic green algae, based on nucleotide sequences of the plastid tufA and nuclear ITS2 loci. The cultures were isolated from a variety of algal hosts, notably the red algae Chondrus crispus, Mastocarpus stellatus, and Osmundea species, and the brown algae Chorda filum and Fucus serratus. The phylogeny revealed that in the Ulvales the majority of isolates fell into Acrochaete (Ulvellaceae), Ulva (Ulvaceae), Bolbocoleon (Bolbocoleaceae), and at least two unknown genera provisionally assigned to the Kornmanniaceae. Acrochaete was monophyletic. The genus was also more specious than previously described with 12 species, including up to six new species awaiting formal description. Isolates identified as Acrochaete repens, the type species of the genus, were polyphyletic. The remainder of the isolates were placed in the Ulotrichales. The results confirm that the endophytic habit supports a broad diversity of algal taxa and suggest that blade formation is a relatively recent innovation within the green algae. © 2012 Phycological Society of America.

  11. The adsorption potential and recovery of thallium using green micro-algae from eutrophic water sources.

    PubMed

    Birungi, Z S; Chirwa, E M N

    2015-12-15

    Thallium (Tl) is a highly volatile and toxic heavy metal regarded to cause pollution even at very low concentrations of several parts per million. Despite the extremely high risk of Tl in the environment, limited information on removal/recovery exists. The study focussed on the use of green algae to determine the sorption potential and recovery of Tl. From the study, removal efficiency was achieved at 100% for lower concentrations of ≥150 mg/L of Tl. At higher concentrations in a range of 250-500 mg/L, the performance of algae was still higher with sorption capacity (qmax) between 830 and 1000 mg/g. Generally, Chlorella vulgaris was the best adsorbent with a high qmax and lower affinity of 1000 mg/g and 1.11 L/g, respectively. When compared to other studies on Tl adsorption, the tested algae showed a better qmax than most adsorbents. The kinetic studies showed better correlation co-efficient of ≤0.99 for Pseudo-second order model than the first order model. Recovery was achieved highest for C. vulgaris using nitric acid at 93.3%. The strongest functional groups responsible for Tl binding on the algal cell wall were carboxyl and phenols. Green algae from freshwater bodies showed significant potential for Tl removal/recovery from industrial wastewater. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Strong tolerance of blue-green alga Microcystis flos-aquae to very high pressure

    NASA Astrophysics Data System (ADS)

    Ono, F.; Nishihira, N.; Hada, Y.; Mori, Y.; Takarabe, K.; Saigusa, M.; Matsushima, Y.; Yamazaki, D.; Ito, E.

    2015-09-01

    It was shown in our previous reports that a few spores of moss Venturiella could tolerate the very high pressure of 20 GPa for 30 min and germinated a protonema to the length of 30 μm. However, these spores did not grow any further, and disappeared at around 30 days of incubation after seeded. On the other hand, colonies of blue-green alga Microcystis flos-aquae came to appear about 76 days after the moss spores were seeded. Many of these colonies appeared at the places where the moss spores had disappeared. These colonies were formed by the algae that had adhered to the spore cases of the moss and survived after exposure to the very high pressure of 20 GPa. Though the appearance of the colonies of high pressure exposed algae was delayed by about 50 days compared with that of the control group which was not exposed to high pressure, there seems no difference in their shape and color from those of the control group. The pressure tolerance of blue-green alga is found to be enormously strong, and it can survive after exposure to the high pressure which corresponds to the depth of about 550-600 km from the surface of the Earth, just above the lower mantle.

  13. Biosynthesis of phytoquinones. Homogentisic acid: a precursor of plastoquinones, tocopherols and α-tocopherolquinone in higher plants, green algae and blue–green algae

    PubMed Central

    Whistance, G. R.; Threlfall, D. R.

    1970-01-01

    1. By means of 14C tracer experiments and isotope competition experiments the roles of d-tyrosine, p-hydroxyphenylpyruvic acid, p-hydroxyphenylacetic acid, phenylacetic acid, homogentisic acid and homoarbutin (2-methylquinol 4-β-d-glucoside) in the biosynthesis of plastoquinones, tocopherols and α-tocopherolquinone by maize shoots was investigated. It was established that d-tyrosine, p-hydroxyphenylpyruvic acid and homogentisic acid can all be utilized for this purpose, whereas p-hydroxyphenylacetic acid, phenylacetic acid and homoarbutin cannot. Studies on the mode of incorporation of d-tyrosine, p-hydroxyphenylpyruvic acid and homogentisic acid showed that their nuclear carbon atoms and the side-chain carbon atom adjacent to the nucleus give rise (as a C6-C1 unit) to the p-benzoquinone rings and nuclear methyl groups (one in each case) of plastoquinone-9 and α-tocopherolquinone and the aromatic nuclei and nuclear methyl groups (one in each case) of γ-tocopherol and α-tocopherol. 2. By using [14C]-homogentisic acid it has been shown that homogentisic acid is also a precursor of plastoquinone, tocopherols and α-tocopherolquinone in the higher plants Lactuca sativa and Rumex sanguineus, the green algae Chlorella pyrenoidosa and Euglena gracilis and the blue–green alga Anacystis nidulans. PMID:4986835

  14. Ulvan, a sulfated polysaccharide from green algae, activates plant immunity through the jasmonic acid signaling pathway.

    PubMed

    Jaulneau, Valérie; Lafitte, Claude; Jacquet, Christophe; Fournier, Sylvie; Salamagne, Sylvie; Briand, Xavier; Esquerré-Tugayé, Marie-Thérèse; Dumas, Bernard

    2010-01-01

    The industrial use of elicitors as alternative tools for disease control needs the identification of abundant sources of them. We report on an elicitor obtained from the green algae Ulva spp. A fraction containing most exclusively the sulfated polysaccharide known as ulvan-induced expression of a GUS gene placed under the control of a lipoxygenase gene promoter. Gene expression profiling was performed upon ulvan treatments on Medicago truncatula and compared to phytohormone effects. Ulvan induced a gene expression signature similar to that observed upon methyl jasmonate treatment (MeJA). Involvement of jasmonic acid (JA) in ulvan response was confirmed by detecting induction of protease inhibitory activity and by hormonal profiling of JA, salicylic acid (SA) and abscisic acid (ABA). Ulvan activity on the hormonal pathway was further consolidated by using Arabidopsis hormonal mutants. Altogether, our results demonstrate that green algae are a potential reservoir of ulvan elicitor which acts through the JA pathway.

  15. Growth of Legionella pneumophila in association with blue-green algae (Cyanobacteria)

    SciTech Connect

    Tison, D.L.; Pope, D.H.; Cherry, W.B.; Fliermans, C.B.

    1980-02-01

    Legionella pneumophila (Legionnaires disease bacterium) of serogroup 1 was isolated from an algal-bacterial mat community growing at 45/sup 0/C in a man-made thermal effluent. This isolate was grown in mineral salts medium at 45/sup 0/C in association with the blue-green alga (cyanobacterium) Fischerella sp. over a pH range of 6.9 to 7.6. L. pneumophila was apparently using algal extracellular products as its carbon and energy sources. These observations indicate that the temperature, pH, and nutritional requirements of L. pneumophila are not as stringent as those previously observed when cultured on complex media. This association between L. pneumophila and certain blue-green algae suggests an explanation for the apparent widespread distribution of the bacterium in nature.

  16. Ulvan, a Sulfated Polysaccharide from Green Algae, Activates Plant Immunity through the Jasmonic Acid Signaling Pathway

    PubMed Central

    Jaulneau, Valérie; Lafitte, Claude; Jacquet, Christophe; Fournier, Sylvie; Salamagne, Sylvie; Briand, Xavier; Esquerré-Tugayé, Marie-Thérèse; Dumas, Bernard

    2010-01-01

    The industrial use of elicitors as alternative tools for disease control needs the identification of abundant sources of them. We report on an elicitor obtained from the green algae Ulva spp. A fraction containing most exclusively the sulfated polysaccharide known as ulvan-induced expression of a GUS gene placed under the control of a lipoxygenase gene promoter. Gene expression profiling was performed upon ulvan treatments on Medicago truncatula and compared to phytohormone effects. Ulvan induced a gene expression signature similar to that observed upon methyl jasmonate treatment (MeJA). Involvement of jasmonic acid (JA) in ulvan response was confirmed by detecting induction of protease inhibitory activity and by hormonal profiling of JA, salicylic acid (SA) and abscisic acid (ABA). Ulvan activity on the hormonal pathway was further consolidated by using Arabidopsis hormonal mutants. Altogether, our results demonstrate that green algae are a potential reservoir of ulvan elicitor which acts through the JA pathway. PMID:20445752

  17. ULTRASTRUCTURE OF MITOSIS AND CYTOKINESIS IN THE MULTINUCLEATE GREEN ALGA ACROSIPHONIA

    PubMed Central

    Hudson, Peggy R.; Waaland, J. Robert

    1974-01-01

    The processes of mitosis and cytokinesis in the multinucleate green alga Acrosiphonia have been examined in the light and electron microscopes. The course of events in division includes thickening of the chloroplast and migration of numerous nuclei and other cytoplasmic incusions to form a band in which mitosis occurs, while other nuclei in the same cell but not in the band do not divide. Centrioles and microtubules are associated with migrated and dividing nuclei but not with nonmigrated, nondividing nuclei. Cytokinesis is accomplished in the region of the band, by means of an annular furrow which is preceded by a hoop of microtubules. No other microtubules are associated with the furrow. Characteristics of nuclear and cell division in Acrosiphonia are compared with those of other multinucleate cells and with those of other green algae. PMID:4139161

  18. When the lights go out: the evolutionary fate of free-living colorless green algae.

    PubMed

    Figueroa-Martinez, Francisco; Nedelcu, Aurora M; Smith, David R; Adrian, Reyes-Prieto

    2015-05-01

    The endosymbiotic origin of plastids was a launching point for eukaryotic evolution. The autotrophic abilities bestowed by plastids are responsible for much of the eukaryotic diversity we observe today. But despite its many advantages, photosynthesis has been lost numerous times and in disparate lineages throughout eukaryote evolution. For example, among green algae, several groups have lost photosynthesis independently and in response to different selective pressures; these include the parasitic/pathogenic trebouxiophyte genera Helicosporidium and Prototheca, and the free-living chlamydomonadalean genera Polytomella and Polytoma. Here, we examine the published data on colorless green algae and argue that investigations into the different evolutionary routes leading to their current nonphotosynthetic lifestyles provide exceptional opportunities to understand the ecological and genomic factors involved in the loss of photosynthesis.

  19. Esfenvalerate toxicity to the cladoceran Ceriodaphnia dubia in the presence of green algae, Pseudokirchneriella subcapitata.

    PubMed

    Brander, Susanne M; Mosser, Christopher M; Geist, Juergen; Hladik, Michelle L; Werner, Inge

    2012-11-01

    The presence of phytoplankton, like other particulate organic matter, can interfere with the effects of hydrophobic contaminants such as pyrethroid pesticides. However, the reduction or elimination of toxicity by algae added as food during testing is not taken into account in standard US EPA whole effluent toxicity (WET) zooplankton tests. On the other hand, WET test conditions may overestimate toxicity of such compounds in highly productive surface waters with high concentrations of detritus and other particulate matter. In addition, WET tests do not measure impaired swimming ability or predator avoidance behavior as an indicator of increased mortality risk. This study used a modified version of the US EPA WET Ceriodaphnia dubia acute test to investigate the effects of phytoplankton on toxicity of the pyrethroid insecticide, esfenvalerate. Animals were exposed simultaneously to different concentrations of esfenvalerate and green algae (Pseudokirchneriella subcapitata). Mortality and predation risk were recorded after 4 and 24 h. Algae at or below concentrations specified in the WET protocol significantly reduced mortality. Regardless, organisms exposed to esfenvalerate were unable to avoid simulated predation in the presence of algae at any concentration. After 12 h, esfenvalerate adsorbed to algae represented 68-99 % of the total amount recovered. The proportion of algae-bound insecticide increased with algal concentration indicating that conclusions drawn from toxicity tests in which algae are added as food must be interpreted with caution as the dissolved fraction of such hydrophobic contaminants is reduced. Additionally, our results strongly suggest that the EPA should consider adding ecologically-relevant endpoints such as swimming behavior to standard WET protocols.

  20. A Green Algae Mixture of Scenedesmus and Schroederiella Attenuates Obesity-Linked Metabolic Syndrome in Rats

    PubMed Central

    Kumar, Senthil Arun; Magnusson, Marie; Ward, Leigh C.; Paul, Nicholas A.; Brown, Lindsay

    2015-01-01

    This study investigated the responses to a green algae mixture of Scenedesmus dimorphus and Schroederiella apiculata (SC) containing protein (46.1% of dry algae), insoluble fibre (19.6% of dry algae), minerals (3.7% of dry algae) and omega-3 fatty acids (2.8% of dry algae) as a dietary intervention in a high carbohydrate, high fat diet-induced metabolic syndrome model in four groups of male Wistar rats. Two groups were fed with a corn starch diet containing 68% carbohydrates as polysaccharides, while the other two groups were fed a diet high in simple carbohydrates (fructose and sucrose in food, 25% fructose in drinking water, total 68%) and fats (saturated and trans fats from beef tallow, total 24%). High carbohydrate, high fat-fed rats showed visceral obesity with hypertension, insulin resistance, cardiovascular remodelling, and nonalcoholic fatty liver disease. SC supplementation (5% of food) lowered total body and abdominal fat mass, increased lean mass, and attenuated hypertension, impaired glucose and insulin tolerance, endothelial dysfunction, infiltration of inflammatory cells into heart and liver, fibrosis, increased cardiac stiffness, and nonalcoholic fatty liver disease in the high carbohydrate, high fat diet-fed rats. This study suggests that the insoluble fibre or protein in SC helps reverse diet-induced metabolic syndrome. PMID:25875119

  1. A green algae mixture of Scenedesmus and Schroederiella attenuates obesity-linked metabolic syndrome in rats.

    PubMed

    Kumar, Senthil Arun; Magnusson, Marie; Ward, Leigh C; Paul, Nicholas A; Brown, Lindsay

    2015-04-14

    This study investigated the responses to a green algae mixture of Scenedesmus dimorphus and Schroederiella apiculata (SC) containing protein (46.1% of dry algae), insoluble fibre (19.6% of dry algae), minerals (3.7% of dry algae) and omega-3 fatty acids (2.8% of dry algae) as a dietary intervention in a high carbohydrate, high fat diet-induced metabolic syndrome model in four groups of male Wistar rats. Two groups were fed with a corn starch diet containing 68% carbohydrates as polysaccharides, while the other two groups were fed a diet high in simple carbohydrates (fructose and sucrose in food, 25% fructose in drinking water, total 68%) and fats (saturated and trans fats from beef tallow, total 24%). High carbohydrate, high fat-fed rats showed visceral obesity with hypertension, insulin resistance, cardiovascular remodelling, and nonalcoholic fatty liver disease. SC supplementation (5% of food) lowered total body and abdominal fat mass, increased lean mass, and attenuated hypertension, impaired glucose and insulin tolerance, endothelial dysfunction, infiltration of inflammatory cells into heart and liver, fibrosis, increased cardiac stiffness, and nonalcoholic fatty liver disease in the high carbohydrate, high fat diet-fed rats. This study suggests that the insoluble fibre or protein in SC helps reverse diet-induced metabolic syndrome.

  2. Production of Recombinant Proteins in the Chloroplast of the Green Alga Chlamydomonas reinhardtii.

    PubMed

    Guzmán-Zapata, Daniel; Macedo-Osorio, Karla Soledad; Almaraz-Delgado, Alma Lorena; Durán-Figueroa, Noé; Badillo-Corona, Jesus Agustín

    2016-01-01

    Chloroplast transformation in the green algae Chlamydomonas reinhardtii can be used for the production of valuable recombinant proteins. Here, we describe chloroplast transformation of C. reinhardtii followed by protein detection. Genes of interest integrate stably by homologous recombination into the chloroplast genome following introduction by particle bombardment. Genes are inherited and expressed in lines recovered after selection in the presence of an antibiotic. Recombinant proteins can be detected by conventional techniques like immunoblotting and purified from liquid cultures.

  3. Viruses of eukaryotic green algae. Final technical report, June 1, 1989--February 1, 1992

    SciTech Connect

    Van Etten, J.L.

    1992-12-31

    We have isolated and partially characterized many large, polyhedral, DNA containing, plaque forming viruses which infect certain unicellular, eukaryotic, chlorella-like green algae. These viruses have several unique features, including the fact that they code for DNA site-specific endonucleases and DNA methyltransferases. The primary objectives of this study were to identify, clone, and characterize some of the virus-encoded DNA methyltransferases and DNA restriction endonucleases in order to understand their biological function.

  4. Viruses of eukaryotic green algae. Progress report, August 1, 1982-July 1, 1984

    SciTech Connect

    Van Etten, J.L.

    1984-01-01

    The virus, PBCV-1, which infects the eukaryotic, green alga, Chlorella-NC64A has been characterized and we have begun to look at detailed events associated with its growth cycle. In addition, we have recently discovered other dsDNA viruses from natural sources which replicate in Chlorella NC64A. These viruses can be distinguished from PBCV-1 and from each other by plaque morphology, DNA restriction patterns, and by their resistance to certain restriction endonucleases.

  5. The xanthophyll cycle and NPQ in diverse desert and aquatic green algae.

    PubMed

    Lunch, Claire K; Lafountain, Amy M; Thomas, Suzanne; Frank, Harry A; Lewis, Louise A; Cardon, Zoe G

    2013-07-01

    It has long been suspected that photoprotective mechanisms in green algae are similar to those in seed plants. However, exceptions have recently surfaced among aquatic and marine green algae in several taxonomic classes. Green algae are highly diverse genetically, falling into 13 named classes, and they are diverse ecologically, with many lineages including members from freshwater, marine, and terrestrial habitats. Genetically similar species living in dramatically different environments are potentially a rich source of information about variations in photoprotective function. Using aquatic and desert-derived species from three classes of green algae, we examined the induction of photoprotection under high light, exploring the relationship between nonphotochemical quenching and the xanthophyll cycle. In liquid culture, behavior of aquatic Entransia fimbriata (Klebsormidiophyceae) generally matched patterns observed in seed plants. Nonphotochemical quenching was lowest after overnight dark adaptation, increased with light intensity, and the extent of nonphotochemical quenching correlated with the extent of deepoxidation of xanthophyll cycle pigments. In contrast, overnight dark adaptation did not minimize nonphotochemical quenching in the other species studied: desert Klebsormidium sp. (Klebsormidiophyceae), desert and aquatic Cylindrocystis sp. (Zygnematophyceae), and desert Stichococcus sp. (Trebouxiophyceae). Instead, exposure to low light reduced nonphotochemical quenching below dark-adapted levels. De-epoxidation of xanthophyll cycle pigments paralleled light-induced changes in nonphotochemical quenching for species within Klebsormidiophyceae and Trebouxiophyceae, but not Zygnematophyceae. Inhibition of violaxanthin-zeaxanthin conversion by dithiothreitol reduced high-light-associated nonphotochemical quenching in all species (Zygnematophyceae the least), indicating that zeaxanthin can contribute to photoprotection as in seed plants but to different extents

  6. Predicting the Physiological Role of Circadian Metabolic Regulation in the Green Alga Chlamydomonas reinhardtii

    PubMed Central

    Voytsekh, Olga; Mittag, Maria; Schuster, Stefan

    2011-01-01

    Although the number of reconstructed metabolic networks is steadily growing, experimental data integration into these networks is still challenging. Based on elementary flux mode analysis, we combine sequence information with metabolic pathway analysis and include, as a novel aspect, circadian regulation. While minimizing the need of assumptions, we are able to predict changes in the metabolic state and can hypothesise on the physiological role of circadian control in nitrogen metabolism of the green alga Chlamydomonas reinhardtii. PMID:21887226

  7. Evolutionary trajectories explain the diversified evolution of isogamy and anisogamy in marine green algae.

    PubMed

    Togashi, Tatsuya; Bartelt, John L; Yoshimura, Jin; Tainaka, Kei-ichi; Cox, Paul Alan

    2012-08-21

    The evolution of anisogamy (the production of gametes of different size) is the first step in the establishment of sexual dimorphism, and it is a fundamental phenomenon underlying sexual selection. It is believed that anisogamy originated from isogamy (production of gametes of equal size), which is considered by most theorists to be the ancestral condition. Although nearly all plant and animal species are anisogamous, extant species of marine green algae exhibit a diversity of mating systems including both isogamy and anisogamy. Isogamy in marine green algae is of two forms: isogamy with extremely small gametes and isogamy with larger gametes. Based on disruptive selection for fertilization success and zygote survival (theory of Parker, Baker, and Smith), we explored how environmental changes can contribute to the evolution of such complex mating systems by analyzing the stochastic process in the invasion simulations of populations of differing gamete sizes. We find that both forms of isogamy can evolve from other isogamous ancestors through anisogamy. The resulting dimensionless analysis accounts for the evolutionary stability of all types of mating systems in marine green algae, even in the same environment. These results imply that evolutionary trajectories as well as the optimality of gametes/zygotes played an important role in the evolution of gamete size.

  8. Evolutionary trajectories explain the diversified evolution of isogamy and anisogamy in marine green algae

    PubMed Central

    Togashi, Tatsuya; Bartelt, John L.; Yoshimura, Jin; Tainaka, Kei-ichi; Cox, Paul Alan

    2012-01-01

    The evolution of anisogamy (the production of gametes of different size) is the first step in the establishment of sexual dimorphism, and it is a fundamental phenomenon underlying sexual selection. It is believed that anisogamy originated from isogamy (production of gametes of equal size), which is considered by most theorists to be the ancestral condition. Although nearly all plant and animal species are anisogamous, extant species of marine green algae exhibit a diversity of mating systems including both isogamy and anisogamy. Isogamy in marine green algae is of two forms: isogamy with extremely small gametes and isogamy with larger gametes. Based on disruptive selection for fertilization success and zygote survival (theory of Parker, Baker, and Smith), we explored how environmental changes can contribute to the evolution of such complex mating systems by analyzing the stochastic process in the invasion simulations of populations of differing gamete sizes. We find that both forms of isogamy can evolve from other isogamous ancestors through anisogamy. The resulting dimensionless analysis accounts for the evolutionary stability of all types of mating systems in marine green algae, even in the same environment. These results imply that evolutionary trajectories as well as the optimality of gametes/zygotes played an important role in the evolution of gamete size. PMID:22869736

  9. Heterotrimeric G proteins in green algae: an early innovation in the evolution of the plant lineage.

    PubMed

    Hackenberg, Dieter; Pandey, Sona

    2014-01-01

    Heterotrimeric G-proteins (G-proteins, hereafter) are important signaling components in all eukaryotes. The absence of these proteins in the sequenced genomes of Chlorophyaceaen green algae has raised questions about their evolutionary origin and prevalence in the plant lineage. The existence of G-proteins has often been correlated with the acquisition of embryophytic life-cycle and/or terrestrial habitats of plants which occurred around 450 million years ago. Our discovery of functional G-proteins in Chara braunii, a representative of the Charophycean green algae, establishes the existence of this conserved signaling pathway in the most basal plants and dates it even further back to 1-1.5 billion years ago. We have now identified the sequence homologs of G-proteins in additional algal families and propose that green algae represent a model system for one of the most basal forms of G-protein signaling known to exist to date. Given the possible differences that exist between plant and metazoan G-protein signaling mechanisms, such basal organisms will serve as important resources to trace the evolutionary origin of proposed mechanistic differences between the systems as well as their plant-specific functions.

  10. Cell-cycle regulation in green algae dividing by multiple fission.

    PubMed

    Bišová, Kateřina; Zachleder, Vilém

    2014-06-01

    Green algae dividing by multiple fission comprise unrelated genera but are connected by one common feature: under optimal growth conditions, they can divide into more than two daughter cells. The number of daughter cells, also known as the division number, is relatively stable for most species and usually ranges from 4 to 16. The number of daughter cells is dictated by growth rate and is modulated by light and temperature. Green algae dividing by multiple fission can thus be used to study coordination of growth and progression of the cell cycle. Algal cultures can be synchronized naturally by alternating light/dark periods so that growth occurs in the light and DNA replication(s) and nuclear and cellular division(s) occur in the dark; synchrony in such cultures is almost 100% and can be maintained indefinitely. Moreover, the pattern of cell-cycle progression can be easily altered by differing growth conditions, allowing for detailed studies of coordination between individual cell-cycle events. Since the 1950s, green algae dividing by multiple fission have been studied as a unique model for cell-cycle regulation. Future sequencing of algal genomes will provide additional, high precision tools for physiological, taxonomic, structural, and molecular studies in these organisms.

  11. Unique regulation of the Calvin cycle in the ultrasmall green alga Ostreococcus.

    PubMed

    Robbens, Steven; Petersen, Jörn; Brinkmann, Henner; Rouzé, Pierre; Van de Peer, Yves

    2007-05-01

    Glyceraldehyde-3-phosphate dehydrogenase (GapAB) and CP12 are two major players in controlling the inactivation of the Calvin cycle in land plants at night. GapB originated from a GapA gene duplication and differs from GapA by the presence of a specific C-terminal extension that was recruited from CP12. While GapA and CP12 are assumed to be generally present in the Plantae (glaucophytes, red and green algae, and plants), up to now GapB was exclusively found in Streptophyta, including the enigmatic green alga Mesostigma viride. However, here we show that two closely related prasinophycean green algae, Ostreococcus tauri and Ostreococcus lucimarinus, also possess a GapB gene, while CP12 is missing. This remarkable finding either antedates the GapA/B gene duplication or indicates a lateral recruitment. Moreover, Ostreococcus is the first case where the crucial CP12 function may be completely replaced by GapB-mediated GapA/B aggregation.

  12. An unexpectedly large and loosely packed mitochondrial genome in the charophycean green alga Chlorokybus atmophyticus

    PubMed Central

    Turmel, Monique; Otis, Christian; Lemieux, Claude

    2007-01-01

    Background The Streptophyta comprises all land plants and six groups of charophycean green algae. The scaly biflagellate Mesostigma viride (Mesostigmatales) and the sarcinoid Chlorokybus atmophyticus (Chlorokybales) represent the earliest diverging lineages of this phylum. In trees based on chloroplast genome data, these two charophycean green algae are nested in the same clade. To validate this relationship and gain insight into the ancestral state of the mitochondrial genome in the Charophyceae, we sequenced the mitochondrial DNA (mtDNA) of Chlorokybus and compared this genome sequence with those of three other charophycean green algae and the bryophytes Marchantia polymorpha and Physcomitrella patens. Results The Chlorokybus genome differs radically from its 42,424-bp Mesostigma counterpart in size, gene order, intron content and density of repeated elements. At 201,763-bp, it is the largest mtDNA yet reported for a green alga. The 70 conserved genes represent 41.4% of the genome sequence and include nad10 and trnL(gag), two genes reported for the first time in a streptophyte mtDNA. At the gene order level, the Chlorokybus genome shares with its Chara, Chaetosphaeridium and bryophyte homologues eight to ten gene clusters including about 20 genes. Notably, some of these clusters exhibit gene linkages not previously found outside the Streptophyta, suggesting that they originated early during streptophyte evolution. In addition to six group I and 14 group II introns, short repeated sequences accounting for 7.5% of the genome were identified. Mitochondrial trees were unable to resolve the correct position of Mesostigma, due to analytical problems arising from accelerated sequence evolution in this lineage. Conclusion The Chlorokybus and Mesostigma mtDNAs exemplify the marked fluidity of the mitochondrial genome in charophycean green algae. The notion that the mitochondrial genome was constrained to remain compact during charophycean evolution is no longer tenable

  13. Mitochondrion-to-Chloroplast DNA Transfers and Intragenomic Proliferation of Chloroplast Group II Introns in Gloeotilopsis Green Algae (Ulotrichales, Ulvophyceae).

    PubMed

    Turmel, Monique; Otis, Christian; Lemieux, Claude

    2016-09-19

    To probe organelle genome evolution in the Ulvales/Ulotrichales clade, the newly sequenced chloroplast and mitochondrial genomes of Gloeotilopsis planctonica and Gloeotilopsis sarcinoidea (Ulotrichales) were compared with those of Pseudendoclonium akinetum (Ulotrichales) and of the few other green algae previously sampled in the Ulvophyceae. At 105,236 bp, the G planctonica mitochondrial DNA (mtDNA) is the largest mitochondrial genome reported so far among chlorophytes, whereas the 221,431-bp G planctonica and 262,888-bp G sarcinoidea chloroplast DNAs (cpDNAs) are the largest chloroplast genomes analyzed among the Ulvophyceae. Gains of non-coding sequences largely account for the expansion of these genomes. Both Gloeotilopsis cpDNAs lack the inverted repeat (IR) typically found in green plants, indicating that two independent IR losses occurred in the Ulvales/Ulotrichales. Our comparison of the Pseudendoclonium and Gloeotilopsis cpDNAs offered clues regarding the mechanism of IR loss in the Ulotrichales, suggesting that internal sequences from the rDNA operon were differentially lost from the two original IR copies during this process. Our analyses also unveiled a number of genetic novelties. Short mtDNA fragments were discovered in two distinct regions of the G sarcinoidea cpDNA, providing the first evidence for intracellular inter-organelle gene migration in green algae. We identified for the first time in green algal organelles, group II introns with LAGLIDADG ORFs as well as group II introns inserted into untranslated gene regions. We discovered many group II introns occupying sites not previously documented for the chloroplast genome and demonstrated that a number of them arose by intragenomic proliferation, most likely through retrohoming. © The Author 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  14. COMPARISON OF METHODS TO DETECT ALLELOPATHIC EFFECTS OF SUBMERGED MACROPHYTES ON GREEN ALGAE(1).

    PubMed

    Hilt Nee Körner, Sabine; Beutler, Eike; Bauer, Nadine

    2012-02-01

    Detecting allelopathic inhibition of phytoplankton by submerged macrophytes in an ecologically meaningful way is not easy. Multiple-approach investigations from a laboratory scale to the ecosystem level have been recommended to overcome the shortcomings of individual methods. Whether results of different methods are qualitatively or quantitatively comparable has not yet been tested. Here, we compare the sensitivity of the green algae Desmodesmus subspicatus (Chodat) E. Hegewald et Ant. Schmidt and Stigeoclonium helveticum Vischer to the allelopathic effect of the submerged macrophyte Myriophyllum verticillatum L. The following three approaches were used: (i) coincubation of algae in dialysis membrane tubes in a lake inside and outside a M. verticillatum stand, (ii) coincubation of algae in dialysis membrane tubes in aquaria with and without M. verticillatum, and (iii) single additions of tannic acid (TA), an allelopathically active polyphenol present in this macrophyte, to the algae cultures. For each method, fluorescence-based (chl a, PSII activity) and particle-based (cell count, biovolume) parameters were compared after 48 h of incubation. Results revealed quantitative and qualitative differences between methods. Algae incubated in dialysis membrane tubes in aquaria showed a strong decrease in all parameters under the influence of macrophytes. In situ measurements were influenced by adverse growth conditions for the test algae and only detected significant reductions for biovolume. Single additions of TA induced a strong reduction of fluorescence-based parameters similar to aquarium results, but an increase in the cell count. Even the qualitative transfer of laboratory results to field conditions thus requires caution and a proper selection of parameters. © 2011 Phycological Society of America.

  15. The genome and phenome of the green alga Chloroidium sp. UTEX 3007 reveal adaptive traits for desert acclimatization.

    PubMed

    Nelson, David R; Khraiwesh, Basel; Fu, Weiqi; Alseekh, Saleh; Jaiswal, Ashish; Chaiboonchoe, Amphun; Hazzouri, Khaled M; O'Connor, Matthew J; Butterfoss, Glenn L; Drou, Nizar; Rowe, Jillian D; Harb, Jamil; Fernie, Alisdair R; Gunsalus, Kristin C; Salehi-Ashtiani, Kourosh

    2017-06-17

    To investigate the phenomic and genomic traits that allow green algae to survive in deserts, we characterized a ubiquitous species, Chloroidium sp. UTEX 3007, which we isolated from multiple locations in the United Arab Emirates (UAE). Metabolomic analyses of Chloroidium sp. UTEX 3007 indicated that the alga accumulates a broad range of carbon sources, including several desiccation tolerance-promoting sugars and unusually large stores of palmitate. Growth assays revealed capacities to grow in salinities from zero to 60 g/L and to grow heterotrophically on >40 distinct carbon sources. Assembly and annotation of genomic reads yielded a 52.5 Mbp genome with 8153 functionally annotated genes. Comparison with other sequenced green algae revealed unique protein families involved in osmotic stress tolerance and saccharide metabolism that support phenomic studies. Our results reveal the robust and flexible biology utilized by a green alga to successfully inhabit a desert coastline.

  16. Development of a UV laser-induced fluorescence lidar for monitoring blue-green algae in Lake Suwa.

    PubMed

    Saito, Yasunori; Takano, Kengo; Kobayashi, Fumitoshi; Kobayashi, Kazuki; Park, Ho-Dong

    2014-10-20

    We developed a UV (355 nm) laser-induced fluorescence (LIF) lidar for monitoring the real-time status of blue-green algae. Since the fluorescence spectrum of blue-green algae excited by 355 nm showed the specific fluorescence at 650 nm, the lidar was designed to be able to detect the 650 nm fluorescence as a surveillance method for the algae. The usefulness was confirmed by observation at Lake Suwa over four years (2005-2008). The detection limit of the LIF lidar was 16.65 mg/L for the blue-green algae, which is the range of concentrations in the safe level set by the World Health Organization.

  17. Acute toxicity of live and decomposing green alga Ulva ( Enteromorpha) prolifera to abalone Haliotis discus hannai

    NASA Astrophysics Data System (ADS)

    Wang, Chao; Yu, Rencheng; Zhou, Mingjiang

    2011-05-01

    From 2007 to 2009, large-scale blooms of green algae (the so-called "green tides") occurred every summer in the Yellow Sea, China. In June 2008, huge amounts of floating green algae accumulated along the coast of Qingdao and led to mass mortality of cultured abalone and sea cucumber. However, the mechanism for the mass mortality of cultured animals remains undetermined. This study examined the toxic effects of Ulva ( Enteromorpha) prolifera, the causative species of green tides in the Yellow Sea during the last three years. The acute toxicity of fresh culture medium and decomposing algal effluent of U. prolifera to the cultured abalone Haliotis discus hannai were tested. It was found that both fresh culture medium and decomposing algal effluent had toxic effects to abalone, and decomposing algal effluent was more toxic than fresh culture medium. The acute toxicity of decomposing algal effluent could be attributed to the ammonia and sulfide presented in the effluent, as well as the hypoxia caused by the decomposition process.

  18. Competition between cyanobacteria and green algae at low versus elevated CO2: who will win, and why?

    PubMed

    Ji, Xing; Verspagen, Jolanda M H; Stomp, Maayke; Huisman, Jef

    2017-06-01

    Traditionally, it has often been hypothesized that cyanobacteria are superior competitors at low CO2 and high pH in comparison with eukaryotic algae, owing to their effective CO2-concentrating mechanism (CCM). However, recent work indicates that green algae can also have a sophisticated CCM tuned to low CO2 levels. Conversely, cyanobacteria with the high-flux bicarbonate uptake system BicA appear well adapted to high inorganic carbon concentrations. To investigate these ideas we studied competition between three species of green algae and a bicA strain of the harmful cyanobacterium Microcystis aeruginosa at low (100 ppm) and high (2000 ppm) CO2. Two of the green algae were competitively superior to the cyanobacterium at low CO2, whereas the cyanobacterium increased its competitive ability with respect to the green algae at high CO2. The experiments were supported by a resource competition model linking the population dynamics of the phytoplankton species with dynamic changes in carbon speciation, pH and light. Our results show (i) that competition between phytoplankton species at different CO2 levels can be predicted from species traits in monoculture, (ii) that green algae can be strong competitors under CO2-depleted conditions, and (iii) that bloom-forming cyanobacteria with high-flux bicarbonate uptake systems will benefit from elevated CO2 concentrations. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  19. Impact of green algae on the measurement of Microcystis aeruginosa populations in lagoon-treated wastewater with an algae online analyser.

    PubMed

    Nguyen, Thang; Roddick, Felicity A; Fan, Linhua

    2015-01-01

    Tests on the algae online analyser (AOA) showed that there was a strong direct linear correlation between cell density and in vivo Chl-a concentration for M. aeruginosa over the range of interest for a biologically treated effluent at a wastewater treatment plant (25,000-65,000 cells mL(-1), equivalent to a biovolume of 2-6 mm3 L(-1)). However, the AOA can provide an overestimate or underestimate of M. aeruginosa populations when green algae are present in the effluent, depending on their species and relative numbers. The results from this study demonstrated that the green algae (e.g., Euglena gracilis, Chlorella sp.) in the field phytoplankton population should be considered during calibration. In summary, the AOA has potential for use as an alert system for the presence of M. aeruginosa, and thus potentially of cyanobacterial blooms, in wastewater stabilization ponds.

  20. Comparative genomic analysis of retrogene repertoire in two green algae Volvox carteri and Chlamydomonas reinhardtii.

    PubMed

    Jąkalski, Marcin; Takeshita, Kazutaka; Deblieck, Mathieu; Koyanagi, Kanako O; Makałowska, Izabela; Watanabe, Hidemi; Makałowski, Wojciech

    2016-08-04

    Retroposition, one of the processes of copying the genetic material, is an important RNA-mediated mechanism leading to the emergence of new genes. Because the transcription controlling segments are usually not copied to the new location in this mechanism, the duplicated gene copies (retrocopies) become pseudogenized. However, few can still survive, e.g. by recruiting novel regulatory elements from the region of insertion. Subsequently, these duplicated genes can contribute to the formation of lineage-specific traits and phenotypic diversity. Despite the numerous studies of the functional retrocopies (retrogenes) in animals and plants, very little is known about their presence in green algae, including morphologically diverse species. The current availability of the genomes of both uni- and multicellular algae provides a good opportunity to conduct a genome-wide investigation in order to fill the knowledge gap in retroposition phenomenon in this lineage. Here we present a comparative genomic analysis of uni- and multicellular algae, Chlamydomonas reinhardtii and Volvox carteri, respectively, to explore their retrogene complements. By adopting a computational approach, we identified 141 retrogene candidates in total in both genomes, with their fraction being significantly higher in the multicellular Volvox. Majority of the retrogene candidates showed signatures of functional constraints, thus indicating their functionality. Detailed analyses of the identified retrogene candidates, their parental genes, and homologs of both, revealed that most of the retrogene candidates were derived from ancient retroposition events in the common ancestor of the two algae and that the parental genes were subsequently lost from the respective lineages, making many retrogenes 'orphan'. We revealed that the genomes of the green algae have maintained many possibly functional retrogenes in spite of experiencing various molecular evolutionary events during a long evolutionary time after

  1. Toxicity and bioaccumulation kinetics of arsenate in two freshwater green algae under different phosphate regimes.

    PubMed

    Wang, Ning-Xin; Li, Yan; Deng, Xi-Hai; Miao, Ai-Jun; Ji, Rong; Yang, Liu-Yan

    2013-05-01

    In the present study, the toxicity and bioaccumulation kinetics of arsenate in two green algae Chlamydomonas reinhardtii and Scenedesmus obliquus under phosphate-enriched (+P) and limited (-P) conditions were investigated. P-limitation was found to aggravate arsenate toxicity and S. obliquus was more tolerant than C. reinhardtii. Such phosphate-condition-dependent or algal-species-specific toxicity difference was narrowed when the relative inhibition of cell growth was plotted against intracellular arsenate content instead of its extracellular concentration. The discrepance was further reduced when the intracellular ratio of arsenic to phosphorus was applied. It suggests that both arsenate bioaccumulation and intracellular phosphorus played an important role in arsenate toxicity. On the other hand, arsenate uptake was induced by P-limitation and its variation with ambient arsenate concentration could be well fitted to the Michaelis-Menten model. Arsenate transporters of S. obliquus were found to have a higher affinity but lower capacity than those of C. reinhardtii, which explains its better regulation of arsenate accumulation than the latter species in the toxicity experiment. Further, arsenate depuration was facilitated and more was transformed to arsenite in C. reinhardtii or under -P condition. Intracellular proportion of arsenite was also increased after the algae were transferred from the long-term uptake media to a relatively clean solution in the efflux experiment. Both phenomena imply that algae especially the sensitive species could make physiological adjustments to alleviate the adverse effects of arsenate. Overall, our findings will facilitate the application of algae in arsenate remediation.

  2. The effect of natural organic matter on bioaccumulation and toxicity of chlorobenzenes to green algae.

    PubMed

    Zhang, Shuai; Lin, Daohui; Wu, Fengchang

    2016-07-05

    The effect of natural organic matter (NOM) on toxicity and bioavailability of hydrophobic organic contaminants (HOCs) to aquatic organisms has been investigated with conflicting results and undefined mechanisms, and few studies have been conducted on volatile HOCs. In this study, six volatile chlorobenzenes (CBs) with 1-6 chlorine substitutions were investigated for their bioaccumulation in an acute toxicity to a green alga (Chlorella pyrenoidosa) in the presence/absence of Suwannee River NOM (SRNOM). The fluorescence quenching efficiency of SRNOM increased as the number of chlorine substitutions of CBs increased. SRNOM increased the cell-surface hydrophobicity of algae and decreased the release rates of algae-accumulated CBs, thus increasing the concentration factor (CF) and accumulation of the CBs in the algae. SRNOM increased the toxicity of monochlorobenzene and 1,2-dichlorobenzene, decreased the toxicity of pentachlorobenzene and hexachlorobenzene, and had no significant effect on the toxicity of 1,2,3-trichlorobenzene and 1,2,3,4-tetrachlorobenzene. Relationships between the 96 h CF/IC50 (i.e., the CB concentration leading to a 50% algal growth reduction compared with the control) and physicochemical properties of CBs with/without SRNOM were established, providing reasonable explanations for the experimental results. These findings will help with the accurate assessment of ecological risks of organic pollutants in the presence of NOM. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Three novel species of coccoid green algae within the Watanabea clade (Trebouxiophyceae, Chlorophyta).

    PubMed

    Song, Huiyin; Hu, Yuxin; Zhu, Huan; Wang, Qinghua; Liu, Guoxiang; Hu, Zhengyu

    2016-12-01

    Coccoid green algae are extremely diverse despite their simple coccoid phenotype, a phenotype that may be the result of convergent evolution. In this study, we used a polyphasic approach combining molecular phylogenetic analyses, morphology and ultrastructure to investigate isolated coccoid strains from China, and our results reveal three new lineages of Trebouxiophyceae: the novel genus and species Mysteriochloris nanningensis gen. et sp. nov., and the two novel species Phyllosiphon coccidium sp. nov. and Desertella yichangensis sp. nov. (Trebouxiophyceae, Chlorophyta). We provide a detailed characterization of the novel microalgae which they are autosporic coccoid unicells and have parietal chloroplasts. In phylogenies based on 18S rDNA sequences and the chloroplast ribulose-bisphosphate carboxylase gene (rbcL), these three algae are nested within the Watanabea clade and are different from any known algae. M. nanningensis FACHB-1787 is not really close to any known algae within the Watanabea clade. Phyllosiphoncoccidium FACHB-2212 is within the Phyllosiphon lineages. D. yichangensis FACHB-1793 is closely related to Desertella californica and described as a representative of a novel species of the genus Desertella.

  4. Genomic analysis of organismal complexity in the multicellular green alga Volvox carteri

    SciTech Connect

    Prochnik, Simon E.; Umen, James; Nedelcu, Aurora; Hallmann, Armin; Miller, Stephen M.; Nishii, Ichiro; Ferris, Patrick; Kuo, Alan; Mitros, Therese; Fritz-Laylin, Lillian K.; Hellsten, Uffe; Chapman, Jarrod; Simakov, Oleg; Rensing, Stefan A.; Terry, Astrid; Pangilinan, Jasmyn; Kapitonov, Vladimir; Jurka, Jerzy; Salamov, Asaf; Shapiro, Harris; Schmutz, Jeremy; Grimwood, Jane; Lindquist, Erika; Lucas, Susan; Grigoriev, Igor V.; Schmitt, Rudiger; Kirk, David; Rokhsar, Daniel S.

    2010-07-01

    Analysis of the Volvox carteri genome reveals that this green alga's increased organismal complexity and multicellularity are associated with modifications in protein families shared with its unicellular ancestor, and not with large-scale innovations in protein coding capacity. The multicellular green alga Volvox carteri and its morphologically diverse close relatives (the volvocine algae) are uniquely suited for investigating the evolution of multicellularity and development. We sequenced the 138 Mb genome of V. carteri and compared its {approx}14,500 predicted proteins to those of its unicellular relative, Chlamydomonas reinhardtii. Despite fundamental differences in organismal complexity and life history, the two species have similar protein-coding potentials, and few species-specific protein-coding gene predictions. Interestingly, volvocine algal-specific proteins are enriched in Volvox, including those associated with an expanded and highly compartmentalized extracellular matrix. Our analysis shows that increases in organismal complexity can be associated with modifications of lineage-specific proteins rather than large-scale invention of protein-coding capacity.

  5. Evaluation of antigenotoxic effects of carotenoids from green algae Chlorococcum humicola using human lymphocytes

    PubMed Central

    Bhagavathy, S; Sumathi, P

    2012-01-01

    Objective To identify the available phytochemicals and carotenoids in the selected green algae and evaluate the potential genotoxic/antigenotoxic effect using lymphocytes. Methods Organic solvent extracts of Chlorococcum humicola (C. humicola) were used for the phytochemical analysis. The available carotenoids were assessed by HPLC, and LC-MS analysis. The genotoxicity was induced by the benzo(a)pyrene in the lymphocyte culture, the genotoxic and antigenotoxic effects of algal carotenoids with and without genotoxic inducer were evaluated by chromosomal aberration (CA), sister chromatid exchange (SCE) and micronucleus assay (MN). Results The results of the analysis showed that the algae were rich in carotenoids and fatty acids. In the total carotenoids lutein, β-carotene and α-carotene were found to be present in higher concentration. The frequency of CA and SCE increased by benzo(a)pyrene were significantly decreased by the carotenoids (P<0.05 for CA, P<0.001 for SCE). The MN frequencies of the cells were significantly decreased by the treatment with carotenoids when compared with the positive controls (P<0.05). Conclusions The findings of the present study demonstrate that, the green algae C. humicola is a rich source of bioactive compounds especially carotenoids which effectively fight against environmental genotoxic agents, the carotenoids itself is not a genotoxic substance and should be further considered for its beneficial effects. PMID:23569879

  6. Evaluation of antigenotoxic effects of carotenoids from green algae Chlorococcum humicola using human lymphocytes.

    PubMed

    Bhagavathy, S; Sumathi, P

    2012-02-01

    To identify the available phytochemicals and carotenoids in the selected green algae and evaluate the potential genotoxic/antigenotoxic effect using lymphocytes. Organic solvent extracts of Chlorococcum humicola (C. humicola) were used for the phytochemical analysis. The available carotenoids were assessed by HPLC, and LC-MS analysis. The genotoxicity was induced by the benzo(a)pyrene in the lymphocyte culture, the genotoxic and antigenotoxic effects of algal carotenoids with and without genotoxic inducer were evaluated by chromosomal aberration (CA), sister chromatid exchange (SCE) and micronucleus assay (MN). The results of the analysis showed that the algae were rich in carotenoids and fatty acids. In the total carotenoids lutein, β-carotene and α-carotene were found to be present in higher concentration. The frequency of CA and SCE increased by benzo(a)pyrene were significantly decreased by the carotenoids (P<0.05 for CA, P<0.001 for SCE). The MN frequencies of the cells were significantly decreased by the treatment with carotenoids when compared with the positive controls (P<0.05). The findings of the present study demonstrate that, the green algae C. humicola is a rich source of bioactive compounds especially carotenoids which effectively fight against environmental genotoxic agents, the carotenoids itself is not a genotoxic substance and should be further considered for its beneficial effects.

  7. Identification of phytochelatins in the cadmium-stressed conjugating green alga Micrasterias denticulata.

    PubMed

    Volland, Stefanie; Schaumlöffel, Dirk; Dobritzsch, Dirk; Krauss, Gerd-Joachim; Lütz-Meindl, Ursula

    2013-04-01

    Aquatic environments like peat bogs are affected by anthropogenic metal input into the environment. These ecosystems are inhabited by unicellular green algae of the class Zygnematophyceae. In this study the desmid Micrasterias denticulata was stressed with 600 nM Cd, 10 μM Cr and 300 nM Cu for 3 weeks. GSH levels were measured with HPLC and did not differ between the different treatments or the control. According to the metallo-thiolomics concept, mass spectrometry was used as a method for unambiguous thiol peptide identification. PC2, PC3 and PC4 were clearly identified in the Cd stressed sample with UPLC-MS by their MS spectrum and molecular masses. PC2 and PC3 were determined to be the main thiol compounds, while PC4 was only abundant in traces in Micrasterias. In addition, the identity of PC2 and PC3 was confirmed by MS/MS. No PCs were detected in the Cu stressed algae sample. However, in the Cr stressed sample traces of PC2 were indicated by a peak in UPLC-MS at the retention time of the PC2 standard, but the intensity was too low to acquire reliable MS and MS/MS spectra. In this study PCs have been detected for the first time in a green alga of the division Streptophyta, a close relative to higher plants. Copyright © 2012 Elsevier Ltd. All rights reserved.

  8. Differential sensitivity of two green algae, Scenedesmus quadricauda and Chlorella vulgaris, to 14 pesticide adjuvants.

    PubMed

    Ma, Jianyi; Lin, Fucheng; Zhang, Renzhi; Yu, Weiwu; Lu, Ninghai

    2004-05-01

    Growth-inhibition tests for 14 pesticide adjuvants which are widely used to manufacture various pesticidal formulations in China, were performed on the green algae Scenedesmus quadricauda, and Chlorella vulgaris to compare differential sensitivity among populations of these algae to the adjuvants. The results showed that the acute toxicities of 700#, 1601#, By-140, and SOPA to S. quadricauda and C. vulgaris were the lowest among all the tested adjuvants. The acute toxicities of Tween 80, O-25, and AEO-13 phosphate to the selected two green algae were intermediate among the tested adjuvants. The acute toxicities of 602#, 500#, OT, NP-10, OP-10, and JFC were the highest. Meanwhile, the algal species vary widely in their response to those adjuvants. The results showed that there was a differential response to various adjuvants among the selected algal species and that the sensitivities of the various algal species exposed to 1601# and OT varied by nearly 1 order and to 700#, and By-140 varied by over 1 order of magnitude. In addition, the NOEC and LOEC values of the selected 14 adjuvants to S. quadricauda and C. vulgaris were tested; the result showed that NOEC < or = EC10

  9. First laccase in green algae: purification and characterization of an extracellular phenol oxidase from Tetracystis aeria.

    PubMed

    Otto, Benjamin; Schlosser, Dietmar

    2014-12-01

    A green algal phenol oxidase was firstly purified, confirmed to be a laccase, and a hetero-oligomeric quaternary structure is suggested. The operation of a laccase-mediator system is firstly described in algae. Laccases (EC 1.10.3.2) catalyze the oxidation of a multitude of aromatic substrates. They are well known in higher plants and fungi, while their presence in green algae appears uncertain. Extracellular laccase-like enzyme activity has previously been described in culture supernatants of the green soil alga Tetracystis aeria [Otto et al. in Arch Microbiol 192:759-768, (2010)]. As reported herein, the T. aeria enzyme was purified 120-fold by employing a combination of anion exchange and size exclusion chromatography. The purified enzyme was confirmed to be a laccase according to its substrate specificity. It oxidizes 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), syringaldazine, and 2,6-dimethoxyphenol (pH optima of pH ≤ 2.5, 7.0, and 6.5; K m values of 28.8, 40.5, and 1,830 µM; respectively), but not L-tyrosine or Fe(2+). ABTS is by far the most efficient substrate. Two polypeptides, A (~110 kDa) and B (71 kDa), were co-purified by the applied procedure, both being highly N-glycosylated (≥~53 and ≥ 27 %, respectively). As suggested by various gel electrophoretic analyses, the native enzyme (apparent molecular mass of ~220 kDa) most probably is a hetero-oligomer with the composition AB 2 , wherein A is the catalytic subunit and B forms a disulfide-linked homo-dimer B2. The decolorization of anthraquinone (Acid Blue 62 and Remazol Brilliant Blue R) and diazo dyes (Reactive Black 5) was studied in the presence of redox-mediating compounds (ABTS and syringaldehyde), demonstrating the operation of the laccase-mediator system in algae for the first time. Thus, laccases from green algae may participate in the biotransformation of a wide spectrum of natural and xenobiotic compounds.

  10. Removal of phenanthrene from coastal waters by green tide algae Ulva prolifera.

    PubMed

    Zhang, Cui; Lu, Jian; Wu, Jun; Luo, Yongming

    2017-12-31

    Ulva prolifera (U. prolifera) has been frequently involved in terrible algal proliferation in coastal areas. Although it is known to be associated with green tide, its contribution to the natural attenuation of the polycyclic aromatic hydrocarbons (PAHs) in seawater has not been evaluated. In this study, the removal of phenanthrene using U. prolifera collected from coastal water with green tide blooming was investigated. The results showed that phenanthrene could be removed efficiently in the presence of both the live and heat-killed U. prolifera. The phenanthrene concentrations of the live algae treatment decreased smoothly from 10.00 to 0.80μgL(-1) through the whole process, while those of the heat-killed algae treatment decreased sharply from 10.0 to 2.71μgL(-1) in one day and kept constantly after that. The in situ monitoring and visualizing using laser confocal scanning microscopy (LCSM) confirmed the accumulation of phenanthrene in U. prolifera. The increase in nutrient and temperature led to the increase of phenanthrene removal rate, while the salinity had less influence on the removal of phenanthrene. The removal efficiency by U. prolifera had a good linear relationship with phenanthrene initial concentration (r(2)=0.999) even at 100μgL(-1) which was higher than its environmentally relevant concentrations. High removal efficiency (91.3%) was observed when the initial phenanthrene concentration was set at environmental relevant concentration (5μgL(-1)). Results of this study demonstrate a potential new natural attenuation process for typical PAHs in coastal water during the outbreak of green tide. These findings indicate that the outbreak of harmful green tide algae may bring positive environmental benefits in the terms of the removal of harmful organic pollutants from coastal waters. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Growth of the green algae Chlamydomonas reinhardtii under red and blue lasers

    NASA Astrophysics Data System (ADS)

    Kuwahara, Sara S.; Cuello, Joel L.; Myhre, Graham; Pau, Stanley

    2011-03-01

    Red and blue lasers, holding promise as an electric light source for photosynthetic systems on account of being true monochromatic, high-power, and having high electrical-conversion efficiency, were employed in growing a green alga, Chlamydomonas reinhardtii. The laser treatments tested included: 655-nm Red; 680-nm Red; 655-nm Red+474-nm Blue and 680-nm Red+474-nm Blue. A white cold cathode lamp with spectral output similar to that of white fluorescent lamp served as control. C. reinhardtii successfully grew and divided under the 655 and 680-nm red lasers as well as under the white-light control. Supplementing either red with blue laser, however, resulted in increased algae cell count that significantly exceeded those under both red lasers and the white-light control on average by 241%.

  12. Organelle genome complexity scales positively with organism size in volvocine green algae.

    PubMed

    Smith, David Roy; Hamaji, Takashi; Olson, Bradley J S C; Durand, Pierre M; Ferris, Patrick; Michod, Richard E; Featherston, Jonathan; Nozaki, Hisayoshi; Keeling, Patrick J

    2013-04-01

    It has been argued that for certain lineages, noncoding DNA expansion is a consequence of the increased random genetic drift associated with long-term escalations in organism size. But a lack of data has prevented the investigation of this hypothesis in most plastid-bearing protists. Here, using newly sequenced mitochondrial and plastid genomes, we explore the relationship between organelle DNA noncoding content and organism size within volvocine green algae. By looking at unicellular, colonial, and differentiated multicellular algae, we show that organelle DNA complexity scales positively with species size and cell number across the volvocine lineage. Moreover, silent-site genetic diversity data suggest that the volvocine species with the largest cell numbers and most bloated organelle genomes have the smallest effective population sizes. Together, these findings support the view that nonadaptive processes, like random genetic drift, promote the expansion of noncoding regions in organelle genomes.

  13. Diurnal variation in n(2) fixation and photosynthesis by aquatic blue-green algae.

    PubMed

    Peterson, R B; Friberg, E E; Burris, R H

    1977-01-01

    Rates of (14)CO(2) fixation, O(2) evolution, and N(2) fixation (acetylene reduction) by natural populations of blue-green algae recovered from Lake Mendota were measured at frequent intervals between sunrise and sunset. Photosynthesis and N(2) fixation were depressed during midday when light intensity was greatest. As the light intensity rose, most of the algal population migrated to deeper, light-limited waters where radiation damage would be diminished. As the relative rate of N(2) fixation compared to CO(2) fixation increases with depth, it is suggested that the algae maintain balanced growth by migrating vertically via buoyancy regulation. High concentrations of dissolved O(2) in lake water may inhibit N(2) fixation by enhancing photorespiration. Several factors such as photosynthetic rate, light intensity, dissolved O(2), species composition, and vertical and horizontal migration all affect observed rates of in situ N(2) fixation.

  14. Studies on the proteins of mass-cultivated, blue-green alga (Spirulina platensis)

    SciTech Connect

    Annusuyadevi, M.; Subbulakshmi, G.; Madhair'devi, K.; Venkalaramein, L.V.

    1981-05-01

    The characteristics of the protein of fresh-water, mass-cultured Spirulina platensis have been studied. The solubility of this algal protein in water and various aqueous solvents has been estimated. The total protein content of the blue-green algae was approximately 50-55% of which nearly 9.9% was nonprotein nitrogen. About 80% of the total protein nitrogen can be extracted by three successive extractions with water. Ths isoelectric point of this algal protein is found to be 3.0. The total proteins were characterized physicochemically by standard techniques. In the ultracentrifuge total proteins resolve into two major components with S20w values of 2.6 and 4.7 S. The polyacrylamide gel electrophoretic pattern of the total protein showed seven bands including three prominent ones. The in vitro digestibility of the total protein of fresh algae was found to be 85% when assayed with a pepsin-pancreatin system.

  15. Genomic analysis of organismal complexity in the multicellular green alga Volvox carteri.

    PubMed

    Prochnik, Simon E; Umen, James; Nedelcu, Aurora M; Hallmann, Armin; Miller, Stephen M; Nishii, Ichiro; Ferris, Patrick; Kuo, Alan; Mitros, Therese; Fritz-Laylin, Lillian K; Hellsten, Uffe; Chapman, Jarrod; Simakov, Oleg; Rensing, Stefan A; Terry, Astrid; Pangilinan, Jasmyn; Kapitonov, Vladimir; Jurka, Jerzy; Salamov, Asaf; Shapiro, Harris; Schmutz, Jeremy; Grimwood, Jane; Lindquist, Erika; Lucas, Susan; Grigoriev, Igor V; Schmitt, Rüdiger; Kirk, David; Rokhsar, Daniel S

    2010-07-09

    The multicellular green alga Volvox carteri and its morphologically diverse close relatives (the volvocine algae) are well suited for the investigation of the evolution of multicellularity and development. We sequenced the 138-mega-base pair genome of V. carteri and compared its approximately 14,500 predicted proteins to those of its unicellular relative Chlamydomonas reinhardtii. Despite fundamental differences in organismal complexity and life history, the two species have similar protein-coding potentials and few species-specific protein-coding gene predictions. Volvox is enriched in volvocine-algal-specific proteins, including those associated with an expanded and highly compartmentalized extracellular matrix. Our analysis shows that increases in organismal complexity can be associated with modifications of lineage-specific proteins rather than large-scale invention of protein-coding capacity.

  16. DNA barcoding of a new record of epi-endophytic green algae Ulvella leptochaete (Ulvellaceae, Chlorophyta) in India.

    PubMed

    Bast, Felix; Bhushan, Satej; John, Aijaz Ahmad

    2014-09-01

    Epi-endophytic green algae comprise one of the most diverse and phylogenetically primitive groups of green algae and are considered to be ubiquitous in the world's oceans; however, no reports of these algae exist from India. Here we report the serendipitous discovery of Ulvella growing on intertidal green algae Cladophora glomerata and benthic red algae Laurencia obtusa collected from India. DNA barcodes at nuclear ribosomal DNA Internal Transcriber Spacer (nrDNA ITS) 1 and 2 regions for Indian isolates from the west and east coasts have been generated for the first time. Based on morphology and DNA barcoding, isolates were identified as Ulvella leptochaete. Phylogenetic reconstruction of concatenated dataset using Maximum Likelihood method differentiated Indian isolates from other accessions of this alga available in Genbank, albeit with low bootstrap support. Monophyly of Ulvella leptochaete was obvious in both of our phylogenetic analyses. With this first report of epi-endophytic algae from Indian territorial waters, the dire need to catalogue its cryptic diversity is highlighted and avenues of future research are discussed.

  17. Evidence for methane production by the marine algae Emiliania huxleyi

    NASA Astrophysics Data System (ADS)

    Lenhart, Katharina; Klintzsch, Thomas; Langer, Gerald; Nehrke, Gernot; Bunge, Michael; Schnell, Sylvia; Keppler, Frank

    2016-06-01

    Methane (CH4), an important greenhouse gas that affects radiation balance and consequently the earth's climate, still has uncertainties in its sinks and sources. The world's oceans are considered to be a source of CH4 to the atmosphere, although the biogeochemical processes involved in its formation are not fully understood. Several recent studies provided strong evidence of CH4 production in oxic marine and freshwaters, but its source is still a topic of debate. Studies of CH4 dynamics in surface waters of oceans and large lakes have concluded that pelagic CH4 supersaturation cannot be sustained either by lateral inputs from littoral or benthic inputs alone. However, regional and temporal oversaturation of surface waters occurs frequently. This comprises the observation of a CH4 oversaturating state within the surface mixed layer, sometimes also termed the "oceanic methane paradox". In this study we considered marine algae as a possible direct source of CH4. Therefore, the coccolithophore Emiliania huxleyi was grown under controlled laboratory conditions and supplemented with two 13C-labeled carbon substrates, namely bicarbonate and a position-specific 13C-labeled methionine (R-S-13CH3). The CH4 production was 0.7 µg particular organic carbon (POC) g-1 d-1, or 30 ng g-1 POC h-1. After supplementation of the cultures with the 13C-labeled substrate, the isotope label was observed in headspace CH4. Moreover, the absence of methanogenic archaea within the algal culture and the oxic conditions during CH4 formation suggest that the widespread marine algae Emiliania huxleyi might contribute to the observed spatially and temporally restricted CH4 oversaturation in ocean surface waters.

  18. Ecotoxicity of silica nanoparticles to the green alga Pseudokirchneriella subcapitata: importance of surface area.

    PubMed

    Van Hoecke, Karen; De Schamphelaere, Karel A C; Van der Meeren, Paul; Lucas, Stéphane; Janssen, Colin R

    2008-09-01

    To date, (eco)toxicological information on industrial nanoparticles is very limited. In the present study, the hypothesis that the ecotoxicity of nanoparticles (NPs) is related to their surface area and not to their mass was tested using a freshwater green algal species. Particle diameter and morphology were assessed using light scattering and electron microscopy techniques. To assess the toxicity of silica (SiO2) nanoparticles, the growth inhibition of the alga Pseudokirchneriella subcapitata when exposed to stable silica suspensions was monitored. Commercial LUDOX suspensions of nanoparticles with 12.5 and 27.0 nm diameter were found to be toxic, with 72-h 20% effect concentrations for growth rate (E(r)C20) values +/- standard deviation (n = 5) of 20.0 +/- 5.0 and 28.8 +/- 3.2 mg/L, respectively. The toxicity was attributable to the solid nanospheres, because no aggregation was observed and dissolution of the nanoparticles was negligible. When expressing the concentration as a surface area, the difference in toxicity was not significant. In the latter case, 72-h E(r)C20 values +/- standard deviation (n = 5) were 4.7 +/- 1.2 and 3.9 +/- 0.4 m2/L. Silica bulk material was found to be nontoxic up to 1 g/L. In an additional experiment with 100 mg/L of 12.5 and 27.0 nm SiO2 NPs, the interaction between the nanoparticles and algal cells was studied using transmission electron microscopy. Although the particles clearly adhered to the outer cell surface, no evidence was found for particle uptake.

  19. Colony organization in the green alga Botryococcus braunii is specified by a complex extracellular matrix

    DOE PAGES

    Weiss, Taylor L.; Roth, Robyn; Goodson, Carrie; ...

    2012-08-31

    Botryococcus braunii is a colonial green alga whose cells associate via a complex extracellular matrix (ECM) and produce prodigious amounts of liquid hydrocarbons that can be readily converted into conventional combustion engine fuels. We used quickfreeze deep-etch electron microscopy and biochemical/histochemical analysis to elucidate many new features of B. braunii cell/colony organization and composition. Intracellular lipid bodies associate with the chloroplast and endoplasmic reticulum (ER) but show no evidence of being secreted. The ER displays striking fenestrations and forms a continuous subcortical system in direct contact with the cell membrane. The ECM has three distinct components. (i) Each cell ismore » surrounded by a fibrous β-1, 4- and/or β-1, 3-glucan-containing cell wall. (ii) The intracolonial ECM space is filled with a cross-linked hydrocarbon network permeated with liquid hydrocarbons. (iii) Colonies are enclosed in a retaining wall festooned with a fibrillar sheath dominated by arabinose-galactose polysaccharides, which sequesters ECM liquid hydrocarbons. Each cell apex associates with the retaining wall and contributes to its synthesis. Retaining-wall domains also form "drapes" between cells, with some folding in on themselves and penetrating the hydrocarbon interior of a mother colony, partitioning it into daughter colonies. In addition, we propose that retaining-wall components are synthesized in the apical Golgi apparatus, delivered to apical ER fenestrations, and assembled on the surfaces of apical cell walls, where a proteinaceous granular layer apparently participates in fibril morphogenesis. We further propose that hydrocarbons are produced by the nonapical ER, directly delivered to the contiguous cell membrane, and pass across the nonapical cell wall into the hydrocarbon-based ECM.« less

  20. The identification of putative RNA polymerase II C-terminal domain associated proteins in red and green algae.

    PubMed

    Yang, Chunlin; Hager, Paul W; Stiller, John W

    2014-01-01

    A tandemly repeated C-terminal domain (CTD) of the largest subunit of RNA polymerase II is functionally essential and strongly conserved in many organisms, including animal, yeast and plant models. Although present in simple, ancestral red algae, CTD tandem repeats have undergone extensive modifications and degeneration during the evolutionary transition to developmentally complex rhodophytes. In contrast, CTD repeats are conserved in both green algae and their more complex land plant relatives. Understanding the mechanistic differences that underlie these variant patterns of CTD evolution requires knowledge of CTD-associated proteins in these 2 lineages. To provide an initial baseline comparison, we bound potential phospho-CTD associated proteins (PCAPs) to artificially synthesized and phosphorylated CTD repeats from the unicellular red alga Cyanidioschyzon merolae and green alga Chlamydomonas reinhardtii. Our results indicate that red and green algae share a number of PCAPs, including kinases and proteins involved in mRNA export. There also are important taxon-specific differences, including mRNA splicing-related PCAPs recovered from Chlamydomonas but not Cyanidioschyzon, consistent with the relative intron densities in green and red algae. Our results also offer the first experimental indication that different proteins bind 2 distinct types of repeats in Cyanidioschyzon, suggesting a division of function between the proximal and distal CTD, similar to patterns identified in more developmentally complex model organisms.

  1. A new model for the calcification of the green macro-alga Halimeda opuntia (Lamouroux)

    NASA Astrophysics Data System (ADS)

    Wizemann, André; Meyer, Friedrich W.; Westphal, Hildegard

    2014-12-01

    Halimeda opuntia is a cosmopolitan marine calcifying green alga in shallow tropical marine environments. Besides Halimeda's contribution to a diverse habitat, the alga is an important sediment producer. Fallen calcareous segments of Halimeda spp. are a major component of carbonate sediments in many tropical settings and play an important role in reef framework development and carbonate platform buildup. Consequently the calcification of H. opuntia accounts for large portions of the carbonate budget in tropical shallow marine ecosystems. Earlier studies investigating the calcification processes of Halimeda spp. have tended to focus on the microstructure or the physiology of the alga, thus overlooking the interaction of physiological and abiotic processes behind the formation of the skeleton. By analyzing microstructural skeletal features of Halimeda segments with the aid of scanning electron microscopy and relating their occurrence to known physiological processes, we have been able to identify the initiation of calcification within an organic matrix and demonstrate that biologically induced cementation is an important process in calcification. For the first time, we propose a model for the calcification of Halimeda spp. that considers both the alga's physiology and the carbon chemistry of the seawater with respect to the development of different skeletal features. The presence of an organic matrix and earlier detected external carbonic anhydrase activity suggest that Halimeda spp. exhibit biotic precipitation of calcium carbonate, as many other species of marine organisms do. On the other hand, it is the formation of micro-anhedral carbonate through the alga's metabolism that leads to a cementation of living segments. Precisely, this process allows H. opuntia to contribute substantial amounts of carbonate sediments to tropical shallow seas.

  2. Hylodesmus singaporensis gen. et sp. nov., a new autosporic subaerial green alga (Scenedesmaceae, Chlorophyta) from Singapore.

    PubMed

    Eliás, Marek; Nemcová, Yvonne; Skaloud, Pavel; Neustupa, Jirí; Kaufnerová, Veronika; Sejnohová, Lenka

    2010-05-01

    The algal flora of subaerial habitats in the tropics remains largely unexplored, despite the fact that it potentially encompasses a wealth of new evolutionary diversity. Here we present a detailed morphological and molecular characterization of an autosporic coccoid green alga isolated from decaying wood in a natural forest in Singapore. Depending on culture conditions, this alga formed globular to irregularly oval solitary cells. Autosporulation was the only mode of reproduction observed. The cell periphery was filled with numerous vacuoles, and a single parietal chloroplast contained a conspicuous pyrenoid surrounded by a bipartite starch envelope. The cell wall was composed of a thick inner layer and a thin trilaminar outer layer, and the cell surface was ornamented with a few delicate ribs. Phylogenetic analyses of 18S rRNA gene sequences placed our strain in the family Scenedesmaceae (Sphaeropleales, Chlorophyceae) as a strongly supported sister branch of the genus Desmodesmus. Analyses of an alternative phylogenetic marker widely used for the Scenedesmaceae, the ITS2 region, confirmed that the strain is distinct from any scenedesmacean alga sequenced to date, but is related to the genus Desmodesmus, despite lacking the defining phenotypic features of Desmodesmus (cell wall with four sporopolleninic layers ornamented with peculiar submicroscopic structures). Collectively, our results establish that we identified a novel, previously undocumented, evolutionary lineage of scenedesmacean algae necessitating its description as a new species in a new genus. We propose it be named Hylodesmus singaporensis gen. et sp. nov. A cryopreserved holotype specimen has been deposited into the Culture Collection of Algae of Charles University in Prague, Czech Republic (CAUP) as CAUP C-H8001.

  3. Photosynthetic biomanufacturing in green algae; production of recombinant proteins for industrial, nutritional, and medical uses.

    PubMed

    Rasala, Beth A; Mayfield, Stephen P

    2015-03-01

    Recombinant proteins are widely used for industrial, nutritional, and medical applications. Green microalgae have attracted considerable attention recently as a biomanufacturing platform for the production of recombinant proteins for a number of reasons. These photosynthetic eukaryotic microorganisms are safe, scalable, easy to genetically modify through transformation, mutagenesis, or breeding, and inexpensive to grow. Many microalgae species are genetically transformable, but the green alga Chlamydomonas reinhardtii is the most widely used host for recombinant protein expression. An extensive suite of molecular genetic tools has been developed for C. reinhardtii over the last 25 years, including a fully sequenced genome, well-established methods for transformation, mutagenesis and breeding, and transformation vectors for high levels of recombinant protein accumulation and secretion. Here, we review recent successes in the development of C. reinhardtii as a biomanufacturing host for recombinant proteins, including antibodies and immunotoxins, hormones, industrial enzymes, an orally-active colostral protein for gastrointestinal health, and subunit vaccines. In addition, we review the biomanufacturing potential of other green algae from the genera Dunaliella and Chlorella.

  4. Photosynthetic unit size, carotenoids, and chlorophyll-protein composition of Prochloron sp., a prokaryotic green alga.

    PubMed

    Withers, N W; Alberte, R S; Lewin, R A; Thornber, J P; Britton, G; Goodwin, T W

    1978-05-01

    Six samples of the prokaryotic, unicellular algae Prochloron sp., which occur in association with didemnid ascidians, were collected from various localities in the tropical Pacific Ocean, and their pigments and chlorophyll-protein complexes were identified and characterized. No phycobilin pigments were detected in any of the species. Chlorophylls a and b were present in ratios of a/b = 4.4-6.9. The major carotenoids were beta-carotene (70%) and zeaxanthin (20%). Minor carotenoids of one isolate were identified as echinenone, cryptoxanthin, isocryptoxanthin, mutachrome, and trihydroxy-beta-carotene; no epsilon-ring carotenoids were found in any sample. Except for the absence of glycosidic carotenoids, the overall pigment composition is typical of cyanobacteria. A chlorophyll a/b-protein complex was present in Prochloron; it was electrophoretically and spectrally indistinguishable from the light-harvesting chlorophyll a/b-protein of higher plants and green algae. It accounted for 26% (compared to approximately 50% in green plants) of the total chlorophyll; 17% was associated with a P700-chlorophyll a-protein. The photosynthetic unit size of 240 +/- 10 chlorophylls per P700 in Prochloron was about half that of eukaryotic green plants. A model is proposed for the in vivo organization of chlorophyll in Prochloron.

  5. Reproduction-related effects of green alga Coccomyxa sp. infestation in the horse mussel Modiolus modiolus.

    PubMed

    Vaschenko, M A; Kovaleva, A L; Syasina, I G; Kukhlevsky, A D

    2013-05-01

    The effects of Coccomyxa sp. infestation on the reproductive characteristics of the horse mussel Modiolus modiolus from the north-western Pacific (Peter the Great Bay, Sea of Japan) are demonstrated in this study. The mussels were collected monthly from May to September of 2009, and the prevalence of females and males with green tissues was 39% and 47%, respectively. Overall, the green alga infection caused a mild effect on gametogenesis in the horse mussel. The dynamics of gonad development in the healthy and infected mussels during the study period was generally similar, with the spawning being partial and occurring from the beginning of June to the first half of September; total spawning was recorded at the end of this period. However, several negative reproduction-related effects of the green alga infestation were observed, i.e., general gonadal underdevelopment, which was apparent from significant decrease in the acinus areas of the ovaries and testes and an increase in the connective tissue layer between the acini, a delay in some stages of the reproductive cycle and production of decreased number of spermatozoa and large vitellogenic oocytes, especially in the early spawning period (June). All of these results suggest a reduced reproductive output for the infected mussels. Copyright © 2013 Elsevier Inc. All rights reserved.

  6. Common Ancestry Is a Poor Predictor of Competitive Traits in Freshwater Green Algae.

    PubMed

    Narwani, Anita; Alexandrou, Markos A; Herrin, James; Vouaux, Alaina; Zhou, Charles; Oakley, Todd H; Cardinale, Bradley J

    2015-01-01

    Phytoplankton species traits have been used to successfully predict the outcome of competition, but these traits are notoriously laborious to measure. If these traits display a phylogenetic signal, phylogenetic distance (PD) can be used as a proxy for trait variation. We provide the first investigation of the degree of phylogenetic signal in traits related to competition in freshwater green phytoplankton. We measured 17 traits related to competition and tested whether they displayed a phylogenetic signal across a molecular phylogeny of 59 species of green algae. We also assessed the fit of five models of trait evolution to trait variation across the phylogeny. There was no significant phylogenetic signal for 13 out of 17 ecological traits. For 7 traits, a non-phylogenetic model provided the best fit. For another 7 traits, a phylogenetic model was selected, but parameter values indicated that trait variation evolved recently, diminishing the importance of common ancestry. This study suggests that traits related to competition in freshwater green algae are not generally well-predicted by patterns of common ancestry. We discuss the mechanisms by which the link between phylogenetic distance and phenotypic differentiation may be broken.

  7. Recovery of photosynthesis and growth rate in green, blue-green, and diatom algae after exposure to atrazine.

    PubMed

    Brain, Richard A; Arnie, Joshua R; Porch, John R; Hosmer, Alan J

    2012-11-01

    We evaluated the recovery of photosynthesis and growth rate in green (Pseudokirchneriella subcapitata), blue-green (Anabaena flos-aquae), and diatom (Navicula pelliculosa) algae after pulsed exposure to atrazine. Subsequent to a grow-up period of 24 to 72 h to establish requisite cell density for adequate signal strength to measure photosystem II (PSII) quantum yield, algae were exposed to a pulse of atrazine for 48 h followed by a 48-h recovery period in control media. Photosynthesis was measured at 0, 3, 6, 12, 24, and 48 h of the exposure and recovery phases using pulse amplitude modulation fluorometry; growth rate and cell density were also concomitantly measured at these time points. Exposure to atrazine resulted in immediate, but temporary, inhibition of photosynthesis and growth; however, these effects were transient and fully reversible in the tested species of algae. For all three algal species, no statistically significant reductions (p ≤ 0.05) in growth rate or PSII quantum yield were detected at any of the treatment concentrations 48 h after atrazine was removed from the test system. Effects at test levels up to the highest tested exposure levels were consequently determined to be algistatic (reversible). Both biochemically and physiologically, recovery of photosynthesis and growth rate occur immediately, reaching control levels within hours following exposure. Therefore, pulsed exposure profiles of atrazine typically measured in Midwestern U.S. streams are unlikely to result in biologically meaningful changes in primary production given that the effects of atrazine are temporary and fully reversible in species representative of native populations.

  8. Distribution patterns and impact of transposable elements in genes of green algae.

    PubMed

    Philippsen, Gisele S; Avaca-Crusca, Juliana S; Araujo, Ana P U; DeMarco, Ricardo

    2016-12-05

    Transposable elements (TEs) are DNA sequences able to transpose in the host genome, a remarkable feature that enables them to influence evolutive trajectories of species. An investigation about the TE distribution and TE impact in different gene regions of the green algae species Chlamydomonas reinhardtii and Volvox carteri was performed. Our results indicate that TEs are very scarce near introns boundaries, suggesting that insertions in this region are negatively selected. This contrasts with previous results showing enrichment of tandem repeats in introns boundaries and suggests that different evolutionary forces are acting in these different classes of repeats. Despite the relatively low abundance of TEs in the genome of green algae when compared to mammals, the proportion of poly(A) sites derived from TEs found in C. reinhardtii was similar to that described in human and mice. This fact, associated with the enrichment of TEs in gene 5' and 3' flanks of C. reinhardtii, opens up the possibility that TEs may have considerably contributed for gene regulatory sequences evolution in this species. Moreover, it was possible identify several instances of TE exonization for C. reinhardtii, with a particularly interesting case from a gene coding for Condensin II, a protein involved in the maintenance of chromosomal structure, where the addition of a transposomal PHD finger may contribute to binding specificity of this protein. Taken together, our results suggest that the low abundance of TEs in green algae genomes is correlated with a strict negative selection process, combined with the retention of copies that contribute positively with gene structures. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. PredAlgo: a new subcellular localization prediction tool dedicated to green algae.

    PubMed

    Tardif, Marianne; Atteia, Ariane; Specht, Michael; Cogne, Guillaume; Rolland, Norbert; Brugière, Sabine; Hippler, Michael; Ferro, Myriam; Bruley, Christophe; Peltier, Gilles; Vallon, Olivier; Cournac, Laurent

    2012-12-01

    The unicellular green alga Chlamydomonas reinhardtii is a prime model for deciphering processes occurring in the intracellular compartments of the photosynthetic cell. Organelle-specific proteomic studies have started to delineate its various subproteomes, but sequence-based prediction software is necessary to assign proteins subcellular localizations at whole genome scale. Unfortunately, existing tools are oriented toward land plants and tend to mispredict the localization of nuclear-encoded algal proteins, predicting many chloroplast proteins as mitochondrion targeted. We thus developed a new tool called PredAlgo that predicts intracellular localization of those proteins to one of three intracellular compartments in green algae: the mitochondrion, the chloroplast, and the secretory pathway. At its core, a neural network, trained using carefully curated sets of C. reinhardtii proteins, divides the N-terminal sequence into overlapping 19-residue windows and scores the probability that they belong to a cleavable targeting sequence for one of the aforementioned organelles. A targeting prediction is then deduced for the protein, and a likely cleavage site is predicted based on the shape of the scoring function along the N-terminal sequence. When assessed on an independent benchmarking set of C. reinhardtii sequences, PredAlgo showed a highly improved discrimination capacity between chloroplast- and mitochondrion-localized proteins. Its predictions matched well the results of chloroplast proteomics studies. When tested on other green algae, it gave good results with Chlorophyceae and Trebouxiophyceae but tended to underpredict mitochondrial proteins in Prasinophyceae. Approximately 18% of the nuclear-encoded C. reinhardtii proteome was predicted to be targeted to the chloroplast and 15% to the mitochondrion.

  10. Abiotic Stress Tolerance of Charophyte Green Algae: New Challenges for Omics Techniques.

    PubMed

    Holzinger, Andreas; Pichrtová, Martina

    2016-01-01

    Charophyte green algae are a paraphyletic group of freshwater and terrestrial green algae, comprising the classes of Chlorokybophyceae, Coleochaetophyceae, Klebsormidiophyceae, Zygnematophyceae, Mesostigmatophyceae, and Charo- phyceae. Zygnematophyceae (Conjugating green algae) are considered to be closest algal relatives to land plants (Embryophyta). Therefore, they are ideal model organisms for studying stress tolerance mechanisms connected with transition to land, one of the most important events in plant evolution and the Earth's history. In Zygnematophyceae, but also in Coleochaetophyceae, Chlorokybophyceae, and Klebsormidiophyceae terrestrial members are found which are frequently exposed to naturally occurring abiotic stress scenarios like desiccation, freezing and high photosynthetic active (PAR) as well as ultraviolet (UV) irradiation. Here, we summarize current knowledge about various stress tolerance mechanisms including insight provided by pioneer transcriptomic and proteomic studies. While formation of dormant spores is a typical strategy of freshwater classes, true terrestrial groups are stress tolerant in vegetative state. Aggregation of cells, flexible cell walls, mucilage production and accumulation of osmotically active compounds are the most common desiccation tolerance strategies. In addition, high photophysiological plasticity and accumulation of UV-screening compounds are important protective mechanisms in conditions with high irradiation. Now a shift from classical chemical analysis to next-generation genome sequencing, gene reconstruction and annotation, genome-scale molecular analysis using omics technologies followed by computer-assisted analysis will give new insights in a systems biology approach. For example, changes in transcriptome and role of phytohormone signaling in Klebsormidium during desiccation were recently described. Application of these modern approaches will deeply enhance our understanding of stress reactions in an

  11. Abiotic Stress Tolerance of Charophyte Green Algae: New Challenges for Omics Techniques

    PubMed Central

    Holzinger, Andreas; Pichrtová, Martina

    2016-01-01

    Charophyte green algae are a paraphyletic group of freshwater and terrestrial green algae, comprising the classes of Chlorokybophyceae, Coleochaetophyceae, Klebsormidiophyceae, Zygnematophyceae, Mesostigmatophyceae, and Charo- phyceae. Zygnematophyceae (Conjugating green algae) are considered to be closest algal relatives to land plants (Embryophyta). Therefore, they are ideal model organisms for studying stress tolerance mechanisms connected with transition to land, one of the most important events in plant evolution and the Earth’s history. In Zygnematophyceae, but also in Coleochaetophyceae, Chlorokybophyceae, and Klebsormidiophyceae terrestrial members are found which are frequently exposed to naturally occurring abiotic stress scenarios like desiccation, freezing and high photosynthetic active (PAR) as well as ultraviolet (UV) irradiation. Here, we summarize current knowledge about various stress tolerance mechanisms including insight provided by pioneer transcriptomic and proteomic studies. While formation of dormant spores is a typical strategy of freshwater classes, true terrestrial groups are stress tolerant in vegetative state. Aggregation of cells, flexible cell walls, mucilage production and accumulation of osmotically active compounds are the most common desiccation tolerance strategies. In addition, high photophysiological plasticity and accumulation of UV-screening compounds are important protective mechanisms in conditions with high irradiation. Now a shift from classical chemical analysis to next-generation genome sequencing, gene reconstruction and annotation, genome-scale molecular analysis using omics technologies followed by computer-assisted analysis will give new insights in a systems biology approach. For example, changes in transcriptome and role of phytohormone signaling in Klebsormidium during desiccation were recently described. Application of these modern approaches will deeply enhance our understanding of stress reactions in an

  12. The molecular structure of the fastest myosin from green algae, Chara.

    PubMed

    Morimatsu, M; Nakamura, A; Sumiyoshi, H; Sakaba, N; Taniguchi, H; Kohama, K; Higashi-Fujime, S

    2000-04-02

    Chara myosin in green algae, Chara corallina, is the fastest myosin of all those observed so far. To shed light on the molecular mechanism of this fast sliding, we determined the primary structure of Chara myosin heavy chain (hc). It has a motor domain, six IQ motifs for calmodulin binding, a coiled-coil structure to dimerize, and a globular tail. Chara myosin hc is very similar to some plant myosins and has been predicted to belong to the class XI. Short loop 1 and loop 2 may account for the characteristics of mechanochemical properties of Chara myosin. Copyright 2000 Academic Press.

  13. Inhibitory effects of terpene alcohols and aldehydes on growth of green alga Chlorella pyrenoidosa

    SciTech Connect

    Ikawa, Miyoshi; Mosley, S.P.; Barbero, L.J. )

    1992-10-01

    The growth of the green alga Chlorella pyrenoidosa was inhibited by terpene alcohols and the terpene aldehyde citral. The strongest activity was shown by citral. Nerol, geraniol, and citronellol also showed pronounced activity. Strong inhibition was linked to acyclic terpenes containing a primary alcohol or aldehyde function. Inhibition appeared to be taking place through the vapor phase rather than by diffusion through the agar medium from the terpene-treated paper disks used in the system. Inhibition through agar diffusion was shown by certain aged samples of terpene hydrocarbons but not by recently purchased samples.

  14. Viruses of eukaryotic green algae. Progress report, August 1, 1984-March 1, 1986

    SciTech Connect

    Van Etten, J.L.

    1986-01-01

    PBCV-1 is a large dsDNA-containing, plaque forming virus that replicates in a unicellular, eukaryotic Chlorella-like green alga strain NC64A. We have discovered that PBCV-1 infection results in the appearance of a restriction and modification system in the host. Furthermore, we have isolated and partially characterized 30 additional large, dsDNA-containing viruses which replicate in the same host. Some, if not all, of these viruses probably induce the synthesis of modification and restriction systems which are different from that induced by PBCV-1. 16 refs.

  15. Factors influencing dark nitrogen fixation in a blue-green alga.

    PubMed

    Fay, P

    1976-03-01

    Nitrogen-fixing activity declines first rapidly and then more gradually when Anabaenopsis circularis is transferred from light into dark conditions. The rate and duration of dark acetylene reduction (nitrogen fixation) depend upon conditions prevailing during the preceding light period. Factors (such as light intensity, CO2 concentration, and supply of glucose), which in the light affect photosynthesis and the accumulation of reserve carbon, have a profound effect on dark nitrogen fixation. Glucose greatly promotes nitrogen fixation in the light and supports prolonged nitrogenase activity in the dark. The results suggest that heterotrophic nitrogen fixation by blue-green algae in the field may be important both under light and dark conditions.

  16. Identification of a copper-sensitive ascorbate peroxidase in the unicellular green alga Selenastrum capricornutum.

    PubMed

    Sauser, K R; Liu, J K; Wong, T Y

    1997-07-01

    Extracts from the unicellular green alga Selenastrum capricornutum exhibit high superoxide dismutase activity, but only traces of catalase activity. The excess hydrogen peroxide (H2O2) generated by the superoxide dismutase in S. capricornutum may be degraded by a unique peroxidase. This peroxidase has a high specificity for ascorbate as its electron donor. The enzyme has an optimum pH at 8, is insensitive to cyanide and is inhibited by oxine. Addition of low concentrations of copper to algal cultures stimulates the peroxidase activity threefold. This enzymatic system could be used as a sensitive bioindicator for copper in fresh water.

  17. Langmuir-Blodgett film of phycobilisomes from blue-green alga Spirulina platensis.

    PubMed

    Chen, Chao; Zhang, Yu-Zhong; Chen, Xiu-Lan; Zhou, Bai-Cheng; Gao, Hong-Jun

    2003-10-01

    The phycobilisomes were isolated from blue-green alga Spirulina platensis, and could form monolayer film at air/water interface. The monolayer film of phycobilisomes was transferred to newly cleaved mica, and coated with gold. Scanning tunneling microscope was used to investigate the structure of the Langmuir-Blodgett film of phycobilisomes. It was shown that phycobilisomes in the monolayer arrayed in rows with core attaching on the substrate surface and rods radiating towards the air phase, this phenomenon was similar to the arrangement of phycobilisomes on cytoplasmic surface of thylakoid membrane in vivo. The possible applications of the Langmuir-Blodgett film of phycobilisomes were also discussed.

  18. Detecting massive green algae ( Ulva prolifera) blooms in the Yellow Sea and East China Sea using Geostationary Ocean Color Imager (GOCI) data

    NASA Astrophysics Data System (ADS)

    Son, Young Baek; Min, Jee-Eun; Ryu, Joo-Hyung

    2012-09-01

    The historically massive bloom of the green macroalgae Ulva prolifera reported in June-August 2008 around the Qingdao, Yellow Sea, East China Sea and Japan coasts has recurred in a similar season and region. On June 13, 2011, around Qingdao, China, the world's first Geostationary Ocean Color Imager (GOCI) detected an enormous bloom of floating green algae, which originated from the nearshore Subei Bank, China. The large floating green algae patches were observed along and across the Yellow Sea and in the East China Sea during 2011 summer by various oceanic cruises. To detect the massive macroalgae blooms from space, we analyzed their spectral characteristics from in situ optical measurements and satellite-derived green algae spectra. An "Index of floating Green Algae for GOCI" (IGAG) was developed from the multiple spectral band ratios using three wavelengths (555, 660, 745 nm), which the spectral response of green algae reflected at 555, 745, and 865 nm and absorbed at 660 and 680 nm. The results were compared with those obtained by the normalized difference vegetation index (NDVI), enhanced vegetation index (EVI), and Korea Ocean Satellite Center (KOSC) approaches. An advantage of the IGAG method was that muted or subtle signals of floating green algae were enhanced and separated from surrounding complex water signals. Although maps of floating green algae derived by the other approaches delineated dense green algae, they were less sensitive to subtle (less dense) features and in cases of nearby cloudy or complex water conditions. The floating green algae maps from IGAG provided a more robust estimate of wide floating green algae blooms than those derived using NDVI, EVI, or KOSC approaches. The IGAG approach should be useful for tracing and monitoring changes in green algae blooms on regional and global scales.

  19. The culturable mycobiota of Flabellia petiolata: First survey of marine fungi associated to a Mediterranean green alga.

    PubMed

    Gnavi, Giorgio; Garzoli, Laura; Poli, Anna; Prigione, Valeria; Burgaud, Gaëtan; Varese, Giovanna Cristina

    2017-01-01

    Algae-inhabiting marine fungi represent a taxonomically and ecologically interesting group of microorganisms still largely neglected, especially in temperate regions. The aim of this study was to isolate and to identify the culturable mycobiota associated with Flabellia petiolata, a green alga frequently retrieved in the Mediterranean basin. Twenty algal thalli were collected from two different sampling sites in the Mediterranean Sea (Elba Island, Italy). A polyphasic approach showed the presence of a relevant alga-associated mycobiota with 64 taxa identified. The fungal isolates belonged mainly to Ascomycota (61 taxa), while only three Basidiomycota were detected. The phylogenetic position of sterile mycelia and cryptic taxa, inferred on the basis of LSU partial region, highlighted the presence of putative new phylogenetic lineages within Dothideomycetes and Sordariomycetes. This work represents the first quali-quantitative analysis of the culturable mycobiota associated to a green alga in the Mediterranean Sea.

  20. The culturable mycobiota of Flabellia petiolata: First survey of marine fungi associated to a Mediterranean green alga

    PubMed Central

    Garzoli, Laura; Poli, Anna; Prigione, Valeria; Burgaud, Gaëtan; Varese, Giovanna Cristina

    2017-01-01

    Algae-inhabiting marine fungi represent a taxonomically and ecologically interesting group of microorganisms still largely neglected, especially in temperate regions. The aim of this study was to isolate and to identify the culturable mycobiota associated with Flabellia petiolata, a green alga frequently retrieved in the Mediterranean basin. Twenty algal thalli were collected from two different sampling sites in the Mediterranean Sea (Elba Island, Italy). A polyphasic approach showed the presence of a relevant alga-associated mycobiota with 64 taxa identified. The fungal isolates belonged mainly to Ascomycota (61 taxa), while only three Basidiomycota were detected. The phylogenetic position of sterile mycelia and cryptic taxa, inferred on the basis of LSU partial region, highlighted the presence of putative new phylogenetic lineages within Dothideomycetes and Sordariomycetes. This work represents the first quali-quantitative analysis of the culturable mycobiota associated to a green alga in the Mediterranean Sea. PMID:28426712

  1. Impact of two different humic substances on selected coccal green algae and cyanobacteria--changes in growth and photosynthetic performance.

    PubMed

    Bährs, Hanno; Steinberg, Christian E W

    2012-02-01

    There is growing evidence to show that dissolved humic substances, HSs, can directly interact with freshwater organisms, such as phototrophic organisms, cladocerans, amphipods and fish. The responses are-at least in part-transcriptionally controlled. These interactions can lead to stress symptoms in the exposed organisms. In phototrophs, stress symptoms include a reduction in photosynthetic oxygen release and antioxidative stress. Besides the direct effects, HSs also cause indirect effects that provoke different physiological adaptations in the phototrophs. The HS-influenced photosynthetic performance and stress response of two different green algae, Pseudokirchneriella subcapitata (Koršikov) Hindák and Monoraphidium braunii (Nägeli in Kützing) Komárková-Legnerová, and two cyanobacterial species, Synechocystis sp. (PCC 6803, Institut Pasteur) and Microcystis aeruginosa (PCC 7806, Institut Pasteur), were tested. Two humic preparations were applied, the synthetic HS1500 and HuminFeed, HF, which had previously been proven effective in bioassays with invertebrates and a water mould. When the algae were grown near light saturation, most of the tested species were positively affected by HSs in growth rate or chlorophyll content. Cell sizes decreased with increasing HS concentrations for all eukaryotic phototrophs, except for the cyanobacteria. After 4 to 5 days of cultivation at the highest HS exposure, there was a decrease in total dry weight due to reduced cell sizes in contrast to an increase in cell numbers. With the exception of Synechocystis, the dry weight per cell ratio decreased with increasing HS concentration. The efficiency of utilizing absorbed light quanta increased with increasing HS concentrations; the maximum quantum yield of photosystem II (ΦPSIImax) was higher in all of the tested species, with the exception of M. aeruginosa, after exposure to HS. The applied humic preparations did not interact directly with PSII, but changed the physiological

  2. Functional Characterization of UDP-apiose Synthases from Bryophytes and Green Algae Provides Insight into the Appearance of Apiose-containing Glycans during Plant Evolution.

    PubMed

    Smith, James; Yang, Yiwen; Levy, Shahar; Adelusi, Oluwatoyin Oluwayemi; Hahn, Michael G; O'Neill, Malcolm A; Bar-Peled, Maor

    2016-10-07

    Apiose is a branched monosaccharide that is present in the cell wall pectic polysaccharides rhamnogalacturonan II and apiogalacturonan and in numerous plant secondary metabolites. These apiose-containing glycans are synthesized using UDP-apiose as the donor. UDP-apiose (UDP-Api) together with UDP-xylose is formed from UDP-glucuronic acid (UDP-GlcA) by UDP-Api synthase (UAS). It was hypothesized that the ability to form Api distinguishes vascular plants from the avascular plants and green algae. UAS from several dicotyledonous plants has been characterized; however, it is not known if avascular plants or green algae produce this enzyme. Here we report the identification and functional characterization of UAS homologs from avascular plants (mosses, liverwort, and hornwort), from streptophyte green algae, and from a monocot (duckweed). The recombinant UAS homologs all form UDP-Api from UDP-glucuronic acid albeit in different amounts. Apiose was detected in aqueous methanolic extracts of these plants. Apiose was detected in duckweed cell walls but not in the walls of the avascular plants and algae. Overexpressing duckweed UAS in the moss Physcomitrella patens led to an increase in the amounts of aqueous methanol-acetonitrile-soluble apiose but did not result in discernible amounts of cell wall-associated apiose. Thus, bryophytes and algae likely lack the glycosyltransferase machinery required to synthesize apiose-containing cell wall glycans. Nevertheless, these plants may have the ability to form apiosylated secondary metabolites. Our data are the first to provide evidence that the ability to form apiose existed prior to the appearance of rhamnogalacturonan II and apiogalacturonan and provide new insights into the evolution of apiose-containing glycans.

  3. Functional Characterization of UDP-apiose Synthases from Bryophytes and Green Algae Provides Insight into the Appearance of Apiose-containing Glycans during Plant Evolution*

    PubMed Central

    Smith, James; Yang, Yiwen; Levy, Shahar; Adelusi, Oluwatoyin Oluwayemi; Hahn, Michael G.; O'Neill, Malcolm A.; Bar-Peled, Maor

    2016-01-01

    Apiose is a branched monosaccharide that is present in the cell wall pectic polysaccharides rhamnogalacturonan II and apiogalacturonan and in numerous plant secondary metabolites. These apiose-containing glycans are synthesized using UDP-apiose as the donor. UDP-apiose (UDP-Api) together with UDP-xylose is formed from UDP-glucuronic acid (UDP-GlcA) by UDP-Api synthase (UAS). It was hypothesized that the ability to form Api distinguishes vascular plants from the avascular plants and green algae. UAS from several dicotyledonous plants has been characterized; however, it is not known if avascular plants or green algae produce this enzyme. Here we report the identification and functional characterization of UAS homologs from avascular plants (mosses, liverwort, and hornwort), from streptophyte green algae, and from a monocot (duckweed). The recombinant UAS homologs all form UDP-Api from UDP-glucuronic acid albeit in different amounts. Apiose was detected in aqueous methanolic extracts of these plants. Apiose was detected in duckweed cell walls but not in the walls of the avascular plants and algae. Overexpressing duckweed UAS in the moss Physcomitrella patens led to an increase in the amounts of aqueous methanol-acetonitrile-soluble apiose but did not result in discernible amounts of cell wall-associated apiose. Thus, bryophytes and algae likely lack the glycosyltransferase machinery required to synthesize apiose-containing cell wall glycans. Nevertheless, these plants may have the ability to form apiosylated secondary metabolites. Our data are the first to provide evidence that the ability to form apiose existed prior to the appearance of rhamnogalacturonan II and apiogalacturonan and provide new insights into the evolution of apiose-containing glycans. PMID:27551039

  4. The TOR Signaling Network in the Model Unicellular Green Alga Chlamydomonas reinhardtii

    PubMed Central

    Pérez-Pérez, María Esther; Crespo, José L.

    2017-01-01

    Cell growth is tightly coupled to nutrient availability. The target of rapamycin (TOR) kinase transmits nutritional and environmental cues to the cellular growth machinery. TOR functions in two distinct multiprotein complexes, termed TOR complex 1 (TORC1) and TOR complex 2 (TORC2). While the structure and functions of TORC1 are highly conserved in all eukaryotes, including algae and plants, TORC2 core proteins seem to be missing in photosynthetic organisms. TORC1 controls cell growth by promoting anabolic processes, including protein synthesis and ribosome biogenesis, and inhibiting catabolic processes such as autophagy. Recent studies identified rapamycin-sensitive TORC1 signaling regulating cell growth, autophagy, lipid metabolism, and central metabolic pathways in the model unicellular green alga Chlamydomonas reinhardtii. The central role that microalgae play in global biomass production, together with the high biotechnological potential of these organisms in biofuel production, has drawn attention to the study of proteins that regulate cell growth such as the TOR kinase. In this review we discuss the recent progress on TOR signaling in algae. PMID:28704927

  5. Carbon Supply and Photoacclimation Cross Talk in the Green Alga Chlamydomonas reinhardtii.

    PubMed

    Polukhina, Iryna; Fristedt, Rikard; Dinc, Emine; Cardol, Pierre; Croce, Roberta

    2016-11-01

    Photosynthetic organisms are exposed to drastic changes in light conditions, which can affect their photosynthetic efficiency and induce photodamage. To face these changes, they have developed a series of acclimation mechanisms. In this work, we have studied the acclimation strategies of Chlamydomonas reinhardtii, a model green alga that can grow using various carbon sources and is thus an excellent system in which to study photosynthesis. Like other photosynthetic algae, it has evolved inducible mechanisms to adapt to conditions where carbon supply is limiting. We have analyzed how the carbon availability influences the composition and organization of the photosynthetic apparatus and the capacity of the cells to acclimate to different light conditions. Using electron microscopy, biochemical, and fluorescence measurements, we show that differences in CO2 availability not only have a strong effect on the induction of the carbon-concentrating mechanisms but also change the acclimation strategy of the cells to light. For example, while cells in limiting CO2 maintain a large antenna even in high light and switch on energy-dissipative mechanisms, cells in high CO2 reduce the amount of pigments per cell and the antenna size. Our results show the high plasticity of the photosynthetic apparatus of C. reinhardtii This alga is able to use various photoacclimation strategies, and the choice of which to activate strongly depends on the carbon availability. © 2016 American Society of Plant Biologists. All Rights Reserved.

  6. Influence of Speciation of Thorium on Toxic Effects to Green Algae Chlorella pyrenoidosa

    PubMed Central

    Peng, Can; Ma, Yuhui; Ding, Yayun; He, Xiao; Zhang, Peng; Lan, Tu; Wang, Dongqi; Zhang, Zhaohui; Zhang, Zhiyong

    2017-01-01

    Thorium (Th) is a natural radioactive element present in the environment and has the potential to be used as a nuclear fuel. Relatively little is known about the influence and toxicity of Th in the environment. In the present study, the toxicity of Th to the green algae Chlorella pyrenoidosa (C. pyrenoidosa) was evaluated by algal growth inhibition, biochemical assays and morphologic observations. In the cultural medium (OECD TG 201), Th(NO3)4 was transformed to amorphous precipitation of Th(OH)4 due to hydrolysis. Th was toxic to C. pyrenoidosa, with a 96 h half maximum effective concentration (EC50) of 10.4 μM. Scanning electron microscopy shows that Th-containing aggregates were attached onto the surface of the algal cells, and transmission electron microscopy indicates the internalization of nano-sized Th precipitates and ultrastructural alterations of the algal cells. The heteroagglomeration between Th(OH)4 precipitation and alga cells and enhanced oxidative stress might play important roles in the toxicity of Th. To our knowledge, this is the first report of the toxicity of Th to algae with its chemical species in the exposure medium. This finding provides useful information on understanding the fate and toxicity of Th in the aquatic environment. PMID:28394275

  7. The TOR Signaling Network in the Model Unicellular Green Alga Chlamydomonas reinhardtii.

    PubMed

    Pérez-Pérez, María Esther; Couso, Inmaculada; Crespo, José L

    2017-07-12

    Cell growth is tightly coupled to nutrient availability. The target of rapamycin (TOR) kinase transmits nutritional and environmental cues to the cellular growth machinery. TOR functions in two distinct multiprotein complexes, termed TOR complex 1 (TORC1) and TOR complex 2 (TORC2). While the structure and functions of TORC1 are highly conserved in all eukaryotes, including algae and plants, TORC2 core proteins seem to be missing in photosynthetic organisms. TORC1 controls cell growth by promoting anabolic processes, including protein synthesis and ribosome biogenesis, and inhibiting catabolic processes such as autophagy. Recent studies identified rapamycin-sensitive TORC1 signaling regulating cell growth, autophagy, lipid metabolism, and central metabolic pathways in the model unicellular green alga Chlamydomonas reinhardtii. The central role that microalgae play in global biomass production, together with the high biotechnological potential of these organisms in biofuel production, has drawn attention to the study of proteins that regulate cell growth such as the TOR kinase. In this review we discuss the recent progress on TOR signaling in algae.

  8. Size-dependent ecotoxicity of barium titanate particles: the case of Chlorella vulgaris green algae.

    PubMed

    Polonini, Hudson C; Brandão, Humberto M; Raposo, Nádia R B; Brandão, Marcos Antônio F; Mouton, Ludovic; Couté, Alain; Yéprémian, Claude; Sivry, Yann; Brayner, Roberta

    2015-05-01

    Studies have been demonstrating that smaller particles can lead to unexpected and diverse ecotoxicological effects when compared to those caused by the bulk material. In this study, the chemical composition, size and shape, state of dispersion, and surface's charge, area and physicochemistry of micro (BT MP) and nano barium titanate (BT NP) were determined. Green algae Chlorella vulgaris grown in Bold's Basal (BB) medium or Seine River water (SRW) was used as biological indicator to assess their aquatic toxicology. Responses such as growth inhibition, cell viability, superoxide dismutase (SOD) activity, adenosine-5-triphosphate (ATP) content and photosynthetic activity were evaluated. Tetragonal BT (~170 nm, 3.24 m(2) g(-1) surface area) and cubic BT (~60 nm, 16.60 m(2) g(-1)) particles were negative, poorly dispersed, and readily aggregated. BT has a statistically significant effect on C. vulgaris growth since the lower concentration tested (1 ppm), what seems to be mediated by induced oxidative stress caused by the particles (increased SOD activity and decreased photosynthetic efficiency and intracellular ATP content). The toxic effects were more pronounced when the algae was grown in SRW. Size does not seem to be an issue influencing the toxicity in BT particles toxicity since micro- and nano-particles produced significant effects on algae growth.

  9. Effect of copper on the activation of the acid phosphatase from the green algae Pseudokirchneriella subcapitata.

    PubMed

    Jonsson, Claudio Martín; Aoyama, Hiroshi

    2010-02-01

    The presence of copper in water environment may have detrimental effects on aquatic organisms, including algae, where different enzymatic systems can be affected. Algae acid phosphatase plays important roles in metabolic processes such as decomposition of organic phosphate, autophagic digestive process, recycling cellular materials and zygote formation during reproduction. This work describes an in vitro activation effect of copper on the acid phosphatase of the green algae Pseudokirchneriella subcapitata (formely Selenastrum capricornutum) under preincubation condition. Apparent Michaelis constant values of 1.21 and 0.37 mM, and activation energy values of 26.8 and 13.6 kJ mol(-1) were determined in the absence and in the presence of 0.2 mM Cu(2+), respectively. The dissociation constant value for Cu(2+) binding to the enzyme was determined to be 22.04 microM. The decrease of the apparent Michaelis constant (Km) and activation energy values in the presence of Cu(2+) correlates well with its activating effect on the acid phosphatase activity. This propriety could be used as a sensitive bioindicator for copper in environmental samples.

  10. Influence of Speciation of Thorium on Toxic Effects to Green Algae Chlorella pyrenoidosa.

    PubMed

    Peng, Can; Ma, Yuhui; Ding, Yayun; He, Xiao; Zhang, Peng; Lan, Tu; Wang, Dongqi; Zhang, Zhaohui; Zhang, Zhiyong

    2017-04-10

    Thorium (Th) is a natural radioactive element present in the environment and has the potential to be used as a nuclear fuel. Relatively little is known about the influence and toxicity of Th in the environment. In the present study, the toxicity of Th to the green algae Chlorella pyrenoidosa (C. pyrenoidosa) was evaluated by algal growth inhibition, biochemical assays and morphologic observations. In the cultural medium (OECD TG 201), Th(NO₃)₄ was transformed to amorphous precipitation of Th(OH)₄ due to hydrolysis. Th was toxic to C. pyrenoidosa, with a 96 h half maximum effective concentration (EC50) of 10.4 μM. Scanning electron microscopy shows that Th-containing aggregates were attached onto the surface of the algal cells, and transmission electron microscopy indicates the internalization of nano-sized Th precipitates and ultrastructural alterations of the algal cells. The heteroagglomeration between Th(OH)₄ precipitation and alga cells and enhanced oxidative stress might play important roles in the toxicity of Th. To our knowledge, this is the first report of the toxicity of Th to algae with its chemical species in the exposure medium. This finding provides useful information on understanding the fate and toxicity of Th in the aquatic environment.

  11. Spectroscopic investigation of ionizing-radiation tolerance of a Chlorophyceae green micro-alga

    NASA Astrophysics Data System (ADS)

    Farhi, E.; Rivasseau, C.; Gromova, M.; Compagnon, E.; Marzloff, V.; Ollivier, J.; Boisson, A. M.; Bligny, R.; Natali, F.; Russo, D.; Couté, A.

    2008-03-01

    Micro-organisms living in extreme environments are captivating in the peculiar survival processes they have developed. Deinococcus radiodurans is probably the most famous radio-resistant bacteria. Similarly, a specific ecosystem has grown in a research reactor storage pool, and has selected organisms which may sustain radiative stress. An original green micro-alga which was never studied for its high tolerance to radiations has been isolated. It is the only autotrophic eukaryote that develops in this pool, although contamination possibilities coming from outside are not unusual. Studying what could explain this irradiation tolerance is consequently very interesting. An integrative study of the effects of irradiation on the micro-algae physiology, metabolism, internal dynamics, and genomics was initiated. In the work presented here, micro-algae were stressed with irradiation doses up to 20 kGy (2 Mrad), and studied by means of nuclear magnetic resonance, looking for modifications in the metabolism, and on the IN13 neutron backscattering instrument at the ILL, looking for both dynamics and structural macromolecular changes in the cells.

  12. Carbon Supply and Photoacclimation Cross Talk in the Green Alga Chlamydomonas reinhardtii1[OPEN

    PubMed Central

    Fristedt, Rikard; Dinc, Emine

    2016-01-01

    Photosynthetic organisms are exposed to drastic changes in light conditions, which can affect their photosynthetic efficiency and induce photodamage. To face these changes, they have developed a series of acclimation mechanisms. In this work, we have studied the acclimation strategies of Chlamydomonas reinhardtii, a model green alga that can grow using various carbon sources and is thus an excellent system in which to study photosynthesis. Like other photosynthetic algae, it has evolved inducible mechanisms to adapt to conditions where carbon supply is limiting. We have analyzed how the carbon availability influences the composition and organization of the photosynthetic apparatus and the capacity of the cells to acclimate to different light conditions. Using electron microscopy, biochemical, and fluorescence measurements, we show that differences in CO2 availability not only have a strong effect on the induction of the carbon-concentrating mechanisms but also change the acclimation strategy of the cells to light. For example, while cells in limiting CO2 maintain a large antenna even in high light and switch on energy-dissipative mechanisms, cells in high CO2 reduce the amount of pigments per cell and the antenna size. Our results show the high plasticity of the photosynthetic apparatus of C. reinhardtii. This alga is able to use various photoacclimation strategies, and the choice of which to activate strongly depends on the carbon availability. PMID:27637747

  13. (Carbon and hydrogen metabolism of green algae in light and dark)

    SciTech Connect

    Not Available

    1990-01-01

    The focus of this project was the elucidation of anaerobic metabolism in ecuaryotic green algae, chlamydomonas reinhardii. Chlamydomonas is a versatile organism that can grow under disparate conditions such as fresh water lakes and sewage ponds. The cell an photoassimilate CO{sub 2} aerobically and anaerobically, the latter after adaptation'' to a hydrogen metabolism. It can recall the knallgas or oxyhydrogen reaction and utilize hydrogen the simplest of all reducing agents for the dark assimilation of CO{sub 2} by the photosynthetic carbon reduction cycle. The dark reduction with hydrogen lies on the border line between autotrophic and heterotrophic carbon assimilation. Both autotrophic and heterotrophic bacteria are known in which molecular hydrogen can replace either inorganic or organic hydrogen donors. Here the dark reduction of CO{sub 2} acquires a particular importance since it occurs in the same cell that carries on photoreduction and photosynthesis. We will demonstrate here that the alga chloroplast possesses a respiratory capacity. It seems likely that Chlamydomonas may have retained the chloroplastic respiratory pathway because of the selective advantage provided to the algae under a wide range of environmental conditions that the cells experience in nature. The ability to cycle electrons and poise the reduction level of the photosynthetic apparatus under aerobic and microaerobic conditions could allow more efficient CO{sub 2} fixation and enhanced growth under unfavorable conditions or survival under more severe conditions.

  14. Molecular identification of green algae from the rafts based infrastructure of Porphyra yezoensis.

    PubMed

    Shen, Qi; Li, Hongye; Li, Yan; Wang, Zongling; Liu, Jiesheng; Yang, Weidong

    2012-10-01

    To provide more information on the origin of the Ulva prolifera bloom in Qingdao sea area in China from 2007 to 2011, the diversity of green algae growing on the rafts of Porphyra yezoensis on the coast in Jiangsu Province was investigated based on ITS, rbcL and 5S sequences. Eighty-four of green algal samples from various sites and cruises in 2010 and 2011 were collected. According to ITS and rbcL sequences, samples from the rafts of P. yezoensis fell into four clades: Ulva linza-procera-prolifera (LPP) complex, Ulva flexuosa, Blidingia sp. and Urospora spp. However, based on the 5S rDNA, a more resolved DNA marker, only one of the 84 samples belonged to U. prolifera. Combined with the previous reports, it is likely that U. prolifera bloom in Qingdao sea area might consist of more than one origin, and Porphyra cultivation rafts might be one of the causes.

  15. Requirement of low oxidation-reduction potential for photosynthesis in a blue-green alga (Phormidium sp.).

    PubMed

    Weller, D; Doemel, W; Brock, T D

    1975-06-20

    Photosynthesis in a Phormidium species which forms dense conical-shaped structures in thermal springs is strongly inhibited by aeration but is stimulated by sulfide and other agents (cysteine, thioglycolate, sulfite) which lower the oxidation-reduction potential. The compact structures which this alga forms in nature may restrict oxygen penetration from the enviroment so that the anaerobic or microaerophilic conditions necessary ofr photosynthesis can develop. The alga may be defective in a regulatory mechanism that controls the reoxidation of reduced pyridine nucleotides formed during photosynthesis. It is suggested that other mat-forming and benthic blue-green algae may also prefer anaerobib conditions for growth and photosynthesis.

  16. Determination of Volatile Compounds in Four Commercial Samples of Japanese Green Algae Using Solid Phase Microextraction Gas Chromatography Mass Spectrometry

    PubMed Central

    Yoshikawa, Keisuke; Fujita, Akira; Mase, Nobuyuki; Watanabe, Naoharu

    2014-01-01

    Green algae are of great economic importance. Seaweed is consumed fresh or as seasoning in Japan. The commercial value is determined by quality, color, and flavor and is also strongly influenced by the production area. Our research, based on solid phase microextraction gas chromatography mass spectrometry (SPME-GC-MS), has revealed that volatile compounds differ intensely in the four varieties of commercial green algae. Accordingly, 41 major volatile compounds were identified. Heptadecene was the most abundant compound from Okayama (Ulva prolifera), Tokushima (Ulva prolifera), and Ehime prefecture (Ulva linza). Apocarotenoids, such as ionones, and their derivatives were prominent volatiles in algae from Okayama (Ulva prolifera) and Tokushima prefecture (Ulva prolifera). Volatile, short chained apocarotenoids are among the most potent flavor components and contribute to the flavor of fresh, processed algae, and algae-based products. Benzaldehyde was predominant in seaweed from Shizuoka prefecture (Monostroma nitidum). Multivariant statistical analysis (PCA) enabled simple discrimination of the samples based on their volatile profiles. This work shows the potential of SPME-GC-MS coupled with multivariant analysis to discriminate between samples of different geographical and botanical origins and form the basis for development of authentication methods of green algae products, including seasonings. PMID:24592162

  17. Determination of volatile compounds in four commercial samples of Japanese green algae using solid phase microextraction gas chromatography mass spectrometry.

    PubMed

    Yamamoto, Masayoshi; Baldermann, Susanne; Yoshikawa, Keisuke; Fujita, Akira; Mase, Nobuyuki; Watanabe, Naoharu

    2014-01-01

    Green algae are of great economic importance. Seaweed is consumed fresh or as seasoning in Japan. The commercial value is determined by quality, color, and flavor and is also strongly influenced by the production area. Our research, based on solid phase microextraction gas chromatography mass spectrometry (SPME-GC-MS), has revealed that volatile compounds differ intensely in the four varieties of commercial green algae. Accordingly, 41 major volatile compounds were identified. Heptadecene was the most abundant compound from Okayama (Ulva prolifera), Tokushima (Ulva prolifera), and Ehime prefecture (Ulva linza). Apocarotenoids, such as ionones, and their derivatives were prominent volatiles in algae from Okayama (Ulva prolifera) and Tokushima prefecture (Ulva prolifera). Volatile, short chained apocarotenoids are among the most potent flavor components and contribute to the flavor of fresh, processed algae, and algae-based products. Benzaldehyde was predominant in seaweed from Shizuoka prefecture (Monostroma nitidum). Multivariant statistical analysis (PCA) enabled simple discrimination of the samples based on their volatile profiles. This work shows the potential of SPME-GC-MS coupled with multivariant analysis to discriminate between samples of different geographical and botanical origins and form the basis for development of authentication methods of green algae products, including seasonings.

  18. Phagotrophy by the picoeukaryotic green alga Micromonas: implications for Arctic Oceans.

    PubMed

    McKie-Krisberg, Zaid M; Sanders, Robert W

    2014-10-01

    Photosynthetic picoeukaryotes (PPE) are recognized as major primary producers and contributors to phytoplankton biomass in oceanic and coastal environments. Molecular surveys indicate a large phylogenetic diversity in the picoeukaryotes, with members of the Prymnesiophyceae and Chrysophyseae tending to be more common in open ocean waters and Prasinophyceae dominating coastal and Arctic waters. In addition to their role as primary producers, PPE have been identified in several studies as mixotrophic and major predators of prokaryotes. Mixotrophy, the combination of photosynthesis and phagotrophy in a single organism, is well established for most photosynthetic lineages. However, green algae, including prasinophytes, were widely considered as a purely photosynthetic group. The prasinophyte Micromonas is perhaps the most common picoeukaryote in coastal and Arctic waters and is one of the relatively few cultured representatives of the picoeukaryotes available for physiological investigations. In this study, we demonstrate phagotrophy by a strain of Micromonas (CCMP2099) isolated from Arctic waters and show that environmental factors (light and nutrient concentration) affect ingestion rates in this mixotroph. In addition, we show size-selective feeding with a preference for smaller particles, and determine P vs I (photosynthesis vs irradiance) responses in different nutrient conditions. If other strains have mixotrophic abilities similar to Micromonas CCMP2099, the widespread distribution and frequently high abundances of Micromonas suggest that these green algae may have significant impact on prokaryote populations in several oceanic regimes.

  19. Combined exposure to hydrogen peroxide and light--selective effects on cyanobacteria, green algae, and diatoms.

    PubMed

    Drábková, Michaela; Admiraal, Wim; Marsálek, Blahoslav

    2007-01-01

    The selective toxicity of H2O2 was investigated to develop a potential tool for limiting cyanobacterial blooms and to better understand the occurrence of cyanobacteria and other phytoplankton species in relation to reactive oxygen species in surface waters. The cyanobacterium Microcystis aeruginosa, the green alga Pseudokirchneriella subcapitata, and the diatom Navicula seminulum were tested under pulse exposure to H202 in the dark and at various irradiances. H2O2 was decomposed at rates depending on algal species and was proportional to irradiance. The cyanobacterium was affected by H202 at 10 times lower concentrations than green alga and diatom, and a strong light-dependent toxicity enhanced the difference. The inhibition was measured as photosynthetic yield (Fv/Fm) in pulse amplitude modulated fluorometry, and was confirmed by changes in minimal fluorescence (F0) and photosynthetic oxygen evolution. Single doses of 0.27 mg L(-1) of H202 caused 50% inhibition to M. aeruginosa at high irradiance. Such concentration overlaps with the highest levels of 0.34 mg L(-1) observed in natural waters, suggesting that H202 may act as a limiting factor for cyanobacterial growth.

  20. Acute toxicity and effects of 1-alkyl-3-methylimidazolium bromide ionic liquids on green algae.

    PubMed

    Ma, Jian-Min; Cai, Lin-Lin; Zhang, Bang-Jun; Hu, Ling-Wei; Li, Xiao-Yu; Wang, Jian-Ji

    2010-09-01

    In the present study, the acute toxicity of 1-Alkyl-3-methylimidazolium bromide ([Cnmim]Br) on the green algal Scenedesmus obliquus and Chlorella ellipsoidea was determined. The length of alkyl side chain of these imidazolium ionic liquids were C4, C6, C8, C10 and C12. The primary production of S. obliquus was also assessed after they were exposed to 0.01, 0.05, 0.10, 0.50 and 1.00 mg/L of [C10mim]Br for 96 h. The results showed that the acute toxicity of these ionic liquids was positively correlated with the alkyl chain length. Meanwhile, the concentration of the ionic liquid strongly influenced the primary production of algae. These results indicate that [Cnmim]Br with longer alkyl length have toxic effects on the green algae, and the risk to aquatic ecosystems by ionic liquid's leaking into the water body must be evaluated in the future. Copyright (c) 2009 Elsevier Inc. All rights reserved.

  1. Biochemical Basis of Obligate Autotrophy in Blue-Green Algae and Thiobacilli

    PubMed Central

    Smith, Arnold J.; London, Jack; Stanier, Roger Y.

    1967-01-01

    Differential rates of incorporation of sugars, organic acids, and amino acids during autotrophic growth of several blue-green algae and thiobacilli have been determined. In obligate autotrophs (both blue-green algae and thiobacilli), exogenously furnished organic compounds make a very small contribution to cellular carbon; acetate, the most readily incorporated compound of those studied, contributes about 10% of newly synthesized cellular carbon. In Thiobacillus intermedius, a facultative chemoautotroph, acetate contributes over 40% of newly synthesized cellular carbon, and succinate and glutamate almost 90%. In the obligate autotrophs, carbon from pyruvate, acetate, and glutamate is incorporated into restricted groups of cellular amino acids, and the patterns of incorporation in all five organisms are essentially identical. These patterns suggest that the tricarboxylic acid cycle is blocked at the level of α-ketoglutarate oxidation. Enzymatic analyses confirmed the absence of α-ketoglutarate dehydrogenase in the obligate autotrophs, and also revealed that they lacked reduced nicotinamide adenine dinucleotide oxidase, and had extremely low levels of malic and succinic dehydrogenase. These enzymatic deficiencies were not manifested by the two facultative chemoautotrophs examined. On the basis of the data obtained, an interpretation of obligate autotrophy in both physiological and evolutionary terms has been developed. PMID:4963789

  2. Precambrian palaeontology in the light of molecular phylogeny - an example: the radiation of the green algae

    NASA Astrophysics Data System (ADS)

    Teyssèdre, B.

    2007-09-01

    The problem of the antiquity of the radiation of the green algae (phylum Viridiplantae) has been hotly debated and is still controversial today. A method combining Precambrian paleontology and molecular phylogeny is applied to shed light on this topic. As a critical method, molecular phylogeny is essential for avoiding taxonomic mistakes. As a heuristic method, it helps us to discern to what extent the presence of such and such clade is likely at such and such time, and it may even suggest the attribution of some fossil to a clade whose taxonomic position will be distinctly defined even though it has no previously known representative. Some well characterized Precambrian fossils of green algae are Palaeastrum and Proterocladus at Svanbergfjellet (ca. 750 Ma), Tasmanites and Pterospermella at Thule (ca. 1200 Ma), Spiromorpha at Ruyang (ca. 1200 Ma) and Leiosphaeridia crassa at Roper (ca. 1450 Ma). The position of these fossils in the taxonomy and the phylogeny of the Viriplantae is discussed. The conclusions are that the Chlorophyceae and the Ulvophyceae were separated long before 750 Ma, that the Chlorophyta and the Streptophyta were separated long before 1200 Ma and that the last common ancestor of the Viridiplantae and the Rhodophyta was possibly two billion years old.

  3. AGROBACTERIUM-MEDIATED TRANSFORMATION IN THE GREEN ALGA HAEMATOCOCCUS PLUVIALIS (CHLOROPHYCEAE, VOLVOCALES)(1).

    PubMed

    Kathiresan, S; Chandrashekar, A; Ravishankar, G A; Sarada, R

    2009-06-01

    The first successful Agrobacterium-mediated transformation of the green alga Haematococcus pluvialis Flot. using the binary vectors hosting the genes coding for GUS (β-glucuronidase), GFP (green fluorescent protein), and hpt (hygromycin phosphotransferase) is reported here. Colonies resistant to hygromycin at 10 mg · L(-1) expressed β-glucuronidase. The greenish yellow fluorescence of GFP was observed when the hygromycin-resistant cells were viewed with a fluorescent microscope. PCR was used to successfully amplify fragments of the hpt (407 bp) and GUS (515 bp) genes from transformed cells, while Southern blots indicated the integration of the hygromycin gene into the genome of H. pluvialis. SEM indicated that the cell wall of H. pluvialis was altered on infection with Agrobacterium. The transformation achieved here by Agrobacterium does not need treatment with acetosyringone or the wounding of cells. A robust transformation method for this alga would pave the way for manipulation of many important pathways relevant to the food, pharmaceutical, and nutraceutical industries.

  4. A new microscopic method to analyse desiccation-induced volume changes in aeroterrestrial green algae.

    PubMed

    Lajos, K; Mayr, S; Buchner, O; Blaas, K; Holzinger, A

    2016-08-01

    Aeroterrestrial green algae are exposed to desiccation in their natural habitat, but their actual volume changes have not been investigated. Here, we measure the relative volume reduction (RVRED ) in Klebsormidium crenulatum and Zygnema sp. under different preset relative air humidities (RH). A new chamber allows monitoring RH during light microscopic observation of the desiccation process. The RHs were set in the range of ∼4 % to ∼95% in 10 steps. RVRED caused by the desiccation process was determined after full acclimation to the respective RHs. In K. crenulatum, RVRED (mean ± SE) was 46.4 ± 1.9%, in Zygnema sp. RVRED was only 34.3 ± 2.4% at the highest RH (∼95%) tested. This indicates a more pronounced water loss at higher RHs in K. crenulatum versus Zygnema sp. By contrast, at the lowest RH (∼4%) tested, RVRED ranged from 75.9 ± 2.7% in K. crenulatum to 83.9 ± 2.2% in Zygnema sp. The final volume reduction is therefore more drastic in Zygnema sp. These data contribute to our understanding of the desiccation process in streptophytic green algae, which are considered the closest ancestors of land plants.

  5. Quantitative structure-activity relationships for green algae growth inhibition by polymer particles.

    PubMed

    Nolte, Tom M; Peijnenburg, Willie J G M; Hendriks, A Jan; van de Meent, Dik

    2017-03-19

    After use and disposal of chemical products, many types of polymer particles end up in the aquatic environment with potential toxic effects to primary producers like green algae. In this study, we have developed Quantitative Structure-Activity Relationships (QSARs) for a set of highly structural diverse polymers which are capable to estimate green algae growth inhibition (EC50). The model (N = 43, R(2) = 0.73, RMSE = 0.28) is a regression-based decision tree using one structural descriptor for each of three polymer classes separated based on charge. The QSAR is applicable to linear homo polymers as well as copolymers and does not require information on the size of the polymer particle or underlying core material. Highly branched polymers, non-nitrogen cationic polymers and polymeric surfactants are not included in the model and thus cannot be evaluated. The model works best for cationic and non-ionic polymers for which cellular adsorption, disruption of the cell wall and photosynthesis inhibition were the mechanisms of action. For anionic polymers, specific properties of the polymer and test characteristics need to be known for detailed assessment. The data and QSAR results for anionic polymers, when combined with molecular dynamics simulations indicated that nutrient depletion is likely the dominant mode of toxicity. Nutrient depletion in turn, is determined by the non-linear interplay between polymer charge density and backbone flexibility.

  6. A novel ether-linked phytol-containing digalactosylglycerolipid in the marine green alga, Ulva pertusa.

    PubMed

    Ishibashi, Yohei; Nagamatsu, Yusuke; Miyamoto, Tomofumi; Matsunaga, Naoyuki; Okino, Nozomu; Yamaguchi, Kuniko; Ito, Makoto

    2014-10-03

    Galactosylglycerolipids (GGLs) and chlorophyll are characteristic components of chloroplast in photosynthetic organisms. Although chlorophyll is anchored to the thylakoid membrane by phytol (tetramethylhexadecenol), this isoprenoid alcohol has never been found as a constituent of GGLs. We here described a novel GGL, in which phytol was linked to the glycerol backbone via an ether linkage. This unique GGL was identified as an Alkaline-resistant and Endogalactosylceramidase (EGALC)-sensitive GlycoLipid (AEGL) in the marine green alga, Ulva pertusa. EGALC is an enzyme that is specific to the R-Galα/β1-6Galβ1-structure of galactolipids. The structure of U. pertusa AEGL was determined following its purification to 1-O-phytyl-3-O-Galα1-6Galβ1-sn-glycerol by mass spectrometric and nuclear magnetic resonance analyses. AEGLs were ubiquitously distributed in not only green, but also red and brown marine algae; however, they were rarely detected in terrestrial plants, eukaryotic phytoplankton, or cyanobacteria. Copyright © 2014 Elsevier Inc. All rights reserved.

  7. In vitro cytotoxicity assessment of ulvan, a polysaccharide extracted from green algae.

    PubMed

    Alves, Anabela; Sousa, Rui A; Reis, Rui L

    2013-08-01

    Sustainable exploitation and valorization of natural marine resources represents a highly interesting platform for the development of novel biomaterials, with both economic and environmental benefits. In this context, toxicity data is regarded as a crucial and fundamental knowledge prior to any advances in the application development of natural derived polymers. In the present work, cytotoxicity of ulvan extracted from green algae Ulva lactuca was assessed by means of standard in vitro cytotoxicity assays. Fibroblast-like cells were incubated in the presence of this green algae's polysaccharide, and cell viability was assayed through 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium test. In addition, double stranded DNA and total protein were quantified in order to assess cell number. In order to establish ulvan's non-cytotoxic behaviour, the effect of this polysaccharide on cellular metabolic activity and cell number was directly compared to hyaluronic acid (HA), used as a non-cytotoxic control material. In this study, ulvan demonstrated promising results in terms of cytotoxicity, comparable to the currently used HA, which suggests that ulvan can be considered as non-toxic in the range of concentrations studied.

  8. Structural characterization and anticoagulant activity of a sulfated polysaccharide from the green alga Codium divaricatum.

    PubMed

    Li, Na; Mao, Wenjun; Yan, Mengxia; Liu, Xue; Xia, Zheng; Wang, Shuyao; Xiao, Bo; Chen, Chenglong; Zhang, Lifang; Cao, Sujian

    2015-05-05

    A sulfated polysaccharide, designated CP2-1, was isolated from the green alga Codium divaricatum by water extraction and purified by anion-exchange and size-exclusion chromatography. CP2-1 is a galactan which is highly sulfated and substituted with pyruvic acid ketals. On the basis of chemical and spectroscopic analyses, the backbone of CP2-1 was mainly composed of (1→3)-β-d-galactopyranose residues, branched by single (1→)-β-d-galactopyranose units attached to the main chain at C-4 positions. The degree of branching was estimated to be about 12.2%. Sulfate groups were at C-4 of (1→3)-β-d-galactopyranose and C-6 of non-reducing terminal galactose residues. In addition, the ketals of pyruvic acid were found at 3,4- of non-reducing terminal galactose residues forming a five-membered ring. CP2-1 possessed a high anticoagulant activity as assessed by the activated partial thromboplastin time and thrombin time assays. The investigation demonstrated that CP2-1 was an anticoagulant-active sulfated polysaccharide distinguishing from other sulfated polysaccharides from marine green algae.

  9. Physiological and biochemical responses of the freshwater green algae Closterium ehrenbergii to the common disinfectant chlorine.

    PubMed

    Sathasivam, Ramaraj; Ebenezer, Vinitha; Guo, Ruoyu; Ki, Jang-Seu

    2016-11-01

    Chlorine (Cl2) is widely used as a disinfectant in water treatment plants and for cleaning swimming pools; it is finally discharged into aquatic environments, possibly causing damage to the non-target organisms in the receiving water bodies. Present study evaluated the effects of the biocide Cl2 to the green alga Closterium ehrenbergii (C. ehrenbergii). Growth rate, chlorophyll a levels, carotenoids, chlorophyll autofluorescence, and antioxidant enzymes were monitored up to 72-h after Cl2 exposure. C. ehrenbergii showed dose-dependent decrease in growth rate and cell division after exposure to Cl2. By using cell counts, the median effective concentration (EC50)-72-h was calculated to be 0.071mgL(-1). Cl2 significantly decreased the pigment levels and chlorophyll autofluorescence intensity, indicating that the photosystem was damaged in C. ehrenbergii. In addition, it increased the production of reactive oxygen species (ROS) in the cells. This stressor significantly increased the activities of antioxidant enzymes, including superoxide dismutase (SOD), catalase, and glutathione, and affected the physiology of the cells. These results indicate that Cl2 induces oxidative stress in the cellular metabolic process and leads to physiological and biochemical damages in the green algae. Cl2 discharged in industrial effluents and from water treatment plants may cause harmful effects to the C. ehrenbergii a common freshwater microalgae and other non-target organisms.

  10. A new microscopic method to analyse desiccation‐induced volume changes in aeroterrestrial green algae

    PubMed Central

    LAJOS, K.; MAYR, S.; BUCHNER, O.; BLAAS, K.

    2016-01-01

    Summary Aeroterrestrial green algae are exposed to desiccation in their natural habitat, but their actual volume changes have not been investigated. Here, we measure the relative volume reduction (RVRED) in Klebsormidium crenulatum and Zygnema sp. under different preset relative air humidities (RH). A new chamber allows monitoring RH during light microscopic observation of the desiccation process. The RHs were set in the range of ∼4 % to ∼95% in 10 steps. RVRED caused by the desiccation process was determined after full acclimation to the respective RHs. In K. crenulatum, RVRED (mean ± SE) was 46.4 ± 1.9%, in Zygnema sp. RVRED was only 34.3 ± 2.4% at the highest RH (∼95%) tested. This indicates a more pronounced water loss at higher RHs in K. crenulatum versus Zygnema sp. By contrast, at the lowest RH (∼4%) tested, RVRED ranged from 75.9 ± 2.7% in K. crenulatum to 83.9 ± 2.2% in Zygnema sp. The final volume reduction is therefore more drastic in Zygnema sp. These data contribute to our understanding of the desiccation process in streptophytic green algae, which are considered the closest ancestors of land plants. PMID:27075881

  11. Photosystem II stress tolerance in the unicellular green alga Chlamydomonas Reinhardtii under space conditions

    NASA Astrophysics Data System (ADS)

    Bertalan, Ivo; Esposito, Dania; Torzillo, Giuseppe; Faraloni, Cecilia; Johanningmeier, Udo; Giardi, Maria Teresa

    2007-09-01

    Photosynthesis was established on the earth 3.5 billion years ago. Due to the absence of the ozone layer in the early atmosphere it was most likely adapted to the presence of ionizing radiation continuously emitted by solar and stellar flares. That complex radiation spectrum comprises protons, alpha particles, heavy charged particle-HZE, electrons, X-ray and neutrons. Such spectrum has a significant impact on biological systems which capture light energy for e.g. photosynthesis. Oxygenic photosynthesis of plants, algae and cyanobacteria initiates at the level of photosystem II (PSII), a multisubunit protein complex embedded in the thylakoid membrane inside chloroplasts. PSII uses sunlight to power the unique photo-induced oxidation of water to atmospheric oxygen which is indispensable for most life forms. It is an especially sensitive component if exposed to space radiation and thus an important target for research aimed at improving bioregenerative life-support systems. The unicellular green algae Chlamydomonas reinhardtii is a long standing model organism for photosynthesis research. It was exposed to ionizing radiation in the ESA facility Biopan located in the Foton capsule brought to space by the Russian Soyuzfor 15 days. The algae were tested in space under shielded conditions in the past, but they were never exposed to direct ionizing radiation such as in Biopan. Conditions for survival were identified. It was observed that the effect of space stress on the survival of the algae varied depending on the light conditions to which they were exposed during the flight. In some cases the flight experience caused a stimulation of the photosystem II oxygen evolution of the cells.

  12. Iron colloids reduce the bioavailability of phosphorus to the green alga Raphidocelis subcapitata.

    PubMed

    Baken, Stijn; Nawara, Sophie; Van Moorleghem, Christoff; Smolders, Erik

    2014-08-01

    Phosphorus (P) is a limiting nutrient in many aquatic systems. The bioavailability of P in natural waters strongly depends on its speciation. In this study, structural properties of iron colloids were determined and related to their effect on P sorption and P bioavailability. The freshwater green alga Raphidocelis subcapitata was exposed to media spiked with radiolabelled (33)PO4, and the uptake of (33)P was monitored for 1 h. The media contained various concentrations of synthetic iron colloids with a size between 10 kDa and 0.45 μm. The iron colloids were stabilised by natural organic matter. EXAFS spectroscopy showed that these colloids predominantly consisted of ferrihydrite with small amounts of organically complexed Fe. In colloid-free treatments, the P uptake flux by the algae obeyed Michaelis-Menten kinetics. In the presence of iron colloids at 9 or 90 μM Fe, corresponding to molar P:Fe ratios between 0.02 and 0.17, the truly dissolved P (<10 kDa) was between 4 and 60% of the total dissolved P (<0.45 μm). These colloids reduced the P uptake flux by R. subcapitata compared to colloid-free treatments at the same total dissolved P concentration. However, the P uptake flux from colloid containing solutions equalled that from colloid-free ones when expressed as truly dissolved P. This demonstrates that colloidal P did not contribute to the P uptake flux. It is concluded that, on the short term, phosphate adsorbed to ferrihydrite colloids is not available to the green alga R. subcapitata. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Cell death in the unicellular green alga Micrasterias upon H2O2 induction

    PubMed Central

    Darehshouri, Anza; Affenzeller, Matthias; Lütz-Meindl, Ursula

    2010-01-01

    In the present study we investigate whether the unicellular green alga Micrasterias denticulata is capable of executing programmed cell death (PCD) upon experimental induction and by which morphological, molecular and physiological hallmarks it is characterized. This is particularly interesting as unicellular fresh water green algae growing in shallow bog ponds are exposed to extreme environmental conditions and the capability to perform PCD may provide an important strategy to guarantee survival of the population. The theoretically “immortal” alga Micrasterias is an ideal object for such investigations as it has served as a cell biological model system since many years and details on its growth properties, physiology and ultrastructure throughout the cell cycle are well known. Treatment with low concentrations of H2O2 known to induce PCD in other organisms resulted in severe ultrastructural changes of organelles as observed in TEM. These include deformation and partly disintegration of mitochondria, abnormal dilatation of cisternal rims of dictyosomes, the occurrence of multivesicular bodies, an increase in the number of ER compartments and slight condensation of chromatin. Additionally, a statistically significant increase in caspase-3-like activity could be detected which was abrogated by a caspase-3 inhibitor. Photosynthetic activity measured by fast chlorophyll fluorescence decreased as a consequence of H2O2 exposure whereas pigment composition, except of a reduction in carotenoids, was the same as in untreated controls. TUNEL positive staining and ladder-like degradation of DNA, both frequently regarded as PCD hallmark in higher plants could only be detected in dead Micrasterias cells. PMID:18950431

  14. Estrogenic activity in extracts and exudates of cyanobacteria and green algae.

    PubMed

    Sychrová, E; Štěpánková, T; Nováková, K; Bláha, L; Giesy, J P; Hilscherová, K

    2012-02-01

    Here is presented some of the first information on interactions of compounds produced by cyanobacteria and green algae with estrogen receptor signaling. Estrogenic potency of aqueous extracts and exudates (culture spent media with extracellular products) of seven species of cyanobacteria (10 different laboratory strains) and two algal species were assessed by use of in vitro trans-activation assays. Compounds produced by cyanobacteria and algae, and in particular those excreted from the cells, were estrogenic. Most exudates were estrogenic with potencies expressed at 50% of the maximum response under control of the estrogen receptor ranging from 0.2 to 7.2 ng 17β-estradiol (E(2)) equivalents (EEQ)/L. The greatest estrogenic potency was observed for exudates of Microcystis aerigunosa, a common species that forms water blooms. Aqueous extracts of both green algae, but only one species of cyanobacteria (Aphanizomenon gracile) elicited significant estrogenicity with EEQ ranging from 15 to 280 ng 17β-estradiol (E(2))/g dry weight. Scenedesmus quadricauda exudates and extracts of Aphanizomenon flos-aquae were antagonistic to the ER when coexposed to E(2). The EEQ potency was not correlated with concentrations of cyanotoxins, such as microcystin and cylindrospermopsin, which suggests that the EEQ was comprised of other compounds. The study demonstrates some differences between the estrogenic potency of aqueous extracts prepared from the same species, but of different origin, while the effects of exudates were comparable within species. The observed estrogenic potencies are important namely in relation to the possible mass expansion of cyanobacteria and release of the active compounds into surrounding water.

  15. Larvicidal algae.

    PubMed

    Marten, Gerald G

    2007-01-01

    Although most algae are nutritious food for mosquito larvae, some species kill the larvae when ingested in large quantities. Cyanobacteria (blue-green algae) that kill larvae do so by virtue of toxicity. While blue-green algae toxins may offer possibilities for delivery as larvicides, the toxicity of live blue-green algae does not seem consistent enough for live algae to be useful for mosquito control. Certain species of green algae in the order Chlorococcales kill larvae primarily because they are indigestible. Where these algae are abundant in nature, larvae consume them to the exclusion of other food and then starve. Under the right circumstances, it is possible to introduce indigestible algae into a breeding habitat so they become abundant enough to render it unsuitable for mosquito production. The algae can persist for years, even if the habitat dries periodically. The main limitation of indigestible algae lies in the fact that, under certain conditions, they may not replace all the nutritious algae in the habitat. More research on techniques to ensure complete replacement will be necessary before indigestible algae can go into operational use for mosquito control.

  16. Antioxidant system responses in two co-occurring green-tide algae under stress conditions

    NASA Astrophysics Data System (ADS)

    Wang, Ying; Zhao, Xinyu; Tang, Xuexi

    2016-01-01

    Green tides have occurred every year from 2007 to 2014 in the Yellow Sea. Ulva prolifera (Müller) J. Agardh has been identified as the bloom-forming alga, co-occurring with U. intestinalis. We observed distinct strategies for both algal species during green tides. U. prolifera exhibited a high abundance initially and then decreased dramatically, while U. intestinalis persisted throughout. The antioxidant system responses of these two macroalgae were compared in the late phase of a green tide (in-situ) and after laboratory acclimation. Lipid peroxidation and antioxidant system responses differed significantly between the two. Malondialdehyde and hydrogen peroxide contents increased significantly in-situ in U. prolifera, but not in U. intestinalis. In U. prolifera, we observed a significant decrease in total antioxidant ability (T-AOC), antioxidant enzymes (SOD and Apx), and non-enzyme antioxidants (GSH and AsA) in-situ. U. intestinalis showed the same pattern of T-AOC and SOD, but its Gpx, Apx, and GSH responses did not differ significantly. The results suggest that U. prolifera was more susceptible than U. intestinalis to the harsh environmental changes during the late phase of a Yellow Sea green tide. The boom and bust strategy exhibited by U. prolifera and the persistence of U. intestinalis can be explained by differences in enzyme activity and antioxidant systems.

  17. Rapid mass movement of chloroplasts during segment formation of the calcifying siphonalean green alga, Halimeda macroloba.

    PubMed

    Larkum, Anthony W D; Salih, Anya; Kühl, Michael

    2011-01-01

    The calcifying siphonalean green alga, Halimeda macroloba is abundant on coral reefs and is important in the production of calcium carbonate sediments. The process by which new green segments are formed over-night is revealed here for the first time. Growth of new segments was visualised by epifluorescence and confocal microscopy and by pulse amplitude modulation (PAM) fluorimetry. Apical colourless proto-segments were initiated on day 1, and formed a loose network of non-calcified, non-septate filaments, containing no chloroplasts. Rapid greening was initiated at dusk by i) the mass movement of chloroplasts into these filaments from the parent segment and ii) the growth of new filaments containing chloroplasts. Greening was usually complete in 3-5 h and certainly before dawn on day 2 when the first signs of calcification were apparent. Mass chloroplast movement took place at a rate of ∼0.65 µm/s. Photosynthetic yield and rate remained low for a period of 1 to several hours, indicating that the chloroplasts were made de novo. Use of the inhibitors colchicine and cytochalasin d indicated that the movement process is dependent on both microtubules and microfilaments. This unusual process involves the mass movement of chloroplasts at a high rate into new segments during the night and rapid calcification on the following day and may be an adaptation to minimise the impact of herbivorous activity.

  18. Pectin Metabolism and Assembly in the Cell Wall of the Charophyte Green Alga Penium margaritaceum1[W][OPEN

    PubMed Central

    Domozych, David S.; Sørensen, Iben; Popper, Zoë A.; Ochs, Julie; Andreas, Amanda; Fangel, Jonatan U.; Pielach, Anna; Sacks, Carly; Brechka, Hannah; Ruisi-Besares, Pia; Willats, William G.T.; Rose, Jocelyn K.C.

    2014-01-01

    The pectin polymer homogalacturonan (HG) is a major component of land plant cell walls and is especially abundant in the middle lamella. Current models suggest that HG is deposited into the wall as a highly methylesterified polymer, demethylesterified by pectin methylesterase enzymes and cross-linked by calcium ions to form a gel. However, this idea is based largely on indirect evidence and in vitro studies. We took advantage of the wall architecture of the unicellular alga Penium margaritaceum, which forms an elaborate calcium cross-linked HG-rich lattice on its cell surface, to test this model and other aspects of pectin dynamics. Studies of live cells and microscopic imaging of wall domains confirmed that the degree of methylesterification and sufficient levels of calcium are critical for lattice formation in vivo. Pectinase treatments of live cells and immunological studies suggested the presence of another class of pectin polymer, rhamnogalacturonan I, and indicated its colocalization and structural association with HG. Carbohydrate microarray analysis of the walls of P. margaritaceum, Physcomitrella patens, and Arabidopsis (Arabidopsis thaliana) further suggested the conservation of pectin organization and interpolymer associations in the walls of green plants. The individual constituent HG polymers also have a similar size and branched structure to those of embryophytes. The HG-rich lattice of P. margaritaceum, a member of the charophyte green algae, the immediate ancestors of land plants, was shown to be important for cell adhesion. Therefore, the calcium-HG gel at the cell surface may represent an early evolutionary innovation that paved the way for an adhesive middle lamella in multicellular land plants. PMID:24652345

  19. Rickettsial endosymbiont in the "early-diverging" streptophyte green alga Mesostigma viride.

    PubMed

    Yang, Ashley; Narechania, Apurva; Kim, Eunsoo

    2016-04-01

    A bacterial endosymbiont was unexpectedly found in the "axenic" culture strain of the streptophyte green alga Mesostigma viride (NIES-995). Phylogenetic analyses based on 16S rRNA gene sequences showed that the symbiont belongs to the order Rickettsiales, specifically to the recently designated clade "Candidatus Megaira," which is closely related to the well-known Rickettsia clade. Rickettsiales bacteria of the "Ca. Megaira" clade are found in a taxonomically diverse array of eukaryotic hosts, including chlorophycean green algae, several ciliate species, and invertebrates such as Hydra. Transmission electron microscopy, fluorescence in situ hybridi-zation, and SYBR Green I staining experiments revealed that the endosymbiont of M. viride NIES-995 is rod shaped, typically occurs in clusters, and is surrounded by a halo-like structure, presumably formed by secretory substances from the bacterium. Two additional M. viride strains (NIES-296 and NIES-475), but not SAG50-1, were found to house the rickettsial endosymbiont. Analyses of strain NIES-995 transcriptome data indicated the presence of at least 91 transcriptionally active genes of symbiont origins. These include genes for surface proteins (e.g., rOmpB) that are known to play key roles in bacterial attachment onto host eukaryotes in related Rickettsia species. The assembled M. viride transcriptome includes transcripts that code for a suite of predicted algal-derived proteins, such as Ku70, WASH, SCAR, and CDC42, which may be important in the formation of the algal-rickettsial association.

  20. Chromosome-level genome assembly and transcriptome of the green alga Chromochloris zofingiensis illuminates astaxanthin production

    DOE PAGES

    Roth, Melissa S.; Cokus, Shawn J.; Gallaher, Sean D.; ...

    2017-05-08

    Microalgae have potential to help meet energy and food demands without exacerbating environmental problems. There is interest in the unicellular green alga Chromochloris zofingiensis, because it produces lipids for biofuels and a highly valuable carotenoid nutraceutical, astaxanthin. Here, to advance understanding of its biology and facilitate commercial development, we present a C. zofingiensis chromosome-level nuclear genome, organelle genomes, and transcriptome from diverse growth conditions. The assembly, derived from a combination of short- and long-read sequencing in conjunction with optical mapping, revealed a compact genome of ~58 Mbp distributed over 19 chromosomes containing 15,274 predicted protein-coding genes. The genome has uniformmore » gene density over chromosomes, low repetitive sequence content (~6%), and a high fraction of protein-coding sequence (~39%) with relatively long coding exons and few coding introns. Functional annotation of gene models identified orthologous families for the majority (~73%) of genes. Synteny analysis uncovered localized but scrambled blocks of genes in putative orthologous relationships with other green algae. Two genes encoding beta-ketolase (BKT), the key enzyme synthesizing astaxanthin, were found in the genome, and both were up-regulated by high light. Isolation and molecular analysis of astaxanthin-deficient mutants showed that BKT1 is required for the production of astaxanthin. Moreover, the transcriptome under high light exposure revealed candidate genes that could be involved in critical yet missing steps of astaxanthin biosynthesis, including ABC transporters, cytochrome P450 enzymes, and an acyltransferase. Finally, the high-quality genome and transcriptome provide insight into the green algal lineage and carotenoid production.« less

  1. Chromosome-level genome assembly and transcriptome of the green alga Chromochloris zofingiensis illuminates astaxanthin production

    PubMed Central

    Roth, Melissa S.; Cokus, Shawn J.; Gallaher, Sean D.; Walter, Andreas; Lopez, David; Erickson, Erika; Endelman, Benjamin; Westcott, Daniel; Larabell, Carolyn A.; Merchant, Sabeeha S.; Pellegrini, Matteo

    2017-01-01

    Microalgae have potential to help meet energy and food demands without exacerbating environmental problems. There is interest in the unicellular green alga Chromochloris zofingiensis, because it produces lipids for biofuels and a highly valuable carotenoid nutraceutical, astaxanthin. To advance understanding of its biology and facilitate commercial development, we present a C. zofingiensis chromosome-level nuclear genome, organelle genomes, and transcriptome from diverse growth conditions. The assembly, derived from a combination of short- and long-read sequencing in conjunction with optical mapping, revealed a compact genome of ∼58 Mbp distributed over 19 chromosomes containing 15,274 predicted protein-coding genes. The genome has uniform gene density over chromosomes, low repetitive sequence content (∼6%), and a high fraction of protein-coding sequence (∼39%) with relatively long coding exons and few coding introns. Functional annotation of gene models identified orthologous families for the majority (∼73%) of genes. Synteny analysis uncovered localized but scrambled blocks of genes in putative orthologous relationships with other green algae. Two genes encoding beta-ketolase (BKT), the key enzyme synthesizing astaxanthin, were found in the genome, and both were up-regulated by high light. Isolation and molecular analysis of astaxanthin-deficient mutants showed that BKT1 is required for the production of astaxanthin. Moreover, the transcriptome under high light exposure revealed candidate genes that could be involved in critical yet missing steps of astaxanthin biosynthesis, including ABC transporters, cytochrome P450 enzymes, and an acyltransferase. The high-quality genome and transcriptome provide insight into the green algal lineage and carotenoid production. PMID:28484037

  2. De-eutrophication of effluent wastewater from fish aquaculture by using marine green alga Ulva pertusa

    NASA Astrophysics Data System (ADS)

    Liu, Jianguo; Wang, Zengfu; Lin, Wei

    2010-03-01

    The de-eutrophication abilities and characteristics of Ulva pertusa, a marine green alga, were investigated in Qingdao Yihai Hatchery Center from spring to summer in 2005 by analyzing the dynamic changes in NH{4/+}, NO{3/-}, NO{2/-} as well as the total dissolved inorganic nitrogen (DIN). The results show that the effluent wastewater produced by fish aquaculture had typical eutrophication levels with an average of 34.3 μmol L-1 DIN. This level far exceeded the level IV quality of the national seawater standard and could easily lead to phytoplankton blooms in nature if discarded with no treatment. The de-eutrophication abilities of U. pertusa varied greatly and depended mainly on the original eutrophic level the U. pertusa material was derived from. U. pertusa used to living in low DIN conditions had poor DIN removal abilities, while materials cultured in DIN-enriched seawater showed strong de-eutrophication abilities. In other words, the de-eutrophication ability of U. pertusa was evidently induced by high DIN levels. The de-eutrophication capacity of U. pertusa seemed to also be light dependent, because it was weaker in darkness than under illumination. However, no further improvement in the de-eutrophication capacity of U. pertusa was observed once the light intensity exceeded 300 μmol M2 S-1. Results of semi-continuous wastewater replacement experiments showed that U. pertusa permanently absorbed nutrients from eutrophicated wastewater at a mean rate of 299 mg/kg fresh weight per day (126 mg/kg DIN during the night, 173 mg/kg in daytime). Based on the above results, engineered de-eutrophication of wastewater by using a U. pertusa filter system seems feasible. The algal quantity required to purify all the eutrophicated outflow wastewater from the Qingdao Yihai Hatchery Center into oligotrophic level I clean seawater was also estimated using the daily discharged wastewater, the average DIN concentration released and the de-eutrophication capacity of U. pertusa.

  3. Inhibition of enterovirus 71-induced apoptosis by allophycocyanin isolated from a blue-green alga Spirulina platensis.

    PubMed

    Shih, Shin-Ru; Tsai, Kun-Nan; Li, Yi-Shuane; Chueh, Chuang-Chun; Chan, Err-Cheng

    2003-05-01

    Enterovirus 71 infection causes significant morbidity and mortality in children, yet there is no effective treatment. In this study, a protein-bound pigment, allophycocyanin purified from blue-green algae is first reported to exhibit anti-enterovirus 71 activity. Allophycocyanin neutralized the enterovirus 71-induced cytopathic effect in both human rhabdomyosarcoma cells and African green monkey kidney cells. The 50% inhibitory concentration of allophycocyanin for neutralizing the enterovirus 71-induced cytopathic effect was approximately 0.045 +/- 0.012 microM in green monkey kidney cells. The cytotoxic concentrations of allophycocyanin for rhabdomyosarcoma cells and African green monkey kidney cells were 1.653 +/- 0.003 microM and 1.521 +/- 0.012 microM, respectively. A plaque reduction assay showed that the concentrations of allophycocyanin for reducing plaque formation by 50% were approximately 0.056 +/- 0.007 microM and 0.101 +/- 0.032 microM, when allophycocyanin were added at the state of viral adsorption and post-adsorption, respectively. Antiviral activity was more efficient in cultures treated with allophycocyanin before viral infection compared with that in the cultures treated after infection. Allophycocyanin was also able to delay viral RNA synthesis in the infected cells and to abate the apoptotic process in enterovirus 71-infected rhabdomyosarcoma cells with evidence of characteristic DNA fragmentation, decreasing membrane damage and declining cell sub-G1 phase. It is concluded that allophycocyanin possesses antiviral activity and has a potential for development as an anti-enterovirus 71 agent.

  4. Growth and Metabolism of the Green Alga, Chlorella Pyrenoidosa, in Simulated Microgravity

    NASA Technical Reports Server (NTRS)

    Mills, W. Ronald

    2003-01-01

    The effect of microgravity on living organisms during space flight has been a topic of interest for some time, and a substantial body of knowledge on the subject has accumulated. Despite this, comparatively little information is available regarding the influence of microgravity on algae, even though it has been suggested for long duration flight or occupancy in space that plant growth systems, including both higher plants and algae, are likely to be necessary for bioregenerative life support systems. High-Aspect-Ratio Rotating-Wall Vessel or HARV bioreactors developed at Johnson Space Center provide a laboratory-based approach to investigating the effects of microgravity on cellular reactions. In this study, the HARV bioreactor was used to examine the influence of simulated microgravity on the growth and metabolism of the green alga, Chlorella pyrenoidosa. After the first 2 days of culture, cell numbers increased more slowly in simulated microgravity than in the HARV gravity control; after 7 days, growth in simulated microgravity was just over half (58%) that of the gravity control and at 14 days it was less than half (42%). Chlorophyll and protein were also followed as indices of cell competence and function; as with growth, after 2-3 days, protein and chlorophyll levels were reduced in modeled microgravity compared to gravity controls. Photosynthesis is a sensitive biochemical index of the fitness of photosynthetic organisms; thus, CO2-dependent O2 evolution was tested as a measure of photosynthetic capacity of cells grown in simulated microgravity. When data were expressed with respect to cell number, modeled microgravity appeared to have little effect on CO2 fixation. Thus, even though the overall growth rate was lower for cells cultured in microgravity, the photosynthetic capacity of the cells appears to be unaffected. Cells grown in simulated microgravity formed loose clumps or aggregates within about 2 days of culture, with aggregation increasing over time

  5. Host-parasite relationship of the geoduck Panopea abbreviata and the green alga Coccomyxa parasitica in the Argentinean Patagonian coast.

    PubMed

    Vázquez, Nuria; Rodríguez, Francisco; Ituarte, Cristián; Klaich, Javier; Cremonte, Florencia

    2010-11-01

    The association of the geoduck Panopea abbreviata and the green alga Coccomyxa parasitica is described. The identity of the green alga was confirmed by molecular studies; the alga was found within the hemocytes that infiltrate the connective tissue of the geoduck siphons. Cytological characteristics of hemocytes were not altered by algal infection; very often the algae were seen enveloped by a digestive vacuole within the hemocyte cytoplasm, evidencing diverse degrees of resorption. Connective cells of siphons were rarely infected by C. parasitica. The mean prevalence of C. parasitica was higher (82%) in San Matías Gulf (42°00'S, 65°05'W) than in San José Gulf (45%) (40°32'S, 64°02'W); except for spring, when the two locations showed no differences in prevalences (80%). Independently of location, season and host size, infected geoducks showed lower condition index values than uninfected ones. Regarding other bivalve species, only one specimen of the razor clam Ensis macha was found infected, and none of the oysters Ostrea puelchana and Pododesmus rudis and scallop Aequipecten tehuelchus was parasitized by the green alga.

  6. Cyanolichens can have both cyanobacteria and green algae in a common layer as major contributors to photosynthesis

    PubMed Central

    Henskens, Frieda L.; Green, T. G. Allan; Wilkins, Alistair

    2012-01-01

    Background and Aims Cyanolichens are usually stated to be bipartite (mycobiont plus cyanobacterial photobiont). Analyses revealed green algal carbohydrates in supposedly cyanobacterial lichens (in the genera Pseudocyphellaria, Sticta and Peltigera). Investigations were carried out to determine if both cyanobacteria and green algae were present in these lichens and, if so, what were their roles. Methods The types of photobiont present were determined by light and fluorescence microscopy. Small carbohydrates were analysed to detect the presence of green algal metabolites. Thalli were treated with selected strengths of Zn2+ solutions that stop cyanobacterial but not green algal photosynthesis. CO2 exchange was measured before and after treatment to determine the contribution of each photobiont to total thallus photosynthesis. Heterocyst frequencies were determined to clarify whether the cyanobacteria were modified for increased nitrogen fixation (high heterocyst frequencies) or were normal, vegetative cells. Key Results Several cyanobacterial lichens had green algae present in the photosynthetic layer of the thallus. The presence of the green algal transfer carbohydrate (ribitol) and the incomplete inhibition of thallus photosynthesis upon treatment with Zn2+ solutions showed that both photobionts contributed to the photosynthesis of the lichen thallus. Low heterocyst frequencies showed that, despite the presence of adjacent green algae, the cyanobacteria were not altered to increase nitrogen fixation. Conclusions These cyanobacterial lichens are a tripartite lichen symbiont combination in which the mycobiont has two primarily photosynthetic photobionts, ‘co-primary photobionts’, a cyanobacterium (dominant) and a green alga. This demonstrates high flexibility in photobiont choice by the mycobiont in the Peltigerales. Overall thallus appearance does not change whether one or two photobionts are present in the cyanobacterial thallus. This suggests that, if there is

  7. Cyanolichens can have both cyanobacteria and green algae in a common layer as major contributors to photosynthesis.

    PubMed

    Henskens, Frieda L; Green, T G Allan; Wilkins, Alistair

    2012-08-01

    Cyanolichens are usually stated to be bipartite (mycobiont plus cyanobacterial photobiont). Analyses revealed green algal carbohydrates in supposedly cyanobacterial lichens (in the genera Pseudocyphellaria, Sticta and Peltigera). Investigations were carried out to determine if both cyanobacteria and green algae were present in these lichens and, if so, what were their roles. The types of photobiont present were determined by light and fluorescence microscopy. Small carbohydrates were analysed to detect the presence of green algal metabolites. Thalli were treated with selected strengths of Zn(2+) solutions that stop cyanobacterial but not green algal photosynthesis. CO(2) exchange was measured before and after treatment to determine the contribution of each photobiont to total thallus photosynthesis. Heterocyst frequencies were determined to clarify whether the cyanobacteria were modified for increased nitrogen fixation (high heterocyst frequencies) or were normal, vegetative cells. Several cyanobacterial lichens had green algae present in the photosynthetic layer of the thallus. The presence of the green algal transfer carbohydrate (ribitol) and the incomplete inhibition of thallus photosynthesis upon treatment with Zn(2+) solutions showed that both photobionts contributed to the photosynthesis of the lichen thallus. Low heterocyst frequencies showed that, despite the presence of adjacent green algae, the cyanobacteria were not altered to increase nitrogen fixation. These cyanobacterial lichens are a tripartite lichen symbiont combination in which the mycobiont has two primarily photosynthetic photobionts, 'co-primary photobionts', a cyanobacterium (dominant) and a green alga. This demonstrates high flexibility in photobiont choice by the mycobiont in the Peltigerales. Overall thallus appearance does not change whether one or two photobionts are present in the cyanobacterial thallus. This suggests that, if there is a photobiont effect on thallus structure, it is

  8. The mTERF protein MOC1 terminates mitochondrial DNA transcription in the unicellular green alga Chlamydomonas reinhardtii.

    PubMed

    Wobbe, Lutz; Nixon, Peter J

    2013-07-01

    The molecular function of mTERFs (mitochondrial transcription termination factors) has so far only been described for metazoan members of the protein family and in animals they control mitochondrial replication, transcription and translation. Cells of photosynthetic eukaryotes harbour chloroplasts and mitochondria, which are in an intense cross-talk that is vital for photosynthesis. Chlamydomonas reinhardtii is a unicellular green alga widely used as a model organism for photosynthesis research and green biotechnology. Among the six nuclear C. reinhardtii mTERF genes is mTERF-like gene of Chlamydomonas (MOC1), whose inactivation alters mitorespiration and interestingly also light-acclimation processes in the chloroplast that favour the enhanced production of biohydrogen. We show here from in vitro studies that MOC1 binds specifically to a sequence within the mitochondrial rRNA-coding module S3, and that a knockout of MOC1 in the mutant stm6 increases read-through transcription at this site, indicating that MOC1 acts as a transcription terminator in vivo. Whereas the level of certain antisense RNA species is higher in stm6, the amount of unprocessed mitochondrial sense transcripts is strongly reduced, demonstrating that a loss of MOC1 causes perturbed mitochondrial DNA (mtDNA) expression. Overall, we provide evidence for the existence of mitochondrial antisense RNAs in C. reinhardtii and show that mTERF-mediated transcription termination is an evolutionary-conserved mechanism occurring in phototrophic protists and metazoans.

  9. The mTERF protein MOC1 terminates mitochondrial DNA transcription in the unicellular green alga Chlamydomonas reinhardtii

    PubMed Central

    Wobbe, Lutz; Nixon, Peter J.

    2013-01-01

    The molecular function of mTERFs (mitochondrial transcription termination factors) has so far only been described for metazoan members of the protein family and in animals they control mitochondrial replication, transcription and translation. Cells of photosynthetic eukaryotes harbour chloroplasts and mitochondria, which are in an intense cross-talk that is vital for photosynthesis. Chlamydomonas reinhardtii is a unicellular green alga widely used as a model organism for photosynthesis research and green biotechnology. Among the six nuclear C. reinhardtii mTERF genes is mTERF-like gene of Chlamydomonas (MOC1), whose inactivation alters mitorespiration and interestingly also light-acclimation processes in the chloroplast that favour the enhanced production of biohydrogen. We show here from in vitro studies that MOC1 binds specifically to a sequence within the mitochondrial rRNA-coding module S3, and that a knockout of MOC1 in the mutant stm6 increases read-through transcription at this site, indicating that MOC1 acts as a transcription terminator in vivo. Whereas the level of certain antisense RNA species is higher in stm6, the amount of unprocessed mitochondrial sense transcripts is strongly reduced, demonstrating that a loss of MOC1 causes perturbed mitochondrial DNA (mtDNA) expression. Overall, we provide evidence for the existence of mitochondrial antisense RNAs in C. reinhardtii and show that mTERF-mediated transcription termination is an evolutionary-conserved mechanism occurring in phototrophic protists and metazoans. PMID:23649833

  10. Overview on Biological Activities and Molecular Characteristics of Sulfated Polysaccharides from Marine Green Algae in Recent Years

    PubMed Central

    Wang, Lingchong; Wang, Xiangyu; Wu, Hao; Liu, Rui

    2014-01-01

    Among the three main divisions of marine macroalgae (Chlorophyta, Phaeophyta and Rhodophyta), marine green algae are valuable sources of structurally diverse bioactive compounds and remain largely unexploited in nutraceutical and pharmaceutical areas. Recently, a great deal of interest has been developed to isolate novel sulfated polysaccharides (SPs) from marine green algae because of their numerous health beneficial effects. Green seaweeds are known to synthesize large quantities of SPs and are well established sources of these particularly interesting molecules such as ulvans from Ulva and Enteromorpha, sulfated rhamnans from Monostroma, sulfated arabinogalactans from Codium, sulfated galacotans from Caulerpa, and some special sulfated mannans from different species. These SPs exhibit many beneficial biological activities such as anticoagulant, antiviral, antioxidative, antitumor, immunomodulating, antihyperlipidemic and antihepatotoxic activities. Therefore, marine algae derived SPs have great potential for further development as healthy food and medical products. The present review focuses on SPs derived from marine green algae and presents an overview of the recent progress of determinations of their structural types and biological activities, especially their potential health benefits. PMID:25257786

  11. Extraction of nutraceuticals from Spirulina (blue-green alga): A bioorganic chemistry practice using thin-layer chromatography.

    PubMed

    Herrera Bravo de Laguna, Irma; Toledo Marante, Francisco J; Luna-Freire, Kristerson R; Mioso, Roberto

    2015-01-01

    Spirulina is a blue-green alga (cyanobacteria) with high nutritive value. This work provides an innovative and original approach to the consideration of a bioorganic chemistry practice, using Spirulina for the separation of phytochemicals with nutraceutical characteristics via thin-layer chromatography (TLC) plates. The aim is to bring together current research, theory, and practice, and always in accordance with pedagogical ideas.

  12. Extraction of Nutraceuticals from Spirulina (Blue-Green Alga): A Bioorganic Chemistry Practice Using Thin-layer Chromatography

    ERIC Educational Resources Information Center

    Herrera Bravo de Laguna, Irma; Toledo Marante, Francisco J.; Luna-Freire, Kristerson R.; Mioso, Roberto

    2015-01-01

    Spirulina is a blue-green alga (cyanobacteria) with high nutritive value. This work provides an innovative and original approach to the consideration of a bioorganic chemistry practice, using Spirulina for the separation of phytochemicals with nutraceutical characteristics via thin-layer chromatography (TLC) plates. The aim is to bring together…

  13. Extraction of Nutraceuticals from Spirulina (Blue-Green Alga): A Bioorganic Chemistry Practice Using Thin-layer Chromatography

    ERIC Educational Resources Information Center

    Herrera Bravo de Laguna, Irma; Toledo Marante, Francisco J.; Luna-Freire, Kristerson R.; Mioso, Roberto

    2015-01-01

    Spirulina is a blue-green alga (cyanobacteria) with high nutritive value. This work provides an innovative and original approach to the consideration of a bioorganic chemistry practice, using Spirulina for the separation of phytochemicals with nutraceutical characteristics via thin-layer chromatography (TLC) plates. The aim is to bring together…

  14. Overview on biological activities and molecular characteristics of sulfated polysaccharides from marine green algae in recent years.

    PubMed

    Wang, Lingchong; Wang, Xiangyu; Wu, Hao; Liu, Rui

    2014-09-25

    Among the three main divisions of marine macroalgae (Chlorophyta, Phaeophyta and Rhodophyta), marine green algae are valuable sources of structurally diverse bioactive compounds and remain largely unexploited in nutraceutical and pharmaceutical areas. Recently, a great deal of interest has been developed to isolate novel sulfated polysaccharides (SPs) from marine green algae because of their numerous health beneficial effects. Green seaweeds are known to synthesize large quantities of SPs and are well established sources of these particularly interesting molecules such as ulvans from Ulva and Enteromorpha, sulfated rhamnans from Monostroma, sulfated arabinogalactans from Codium, sulfated galacotans from Caulerpa, and some special sulfated mannans from different species. These SPs exhibit many beneficial biological activities such as anticoagulant, antiviral, antioxidative, antitumor, immunomodulating, antihyperlipidemic and antihepatotoxic activities. Therefore, marine algae derived SPs have great potential for further development as healthy food and medical products. The present review focuses on SPs derived from marine green algae and presents an overview of the recent progress of determinations of their structural types and biological activities, especially their potential health benefits.

  15. Ocean acidification alters the calcareous microstructure of the green macro-alga Halimeda opuntia

    NASA Astrophysics Data System (ADS)

    Wizemann, André; Meyer, Friedrich W.; Hofmann, Laurie C.; Wild, Christian; Westphal, Hildegard

    2015-09-01

    Decreases in seawater pH and carbonate saturation state ( Ω) following the continuous increase in atmospheric CO2 represent a process termed ocean acidification, which is predicted to become a main threat to marine calcifiers in the near future. Segmented, tropical, marine green macro-algae of the genus Halimeda form a calcareous skeleton that involves biotically initiated and induced calcification processes influenced by cell physiology. As Halimeda is an important habitat provider and major carbonate sediment producer in tropical shallow areas, alterations of these processes due to ocean acidification may cause changes in the skeletal microstructure that have major consequences for the alga and its environment, but related knowledge is scarce. This study used scanning electron microscopy to examine changes of the CaCO3 segment microstructure of Halimeda opuntia specimens that had been exposed to artificially elevated seawater pCO2 of ~650 µatm for 45 d. In spite of elevated seawater pCO2, the calcification of needles, located at the former utricle walls, was not reduced as frequent initiation of new needle-shaped crystals was observed. Abundance of the needles was ~22 % µm-2 higher and needle crystal dimensions ~14 % longer. However, those needles were ~42 % thinner compared with the control treatment. Moreover, lifetime cementation of the segments decreased under elevated seawater pCO2 due to a loss in micro-anhedral carbonate as indicated by significantly thinner calcified rims of central utricles (35-173 % compared with the control treatment). Decreased micro-anhedral carbonate suggests that seawater within the inter-utricular space becomes CaCO3 undersaturated ( Ω < 1) during nighttime under conditions of elevated seawater pCO2, thereby favoring CaCO3 dissolution over micro-anhedral carbonate accretion. Less-cemented segments of H. opuntia may impair the environmental success of the alga, its carbonate sediment contribution, and the temporal storage of

  16. Cultivation of green algae Chlorella sp. in different wastewaters from municipal wastewater treatment plant.

    PubMed

    Wang, Liang; Min, Min; Li, Yecong; Chen, Paul; Chen, Yifeng; Liu, Yuhuan; Wang, Yingkuan; Ruan, Roger

    2010-10-01

    The objective of this study was to evaluate the growth of green algae Chlorella sp. on wastewaters sampled from four different points of the treatment process flow of a local municipal wastewater treatment plant (MWTP) and how well the algal growth removed nitrogen, phosphorus, chemical oxygen demand (COD), and metal ions from the wastewaters. The four wastewaters were wastewater before primary settling (#1 wastewater), wastewater after primary settling (#2 wastewater), wastewater after activated sludge tank (#3 wastewater), and centrate (#4 wastewater), which is the wastewater generated in sludge centrifuge. The average specific growth rates in the exponential period were 0.412, 0.429, 0.343, and 0.948 day(-1) for wastewaters #1, #2, #3, and #4, respectively. The removal rates of NH4-N were 82.4%, 74.7%, and 78.3% for wastewaters #1, #2, and #4, respectively. For #3 wastewater, 62.5% of NO3-N, the major inorganic nitrogen form, was removed with 6.3-fold of NO2-N generated. From wastewaters #1, #2, and #4, 83.2%, 90.6%, and 85.6% phosphorus and 50.9%, 56.5%, and 83.0% COD were removed, respectively. Only 4.7% was removed in #3 wastewater and the COD in #3 wastewater increased slightly after algal growth, probably due to the excretion of small photosynthetic organic molecules by algae. Metal ions, especially Al, Ca, Fe, Mg, and Mn in centrate, were found to be removed very efficiently. The results of this study suggest that growing algae in nutrient-rich centrate offers a new option of applying algal process in MWTP to manage the nutrient load for the aeration tank to which the centrate is returned, serving the dual roles of nutrient reduction and valuable biofuel feedstock production.

  17. Proliferation of group II introns in the chloroplast genome of the green alga Oedocladium carolinianum (Chlorophyceae)

    PubMed Central

    Otis, Christian

    2016-01-01

    Background The chloroplast genome sustained extensive changes in architecture during the evolution of the Chlorophyceae, a morphologically and ecologically diverse class of green algae belonging to the Chlorophyta; however, the forces driving these changes are poorly understood. The five orders recognized in the Chlorophyceae form two major clades: the CS clade consisting of the Chlamydomonadales and Sphaeropleales, and the OCC clade consisting of the Oedogoniales, Chaetophorales, and Chaetopeltidales. In the OCC clade, considerable variations in chloroplast DNA (cpDNA) structure, size, gene order, and intron content have been observed. The large inverted repeat (IR), an ancestral feature characteristic of most green plants, is present in Oedogonium cardiacum (Oedogoniales) but is lacking in the examined members of the Chaetophorales and Chaetopeltidales. Remarkably, the Oedogonium 35.5-kb IR houses genes that were putatively acquired through horizontal DNA transfer. To better understand the dynamics of chloroplast genome evolution in the Oedogoniales, we analyzed the cpDNA of a second representative of this order, Oedocladium carolinianum. Methods The Oedocladium cpDNA was sequenced and annotated. The evolutionary distances separating Oedocladium and Oedogonium cpDNAs and two other pairs of chlorophycean cpDNAs were estimated using a 61-gene data set. Phylogenetic analysis of an alignment of group IIA introns from members of the OCC clade was performed. Secondary structures and insertion sites of oedogonialean group IIA introns were analyzed. Results The 204,438-bp Oedocladium genome is 7.9 kb larger than the Oedogonium genome, but its repertoire of conserved genes is remarkably similar and gene order differs by only one reversal. Although the 23.7-kb IR is missing the putative foreign genes found in Oedogonium, it contains sequences coding for a putative phage or bacterial DNA primase and a hypothetical protein. Intergenic sequences are 1.5-fold longer and

  18. Lineage-specific fragmentation and nuclear relocation of the mitochondrial cox2 gene in chlorophycean green algae (Chlorophyta).

    PubMed

    Rodríguez-Salinas, Elizabeth; Riveros-Rosas, Héctor; Li, Zhongkui; Fucíková, Karolina; Brand, Jerry J; Lewis, Louise A; González-Halphen, Diego

    2012-07-01

    In most eukaryotes the subunit 2 of cytochrome c oxidase (COX2) is encoded in intact mitochondrial genes. Some green algae, however, exhibit split cox2 genes (cox2a and cox2b) encoding two polypeptides (COX2A and COX2B) that form a heterodimeric COX2 subunit. Here, we analyzed the distribution of intact and split cox2 gene sequences in 39 phylogenetically diverse green algae in phylum Chlorophyta obtained from databases (28 sequences from 22 taxa) and from new cox2 data generated in this work (23 sequences from 18 taxa). Our results support previous observations based on a smaller number of taxa, indicating that algae in classes Prasinophyceae, Ulvophyceae, and Trebouxiophyceae contain orthodox, intact mitochondrial cox2 genes. In contrast, all of the algae in Chlorophyceae that we examined exhibited split cox2 genes, and could be separated into two groups: one that has a mitochondrion-localized cox2a gene and a nucleus-localized cox2b gene ("Scenedesmus-like"), and another that has both cox2a and cox2b genes in the nucleus ("Chlamydomonas-like"). The location of the split cox2a and cox2b genes was inferred using five different criteria: differences in amino acid sequences, codon usage (mitochondrial vs. nuclear), codon preference (third position frequencies), presence of nucleotide sequences encoding mitochondrial targeting sequences and presence of spliceosomal introns. Distinct green algae could be grouped according to the form of cox2 gene they contain: intact or fragmented, mitochondrion- or nucleus-localized, and intron-containing or intron-less. We present a model describing the events that led to mitochondrial cox2 gene fragmentation and the independent and sequential migration of cox2a and cox2b genes to the nucleus in chlorophycean green algae. We also suggest that the distribution of the different forms of the cox2 gene provides important insights into the phylogenetic relationships among major groups of Chlorophyceae.

  19. Two light-activated conductances in the eye of the green alga Volvox carteri.

    PubMed Central

    Braun, F J; Hegemann, P

    1999-01-01

    Photoreceptor currents of the multicellular green alga Volvox carteri were analyzed using a dissolver mutant. The photocurrents are restricted to the eyespot region of somatic cells. Photocurrents are detectable from intact cells and excised eyes. The rhodopsin action spectrum suggests that the currents are induced by Volvox rhodopsin. Flash-induced photocurrents are a composition of a fast Ca2+-carried current (PF) and a slower current (PS), which is carried by H+. PF is a high-intensity response that appears with a delay of less than 50 micros after flash. The stimulus-response curve of its initial rise is fit by a single exponential and parallels the rhodopsin bleaching. These two observations suggest that the responsible channel is closely connected to the rhodopsin, both forming a tight complex. At low flash energies PS is dominating. The current delay increases up to 10 ms, and the PS amplitude saturates when only a few percent of the rhodopsin is bleached. The data are in favor of a second signaling system, which includes a signal transducer mediating between rhodopsin and the channel. We present a model of how different modes of signal transduction are accomplished in this alga under different light conditions. PMID:10049347

  20. Inhibition of target of rapamycin signaling by rapamycin in the unicellular green alga Chlamydomonas reinhardtii.

    PubMed

    Crespo, José L; Díaz-Troya, Sandra; Florencio, Francisco J

    2005-12-01

    The macrolide rapamycin specifically binds the 12-kD FK506-binding protein (FKBP12), and this complex potently inhibits the target of rapamycin (TOR) kinase. The identification of TOR in Arabidopsis (Arabidopsis thaliana) revealed that TOR is conserved in photosynthetic eukaryotes. However, research on TOR signaling in plants has been hampered by the natural resistance of plants to rapamycin. Here, we report TOR inactivation by rapamycin treatment in a photosynthetic organism. We identified and characterized TOR and FKBP12 homologs in the unicellular green alga Chlamydomonas reinhardtii. Whereas growth of wild-type Chlamydomonas cells is sensitive to rapamycin, cells lacking FKBP12 are fully resistant to the drug, indicating that this protein mediates rapamycin action to inhibit cell growth. Unlike its plant homolog, Chlamydomonas FKBP12 exhibits high affinity to rapamycin in vivo, which was increased by mutation of conserved residues in the drug-binding pocket. Furthermore, pull-down assays demonstrated that TOR binds FKBP12 in the presence of rapamycin. Finally, rapamycin treatment resulted in a pronounced increase of vacuole size that resembled autophagic-like processes. Thus, our findings suggest that Chlamydomonas cell growth is positively controlled by a conserved TOR kinase and establish this unicellular alga as a useful model system for studying TOR signaling in photosynthetic eukaryotes.

  1. Release of reduced inorganic selenium species into waters by the green fresh water algae Chlorella vulgaris.

    PubMed

    Simmons, Denina Bobbie Dawn; Wallschläger, Dirk

    2011-03-15

    The common green fresh water algae Chlorella vulgaris was exposed to starting concentrations of 10 μg/L selenium in the form of selenate, selenite, or selenocyanate (SeCN(-)) for nine days in 10% Bold's basal medium. Uptake of selenate was more pronounced than that of selenite, and there was very little uptake of selenocyanate. Upon uptake of selenate, significant quantities of selenite and selenocyanate were produced by the algae and released back into the growth medium; no selenocyanate was released after selenite uptake. Release of the reduced metabolites after selenate exposure appeared to coincide with increasing esterase activity in solution, indicating that cell death (lysis) was the primary emission pathway. This is the first observation of biotic formation of selenocyanate and its release into waters from a nonindustrial source. The potential environmental implications of this laboratory observation are discussed with respect to the fate of selenium in impacted aquatic systems, the ecotoxicology of selenium bioaccumulation, and the interpretation of environmental selenium speciation data generated, using methods incapable of positively identifying reduced inorganic selenium species, such as selenocyanate.

  2. Effect of Nanohexaconazole on Nitrogen Fixing Blue Green Algae and Bacteria.

    PubMed

    Kumar, Rajesh; Gopal, Madhuban; Pabbi, Sunil; Paul, Sangeeta; Alam, Md Imteyaz; Yadav, Saurabh; Nair, Kishore Kumar; Chauhan, Neetu; Srivastava, Chitra; Gogoi, Robin; Singh, Pradeep Kumar; Goswami, Arunava

    2016-01-01

    Nanohexaconazole is a highly efficient fungicide against Rhizoctonia solani. Nanoparticles are alleged to adversely affect the non-target organisms. In order to evaluate such concern, the present study was carried out to investigate the effect of nanohexaconazole and its commercial formulation on sensitive nitrogen fixing blue green algae (BGA) and bacteria. Various activities of algae and bacteria namely growth, N-fixation, N-assimilation, Indole acetic acid (IAA) production and phosphate solubilization were differently affected in the presence of hexaconazole. Although, there was stimulatory to slightly inhibitory effect on the growth measurable parameters of the organisms studied at the recommended dose of nanohexaconazole, but its higher dose was inhibitory to all these microorganisms. On the other hand, the recommended as well as higher dose of commercial hexaconazole showed much severe inhibition of growth and metabolic activity of these organisms as compared to the nano preparation. The uses of nanohexazconazole instead of hexaconazole as a fungicide will not only help to control various fungal pathogens but also sustain the growth and activity of these beneficial microorganisms for sustaining soil fertility and productivity.

  3. Fatty acid profiles of four filamentous green algae under varying culture conditions.

    PubMed

    Liu, Junzhuo; Vanormelingen, Pieter; Vyverman, Wim

    2016-01-01

    Although benthic filamentous algae are interesting targets for wastewater treatment and biotechnology, relatively little is known about their biochemical composition and variation in response to growth conditions. Fatty acid composition of four benthic filamentous green algae was determined in different culture conditions. Although the response was partly species-dependent, increasing culture age, nitrogen deprivation and dark exposure of stationary phase greatly increased both total fatty acid content (TFA) from 12-35 to 40-173mgg(-1) dry weight (DW) and the relative proportion of polyunsaturated fatty acids (PUFAs) from 21-58% to 55-87% of TFA, with dark exposure having the greatest effect. However, the main variation in fatty acid composition was between species, with Uronema being rich in C16:0 (2.3% of DW), Klebsormidium in C18:2ω6 (5.4% of DW) and Stigeoclonium in C18:3ω3 (11.1% of DW). This indicates the potential of the latter two species as potential sources of these PUFAs. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Removal of Selected Pharmaceutical and Personal Care Products by the Green Alga Nannochloris sp.

    NASA Astrophysics Data System (ADS)

    Bai, X.; Acharya, K.

    2016-12-01

    Emerging contaminants have become an increasing concern in the environment due to their ubiquitous distribution and potential adverse effects on wildlife and humans. Municipal wastewater is a major source of pharmaceutical and personal care products (PPCPs) in the Las Vegas metropolitan area. The ecotoxic impacts of PPCPs on aquatic organisms include development of antimicrobial resistance, decreases in plankton diversity, and endocrine disruption. Freshwater algae can be responsible for the uptake and transfer of the contaminants because they are a major food source for most aquatic organisms. This research applied laboratory-based incubation studies to evaluate the removal efficiency and uptake mechanisms of the selected PPCPs (trimethoprim, sulfamethoxazole, and triclosan) by the green alga Nannochloris sp. The results showed that trimethoprim and sulfamethoxazole remained in the algal culture at 100% and 68%, respectively, after 14 days of incubation, and therefore were not significantly removed from the medium. However, the antimicrobial triclosan was significantly removed from the medium. Immediately after incubation began, 74% of triclosan dissipated and 100% of triclosan was removed after 7 days of incubation. Additionally, over 42% of triclosan was found associated with the algal cells throughout the incubation. The results demonstrate that the presence of Nannochloris sp. eliminated triclosan in the aquatic system, but could not significantly remove the antibiotics trimethoprim and sulfamethoxazole. This study provided crucial information that toxicity of triclosan in aquatic organisms is a critical concern because of its high uptake by phytoplankton. The resistance of trimethoprim and sulfamethoxazole to uptake by phytoplankton may threaten water quality.

  5. The Unicellular Green Alga Chlamydomonas reinhardtii as an Experimental System to Study Chloroplast RNA Metabolism

    NASA Astrophysics Data System (ADS)

    Nickelsen, J.; Kück, U.

    Chloroplasts are typical organelles of photoautotrophic eukaryotic cells which drive a variety of functions, including photosynthesis. For many years the unicellular green alga Chlamydomonas reinhardtii has served as an experimental organism for studying photosynthetic processes. The recent development of molecular tools for this organism together with efficient methods of genetic analysis and the availability of many photosynthesis mutants has now made this alga a powerful model system for the analysis of chloroplast biogenesis. For example, techniques have been developed to transfer recombinant DNA into both the nuclear and the chloroplast genome. This allows both complementation tests and analyses of gene functions in vivo. Moreover, site-specific DNA recombinations in the chloroplast allow targeted gene disruption experiments which enable a "reverse genetics" to be performed. The potential of the algal system for the study of chloroplast biogenesis is illustrated in this review by the description of regulatory systems of gene expression involved in organelle biogenesis. One example concerns the regulation of trans-splicing of chloroplast mRNAs, a process which is controlled by both multiple nuclear- and chloroplast-encoded factors. The second example involves the stabilization of chloroplast mRNAs. The available data lead us predict distinct RNA elements, which interact with trans-acting factors to protect the RNA against nucleolytic attacks.

  6. Genetic basis for soma is present in undifferentiated volvocine green algae.

    PubMed

    Grochau-Wright, Z I; Hanschen, E R; Ferris, P J; Hamaji, T; Nozaki, H; Olson, B J S C; Michod, R E

    2017-06-01

    Somatic cellular differentiation plays a critical role in the transition from unicellular to multicellular life, but the evolution of its genetic basis remains poorly understood. By definition, somatic cells do not reproduce to pass on genes and so constitute an extreme form of altruistic behaviour. The volvocine green algae provide an excellent model system to study the evolution of multicellularity and somatic differentiation. In Volvox carteri, somatic cell differentiation is controlled by the regA gene, which is part of a tandem duplication of genes known as the reg cluster. Although previous work found the reg cluster in divergent Volvox species, its origin and distribution in the broader group of volvocine algae has not been known. Here, we show that the reg cluster is present in many species without somatic cells and determine that the genetic basis for soma arose before the phenotype at the origin of the family Volvocaceae approximately 200 million years ago. We hypothesize that the ancestral function was involved in regulating reproduction in response to stress and that this function was later co-opted to produce soma. Determining that the reg cluster was co-opted to control somatic cell development provides insight into how cellular differentiation, and with it greater levels of complexity and individuality, evolves. © 2017 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2017 European Society For Evolutionary Biology.

  7. Speculations on a possible essential function of the gelatinous sheath of blue-green algae.

    PubMed

    Lange, W

    1976-08-01

    Voluminous and often fluffy sheaths surrounding blue-green algal cells are observed (a) in productive natural waters, (b) in bacteria-containing laboratory cultures growing in inorganic nutrient media with added bacteria-assimilable organic matter, and (c) in axenic cultures in the same inorganic media even without added organic matter. The sheaths of bacteria-associated species in inorganic media without added organic matter are, by comparison, thin, and growth is meager. Repeated observations show that voluminous sheaths and vigorous growth of algal species are associated. It is suggested that formation and retention of a voluminous shealth provide a microenvironment around the algal cell where essential nutrients, present at only submarginal levels in the surrounding water, are concentrated and become readily available to the cell. The increase in nutrient concentration above a critical level, in turn, leads to vigorous algal growth. The voluminous sheath produced by the alga is not attacked by alga-associated bacteria when other assimilable organic matter is available; but in the absence of a more suitalble food, the bacteria feed on the less desirable gelatinous sheath, markedly reducing its thickness and causing meager algal growth.

  8. Detection, purification and characterization of a lectin from freshwater green algae Spirogyra spp.

    PubMed

    Oliveira, Antônia S DE; Lóssio, Cláudia F; Rangel, Anne J; Martins, Maria G Q; Nascimento, Fernando E P DO; Andrade, Maria L L DE; Cavada, Benildo S; Lacerda, Sírleis R; Nascimento, Kyria S DO

    2017-08-31

    Freshwater algae are rich sources of structurally biologically active metabolites, such as fatty acids, steroids, carotenoids and polysaccharides. Among these metabolites, lectins stand out. Lectins are proteins or glycoproteins of non-immune origin which bind to carbohydrates or glycoconjugates, without changing ligand structure. Many studies have reported on the use of Spirogyra spp. as effective bioindicators of heavy metals; however, reports on Spirogyra molecular bioprospecting are quite limited. Therefore, this study aimed to detect, isolate, purify and characterize a lectin present in the freshwater green algae Spirogyra. Presence of the lectin protein in the extract was detected by hemagglutination assays. Subsequently, the protein extract was subjected to a sugar inhibition assay to identify the lectin-specific carbohydrate. Following this, the extract was applied to a guar gum column to afford the pure lectin. The lectin was inhibited by N-acetyl-glucosamine and N-acetyl-beta-D-mannose, but more strongly by D-galactose. The apparent molecular mass of the purified lectin was evaluated by Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (SDS-PAGE). Electrophoretic analysis revealed a single protein band with an apparent molecular mass of 56 kDa. Thus, it could be concluded that a lectin was purified from Spirogyra spp.

  9. Optimization of recombinant protein expression in the chloroplasts of green algae.

    PubMed

    Fletcher, Samuel P; Muto, Machiko; Mayfield, Stephen P

    2007-01-01

    Through advances in molecular and genetic techniques, protein expression in the chloroplasts of green algae has been optimized for high-level expression. Recombinant proteins expressed in algae have the potential to provide novel and safe treatment of disease and infection where current, high-cost drugs are the only option, or worse, where therapeutic drugs are not available due to their prohibitively high-cost to manufacture. Optimization of recombinant protein expression in Chlamydomonas reinhardtii chloroplasts has been accomplished by employing chloroplast codon bias and combinatorial examination of promoter and UTR combinations. In addition, as displayed by the expression of an anti-herpes antibody, the C. reinhardtii chloroplast is capable of correctly folding and assembling complex mammalian proteins. These data establish algal chloroplasts as a system for the production of complex human therapeutic proteins in soluble and active form, and at significantly reduced time and cost compared to existing production systems. Production of recombinant proteins in algal chloroplasts may enable further development of safe, efficacious and cost-effective protein therapeutics.

  10. Characterization of a heat-shock-inducible hsp70 gene of the green alga Volvox carteri.

    PubMed

    Cheng, Qian; Hallmann, Armin; Edwards, Lisseth; Miller, Stephen M

    2006-04-12

    The green alga Volvox carteri possesses several thousand cells, but just two cell types: large reproductive cells called gonidia, and small, biflagellate somatic cells. Gonidia are derived from large precursor cells that are created during embryogenesis by asymmetric cell divisions. The J domain protein GlsA (Gonidialess A) is required for these asymmetric divisions and is believed to function with an Hsp70 partner. As a first step toward identifying this partner, we cloned and characterized V. carteri hsp70A, which is orthologous to HSP70A of the related alga Chlamydomonas reinhardtii. Like HSP70A, V. carteri hsp70A contains multiple heat shock elements (HSEs) and is highly inducible by heat shock. Consistent with these properties, Volvox transformants that harbor a glsA antisense transgene that is driven by an hsp70A promoter fragment express Gls phenotypes that are temperature-dependent. hsp70A appears to be the only gene in the genome that encodes a cytoplasmic Hsp70, so we conclude that Hsp70A is clearly the best candidate to be the chaperone that participates with GlsA in asymmetric cell division.

  11. Effect of aluminum and zinc on enzyme activities in the green Alga Selenastrum capricorutum

    SciTech Connect

    Kong, F.X.; Chen, Y.

    1995-11-01

    Acid rain produced by atmospheric pollution may decrease the pH value of water and increase the availability and potential toxicity of metals in water which have detrimental effects on aquatic organism, including algae, the important component of the primary production, and, thus, the entire aquatic food chain. Recent reviews of the effects of acid rain on freshwater ecosystems have emphasized research interest in soluble trivalent aluminum, although Al is rated low among trace metals in biological importance. On the other hand, zinc is an important trace element for the growth of phytoplankton and the cofactor of some enzymes. The growth response and tolerance of different species of algae to Al and Zn have been reported by Whitton who showed that algal growth would be stimulated by lower levels of the metals and totally inhibited by higher levels. These is little information, however, on the effect of Al on biochemical processes in aquatic organisms. This study investigates the influence of aluminum and zinc on several physioclogical processes in S. capricournutum, a common species of green algal in lake water. Algal growth (dry weight), ATP levels and the activities of several enzymes in the algal cells were measured after the treatment with various concentrations of Al and Zn in culture medium. Special attention is given to the relation between the enzymatic response and algal growth. 15 refs., 2 figs., 1 tab.

  12. Fatty Acid Composition of Unicellular Strains of Blue-Green Algae1

    PubMed Central

    Kenyon, C. N.

    1972-01-01

    The fatty acids of 34 strains of unicellular blue-green algae provisionally assigned to the genera Synechococcus, Aphanocapsa, Gloeocapsa, Microcystis, and Chlorogloea by Stanier et al. have been chemically characterized. The strains analyzed can be divided into a series of compositional groups based upon the highest degree of unsaturation of the major cellular fatty acids. Twenty strains fall into the group characterized by one trienoic fatty acid isomer (α-linolenic acid), and seven strains fall into a group characterized by another trienoic acid isomer (γ-linolenic acid). These groups in many cases correlate well with groupings based upon other phenotypic characters of the strains, e.g., deoxyribonucleic acid base composition. The assignment of a strain to a compositional group is not altered when the strain is grown under a variety of different culture conditions. All strains contain glycolipids with the properties of mono- and digalactosyldiglycerides. PMID:4621688

  13. Multi-Level Light Capture Control in Plants and Green Algae.

    PubMed

    Wobbe, Lutz; Bassi, Roberto; Kruse, Olaf

    2016-01-01

    Life on Earth relies on photosynthesis, and the ongoing depletion of fossil carbon fuels has renewed interest in phototrophic light-energy conversion processes as a blueprint for the conversion of atmospheric CO2 into various organic compounds. Light-harvesting systems have evolved in plants and green algae, which are adapted to the light intensity and spectral composition encountered in their habitats. These organisms are constantly challenged by a fluctuating light supply and other environmental cues affecting photosynthetic performance. Excess light can be especially harmful, but plants and microalgae are equipped with different acclimation mechanisms to control the processing of sunlight absorbed at both photosystems. We summarize the current knowledge and discuss the potential for optimization of phototrophic light-energy conversion.

  14. Mebamamides A and B, Cyclic Lipopeptides Isolated from the Green Alga Derbesia marina.

    PubMed

    Iwasaki, Arihiro; Ohno, Osamu; Sumimoto, Shinpei; Matsubara, Teruhiko; Shimada, Satoshi; Sato, Toshinori; Suenaga, Kiyotake

    2015-04-24

    Mebamamides A and B, new lipopeptides with four d-amino acid residues and a 3,8-dihydroxy-9-methyldecanoic acid residue, were isolated from the green alga Derbesia marina. Their gross structures were elucidated by spectroscopic and ESI-ITMS analyses. The absolute configurations except for the two leucines were revealed based on chiral-phase HPLC analyses of the acid hydrolysate and a modified Mosher's method. A distinction between D-Leu and L-Leu in the sequence was established by the application of a dansyl-Edman method to the partial acid hydrolysate. Mebamamide A did not exhibit any growth inhibitory activity against HeLa and HL60 cells at 10 μM, and mebamamide B did not exhibit any growth inhibitory activity against those cells at 100 μM. Additionally, it was suggested that mebamamide B induced the differentiation of HL60 cells into macrophage-like cells at 100 μM.

  15. Complete chloroplast genome of green tide algae Ulva flexuosa (Ulvophyceae, Chlorophyta) with comparative analysis.

    PubMed

    Cai, Chuner; Wang, Lingke; Zhou, Lingjie; He, Peimin; Jiao, Binghua

    2017-01-01

    Ulva flexuosa, one kind of green tide algae, has outbroken in the Yellow Sea of China during the past ten years. In the present study, we sequenced the chloroplast genome of U. flexuosa followed by annotation and comparative analysis. It indicated that the chloroplast genomes had high conservation among Ulva spp., and high rearrangement outside them. Though U. flexuosa was closer to U. linza than U. fasciata in phylogenetic tree, the average Ka/Ks between U. flexuosa and U. linza assessed by 67 protein-coding genes was higher than those between U. flexuosa and other species in Ulva spp., due to the variation of psbZ, psbM and ycf20. Our results laid the foundation for the future studies on the evolution of chloroplast genomes of Ulva, as well as the molecular identification of U. flexuosa varieties.

  16. Viruses of eukaryotic green algae; Progress report, June 20, 1990--July 1, 1991

    SciTech Connect

    Van Etten, J.L.

    1991-12-31

    Many large polyhedral, dsDNA containing (ca. 330 kb), plaque forming viruses which infect a unicellular, eukaryotic, chlorella-like green alga have been isolated and characterized. The plaque assay, the ability to synchronously infect the host, the short life cycle, and the ability of the viruses to undergo homologous recombination make them excellent model systems for studying many plant cell functions in the manner that bacterial and animal viruses have been used to study bacterial and animal cell functions. These viruses have several unique features including: (1) coding for DNA methyltransferase and site-specific (restriction) endonucleases and (2) unlike other viruses, these viruses appear to code for the enzymes involved in the glycosylation of their glycoproteins.

  17. 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.

  18. Spirulan from blue-green algae inhibits fibrin and blood clots: its potent antithrombotic effects.

    PubMed

    Choi, Jun-Hui; Kim, Seung; Kim, Sung-Jun

    2015-05-01

    We investigated in vitro and in vivo fibrinolytic and antithrombotic activity of spirulan and analyzed its partial biochemical properties. Spirulan, a sulfated polysaccharide from the blue-green alga Arthrospira platensis, exhibits antithrombotic potency. Spirulan showed a strong fibrin zymogram lysis band corresponding to its molecular mass. It specifically cleaved Aα and Bβ, the major chains of fibrinogen. Spirulan directly decreased the activity of thrombin and factor X activated (FXa), procoagulant proteins. In vitro assays using human fibrin and mouse blood clots showed fibrinolytic and hemolytic activities of spirulan. Spirulan (2 mg/kg) showed antithrombotic effects in the ferric chloride (FeCl3 )-induced carotid arterial thrombus model and collagen and epinephrine-induced pulmonary thromboembolism mouse model. These results may be attributable to the prevention of thrombus formation and partial lysis of thrombus. Therefore, we suggest that spirulan may be a potential antithrombotic agent for thrombosis-related diseases.

  19. Seawater-based methane production from blue-green algae biomass by marine bacteria coculture

    SciTech Connect

    Matsunaga, T.; Izumida, H.

    1984-01-01

    Marine-enriched culture NKM 004 produced methane from various carbohydrates, but methane production was inhibited by sulfate and acetate accumulated in the medium. On the other hand, marine methanogenic bacterium NKM 006 produced methane from acetate and methyltrophic substrates, and methane production was not inhibited by sulfate. The mixture of NKM 004 and NKM 006 continuously produced methane from marine blue-green algae Dermocarpa species NKBG 102B at 54 ..mu..mol/L medium/h for 200 h and the dry weight of the algal biomass was decreased to 25% of the initial weight in the natural seawater. Conversion of algal carbohydrate (glucose equivalent) to methane was 65%. Results indicate that this system is promising for methane production based on seawater and solar energy.

  20. Regulatory effect of hydrogen on nitrogenase activity of the blue-green alga (cyanobacterium) Nostoc muscorum.

    PubMed

    Scherer, S; Kerfin, W; Böger, P

    1980-03-01

    Preincubation of the blue-green alga (cyanobacterium) Nostoc muscorum under an atmosphere of argon plus acetylene in the light led to a greater than fourfold increase of light-induced hydrogen evolution and to a 50% increase of acetylene reduction, as compared to cells that had not been preconditioned. The basic and the increased hydrogen evolution were both due to nitrogenase activity. Furthermore, after preincubation the hydrogen uptake, usually observed with unconditional cells, was abolished. Nostoc preincubated under acetylene evolved hydrogen in the light even in the presence of nitrogen for at least 2 h, with a 15-fold increase as compared to the unconditioned cells. These acetylene effects could be completely abolished by the presence of hydrogen during acetylene preincubation. These findings indicate that the hydrogen concentration in N. muscorum cells plays a role in regulation of nitrogenase activity.

  1. Synchronization of Green Algae by Light and Dark Regimes for Cell Cycle and Cell Division Studies.

    PubMed

    Hlavová, Monika; Vítová, Milada; Bišová, Kateřina

    2016-01-01

    A synchronous population of cells is one of the prerequisites for studying cell cycle processes such as DNA replication, nuclear and cellular division. Green algae dividing by multiple fission represent a unique single cell system enabling the preparation of highly synchronous cultures by application of a light-dark regime similar to what they experience in nature. This chapter provides detailed protocols for synchronization of different algal species by alternating light-dark cycles; all critical points are discussed extensively. Moreover, detailed information on basic analysis of cell cycle progression in such cultures is presented, including analyses of nuclear, cellular, and chloroplast divisions. Modifications of basic protocols that enable changes in cell cycle progression are also suggested so that nuclear or chloroplast divisions can be followed separately.

  2. Development of suitable photobioreactors for CO2 sequestration addressing global warming using green algae and cyanobacteria.

    PubMed

    Kumar, Kanhaiya; Dasgupta, Chitralekha Nag; Nayak, Bikram; Lindblad, Peter; Das, Debabrata

    2011-04-01

    CO(2) sequestration by cyanobacteria and green algae are receiving increased attention in alleviating the impact of increasing CO(2) in the atmosphere. They, in addition to CO(2) capture, can produce renewable energy carriers such as carbon free energy hydrogen, bioethanol, biodiesel and other valuable biomolecules. Biological fixation of CO(2) are greatly affected by the characteristics of the microbial strains, their tolerance to temperature and the CO(2) present in the flue gas including SO(X), NO(X). However, there are additional factors like the availability of light, pH, O(2) removal, suitable design of the photobioreactor, culture density and the proper agitation of the reactor that will affect significantly the CO(2) sequestration process. Present paper deals with the photobioreactors of different geometry available for biomass production. It also focuses on the hybrid types of reactors (integrating two reactors) which can be used for overcoming the bottlenecks of a single photobioreactor.

  3. Calcium spirulan, an inhibitor of enveloped virus replication, from a blue-green alga Spirulina platensis.

    PubMed

    Hayashi, T; Hayashi, K; Maeda, M; Kojima, I

    1996-01-01

    Bioactivity-directed fractionation of a hot H2O extract from a blue-green alga Spirulina platensis led to the isolation of a novel sulfated polysaccharide named calcium spirulan (Ca-SP) as an antiviral principle. This polysaccharide was composed of rhamnose, ribose, mannose, fructose, galactose, xylose, glucose, glucuronic acid, galacturonic acid, sulfate, and calcium. Ca-SP was found to inhibit the replication of several enveloped viruses, including Herpes simplex virus type 1, human cytomegalovirus, measles virus, mumps virus, influenza A virus, and HIV-1. It was revealed that Ca-SP selectively inhibited the penetration of virus into host cells. Retention of molecular conformation by chelation of calcium ion with sulfate groups was suggested to be indispensable to its antiviral effect.

  4. Blue green alga mediated synthesis of gold nanoparticles and its antibacterial efficacy against Gram positive organisms.

    PubMed

    Suganya, K S Uma; Govindaraju, K; Kumar, V Ganesh; Dhas, T Stalin; Karthick, V; Singaravelu, G; Elanchezhiyan, M

    2015-02-01

    Biofunctionalized gold nanoparticles (AuNPs) play an important role in design and development of nanomedicine. Synthesis of AuNPs from biogenic materials is environmentally benign and possesses high bacterial inhibition and bactericidal properties. In the present study, blue green alga Spirulina platensis protein mediated synthesis of AuNPs and its antibacterial activity against Gram positive bacteria is discussed. AuNPs were characterized using Ultraviolet-visible (UV-vis) spectroscopy, Fluorescence spectroscopy, Fourier Transform-Infrared (FTIR) spectroscopy, Raman spectroscopy, High Resolution-Transmission Electron Microscopy (HR-TEM) and Energy Dispersive X-ray analysis (EDAX). Stable, well defined AuNPs of smaller and uniform shape with an average size of ~ 5 nm were obtained. The antibacterial efficacy of protein functionalized AuNPs were tested against Gram positive organisms Bacillus subtilis and Staphylococcus aureus.

  5. Purification and characterization of phycocyanin from the blue-green alga Aphanizomenon flos-aquae.

    PubMed

    Benedetti, Serena; Rinalducci, Sara; Benvenuti, Francesca; Francogli, Sonia; Pagliarani, Silvia; Giorgi, Luca; Micheloni, Mauro; D'Amici, Gian Maria; Zolla, Lello; Canestrari, Franco

    2006-03-20

    Aphanizomenon flos-aquae (AFA) is a blue-green alga and represents a nutrient-dense food source. In this study the presence of phycocyanin (PC), a blue protein belonging to the photosynthetic apparatus, has been demonstrated in AFA. An efficient method for its separation has been set up: PC can be purified by a simple single step chromatographic run using a hydroxyapatite column (ratio A620/A280 of 4.78), allowing its usage for health-enhancing properties while eliminating other aspecific algal components. Proteomic investigation and HPLC analysis of purified AFA phycobilisomes revealed that, contrary to the well-characterized Synechocystis and Spirulina spp., only one type of biliprotein is present in phycobilisomes: phycocyanins with no allo-phycocyanins. Two subunit polypeptides of PC were also separated: the beta subunit containing two bilins as chromophore and the alpha subunit containing only one.

  6. Complete chloroplast genome of green tide algae Ulva flexuosa (Ulvophyceae, Chlorophyta) with comparative analysis

    PubMed Central

    Jiao, Binghua

    2017-01-01

    Ulva flexuosa, one kind of green tide algae, has outbroken in the Yellow Sea of China during the past ten years. In the present study, we sequenced the chloroplast genome of U. flexuosa followed by annotation and comparative analysis. It indicated that the chloroplast genomes had high conservation among Ulva spp., and high rearrangement outside them. Though U. flexuosa was closer to U. linza than U. fasciata in phylogenetic tree, the average Ka/Ks between U. flexuosa and U. linza assessed by 67 protein-coding genes was higher than those between U. flexuosa and other species in Ulva spp., due to the variation of psbZ, psbM and ycf20. Our results laid the foundation for the future studies on the evolution of chloroplast genomes of Ulva, as well as the molecular identification of U. flexuosa varieties. PMID:28863197

  7. Assessment of blue-green algae in substantially reducing nitrogen fertilizer requirements for biomass fuel crops

    SciTech Connect

    Anderson, D.B.; Molten, P.M.; Metting, B.

    1981-07-01

    Laboratory, mass culture, and field studies are being undertaken in order to assess the potential of using blue-green algae (cyanobacteria) as nitrogen biofertilizers on irrigated ground. Of seven candidate strains, two were chosen for application to replicated field plots sown to field corn and the basis of laboratory-scale soil tray experiments and ease of semi-continuous 8000 l culture. Chosen were Anabaena BM-165, isolated from a local soil and Tolypothrix tenuis, imported from India. Using the acetylene reduction method, Anabaena is estimated from laboratory soil experiments to be able to fix from 30 to 62 kg N/ha/y, and has been mass cultured to a density of 1527 mg dry wt/l. T. tenuis is estimated from laboratory experiments to be able to fix from 27 to 65 kg N/ha/y, and has been mass cultured to a density of 1630 mg dry wt/l.

  8. Predictive modeling studies for the ecotoxicity of ionic liquids towards the green algae Scenedesmus vacuolatus.

    PubMed

    Das, Rudra Narayan; Roy, Kunal

    2014-06-01

    Hazardous potential of ionic liquids is becoming an issue of high concern with increasing application of these compounds in various industrial processes. Predictive toxicological modeling on ionic liquids provides a rational assessment strategy and aids in developing suitable guidance for designing novel analogues. The present study attempts to explore the chemical features of ionic liquids responsible for their ecotoxicity towards the green algae Scenedesmus vacuolatus by developing mathematical models using extended topochemical atom (ETA) indices along with other categories of chemical descriptors. The entire study has been conducted with reference to the OECD guidelines for QSAR model development using predictive classification and regression modeling strategies. The best models from both the analyses showed that ecotoxicity of ionic liquids can be decreased by reducing chain length of cationic substituents and increasing hydrogen bond donor feature in cations, and replacing bulky unsaturated anions with simple saturated moiety having less lipophilic heteroatoms.

  9. Biochemical and morphological characterization of sulfur-deprived and H2-producing Chlamydomonas reinhardtii (green alga).

    PubMed

    Zhang, Liping; Happe, Thomas; Melis, Anastasios

    2002-02-01

    Sulfur deprivation in green algae causes reversible inhibition of photosynthetic activity. In the absence of S, rates of photosynthetic O2 evolution drop below those of O2 consumption by respiration. As a consequence, sealed cultures of the green alga Chlamydomonas reinhardtii become anaerobic in the light, induce the "Fe-hydrogenase" pathway of electron transport and photosynthetically produce H2 gas. In the course of such H2-gas production cells consume substantial amounts of internal starch and protein. Such catabolic reactions may sustain, directly or in directly, the H2-production process. Profile analysis of selected photosynthetic proteins showed a precipitous decline in the amount of ribulose-1,5-bisphosphate carboxylase-oxygenase (Rubisco) as a function of time in S deprivation, a more gradual decline in the level of photosystem (PS) II and PSI proteins, and a change in the composition of the PSII light-harvesting complex (LHC-II). An increase in the level of the enzyme Fe-hydrogenase was noted during the initial stages of S deprivation (0-72 h) followed by a decline in the level of this enzyme during longer (t >72 h) S-deprivation times. Microscopic observations showed distinct morphological changes in C. reinhardtii during S deprivation and H2 production. Ellipsoid-shaped cells (normal photosynthesis) gave way to larger and spherical cell shapes in the initial stages of S deprivation and H2 production, followed by cell mass reductions after longer S-deprivation and H2-production times. It is suggested that, under S-deprivation conditions, electrons derived from a residual PSII H2O-oxidation activity feed into the hydrogenase pathway, thereby contributing to the H2-production process in Chlamydomonas reinhardtii. Interplay between oxygenic photosynthesis, mitochondrial respiration, catabolism of endogenous substrate, and electron transport via the hydrogenase pathway is essential for this light-mediated H2-production process.

  10. Equilibrium, thermodynamic and kinetic investigations for biosorption of uranium with green algae (Cladophora hutchinsiae).

    PubMed

    Bağda, Esra; Tuzen, Mustafa; Sarı, Ahmet

    2017-09-01

    Removal of toxic chemicals from environmental samples with low-cost methods and materials are very useful approach for especially large-scale applications. Green algae are highly abundant biomaterials which are employed as useful biosorbents in many studies. In the present study, an interesting type of green algae, Cladophora hutchinsiae (C. hutchinsiae) was used for removal of highly toxic chemical such as uranium. The pH, biosorbent concentration, contact time and temperature were optimized as 5.0, 12 g/L, 60 min and 20 °C, respectively. For the equilibrium calculations, three well known isotherm models (Langmuir, Freundlich and Dubinin-Radushkevich) were employed. The maximum biosorption capacity of the biosorbent was calculated as about 152 mg/g under the optimum batch conditions. The mean energy of biosorption was calculated as 8.39 kJ/mol from the D-R biosorption isotherm. The thermodynamic and kinetic characteristics of biosorption were also investigated to explain the nature of the process. The kinetic data best fits the pseudo-second-order kinetic model with a regression coefficient of >0.99 for all studied temperatures. The calculated ΔH° and ΔG° values showed that the biosorption process is exothermic and spontaneous for temperatures between 293 and 333 K. Furthermore, after seven cycling process, the sorption and desorption efficiencies of the biosorbent were found to be 70, and 58%, respectively meaning that the biosorbent had sufficiently high reusability performance as a clean-up tool. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Action Spectra for Nitrate and Nitrite Assimilation in Blue-Green Algae 1

    PubMed Central

    Serrano, Aurelio; Losada, Manuel

    1988-01-01

    Action spectra for the assimilation of nitrate and nitrite have been obtained for several blue-green algae (cyanobacteria) with different accessory pigment composition. The action spectra for both nitrate and nitrite utilization by nitrate-grown Anacystis nidulans L-1402-1 cells exhibited a clear peak at about 620 nanometers, corresponding to photosystem II (PSII) C-phycocyanin absorption, the contribution of chlorophyll a (Chl a) being barely detectable. The action spectrum for nitrate reduction by a nitrite reductase mutant of A. nidulans R2 was very similar. All these action spectra resemble the fluorescence excitation spectrum of cell suspensions of the microalgae monitored at 685 nanometers—the fluorescence band of Chl a in PSII. In contrast, the action spectrum for nitrite utilization by nitrogen-starved A. nidulans cells, which are depleted of C-phycocyanin, showed a maximum near 680 nanometers, attributable to Chl a absorption. The action spectrum for nitrite utilization by Calothrix sp. PCC 7601 cells, which contain both C-phycoerythrin and C-phycocyanin as PSII accessory pigments, presented a plateau in the region from 550 to 630 nanometers. In this case, there was also a clear parallelism between the action spectrum and the fluorescence excitation spectrum, which showed two overlapped peaks with maxima at 562 and 633 nanometers. The correlation observed between the action spectra for both nitrate and nitrite assimilation and the light-harvesting pigment content of the blue-green algae studied strongly suggests that phycobiliproteins perform a direct and active role in these photosynthetic processes. PMID:16666041

  12. Sensitivity evaluation of the green alga Chlamydomonas reinhardtii to uranium by pulse amplitude modulated (PAM) fluorometry.

    PubMed

    Herlory, Olivier; Bonzom, Jean-Marc; Gilbin, Rodolphe

    2013-09-15

    Although ecotoxicological studies tend to address the toxicity thresholds of uranium in freshwaters, there is a lack of information on the effects of the metal on physiological processes, particularly in aquatic plants. Knowing that uranium alters photosynthesis via impairment of the water photo-oxidation process, we determined whether pulse amplitude modulated (PAM) fluorometry was a relevant tool for assessing the impact of uranium on the green alga Chlamydomonas reinhardtii and investigated how and to what extent uranium hampered photosynthetic performance. Photosynthetic activity and quenching were assessed from fluorescence induction curves generated by PAM fluorometry, after 1 and 5h of uranium exposure in controlled conditions. The oxygen-evolving complex (OEC) of PSII was identified as the primary action site of uranium, through alteration of the water photo-oxidation process as revealed by F0/Fv. Limiting re-oxidation of the plastoquinone pool, uranium impaired the electron flux between the photosystems until almost complete inhibition of the PSII quantum efficiency ( [Formula: see text] , EC50=303 ± 64 μg UL(-1) after 5h of exposure) was observed. Non-photochemical quenching (qN) was identified as the most sensitive fluorescence parameter (EC50=142 ± 98 μg UL(-1) after 5h of exposure), indicating that light energy not used in photochemistry was dissipated in non-radiative processes. It was shown that parameters which stemmed from fluorescence induction kinetics are valuable indicators for evaluating the impact of uranium on PSII in green algae. PAM fluorometry provided a rapid and reasonably sensitive method for assessing stress response to uranium in microalgae.

  13. Hiding in plain sight: Koshicola spirodelophila gen. et sp. nov. (Chaetopeltidales, Chlorophyceae), a novel green alga associated with the aquatic angiosperm Spirodela polyrhiza.

    PubMed

    Watanabe, Shin; Fučíková, Karolina; Lewis, Louise A; Lewis, Paul O

    2016-05-01

    Discovery and morphological characterization of a novel epiphytic aquatic green alga increases our understanding of Chaetopeltidales, a poorly known order in Chlorophyceae. Chloroplast genomic data from this taxon reveals an unusual architecture previously unknown in green algae. Using light and electron microscopy, we characterized the morphology and ultrastructure of a novel taxon of green algae. Bayesian phylogenetic analyses of nuclear and plastid genes were used to test the hypothesized membership of this taxon in order Chaetopeltidales. With next-generation sequence data, we assembled the plastid genome of this novel taxon and compared its gene content and architecture to that of related species to further investigate plastid genome traits. The morphology and ultrastructure of this alga are consistent with placement in Chaetopeltidales (Chlorophyceae), but a distinct trait combination supports recognition of this alga as a new genus and species-Koshicola spirodelophila gen. et sp. nov. Its placement in the phylogeny as a descendant of a deep division in the Chaetopeltidales is supported by analysis of molecular data sets. The chloroplast genome is among the largest reported in green algae and the genes are distributed on three large (rather than a single) chromosome, in contrast to other studied green algae. The discovery of Koshicola spirodelophila gen. et sp. nov. highlights the importance of investigating even commonplace habitats to explore new microalgal diversity. This work expands our understanding of the morphological and chloroplast genomic features of green algae, and in particular those of the poorly studied Chaetopeltidales. © 2016 Botanical Society of America.

  14. Ostreococcus tauri is a new model green alga for studying iron metabolism in eukaryotic phytoplankton.

    PubMed

    Lelandais, Gaëlle; Scheiber, Ivo; Paz-Yepes, Javier; Lozano, Jean-Claude; Botebol, Hugo; Pilátová, Jana; Žárský, Vojtěch; Léger, Thibaut; Blaiseau, Pierre-Louis; Bowler, Chris; Bouget, François-Yves; Camadro, Jean-Michel; Sutak, Robert; Lesuisse, Emmanuel

    2016-05-03

    Low iron bioavailability is a common feature of ocean surface water and therefore micro-algae developed original strategies to optimize iron uptake and metabolism. The marine picoeukaryotic green alga Ostreococcus tauri is a very good model for studying physiological and genetic aspects of the adaptation of the green algal lineage to the marine environment: it has a very compact genome, is easy to culture in laboratory conditions, and can be genetically manipulated by efficient homologous recombination. In this study, we aimed at characterizing the mechanisms of iron assimilation in O. tauri by combining genetics and physiological tools. Specifically, we wanted to identify and functionally characterize groups of genes displaying tightly orchestrated temporal expression patterns following the exposure of cells to iron deprivation and day/night cycles, and to highlight unique features of iron metabolism in O. tauri, as compared to the freshwater model alga Chalamydomonas reinhardtii. We used RNA sequencing to investigated the transcriptional responses to iron limitation in O. tauri and found that most of the genes involved in iron uptake and metabolism in O. tauri are regulated by day/night cycles, regardless of iron status. O. tauri lacks the classical components of a reductive iron uptake system, and has no obvious iron regulon. Iron uptake appears to be copper-independent, but is regulated by zinc. Conversely, iron deprivation resulted in the transcriptional activation of numerous genes encoding zinc-containing regulation factors. Iron uptake is likely mediated by a ZIP-family protein (Ot-Irt1) and by a new Fea1-related protein (Ot-Fea1) containing duplicated Fea1 domains. The adaptation of cells to iron limitation involved an iron-sparing response tightly coordinated with diurnal cycles to optimize cell functions and synchronize these functions with the day/night redistribution of iron orchestrated by ferritin, and a stress response based on the induction of

  15. Phylogenetic and morphological characterization of the green alga infesting the horse mussel Modiolus modiolus from Vityaz Bay (Peter the Great Bay, Sea of Japan).

    PubMed

    Syasina, I G; Kukhlevsky, A D; Kovaleva, A L; Vaschenko, M A

    2012-10-01

    In this work, the ultrastructural features and taxonomic position of the green microalga infesting the horse mussel Modiolus modiolus from the north-western Pacific (Vityaz Bay, Peter the Great Bay, Sea of Japan) are reported. Mussels were collected monthly from May to September of 2009. In different months, the prevalence of mussels with green tissues was 16.6-62.5% (mean 43%). The most affected organs were the mantle, digestive gland and gonad. Histological analysis revealed severe infiltration of the connective tissue by hemocytes containing the alga cells. Electron microscopy showed that the alga was morphologically similar to the green algae from the genus Coccomyxa (Chlorophyta: Chlorococcales). Two new primers were designed to generate partial small subunit (SSU) rRNA sequences of the green alga from M. modiolus. Phylogenetic analysis based on the comparison of the SSU rRNA sequences of the trebouxiophyceans confirmed an affiliation of the green alga with the genus Coccomyxa. The sequence (1296 bases) of the green alga from M. modiolus was most closely related to the sequence CPCC 508 (AM981206) (identity 100%), obtained from an acid-tolerant, free-living chlorophyte microalga Coccomyxa sp. and to the sequences EU127470 (identity 99.3%) and EU127471 (identity 99.7%) of the green alga, presumably the true Coccomyxa parasitica, infecting the blue mussel Mytilus edulis from the Flensburg Fjord (North Atlantic). Copyright © 2012 Elsevier Inc. All rights reserved.

  16. Effects of temperature on the germination of green algae micro-propagules in coastal waters of the Subei Shoal, China

    NASA Astrophysics Data System (ADS)

    Song, Wei; Peng, Keqin; Xiao, Jie; Li, Yan; Wang, Zongling; Liu, Xiangqing; Fu, Mingzhu; Fan, Shiliang; Zhu, Mingyuan; Li, Ruixiang

    2015-09-01

    Since 2007, large-scale green tides that primarily consisted of Ulva prolifera have consecutively invaded the coast of Qingdao (36°06'N, 120°25'E, PR China) in summer. The germination of green algae micro-propagules in the Subei Shoal played a significant role in the formation of these green tides. The change in sea temperature might be the key factor that affects the germination of the micro-propagules because the other environmental factors varied only slightly according to previous studies. This study was designed to investigate the effects of temperature on the germination of micro-propagules via laboratory experiments. The results showed the following: (1) five types of green algae micro-propagules, including U. prolifera, U. linza, U. compressa, Ulva sp. (Clade 6) and Blidingia sp., were detected in the seawater samples collected from the Subei Shoal; (2) at 5 °C, germinated micro-propagules were not detected in any of the samples; at 10 °C, the micro-propagules began to germinate, and the germination quantity markedly changed between 10 °C and 30 °C; (3) the germination numbers of U. prolifera, U. linza, Ulva sp. (Clade 6) and Blidingia sp. were maximized at 15 °C, 10 °C, 25 °C and 20 °C, respectively. This study indicated that the sea temperature played a significant role in the germination of green algae micro-propagules in water and could partly explain the community succession phenomenon of the attached green algae in the Subei Shoal.

  17. The genome and phenome of the green alga Chloroidium sp. UTEX 3007 reveal adaptive traits for desert acclimatization

    PubMed Central

    Nelson, David R; Khraiwesh, Basel; Fu, Weiqi; Alseekh, Saleh; Jaiswal, Ashish; Chaiboonchoe, Amphun; Hazzouri, Khaled M; O’Connor, Matthew J; Butterfoss, Glenn L; Drou, Nizar; Rowe, Jillian D; Harb, Jamil; Fernie, Alisdair R; Gunsalus, Kristin C; Salehi-Ashtiani, Kourosh

    2017-01-01

    To investigate the phenomic and genomic traits that allow green algae to survive in deserts, we characterized a ubiquitous species, Chloroidium sp. UTEX 3007, which we isolated from multiple locations in the United Arab Emirates (UAE). Metabolomic analyses of Chloroidium sp. UTEX 3007 indicated that the alga accumulates a broad range of carbon sources, including several desiccation tolerance-promoting sugars and unusually large stores of palmitate. Growth assays revealed capacities to grow in salinities from zero to 60 g/L and to grow heterotrophically on >40 distinct carbon sources. Assembly and annotation of genomic reads yielded a 52.5 Mbp genome with 8153 functionally annotated genes. Comparison with other sequenced green algae revealed unique protein families involved in osmotic stress tolerance and saccharide metabolism that support phenomic studies. Our results reveal the robust and flexible biology utilized by a green alga to successfully inhabit a desert coastline. DOI: http://dx.doi.org/10.7554/eLife.25783.001 PMID:28623667

  18. Distinctive Architecture of the Chloroplast Genome in the Chlorodendrophycean Green Algae Scherffelia dubia and Tetraselmis sp. CCMP 881

    PubMed Central

    Turmel, Monique; de Cambiaire, Jean-Charles; Otis, Christian; Lemieux, Claude

    2016-01-01

    The Chlorodendrophyceae is a small class of green algae belonging to the core Chlorophyta, an assemblage that also comprises the Pedinophyceae, Trebouxiophyceae, Ulvophyceae and Chlorophyceae. Here we describe for the first time the chloroplast genomes of chlorodendrophycean algae (Scherffelia dubia, 137,161 bp; Tetraselmis sp. CCMP 881, 100,264 bp). Characterized by a very small single-copy (SSC) region devoid of any gene and an unusually large inverted repeat (IR), the quadripartite structures of the Scherffelia and Tetraselmis genomes are unique among all core chlorophytes examined thus far. The lack of genes in the SSC region is offset by the rich and atypical gene complement of the IR, which includes genes from the SSC and large single-copy regions of prasinophyte and streptophyte chloroplast genomes having retained an ancestral quadripartite structure. Remarkably, seven of the atypical IR-encoded genes have also been observed in the IRs of pedinophycean and trebouxiophycean chloroplast genomes, suggesting that they were already present in the IR of the common ancestor of all core chlorophytes. Considering that the relationships among the main lineages of the core Chlorophyta are still unresolved, we evaluated the impact of including the Chlorodendrophyceae in chloroplast phylogenomic analyses. The trees we inferred using data sets of 79 and 108 genes from 71 chlorophytes indicate that the Chlorodendrophyceae is a deep-diverging lineage of the core Chlorophyta, although the placement of this class relative to the Pedinophyceae remains ambiguous. Interestingly, some of our phylogenomic trees together with our comparative analysis of gene order data support the monophyly of the Trebouxiophyceae, thus offering further evidence that the previously observed affiliation between the Chlorellales and Pedinophyceae is the result of systematic errors in phylogenetic reconstruction. PMID:26849226

  19. Distinctive Architecture of the Chloroplast Genome in the Chlorodendrophycean Green Algae Scherffelia dubia and Tetraselmis sp. CCMP 881.

    PubMed

    Turmel, Monique; de Cambiaire, Jean-Charles; Otis, Christian; Lemieux, Claude

    2016-01-01

    The Chlorodendrophyceae is a small class of green algae belonging to the core Chlorophyta, an assemblage that also comprises the Pedinophyceae, Trebouxiophyceae, Ulvophyceae and Chlorophyceae. Here we describe for the first time the chloroplast genomes of chlorodendrophycean algae (Scherffelia dubia, 137,161 bp; Tetraselmis sp. CCMP 881, 100,264 bp). Characterized by a very small single-copy (SSC) region devoid of any gene and an unusually large inverted repeat (IR), the quadripartite structures of the Scherffelia and Tetraselmis genomes are unique among all core chlorophytes examined thus far. The lack of genes in the SSC region is offset by the rich and atypical gene complement of the IR, which includes genes from the SSC and large single-copy regions of prasinophyte and streptophyte chloroplast genomes having retained an ancestral quadripartite structure. Remarkably, seven of the atypical IR-encoded genes have also been observed in the IRs of pedinophycean and trebouxiophycean chloroplast genomes, suggesting that they were already present in the IR of the common ancestor of all core chlorophytes. Considering that the relationships among the main lineages of the core Chlorophyta are still unresolved, we evaluated the impact of including the Chlorodendrophyceae in chloroplast phylogenomic analyses. The trees we inferred using data sets of 79 and 108 genes from 71 chlorophytes indicate that the Chlorodendrophyceae is a deep-diverging lineage of the core Chlorophyta, although the placement of this class relative to the Pedinophyceae remains ambiguous. Interestingly, some of our phylogenomic trees together with our comparative analysis of gene order data support the monophyly of the Trebouxiophyceae, thus offering further evidence that the previously observed affiliation between the Chlorellales and Pedinophyceae is the result of systematic errors in phylogenetic reconstruction.

  20. Environmental monitoring of heavy metals in Bulgarian Black Sea green algae.

    PubMed

    Strezov, Alexander; Nonova, Tzvetana

    2005-06-01

    Fe, Mn, Cu, Pb and Cd concentration distribution in six green macroalgae species from the Bulgarian Black Sea coast were determined. The measurement of these metals was carried out during six seasons from 1996 to 2002 using atomic absorption spectrometry (AAS). Samples were collected from eight different sites-Shabla, Kaliakra, Tuzlata, Ravda, Ahtopol and Sinemoretz. The obtained heavy metal (HM) data (mean values microg/g) for all algae are: 650 +/- 100 for Fe, 184 +/- 15 for Mn, 5.6 +/- 0.5 for Cu, 3.3 +/- 0.3 for Pb and 1.1 +/- 0.2 for Cd. The obtained HM contents indicate that different species demonstrate various degree of metal accumulation and the obtained higher values in the northern sector of the studied zone can be attributed to the discharge influence of the big rivers, entering the Black Sea-Danube, Dnyepr, Dnester and local pollutant emissions. All data show that there is no serious contamination in green macroalgae with heavy and toxic metals along the whole Bulgarian Black Sea coast.

  1. Composition, uniqueness and variability of the epiphytic bacterial community of the green alga Ulva australis

    PubMed Central

    Burke, Catherine; Thomas, Torsten; Lewis, Matt; Steinberg, Peter; Kjelleberg, Staffan

    2011-01-01

    Green Ulvacean marine macroalgae are distributed worldwide in coastal tidal and subtidal ecosystems. As for many living surfaces in the marine environment, little is known concerning the epiphytic bacterial biofilm communities that inhabit algal surfaces. This study reports on the largest published libraries of near full-length 16S rRNA genes from a marine algal surface (5293 sequences from six samples) allowing for an in-depth assessment of the diversity and phylogenetic profile of the bacterial community on a green Ulvacean alga. Large 16S rRNA gene libraries of surrounding seawater were also used to determine the uniqueness of this bacterial community. The surface of Ulva australis is dominated by sequences of Alphaproteobacteria and the Bacteroidetes, especially within the Rhodobacteriaceae, Sphingomonadaceae, Flavobacteriaceae and Sapropiraceae families. Seawater libraries were also dominated by Alphaproteobacteria and Bacteroidetes sequences, but were shown to be clearly distinct from U. australis libraries through the clustering of sequences into operational taxonomic units and Bray–Curtis similarity analysis. Almost no similarity was observed between these two environments at the species level, and only minor similarity was observed at levels of sequence clustering representing clades of bacteria within family and genus taxonomic groups. Variability between libraries of U. australis was relatively high, and a consistent sub-population of bacterial species was not detected. The competitive lottery model, originally derived to explain diversity in coral reef fishes, may explain the pattern of colonization of this algal surface. PMID:21048801

  2. Unraveling the Photoprotective Response of Lichenized and Free-Living Green Algae (Trebouxiophyceae, Chlorophyta) to Photochilling Stress.

    PubMed

    Míguez, Fátima; Schiefelbein, Ulf; Karsten, Ulf; García-Plazaola, José I; Gustavs, Lydia

    2017-01-01

    Lichens and free-living terrestrial algae are widespread across many habitats and develop successfully in ecosystems where a cold winter limits survival. With the goal of comparing photoprotective responses in free-living and lichenized algae, the physiological responses to chilling and photochilling conditions were studied in three lichens and their isolated algal photobionts together as well as in a fourth free-living algal species. We specifically addressed the following questions: (i) Are there general patterns of acclimation in green algae under chilling and photochilling stresses? (ii) Do free-living algae exhibit a similar pattern of responses as their lichenized counterparts? (iii) Are these responses influenced by the selection pressure of environmental conditions or by the phylogenetic position of each species? To answer these questions, photosynthetic fluorescence measurements as well as pigment and low molecular weight carbohydrate pool analyses were performed under controlled laboratory conditions. In general, photochemical efficiency in all free-living algae decreased with increasing duration of the stress, while the majority of lichens maintained an unchanged photochemical activity. Nevertheless, these patterns cannot be generalized because the alga Trebouxia arboricola and the lichen Ramalina pollinaria (associated with Trebouxia photobionts) both showed a similar decrease in photochemical efficiency. In contrast, in the couple Elliptochloris bilobata-Baeomyces rufus, only the algal partner exhibited a broad physiological performance under stress. This study also highlights the importance of the xanthophyll cycle in response to the studied lichens and algae to photochilling stress, while the accumulation of sugars was not related to cold acclimation, except in the alga E. bilobata. The differences in response patterns detected among species can be mainly explained by their geographic origin, although the phylogenetic position should also be

  3. Unraveling the Photoprotective Response of Lichenized and Free-Living Green Algae (Trebouxiophyceae, Chlorophyta) to Photochilling Stress

    PubMed Central

    Míguez, Fátima; Schiefelbein, Ulf; Karsten, Ulf; García-Plazaola, José I.; Gustavs, Lydia

    2017-01-01

    Lichens and free-living terrestrial algae are widespread across many habitats and develop successfully in ecosystems where a cold winter limits survival. With the goal of comparing photoprotective responses in free-living and lichenized algae, the physiological responses to chilling and photochilling conditions were studied in three lichens and their isolated algal photobionts together as well as in a fourth free-living algal species. We specifically addressed the following questions: (i) Are there general patterns of acclimation in green algae under chilling and photochilling stresses? (ii) Do free-living algae exhibit a similar pattern of responses as their lichenized counterparts? (iii) Are these responses influenced by the selection pressure of environmental conditions or by the phylogenetic position of each species? To answer these questions, photosynthetic fluorescence measurements as well as pigment and low molecular weight carbohydrate pool analyses were performed under controlled laboratory conditions. In general, photochemical efficiency in all free-living algae decreased with increasing duration of the stress, while the majority of lichens maintained an unchanged photochemical activity. Nevertheless, these patterns cannot be generalized because the alga Trebouxia arboricola and the lichen Ramalina pollinaria (associated with Trebouxia photobionts) both showed a similar decrease in photochemical efficiency. In contrast, in the couple Elliptochloris bilobata-Baeomyces rufus, only the algal partner exhibited a broad physiological performance under stress. This study also highlights the importance of the xanthophyll cycle in response to the studied lichens and algae to photochilling stress, while the accumulation of sugars was not related to cold acclimation, except in the alga E. bilobata. The differences in response patterns detected among species can be mainly explained by their geographic origin, although the phylogenetic position should also be

  4. Natural synchronisation for the study of cell division in the green unicellular alga Ostreococcus tauri.

    PubMed

    Farinas, Benoît; Mary, Camille; de O Manes, Carmem-Lara; Bhaud, Yvonne; Peaucellier, Gérard; Moreau, Hervé

    2006-01-01

    Ostreococcus tauri (Prasinophyceae) is a marine unicellular green alga which diverged early in the green lineage. The interest of O. tauri as a potential model to study plant cell division is based on its key phylogenetic position, its simple binary division, a very simple cellular organisation and now the availability of the full genome sequence. In addition O. tauri has a minimal yet complete set of cell cycle control genes. Here we show that division can be naturally synchronised by light/dark cycles and that organelles divide before the nucleus. This natural synchronisation, although being only partial, enables the study of the expression of CDKs throughout the cell cycle. The expression patterns of OtCDKA and OtCDKB were determined both at the mRNA and protein levels. The single OtCDKA gene is constantly expressed throughout the cell cycle, whereas OtCDKB is highly regulated and expressed only in S/G2/M phases. More surprisingly, OtCDKA is not phosphorylated at the tyrosine residue, in contrast to OtCDKB which is strongly phosphorylated during cell division. OtCDKA kinase activity appears before the S phase, indicating a possible role of this protein in the G1/S transition. OtCDKB kinase activity occurs later than OtCDKA, and its tyrosine phosphorylation is correlated to G2/M, suggesting a possible control of the mitotic activity. To our knowledge this is the first organism in the green lineage which showed CDKB tyrosine phosphorylation during cell cycle progression.

  5. Screening and isolation of the algicidal compounds from marine green alga Ulva intestinalis

    NASA Astrophysics Data System (ADS)

    Sun, Xue; Jin, Haoliang; Zhang, Lin; Hu, Wei; Li, Yahe; Xu, Nianjun

    2016-07-01

    Twenty species of seaweed were collected from the coast of Zhejiang, China, extracted with ethanol, and screened for algicidal activity against red tide microalgae Heterosigma akashiwo and Prorocentrum micans. Inhibitory effects of fresh and dried tißsues of green alga Ulva intestinalis were assessed and the main algicidal compounds were isolated, purified, and identified. Five seaweed species, U. intestinalis, U. fasciata, Grateloupia romosissima, Chondria crassicaulis, and Gracilariopsis lemaneiformis, were investigated for their algicidal activities. Fresh tissues of 8.0 and 16.0 mg/mL of U. intestinalis dissolved in media significantly inhibited growth of H. akashiwo and P. micans, respectively. Dried tissue and ethyl acetate (EtOAc) extracts of U. intestinalis at greater than 1.2 and 0.04 mg/mL, respectively, were fatal to H. akashiwo, while its water and EtOAc extracts in excess of 0.96 and 0.32 mg/mL, respectively, were lethal to P. micans. Three algicidal compounds in the EtOAc extracts were identified as 15-ethoxy-(6z,9z,12z)-hexadecatrienoic acid (I), (6E,9E,12E)-(2-acetoxy- β-D-glucose)-octadecatrienoic acid ester (II) and hexadecanoic acid (III). Of these, compound II displayed the most potent algicidal activity with IC50 values of 4.9 and 14.1 µg/mL for H. akashiwo and P. micans, respectively. Compound I showed moderate algicidal activity with IC50 values of 13.4 and 24.7 µg/mL for H. akashiwo and P. micans, respectively. These findings suggested that certain macroalgae or products therefrom could be used as effective biological control agents against red tide algae.

  6. Anaerobic and aerobic hydrogen gas formation by the blue-green alga Anabaena cylindrica.

    PubMed

    Daday, A; Platz, R A; Smith, G D

    1977-11-01

    An investigation was made of certain factors involved in the formation of hydrogen gas, both in an anaerobic environment (argon) and in air, by the blue-green alga Anabaena cylindrica. The alga had not been previously adapted under hydrogen gas and hence the hydrogen evolution occurred entirely within the nitrogen-fixing heterocyst cells; organisms grown in a fixed nitrogen source, and which were therefore devoid of heterocysts, did not produce hydrogen under these conditions. Use of the inhibitor dichlorophenyl-dimethyl urea showed that hydrogen formation was directly dependent on photosystem I and only indirectly dependent on photosystem II, consistent with heterocysts being the site of hydrogen formation. The uncouplers carbonyl cyanide chlorophenyl hydrazone and dinitrophenol almost completely inhibited hydrogen formation, indicating that the process occurs almost entirely via the adenosine 5'-triphosphate-dependent nitrogenase. Salicylaldoxime also inhibited hydrogen formation, again illustrating the necessity of photophosphorylation. Whereas hydrogen formation could usually only be observed in anaerobic, dinitrogen-free environments, incubation in the presence of the dinitrogen-fixing inhibitor carbon monoxide plus the hydrogenase inhibitor acetylene resulted in significant formation of hydrogen even in air. Hydrogen formation was studied in batch cultures as a function of age of the cultures and also as a function of culture concentration, in both cases the cultures being harvested in logarithmic growth. Hydrogen evolution (and acetylene-reducing activity) exhibited a distinct maximum with respect to the age of the cultures. Finally, the levels of the protective enzyme, superoxide dismutase, were measured in heterocyst and vegetative cell fractions of the organism; the level was twice as high in heterocyst cells (2.3 units/mg of protein) as in vegetative cells (1.1 units/mg of protein). A simple procedure for isolating heterocyst cells is described.

  7. An extended corona attached to metaphase kinetochores of the green alga Oedogonium.

    PubMed

    Pickett-Heaps, J D; Carpenter, J

    1993-04-01

    Mitotic cells of the green alga Oedogonium were treated with the anti-microtubule agent oryzalin (1.0-0.1 microM) for 5 to 10 min. Within 5 min treatment of living cells, metaphase spindles became spherical with disorganized chromosomes, and anaphase spindles collapsed. At lower concentrations, the effects were slower, and partial recovery was observed about 10 to 20 min after the drug was washed out. Following breakdown of the spindle, considerable disorganized activity detected by time-lapse continued within the nucleus, isolated from the cytoplasm by its intact nuclear membrane. Under the electron microscope, spindle microtubules (MTs) were absent in oryzalin-treated cells. Paired metaphase kinetochores displayed an array of fine filamentous material extended, usually straight, about 3 microns into the nucleoplasm. In cells recovering from oryzalin treatment, MTs became associated with kinetochores in the usual manner. However, this filamentous array, the "extended corona" (EC), was almost undetectable, even when the MTs were short and poorly organized. The EC is appreciably larger by metaphase than the corona of prophase chromosomes and so it may assemble during early mitosis. Fine filaments interspersed with kinetochore MTs have been described in carefully fixed cells of this alga (M.J. Schibler, J.D. Pickett-Heaps, Eur. J. Cell Biol. 22, 687-698 (1980)). The EC apparently represents a less organized form of this material remaining after its scaffold of MTs has been removed. These fibers appear involved in MT capture upon spindle recovery from anti-MT drugs. They could function during prometaphase and even anaphase movement along spindle MTs.

  8. Effect of scenedesmus acuminatus green algae extracts on the development of Candida lipolytic yeast in gas condensate-containing media

    NASA Technical Reports Server (NTRS)

    Bilmes, B. I.; Kasymova, G. A.; Runov, V. I.; Karavayeva, N. N.

    1980-01-01

    Data are given of a comparative study of the growth and development as well as the characteristics of the biomass of the C. Lipolytica yeast according to the content of raw protein, protein, lipids, vitamins in the B group, and residual hydrocarbons during growth in media with de-aromatized gas-condensate FNZ as the carbon source with aqueous and alcohol extracts of S. acuminatus as the biostimulants. It is shown that the decoction and aqueous extract of green algae has the most intensive stimulating effect on the yeast growth. When a decoction of algae is added to the medium, the content of residual hydrocarbons in the biomass of C. lipolytica yeast is reduced by 4%; the quantity of protein, lipids, thamine and inositol with replacement of the yeast autolysate by the decoction of algae is altered little.

  9. Acute toxicities of pharmaceuticals toward green algae. mode of action, biopharmaceutical drug disposition classification system and quantile regression models.

    PubMed

    Villain, Jonathan; Minguez, Laetitia; Halm-Lemeille, Marie-Pierre; Durrieu, Gilles; Bureau, Ronan

    2016-02-01

    The acute toxicities of 36 pharmaceuticals towards green algae were estimated from a set of quantile regression models representing the first global quantitative structure-activity relationships. The selection of these pharmaceuticals was based on their predicted environmental concentrations. An agreement between the estimated values and the observed acute toxicity values was found for several families of pharmaceuticals, in particular, for antidepressants. A recent classification (BDDCS) of drugs based on ADME properties (Absorption, Distribution, Metabolism and Excretion) was clearly correlated with the acute ecotoxicities towards algae. Over-estimation of toxicity from our QSAR models was observed for classes 2, 3 and 4 whereas our model results were in agreement for the class 1 pharmaceuticals. Clarithromycin, a class 3 antibiotic characterized by weak metabolism and high solubility, was the most toxic to algae (molecular stability and presence in surface water). Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Silver nanoparticles as a control agent against facades coated by aerial algae-A model study of Apatococcus lobatus (green algae).

    PubMed

    Nowicka-Krawczyk, Paulina; Żelazna-Wieczorek, Joanna; Koźlecki, Tomasz

    2017-01-01

    Aerial algae are an important biological factor causing the biodegradation of building materials and facades. Conservation procedures aimed at the protection of historic and utility materials must be properly designed to avoid an increase of the degradation rate. The aim of the present study was to investigate the effect of silver nanoparticles (AgNP) synthetized with features contributing to the accessibility and toxicity (spherical shape, small size) on the most frequently occurring species of green algae in aerial biofilms and thus, the most common biodegradation factor-Apatococcus lobatus. Changes in the chloroplasts structure and the photosynthetic activity of the cells under AgNP exposure were made using confocal laser microscopy and digital image analysis and the estimation of growth inhibition rate was made using a biomass assay. In the majority of cases, treatment with AgNP caused a time and dose dependant degradation of chloroplasts and decrease in the photosynthetic activity of cells leading to the inhibition of aerial algae growth. However, some cases revealed an adaptive response of the cells. The response was induced by either a too low, or-after a short time-too high concentration of AgNP. Taken together, the data suggest that AgNP may be used as a biocide against aerial algal coatings; however, with a proper caution related to the concentration of the nanoparticles.

  11. Glycosyltransferase Family 43 Is Also Found in Early Eukaryotes and Has Three Subfamilies in Charophycean Green Algae

    PubMed Central

    Taujale, Rahil; Yin, Yanbin

    2015-01-01

    The glycosyltransferase family 43 (GT43) has been suggested to be involved in the synthesis of xylans in plant cell walls and proteoglycans in animals. Very recently GT43 family was also found in Charophycean green algae (CGA), the closest relatives of extant land plants. Here we present evidence that non-plant and non-animal early eukaryotes such as fungi, Haptophyceae, Choanoflagellida, Ichthyosporea and Haptophyceae also have GT43-like genes, which are phylogenetically close to animal GT43 genes. By mining RNA sequencing data (RNA-Seq) of selected plants, we showed that CGA have evolved three major groups of GT43 genes, one orthologous to IRX14 (IRREGULAR XYLEM14), one orthologous to IRX9/IRX9L and the third one ancestral to all land plant GT43 genes. We confirmed that land plant GT43 has two major clades A and B, while in angiosperms, clade A further evolved into three subclades and the expression and motif pattern of A3 (containing IRX9) are fairly different from the other two clades likely due to rapid evolution. Our in-depth sequence analysis contributed to our overall understanding of the early evolution of GT43 family and could serve as an example for the study of other plant cell wall-related enzyme families. PMID:26023931

  12. Glycosyltransferase family 43 is also found in early eukaryotes and has three subfamilies in Charophycean green algae.

    PubMed

    Taujale, Rahil; Yin, Yanbin

    2015-01-01

    The glycosyltransferase family 43 (GT43) has been suggested to be involved in the synthesis of xylans in plant cell walls and proteoglycans in animals. Very recently GT43 family was also found in Charophycean green algae (CGA), the closest relatives of extant land plants. Here we present evidence that non-plant and non-animal early eukaryotes such as fungi, Haptophyceae, Choanoflagellida, Ichthyosporea and Haptophyceae also have GT43-like genes, which are phylogenetically close to animal GT43 genes. By mining RNA sequencing data (RNA-Seq) of selected plants, we showed that CGA have evolved three major groups of GT43 genes, one orthologous to IRX14 (IRREGULAR XYLEM14), one orthologous to IRX9/IRX9L and the third one ancestral to all land plant GT43 genes. We confirmed that land plant GT43 has two major clades A and B, while in angiosperms, clade A further evolved into three subclades and the expression and motif pattern of A3 (containing IRX9) are fairly different from the other two clades likely due to rapid evolution. Our in-depth sequence analysis contributed to our overall understanding of the early evolution of GT43 family and could serve as an example for the study of other plant cell wall-related enzyme families.

  13. [Peculiarities of growth of the monocellular green algae culture after the influence of electromagnetic field in deuterated water-containing media].

    PubMed

    Semenov, K T; Aslanian, R R

    2013-01-01

    Exposing the inoculum of monocellular green algae Dunalialla tertiolecta and Tetraselmis viridis to 50 Hz electromagnetic field for several hours resulted in a reduced growth rate in both cultures. It was ascertained that heavy water inhibited growth of algae Dunaliella tertiolecta. The light water activated growth of the culture in the exponential phase only.

  14. Complex phylogenetic distribution of a non-canonical genetic code in green algae

    PubMed Central

    2010-01-01

    Background A non-canonical nuclear genetic code, in which TAG and TAA have been reassigned from stop codons to glutamine, has evolved independently in several eukaryotic lineages, including the ulvophycean green algal orders Dasycladales and Cladophorales. To study the phylogenetic distribution of the standard and non-canonical genetic codes, we generated sequence data of a representative set of ulvophycean green algae and used a robust green algal phylogeny to evaluate different evolutionary scenarios that may account for the origin of the non-canonical code. Results This study demonstrates that the Dasycladales and Cladophorales share this alternative genetic code with the related order Trentepohliales and the genus Blastophysa, but not with the Bryopsidales, which is sister to the Dasycladales. This complex phylogenetic distribution whereby all but one representative of a single natural lineage possesses an identical deviant genetic code is unique. Conclusions We compare different evolutionary scenarios for the complex phylogenetic distribution of this non-canonical genetic code. A single transition to the non-canonical code followed by a reversal to the canonical code in the Bryopsidales is highly improbable due to the profound genetic changes that coincide with codon reassignment. Multiple independent gains of the non-canonical code, as hypothesized for ciliates, are also unlikely because the same deviant code has evolved in all lineages. Instead we favor a stepwise acquisition model, congruent with the ambiguous intermediate model, whereby the non-canonical code observed in these green algal orders has a single origin. We suggest that the final steps from an ambiguous intermediate situation to a non-canonical code have been completed in the Trentepohliales, Dasycladales, Cladophorales and Blastophysa but not in the Bryopsidales. We hypothesize that in the latter lineage an initial stage characterized by translational ambiguity was not followed by final

  15. Culture observation and molecular phylogenetic analysis on the blooming green alga Chaetomorpha valida (Cladophorales, Chlorophyta) from China

    NASA Astrophysics Data System (ADS)

    Deng, Yunyan; Tang, Xiaorong; Zhan, Zifeng; Teng, Linhong; Ding, Lanping; Huang, Bingxin

    2013-05-01

    The marine green alga Chaetomorpha valida fouls aquaculture ponds along the coastal cities of Dalian and Rongcheng, China. Unialgal cultures were observed under a microscope to determine the developmental morphological characters of C. valida. Results reveal that gametophytic filaments often produce lateral branches under laboratory culture conditions, suggesting an atypical heteromorphic life cycle of C. valida between unbranched sporophytes and branched gametophytes, which differs from typical isomorphic alternation of Chaetomorpha species. The shape of the basal attachment cell, an important taxonomic character within the genus, was found variable depending on environmental conditions. The 18S rDNA and 28S rDNA regions were used to explore the phylogenetic affinity of the taxa. Inferred trees from 18S rDNA sequences revealed a close relationship between C. valida and Chaetomorpha moniligera. These results would enrich information in general biology and morphological plasticity of C. valida and provided a basis for future identification of green tide forming algae.

  16. Nucleotide diversity of the colorless green alga Polytomella parva (Chlorophyceae, Chlorophyta): high for the mitochondrial telomeres, surprisingly low everywhere else.

    PubMed

    Smith, David Roy; Lee, Robert W

    2011-01-01

    Silent-site nucleotide diversity data (π(silent)) can provide insights into the forces driving genome evolution. Here we present π(silent) statistics for the mitochondrial and nuclear DNAs of Polytomella parva, a nonphotosynthetic green alga with a highly reduced, linear fragmented mitochondrial genome. We show that this species harbors very little genetic diversity, with the exception of the mitochondrial telomeres, which have an excess of polymorphic sites. These data are compared with previously published π(silent) values from the mitochondrial and nuclear genomes of the model species Chlamydomonas reinhardtii and Volvox carteri, which are close relatives of P. parva, and are used to understand the modes and tempos of genome evolution within green algae.

  17. Metabolic regulation of triacylglycerol accumulation in the green algae: identification of potential targets for engineering to improve oil yield.

    PubMed

    Goncalves, Elton C; Wilkie, Ann C; Kirst, Matias; Rathinasabapathi, Bala

    2016-08-01

    The great need for more sustainable alternatives to fossil fuels has increased our research interests in algal biofuels. Microalgal cells, characterized by high photosynthetic efficiency and rapid cell division, are an excellent source of neutral lipids as potential fuel stocks. Various stress factors, especially nutrient-starvation conditions, induce an increased formation of lipid bodies filled with triacylglycerol in these cells. Here we review our knowledge base on glycerolipid synthesis in the green algae with an emphasis on recent studies on carbon flux, redistribution of lipids under nutrient-limiting conditions and its regulation. We discuss the contributions and limitations of classical and novel approaches used to elucidate the algal triacylglycerol biosynthetic pathway and its regulatory network in green algae. Also discussed are gaps in knowledge and suggestions for much needed research both on the biology of triacylglycerol accumulation and possible avenues to engineer improved algal strains.

  18. Influence of extracellular polysaccharides (EPS) produced by two different green unicellular algae on membrane filtration in an algae-based biofuel production process.

    PubMed

    Matsumoto, Takaki; Yamamura, Hiroshi; Hayakawa, Jyunpei; Watanabe, Yoshimasa; Harayama, Shigeaki

    2014-01-01

    In the present study, two strains of green algae named S1 and S2, categorized as the same species of Pseudo-coccomyxa ellipsoidea but showing 99% homology, were cultivated under the same conditions and filtrated with a microfiltration membrane. On the basis of the results of the extracellular polysaccharides (EPS) characteristics of these two green algae and the degree of fouling, the influence of these characteristics on the performance of membrane filtration was investigated. There was no difference in the specific growth rate between the S1 and S2 strains; however, large differences were seen in the amount and quality of EPS between S1 and S2. When the S1 and S2 strains were filtered with a membrane, the trend in the increase in transmembrane pressure (TMP) was quite different. The filtration of the S1 strain showed a rapid increase in TMP, whereas the TMP of the filtration of the S2 strain did not increase at all during the operation. This clearly demonstrated that the characteristics of each strain affect the development of membrane fouling. On the basis of the detailed characterization of solved-EPS (s-EPS) and bound-EPS (b-EPS), it was clarified that s-EPS mainly contributed to irreversible fouling for both operations and the biopolymer-like organic matter contained in b-EPS mainly contributed to reversible fouling.

  19. Response of the green alga Oophila sp., a salamander endosymbiont, to a PSII-inhibitor under laboratory conditions.

    PubMed

    Baxter, Leilan; Brain, Richard; Rodriguez-Gil, Jose Luis; Hosmer, Alan; Solomon, Keith; Hanson, Mark

    2014-08-01

    In a rare example of autotroph-vertebrate endosymbiosis, eggs of the yellow-spotted salamander (Ambystoma maculatum) are colonized by a green alga (Oophila sp.) that significantly enhances salamander development. Previous studies have demonstrated the potential for impacts to the salamander embryo when growth of the algae is impaired by exposure to herbicides. To further investigate this relationship, the authors characterized the response of the symbiotic algae (Oophila sp.) alone to the photosystem II (PSII) inhibitor atrazine under controlled laboratory conditions. After extraction of the alga from A. maculatum eggs and optimization of culturing conditions, 4 toxicity assays (96 h each) were conducted. Recovery of the algal population was also assessed after a further 96 h in untreated media. Average median effective concentration (EC50) values of 123 µg L(-1) (PSII yield), 169 µg L(-1) (optical density), and 299 µg L(-1) (growth rate) were obtained after the 96-h exposure. Full recovery of exposed algal populations after 96 h in untreated media was observed for all endpoints, except for optical density at the greatest concentration tested (300 µg L(-1) ). Our results show that, under laboratory conditions, Oophila sp. is generally less sensitive to atrazine than standard test species. Although conditions of growth in standard toxicity tests are not identical to those in the natural environment, these results provide an understanding of the tolerance of this alga to PSII inhibitors as compared with other species. © 2014 SETAC.

  20. Visualization of nuclear localization of transcription factors with cyan and green fluorescent proteins in the red alga Porphyra yezoensis.

    PubMed

    Uji, Toshiki; Takahashi, Megumu; Saga, Naotsune; Mikami, Koji

    2010-04-01

    Transcription factors play a central role in expression of genomic information in all organisms. The objective of our study is to analyze the function of transcription factors in red algae. One way to analyze transcription factors in eukaryotic cells is to study their nuclear localization, as reported for land plants and green algae using fluorescent proteins. There is, however, no report documenting subcellular localization of transcription factors from red algae. In the present study, using the marine red alga Porphyra yezoensis, we confirmed for the first time successful expression of humanized fluorescent proteins (ZsGFP and ZsYFP) from a reef coral Zoanthus sp. and land plant-adapted sGFP(S65T) in gametophytic cells comparable to expression of AmCFP. Following molecular cloning and characterization of transcription factors DP-E2F-like 1 (PyDEL1), transcription elongation factor 1 (PyElf1) and multiprotein bridging factor 1 (PyMBF1), we then demonstrated that ZsGFP and AmCFP can be used to visualize nuclear localization of PyElf1 and PyMBF1. This is the first report to perform visualization of subcellular localization of transcription factors as genome-encoded proteins in red algae.

  1. Strategies for psbA gene expression in cyanobacteria, green algae and higher plants: from transcription to PSII repair.

    PubMed

    Mulo, Paula; Sakurai, Isamu; Aro, Eva-Mari

    2012-01-01

    The Photosystem (PS) II of cyanobacteria, green algae and higher plants is prone to light-induced inactivation, the D1 protein being the primary target of such damage. As a consequence, the D1 protein, encoded by the psbA gene, is degraded and re-synthesized in a multistep process called PSII repair cycle. In cyanobacteria, a small gene family codes for the various, functionally distinct D1 isoforms. In these organisms, the regulation of the psbA gene expression occurs mainly at the level of transcription, but the expression is fine-tuned by regulation of translation elongation. In plants and green algae, the D1 protein is encoded by a single psbA gene located in the chloroplast genome. In chloroplasts of Chlamydomonas reinhardtii the psbA gene expression is strongly regulated by mRNA processing, and particularly at the level of translation initiation. In chloroplasts of higher plants, translation elongation is the prevalent mechanism for regulation of the psbA gene expression. The pre-existing pool of psbA transcripts forms translation initiation complexes in plant chloroplasts even in darkness, while the D1 synthesis can be completed only in the light. Replacement of damaged D1 protein requires also the assistance by a number of auxiliary proteins, which are encoded by the nuclear genome in green algae and higher plants. Nevertheless, many of these chaperones are conserved between prokaryotes and eukaryotes. Here, we describe the specific features and fundamental differences of the psbA gene expression and the regeneration of the PSII reaction center protein D1 in cyanobacteria, green algae and higher plants. This article is part of a Special Issue entitled Photosystem II. © 2011 Elsevier B.V. All rights reserved.

  2. Purification and characterization of cytochrome f-556.5 from the blue-green alga Spirulina platensis.

    PubMed

    Böhme, H; Pelzer, B; Böger, P

    1980-10-03

    The membrane-bound cytochrome f-556.5 from the blue-green alga Spirulina platensis was purified to apparent homogeneity. Most of its properties are comparable to cytochrome f isolated from higher plants and green algae. It is clearly distinguishable from soluble cytochrome c-554, also present in Spirulina, which probably replaces the function of plastocyanin in photosynthetic electron transport. 1. The reduced form of cytochrome f exhibits an asymmetrical alpha-band with a maximum at 556.5 nm, and a pronounced shoulder at 550 nm. The beta-, gamma and delta-bands coincide with those described for Scenedesmus cytochrome f-553, with maxima at 524 (532), 422, 331 and a protein peak at 276 nm. The maximum of ferricytochrome f is at 410.5 nm; there is no indication of a weak 695 nm band, described for soluble c-type cytochromes. The purest preparations had a delta/protein-peak ratio of 0.8; the gamma/alpha ratio was 7.3. Formation of a pyridine hemochromogen with a maximum at 550 nm indicated a c-type cytochrome. The molar extinction coefficient at 556.5 nm is 30200, the differential extinction coefficient 21 500. 2. The molecular weight determined by gel filtration or SDS-polyacrylamide gel electrophoresis is 33 000 and 34 000, respectively. 3. The redox properties differ from those described for other cytochromes f isolated from green algae and higher plants: the midpoint redox potential is significantly more negative (+318 mV, pH 7.0) and from pH 6 to 10 no pH dependence is observed. 4. The isoelectric point was determined at pH 3.95, which is more acidic as compared to other cytochromes f. 5. Comparison of the amino acid composition indicated a distant relationship to higher plant cytochrome f and a closer relationship to cytochrome f from green algae.

  3. Isolation of a novel oil globule protein from the green alga Haematococcus pluvialis (Chlorophyceae).

    PubMed

    Peled, Ehud; Leu, Stefan; Zarka, Aliza; Weiss, Meira; Pick, Uri; Khozin-Goldberg, Inna; Boussiba, Sammy

    2011-09-01

    Cytoplasmic oil globules of Haematococcus pluvialis (Chlorophyceae) were isolated and analyzed for pigments, lipids and proteins. Astaxanthin appeared to be the only pigment deposited in the globules. Triacyglycerols were the main lipids (more than 90% of total fatty acids) in both the cell-free extract and in the oil globules. Lipid profile analysis of the oil globules showed that relative to the cell-free extract, they were enriched with extraplastidial lipids. A fatty acids profile revealed that the major fatty acids in the isolated globules were oleic acid (18:1) and linoleic acid (18:2). Protein extracts from the globules revealed seven enriched protein bands, all of which were possible globule-associated proteins. A major 33-kDa globule protein was partially sequenced by MS/MS analysis, and degenerate DNA primers were prepared and utilized to clone its encoding gene from cDNA extracted from cells grown in a nitrogen depleted medium under high light. The sequence of this 275-amino acid protein, termed the Haematococcus Oil Globule Protein (HOGP), revealed partial homology with a Chlamydomonas reinhardtii oil globule protein and with undefined proteins from other green algae. The HOGP transcript was barely detectable in vegetative cells, but its level increased by more than 100 fold within 12 h of exposure to nitrogen depletion/high light conditions, which induced oil accumulation. HOGP is the first oil-globule-associated protein to be identified in H. pluvialis, and it is a member of a novel gene family that may be unique to green microalgae.

  4. The nucleotide sequence of blue-green algae phenylalanine-tRNA and the evolutionary origin of chloroplasts.

    PubMed Central

    Hecker, L I; Barnett, W E; Lin, F K; Furr, T D; Heckman, J E; RajBhandary, U L; Chang, S H

    1982-01-01

    Phenylalanine tRNA from the blue-green alga, Agmenellum quadruplicatum, has been purified to homogeneity. The nucleotide sequence of this tRNA was determined to be: (see tests) Comparisons of the sequence and the modified nucleosides of this tRNA with those of other tRNAPhes thus far sequenced, indicate that this blue green algal tRNAPhe is typically prokaryotic and closely resembles the chloroplast tRNAPhes of higher plants and Euglena. The significance of this observation to the evolutionary origin of chloroplasts is discussed. Images PMID:6817301

  5. Heterotrimeric G-proteins in green algae. An early innovation in the evolution of the plant lineage.

    PubMed

    Hackenberg, Dieter; Pandey, Sona

    2014-01-01

    Heterotrimeric G-proteins (G-proteins, hereafter) are important signaling components in all eukaryotes. The absence of these proteins in the sequenced genomes of Chlorophycean green algae has raised questions about their evolutionary origin and prevalence in the plant lineage. The existence of G-proteins has often been correlated with the acquisition of embryophytic life-cycle and/or terrestrial habitats of plants which occurred around 450 million years ago. Our discovery of functional G-proteins in Chara braunii, a representative of the Charophycean green algae, establishes the existence of this conserved signaling pathway in the most basal plants and dates it even further back to 1-1.5 billion years ago. We have now identified the sequence homologs of G-proteins in additional algal families and propose that green algae represent a model system for one of the most basal forms of G-protein signaling known to exist to date. Given the possible differences that exist between plant and metazoan G-protein signaling mechanisms, such basal organisms will serve as important resources to trace the evolutionary origin of proposed mechanistic differences between the systems as well as their plant-specific functions.

  6. High Yields of Hydrogen Production Induced by Meta-Substituted Dichlorophenols Biodegradation from the Green Alga Scenedesmus obliquus

    PubMed Central

    Papazi, Aikaterini; Andronis, Efthimios; Ioannidis, Nikolaos E.; Chaniotakis, Nikolaos; Kotzabasis, Kiriakos

    2012-01-01

    Hydrogen is a highly promising energy source with important social and economic implications. The ability of green algae to produce photosynthetic hydrogen under anaerobic conditions has been known for years. However, until today the yield of production has been very low, limiting an industrial scale use. In the present paper, 73 years after the first report on H2-production from green algae, we present a combinational biological system where the biodegradation procedure of one meta-substituted dichlorophenol (m-dcp) is the key element for maintaining continuous and high rate H2-production (>100 times higher than previously reported) in chloroplasts and mitochondria of the green alga Scenedesmus obliquus. In particular, we report that reduced m-dcps (biodegradation intermediates) mimic endogenous electron and proton carriers in chloroplasts and mitochondria, inhibit Photosystem II (PSII) activity (and therefore O2 production) and enhance Photosystem I (PSI) and hydrogenase activity. In addition, we show that there are some indications for hydrogen production from sources other than chloroplasts in Scenedesmus obliquus. The regulation of these multistage and highly evolved redox pathways leads to high yields of hydrogen production and paves the way for an efficient application to industrial scale use, utilizing simple energy sources and one meta-substituted dichlorophenol as regulating elements. PMID:23145057

  7. Comparison of the Photosynthetic Yield of Cyanobacteria and Green Algae: Different Methods Give Different Answers.

    PubMed

    Schuurmans, R Milou; van Alphen, Pascal; Schuurmans, J Merijn; Matthijs, Hans C P; Hellingwerf, Klaas J

    2015-01-01

    The societal importance of renewable carbon-based commodities and energy carriers has elicited a particular interest for high performance phototrophic microorganisms. Selection of optimal strains is often based on direct comparison under laboratory conditions of maximal growth rate or additional valued features such as lipid content. Instead of reporting growth rate in culture, estimation of photosynthetic efficiency (quantum yield of PSII) by pulse-amplitude modulated (PAM) fluorimetry is an often applied alternative method. Here we compared the quantum yield of PSII and the photonic yield on biomass for the green alga Chlorella sorokiniana 211-8K and the cyanobacterium Synechocystis sp. PCC 6803. Our data demonstrate that the PAM technique inherently underestimates the photosynthetic efficiency of cyanobacteria by rendering a high F0 and a low FM, specifically after the commonly practiced dark pre-incubation before a yield measurement. Yet when comparing the calculated biomass yield on light in continuous culture experiments, we obtained nearly equal values for both species. Using mutants of Synechocystis sp. PCC 6803, we analyzed the factors that compromise its PAM-based quantum yield measurements. We will discuss the role of dark respiratory activity, fluorescence emission from the phycobilisomes, and the Mehler-like reaction. Based on the above observations we recommend that PAM measurements in cyanobacteria are interpreted only qualitatively.

  8. The family of DOF transcription factors: from green unicellular algae to vascular plants.

    PubMed

    Moreno-Risueno, Miguel Angel; Martínez, Manuel; Vicente-Carbajosa, Jesús; Carbonero, Pilar

    2007-04-01

    This article deals with the origin and evolution of the DOF transcription factor family through a phylogenetic analysis of those DOF sequences identified from a variety of representative organisms from different taxonomic groups: the green unicellular alga Chlamydomonas reinhardtii, the moss Physcomitrella patens, the fern Selaginella moellendorffii, the gymnosperm Pinus taeda, the dicotyledoneous Arabidopsis thaliana and the monocotyledoneous angiosperms Oryza sativa and Hordeum vulgare. In barley, we have identified 26 different DOF genes by sequence analyses of clones isolated from the screening of genomic libraries and of ESTs, whereas a single DOF gene was identified by bioinformatics searches in the Chlamydomonas genome. The phylogenetic analysis groups all these genes into six major clusters of orthologs originated from a primary basal grade. Our results suggest that duplications of an ancestral DOF, probably formed in the photosynthetic eukaryotic ancestor, followed by subsequent neo-, sub-functionalization and pseudogenization processes would have triggered the expansion of the DOF family. Loss, acquisition and shuffling of conserved motifs among the new DOFs likely underlie the mechanism of formation of the distinct subfamilies.

  9. Integration of carbon assimilation modes with photosynthetic light capture in the green alga Chlamydomonas reinhardtii.

    PubMed

    Berger, Hanna; Blifernez-Klassen, Olga; Ballottari, Matteo; Bassi, Roberto; Wobbe, Lutz; Kruse, Olaf

    2014-10-01

    The unicellular green alga Chlamydomonas reinhardtii is capable of using organic and inorganic carbon sources simultaneously, which requires the adjustment of photosynthetic activity to the prevailing mode of carbon assimilation. We obtained novel insights into the regulation of light-harvesting at photosystem II (PSII) following altered carbon source availability. In C. reinhardtii, synthesis of PSII-associated light-harvesting proteins (LHCBMs) is controlled by the cytosolic RNA-binding protein NAB1, which represses translation of particular LHCBM isoform transcripts. This mechanism is fine-tuned via regulation of the nuclear NAB1 promoter, which is activated when linear photosynthetic electron flow is restricted by CO(2)-limitation in a photoheterotrophic context. In the wild-type, accumulation of NAB1 reduces the functional PSII antenna size, thus preventing a harmful overexcited state of PSII, as observed in a NAB1-less mutant. We further demonstrate that translation control as a newly identified long-term response to prolonged CO(2)-limitation replaces LHCII state transitions as a fast response to PSII over-excitation. Intriguingly, activation of the long-term response is perturbed in state transition mutant stt7, suggesting a regulatory link between the long- and short-term response. We depict a regulatory circuit operating on distinct timescales and in different cellular compartments to fine-tune light-harvesting in photoheterotrophic eukaryotes.

  10. Characterization of Hydrogen Metabolism in the Multicellular Green Alga Volvox carteri.

    PubMed

    Cornish, Adam J; Green, Robin; Gärtner, Katrin; Mason, Saundra; Hegg, Eric L

    2015-01-01

    Hydrogen gas functions as a key component in the metabolism of a wide variety of microorganisms, often acting as either a fermentative end-product or an energy source. The number of organisms reported to utilize hydrogen continues to grow, contributing to and expanding our knowledge of biological hydrogen processes. Here we demonstrate that Volvox carteri f. nagariensis, a multicellular green alga with differentiated cells, evolves H2 both when supplied with an abiotic electron donor and under physiological conditions. The genome of Volvox carteri contains two genes encoding putative [FeFe]-hydrogenases (HYDA1 and HYDA2), and the transcripts for these genes accumulate under anaerobic conditions. The HYDA1 and HYDA2 gene products were cloned, expressed, and purified, and both are functional [FeFe]-hydrogenases. Additionally, within the genome the HYDA1 and HYDA2 genes cluster with two putative genes which encode hydrogenase maturation proteins. This gene cluster resembles operon-like structures found within bacterial genomes and may provide further insight into evolutionary relationships between bacterial and algal [FeFe]-hydrogenase genes.

  11. Simultaneous cryo X-ray ptychographic and fluorescence microscopy of green algae.

    PubMed

    Deng, Junjing; Vine, David J; Chen, Si; Nashed, Youssef S G; Jin, Qiaoling; Phillips, Nicholas W; Peterka, Tom; Ross, Rob; Vogt, Stefan; Jacobsen, Chris J

    2015-02-24

    Trace metals play important roles in normal and in disease-causing biological functions. X-ray fluorescence microscopy reveals trace elements with no dependence on binding affinities (unlike with visible light fluorophores) and with improved sensitivity relative to electron probes. However, X-ray fluorescence is not very sensitive for showing the light elements that comprise the majority of cellular material. Here we show that X-ray ptychography can be combined with fluorescence to image both cellular structure and trace element distribution in frozen-hydrated cells at cryogenic temperatures, with high structural and chemical fidelity. Ptychographic reconstruction algorithms deliver phase and absorption contrast images at a resolution beyond that of the illuminating lens or beam size. Using 5.2-keV X-rays, we have obtained sub-30-nm resolution structural images and ∼90-nm-resolution fluorescence images of several elements in frozen-hydrated green algae. This combined approach offers a way to study the role of trace elements in their structural context.

  12. Comparison of the Photosynthetic Yield of Cyanobacteria and Green Algae: Different Methods Give Different Answers

    PubMed Central

    Schuurmans, R. Milou; van Alphen, Pascal; Schuurmans, J. Merijn; Matthijs, Hans C. P.; Hellingwerf, Klaas J.

    2015-01-01

    The societal importance of renewable carbon-based commodities and energy carriers has elicited a particular interest for high performance phototrophic microorganisms. Selection of optimal strains is often based on direct comparison under laboratory conditions of maximal growth rate or additional valued features such as lipid content. Instead of reporting growth rate in culture, estimation of photosynthetic efficiency (quantum yield of PSII) by pulse-amplitude modulated (PAM) fluorimetry is an often applied alternative method. Here we compared the quantum yield of PSII and the photonic yield on biomass for the green alga Chlorella sorokiniana 211-8K and the cyanobacterium Synechocystis sp. PCC 6803. Our data demonstrate that the PAM technique inherently underestimates the photosynthetic efficiency of cyanobacteria by rendering a high F0 and a low FM, specifically after the commonly practiced dark pre-incubation before a yield measurement. Yet when comparing the calculated biomass yield on light in continuous culture experiments, we obtained nearly equal values for both species. Using mutants of Synechocystis sp. PCC 6803, we analyzed the factors that compromise its PAM-based quantum yield measurements. We will discuss the role of dark respiratory activity, fluorescence emission from the phycobilisomes, and the Mehler-like reaction. Based on the above observations we recommend that PAM measurements in cyanobacteria are interpreted only qualitatively. PMID:26394153

  13. Respiratory-deficient mutants of the unicellular green alga Chlamydomonas: a review.

    PubMed

    Salinas, Thalia; Larosa, Véronique; Cardol, Pierre; Maréchal-Drouard, Laurence; Remacle, Claire

    2014-05-01

    Genetic manipulation of the unicellular green alga Chlamydomonas reinhardtii is straightforward. Nuclear genes can be interrupted by insertional mutagenesis or targeted by RNA interference whereas random or site-directed mutagenesis allows the introduction of mutations in the mitochondrial genome. This, combined with a screen that easily allows discriminating respiratory-deficient mutants, makes Chlamydomonas a model system of choice to study mitochondria biology in photosynthetic organisms. Since the first description of Chlamydomonas respiratory-deficient mutants in 1977 by random mutagenesis, many other mutants affected in mitochondrial components have been characterized. These respiratory-deficient mutants increased our knowledge on function and assembly of the respiratory enzyme complexes. More recently some of these mutants allowed the study of mitochondrial gene expression processes poorly understood in Chlamydomonas. In this review, we update the data concerning the respiratory components with a special focus on the assembly factors identified on other organisms. In addition, we make an inventory of different mitochondrial respiratory mutants that are inactivated either on mitochondrial or nuclear genes.

  14. Active hydrocarbon biosynthesis and accumulation in a green alga, Botryococcus braunii (race A).

    PubMed

    Hirose, Mana; Mukaida, Fukiko; Okada, Sigeru; Noguchi, Tetsuko

    2013-08-01

    Among oleaginous microalgae, the colonial green alga Botryococcus braunii accumulates especially large quantities of hydrocarbons. This accumulation may be achieved more by storage of lipids in the extracellular space rather than in the cytoplasm, as is the case for all other examined oleaginous microalgae. The stage of hydrocarbon synthesis during the cell cycle was determined by autoradiography. The cell cycle of B. braunii race A was synchronized by aminouracil treatment, and cells were taken at various stages in the cell cycle and cultured in a medium containing [(14)C]acetate. Incorporation of (14)C into hydrocarbons was detected. The highest labeling occurred just after septum formation, when it was about 2.6 times the rate during interphase. Fluorescent and electron microscopy revealed that new lipid accumulation on the cell surface occurred during at least two different growth stages and sites of cells. Lipid bodies in the cytoplasm were not prominent in interphase cells. These lipid bodies then increased in number, size, and inclusions, reaching maximum values just before the first lipid accumulation on the cell surface at the cell apex. Most of them disappeared from the cytoplasm concomitant with the second new accumulation at the basolateral region, where extracellular lipids continuously accumulated. The rough endoplasmic reticulum near the plasma membrane is prominent in B. braunii, and the endoplasmic reticulum was often in contact with both a chloroplast and lipid bodies in cells with increasing numbers of lipid bodies. We discuss the transport pathway of precursors of extracellular hydrocarbons in race A.

  15. Characterization of Hydrogen Metabolism in the Multicellular Green Alga Volvox carteri

    SciTech Connect

    Cornish, Adam J.; Green, Robin; Gärtner, Katrin; Mason, Saundra; Hegg, Eric L.

    2015-04-30

    Hydrogen gas functions as a key component in the metabolism of a wide variety of microorganisms, often acting as either a fermentative end-product or an energy source. The number of organisms reported to utilize hydrogen continues to grow, contributing to and expanding our knowledge of biological hydrogen processes. Here we demonstrate that Volvox carteri f. nagariensis, a multicellular green alga with differentiated cells, evolves H2 both when supplied with an abiotic electron donor and under physiological conditions. The genome of Volvox carteri contains two genes encoding putative [FeFe]-hydrogenases (HYDA1 and HYDA2), and the transcripts for these genes accumulate under anaerobic conditions. The HYDA1 and HYDA2 gene products were cloned, expressed, and purified, and both are functional [FeFe]-hydrogenases. Additionally, within the genome the HYDA1 and HYDA2 genes cluster with two putative genes which encode hydrogenase maturation proteins. This gene cluster resembles operon-like structures found within bacterial genomes and may provide further insight into evolutionary relationships between bacterial and algal [FeFe]-hydrogenase genes.

  16. Characterization of Hydrogen Metabolism in the Multicellular Green Alga Volvox carteri

    DOE PAGES

    Cornish, Adam J.; Green, Robin; Gärtner, Katrin; ...

    2015-04-30

    Hydrogen gas functions as a key component in the metabolism of a wide variety of microorganisms, often acting as either a fermentative end-product or an energy source. The number of organisms reported to utilize hydrogen continues to grow, contributing to and expanding our knowledge of biological hydrogen processes. Here we demonstrate that Volvox carteri f. nagariensis, a multicellular green alga with differentiated cells, evolves H2 both when supplied with an abiotic electron donor and under physiological conditions. The genome of Volvox carteri contains two genes encoding putative [FeFe]-hydrogenases (HYDA1 and HYDA2), and the transcripts for these genes accumulate under anaerobicmore » conditions. The HYDA1 and HYDA2 gene products were cloned, expressed, and purified, and both are functional [FeFe]-hydrogenases. Additionally, within the genome the HYDA1 and HYDA2 genes cluster with two putative genes which encode hydrogenase maturation proteins. This gene cluster resembles operon-like structures found within bacterial genomes and may provide further insight into evolutionary relationships between bacterial and algal [FeFe]-hydrogenase genes.« less

  17. A novel alphaproteobacterial ectosymbiont promotes the growth of the hydrocarbon-rich green alga Botryococcus braunii

    PubMed Central

    Tanabe, Yuuhiko; Okazaki, Yusuke; Yoshida, Masaki; Matsuura, Hiroshi; Kai, Atsushi; Shiratori, Takashi; Ishida, Ken-ichiro; Nakano, Shin-ichi; Watanabe, Makoto M.

    2015-01-01

    Botryococcus braunii is a colony-forming green alga that accumulates large amounts of liquid hydrocarbons within the colony. The utilization of B. braunii for biofuel production is however hindered by its low biomass productivity. Here we describe a novel bacterial ectosymbiont (BOTRYCO-2) that confers higher biomass productivity to B. braunii. 16S rDNA analysis indicated that the sequence of BOTRYCO-2 shows low similarity (<90%) to cultured bacterial species and located BOTRYCO-2 within a phylogenetic lineage consisting of uncultured alphaproteobacterial clones. Fluorescence in situ hybridization (FISH) studies and transmission electric microscopy indicated that BOTRYCO-2 is closely associated with B. braunii colonies. Interestingly, FISH analysis of a water bloom sample also found BOTRYCO-2 bacteria in close association with cyanobacterium Microcystis aeruginosa colonies, suggesting that BOTRYCO-2 relatives have high affinity to phytoplankton colonies. A PCR survey of algal bloom samples revealed that the BOTRYCO-2 lineage is commonly found in Microcystis associated blooms. Growth experiments indicated that B. braunii Ba10 can grow faster and has a higher biomass (1.8-fold) and hydrocarbon (1.5-fold) yield in the presence of BOTRYCO-2. Additionally, BOTRYCO-2 conferred a higher biomass yield to BOT-22, one of the fastest growing strains of B. braunii. We propose the species name ‘Candidatus Phycosocius bacilliformis’ for BOTRYCO-2. PMID:26130609

  18. Amylibacter ulvae sp. nov., a new alphaproteobacterium isolated from the Pacific green alga Ulva fenestrata.

    PubMed

    Nedashkovskaya, Olga I; Kukhlevskiy, Andrey D; Zhukova, Natalia V; Kim, Seung Bum

    2016-04-01

    A strictly aerobic, Gram-stain-negative, rod-shaped and non-motile bacterium, designated strain 6Alg 255(T), was isolated from the green alga Ulva fenestrata. Phylogenetic analysis based on 16S rRNA gene sequencing revealed that the novel strain affiliated to the family Rhodobacteraceae of the class Alphaproteobacteria being most closely related to Amylibacter marinus LMG 28364(T) with 16S rRNA gene sequence similarity of 97.2 %. Strain 6Alg 255(T) grew with 0.5-6.0 % NaCl and at 4-33 °C, hydrolysed aesculin, casein, gelatin and urea. The DNA G + C content was 50.4 mol%. The prevalent fatty acids were C18:1 ω7c and C16:0. The polar lipid profile was characterized by the presence of phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine and unidentified aminolipid. The major respiratory quinone was Q-10. The significant molecular distinctiveness between the novel isolate and its nearest neighbour was strongly supported by the differences in physiological and biochemical tests. Therefore, strain 6Alg 255(T) represents a novel species of the genus Amylibacter, for which the name Amylibacter ulvae sp. nov. is proposed. The type strain is 6Alg 255(T) (=KCTC 32465(T) = KMM 6515(T)).

  19. Cloning and characterization of d-threonine aldolase from the green alga Chlamydomonas reinhardtii.

    PubMed

    Hirato, Yuki; Tokuhisa, Mayumi; Tanigawa, Minoru; Ashida, Hiroyuki; Tanaka, Hiroyuki; Nishimura, Katsushi

    2017-03-01

    d-Threonine aldolase (DTA) catalyzes the pyridoxal 5'-phosphate (PLP)-dependent interconversion of d-threonine and glycine plus acetaldehyde. The enzyme is a powerful tool for the stereospecific synthesis of various β-hydroxy amino acids in synthetic organic chemistry. In this study, DTA from the green alga Chlamydomonas reinhardtii was discovered and characterized, representing the first report to describe the existence of eukaryotic DTA. DTA was overexpressed in recombinant Escherichia coli BL21 (DE3) cells; the specific activity of the enzyme in the cell-free extract was 0.8 U/mg. The recombinant enzyme was purified to homogeneity by ammonium sulfate fractionation, DEAE-Sepharose, and Mono Q column chromatographies (purified enzyme 7.0 U/mg). For the cleavage reaction, the optimal temperature and pH were 70 °C and pH 8.4, respectively. The enzyme demonstrated 90% of residual activity at 50 °C for 1 h. The enzyme catalyzed the synthesis of d- and d-allo threonine from a mixture of glycine and acetaldehyde (the diastereomer excess of d-threonine was 18%). DTA was activated by several divalent metal ions, including manganese, and was inhibited by PLP enzyme inhibitors and metalloenzyme inhibitors. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Phototoxicity of benzo(a)pyrene in the green alga Selenastrum capricornutum

    SciTech Connect

    Cody, T.E.; Radike, M.J.; Warshawsky, D.

    1984-10-01

    The effects of selected polycyclic aromatic hydrocarbons (PAHs) on the growth of the green alga Selenastrum capricornutum in three light regimens were examined. In gold fluorescent light, benzo(a)pyrene (BaP) at 12 mg/liter (48 ..mu..mole/liter), benz(a)anthracene (BaA) at 40 mg/liter (175 ..mu..mole/liter), anthracene (A) at 40 mg/liter (224 ..mu..mole/liter), and 13 metabolites of BaP each at 40 ..mu..g/liter had no effect on algal growth. In cool-white fluorescent light, 30% inhibition of algal growth occurred with 0.1 ..mu..mole/liter BaP, 8.0 ..mu..mole/liter BaA, and 40 ..mu..mole/liter A. BaP at 0.16 mg/liter (0.64 ..mu..mole/liter) totally inhibited growth. BaP concentrations an order of magnitude lower inhibited algal growth in fluorescent blacklight. In cool-white light, 5 of 13 metabolites of BaP (each 40 ..mu..g/liter) inhibited algal growth; 3,6-quinone; 6-hydroxy; 9-hydroxy; 3-hydroxy; and 1,6-quinone. Based on these results, PAHs and metabolites of BaP are selectively phototoxic to S. capricornutum due to the incident light intensity below 550 nm.

  1. New α-Glucosidase Inhibitory Triterpenic Acid from Marine Macro Green Alga Codium dwarkense Boergs.

    PubMed

    Ali, Liaqat; Khan, Abdul Latif; Al-Kharusi, Lubna; Hussain, Javid; Al-Harrasi, Ahmed

    2015-07-14

    The marine ecosystem has been a key resource for secondary metabolites with promising biological roles. In the current study, bioassay-guided phytochemical investigations were carried out to assess the presence of enzyme inhibitory chemical constituents from the methanolic extract of marine green alga-Codium dwarkense. The bioactive fractions were further subjected to chromatographic separations, which resulted in the isolation of a new triterpenic acid; dwarkenoic acid (1) and the known sterols; androst-5-en-3β-ol (2), stigmasta-5,25-dien-3β,7α-diol (3), ergosta-5,25-dien-3β-ol (4), 7-hydroxystigmasta-4,25-dien-3-one-7-O-β-d-fucopyranoside (5), 7-hydroxystigmasta-4,25-dien-3-one (6), and stigmasta-5,25-dien-3β-ol (7). The structure elucidation of the new compound was carried out by combined mass spectrometry and 1D (1H and 13C) and 2D (HSQC, HMBC, COSY, and NOESY) NMR spectroscopic data. The sub-fractions and pure constituents were assayed for enzymatic inhibition of alpha-glucosidase. Compound 1 showed significant inhibition at all concentrations. Compounds 2, 3, 5, and 7 exhibited a dose-dependent response, whereas compounds 4-6 showed moderate inhibition. Utilizing such marine-derived biological resources could lead to drug discoveries related to anti-diabetics.

  2. Phycobilisomes from blue-green and red algae: isolation criteria and dissociation characteristics.

    PubMed

    Gantt, E; Lipschultz, C A; Grabowski, J; Zimmerman, B K

    1979-04-01

    A general procedure for the isolation of functionally intact phycobilisomes was devised, based on modifications of previously used procedures. It has been successful with numerous species of red and blue-green algae (Anabaena variabilis, Anacystis nidulans, Agmenellum quadruplicatum, Fremyella diplosiphon, Glaucosphaera vacuolata, Griffithsia pacifica, Nemalion multifidum, Nostoc sp., Phormidium persicinum, Porphyridium cruentum, P. sordidum, P. aerugineum, Rhodosorus marinus). Isolation was carried out in 0.75 molar K-phosphate (pH 6.8 to 7.0) at 20 to 23 C on sucrose step gradients. Lower temperature (4 to 10 C) was usually unfavorable resulting in uncoupling of energy transfer and partial dissociation of the phycobilisomes, sometimes with complete loss of allophycocyanin. Intact phycobilisomes were characterized by fluorescence emission peaks of 670 to 675 nanometers at room temperature, and 678 to 685 nanometers at liquid nitrogen temperature. Uncoupling and subsequent dissociation of phycobilisomes, in lowered ionic conditions, varied with the species and the degree of dissociation but occurred preferentially between phycocyanin and allophycocyanin, or between phycocyanin and phycoerythrin.

  3. The effects of nitric oxide in settlement and adhesion of zoospores of the green alga Ulva.

    PubMed

    Thompson, Stephanie E M; Callow, Maureen E; Callow, James A

    2010-01-01

    Previous studies have shown that elevated nitric oxide (NO) reduces adhesion in diatom, bacterial and animal cells. This article reports experiments designed to investigate whether elevated NO reduces the adhesion of zoospores of the green alga Ulva, an important fouling species. Surface-normalised values of NO were measured using the fluorescent indicator DAF-FM DA and parallel hydrodynamic measurements of adhesion strength were made. Elevated levels of NO caused by the addition of the exogenous NO donor SNAP reduced spore settlement by 20% and resulted in lower adhesion strength. Addition of the NO scavenger cPTIO abolished the effects of SNAP on adhesion. The strength of attachment and NO production by spores in response to four coatings (Silastic T2; Intersleek 700; Intersleek 900 and polyurethane) shows that reduced adhesion is correlated with an increase in NO production. It is proposed that in spores of Ulva, NO is used as an intracellular signalling molecule to detect how conducive a surface is for settlement and adhesion. The effect of NO on the adhesion of a range of organisms suggests that NO-releasing coatings could have the potential to control fouling.

  4. Simultaneous cryo X-ray ptychographic and fluorescence microscopy of green algae

    PubMed Central

    Deng, Junjing; Vine, David J.; Chen, Si; Nashed, Youssef S. G.; Jin, Qiaoling; Phillips, Nicholas W.; Peterka, Tom; Ross, Rob; Vogt, Stefan; Jacobsen, Chris J.

    2015-01-01

    Trace metals play important roles in normal and in disease-causing biological functions. X-ray fluorescence microscopy reveals trace elements with no dependence on binding affinities (unlike with visible light fluorophores) and with improved sensitivity relative to electron probes. However, X-ray fluorescence is not very sensitive for showing the light elements that comprise the majority of cellular material. Here we show that X-ray ptychography can be combined with fluorescence to image both cellular structure and trace element distribution in frozen-hydrated cells at cryogenic temperatures, with high structural and chemical fidelity. Ptychographic reconstruction algorithms deliver phase and absorption contrast images at a resolution beyond that of the illuminating lens or beam size. Using 5.2-keV X-rays, we have obtained sub–30-nm resolution structural images and ∼90-nm–resolution fluorescence images of several elements in frozen-hydrated green algae. This combined approach offers a way to study the role of trace elements in their structural context. PMID:25675478

  5. Purification, characterization, and complete amino acid sequence of a thioredoxin from a green alga, Chlamydomonas reinhardtii.

    PubMed

    Decottignies, P; Schmitter, J M; Jacquot, J P; Dutka, S; Picaud, A; Gadal, P

    1990-07-01

    Two thioredoxins (named Ch1 and Ch2 in reference to their elution pattern on an anion-exchange column) have been purified to homogeneity from the green alga, Chlamydomonas reinhardtii. In this paper, we described the properties and the sequence of the most abundant form, Ch2. Its activity in various enzymatic assays has been compared with those of Escherichia coli and spinach thioredoxins. C. reinhardtii thioredoxin Ch2 can serve as a substrate for E. coli thioredoxin reductase with a lower efficiency when compared to the homologous system. In the presence of dithiothreitol (DTT), the protein is able to catalyze the reduction of porcine insulin. Thioredoxin Ch2 is as efficient as its spinach counterpart in the DTT or light activation of corn NADP-malate dehydrogenase, but it only activates spinach fructose-1, 6-bisphosphatase at very high concentrations. The complete primary structure of the C. reinhardtii thioredoxin Ch2 was determined by automated Edman degradation of the intact protein and of peptides derived from trypsin, chymotrypsin, clostripain, and SV8 protease digestions. It consists of a polypeptide of 106 amino acids (MW 11,808) and contains the well-conserved active site sequence Trp-Cys-Gly-Pro-Cys. The sequence of the algal thioredoxin Ch2 has been compared to that of thioredoxins from other sources and has the greatest similarity (67%) with the thioredoxin from Anabaena 7119.

  6. Kinetic flux profiling dissects nitrogen utilization pathways in the oleaginous green alga Chlorella protothecoides.

    PubMed

    Wu, Chao; Xiong, Wei; Dai, Junbiao; Wu, Qingyu

    2016-02-01

    As a promising candidate for biodiesel production, the green alga Chlorella protothecoides can efficiently produce oleaginous biomass and the lipid biosynthesis is greatly influenced by the availability of nitrogen source and corresponding nitrogen assimilation pathways. Based on isotope-assisted kinetic flux profiling (KFP), the fluxes through the nitrogen utilization pathway were quantitatively analyzed. We found that autotrophic C. protothecoides cells absorbed ammonium mainly through glutamate dehydrogenase (GDH), and partially through glutamine synthetase (GS), which was the rate-limiting enzyme of nitrogen assimilation process with rare metabolic activity of glutamine oxoglutarate aminotransferase (GOGAT, also known as glutamate synthase); whereas under heterotrophic conditions, the cells adapted to GS-GOGAT cycle for nitrogen assimilation in which GS reaction rate was associated with GOGAT activity. The fact that C. protothecoides chooses the adenosine triphosphate-free and less ammonium-affinity GDH pathway, or alternatively the energy-consuming GS-GOGAT cycle with high ammonium affinity for nitrogen assimilation, highlights the metabolic adaptability of C. protothecoides exposed to altered nitrogen conditions.

  7. Ca2+ Requirement for Aerobic Nitrogen Fixation by Heterocystous Blue-Green Algae 1

    PubMed Central

    Rodríguez, Herminia; Rivas, Joaquín; Guerrero, Miguel G.; Losada, Manuel

    1990-01-01

    The requirement of Ca2+ for growth and nitrogen fixation has been investigated in two strains of heterocystous blue-green algae (Anabaena sp. and Anabaena ATCC 33047). With combined nitrogen (nitrate or ammonium) or with N2 under microaerobic conditions, Ca2+ was not required for growth, at least in concentrations greater than traces. In contrast, Ca2+ was required as a macronutrient for growth and nitrogen fixation with air as the nitrogen source. Addition of Ca2+ to an aerobic culture without Ca2+ promoted, after a lag of several hours, development of nitrogenase activity and cell growth. Provision of air to a microaerobic culture in the absence of Ca2+ promoted a drastic drop in nitrogenase activity, which rapidly recovered its initial level upon restoration of microaerobic conditions. Development of nitrogenase activity in response to either Ca2+ or low oxygen tension was dependent on de novo protein synthesis. The role of Ca2+ seems to be related to protection of nitrogenase from inactivation, by conferring heterocysts resistance to oxygen. PMID:16667401

  8. Transcriptome for Photobiological Hydrogen Production Induced by Sulfur Deprivation in the Green Alga Chlamydomonas reinhardtii▿ †

    PubMed Central

    Nguyen, Anh Vu; Thomas-Hall, Skye R.; Malnoë, Alizée; Timmins, Matthew; Mussgnug, Jan H.; Rupprecht, Jens; Kruse, Olaf; Hankamer, Ben; Schenk, Peer M.

    2008-01-01

    Photobiological hydrogen production using microalgae is being developed into a promising clean fuel stream for the future. In this study, microarray analyses were used to obtain global expression profiles of mRNA abundance in the green alga Chlamydomonas reinhardtii at different time points before the onset and during the course of sulfur-depleted hydrogen production. These studies were followed by real-time quantitative reverse transcription-PCR and protein analyses. The present work provides new insights into photosynthesis, sulfur acquisition strategies, and carbon metabolism-related gene expression during sulfur-induced hydrogen production. A general trend toward repression of transcripts encoding photosynthetic genes was observed. In contrast to all other LHCBM genes, the abundance of the LHCBM9 transcript (encoding a major light-harvesting polypeptide) and its protein was strongly elevated throughout the experiment. This suggests a major remodeling of the photosystem II light-harvesting complex as well as an important function of LHCBM9 under sulfur starvation and photobiological hydrogen production. This paper presents the first global transcriptional analysis of C. reinhardtii before, during, and after photobiological hydrogen production under sulfur deprivation. PMID:18708561

  9. Active Hydrocarbon Biosynthesis and Accumulation in a Green Alga, Botryococcus braunii (Race A)

    PubMed Central

    Hirose, Mana; Mukaida, Fukiko; Okada, Sigeru

    2013-01-01

    Among oleaginous microalgae, the colonial green alga Botryococcus braunii accumulates especially large quantities of hydrocarbons. This accumulation may be achieved more by storage of lipids in the extracellular space rather than in the cytoplasm, as is the case for all other examined oleaginous microalgae. The stage of hydrocarbon synthesis during the cell cycle was determined by autoradiography. The cell cycle of B. braunii race A was synchronized by aminouracil treatment, and cells were taken at various stages in the cell cycle and cultured in a medium containing [14C]acetate. Incorporation of 14C into hydrocarbons was detected. The highest labeling occurred just after septum formation, when it was about 2.6 times the rate during interphase. Fluorescent and electron microscopy revealed that new lipid accumulation on the cell surface occurred during at least two different growth stages and sites of cells. Lipid bodies in the cytoplasm were not prominent in interphase cells. These lipid bodies then increased in number, size, and inclusions, reaching maximum values just before the first lipid accumulation on the cell surface at the cell apex. Most of them disappeared from the cytoplasm concomitant with the second new accumulation at the basolateral region, where extracellular lipids continuously accumulated. The rough endoplasmic reticulum near the plasma membrane is prominent in B. braunii, and the endoplasmic reticulum was often in contact with both a chloroplast and lipid bodies in cells with increasing numbers of lipid bodies. We discuss the transport pathway of precursors of extracellular hydrocarbons in race A. PMID:23794509

  10. Toxic cell concentrations of three polychlorinated biphenyl congeners in the green alga, Selenastrum capricornutum

    SciTech Connect

    Mayer, P. |; Halling-Soerensen, B.; Nyholm, N.; Sijm, D.T.H.M.

    1998-09-01

    Algal growth inhibition tests were performed with the unicellular green alga Selenastrum capricornutum and three {sup 14}C-labeled polychlorinated biphenyl (PCB) congeners. Toxicity was related to external aqueous concentrations and additionally to internal algal bound PCB concentrations. Estimates of the concentrations at 50% effectiveness (EC50s) for the three PCB congeners ranged within a factor of 17 when based on measured aqueous concentrations. When based on internal toxicant concentrations the corresponding range was 6.7 to 14.3 mmol/kg wet weight. Thus, changing the basis from external to internal concentrations reduced the range by almost one order of magnitude. Additional toxic cell concentrations of five monoaromatic compounds and S. capricornutum were calculated from literature data to be in the same order of magnitude as the experimental toxic cell concentrations for the PCBs, whereas EC50 values for all substances ranged by more than four orders of magnitude. The experimental and calculated data indicate that observed differences in the estimated EC50 values were mainly due to differences in bioconcentration behavior rather than to different intrinsic toxicities. These findings are in agreement with the concept of baseline toxicity, meaning that a number of hydrophobic organics exerts their acute toxicity by one relatively nonspecific mode of action.

  11. Chlorophyll a fluorescence lifetime reveals reversible UV-induced photosynthetic activity in the green algae Tetraselmis.

    PubMed

    Kristoffersen, Arne S; Hamre, Børge; Frette, Øyvind; Erga, Svein R

    2016-04-01

    The fluorescence lifetime is a very useful parameter for investigating biological materials on the molecular level as it is mostly independent of the fluorophore concentration. The green alga Tetraselmis blooms in summer, and therefore its response to UV irradiation is of particular interest. In vivo fluorescence lifetimes of chlorophyll a were measured under both normal and UV-stressed conditions of Tetraselmis. Fluorescence was induced by two-photon excitation using a femtosecond laser and laser scanning microscope. The lifetimes were measured in the time domain by time-correlated single-photon counting. Under normal conditions, the fluorescence lifetime was 262 ps, while after 2 h of exposure to UV radiation the lifetime increased to 389 ps, indicating decreased photochemical quenching, likely caused by a damaged and down-regulated photosynthetic apparatus. This was supported by a similar increase in the lifetime to 425 ps when inhibiting photosynthesis chemically using DCMU. Furthermore, the UV-stressed sample was dark-adapted overnight, resulting in a return of the lifetime to 280 ps, revealing that the damage caused by UV radiation is repairable on a relatively short time scale. This reversal of photosynthetic activity was also confirmed by [Formula: see text] measurements.

  12. Stereocontrolled reduction of alpha- and beta-keto esters with micro green algae, Chlorella strains.

    PubMed

    Ishihara, K; Yamaguchi, H; Adachi, N; Hamada, H; Nakajima, N

    2000-10-01

    The stereocontrolled reduction of alpha- and beta-keto esters using micro green algae was accomplished by a combination of the cultivation method and the introduction of an additive. The reduction of ethyl pyruvate and ethyl benzoylformate by the photoautotrophically cultivated Chlorella sorokiniana gave the corresponding alcohol in high e.e. (>99% e.e. (S) and >99% e.e. (R), respectively). In the presence of glucose as an additive, the reduction of ethyl 3-methyl-2-oxobutanoate by the heterotrophically cultivated C. sorokiniana afforded the corresponding (R)-alcohol. On the other hand, the reduction in the presence of ethyl propionate gave the (S)-alcohol. Ethyl 2-methyl-3-oxobutanoate was reduced in the presence of glycerol by the photoautotrophically cultivated C. sorokiniana or the heterotrophically cultivated C. sorokiniana to the corresponding syn-(2R,3S)-hydroxy ester with high diastereo- and enantiomeric excess (e.e.). Some additives altered the stereochemical course in the reduction of alpha- and beta-keto esters.

  13. The hepatoprotective activity of blue green algae in Schistosoma mansoni infected mice.

    PubMed

    Mohamed, Azza H; Osman, Gamalat Y; Salem, Tarek A; Elmalawany, Alshimaa M

    2014-10-01

    This study aims to evaluate the immunomodulatory effects of a natural product, blue green algae (BGA) (100 mg/kg BW), alone or combined with praziquantel PZQ (250 mg/kg BW) on granulomatous inflammation, liver histopathology, some biochemical and immunological parameters in mice infected with Schistosoma mansoni. Results showed that the diameter and number of egg granuloma were significantly reduced after treatment of S. mansoni-infected mice with BGA, PZQ and their combination. The histopathological alterations observed in the liver of S. mansoni-infected mice were remarkably inhibited after BGA treatments. BGA decreased the activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP) as well as the level of total protein (TP) while the level of albumin was increased. Treatment of infected mice with BGA, PZQ as well as their combination led to significant elevation in the activities of hepatic antioxidant enzymes glutathione peroxidase (GPX) and glutathione-S-transferase (GST) as compared with control group. Combination of BGA and PZQ resulted in significant reduction in the level of intercellular adhesion molecules-1 (ICAM-1), vascular adhesion molecules-1 (VCAM-1) and tumor necrosis factor-alpha (TNF-α) when compared to those of the S. mansoni-infected group. Overall, BGA significantly inhibited the liver damage accompanied with schistosomiasis, exhibited a potent antioxidant and immunoprotective activities. This study suggests that BGA can be considered as promising for development a complementary and/or alternative medicine against schistosomiasis.

  14. Isolation of prasinoviruses of the green unicellular algae Ostreococcus spp. on a worldwide geographical scale.

    PubMed

    Bellec, Laure; Grimsley, Nigel; Desdevises, Yves

    2010-01-01

    Ostreococcus spp. are extremely small unicellular eukaryotic green algae found worldwide in marine environments, and they are susceptible to attacks by a diverse group of large DNA viruses. Several biologically distinct species of Ostreococcus are known and differ in the ecological niches that they occupy: while O. tauri (representing clade C strains) is found in marine lagoons and coastal seas, strains belonging to clade A, exemplified by O. lucimarinus, are present in different oceans. We used laboratory cultures of clonal isolates of these two species to assay for the presence of viruses in seawater samples from diverse locations. In keeping with the distributions of their host strains, we found a decline in the abundance of O. tauri viruses from a lagoon in southwest France relative to the Mediterranean Sea, whereas in the ocean, no O. tauri viruses were detected. In contrast, viruses infecting O. lucimarinus were detected from distantly separated oceans. DNA sequencing, phylogenetic analyses using a conserved viral marker gene, and a Mantel test revealed no relationship between geographic and phylogenetic distances in viruses infecting O. lucimarinus.

  15. Two components of photoreceptor potential in phototaxis of the flagellated green alga Haematococcus pluvialis

    PubMed Central

    Sineshchekov, Oleg A.; Litvin, Felix F.; Keszthelyi, Lajos

    1990-01-01

    The kinetics of the photoreceptor potential of phototaxis in biflagellated green alga Haematococcus pluvialis in response to a 10-ns laser pulse of three wavelengths (465, 550, and 590 nm) were measured in single cells with 30 μs time resolution. The rise and the decay of photoinduced potential are both at least biphasic. The first component of the rise is very stable and has no measurable (<30 μs) time delay. The second component is triggered after a 120-400-μs lag period, depending on flash intensity. Its appearance is sensitive to the physiological state of the cell and the amplitude can be increased by phototactically ineffective red background illumination. The electrical generators for both components are localized in the same region of the cell membrane (on the stigma-bearing side) and these components have the same depolarizing sign. The results indicate that the photoreceptor potential in phototaxis comprises two components, which could be interpreted as light-induced charge movement within the photoreceptor molecules and changes in ion permeability of the cell membrane. PMID:19431753

  16. First crystal structure of Rubisco from a green alga, Chlamydomonas reinhardtii.

    PubMed

    Taylor, T C; Backlund, A; Bjorhall, K; Spreitzer, R J; Andersson, I

    2001-12-21

    The crystal structure of Rubisco (ribulose 1,5-bisphosphate carboxylase/oxygenase) from the unicellular green alga Chlamydomonas reinhardtii has been determined to 1.4 A resolution. Overall, the structure shows high similarity to the previously determined structures of L8S8 Rubisco enzymes. The largest difference is found in the loop between beta strands A and B of the small subunit (betaA-betaB loop), which is longer by six amino acid residues than the corresponding region in Rubisco from Spinacia. Mutations of residues in the betaA-betaB loop have been shown to affect holoenzyme stability and catalytic properties. The information contained in the Chlamydomonas structure enables a more reliable analysis of the effect of these mutations. No electron density was observed for the last 13 residues of the small subunit, which are assumed to be disordered in the crystal. Because of the high resolution of the data, some posttranslational modifications are unambiguously apparent in the structure. These include cysteine and N-terminal methylations and proline 4-hydroxylations.

  17. Characteristics of Fluorescence and Delayed Light Emission from Green Photosynthetic Bacteria and Algae

    PubMed Central

    Clayton, Roderick K.

    1965-01-01

    Green photosynthetic bacteria exhibit variations in the intensity of their fluorescence during illumination. The initial intensity of fluorescence, measured at the onset of illumination, has a spectrum in which the major pigment Chlorobium chlorophyll predominates. The minor pigment bacteriochlorophyll predominates in the spectrum of the time-varying part of the fluorescence. The spectrum of delayed light emission is identical to that of the time-varying fluorescence. The variations in fluorescence also resemble the delayed light in their kinetics and in their dependence on exciting light intensity. Similar results are obtained for the kinetics of prompt and delayed light emission in the algae Chlorella and Anacystis. These findings raise the possibility that the variations in fluorescence actually represent a fast component of delayed light emission, of intensity comparable to the intensity of fluorescence. In Anacystis there is an outburst of light emission that develops after the exciting light has been turned off, reaching a maximum intensity after 1 to 3 seconds. This emitted light has the spectrum of chlorophyll fluorescence. It appears to be a novel example of bioluminescence with singlet excited chlorophyll as the emitter. PMID:14324979

  18. Occurrence of Only One Form of Glutamine Synthetase in the Green Alga Monoraphidium braunii.

    PubMed Central

    Garcia-Fernandez, J. M.; Lopez-Ruiz, A.; Toribio, F.; Roldan, J. M.; Diez, J.

    1994-01-01

    Anion-exchange chromatography of crude extracts from the green alga Monoraphidium braunii yielded two glutamine synthetase (GS) activities. The ratio of activities was markedly different when crude extracts were subjected to various processing conditions but was not influenced by environmental factors of cell cultures. However, high performance liquid chromatography anion-exchange chromatograms showed only one GS if the crude extracts were processed immediately after cell disruption. Moreover, standard chromatography of crude extracts obtained in the absence of dithioerythritol, a reductant generally used in disruption buffers, yielded a single activity peak. Enzyme samples from the two activities obtained in the presence of dithioerythritol were purified for physicochemical characterization and antibody production. Both enzyme samples exhibited similar reactions to different inactivating agents and were undistinguishable by size-exclusion chromatography and native polyacrylamide gel electrophoresis. Additionally, the two GS preparations showed absolute antigenic identity as demonstrated by immunodiffusion and immunoblotting experiments. Immunocytochemistry of M. braunii cryosections evidenced a chloroplast-specific distribution of the enzyme, which rules out the existence of a cytoplasmic counterpart. All these results support the proposal that M. braunii possesses only one form of GS. PMID:12232093

  19. Oxygen-dependent proton efflux in cyanobacteria (blue-green algae).

    PubMed Central

    Scherer, S; Stürzl, E; Böger, P

    1984-01-01

    The oxygen-dependent proton efflux (in the dark) of intact cells of Anabaena variabilis and four other cyanobacteria (blue-green algae) was investigated. In contrast to bacteria and isolated mitochondria, an H+/e ratio (= protons translocated per electron transported) of only 0.23 to 0.35 and a P/e ratio of 0.8 to 1.5 were observed, indicative of respiratory electron transport being localized essentially on the thylakoids, not on the cytoplasmic membrane. Oxygen-induced acidification of the medium was sensitive to cyanide and the uncoupler carbonyl cyanide m-chlorophenylhydrazone. Inhibitors such as 2,6-dinitrophenol and vanadate exhibited a significant decrease in the H+/e ratio. After the oxygen pulse, electron transport started immediately, but proton efflux lagged 40 to 60 s behind, a period also needed before maximum ATP pool levels were attained. We suggest that proton efflux in A. variabilis is due to a proton-translocating ATP hydrolase (ATP-consuming ATPase) rather than to respiratory electron transport located on the cytoplasmic membrane. PMID:6327614

  20. Simultaneous cryo X-ray ptychographic and fluorescence microscopy of green algae

    DOE PAGES

    Deng, Junjing; Vine, David J.; Chen, Si; ...

    2015-02-24

    Trace metals play important roles in normal and in disease-causing biological functions. X-ray fluorescence microscopy reveals trace elements with no dependence on binding affinities (unlike with visible light fluorophores) and with improved sensitivity relative to electron probes. However, X-ray fluorescence is not very sensitive for showing the light elements that comprise the majority of cellular material. Here we show that X-ray ptychography can be combined with fluorescence to image both cellular structure and trace element distribution in frozen-hydrated cells at cryogenic temperatures, with high structural and chemical fidelity. Ptychographic reconstruction algorithms deliver phase and absorption contrast images at a resolutionmore » beyond that of the illuminating lens or beam size. Using 5.2-keV X-rays, we have obtained sub-30-nm resolution structural images and ~90-nm-resolution fluorescence images of several elements in frozen-hydrated green algae. Finally, this combined approach offers a way to study the role of trace elements in their structural context.« less

  1. Nitrogenase activity, amino acid pool patterns and amination in blue-green algae.

    PubMed

    Dharmawardene, M W; Stewart, W D; Stanley, S O

    1972-06-01

    The free amino acid pools in the nitrogen-fixing blue-green algae Anabaena cylindrica, A. flos-aquae and Westiellopsis prolifica contain a variety of amino acids with aspartic acid, glutamic acid and the amide glutamine being present in much higher concentrations than the others. This pattern is characteristic of that found in organisms having glutamine synthetage/glutamate synthetase [glutamine amide-2-oxoglutarate amino transferase (oxido-reductase)] as an important pathway of ammonia incorporation. Under nitrogen-starved conditions the level of acetylene reduction (nitrogen fixation) and the glutamine pool both increase but the free ammonia pool decreases, suggesting that ammonia rather than glutamine regulates nitrogen fixation.Glutamine synthetase has been demonstrated in Anabaena cylindrica using the γ-glutamyl transferase assay and also using a biosynthetic assay in which Pi release from ATP during glutamine synthesis was measured. The enzyme (γ-glutamyl transferase assay) is present in nitrogen-fixing cultures and activity is higher in aerobic than in microaerophilic cultures. Ammonium-grown cultures have lowest levels of all and activity in the presence of nitrate-nitrogen (150 mg nitrogen 1(-1)) is lower than in aerobic cultures growing on elemental nitrogen. Ammonium-nitrogen and nitrate-nitrogen have no effect on glutamine synthetase in vitro. Glutamate synthetase also operates in nitrogen-fixing cultures of Anabaena cylindrica.

  2. Recovery of adenine-nucleotide pools in terrestrial blue-green algae after prolonged drought periods.

    PubMed

    Scherer, Siegfried; Chen, Ting-Wei; Böger, Peter

    1986-03-01

    The response of Nostoc commune and Nostoc flagelliforme (terrestrial blue-green algae), grown in their natural habitat, towards rewetting after prolonged drought periods (2 weeds up to five years) has been investigated. In Nostoc flagelliforme, the energy charge (EC) about 0.18 in dry condition increases rapidly (EC=0.7 after 1 h) and more slowly in a second phase (EC=0.8 after 6 h). The total content of AXP (=ATP+ADP+AMP) apparently increases due to de novo synthesis of adenine nucleotides. ATP-build-up after a drought period is probably provided by oxidative phosphorylation. It has been found to be about the same, regardless of whether the foregoing drought period had been extended over 6 months or 5 years.Dry samples of colony mats of N. commune exhibit very low ATP-, but high ADP-contents. Within 6 h after rewetting, the final level of extractable ATP (60-100 nmol/mg chlorophyll) is recovered.

  3. Bioenergetic strategy for the biodegradation of p-cresol by the unicellular green alga Scenedesmus obliquus.

    PubMed

    Papazi, Aikaterini; Assimakopoulos, Konstantinos; Kotzabasis, Kiriakos

    2012-01-01

    Cultures from the unicellular green alga Scenedesmus obliquus biodegrade the toxic p-cresol (4-methylphenol) and use it as alternative carbon/energy source. The biodegradation procedure of p-cresol seems to be a two-step process. HPLC analyses indicate that the split of the methyl group (first step) that is possibly converted to methanol (increased methanol concentration in the growth medium), leading, according to our previous work, to changes in the molecular structure and function of the photosynthetic apparatus and therefore to microalgal biomass increase. The second step is the fission of the intermediately produced phenol. A higher p-cresol concentration results in a higher p-cresol biodegradation rate and a lower total p-cresol biodegradability. The first biodegradation step seems to be the most decisive for the effectiveness of the process, because methanol offers energy for the further biodegradation reactions. The absence of LHCII from the Scenedesmus mutant wt-lhc stopped the methanol effect and significantly reduced the p-cresol biodegradation (only 9%). The present contribution deals with an energy distribution between microalgal growth and p-cresol biodegradation, activated by p-cresol concentration. The simultaneous biomass increase with the detoxification of a toxic phenolic compound (p-cresol) could be a significant biotechnological aspect for further applications.

  4. Bioenergetic Strategy for the Biodegradation of p-Cresol by the Unicellular Green Alga Scenedesmus obliquus

    PubMed Central

    Papazi, Aikaterini; Assimakopoulos, Konstantinos; Kotzabasis, Kiriakos

    2012-01-01

    Cultures from the unicellular green alga Scenedesmus obliquus biodegrade the toxic p-cresol (4-methylphenol) and use it as alternative carbon/energy source. The biodegradation procedure of p-cresol seems to be a two-step process. HPLC analyses indicate that the split of the methyl group (first step) that is possibly converted to methanol (increased methanol concentration in the growth medium), leading, according to our previous work, to changes in the molecular structure and function of the photosynthetic apparatus and therefore to microalgal biomass increase. The second step is the fission of the intermediately produced phenol. A higher p-cresol concentration results in a higher p-cresol biodegradation rate and a lower total p-cresol biodegradability. The first biodegradation step seems to be the most decisive for the effectiveness of the process, because methanol offers energy for the further biodegradation reactions. The absence of LHCII from the Scenedesmus mutant wt-lhc stopped the methanol effect and significantly reduced the p-cresol biodegradation (only 9%). The present contribution deals with an energy distribution between microalgal growth and p-cresol biodegradation, activated by p-cresol concentration. The simultaneous biomass increase with the detoxification of a toxic phenolic compound (p-cresol) could be a significant biotechnological aspect for further applications. PMID:23251641

  5. Salt stress-induced cell death in the unicellular green alga Micrasterias denticulata.

    PubMed

    Affenzeller, Matthias Josef; Darehshouri, Anza; Andosch, Ancuela; Lütz, Cornelius; Lütz-Meindl, Ursula

    2009-01-01

    Programmed cell death (PCD) is a key element in normal plant growth and development which may also be induced by various abiotic and biotic stress factors including salt stress. In the present study, morphological, biochemical, and physiological responses of the theoretically immortal unicellular freshwater green alga Micrasterias denticulata were examined after salt (200 mM NaCl or 200 mM KCl) and osmotic stress induced by iso-osmotic sorbitol. KCl caused morphological changes such as cytoplasmic vacuolization, extreme deformation of mitochondria, and ultrastructural changes of Golgi and ER. However, prolonged salt stress (24 h) led to the degradation of organelles by autophagy, a special form of PCD, both in NaCl- and KCl-treated cells. This was indicated by the enclosure of organelles by ER-derived double membranes. DNA of NaCl- and KCl-stressed cells but not of sorbitol-treated cells showed a ladder-like pattern on agarose gel, which means that the ionic rather than the osmotic component of salt stress leads to the activation of the responsible endonuclease. DNA laddering during salt stress could be abrogated by addition of Zn(2+). Neither cytochrome c release from mitochondria nor increase in caspase-3-like activity occurred after salt stress. Reactive oxygen species could be detected within 5 min after the onset of salt and osmotic stress. Respiration, photosynthetic activity, and pigment composition indicated an active metabolism which supports programmed rather than necrotic cell death in Micrasterias after salt stress.

  6. Convoluted Plasma Membrane Domains in the Green Alga Chara are Depleted of Microtubules and Actin Filaments.

    PubMed

    Sommer, Aniela; Hoeftberger, Margit; Hoepflinger, Marion C; Schmalbrock, Sarah; Bulychev, Alexander; Foissner, Ilse

    2015-10-01

    Charasomes are convoluted plasma membrane domains in the green alga Chara australis. They harbor H(+)-ATPases involved in acidification of the medium, which facilitates carbon uptake required for photosynthesis. In this study we investigated the distribution of cortical microtubules and cortical actin filaments in relation to the distribution of charasomes. We found that microtubules and actin filaments were largely lacking beneath the charasomes, suggesting the absence of nucleating and/or anchoring complexes or an inhibitory effect on polymerization. We also investigated the influence of cytoskeleton inhibitors on the light-dependent growth and the darkness-induced degradation of charasomes. Inhibition of cytoplasmic streaming by cytochalasin D significantly inhibited charasome growth and delayed charasome degradation, whereas depolymerization of microtubules by oryzalin or stabilization of microtubules by paclitaxel had no effect. Our data indicate that the membrane at the cytoplasmic surface of charasomes has different properties in comparison with the smooth plasma membrane. We show further that the actin cytoskeleton is necessary for charasome growth and facilitates charasome degradation presumably via trafficking of secretory and endocytic vesicles, respectively. However, microtubules are required neither for charasome growth nor for charasome degradation.

  7. The growth response of the green alga Chlorella vulgaris to combined divalent cation exposure.

    PubMed

    Rachlin, J W; Grosso, A

    1993-01-01

    Using the growth response of the green alga Chlorella vulgaris as a model system, the effects of combinations of the environmentally active cations Cd, Co, and Cu were evaluated. The 96-h static EC50 for these cations to C. vulgaris were, respectively, 0.89 microM, 9.0 microM, and 2.8 microM, yielding a toxicity series such that Cd > Cu > Co. The cation combinations of Cd + Cu, and Cu + Co acted synergistically, while Cd + Co, and the tri-metallic combination Cd + Cu + Co resulted in antagonistic interactions. Examination of these toxic combinations at 24, 48, 72, and 96 h indicate that the cellular response is not a uniform one. Failure of energy dispersive X-ray spectrophotometric analysis to demonstrate any intracellular incorporation of these cations (except for a weak cytoplasmic Cu peak at the 8.0 KEV position) suggests that the toxic actions of these cations at EC50 concentrations are exerted at the level of the plasma membrane.

  8. Robust Transgene Expression from Bicistronic mRNA in the Green Alga Chlamydomonas reinhardtii

    PubMed Central

    Onishi, Masayuki; Pringle, John R.

    2016-01-01

    The unicellular green alga Chlamydomonas reinhardtii is a model organism that provides an opportunity to understand the evolution and functional biology of the lineage that includes the land plants, as well as aspects of the fundamental core biology conserved throughout the eukaryotic phylogeny. Although many tools are available to facilitate genetic, molecular biological, biochemical, and cell biological studies in Chlamydomonas, expression of unselected transgenes of interest (GOIs) has been challenging. In most methods used previously, the GOI and a selectable marker are expressed from two separate mRNAs, so that their concomitant expression is not guaranteed. In this study, we developed constructs that allow expression of an upstream GOI and downstream selectable marker from a single bicistronic mRNA. Although this approach in other systems has typically required a translation-enhancing element such as an internal ribosome entry site for the downstream marker, we found that a short stretch of unstructured junction sequence was sufficient to obtain adequate expression of the downstream gene, presumably through post-termination reinitiation. With this system, we obtained robust expression of both endogenous and heterologous GOIs, including fluorescent proteins and tagged fusion proteins, in the vast majority of transformants, thus eliminating the need for tedious secondary screening for GOI-expressing transformants. This improved efficiency should greatly facilitate a variety of genetic and cell-biological studies in Chlamydomonas and also enable new applications such as expression-based screens and large-scale production of foreign proteins. PMID:27770025

  9. CELL WALL CARBOHYDRATE EPITOPES IN THE GREEN ALGA OEDOGONIUM BHARUCHAE F. MINOR (OEDOGONIALES, CHLOROPHYTA)(1).

    PubMed

    Estevez, José M; Leonardi, Patricia I; Alberghina, Josefina S

    2008-10-01

    Cell wall changes in vegetative and suffultory cells (SCs) and in oogonial structures from Oedogonium bharuchae N. D. Kamat f. minor Vélez were characterized using monoclonal antibodies against several carbohydrate epitopes. Vegetative cells and SCs develop only a primary cell wall (PCW), whereas mature oogonial cells secrete a second wall, the oogonium cell wall (OCW). Based on histochemical and immunolabeling results, (1→4)-β-glucans in the form of crystalline cellulose together with a variable degree of Me-esterified homogalacturonans (HGs) and hydroxyproline-rich glycoprotein (HRGP) epitopes were detected in the PCW. The OCW showed arabinosides of the extensin type and low levels of arabinogalactan-protein (AGP) glycans but lacked cellulose, at least in its crystalline form. Surprisingly, strong colabeling in the cytoplasm of mature oogonia cells with three different antibodies (LM-5, LM-6, and CCRC-M2) was found, suggesting the presence of rhamnogalacturonan I (RG-I)-like structures. Our results are discussed relating the possible functions of these cell wall epitopes with polysaccharides and O-glycoproteins during oogonium differentiation. This study represents the first attempt to characterize these two types of cell walls in O. bharuchae, comparing their similarities and differences with those from other green algae and land plants. This work represents a contribution to the understanding of how cell walls have evolved from simple few-celled to complex multicelled organisms.

  10. Health benefits of blue-green algae: prevention of cardiovascular disease and nonalcoholic fatty liver disease.

    PubMed

    Ku, Chai Siah; Yang, Yue; Park, Youngki; Lee, Jiyoung

    2013-02-01

    Blue-green algae (BGA) are among the most primitive life forms on earth and have been consumed as food or medicine by humans for centuries. BGA contain various bioactive components, such as phycocyanin, carotenoids, γ-linolenic acid, fibers, and plant sterols, which can promote optimal health in humans. Studies have demonstrated that several BGA species or their active components have plasma total cholesterol and triglyceride-lowering properties due to their modulation of intestinal cholesterol absorption and hepatic lipogenic gene expression. BGA can also reduce inflammation by inhibiting the nuclear factor κ B activity, consequently reducing the production of proinflammatory cytokines. Furthermore, BGA inhibit lipid peroxidation and have free radical scavenging activity, which can be beneficial for the protection against oxidative stress. The aforementioned effects of BGA can contribute to the prevention of metabolic and inflammatory diseases. This review provides an overview of the current knowledge of the health-promoting functions of BGA against cardiovascular disease and nonalcoholic fatty liver disease, which are major health threats in the developed countries.

  11. Degradation of tricyclazole: Effect of moisture, soil type, elevated carbon dioxide and Blue Green Algae (BGA).

    PubMed

    Kumar, Naveen; Mukherjee, Irani; Sarkar, Bipasa; Paul, Ranjit Kumar

    2017-01-05

    Pesticide persistence and degradation in soil are influenced by factors like soil characteristics, light, moisture etc. Persistence of tricyclazole was studied under different soil moisture regimes viz., dry, field capacity and submerged in two different soil types viz., Inceptisol and Ultisol from Delhi and Karnataka, respectively. Tricyclazole dissipated faster in submerged (t1/2 160.22-177.05d) followed by field capacity (t1/2 167.17-188.07d) and dry (t1/2 300.91-334.35d) in both the soil types. Half-life of tricyclazole in Delhi field capacity soil amended with Blue Green Algae (BGA), was 150.5d as compared to 167.1d in unamended soil. In Karnataka soil amended with BGA the half-lives were 177.0d compared to 188.0d in unamended soil, indicating that BGA amendment enhanced the rate of dissipation of in both the selected soils. Tricyclazole was found to be stable in water over a pH range of 3-9, the half life in paddy field was 60.20d and 5.47d in paddy soil and paddy water, respectively. Statistical analysis and Duncan's Multiple Range Test (DMRT) revealed significant effect of moisture regime, organic matter and atmospheric CO2 level on dissipation of tricyclazole from soil and pH of water (at 95% confidence level p<0.0001). Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Distinctive architecture of the chloroplast genome in the chlorophycean green alga Stigeoclonium helveticum.

    PubMed

    Bélanger, Anne-Sophie; Brouard, Jean-Simon; Charlebois, Patrick; Otis, Christian; Lemieux, Claude; Turmel, Monique

    2006-11-01

    The chloroplast genome has experienced many architectural changes during the evolution of chlorophyte green algae, with the class Chlorophyceae displaying the lowest degree of ancestral traits. We have previously shown that the completely sequenced chloroplast DNAs (cpDNAs) of Chamydomonas reinhardtii (Chlamydomonadales) and Scenedesmus obliquus (Sphaeropleales) are highly scrambled in gene order relative to one another. Here, we report the complete cpDNA sequence of Stigeoclonium helveticum (Chaetophorales), a member of a third chlorophycean lineage. This genome, which encodes 97 genes and contains 21 introns (including four putatively trans-spliced group II introns inserted at novel sites), is remarkably rich in derived features and extremely rearranged relative to its chlorophycean counterparts. At 223,902 bp, Stigeoclonium cpDNA is the largest chloroplast genome sequenced thus far, and in contrast to those of Chlamydomonas and Scenedesmus, features no large inverted repeat. Interestingly, the pattern of gene distribution between the DNA strands and the bias in base composition along each strand suggest that the Stigeoclonium genome replicates bidirectionally from a single origin. Unlike most known trans-spliced group II introns, those of Stigeoclonium exhibit breaks in domains I and II. By placing our comparative genome analyses in a phylogenetic framework, we inferred an evolutionary scenario of the mutational events that led to changes in genome architecture in the Chlorophyceae.

  13. Health Benefits of Blue-Green Algae: Prevention of Cardiovascular Disease and Nonalcoholic Fatty Liver Disease

    PubMed Central

    Ku, Chai Siah; Yang, Yue; Park, Youngki

    2013-01-01

    Abstract Blue-green algae (BGA) are among the most primitive life forms on earth and have been consumed as food or medicine by humans for centuries. BGA contain various bioactive components, such as phycocyanin, carotenoids, γ-linolenic acid, fibers, and plant sterols, which can promote optimal health in humans. Studies have demonstrated that several BGA species or their active components have plasma total cholesterol and triglyceride-lowering properties due to their modulation of intestinal cholesterol absorption and hepatic lipogenic gene expression. BGA can also reduce inflammation by inhibiting the nuclear factor κ B activity, consequently reducing the production of proinflammatory cytokines. Furthermore, BGA inhibit lipid peroxidation and have free radical scavenging activity, which can be beneficial for the protection against oxidative stress. The aforementioned effects of BGA can contribute to the prevention of metabolic and inflammatory diseases. This review provides an overview of the current knowledge of the health-promoting functions of BGA against cardiovascular disease and nonalcoholic fatty liver disease, which are major health threats in the developed countries. PMID:23402636

  14. F-actin reorganization upon de- and rehydration in the aeroterrestrial green alga Klebsormidium crenulatum.

    PubMed

    Blaas, Kathrin; Holzinger, Andreas

    2017-03-21

    Filamentous actin (F-actin) is a dynamic network involved in many cellular processes like cell division and cytoplasmic streaming. While many studies have addressed the involvement of F-actin in different cellular processes in cultured cells, little is known on the reactions to environmental stress scenarios, where this system might have essential regulatory functions. We investigated here the de- and rehydration kinetics of breakdown and reassembly of F-actin in the streptophyte green alga Klebsormidium crenulatum. Measurements of the chlorophyll fluorescence (effective quantum yield of photosystem II [ΔF/Fm']) via pulse amplitude modulation were performed as a measure for dehydration induced shut down of physiological activity, which ceased after 141±15min at ∼84% RH. We hypothesized that there is a link between this physiological parameter and the status of the F-actin system. Indeed, 20min of dehydration (ΔF/Fm'=0) leads to a breakdown of the fine cortical F-actin network as visualized by Atto 488 phalloidin staining, and dot-like structures remained. Already 10min after rehydration a beginning reassembly of F-actin is observed, after 25min the F-actin network appeared similar to untreated controls, indicating a full recovery. These results demonstrate the fast kinetics of F-actin dis- and reassembly likely contributing to cellular reorganization upon rehydration.

  15. Convoluted Plasma Membrane Domains in the Green Alga Chara are Depleted of Microtubules and Actin Filaments

    PubMed Central

    Sommer, Aniela; Hoeftberger, Margit; Hoepflinger, Marion C.; Schmalbrock, Sarah; Bulychev, Alexander; Foissner, Ilse

    2015-01-01

    Charasomes are convoluted plasma membrane domains in the green alga Chara australis. They harbor H+-ATPases involved in acidification of the medium, which facilitates carbon uptake required for photosynthesis. In this study we investigated the distribution of cortical microtubules and cortical actin filaments in relation to the distribution of charasomes. We found that microtubules and actin filaments were largely lacking beneath the charasomes, suggesting the absence of nucleating and/or anchoring complexes or an inhibitory effect on polymerization. We also investigated the influence of cytoskeleton inhibitors on the light-dependent growth and the darkness-induced degradation of charasomes. Inhibition of cytoplasmic streaming by cytochalasin D significantly inhibited charasome growth and delayed charasome degradation, whereas depolymerization of microtubules by oryzalin or stabilization of microtubules by paclitaxel had no effect. Our data indicate that the membrane at the cytoplasmic surface of charasomes has different properties in comparison with the smooth plasma membrane. We show further that the actin cytoskeleton is necessary for charasome growth and facilitates charasome degradation presumably via trafficking of secretory and endocytic vesicles, respectively. However, microtubules are required neither for charasome growth nor for charasome degradation. PMID:26272553

  16. The effect of bloom of filamentous green algae on the reproduction of yellowfin sculpin Cottocomephorus grewingkii (Dybowski, 1874) (Cottoidae) during ecological crisis in Lake Baikal.

    PubMed

    Khanaev, I V; Dzyuba, E V; Kravtsova, L S; Grachev, M A

    2016-03-01

    In shallow water areas of open Lake Baikal, filamentous green alga of the genus Spirogyra grows abundantly. Together with alga of the genus Ulothrix, it forms algal mats. According to our observations from 2010 to 2013, the spawning habitat conditions for the yellowfin sculpin Cottocomephorus grewingkii (Dybowski, 1874) (Cottidae) proved to be significantly disturbed in the littoral zone of Listvennichnyi Bay (southern Baikal), which, in turn, reduced the number of egg layings. With a 100% projective cover of the floor and a high density of green filamentous algae, the shallow-water stony substrate becomes completely inaccessible for spawning of the August population.

  17. The toxicity of plastic nanoparticles to green algae as influenced by surface modification, medium hardness and cellular adsorption.

    PubMed

    Nolte, Tom M; Hartmann, Nanna B; Kleijn, J Mieke; Garnæs, Jørgen; van de Meent, Dik; Jan Hendriks, A; Baun, Anders

    2017-02-01

    To investigate processes possibly underlying accumulation and ecological effects of plastic nano-particles we have characterized their interaction with the cell wall of green algae. More specifically, we have investigated the influence of particle surface functionality and water hardness (Ca(2+) concentration) on particle adsorption to algae cell walls. Polystyrene nanoparticles with different functional groups (non-functionalized, -COOH and -NH2) as well as coated (starch and PEG) gold nanoparticles were applied in these studies. Depletion measurements and atomic force microscopy (AFM) showed that adsorption of neutral and positively charged plastic nanoparticles onto the cell wall of P. subcapitata was stronger than that of negatively charged plastic particles. Results indicated that binding affinity is a function of both inter-particle and particle-cell wall interactions which are in turn influenced by the medium hardness and particle concentration. Physicochemical modelling using DLVO theory was used to interpret the experimental data, using also values for interfacial surface free energies. Our study shows that material properties and medium conditions play a crucial role in the rate and state of nanoparticle bio-adsorption for green algae. The results show that the toxicity of nanoparticles can be better described and assessed by using appropriate dose metrics including material properties, complexation/agglomeration behavior and cellular attachment and adsorption. The applied methodology provides an efficient and feasible approach for evaluating potential accumulation and hazardous effects of nanoparticles to algae caused by particle interactions with the algae cell walls. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Evidence for the occurrence of photorespiration in synurophyte algae.

    PubMed

    Bhatti, Shabana; Colman, Brian

    2011-09-01

    The fluxes of CO(2) and oxygen during photosynthesis by cell suspensions of Tessellaria volvocina and Mallomonas papillosa were monitored mass spectrometrically. There was no rapid uptake of CO(2,) only a slow drawdown to compensation concentrations of 26 μM for T. volvocina and 18 μM for M. papillosa, when O(2) evolution ceased, indicating a lack of active bicarbonate uptake by the cells. Darkening of the cells after a period of photosynthesis did not cause rapid release of CO(2), indicating the absence of an intracellular inorganic carbon pool. However, upon darkening a brief burst of CO(2) was observed similar to the post-illumination burst characteristic of C(3) higher plants. Treatment of the cells of both species with the membrane-permeable carbonic anhydrase inhibitor ethoxyzolamide had no adverse effect on photosynthetic rate, but stimulated the dark CO(2) burst indicating the dark oxidation of a compound formed in the light. In the absence of any active accumulation of inorganic carbon photosynthesis in these species should be inhibited by O(2). This was investigated in four synurophyte species T. volvocina, M. papillosa, Synura petersenii, and Synura uvella: photosynthetic O(2) evolution rates in all four algae, measured by O(2) electrode, were significantly higher (40-50%) in media at low O(2) (4%) than in air-equilibrated (21% O(2)) media, indicating an O(2) inhibition of photosynthesis (Warburg effect) and thus the occurrence of photorespiration in these species.

  19. Acid water interferes with salamander-green algae symbiosis during early embryonic development.

    PubMed

    Bianchini, Kristin; Tattersall, Glenn J; Sashaw, Jessica; Porteus, Cosima S; Wright, Patricia A

    2012-01-01

    The inner egg capsule of embryos of the yellow-spotted salamander (Ambystoma maculatum) are routinely colonized by green algae, such as Oophila amblystomatis, that supply O(2) in the presence of light and may consume nitrogenous wastes, forming what has been proposed to be a mutualistic relationship. Given that A. maculatum have been reported to breed in acidic (pH <5.0) and neutral lakes, we hypothesized that low water pH would negatively affect these symbiotic organisms and alter the gradients within the jelly mass. Oxygen gradients were detected within jelly masses measured directly in a natural breeding pond (pH 4.5-4.8) at midday in full sunlight. In the lab, embryo jelly masses reared continuously at pH 4.5 had lower P(O)₂and higher ammonia levels relative to jelly masses held at pH 8.0 (control). Ammonia and lactate concentrations in embryonic tissues were approximately 37%-93% higher, respectively, in embryos reared at water pH 4.5 compared with pH 8.0. Mass was also reduced in embryos reared at pH 4.5 versus pH 8.0. In addition, light conditions (24 h light, 12L : 12D, or 24 h dark) and embryonic position (periphery vs. center) in the jelly mass affected P(O)₂but not ammonia gradients, suggesting that algal symbionts generate O(2) but do not significantly impact local ammonia concentrations, regardless of the pH of the water. We conclude that chronic exposure to acidic breeding ponds had a profound effect on the microenvironment of developing A. maculatum embryos, which in turn resulted in an elevation of potentially harmful metabolic end products and inhibited growth. Under acidic conditions, the expected benefit provided by the algae to the salamander embryo (i.e., high O(2) and low ammonia microenvironment) is compromised, suggesting that the A. maculatum-algal mutualism is beneficial to salamanders only at higher water pH values.

  20. Relationships between acid-soluble thiol peptides and accumulated Pb in the green alga Stichococcus bacillaris.

    PubMed

    Pawlik-Skowrońska

    2000-09-01

    Stichococcus bacillaris, an ubiquitous green microalga accumulated inorganic lead (Pb) from aqueous solutions extra- and intracellularly. In response to Pb uptake acid-soluble thiol peptides (glutathione - GSH and phytochelatins - PC) were synthesized. The proportion of the intracellular Pb uptake by algal cells was low and comprised only 3-6% of the total metal sorption. The intracellular uptake was dependent on external Pb concentration, time of metal exposure and cell metabolism. Pb accumulation in alga was determined by means of 210Pb radiometry. Reduced GSH and PC were determined in algal cells using HPLC with the post-column derivatization with Ellman's reagent. Within the studied concentration range 0.1-20 µM, inorganic lead caused a significant production of induced thiol peptides: PC (n=2-4) and some other unidentified oligopeptides, probably (GluCys)n. The time of appearance and the concentration of individual oligomers of phytochelatins were dependent on the external Pb concentration and time of metal exposure. In algal cells exposed to Pb, significant changes in the GSH level accompanying the formation of the induced thiol peptides were also observed. The GSH level decreased in the cells exposed to the lower (up to 10 µM) studied Pb concentrations or increased in the cells treated with higher (20 µM) Pb concentrations. The thiol groups originated from induced peptides (mainly phytochelatins) followed a stoichiometric relationship 2:1 to the intracellular Pb amounts, however, only at the lowest studied external concentration (0.1 µM). At higher concentrations (up to 2.5 µM), intracellular Pb concentration was equal or even exceeded (at Pb>2.5 µM) two to three times the level of induced thiols. S. bacillaris accumulated intracellularly by 46% more Pb in light than in dark and the level of induced thiol peptides was significantly higher in the cells exposed to Pb under illumination. The rapid formation of these peptides in S. bacillaris in response

  1. Light-modulated NADP-malate dehydrogenases from mossfern and green algae: insights into evolution of the enzyme's regulation.

    PubMed

    Ocheretina, O; Haferkamp, I; Tellioglu, H; Scheibe, R

    2000-11-27

    Chloroplast NADP-dependent malate dehydrogenase is one of the best-studied light-regulated enzymes. In C3 plants, NADP-MDH is a part of the 'malate valve' that controls the export of reducing equivalents in the form of malate to the cytosol. NADP-MDH is completely inactive in the dark and is activated in the light with reduced thioredoxin. Compared with its permanently active NAD-linked counterparts, NADP-MDH exhibits N- and C-terminal sequence extensions, each bearing one regulatory disulphide. Upon reduction of the C-terminal disulphide, the enzyme active site becomes accessible for the substrate. Reduction of the N-terminal disulphide promotes a conformational change advantageous for catalysis. To trace the evolutionary development of this intricate regulation mechanism, we isolated cDNA clones for NADP-MDH from the mossfern Selaginella and from two unicellular green algae. While the NADP-MDH sequence from Selaginella demonstrates the classic cysteine pattern of the higher plant enzyme, the sequences from the green algae are devoid of the N-terminal regulatory disulphide. Phylogenetic analysis of new sequences and of those available in the databases led to the conclusion that the chloroplast NADP-MDH and the cytosolic NAD-dependent form arose via duplication of an ancestral eubacterial gene, which preceded the separation of plant and animal lineages. Redox-sensitive NADP-MDH activity was detected only in the 'green' plant lineage starting from the primitive prasinophytic algae but not in cyanobacteria, Cyanophora paradoxa, red algae and diatoms. The latter organisms therefore appear to utilize mechanisms other than the light-regulated 'malate valve' to remove from plastids excessive electrons produced by photosynthesis.

  2. The effect of sulfide on the blue-green algae of hot springs II. Yellowstone National Park.

    PubMed

    Castenholz, R W

    1977-06-01

    In the Mammoth Springs (Yellowstone National Park) waters with near neutral pH and soluble sulfide (H2S, HS(-), S(2-)) of over 1-2 mg/liter (30-60ΜM) are characterized by substrate covers of phototrophic bacteria (Chloroflexus and aChlorobium-like unicell) above 50‡C and by a blue-green alga (Spirulina labyrinthiformis) below this temperature.Synechococcus. Mastigocladus, and other blue-green algae typical of most hot springs of western North America are excluded, apparently by sulfide. The sulfide-adaptedSpirulina photosynthesized at maximum rates at 45‡C and at approximately 300 to 700ΜEin/m(2)/sec of "visible" radiation. Sulfide (0.6-1.2 mM) severely poisoned photosynthesis of nonadapted populations, but those continuously exposed to over 30ΜM tolerated at least 1 mM without inhibition. A normal(14)C-HCO3 photoincorporation rate was sustained with 0.6-1 mM sulfide in the presence of DCMU (7ΜM) or NH2OH (0.2 mM), although both of these photosystem II inhibitors prevented photoincorporation without sulfide. Other sulfur-containing compounds (S2O3 (2-) SO3 (2-), S2O4 (2-) thioglycolic acid cysteine) were unable to relieve DCMU inhibition. The lowering of the photoincorporation rate by preferentially irradiating photosystem I was also relieved by sulfide. The most tenable explanation of these results is that sulfide is used as a photo-reductant of CO2, at least when photosystem II is inhibited. It is suggested that in some blue-green algae photosystem II is poisoned by a low sulfide concentration, thus making these algae sulfidedependent if they are to continue photosynthesizing in a sulfide environment. Presumably a sulfidecytochrome reductase enzyme system must be synthesized for sulfide to be used as a photo-reductant.

  3. Production of Calcite by the Green Alga Halimeda in Artificial Cretaceous Seawater

    NASA Astrophysics Data System (ADS)

    Stanley, S. M.; Ries, J. B.

    2006-12-01

    The codiacean green alga Halimeda contributes 20-30% of the carbonate sediment in lagoonal areas adjacent to modern Caribbean and Indo-Pacific coral reefs. This alga is syncytial, lacking cell membranes, so that an individual thallus functions as a giant, multinucleate cell. The thallus grows as branching chains of segments interconnected by tubular filaments. A segment is formed in a single day and then filled with calcium carbonate over several days. Aragonite crystals grow within segments in the form of needles, but in some regions of a segment these are subsequently dissolved and their calcium carbonate is reprecipitated as microgranular aragonite. Some of the needles grow in a spherulitic pattern similar to that of inorganic aragonite precipitates. It has been debated whether Halimeda employs organic templates to secrete the aragonite polymorph of calcium carbonate or simply induces precipitation by taking up carbon dioxide for photosynthesis. We have found that Halimeda incrassata segments grown in seawater of modern ionic composition (Mg/Ca molar ratio = 5.2) actually contain an average of about 8% high-Mg calcite (mean 16 mol % Mg substituting for Ca). As the Mg/Ca ratio of ambient seawater is stepped down, calcite constitutes an increasing percentage of the calcium carbonate produced, and, as we have found for numerous other kinds of organisms, the Mg content of the calcite declines. For segments grown in seawater with the imputed Cretaceous Mg/Ca molar ratio of 1.5, calcite constituted, on average, 46% of the calcium carbonate (maximum, 67%) and contained about 6 mol% Mg. Experiments show that in artificial seawaters having different Mg/Ca molar ratios but otherwise having the ionic strength and chemical composition of modern seawater, aragonite can precipitate inorganically when the Mg/Ca molar ratio is above 2. The fact that Halimeda produces slightly more aragonite than calcite when the ambient Mg/Ca molar ratio is 1.5 indicates that it does exert a

  4. Expulsion of Symbiotic Algae during Feeding by the Green Hydra – a Mechanism for Regulating Symbiont Density?

    PubMed Central

    Fishman, Yelena; Zlotkin, Eliahu; Sher, Daniel

    2008-01-01

    Background Algal-cnidarian symbiosis is one of the main factors contributing to the success of cnidarians, and is crucial for the maintenance of coral reefs. While loss of the symbionts (such as in coral bleaching) may cause the death of the cnidarian host, over-proliferation of the algae may also harm the host. Thus, there is a need for the host to regulate the population density of its symbionts. In the green hydra, Chlorohydra viridissima, the density of symbiotic algae may be controlled through host modulation of the algal cell cycle. Alternatively, Chlorohydra may actively expel their endosymbionts, although this phenomenon has only been observed under experimentally contrived stress conditions. Principal Findings We show, using light and electron microscopy, that Chlorohydra actively expel endosymbiotic algal cells during predatory feeding on Artemia. This expulsion occurs as part of the apocrine mode of secretion from the endodermal digestive cells, but may also occur via an independent exocytotic mechanism. Significance Our results demonstrate, for the first time, active expulsion of endosymbiotic algae from cnidarians under natural conditions. We suggest this phenomenon may represent a mechanism whereby cnidarians can expel excess symbiotic algae when an alternative form of nutrition is available in the form of prey. PMID:18596972

  5. Assessing the combined effects from two kinds of cephalosporins on green alga (Chlorella pyrenoidosa) based on response surface methodology.

    PubMed

    Guo, Ruixin; Xie, Weishu; Chen, Jianqiu

    2015-04-01

    The present work evaluated the combined effects of cefradine and ceftazidime on the green alga Chlorella pyrenoidosa using response surface methodologies (RSM). After a 48 h-exposure, the population growth rate (PGR), the chlorophyll-a content and the SOD content of the alga increased with increased concentrations of two antibiotics. However, the three responses did not continue to demonstrate significant increases once antibiotic concentrations exceed a moderate level. Three two order polynomial regression equations were obtained to describe well the relationship between the responses of the alga and the two antibiotics' concentration (R(2) = 0.9997, 0.9292 and 0.9039, respectively). Three 3 D-surface graphs and their contour plots showed directly the changing trends of the alga under the combined effects of two antibiotics. This study for the first time employed the RSM in ecotoxicology, which indicated that the RSM should be placed under a feasible and a potential application prospect in toxicity assessment. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Effects of lead on growth, photosynthetic characteristics and production of reactive oxygen species of two freshwater green algae.

    PubMed

    Dao, Ly H T; Beardall, John

    2016-03-01

    In the natural environment, heavy metal contamination can occur as long-term pollution of sites or as pulses of pollutants from wastewater disposal. In this study two freshwater green algae, Chlorella sp. FleB1 and Scenedesmus YaA6, were isolated from lead-polluted water samples and the effects of 24 h vs 4 and 8 d exposure of cultures to lead on growth, photosynthetic physiology and production of reactive oxygen species (ROS) of these algae were investigated. In Chlorella sp. FleB1, there was agreement between lead impacts on chlorophyll content, photosynthesis and growth in most case. However, in Scenedesmus acutus YaA6 growth was inhibited at lower lead concentrations (0.03-0.87 × 10(-9) M), under which ROS, measured by 2',7' dichlorodihydrofluorescein diacetate fluorescence, were 4.5 fold higher than in controls but photosynthesis was not affected, implying that ROS had played a role in the growth inhibition that did not involve direct effects on photosynthesis. Effects of short-term (5 h, 24 h) vs long-term (4 d and 8 d) exposure to lead were also compared between the two algae. The results contribute to our understanding of the mechanisms of lead toxicity to algae.

  7. Survival and reproduction of some blue-green and green algae as affected by sewage water, fertilizer factory effluent, brassica oil, phenol, toluene and benzene.

    PubMed

    Agrawal, S C; Gupta, S

    2009-01-01

    Fourteen blue-green and green algae survived for widely different time periods ranging between 22-102 d in control culture medium. Irrespective of their long or short survival period in control cultures, their pro- or eukaryotic nature, their different morphological types or natural habitats, they all survived for a short time period ranging between 3-8 d in sewage water, 5-10 d in fertilizer factory effluent, (1/4)-2 d in brassica oil, (1/2)-2 d in phenol, 1-3 d in toluene, and 1-4 d in benzene (showing the relative toxicity of different chemicals to different algae, and the antialgal nature of brassica oil). Dilution decreased the toxicity of these agents very little, indicating that they all were very toxic to algae. None of the agent induced the formation of any reproductive or dormant cells. Sewage water, fertilizer factory effluent, brassica oil and/or benzene favored the formation of necridia cells in Phormidium bohneri, P. foveolarum, Microcoleus chthonoplastes, Lyngbya birgei, and L. major filaments. Scenedesmus quadricauda shed off all spines earlier, Hormidium flaccidum fragmented less or not at all, Scytonema millei formed no false branch and heterocyst, Aphanothece pallida and Gloeocapsa atrata cells did not divide, Cosmarium granatum cells did not form any zygospore and Oedogonium sp. not any oogonia-like cells under all or most of treatments with 25-100 % sewage water, 1-100 % fertilizer factory effluent, 1-100 % brassica oil, 25-100 % phenol, toluene and benzene.

  8. Enhanced acetyl-CoA production is associated with increased triglyceride accumulation in the green alga Chlorella desiccata.

    PubMed

    Avidan, Omri; Brandis, Alexander; Rogachev, Ilana; Pick, Uri

    2015-07-01

    Triglycerides (TAGs) from microalgae can be utilized as food supplements and for biodiesel production, but little is known about the regulation of their biosynthesis. This work aimed to test the relationship between acetyl-CoA (Ac-CoA) levels and TAG biosynthesis in green algae under nitrogen deprivation. A novel, highly sensitive liquid chromatography mass spectrometry (LC-MS/MS) technique enabled us to determine the levels of Ac-CoA, malonyl-CoA, and unacetylated (free) CoA in green microalgae. A comparative study of three algal species that differ in TAG accumulation levels shows that during N starvation, Ac-CoA levels rapidly rise, preceding TAG accumulation in all tested species. The levels of Ac-CoA in the high TAG accumulator Chlorella desiccata exceed the levels in the moderate TAG accumulators Dunaliella tertiolecta and Chlamydomonas reinhardtii. Similarly, malonyl-CoA and free CoA levels also increase, but to lower extents. Calculated cellular concentrations of Ac-CoA are far lower than reported K mAc-CoA values of plastidic Ac-CoA carboxylase (ptACCase) in plants. Transcript level analysis of plastidic pyruvate dehydrogenase (ptPDH), the major chloroplastic Ac-CoA producer, revealed rapid induction in parallel with Ac-CoA accumulation in C. desiccata, but not in D. tertiolecta or C. reinhardtii. It is proposed that the capacity to accumulate high TAG levels in green algae critically depends on their ability to divert carbon flow towards Ac-CoA. This requires elevation of the chloroplastic CoA pool level and enhancement of Ac-CoA biosynthesis. These conclusions may have important implications for future genetic manipulation to enhance TAG biosynthesis in green algae.

  9. Enhanced acetyl-CoA production is associated with increased triglyceride accumulation in the green alga Chlorella desiccata

    PubMed Central

    Avidan, Omri; Brandis, Alexander; Rogachev, Ilana; Pick, Uri

    2015-01-01

    Triglycerides (TAGs) from microalgae can be utilized as food supplements and for biodiesel production, but little is known about the regulation of their biosynthesis. This work aimed to test the relationship between acetyl-CoA (Ac-CoA) levels and TAG biosynthesis in green algae under nitrogen deprivation. A novel, highly sensitive liquid chromatography mass spectrometry (LC-MS/MS) technique enabled us to determine the levels of Ac-CoA, malonyl-CoA, and unacetylated (free) CoA in green microalgae. A comparative study of three algal species that differ in TAG accumulation levels shows that during N starvation, Ac-CoA levels rapidly rise, preceding TAG accumulation in all tested species. The levels of Ac-CoA in the high TAG accumulator Chlorella desiccata exceed the levels in the moderate TAG accumulators Dunaliella tertiolecta and Chlamydomonas reinhardtii. Similarly, malonyl-CoA and free CoA levels also increase, but to lower extents. Calculated cellular concentrations of Ac-CoA are far lower than reported K mAc-CoA values of plastidic Ac-CoA carboxylase (ptACCase) in plants. Transcript level analysis of plastidic pyruvate dehydrogenase (ptPDH), the major chloroplastic Ac-CoA producer, revealed rapid induction in parallel with Ac-CoA accumulation in C. desiccata, but not in D. tertiolecta or C. reinhardtii. It is proposed that the capacity to accumulate high TAG levels in green algae critically depends on their ability to divert carbon flow towards Ac-CoA. This requires elevation of the chloroplastic CoA pool level and enhancement of Ac-CoA biosynthesis. These conclusions may have important implications for future genetic manipulation to enhance TAG biosynthesis in green algae. PMID:25922486

  10. Toxicity assessment of manufactured nanomaterials using the unicellular green alga Chlamydomonas reinhardtii.

    PubMed

    Wang, Jiangxin; Zhang, Xuezhi; Chen, Yongsheng; Sommerfeld, Milton; Hu, Qiang

    2008-10-01

    With the rapid development of nanotechnology, there is an increasing risk of human and environmental exposure to nanotechnology-based materials and products. As water resources are particularly vulnerable to direct and indirect contamination of nonomaterials (NMs), the potential toxicity and environmental implication of NMs to aquatic organisms must be evaluated. In this study, we assessed potential toxicity of two commercially used NMs, titanium dioxide (TiO(2)) and quantum dots (QDs), using the unicellular green alga Chlamydomonas reinhartii as a model system. The response of the organism to NMs was assessed at physiological, biochemical, and molecular genetic levels. Growth kinetics showed that growth inhibition occurred during the first two to three days of cultivation in the presence of TiO(2) or QDs. Measurements of lipid peroxidation measurement indicated that oxidative stress of the cells occurred as early as 6 h after exposure to TiO(2) or QDs. The transcriptional expression profiling of four stress response genes (sod1, gpx, cat, and ptox2) revealed that transient up-regulation of these genes occurred in cultures containing as low as 1.0 mg L(-1) of TiO(2) or 0.1 mg L(-1) of QDs, and the maximum transcripts of cat, sod1, gpx, and ptox2 occurred at 1.5, 3, 3, and 6 h, respectively, and were proportional to the initial concentration of the NMs. As the cultures continued, recovery in growth was observed and the extent of recovery, as indicated by the final cell concentration, was dosage-dependent. QDs were found to be more toxic to Chlamydomonas cells than TiO(2) under our experimental conditions.

  11. UV radiation-induced accumulation of photoprotective compounds in the green alga Tetraspora sp. CU2551.

    PubMed

    Rastogi, Rajesh P; Incharoensakdi, Aran

    2013-09-01

    The effect of UV radiation on the accumulation of novel mycosporine-like amino acids (MAAs) along with their photoprotective function was investigated in the green alga Tetraspora sp. CU2551. No UV-absorbing compound was detected in this organism growing under normal light condition while two MAAs with absorption maxima at 324 nm and 322 nm were found to be accumulated after UV irradiation. The effects of UV exposure time with different cut-off filter foils namely 295 (PAR + UV-A + UV-B), 320 (PAR + UV-A) and 395 nm (PAR only) were studied on induction of the synthesis of these MAAs. Concentration of MAAs was found to increase with increase in exposure time under UV radiation. Furthermore, the antioxidant and photoprotective action of these MAAs was also investigated. The role of MAAs in diminishing the UV-induced production of ROS in vivo was also demonstrated using the oxidant-sensing probe 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA) and results obtained supported the results of DPPH free radical scavenging assay. The MAAs also exhibited efficient photoprotective ability on Escherichia coli cells against UV-B stress. Thus, the MAAs in Tetraspora sp. CU2551 may act as efficient antioxidants as well as UV-sunscreen. This is the first report for the UV-induced synthesis and co-accumulation of these MAAs and their photoprotective actions in Tetraspora sp. which is a member of the class Chlorophyceae. Moreover, UV-induced accumulation as well as photoprotective function of these compounds may facilitate this chlorophyte to perform important ecological functions in harsh environmental conditions with high UV-B fluxes in their brightly lit habitats.

  12. The effect of lanthanides on photosynthesis, growth, and chlorophyll profile of the green alga Desmodesmus quadricauda.

    PubMed

    Řezanka, Tomáš; Kaineder, Katrin; Mezricky, Dana; Řezanka, Michal; Bišová, Kateřina; Zachleder, Vilém; Vítová, Milada

    2016-12-01

    Lanthanides (La, Gd, Nd, Ce) accumulated in the green alga Desmodesmus quadricauda but their intracellular localizations were distinctly different: lanthanum and gadolinium were localized in cytoplasm, while neodymium and cerium were in the chloroplast. The effect of lanthanum and neodymium, as representatives of these two groups, on growth, chlorophyll content and photosynthetic rate at different light intensities was studied. At the lowest light intensity used (50 µmol photons m(-2) s(-1)), in the presence of lanthanides (Nd), growth was enhanced by as much as 36 % over lanthanide free control, and the photosynthetic rate increased by up to 300 %. At high light intensities (238, 460, and 750 µmol photons m(-2) s(-1)), photosynthetic rate increased markedly, but there was no significant difference between rates in the presence or absence of lanthanides. However, growth, measured as a percentage of dry weight, if compared with lanthanide free control, increased at all light intensities (31, 39, and 20 %, respectively). The total amount of chlorophyll after lanthanide treatment increased by up to 21 % relative to the control culture, mainly due to an increase in the level of chlorophyll b. Addition of lanthanides caused a change in the chlorophyll a/b ratio from 4.583 in control cultivation, to 1.05. Possible mechanisms of lanthanide-induced photosynthetic change, alterations in photosynthetic structures, and increases in growth are discussed and compared with findings in higher plants. The hypothesis that the lanthanide effect could be due to formation of lanthanide-pheophytins was not confirmed as lanthanide pheophytins were not found in D. quadricauda. Furthermore, we have shown that the preferential incorporation of heavy isotopes of magnesium, namely (25)Mg and (26)Mg, into chlorophyll during photosynthesis that occurred in controls was diminished in the presence of lanthanides.

  13. Sensitivity of the green algae Chlamydomonas reinhardtii to gamma radiation: Photosynthetic performance and ROS formation.

    PubMed

    Gomes, Tânia; Xie, Li; Brede, Dag; Lind, Ole-Christian; Solhaug, Knut Asbjørn; Salbu, Brit; Tollefsen, Knut Erik

    2017-02-01

    The aquatic environment is continuously exposed to ionizing radiation from both natural and anthropogenic sources, making the characterization of ecological and health risks associated with radiation of large importance. Microalgae represent the main source of biomass production in the aquatic ecosystem, thus becoming a highly relevant biological model to assess the impacts of gamma radiation. However, little information is available on the effects of gamma radiation on microalgal species, making environmental radioprotection of this group of species challenging. In this context, the present study aimed to improve the understanding of the effects and toxic mechanisms of gamma radiation in the unicellular green algae Chlamydomonas reinhardtii focusing on the activity of the photosynthetic apparatus and ROS formation. Algal cells were exposed to gamma radiation (0.49-1677mGy/h) for 6h and chlorophyll fluorescence parameters obtained by PAM fluorometry, while two fluorescent probes carboxy-H2DFFDA and DHR 123 were used for the quantification of ROS. The alterations seen in functional parameters of C. reinhardtii PSII after 6h of exposure to gamma radiation showed modifications of PSII energy transfer associated with electron transport and energy dissipation pathways, especially at the higher dose rates used. Results also showed that gamma radiation induced ROS in a dose-dependent manner under both light and dark conditions. The observed decrease in photosynthetic efficiency seems to be connected to the formation of ROS and can potentially lead to oxidative stress and cellular damage in chloroplasts. To our knowledge, this is the first report on changes in several chlorophyll fluorescence parameters associated with photosynthetic performance and ROS formation in microalgae after exposure to gamma radiation.

  14. A new paradigm for producing astaxanthin from the unicellular green alga Haematococcus pluvialis.

    PubMed

    Zhang, Zhen; Wang, Baobei; Hu, Qiang; Sommerfeld, Milton; Li, Yuanguang; Han, Danxiang

    2016-10-01

    The unicellular green alga Haematococcus pluvialis has been exploited as a cell factory to produce the high-value antioxidant astaxanthin for over two decades, due to its superior ability to synthesize astaxanthin under adverse culture conditions. However, slow vegetative growth under favorable culture conditions and cell deterioration or death under stress conditions (e.g., high light, nitrogen starvation) has limited the astaxanthin production. In this study, a new paradigm that integrated heterotrophic cultivation, acclimation of heterotrophically grown cells to specific light/nutrient regimes, followed by induction of astaxanthin accumulation under photoautotrophic conditions was developed. First, the environmental conditions such as pH, carbon source, nitrogen regime, and light intensity, were optimized to induce astaxanthin accumulation in the dark-grown cells. Although moderate astaxanthin content (e.g., 1% of dry weight) and astaxanthin productivity (2.5 mg L(-1)  day(-1) ) were obtained under the optimized conditions, a considerable number of cells died off when subjected to stress for astaxanthin induction. To minimize the susceptibility of dark-grown cells to light stress, the algal cells were acclimated, prior to light induction of astaxanthin biosynthesis, under moderate illumination in the presence of nitrogen. Introduction of this strategy significantly reduced the cell mortality rate under high-light and resulted in increased cellular astaxanthin content and astaxanthin productivity. The productivity of astaxanthin was further improved to 10.5 mg L(-1)  day(-1) by implementation of such a strategy in a bubbling column photobioreactor. Biochemical and physiological analyses suggested that rebuilding of photosynthetic apparatus including D1 protein and PsbO, and recovery of PSII activities, are essential for acclimation of dark-grown cells under photo-induction conditions. Biotechnol. Bioeng. 2016;113: 2088-2099. © 2016 The Authors

  15. A new paradigm for producing astaxanthin from the unicellular green alga Haematococcus pluvialis

    PubMed Central

    Zhang, Zhen; Wang, Baobei; Hu, Qiang; Sommerfeld, Milton

    2016-01-01

    ABSTRACT The unicellular green alga Haematococcus pluvialis has been exploited as a cell factory to produce the high‐value antioxidant astaxanthin for over two decades, due to its superior ability to synthesize astaxanthin under adverse culture conditions. However, slow vegetative growth under favorable culture conditions and cell deterioration or death under stress conditions (e.g., high light, nitrogen starvation) has limited the astaxanthin production. In this study, a new paradigm that integrated heterotrophic cultivation, acclimation of heterotrophically grown cells to specific light/nutrient regimes, followed by induction of astaxanthin accumulation under photoautotrophic conditions was developed. First, the environmental conditions such as pH, carbon source, nitrogen regime, and light intensity, were optimized to induce astaxanthin accumulation in the dark‐grown cells. Although moderate astaxanthin content (e.g., 1% of dry weight) and astaxanthin productivity (2.5 mg L−1 day−1) were obtained under the optimized conditions, a considerable number of cells died off when subjected to stress for astaxanthin induction. To minimize the susceptibility of dark‐grown cells to light stress, the algal cells were acclimated, prior to light induction of astaxanthin biosynthesis, under moderate illumination in the presence of nitrogen. Introduction of this strategy significantly reduced the cell mortality rate under high‐light and resulted in increased cellular astaxanthin content and astaxanthin productivity. The productivity of astaxanthin was further improved to 10.5 mg L−1 day−1 by implementation of such a strategy in a bubbling column photobioreactor. Biochemical and physiological analyses suggested that rebuilding of photosynthetic apparatus including D1 protein and PsbO, and recovery of PSII activities, are essential for acclimation of dark‐grown cells under photo‐induction conditions. Biotechnol. Bioeng. 2016;113: 2088–2099.

  16. Biosorption of copper, cobalt and nickel by marine green alga Ulva reticulata in a packed column.

    PubMed

    Vijayaraghavan, K; Jegan, J; Palanivelu, K; Velan, M

    2005-07-01

    Biosorption of copper, cobalt and nickel by marine green alga Ulva reticulata were investigated in a packed bed up-flow column. The experiments were conducted to study the effect of important design parameters such as bed height and flow rate. At a bed height of 25 cm, the metal-uptake capacity of U. reticulata for copper, cobalt and nickel was found to be 56.3+/-0.24, 46.1+/-0.07 and 46.5+/-0.08 mgg(-1), respectively. The Bed Depth Service Time (BDST) model was used to analyze the experimental data. The computed sorption capacity per unit bed volume (N0) was 2580, 2245 and 1911 mgl(-1) for copper, cobalt and nickel, respectively. The rate constant (K(a)) was recorded as 0.063, 0.081 and 0.275 lmg(-1)h(-1) for copper, cobalt and nickel, respectively. In flow rate experiments, the results confirmed that the metal uptake capacity and the metal removal efficiency of U. reticulata decreased with increasing flow rate. The Thomas model was used to fit the column biosorption data at different flow rates and model constants were evaluated. The column regeneration studies were carried out for three sorption-desorption cycles. The elutant used for the regeneration of the biosorbent was 0.1 M CaCl2 at pH 3 adjusted using HCl. For all the metal ions, a decreased breakthrough time and an increased exhaustion time were observed as the regeneration cycles progressed, which also resulted in a broadened mass transfer zone. The pH variations during both sorption and desorption process have been reported.

  17. Blue-Green Algae Inhibit the Development of Atherosclerotic Lesions in Apolipoprotein E Knockout Mice

    PubMed Central

    Ku, Chai Siah; Kim, Bohkyung; Pham, Tho X.; Yang, Yue; Wegner, Casey J.; Park, Young-Ki; Balunas, Marcy

    2015-01-01

    Abstract Hyperlipidemia and inflammation contribute to the development of atherosclerotic lesions. Our objective was to determine antiatherogenic effect of edible blue-green algae (BGA) species, that is, Nostoc commune var. sphaeroides Kützing (NO) and Spirulina platensis (SP), in apolipoprotein E knockout (ApoE−/−) mice, a well-established mouse model of atherosclerosis. Male ApoE−/− mice were fed a high-fat/high-cholesterol (HF/HC, 15% fat and 0.2% cholesterol by wt) control diet or a HF/HC diet supplemented with 5% (w/w) of NO or SP powder for 12 weeks. Plasma total cholesterol (TC) and triglycerides (TG) were measured, and livers were analyzed for histology and gene expression. Morphometric analysis for lesions and immunohistochemical analysis for CD68 were conducted in the aorta and the aortic root. NO supplementation significantly decreased plasma TC and TG, and liver TC, compared to control and SP groups. In the livers of NO-fed mice, less lipid droplets were present with a concomitant decrease in fatty acid synthase protein levels than the other groups. There was a significant increase in hepatic low-density lipoprotein receptor protein levels in SP-supplemented mice than in control and NO groups. Quantification of aortic lesions by en face analysis demonstrated that both NO and SP decreased aortic lesion development to a similar degree compared with control. While lesions in the aortic root were not significantly different between groups, the CD68-stained area in the aortic root was significantly lowered in BGA-fed mice than controls. In conclusion, both NO and SP supplementation decreased the development of atherosclerotic lesions, suggesting that they may be used as a natural product for atheroprotection. PMID:26566121

  18. Construction of a growth model in the green alga Tetraselmis subcordiformis using a response surface approach

    NASA Astrophysics Data System (ADS)

    Wang, Hui; Niu, Jingyan; Liu, Jiahui; Yang, Hongshuai; Liu, Zhigang

    2016-06-01

    The green alga Tetraselmis subcordiformis has been widely used as a quality live food for aquaculture species, and also has been studied as a model organism for the photo-biological production of hydrogen. We attempted to quantify the relationship between T. subcordiformis specific growth rate (SGR) and three important environmental factors (temperature, salinity, and pH) using the central composite design and response surface method under laboratory conditions. The results showed that the linear effects of temperature and salinity were significant (P< 0.05), and they were equally important in impacting T. subcordiformis specific growth; the linear effect of pH was not significant (P>0.05); the interactive effect of temperature and pH was significant (P<0.05), whereas the temperature × salinity and salinity × pH interactions were not significant (P>0.05); all of the quadratic effects of the three factors were significant (P<0.05). A model equation for specific growth rate with the three factors was established, with the unadjusted and predictive R 2 as high as 0.990 and 0.921, respectively, suggesting that the model was a very good fit and that it could be used to predict SGR. Through optimizing the reliable model, an optimal 3-factor combination of 25 °C/35 of salinity/pH 7.9 was obtained, at which the maximum specific growth rate (0.65) was recorded, with a desirability value of 93.8%. These experimental results could serve as guidelines for increasing T. subcordiformis production efficiency.

  19. Assessing potential health risks from microcystin toxins in blue-green algae dietary supplements.

    PubMed Central

    Gilroy, D J; Kauffman, K W; Hall, R A; Huang, X; Chu, F S

    2000-01-01

    The presence of blue-green algae (BGA) toxins in surface waters used for drinking water sources and recreation is receiving increasing attention around the world as a public health concern. However, potential risks from exposure to these toxins in contaminated health food products that contain BGA have been largely ignored. BGA products are commonly consumed in the United States, Canada, and Europe for their putative beneficial effects, including increased energy and elevated mood. Many of these products contain Aphanizomenon flos-aquae, a BGA that is harvested from Upper Klamath Lake (UKL) in southern Oregon, where the growth of a toxic BGA, Microcystis aeruginosa, is a regular occurrence. M. aeruginosa produces compounds called microcystins, which are potent hepatotoxins and probable tumor promoters. Because M. aeruginosa coexists with A. flos-aquae, it can be collected inadvertently during the harvesting process, resulting in microcystin contamination of BGA products. In fall 1996, the Oregon Health Division learned that UKL was experiencing an extensive M. aeruginosa bloom, and an advisory was issued recommending against water contact. The advisory prompted calls from consumers of BGA products, who expressed concern about possible contamination of these products with microcystins. In response, the Oregon Health Division and the Oregon Department of Agriculture established a regulatory limit of 1 microg/g for microcystins in BGA-containing products and tested BGA products for the presence of microcystins. Microcystins were detected in 85 of 87 samples tested, with 63 samples (72%) containing concentrations > 1 microg/g. HPLC and ELISA tentatively identified microcystin-LR, the most toxic microcystin variant, as the predominant congener. Images Figure 1 Figure 2 PMID:10811570

  20. Effects of chlorpyrifos on the growth and ultrastructure of green algae, Ankistrodesmus gracilis.

    PubMed

    Asselborn, Viviana; Fernández, Carolina; Zalocar, Yolanda; Parodi, Elisa R

    2015-10-01

    The effect of the organophosphorus insecticide chlorpyrifos on the growth, biovolume, and ultrastructure of the green microalga Ankistrodesmus gracilis was evaluated. Concentrations of 9.37, 18.75, 37.5, 75 and 150mgL(-1) of chlorpyrifos were assayed along with a control culture. At the end of the bioassay the ultrastructure of algal cells from control culture and from cultures exposed to 37.5 and 150mgL(-1) was observed under transmission (TEM) and scanning electron microscopy (SEM). After 24 and 48h, treatments with 75 and 150mgL(-1) inhibited the growth of A. gracilis; whereas after 72 and 96h, all the treatments except at 9.37mgL(-1) significantly affected the algae growth. The effective concentration 50 (EC50) after 96h was 22.44mgL(-1) of chlorpyrifos. After the exposure to the insecticide, an increase in the biovolume was observed, with a larger increase in cells exposed to 75 and 150mgL(-1). Radical changes were observed in the ultrastructure of cells exposed to chlorpyrifos. The insecticide affected the cell shape and the distribution of the crests in the wall. At 37.5mgL(-1) electodense bodies were observed along with an increase in the size and number of starch granules. At 150mgL(-1) such bodies occupied almost the whole cytoplasm together with lipids and remains of thylakoids. Autospores formation occurred normally at 37.5mgL(-1) while at 150mgL(-1) karyokinesis occurred, but cell-separation-phase was inhibited. The present study demonstrates that the exposure of phytoplankton to the insecticide chlorpyrifos leads to effects observed at both cellular and population level.

  1. Blue-Green Algae Inhibit the Development of Atherosclerotic Lesions in Apolipoprotein E Knockout Mice.

    PubMed

    Ku, Chai Siah; Kim, Bohkyung; Pham, Tho X; Yang, Yue; Wegner, Casey J; Park, Young-Ki; Balunas, Marcy; Lee, Ji-Young

    2015-12-01

    Hyperlipidemia and inflammation contribute to the development of atherosclerotic lesions. Our objective was to determine antiatherogenic effect of edible blue-green algae (BGA) species, that is, Nostoc commune var. sphaeroides Kützing (NO) and Spirulina platensis (SP), in apolipoprotein E knockout (ApoE(-/-)) mice, a well-established mouse model of atherosclerosis. Male ApoE(-/-) mice were fed a high-fat/high-cholesterol (HF/HC, 15% fat and 0.2% cholesterol by wt) control diet or a HF/HC diet supplemented with 5% (w/w) of NO or SP powder for 12 weeks. Plasma total cholesterol (TC) and triglycerides (TG) were measured, and livers were analyzed for histology and gene expression. Morphometric analysis for lesions and immunohistochemical analysis for CD68 were conducted in the aorta and the aortic root. NO supplementation significantly decreased plasma TC and TG, and liver TC, compared to control and SP groups. In the livers of NO-fed mice, less lipid droplets were present with a concomitant decrease in fatty acid synthase protein levels than the other groups. There was a significant increase in hepatic low-density lipoprotein receptor protein levels in SP-supplemented mice than in control and NO groups. Quantification of aortic lesions by en face analysis demonstrated that both NO and SP decreased aortic lesion development to a similar degree compared with control. While lesions in the aortic root were not significantly different between groups, the CD68-stained area in the aortic root was significantly lowered in BGA-fed mice than controls. In conclusion, both NO and SP supplementation decreased the development of atherosclerotic lesions, suggesting that they may be used as a natural product for atheroprotection.

  2. Hypocholesterolemic effect of Nostoc commune var. sphaeroides Kützing, an edible blue-green alga.

    PubMed

    Rasmussen, Heather E; Blobaum, Kara R; Jesch, Elliot D; Ku, Chai Siah; Park, Young-Ki; Lu, Fan; Carr, Timothy P; Lee, Ji-Young

    2009-10-01

    Intake of an edible blue-green alga Nostoc commune var. sphaeroides Kützing (N. Commune) has been shown to lower plasma total cholesterol concentration, but the mechanisms behind the hypocholesterolemic effect have not been elucidated. To elucidate the mechanisms underlying the cholesterol-lowering effect of N. commune in mice. Male C57BL/6J mice were fed the AIN-93 M diet supplemented with 0 or 5% (wt/wt) dried N. Commune for 4 weeks. Lipid levels in the plasma and liver, intestinal cholesterol absorption and fecal sterol excretion were measured. Expression of hepatic and intestinal genes involved in cholesterol metabolism was evaluated by quantitative realtime PCR. N. commune supplementation significantly reduced total plasma cholesterol and triglyceride concentrations by approximately 20% compared to controls. Intestinal cholesterol absorption was significantly decreased, while fecal neutral sterol output was significantly increased in N. commune-fed mice. mRNA levels of the cholesterol transporters such as Niemann Pick C1 Like 1, scavenger receptor class B type 1, ATP-binding cassette transporters G5 and A1 in small intestine were not significantly different between two groups. Hepatic lipid contents including total cholesterol, triglyceride and free cholesterol in N. commune-fed mice were not significantly altered. However, the expression of cholesterol modulating genes including sterol regulatory element binding protein-2 and 3-hydroxy-3-methylglutaryl coenzyme A reductase were significantly increased in mice fed N. commune. N. commune supplementation exerted a hypocholesterolemic effect in mice, largely in part, by reducing intestinal cholesterol absorption and promoting fecal neutral sterol excretion.

  3. Increased temperature mitigates the effects of ocean acidification in calcified green algae ( Halimeda spp.)

    NASA Astrophysics Data System (ADS)

    Campbell, Justin E.; Fisch, Jay; Langdon, Chris; Paul, Valerie J.

    2016-03-01

    The singular and interactive effects of ocean acidification and temperature on the physiology of calcified green algae ( Halimeda incrassata, H. opuntia, and H. simulans) were investigated in a fully factorial, 4-week mesocosm experiment. Individual aquaria replicated treatment combinations of two pH levels (7.6 and 8.0) and two temperatures (28 and 31 °C). Rates of photosynthesis, respiration, and calcification were measured for all species both prior to and after treatment exposure. Pre-treatment measurements revealed that H. incrassata displayed higher biomass-normalized rates of photosynthesis and calcification (by 55 and 81 %, respectively) relative to H. simulans and H. opuntia. Furthermore, prior to treatment exposure, photosynthesis was positively correlated to calcification, suggesting that the latter process may be controlled by photosynthetic activity in this group. After treatment exposure, net photosynthesis was unaltered by pH, yet significantly increased with elevated temperature by 58, 38, and 37 % for H. incrassata, H. simulans, and H. opuntia, respectively. Both pH and temperature influenced calcification, but in opposing directions. On average, calcification declined by 41 % in response to pH reduction, but increased by 49 % in response to elevated temperature. Within each pH treatment, elevated temperature increased calcification by 23 % (at pH 8.0) and 74 % (at pH 7.6). Interactions between pH, temperature, and/or species were not observed. This work demonstrates that, in contrast to prior studies, increased temperature may serve to enhance the metabolic performance (photosynthesis and calcification) of some marine calcifiers, despite elevated carbon dioxide concentrations. Thus, in certain cases, ocean warming may mitigate the negative effects of acidification.

  4. Construction of a growth model in the green alga Tetraselmis subcordiformis using a response surface approach

    NASA Astrophysics Data System (ADS)

    Wang, Hui; Niu, Jingyan; Liu, Jiahui; Yang, Hongshuai; Liu, Zhigang

    2017-05-01

    The green alga Tetraselmis subcordiformis has been widely used as a quality live food for aquaculture species, and also has been studied as a model organism for the photo-biological production of hydrogen. We attempted to quantify the relationship between T. subcordiformis specific growth rate (SGR) and three important environmental factors (temperature, salinity, and pH) using the central composite design and response surface method under laboratory conditions. The results showed that the linear effects of temperature and salinity were significant ( P< 0.05), and they were equally important in impacting T. subcordiformis specific growth; the linear effect of pH was not significant ( P>0.05); the interactive effect of temperature and pH was significant ( P<0.05), whereas the temperature × salinity and salinity × pH interactions were not significant ( P>0.05); all of the quadratic effects of the three factors were significant ( P<0.05). A model equation for specific growth rate with the three factors was established, with the unadjusted and predictive R 2 as high as 0.990 and 0.921, respectively, suggesting that the model was a very good fit and that it could be used to predict SGR. Through optimizing the reliable model, an optimal 3-factor combination of 25 °C/35 of salinity/pH 7.9 was obtained, at which the maximum specific growth rate (0.65) was recorded, with a desirability value of 93.8%. These experimental results could serve as guidelines for increasing T. subcordiformis production efficiency.

  5. Assessing potential health risks from microcystin toxins in blue-green algae dietary supplements.

    PubMed

    Gilroy, D J; Kauffman, K W; Hall, R A; Huang, X; Chu, F S

    2000-05-01

    The presence of blue-green algae (BGA) toxins in surface waters used for drinking water sources and recreation is receiving increasing attention around the world as a public health concern. However, potential risks from exposure to these toxins in contaminated health food products that contain BGA have been largely ignored. BGA products are commonly consumed in the United States, Canada, and Europe for their putative beneficial effects, including increased energy and elevated mood. Many of these products contain Aphanizomenon flos-aquae, a BGA that is harvested from Upper Klamath Lake (UKL) in southern Oregon, where the growth of a toxic BGA, Microcystis aeruginosa, is a regular occurrence. M. aeruginosa produces compounds called microcystins, which are potent hepatotoxins and probable tumor promoters. Because M. aeruginosa coexists with A. flos-aquae, it can be collected inadvertently during the harvesting process, resulting in microcystin contamination of BGA products. In fall 1996, the Oregon Health Division learned that UKL was experiencing an extensive M. aeruginosa bloom, and an advisory was issued recommending against water contact. The advisory prompted calls from consumers of BGA products, who expressed concern about possible contamination of these products with microcystins. In response, the Oregon Health Division and the Oregon Department of Agriculture established a regulatory limit of 1 microg/g for microcystins in BGA-containing products and tested BGA products for the presence of microcystins. Microcystins were detected in 85 of 87 samples tested, with 63 samples (72%) containing concentrations > 1 microg/g. HPLC and ELISA tentatively identified microcystin-LR, the most toxic microcystin variant, as the predominant congener.

  6. Ornithinimicrobium algicola sp. nov., a marine actinobacterium isolated from the green alga of the genus Ulva.

    PubMed

    Ramaprasad, E V V; Sasikala, Ch; Ramana, Ch V

    2015-12-01

    A Gram-staining-positive, non-spore-forming actinobacterium, strain JC311T, isolated from marine green alga of the genus Ulva was studied to examine its taxonomic position. On the basis of the 16S rRNA gene sequence similarity studies, strain JC311T was shown represent a member of the genus Ornithinimicrobium and to be closely related to Ornithinimicrobium pekingense LW6T (98.6 %), Ornithinimicrobium kibberense K22-20T (98.3 %) and Ornithinimicrobium humiphilum HKI 0124T (98.1 %). However, strain JC311T showed less than 22 % DNA reassociation value (based on DNA-DNA hybridization) with O. pekingense JCM14001T, O. kibberense JCM12763T and O. humiphilum KCTC19901T. The predominant menaquinone of strain JC311T was MK-8(H4). The peptidoglycan contained l-ornithine as the diagnostic diamino acid. The polar lipid profile consisted of the lipids diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, glycophospholipid, aminophospholipid, phospholipid and two unidentified lipids. The major fatty acids iso-C16 : 0, iso-C15 : 0, iso-C17 : 1ω9c and iso-C17 : 0 were consistent with the fatty acid patterns reported for members of the genus Ornithinimicrobium. The distinct genomic, morphological, physiological and chemotaxonomic differences from the previously described taxa support the classification of JC311T as a representative of a novel species of the genus Ornithinimicrobium, for which we propose the name Ornithinimicrobium algicola sp. nov., with the type strain JC311T ( = KCTC 39559 T =  LMG 28808T).

  7. Olleya algicola sp. nov., a marine bacterium isolated from the green alga Ulva fenestrata.

    PubMed

    Nedashkovskaya, Olga I; Kim, Song-Gun; Zhukova, Natalia V; Mikhailov, Valery V

    2017-07-01

    A strictly aerobic, Gram-stain-negative, rod-shaped, motile by gliding and yellow-pigmented bacterium, designated strain 3Alg 18T, was isolated from the Pacific green alga Ulva fenestrata. Phylogenetic analysis based on 16S rRNA gene sequences showed that the novel strain was affiliated to the family Flavobacteriaceae of the phylum Bacteroidetes, being most closely related to the type strains of recognized species of the genus Olleya, with 16S rRNA gene sequence similarity of 97.9-99.3 %. Strain 3Alg 18T grew in the presence of 0.5-5 % (w/v) NaCl and at 4-37 °C, and hydrolysed aesculin, casein, gelatin, starch and Tweens 20, 40 and 80. The prevalent fatty acids were iso-C15 : 0, iso-C15 : 1 G, iso-C15 : 0 3-OH, iso-C16:0 2-OH, iso-C17 : 0 3-OH, summed feature 3, iso-C16 : 0 3-OH, anteiso-C15 : 0 and C15 : 0. The polar lipid profile contained phosphatidylethanolamine, three unidentified aminolipids and four unidentified lipids. The major respiratory quinone was menaquinone MK-6. The genomic DNA G+C content was 34.6 mol%. On the basis of 16S rRNA gene sequence data, and chemotaxonomic and phenotypic characteristics, strain 3Alg 18T represents a novel species of the genus Olleya, for which the name Olleya algicola sp. nov. is proposed. The type strain is 3Alg 18T (=KCTC 22024T=KMM 6133T).

  8. Phragmoplast of the green alga Spirogyra is functionally distinct from the higher plant phragmoplast

    PubMed Central

    1995-01-01

    Cytokinesis in the green alga Spirogyra (Zygnemataceae) is characterized by centripetal growth of a septum, which impinges on a persistent, centrifugally expanding telophase spindle, leading to a phragmoplast-like structure of potential phylogenetic significance (Fowke, L. C., and J. D. Pickett-Heaps. 1969. J. Phycol. 5:273-281). Combining fluorescent tagging of the cytoskeleton in situ and video- enhanced differential interference contrast microscopy of live cells, the process of cytokinesis was investigated with emphasis on cytoskeletal reorganization and concomitant redistribution of organelles. Based on a sequence of cytoskeletal arrangements and the effects of cytoskeletal inhibitors thereon, cytokinetic progression could be divided into three functional stages with respect to the contribution of microfilaments (MFs) and microtubules (MTs): (1) Initiation: in early prophase, a cross wall initial was formed independently of MFs and MTs at the presumptive site of wall growth. (2) Septum ingrowth: numerous organelles accumulated at the cross wall initial concomitant with reorganization of the extensive peripheral interphase MF array into a distinct circumferential MF array. This array guided the ingrowing septum until it contacted the expanding interzonal MT array. (3) Cross wall closure: MFs at the growing edge of the septum coaligned with and extended along the interzonal MTs toward the daughter nuclei. Thus, actin-based transportation of small organelles during this third stage occurred, in part, along a scaffold previously deployed in space by MTs. Displacement of the nuclei- associated interzonal MT array by centrifugation and depolymerization of the phragmoplast-like structure showed that the success of cytokinesis at the third stage depends on the interaction of both MF and MT cytoskeletons. Important features of the phragmoplast-like structure in Spirogyra were different from the higher plant phragmoplast: in particular, MFs were responsible for the

  9. Artificial microfossils - Experimental studies of permineralization of blue-green algae in silica.

    NASA Technical Reports Server (NTRS)

    Oehler, J. H.; Schopf, J. W.

    1971-01-01

    A technique has been developed to artificially fossilize microscopic algae in crystalline silica under conditions of moderately elevated temperature and pressure. The technique is designed to simulate geochemical processes thought to have resulted in the preservation of organic microfossils in Precambrian bedded cherts. In degree of preservation and mineralogic setting, the artificially permineralized microorganisms are comparable to naturally occurring fossil algae.

  10. Artificial microfossils - Experimental studies of permineralization of blue-green algae in silica.

    NASA Technical Reports Server (NTRS)

    Oehler, J. H.; Schopf, J. W.

    1971-01-01

    A technique has been developed to artificially fossilize microscopic algae in crystalline silica under conditions of moderately elevated temperature and pressure. The technique is designed to simulate geochemical processes thought to have resulted in the preservation of organic microfossils in Precambrian bedded cherts. In degree of preservation and mineralogic setting, the artificially permineralized microorganisms are comparable to naturally occurring fossil algae.

  11. Preferential technological and life cycle environmental performance of chitosan flocculation for harvesting of the green algae Neochloris oleoabundans.

    PubMed

    Beach, Evan S; Eckelman, Matthew J; Cui, Zheng; Brentner, Laura; Zimmerman, Julie B

    2012-10-01

    Dewatering of the green algae Neochloris oleoabundans by flocculation was investigated for chitosan biopolymer, ferric sulfate, and alum. Chitosan was found to be most effective flocculant, with an optimum dose of 100mg/L algae broth. Zeta potential measurements suggest the mechanism involves both adsorption and charge neutralization processes. Life cycle assessment (LCA) was used to compare the chitosan method to other flocculation methods as well as centrifugation and filtration/chamber press processes. LCA showed that among these techniques, flocculation by chitosan is the least energy intensive and had the lowest impacts across all other categories of environmental impacts. The results are discussed in the overall context of biofuel production from algal biomass.

  12. Colony organization in the green alga Botryococcus braunii is specified by a complex extracellular matrix

    SciTech Connect

    Weiss, Taylor L.; Roth, Robyn; Goodson, Carrie; Vithda, Stanislav; Black, Ian; Azadi, Parastoo; Rusch, Jannette; Holzenburg, Andreas; Devarenne, Timothy P.; Goodenough, Ursula

    2012-08-31

    Botryococcus braunii is a colonial green alga whose cells associate via a complex extracellular matrix (ECM) and produce prodigious amounts of liquid hydrocarbons that can be readily converted into conventional combustion engine fuels. We used quickfreeze deep-etch electron microscopy and biochemical/histochemical analysis to elucidate many new features of B. braunii cell/colony organization and composition. Intracellular lipid bodies associate with the chloroplast and endoplasmic reticulum (ER) but show no evidence of being secreted. The ER displays striking fenestrations and forms a continuous subcortical system in direct contact with the cell membrane. The ECM has three distinct components. (i) Each cell is surrounded by a fibrous β-1, 4- and/or β-1, 3-glucan-containing cell wall. (ii) The intracolonial ECM space is filled with a cross-linked hydrocarbon network permeated with liquid hydrocarbons. (iii) Colonies are enclosed in a retaining wall festooned with a fibrillar sheath dominated by arabinose-galactose polysaccharides, which sequesters ECM liquid hydrocarbons. Each cell apex associates with the retaining wall and contributes to its synthesis. Retaining-wall domains also form "drapes" between cells, with some folding in on themselves and penetrating the hydrocarbon interior of a mother colony, partitioning it into daughter colonies. In addition, we propose that retaining-wall components are synthesized in the apical Golgi apparatus, delivered to apical ER fenestrations, and assembled on the surfaces of apical cell walls, where a proteinaceous granular layer apparently participates in fibril morphogenesis. We further propose that hydrocarbons are produced by the nonapical ER, directly delivered to the contiguous cell membrane, and pass across the nonapical cell wall into the hydrocarbon-based ECM.

  13. Photosynthetic activity and protein overexpression found in Cr(III)-tolerant cells of the green algae Dictyosphaerium chlorelloides.

    PubMed

    Pereira, M; Bartolomé, C M; Sánchez-Fortún, S

    2014-08-01

    Chromium is an important constituent in effluents obtained from chromium plating industries. Due to the highly toxic nature of Cr(VI), attention has been shifted to less hazardous Cr(III) electroplating processes. This study evaluated aquatic toxicity of Cr(III)-containing laboratory samples representative of effluents from chromium electroplating industries, on the photosynthetic activity exhibited by both Cr(III)-sensitive (Dc1M(wt)) and tolerant (Dc1M(Cr(III)R30)) Dictyosphaerium chlorelloides strains. Additionally, selected de novo-determined peptide sequences, obtained from Dc1M(Cr(III)R30), have been analyzed to evidence the possible Cr(III) toxic mechanism involved in the resistance of these cells to high Cr(III) levels in aquatic environments. Dc1M(Cr(III)R30) strain exhibited a gross photosynthetic balance of about five times lower than that exhibited by Dc1M(wt) strain, demonstrating that Dc1M(Cr(III)R30) has a photosynthetic yield significantly lower than Dc1M(wt). SDS-PAGE of Dc1M(Cr(III)R30) samples showed the presence of at least two protein bands (23.05 and 153.46 KDa, respectively) absent in wild-type strain samples. Although it has achieved a low coincidence between the lower molecular weight band and a GTPase identified from genome of the green alga Chlamydomonas reinhardtii, none of de novo peptide sequences obtained showed a significant MS-BLAST score, so that further studies will be required.

  14. Colony organization in the green alga Botryococcus braunii (Race B) is specified by a complex extracellular matrix.

    PubMed

    Weiss, Taylor L; Roth, Robyn; Goodson, Carrie; Vitha, Stanislav; Black, Ian; Azadi, Parastoo; Rusch, Jannette; Holzenburg, Andreas; Devarenne, Timothy P; Goodenough, Ursula

    2012-12-01

    Botryococcus braunii is a colonial green alga whose cells associate via a complex extracellular matrix (ECM) and produce prodigious amounts of liquid hydrocarbons that can be readily converted into conventional combustion engine fuels. We used quick-freeze deep-etch electron microscopy and biochemical/histochemical analysis to elucidate many new features of B. braunii cell/colony organization and composition. Intracellular lipid bodies associate with the chloroplast and endoplasmic reticulum (ER) but show no evidence of being secreted. The ER displays striking fenestrations and forms a continuous subcortical system in direct contact with the cell membrane. The ECM has three distinct components. (i) Each cell is surrounded by a fibrous β-1, 4- and/or β-1, 3-glucan-containing cell wall. (ii) The intracolonial ECM space is filled with a cross-linked hydrocarbon network permeated with liquid hydrocarbons. (iii) Colonies are enclosed in a retaining wall festooned with a fibrillar sheath dominated by arabinose-galactose polysaccharides, which sequesters ECM liquid hydrocarbons. Each cell apex associates with the retaining wall and contributes to its synthesis. Retaining-wall domains also form "drapes" between cells, with some folding in on themselves and penetrating the hydrocarbon interior of a mother colony, partitioning it into daughter colonies. We propose that retaining-wall components are synthesized in the apical Golgi apparatus, delivered to apical ER fenestrations, and assembled on the surfaces of apical cell walls, where a proteinaceous granular layer apparently participates in fibril morphogenesis. We further propose that hydrocarbons are produced by the nonapical ER, directly delivered to the contiguous cell membrane, and pass across the nonapical cell wall into the hydrocarbon-based ECM.

  15. Colony Organization in the Green Alga Botryococcus braunii (Race B) Is Specified by a Complex Extracellular Matrix

    PubMed Central

    Weiss, Taylor L.; Roth, Robyn; Goodson, Carrie; Vitha, Stanislav; Black, Ian; Azadi, Parastoo; Rusch, Jannette; Holzenburg, Andreas

    2012-01-01

    Botryococcus braunii is a colonial green alga whose cells associate via a complex extracellular matrix (ECM) and produce prodigious amounts of liquid hydrocarbons that can be readily converted into conventional combustion engine fuels. We used quick-freeze deep-etch electron microscopy and biochemical/histochemical analysis to elucidate many new features of B. braunii cell/colony organization and composition. Intracellular lipid bodies associate with the chloroplast and endoplasmic reticulum (ER) but show no evidence of being secreted. The ER displays striking fenestrations and forms a continuous subcortical system in direct contact with the cell membrane. The ECM has three distinct components. (i) Each cell is surrounded by a fibrous β-1, 4- and/or β-1, 3-glucan-containing cell wall. (ii) The intracolonial ECM space is filled with a cross-linked hydrocarbon network permeated with liquid hydrocarbons. (iii) Colonies are enclosed in a retaining wall festooned with a fibrillar sheath dominated by arabinose-galactose polysaccharides, which sequesters ECM liquid hydrocarbons. Each cell apex associates with the retaining wall and contributes to its synthesis. Retaining-wall domains also form “drapes” between cells, with some folding in on themselves and penetrating the hydrocarbon interior of a mother colony, partitioning it into daughter colonies. We propose that retaining-wall components are synthesized in the apical Golgi apparatus, delivered to apical ER fenestrations, and assembled on the surfaces of apical cell walls, where a proteinaceous granular layer apparently participates in fibril morphogenesis. We further propose that hydrocarbons are produced by the nonapical ER, directly delivered to the contiguous cell membrane, and pass across the nonapical cell wall into the hydrocarbon-based ECM. PMID:22941913

  16. Green Algae from Coal Bed Methane Ponds as a Source of Fertilizer for Economically Important Plants of Montana

    NASA Astrophysics Data System (ADS)

    Ogunsakin, O. R.; Apple, M. E.; Zhou, X.; Peyton, B.

    2016-12-01

    The Tongue River Basin of northeastern Wyoming and southeastern Montana is the location of natural gas reserves and coal bed methane (CBM) acreage. Although the water that emanates from CBM extraction varies with site, it is generally of higher quality than the waters produced by conventional oil and gas wells, in part because it is low in volatile organic compounds. However, since CBM water contains dissolved solids, including sodium (Na), bicarbonate (HCO3) and chloride (Cl) ions, the water must be treated before it can be discharged into the river or wetlands, or used for stock ponds or irrigation. Several ponds have been constructed to serve as a holding facility for CBM water. Algae from the CBM ponds of the Tongue River Basin have the potential to be utilized as fertilizer on economically important plants of Montana. Two very important crop plants of Montana are wheat, Triticum aestivum, and potatoes, Solanum tuberosum. To explore this potential, isolates of unicellular green algae (Chlorella sp.) from the CBM ponds were cultured in aerated vessels with Bold's Basic Growth Medium and natural and/or supplemental light. Algal biomass was condensed in and collected from a valved funnel, after which cell density was determined via light microscopy and a hemacytometer. Algal/water slurries with known nutrient contents were added to seedlings of hard winter wheat, T.aestivum, grown in a greenhouse for three months before harves. When compared to wheat provided with just water, or with water and a commercially available fertilizer, the wheat fertilized with algae had a higher chlorophyll content, more tillers (side shoots), and a higher ratio of influorescences (groups of flowers) per stem. In a related experiment, Ranger Russet seed potatoes, S. tuberosum were given just water, water and Hoagland's nutrient solution, or water with algae in order to compare aboveground growth and potato production among the treatments. The results of this study suggest that

  17. Comparative Chloroplast Genome Analyses of Streptophyte Green Algae Uncover Major Structural Alterations in the Klebsormidiophyceae, Coleochaetophyceae and Zygnematophyceae.

    PubMed

    Lemieux, Claude; Otis, Christian; Turmel, Monique

    2016-01-01

    The Streptophyta comprises all land plants and six main lineages of freshwater green algae: Mesostigmatophyceae, Chlorokybophyceae, Klebsormidiophyceae, Charophyceae, Coleochaetophyceae and Zygnematophyceae. Previous comparisons of the chloroplast genome from nine streptophyte algae (including four zygnematophyceans) revealed that, although land plant chloroplast DNAs (cpDNAs) inherited most of their highly conserved structural features from green algal ancestors, considerable cpDNA changes took place during the evolution of the Zygnematophyceae, the sister group of land plants. To gain deeper insights into the evolutionary dynamics of the chloroplast genome in streptophyte algae, we sequenced the cpDNAs of nine additional taxa: two klebsormidiophyceans (Entransia fimbriata and Klebsormidium sp. SAG 51.86), one coleocheatophycean (Coleochaete scutata) and six zygnematophyceans (Cylindrocystis brebissonii, Netrium digitus, Roya obtusa, Spirogyra maxima, Cosmarium botrytis and Closterium baillyanum). Our comparative analyses of these genomes with their streptophyte algal counterparts indicate that the large inverted repeat (IR) encoding the rDNA operon experienced loss or expansion/contraction in all three sampled classes and that genes were extensively shuffled in both the Klebsormidiophyceae and Zygnematophyceae. The klebsormidiophycean genomes boast greatly expanded IRs, with the Entransia 60,590-bp IR being the largest known among green algae. The 206,025-bp Entransia cpDNA, which is one of the largest genome among streptophytes, encodes 118 standard genes, i.e., four additional genes compared to its Klebsormidium flaccidum homolog. We inferred that seven of the 21 group II introns usually found in land plants were already present in the common ancestor of the Klebsormidiophyceae and its sister lineages. At 107,236 bp and with 117 standard genes, the Coleochaete IR-less genome is both the smallest and most compact among the streptophyte algal cpDNAs analyzed thus

  18. Comparative Chloroplast Genome Analyses of Streptophyte Green Algae Uncover Major Structural Alterations in the Klebsormidiophyceae, Coleochaetophyceae and Zygnematophyceae

    PubMed Central

    Lemieux, Claude; Otis, Christian; Turmel, Monique

    2016-01-01

    The Streptophyta comprises all land plants and six main lineages of freshwater green algae: Mesostigmatophyceae, Chlorokybophyceae, Klebsormidiophyceae, Charophyceae, Coleochaetophyceae and Zygnematophyceae. Previous comparisons of the chloroplast genome from nine streptophyte algae (including four zygnematophyceans) revealed that, although land plant chloroplast DNAs (cpDNAs) inherited most of their highly conserved structural features from green algal ancestors, considerable cpDNA changes took place during the evolution of the Zygnematophyceae, the sister group of land plants. To gain deeper insights into the evolutionary dynamics of the chloroplast genome in streptophyte algae, we sequenced the cpDNAs of nine additional taxa: two klebsormidiophyceans (Entransia fimbriata and Klebsormidium sp. SAG 51.86), one coleocheatophycean (Coleochaete scutata) and six zygnematophyceans (Cylindrocystis brebissonii, Netrium digitus, Roya obtusa, Spirogyra maxima, Cosmarium botrytis and Closterium baillyanum). Our comparative analyses of these genomes with their streptophyte algal counterparts indicate that the large inverted repeat (IR) encoding the rDNA operon experienced loss or expansion/contraction in all three sampled classes and that genes were extensively shuffled in both the Klebsormidiophyceae and Zygnematophyceae. The klebsormidiophycean genomes boast greatly expanded IRs, with the Entransia 60,590-bp IR being the largest known among green algae. The 206,025-bp Entransia cpDNA, which is one of the largest genome among streptophytes, encodes 118 standard genes, i.e., four additional genes compared to its Klebsormidium flaccidum homolog. We inferred that seven of the 21 group II introns usually found in land plants were already present in the common ancestor of the Klebsormidiophyceae and its sister lineages. At 107,236 bp and with 117 standard genes, the Coleochaete IR-less genome is both the smallest and most compact among the streptophyte algal cpDNAs analyzed thus

  19. Evolutionary relatedness does not predict competition and co-occurrence in natural or experimental communities of green algae

    PubMed Central

    Alexandrou, Markos A.; Cardinale, Bradley J.; Hall, John D.; Delwiche, Charles F.; Fritschie, Keith; Narwani, Anita; Venail, Patrick A.; Bentlage, Bastian; Pankey, M. Sabrina; Oakley, Todd H.

    2015-01-01

    The competition-relatedness hypothesis (CRH) predicts that the strength of competition is the strongest among closely related species and decreases as species become less related. This hypothesis is based on the assumption that common ancestry causes close relatives to share biological traits that lead to greater ecological similarity. Although intuitively appealing, the extent to which phylogeny can predict competition and co-occurrence among species has only recently been rigorously tested, with mixed results. When studies have failed to support the CRH, critics have pointed out at least three limitations: (i) the use of data poor phylogenies that provide inaccurate estimates of species relatedness, (ii) the use of inappropriate statistical models that fail to detect relationships between relatedness and species interactions amidst nonlinearities and heteroskedastic variances, and (iii) overly simplified laboratory conditions that fail to allow eco-evolutionary relationships to emerge. Here, we address these limitations and find they do not explain why evolutionary relatedness fails to predict the strength of species interactions or probabilities of coexistence among freshwater green algae. First, we construct a new data-rich, transcriptome-based phylogeny of common freshwater green algae that are commonly cultured and used for laboratory experiments. Using this new phylogeny, we re-analyse ecological data from three previously published laboratory experiments. After accounting for the possibility of nonlinearities and heterogeneity of variances across levels of relatedness, we find no relationship between phylogenetic distance and ecological traits. In addition, we show that communities of North American green algae are randomly composed with respect to their evolutionary relationships in 99% of 1077 lakes spanning the continental United States. Together, these analyses result in one of the most comprehensive case studies of how evolutionary history influences

  20. Cancer prevention by green tea: evidence from epidemiologic studies1234

    PubMed Central

    2013-01-01

    In contrast to the consistent results of an inhibitory effect of green tea extracts and tea polyphenols on the development and growth of carcinogen-induced tumors in experimental animal models, results from human studies are mixed. Both observational and intervention studies have provided evidence in support of a protective role of green tea intake in the development of oral–digestive tract cancer or an inhibitory role of oral supplementation of green tea extract on a precancerous lesion of oral cavity. Evidence in support of green tea intake against the development of liver cancer risk is limited and inconsistent. An inverse association between green tea intake and lung cancer risk has been observed among never smokers but not among smokers. Although observational studies do not support a beneficial role of tea intake against the development of prostate cancer, several phase 2 clinical trials have shown an inhibitory effect of green tea extract against the progression of prostate premalignant lesions to malignant tumors. Prospective epidemiologic studies so far have not provided evidence for a protective effect of green tea consumption on breast cancer development. Current data neither confirm nor refute a definitive cancer-preventive role of green tea intake. Large randomized intervention trials on the efficacy of green tea polyphenols or extracts are required before a recommendation for green tea consumption for cancer prevention should be made. PMID:24172305

  1. Cancer prevention by green tea: evidence from epidemiologic studies.

    PubMed

    Yuan, Jian-Min

    2013-12-01

    In contrast to the consistent results of an inhibitory effect of green tea extracts and tea polyphenols on the development and growth of carcinogen-induced tumors in experimental animal models, results from human studies are mixed. Both observational and intervention studies have provided evidence in support of a protective role of green tea intake in the development of oral-digestive tract cancer or an inhibitory role of oral supplementation of green tea extract on a precancerous lesion of oral cavity. Evidence in support of green tea intake against the development of liver cancer risk is limited and inconsistent. An inverse association between green tea intake and lung cancer risk has been observed among never smokers but not among smokers. Although observational studies do not support a beneficial role of tea intake against the development of prostate cancer, several phase 2 clinical trials have shown an inhibitory effect of green tea extract against the progression of prostate premalignant lesions to malignant tumors. Prospective epidemiologic studies so far have not provided evidence for a protective effect of green tea consumption on breast cancer development. Current data neither confirm nor refute a definitive cancer-preventive role of green tea intake. Large randomized intervention trials on the efficacy of green tea polyphenols or extracts are required before a recommendation for green tea consumption for cancer prevention should be made.

  2. Strong interactions between stoichiometric constraints and algal defenses: evidence from population dynamics of Daphnia and algae in phosphorus-limited microcosms.

    PubMed

    DeMott, William R; Van Donk, Ellen

    2013-01-01

    The dynamic interactions among nutrients, algae and grazers were tested in a 2 × 3 factorial microcosm experiment that manipulated grazers (Daphnia present or absent) and algal composition (single species cultures and mixtures of an undefended and a digestion-resistant green alga). The experiment was run for 25 days in 10-L carboys under mesotrophic conditions that quickly led to strong phosphorus limitation of algal growth (TP is approximately equal to 0.5 μM, N:P 40:1). Four-day Daphnia juvenile growth assays tested for Daphnia P-limitation and nutrient-dependent or grazer-induced algal defenses. The maximal algal growth rate of undefended Ankistrodesmus (mean ± SE for three replicate microcosms; 0.92 ± 0.02 day(-1)) was higher than for defended Oocystis (0.62 ± 0.03 day(-1)), but by day 6, algal growth was strongly P-limited in all six treatments (molar C:P ratio >900). The P-deficient algae were poor quality resources in all three algal treatments. However, Daphnia population growth, reproduction, and survival were much lower in the digestion-resistant treatment even though growth assays provided evidence for Daphnia P-limitation in only the undefended and mixed treatments. Growth assays provided little or no support for simple threshold element ratio (TER) models that fail to consider algae defenses that result in viable gut passage. Our results show that strong P-limitation of algal growth enhances the defenses of a digestion-resistant alga, favoring high abundance of well-defended algae and energy limitation of zooplankton growth.

  3. Occurrence of metallothionein gene smtA in synechococcus Tx-20 and other blue-green algae

    SciTech Connect

    Robinson, N.J.; Gupta, A.; Huckle, J.W.; Jackson, P.; Whitton, B.A. )

    1990-06-01

    Blue-green algae are often abundant at Zn- and Cd-contaminated sites. In order to understand the mechanisms associated with Zn- and Cd-tolerance, we have isolated a metallothionein gene, designated smtA, in Synechococcus Tx-20 (- Pcc 6301 - Anacystis nidulans), a strain apparently obtained from an unpolluted site. The gene was cloned and sequenced, and its expression investigated in a range of heavy-metal-tolerant strains of the same organism obtained by stepwise adaptation. The polymerase chain reaction was used to probe for the possible presence of the homologous gene in a range of other strains (especially Synechococcus) isolated from sites without and with heavy metal contamination.

  4. A geometrical approach explains Lake Ball (Marimo) formations in the green alga, Aegagropila linnaei.

    PubMed

    Togashi, Tatsuya; Sasaki, Hironobu; Yoshimura, Jin

    2014-01-20

    An extremely rare alga, Aegagropila linnaei, is known for its beautiful spherical filamentous aggregations called Lake Ball (Marimo). It has long been a mystery in biology as to why this species forms 3D ball-like aggregations. This alga also forms two-dimensional mat-like aggregations. Here we show that forming ball-like aggregations is an adaptive strategy to increase biomass in the extremely limited environments suitable for growth of this alga. We estimate the maximum biomass attained by ball colonies and compare it to that attained by mat colonies. As a result, a ball colony can become larger in areal biomass than the mat colony. In the two large ball colonies studied so far, they actually have larger biomasses than the mat colonies. The uniqueness of Lake Balls in nature seems to be due to the rarity of such environmental conditions. This implies that the conservation of this alga is difficult, but important.

  5. Substrate specificity of the violaxanthin de-epoxidase of the primitive green alga Mantoniella squamata (Prasinophyceae).

    PubMed

    Goss, Reimund

    2003-09-01

    The substrate specificity of the enzyme violaxanthin de-epoxidase (VDE) of the primitive green alga Mantoniella squamata (Prasinophyceae) was tested in in vitro enzyme assays employing the following xanthophyll mono-epoxides: antheraxanthin (Ax), diadinoxanthin (Ddx), lutein-epoxide (LE), cryptoxanthin-epoxide (CxE), 9- cis neoxanthin (cNx), all- trans neoxanthin (Nx), and xanthophyll di-epoxides: 9- cis violaxanthin (cVx), all- trans violaxanthin (Vx), cryptoxanthin-di-epoxide (CxDE). The data presented in this study show that the VDE of M. squamata not only exhibits a low affinity for the mono-epoxide Ax, as has been reported by R. Frommolt et al. (2001, Planta 213:446-456), but has a reduced substrate affinity for the mono-epoxides Ddx, LE, CxE, and Nx as well. On the other hand, xanthophylls with a second epoxy-group (Vx, CxDE) can be de-epoxidized with a higher efficiency. Such a preference for xanthophyll di-epoxides cannot be observed for the higher-plant VDE, where, in general, no marked differences in the pigment de-epoxidation rates between xanthophyll mono- and di-epoxides are visible. Despite this substantial difference between the VDEs of M. squamata and S. oleracea there are also features common to both enzymes. Neither VDE is able to convert xanthophylls with a 9- cis configuration in the acyclic polyene chain and both rely on substrates in the all- trans configuration. Both enzymes furthermore exhibit a dependence of enzyme activity on the polarity of the substrate. Highly polar (Nx) or non-polar (CxE) xanthophylls are de-epoxidized with greatly reduced rates in comparison to substrates with an intermediate polarity (Vx, Ax, LE, Ddx). This dependence on substrate polarity becomes more obvious when the higher-plant VDE is examined, as the substrate affinity of the VDE of M. squamata is more strongly influenced by the existence or absence of a second epoxy-group. In summary, the data presented in this study underline the fact that different VDEs