an analytical study of the role of various factors causing red tide outbreaks of trichodesmium as deduced from field and laboratory observation.the marine blue green alga trichodesmium sp is found in red-tide outbreaks in sub-tropical areas in the pacific and indian oceans, the arabian seas and the equatorial currents of the gulf of mexico. giberellic acid stimulated the growth of trichodesmium cultures to a greater extent than in the diatom melosira sulcata. while increasing either the nitrate or phosphate above the normal levels in the culture medium did not greatly stimulate the growth of this organism, trichodesmium did thrive in ni ...1975812691
marine oscillatoria (trichodesmium): explanation for aerobic nitrogen fixation without heterocysts.nitrogen fixation in marine oscillatoria appears to be associated with differentiated cells located in the center of the colony. these central cells exhibit reduced pigmentation relative to peripherally located cells and do not incorporate 14co2 in photosynthesis. central cells apparently do not produce o2 which would deactivate nitrogenase. when central cells are exposed to o2 via disruption of the colonies, n2 fixation (acetylene reduction) decreases sharply even though individual trichomes re ...19761257749
ultrastructural and chemical assessment of poly-beta-hydroxybutyric acid in the marine cyanobacterium trichodesmium thiebautii.we report here on the occurrence and quantities of poly-beta-hydroxybutyric acid (phb) in natural populations of the marine cyanobacterium trichodesmium thiebautii. a diurnal variation in the shape and size of phb granules and in phb content was observed. the highest phb levels (2.3 +/- 0.8 mg g-1 dry wt) were recorded in the early morning and the values decreased thereafter with a minimum at night (1.6 +/- 0.9 mg g-1 dry wt). our data suggest that phb is a prominent cell constituent in t. thieb ...19921325936
glutamine synthetase and nitrogen cycling in colonies of the marine diazotrophic cyanobacteria trichodesmium spp.we examined freshly collected samples of the colonial planktonic cyanobacterium trichodesmium thiebautii to determine the pathways of recently fixed n within and among trichomes. high concentrations of glutamate and glutamine were found in colonies. glutamate and glutamine uptake rates and concentrations in cells were low in the early morning and increased in the late morning to reach maxima near midday; then uptake and concentration again fell to low values. this pattern followed that previousl ...19921359837
unique modification of adenine in genomic dna of the marine cyanobacterium trichodesmium sp. strain nibb 1067.the genomic dna of the marine nonheterocystous nitrogen-fixing cyanobacterium trichodesmium sp. strain nibb 1067 was found to be highly resistant to dna restriction endonucleases. the dna was digested extensively by the restriction enzyme dpni, which requires adenine methylation for activity. the dna composition, determined by high-performance liquid chromatography (hplc), was found to be 69% at. surprisingly, it was found that a modified adenine which was not methylated at the usual n6 position ...19911657876
amplification, cloning, and sequencing of a nifh segment from aquatic microorganisms and natural use of the polymerase chain reaction and degenerate oligonucleotide primers for highly conserved regions of nifh, a segment of nifh dna was amplified from several aquatic microorganisms, including an n2-fixing bacterium closely associated with the marine filamentous cyanobacterium trichodesmium sp., a heterotrophic isolate from the root/rhizome of the seagrass ruppia maritima, and the heterocystous freshwater cyanobacterium anabaena oscillarioides. nifh segments were amplified directly from d ...19911768139
a neurotoxic factor associated with the bloom-forming cyanobacterium trichodesmium. 19911904659
arrangement of nitrogenase structural genes in an aerobic filamentous nonheterocystous cyanobacterium.members of the marine filamentous, nonheterocystous cyanobacterial genus trichodesmium not only are capable of fixing nitrogen aerobically in the light but when grown under a light-dark cycle will fix nitrogen only during the light phase. in this study, we constructed a restriction map of the structural nitrogen fixation genes (nifhdk) in trichodesmium sp. strain nibb 1067. we found that the organization of the nif genes in trichodesmium sp. strain nibb 1067 is contiguous, as found in other nonh ...19911938909
use of degenerate oligonucleotides for amplification of the nifh gene from the marine cyanobacterium trichodesmium thiebautii.trichodesmium spp. are marine filamentous, nonheterocystous, nitrogen-fixing cyanobacteria which are an important component of marine ecosystems. this organism has never been maintained in axenic culture, and there has remained some doubt as to the identity of the organism responsible for nitrogen fixation in trichodesmium aggregates. by using degenerate oligonucleotide primers, it has been possible to amplify, clone, and sequence a segment of the nifh gene from a natural assemblage of trichodes ...19892513774
the ultrastructure of the marine blue green alga, trichodesmium erythraeum, with special reference to the cell wall, gas vacuoles, and cylindrical bodies. 19694986297
evolutionary affiliation of the marine nitrogen-fixing cyanobacterium trichodesmium sp. strain nibb 1067, derived by 16s ribosomal rna sequence analysis.the 16s rrna sequence of trichodesmium sp. strain nibb 1067 was determined and used for the construction of a distance tree and bootstrap analysis. the tree shows that, among the available cyanobacterial 16s rrna sequences, trichodesmium nibb 1067 has oscillatoria pcc 7515 as its closest relative, presenting 94.9% of sequence similarity with the latter strain. this is in contrast to a difference of 9 mol% g+c in mean genomic dna base composition between the two organisms. nevertheless, the genot ...19947522848
toxic effect of the bloom-forming trichodesmium sp. (cyanophyta) to the copepod acartia tonsa.the toxicity of the marine cyanobacterium trichodesmium sp. to the copepod acartia tonsa was assessed in a series of experiments during a trichodesmium bloom off the north carolina coast in late october 1992. healthy intact cells of trichodesmium sp. were not toxic to a. tonsa and were ingested by a. tonsa when no other foods were available. however, homogenized trichodesmium cells were toxic to a. tonsa, suggesting that trichodesmium sp. contains certain type(s) of intracellular biotoxins. this ...19947952947
apparent relationships between toxins elaborated by the cyanobacterium trichodesmium erythraeum and those present in the flesh of the narrow-barred spanish mackerel scomberomorus commersoni.the marine cyanobacterium trichodesmium erythraeum contains toxic water-soluble material that produces signs in mice similar to those produced by water-soluble extracts of the flesh of a specimen of pelagic fish scomberomorus commersoni from a batch that had been implicated in a poisoning resembling ciguatera. extracts of water-soluble material from both the cyanobacterium and the fish contained toxins that were chromatographically indistinguishable. a peptide and an alkaloid were detected in pa ...19938266348
isolation of nifh and part of nifd by modified capture polymerase chain reaction from a natural population of the marine cyanobacterium trichodesmium sp.a modified capture polymerase chain reaction (cpcr) technique was used to isolate the entire sequence of the nifh gene and its flanking regions from a natural population of trichodesmium sp. a set of specific cpcr primers derived from a known 72-bp dna segment of the nifh sequence permitted isolation of both the upstream and the downstream region of trichodesmium sp. nifh. the 882-bp nifh gene presented here is the first full-length gene isolated from trichodesmium sp. a sequence similar to a ni ...19968869497
glbn (cyanoglobin) is a peripheral membrane protein that is restricted to certain nostoc spp.the glbn gene of nostoc commune utex 584 is juxtaposed to nifu and nifh, and it encodes a 12-kda monomeric hemoglobin that binds oxygen with high affinity. in n. commune utex 584, maximum accumulation of glbn occurred in both the heterocysts and vegetative cells of nitrogen-fixing cultures when the rate of oxygen evolution was repressed to less than 25 micromol of o2 mg of chlorophyll a(-1) h(-1). accumulation of glbn coincided with maximum synthesis of nifh and ferredoxin nadp+ oxidoreductase ( ...19968932316
structural analysis of the trichodesmium nitrogenase iron protein: implications for aerobic nitrogen fixation activity.trichodesmium spp. are marine filamentous nitrogen-fixing cyanobacteria which play an important role in the nitrogen budget of the open ocean. trichodesmium is unique in that it is nonheterocystous and fixes nitrogen during the day, while evolving oxygen through photosynthesis, even though nitrogenase is sensitive to oxygen inactivation. the sequence of the gene encoding the fe protein component of nitrogenase from the recently cultivated isolate trichodesmium sp. ims 101 was used to construct a ...19979271856
circadian rhythm of nitrogenase gene expression in the diazotrophic filamentous nonheterocystous cyanobacterium trichodesmium sp. strain ims 101.recent studies suggested that the daily cycle of nitrogen fixation activity in the marine filamentous nonheterocystous cyanobacterium trichodesmium sp. is controlled by a circadian rhythm. in this study, we evaluated the rhythm of nitrogen fixation in trichodesmium sp. strain ims 101 by using the three criteria for an endogenous rhythm. nitrogenase transcript abundance oscillated with a period of approximately 24 h, and the cycle was maintained even under constant light conditions. the cyclic pa ...19989658003
whole-cell immunolocalization of nitrogenase in marine diazotrophic cyanobacteria, trichodesmium sppthe mechanism by which planktonic marine cyanobacteria of the genus trichodesmium fix n2 aerobically during photosynthesis without heterocysts is unknown. as an aid in understanding how these species protect nitrogenase, we have developed an immunofluorescence technique coupled to light microscopy (if-lm) with which intact cyanobacteria can be immunolabeled and the distribution patterns of nitrogenase and other proteins can be described and semiquantified. chilled ethanol was used to fix the cel ...19989687472
the presence and expression of hetr in the non-heterocystous cyanobacterium symploca pcc 8002.the filamentous cyanobacteria symploca pcc 8002 (symploca) and trichodesmium spp. fix nitrogen aerobically in the light in a light/dark cycle, without forming specialized thick-walled cells (heterocysts). even though they do not form heterocysts, we amplified and sequenced a segment of a key regulatory gene in heterocyst differentiation, the hetr gene, from symploca, trichodesmium erythraeum and leptolyngbya pcc 73110 (which fixes nitrogen anaerobically) using degenerate oligonucleotides. the tr ...19989835026
cloning and transcriptional analysis of the nifuhdk genes of trichodesmium sp. ims101 reveals stable nifd, nifdk and nifk transcripts.trichodesmium spp. are marine filamentous, non-heterocystous cyanobacteria capable of aerobic nitrogen fixation. in this study, the nitrogenase structural genes (nifhdk) and nifu gene of trichodesmium sp. ims101 were cloned and sequenced. the trichodesmium sp. ims101 nifh, nifd and nifk amino acid sequences showed only 79%, 66% and 68% identity, respectively, to those of anabaena sp. strain pcc 7120. a potential transcription start site for nifh was found 212 bases upstream of the nifh start cod ...19989884228
expression of photosynthesis genes in relation to nitrogen fixation in the diazotrophic filamentous nonheterocystous cyanobacterium trichodesmium sp. ims 101.the daily cycle of nitrogenase expression in the marine filamentous nonheterocystous cyanobacterium trichodesmium spp. is controlled by a circadian rhythm. we evaluated the rhythm of two key photosynthesis genes, psba of photosystem ii and psaa of photosystem i, in trichodesmium sp. ims 101 using the 3 criteria for an endogenous rhythm. the transcript abundance of psba and psaa transcripts oscillated with a period of ca. 24 h under a 12 h light/12 h dark regime. at 24 degrees c and 28 degrees c ...199910561071
nitrate assimilation genes of the marine diazotrophic, filamentous cyanobacterium trichodesmium sp. strain wh9601.a 4.0-kb dna fragment of trichodesmium sp. strain wh9601 contained gene sequences encoding the nitrate reduction enzymes, nira and narb. a third gene positioned between nira and narb encodes a putative membrane protein with similarity to the nitrate permeases of bacillus subtilis (nasa) and emericella nidulans (crna). the gene was shown to functionally complement a deltanasa mutant of b. subtilis and was assigned the name napa (nitrate permease). napa was involved in both nitrate and nitrite upt ...200010692386
precision of different methods used for estimating the abundance of the nitrogen-fixing marine cyanobacterium, trichodesmium ehrenberg.variances involved in estimating the abundance of the nitrogen-fixing marine cyanobacterium, trichodesmium ehrenberg, were evaluated by repeated sampling using bottle casts and plankton net tows at two stations in the southern east china sea. the variance among individual samples and the variance arising from subsampling processes were separated by the method of analysis of variance, and the coefficient of variation (c.v.) of an abundance estimate based on a single subsample was calculated. for ...200010699211
the nitrogen physiology of the marine n2-fixing cyanobacteria trichodesmium spp.trichodesmium spp. have proved to be enigmatic organisms, and their ecology and physiology are unusual among diazotrophs. recent research shows that they can simultaneously fix n2 and take up combined nitrogen. the co-occurrence of these two processes is thought to be incompatible, but they could be obligatory in trichodesmium spp. if only a small fraction of cells within a colony or along a filament are capable of n2 fixation. combined nitrogen is released from cells during periods of active gr ...200010740295
regulation of biological nitrogen fixation.biological nitrogen fixation, a process found only in some prokaryotes, is catalyzed by the nitrogenase enzyme complex. bacteria containing nitrogenase occupy an indispensable ecological niche, supplying fixed nitrogen to the global nitrogen cycle. due to this inceptive role in the nitrogen cycle, diazotrophs are present in virtually all ecosystems, with representatives in environments as varied as aerobic soils (e.g., azotobacter species), the ocean surface layer (trichodesmium) and specialized ...200010801900
phosphorus limitation of nitrogen fixation by trichodesmium in the central atlantic ocean.marine fixation of atmospheric nitrogen is believed to be an important source of biologically useful nitrogen to ocean surface waters, stimulating productivity of phytoplankton and so influencing the global carbon cycle. the majority of nitrogen fixation in tropical waters is carried out by the marine cyanobacterium trichodesmium, which supplies more than half of the new nitrogen used for primary production. although the factors controlling marine nitrogen fixation remain poorly understood, it h ...200111333977
unicellular cyanobacteria fix n2 in the subtropical north pacific ocean.fixed nitrogen (n) often limits the growth of organisms in terrestrial and aquatic biomes, and n availability has been important in controlling the co2 balance of modern and ancient oceans. the fixation of atmospheric dinitrogen gas (n2) to ammonia is catalysed by nitrogenase and provides a fixed n for n-limited environments. the filamentous cyanobacterium trichodesmium has been assumed to be the predominant oceanic n2-fixing microorganism since the discovery of n2 fixation in trichodesmium in 1 ...200111493920
segregation of nitrogen fixation and oxygenic photosynthesis in the marine cyanobacterium the modern ocean, a significant amount of nitrogen fixation is attributed to filamentous, nonheterocystous cyanobacteria of the genus trichodesmium. in these organisms, nitrogen fixation is confined to the photoperiod and occurs simultaneously with oxygenic photosynthesis. nitrogenase, the enzyme responsible for biological n2 fixation, is irreversibly inhibited by oxygen in vitro. how nitrogenase is protected from damage by photosynthetically produced o2 was once an enigma. using fast repetit ...200111711677
iron stress in open-ocean cyanobacteria (synechococcus, trichodesmium, and crocosphaera spp.): identification of the idia protein.cyanobacteria are prominent constituents of the marine biosphere that account for a significant percentage of oceanic primary productivity. in an effort to resolve how open-ocean cyanobacteria persist in regions where the fe concentration is thought to be limiting their productivity, we performed a number of fe stress experiments on axenic cultures of marine synechococcus spp., crocosphaera sp., and trichodesmium sp. through this work, we determined that all of these marine cyanobacteria mount a ...200111722891
partitioning of bacterial communities between seawater and healthy, black band diseased, and dead coral surfaces.distinct partitioning has been observed in the composition and diversity of bacterial communities inhabiting the surface and overlying seawater of three coral species infected with black band disease (bbd) on the southern caribbean island of curaçao, netherlands antilles. pcr amplification and sequencing of bacterial 16s rrna genes (rdna) with universally conserved primers have identified over 524 unique bacterial sequences affiliated with 12 bacterial divisions. the molecular sequences exhibite ...200211976091
characterization of trichodesmium spp. by genetic techniques.the genetic diversity of trichodesmium spp. from natural populations (off bermuda in the sargasso sea and off north australia in the arafura and coral seas) and of culture isolates from two regions (sargasso sea and indian ocean) was investigated. three independent techniques were used, including a dna fingerprinting method based on a highly iterated palindrome (hip1), denaturing gradient gel electrophoresis of a hetr fragment, and sequencing of the internal transcribed spacer (its) of the 16s-2 ...200211976093
iron and marine nitrogen fixation: progress and future directions.a synthesis of the current understanding of potential iron limitation of pelagic nitrogen fixation is given, considering biochemical bases of fe requirements and empirical observations of growth and fe quotas of cultures and field populations of trichodesmium. the potential for iron limitation of heterotrophic diazotrophy in the marine environment is also evaluated.200212160315
buoyancy regulation and the potential for vertical migration in the oceanic cyanobacterium trichodesmium.diel protein and carbohydrate content in trichodesmium thiebautii was measured to evaluate the relationship to buoyancy status. carbohydrate:protein ratio was the best predictor of buoyancy and fit a cosine curve with increasing values during the day and decreasing values at night in cycles that paralleled observed diel buoyancy patterns. this ratio also increased in short-term experiments as a function of light and increased in parallel with decreasing positive buoyancy. we used changes in this ...200312481233
diurnal expression of hetr and diazocyte development in the filamentous non-heterocystous cyanobacterium trichodesmium erythraeum.the marine non-heterocystous cyanobacterium trichodesmium fixes atmospheric n(2) aerobically in light. in situ immunolocalization/light microscopy of nifh revealed that lighter, non-granulated cell regions observed correspond to the nitrogenase-containing diazocyte clusters in trichodesmium ims101. the number of diazocyte clusters per trichome varied from 0 to 4 depending on trichome length. the constant percentage of diazocytes (approx. 15 %) in cultured strains and five natural populations sug ...200312724375
split dnae genes encoding multiple novel inteins in trichodesmium erythraeum.three inteins were found when analyzing a pair of split dnae genes encoding the catalytic subunit of dna polymerase iii in the oceanic n2-fixing cyanobacterium trichodesmium erythraeum. the three inteins (dnae-1, dnae-2, and dnae-3) were clustered in a 70-amino acid (aa) region of the predicted dnae protein. the dnae-1 intein is 1258 aa long and three times as large as a typical intein, due to the presence of large tandem repeats in which a 57-aa sequence is repeated 17 times. the dnae-2 intein ...200312766150
water pollution and habitat degradation in the gulf of thailand.the gulf of thailand has been a major marine resource for thai people for a long time. however, recent industrialization and community development have exerted considerable stress on the marine environments and provoked habitat degradation. the following pollution problems in the gulf have been prioritized and are discussed in details: (1) untreated municipal and industrial waste water are considered to be the most serious problems of the country due to limited waste water treatment facilities i ...200312787596
growth, n2 fixation and photosynthesis in a cyanobacterium, trichodesmium sp., under fe stress.trichodesmium sp., isolated from the great barrier reef lagoon, was cultured in artificial seawater media containing a range of fe concentration. fe additions stimulated growth, n2 fixation, cellular chlorophyll a content, light-saturated chlorophyll a-specific gross photosynthetic capacity (pmchl a) and the dark respiration rate (rdchl a). cell yields only doubled for 9 nm fe relative to zero added fe, whereas n2 fixation increased 11-fold considerably for 450 nm fe. the results suggest that n2 ...200312882160
four inteins and three group ii introns encoded in a bacterial ribonucleotide reductase gene.a bacterial ribonucleotide reductase gene was found to encode four inteins and three group ii introns in the oceanic n2-fixing cyanobacterium trichodesmium erythraeum. the 13,650-bp ribonucleotide reductase gene is divided into eight extein- or exon-coding sequences that together encode a 768-amino acid mature ribonucleotide reductase protein, with 83% of the gene sequence encoding introns and inteins. the four inteins are encoded on the second half of the gene, and each has conserved sequence m ...200312975359
temperature excludes n2-fixing heterocystous cyanobacteria in the tropical oceans.whereas the non-heterocystous cyanobacteria trichodesmium spp. are the dominant n2-fixing organisms in the tropical oceans, heterocystous species dominate n2 fixation in freshwater lakes and brackish environments such as the baltic sea. so far no satisfactory explanation for the absence of heterocystous cyanobacteria in the pelagic of the tropical oceans has been given, even though heterocysts would seem to represent an ideal strategy for protecting nitrogenase from being inactivated by o2, ther ...200314523445
characterization of phosphorus-regulated genes in trichodesmium spp. 200314583545
intein harbouring large tandem repeats in replicative dna helicase of trichodesmium erythraeum.protein splicing inteins can be small as approximately 130 aa or up to approximately 600 aa when harbouring an endonuclease domain. here we report the identification and characterization of an unusually large intein, 1650 aa long and the largest of known inteins, encoded by the replicative dna helicase gene dnab of the oceanic n2-fixing cyanobacterium trichodesmium erythraeum. this ter dnab-1 intein co-exists with a 177-aa mini-intein in the same host protein and harbours large tandem repeats in ...200414763989
n2 fixation by unicellular bacterioplankton from the atlantic and pacific oceans: phylogeny and in situ rates.n2-fixing proteobacteria (alpha and gamma) and unicellular cyanobacteria are common in both the tropical north atlantic and pacific oceans. in near-surface waters proteobacterial nifh transcripts were present during both night and day while unicellular cyanobacterial nifh transcripts were present during the nighttime only, suggesting separation of n2 fixation and photosynthesis by unicellular cyanobacteria. phylogenetic relationships among unicellular cyanobacteria from both oceans were determin ...200414766553
distribution of the cyanophyte trichodesmium (oscillatoriaceae) in the eastern caribbean sea: influence of the orinoco river.orinoco river influence in the caribbean sea, characterized by high nutrient input, causes a decrease of trichodesmium populations. the caribbean time series (cats) station, south of puerto rico (17 degrees 36'n 67 degrees 00'w), was monitored for 25 months in order to observe the trichodesmium abundance pattern and the presence of the river plume. in general, mean trichodesmium abundance was higher at the surface and decreased with depth. the mean upper water column (surface to 20 m) abundance ...200015266799
traffic lights in trichodesmium. regulation of photosynthesis for nitrogen fixation studied by chlorophyll fluorescence kinetic microscopy.we investigated interactions between photosynthesis and nitrogen fixation in the non-heterocystous marine cyanobacterium trichodesmium ims101 at the single-cell level by two-dimensional (imaging) microscopic measurements of chlorophyll fluorescence kinetics. nitrogen fixation was closely associated with the appearance of cells with high basic fluorescence yield (f(0)), termed bright cells. in cultures aerated with normal air, both nitrogen fixation and bright cells appeared in the middle of the ...200415299119
from endonucleases to transcription factors: evolution of the ap2 dna binding domain in plants.all members of the ap2/erf family of plant transcription regulators contain at least one copy of a dna binding domain called the ap2 domain. the ap2 domain has been considered plant specific. here, we show that homologs are present in the cyanobacterium trichodesmium erythraeum, the ciliate tetrahymena thermophila, and the viruses enterobacteria phage rb49 and bacteriophage felix 01. we demonstrate that the t. erythraeum ap2 domain selectively binds stretches of poly(dg)/poly(dc) showing functio ...200415319480
high rates of n2 fixation by unicellular diazotrophs in the oligotrophic pacific ocean.the availability of nitrogen is important in regulating biological productivity in marine environments. deepwater nitrate has long been considered the major source of new nitrogen supporting primary production in oligotrophic regions of the open ocean, but recent studies have showed that biological n2 fixation has a critical role in supporting oceanic new production. large colonial cyanobacteria in the genus trichodesmium and the heterocystous endosymbiont richelia have traditionally been consid ...200415329721
development of a universal microarray based on the ligation detection reaction and 16s rrna gene polymorphism to target diversity of cyanobacteria.the cyanobacteria are photosynthetic prokaryotes of significant ecological and biotechnological interest, since they strongly contribute to primary production and are a rich source of bioactive compounds. in eutrophic fresh and brackish waters, their mass occurrences (water blooms) are often toxic and constitute a high potential risk for human health. therefore, rapid and reliable identification of cyanobacterial species in complex environmental samples is important. here we describe the develop ...200415574913
the impact of surface-adsorbed phosphorus on phytoplankton redfield stoichiometry.the redfield ratio of 106 carbon:16 nitrogen:1 phosphorus in marine phytoplankton is one of the foundations of ocean biogeochemistry, with applications in algal physiology, palaeoclimatology and global climate change. however, this ratio varies substantially in response to changes in algal nutrient status and taxonomic affiliation. here we report that redfield ratios are also strongly affected by partitioning into surface-adsorbed and intracellular phosphorus pools. the c:n:surface-adsorbed p (8 ...200415602560
unveiling of novel radiations within trichodesmium cluster by hetr gene sequence analysis.the filamentous nonheterocystous cyanobacterial genus katagnymene is a common diazotrophic component of tropical and subtropical oceans. to assess the phylogenetic affiliation of this taxon, two partial 16s rrna gene sequences and 25 partial hetr gene sequences originating from the genera katagnymene and trichodesmium collected from open, surface waters of the atlantic, indian, and pacific oceans were compared. single trichomes or colonies were identified morphologically by using light microscop ...200515640187
variable selection pressures across lineages in trichodesmium and related cyanobacteria based on the heterocyst differentiation protein gene hetr.due to the irreversible inhibition of nitrogenase by o2, n2 fixation is incompatible with the oxygenic photosynthesis of cyanobacteria. these organisms have therefore evolved various strategies for growing diazotrophically. one group of n2-fixing cyanobacteria has specialized cells, heterocysts, which contain the nitrogenase, lack the oxygenic photosystem ii, and are virtually anoxic inside as the result of respiratory activity and a thick glycolipid cell wall. the hetr gene encodes a serine pro ...200515716028
a retinoic acid binding cytochrome p450: cyp120a1 from synechocystis sp. pcc least 35 cytochrome p450 (p450, cyp) or cytochrome p450-like genes have been identified in 10 cyanobacterial genomes yet none have been functionally characterized. cyp110 and cyp120 represent the two largest cyanobacterial p450 families with 16 and four members, respectively, identified to date. the synechocystis sp. pcc 6803 cyp120a1 protein sequence shares high degrees of conservation with cyp120a2 from trichodesmium erythraeum ims101 and cyp120b1 and cyp120c1 from nostoc punctiforme pcc 73 ...200515752715
dynamics of the 'echo' effect in a phytoplankton system with nitrogen fixation.consideration of nitrogen fixation adds a positive nonlinear feedback to plankton ecosystem models. we investigate the consequences of this feedback for secondary phytoplankton blooms and the response of phytoplankton dynamics to physical forcing. the dynamics of phytoplankton, trichodesmium (the nitrogen fixer), and nutrients is modeled with a system of three differential equations. the model includes two types of nonlinear interactions: the competition of phytoplankton and trichodesmium for li ...200515820739
patellamide a and c biosynthesis by a microcin-like pathway in prochloron didemni, the cyanobacterial symbiont of lissoclinum patella.prochloron spp. are obligate cyanobacterial symbionts of many didemnid family ascidians. it has been proposed that the cyclic peptides of the patellamide class found in didemnid extracts are synthesized by prochloron spp., but studies in which host and symbiont cells are separated and chemically analyzed to identify the biosynthetic source have yielded inconclusive results. as part of the prochloron didemni sequencing project, we identified patellamide biosynthetic genes and confirmed their func ...200515883371
an intron-encoded protein assists rna splicing of multiple similar introns of different bacterial genes.four group ii introns were found in an unusually intron-rich dnan gene (encoding the beta subunit of dna polymerase iii) of the cyanobacterium trichodesmium erythraeum, and they have strong similarities to two introns of the rir gene (encoding ribonucleotide reductase) of the same organism. of these six introns, only the rir-3 intron encodes a maturase protein and showed efficient rna splicing when expressed in escherichia coli cells. the other five introns do not encode a maturase protein and d ...200516150738
temporal patterns of nitrogenase gene (nifh) expression in the oligotrophic north pacific ocean.dinitrogen (n(2))-fixing microorganisms (diazotrophs) play important roles in ocean biogeochemistry and plankton productivity. in this study, we examined the presence and expression of specific planktonic nitrogenase genes (nifh) in the upper ocean (0 to 175 m) at station aloha in the oligotrophic north pacific ocean. clone libraries constructed from reverse-transcribed pcr-amplified mrna revealed six unique phylotypes. five of the nifh phylotypes grouped with sequences from unicellular and fila ...200516151126
localized tetrazolium reduction in relation to n(2) fixation, co(2) fixation, and h(2) uptake in aquatic filamentous cyanobacteria.the aquatic filamentous cyanobacteria anabaena oscillarioides and trichodesmium sp. reveal specific cellular regions of tetrazolium salt reduction. the effects of localized reduction of five tetrazolium salts on n(2) fixation (acetylene reduction), co(2) fixation, and h(2) utilization were examined. during short-term (within 30 min) exposures in a. oscillarioides, salt reduction in heterocysts occurred simultaneously with inhibition of acetylene reduction. conversely, when salts failed to either ...198216345923
immunochemical localization of nitrogenase in marine trichodesmium aggregates: relationship to n(2) fixation potential.colonial aggregation among nonheterocystous filaments of the planktonic marine cyanobacterium trichodesmium is known to enhance n(2) fixation, mediated by the o(2)-sensitive enzyme complex nitrogenase. expression of nitrogenase appears linked to the formation of o(2)-depleted microzones within aggregated bacterium-associated colonies. while this implies a mechanism by which nonheterocystous n(2) fixation can take place in an oxygenated water column, both the location and regulation of the n(2)-f ...198916348057
antiserum to nitrogenase generated from an amplified dna fragment from natural populations of trichodesmium spp.a fragment of the nifh gene was amplified from natural populations of trichodesmium spp. and cloned into a maltose-binding protein (mbp) expression vector. the peptide product of the amplified 359-bp fragment of nifh was cleaved from the fusion protein, purified, and used to generate a specific antibody to the fe protein of nitrogenase. the antiserum recognized the mbp-nitrogenase fusion protein and the cleaved nif peptide product but not mbp. the antibody cross-reacted with nitrogenase from nat ...199016348356
basis for diel variation in nitrogenase activity in the marine planktonic cyanobacterium trichodesmium thiebautii.natural populations of the nonheterocystous marine cyanobacterium trichodesmium thiebautii exhibit a diel periodicity in nitrogenase activity (na). na "turns on" near dawn and "turns off" near dusk, independent of photic conditions. chloramphenicol (cap) and ammonium prevented turn on of na in t. thiebautii when added to samples collected before dawn but were progressively less effective in inhibiting na in samples collected later in the morning. in samples collected after turn on, activities de ...199016348357
modification of the fe protein of nitrogenase in natural populations of trichodesmium thiebautii.the fe protein of nitrogenase in the marine nonheterocystous cyanobacterium trichodesmium thiebautii is interconverted between two forms, which is reminiscent of the adp-ribosylation described in the purple bacterium rhodospirillum rubrum. in natural populations of t. thiebautii during the day, when nitrogenase activity (na) is present and while photosynthetic rates are high, a low-molecular-mass form of the fe protein is present. in the late afternoon, the low-molecular-mass form is partially c ...199316348883
growth, nitrogen fixation, and spectral attenuation in cultivated trichodesmium species.physiological studies of trichodesmium species have been hindered by difficulties in maintaining actively growing, nitrogen-fixing cultures. previous cultivation successes have not been widely duplicated. we present here a simple modified seawater medium and handling techniques which have been used to maintain actively growing trichodesmium thiebautii in laboratory culture for over 1 year. the cultured population, isolated from coastal atlantic waters, has a growth rate of 0.23 division day and ...199316348931
cytochrome oxidase: subcellular distribution and relationship to nitrogenase expression in the nonheterocystous marine cyanobacterium trichodesmium thiebautii.immunochemical labeling was used to study the subcellular distribution of cytochrome oxidase, a respiratory protein, in trichodesmium thiebautii. the protein was found associated with both cytoplasmic and thylakoid membranes. about a sixfold variation in the protein content (gold particle count) was found among trichodesmium cells within a single colony. double labeling was performed with cytochrome oxidase and nitrogenase antisera. regression analysis of gold particle counts per unit of cell ar ...199316349062
iron-stimulated n(2) fixation and growth in natural and cultured populations of the planktonic marine cyanobacteria trichodesmium light of recent proposals that iron (fe) availability may play an important role in controlling oceanic primary production and nutrient flux, its regulatory impact on n(2) fixation and production dynamics was investigated in the widespread and biogeochemically important diazotrophic, planktonic cyanobacteria trichodesmium spp. fe additions, as fecl(3) and edta-chelated fecl(3), enhanced n(2) fixation (nitrogenase activity), photosynthesis (co(2) fixation), and growth (chlorophyll a production ...199416349210
amino acid cycling in colonies of the planktonic marine cyanobacterium trichodesmium thiebautii.we examined diel trends in internal pools and net efflux of free amino acids in colonies of the nonheterocystous, diazotrophic cyanobacterium trichodesmium thiebautii, freshly collected from waters of the caribbean and the bahamas. the kinetics of glutamate uptake by whole colonies were also examined. while intracolonial pools of most free amino acids were relatively constant through the day, pools of glutamate and glutamine varied over the diel cycle, with maxima during the early afternoon. thi ...199416349431
release of dissolved organic nitrogen by marine diazotrophic cyanobacteria, trichodesmium spp.trichodesmium sp. is a filamentous, colonial cyanobacterium which contributes substantially to the input of nitrogen in tropical and subtropical oceanic waters through nitrogen fixation (n(2) fixation). we applied a n tracer technique to assess the rate of release of dissolved organic nitrogen (don) from this cyanobacterium and compared those rates with rates of n(2) fixation determined for the same assemblages at the same times of day. rates of release of don showed considerable variation withi ...199416349432
phosphonate utilization by the globally important marine diazotroph trichodesmium.the factors that control the growth and nitrogen fixation rates of marine diazotrophs such as trichodesmium have been intensively studied because of the role that these processes have in the global cycling of carbon and nitrogen, and in the sequestration of carbon to the deep sea. because the phosphate concentrations of many ocean gyres are low, the bioavailability of the larger, chemically heterogeneous pool of dissolved organic phosphorus could markedly influence trichodesmium physiology. here ...200616397497
phosphorus scavenging in the unicellular marine diazotroph crocosphaera watsonii.through the fixation of atmospheric nitrogen and photosynthesis, marine diazotrophs play a critical role in the global cycling of nitrogen and carbon. crocosphaera watsonii is a recently described unicellular diazotroph that may significantly contribute to marine nitrogen fixation in tropical environments. one of the many factors that can constrain the growth and nitrogen fixation rates of marine diazotrophs is phosphorus bioavailability. using genomic and physiological approaches, we examined p ...200616461699
temporal variability in nitrogenase gene expression in natural populations of the marine cyanobacterium trichodesmium thiebautii.we report a distinct diel periodicity in the abundance of nifh (dinitrogenase reductase) mrna in natural populations of the nonheterocystous marine cyanobacterium trichodesmium thiebautii. our observations show that in addition to translational and posttranslational controls, trichodesmium nitrogenase expression is also regulated at the transcriptional and/or posttranscriptional level.199616535258
overexpression and characterization of an iron storage and dna-binding dps protein from trichodesmium erythraeum.although the role of iron in marine productivity has received a great deal of attention, no iron storage protein has been isolated from a marine microorganism previously. we describe an fe-binding protein belonging to the dps family (dna binding protein from starved cells) in the n(2)-fixing marine cyanobacterium trichodesmium erythraeum. a dps gene encoding a protein with significant levels of identity to members of the dps family was identified in the genome of t. erythraeum. this gene codes f ...200616597998
modeling the dynamic regulation of nitrogen fixation in the cyanobacterium trichodesmium sp.a physiological, unbalanced model is presented that explicitly describes growth of the marine cyanobacterium trichodesmium sp. at the expense of n(2) (diazotrophy). the model involves the dynamics of intracellular reserves of carbon and nitrogen and allows the uncoupling of the metabolism of these elements. the results show the transient dynamics of n(2) fixation when combined nitrogen (no(3)(-), nh(4)(+)) is available and the increased rate of n(2) fixation when combined nitrogen is insufficien ...200616672460
structure of trichamide, a cyclic peptide from the bloom-forming cyanobacterium trichodesmium erythraeum, predicted from the genome sequence.a gene cluster for the biosynthesis of a new small cyclic peptide, dubbed trichamide, was discovered in the genome of the global, bloom-forming marine cyanobacterium trichodesmium erythraeum ism101 because of striking similarities to the previously characterized patellamide biosynthesis cluster. the tri cluster consists of a precursor peptide gene containing the amino acid sequence for mature trichamide, a putative heterocyclization gene, an oxidase, two proteases, and hypothetical genes. based ...200616751554
transatlantic abundance of the n2-fixing colonial cyanobacterium trichodesmium.colonial diazotrophic cyanobacteria of the genus trichodesmium are thought to play a significant role in the input of new nitrogen to upper layers of the tropical and subtropical oceanic ecosystems that cover nearly half of earth's surface. here we describe results of a transatlantic survey in which a noninvasive underwater digital microscope (the video plankton recorder), was towed across the north atlantic at 6 meters per second while undulating between the surface and 130 meters. colony abund ...200616763148
common evolutionary origin of planktonic and benthic nitrogen-fixing oscillatoriacean cyanobacteria from tropical oceans.the filamentous cyanobacteria belonging to the genus hydrocoleum (blennothrix) are among the most common mat-forming cyanobacteria in tropical oceans. we present here the evidence that these benthic cyanobacteria are morphologically and phylogenetically very close to the planktonic species of trichodesmium. genetic relationship was established independently with regard to sequences of the 16s rrna gene, nifh gene, and phycocyanin and phycoerythrin intergenic spacers. the species of both genera f ...200616842341
selection on protein-coding genes of natural cyanobacterial populations.we examined the distribution of synonymous and non-synonymous changes in 12 protein-coding genes of natural populations of cyanobacteria to infer changes in gene functionality. by comparing mutation distributions within and across species using the mcdonald-kreitman test, we found data sets to contain evidence for purifying selection (hetr of trichodesmium, nifh of cylindrospermopsis raceborskii and rpoc1 of anabaena lemmermannii) and positive selection (kaic of microcoleus chthonoplastes and rb ...200616913914
on the role of oxygen for nitrogen fixation in the marine cyanobacterium trichodesmium sp.the marine, non-heterocystous, filamentous cyanobacterium trichodesmium shows a distinct diurnal pattern of nitrogenase activity. in an attempt to reveal the factors that control this pattern, a series of measurements were carried out using online acetylene reduction assay. light response curves of nitrogenase were recorded applying various concentrations of oxygen. the effect of oxygen depended on the irradiance applied. above a photon irradiance of 16 mumol m(-2) s(-1) nitrogenase activity was ...200717298372
coupling between autocatalytic cell death and transparent exopolymeric particle production in the marine cyanobacterium trichodesmium.extracellular polysaccharide aggregates, operationally defined as transparent exopolymeric particles (tep), are recognized as an important conduit for carbon recycling and export in aquatic systems. yet, the factors controlling the build-up of the tep pool are not well characterized. here we show that increased tep production by trichodesmium, an oceanic bloom-forming nitrogen-fixing (diazotrophic) cyanobacterium, is coupled with autocatalytic programmed cell death (pcd) process. we demonstrate ...200717504479
nitrogen fixation in the marine environment.cyanobacteria of the genus oscillatoria (trichodesmium) account for annual inputs of nitrogen to the world's oceans of about 4.8 x 10(12) grams while benthic environments contribute 15 x 10(12) grams. the sum of these inputs is one-fifth of current estimates of nitrogen fixation in terrestrial environments and one-half of the present rate of industrial synthesis of ammonia. when the total of all nitrogen inputs to the sea is compared with estimated losses through denitrification, the marine nitr ...198217740970
major role of the cyanobacterium trichodesmium in nutrient cycling in the north atlantic ocean.the diazotrophic cyanobacterium trichodesmium is a large (about 0.5 by 3 millimeters) phytoplankter that is common in tropical open-ocean waters. measurements of abundance, plus a review of earlier observations, indicate that it, rather than the picophytoplankton, is the most important primary producer (about 165 milligrams of carbon per square meter per day) in the tropical north atlantic ocean. furthermore, nitrogen fixation by trichodesmium introduces the largest fraction of new nitrogen to t ...199117773605
direct measurement of o2-depleted microzones in marine oscillatoria: relation to n2 fixation.among the nitrogen (n(2))-fixing cyanobacteria, the filamentous, nonheterocystous marine oscillatoria spp. (trichodesmium) appears enigmatic; it exhibits n(2) fixation in the presence of oxygenic photosynthesis without structural protection of the n(2-)fixing apparatus (nitrogenase) from potential inhibition by molecular oxygen (o(2)). characteristically, n(2) fixation is largely confined to aggregates (bundles) of filaments. previous work has suggested that spatial partitioning of photosynthesi ...198817792609
comparison of the kinetics of iron release from a marine (trichodesmium erythraeum) dps protein and mammalian ferritin in the presence and absence of ligands.the ferritin superfamily of iron storage proteins includes ferritin proper and dps (dna binding protein from starved cells) along with bacterioferritin. we examined the release of fe from the dps of trichodesmium erythraeum (dps(tery)) and compared it to the release of fe from horse spleen ferritin (hosf) under various conditions. both desferrioxamine b (dfb), a fe(iii) chelator, and ascorbic acid were able to mobilize fe from dps(tery) at rates comparable to those observed for hosf. the initial ...200717804072
fast, sensitive, and inexpensive alternative to analytical pigment hplc: quantification of chlorophylls and carotenoids in crude extracts by fitting with gauss peak spectra.quantification of pigments in complex mixtures is an important task in the physiology of photosynthetic organisms, because pigment composition differs depending on the species, tissue, and physiological state. currently available methods, however, are either limited to very few pigments (classical uv/vis spectroscopic methods), or they are time-consuming, labor intensive, or costly (e.g., hplc). here we describe a uv/vis spectrophotometric method that is capable of a rapid (approximately 1 min/s ...200717854156
effects of iron limitation on the expression of metabolic genes in the marine cyanobacterium trichodesmium erythraeum ims101.iron deficiency in axenic cultures of trichodesmium erythraeum ims101 led to significant declines in both nitrogen fixation rates and photochemical energy conversion efficiency, accompanied by downregulation of genes encoding the major iron-binding proteins, including psba and psbe of photosystem ii, psaa and psac of photosystem i, petb and petc of the cytochrome b(6)f complex, and nifh. however, the iron-starved cultures remained viable and expression of the metalloprotein genes was partially o ...200717991025
diazotrophic bacterioplankton in a coral reef lagoon: phylogeny, diel nitrogenase expression and response to phosphate enrichment.we investigated diazotrophic bacterioplankton assemblage composition in the heron reef lagoon (great barrier reef, australia) using culture-independent techniques targeting the nifh fragment of the nitrogenase gene. seawater was collected at 3 h intervals over a period of 72 h (i.e. over diel as well as tidal cycles). an incubation experiment was also conducted to assess the impact of phosphate (po(4)3*) availability on nifh expression patterns. dna-based nifh libraries contained primarily seque ...200718043616
modeled contributions of three types of diazotrophs to nitrogen fixation at station aloha.a diagnostic model based on biomass and growth was used to assess the relative contributions of filamentous nonheterocystous trichodesmium and unicellular cyanobacteria, termed groups a and b, to nitrogen fixation at the north pacific station aloha over a 2-year period. average (and 95% confidence interval, ci) annual rates of modeled monthly values for trichodesmium, group b and group a were 92 (52), 14 (4) and 12 (8) mmol n per m(2) per year, respectively. the fractional contribution to modele ...200718043668
on microalgal settlements and the sluggish development of marine biofouling in port blair waters, andamans.settlement of microalgae was investigated on perspex, aluminium and zinc coupons immersed in port blair bay waters for over 3 months. commencement of fouling was exceptionally slow, and few microalgae were found until 14 days. settlement occurred thereafter, and 47 microalgal species contributed to the fouling. the dominant forms belonged to the genera navicula and nitzschia, whereas coscinodiscus eccentricus, gyrosigma balticum and trichodesmium erythraeum also accounted for high proportions of ...200818097790
abundances and distributions of the dominant nifh phylotypes in the northern atlantic ocean.understanding the factors that influence the distribution and abundance of marine diazotrophs is important in order to assess their role in the oceanic nitrogen cycle. environmental dna samples from four cruises to the north atlantic ocean, covering a sampling area of 0 degrees n to 42 degrees n and 67 degrees w to 13 degrees w, were analyzed for the presence and amount of seven nifh phylotypes using real-time quantitative pcr and taqman probes. the cyanobacterial phylotypes dominated in abundan ...200818245263
nitrogen fixation in an anticyclonic eddy in the oligotrophic north pacific ocean.mesoscale physical processes (for example eddies, frontal meanders and planetary waves) can play important roles in controlling ocean biogeochemistry. we examined spatial variations in upper ocean (0-100 m) nutrient inventories, n(2) fixing microorganism diversity and abundance, and rates of n(2) fixation in an anticyclonic eddy near station aloha (22 degrees 45' n, 158 degrees 00' w) in the north pacific subtropical gyre (npsg). in july 2005, satellite-based sea surface altimetry and ocean colo ...200818309359
iron limitation in the marine cyanobacterium trichodesmium reveals new insights into regulation of photosynthesis and nitrogen fixation.* as iron (fe) deficiency is a main limiting factor of ocean productivity, its effects were investigated on interactions between photosynthesis and nitrogen fixation in the marine nonheterocystous diazotrophic cyanobacterium trichodesmium ims101. * biophysical methods such as fluorescence kinetic microscopy, fast repetition rate (frr) fluorimetry, and in vivo and in vitro spectroscopy of pigment composition were used, and nitrogenase activity and the abundance of key proteins were measured. * fe ...200818513224
collagen's triglycine repeat number and phylogeny suggest an interdomain transfer event from a devonian or silurian organism into trichodesmium erythraeum.two competing effects at two vastly different scales may explain collagen's current translation length. the necessity to have long molecules for maintaining mechanical integrity at the organism and supraorganism scales may be limited by the need to have small molecules capable of robust self-assembly at the nanoscale. the triglycine repeat regions of all 556 currently cataloged organisms with collagen-like genes were ranked by length. this revealed a sharp boundary in the gxy transcript number a ...200818521530
diversity and abundance of diazotrophic microorganisms in the south china sea during intermonsoon.the spatial heterogeneity of diversity and abundance of diazotrophs were investigated off the vietnamese coast in the south china sea (scs). the study area extended from the mekong river plume to the shelf region and beyond to stations extending to 1700 m depth. the scs diazotroph community, based on nifh gene diversity, had components closely related to sequences from open ocean, estuarine, saltmarsh and microbial mat communities. rarefaction analysis suggested that by using a 97% similarity op ...200818528417
viridamides a and b, lipodepsipeptides with antiprotozoal activity from the marine cyanobacterium oscillatoria nigro-viridis.parallel chemical and phylogenetic investigation of a marine cyanobacterium from panama led to the isolation of two new pks-nrps-derived compounds, viridamides a and b. their structures were determined by nmr and mass spectroscopic methods, and the absolute configurations assigned by marfey's method and chiral hplc analysis. in addition to six standard, n-methylated amino and hydroxy acids, these metabolites contained the structurally novel 5-methoxydec-9-ynoic acid moiety and an unusual proline ...200818715036
diversity and expression of nitrogen fixation genes in bacterial symbionts of marine sponges.marine sponges contain complex assemblages of bacterial symbionts, the roles of which remain largely unknown. we identified diverse bacterial nifh genes within sponges and found that nifh genes are expressed in sponges. this is the first demonstration of the expression of any protein-coding bacterial gene within a sponge. two sponges ircinia strobilina and mycale laxissima were collected from key largo, florida and had delta(15)n values of c. 0-1 per thousand and 3-4 per thousand respectively. t ...200818761667
the genome of cyanothece 51142, a unicellular diazotrophic cyanobacterium important in the marine nitrogen cycle.unicellular cyanobacteria have recently been recognized for their contributions to nitrogen fixation in marine environments, a function previously thought to be filled mainly by filamentous cyanobacteria such as trichodesmium. to begin a systems level analysis of the physiology of the unicellular n(2)-fixing microbes, we have sequenced to completion the genome of cyanothece sp. atcc 51142, the first such organism. cyanothece 51142 performs oxygenic photosynthesis and nitrogen fixation, separatin ...200818812508
distribution and activity of diazotrophs in the eastern equatorial atlantic.the gene abundance and gene expression of six diazotroph populations from the eastern equatorial atlantic in june 2007 were examined using nifh gene quantitative polymerase chain reaction (q pcr) methods. of all the diazotrophs, trichodesmium spp. was the most abundant with the highest number of gene copies in the gulf of guinea. trichodesmium also had the highest nitrogenase gene transcript abundance overall with the maximum in samples collected at the equator and in waters influenced by the co ...200919175790
reversible coupling of individual phycobiliprotein isoforms during state transitions in the cyanobacterium trichodesmium analysed by single-cell fluorescence kinetic the non-heterocyst, marine cyanobacterium trichodesmium nitrogen fixation is confined to the photoperiod and occurs coevally with oxygenic photosynthesis although nitrogenase is irreversibly inactivated by oxygen. in previous studies it was found that regulation of photosynthesis for nitrogen fixation involves mehler reaction and various activity states with reversible coupling of photosynthetic components. we now investigated these activity states in more detail. spectrally resolved fluoresc ...200919186173
phenotypic and genotypic characterization of multiple strains of the diazotrophic cyanobacterium, crocosphaera watsonii, isolated from the open ocean.diazotrophic cyanobacteria have long been recognized as important sources of reduced nitrogen (n) and therefore are important ecosystem components. until recently, species of the filamentous cyanobacterium trichodesmium were thought to be the primary sources of fixed n to the open ocean euphotic zone. it is now recognized that unicellular cyanobacteria are also important contributors, with members of the oligotrophic genus crocosphaera being the only cultured examples. herein we genetically and ...200919196268
the alkaline phosphatase phox is more widely distributed in marine bacteria than the classical phoa.phosphorus (p) is a vital nutrient for all living organisms and may control the growth of bacteria in the ocean. bacteria induce alkaline phosphatases when inorganic phosphate (p(i)) is insufficient to meet their p-requirements, and therefore bulk alkaline phosphatase activity measurements have been used to assess the p-status of microbial assemblages. in this study, the molecular basis of marine bacterial phosphatases and their potential role in the environment were investigated. we found that ...200919212430
[phytoplankton assemblages on the continental shelf of east china sea in autumn 2006].based on the survey from november 19 to december 24, 2006, the species composition, assemblage structure, and cell abundance of phytoplankton on the continental shelf of east china sea (24.0 degrees n- 32.0 degrees n, 120.0 degrees - 128.0 degrees e) were studied. the phytoplankton flora in the survey area included 145 taxa, belonging to 64 genera of 4 classes (including uncertain species). bacillariophyta was the dominant functional group, followed by pyrrophyta. the dominant species in turn we ...200819238843
fixation and fate of c and n in the cyanobacterium trichodesmium using nanometer-scale secondary ion mass spectrometry.the marine cyanobacterium trichodesmium is ubiquitous in tropical and subtropical seas and is an important contributor to global n and c cycling. we sought to characterize metabolic uptake patterns in individual trichodesmium ims-101 cells by quantitatively imaging (13)c and (15)n uptake with high-resolution secondary ion mass spectrometry (nanosims). trichodesmium fix both co(2) and n(2) concurrently during the day and are, thus, faced with a balancing act: the o(2) evolved during photosynthesi ...200919332780
carotenoids provide the major antioxidant defence in the globally significant n2-fixing marine cyanobacterium trichodesmium.photosynthetic oxygen-evolving microorganisms contend with continuous self-production of molecular oxygen and reactive oxygen species. the deleterious effects of reactive oxygen species are exacerbated for cyanobacterial nitrogen-fixers (diazotrophs) due to the innate sensitivity of nitrogenase to oxygen. this renders incompatible the processes of oxygen-evolving photosynthesis and n-fixation. we examined total antioxidative potential of various diazotrophic and non-diazotrophic cyanobacteria. w ...200919397682
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