| 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 ... | 2008 | 18513224 |
| 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 ... | 2008 | 18528417 |
| 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 ... | 2008 | 18715036 |
| 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 ... | 2008 | 18761667 |
| 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 ... | 2008 | 18812508 |
| 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 ... | 2009 | 19175790 |
| decoupling of ammonium regulation and ntca transcription in the diazotrophic marine cyanobacterium trichodesmium sp. ims101. | nitrogen (n) physiology in the marine cyanobacterium trichodesmium ims101 was studied along with transcript accumulation of the n-regulatory gene ntca and of two of its target genes: napa (nitrate assimilation) and nifh (n(2) fixation). n(2) fixation was impaired in the presence of nitrite, nitrate and urea. strain ims101 was capable of growth on these combined n sources at <2 μm but growth rates declined at elevated concentrations. assimilation of nitrate and urea was impaired in the presence o ... | 2011 | 21938021 |
| diazocyte development in the marine diazotrophic cyanobacterium trichodesmium. | the establishment of non-diazotrophic cultures of the filamentous marine cyanobacterium trichodesmium erythraeum ims101 enabled the first detailed investigation of the process leading to the development of its unique nitrogen-fixing cell type, the diazocyte. trichome heterogeneity was apparent already within 3-8h, while the differentiation of mature diazocytes, containing the nitrogenase enzyme, required 27 h after the removal of combined nitrogen. the distribution of "pro-diazocytes" within the ... | 2011 | 22053003 |
| credneramides a and b: neuromodulatory phenethylamine and isopentylamine derivatives of a vinyl chloride-containing fatty acid from cf. trichodesmium sp. nov. | credneramides a (1) and b (2), two vinyl chloride-containing metabolites, were isolated from a papua new guinea collection of cf. trichodesmium sp. nov. and expand a recently described class of vinyl chloride-containing natural products. the precursor fatty acid, credneric acid (3), was isolated from both the aqueous and organic fractions of the parent fraction as well as from another geographically and phylogenetically distinct cyanobacterial collection (panama). credneramides a and b inhibited ... | 2011 | 22148360 |
| reversible coupling of individual phycobiliprotein isoforms during state transitions in the cyanobacterium trichodesmium analysed by single-cell fluorescence kinetic measurements. | in 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 ... | 2009 | 19186173 |
| Environmental forcing of nitrogen fixation in the eastern tropical and sub-tropical north atlantic ocean. | During the winter of 2006 we measured nifH gene abundances, dinitrogen (N(2)) fixation rates and carbon fixation rates in the eastern tropical and sub-tropical North Atlantic Ocean. The dominant diazotrophic phylotypes were filamentous cyanobacteria, which may include Trichodesmium and Katagnymene, with up to 10(6) L(-1)nifH gene copies, unicellular group A cyanobacteria with up to 10(5) L(-1)nifH gene copies and gamma A proteobacteria with up to 10(4) L(-1)nifH gene copies. N(2) fixation rates ... | 2011 | 22174940 |
| 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 ... | 2009 | 19196268 |
| 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 ... | 2009 | 19212430 |
| 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 ... | 2009 | 19332780 |
| microbial community gene expression within colonies of the diazotroph, trichodesmium, from the southwest pacific ocean. | trichodesmium are responsible for a large fraction of open ocean nitrogen fixation, and are often found in complex consortia of other microorganisms, including viruses, prokaryotes, microbial eukaryotes and metazoa. we applied a community gene expression (metatranscriptomic) approach to study the patterns of microbial gene utilization within colonies of trichodesmium collected during a bloom in the southwest pacific ocean in april 2007. the survey generated 5711-day and 5385-night putative mrna ... | 2009 | 19571897 |
| a molecular assessment of the iron stress response in the two phylogenetic clades of trichodesmium. | trichodesmium spp. play key roles in global carbon and nitrogen budgets and thus defining what controls their productivity is important for understanding climate change. while iron availability has been shown to be an important chemical factor for controlling both growth and nitrogen fixation rates in trichodesmium, all culture experiments to date have focused solely on representatives from one clade of trichodesmium. genomic sequence analysis determined that the trichodesmium erythraeum (ims101 ... | 2010 | 19708870 |
| acclimation of trichodesmium erythraeum ism101 to high and low irradiance analysed on the physiological, biophysical and biochemical level. | as the nonheterocystous diazotrophic cyanobacterium trichodesmium lives both at the ocean surface and deep in the water column, it has to acclimate to vastly different irradiances. here, we investigate its strategy of light acclimation in several ways. in this study, we used spectrally resolved fluorescence kinetic microscopy to investigate the biophysics of photosynthesis in individual cells, analysed cell extracts for pigment and phycobiliprotein composition, measured nitrogenase activity and ... | 2010 | 19863729 |
| unicellular cyanobacterial distributions broaden the oceanic n2 fixation domain. | nitrogen (n2)-fixing microorganisms (diazotrophs) are an important source of biologically available fixed n in terrestrial and aquatic ecosystems and control the productivity of oligotrophic ocean ecosystems. we found that two major groups of unicellular n2-fixing cyanobacteria (ucyn) have distinct spatial distributions that differ from those of trichodesmium, the n2-fixing cyanobacterium previously considered to be the most important contributor to open-ocean n2 fixation. the distributions and ... | 2010 | 20185682 |
| regulation of nitrogen metabolism in the marine diazotroph trichodesmium ims101 under varying temperatures and atmospheric co2 concentrations. | we examined the influence of forecasted changes in global temperatures and pco(2) on n(2) fixation and assimilation in the ecologically important cyanobacterium trichodesmium spp. changes of mrna transcripts (nifh, glna, hetr, psba, psab), protein (nitrogenase, glutamine synthetase) pools and enzymatic activity (nitrogenase) were measured under varying pco(2) and temperatures. high pco(2) shifted transcript patterns of all genes, resulting in a more synchronized diel expression. under the same c ... | 2010 | 20345946 |
| red tides in the gulf of mexico: where, when, and why? | [1] independent data from the gulf of mexico are used to develop and test the hypothesis that the same sequence of physical and ecological events each year allows the toxic dinoflagellate karenia brevis to become dominant. a phosphorus-rich nutrient supply initiates phytoplankton succession, once deposition events of saharan iron-rich dust allow trichodesmium blooms to utilize ubiquitous dissolved nitrogen gas within otherwise nitrogen-poor sea water. they and the co-occurring k. brevis are posi ... | 2006 | 20411040 |
| is the distribution of nitrogen-fixing cyanobacteria in the oceans related to temperature? | approximately 50% of the global natural fixation of nitrogen occurs in the oceans supporting a considerable part of the new primary production. virtually all nitrogen fixation in the ocean occurs in the tropics and subtropics where the surface water temperature is 25°c or higher. it is attributed almost exclusively to cyanobacteria. this is remarkable firstly because diazotrophic cyanobacteria are found in other environments irrespective of temperature and secondly because primary production in ... | 2009 | 19397684 |
| combined effects of co2 and light on the n2-fixing cyanobacterium trichodesmium ims101: physiological responses. | recent studies on the diazotrophic cyanobacterium trichodesmium erythraeum (ims101) showed that increasing co(2) partial pressure (pco(2)) enhances n(2) fixation and growth. significant uncertainties remain as to the degree of the sensitivity to pco(2), its modification by other environmental factors, and underlying processes causing these responses. to address these questions, we examined the responses of trichodesmium ims101 grown under a matrix of low and high levels of pco(2) (150 and 900 mi ... | 2010 | 20625004 |
| population and trophic dynamics of trichodesmium thiebautii in the se lagoon of new caledonia. comparison with t. erythraeum in the sw lagoon. | while trichodesmium erythraeum is prevalent in the semi-closed sw lagoon of new caledonia, t. thiebautii is dominant in the more open se lagoon. this led to the comparison of the two species from the results of two high-frequency surveys focused on t. erythraeum (rodier and le borgne, 2008) and t. thiebautii (the present paper). (1) environmental conditions and triggers of the blooms are the same: calm weather and/or temperature >26 degrees c, and temporary nutrient inputs are required for both; ... | 2010 | 20638692 |
| the influence of pco2 and temperature on gene expression of carbon and nitrogen pathways in trichodesmium ims101. | growth, protein amount, and activity levels of metabolic pathways in trichodesmium are influenced by environmental changes such as elevated pco(2) and temperature. this study examines changes in the expression of essential metabolic genes in trichodesmium grown under a matrix of pco(2) (400 and 900 µatm) and temperature (25 and 31°c). using rt-qpcr, we studied 21 genes related to four metabolic functional groups: co(2) concentrating mechanism (bica1, bica2, ccmm, ccmk2, ccmk3, ndhf4, ndhd4, ndhl ... | 2010 | 21151907 |
| interactions between ccm and n(2) fixation in trichodesmium. | in view of the current increase in atmospheric pco(2) and concomitant changes in the marine environment, it is crucial to assess, understand, and predict future responses of ecologically relevant phytoplankton species. the diazotrophic cyanobacterium trichodesmium erythraeum was found to respond strongly to elevated pco(2) by increasing growth, production rates, and n(2) fixation. the magnitude of these co(2) effects exceeds those previously seen in other phytoplankton, raising the question abou ... | 2010 | 21190135 |
| comparative proteomic profiles of the marine cyanobacterium trichodesmium erythraeum ims101 under different nitrogen regimes. | trichodesmium is a marine filamentous diazotrophic cyanobacterium and an important contributor of "new" nitrogen in the oligotrophic surface waters of the tropical and sub-tropical oceans. it is unique in that it exclusively fixes n(2) at daytime, although it belongs to the non-heterocystous filamentous segment of the cyanobacterial radiation. here we present the first quantitative proteomic analysis of trichodesmium erythraeum ims101 when grown under different nitrogen regimes using 2-de/maldi- ... | 2011 | 21210425 |
| nitrogen fixation and nitrogenase (nifh) expression in tropical waters of the eastern north atlantic. | expression of nifh in 28 surface water samples collected during fall 2007 from six stations in the vicinity of the cape verde islands (north-east atlantic) was examined using reverse transcription-polymerase chain reaction (rt-pcr)-based clone libraries and quantitative rt-pcr (rt-qpcr) analysis of seven diazotrophic phylotypes. biological nitrogen fixation (bnf) rates and nutrient concentrations were determined for these stations, which were selected based on a range in surface chlorophyll conc ... | 2011 | 21228888 |
| comparative proteomic profiles of the marine cyanobacterium trichodesmium erythraeum ims101 under different nitrogen regimes. | trichodesmium is a marine filamentous diazotrophic cyanobacterium and an important contributor of "new" nitrogen in the oligotrophic surface waters of the tropical and sub-tropical oceans. it is unique in that it exclusively fixes n(2) at daytime, although it belongs to the non-heterocystous filamentous segment of the cyanobacterial radiation. here we present the first quantitative proteomic analysis of trichodesmium erythraeum ims101 when grown under different nitrogen regimes using 2-de/maldi- ... | 2011 | 21268270 |
| [community composition of phytoplankton in fujian-guangdong coastal upwelling region in summer and related affecting factors]. | based on the investigation data of 133 samples from 30 grid stations in the fujian-guangdong coastal upwelling region (21.6 degrees - 24.3 degrees n,115.7 degrees -118.7 degrees e) in 11-16 june 2009, this paper studied the phytoplankton species composition and cell abundance in the region in three dimensions (vertical, horizontal, and sectional), and approached their relations with major environmental factors. a total of 159 taxa belonging to 85 genera of 4 phyla were identified, among which, d ... | 2011 | 21608268 |
| identification of trichotoxin, a novel chlorinated compound associated with the bloom forming cyanobacterium, trichodesmium thiebautii. | trichodesmium is a suspected toxin-producing nonheterocystous cyanobacteria ubiquitous in tropical, subtropical, and temperate seas. the genus is known for its ability to fix nitrogen and form massive blooms. in oligotrophic seas, it can dominate the biomass and be a major component of oceanic primary production and global nitrogen cycling. numerous reports suggest trichodesmium-derived toxins are a cause of death of fish, crabs, and bivalves. laboratory studies have demonstrated neurotoxic effe ... | 2011 | 21740025 |
| first evidence of palytoxin and 42-hydroxy-palytoxin in the marine cyanobacterium trichodesmium. | marine pelagic diazotrophic cyanobacteria of the genus trichodesmium (oscillatoriales) are widespread throughout the tropics and subtropics, and are particularly common in the waters of new caledonia. blooms of trichodesmium are suspected to be a potential source of toxins in the ciguatera food chain and were previously reported to contain several types of paralyzing toxins. the toxicity of water-soluble extracts of trichodesmium spp. were analyzed by mouse bioassay and neuroblastoma assay and t ... | 2011 | 21731549 |
| Diversity and distribution of diazotrophic communities in the South China Sea deep basin with mesoscale cyclonic eddy perturbations. | The South China Sea (SCS) is an oligotrophic subtropical marginal ocean with a deep basin and a permanently stratified central gyre. Upwelling and nitrogen fixation provide new nitrogen for primary production in the SCS. This study was aimed at an investigation of phylogenetic diversity and quantification of the diazotroph community in the SCS deep basin, which is characterized by frequent mesoscale eddies. The diazotroph community had a relatively low diversity but a distinct spatial heterogene ... | 2011 | 22066702 |
| Quorum sensing control of phosphorus acquisition in Trichodesmium consortia. | Colonies of the cyanobacterium Trichodesmium are abundant in the oligotrophic ocean, and through their ability to fix both CO(2) and N(2), have pivotal roles in the cycling of carbon and nitrogen in these highly nutrient-depleted environments. Trichodesmium colonies host complex consortia of epibiotic heterotrophic bacteria, and yet, the regulation of nutrient acquisition by these epibionts is poorly understood. We present evidence that epibiotic bacteria in Trichodesmium consortia use quorum se ... | 2011 | 21900966 |
| Heterotrophic organisms dominate nitrogen fixation in the South Pacific Gyre. | Oceanic subtropical gyres are considered biological deserts because of the extremely low availability of nutrients and thus minimum productivities. The major source of nutrient nitrogen in these ecosystems is N(2)-fixation. The South Pacific Gyre (SPG) is the largest ocean gyre in the world, but measurements of N(2)-fixation therein, or identification of microorganisms involved, are scarce. In the 2006/2007 austral summer, we investigated nitrogen and carbon assimilation at 11 stations throughou ... | 2011 | 22170429 |
| acquisition of iron by trichodesmium and associated bacteria in culture. | trichodesmium colonies contain an abundant microbial consortium that is likely to play a role in nutrient cycling within the colony. this study used laboratory cultures of trichodesmium and two genome-sequenced strains of bacteria typical of trichodesmium-associated microbes to develop an understanding of the cycling of iron, a potentially limiting micronutrient, within trichodesmium colonies. we found that the ferric siderophores desferrioxamine b and aerobactin were not readily bioavailable to ... | 2011 | 22118517 |
| Isolation and characterization of the unicellular diazotrophic cyanobacterium Group C TW3 from the tropical western Pacific Ocean. | A unicellular diazotrophic cyanobacterium strain of Group C, designated TW3, was isolated from the oligotrophic Kuroshio Current of the western Pacific Ocean. To our knowledge, this represents the first successful laboratory culture of a Group C unicellular diazotroph from oceanic water. TW3 cells are green rods, 2.5-3.0 µm in width and 4.0-6.0 µm in length. Phylogenetic analyses of both 16S rRNA and nifH gene fragments indicated that the TW3 sequences were over 98% identical to those of the pre ... | 2011 | 21981769 |