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  • Cyanobacteria  (2)
  • Nitrogen fixation  (2)
  • Arsenate  (1)
  • Betaine lipids  (1)
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  • 1
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    Phosphorus supply drives rapid turnover of membrane phospholipids in the diatom Thalassiosira pseudonana (2011)
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © The Author(s), 2010. This is the author's version of the work. It is posted here by permission of Nature Publishing Group for personal use, not for redistribution. The definitive version was published in The ISME Journal 5 (2011): 1057–1060, doi:10.1038/ismej.2010.192.
    Description: In low phosphorus (P) marine systems phytoplankton replace membrane phospholipids with non-phosphorus lipids, but it is not known how rapidly this substitution occurs. Here, when cells of the model diatom Thalassiosira pseudonana were transferred from P-replete medium to P-free medium, the phospholipid content of the cells rapidly declined within 48 h from 45±0.9% to 21±4.5% of total membrane lipids; the difference was made up by non-phosphorus lipids. Conversely, when P-limited T. pseudonana were resupplied with P, cells reduced the percentage of their total membrane lipid contributed by a non-phosphorus lipid from 43±1.5% to 7.3±0.9% within 24 h, while the contribution by phospholipids rose from 2.2±0.1% to 44±3%. This dynamic phospholipid reservoir contained sufficient P to synthesize multiple haploid genomes, suggesting that phospholipid turnover could be an important P source for cells. Field observations of phytoplankton lipid content may thus reflect short-term changes in P supply and cellular physiology, rather than simply long-term adjustment to the environment.
    Description: This research was funded by NSF OCE-0646944 and OCE- 1045670 (B.V.M.), OCE-0723677 and OCE-0549794 (S.T.D.), and by the Graduate School, National Oceanography Centre, Southampton (P.M).
    Keywords: Betaine lipids ; DGCC ; Lipid substitution ; Non-phosphorus lipids ; Phosphatidylcholine ; Diatoms
    Repository Name: Woods Hole Open Access Server
    Type: Preprint
    Format: application/pdf
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  • 2
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    The depth-distribution of nitrogen fixation by Trichodesmium spp. colonies in the tropical–subtropical North Atlantic (2015)
    Elsevier
    Details
    Publication Date: 2022-05-25
    Description: © The Author(s), 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Deep Sea Research Part I: Oceanographic Research Papers 104 (2015): 72-91, doi:10.1016/j.dsr.2015.06.012.
    Description: Nitrogen fixation is an important yet still incompletely constrained component of the marine nitrogen cycle, particularly in the subsurface. A Video Plankton Recorder (VPR) survey in the subtropical North Atlantic found higher than expected Trichodesmium colony abundances at depth, leading to the hypothesis that deep nitrogen fixation in the North Atlantic may have been previously underestimated. Here, Trichodesmium colony abundances and modeled nitrogen fixation from VPR transects completed on two cruises in the tropical and subtropical North Atlantic in fall 2010 and spring 2011 were used to evaluate that hypothesis. A bio-optical model was developed based on carbon-normalized nitrogen fixation rates measured on those cruises. Estimates of colony abundance and nitrogen fixation were similar in magnitude and vertical and geographical distribution to conventional estimates in a recently compiled climatology. Thus, in the mean, VPR-based estimates of volume-specific nitrogen fixation rates at depth in the tropical North Atlantic were not inconsistent with estimates derived from conventional sampling methods. Based on this analysis, if Trichodesmium nitrogen fixation by colonies is underestimated, it is unlikely that it is due to underestimation of deep abundances by conventional sampling methods.
    Description: We gratefully acknowledge support of this research by NSF and NASA. A NASA Earth and Space Science Fellowship supported E. Olson's graduate studies.
    Keywords: Nitrogen fixation ; Trichodesmium spp. ; North Atlantic ; Video Plankton Recorder
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 3
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    Ocean urea fertilization for carbon credits poses high ecological risks (2008)
    Details
    Publication Date: 2022-05-26
    Description: Author Posting. © Elsevier B.V., 2008. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Marine Pollution Bulletin 56 (2008): 1049-1056, doi:10.1016/j.marpolbul.2008.03.010.
    Description: The proposed plan for enrichment of the Sulu Sea, Philippines, a region of rich marine biodiversity, with thousands of tonnes of urea in order to stimulate algal blooms and sequester carbon is flawed for multiple reasons. Urea is preferentially used as a nitrogen source by some cyanobacteria and dinoflagellates, many of which are neutrally or positively buoyant. Biological pumps to the deep sea are classically leaky, and the inefficient burial of new biomass makes the estimation of a net loss of carbon from the atmosphere questionable at best. The potential for growth of toxic dinoflagellates is also high, as many grow well on urea and some even increase their toxicity when grown on urea. Many toxic dinoflagellates form cysts which can settle to the sediment and germinate in subsequent years, forming new blooms even without further fertilization. If large-scale blooms do occur, it is likely that they will contribute to hypoxia in the bottom waters upon decomposition. Lastly, urea production requires fossil fuel usage, further limiting the potential for net carbon sequestration. The environmental and economic impacts are potentially great and need to be rigorously assessed.
    Description: This paper was developed under the Global Ecology and Oceanography of Harmful Algal Blooms (GEOHAB) core research project on HABs and Eutrophication and the GEOHAB regional focus on HABs in Asia. GEOHAB is supported by the International Oceanographic Commission (IOC) of UNESCO and by the Scientific Committee on Oceanic Research (SCOR), which are, in turn, supported by multiple agencies, including NSF and NOAA of the USA.
    Keywords: Urea dumping ; Ocean fertilization ; Carbon credits ; Sulu Sea ; Carbon sequestration ; Harmful algae ; Toxic dinoflagellates ; Cyanobacteria ; Hypoxia
    Repository Name: Woods Hole Open Access Server
    Type: Preprint
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  • 4
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    Trichodesmium AHL amendment metatranscriptomic reads accessions and metadata (2019)
    Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu
    Details
    Publication Date: 2022-10-31
    Description: Dataset: Trichodesmium AHL metatranscriptomes_AE1409
    Description: Trichodesmium is a marine, diazotrophic cyanobacterium that plays a central role in the biogeochemical cycling of carbon and nitrogen. Colonies ubiquitously co-occur with a diverse microbiome of heterotrophic bacteria. Here we show that manipulation of the microbiome with quorum sensing acyl homoserine lactone (AHL) molecules significantly modulated rates of N2 fixation by Trichodesmium collected from the western North Atlantic, with both positive and negative effects of varied magnitude. Changes in Trichodesmium N2 fixation did not clearly correlate with changes in microbiome composition or geochemical patterns. Metatranscriptome sequencing revealed significant changes in the relative abundance of microbiome transcripts encoding metabolic functions consistent with quorum sensing responses in model bacteria. There was little overlap in specific microbiome transcriptional responses to AHL addition between stations, and this variability in microbiome gene expression may underpin the heterogeneous changes in Trichodesmium N2 fixation. These data suggest the microbiome could play a large and previously overlooked role in modulating Trichodesmium N2 fixation. This metadata form describes the metatranscriptomic sequencing reads that were used in the study. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/746654
    Description: NSF Division of Ocean Sciences (NSF OCE) OCE-1332898, NSF Division of Ocean Sciences (NSF OCE) OCE-1332912
    Keywords: Trichodesmium ; Metatranscriptome ; Quorum sensing ; Nitrogen fixation
    Repository Name: Woods Hole Open Access Server
    Type: Dataset
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  • 5
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    Arsenate resistance in the unicellular marine diazotroph Crocosphaera watsonii (2014)
    Frontiers Media
    Details
    Publication Date: 2022-05-26
    Description: © The Author(s), 2011. This is an open-access article subject to a non-exclusive license between the authors and Frontiers Media SA, which permits use, distribution and reproduction in other forums, provided the original authors and source are credited. The definitive version was published in Frontiers in Microbiology 2 (2011): 214, doi:10.3389/fmicb.2011.00214.
    Description: The toxic arsenate ion can behave as a phosphate analog, and this can result in arsenate toxicity especially in areas with elevated arsenate to phosphate ratios like the surface waters of the ocean gyres. In these systems, cellular arsenate resistance strategies would allow phytoplankton to ameliorate the effects of arsenate transport into the cell. Despite the potential coupling between arsenate and phosphate cycling in oligotrophic marine waters, relatively little is known about arsenate resistance in the nitrogen-fixing marine cyanobacteria that are key components of the microbial community in low nutrient systems. The unicellular diazotroph, Crocosphaera watsonii WH8501, was able to grow at reduced rates with arsenate additions up to 30 nM, and estimated arsenate to phosphate ratios of 6:1. The genome of strain WH8501 contains homologs for arsA, arsH, arsB, and arsC, allowing for the reduction of arsenate to arsenite and the pumping of arsenite out of the cell. The short-term addition of arsenate to the growth medium had no effect on nitrogen fixation. However, arsenate addition did result in the up-regulation of the arsB gene with increasing arsenate concentrations, indicating the induction of the arsenate detoxification response. The arsB gene was also up-regulated by phosphorus stress in concert with a gene encoding the high-affinity phosphate binding protein pstS. Both genes were down-regulated when phosphate was re-fed to phosphorus-stressed cells. A field survey of surface water from the low phosphate western North Atlantic detected expression of C. watsonii arsB, suggestive of the potential importance of arsenate resistance strategies in this and perhaps other systems.
    Description: This research was funded in part by the National Science Foundation #OCE-0451419, and the Center for Microbial Oceanography: Research and Education.
    Keywords: Cyanobacteria ; Phosphorus ; Marine ; Arsenate ; Diazotroph ; Crocosphaera
    Repository Name: Woods Hole Open Access Server
    Type: Article
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