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Environmental nitrogen and phosphorus nutrient variability triggers intracellular resource reallocation in Gracilariopsis lemaneiformis (Rhodophyta). ALGAL RES 2022. [DOI: 10.1016/j.algal.2022.102778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
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Berthold M, Campbell DA. Restoration, conservation and phytoplankton hysteresis. CONSERVATION PHYSIOLOGY 2021; 9:coab062. [PMID: 34394942 PMCID: PMC8361504 DOI: 10.1093/conphys/coab062] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/26/2020] [Revised: 06/10/2021] [Accepted: 07/22/2021] [Indexed: 06/13/2023]
Abstract
Phytoplankton growth depends not only upon external factors that are not strongly altered by the presence of phytoplankton, such as temperature, but also upon factors that are strongly influenced by activity of phytoplankton, including photosynthetically active radiation, and the availability of the macronutrients carbon, nitrogen, phosphorus and, for some, silicate. Since phytoplankton therefore modify, and to an extent create, their own habitats, established phytoplankton communities can show resistance and resilience to change, including managed changes in nutrient regimes. Phytoplankton blooms and community structures can be predicted from the overall biogeochemical setting and inputs, but restorations may be influenced by the physiological responses of established phytoplankton taxa to nutrient inputs, temperature, second-order changes in illumination and nutrient recycling. In this review we discuss the contributions of phytoplankton ecophysiology to biogeochemical hysteresis and possible effects on community composition in the face of management, conservation or remediation plans.
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Affiliation(s)
- Maximilian Berthold
- Department of Biology, Mount Allison University, Sackville, New Brunswick E4L 1C9, Canada
| | - Douglas A Campbell
- Department of Biology, Mount Allison University, Sackville, New Brunswick E4L 1C9, Canada
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Nutrient-Colimited Trichodesmium as a Nitrogen Source or Sink in a Future Ocean. Appl Environ Microbiol 2018; 84:AEM.02137-17. [PMID: 29180365 DOI: 10.1128/aem.02137-17] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Accepted: 11/16/2017] [Indexed: 11/20/2022] Open
Abstract
Nitrogen-fixing (N2) cyanobacteria provide bioavailable nitrogen to vast ocean regions but are in turn limited by iron (Fe) and/or phosphorus (P), which may force them to employ alternative nitrogen acquisition strategies. The adaptive responses of nitrogen fixers to global-change drivers under nutrient-limited conditions could profoundly alter the current ocean nitrogen and carbon cycles. Here, we show that the globally important N2 fixer Trichodesmium fundamentally shifts nitrogen metabolism toward organic-nitrogen scavenging following long-term high-CO2 adaptation under iron and/or phosphorus (co)limitation. Global shifts in transcripts and proteins under high-CO2/Fe-limited and/or P-limited conditions include decreases in the N2-fixing nitrogenase enzyme, coupled with major increases in enzymes that oxidize trimethylamine (TMA). TMA is an abundant, biogeochemically important organic nitrogen compound that supports rapid Trichodesmium growth while inhibiting N2 fixation. In a future high-CO2 ocean, this whole-cell energetic reallocation toward organic nitrogen scavenging and away from N2 fixation may reduce new-nitrogen inputs by Trichodesmium while simultaneously depleting the scarce fixed-nitrogen supplies of nitrogen-limited open-ocean ecosystems.IMPORTANCE Trichodesmium is among the most biogeochemically significant microorganisms in the ocean, since it supplies up to 50% of the new nitrogen supporting open-ocean food webs. We used Trichodesmium cultures adapted to high-CO2 conditions for 7 years, followed by additional exposure to iron and/or phosphorus (co)limitation. We show that "future ocean" conditions of high CO2 and concurrent nutrient limitation(s) fundamentally shift nitrogen metabolism away from nitrogen fixation and instead toward upregulation of organic nitrogen-scavenging pathways. We show that the responses of Trichodesmium to projected future ocean conditions include decreases in the nitrogen-fixing nitrogenase enzymes coupled with major increases in enzymes that oxidize the abundant organic nitrogen source trimethylamine (TMA). Such a shift toward organic nitrogen uptake and away from nitrogen fixation may substantially reduce new-nitrogen inputs by Trichodesmium to the rest of the microbial community in the future high-CO2 ocean, with potential global implications for ocean carbon and nitrogen cycling.
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Hong H, Shen R, Zhang F, Wen Z, Chang S, Lin W, Kranz SA, Luo YW, Kao SJ, Morel FMM, Shi D. The complex effects of ocean acidification on the prominent N2-fixing cyanobacteriumTrichodesmium. Science 2017; 356:527-531. [DOI: 10.1126/science.aal2981] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 04/12/2017] [Indexed: 11/02/2022]
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Wu S, Zhou J, Xin Y, Xue S. Nutritional stress effects under different nitrogen sources on the genes in microalga Isochrysis zhangjiangensis and the assistance of Alteromonas macleodii in releasing the stress of amino acid deficiency. JOURNAL OF PHYCOLOGY 2015; 51:885-895. [PMID: 26986885 DOI: 10.1111/jpy.12328] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2015] [Accepted: 07/03/2015] [Indexed: 06/05/2023]
Abstract
The expressions of nine nitrogen assimilation-associated genes, NRT2, NAR1, NIA2, NIR, GLN2, GLSF, GSN1, GDH, and AAT2, in the microalga Isochrysis zhangjiangensis were investigated to unveil the effects of limitations of various nitrogen sources (NaNO3 , NH4 Cl, NaNO2 , and an amino acid mixture) on the microalgae. The results demonstrated that the NRT2, NAR1, GLN2, GSN1, and AAT2 genes were highly expressed in lipid-rich microalgae under inorganic nitrogen-deficient conditions and they decreased after nitrogen resupply. Significant increases in the expressions of NAR1, GLN2, and GLSF were found in nitrate-depleted microalgae, whereas significant increases in the expressions of NRT2, NAR1, GLN2, and GSN1 were found in nitrite-depleted microalgae. Significant increases in the expressions of only NRT2 and GSN1 were found in ammonium-depleted microalgae (P < 0.05). Except for the NRT2, other genes were expressed at lower levels under amino acid-deficient conditions compared with amino acid-sufficient controls. The expression of the NIA2 gene decreased in nitrogen-depleted microalgae regardless of the initial nitrogen source. However, the results of fatty acid analyses showed that the features of fatty acid profiles followed a similar mode, in which the percentage compositions of C16:0 and C18:1Δ(9) increased in nitrogen-depleted cells and that of C16:1Δ(9) , C18:3Δ(9,12,15) , C18:4Δ(6,9,12,15) , and C18:5Δ(3,6,9,12,15) decreased, regardless of the type of nitrogen source applied. It was also found that the epiphytic bacterium Alteromonas macleodii played a particularly important role in releasing microalgae from the stress of amino acid deficiency. These findings also provide a foundation for regulating microalgal lipid production through manipulation of the nitrogen assimilation-associated genes.
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Affiliation(s)
- Shuang Wu
- Marine Bioproducts Engineering Group, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning, 116023, China
| | - Jiannan Zhou
- Marine Bioproducts Engineering Group, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning, 116023, China
| | - Yanjuan Xin
- Marine Bioproducts Engineering Group, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning, 116023, China
| | - Song Xue
- Marine Bioproducts Engineering Group, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning, 116023, China
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The primary transcriptome of the marine diazotroph Trichodesmium erythraeum IMS101. Sci Rep 2014; 4:6187. [PMID: 25155278 PMCID: PMC4143802 DOI: 10.1038/srep06187] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Accepted: 08/04/2014] [Indexed: 01/03/2023] Open
Abstract
Blooms of the dinitrogen-fixing marine cyanobacterium Trichodesmium considerably contribute to new nitrogen inputs into tropical oceans. Intriguingly, only 60% of the Trichodesmium erythraeum IMS101 genome sequence codes for protein, compared with ~85% in other sequenced cyanobacterial genomes. The extensive non-coding genome fraction suggests space for an unusually high number of unidentified, potentially regulatory non-protein-coding RNAs (ncRNAs). To identify the transcribed fraction of the genome, here we present a genome-wide map of transcriptional start sites (TSS) at single nucleotide resolution, revealing the activity of 6,080 promoters. We demonstrate that T. erythraeum has the highest number of actively splicing group II introns and the highest percentage of TSS yielding ncRNAs of any bacterium examined to date. We identified a highly transcribed retroelement that serves as template repeat for the targeted mutation of at least 12 different genes by mutagenic homing. Our findings explain the non-coding portion of the T. erythraeum genome by the transcription of an unusually high number of non-coding transcripts in addition to the known high incidence of transposable elements. We conclude that riboregulation and RNA maturation-dependent processes constitute a major part of the Trichodesmium regulatory apparatus.
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Bergman B, Sandh G, Lin S, Larsson J, Carpenter EJ. Trichodesmium--a widespread marine cyanobacterium with unusual nitrogen fixation properties. FEMS Microbiol Rev 2012; 37:286-302. [PMID: 22928644 PMCID: PMC3655545 DOI: 10.1111/j.1574-6976.2012.00352.x] [Citation(s) in RCA: 111] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Revised: 08/13/2012] [Accepted: 08/21/2012] [Indexed: 12/03/2022] Open
Abstract
The last several decades have witnessed dramatic advances in unfolding the diversity and commonality of oceanic diazotrophs and their N2-fixing potential. More recently, substantial progress in diazotrophic cell biology has provided a wealth of information on processes and mechanisms involved. The substantial contribution by the diazotrophic cyanobacterial genus Trichodesmium to the nitrogen influx of the global marine ecosystem is by now undisputable and of paramount ecological importance, while the underlying cellular and molecular regulatory physiology has only recently started to unfold. Here, we explore and summarize current knowledge, related to the optimization of its diazotrophic capacity, from genomics to ecophysiological processes, via, for example, cellular differentiation (diazocytes) and temporal regulations, and suggest cellular research avenues that now ought to be explored.
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Nuester J, Vogt S, Newville M, Kustka AB, Twining BS. The unique biogeochemical signature of the marine diazotroph trichodesmium. Front Microbiol 2012; 3:150. [PMID: 22557997 PMCID: PMC3337509 DOI: 10.3389/fmicb.2012.00150] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Accepted: 03/30/2012] [Indexed: 11/13/2022] Open
Abstract
The elemental composition of phytoplankton can depart from canonical Redfield values under conditions of nutrient limitation or production (e.g., N fixation). Similarly, the trace metal metallome of phytoplankton may be expected to vary as a function of both ambient nutrient concentrations and the biochemical processes of the cell. Diazotrophs such as the colonial cyanobacteria Trichodesmium are likely to have unique metal signatures due to their cell physiology. We present metal (Fe, V, Zn, Ni, Mo, Mn, Cu, Cd) quotas for Trichodesmium collected from the Sargasso Sea which highlight the unique metallome of this organism. The element concentrations of bulk colonies and trichomes sections were analyzed by ICP-MS and synchrotron x-ray fluorescence, respectively. The cells were characterized by low P contents but enrichment in V, Fe, Mo, Ni, and Zn in comparison to other phytoplankton. Vanadium was the most abundant metal in Trichodesmium, and the V quota was up to fourfold higher than the corresponding Fe quota. The stoichiometry of 600C:101N:1P (mol mol(-1)) reflects P-limiting conditions. Iron and V were enriched in contiguous cells of 10 and 50% of Trichodesmium trichomes, respectively. The distribution of Ni differed from other elements, with the highest concentration in the transverse walls between attached cells. We hypothesize that the enrichments of V, Fe, Mo, and Ni are linked to the biochemical requirements for N fixation either directly through enrichment in the N-fixing enzyme nitrogenase or indirectly by the expression of enzymes responsible for the removal of reactive oxygen species. Unintentional uptake of V via P pathways may also be occurring. Overall, the cellular content of trace metals and macronutrients differs significantly from the (extended) Redfield ratio. The Trichodesmium metallome is an example of how physiology and environmental conditions can cause significant deviations from the idealized stoichiometry.
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Affiliation(s)
- Jochen Nuester
- Bigelow Laboratory for Ocean SciencesEast Boothbay, ME, USA
| | - Stefan Vogt
- X-ray Science Division, Advanced Photon Source, Argonne National LaboratoryArgonne, IL, USA
| | - Matthew Newville
- Center for Advanced Radiation Sources, The University of ChicagoArgonne, IL, USA
| | - Adam B. Kustka
- Department of Earth and Environmental Sciences, Rutgers UniversityNewark, NJ, USA
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Sandh G, Xu L, Bergman B. Diazocyte development in the marine diazotrophic cyanobacterium Trichodesmium. MICROBIOLOGY-SGM 2011; 158:345-352. [PMID: 22053003 DOI: 10.1099/mic.0.051268-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
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 3-8 h, 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 trichomes correlates with the localization of mature diazocytes, which suggests that pattern regulation is an early event during diazocyte development. The development was initially identified as changes in the subcellular ultrastructure, most notably the degradation of glycogen granules and gas vacuoles. These changes were preceded by the induced expression of the global nitrogen regulator ntcA at an early stage of combined nitrogen deprivation, followed by elevated expression of genes related to nitrogen metabolism and their corresponding proteins. The strongest induction (10-fold) was related to the transcription of the respiratory gene coxB2, apparent already at an early stage, which suggests an important role for respiration and the subsequent energy generation in the subcellular changes found, and in the creation of the reducing environment required for nitrogen fixation in diazocytes.
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Affiliation(s)
- Gustaf Sandh
- Department of Botany, Stockholm University, S-106 91 Stockholm, Sweden
| | - Linghua Xu
- Department of Botany, Stockholm University, S-106 91 Stockholm, Sweden
| | - Birgitta Bergman
- Department of Botany, Stockholm University, S-106 91 Stockholm, Sweden
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