Transcriptomic profiling of an oceanic diatom adapted to Cu deficiency
Ontology highlight
ABSTRACT:
ORGANISM(S): Thalassiosira oceanica CCMP1005
PROVIDER: GSE188999 | GEO | 2021/11/19
REPOSITORIES: GEO
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Project description:Copper (Cu) plays an essential role in cellular metabolism and limits phytoplankton growth and production in parts of the open sea. Whole transcriptome analysis provides a powerful tool to explore gene expression profiles and cellular metabolic pathways regulated by Cu. In this study, we identified Cu-regulated genes by profiling the transcriptomes of an oceanic diatom, Thalassiosira oceanica 1005, adapted to survive in a Cu-limited and Cu-replete environment. The results provide insights to the mechanisms of adaptation and acclimation of T. oceanica to low Cu environments.
2020-02-29 | GSE145010 | GEO
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Project description:Iron (Fe) and phosphorus (P) are essential nutrients with close geochemical association. They exist at low concentrations in surface waters and may be co-limiting resources for phytoplankton growth. However, the adaptive strategies of photosynthetic organisms to Fe/P co-limitation remain largely unknown. Here, we show that phosphorus deficiency increases the growth of Fe-limited cyanobacteria through a PhoB-mediated regulatory network. In addition to its well-recognized role in controlling phosphate homeostasis, PhoB regulates key metabolic processes crucial for Fe-limited cyanobacteria, including ROS detoxification and Fe uptake. Transcript abundances of PhoB-targeted genes are enriched in samples from the P-deplete ocean, and a conserved PhoB binding site is widely present in the promoters of the targets, suggesting that the strategy we discovered may be highly conserved. Our findings provide important molecular insights into the response of cyanobacteria to simultaneous Fe/P nutrient limitation and help in understanding how nutrient availability affects primary productivity in aquatic environments.
2024-03-06 | GSE260812 | GEO
Project description:Phosphorus is a critical nutrient controlling phytoplankton growth. Availability of this limiting factor can vary significantly in space and time, particularly in dynamic aquatic ecosystems. Diatoms are important eukaryotic phytoplankton that thrive in regions of pulsed phosphate supply, yet little is known of the sensory mechanisms enabling them to detect and rapidly respond to phosphorus availability. Here we show that phosphorus-starved diatoms utilise a novel Ca2+-dependent signalling pathway to sense and regulate cellular recovery following phosphorus resupply. This pathway, which has not previously been described in eukaryotes, is sensitive to sub-micromolar concentrations of phosphate, alongside a range of environmentally relevant phosphorus forms. Using comparative proteomics, we have characterised early adaptations governing diatom cellular recovery from phosphorus limitation. Strikingly, the dominant response was substantial enhancement of nitrogen assimilation proteins. This led to 12-fold increases in absolute nitrate uptake rates, relative to phosphorus-starved cells. Moreover, we find that the novel phosphorus-Ca2+ signalling pathway controls this primary recovery response. Our findings highlight that fundamental cross-talk between the essential nutrients phosphorus and nitrogen drive diatom recovery from phosphorus limitation. Moreover, a novel Ca2+-dependent phosphorus signalling pathway governs such ecological acclimation responses, and is thus likely critical to the success of diatoms in regions of episodic nutrient supply.
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Project description:The global transcriptional response of Saccharomyces cerevisiae was investigated in low temperature chemostat cultures grown in carbon or nitrogen limitation. During steady state chemostats, the growth rates and in vivo fluxes were kept constant however the growth-limiting nutrient was significantly higher at 12oC than at 30oC and had significant effects on transcriptional responses. Growth at 12oC resulted in a rearrangement of transporters for the limiting nutrient, where hexose transporters (HXTs) and ammonium permeases (MEPs) were differentially expressed in cultures grown at 30oC in carbon and nitrogen limitations, respectively. In addition, we found repression of genes encoding proteins in reserve carbohydrates metabolism and metabolism of alternative carbon or nitrogen sources other than glucose or ammonia. However, there were also similar responses when the transcriptional response was evaluated regardless of the growth-limiting nutrient. In particular, induction of ribosome biogenesis genes emphasizes the significance of transcription and translational adaptation at low temperature. In contrast, genes encoding proteins during stress response were downregulated. This down-regulation of stress elements better known as environmental stress response (ESR) is in contradiction with previous low temperature transcriptome analyses. During continuous steady state low temperature cultivation, ESR no longer plays an integral role in S. cerevisiaeM-bM-^@M-^Ys response to temperature change. Similarly, trehalose accumulation, consistent with its gene expression, was not indispensable for growth at 12oC. This response, however, does not exclude that ESR may be required for transition phase in low temperature growth when cells are transferred from one temperature to another. Keywords: chemostat temperature 12 degree celsuis 30 degree celsius The global transcriptional response of Saccharomyces cerevisiae was investigated in low temperature chemostat cultures grown in carbon or nitrogen limitation at a dilution rate of 0.03h-1
2007-01-20 | E-GEOD-6190 | biostudies-arrayexpress
Project description:Copper-limiting growth conditions were thought to cause an induction of genes possibly involved in copper uptake and sorting. This rationale in mind, we performed microarray analyses on B. japonicum cells grown in three variations of the BVM minimal medium. Variant 1 contained 2 M-NM-<M CuSO4 (copper excess). Variant 2 was prepared in HCl-treated glassware without any copper added (copper starvation). The residual copper concentration in this copper-starvation medium was analyzed by GF-AAS and determined to be 5 nM. Variant 3 (extreme copper limitation) was prepared like variant 2 but with the addition of 10 M-NM-<M BCS and 1 mM ascorbic acid where BCS chelates Cu(I) selectively, and ascorbic acid reduces any Cu(II) to Cu(I). Changes in the transcription profiles were recorded by the pairwise comparison of cells grown in variant 2 vs. 1, and variant 3 vs. 2. Only a small set of genes were differentially up- or down-regulated when copper-starved cells were compared with cells grown in copper excess. Most notably, five genes located adjacent to each other on the B. japonicum genome displayed an increased expression: bll4882 to bll4878. The five genes were named pcuA, pcuB, pcuC, pcuD, and pcuE (mnemonic of proteins for Cu trafficking). The genes with decreased expression are either of unknown function or M-bM-^@M-^S not surprisingly M-bM-^@M-^S play a role in copper resistance. Extreme copper limitation (variant 3 vs. 2) did not further enhance the expression of the five pcu genes. Instead, another cluster of adjacent genes was strongly up-regulated: bll0889 to bll0883, which code for unidentified transport functions. Incidentally, the list also includes the copper chaperone ScoI. Taken together, copper-limiting growth conditions have led to the de-repression of genes potentially involved in copper acquisition. Microarray-based transcriptome analysis of B. japonicum 110spc4 wild-type cells grown under normal, copper-limiting and copper excess conditions
2012-10-01 | E-GEOD-40437 | biostudies-arrayexpress
Project description:Like many microalgae unicellular green alga, Chlamydomonas reinhardtii also accumulates energy rich storage lipid and starch under nutrient-limited conditions, such as phosphorus (P) and nitrogen (N) limitation. To dissect the transcriptional regulation of lipid and starch biosynthesis in response to nutrient limitation, we have characterized the biological role of a candidate regulator: the MYB family transcription factor, PSR1 (phosphorus starvation response 1). Genetically modified (psr1 compromised) and wild-type lines were grown under P limiting and sufficient conditions and assayed at two time points by SOLiD RNA-seq.
2016-01-08 | E-MTAB-2556 | biostudies-arrayexpress
Project description:Zinc is an essential nutrient because of its role in catalysis and in stabilizing protein structure, but excess zinc can also be deleterious. Four nutritional zinc states have been identified in the alga Chlamydomonas reinhardtii: zinc toxic, zinc replete, zinc deficient and zinc limited. Growth is inhibited in zinc-limited and zinc toxic cells relative to zinc-replete cells, while zinc-deficiency is visually asymptomatic but distinguished by the accumulation of transcripts encoding ZIP family transporters. To identify targets of zinc deficiency and mechanisms of zinc acclimation, we used RNA-seq to probe zinc nutrition responsive changes in gene expression. We identified a subset of genes encoding zinc-handling components, including ZIP family transporters and candidate zinc chaperones. In addition, we noted an impact on two other regulatory pathways, the carbon concentrating mechanism (CCM) and the nutritional copper regulon. Targets of transcription factor Ccm1 and various CAH genes are up-regulated in zinc-deficiency, as a likely consequence of reduced carbonic anhydrase activity, which is validated by mass spectrometry and immunoblot analysis of Cah1, Cah3 and Cah4. Chlamydomonas is therefore not able to grow photoautotrophically in air in zinc limiting conditions, but supplementation with 1% CO2 restores growth to wild-type rates, suggesting that the inability to maintain CCM is a major consequence of zinc limitation. Surprisingly, we noted also that the Crr1 regulon, which responds to Cu limitation, is also turned on in zinc deficiency, and in fact, Crr1 is required for growth in zinc-limiting conditions. Zinc deficient cells are functionally copper deficient, as evidenced by reduced plastocyanin abundance, even though they hyperaccumulate copper up to 50-fold over normal levels. We suggest that zinc-deficient cells sequester Cu in a bio-unavailable form, perhaps to prevent mis-metallation of critical zinc sites. Zn-limited wild-type cells were generated by transfer of cells from the first round of growth in medium with no supplemental Zn into TAP medium supplemented or not with 2.5 µM Zn-EDTA The control samples for this study are represented in GSE25622
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