Development and application of a microarray for assessing gene transcription in open ocean microbial communities.
Ontology highlight
ABSTRACT:
ORGANISM(S): uncultured marine microorganism
SUBMITTER: Irina Shilova
PROVIDER: E-GEOD-44448 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
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Project description:We investigated the gene expression responses of Candidatus Pelagibacter ubique cultures to iron limitation. Differential expression was observed for genes in iron acquisition and incorporation operons. SfuC in particular was 16 times higher in iron-limited cultures and encodes a periplasmic iron-binding protein. Six natural seawater cultures were amended with minimal nutrients and inoculated with P. ubique. Close to maximum cell density, all carboys were supplemented with 100 nM ferrichrome (an iron-chelating siderophore) and three carboys were additionally supplemented with 1 µM FeCl3. Each of the six carboys was sampled for microarray analyses one, two, and eleven days after the ferrichrome addition.
2010-05-05 | E-GEOD-20962 | biostudies-arrayexpress
Project description:Nitrogen is one of the major nutrients limiting microbial productivity in the ocean, and as a result marine microorganisms have evolved specialized systems for responding to nitrogen stress. The highly abundant alphaproteobacterium Candidatus Pelagibacter ubique lacks the canonical GlnB, GlnD, and NtrB/NtrC genes for regulating nitrogen assimilation. A survey of 127 Alphaproteobacteria genomes found these genes to be highly represented in free-living and pathogenic organisms with large genomes and only missing in a subset of obligate intracellular organisms and other SAR11 strains. We examined global differences in mRNA and protein expression in Ca. P. ubique strain HTCC1062 during nitrogen-limited and nitrogen-replete stationary phase to understand how this thriving organism responds to nitrogen limitation. Transporters for ammonium (AmtB), taurine (TauA), amino acids (YhdW), and opines (OccT) were all elevated in nitrogen-limited cells, indicating they devote increased resources to the assimilation of nitrogenous compounds. Enzymes for assimilating amine into glutamine (GlnA) and glutamate (AspC, GltBD) were similarly up-regulated. Differential regulation of the transcriptional regulator NtrX in the two-component signaling system NtrY/NtrX was also observed, implicating it in the control of the nitrogen starvation response. Comparisons of the transcriptome and proteome suggest that Amt is post-transcriptionally repressed during nitrogen limitation, supporting previous studies that computationally identified a novel cis-acting riboswitch upstream of this gene. These observations support the conclusion that Ca. P. ubique has an unusually simple regulatory system that enables it to increase its capacity for the uptake of nitrogenous compounds in response to nitrogen limitation. Batch cultures of P. ubique were grown in a defined arificial seawater media. Three cultures were given no nitrogen amendment, and three other cultures received an excess concentration of NH3. Cultures were harvested for microarray analyses during log and stationary phase for the purpose of observing differences in gene expression related to nitrogen limitation. Proteomic analysis was conducted in parallel and is available at http://omics.pnl.gov .
2013-09-01 | E-GEOD-37445 | biostudies-arrayexpress
Project description:Plants and rhizosphere microbes rely closely on each other, with plants supplying carbon to bacteria in root exudates, and bacteria mobilizing soil-bound phosphate for plant nutrition. When the phosphate supply becomes limiting for plant growth, the composition of root exudation changes, affecting rhizosphere microbial communities and microbially-mediated nutrient fluxes. To evaluate how plant phosphate deprivation affects rhizosphere bacteria, Lolium perenne seedlings were root-inoculated with Pseudomonas aeruginosa 7NR, and grown in axenic microcosms under different phosphate regimes (330 uM vs 3-6 uM phosphate). The effect of biological nutrient limitation was examined by DNA microarray studies of rhizobacterial gene expression.
2011-07-01 | E-MEXP-2812 | biostudies-arrayexpress
Project description:Lipid accumulation by oleaginous microorganisms is of great scientific interest and biotechnological potential. While nitrogen limitation has been routinely employed, low-cost raw materials usually contain rich nitrogenous components, thus preventing from efficient lipid production. Inorganic phosphate (Pi) limitation has been found sufficient to promote conversion of sugars into lipids, yet the molecular basis of cellular response to Pi-limitation and concurrent lipid accumulation remains elusive. Here we performed multi-omic analyses of the oleaginous yeast Rhodosporidium toruloides to shield lights on Pi-limitation induced lipid accumulation. Samples were prepared under Pi-limited as well as Pi-replete chemostat conditions, and subjected to analysis at the transcriptomic, proteomic and metabolomic level. In total, 7970 genes, 4212 proteins and 123 metabolites were identified. Results showed that Pi-limitation facilitates up-regulation of Pi-associated metabolism, RNA degradation and triacylglycerol biosynthesis, while down-regulation of ribosome biosynthesis and tricarboxylic acid cycle. Pi-limitation leads to de-phosphorylation of adenosine monophosphate, the allosteric activator of isocitrate dehydrogenase key to lipid biosynthesis. It was found that NADPH, the key cofactor for fatty acid biosynthesis, is limited due to reduced flux through the pentose phosphate pathway and transhydrogenation cycle, and that this can be overcomed by overexpression of an endogenous malic enzyme. These phenomena are found distinctive from those under nitrogen-limitation. The information greatly enriches our understanding on microbial oleaginicity and Pi-related metabolism. Importantly, systems data may facilitate designing advanced cell factories for production of lipids and related oleochemicals.
2018-05-31 | GSE113097 | GEO
Project description:Candidatus Pelagibacter ubique is the most abundant marine microorganism, but is unable to utilize inorganic sulfur compounds that are plentiful in the ocean. To investigate how these cells adapt to organic sulfur limitation, batch cultures were grown in defined media containing either limiting or non-limiting amounts of dimethylsulfoniopropionate (DMSP) as the sole sulfur source. Protein and mRNA expression were measured during exponential growth, immediately prior to stationary phase, and in late stationary phase. Two distinct responses were observed: one as DMSP approached exhaustion, and another after the DMSP supply was depleted. The first response was characterized by increased transcription and translation of all Ca. P. ubique genes downstream of previously confirmed S-adenosyl methionine (SAM) riboswitches: bhmT, mmuM, and metY. These genes were up to 33 times more abundant during low DMSP conditions and shunt all available sulfur to methionine. The osmotically inducible organic hydroperoxidase OsmC was the most up-regulated protein as DMSP (an osmolyte) became scarce. The second response, during sulfur-depleted stationary phase, saw increased transcription of the heme c shuttle ccmC and two small genes of unknown function (SAR11_1163 and SAR11_1164) which were 6-10 times higher in sulfur-starved cultures. No known membrane transporters were up-regulated in response to sulfur limitation, suggesting that this bacterium's strategy for coping with sulfur stress focuses on intracellularly redistributing, rather than importing, organic sulfur compounds. This supports the conclusion that the few organosulfur molecules that Ca. P. ubique is able to metabolize are rarely limiting in the marine environment. Batch cultures of P. ubique were grown in a defined arificial seawater media. Five cultures were amended with a limiting concentration of DMSP as the sole sulfur source and another four control cultures were amended with a non-limiting DMSP concentration. Cultures were harvested for microarray analyses at multiple timepoints for the purpose of observing differences in gene expression related to sulfur limitation. Proteomic analyses were conducted in parallel and are available at https://www.ebi.ac.uk/pride/archive/projects/PXD003672 .
2016-06-26 | E-GEOD-31630 | biostudies-arrayexpress
Project description:A short-term microcosm experiment was conducted to evaluate the impact of wastewater discharge on coastal microbial communities. Coastal seawater was exposed to two types of treated wastewater: (i) unfiltered wastewater, containing nutrients, pollutants, and allochthonous microbes, and (ii) filtered wastewater, which retained only nutrients and pollutants while removing microbial components. Metaproteomic samples were collected from the coastal seawater prior to the experiment and from each experimental flask at the late exponential growth phase to assess microbial functional responses to wastewater exposure.
2025-05-09 | PXD061573 | Pride
Project description:Copper and iron are essential micronutrients for most living organisms because they participate as cofactors in biological processes including respiration, photosynthesis and oxidative stress protection. In many eukaryotic organisms, including yeast and mammals, copper and iron homeostases are highly interconnected; however such interdependence is not well established in higher plants. Here we propose that COPT2, a high-affinity copper transport protein, functions under copper and iron deficiencies in Arabidopsis thaliana. COPT2 is a plasma membrane protein that functions in copper acquisition and distribution. Characterization of the COPT2 expression pattern indicates a synergic response to copper and iron limitation in roots. We have characterized a knockout of COPT2, copt2-1, that leads to increased resistance to simultaneous copper and iron deficiencies, measured as reduced leaf chlorosis and improved maintenance of the photosynthetic apparatus. We propose that COPT2 expression could play a dual role under Fe deficiency. First, COPT2 participates in the attenuation of copper deficiency responses driven by iron limitation maybe aimed to minimize further iron consume. On the other hand, global expression analyses of copt2-1 mutants versus wild type Arabidopsis plants indicate that low phosphate responses are increased in copt2-1 plants. In this sense, COPT2 function under Fe deficiency counteracts low phosphate responses. These results open up new biotechnological approaches to fight iron deficiency in crops.
2013-06-05 | GSE42642 | GEO
Project description:Photosynthetic microorganisms encounter an erratic nutrient environment characterized by periods of iron limitation and sufficiency. Surviving in such an environment requires mechanisms for handling these transitions. Our study identified a regulatory system involved in the process of recovery from iron limitation in cyanobacteria. We set out to study the role of bacterioferritin co-migratory proteins during transitions in iron bioavailability in the cyanobacterium Synechocystis sp. PCC 6803 using knockout strains coupled with physiological and biochemical measurements. One of the mutants displayed slow recovery from iron limitation. However, we discovered that the cause of the phenotype was not the intended knockout but rather the serendipitous selection of a mutation in an unrelated locus, slr1658. Bioinformatics analysis suggested similarities to two-component systems and a possible regulatory role. Transcriptomic analysis of the recovery from iron limitation showed that the slr1658 mutation had an extensive effect on the expression of genes encoding regulatory proteins, proteins involved in the remodeling and degradation of the photosynthetic apparatus and proteins modulating electron transport. Most significantly, the transcript of the cyanobacterial homolog of the cyclic electron transport protein PGR5 was upregulated 1000-fold in slr1658 disruption mutants. pgr5 transcript in the slr1658 retained these high levels under a range of stress and recovery conditions. The results suggest that slr1658 is part of a regulatory operon that is most probably involved in regulating alternative electron flow. Disruption of its function has deleterious results under oxidative stress promoting conditions.
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2020-03-09 | PXD015623 | Pride
Project description:Aquatic microorganisms are typically identified as either oligotrophic or copiotrophic, representing trophic strategies adapted to low or high nutrient concentrations, respectively. Here, we sought to take steps towards identifying these and additional adaptations to nutrient availability with a quantitative analysis of microbial resource use in mixed communities. We incubated an estuarine microbial community with stable isotope labeled amino acids (AAs) at concentrations spanning three orders of magnitude, followed by taxon-specific quantitation of isotopic incorporation using NanoSIMS analysis of high-density microarrays. The resulting data revealed that trophic response to AA availability falls along a continuum between copiotrophy and oligotrophy, and high and low activity. To illustrate strategies along this continuum more simply, we statistically categorized microbial taxa among three trophic types, based on their incorporation responses to increasing resource concentration. The data indicated that taxa with copiotrophic-like resource use were not necessarily the most active, and taxa with oligotrophic-like resource use were not always the least active. Two of the trophic strategies were not randomly distributed throughout a 16S rDNA phylogeny, suggesting they are under selective pressure in this ecosystem and that a link exists between evolutionary relatedness and substrate affinity. The diversity of strategies to adapt to differences in resource availability highlights the need to expand our understanding of microbial interactions with organic matter in order to better predict microbial responses to a changing environment. manuscript accepted by PLoS ONE 4 datasets: 1) fluorescence data for 3 treatments combined, 2) isotopic data for treatment = LOW, 3) isotopic data for treatment = MEDIUM, 4) isotopic data for treatment = HIGH
2014-03-26 | E-GEOD-56119 | biostudies-arrayexpress