Unknown,Transcriptomics,Genomics,Proteomics

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Expression Profile of R. capsulatus under heat and cold stress

ABSTRACT: The effects of temperature stress on transcriptome of purple non sulfur bacterium R. capsulatus were investigated by comparing expression profiles under optimum hydrogen production condition (30M-BM-0C), heat (42M-BM-0C) and cold (4M-BM-0C) stress conditions. Bacteria were grown anaerobically under continuous illumination (200 W/m2) in 150 ml volume photobioreactors at 30M-BM-0C for 48 hours. Then cold stress (4M-BM-0C) and heat stress (42M-BM-0C) were applied in parallel. For microarray analysis, RNA samples from 1.5x109 cells were collected after 2 hours and 6 hours of stress applications. A microarray chip for Rhodobacter capsulatus was not commercially available. For that reason, a GeneChipM-BM-. array was custom designed and manufactured by Affymetrix, Santa Clara, California. The nucleotide sequence of the bacterium is available in GenBank with the accession numbers CP001312 for the chromosome and CP001313 for the plasmid pRCB133. The feature size of the antisense DNA array was 11 micron and the format was 100-3660. A total of 4,052 probe sets for open reading frames (ORFs) and 200 intergenic sequences with longer than 300bp were placed on the microarray. The cDNA synthesis, labeling, and hybridization protocols were performed according to the Affymetrix Expression Analysis Technical Manual given for prokaryotic samples

ORGANISM(S): Rhodobacter capsulatus

SUBMITTER: Muazzez Gurgan

PROVIDER: E-GEOD-53477 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Background Regulation of transcription is essential for any organism and Rhizobium etli (a multi-replicon, nitrogen-fixing symbiotic bacterium) is no exception. This bacterium is commonly found in the rhizosphere (free-living) or inside of root-nodules of the common bean (Phaseolus vulgaris) in a symbiotic relationship. Abiotic stresses, such as high soil temperatures and salinity, compromise the genetic stability of R. etli and therefore its symbiotic interaction with P. vulgaris. However, it is still unclear which genes are up- or down-regulated to cope with these stress conditions. The aim of this study was to identify the genes and non-coding RNAs (ncRNAs) that are differentially expressed under heat and saline shock, as well as the promoter regions of the up-regulated loci. Results Analysing the heat and saline shock responses of R. etli CE3 through RNA-Seq, we identified 756 and 392 differentially expressed genes, respectively, and 106 were up-regulated under both conditions. Notably, the set of genes over-expressed under either condition was preferentially encoded on plasmids, although this observation was more significant for the heat shock response. In contrast, during either saline shock or heat shock, the down-regulated genes were principally chromosomally encoded. Our functional analysis shows that genes encoding chaperone proteins were up-regulated during the heat shock response, whereas genes involved in the metabolism of compatible solutes were up-regulated following saline shock. Furthermore, we identified thirteen and nine ncRNAs that were differentially expressed under heat and saline shock, respectively, as well as eleven ncRNAs that had not been previously identified. Finally, using an in silico analysis, we studied the promoter motifs in all of the non-coding regions associated with the genes and ncRNAs up-regulated under both conditions. Conclusions Our data suggest that the replicon contribution is different for different stress responses and that the heat shock response is more complex than the saline shock response. In general, this work exemplifies how strategies that not only consider differentially regulated genes but also regulatory elements of the stress response provide a more comprehensive view of bacterial gene regulation. mRNA of nine independent cultures of wild type strain Rhizobium etli CE3 were sequenced using Illumina GAIIx. Our parameters were: all cultures were taken from exponential phase, at 30M-BM-0C for 30min in control condition; 42M-BM-0C for 30min for the culture subject to heat -shock, and 30min at 30M-BM-0C in supplementary PY medium with 80mM NaCl for the saline shock condition.

Project description:Stress acclimation is an effective mechanism that plants acquired for adaption to dynamic environmental conditions. After undergoing cold acclimation, plants become more tolerant to cold stress. In order to understand the mechanism of cold acclimation, we performed a systematic, comprehensive study of cold response and acclimation in Cassava (Manihot esculenta), a staple crop and major food source in the tropical regions of the world. We profiled mRNA genes and small-RNA species, using next generation sequencing, and performed an integrative analysis of the transcriptome and microRNAome of Cassava across the normal condition, a moderate cold stress at 14M-BM-0C, a harsh stress at 4M-BM-0C after cold acclimation at 14M-BM-0C, and a cold shock from 24M-BM-0C to 4M-BM-0C. Two results from the analysis were striking. First, the moderate stress and cold shock, despite a difference of 10M-BM-0C between the two, triggered comparable degrees of perturbation to the transcriptome; in contrary, further harsh stress after cold acclimation resulted in a much smaller degree of transcriptome variation. Second and more importantly, about two thirds of the up- or down-regulated genes after moderate stress reversed their expression to down- or up-regulation, respectively, under harsh stress after cold acclimation, resulting in a genome-wide rewiring of regulatory networks. MicroRNAs, which are key post-transcriptional gene regulators, were major players in this massive rewiring of genetic circuitry. Further, a function enrichment analysis of the perturbed genes revealed that cold acclimation helped the plant to develop immunity to further harsh stress by exclusively inducing genes with functions of nutrient reservoir; in contrast, many genes with functions of viral reproduction were induced by cold shock. Our study revealed, for the first time, the molecular basis of stress acclimation in plants, and shed lights on the role of microRNA gene regulation in cold response and acclimation in Euphorbia. Three organs/tissues (folded leaf, fully expanded leaf and roots) of Cassava cultivar SC124 harvested at 6h, 24h and 5d for three cold treatments of CA, CCA and CS, for gene expression profiling at the stages of initial response, secondary response, and functional adaption to cold stresses. Total RNA of each sample was isolated individually, and then pooled with an equal amount from each sample into one for profiling. As a result, four mRNA libraries and four small-RNA libraries, corresponding to the conditions of CA, CCA, CS and NC, were constructed.

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Expression Profile of R. capsulatus under heat and cold stress

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