Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

Transcription profiling of rat colon from animals fed cellulose vs FOS diets and infected with Salmonella

ABSTRACT: To increase our knowledge of the effects of Fructo oligosaccharides (FOS) on Salmonella infection in fats, a controlle rat infection study was performed. Two groups of 12 rats were adapted for 14 days to a cellulose diet and one group of 12 rats to a FOS diet. One cellulose-fed group and the FOS-fed group were infected with Salmonella. Two days post infection mRNA was collected from the mucosa of the colon and changes in gene expression were assessed using an Agilent rat whole genome microarray (G4131A Agilent Technologies). Results indicate that Salmonella affects colonic mucosal gene expression, which is further enhanded by dietary FOS. Experiment Overall Design: In the present study, large-scale gene expression analysis was performed to reveal whether Salmonella induced changes of colonic mucosal gene expression in rats. Furthermore, we compared the colonic gene expression changes of infected rats fed a diet supplemented with Fructo oligosaccharides (FOS) or cellulose as control. Two groups of Wistar rats (n=12) were adapted for 14 days to a cellulose diet and one group (n=12) to a FOS diet. One cellulose-fed group and the FOS-fed group were infected with Salmonella. RNA was isolated from colonic mucosal scrapings. mRNA samples of 12 rats per group were pooled. Each group-sample was hybridised in duplicate on Agilent rat whole genome microarrays containing 44290 60-mer spots.

ORGANISM(S): Rattus norvegicus

SUBMITTER: Wendy Rodenburg

PROVIDER: E-GEOD-7472 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

Salmonella induces prominent gene expression in the rat colon.

Rodenburg Wendy W Keijer Jaap J Kramer Evelien E Roosing Susanne S Vink Carolien C Katan Martijn B MB van der Meer Roelof R Bovee-Oudenhoven Ingeborg M J IM

BMC microbiology 20070912

<h4>Background</h4>Salmonella enteritidis is suggested to translocate in the small intestine. In vivo it induces gene expression changes in the ileal mucosa and Peyer's patches. Stimulation of Salmonella translocation by dietary prebiotics fermented in colon suggests involvement of the colon as well. However, effects of Salmonella on colonic gene expression in vivo are largely unknown. We aimed to characterize time dependent Salmonella-induced changes of colonic mucosal gene expression in rats u ...[more]

PMID: 17850650

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Project description:Background: Xylella fastidiosa, a Gram-negative fastidious bacterium, grows exclusively in the xylem of several plants, causing diseases such as citrus variegated chlorosis. As the xylem sap contains low concentrations of amino acids and other compounds, X. fastidiosa needs to cope with nitrogen limitation in its natural habitat. Results: In this work, we performed a whole-genome microarray analysis of the X. fastidiosa nitrogen starvation response. A time-course experiment (2, 8 and 12 hours) revealed many differentially expressed genes under nitrogen starvation, such as genes related to transport, nitrogen assimilation, amino acid biosynthesis, transcriptional regulation, and many genes encoding hypothetical proteins. In addition, a decrease in the expression levels of many genes involved in carbon metabolism and energy generation pathways was also observed. Comparison of gene expression profiles between the wild type strain and the rpoN null mutant allowed the identification of genes induced by nitrogen starvation in a ?54-dependent manner. A more complete picture of the ?54 regulon was achieved by combining the transcriptome data with an in silico search for potential ?54-dependent promoters, using a position weight matrix approach. One of these ?54-predicted binding sites, located upstream of the glnA gene (encoding a glutamine synthetase), was validated by primer extension assays, confirming that this gene has a ?54-dependent promoter and contains a predicted NtrC binding site. Conclusions: Together, these results show that nitrogen starvation causes intense changes in the X. fastidiosa transcriptome and some of these differentially expressed genes belong to the ?54 regulon. For time-course studies, cells cultivated at late-exponential phase in PWG medium were used to inoculate a culture in 100 ml XDM2 medium to an optical density at 600 nm (OD600 nm) of 0.1. Cells were grown during 12 days in the XDM2 medium (mid-log phase) and harvested by centrifugation. Then, the culture was divided into two 6 portions and cells were washed with XDM2 medium (zero time) or XDM2 medium lacking all nitrogen sources (XDM0), respectively. The cultivation was continued for 2h, 8h and 12h in XDM0 to establish nitrogen starvation conditions. For each time point, cells in a 25-ml culture were collected by centrifugation and rapidly frozen in dry ice, until RNA isolation. Three RNA samples isolated from independently grown cultures of the cells at each starvation period (2h, 8h and 12h) were examined, and each preparation was subjected to microarray analysis. As the genes were spotted at least in duplicate, we obtained six replicates for each gene from three independent data sets per gene per starvation period. Comparison of gene expression profiles between the wild type strain and the rpoN null mutant allowed the identification of genes induced by nitrogen starvation in a ?54-dependent manner. To determine the effect of rpoN inactivation on gene expression after nitrogen starvation, the transcriptomes of the wild type and the rpoN strains were compared using DNA microarrays, with both strains grown on XDM2 medium and submitted to nitrogen starvation (XDM0) during 2 hours. Three RNA samples isolated from independently grown cultures of the cells were examined. Due to the platform design, each microarray slide was divided into "LEFT" and "RIGHT", allowing the probing of two technical replicates per slide.

Project description:Xylella fastidiosa is the etiologic agent of a wide range of plant diseases including citrus variegated chlorosis (CVC), a major threat to the Brazilian citrus industry. Genome sequences of several strains of this phytopathogen are accessible, enabling large-scale functional studies. Transcript levels in different iron availabilities were assessed with DNA microarrays representing 2608 (91.6%) coding sequences (CDS) of X. fastidiosa CVC strain 9a5c. When treated with the iron chelator 2,2-dipyridyl, 193 CDS were considered as up-regulated and 216 as down-regulated. In the presence of 100uM of ferric pyrophosphate, 218 and 256 CDS were considered as up- and down-regulated, respectively. Differential expression for a subset of 44 CDS was further evaluated by reverse transcription - quantitative PCR that showed a Pearson correlation of 0.77 with array results. The CDS differentially expressed upon the iron concentration shift participate in diverse cellular functions. Many CDS involved with regulatory functions, pathogenicity and cell structure, were modulated in both conditions tested suggesting that major changes in cell architecture and metabolism occur when X. fastidiosa cells are exposed to extreme variations in iron concentration. Interestingly, the modulated CDS include those related to colicin V-like bacteriocin synthesis and secretion and to pili/fimbriae functions. We also investigated the contribution of the ferric uptake regulator Fur to the iron regulon of X. fastidiosa. The promoter regions of strain 9a5c genome were screened for putative Fur boxes and candidates were analyzed by electrophoretic mobility shift assays. Taken together, our data support the hypothesis that Fur is not solely responsible for the modulation of the iron regulon of X. fastidiosa and present novel evidence for iron regulation of pathogenicity determinants. Keywords: stress response; response to iron-depleted condition Direct comparison between low iron content (200uM 2,2-dipyridyl) and control condition. Hybridizations are dye-swaped. There are 2 biological replicates (independent harvest) and 2 technical replicates of each array (L - left and R - right).

Project description:Xylella fastidiosa is the etiologic agent of a wide range of plant diseases including citrus variegated chlorosis (CVC), a major threat to the Brazilian citrus industry. Genome sequences of several strains of this phytopathogen are accessible, enabling large-scale functional studies. Transcript levels in different iron availabilities were assessed with DNA microarrays representing 2608 (91.6%) coding sequences (CDS) of X. fastidiosa CVC strain 9a5c. When treated with the iron chelator 2,2-dipyridyl, 193 CDS were considered as up-regulated and 216 as down-regulated. In the presence of 100uM of ferric pyrophosphate, 218 and 256 CDS were considered as up- and down-regulated, respectively. Differential expression for a subset of 44 CDS was further evaluated by reverse transcription - quantitative PCR that showed a Pearson correlation of 0.77 with array results. The CDS differentially expressed upon the iron concentration shift participate in diverse cellular functions. Many CDS involved with regulatory functions, pathogenicity and cell structure, were modulated in both conditions tested suggesting that major changes in cell architecture and metabolism occur when X. fastidiosa cells are exposed to extreme variations in iron concentration. Interestingly, the modulated CDS include those related to colicin V-like bacteriocin synthesis and secretion and to pili/fimbriae functions. We also investigated the contribution of the ferric uptake regulator Fur to the iron regulon of X. fastidiosa. The promoter regions of strain 9a5c genome were screened for putative Fur boxes and candidates were analyzed by electrophoretic mobility shift assays. Taken together, our data support the hypothesis that Fur is not solely responsible for the modulation of the iron regulon of X. fastidiosa and present novel evidence for iron regulation of pathogenicity determinants. Direct comparison between high iron content (100uM ferric pyrophosphate) and control condition. Hybridizations are dye-swaped. There are 2 biological replicates (independent harvest) and 2 technical replicates of each array (L - left and R - right).

Dataset Information

Transcription profiling of rat colon from animals fed cellulose vs FOS diets and infected with Salmonella

Publications

Salmonella induces prominent gene expression in the rat colon.

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