E. coli O157:H7 phage type 21/28 & 32 CGH analysis
Ontology highlight
ABSTRACT:
ORGANISM(S): Escherichia coli O157:H7 str. Sakai
SUBMITTER: Jai Tree
PROVIDER: E-GEOD-28838 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
Similar Datasets
Project description:Six isolates of PT21/28 and six of PT32 were analysed by CGH using UBECarray3 microarrays (containing probes for E. coli K-12 str. MG1655 and O157:H7 str. EDL933 and Sakai) to define genotypic differences between phage types. gDNA from E.coli O157 str. Sakai was hybridised to all arrays to provide a universal control channel on all arrays.
2012-04-21 | GSE28838 | GEO
Project description:Escherichia coli O157 presents a number of specific problems in terms of food safety and public health. It has been found that E. coli O157 is more resistant to a number of the stresses encountered during food production such as heat, pH and osmotic shock. This greater resistance is thought to contribute to the low infectious dose of E. coli O157 (<100 organisms). Moreover, E. coli O157 is associated with debilitating conditions such as haemorrhagic colitis and haemoytic uraemic syndrome, particularly in children and the elderly. We have been studying the stress responses of E. coli O157:H7 (Sakai) and comparing with a commensal strain of E. coli K-12, MG1655. We found that E. coli O157 (Sakai) is more resistant to heat stress than MG1655. A microarray study of these strains subjected to sub-lethal heat-stress at 45M-BM-0C was carried out. In E. coli O157 (Sakai), 380 genes responded significantly to the treatment compared to 410 genes in MG1655. Overnight cultures of E. coli O157 (Sakai) and E. coli K-12 MG1655 were grown in Neidhardt's EZ Rich Defined Medium and diluted 1:100 in 50 ml fresh medium in 125 ml Ehrlenmeyer flasks. The cultures were shaken at 37M-BM-0C until the optical density (OD600) reached 0.4. Each culture was divided into 2 equal parts in identical flasks. One flask flask was transferred to a shaking water bath and incubated at 45M-BM-0C for 10 min; the other flask was incubated at 37M-BM-0C for 10 min. After incubation, the cultures were transferred to 50 mL centrifuge tubes and treated with RNAprotectM-bM-^DM-" to stabilise the mRNA. The experiment was performed 3 times on different days. Six custom-made microarray slides were used in this study; each slide was hybridised with labelled cDNA made from untreated and heated E. coli O157 (Sakai) or MG1655.
2018-03-20 | E-MTAB-5912 | biostudies-arrayexpress
Project description:Transcript abundance in Escherichia coli O157:H7 was determined in the presence or absence of pulsed expression of the small RNA, AsxR. AsxR was cloned under the control the arabinose inducible promoter Para. Escherichia coli O157:H7 str. TUV93-0 with pAsxR or empty vector was cultured in MEM-HEPES media to an OD600 of 0.8 and 0.2% arabinose added. 10min after addition of arabinose 10ml of cells were harvested and and pellets resuspended in 1ml of Trizol and total RNA isolated. RNAs were labelled using the SuperScript Plus indirect cDNA labelling System. Triplicate control RNAs were pooled and hybridised to seperate AsxR test RNAs on three microarays. Arrays were hybridised using the Maui hybridisation platform and Scann using and Axon Autoloader Scanner. GenePix software was used to analyse images and GPR files were analysed using Genespring 7.3.1.
2014-05-22 | E-GEOD-46113 | biostudies-arrayexpress
Project description:We compared the transcriptional profiles of 12 E. coli O157:H7 isolates grown to stationary phase in LB broth. These isolates possess the same two enzyme PFGE profile and are related temporally or geographically to the above outbreak. These E. coli O157:H7 isolates included three clinical isolates, five isolates from separate bags of spinach, and single isolates from pasture soil, river water, cow feces, and a feral pig. Twelve condition experiment, 12 E. coli O157:H7 isolates. Two biological replicates for isolates RM6067, RM6069, RM6101, RM6102, RM6103, RM6149, RM6655, RM6658, RM9992, RM9997, RM9998 and RM10002 independently grown to stationary phase in LB at 37°C and harvested. One replicate per array. A type 2 gene expression experimental design was used, with fluorescently labeled genomic DNA as a reference channel in each experiment as described by Lucchini, S., et al. 2005. Infect Immun 73:88-102.
2011-11-01 | E-GEOD-33131 | biostudies-arrayexpress
Project description:Differences in gene expression between a mutant D. vulgaris strain missing the PerR transcriptional regulator gene and the wild-type strain. For each condition (PerR_cDNA_vrs_gDNA, wild-type_cDNA_vrs_gDNA) 2 unique biological samples were hybridized to 4 arrays that each contained duplicate spots. Genomic DNA was used as universal reference. Log2 PerR mutant versus wild-type gene expresson with growth on WP-lactate. SUPPLEMENTARY FILES: * Log2 gene expression ratios of PerR mutant/wild-type (PerR/gDNA/ wildtype/gDNA) and q-values. * Wild type raw data. * PerR mutant raw data.
2011-01-05 | E-GEOD-26448 | biostudies-arrayexpress
Project description:Hybridisation of reference strains to the VirEp Staphylococcus aureus microarray, and characterisation of different S. aureus isolates from different locations and associated with different diseases.
2008-05-01 | E-MEXP-1548 | biostudies-arrayexpress
Project description:Integrating laterally acquired virulence genes into the backbone regulatory network is important for the pathogenesis of Escherichia coli O157:H7, which has captured many virulence genes through horizontal transfer during evolution. GadE is an essential transcriptional activator of glutamate decarboxylase (GAD) system, the most efficient acid resistance mechanism in E. coli. The full contribution of GadE to the acid resistance and virulence of pathogenic E. coli O157:H7 remains largely unknown. We inactivated gadE in E. coli O157:H7 Sakai and compared global transcription profiles with that of wild type in exponential and stationary phases of growth using microarrays containing 6088 ORFs from three E. coli genomes. gadE inactivation significantly altered the expression of 60 genes independent of growth phase and 122 genes in a growth phase-dependent manner. Inactivation of gadE markedly down-regulated the expression of gadA, gadB, gadC and many acid fitness island genes in a growth phase-dependent manner. Nineteen genes encoded on the locus of enterocyte effacement (LEE), including ler, showed a significant increase in expression upon gadE inactivation. Altogether, our data indicate that GadE is critical for acid resistance of E. coli O157:H7 and plays an important role in virulence by down-regulating expression of LEE. The results are based on O157:H7 Sakai wild type and gadE mutant exponential and stationary phase cultures grown in MOPS minimal medium. Differences in transcript levels were determined using a mixed model ANOVA in R/MAANOVA which tested for significant differences due to growth phase (exponential or stationary), strain (wild type or mutant) and the interaction of these two factors using the following linear model: array+dye+sample (biological replicate)+ phase+strain+phase*strain. We incorporated the dye-swaps among the biological replicates.
2010-05-18 | E-GEOD-13132 | biostudies-arrayexpress
Project description:Two outbreak strains of E. coli O157:H7 differ phylogenetically, in gene content, and in epidemiological characteristics. The working hypothesis in this experiment was that these strains will also differ in the transcription of shared virulence genes. Indeed, following a 30 minute exposure to epithelial cells, strain TW14359 overexpressed major and ancillary virulence genes, relative to strain Sakai. E. coli O157:H7 strains were physiologically normalized by growth to stationary phase, twice, in MOPS minimal media. Cultures were then transferred to DMEM media for adaptation. After 3 h of growth in DMEM, O157:H7 cultures were used to infect monolayers of MAC-T epithelial cells. 30 min following incubation, aliquots of suspended, non-adherent bacteria were used for RNA extraction. Five biological replications of the experiment were performed with each strain and, together with dye-swaps, 10 array hybridizations were carried out. Array data were fitted to a mixed model ANOVA using the following linear model: array+dye+sample (biological replicate)+strain+error.
2010-05-05 | E-GEOD-17389 | biostudies-arrayexpress
Project description:Escherichia coli O157 presents a number of specific problems in terms of food safety and public health. It has been found that E. coli O157 is more resistant to a number of the stresses encountered during food production such as heat, pH and osmotic shock. This greater resistance is thought to contribute to the low infectious dose of E. coli O157 (<100 organisms). Moreover, E. coli O157 is associated with debilitating conditions such as haemorrhagic colitis and haemoytic uraemic syndrome, particularly in children and the elderly. We have been studying the stress responses of E. coli O157:H7 (Sakai) and comparing with a commensal strain of E. coli K-12, MG1655. We found that E. coli O157 (Sakai) is more sensitive to oxidative stress than MG1655. A microarray study of these strains treated with sub-lethal concentrations (0.5mg/ml) of menadione revealed big differences in their responses. In E. coli O157 (Sakai), 540 genes responded significantly to the treatment compared to 121 genes in MG1655. One surprising finding from the microarray data was the observation that many iron-transport genes were up-regulated in E. coli O157 (Sakai) whereas relatively few were induced in MG1655 despite the fact that the bacteria were grown in a medium containing ample iron. We speculated that the induction of iron transport genes in an iron-rich medium might have contributed to the enhanced killing of E. coli O157 (Sakai) through triggering of a Fenton reaction. We speculated that the difference in sensitivity to oxidative stress might be due to differences in the intracellular iron content of E. coli O157 and MG1655. We found that E. coli O157 contains ~50% more iron than MG1655 and believe that during oxidative stress, this iron is released by damaged proteins. The greater levels of free iron in E. coli O157 will trigger a greater Fenton reaction that can damage the ferric uptake regulator (Fur), resulting in unregulated iron transport. In MG1655, the lower iron content results in a smaller Fenton reaction, enabling the cellular protection systems to limit damage and protect Fur.
2015-02-22 | GSE36130 | GEO
Project description:There is increasing evidence to support a role for sigma factor 54 (RpoN) in the regulation of stress resistance factors and protein secretion systems important to bacterial transmission and pathogenesis. In enterohemorrhagic E. coli O157:H7, acid resistance and type III secretion are essential determinants of gastric passage and colonization. This study thus described the transcriptome of an rpoN null strain of E. coli O157:H7 (EcJR-8) to determine the influence of RpoN on virulence and stress resistance gene regulation, and further explored its contribution to glutamate-dependent acid resistance (GDAR). Inactivation of rpoN resulted in the growth phase-dependent, differential expression of 104 genes. This included type III secretion structural and regulatory genes encoded on the locus of enterocyte effacement (LEE), as well as GDAR genes gadA, gadBC and gadE. Upregulation of gad transcript levels in EcJR-8 during logarithmic growth correlated with increased GDAR and survival in a model stomach. Acid susceptibility was reconstituted in EcJR-8 complemented in trans with wild-type rpoN. Acid resistance in EcJR-8 was dependent on exogenous glutamate, gadE and rpoS, but was independent of hns. Results also suggest that GDAR may be controlled by RpoN at multiple regulatory levels. This study supports the hypothesis that RpoN is an important regulator of virulence and stress resistance factors in E. coli O157:H7, and is the first to examine the mechanism by which it represses GDAR. Hybridizations measured transcriptional differences between an rpoN null and wild-type (WT) strain of E. coli O157:H7 Sakai at logarithmic and transition phase. Image files (TIFF) of hybridized microarray slides were generated using an Axon 4000B scanner (Molecular Devices), and analyzed using GenePix Pro software (Molecular Devices, ver. 6.0). The resulting microarray intensity data was log2-transformed, and normalized using the LOWESS algorithm in MAANOVA ver. 0.98-8 (R ver. 2.2.1).
2009-08-08 | E-GEOD-17467 | biostudies-arrayexpress