Transcription profiling of Escherichia coli over-expressing genes involved in signaling systems that detect and respond to alterations of the bacterial envelope
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ABSTRACT: The Bae, Cpx, Psp, Rcs and ?E pathways constitute the Escherichia coli signaling systems that detect and respond to alterations of the bacterial envelope. Contributions of these systems to stress response have previously been examined individually; however, the possible interconnections between these pathways are unknown. Here we investigate the dynamics between the five stress response pathways by i) determining the specificities of each system with respect to signal inducing conditions, and ii) monitoring global transcriptional changes in response to transient over-expression of each of the effectors.
Project description:Human H1299 lung cancer cells or clones engineered for tetracycline-inducible expression of wild type IRP2, or the deletion mutant IRP2?73 (lacking a specific insert of 73 amino acids), were injected subcutaneously into nude mice. The induction of IRP2 profoundly stimulated the growth of tumor xenografts, and this response was blunted by addition of tetracycline in the drinking water of the animals, to turnoff the IRP2 transgene. Interestingly, IRP2?73 failed to promote tumor growth above control levels. As expected, xenografts expressing the IRP2 transgene exhibited high levels of transferrin receptor 1 (TfR1); however, the expression of other known IRP targets was not affected. Moreover, these xenografts manifested increased c-MYC levels and ERK1/2 phosphorylation. A microarray analysis identified distinct gene expression patterns between control and tumors containing IRP2 or IRP1 transgenes. By contrast, gene expression profiles of control and IRP2?73-related tumors were more similar, consistently with their growth phenotype. Collectively, these data demonstrate an apparent pro-oncogenic activity of IRP2 that depends on its specific 73 amino acids insert, and provide further evidence for a link between IRPs and cancer biology.
Project description:The influence of Sro9 on steady-state levels of a specific set of mRNAs in yeast was investigated. This was assessed using whole genome expression profiling of delta Sro9 in comparison to wild-type cells.
Project description:We found that the antibiotic colistin acts synergistically with antifungals of the echinocandin class (e.g. aminocandin) on C. albicans cells. In order to elucidate the mode of action of colistin in fungi we performed microarray analysis of samples treated with only aminocandin (0.00125µg/ml) or treated with aminocandin (0.00125µg/ml) and colistin (5µg/ml). We compared: (A). untreated cells to cells treated with aminocandin only; (B). cells treated with aminocandin to cells treated with aminocandin and colistin (which is the focus of this experiment). By comparing those datasets it should be possible to identify genes differentially expressed in response to aminocandin and in response to both drugs. And subsequently to be able to interpret where in the cell colistin acts. (See related experiment in ArrayExpress: E-MEXP-3437 for comparison between untreated cells vs cells treated with aminocandin only.)
Project description:Genome-wide transcriptional profiling on microarray was performed for strain MC4100 in comparison to its otherwise isogenic ycgE::cat derivative. Strains were grown in LB at 28°C and cells were harvested at an OD (578nm) of 4.0.
Project description:Wildtype and ycgF::kan cells were grown in LB medium at 37°C to an OD(578 nm) of 0,7. Then the cultures were shifted to 16°C and blue-light irradiated for 3 hours.
Project description:Analysis used RNA extracted from Escherichia coli exposed or not to cobalt. Experiments were done with E. coli MC4100 cultures exposed to CoCl2 (250 µM) in mid-exponential phase during 30 min. Comparisons were made across multiple arrays, using E. coli MC4100 DNA microarrays spotted with PCR products at the Gif/Orsay DNA microarrays Platform.
Project description:Several members of the Bacillus cereus group of bacteria carry lysogenic phages of the family Tectiviridae. The Bacilus cereus reference strain (ATCC 14579) harbor a linear plasmid (pBClin15) that is highly similar to the genomes of the Tectiviruses. Production of active phages has however never been reported for pBClin15 and the role of pBClin15 in B. cereus physiology has been enigmatic. We have for the first time demonstrated an effect of pBClin15 on the physiology of B. cereus ATCC 14579 whereby the wild type is more sensitive to DNA damaging antibiotics compared to a pBClin15 cured strain. The microarray experiments in this study were designed to highlight transcriptional differences between the B. cereus ATCC 14579 wild type and a plasmid cured variant that potentially could explain the impact of pBClin15 on the B. cereus physiology. Microarray experiments were carried out under non-stressful conditions (growth in logarithmic phase in LB medium) under which there were no phenotypic difference between the wild type and pBClin15 cured strain as well as under stressful conditions under which there were phenotypic differences between the two strain (growth in LB medium supplemented with 0.5M-5g norfloxacin per ml).