Project description:Microarrays allow us to monitor the change in transcription of every gene in the genome in response to a change in cellular state. We use cDNA microarrays to measure the response of E. coli to 13 different antibiotics and 3 synergistic combinations. Hierarchichal clustering reveals 4 distinct classes of antibiotics distinguished by their modes of action, and allows us to predict the mechanism for promethazine, a drug whose mode of action has not previously been established. The expression profiles of the synergistic combinations exhibit a complex relationship between the two component antibiotics, with similarity to one of the two drugs, as well as a surprising number of new gene responses exhibited by E. coli in response to neither drug alone. The subset of drugs which act in synergy with each other suggests that only very specific combination of mechanisms give rise to synergistic behavior. Keywords: stress response, antibiotic response, synergy
Project description:Microarrays allow us to monitor the change in transcription of every gene in the genome in response to a change in cellular state. We use cDNA microarrays to measure the response of E. coli to 13 different antibiotics and 3 synergistic combinations. Hierarchichal clustering reveals 4 distinct classes of antibiotics distinguished by their modes of action, and allows us to predict the mechanism for promethazine, a drug whose mode of action has not previously been established. The expression profiles of the synergistic combinations exhibit a complex relationship between the two component antibiotics, with similarity to one of the two drugs, as well as a surprising number of new gene responses exhibited by E. coli in response to neither drug alone. The subset of drugs which act in synergy with each other suggests that only very specific combination of mechanisms give rise to synergistic behavior. Keywords: stress response, antibiotic response, synergy Each array has two spots to monitor the response of E coli to one of the treatments, and two control spots (ie no treatment). These are background corrected, normalized for total intensity, and then the average volume difference is calculated. Each treatment has two replicates, and the result is average across these two replicates. Our final processed data is a relative volume difference, in which the aforementioned volume difference is divided by an estimate of the error in the data. This relative volume difference gives us greater confidence that the changes we see are real. Any relative volume difference >= 2 or <= -2 (ie where the absolute volume difference is twice as much as the estimated error or more) is considered to be significant. Total of 68 hybridizations: 17 samples X 2 replicates for each sample X (1 sample + 1 control for each replicate)
Project description:This experiment was conducted to understand the gene functions of Escherichia coli in different concentrations of induction of Isopropyl β-D-1-thiogalactopyranoside (IPTG). Experiments were performed with no induction, or with induction using 0.2mM or 1 mM of IPTG.
Project description:The purpose of this study is to determine whether the presence of pathogenic Escherichia coli in colon is associated with psychiatric disorders.
Project description:The intention of this study is to analyse the effect of antibiotics on the gene expression of Escherichia coli. Shaking-flask cultivations of Escherichia coli K12GFP-UTL2 were carried out with a medium containing nalidixic acid. Cultures with antibiotic-free medium, which were run in an identical way, served as reference. Samples were taken at different times during the cultivations, the RNA was isolated and hybridised on whole genome yeast microarrays. Keywords: Influence of toxins on gene expression in E. coli
Project description:Gram-negative bacteria possess stress responses to maintain the integrity of the cell envelope. Stress sensors monitor outer membrane permeability, envelope protein folding, and energization of the inner membrane. The systems used by Gram-negative bacteria to sense and combat stress resulting from disruption of the peptidoglycan layer are not well characterized. The peptidoglycan layer is a single molecule that completely surrounds the cell and ensures its structural integrity. During cell growth new peptidoglcyan subunits are incorporated into the peptidoglycan layer by a series of enzymes called the penicillin-binding proteins (PBPs). To explore how Gram-negative bacteria respond to peptidoglycan stress, global gene expression analysis was used to identify Escherichia coli stress responses activated following inhibition of specific PBPs by the β-lactam antibiotics mecillinam and cefsulodin. Inhibition of PBPs with different roles in peptidoglycan synthesis has different consequences for cell morphology and viability, suggesting that not all perturbations to the peptidoglycan layer generate equivalent stresses. We demonstrate that inhibition of different PBPs resulted in both shared and unique stress responses. The regulation of capsular synthesis (Rcs) phosphorelay was activated by inhibition of all of the PBPs tested. Furthermore, we show that activation of the Rcs phosphorelay increased survival in the presence of these antibiotics, independently of capsule synthesis. Both activation of the phosphorelay and survival required signal transduction via the outer membrane lipoprotein RcsF and the response regulator RcsB. We propose that the Rcs pathway responds to peptidoglycan damage and contributes to the intrinsic resistance of E. coli to β-lactam antibiotics. We used microarrays to identify changes in gene expression resulting from treatment of Escherichia coli with the β-lactam antibiotics cefsulodin, mecillinam, or the combination. This SuperSeries is composed of the following subset Series:; GSE10158: Expression of Escherichia coli treated with cefsulodin and mecillinam, alone and in combination; GSE10159: Expression of Escherichia coli treated with cefsulodin and mecillinam, alone at the minimum inhibitory concentration Experiment Overall Design: Refer to individual Series
Project description:Despite the characterization of many aetiologic genetic changes. The specific causative factors in the development of sporadic colorectal cancer remain unclear. This study was performed to detect the possible role of Enteropathogenic Escherichia coli (EPEC) in developing colorectal carcinoma.
Project description:The intention of this study is to analyse the effect of antibiotics on the gene expression of Escherichia coli. Shaking-flask cultivations of Escherichia coli K12GFP-UTL2 were carried out with a medium containing nalidixic acid. Cultures with antibiotic-free medium, which were run in an identical way, served as reference. Samples were taken at different times during the cultivations, the RNA was isolated and hybridised on whole genome yeast microarrays. Keywords: Influence of toxins on gene expression in E. coli A timeserial experiment of the influence of nalidixic acid on the gene expression in Escherichia coli was performed. Effects of the growth curve were eliminated by bionformatic methods.
Project description:To investigate and compare transcriptomic changes of Escherichia coli K-12 MG1655, the bacterium was exposed to nine antibiotics (tetracycline, mitomycin C ,imipenem, ceftazidime, kanamycin, ciprofloxacin, polymyxin E, erythromycin, and chloramphenicol) , and RNA-Seq was performed to determine comparative transcriptomic changes.