Project description:This project used transcriptomic analysis of the S-nitrosoglutathione (GSNO) response in E. coli, and associated regulatory mutants, to identified the molecular targets of and response to GSNO during aerobic growth in minimal media. Keywords: Comparative genomic response
Project description:Escherichia coli strain MG1655 was grown in a New Brunswick Scientific Bioflow III Biofermentor under continuous culture (chemostat) conditions. Cells were grown in defined media containing 54 mM glycerol as the sole and limiting source of energy and carbon. The working volume was 1 litre, and the dilution rate 0.2 h-1. For aerobic growth, the air-flow rate was 1 l/min, and the dissolved oxygen tension was maintained at 40% air saturation by measuring oxygen dissolved in the culture using a Broadley James D140 OxyProbe® electrode and automated adjustment of stirring rate. Cells were grown as above to steady-state, At steady-state, GSNO was added to the chemostat culture and to the nutrient feed at a final concentration of 200 uM unless otherwise stated. Samples were taken immediately prior to the addition of GSNO and after a period of 5 min exposure to GSNO for subsequent analysis using microarrays. Cells were harvested directly into RNA Protect (Qiagen) to stabilize RNA, and total RNA was purified using Qiagen’s RNeasy Mini kit as recommended by the suppliers. Equal quantities of RNA from control and GSNO-supplemented cultures were labelled using nucleotide analogues of dCTP containing either Cy3 or Cy5 fluorescent dyes. The average signal intensity and local background correction were obtained using a commercially available software package from Biodiscovery, Inc (Imagene, version 4.0 and GeneSight, version 3.5). The mean values from each channel were log2 transformed and normalised using the Lowess method to remove intensity-dependent effects in the log2(ratios) values. The Cy3/Cy5 fluorescent ratios were calculated from the normalized values. Keywords: dose response
Project description:Escherichia coli strain MG1655 was grown in a New Brunswick Scientific Bioflow III Biofermentor under continuous culture (chemostat) conditions. Cells were grown in defined media containing 54 mM glycerol as the sole and limiting source of energy and carbon. The working volume was 1 litre, and the dilution rate 0.2 h-1. In order to establish anaerobic growth, nitrogen was sparged through the chemostat medium prior to inoculation and throughout the course of the experiment at a rate of 0.2 l/min. No dissolved oxygen was detectable using the OxyProbe. Sodium fumarate was added to anaerobic medium at a final concentration of 50 mM to act as a terminal electron acceptor. Cells were grown as above to steady-state, At steady-state, GSNO was added to the chemostat culture and to the nutrient feed at a final concentration of 200 uM unless otherwise stated. Samples were taken immediately prior to the addition of GSNO and after a period of 5 min exposure to GSNO for subsequent analysis using microarrays. Cells were harvested directly into RNA Protect (Qiagen) to stabilize RNA, and total RNA was purified using Qiagen’s RNeasy Mini kit as recommended by the suppliers. Equal quantities of RNA from control and GSNO-supplemented cultures were labelled using nucleotide analogues of dCTP containing either Cy3 or Cy5 fluorescent dyes. The average signal intensity and local background correction were obtained using a commercially available software package from Biodiscovery, Inc (Imagene, version 4.0 and GeneSight, version 3.5). The mean values from each channel were log2 transformed and normalised using the Lowess method to remove intensity-dependent effects in the log2(ratios) values. The Cy3/Cy5 fluorescent ratios were calculated from the normalized values. Keywords: dose response
Project description:The response to acidity is crucial for neutralophilic bacteria. Escherichia coli has a well characterized regulatory network to induce multiple defense mechanisms against excess of protons. Nevertheless, systemic studies of the transcriptional and translational reprogramming of E. coli to different acidic strengths have not yet been performed. Here, we used ribosome profiling and mRNA sequencing to determine the response of E. coli to pH 7.6, 5.8 and 4.4. Data were analyzed using the high-throughput HRIBO pipeline and previously undetected adaptations of E. coli to acid stress were found including up-regulation of glycerol catabolism and siderophore production, down-regulation of many membrane proteins and regulation by the transcriptional regulators YdeO, MhpR, IscR, and YdcI. Several examples of differential transcriptional and translational regulation of genes were identified as well as potential novel small open reading frames. These results expand the acid resistance network and provide new insights into the fine-tuned response of E. coli.
Project description:Escherichia coli strain MG1655 was grown in a New Brunswick Scientific Bioflow III Biofermentor under continuous culture (chemostat) conditions. Cells were grown in defined media containing 54 mM glycerol as the sole and limiting source of energy and carbon. The working volume was 1 litre, and the dilution rate 0.2 h-1. For aerobic growth, the air-flow rate was 1 l/min, and the dissolved oxygen tension was maintained at 40% air saturation by measuring oxygen dissolved in the culture using a Broadley James D140 OxyProbe® electrode and automated adjustment of stirring rate. Cells were grown as above to steady-state, At steady-state, GSNO was added to the chemostat culture and to the nutrient feed at a final concentration of 200 uM unless otherwise stated. Samples were taken immediately prior to the addition of GSNO and after a period of 5 min exposure to GSNO for subsequent analysis using microarrays. Cells were harvested directly into RNA Protect (Qiagen) to stabilize RNA, and total RNA was purified using Qiagenâs RNeasy Mini kit as recommended by the suppliers. Equal quantities of RNA from control and GSNO-supplemented cultures were labelled using nucleotide analogues of dCTP containing either Cy3 or Cy5 fluorescent dyes. The average signal intensity and local background correction were obtained using a commercially available software package from Biodiscovery, Inc (Imagene, version 4.0 and GeneSight, version 3.5). The mean values from each channel were log2 transformed and normalised using the Lowess method to remove intensity-dependent effects in the log2(ratios) values. The Cy3/Cy5 fluorescent ratios were calculated from the normalized values.
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:Transcriptional profiling of E. coli cells comparing control harboring the empty vector pRadGro (Ec-pR) with E. coli expressing the Deinococcus radiodurans response regulator DR1558 (Ec-1558) Expression of DR1558 conferred to multi-stress tolerance to E. coli.