Project description:Determine if cells in stationary-phase cultures respond to increased temperature. Yeast cells in stationary-phase cultures were exposed to temperature upshift (30C to 39C) with samples harvested every 30-minutes over 8 hours. All experimental samples are over an common reference. There are two replicates for each time point and six replicates of T0.
Project description:Background: As carbon sources are exhausted, Saccharomyces cerevisiae cells exhibit reduced metabolic activity and cultures enter stationary phase. We asked whether cells in stationary-phase cultures respond to additional stress at the level of transcript abundance. Results: Microarrays were used to quantify changes in transcript abundance in cells from stationary-phase cultures. In response to oxidative stress, more than 800 mRNAs increased within 1 minute. A significant number of these mRNAs encode proteins involved in stress responses. We tested whether mRNA increases were due to new transcription, rapid poly-adenylation of message (which would not be detected by microarrays), or potential release of mature mRNA sequestered in the cell but insoluble during RNA isolation. Examination of the response to oxidative stress in an RNA polymerase II mutant, rpb1-1 suggested new transcription was not required. Quantitative RT-PCR analysis of a subset of these transcripts further suggested that essentially all isolated transcripts were polyadenylated. In contrast, over 1000 transcripts increased after protease treatment of cell-free lysates from stationary-phase but not exponentially growing cultures. We also determined that oxidative stress and temperature upshift led to the release of different transcripts, suggesting that mRNA release is stress specific. Conclusions: A large number of mRNAs are sequestered in a protease-labile, rapidly releasable form in cells in stationary-phase cultures but not exponentially growing cultures. The differences between mRNAs released by protease treatment and those observed with oxidative stress and temperature upshift, suggest different stresses cause the release of different transcripts. We hypothesize that P-bodies are involved in this sequestration. Keywords: stress response
Project description:Analysis of gene expression of mid log phase cultures of Escherichia coli Ancestor strain, and high temperature evolved lines 42-1, 42-2 and 42-3. Keywords: other
Project description:Determine if yeast cell in stationary-phase cultures respond to oxidative stress Yeast cells in stationary-phase cultures were exposed to oxidative stress with samples harvested every 30-minutes over 8 hours. All experimental samples are over an common reference. There are two replicates for each time point and six replicates of T0.
Project description:Determine if yeast cells in stationary-phase cultures respond to oxidative stress Yeast cells in stationary-phase cultures were exposed to oxidative stress with samples harvested every 1-minute over 35 minutes, with a final time point at 60 minutes. All experimental samples are over an common reference. There are two replicates for each time point and six replicates of T0.
Project description:Listeria monocytogenes, the etiological agent of listeriosis, is capable of growth and survival at temperatures ranging from 2 to 48oC, reflecting the diverse environments and host species inhabited by this organism. L. monocytogenes expresses up to 29 proteins, termed internalins, whose structure indicates they make good candidates for facilitating bacterial-host cell interactions. Considering the ubiquitous nature of this organism, we speculated that environmental temperature might serve as an important biological signal in controlling their expression. We therefore employed a subgenomic microarray to investigate the expression profiles of 24 members of the internalin gene family identified in L. monocytogenes 10403S. Competitive hybridization was performed between RNA extracted from 10403S grown to early stationary phase at 37oC, and 10403S grown to early stationary phase at 16oC, 30oC and 42oC. The data reveal that internalin genes can be divided into four broad categories such that (i) four internalin genes inlC2, inlD, lmo0331 and lmo0610 show temperature-dependent expression similar to sigB and the σB-dependent gene opuCA; (ii) three internalin genes inlA, inlB and inlC show temperature-dependent expression similar to the PrfA-dependent gene plcA; (iii) five internalin-like genes inlG, inlJ, lmo0327, lmo0514 and lmo1290 show unique temperature-dependent expression and (iv) twelve internalin genes show no difference in expression under the conditions investigated in this study. Our data also shows that the expression of many housekeeping genes can vary considerably under different temperatures, and normalization of both microarray and qRT-PCR data using housekeeping genes should be based on comprehensive experimental validation. Keywords: Listeria monocytogenes, internalins, temperature, sub-genomic microarrays