Project description:In this study, we present an investigation of the yeast response to the exposure to octanoic and decanoic acids, two major fermentation inhibitors. Aerobically grown cells of Saccharomyces cerevisiae U13 wine strain have been exposed to 0,05 mM of octanoic and decanoic acid. We have compared the variations of expression induced by the acid challenges in comparison to a reference non trated modality, as well as the two acid responses. The transcriptome analysis is build in a triangular design in which the RNA extracted from three modalities : reference (non treated cells) , cells exposed to octanoic acid, and cells exposed to decanoic acid are compared.
Project description:Extensive transcriptional heterogeneity revealed by isoform profiling Application of TIF-Seq (Transcript IsoForm Sequencing) to S.cerevisiae. The method was applied to simultaneously identify the 5' capped mRNA transcription start site and the 3' polyadenylation site in different conditions: WT cells grown in glucose media [ypd, 2 biological replicates (bio) and 3 independent library preparations, technical replicates(lib)], WT cells grown in galactose media [ypgal, 4 biological replicates (bio) and 3 independent library preparations, technical replicates(lib)]. A modified protocol designed to enrich in long mRNA molecules was performed for WT cells grown in glucose media [ypd, 2 biological replicates (bio)] and in galactose media [ypgal, 2 biological replicates (bio)] conditions. Finally, control samples performed with a modified protocol designed to identify non-capped but polyadenylated molecules was performed in WT cells grown both in glucose (nypd) and galactose (nypgal) media.
Project description:The wild-type (grown on galactose or glucose) or msn2/4 mutant (grown on galactose) strains were grown aerobically. At time zero (generation 0) the sparge gas was switched from air to O2-free N2 and samples were harvested after 0 (aerobic control), 0.04, 0.08, 0.19, and 2 generations of anaerobic growth. Keywords: time-course
Project description:In previous temporal studies, we found the anaerobic response was biphasic when cells growing in galactose medium were shifted from aerobiosis to anaerobiosis, consisting of an acute, transitory phase (<60 min) followed by a more chronic but delayed phase (> 1 generation), but largely monophasic (delayed, chronic phase only) when cells were shifted in glucose medium. Gene network and functional analyses revealed the acute phase was comprised of genes associated with the retooling of metabolism (respiro-fermentative to strictly fermentative) and balancing energy supply and demand. A similar pattern of gene expression is seen when cells encounter other “environmentally stressful” conditions. However, cells shifted to anaerobiosis on glucose, in which no catabolic rearrangement is required nor change in growth rate observed, do not exhibit this pattern, suggesting the “stress” encountered is one associated with the abrupt cessation of galactose-dependent respiration and slowing of growth, not oxygen deprivation per se. In order to test this hypothesis, we added the respiratory inhibitor, antimycin A, under aerobiosis for three generations then shifted to anaerobiosis, which no catabolic rearrangement is required. Keywords: time course Sparged, fermentor cultures of a wild-type yeast strain (JM43) were aerobically grown on galactose medium (SSG-TEA) in the presence of Antimycin A for three generations. After three generations, the sparge gas was switched from air to O2-free N2 and samples were harvested after 0.04, 0.08, 0.13, 0.19, 0.25, 0.38, 0.5, 1, 2, and 3 generations of anaerobic growth in the presence of Antimycin A. Total RNA was reverse transcribed (Cy3) and hybridized against a reference (Cy5). The full time series was repeated in triplicate.
Project description:In previous temporal studies, we found the anaerobic response was biphasic when cells growing in galactose medium were shifted from aerobiosis to anaerobiosis, consisting of an acute, transitory phase (<60 min) followed by a more chronic but delayed phase (> 1 generation), but largely monophasic (delayed, chronic phase only) when cells were shifted in glucose medium. Gene network and functional analyses revealed the acute phase was comprised of genes associated with the retooling of metabolism (respiro-fermentative to strictly fermentative) and balancing energy supply and demand. A similar pattern of gene expression is seen when cells encounter other “environmentally stressful” conditions. However, cells shifted to anaerobiosis on glucose, in which no catabolic rearrangement is required nor change in growth rate observed, do not exhibit this pattern, suggesting the “stress” encountered is one associated with the abrupt cessation of galactose-dependent respiration and slowing of growth, not oxygen deprivation per se. In order to test this hypothesis, we conducted this genomic study using the respiratory inhibitor, antimycin A, under aerobiosis, which mimicked the retooling of metabolism from respiro-fermentative to strictly fermentative growth. Keywords: time course Sparged, fermentor cultures of a wild-type yeast strain (JM43) were aerobically grown on galactose medium (SSG-TEA) for six generations of preconditioning. When cell density was ≈1 Klett unit, Antimycin A (1 μM) was added into medium. Samples were harvested after 0 (control), 0.04, 0.08, 0.13, 0.19, 0.25, 0.38, 0.5, 1, 2, and 3 generations of aerobic growth in the presence of Antimycin A. Total RNA was reverse transcribed (Cy3) and hybridized against a reference (Cy5). The full time series was repeated in triplicate.
Project description:The relationship between chromatin structure and transposable element (TE) integration is a fundamental question as nucleosomes can either mediate or inhibit TE insertion. The Ty1 element in Saccharomyces cerevisiae preferentially inserts upstream of RNA Polymerase III-transcribed genes, in a manner coincident with nucleosome positioning. Ty1 insertion positions have largely been inferred from nucleosome occupancy maps, but this approach is imperfect. Nucleosome occupancy maps are typically generated from wild-type Saccharomyces cerevisiae cells grown in standard conditions. Many Ty1 studies rely on a galactose-inducible expression system and it is not yet known if Ty1 overexpression from the GAL1 promoter itself alters nucleosome organization under inducing conditions. Here, we used a galactose-inducible Ty1 expression system and genome-wide MNase-seq to determine whether Ty1 donor plasmid transformation and overexpression alter nucleosome occupancy. We find that changes in carbon source do not substantially alter genome-wide nucleosome organization. In contrast, galactose induction of Ty1 expression revealed time-dependent changes in nucleosome occupancy. Nucleosome organization is unchanged across pre-induction, 6-hour galactose exposure, and post-induction repressing conditions, but nucleosome occupancy shifted at 12 and 24 hours, with changes evident at both Pol II and tRNA genes. We also found that Ty1 integration events are rare at early time points, emerge by 12 hours, and accumulate substantially by 24 hours. Ty1 preferentially targets nucleosomal DNA, but prolonged induction shifts insertion positions relative to nucleosomes. We also find that Ty1 preferentially targets nucleosomal DNA that lies in close proximity to histones, with this preference showing time-dependent shifts during induction.
Project description:In this study, we present an investigation of the yeast response to the exposure to octanoic and decanoic acids, two major fermentation inhibitors. Aerobically grown cells of Saccharomyces cerevisiae U13 wine strain have been exposed to 0,05 mM of octanoic and decanoic acid. We have compared the variations of expression induced by the acid challenges in comparison to a reference non trated modality, as well as the two acid responses. The transcriptome analysis is build in a triangular design in which the RNA extracted from three modalities : reference (non treated cells) , cells exposed to octanoic acid, and cells exposed to decanoic acid are compared. 12 samples have been analyzed in a triangular design (4 samples per modalité), four references (non treated cells), four samples exposed to octanoic acid, four samples exposed to decanoic acid
Project description:The goal of these experiments was to define the targets of Ty3 transposition in Saccharomyces cerevisiae. Ty3 is a retroviruslike element that is found at the transcription initiation site of chromosomal tRNA genes. A Ty3 that can be induced by growth in galactose-containing medium and which was marked by an insertion of HIS3 downstream of the second open reading frame of the element (POL3) was induced to undergo transposition by plating cells onto galactose containing medium and replica-plating onto medium selective for cells that had undergone transposition. These cells were collected, DNA was extracted, and inverse PCR was performed using primers inside the Ty3 element in order to generate a library of insertion sites flanked by Illumina sequence-compatible primers.