Project description:The capacity of respiring cultures of Saccharomyces cerevisiae to instantaneously switch to fast alcoholic fermentation upon a transfer to anaerobic sugar-excess conditions is a key characteristic of Saccharomyces cerevisiae in many of its industrial applications. This transition was studied by exposing aerobic glucose-limited chemostat cultures grown at a low specific growth rate to two simultaneous perturbations: oxygen depletion and relief of glucose limitation. This shift towards fully fermentative conditions caused a massive transcriptional response, where one third of all genes within the genome were transcribed differentially. During the first 30 min, most of these changes were driven by relief from glucose limitation. An anaerobic induction response was only observed after the initial response to glucose excess. By comparing this study with public datasets representing dynamic and steady conditions, 14 up-regulated and 11 down-regulated genes were determined to be anaerobiosis specific and can therefore be use as âsignatureâ transcripts for anaerobicity under dynamic as well as under steady state conditions Experiment Overall Design: To invoke rapid and full induction of fermentative capacity, respiratory, aerobic glucose-limited chemostat cultures (D=0.1â¢h-1) were shifted to fully fermentative conditions by sudden depletion of oxygen and addition of glucose. The glucose was added two min after sparging the continuous culture with pure nitrogen, when the dissolved oxygen concentration had decreased from 75-80% to 10-15% of air saturation. Samples for micro-arrays were taken for each time point after the perturbation (5, 10, 30, 60 and 120 min) from two independently cultured replicates, while steady state data were taken from three independent chemostats. The complete dataset therefore comprised 13 samples.
Project description:We report high-throughput RNA sequencing of WT, Δfnr, ΔarcA and Δihf in the exponential phase under anaerobic fermentative conditions
Project description:The capacity of respiring cultures of Saccharomyces cerevisiae to instantaneously switch to fast alcoholic fermentation upon a transfer to anaerobic sugar-excess conditions is a key characteristic of Saccharomyces cerevisiae in many of its industrial applications. This transition was studied by exposing aerobic glucose-limited chemostat cultures grown at a low specific growth rate to two simultaneous perturbations: oxygen depletion and relief of glucose limitation. This shift towards fully fermentative conditions caused a massive transcriptional response, where one third of all genes within the genome were transcribed differentially. During the first 30 min, most of these changes were driven by relief from glucose limitation. An anaerobic induction response was only observed after the initial response to glucose excess. By comparing this study with public datasets representing dynamic and steady conditions, 14 up-regulated and 11 down-regulated genes were determined to be anaerobiosis specific and can therefore be use as “signature” transcripts for anaerobicity under dynamic as well as under steady state conditions Keywords: global transcriptional time-dependent profile
Project description:We report high-throughput RNA sequencing of WT, ΔfnrΔarcA (FA), ΔfnrΔihf (FI) and ΔarcAΔihf (AI) strains in the exponential phase under anaerobic fermentative conditions
Project description:The pathophysiological mechanisms that drive non-alcoholic fatty liver disease (NAFLD) progression remain poorly understood. This multicenter study characterized the transcriptional changes that occur as liver disease progresses. 216 snap frozen liver biopsies, comprising 206 NAFLD cases with different fibrosis stages and 10 controls were studied. Samples underwent high-throughput RNA sequencing. This study provides novel insights into transcriptional changes during liver disease evolution and progression as well as proof of principle that transcriptomic changes reveal potentially tractable biomarkers for NAFLD fibrosis.
Project description:The ability of the yeast Saccharomyces cerevisiae to convert glucose, even in the presence of oxygen, via glycolysis and the fermentative pathway to ethanol has played an important role in its domestication. Despite the extensive knowledge on these pathways in S. cerevisiae, relatively little is known about these pathways in other industrially-relevant Saccharomyces yeast species. In this study we explore the diversity of the glycolytic and fermentative pathways within the Saccharomyces genus using S. cerevisiae, S. kudriavzevii and S. eubayanus as paradigms. Sequencing data revealed a highly conserved genetic makeup of the glycolytic and fermentative pathways in the three species in terms of number of paralogous genes. Although promoter regions were less conserved between the three species as compared to coding sequences, binding sites for Rap1, Gcr1 and Abf1, main transcriptional regulators of glycolytic and fermentative genes, were highly conserved. Transcriptome profiling of these three strains grown in aerobic batch cultivation in chemically defined medium with glucose as carbon source, revealed a remarkably similar expression of the glycolytic and fermentative genes across species, and the conserved classification of genes into major and minor paralogs. Furthermore, transplantation of the promoters of major paralogs of S. kudriavzevii and S. eubayanus into S. cerevisiae demonstrated not only the transferability of these promoters, but also the similarity of their strength and response to various environmental stimuli. The relatively low homology of S. kudriavzevii and S. eubayanus promoters to their S. cerevisiae relatives makes them very attractive alternatives for strain construction in S. cerevisiae, thereby expanding S. cerevisiae molecular toolbox.