Project description:Yeast cells can be affected during their growth to several stress conditions. One of the most known and characterised is the osmotic stress and most of the studies about osmotic sterss response in yeast have been focused on salt or sorbitol stress. However, during yeast growth in industrially relevant processes (for instance throughout alcoholic fermentation on the must to produce alcoholic beverages) the osmotic stress is mainly due to the high sugar(in particular glucose) concentration (200-250 g/L).
Project description:Development of molecular approaches based on chromosome conformation capture (3C) technology such as Hi-C, combined with methods for modeling and interpreting chromatin interaction data, have revolutionized the analysis of chromosome folding. Even if the impact of chromatin structure on gene expression seems likely, little is known about the dynamics of DNA compaction and the factors involved in this process still have to be determined. Using the yeast Saccharomyces cerevisiae as a model, we used Hi-C technology to evaluate how 3D chromatin structure changes during different cellular processes such as adaptation in response to stress or DNA repair. We optimized the protocol from Belton, J.M et al (1) to produce our Hi-C libraries, one from control cells, one from cells after oxidative stress and one from cells after UV irradiation. Preliminary analysis suggests that in response to oxidative stress, chromosomes tend to make more contacts in trans and less contacts in cis compared to normal condition.
Project description:Second fermentation in a bottle supposes such specific conditions that undergo yeasts to a set of stress situations like high ethanol, low nitrogen, low pH or sub-optimal temperature. Also, yeast have to grow until 1 or 2 generations and ferment all sugar available while they resist increasing CO2 pressure produced along with fermentation. Because of this, yeast for second fermentation must be selected depending on different technological criteria such as resistance to ethanol, pressure, high flocculation capacity, and good autolytic and foaming properties. All of these stress factors appear sequentially or simultaneously, and their superposition could amplify their inhibitory effects over yeast growth. Considering all of the above, it has supposed interesting to characterize the adaptive response of commercial yeast strain EC1118 during second-fermentation experiments under oenological/industrial conditions by transcriptomic profiling. We have pointed ethanol as the most relevant environmental condition in the induction of genes involved in respiratory metabolism, oxidative stress, autophagy, vacuolar and peroxisomal function, after comparison between time-course transcriptomic analysis in alcoholic fermentation and transcriptomic profiling in second fermentation. Other examples of parallelism include overexpression of cellular homeostasis and sugar metabolism genes. Finally, this study brings out the role of low-temperature on yeast physiology during second-fermentation.