Project description:Evolutionary engineering strategy was used for selection of ethanol-tolerant Saccharomyces cerevisiae clones under gradually increasing ethanol stress levels. Clones B2 and B8 were selected based on their higher ethanol-tolerance and higher ethanol production levels. Whole genome microarray analysis was used for identifying the gene expression levels of these two evolved clones compared to the reference strain.
2016-03-01 | GSE78759 | GEO
Project description:Sequencing of laboratory evolved heterozygous Saccharomyces cerevisiae clones
Project description:Evolutionary engineering strategy was used for selection of ethanol-tolerant Saccharomyces cerevisiae clones under gradually increasing ethanol stress levels. Clones B2 and B8 were selected based on their higher ethanol-tolerance and higher ethanol production levels. Whole genome microarray analysis was used for identifying the gene expression levels of these two evolved clones compared to the reference strain. Two evolved ethanol-tolerant strains B2 and B8, which were selected by evolutionary engineering under gradually increasing ethanol stress, were used for whole genome transcriptomic analysis in comparison with the reference strain. Cells were grown in yeast minimal media until they reach a final OD600 of 1. Following total RNA isolation, gene expression levels were analyzed using One-color microarray-based gene expression analysis (Agilent Technologies). Experiments were done in triplicates.
Project description:We have employed whole genome microarray expression profiling as a discovery platform to identify genes implicated in the resistance to cobalt in Saccharomyces cerevisiae. The evolved strains and the wild type were harvested in exponential phase WT (CEN.PK), the evolved strain (CI25E) and the evolved strain delta Cot1 harvested in exponential phase (DO 600nm=3) ; three independant replicate for each.
Project description:We have employed whole genome microarray expression profiling as a discovery platform to identify genes implicated in the resistance to cobalt in Saccharomyces cerevisiae. The evolved strains and the wild type were harvested in exponential phase
Project description:CGH arrays for Smukowski Heil, et al MBE 2017. Hybridization is often considered maladaptive, but sometimes hybrids can invade new ecological niches and adapt to novel or stressful environments better than their parents. The genomic changes that occur following hybridization that facilitate genome resolution and/or adaptation are not well understood. Here, we address these questions using experimental evolution of de novo interspecific hybrid yeast Saccharomyces cerevisiae x Saccharomyces uvarum and their parentals. We evolved these strains in nutrient limited conditions for hundreds of generations and sequenced the resulting cultures to identify genomic changes. Analysis of 16 hybrid clones and 16 parental clones identified numerous point mutations, copy number changes, and loss of heterozygosity events, including species biased amplification of nutrient transporters. We focused on a particularly interesting example, in which we saw repeated loss of heterozygosity at the high affinity phosphate transporter gene PHO84 in both intra- and interspecific hybrids. Using allele replacement methods, we tested the fitness of different alleles in hybrid and S. cerevisiae strain backgrounds and found that the loss of heterozygosity is indeed the result of selection on one allele over the other in both S. cerevisiae and the hybrids. This is an example where hybrid genome resolution is driven by positive selection on existing heterozygosity, and demonstrates that even infrequent outcrossing may have lasting impacts on adaptation.
Project description:Saccharomyces cerevisiae IMS0002 which, after metabolic and evolutionary engineering, ferments the pentose sugar arabinose. Glucose and arabinose-limited anaerobic chemostat cultures of IMS0002 and its non-evolved ancestor IMS0001 were subjected to transcriptome analysis to identify key genetic changes contributing to efficient arabinose utilization by strain IMS0002.
Project description:Aneuploidy is a hallmark of tumor cells, and yet the precise relationship between aneuploidy and a cell’s proliferative ability, or cellular fitness, has remained elusive. In this study, we have combined a detailed analysis of aneuploid clones isolated from laboratory-evolved populations of Saccharomyces cerevisiae with a systematic, genome-wide screen for the fitness effects of telomeric amplifications to address the relationship between aneuploidy and cellular fitness. We found that aneuploid clones rise to high population frequencies in nutrient-limited evolution experiments and show increased fitness relative to wild type. Direct competition experiments confirmed that three out of four aneuploid events isolated from evolved populations were themselves sufficient to improve fitness. To expand the scope beyond this small number of exemplars, we created a genome-wide collection of >1,800 diploid yeast strains, each containing a different telomeric amplicon (Tamp), ranging in size from 0.4 to 1,000 kb. Using pooled competition experiments in nutrient-limited chemostats followed by high-throughput sequencing of strain-identifying barcodes, we determined the fitness effects of these >1,800 Tamps under three different conditions. Our data revealed that the fitness landscape explored by telomeric amplifications is much broader than that explored by single-gene amplifications. As also observed in the evolved clones, we found the fitness effects of most Tamps to be condition specific, with a minority showing common effects in all three conditions. By integrating our data with previous work that examined the fitness effects of single-gene amplifications genome-wide, we found that a small number of genes within each Tamp are centrally responsible for each Tamp’s fitness effects. Our genome-wide Tamp screen confirmed that telomeric amplifications identified in laboratory-evolved populations generally increased fitness. Our results show that Tamps are mutations that produce large, typically condition-dependent changes in fitness that are important drivers of increased fitness in asexually evolving populations.