Project description:The environmental stresses and inhibitors encounted by Saccharomyces cerevisiae strains are main limiting factors in bioethanol fermentation. Investigation of the molecular mechanisms underlying the stresses-related phenotypes diversities within and between S. cerevisiae populations could guide the construction of yeast strains with improved stresses tolerance and fermentation performances. Here, we explored the genetic characteristics of the bioethanol S. cerevisiae strains, and elucidated the genetic variations correlated with its advantaged traits (higher ethanol yield under sever conditions and better tolerance to multiple stresses compared to an S288c derived laboratory strain BYZ1). Firstly, pulse-field gel electrophoresis combined with array-comparative genomic hybridization was used to compare the genome structure of industrial strains and the laboratory strain BYZ1.
Project description:We study the genetics, including microarray karyotyping using comparative genomic hybridization, to explore global changes in the genomic DNA of seven S. cerevisiae strains related to traditional fermentations of very different sources comparing to the sequenced S. cerevisiae laboratory strain (S288C). Our final goal is to determine the adaptive evolution of properties of biotechnological interest in Saccharomyces yeasts. Many copy number variations (CNVs) were observed, especially in genes associated to subtelomeric regions and transposon elements. Among the fermentation strains, differential CNV was observed in genes related to sugar transport and metabolism. An outstanding example of diverse CNV is the gen PUT1, involved in proline assimilation, which correlated with the adaptation of the strains to the presence of this nitrogen source in the media.
Project description:We study the genetics, including microarray karyotyping using comparative genomic hybridization to explore global changes in the genomic DNA, of four S. bayanus var uvarum strains related to traditional fermentations of very different sources comparing to the sequenced S. cerevisiae laboratory strain (S288C). Our final goal is to determine the adaptive evolution of properties of biotechnological interest in Saccharomyces yeasts. Many copy number variations (CNV) were observed, especially in genes associated to subtelomeric regions and transposon elements. Among the fermentation strains, differential CNV was observed in genes related to sugar transport and metabolism. An outstanding example of diverse CNV is the gen PUT1, involved in proline assimilation, which correlated with the adaptation of the strains to the presence of this nitrogen source in the media.
Project description:We created a multi-species microarray platform, containing probes to the whole genomes of seven different Saccharomyces species, with very dense coverage (one probe every ~500 bp) of the S. cerevisiae genome, including non-S288c regions, mitochondrial and 2 micron circle genomes, plus probes at fairly dense coverage (one probe every ~2,100 bp) for each of the genomes of six other Saccharomyces species: S. paradoxus, S. mikatae, S. kudriavzevii, S. bayanus, S. kluyveri and S. castellii. We performed array-Comparative Genomic Hybridization (aCGH) using this platform, examining 83 different Saccharomyces strains collected across a wide range of habitats; of these, 69 were widely used commercial S. cerevisiae wine strains, while the remaining 14 were from a wide range of other industrial and natural habitats. Thus, we were able to sample much of the pan-genome space of the Saccharomyces genus. We observed interspecific hybridization events, introgression events, and pervasive copy number variation (CNV) in all but a few of the strains. These CNVs were distributed throughout the strains such that they did not produce any clear phylogeny, suggesting extensive mating in both industrial and wild strains. To validate our results and to determine whether apparently similar introgressions and CNVs were identical by descent or recurrent, we also performed whole genome sequencing on nine of these strains. These data may help pinpoint genomic regions involved in adaptation to different industrial milieus, as well as shed light on the course of domestication of S. cerevisiae.
Project description:We developed an artificial genome evolution system, which we termed ‘TAQing’, by introducing multiple genomic DNA double-strand breaks using a heat-activatable endonuclease in mitotic yeast. The heat-activated endonuclease, TaqI, induced random DSBs, which resulted in diverse types of chromosomal rearrangements including translocations. Array comparative genomic hybridization (aCGH) analysis was performed with cell-fused Saccharomyces cerevisiae strains induced genome evolution by TAQing system. Some of copy number variations (CNVs) induced by massive genome rearrangements were detected in the TAQed yeast strains.
Project description:We study the genetics, including microarray karyotyping using comparative genomic hybridization, to explore global changes in the genomic DNA of seven S. cerevisiae strains related to traditional fermentations of very different sources comparing to the sequenced S. cerevisiae laboratory strain (S288C). Our final goal is to determine the adaptive evolution of properties of biotechnological interest in Saccharomyces yeasts. Many copy number variations (CNVs) were observed, especially in genes associated to subtelomeric regions and transposon elements. Among the fermentation strains, differential CNV was observed in genes related to sugar transport and metabolism. An outstanding example of diverse CNV is the gen PUT1, involved in proline assimilation, which correlated with the adaptation of the strains to the presence of this nitrogen source in the media. Seven S. cerevisiae strains were obtained from natural environments and different fermentation processes. The S. cerevisiae strain S288C was used as a control for microarray hybridizations. All experiments were performed using duplicate arrays, and Cy5-dCTP and Cy3-dCTP dye-swap assays were performed to reduce dye-specific bias.
Project description:High-throughput techniques for detecting DNA polymorphisms generally do not identify changes in which the genomic position of a sequence, but not its copy number, varies among individuals. To explore such balanced structural polymorphisms, we used array-based Comparative Genomic Hybridization (aCGH) to conduct a genome-wide screen for single-copy genomic segments that occupy different genomic positions in the standard laboratory strain of Saccharomyces cerevisiae (S90) and a polymorphic wild isolate (Y101) through analysis of six tetrads from a cross of these two strains. Paired-end high-throughput sequencing of Y101 validated four of the predicted rearrangements. The transposed segments contained one to four annotated genes each, yet crosses between S90 and Y101 yielded mostly viable tetrads. The longest segment comprised 13.5 kb near the telomere of chromosome XV in the S288C reference strain and Southern blotting confirmed its predicted location on chromosome IX in Y101. Interestingly, inter-locus crossover events between copies of this segment occurred at a detectable rate. The presence of low-copy repetitive sequences at the junctions of this segment suggests that it may have arisen through ectopic recombination. Our methodology and findings provide a starting point for exploring the origins, phenotypic consequences, and evolutionary fate of this largely unexplored form of genomic polymorphism.