Project description:Analysis of copy number variation in evolved haploid, diploid, tetraploid strains. All experimental samples were compared to the same reference strain S288C. The samples include the progenitor strains for the haploid, diploid, and tetraploid evolution experiments, and single colony isolates (clones) from the evolving populations at given time points. Evolved clones were analyzed at generation 250 unless the name is followed by gen35, gen55 or gen500, in which case those generations were analyzed.
Project description:Haploid, diploid, and tetraploid yeast were experimentally evolved in 2% raffinose medium. After 250 generations, we assessed the gene expression alterations in 2 evolved haploids, 2 evolved diploids, and 4 evolved tetraploids relative to the diploid ancestor.
Project description:Polyploidy is observed across the tree of life, yet its influence on evolution remains incompletely understood. Polyploidy, usually whole-genome duplication, is proposed to alter the rate of evolutionary adaptation. This could occur through complex effects on the frequency or fitness of beneficial mutations. For example, in diverse cell types and organisms, immediately after a whole-genome duplication, newly formed polyploids missegregate chromosomes and undergo genetic instability. The instability following whole-genome duplications is thought to provide adaptive mutations in microorganisms and can promote tumorigenesis in mammalian cells. Polyploidy may also affect adaptation independently of beneficial mutations through ploidy-specific changes in cell physiology. Here we perform in vitro evolution experiments to test directly whether polyploidy can accelerate evolutionary adaptation. Compared with haploids and diploids, tetraploids undergo significantly faster adaptation. Mathematical modelling suggests that rapid adaptation of tetraploids is driven by higher rates of beneficial mutations with stronger fitness effects, which is supported by whole-genome sequencing and phenotypic analyses of evolved clones. Chromosome aneuploidy, concerted chromosome loss, and point mutations all provide large fitness gains. We identify several mutations whose beneficial effects are manifest specifically in the tetraploid strains. Together, these results provide direct quantitative evidence that in some environments polyploidy can accelerate evolutionary adaptation.
Project description:Using RNA-seq, we analyzed the transcriptomes of isogenic haploid (MATa) and tetraploid (MATaaaa) budding yeast strains in the Sigma 1278b background and identified genes whose regulation was altered by ploidy. Analysis of poly(A)+ RNA from 2 biological replicates of haploid (MATa) and tetraploid (MATaaaa) strains.
Project description:Using RNA-seq, we analyzed the transcriptomes of isogenic haploid (MATa) and tetraploid (MATaaaa) budding yeast strains in the Sigma 1278b background and identified genes whose regulation was altered by ploidy.
Project description:Strand specific RNA sequencing of S. pombe revealed a highly structured programme of ncRNA expression at over 600 loci. Waves of antisense transcription accompanied sexual differentiation. A substantial proportion of ncRNA arose from mechanisms previously considered to be largely artefactual, including improper 3’ termination and bi-directional transcription. Constitutive induction of the entire spk1+, spo4+, dis1+ and spo6+ antisense transcripts from an integrated, ectopic, locus disrupted their respective meiotic functions. This ability of antisense transcripts to disrupt gene function when expressed in trans suggests that cis production at native loci during sexual differentiation may also control gene function. Consistently, insertion of a marker gene adjacent to the dis1+ antisense start site mimicked ectopic antisense expression in reducing the levels of this microtubule regulator and abolishing the microtubule-dependent “horsetail” stage of meiosis. Antisense production had no impact at any of these loci when the RNAi machinery was removed. Thus, far from being simply ‘genome chatter’, this extensive ncRNA landscape constitutes a fundamental component in the controls that drive the complex programme of sexual differentiation in S. pombe. Thorough interrogation of the Schizosaccharomyces pombe transcriptome during sexual differentiation using strand-specific total RNA sequencing (AB SOLiD 3.0 and 3.0+). A total of 19 samples were analysed by two separate machine runs (henceforth first and second runs, respectively). In the first machine run the following 5 samples were processed (on a single sequencing slide): Vegetative haploid (strain IH5974), pat1.114 diploid (IH2912) at vegetative growth (0) and pat1.114 diploid (IH2912) at 3, 5 and 10 hours following temperature shift from 25ºC to 32ºC to induce meiosis by Pat1 inactivation. In the second machine run the following 14 samples were processed (on two sequencing slides): Vegetative haploid (IH5974), pat1.114 diploid (IH2912) at vegetative growth (0) and pat1.114 diploid (IH2912) at 3, 5 and 10 hours following the temperature shift (a biological replicate of the first machine run). In addition, asynchronous IH3365 (wild type diploid) was also sequenced to enable a series of pair-wise haploid/diploid comparisons between itself, asynchronous haploid (IH5974) and pat1.114 diploid (IH2912) at vegetative growth. Finally, to find putative targets of the two bzip transcription factors atf21 and atf31, we sequenced RNA extracts from IH8832 (atf21.delta diploid) and IH8814 (atf31.delta diploid) before (0), and 3, 5, and 10 hours after the temperature shift, while the pat1.114 diploid (IH2912) at vegetative growth (0) and pat1.114 diploid (IH2912) at 3, 5 and 10 hours following the temperature shift were used as reference for this analysis.
Project description:The aim of this study was to analyze the impact of autotetraploidy on gene expression in Arabidopsis thaliana by comparing diploid versus tetraploid transcriptomes. In particular, this included the comparison of the transcriptome of different tetraploid A. thaliana ecotypes (Col-0 vs. Ler-0). The study was extended to address further aspects. One was the comparison of the transcriptomes in subsequent generations. This intended to obtain information on the genome wide stability of autotetraploid gene expression. Another line of work compared the transcriptomes of different diploid vs. tetraploid tissues. This aimed to investigate whether particular gene groups are specifically affected during the development of A. thaliana autotetraploids. Samples 1-8: Arabidopsis thaliana Col-0 tetraploid transcriptome. Transcriptional profiling and comparison of diploid vs. tetraploid Col-0 seedlings. The experiment was carried out with pedigree of independently generated and assessed tetraploid Col-0 lines. Samples 9-12: Arabidopsis thaliana Ler-0 tetraploid transcriptome. Transcriptional profiling and comparison of diploid vs. tetraploid Ler-0 seedlings. The experiment was carried out with pedigree of independently generated and assessed tetraploid Ler-0 lines. Samples 13-24: Arabidopsis thaliana Col-0 tetraploid transcriptome. Transcriptional profiling and comparison of diploid vs. tetraploid Col-0 leaves (6th - 8th). The experiment was carried out with pedigree of independently generated and assessed tetraploid Col-0 lines. Samples 25-32: Arabidopsis thaliana Ler-0 tetraploid transcriptome. Transcriptional profiling and comparison of diploid vs. tetraploid Ler-0 leaves (6th - 8th). The experiment was carried out with pedigree of independently generated and assessed tetraploid Ler-0 lines. Samples 33-36: Arabidopsis thaliana Ler-0 tetraploid transcriptome. Transcriptional profiling and comparison of tetraploid vs. tetraploid Ler-0 seedlings from the second (F2) and third (F3) generation after induction, respectively. The experiment was carried out with pedigree of independently generated and assessed tetraploid Ler-0 lines. Samples 37-40: Arabidopsis thaliana Col-0 tetraploid transcriptome. Transcriptional profiling and comparison of tetraploid vs. tetraploid Col-0 seedlings from the second (F2) and third (F3) generation after induction, respectively. The experiment was carried out with pedigree of independently generated and assessed tetraploid Col-0 lines. Samples 41-44: Arabidopsis thaliana Col-0/Ler-0 diploid transcriptome. Transcriptional profiling and comparison of diploid Col-0 vs. diploid Ler-0 seedlings. The experiment was carried out with pedigree of esrablished lines. Samples 45-48: Arabidopsis thaliana Col-0/Ler-0 tetraploid transcriptome. Transcriptional profiling and comparison of tetraploid Col-0 vs tetraploid Ler-0 seedlings. The experiment was carried out with pedigree of independently generated and assessed tetraploid Col-0 and Ler-0 lines.