Project description:Deep sequencing of total RNA extracted from the genital discs of males for each of the following strains : Drosophila sechellia, Drosophila mauritiana, hybrid introgression line 3Q1(A) and hybrid introgression line Q1(A)
2011-07-22 | GSE28663 | GEO
Project description:California Scrub Oak Phylogeny and Introgression
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:Polycomb/Trithorax response elements (PRE/TREs) can switch their function reversibly between silencing and activation, by mechanisms that are poorly understood. Here we show that a switch in forward and reverse noncoding transcription from the Drosophila vestigial (vg) PRE/TRE switches the status of the element between silencing (induced by the forward strand) and activation (induced by the reverse strand). In vitro, both ncRNAs inhibit PRC2 histone methyltransferase activity, but in vivo only the reverse strand binds PRC2. Overexpression of the reverse strand evicts PRC2 from chromatin and inhibits its enzymatic activity. We propose that interactions of RNAs with PRC2 are differentially regulated in vivo, allowing regulated inhibition of local PRC2 activity. Genome-wide analysis shows that strand switching of ncRNAs occurs at several hundred PcG binding sites in fly and vertebrate genomes. This work identifies a novel and potentially widespread class of PRE/TREs that switch function by switching the direction of ncRNA transcription. E(Z) and H3K27me3 profile in Drosophila embryos of two transgenic lines (pKC27.vg.fwd' and pKC27.vg.rev') that were crossed to daGAL4 in order to overexpress the forward or the reverse vg PRE/TRE ncRNA from an ectopic site ('site 1' in this study).
Project description:Deep sequencing of total RNA extracted from the genital discs of males for each of the following strains : Drosophila sechellia, Drosophila mauritiana, hybrid introgression line 3Q1(A) and hybrid introgression line Q1(A) Analysis of poly(A)+ RNA for three independent biological replicates of sequencing libraries for each of the following strains: D. sechellia w, D. mauritiana P-insertion Q1, hybrid introgression line 3Q1(A), and hybrid introgression line Q1(A). Male genital discs were obtained as described above, and total RNA was extracted using RNAqueousM-CM-^BM-BM-.-Micro Kit (Ambion). Poly(A)+ transcripts were isolated subsequently using MicroPoly(A)PuristM-CM-"M-BM-^DM-BM-" Kit (Ambion). To facilitate normalization of reads across our samples, at this stage of library construction we spiked-in small amounts of exogenous RNA from ArrayControlM-CM-"M-BM-^DM-BM-" Kit (Ambion) into each sample of poly(A)+ RNA. Paired-end sequencing was carried out by loading the samples onto four lanes (three samples per lane) of a flow cell and run on an Illumina Genome Analyzer IIx sequencer using 72 cycles per end of each paired-end read. Biological replicates of each genotype were loaded onto separate lanes.
Project description:We report on a genome-wide scan for introgression in the house mouse (Mus musculus domesticus) involving the Algerian mouse (Mus spretus), using 20 samples from the ranges of sympatry and allopatry. Our analysis reveals significant variability in introgression signatures along the genomes, as well as across the samples. We find that fewer than half of the chromosomes in each genome harbor all detectable introgression. Further, a surprising result is that European mice carry more M. spretus alleles than the sympatric African ones. Using the length distribution and sharing patterns of introgressed genomic tracts across the samples, we propose three hypotheses. First, at least three distinct hybridization events involving M. spretus have occurred, one of which is ancient, and the other two are recent. Second, several of the inferred introgressed tracts contain genes that are likely to confer adaptive advantage. Third, introgressed tracts might contain driver genes that determine the evolutionary fate of those tracts. Further, our analysis revealed introgressed genes of functional importance, including the Vkorc1 gene, which is implicated in rodenticide resistance, and olfactory receptor genes. Our findings highlight the extent and role of introgression in nature, and call for careful analysis and interpretation of house mouse data in evolutionary and genetic studies.