Project description:Transposable elements (TEs), whose propagation can result in severe damage to the host genome, are silenced in the animal gonad by Piwi-interacting RNAs (piRNAs). piRNAs produced in the ovaries are deposited in the embryonic germline and initiate TE repression in the germline progeny. Whether the maternally transmitted piRNAs play a role in the silencing of somatic TEs is, however, unknown. Here we show that maternally transmitted piRNAs from the tirant retrotransposon in Drosophila are required for the somatic silencing of the TE and correlate with an increase in histone H3K9 trimethylation an active tirant copy. Comparison of tirant piRNAs in two Drosophila simulans natural populations.
Project description:The comparison of transcriptome profiles among populations is a powerful tool for investigating the role of gene expression change in adaptation to new environments. In this study, we use massively parallel sequencing of 39 cDNAs obtained from large samples of adult males, to compare a population of Drosophila simulans from a natural reserve within its ancestral range (eastern Africa) with a derived population collected in the strongly anthropized Rhone valley (France). The goal was to scan for adaptation linked to the invasion of new environments by the species. Among 15,090 genes retained for the analysis, 794 were found to be differentially expressed between the two populations. We observed an increase in expression of reproduction-related genes in eastern Africa, and an even stronger increase in expression of Cytochrome P450, Glutathione transferase and Glucuronosyl transferase genes in the derived population. These three gene families are involved in detoxification processes, which suggests that pesticides are a major environmental pressure for the species in this area. The survey of the Cyp6g1 upstream region revealed the insertion of a transposable element, Juan, in the regulatory sequence that is almost fixed in the Rhoˆne Valley, but barely present in Mayotte. This shows that Cyp6g1 has undergone parallel evolution in derived populations of D. simulans as previously shown for D. melanogaster. The increasing amount of data produced by comparative population genomics and transcriptomics should permit the identification of additional genes associated with functional divergence among those differentially expressed. Two samples for two populations, with diverse medium. Each sample composed of 100 males from a 100 different wild-caught females
Project description:Hybrid incompatibility between Drosophila melanogaster and D. simulans is caused by a lethal interaction of the proteins encoded by the Hmr and Lhr genes. In D. melanogaster the loss of HMR results in mitotic defects, an increase in transcription of transposable elements and a deregulation of heterochromatic genes. To investigate the molecular mechanisms that mediate HMRs function, we measured genome-wide localization of HMR in D. melanogaster by chromatin immunoprecipitation. Interestingly, we find HMR localizing to genomic insulator sites that can be classified into two groups. One group that belongs to the gypsy class of insulators and another one that separates HP1a binding regions from active promoters. The activity of these promoters is strongly affected in Hmr mutant flies. Our data provide a novel link between HMR and insulator proteins and suggest a key role for genome organization in the formation of species.
Project description:We identified 6,975 insertion/deletion events of between 10 and 100 bp in length from the Drosophila simulans and Drosophila sechellia Mercator/MAVID genomic sequence alignment. Replicate pure samples of Drosophila simulans and Drosophila sechellia gDNA were competitively hybridized to measure the expected relative hybridization intensity of alleles from each species. We used these measured intensities to assess the likelihood that the hybridization signal at each probe in an experimental animal reflected homozygosity or heterozygosity at that locus.
2013-02-26 | GSE44443 | GEO
Project description:Natural variability of transposable element insertion sites in Drosophila melanogaster and Drosophila simulans.
Project description:Curration of small RNAs from four melanogaster-subgroup species (Drosophila simulans, Drosophila sechellia, Drosophila erecta, and Drosophila yakuba) for the purpose of non-coding RNA annotation and comparative genomics assessment.
2014-07-22 | GSE56244 | GEO
Project description:Piciformes transposable elements
Project description:The comparison of transcriptome profiles among populations is a powerful tool for investigating the role of gene expression change in adaptation to new environments. In this study, we use massively parallel sequencing of 39 cDNAs obtained from large samples of adult males, to compare a population of Drosophila simulans from a natural reserve within its ancestral range (eastern Africa) with a derived population collected in the strongly anthropized Rhone valley (France). The goal was to scan for adaptation linked to the invasion of new environments by the species. Among 15,090 genes retained for the analysis, 794 were found to be differentially expressed between the two populations. We observed an increase in expression of reproduction-related genes in eastern Africa, and an even stronger increase in expression of Cytochrome P450, Glutathione transferase and Glucuronosyl transferase genes in the derived population. These three gene families are involved in detoxification processes, which suggests that pesticides are a major environmental pressure for the species in this area. The survey of the Cyp6g1 upstream region revealed the insertion of a transposable element, Juan, in the regulatory sequence that is almost fixed in the Rhoˆne Valley, but barely present in Mayotte. This shows that Cyp6g1 has undergone parallel evolution in derived populations of D. simulans as previously shown for D. melanogaster. The increasing amount of data produced by comparative population genomics and transcriptomics should permit the identification of additional genes associated with functional divergence among those differentially expressed.