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: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: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.
Project description:In order to characterize duplication polymorphisms in Drosophila simulans, we applied comparative genome hybridization (CGH) using tiling arrays originally designed to cover the full euchromatic genome of its sister species D. melanogaster. We only used the ~900,000 probes in the tiling arrays that had a perfect and unique match to the D. simulans genome (droSim1). We inferred copy number changes with a Hidden Markov Model (HMM) that returned the posterior probabilities for copy number by comparing DNA hybridization intensities between natural isolates. The probabilities of mutation were parsed to make duplication calls. The supplementary file linked to each Sample record contains for each probe, its location in the D. simulans genome and its posterior probability of being duplicated (output from the Hiddem Markov Model)
Project description:We used DamID-seq to analyze the genome-wide binding patterns of the group B Sox proteins Dichaete and SoxNeuro in four species of Drosophila: D. melanogaster, D. simulans, D. yakuba and D. pseudoobscura. Both binding site turnover between species and a comparison of the binding properties of the two partially-redundant transcription factors were analyzed. We found that, despite widespread turnover, genomic intervals that are commonly bound by both Dichaete and SoxNeuro are highly conserved in Drosophila. DamID for Dichaete (Dichaete-Dam) was performed in D. melanogaster, D. simulans, D. yakuba and D. pseudoobscura, while DamID for SoxNeuro (SoxN-Dam) was performed in D. melanogaster and D. simulans. The control experiment, Dam-only, was performed in all species. Three biological replicates were sequenced for each condition in each species.
Project description:This is a dataset which comprises the following two different kinds of genomic data in Drosophila species: First, triplicate ChIP-seq data of CTCF (CCCTC binding factor) binding profiles in each of the four closely related Drosophila species : Drosophila melanogaster, Drosophila simulans, Drosophila yakuba and Drosophila pseudoobscura at white pre pupa stage; Second, triplicate RNA-seq data of white pre pupa whole animals of three Drosophila species: Drosophila melanogaster, Drosophila simulans and Drosophila yakub. The binding site/region/peaks are called using a modified method of QuEST( please see details in our related publication). The sequence read counts and RPKM values are calculated following the method in Mortazavi et al 2008 Nature Methods paper. For data usage terms and conditions, please refer to http://www.genome.gov/27528022 and http://www.genome.gov/Pages/Research/ENCODE/ENCODEDataReleasePolicyFinal2008.pdf
Project description:Speciation involves the reproductive isolation of natural populations due to the sterility or lethality of their hybrids. However, the molecular basis of hybrid lethality and the evolutionary driving forces that provoke it, remain largely elusive. The hybrid male rescue (Hmr) and the lethal hybrid rescue (Lhr) genes serve as a model to study speciation in Drosophilids as their interaction causes lethality in male hybrid offspring. Here we show that HMR and LHR form a centromeric complex necessary for proper chromosome segregation. We find that the Hmr expression level is substantially higher in D. melanogaster whereas Lhr expression levels are increased in D. simulans. The resulting elevated amount of HMR/LHR complex in hybrids results in an extensive mislocalisation of the complex, an interference with the regulation of transposable elements and an impairment of cell proliferation. Our findings provide evidence for a major role of centromere divergence in the generation of biodiversity. Raw data were analysed using the MaxQuant 1.2.2.5 software package. Identified proteins were considered as interation partners if their MaxQuant iBAQ values displayed a greater than 16fold enrichment compared to control anti-FLAG purifications from Schneider cell nuclear extracts not expressing any FLAG-tagged protein.