Drosophila melanogaster
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ABSTRACT:
PROVIDER: PRJNA309630 | ENA |
REPOSITORIES: ENA
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Project description:Background: Transposable elements (TEs) represent a substantial fraction of the genomes, playing a major role in evolution, as sources of genetic variability. To fully appraise the role of TE in the acquisition of genetic novelty in genome evolution, we must also consider the impact of their own transcriptional activity. Results: We studied impact of TE transcriptional activity on gene using high-throughput RNA-Seq sequencing in Drosophila melanogaster. TEs, which turn out to be expressed in euchromatin as well as in heterochromatin, interact with genes at different levels. The observed transcription from TEs involve canonical or non-canonical transcription start sites (TSSs) distributed along their sequence. We also find evidences for potential bidirectional transcription from the TE promoter regions where the antisense transcript is co-opted by the host genome as TSSs of a gene. We found that active TEs seem to accumulate in the 5' upstream regions of the genes, and possibly provide an alternative transcript of the nearby gene. Indeed, predominantly, the TE transcript is collinear and overlapping the gene. Apart from the 5' upstream regions, we also found that most active TEs are transcribed on the gene transcript strand. Conversely, few transcripts from TE are anti sense with respect to the gene. This suggests that they have a disruptive action and are counter-selected. The only exceptions are for TEs located into introns, where they could provide another complex way of gene regulation, and in the 3' downstream region, where other mechanisms akin to siRNAs could take place. Finally, we noted several cases where the cryptic TSS is located on TE fragments corresponding to a low complexity sequence. Frequently these TE fragments appear to be over-represented when close to genes, suggesting a possible selected role. Conclusion: Altogether, these results suggest that active transposable elements influence host gene transcription. It is likely that some features of transposable elements have been exaptated in order to enrich the genes repertoire by opening routes to sub- or neo-functionalization. Examination of the transcription produced by transposable elements in D. melanogaster
2014-01-01 | E-GEOD-52472 | biostudies-arrayexpress
Project description:Drosophila Piwi-family proteins have been implicated in transposon control. Here, we examine piwi-interacting RNAs (piRNAs) associated with each Drosophila Piwi protein and find that Piwi and Aubergine bind RNAs that are predominantly antisense to transposons, whereas Ago3 complexes contain predominantly sense piRNAs. As in mammals, the majority of Drosophila piRNAs are derived from discrete genomic loci. These loci comprise mainly defective transposon sequences, and some have previously been identified as master regulators of transposon activity. Our data suggest that heterochromatic piRNA loci interact with potentially active, euchromatic transposons to form an adaptive system for transposon control. Complementary relationships between sense and antisense piRNA populations suggest an amplification loop wherein each piRNA-directed cleavage event generates the 5’ end of a new piRNA. Thus, sense piRNAs, formed following cleavage of transposon mRNAs, may enhance production of antisense piRNAs, complementary to active elements, by directing cleavage of transcripts from master control loci. Keywords: small RNA libraries from Drosophila ovaries
2007-03-08 | GSE6734 | GEO
Project description:Developmental regulation of piRNAs during spermatogenesis in Drosophila melanogaster
| PRJNA285464 | ENA
Project description:Experiment to estimate mutatational variance of gene expression in Drosophila melanogaster at two times in development using 12 mutation accumulation lines. Keywords = evolution Keywords = quantitative genetics Keywords = Drosophila Keywords = mutation Keywords: other
2005-09-04 | GSE2126 | GEO
Project description:Argonaute proteins of the PIWI-clade, complexed with PIWI-interacting RNAs (piRNAs), protect the animal germline genome by silencing transposable elements. One of the leading experimental systems for studying piRNA biology is the Drosophila melanogaster ovary. In addition to classical mutagenesis, transgenic RNA interference (RNAi), which enables tissue-specific silencing of gene expression, plays a central role in piRNA research. Here, we establish a versatile toolkit focused on piRNA biology that integrates transgenic RNAi in the germline, GFP-marker lines for key proteins of the piRNA pathway, and reporter transgenes to establish genetic hierarchies. We compare constitutive, pan-germline RNAi with an equally potent transgenic RNAi system that is activated only upon germ cell cyst formation. Stage specific RNAi allows investigating the role of genes essential for cell survival (e.g. nuclear RNA export or the SUMOylation pathways) in piRNA-dependent and independent transposon silencing. Our work forms the basis for an expandable genetic toolkit available from the Vienna Drosophila Resource Center.
2021-05-19 | GSE174611 | GEO
Project description:The PIWI-interacting RNA (piRNA) pathway plays a crucial role in preventing endogenous genomic parasites, transposable elements (TEs), from damaging the genetic material of animal gonadal cells. Specific regions in the genome, called piRNA clusters, define each species’ piRNA repertoire and therefore its capacity to recognize and silence transposons. In the somatic cells of the Drosophila melanogaster ovary, the flamenco (flam) unistrand cluster is the main source of piRNAs and primarily regulates Gypsy family TEs that are able to form virus-like particles and infect neighbouring germ cells. Disruption of the flam locus or failure to process flam precursor transcripts into piRNAs results in sterility, yet it remains unknown whether this silencing mechanism is employed widely across Drosophilidae. Here, using both synteny-based analyses and de novo TE annotation, we identify candidate loci sharing both their organisation and TE targeting repertoire with flam in widely divergent Drosophila species groups. Small RNA-sequencing validated these loci as bona-fide unistrand piRNA clusters and revealed their predominant expression in somatic cells of the ovary, likely to counter TE mobilisation in this tissue. This study provides compelling evidence of co-evolution between virus-like Gypsy family transposons and a host defence mechanism in form of soma-expressed, unistrand piRNA clusters.
2023-09-26 | GSE240910 | GEO
Project description:The PIWI-interacting RNA (piRNA) pathway plays a crucial role in preventing endogenous genomic parasites, transposable elements (TEs), from damaging the genetic material of animal gonadal cells. Specific regions in the genome, called piRNA clusters, define each species’ piRNA repertoire and therefore its capacity to recognize and silence transposons. In the somatic cells of the Drosophila melanogaster ovary, the flamenco (flam) unistrand cluster is the main source of piRNAs and primarily regulates Gypsy family TEs that are able to form virus-like particles and infect neighbouring germ cells. Disruption of the flam locus or failure to process flam precursor transcripts into piRNAs results in sterility, yet it remains unknown whether this silencing mechanism is employed widely across Drosophilidae. Here, using both synteny-based analyses and de novo TE annotation, we identify candidate loci sharing both their organisation and TE targeting repertoire with flam in widely divergent Drosophila species groups. Small RNA-sequencing validated these loci as bona-fide unistrand piRNA clusters and revealed their predominant expression in somatic cells of the ovary, likely to counter TE mobilisation in this tissue. This study provides compelling evidence of co-evolution between virus-like Gypsy family transposons and a host defence mechanism in form of soma-expressed, unistrand piRNA clusters.
2023-09-26 | GSE225888 | GEO
Project description:Transposons evolve rapidly and can mobilize and trigger genetic instability. piRNAs silence these genome pathogens, but it is unclear how the piRNA pathway adapts to new transposons. In Drosophila piRNAs, encoded by heterochromatic clusters are maternally deposited in the embryo. Paternally inherited P-element transposons thus escape silencing and trigger a genetic instability and sterility. We show that this syndrome, termed P-M hybrid dysgenesis, also disrupts the piRNA biogenesis machinery and activates resident transposons. As dysgenic hybrids age, however, fertility is restored, P-elements are silenced, and P-element piRNAs are produced de novo. In addition, the piRNA biogenesis machinery is restored and resident elements are silenced. Significantly, new resident transposons insertions accumulate in piRNA clusters, and these new insertions are transmitted to progeny with high fidelity, produce novel piRNAs, and are associated with reduced transposition. P-M hybrid dysgenesis thus leads to heritable changes in chromosome structure that appear to enhance transposon silencing.
2011-12-23 | GSE31813 | GEO
Project description:Background: Transposable elements (TEs) represent a substantial fraction of the genomes, playing a major role in evolution, as sources of genetic variability. To fully appraise the role of TE in the acquisition of genetic novelty in genome evolution, we must also consider the impact of their own transcriptional activity. Results: We studied impact of TE transcriptional activity on gene using high-throughput RNA-Seq sequencing in Drosophila melanogaster. TEs, which turn out to be expressed in euchromatin as well as in heterochromatin, interact with genes at different levels. The observed transcription from TEs involve canonical or non-canonical transcription start sites (TSSs) distributed along their sequence. We also find evidences for potential bidirectional transcription from the TE promoter regions where the antisense transcript is co-opted by the host genome as TSSs of a gene. We found that active TEs seem to accumulate in the 5' upstream regions of the genes, and possibly provide an alternative transcript of the nearby gene. Indeed, predominantly, the TE transcript is collinear and overlapping the gene. Apart from the 5' upstream regions, we also found that most active TEs are transcribed on the gene transcript strand. Conversely, few transcripts from TE are anti sense with respect to the gene. This suggests that they have a disruptive action and are counter-selected. The only exceptions are for TEs located into introns, where they could provide another complex way of gene regulation, and in the 3' downstream region, where other mechanisms akin to siRNAs could take place. Finally, we noted several cases where the cryptic TSS is located on TE fragments corresponding to a low complexity sequence. Frequently these TE fragments appear to be over-represented when close to genes, suggesting a possible selected role. Conclusion: Altogether, these results suggest that active transposable elements influence host gene transcription. It is likely that some features of transposable elements have been exaptated in order to enrich the genes repertoire by opening routes to sub- or neo-functionalization.
2014-01-01 | GSE52472 | GEO
Project description:The PIWI-interacting RNA (piRNA) pathway plays a crucial role in preventing endogenous genomic parasites, transposable elements (TEs), from damaging the genetic material of animal gonadal cells. Specific regions in the genome, called piRNA clusters, define each species’ piRNA repertoire and therefore its capacity to recognize and silence transposons. In the somatic cells of the Drosophila melanogaster ovary, the flamenco (flam) unistrand cluster is the main source of piRNAs and primarily regulates Gypsy family TEs that are able to form virus-like particles and infect neighbouring germ cells. Disruption of the flam locus or failure to process flam precursor transcripts into piRNAs results in sterility, yet it remains unknown whether this silencing mechanism is employed widely across Drosophilidae. Here, using both synteny-based analyses and de novo TE annotation, we identify candidate loci sharing both their organisation and TE targeting repertoire with flam in widely divergent Drosophila species groups. Small RNA-sequencing validated these loci as bona-fide unistrand piRNA clusters and revealed their predominant expression in somatic cells of the ovary, likely to counter TE mobilisation in this tissue. This study provides compelling evidence of co-evolution between virus-like Gypsy family transposons and a host defence mechanism in form of soma-expressed, unistrand piRNA clusters.
2023-09-26 | GSE225887 | GEO