41 results on '"Alain Pélisson"'
Search Results
2. The Mi-2 nucleosome remodeler and the Rpd3 histone deacetylase are involved in piRNA-guided heterochromatin formation
- Author
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Bruno Mugat, Simon Nicot, Carolina Varela-Chavez, Christophe Jourdan, Kaoru Sato, Eugenia Basyuk, François Juge, Mikiko C. Siomi, Alain Pélisson, and Séverine Chambeyron
- Subjects
Science - Abstract
In S. pombe, small non-coding RNA mediates heterochromatin formation by recruiting the nucleosome remodeling and histone deacetylase complex. Here, the authors show that fly nucleosome remodeler Mi-2 and histone deacetylase Rpd3 are involved in piRNA-dependent transcriptional silencing of transposable elements.
- Published
- 2020
- Full Text
- View/download PDF
3. A Transposon Story: From TE Content to TE Dynamic Invasion of Drosophila Genomes Using the Single-Molecule Sequencing Technology from Oxford Nanopore
- Author
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Mourdas Mohamed, Nguyet Thi-Minh Dang, Yuki Ogyama, Nelly Burlet, Bruno Mugat, Matthieu Boulesteix, Vincent Mérel, Philippe Veber, Judit Salces-Ortiz, Dany Severac, Alain Pélisson, Cristina Vieira, François Sabot, Marie Fablet, and Séverine Chambeyron
- Subjects
transposable elements ,ONT ,Drosophila melanogaster ,Drosophila simulans ,piRNA ,Cytology ,QH573-671 - Abstract
Transposable elements (TEs) are the main components of genomes. However, due to their repetitive nature, they are very difficult to study using data obtained with short-read sequencing technologies. Here, we describe an efficient pipeline to accurately recover TE insertion (TEI) sites and sequences from long reads obtained by Oxford Nanopore Technology (ONT) sequencing. With this pipeline, we could precisely describe the landscapes of the most recent TEIs in wild-type strains of Drosophila melanogaster and Drosophila simulans. Their comparison suggests that this subset of TE sequences is more similar than previously thought in these two species. The chromosome assemblies obtained using this pipeline also allowed recovering piRNA cluster sequences, which was impossible using short-read sequencing. Finally, we used our pipeline to analyze ONT sequencing data from a D. melanogaster unstable line in which LTR transposition was derepressed for 73 successive generations. We could rely on single reads to identify new insertions with intact target site duplications. Moreover, the detailed analysis of TEIs in the wild-type strains and the unstable line did not support the trap model claiming that piRNA clusters are hotspots of TE insertions.
- Published
- 2020
- Full Text
- View/download PDF
4. MicroRNA-Dependent Transcriptional Silencing of Transposable Elements in Drosophila Follicle Cells.
- Author
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Bruno Mugat, Abdou Akkouche, Vincent Serrano, Claudia Armenise, Blaise Li, Christine Brun, Tudor A Fulga, David Van Vactor, Alain Pélisson, and Séverine Chambeyron
- Subjects
Genetics ,QH426-470 - Abstract
RNA interference-related silencing mechanisms concern very diverse and distinct biological processes, from gene regulation (via the microRNA pathway) to defense against molecular parasites (through the small interfering RNA and the Piwi-interacting RNA pathways). Small non-coding RNAs serve as specificity factors that guide effector proteins to ribonucleic acid targets via base-pairing interactions, to achieve transcriptional or post-transcriptional regulation. Because of the small sequence complementarity required for microRNA-dependent post-transcriptional regulation, thousands of microRNA (miRNA) putative targets have been annotated in Drosophila. In Drosophila somatic ovarian cells, genomic parasites, such as transposable elements (TEs), are transcriptionally repressed by chromatin changes induced by Piwi-interacting RNAs (piRNAs) that prevent them from invading the germinal genome. Here we show, for the first time, that a functional miRNA pathway is required for the piRNA-mediated transcriptional silencing of TEs in this tissue. Global miRNA depletion, caused by tissue- and stage-specific knock down of drosha (involved in miRNA biogenesis), AGO1 or gawky (both responsible for miRNA activity), resulted in loss of TE-derived piRNAs and chromatin-mediated transcriptional de-silencing of TEs. This specific TE de-repression was also observed upon individual titration (by expression of the complementary miRNA sponge) of two miRNAs (miR-14 and miR-34) as well as in a miR-14 loss-of-function mutant background. Interestingly, the miRNA defects differentially affected TE- and 3' UTR-derived piRNAs. To our knowledge, this is the first indication of possible differences in the biogenesis or stability of TE- and 3' UTR-derived piRNAs. This work is one of the examples of detectable phenotypes caused by loss of individual miRNAs in Drosophila and the first genetic evidence that miRNAs have a role in the maintenance of genome stability via piRNA-mediated TE repression.
- Published
- 2015
- Full Text
- View/download PDF
5. The Mi-2 nucleosome remodeler and the Rpd3 histone deacetylase are involved in piRNA-guided heterochromatin formation
- Author
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Séverine Chambeyron, Bruno Mugat, Simon Nicot, Kaoru Sato, Mikiko C. Siomi, Carolina Varela-Chavez, Christophe Jourdan, François Juge, Eugenia Basyuk, Alain Pélisson, Institut de génétique humaine (IGH), and Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
0301 basic medicine ,[SDV]Life Sciences [q-bio] ,General Physics and Astronomy ,Histone Deacetylase 1 ,Autoantigens ,Non-coding RNAs ,Epigenesis, Genetic ,Histones ,0302 clinical medicine ,Heterochromatin ,Transposition ,Drosophila Proteins ,RNA, Small Interfering ,lcsh:Science ,ComputingMilieux_MISCELLANEOUS ,Adenosine Triphosphatases ,Regulation of gene expression ,Multidisciplinary ,Protein Inhibitors of Activated STAT ,Nucleosomes ,Cell biology ,Drosophila melanogaster ,Argonaute Proteins ,Epigenetics ,Female ,endocrine system ,Science ,Piwi-interacting RNA ,Biology ,Article ,General Biochemistry, Genetics and Molecular Biology ,03 medical and health sciences ,Histone H3 ,[SDV.BBM.GTP]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Genomics [q-bio.GN] ,Animals ,Nucleosome ,Gene Silencing ,[SDV.GEN]Life Sciences [q-bio]/Genetics ,urogenital system ,Ovary ,fungi ,[SDV.BBM.BM]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Molecular biology ,General Chemistry ,030104 developmental biology ,Gene Expression Regulation ,Histone deacetylase complex ,lcsh:Q ,Histone deacetylase ,030217 neurology & neurosurgery - Abstract
In eukaryotes, trimethylation of lysine 9 on histone H3 (H3K9) is associated with transcriptional silencing of transposable elements (TEs). In drosophila ovaries, this heterochromatic repressive mark is thought to be deposited by SetDB1 on TE genomic loci after the initial recognition of nascent transcripts by PIWI-interacting RNAs (piRNAs) loaded on the Piwi protein. Here, we show that the nucleosome remodeler Mi-2, in complex with its partner MEP-1, forms a subunit that is transiently associated, in a MEP-1 C-terminus-dependent manner, with known Piwi interactors, including a recently reported SUMO ligase, Su(var)2-10. Together with the histone deacetylase Rpd3, this module is involved in the piRNA-dependent TE silencing, correlated with H3K9 deacetylation and trimethylation. Therefore, drosophila piRNA-mediated transcriptional silencing involves three epigenetic effectors, a remodeler, Mi-2, an eraser, Rpd3 and a writer, SetDB1, in addition to the Su(var)2-10 SUMO ligase., In S. pombe, small non-coding RNA mediates heterochromatin formation by recruiting the nucleosome remodeling and histone deacetylase complex. Here, the authors show that fly nucleosome remodeler Mi-2 and histone deacetylase Rpd3 are involved in piRNA-dependent transcriptional silencing of transposable elements.
- Published
- 2020
6. A transposon story : from TE content to TE dynamic invasion of Drosophila genomes using the single-molecule sequencing technology from Oxford Nanopore
- Author
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Séverine Chambeyron, Nelly Burlet, Judit Salces-Ortiz, Bruno Mugat, Philippe Veber, François Sabot, Nguyet Thi-Minh Dang, Alain Pélisson, Marie Fablet, Cristina Vieira, Yuki Ogyama, Vincent Mérel, Matthieu Boulesteix, Mourdas Mohamed, Dany Severac, Institut de génétique humaine (IGH), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Diversité, adaptation, développement des plantes (UMR DIADE), Institut de Recherche pour le Développement (IRD [France-Sud])-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad), Eléments transposables, évolution, populations, Département génétique, interactions et évolution des génomes [LBBE] (GINSENG), Laboratoire de Biométrie et Biologie Evolutive - UMR 5558 (LBBE), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Recherche en Informatique et en Automatique (Inria)-VetAgro Sup - Institut national d'enseignement supérieur et de recherche en alimentation, santé animale, sciences agronomiques et de l'environnement (VAS)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Recherche en Informatique et en Automatique (Inria)-VetAgro Sup - Institut national d'enseignement supérieur et de recherche en alimentation, santé animale, sciences agronomiques et de l'environnement (VAS)-Centre National de la Recherche Scientifique (CNRS)-Laboratoire de Biométrie et Biologie Evolutive - UMR 5558 (LBBE), Université de Lyon-Université de Lyon-Institut National de Recherche en Informatique et en Automatique (Inria)-VetAgro Sup - Institut national d'enseignement supérieur et de recherche en alimentation, santé animale, sciences agronomiques et de l'environnement (VAS)-Centre National de la Recherche Scientifique (CNRS), Universitat Pompeu Fabra [Barcelona] (UPF), Institut de Génomique Fonctionnelle - Montpellier GenomiX (IGF MGX), Institut de Génomique Fonctionnelle (IGF), Université de Montpellier (UM)-Université Montpellier 1 (UM1)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Montpellier 2 - Sciences et Techniques (UM2)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Université Montpellier 1 (UM1)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Montpellier 2 - Sciences et Techniques (UM2)-Centre National de la Recherche Scientifique (CNRS), Equipe de recherche européenne en algorithmique et biologie formelle et expérimentale (ERABLE), Inria Grenoble - Rhône-Alpes, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), Institut National de la Santé et de la Recherche Médicale (INSERM)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-BioCampus (BCM), Institut National de la Santé et de la Recherche Médicale (INSERM)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Fondation pour la Recherche Médicale, Agence Nationale de la Recherche (France), and Centre National de la Recherche Scientifique (France)
- Subjects
0301 basic medicine ,Transposable element ,Drosophila simulans ,Piwi-interacting RNA ,ONT ,Computational biology ,piRNA ,Genome ,Article ,Transposition (music) ,03 medical and health sciences ,Nanopores ,0302 clinical medicine ,Chromosome (genetic algorithm) ,[SDV.BBM.GTP]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Genomics [q-bio.GN] ,Melanogaster ,Animals ,lcsh:QH301-705.5 ,Drosophila melanogaster ,ComputingMilieux_MISCELLANEOUS ,[SDV.GEN]Life Sciences [q-bio]/Genetics ,biology ,[SDV.BBM.BM]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Molecular biology ,General Medicine ,biology.organism_classification ,[SDV.BIBS]Life Sciences [q-bio]/Quantitative Methods [q-bio.QM] ,030104 developmental biology ,lcsh:Biology (General) ,DNA Transposable Elements ,Drosophila ,Nanopore sequencing ,transposable elements ,Transposable elements ,030217 neurology & neurosurgery - Abstract
Transposable elements (TEs) are the main components of genomes. However, due to their repetitive nature, they are very difficult to study using data obtained with short-read sequencing technologies. Here, we describe an efficient pipeline to accurately recover TE insertion (TEI) sites and sequences from long reads obtained by Oxford Nanopore Technology (ONT) sequencing. With this pipeline, we could precisely describe the landscapes of the most recent TEIs in wild-type strains of Drosophila melanogaster and Drosophila simulans. Their comparison suggests that this subset of TE sequences is more similar than previously thought in these two species. The chromosome assemblies obtained using this pipeline also allowed recovering piRNA cluster sequences, which was impossible using short-read sequencing. Finally, we used our pipeline to analyze ONT sequencing data from a D. melanogaster unstable line in which LTR transposition was derepressed for 73 successive generations. We could rely on single reads to identify new insertions with intact target site duplications. Moreover, the detailed analysis of TEIs in the wild-type strains and the unstable line did not support the trap model claiming that piRNA clusters are hotspots of TE insertions., This research was funded by the Fondation pour la Recherche Médicale, grant number “DEQ20180339167” to S.C, by the ANR Exhyb to C.V., by the CNRS.
- Published
- 2020
7. Piwi Is Required during Drosophila Embryogenesis to License Dual-Strand piRNA Clusters for Transposon Repression in Adult Ovaries
- Author
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Carolina Varela-Chavez, Abdou Akkouche, Blaise Li, Raoul Raffel, Bridlin Barckmann, Alain Pélisson, Séverine Chambeyron, Bruno Mugat, Institut de génétique humaine (IGH), and Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
0301 basic medicine ,Transposable element ,endocrine system ,Chromosomal Proteins, Non-Histone ,Heterochromatin ,[SDV]Life Sciences [q-bio] ,Piwi-interacting RNA ,Epigenetic Repression ,Methylation ,Germline ,Histones ,03 medical and health sciences ,[SDV.BBM.GTP]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Genomics [q-bio.GN] ,Morphogenesis ,Animals ,Drosophila Proteins ,RasiRNA ,RNA, Small Interfering ,Molecular Biology ,ComputingMilieux_MISCELLANEOUS ,Genetics ,[SDV.GEN]Life Sciences [q-bio]/Genetics ,biology ,urogenital system ,Ovary ,Age Factors ,Gene Expression Regulation, Developmental ,Drosophila embryogenesis ,[SDV.BBM.BM]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Molecular biology ,Cell Biology ,DNA Methylation ,Drosophila melanogaster ,Fertility ,030104 developmental biology ,Histone ,Argonaute Proteins ,DNA Transposable Elements ,biology.protein ,Female ,RNA Interference ,Infertility, Female ,Reprogramming ,Protein Binding - Abstract
Most piRNAs in the Drosophila female germline are transcribed from heterochromatic regions called dual-strand piRNA clusters. Histone 3 lysine 9 trimethylation (H3K9me3) is required for licensing piRNA production by these clusters. However, it is unclear when and how they acquire this permissive heterochromatic state. Here, we show that transient Piwi depletion in Drosophila embryos results in H3K9me3 decrease at piRNA clusters in ovaries. This is accompanied by impaired biogenesis of ovarian piRNAs, accumulation of transposable element transcripts, and female sterility. Conversely, Piwi depletion at later developmental stages does not disturb piRNA cluster licensing. These results indicate that the identity of piRNA clusters is epigenetically acquired in a Piwi-dependent manner during embryonic development, which is reminiscent of the widespread genome reprogramming occurring during early mammalian zygotic development.
- Published
- 2017
8. A user-friendly chromatographic method to purify small regulatory RNAs
- Author
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Bruno Mugat, Alain Pélisson, Claudia Armenise, Thomas Grentzinger, Séverine Chambeyron, and Christine Brun
- Subjects
Male ,Small RNA ,Chromatography ,Sequence Analysis, RNA ,Ovary ,RNA ,Genes, Insect ,Ribosomal RNA ,Argonaute ,Biology ,Chromatography, Ion Exchange ,General Biochemistry, Genetics and Molecular Biology ,Deep sequencing ,Mice, Inbred C57BL ,RNA silencing ,HEK293 Cells ,Testis ,Animals ,Humans ,RNA, Small Untranslated ,Gene silencing ,Drosophila ,Female ,Molecular Biology ,Ribonucleoprotein - Abstract
The discovery of the small regulatory RNAs has changed our vision of cellular regulations. Indeed, when loaded on Argonaute proteins they form ribonucleoprotein complexes (RNPs) that target complementary sequences to achieve widespread silencing mechanisms conserved in most eukaryotes. The recent development of deep sequencing approaches highly contributed to their detection. Small RNA isolation from cells and/or tissues remains a crucial stage to generate robust and relevant sequencing data. In 2006, a novel strategy based on anion-exchange chromatography has been proposed as an alternative to the standard size-isolation purification procedure. Using bioinformatic comparative analysis, we here demonstrate that anion-exchange chromatographic RNP purification prior to small RNA extraction unbiasedly enriches datasets in bona fide reads (small regulatory RNA sequences) and depletes endogenous contaminants (ribosomal RNAs and degradation RNA products). The resulting increase in sequencing depth provides a major benefit to study rare populations. We then developed a fast and basic manual procedure to purify such small non-coding RNAs using anion-exchange chromatography at the bench. We validated the efficiency of this new method and used this strategy to purify small RNAs from various tissues and organisms. We moreover determined that our manual purification increases the output of the previously described anion-exchange chromatography procedure.
- Published
- 2014
9. MicroRNA-Dependent Transcriptional Silencing of Transposable Elements in Drosophila Follicle Cells
- Author
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Alain Pélisson, Bruno Mugat, Claudia Armenise, Vincent Serrano, Christine Brun, Blaise Li, David Van Vactor, Abdou Akkouche, Séverine Chambeyron, Tudor A. Fulga, Institut de génétique humaine (IGH), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), and Harvard Medical School [Boston] (HMS)
- Subjects
Cancer Research ,Small interfering RNA ,lcsh:QH426-470 ,Biology ,Ovarian Follicle ,RNA interference ,microRNA ,Genetics ,Gene silencing ,Animals ,Drosophila Proteins ,Gene Silencing ,RNA, Small Interfering ,Molecular Biology ,Genetics (clinical) ,Ecology, Evolution, Behavior and Systematics ,Drosha ,Regulation of gene expression ,[SDV.GEN]Life Sciences [q-bio]/Genetics ,RNA ,MicroRNAs ,lcsh:Genetics ,Gene Expression Regulation ,DNA Transposable Elements ,Drosophila ,Female ,RNA Interference ,Drosophila Protein ,Research Article - Abstract
RNA interference-related silencing mechanisms concern very diverse and distinct biological processes, from gene regulation (via the microRNA pathway) to defense against molecular parasites (through the small interfering RNA and the Piwi-interacting RNA pathways). Small non-coding RNAs serve as specificity factors that guide effector proteins to ribonucleic acid targets via base-pairing interactions, to achieve transcriptional or post-transcriptional regulation. Because of the small sequence complementarity required for microRNA-dependent post-transcriptional regulation, thousands of microRNA (miRNA) putative targets have been annotated in Drosophila. In Drosophila somatic ovarian cells, genomic parasites, such as transposable elements (TEs), are transcriptionally repressed by chromatin changes induced by Piwi-interacting RNAs (piRNAs) that prevent them from invading the germinal genome. Here we show, for the first time, that a functional miRNA pathway is required for the piRNA-mediated transcriptional silencing of TEs in this tissue. Global miRNA depletion, caused by tissue- and stage-specific knock down of drosha (involved in miRNA biogenesis), AGO1 or gawky (both responsible for miRNA activity), resulted in loss of TE-derived piRNAs and chromatin-mediated transcriptional de-silencing of TEs. This specific TE de-repression was also observed upon individual titration (by expression of the complementary miRNA sponge) of two miRNAs (miR-14 and miR-34) as well as in a miR-14 loss-of-function mutant background. Interestingly, the miRNA defects differentially affected TE- and 3' UTR-derived piRNAs. To our knowledge, this is the first indication of possible differences in the biogenesis or stability of TE- and 3' UTR-derived piRNAs. This work is one of the examples of detectable phenotypes caused by loss of individual miRNAs in Drosophila and the first genetic evidence that miRNAs have a role in the maintenance of genome stability via piRNA-mediated TE repression., Author Summary The fine-tuning of gene expression required for the normal development of multicellular organisms involves small RNAs that are called microRNAs (miRNAs). MiRNAs can reduce the stability or the activity of the many cellular messenger RNAs that contain miRNA complementary sequences. In animal gonads, the harmful expression and proliferation of genomic parasites, such as transposable elements, is prevented by a similar, sequence homology-based silencing mechanism that involves a different class of small RNAs, the Piwi-interacting RNAs (piRNAs). We report here that, in Drosophila somatic ovarian tissues, two miRNAs, miR-14 and miR-34, are required for the accumulation of piRNAs that prevent the expression of transposable elements and, probably, the subsequent invasion of the germinal genome. On the other hand, we found that other sources of piRNA production, such as the 3' end of genes, are miRNA-independent, suggesting the existence of variations in the piRNA biogenesis pathways depending on the piRNA genomic origin. Our results therefore highlight a novel miRNA function in the maintenance of genome stability through piRNA-mediated TE repression.
- Published
- 2015
10. Evidence for a piwi-Dependent RNA Silencing of the gypsy Endogenous Retrovirus by the Drosophila melanogaster flamenco Gene
- Author
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Alain Bucheton, Alain Pélisson, Geneviève Payen-Groschêne, and Emeline Sarot
- Subjects
Untranslated region ,Endogenous retrovirus ,Piwi-interacting RNA ,Genes, Insect ,Animals, Genetically Modified ,RNA interference ,Genes, Regulator ,Genetics ,Animals ,Gene Silencing ,RNA, Small Interfering ,Gene ,RDE-1 ,Base Sequence ,biology ,Endogenous Retroviruses ,Ovary ,biology.organism_classification ,RNA silencing ,Lac Operon ,Larva ,Mutation ,Drosophila ,Female ,RNA Interference ,Drosophila melanogaster ,5' Untranslated Regions ,Research Article - Abstract
In Drosophila melanogaster, the endogenous retrovirus gypsy is repressed by the functional alleles (restrictive) of an as-yet-uncloned heterochromatic gene called flamenco. Using gypsy-lacZ transcriptional fusions, we show here that this repression takes place not only in the follicle cells of restrictive ovaries, as was previously observed, but also in restrictive larval female gonads. Analyses of the role of gypsy cis-regulatory sequences in the control of gypsy expression are also presented. They rule out the hypothesis that gypsy would contain a single binding region for a putative Flamenco repressor. Indeed, the ovarian expression of a chimeric yp3-lacZ construct was shown to become sensitive to the Flamenco regulation when any of three different 5′-UTR gypsy sequences (ranging from 59 to 647 nucleotides) was incorporated into the heterologous yp3-lacZ transcript. The piwi mutation, which is known to affect RNA-mediated homology-dependent transgene silencing, was also shown to impede the repression of gypsy in restrictive female gonads. Finally, a RNA-silencing model is also supported by the finding in ovaries of short RNAs (25–27 nucleotides long) homologous to sequences from within the gypsy 5′-UTR.
- Published
- 2004
11. A Novel Double-stranded RNA-binding Protein, Disco Interacting Protein 1 (DIP1), Contributes to Cell Fate Decisions during Drosophila Development
- Author
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Alain Pélisson, Ana Regina Campos, Xiao Li Zhao, Dorothy Desousa, Bijan K. Dey, Peter Pelka, Alain Bucheton, Mahua Mukhopadhyay, and Valérie Robert
- Subjects
Molecular Sequence Data ,Biology ,Biochemistry ,Double-stranded RNA binding ,Transcription (biology) ,Gene expression ,Animals ,Drosophila Proteins ,Amino Acid Sequence ,Cloning, Molecular ,Molecular Biology ,Gene ,Cell Nucleus ,Zinc finger ,Binding Sites ,Gene Expression Regulation, Developmental ,Nuclear Proteins ,RNA-Binding Proteins ,RNA ,Cell Biology ,Molecular biology ,RNA silencing ,RNA splicing ,Drosophila ,Cell Division ,Transcription Factors - Abstract
We report the identification of the Disco Interacting Protein 1 (DIP1) gene isolated in a yeast interaction trap screen using the zinc finger protein disconnected (disco) as a bait. DIP1 encodes a protein containing two double-stranded RNA binding domains (dsRBD). Consistent with the presence of dsRBD, DIP1 binds dsRNA or structured RNAs in Northwestern assays. DIP1 is found in nuclear subdomains resembling speckles known to accumulate transcription and splicing factors. In early embryos, nuclear localization of DIP1 protein coincides with the onset of zygotic gene expression. Later in development DIP1 expression is decreased in dividing cells in different tissues. Overexpression of DIP1 in the eye-antennal imaginal disc, early in embryonic and larval development, causes the formation of supernumerary structures in the head capsule. A role for DIP1 in epigenetic mechanisms that lead to the establishment and/or maintenance of cell fate specification is discussed.
- Published
- 2003
12. Comparative and Functional Studies of Drosophila Species Invasion by the gypsy Endogenous Retrovirus
- Author
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Alain Bucheton, Christophe Terzian, Alain Pélisson, and Lucine Mejlumian
- Subjects
Genetics ,Base Sequence ,Endogenous Retroviruses ,Molecular Sequence Data ,Gene Products, env ,Sequence Homology ,Endogenous retrovirus ,DNA ,Biology ,biology.organism_classification ,Genome ,Evolution, Molecular ,Drosophila melanogaster ,Phylogenetics ,Horizontal gene transfer ,Melanogaster ,Animals ,Drosophila ,Amino Acid Sequence ,Gene ,Phylogeny ,Research Article - Abstract
Gypsy is an endogenous retrovirus of Drosophila melanogaster. Phylogenetic studies suggest that occasional horizontal transfer events of gypsy occur between Drosophila species. gypsy possesses infective properties associated with the products of the envelope gene that might be at the origin of these interspecies transfers. We report here the existence of DNA sequences putatively encoding full-length Env proteins in the genomes of Drosophila species other than D. melanogaster, suggesting that potentially infective gypsy copies able to spread between sexually isolated species can occur. The ability of gypsy to invade the genome of a new species is conditioned by its capacity to be expressed in the naive genome. The genetic basis for the regulation of gypsy activity in D. melanogaster is now well known, and it has been assigned to an X-linked gene called flamenco. We established an experimental simulation of the invasion of the D. melanogaster genome by gypsy elements derived from other Drosophila species, which demonstrates that these non-D. melanogaster gypsy elements escape the repression exerted by the D. melanogaster flamenco gene.
- Published
- 2002
13. [Untitled]
- Author
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Alain Pélisson, Fabienne Chalvet, A. I. Kim, Laure Teysset, Alain Bucheton, Christophe Terzian, and Nicole Prud'Homme
- Subjects
Genetics ,biology ,Phylogenetic tree ,fungi ,Endogenous retrovirus ,Plant Science ,General Medicine ,biology.organism_classification ,Genome ,Genetic load ,Retrovirus ,Phylogenetics ,Insect Science ,Animal Science and Zoology ,Drosophila melanogaster ,Gene - Abstract
The gypsy element of Drosophila melanogaster is the first retrovirus identified so far in invertebrates. According to phylogenetic data, gypsy belongs to the same group as the Ty3 class of LTR-retrotransposons, which suggests that retroviruses evolved from this kind of retroelements before the radiation of vertebrates. There are other invertebrate retroelements that are also likely to be endogenous retroviruses because they share with gypsy some structural and functional retroviral-like characteristics. Gypsy is controlled by a Drosophila gene called flamenco, the restrictive alleles of which maintain the retrovirus in a repressed state. In permissive strains, functional gypsy elements transpose at high frequency and produce infective particles. Defective gypsy proviruses located in pericentromeric heterochromatin of all strains seem to be very old components of the genome of Drosophila melanogaster, which indicates that gypsy invaded this species, or an ancestor, a long time ago. At that time, Drosophila melanogaster presumably contained permissive alleles of the flamenco gene. One can imagine that the species survived to the increase of genetic load caused by the retroviral invasion because restrictive alleles of flamenco were selected. The characterization of a retrovirus in Drosophila, one of the most advanced model organisms for molecular genetics, provides us with an exceptional clue to study how a species can resist a retroviral invasion.
- Published
- 1997
14. piRNA mediated transgenerational inheritance of an acquired trait
- Author
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Vincent Serrano, Alain Pélisson, Séverine Chambeyron, Bruno Mugat, Christine Brun, Claudia Armenise, Thomas Grentzinger, Institut de génétique humaine (IGH), and Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
Transposable element ,Male ,endocrine system ,Aging ,Euchromatin ,Transcription, Genetic ,Heterochromatin ,Piwi-interacting RNA ,Biology ,Germline ,03 medical and health sciences ,0302 clinical medicine ,Quantitative Trait, Heritable ,Genetics ,RNA Precursors ,Gene silencing ,Animals ,Epigenetics ,Gene Silencing ,RNA, Small Interfering ,Genetics (clinical) ,ComputingMilieux_MISCELLANEOUS ,030304 developmental biology ,0303 health sciences ,[SDV.GEN]Life Sciences [q-bio]/Genetics ,urogenital system ,Research ,Chromatin ,DNA Transposable Elements ,Drosophila ,Female ,030217 neurology & neurosurgery - Abstract
The maintenance of genome integrity is an essential trait to the successful transmission of genetic information. In animal germ cells, piRNAs guide PIWI proteins to silence transposable elements (TEs) in order to maintain genome integrity. In insects, most TE silencing in the germline is achieved by secondary piRNAs that are produced by a feed-forward loop (the ping-pong cycle), which requires the piRNA-directed cleavage of two types of RNAs: mRNAs of functional euchromatic TEs and heterochromatic transcripts that contain defective TE sequences. The first cleavage that initiates such an amplification loop remains poorly understood. Taking advantage of the existence of strains that are devoid of functional copies of the LINE-like I-element, we report here that in such Drosophila ovaries, the initiation of a ping-pong cycle is exclusively achieved by secondary I-element piRNAs that are produced in the ovary and deposited in the embryonic germline. This unusual secondary piRNA biogenesis, detected in the absence of functional I-element copies, results from the processing of sense and antisense transcripts of several different defective I-element. Once acquired, for instance after ancestor aging, this capacity to produce heterochromatic-only secondary piRNAs is partially transmitted through generations via maternal piRNAs. Furthermore, such piRNAs acting as ping-pong initiators in a chromatin-independent manner confer to the progeny a high capacity to repress the I-element mobility. Our study explains, at the molecular level, the basis for epigenetic memory of maternal immunity that protects females from hybrid dysgenesis caused by transposition of paternally inherited functional I-element.
- Published
- 2012
15. Gypsy transposition correlates with the production of a retroviral envelope-like protein under the tissue-specific control of the Drosophila flamenco gene
- Author
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Alain Bucheton, Victor G. Corces, P.A. Smith, Alain Pélisson, S.U. Song, and Nicole Prud'Homme
- Subjects
Male ,Transposable element ,Transcription, Genetic ,Somatic cell ,RNA Splicing ,Recombinant Fusion Proteins ,Molecular Sequence Data ,Genes, Insect ,Retrotransposon ,Genes, env ,Polymerase Chain Reaction ,General Biochemistry, Genetics and Molecular Biology ,Germline ,Open Reading Frames ,Viral Envelope Proteins ,Genes, Reporter ,Animals ,Amino Acid Sequence ,RNA, Messenger ,Molecular Biology ,Gene ,In Situ Hybridization ,Subgenomic mRNA ,Gene Rearrangement ,Genetics ,Sex Characteristics ,Base Sequence ,General Immunology and Microbiology ,biology ,General Neuroscience ,Ovary ,RNA ,biology.organism_classification ,Germ Cells ,Retroviridae ,Gene Expression Regulation ,DNA Transposable Elements ,Drosophila ,Female ,Drosophila melanogaster ,Research Article - Abstract
Gypsy displays striking similarities to vertebrate retroviruses, including the presence of a yet uncharacterized additional open reading frame (ORF3) and the recent evidence for infectivity. It is mobilized with high frequency in the germline of the progeny of females homozygous for the flamenco permissive mutation. We report the characterization of a gypsy subgenomic ORF3 RNA encoding typical retroviral envelope proteins. In females, env expression is strongly repressed by one copy of the non-permissive allele of flamenco. A less dramatic reduction in the accumulation of other transcripts and retrotranscripts is also observed. These effects correlate well with the inhibition of gypsy transposition in the progeny of these females, and are therefore likely to be responsible for this phenomenon. The effects of flamenco on gypsy expression are apparently restricted to the somatic follicle cells that surround the maternal germline. Moreover, permissive follicle cells display a typically polarized distribution of gypsy RNAs and envelope proteins, both being mainly accumulated at the apical pole, close to the oocyte. We propose a model suggesting that gypsy germinal transposition might occur only in individuals that have maternally inherited enveloped gypsy particles due to infection of the maternal germline by the soma.
- Published
- 1994
16. Retroviruses in invertebrates: the gypsyretrotransposon is apparently an infectious retrovirus of Drosophilamelanogaster
- Author
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Alain Bucheton, N Purd'homme, Alain Pélisson, Pedro Santamaria, A. I. Kim, and Christophe Terzian
- Subjects
Transposable element ,Microinjections ,viruses ,Endogenous retrovirus ,Insect Viruses ,Retrotransposon ,Chromosomes ,Salivary Glands ,Retrovirus ,Animals ,In Situ Hybridization ,Ovum ,Genetics ,Multidisciplinary ,biology ,fungi ,biology.organism_classification ,Long terminal repeat ,Reverse transcriptase ,Drosophila melanogaster ,Retroviridae ,Mutagenesis ,Horizontal gene transfer ,DNA Transposable Elements ,Female ,Infertility, Female ,Research Article ,Retroviridae Infections - Abstract
Retroviruses are commonly considered to be restricted to vertebrates. However, the genome of many eukaryotes contains mobile sequences known as retrotransposons with long terminal repeats (LTR retrotransposons) or viral retrotransposons, showing similarities with integrated proviruses of retroviruses, such as Ty elements in Saccharomyces cerevisiae, copia-like elements in Drosophila, and endogenous proviruses in vertebrates. The gypsy element of Drosophila melanogaster has LTRs and contains three open reading frames, one of which encodes potential products similar to gag-specific protease, reverse transcriptase, and endonuclease. It is more similar to typical retroviruses than to LTR retrotransposons. We report here experiments showing that gypsy can be transmitted by microinjecting egg plasma from embryos of a strain containing actively transposing gypsy elements into embryos of a strain originally devoid of transposing elements. Horizontal transfer is also observed when individuals of the "empty" stock are raised on medium containing ground pupae of the stock possessing transposing elements. These results suggest that gypsy is an infectious retrovirus and provide evidence that retroviruses also occur in invertebrates.
- Published
- 1994
17. Properties of transgenic strains ofDrosophila melanogastercontaining I transposable elements fromDrosophila teissieri
- Author
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Chantal Vaury, Alain Bucheton, Alain Pélisson, and Pierre Abad
- Subjects
Male ,Transposable element ,Genetics ,Genome ,biology ,Transgene ,RNA ,Retrotransposon ,General Medicine ,biology.organism_classification ,Animals, Genetically Modified ,Transformation (genetics) ,Drosophila melanogaster ,Species Specificity ,Drosophilidae ,DNA Transposable Elements ,Animals ,Hybridization, Genetic ,Drosophila ,Female ,Drosophila (subgenus) ,Infertility, Female - Abstract
SummaryI factors are transposable elements ofDrosophila melanogaster similarto mammalian LINEs, that transpose by reverse transcription of an RNA intermediate and are responsible for the I–R system of hybrid dysgenesis. There are two categories of strains in this species: inducer, that contain about 15 I elements at the various sites on chromosomal arms, and reactive, that lack active I factors. I elements occur in variousDrosophilaspecies. Potentially functional I factors fromDrosophila teissierican transpose when introduced by P-element-mediated transformation in a reactive strain ofDrosophila melanogaster. We have studied the properties ofDrosophila melanogasterstrains into which such an I factor fromDrosophila teissieri, namedItei, was introduced. Typical hybrid dysgenesis is produced when males carryingIteiare crossed with reactive females. However, more than one copy of the element seems necessary to produce dysgenic traits, whereas only one I factor ofDrosophila melanogasterseems to be sufficient. The copy number ofIteiin transformed lines maintained by endogamous crosses increases rapidly and stabilizes at values similar to those observed in inducer strains. AsDrosophila teissiericontains much fewer copies than theDrosophila melanogasterstrains, this suggests that the copy number of I elements is not simply regulated by sequences present in the element itself.
- Published
- 1993
18. Maternal mRNA deadenylation and decay by the piRNA pathway in the early Drosophila embryo
- Author
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Catherine Papin, Christel Rouget, Alain Pélisson, Eric C. Lai, Anne Cecile Meunier, Martine Simonelig, Nicolas Robine, Bénédicte Franco, Anthony Boureux, Institut de génétique humaine (IGH), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Centre de recherche en Biologie Cellulaire (CRBM), and Université Montpellier 2 - Sciences et Techniques (UM2)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Université Montpellier 1 (UM1)
- Subjects
Cytoplasm ,Embryo, Nonmammalian ,Zygote ,RNA Stability ,Germline ,0302 clinical medicine ,Peptide Initiation Factors ,Drosophila Proteins ,RNA, Small Interfering ,3' Untranslated Regions ,ComputingMilieux_MISCELLANEOUS ,Genetics ,Regulation of gene expression ,0303 health sciences ,Multidisciplinary ,Gene Expression Regulation, Developmental ,RNA-Binding Proteins ,MRNA stabilization ,Argonaute ,ARN ,Drosophila melanogaster ,Argonaute Proteins ,Drosophila ,Female ,Smaug ,endocrine system ,Piwi-interacting RNA ,Mothers ,Embryon animal ,Biology ,Polyadenylation ,03 medical and health sciences ,Ribonucleases ,Biologie animale ,microRNA ,Animals ,L50 - Physiologie et biochimie animales ,RNA, Messenger ,030304 developmental biology ,[SDV.GEN]Life Sciences [q-bio]/Genetics ,urogenital system ,RNA ,Développement embryonnaire ,Repressor Proteins ,L52 - Physiologie animale : croissance et développement ,DNA Transposable Elements ,030217 neurology & neurosurgery - Abstract
Small RNAs of the piRNA (Piwi-associated RNA) class have various functions in the germline — repressing transposable elements, maintaining germline stem cells and promoting genome stability. Rouget et al. have now uncovered a function for piRNAs outside the germline, in the fruit fly embryo. Specifically, piRNAs that are complementary to a sequence in the 3′-untranslated region of an mRNA for the embryonic posterior morphogen Nanos facilitate adenylation of the mRNA and its subsequent decay. Without piRNAs, Nanos accumulates and developmental defects result. Piwi-associated RNAs (piRNAs) are small RNAs with several functions in the germline, such as repressing transposable elements and helping to maintain germline stem cells. Now, a function for piRNAs has been discovered outside the germline, in the fruitfly embryo. Specifically, piRNAs are required for the decay of the messenger RNA encoding the posterior morphogen Nanos. When piRNA-induced regulation is impaired, this mRNA is stabilized and developmental defects ensue. Piwi-associated RNAs (piRNAs), a specific class of 24- to 30-nucleotide-long RNAs produced by the Piwi-type of Argonaute proteins, have a specific germline function in repressing transposable elements. This repression is thought to involve heterochromatin formation and transcriptional and post-transcriptional silencing1,2,3,4,5,6. The piRNA pathway has other essential functions in germline stem cell maintenance7 and in maintaining germline DNA integrity8,9,10. Here we uncover an unexpected function of the piRNA pathway in the decay of maternal messenger RNAs and in translational repression in the early embryo. A subset of maternal mRNAs is degraded in the embryo at the maternal-to-zygotic transition. In Drosophila, maternal mRNA degradation depends on the RNA-binding protein Smaug and the deadenylase CCR411,12,13, as well as the zygotic expression of a microRNA cluster14. Using mRNA encoding the embryonic posterior morphogen Nanos (Nos) as a paradigm to study maternal mRNA decay, we found that CCR4-mediated deadenylation of nos depends on components of the piRNA pathway including piRNAs complementary to a specific region in the nos 3′ untranslated region. Reduced deadenylation when piRNA-induced regulation is impaired correlates with nos mRNA stabilization and translational derepression in the embryo, resulting in head development defects. Aubergine, one of the Argonaute proteins in the piRNA pathway, is present in a complex with Smaug, CCR4, nos mRNA and piRNAs that target the nos 3′ untranslated region, in the bulk of the embryo. We propose that piRNAs and their associated proteins act together with Smaug to recruit the CCR4 deadenylation complex to specific mRNAs, thus promoting their decay. Because the piRNAs involved in this regulation are produced from transposable elements, this identifies a direct developmental function for transposable elements in the regulation of gene expression.
- Published
- 2010
19. Small RNA-mediated control of retrotrotransposons in Drosophila
- Author
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Alain Pélisson, Vincent Serrano, Séverine Chambeyron, Alain Bucheton, and Christine Brun
- Subjects
lcsh:Immunologic diseases. Allergy ,Genetics ,endocrine system ,Small RNA ,urogenital system ,Somatic cell ,fungi ,Piwi-interacting RNA ,Retrotransposon ,Biology ,Germline ,Infectious Diseases ,Protein structure ,Virology ,Oral Presentation ,Epigenetics ,lcsh:RC581-607 ,Biogenesis - Abstract
In the Drosophila ovary, the I-element (a NLR retrotransposon) and gypsy are both controlled by piRNAs (small RNAs associated with Piwi-like proteins); but there are important variations on this common theme, according to the cell lineage where it operates: the germline (for the I-element) versus the ovarian somatic cells (for gypsy). We are taking advantage of these differences to study the piRNA biogenesis, the epigenetic effects of the maternal transmission of piRNAs and the mechanism of piRNA-mediated regulation.
- Published
- 2009
20. When drosophila meets retrovirology: The gypsy case
- Author
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Alain Bucheton, Alain Pélisson, Christophe Terzian, Rétrovirus et Pathologie Comparée (RPC), Institut National de la Recherche Agronomique (INRA)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Ecole Nationale Vétérinaire de Lyon (ENVL), Institut de génétique humaine (IGH), and Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
media_common.quotation_subject ,[SDV]Life Sciences [q-bio] ,Endogenous retrovirus ,Insect ,CLEAVAGE SITE ,Env Protein ,Genome ,03 medical and health sciences ,0302 clinical medicine ,NUCLEOTIDE-SEQUENCE ,INFECTIOUS RETROVIRUS ,Drosophila ,RETROTRANSPOSON ,ENVELOPE FUSION PROTEIN ,030304 developmental biology ,media_common ,FLAMENCO GENE ,Genetics ,0303 health sciences ,MELANOGASTER ,biology ,ENDOGENOUS RETROVIRUS ,TRANSPOSABLE GENETIC ELEMENT ,Retrovirology ,biology.organism_classification ,EVOLUTION ,3. Good health ,Drosophila melanogaster ,030217 neurology & neurosurgery - Abstract
International audience; Insect endogenous retroviruses (IERVs) are present in the genome of several species. It was shown that gypsy is an active endogenous retrovirus in Drosophila melanogaster, which could be transmitted to individuals fed with gypsy-containing extracts. Moreover, gypsy replication depends on cell-cell transfer. Here, we review recent findings which help to elucidate the structure and the role of gypsy Env protein during gypsy horizontal and vertical transfers.
- Published
- 2009
21. piRNA-mediated nuclear accumulation of retrotransposon transcripts in the Drosophila female germline
- Author
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Dorsaf Laouini, Alain Bucheton, Alain Pélisson, Christine Brun, Geneviève Payen-Groschêne, Séverine Chambeyron, Anna Popkova, Institut de génétique humaine (IGH), and Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
Transposable element ,endocrine system ,Retroelements ,Transcription, Genetic ,Euchromatin ,Piwi-interacting RNA ,Retrotransposon ,Biology ,03 medical and health sciences ,Animals ,Drosophila Proteins ,RasiRNA ,Gene Silencing ,RNA, Small Interfering ,Psychological repression ,ComputingMilieux_MISCELLANEOUS ,Ovum ,030304 developmental biology ,Cell Nucleus ,Genetics ,0303 health sciences ,[SDV.GEN]Life Sciences [q-bio]/Genetics ,Multidisciplinary ,urogenital system ,030302 biochemistry & molecular biology ,RNA ,Biological Sciences ,RNA silencing ,Drosophila melanogaster ,[SDV.GEN.GH]Life Sciences [q-bio]/Genetics/Human genetics ,Female - Abstract
Germline silencing of transposable elements is essential for the maintenance of genome integrity. Recent results indicate that this repression is largely achieved through a RNA silencing pathway that involves Piwi-interacting RNAs (piRNAs). However the repressive mechanisms are not well understood. To address this question, we used the possibility to disrupt the repression of the Drosophila I element retrotransposon by hybrid dysgenesis. We show here that the repression of the functional I elements that are located in euchromatin requires proteins of the piRNA pathway, and that the amount of ovarian I element piRNAs correlates with the strength of the repression in the female germline. Antisense RNAs, which are likely used to produce antisense piRNAs, are transcribed by heterochromatic defective I elements, but efficient production of these antisense small RNAs requires the presence in the genome of euchromatic functional I elements. Finally, we demonstrate that the piRNA-induced silencing of the functional I elements is at least partially posttranscriptional. In a repressive background, these elements are still transcribed, but some of their sense transcripts are kept in nurse cell nuclear foci together with those of the Doc retrotransposon. In the absence of I element piRNAs, either in dysgenic females or in mutants of the piRNA silencing pathway, sense I element transcripts are transported toward the oocyte where retrotransposition occurs. Our results indicate that piRNAs are involved in a posttranscriptional gene-silencing mechanism resulting in RNA nuclear accumulation.
- Published
- 2008
22. The flamenco locus controls the gypsy and ZAM retroviruses and is required for Drosophila oogenesis
- Author
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Alain Pélisson, Jennifer Kinder, Ana Regina Campos, Maryvonne Mével-Ninio, Alain Bucheton, Institut de génétique humaine (IGH), and Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
Transposable element ,Heterochromatin ,Endogenous retrovirus ,Locus (genetics) ,Genes, Insect ,Biology ,Investigations ,Animals, Genetically Modified ,03 medical and health sciences ,Oogenesis ,Transcription (biology) ,Genetics ,Coding region ,Animals ,Drosophila Proteins ,Allele ,RNA, Small Interfering ,ComputingMilieux_MISCELLANEOUS ,030304 developmental biology ,DNA Primers ,0303 health sciences ,[SDV.GEN]Life Sciences [q-bio]/Genetics ,Base Sequence ,030302 biochemistry & molecular biology ,Genetic Complementation Test ,Gene Expression Regulation, Developmental ,Cadherins ,RNA silencing ,Mutagenesis, Insertional ,Drosophila melanogaster ,Retroviridae ,Female ,Transcription Factors - Abstract
In Drosophila, the as yet uncloned heterochromatic locus flamenco (flam) controls mobilization of the endogenous retrovirus gypsy through the repeat-associated small interfering (rasi) RNA silencing pathway. Restrictive alleles (flamR) downregulate accumulation of gypsy transcripts in the somatic follicular epithelium of the ovary. In contrast, permissive alleles (flamP) are unable to repress gypsy. DIP1, the closest transcription unit to a flam-insertional mutation, was considered as a good candidate to be a gypsy regulator, since it encodes a dsRNA-binding protein. To further characterize the locus we analyzed P-induced flam mutants and generated new mutations by transposon mobilization. We show that flam is required somatically for morphogenesis of the follicular epithelium, the tissue where gypsy is repressed. This developmental activity is necessary to control gypsy and another retroelement, ZAM. We also show that flam is not DIP1, as none of the new permissive mutants affect the DIP1 coding sequence. In addition, two deletions removing DIP1 coding sequences do not affect any of the flamenco functions. Our results suggest that flamenco extends proximally to DIP1, spanning >130 kb of transposon-rich heterochromatin. We propose a model explaining the multiple functions of this large heterochromatic locus.
- Published
- 2007
23. Restrictive Flamenco Alleles Are Maintained in Drosophila melanogaster Population Cages, Despite the Absence of Their Endogenous Gypsy Retroviral Targets
- Author
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Christophe Terzian, Alain Pélisson, Geneviève Payen-Groschêne, Alain Bucheton, Institut de génétique humaine (IGH), and Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
Male ,Linkage disequilibrium ,BALANCING SELECTION ,Population ,Endogenous retrovirus ,Genes, Insect ,Genes, Recessive ,Locus (genetics) ,Biology ,Balancing selection ,NATURAL AND EXPERIMENTAL POPULATIONS ,03 medical and health sciences ,Proviruses ,Genes, Reporter ,Genetics ,Animals ,Selection, Genetic ,Allele ,education ,Molecular Biology ,Gene ,Alleles ,Ecology, Evolution, Behavior and Systematics ,030304 developmental biology ,0303 health sciences ,education.field_of_study ,[SDV.GEN]Life Sciences [q-bio]/Genetics ,Polymorphism, Genetic ,Endogenous Retroviruses ,030302 biochemistry & molecular biology ,Recombinant Proteins ,Genetic load ,ANTI-GYPSY RESISTANCE COST ,[SDV.GEN.GH]Life Sciences [q-bio]/Genetics/Human genetics ,FLAMENCO ,Female ,DROSOPHILA MELANOGASTER ,LINKAGE DESEQUILIBRIUM ,Transcription Factors - Abstract
International audience; The flamenco (flam) locus, located at 20A1-3 in the centromeric heterochromatin of the Drosophila melanogaster X chromosome, is a major regulator of the gypsy/mdg4 endogenous retrovirus. In restrictive strains, functional flam alleles maintain gypsy proviruses in a repressed state. By contrast, in permissive strains, proviral amplification results from infection of the female germ line and subsequent insertions into the chromosomes of the progeny. A restrictive/permissive polymorphism prevails in natural and laboratory populations. This polymorphism was assumed to be maintained by the interplay of opposite selective forces; on one hand, the increase of genetic load caused by proviral insertions would favor restrictive flam alleles because they make flies resistant to these gypsy replicative transpositions and, on the other, a hypothetical resistance cost would select against such alleles in the absence of the retrovirus. However, the population cage data presented in this paper do not fit with this simple resistance cost hypothesis because restrictive alleles were not eliminated in the absence of functional gypsy proviruses; on the contrary, using 2 independent flam allelic pairs, the restrictive frequency rose to about 90% in every experimental population, whatever the pair of alleles and the allelic proportions in the initial inoculum. These data suggest that the flam polymorphism is maintained by some strong balancing selection, which would act either on flam itself, independently of the deleterious effect of gypsy, or on a hypothetical flanking gene, in linkage disequilibrium with flam. Alternatively, restrictive flam alleles might also be resistant to some other retroelements that would be still present in the cage populations, causing a positive selection for these alleles. Whatever selective forces that maintain high levels of restrictive alleles independently of gypsy, this unknown mechanism can set up an interesting kind of antiviral innate immunity, at the population level.
- Published
- 2007
24. A Novel Repeat-Associated Small Interfering RNA-Mediated Silencing Pathway Downregulates Complementary Sense gypsy Transcripts in Somatic Cells of the Drosophila Ovary▿
- Author
-
Alain Pélisson, Geneviève Payen-Groschêne, Alain Bucheton, and Emeline Sarot
- Subjects
Ribonuclease III ,Small interfering RNA ,RNA-induced silencing complex ,Immunology ,Piwi-interacting RNA ,Cellular Response to Infection ,Down-Regulation ,Biology ,Virus Replication ,Microbiology ,03 medical and health sciences ,0302 clinical medicine ,RNA interference ,Virology ,RasiRNA ,Animals ,Drosophila Proteins ,RNA-Induced Silencing Complex ,3' Flanking Region ,RNA, Messenger ,RNA, Small Interfering ,030304 developmental biology ,Genetics ,0303 health sciences ,Endogenous Retroviruses ,Ovary ,RNA ,Proteins ,Argonaute ,RNA silencing ,Insect Science ,Argonaute Proteins ,RNA, Viral ,Drosophila ,Female ,RNA Interference ,030217 neurology & neurosurgery ,RNA Helicases - Abstract
Replication of the gypsy endogenous retrovirus involves contamination of the female germ line by adjacent somatic tissues. This is prevented by flam , an as-yet-uncloned heterochromatic pericentromeric locus, at the level of transcript accumulation in these somatic ovarian tissues. We tested the effect of a presumptive RNA silencing mechanism on the accumulation of RNAs produced by constructs containing various gypsy sequences and report that the efficiency of silencing is indeed correlated with the amount of complementary RNAs, 25 to 30 nucleotides in length, in the ovary. For instance, while these RNAs were found to display a three- to fivefold excess of the antisense strands, only the transcripts that contain the complementary sense gypsy sequences could be repressed, indicating that they are targeted at the RNA, not DNA, level. Their size and asymmetry in strand polarity are typical of the novel repeat-associated small interfering RNA (rasiRNA)-mediated pathway, recently suspected to prevent the deleterious expression of selfish DNA specifically in the germ line. Unlike microRNAs (but like rasiRNAs and, surprisingly, siRNAs as well), gypsy rasiRNAs are modified at the 3′ end. The rasiRNA-associated protein Piwi (but not Aub) is required for gypsy silencing, whereas Dicer-2 (which makes siRNAs) is not. In contrast, piwi , aub , and flam do not appear to affect somatic siRNA-mediated silencing. The amount of gypsy rasiRNAs is genetically determined by the flam locus in a provirus copy number-independent manner and is triggered in the somatic tissues by some pericentromeric provirus(es), which are thereby able to protect the germ line from retroviral invasion.
- Published
- 2006
25. Characterization of a nucleocapsid-like region and of two distinct primer tRNALys,2 binding sites in the endogenous retrovirus Gypsy
- Author
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Jean-Luc Darlix, Julien Depollier, Alain Pélisson, Roland Ivanyi-Nagy, Caroline Gabus, Alain Bucheton, Institut National de la Santé et de la Recherche Médicale (INSERM), École normale supérieure - Lyon (ENS Lyon), Institut de génétique humaine (IGH), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Larose, Catherine, and École normale supérieure de Lyon (ENS de Lyon)
- Subjects
DNA, Complementary ,viruses ,Molecular Sequence Data ,Endogenous retrovirus ,Gene Products, gag ,Retrotransposon ,RNA-binding protein ,Cell Line ,03 medical and health sciences ,Open Reading Frames ,Retrovirus ,Complementary DNA ,[SDV.BBM.GTP]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Genomics [q-bio.GN] ,Genetics ,Animals ,Amino Acid Sequence ,ComputingMilieux_MISCELLANEOUS ,030304 developmental biology ,Gammaretrovirus ,0303 health sciences ,Binding Sites ,biology ,030302 biochemistry & molecular biology ,Endogenous Retroviruses ,fungi ,RNA ,RNA-Binding Proteins ,Nucleocapsid Proteins ,biology.organism_classification ,[SDV.GEN.GH]Life Sciences [q-bio]/Genetics/Human genetics ,RNA, Transfer, Lys ,RNA, Viral ,[SDV.BBM.GTP] Life Sciences [q-bio]/Biochemistry, Molecular Biology/Genomics [q-bio.GN] ,Drosophila ,Drosophila melanogaster ,Peptides - Abstract
International audience; Mobile LTR-retroelements comprising retroviruses and LTR-retrotransposons form a large part of eukaryotic genomes. Their mode of replication and abundance favour the notion that they are major actors in eukaryote evolution. The Gypsy retroelement can spread in the germ line of the fruit fly Drosophila melanogaster via both env-independent and env-dependent processes. Thus, Gypsy is both an active retrotransposon and an infectious retrovirus resembling the gammaretrovirus MuLV. However, unlike gammaretroviruses, the Gypsy Gag structural precursor is not processed into Matrix, Capsid and Nucleocapsid (NC) proteins. In contrast, it has features in common with Gag of the ancient yeast TY1 retroelement. These characteristics of Gypsy make it a very interesting model to study replication of a retroelement at the frontier between ancient retrotransposons and retroviruses. We investigated Gypsy replication using an in vitro model system and transfection of insect cells. Results show that an unstructured domain of Gypsy Gag has all the properties of a retroviral NC. This NC-like peptide forms ribonucleoparticle-like complexes upon binding Gypsy RNA and directs the annealing of primer tRNALys,2 to two distinct primer binding sites (PBS) at the genome 5′ and 3′ ends. Only the 5′ PBS is indispensable for cDNA synthesis in vitro and in Drosophila cells.
- Published
- 2006
26. Drosophila germline invasion by the endogenous retrovirus gypsy: involvement of the viral env gene
- Author
-
L. Mejlumian, V. Robert, Alain Bucheton, Alain Pélisson, and Christophe Terzian
- Subjects
Somatic cell ,viruses ,Mutant ,Endogenous retrovirus ,Endogeny ,Biology ,Virus Replication ,Biochemistry ,Genome ,Genes, env ,Germline ,Animals, Genetically Modified ,Evolution, Molecular ,Proviruses ,Animals ,Humans ,Molecular Biology ,Gene ,Genetics ,fungi ,Endogenous Retroviruses ,Virology ,Drosophila melanogaster ,Germ Cells ,Viral replication ,Insect Science - Abstract
The endogenous retrovirus gypsy is expressed at high levels in mutant flamenco female flies. Gypsy viral particles extracted from such flies can infect naive flamenco individuals raised in the presence of these extracts mixed into their food. This results in the integration of new proviruses into the germline genome. These proviruses can then increase their copy number by (1) expression in the flamenco female somatic cells, (2) transfer into the oocyte and (3) integration into the genome of the progeny. Surprisingly, unlike the infection observed in the feeding experiments, this strategy of endogenous proviral multiplication does not seem to involve the expression of the viral env gene.
- Published
- 2002
27. Characterization of the flamenco region of the Drosophila melanogaster genome
- Author
-
Alain Pélisson, Alain Bucheton, Nicole Prud'Homme, Valérie Robert, and A. I. Kim
- Subjects
Genetic Markers ,DNA, Complementary ,Molecular Sequence Data ,Restriction Mapping ,Genomics ,Biology ,Genome ,Polymerase Chain Reaction ,Restriction map ,Heterochromatin ,Genetics ,Animals ,Drosophila Proteins ,Genomic library ,Transgenes ,Cloning, Molecular ,Repeated sequence ,Gene ,Crosses, Genetic ,Gene Library ,Repetitive Sequences, Nucleic Acid ,Cell Nucleus ,Electrophoresis, Agar Gel ,Base Sequence ,Models, Genetic ,Genetic Complementation Test ,Chromosome Mapping ,DNA ,Blotting, Northern ,Cosmids ,Protein Structure, Tertiary ,genomic DNA ,Drosophila melanogaster ,Retroviridae ,Mutation ,Cosmid ,Mutagenesis, Site-Directed ,RNA ,Research Article ,Transcription Factors - Abstract
The flamenco gene, located at 20A1-3 in the β-heterochromatin of the Drosophila X chromosome, is a major regulator of the gypsy/mdg4 endogenous retrovirus. As a first step to characterize this gene, ∼100 kb of genomic DNA flanking a P-element-induced mutation of flamenco was isolated. This DNA is located in a sequencing gap of the Celera Genomics project, i.e., one of those parts of the genome in which the “shotgun” sequence could not be assembled, probably because it contains long stretches of repetitive DNA, especially on the proximal side of the P insertion point. Deficiency mapping indicated that sequences required for the normal flamenco function are located >130 kb proximal to the insertion site. The distal part of the cloned DNA does, nevertheless, contain several unique sequences, including at least four different transcription units. Dip1, the closest one to the P-element insertion point, might be a good candidate for a gypsy regulator, since it putatively encodes a nuclear protein containing two double-stranded RNA-binding domains. However, transgenes containing dip1 genomic DNA were not able to rescue flamenco mutant flies. The possible nature of the missing flamenco sequences is discussed.
- Published
- 2001
28. Retrotransposons and Retroviruses in Insect Genomes
- Author
-
Alain Pélisson, Alain Bucheton, and Christophe Terzian
- Subjects
Insect Genomes ,Evolutionary biology ,Retrotransposon ,Biology - Published
- 2000
29. Proviral amplification of the Gypsy endogenous retrovirus of Drosophila melanogaster involves env-independent invasion of the female germline
- Author
-
Laure Teysset, Fabienne Chalvet, Nicole Prud'Homme, Christophe Terzian, Pedro Santamaria, Alain Pélisson, and Alain Bucheton
- Subjects
Retroelements ,Replicative transposition ,Somatic cell ,Endogenous retrovirus ,Genes, Insect ,Biology ,Virus Replication ,Genes, env ,General Biochemistry, Genetics and Molecular Biology ,Germline ,Sex Factors ,Proviruses ,Gene duplication ,Animals ,Cell Lineage ,Molecular Biology ,Gene ,Derepression ,Crosses, Genetic ,Ovum ,Genetics ,General Immunology and Microbiology ,General Neuroscience ,Endogenous Retroviruses ,Gene Amplification ,biology.organism_classification ,Virology ,Drosophila melanogaster ,Female ,Research Article - Abstract
Gypsy is an infectious endogenous retrovirus of Drosophila melanogaster. The gypsy proviruses replicate very efficiently in the genome of the progeny of females homozygous for permissive alleles of the flamenco gene. This replicative transposition is correlated with derepression of gypsy expression, specifically in the somatic cells of the ovaries of the permissive mothers. The determinism of this amplification was studied further by making chimeric mothers containing different permissive/restrictive and somatic/germinal lineages. We show here that the derepression of active proviruses in the permissive soma is necessary and sufficient to induce proviral insertions in the progeny, even if the F1 flies derive from restrictive germ cells devoid of active proviruses. Therefore, gypsy endogenous multiplication results from the transfer of some gypsy-encoded genetic material from the soma towards the germen of the mother and its subsequent insertion into the chromosomes of the progeny. This transfer, however, is not likely to result from retroviral infection of the germline. Indeed, we also show here that the insertion of a tagged gypsy element, mutant for the env gene, occurs at high frequency, independently of the production of gypsy Env proteins by any transcomplementing helper. The possible role of the env gene for horizontal transfer to new hosts is discussed.
- Published
- 1999
30. RETROVIRUSES OF DROSOPHILA: THE GYPSY PARADIGM
- Author
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Alain Pélisson, Alain Bucheton, and Christophe Terzian
- Subjects
Evolutionary biology ,Biology ,Drosophila (subgenus) ,biology.organism_classification - Published
- 1999
31. Potentially active copies of the gypsy retroelement are confined to the Y chromosome of some strains of Drosophila melanogaster possibly as the result of the female-specific effect of the flamenco gene
- Author
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Nikolaj Junakovic, Carmen Di Franco, Alain Pélisson, Fabienne Chalvet, Alessandro Terrinoni, and Alain Bucheton
- Subjects
Male ,Genotype ,Retroelements ,Heterochromatin ,Restriction Mapping ,Endogenous retrovirus ,Genes, Insect ,Y chromosome ,Genome ,Genetics ,Animals ,Allele ,Molecular Biology ,Gene ,Ecology, Evolution, Behavior and Systematics ,Genomic organization ,genomic organisation ,Drosophila melanogaster ,retrovirus ,heterochromatin ,Female ,Retroviridae ,Y Chromosome ,biology ,Settore BIO/12 ,biology.organism_classification ,Genes ,Insect - Abstract
Gypsy is an endogenous retrovirus present in the genome of Drosophila melanogaster. This element is mobilized only in the progeny of females which contain active gypsy elements and which are homozygous for permissive alleles of a host gene called flamenco (flam). Some data strongly suggest that gypsy elements bearing a diagnostic HindIII site in the central region of the retrovirus body represent a subfamily that appears to be much more active than elements devoid of this site. We have taken advantage of this structural difference to assess by the Southern blotting technique the genomic distribution of active gypsy elements. In some of the laboratory Drosophila stocks tested, active gypsy elements were found to be restricted to the Y chromosome. Further analyses of 14 strains tested for the permissive vs. restrictive status of their flamenco alleles suggest that the presence of permissive alleles of flam in a stock tends to be associated with the confinement of active gypsy elements to the Y chromosome. This might be the result of the female-specific effect of flamenco on gypsy activity.
- Published
- 1998
32. The Doc transposable element in Drosophila melanogaster and Drosophila simulans: genomic distribution and transcription
- Author
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Alain Pélisson, Bernard Dastugue, Chantal Vaury, Marie-Christine Chaboissier, M. E. Drake, and O. Lajoinie
- Subjects
Transposable element ,Genetics ,Transcription, Genetic ,Restriction Mapping ,RNA ,Chromosome Mapping ,Gene Expression ,Plant Science ,General Medicine ,Biology ,biology.organism_classification ,Genome ,Human genetics ,Drosophila melanogaster ,Transcription (biology) ,Insect Science ,Melanogaster ,DNA Transposable Elements ,Animals ,Animal Science and Zoology ,Drosophila ,Polyadenylated RNA ,In Situ Hybridization - Abstract
The mobile element Doc is similar in structure and coding potential to the LINE families found in various organisms. In this paper, we analyze the insertional and structural polymorphism of this element and show that it appears to have a long evolutionary history in the genome of D. melanogaster. Like the family of I elements, the Doc family seems to display three types of elements: full length elements, defective members that have recently transposed and long since immobilized members common to each D. melanogaster strain. These three classes of Doc elements seem to be present in D. simulans, a closely related species to D. melanogaster. Furthermore, we show that Doc is transcribed as a polyadenylated RNA of about 5 kb in length, presumed to be a full length RNA. This transcript is present in different tissues and at different stages of Drosophila development. These results are compared with previous records on the chromosomal distribution of LINEs or other transposable element families. Doc transcription is analyzed in an attempt to understand the link between Doc transcription and transposition.
- Published
- 1994
33. I elements and the Drosophila genome
- Author
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Pierre Abad, Marie-Christine Chaboissier, Alain Pélisson, M. Simonelig, Chantal Vaury, and Alain Bucheton
- Subjects
Transposable element ,Male ,Molecular Sequence Data ,Retrotransposon ,Plant Science ,Species Specificity ,Molecular evolution ,Drosophilidae ,Heterochromatin ,Genetics ,Animals ,Amino Acid Sequence ,Drosophila (subgenus) ,Crosses, Genetic ,Genomic organization ,biology ,Base Sequence ,Models, Genetic ,Reproduction ,General Medicine ,biology.organism_classification ,Drosophila melanogaster ,Gene Expression Regulation ,Insect Science ,Horizontal gene transfer ,DNA Transposable Elements ,Hybridization, Genetic ,RNA ,Animal Science and Zoology ,Drosophila ,Female - Abstract
LINEs are a large class of transposable elements in eukaryotes. They transpose by reverse transcription of an RNA intermediate. I elements of Drosophila melanogaster belong to this class and are responsible for the I-R system of hybrid dysgenesis. Many results indicate that at the beginning of the century natural populations of this species were devoid of active I elements and that they were invaded by functional I elements in the last decades. Many Drosophila species contain both defective and active I elements. It seems that the latter were lost in Drosophila melanogaster before its spread throughout the world, and that the recent invasion results from the spread of functional elements originating either from another species by horizontal transfer or from an isolated population of the same species. These data are discussed, as well as their significance in evolutionary processes.
- Published
- 1992
34. [Untitled]
- Author
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Alain Pélisson, Christophe Terzian, and Alain Bucheton
- Subjects
Genetics ,Retrovirus ,Phylogenetics ,viruses ,RNA-Directed DNA Polymerase ,Endogenous retrovirus ,Biology ,ORFS ,Paleovirology ,biology.organism_classification ,Gene ,Ecology, Evolution, Behavior and Systematics ,Reverse transcriptase - Abstract
The genome of invertebrates is rich in retroelements which are structurally reminiscent of the retroviruses of vertebrates. Those containing three open reading frames (ORFs), including an env-like gene, may well be considered as endogenous retroviruses. Further support to this similarity has been provided by the ability of the env-like gene of DmeGypV (the Gypsy endogenous retrovirus of Drosophila melanogaster) to promote infection of Drosophila cells by a pseudotyped vertebrate retrovirus vector. To gain insights into their evolutionary story, a sample of thirteen insect endogenous retroviruses, which represents the largest sample analysed until now, was studied by computer-assisted comparison of the translated products of their gag, pol and env genes, as well as their LTR structural features. We found that the three phylogenetic trees based respectively on Gag, Pol and Env common motifs are congruent, which suggest a monophyletic origin for these elements. We showed that most of the insect endogenous retroviruses belong to a major clade group which can be further divided into two main subgroups which also differ by the sequence of their primer binding sites (PBS). We propose to name IERV-K and IERV-S these two major subgroups of I nsect E ndogenous R etro V iruses (or I nsect ER rantiV irus, according to the ICTV nomenclature) which respectively use Lys and Ser tRNAs to prime reverse transcription.
- Published
- 2001
35. Non-mendelian female sterility inDrosophila melanogaster: variations of chromosomal contamination when caused by chromosomes of various inducer efficiencies
- Author
-
Alain Pélisson
- Subjects
Genetics ,Non-Mendelian inheritance ,biology ,Sterility ,Inducer ,General Medicine ,Drosophila melanogaster ,biology.organism_classification - Abstract
SUMMARYA quite specific kind of sterileF1female, calledSFfemales, arises only when females of strains denoted reactive are crossed with males of the other class (inducer). It was previously shown that this sterility results from a nucleocytoplasmic interaction between the maternal reactive cytoplasm and a factor, calledI, which may be born by any one of the paternal chromosomes. InSFfemales, but not in their brothers, a varying proportion of reactive chromosomes are able to acquire irreversibly theIfactor, independently of any classical genetic recombination with the inducer chromosome(s). During this process, called chromosomal contamination, the contaminating chromosome(s) do not undergo any apparent change. The present paper deals with the efficiency of both original inducer and contaminated chromosomes to yield a more or less intenseSFsterility. TheOtanuinducer laboratory strain contains at least two types ofXchromosomes (calledstrongandweak) which differ genetically with respect to their inducer efficiency. Reactive third chromosomes were contaminated by thesestrongorweak Xchromosomes and their inducer efficiencies compared. Results show that they are on averagestrongerwhen they have been contaminated bystrong Xchromosomes than when contaminated byweakones. Such a correlation favours the hypothesis that chromosomal contamination is due to the insertion of some genetic element(s) into reactive chromosomes.
- Published
- 1978
36. Non-mendelian female sterility and hybrid dysgenesis inDrosophila melanogaster
- Author
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G Picard, Margaret G. Kidwell, Alain Bucheton, J. C. Bregliano, Lavige Jm, and Alain Pélisson
- Subjects
Male ,Genetics ,Non-Mendelian inheritance ,X Chromosome ,biology ,Sterility ,Reciprocal cross ,General Medicine ,biology.organism_classification ,Drosophila melanogaster ,Nondisjunction ,Mutation ,Melanogaster ,Animals ,Female ,Inducer ,Crossing Over, Genetic ,Infertility, Female ,Crosses, Genetic ,X chromosome - Abstract
SUMMARYSystematic crosses between various strains ofDrosophila melanogasterlead in some cases to partly sterile F1females (SFfemales). Two main classes of strain, inducer and reactive, have been denned on the basis of this sterility, which shows very specific physiological features.SFfemales arise only when reactive females are crossed with inducer males. In contrast, F1females (RSF) produced by the reciprocal cross between inducer females and reactive males have normal fertility. All wild populations tested are of the inducer category, laboratory strains are either inducer or reactive. Sterility is the result of interaction between two genetic factors denotedIandR, respectively responsible for the inducer and reactive conditions and whose unusual genetic behaviour has been described in other papers. The present paper reports experiments showing that theI–Rinteraction is also responsible for high levels ofXnondisjunction and of mutation in theSFfemale germ-line. The analogy with the P-M system of Kidwell, Kidwell & Sved (1977b), is discussed as are also the implications of the existence of theI-Rsystem for spontaneous mutation research inD. melanogaster.
- Published
- 1978
37. NON-MENDELIAN FEMALE STERILITY IN DROSOPHILA MELANOGASTER: CHARACTERIZATION OF THE NONINDUCER CHROMOSOMES OF INDUCER STRAINS
- Author
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Alain Pélisson and G Picard
- Subjects
Genetics ,B chromosome ,Non-Mendelian inheritance ,biology ,Sterility ,Chromosome ,Investigations ,Balancer chromosome ,Drosophila melanogaster ,biology.organism_classification ,Small supernumerary marker chromosome ,Genetic recombination - Abstract
In relation to non-Mendelian female sterility, Drosophila melanogaster strains can be divided into two main classes, inducer and reactive. The genetic element responsible for the inducer condition (I factor) is chromosomal and may be linked to any inducer-strain chromosome. Each chromosome carrying the I factor (i + chromosome) can, when introduced by the paternal gamete into a reactive oocyte, give rise to females (denoted SF) showing more-or-less reduced fertility. As long as i + chromosomes are transmitted through heterozygous males with reactive originating chromosomes (r chromosomes), I factor follows Mendelian segregation patterns. In contrast, in heterozygous i+/r females, a varying proportion of r chromosomes may irreversibly acquire I factor, independently of classical genetic recombination, by a process called chromosomal contamination. The contaminated reactive chromosomes behave as i + chromosomes.—In the present paper, evidence is given that the Luminy inducer strain displays a polymorphism for two kinds of second chromosomes. Some of them are i +, while others, denoted io, are unable t3 induce any SF sterility when introduced by paternal gametes into reactive oocytes. They are also unable to induce contamination of r chromosomes, but, like r chromosomes, they may be contaminated by i+ chromosomes in SF or RSF females. The study of the segregation of i + and io second chromosomes in the progeny of heterozygous Luminy males and females leads to the conclusion that on chromosome 2 of the Luminy stock the I factor is at a single locus. —XI second and third io chromosomes have been found in several inducer strains. Since these chromosomes can be maintained with i + chromosomes in inducer strains in spite of their ability to be contaminated in RSF females, it can be concluded that chromosomal contamination does not take place in females of inducer strains. This implies that contamination occurs only in cells having cytoplasm in a reactive state.
- Published
- 1979
38. The I-R system of hybrid dysgenesis in Drosophila Melanogaster: Are I factor insertions responsible for the mutator effect of the I-R interaction?
- Author
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Alain Pélisson
- Subjects
Male ,Recombination, Genetic ,Transposable element ,Genetics ,Base Sequence ,biology ,DNA ,biology.organism_classification ,Molecular biology ,Human genetics ,Dysgenesis ,Drosophila melanogaster ,Phenotype ,Genetic Code ,DNA Transposable Elements ,Animals ,Female ,Inducer ,Infertility, Female ,Molecular Biology ,Infertility, Male - Abstract
When Drosophila melanogaster males coming from a class of strains known as inducer are crossed with females from the complementary class (reactive), a quite specific kind of sterile female (SF) is obtained that exhibits other dysgenic traits such as non-disjunctions and non-randomly distributed mutations. This syndrome is caused by the interaction of the 'I factor' linked to inducer chromosomes with the maternally inherited reactive state 'R'. This I--R interaction is also responsible for 'chromosomal contamination' that is likely to result from very frequent I factor insertions into reactive chromosomes. Such insertions might be responsible for the I--R induced mutations and some data concerning this hypothesis are reported here. Out of nine I--R-generated mutants one, the whiteIR1 (wIRI) allele, is closely linked to an I factor, which maps either at the site of the mutation or within less than 0.02 map units. In addition, wIR1 is somewhat unstable when transmitted through SF females. In contrast, the typical I factor does not seem to be associated with any of the eight other mutants as judged by their inability to induce the female sterility characteristic of the I--R syndrome. The possibility is discussed that most of I--R-induced mutations are nevertheless caused by insertions of either undetectable I factors of other transposable elements, not related to I, whose transposition is dependent on the I--R interaction.
- Published
- 1981
39. Evidence for rapid limitation of the I element copy number in a genome submitted to several generations of I-R hybrid dysgenesis in Drosophila melanogaster
- Author
-
Jean Claude Bregliano and Alain Pélisson
- Subjects
Transposable element ,Genetics ,biology ,Sterility ,Offspring ,Drosophilidae ,Genotype ,Drosophila melanogaster ,biology.organism_classification ,Molecular Biology ,Genome ,Germline - Abstract
When Drosophila melanogaster males coming from a class of strains known as inducer are crossed with females from the complementary class (reactive), a quite specific kind of sterility is observed in the F1 female progeny (denoted SF). The inducer chromosomes differ from the reactive chromosomes by the presence of a transposable element (called the I factor) that is responsible for the induction of this dysgenic symptom. In the germ line of dysgenic females, up to 100% of the reactive chromosomes may be contaminated, i.e. they acquire I factor(s) owing to very frequent replicative transpositions. A contaminated reactive stock was obtained by reconstructing the reactive genotype in the offspring of SF females and its kinetics of invasion by I elements was followed in the successive inbred dysgenic generations. The results show that the mean copy number of I elements increased very quickly up to the level of inducer strains and then stayed in equilibrium even though the dysgenic state was perpetuated by selection for SF sterility at every generation. The possible mechanisms of this copy number limitation are discussed.
- Published
- 1987
40. The I-R system of hybrid dysgenesis in Drosophila melanogaster: influence on SF females sterility of their inducer and reactive paternal chromosomes
- Author
-
Alain Pélisson
- Subjects
Genetics ,Male ,biology ,Sterility ,Extrachromosomal Inheritance ,Chromosome ,biology.organism_classification ,Phenotype ,Sperm ,Chromosomes ,Dysgenesis ,Drosophila melanogaster ,Cytoplasm ,Animals ,Hybridization, Genetic ,Inducer ,Female ,Infertility, Female ,Genetics (clinical) ,Crosses, Genetic - Abstract
A specific kind of sterile F1 female, denoted SF, arises when females from strains known as reactive are crossed with males from the complementary class of strains (inducer). It has been shown that this sterility results from the interaction between the maternal reactive cytoplasm and any one of the paternal inducer chromosomes. This interaction yields other dysgenic traits including non-disjunction and mutations. In this note, the abilities of paternal gametes containing various combinations of inducer and reactive chromosomes to give more or less sterile SF females when fertilising standard reactive oocytes were compared. Although they did not cause SF sterility, reactive chromosomes, when present in sperm containing at least one inducer chromosome, were found to influence the intensity of sterility: variations of SF sterility were observed between SF females which differed only by one paternally inherited reactive chromosome. Reactive chromosomes are known to control the cytoplasmic state of reactive females. The present results suggest that this chromosomal control also takes place in SF females.
- Published
- 1979
41. Silencing of retroviruses by small RNAs in Drosophila
- Author
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Vincent Serrano, Alain Pélisson, Alain Bucheton, Christine Brun, and Séverine Chambeyron
- Subjects
Transposable element ,Genetics ,lcsh:Immunologic diseases. Allergy ,Heterochromatin ,viruses ,Invited Speaker Presentation ,Endogenous retrovirus ,Piwi-interacting RNA ,Retrotransposon ,Provirus ,Biology ,Germline ,Infectious Diseases ,Virology ,Gene silencing ,lcsh:RC581-607 - Abstract
Retroviruses propagate also in invertebrates. The Drosophila genome contains many proviruses belonging to several families of endogenous retroviruses. These proviruses are usually repressed, but the mechanisms involved in their repression have been a mystery for a long time. Gypsy is a Drosophila endogenous retrovirus that is also infectious. Therefore it can propagate both horizontally as infectious retroviruses and vertically as endogenous retroviruses. It can transpose as well as retrotransposons. One of the principal ways of propagation of gypsy involves infection of the female germline by particles produced by somatic cells of the ovaries. This process is normally repressed by the host locus flamenco (flam). Restrictive flam alleles repress gypsy in these somatic cells. We have shown that the repression correlates with the amount of complementary 24-29 nucleotide long piRNAs (Piwi interacting RNAs). These small RNAs are responsible for the control of transposable elements. The silencing mechanisms associated with them are different from the mechanisms associated with siRNAs and miRNAs and have still to be elucidated. The amount of gypsy piRNAs is determined by the flam locus in a provirus copy number-independent manner and their production is triggered by pericentromeric defective proviruses located in the locus. flam also controls other retroelements. The flam region is very rich in defective copies of retrotransposons and endogenous retroviruses, including gypsy. Our results indicate that the piRNA silencing pathway may be considered as a sort of immunity system using the defective proviruses (or transposable elements) located in heterochromatin as a repertory directing the silencing machinery toward the transcripts of the corresponding functional retroviruses (or transposable elements).
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