Genomes and Evolution
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Laboratoire Evolution Génomes, Comportement, Ecologie (EGCE), CNRS UMR 9191, IRD UMR247, Université Paris-Saclay
1 avenue de la Terrasse
91198 Gif-sur-Yvette Cedex
France
Scientific Interest
Transposable elements (TEs) are DNA sequences considered as genomic parasites. They have the ability to multiply more quickly then the genome, and then can spread in the genomes and in the populations. Their mobile and repetitive nature makes them potentially harmful (insertion into genes, ectopic recombination). However, insertions can sometimes bring some beneficial effects for the host and may become domesticated. We know several examples of evolutionary innovations due to transposable elements. Hence, transposable elements participate to the dynamics and the evolution of the genome, at the level of structure, and function. However, the non-controlled amplification of transposable elements leads to an exponential increase in copy number. To avoid this situation detrimental to the host, some regulatory pathways have emerged that silence transposable elements. In Drosophila and other metazoans, the germline PIWI pathway uses small RNAs complementary to TE sequences, which will repress, transcriptionally or post transcriptionally, TE expression, by deposing epigenetic marks on the DNA, or by destroying TE mRNAs. These small RNAs are produced by specific genomic loci called pi-clusters, made of the successive accumulation of TEs. Furthermore, TEs, that have no functions in the cell, can accumulate mutations that are not counter-selected, so they ultimately become inactive, present in the genome as relics only. The persistence of active elements in genomes is then helped by their ability to cross species barriers via horizontal transfer events. In the team, we are interested in the molecular evolution of transposable elements in populations, in their amplification dynamics within genome and populations, and in the parameters that influence the probability for a horizontal transfer to occur and to succeed. Our approaches are experimental (drosophila, insect, amphibians), bioinformatics, and theoretical.
Transposable elements (TEs) are DNA sequences considered as genomic parasites. They have the ability to multiply more quickly then the genome, and then can spread in the genomes and in the populations. Their mobile and repetitive nature makes them potentially harmful (insertion into genes, ectopic recombination). However, insertions can sometimes bring some beneficial effects for the host and may become domesticated. We know several examples of evolutionary innovations due to transposable elements. Hence, transposable elements participate to the dynamics and the evolution of the genome, at the level of structure, and function. However, the non-controlled amplification of transposable elements leads to an exponential increase in copy number. To avoid this situation detrimental to the host, some regulatory pathways have emerged that silence transposable elements. In Drosophila and other metazoans, the germline PIWI pathway uses small RNAs complementary to TE sequences, which will repress, transcriptionally or post transcriptionally, TE expression, by deposing epigenetic marks on the DNA, or by destroying TE mRNAs. These small RNAs are produced by specific genomic loci called pi-clusters, made of the successive accumulation of TEs. Furthermore, TEs, that have no functions in the cell, can accumulate mutations that are not counter-selected, so they ultimately become inactive, present in the genome as relics only. The persistence of active elements in genomes is then helped by their ability to cross species barriers via horizontal transfer events. In the team, we are interested in the molecular evolution of transposable elements in populations, in their amplification dynamics within genome and populations, and in the parameters that influence the probability for a horizontal transfer to occur and to succeed. Our approaches are experimental (drosophila, insect, amphibians), bioinformatics, and theoretical.
Thematic