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Meiosis and recombination
(Department Genome Dynamics)
Leader: Bernard DE MASSY
In sexually reproducing species, meiosis allows the proper transmission of the genetic information at each generation through various steps which lead to the formation of haploid gametes from diploid cells. In most species, the proper segregation of chromosomes at the first meiotic division requires the establishment of connections resulting from reciprocal homologous exchanges or crossing over. Crossing over also generate new allele combinations and thus increase the genetic diversity. Our group is addressing several aspects of the mechanism and regulation of meiotic recombination using the mouse as a model system. Meiotic recombination events are initiated by the formation of DNA double-strand breaks catalyzed by Spo11 protein. About 300 DSBs take place at the beginning of meiotic prophase in mouse meiotic cells. We are looking for proteins involved in this process. In parallel, one puzzling question is to understand what determines the distribution of meiotic recombination events in the genome. Initiation is known to occur in highly localized, non random regions, and most often intergenic. We are investigating the various components that might contribute to initiation sites specification (DNA sequence, chromatin, higher order feature, trans acting factors…). DSBs are known to be repaired according to two major pathways, one leading to crossing over, one to non crossover. We are investigating how these DSB repair pathways are regulated.