Organization and integrity of parental chromosomes at fertilization in Drosophila ; Organisation et intégrité des chromosomes parentaux à la fécondation chez la drosophile

Sexual reproduction involves dramatic gamete differentiation and profound parental chromosomes remodelling. At fertilization, these chromosomes need to be rendered competent for the formation of the fist zygotic nucleus. I have studied the functional relevance of several paternal and maternal molecular pathways that participate during this process in Drosophila. The HIRA complex is required for nucleosome assembly in the male pronucleus at fertilization. I have further described the rôle of HIRA and its obligatory partner Yemanuclein-α during this step. I have characterized the somatic roles of this complex during nucleosome assembly and its involvment in heterochromatin stability, which gives us a better understanding of the biological needs that drive its conservation and evolution. I have also focused on several situations where parental chromosomes integrity at fertilization is compromised. (1) I have described a meiotic catastrophe associated with the natural expression of a transposon in the female germline during hybrid dysgenesis. (2) I have contributed to show that K81 is an essential protein for telomere protection in paternal chromosomes during spermiogenesis. (3) I have participated in the characterization of the chromosomal abnormalities associated with cytoplasmic incompatibility induced by Wolbachia. Together, these results underscore the specificities of parental chromosomes at fertilization and shed light into the importance of maternal and paternal pathways for their integration in the first zygotic nucleus ; La reproduction sexuée implique une différentiation extrême des gamètes qui s’accompagne de profonds remaniements des chromosomes parentaux. Au moment de la fécondation, ces chromosomes doivent être rendus compétents pour la formation du premier noyau zygotique. Au cours de ma thèse, j’ai étudié l’importance fonctionnelle de plusieurs voies moléculaires paternelles et maternelles participant à cette étape chez la drosophile. Le complexe HIRA est impliqué dans l’assemblage de nucléosomes ...