Showing results 21 to 40 on 1229 in total
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The evolution of senescence (the physiological decline of organisms with age) poses an apparent paradox because it represents a failure of natural selection to increase the survival and reproductive performance of organisms. The paradox can be resolved if natural selection becomes less effective with age, because the death of postreproductive individuals should have diminished effects on Darwinian fitness. A substantial body of empirical work is consistent with this prediction for animals. However, such evidence is still scarce in plants. I will discuss the plausible reasons why the genetic basis of senescence in plants was not studied from an evolutionary perspective in the past. I will also present our experimental results on the quantitative genetic basis of senescence in the short-lived perennial plant Silene latifolia and their contribution to our understanding of the evolution of senescence in plants.
HDR de Franck Picard le jeudi 4 décembre 2014 à 13 h 30 - amphithéâtre Jordan (Institut Camille Jordan) bâtiment Braconnier (Doua)
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Thèse de Lucie Froissart - Vendredi 30 novembre 2012 - 14h00 Amphi Physique Nucléaire - Bât Dirac
Thèse d'Etienne Rajon - Jeudi 18 décembre 2008 - 14h00 - Amphi du Département de Génie Chimique IUT A
Adenosine-to-inosine (A-to-I) editing is hypothesized to facilitate adaptive evolution by expanding proteomic diversity through an epigenetic approach. However, it is challenging to provide evidences to support this hypothesis at the whole editome level. In this study, we systematically characterized 2,114 A-to-I RNA editing sites in female and male brains of D. melanogaster, and nearly half of these sites had events evolutionarily conserved across Drosophila species. We detected strong signatures of positive selection on the nonsynonymous editing sites in Drosophila brains, and the beneficial editing sites were significantly enriched in genes related to chemical and electrical neurotransmission in Drosophila. By adopting a method originally designed to detect linkage disequilibrium of DNA mutations, we examined the editomes of ten metazoan species and detected extensive linkage of editing in Drosophila and cephalopods. The prevalent linkages of editing in these two clades, many of which are conserved between closely related species and might be associated with the adaptive proteomic recoding, are maintained by natural selection at the cost of genome evolution. Nevertheless, in worms and humans, we only detected modest proportions of linked editing events, the majority of which were not conserved. Furthermore, the linkage of editing in coding regions of worms and humans might be overall deleterious, which drives the evolution of DNA sites to escape promiscuous editing. Altogether, our results suggest that the linkage landscape of A-to-I editing has evolved during metazoan evolution. If time permitting, I will also talk about other work related to adaptive evolution at the post-transcriptional level.
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