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Etude des mécanismes évolutifs perturbant l’organisation des gènes dans les génomes de vertébrés

Abstract : Evolutionary processes disrupting the gene organisation in eukaryotic genomes belong to two categories: changes in the order of the genes, known as rearrangements, and changes in the content of the genome by gene duplications, deletions and gains. The mechanisms through which these events arise, and their functional and selective impact on genomes, are poorly understood. This thesis covers two different projects. Firstly, we investigated the distribution of rearrangement breakpoints between an ancestral genome and its modern descendants. This distribution was modelled according to local genomic characteristics to highlight factors influencing the breakage process. Our results show that the distribution of breakpoints can be simply explained as a function of intergenic spacers length, although in a non-linear fashion differing from classical random expectations. The repartition of breakpoints in genomes seems to be linked to structural properties, and is only marginally affected by selective constraints. It might in fact reflect local chromatin structure in the genome. The second project is part of the joint sequencing effort for the zebrafish genome, and provides an overview of the organisation of this genome. Teleost fish genomes are anciently duplicated: the analysis focuses on the consequences of this duplication. Results show that the zebrafish genome displays a typical teleost fish genome organisation. Genes retained in two copies after the whole genome duplication belong to specific functional categories, and are biased towards genes already conserved as duplicates after the 1R and 2R duplication events that have taken place early in vertebrate history.
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Submitted on : Friday, November 9, 2012 - 9:07:23 AM
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  • HAL Id : tel-00750114, version 1

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Camille Berthelot. Etude des mécanismes évolutifs perturbant l’organisation des gènes dans les génomes de vertébrés. Sciences agricoles. Université Paris Sud - Paris XI, 2012. Français. ⟨NNT : 2012PA112192⟩. ⟨tel-00750114⟩

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