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Etude des patrons d'évolution asymétrique dans les séquences d'ADN

Abstract : This thesis analyses the effect of two essential cellular mechanisms, replication and transcription, on the base composition of DNA sequences. These two processes function asymmetrically on the two DNA strands, and they have as a consequence an asymmetric nucleotide composition in genomic sequences. Moreover, they act in a coordinated manner on genomes, thus the estimation of their respective effects can be difficult.
First, we studied the co-orientation between replication and transcription in prokaryotes. We proposed a method for the study of base composition biases which can separate these two sources of asymmetry. We show that the effect of replication on base composition can be highly variable even between closely related species.

We then studied the substitution pattern in transcribed regions and around replication origins, in human, with special emphasis on the effect of the 5'-3' nucleotide context. Patterns of context-dependent asymmetric substitutions are similar for replication and transcription. The variation of substitution rate with the expression pattern suggests the presence of context-dependent asymmetric repair mechanisms.

We proposed a computational approach for the study of the substitution pattern in microsatellites. We prove that transcribed microsatellites are subject to asymmetric evolution.
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Submitted on : Thursday, July 24, 2008 - 11:02:29 AM
Last modification on : Sunday, September 25, 2022 - 3:53:36 AM
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  • HAL Id : tel-00305419, version 1



Anamaria Necsulea. Etude des patrons d'évolution asymétrique dans les séquences d'ADN. Sciences du Vivant [q-bio]. Université Claude Bernard - Lyon I, 2008. Français. ⟨tel-00305419⟩



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