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Comparaison de séquences d'éléments transposables et de gènes d'hôte chez cinq espèces : A. thaliana, C. elegans, D. melanogaster, H. sapiens et S. cerevisiae

Emmanuelle Lerat 1
1 Eléments transposables, évolution, populations
GINSENG - Département génétique, interactions et évolution des génomes [LBBE]
Abstract : Transposable elements (TEs), which are found in all living organisms and are implied in many mutations and chromosome rearrangements, appear to be major components of genomes. They should be submitted to the same constraints than the host genes. To test this hypothesis, we thus at first time have analyzed codon usage of TEs and host genes in five species: A. thaliana, C. elegans, D. melanogaster, H. sapiens, and S. cerevisiae. Results show that TEs are AT rich whatever the host species: this seems to be an intrinsic characteristic of the TEs. The analysis of the base composition at the different positions of the codons shows that the AT richness on the third position is lower than on the unconstrained regions of the genomes. TEs do not thus only undergo mutational bias but are submitted to selection. However, codon usage in TEs is not related to a low or high expression level, which suggests a particular expression pattern for these elements. An analysis of relative abundance of di- and trinucleotides of TE sequences and host genomes shows that TEs have pattern of abundance similar to that of the host, independently to the base composition bias. This analysis shows, however, that human retrovirus genes and LTR retrotransposons with an env gene of Drosophila have a pattern of relative abundance different to those of the host genes. Dinucleotide abundance seems thus to be a good way to detect potentially infectious retroelements. This work suggests a specific behavior of TEs, which seem submitted to particular selection constraints allowing the keeping of AT richness. However, they undergo host genome stamp, probably of structural type.
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https://tel.archives-ouvertes.fr/tel-00005207
Contributor : Emmanuelle Lerat <>
Submitted on : Thursday, March 4, 2004 - 6:17:58 PM
Last modification on : Monday, February 10, 2020 - 4:36:55 PM
Long-term archiving on: : Friday, April 2, 2010 - 7:49:33 PM

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Emmanuelle Lerat. Comparaison de séquences d'éléments transposables et de gènes d'hôte chez cinq espèces : A. thaliana, C. elegans, D. melanogaster, H. sapiens et S. cerevisiae. Autre [q-bio.OT]. Université Claude Bernard - Lyon I, 2001. Français. ⟨tel-00005207⟩

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