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Expression et évolution de gènes de la famille des ARN hélicases à boîte DEAD chez Arabidopsis thaliana (L.) Heynh

Abstract : The evolution of the regulation of gene expression probably played an important part in gene subfunctionalisation and neofunctionalisation. The existence of gene specific transcript profiles suggests functional diversification, hence loss of functional redundancy, and could explain the maintenance of numerous paralogues in a genome. Real-time quantitative RT-PCR techniques proved to be suitable for the expression studies of gene families with highly variable expression levels and related sequences. The model genome of Arabidopsis thaliana contains a DEAD box RNA helicase family (RH) of 58 members, i.e. almost twice as many as in the animal or yeast genomes. Transcript profiling using real-time quantitative PCR has been obtained for 20 AtRHs from 9 different organs. Among the members of this housekeeping gene family, two AtRHs exhibited plant specific transcript profiles while the other 18 AtRHs had similar profiles, but very different levels of transcription. The main regulatory element of the transcript level is the simultaneous presence of a TATA-box and an intron in the 5' UTR. There is a positive and highly significant correlation between the size of the 5' UTR intron and the transcription level, as long as a characteristic TATA-box is present. Our work on the expression of the AtRH genes suggests a scenario for the evolution of duplicated genes in the same terminal branch of a phylogenetic tree and that often present different expression levels. After the duplication of a highly transcribed ancestral AtRH, an alteration of the transcriptional activity of the divergent duplicates occurs through successive events of suppression of the TATA-box and/or the 5' UTR intron.
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https://tel.archives-ouvertes.fr/tel-00007807
Contributor : Annaïck Mingam <>
Submitted on : Friday, December 17, 2004 - 3:19:18 PM
Last modification on : Friday, October 23, 2020 - 4:52:06 PM
Long-term archiving on: : Friday, April 2, 2010 - 9:18:59 PM

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  • HAL Id : tel-00007807, version 1

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Annaïck Mingam. Expression et évolution de gènes de la famille des ARN hélicases à boîte DEAD chez Arabidopsis thaliana (L.) Heynh. Sciences du Vivant [q-bio]. Université Paris Sud - Paris XI, 2004. Français. ⟨tel-00007807⟩

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