RNA-based gene duplication sheds new light on mammalian sex chromosome evolution

Détails

Demande d'une copie
ID Serval
serval:BIB_20EA814D431A
Type
Thèse: thèse de doctorat.
Collection
Publications
Institution
Titre
RNA-based gene duplication sheds new light on mammalian sex chromosome evolution
Auteur⸱e⸱s
Potrzebowski L.
Directeur⸱rice⸱s
Kaessmann H.
Détails de l'institution
Université de Lausanne, Faculté de biologie et médecine
Adresse
Faculté de biologie et de médecine Université de Lausanne UNIL - Bugnon Rue du Bugnon 21 - bureau 4111 CH-1015 Lausanne SUISSE
Statut éditorial
Acceptée
Date de publication
2009
Langue
anglais
Nombre de pages
69
Notes
REROID:R005204225 ill.
Résumé
ABSTRACT :
Gene duplication is a fundamental source of raw material for the origin of genetic novelty.
It has been assumed for a long time that DNA-based gene duplication was the only source of new genes. Recently however, RNA-based gene duplication (retroposition) was shown in multiple organisms to contribute significantly to their genetic diversity. This mechanism produces intronless gene copies (retrocopies) that are inserted in random genomic position, independent of the position of the parental source genes.
In human, mouse and fruit fly, it was demonstrated that the X-linked genes spawned an excess of functional retroposed gene copies (retrogenes). In human and mouse, the X chromosome also recruited an excess of retrogenes.
Here we further characterized these interesting biases related to the X chromosome in mammals. Firstly, we have confirmed presence of the aforementioned biases in dog and opossum genome. Then based on the expression profile of retrogenes during various spermatogenetic stages, we have provided solid evidence that meiotic sex chromosome inactivation (MSCI) is responsible for an excess of retrogenes stemming from the X chromosome. Moreover, we showed that the X-linked genes started to export an excess of retrogenes just after the split of eutherian and marsupial mammalian lineages. This suggests that MSCI has originated around this time as well. More fundamentally, as MSCI reflects the spread of recombination barrier between the X and Y chromosomes during their evolution, our observation allowed us to re-estimate the age of mammalian sex chromosomes. Previous estimates suggested that they emerged in the common ancestor of all mammals (before the split of monotreme lineage); whereas, here we showed that they originated around the split of marsupial and eutherian lineages, after the divergence of monotremes. Thus, the therian (marsupial and eutherian) sex chromosomes are younger than previously thought.
Thereafter, we have characterized the bias related to the recruitment of genes to the X chromosome. Sexually antagonistic forces are most likely driving this pattern. Using our limited retrogenes expression data, it is difficult to determine the exact nature of these forces but some conclusions have been made. Lastly, we looked at the history of this biased recruitment: it commenced around the split of marsupial and eutherian lineages (akin to the biased export of genes out of the X). In fact, the sexually antagonistic forces are predicted to appear just around that time as well. Thereby, the history of the recruitment of genes to the X, provides an indirect evidence that these forces are responsible for this bias.
Création de la notice
17/06/2010 10:53
Dernière modification de la notice
20/08/2019 12:57
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