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Origine et développement des cellules germinales chez l'huître Crassostrea gigas : intérêt pour le contrôle de la reproduction en écloserie

Abstract : A comprehensive knowledge of Crassostrea gigas oyster reproduction processes is essential to optimize controlled reproduction in hatchery. This study aimed to determine the origin and the mechanisms of annual renewal of germ cells, still unknown in oysters, and the influence of temperature and photoperiod parameters on the regulation of the reproductive cycle. We characterized an orthologue of the vasa gene, the Oyvlg (Oyster vasa-like gene), the first germ cell specific marker isolated in molluscs. This marker was used to study C. gigas germline development. Oyster germ cells appeared specified during early development from mesentoblast 4d, as primordial germ cells (PGCs) determined by maternal cytoplasmic determinants, including Oyvlg mRNA. In adult oysters, the annual renewal of germ cells results from a proliferation of germinal stem cells (GSCs), self-renewing cells, scattered in the conjunctive tissue during the resting period. One-year experimental conditionings were realized to determine temperature and photoperiod parameter effects on oyster gametogenesis. Experimental conditionings consisted in (1) natural temperature and photoperiod conditions corresponding to Marennes-Oléron bay values, (2) accelerated conditions, twice faster than natural cycles and (3) constant wintering conditions adjusted to 8°C and 8 hours day-length. These analyses revealed a high plasticity of C. gigas reproduction since the rhythm of the reproductive cycle was entirely modelled by temperature and photoperiod variations. Decreasing photoperiod may regulate GSCs proliferation while low temperature (8°C-11°C) would enhance gonial mitosis and high temperature would accelerate germ cell maturation. As a result, manipulation of temperature and photoperiod conditions allows effective controlled reproduction all over the year.
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Contributor : Caroline Fabioux <>
Submitted on : Monday, May 30, 2005 - 5:47:55 PM
Last modification on : Tuesday, November 24, 2020 - 12:16:06 PM
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  • HAL Id : tel-00009344, version 1

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Caroline Fabioux. Origine et développement des cellules germinales chez l'huître Crassostrea gigas : intérêt pour le contrôle de la reproduction en écloserie. Biologie de la reproduction. Université de Bretagne occidentale - Brest, 2004. Français. ⟨tel-00009344⟩

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