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Caractérisation des paramètres génétiques de la résistance à certains agents infectieux chez l'huître creuse, Crassostrea gigas, dans le cadre des mortalités massives

Patrick Azema 1, 2 
1 LGPMM - Laboratoire de Génétique et Pathologie des Mollusques Marins
SGMM - Santé, Génétique et Microbiologie des Mollusques
Abstract : The aim of the thesis is the characterization of genetic basis of resistance to certain infectious agents in the Pacific oyster, Crassostrea gigas, in the context of mass mortalities of spat. Previous work at Ifremer highlighted a genetic component to the survival of oyster spat in the field rearing conditions or experimental conditions. Characterization of selected lines having contrasted survival rates in rearing conditions ('resistant' or 'sensitive') clarified the physiological basis of this genetic component or of their resistance/susceptibility to certain pathogens coming after mortalities experienced in the environment. Since 2008, mortality outbreaks of oysters worsened, in particular with a wider geographical distribution, and the involvement of infectious agents (viruses and bacteria) has been identified. In addition, with protocols developed in experimental pathology, it is now possible to assess specifically the level of resistance or susceptibility to certain infectious agents (OsHv-1 and vibrios). Thus, in the framework of the European project Bivalife (FP7, 2011-2013), two-parent families were produced (with factorial crosses, generating full-sib and half-sib families) in the Laboratory of Genetics and Pathology (Ifremer, Tremblade) and the behavior of these families, especially in terms of survival and sensitivity to various infectious agents (OsHv-1 and vibrios) was studied through pathological challenges. Once this biological material characterized, families with extreme behavior for induced mortality by infectious agents were stored (protected from mortality) for a selected generation production in 2013. On the other hand, in the SCORE project, funded following the call for proposals “selection and resource improvement program in oyster' launched by the Maritime Directorate of Fisheries and Aquaculture (DPMA) in June 2011, two-parent families are and will be produced in 2012 and 2013 in the facilities of the Regional Innovation Platform (PRI) in Bouin (Vendée). This project is coordinated by the Shellfish National Committee (CNC) including partners such as the French poultry and aquaculture breeders syndicate (SYSAAF) and Ifremer. Depending on the progress of selection for the mortality rate in the field, some families will be selected to test their sensitivity in laboratory conditions. Genetic parameters of the character of sensitivity to various infectious agents (OsHV-1 and vibrios) will thus be estimated by experimental challenge with the biological materials produced in the projects Bivalife (45 two-parent families produced in the Ifremer hatchery at La Tremblade) and SCORE (two-parent families produced in Bouin facilities). Complementary phenotypic characterization at cellular and molecular levels may also be performed. In addition, the level of dominance of this sensitivity could be estimated based on available biological material (families to produce in 2013).
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Patrick Azema. Caractérisation des paramètres génétiques de la résistance à certains agents infectieux chez l'huître creuse, Crassostrea gigas, dans le cadre des mortalités massives. Génétique animale. Institut agronomique, vétérinaire et forestier de France, 2018. Français. ⟨NNT : 2018IAVF0005⟩. ⟨tel-03392362⟩

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