Data/hora: 01/06/2024 17:25:59

Provedor de dados: 	Institutional Archive of Ifreme (ArchiMer)	
País: 	France	
Título: 	Caractérisation génétique de l’effort reproducteur de l’huître creuse, Crassostrea gigas, dans le cadre des mortalités estivales de juvéniles : Approch QTL

Genetic characterization of the reproductive effort of the Pacific oyster, Crassostrea gigas, in the context of summer mortalities of juvenile : QTL approach	
Autores: 	Flahauw, Emilie.	
Data: 	2013-09-20	
Ano: 	2013	
Palavras-chave: 	Huître creuse du Pacifique; Crassostrea gigas; Mortalités estivales; Survie; Effort reproducteur; Imagerie par Résonance Magnétique; Histologie; Marqueurs microsatellites; Marqueurs SNP; Cartographie de liaison; Détection de QTL; Pacific oyster; Crassostrea gigas; Summer mortality; Survival; Reproductive effort; Magnetif Resonance Imaging; Histology; Microsatellites; SNPs; Linkage mapping; QTL detection.	
Resumo: 	The Pacific oyster, Crassostrea gigas, is a major aquacultured species whose production represents an economic interest at worldwide, european and french levels. However, this species undergoes summer mortalities recorded from the beginning of the 20th century and, since 2008, this phenomenon increased and threatens mainly juvenile oysters. Aquaculture production of oysters suffers consequences of mass mortalities, that’s why this phenomenon has been studied for many years. In France, the bacterium Vibrio splendidus and the Ostreid virus Herpes Virus 1 (OsHV-1) are often associated with mass mortality outbreaks of juveniles oysters and it was demonstrated that selected individuals for resistance to summer mortality were able to slow the increasing in viral load OsHV-1 in their tissues and then to decline it. These same individuals also present a lighter reproductive effort than individuals selected for their sensitivity to summer mortality. In this context, this study aimed to improve the knowledge of genetic architecture of reproduction of C. gigas by identifying some regions of the genome called QTLs (Quantitative Trait Loci) involved in reproductive effort and highlighting possible genetic relationships between reproduction and survival; QTLs involved in survival being already detected. To characterize the reproductive effort, it was necessary to develop a set of new tools. From a biological point of view, 21 F2 families were produced from lines selected for their contrasting response to summer mortality. From a molecular point of view, new SNPs (Single Nucleotide Polymorphism) were developed to increase density of the genetic map already available for C. gigas. On a technical point of view, Magnetic Resonance Imaging (MRI) allowed to observe the gametogenesis of 300 individuals of the same family F2 during eight sessions over two years while previous studies were limited to a one-time observation because of the conventional methods of observation of gametogenesis leading necessarily to the death of the animals. A strong correlation was found between observations by MRI and observations by the conventional method of histology. In addition to the estimation of gonadic index (index traditionally used to characterize the reproductive effort), MRI also revealed individual variations in kinetics of gametogenesis and differences between males and females, the sex being identifiable on MRI images. In parallel, 300 individuals from two F2 families were sacrificed to estimate the gonadic index by histology. This approach enabled the detection of QTLs involved in many gametogenesis traits. Individuals from the three families characterized for F2 reproductive effort were characterized for survival during a summer mortality outbreak. This study was able to detect QTLs involved in the trait "survival." These QTLs correspond to some of those detected in a previous study. In addition, these QTLs are often collocated with QTLs involved in reproductive effort. Although the reproduction of the Pacific oyster is a complex trait to follow, the new tools used in this thesis allowed acquiring new knowledges. The sequencing of genome of Crassostrea gigas and Next-Generation Sequencing technologies may be able to help to refine the detected QTL regions	
Tipo: 	Text	
Idioma: 	Francês	
Identificador: 	http://archimer.ifremer.fr/doc/00233/34377/33786.pdf

http://archimer.ifremer.fr/doc/00233/34377/	
Editor: 	Université de La Rochelle, Ecole doctorale Gay Lussac	
Formato: 	application/pdf	
Fonte: 	2013 Université de la Rochelle

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