Contrôle de la ponte ovulaire chez l'huître creuse Crassostrea gigas : utilisation du modèle Sepia officinalis pour la caractérisation de peptides régulateurs

Despite the fact that the involvement of environmental factors in the physiology of the japanese oyster C. gigas is fully described, regulatory peptides are not known. In this study, we focused on peptidergic control of egg-laying. In order to characterize peptides involved in the regulation of egg-laying in C. gigas, the cuttlefish S. officinalis was used as a model. Firstly, regulatory peptides were investigated in the cuttlefish by peptidomic analysis. This approach led to the identification of eleven new ovarian regulatory peptides. Based on conserved tags, these peptides have been classified into two families: the SepCRPs (Sepia Capsule Releasing Peptides) and the OJPs (Ovarian Jelly Peptides). Released by oocytes into the genital coelom, they are responsible for the storage of oocytes before mating and external egg capsule secretion. In a second step, peptides related to SepCRPs and OJPs were investigated in oysters by means of mass spectrometry, but without any success. Nevertheless, using a myotropic bioassay based on recorded cuttlefish oviduct contractions, the first ovarian regulatory peptide from the oyster was characterized: PIESVD. This peptide triggers adductor muscle contractions in mature females, these contractions being involved in oocyte release. Subsequently, peptidomic analysis of male genital products led to the identification of APGWamide in both cuttlefish and oysters. This neuropeptide triggers oocyte release in both species. Thus, in commercial and experimental hatcheries, APGWamide and PIESVD could be used for the selection of mature females to perform genetic manipulations and in vitro fertilizations.