title: Cg-SoxE and Cg-β-catenin, two new potential actors of the sex-determining pathway in a hermaphrodite lophotrochozoan, the Pacific oyster Crassostrea gigas.
abstract: Sex determination is poorly known in mollusks, lophotrochozoa and most hermaphrodites. In the oyster Crassostrea gigas, an irregular successive hermaphrodite, sex determination may occur at the end of a gametogenetic cycle to prepare the next cycle. To investigate further into these aspects we have focused on orthologs of SoxE and β-catenin, key players of the male and female gonadic differentiation respectively in mammals. Based on phylogenetic analyses, Cg-SoxE, the oyster's SoxE ortholog, is closely related to vertebrate SoxE genes while Cg-β-catenin, the oyster's β-catenin ortholog, is classified amongst lophotrochozoa. The mRNA expression measured by qPCR in the gonadic area during a gametogenetic cycle is maximal for Cg-SoxE when sex is indiscernible and for Cg-β-catenin in mature females. Both expressions are localized from early germ cells to spermatocytes and pre-vitellogenic oocytes, and potentially in somatic cells. Cg-β-catenin is also expressed in vitellogenic oocytes. These actors may be involved in early oyster gonadic differentiation, which includes sex determination. Our results enhance the understanding of sex determination in C. gigas and in mollusks and they provide additional knowledge in compared genomics of reproduction and in molecular phylogeny.
authors.affiliation: Normandie Univ, France; UCBN, BIOMEA, F-14032 Caen, France; CNRS-INEE, FRE 3484, F-14032 Caen, France.
authors.forename: Christelle
authors.initials: C
authors.lastname: Santerre
authors.forename: Pascal
authors.initials: P
authors.lastname: Sourdaine
authors.forename: Béatrice
authors.initials: B
authors.lastname: Adeline
authors.forename: Anne-Sophie
authors.initials: AS
authors.lastname: Martinez
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D049896:Crassostrea / Q000502:physiology*; D005260:Female; D015870:Gene Expression; D005786:Gene Expression Regulation; D006066:Gonads / Q000166:cytology / Q000502:physiology; D057850:Hermaphroditic Organisms; D008297:Male; D008969:Molecular Sequence Data; D009866:Oogenesis; D010802:Phylogeny; D055757:SOXE Transcription Factors / Q000502:physiology*; D017422:Sequence Analysis, DNA; D019849:Sex Determination Processes; D013091:Spermatogenesis; D051176:beta Catenin / Q000502:physiology*
chemical_list: D055757:SOXE Transcription Factors; D051176:beta Catenin
keywords: Gonadic differentiation; Oyster; Sex-determining pathways; Sox9; β-catenin