Key words: Marine Mollusks -Elasmobranchs - Spermatogenesis – Sexual differentiation - Steroidogenesis - Aromatase - Spermatogonial stem cells – Cellular biology
Identification of early markers of spermatogenesis in the small spotted catshark (Scyliorhinus canicula L.).
Spermatogenesis start with the multiplication and differentiation of diploid spermatogonia and ends with the production of highly specialized haploid cells, spermatozoa. Continuous production of male gametes is dependent on the ability of spermatogonial stem cells (SSC) to renew while maintaining their stemness. This takes place within a specific microenvironment called the "niche" and involving autocrine and paracrine factors, these last ones secreted from the surrounding somatic cells. Our studies focus on the identification and functional characterization of the SSC and of the molecular players that control their self-renewal and differentiation using a Chondrichthyans model, the small spotted catshark (Scyliorhinus canicula). The identification of molecular markers is performed through proteomic and transcriptomic approaches on purified cells or testicular areas. Our studies also address the evolution of the niche of germline stem cells in Gnathostomes.
Study of sex determination in the Pacific oyster (Crassostrea gigas).
This theme is of fundamental interest for the understanding of the gonadal differentiation in the oyster during its development and the adult gametogenesis cycles. The oyster is an irregular successive protandric hermaphrodite and poor information is available about the first development of the gonads or sexual reversion occurring sometime from one cycle to another. One of our objectives is to identify conserved factors of the molecular sex determination cascade. Knowledge of an early marker will allow us to define, if present, the time-window where gonadal differentiation could be under environmental influence.