Meeting Abstract

P1.112  Monday, Jan. 4  Gill ionocytes ontogeny in the sea bass: from embryos to juveniles, developmental and functional aspects. SUCRE, E.; BOSSUS, M.; CHARMANTIER-DAURES, M.*; CHARMANTIER, G.; CUCCHI-MOUILLOT, P.; Equipe AEO, Univ. Montpellier 2, France; Equipe AEO, Univ. Montpellier 2, France; Equipe AEO, Univ. Montpellier 2, France; Equipe AEO, Univ. Montpellier 2, France; Equipe AEO, Univ. Montpellier 2, France mireille.charmantier@univ-montp2.fr

The ontogeny of the gill ion transporting cells has been studied in the sea bass (Dicentrarchus labrax) embryos, prelarvae, larvae and juveniles. In toto immunolocalization of the NKA in embryos revealed the presence of numerous tegumentary ionocytes clustered around the gill slits. Histological investigations suggest that these ionocytes, close to the future gill chambers, are at the origin of the ionocytes observed on gill arches and gill filaments after hatching. Triple immunocytochemical staining, including NKA, various NKCCs and CFTR, were used to evaluate the functionality and diversity of the ionocytes, in embryos and juveniles exposed to different salinities. In embryos, the early ionocytes of the gill slits were immature with the presence of NKA and CFTR and the lack of NKCC1. However, in these cells, the CFTR expression disappeared when the salinity decreases from 38 to 5 ppt. In juvenile gills, either ion excretory or ion absorptive ionocytes were detected according to the external medium salinity. At 38 ppt NKCC1 has been immunostained basolaterally and the CFTR is located in the apical crypts of the excretory ionocytes. At 5 ppt, the CFTR and NKCC1 are absent but the T4 antibody (knew to recognize both NKCCs and NCC) reveals an immunostaining in the apical crypts of the ionocytes. The results are discussed in regard to the recent findings in other teleosts.