Meeting Abstract

P1.60  Wednesday, Jan. 4  Osmoregulation in the peneid shrimp Litopenaeus stylirostris: Ontogeny and localization of transporters PHAM, D.; CHARMANTIER, G.; BOULO, V.; GROUSSET, E.; WABETE, N.; CHARMANTIER-DAURES, M.*; Ifremer New Caledonia; Univ. Montpellier 2, France; Univ. Montpellier 2, France; Univ. Montpellier 2, France; Ifremer New Caledonia; Univ. Montpellier 2, France

The ontogeny of osmoregulation was investigated in L. stylirostris by studying salinity tolerance, osmoregulatory capacity and the localization of Na/K-ATPase (NKA) in the branchial chamber organs throughout development. Shrimps at different larval and postlarval stages were exposed to a range of salinities (0 to 45 ppt). Survival rates exceeded 80% at salinity over 25 after 24 hours at all stages. At salinities below 25, salinity tolerance was higher in nauplii and zoeae than in mysis. Postlarvae were able to withstand lower salinities, e.g. 6 at PL9, but they were more sensitive than larvae to salinities over 35. Zoea and mysis slightly hyper-regulated at all tested salinities. After metamorphosis, postlarvae progressively acquired the adult pattern of hyper-hypo-osmoregulation. Immunolocalization of NKA showed a sequential involvement of the different branchial organs: first, pleurae in zoeae, then branchiostegites in mysis and finally the epipodites in postlarval stages. No immunoreactivity was observed in the developing gills at any stage. In late juveniles immunolocalization of NKA, co-transporter NKCC1 and CFTR was assessed in gills, epipodites and branchiostegite at two salinities (12 and 30). NKA was present at 12 and 35 in all organs. CFTR was mostly localized in the branchiostegites at 35. NKCC1 was detected in the gills at both salinities, but in cells different from those with NKA. In conclusion the gills are involved in osmoregulation later than metamorphosis and a cellular complex may be involved in their osmoregulatory function.