| Summary: | The European eel maintains strict osmoregulation of body fluids while migrating between freshwater (FW) and sea water (SW) environments. Microarray studies on salinity adaptation in the eel highlighted genes responsible for the transport of a variety of solutes known to act as osmolytes in mammals. SMIT1 and HMIT genes, implicated in myo‐inositol transport, were isolated, cloned and sequenced. Following these initial studies, other genes involved in osmolyte transport and regulation, including the taurine transporter (TauT) and TonEBP, were cloned and sequenced, and their role in salinity adaptation was investigated. Q‐PCR was used to determine gene expression in the major osmoregulatory tissues (intestine, kidney and gill) at 6 hours, 2, 7 days and 5 months after transfer of eels to SW. In the intestine, SMIT1 was up‐regulated following 2 days SW transfer, however increases in TonEBP expression were only found 5 months after salinity transfer. In the kidney, HMIT, TauT and TonEBP mRNAs were up‐regulated 7 days after fish acclimation to salinity. No changes in the expression of any of these genes were observed in the gill. These studies have revealed differential tissue expression of key osmolyte transporters and the TonEBP transcription factor in the eel during salinity acclimation indicating potential roles in the long term adaptation of eels to the SW environment.
|
|---|