SALINITY ACCLIMATION IN RAINBOW TROUT: MOLECULAR AND PHYSIOLOGICAL RESPONSES

Salinity acclimation occurs in a limited number of teleost species. The rainbow trout, while having a restricted capacity to tolerate abrupt transfer from freshwater to full seawater, is capable of acclimating to gradual increases in salinity. The response to gradual salinity increases in the trout has not been fully characterized at the molecular level. Evidence for the involvement of a number of important gill transport proteins, channels and receptors during acute seawater exposure has been demonstrated in several teleost species including: Brown trout (Madsen et al. 1995), the Atlantic salmon (Singer et al. 2002) and the euryhaline killifish (Singer et al. 1998). To better characterize the acclimatory responses, we have examined changes in mRNA levels and protein content of salinity-responsive genes from the gill in rainbow trout. Juvenile trout were gradually acclimated to increased salinity over 5 days (Da