Salinity effects on activity and expression of glutathione S-transferases in white sturgeon and Chinook salmon

This study evaluated the activity and expression of the glutathione S-transferase (GST) detoxification isoenzymes in juvenile white sturgeon (Acipenser transmontanus) and Chinook salmon (Oncorhynchus tshawytscha) during acclimation from freshwater (2‰) to estuarine (15‰) salinity conditions. In white sturgeon, GST activity toward 1-chloro-2,4-dinitrobenzene (CDNB) increased significantly (P=0.005; n=5) with elevated salinity, but not for the Chinook salmon (P=0.174; n=10). GST activity of both sturgeon and salmon toward ethacrynic acid (ETHA) did not significantly change with elevated salinity (P=0.516 with n=3, and P=0.125 with n=3, respectively). Expression of the GST classes, and hepatic glutathione (GSH) concentration, as determined by HPLC, also did not significantly change with increased salinity. In conclusion, overall GST activity in white sturgeon, but not Chinook salmon, is stimulated by elevated water salinity, thus electrophilic chemicals such as pesticides may be more effectively detoxified by sturgeon as they undergo seaward migration.