INTERACTIVE EFFECTS OF WARM ACCLIMATION, LOW SALINITY, AND TROPHIC FLUORIDE ON THE LIVER METABOLISM OF THE ANTARCTIC FISH Notothenia rossii

Abstract

All Antarctic vertebrates are directly or indirectly exposed to high levels of uoride present in the exoskeleton of krill. Absence of uorosis in these organisms indicates high tolerance to this halogen. e present study investigated the e ect of uoride on the hepatic metabolism of N. rossii Antarctic sh. Levels of the enzymes superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GRED) and arginase (ARG) were determined. Specimens were subjected to eight di erent thermo-saline-trophic conditions, involving the interaction between two temperatures (0 o C or 4 o C), two salinities (20 or 35) and two trophic conditions (with or without uoride). Although uoride did not modulate the levels of SOD, CAT and GRED, low salinity reduced hepatic levels of GRED, revealing that this saline condition may be inducing oxidative stress. Fluoride raised arginase levels except in the case of the thermo-saline condition of 4-20. In relation to antioxidant defense, the liver of N. rossii sh was found to be more resistant to toxic e ects of uoride than the liver of non-Antarctic shes.