Efeito sinérgico da aclimatação térmica e hipóxia sobre as defesas antioxidantes no tambaqui (colossoma macropomum)

Abstract

Considering the imminent increase in environmental temperature, it is extremely important to see how Amazonian fish species of great economic value, such as tambaqui, will respond to climate change. To this end, the evaluation of antioxidant enzymatic activity allows a better understanding of the adaptations that fish develop to survive the variations of physicochemical parameters in their environments. To this end, the objective of the present study was to evaluate the activity of the enzymes Glutathione S-transferase (GST), Catalase (CAT), as well as the lipoperoxidation levels (LPO) and the genotoxic effect of exposure to temperature variations and the concentration of oxygen in the tambaqui. A total of 72 tambaqui juveniles were distributed in 18 experimental tanks, where 9 tanks were kept at 26 ° C and the remaining 9 tanks at 32 ° C for 28 days. After the thermal acclimatization period, the fish underwent hypoxia. Thereafter, each animal was placed in a respirometry chamber and oxygen was kept at 1.5 mgO 2 / L for 8 hours. After this time, the fish were euthanized and liver, muscle and gill samples were collected for enzymatic analyzes and blood samples for the ANE (erythrocyte nuclear anomalies) and comet assays. In the gills, none of the enzymes showed statistically significant differences. In the liver, there was significant difference only in relation to CAT. In muscle, it was possible to observe significant results in both GST and LPO. Regarding the ANE test, it was possible to verify the influence of oxygen concentration, where animals exposed to hypoxia at 26 ° C and 32 ° C had a higher frequency of abnormalities.Similar results were observed in the comet assay, where the Genetic Damage Index (GDI) was also higher in animals exposed to hypoxia, both at 26 ° C and 32 ° C. Although the results show that tambaqui has some resistance to oxidative stress related damage, the genotoxic effect of the analyzed factors is apparent. Palavras-chave: Tambaqui, Hypoxia, Oxidative stress, Genotoxicity