急性高温胁迫对星康吉鳗血清生化指标及组织抗氧化能力的影响OA

Temperature is an important environmental factor affecting the growth and reproduction of fish.As poikilothermic animals,fish lack a thermoregulatory mechanism;therefore,their body temperature is mainly influenced by the aquaculture water temperature.Conger myriaster is a fish with high nutritional and economic value and enormous market potential.C.myriaster shows great potential for artificial cultivation and offers considerable economic promise.Consequently,it has attracted increasing attention from the global research community.This study was conducted to investigate the effect and regulatory mechanism of acute high temperature stress on serum biochemical indexes and antioxidant enzyme activities of different juvenile C.myriaster tissues.In this study,juvenile C.myriaster[body weight:(70.7±8.4)g]were selected;the acute heat stress experiment was set up with five temperature points,namely 24℃(R24,the control group),26℃(R26),28℃(R28),30℃(R30),and 32℃(R32).With prolonged stress times(0,1,6,12,and 24 h),behavioral responses;respiratory frequency;and signs of juvenile C.myriaster were observed during heating and constant temperature stress in each group.Serum superoxide dismutase(SOD),catalase(CAT),alkaline phosphatase(AKP),aspartate aminotransferase(AST),and alanine aminotransferase(ALT)activities and total protein(TP)content in the control and acute high temperature stress groups and SOD,CAT,and glutathione peroxidase(GPx)activities in the liver,intestine,and gill tissues were detected at each time point.The results showed that during the heating process,operculum opening and closing frequency of juvenile C.myriaster in the acute high temperature stress group gradually increased with temperature and stress time.Mucus secretion on the body surface of juvenile C.myriaster changed in the acute high temperature stress group.No death occurred in the R26,R28,and R30 groups during the heating process and constant temperature stress.In the R32 group,death occurred during the heating process;mortality rate reached 100%at 0.5 h after reaching the set temperature.Serum SOD,CAT,AKP,AST,and ALT activities and TP content of juvenile C.myriaster in the acute high temperature stress group and SOD and GPx activities in the liver,gills,and intestine were significantly different from those in the control group at each time point(P<0.05).SOD activity in the serum,liver,gills,and intestine of juvenile C.myriaster in the acute high temperature stress groups exhibited a trend of first increasing and subsequently decreasing with increasing stress duration.CAT activity in the R26 group liver and intestine at 24 h of stress was not significantly different from that of the control group(P>0.05).The behavioral stress response,serum biochemical indexes,and tissue antioxidant capacity of juvenile C.myriaster were relatively less affected below 30℃,indicating that physiological state of the juvenile C.myriaster was still self-regulating at this temperature.Therefore,in the factory-scale recirculating water aquaculture production process,the water temperature for juvenile C.myriaster should be maintained at 24‒30℃to avoid stress effects caused by high summer temperatures or acute temperature fluctuations,thereby increasing aquaculture efficiency.