高温胁迫和恢复对牛蛙蝌蚪及幼蛙生长、变态和抗氧化功能的影响OA

To investigate the physiological regulation of bullfrogs(Lithobates catesbeiana)under long-term heat stress,this study simulated a high-temperature and recovery environment to examine the effects of water temperature on growth,metamorphosis,and antioxidant function during the tadpole and juvenile stages.Three thousand six hundred bullfrog tadpoles at Gosner stage 25[7 d old;(0.04±0.00)g]were randomly divided into 12 tanks,with 300 individuals per tank,and reared for 80 days at water temperatures of 24,27,and 30℃,respectively.Subsequently,post-metamorphic juveniles were maintained at 24℃for an additional 56 days.The results showed that,during the tadpole stage,final body weight(FBW),weight gain rate(WGR),and specific growth rate(SGR)did not differ significantly between the 24 and 27℃groups(P＞0.05),but their values were all significantly higher than those of tadpoles in the 30℃group(P＜0.05).The male ratio and metamorphosis rate in the 27℃group were significantly higher than those in the 24℃group,but lower in the 30 ℃ group(P＜0.05).For juveniles reared at 24℃,FBW,WGR,SGR,and survival rate showed no significant differences between the 24 and 27℃groups(P＞0.05),but their values were all significantly higher than those in the 30℃group(P＜0.05).In terms of intestinal enzyme activity,protease and creatine kinase activities in juveniles did not differ significantly between the 24 and 27℃groups(P＞0.05),but both were significantly lower than those in the 30 group(P＜0.05);lipase and acid phosphatase activities in the 24℃group were significantly higher than those in the 27 and 30℃groups(P＜0.05).Regarding antioxidant indices,intestinal superoxide dismutase(SOD)and catalase(CAT)activities in the 24 and 27℃groups were not significantly different(P＞0.05),but both were significantly higher than those in the 30℃group(P＜0.05).In the liver,glutamic pyruvic transaminase,glutamic oxaloacetic transaminase,SOD,and CAT activities,as well as malondialdehyde content,did not differ significantly between the 24 and 27℃groups(P＞0.05),but all were significantly lower than those in the 30℃group(P＜0.05).The hepatic total antioxidant capacity values of juveniles in the 27 and 30℃groups were significantly higher than those in the 24℃group(P＜0.05).In conclusion,a water temperature of 27℃can promote the growth performance,metamorphosis rate,and male ratio of bullfrog tadpoles,and can enhance the antioxidant capacity of juveniles after stress,thereby improving juvenile growth performance.These findings suggest that maintaining 27℃during the tadpole stage could optimize bullfrog aquaculture in subtropical regions under summer heat waves.