Physiological And Biochemical Responses Of Paramisgurnus Dabryanus To Temperature And Crowding Stress

In order to study the effects of temperature stress and crowding stress on aquatic animals,Paramisgurnus dabryanus was used as a test object to conduct temperature stress and recovery,and low temperature crowding stress test.The experimental fish were subjected to 12 hours of four different temperature stress tests and 24 hours recovery test to determine the changes in some physiological and biochemical indicators of the test fish;and by testing the fish for 8 hours at three different densities under low temperature stress,some physiological and biochemical indicators of the test fish were determined.The change.1.Effect of temperature stress on the immunity of P.dabryanusThe activities of SOD,CAT,LZM and AKP were significantly inhibited under the influence of sudden changes in temperature(P<0.05),and the contents of MDA,AST and ALT were significantly increased in temperature stress(P<0.05);During the period,the activities of SOD and CAT in the experimental groups gradually increased.The activity of LZM and AKP in the high temperature group maintained the level at the end of stress,while the activities of LZM and AKP in the cool group and the low temperature group gradually increased,and the contents of MDA,AST,and ALT gradually decreased.2.Effects of temperature stress on energy metabolism of P.dabryanusDuring the stress period,the activity of HK,PK,LDH and SDH increased significantly at high temperature(P<0.05),decreased significantly at low temperature(P<0.05),and the blood glucose level decreased significantly(P<0.05).The content of TG and CHOL first decreased and then increased.In the recovery period,the activity of HK,PK,LDH and SDH in all experimental groups gradually returned to the level of the control group,and the blood glucose levels in each group were lower than the initial state,there was no significant difference between the groups(P> 0.05);After returning to the control group,the CHOL content in the hypothermia group returned to the control group,while the high-stability group and the cooling group remained lower than the control group.3.Effect of crowding stress on the immunity of P.dabryanusThe activity of SOD,CAT and LZM in the early stage of stress increased significantly(P<0.05),but decreased slightly afterwards,but it was still significantly higher than the level before the experiment(P<0.05).The AKP activity increased first and then decreased.At the end of the experiment(8h)Basically returned to the control group level.The MDA content decreased significantly after crowding stress(P<0.05).Serum AST activity significantly decreased(P<0.05)at the beginning of stress(1h),and then quickly returned to the control group;serum ALT activity increased significantly with the prolongation of stress time(P<0.05).4.Effects of crowding stress on energy metabolism of P.dabryanusThe activity of HK,PK,LDH,blood glucose and serum cortisol were significantly increased(P<0.05),and the activity of SDH was significantly decreased(P<0.05).Serum TG and CHOL levels were not affected during the trial.Studies have shown that low-temperature crowding stress causes a rapid increase in the rate of sugar metabolism in the large loaches.The trend of changes in the high-density group and the anhydrous group is similar.Temperature stress reduces the antioxidative capacity and non-specific immunity of the parafilm loach,and the irreversible damage to the body's immune system is caused by high temperature stress,and the cold stress damage can be restored.High temperature mutations increase the metabolic rate of the fish,and the low temperature mutation reduces the metabolic rate.When the temperature is restored,the body's metabolism returns to normal levels.Under the stress of low temperature crowding,the stress response was caused by the parasitism of the big scales,and the immunity of the experimental fish body was rapidly increased and the energy metabolism was accelerated.