| Giant tiger prawn(Penaeus monodon)is an important fishing and breeding highquality economic shrimp in the coastal areas of China.Due to the decline of wild resources of P.monodon off the coast of China,P.monodon is also an important breed of excellent breeding and release in China.In the process of releasing,and culturing,juvenile prawns are often stimulated by high density,handling,fishing,low and high temperatures stress.After experiencing the above stresses,the physiological and metabolic balance of juvenile P.monodon was broken,resulting in damage to its tissues,consumption of energy storage materials,and even sudden death,which severely affected its release and aquaculture survival rates,and adversely affected the economic benefits of P.monodon releasing and culturing.Therefore,it is necessary to explore the physiological and metabolic changes of the releasing-size P.monodon after being stimulated during transportation,in order to optimize ploys of seeds transporting,and to guarantee the healthy of the releasing shrimps,so as to improve Economic benefits of culturing and releasing.This study analyzes the antioxidant and respiratory metabolic capacity of juvenile prawns after exhaustive exercise and the changes in antioxidant and respiratory metabolic capacity of juvenile prawns during transport,as well as the density of different individuals and water bodies transported.The effect of temperature on the antioxidant capacity of juvenile P.monodon,explored the physiological response mechanism when it was stimulated by exhaustive exercise and transport stress,and analyzed the degree of damage caused by transport parameters to the body of juvenile shrimp,and screened out suitable transport parameters for reference of actual production work.(1)Changes in antioxidant capacity and respiratory metabolic capacity of juvenile P.monodon after exhausted exerciseDue to the fishing and attack stress that often occurs during the P.monodon breeding process,the juvenile shrimp(2.0 ± 0.4 cm)of the breeding and releasing specification was used as the research object.The oxidative capacity and the law of respiration and metabolism provide scientific basis for its aquaculture production and proliferation and releasing.The results showed that at various recovery time points after exhaustion,the total protein concentration(TP)and lactic acid concentration(LA),aspartate aminotransferase(AST),alanine aminotransferase(ALT),and lactic acid There were significant differences in dehydrogenase(LDH)and succinate dehydrogenase(SDH)activities(P <0.05),significant differences in LA and LDH activities in abdominal muscles(P <0.05).TP of heaptopancreas was significantly higher than the control group after 4 hours of recovery,and returned to the control group at 48 hours;LA was significantly higher than the control group after 12 hours of recovery,and returned to the control group at 24 hours;AST and ALT activities after exercise Significantly increased in the 8th to 12 th hours,and returned to the control group level in the 24 th hour;LDH and SDH activities continued to increase,significantly higher than the control group after 12 hours of recovery,and returned to the control group level after 48 hours.Muscle glycogen mass concentration(GLY)decreased significantly after exercise,and returned to the control group level after 12 hours of recovery;LA significantly increased after exercise,and decreased to the control group level after 8 hours;LDH activity increased significantly after exercise.It continued to increase during the 12 th hour,and was still significantly higher than the control group at the 72 nd hour.Activity of superoxide dismutase(SOD),catalase(CAT),peroxidase(POD)and glutathione peroxidase(GSHPx)in juvenile shrimp,total antioxidant capacity(T-AOC)and malondialdehyde(MDA)contents were not significantly different from those in the control group;SOD,CAT,POD activity,MDA content,and T-AOC continued to decline,and GSH-Px activity did not change significantly from 1 to 12 hours.At 24 hours,SOD,CAT,and POD activities were significantly reduced,and GSH-Px activity,MDA content,and T-AOC were significantly increased;at 72 hours,SOD,CAT activities were still significantly lower than those of the control group,and GSH-Px,POD activities and MDA content returned to the control group,T-AOC was significantly higher than the control group.The enzymatic antioxidant system of juveniles was not activated during exhaustive exercise;the antioxidant capacity of juveniles was low within 24 h after exhaustive exercise and should not be stimulated again;the antioxidant capacity of juveniles was exhausted,it increased significantly after 24 h and remained for a long time.The anaerobic metabolism of juvenile shrimp is significantly enhanced after exhaustive exercise,and exhaustive exercise can be performed again after 8 hours;the liver and pancreas are organs that eliminate metabolites of juvenile shrimp and play an important role in the recovery of respiratory metabolism after exercise.(2)Changes in antioxidant capacity and respiratory metabolic capacity of P.monodon during transportIn the multiplication and releasing of P.monodon and its breeding,the transport of its seed is an inevitable part.In order to investigate the physiological and metabolic changes of juveniles P.monodon(2.0 ± 0.4 cm)during transportation,this study conducted a simulated plastic bag transport experiment of juveniles P.monodon for 5 hours in a laboratory environment,and determined changes in transport water quality,physiological indicators of antioxidant capacity and respiratory metabolic physiological indicators in juvenile prawns.The results show that during transportation,the DO,ammonia nitrogen and nitrite concentrations of the transport water are in a safe range.With the change of transportation time,there were significant differences in the overall SOD activity and GSH level of juvenile prawns(P <0.05),and there were extremely significant differences in TP,GLY,LA,AST,ALT,LDH,and SDH activities in muscle and hepatopancreas(P <0.05).The mass concentration of SOD activity,GSH and TAOC in juvenile shrimp increased significantly after undergoing packaging,and have been significantly higher than those in the control group level since then.TP of Hepatopancreas decreased significantly at 1 hour of transport;muscle TP gradually increased during transport,and was significantly higher than the control group after 1.5 hours;liver GLY decreased significantly after undergoing packaging,and did not recover afterwards;muscle GLY at 1-1.5 hours was significantly increased,higher levels of control group.LA and AST activities of hepatopancreas increased significantly at 1.5 hours,and then gradually decreased;hepatopancreas ALT activities gradually decreased during transport,and were significantly lower than the control group at 5 hours;hepatopancreas LDH activities were extremely significant at 4 hours Increased;hepatopancreas SDH activity increased significantly at 1.5 hours,and then decreased to control group levels;LA,AST,ALT,LDH and SDH activity of muscle gradually decreased to levels lower than those in the control group during transportation.From the analysis of the results,the stress of the packaging operation stimulated the antioxidant system of the juvenile P.monodon;during transportation,the body can maintain the metabolic homeostasis by consuming energy storage substances in the liver and pancreas,and the metabolic activities in the muscles are weakened and stored free energy substances in the body.(3)Effect of transport density differences on antioxidant capacity recovery of P.monodonIn order to investigate the suitable transport density of P.monodon for proliferation and releasing,as well as the recovery of the physiological response of the juveniles prawns after undergoing transport stress of different densities,this study took juveniles P.monodon(2.0 ± 0.4cm)as experimental objects,design 5 density groups(D1-200 ind,D2-250 ind / L,D3-300 ind / L,D4-400 ind / L,and D5-500 ind / L)to simulate plastics in a laboratory environment Bagging process,the transportation process lasts 5 hours.After the transportation,the water quality parameters of each group of transportation water body and the anti-oxidation index in the liver,pancreas and abdominal muscles of juvenile shrimp were measured.The results showed that different transport densities and different recovery times after transport had significant interactions on antioxidant physiological indexes in juvenile hepatopancreas and muscle(P <0.05).The DO,ammonia nitrogen concentration and nitrite concentration in the transport water of each density group are all in a safe range.The ammonia nitrogen concentration and nitrite concentration are increased with the increase of the transportation density.TP levels of hepatopancreas in all groups decreased after transportation,and the decline was directly proportional to the transportation density,and all recovered to the control group level at 24 hours.The hepatopancreas SOD activities of the D4 and D5 groups increased significantly after transportation and remained at a high level;the SOD activities of the D1 and D2 groups showed a downward trend during the subsequent recovery process.The hepatopancreas GSH levels of D4 and D5 decreased significantly after transport,and the GSH levels in all density groups showed an upward trend afterwards,reaching a level significantly higher than the control group at 72 hours.Hepatic and pancreatic T-AOC in all groups decreased significantly after transportation,and returned to the control group level at 72 hours.Hepatic and pancreatic MDA levels in each group decreased significantly after transportation and remained low afterwards.The muscle TP level increased after transportation,and the increase was inversely proportional to the transportation density,and decreased to the control group level at 48 hours;SOD activity,GSH levels,and T-AOC in muscles of all density groups appeared after transportation The decline is proportional to the density,and is significantly lower than the control level during the recovery process.The muscle MDA levels in each group decreased after transportation,and the decline was inversely proportional to the density,and they did not increase again during recovery.The experimental results show that the difference in transport density has a significant effect on the antioxidant stress of juveniles.A high transport density can weaken the antioxidant capacity of juveniles.Under the condition that the transport temperature is 25 ° C for 5 hours,the transport density of juvenile prawns should be 300-400 ind / L.(4)Effects of transport temperature differences on the antioxidant capacity recovery of P.monodonIn this study,juvenile P.monodon(3.0 ± 0.4 cm)was used as an experimental object to investigate the recovery of physiological responses of juvenile P.monodon after transport stress at different temperatures.Design 5 temperature groups(T1-15 ?,T2-20 ?,T3-25 ?,T4-30 ? and T5-35 ?)to simulate the process of transporting juvenile prawns in plastic bags in a laboratory environment and The transport process lasts 5 hours.After the transportation,the water quality parameters of each group of transportation water and the anti-oxidation index in the liver,pancreas and abdominal muscles of juvenile prawns were measured.The results showed that different transport temperatures and different recovery times after transport had very significant interaction effects on antioxidant physiological indexes in the liver,pancreas and muscle of young shrimp(P <0.01).Both T4 and T5 groups had higher mortality of juvenile shrimp,and the ammonia nitrogen concentration and nitrite concentration in each temperature group increased with the increase of transport temperature.hepatopancreas TP in the T5 group decreased significantly after transportation.The TP in all treatment groups increased and decreased during the recovery process.The TP in the T4 and T5 groups was significantly lower than the control group at 72 hours.The hepatopancreas SOD activity in the T1,T2,and T4 groups was significantly reduced after transportation,and it did not return to the control group at 72 hours.hepatopancreas GSH levels in the T2,T3,and T4 groups decreased after transport,and the T5 group significantly increased.Each group recovered to a higher level than the control group at 48 hours.The T-AOC in each group decreased significantly after transportation,and the T-AOC in the T5 group recovered to the control group level at 72 hours.Hepatic and pancreatic MDA levels in the T1,T4,and T5 groups increased significantly after transport,and returned to the control group level at 24 hours.Except for T1,the muscle TP in each group increased significantly after transportation and maintained for a long time.Except for T1,the muscle SOD activity of each group was significantly reduced after transportation,and the T1 group was significantly increased,and they all returned to the control group level at 72 hours.Except for T1,the muscle GSH levels in each group were significantly reduced after transportation.The T1 group was significantly increased from the 1st to the 8th hour of recovery,and the GSH level of each group was lower than that of the control group at the 72 nd hour.The muscle T-AOC of each group was significantly reduced after transportation,and was always lower than that of the control group.The MDA levels in the T2,T3,and T4 groups decreased significantly after transportation,and the MDA levels in the T1 and T4 groups increased significantly at 8 and 12 hours,respectively,and were lower than the control group at 72 hours.The results show that both high temperature and low temperature transportation can weaken the antioxidant capacity of juvenile shrimp,but low temperature transportation is more conducive to ensuring that the energy storage material in the transported juveniles is not consumed,thereby improving the survival rate of juveniles.Under the condition that the transportation density is 400 ind / L and the transportation time is 5 hours,the temperature for transporting juvenile prawns in bags should be 15-20 ° C. |
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