The Response Of Penaeus Vannamei To Waterless And Low Temperature Stress And Equipment For Waterless Transportation

Live aquatic products always have delicate and elastic texture,delicious taste,high safety and high nutrition,which occupy an important role in the aquatic product market.Because shrimp culture has regional and climatic characteristics,live transportation is the guarantee for the wide supply and sale of live shrimp.Waterless live transportation is of great significance to the aquaculture and supply of live shrimp because of its high efficiency and convenience.In this study,shrimp(Penaeus vannamei)were cooled at 13? for 3 min,stored in oxygen at 15? for 12 h,and then revived in water at 25 ? to stimulate the process of live transportation without water.The oxidative stress and antioxidant responses,immune responses,glucose metabolism and related neuroendocrine responses were studied under the waterless and low temperature stress.The brief results are as follows:1.The survival rate of shrimp were counted,ultrastructure of hepatopancreas cells were observed and activities of superoxide dismutase(SOD),peroxidase(POD),catalase(CAT),glutathione peroxidase(GSH-Px),antisuperoxide anion free radicals(ASAFR),total antioxidant capacity(TAOC),reactive oxygen species(ROS)production,content of malondialdehyde(MDA)and relative mRNA expressions of CAT and GSH-Px in the hemolymph and hepatopancreas of shrimp were determined to study the oxidative stress and antioxidant responses of live shrimp(Penaeus vannamei)under waterless and low temperature stress.After 12 h,the survival rate of shrimp under waterless transportation stress was still 86.67%.Though there were slight distortions of some organelles in hepatopancreas cells,the alteration was reversible.The activities of SOD,POD,CAT,GSH-Px,TAOC,ROS production and the relative mRNA expressions of CAT and GSH-Px increased following the cold shock and reached peak levels after 3 or 6 h of storage.There was no significant difference(P?0.05)between the fresh and the revived shrimp in SOD,POD,GSH-Px,TAOC,ROS,MDA and relative mRNA expressions of CAT and GSH-Px.MDA level was tissue-specific.The hepatopancreas seems to have a greater ability to defend against damages than hemolymph.These results revealed that waterless and low temperature stress caused significant oxidative and antioxidant responses,but did not lead to irreversible damages to shrimp.2.The amounts of haemocytes were counted,ultrastructure of haemocytes were observed and the activities of phenoloxidase(PO),lysozyme(Lys),gamma-glutamyl transferase(GGT),content of glutamine(Gln)and relative mRNA expressions of prophenoloxidase(proPO),?-1,3-glucan binding protein(LGBP),ferritin(FcFer)and glucose regulated protein 78(GRP78)in hemolymph of shrimp were determined to study the immune responses of live shrimp(Penaeus vannamei)under waterless and low temperature stress.Immune system of shrimp was active during the waterless transportation.The activities of PO,Lys,GGT,content of Gin and relative mRNA expressions of proPO,LGBP,FcFer and GRP78 all increased and reached peak levels after 3 h to 9 h of storage to alleviate stress and prevent from damages caused by waterless transportation stress.All the indicators decreased and maintained at relatively stable levels in the late period of experiment because of the damage caused by long time of transportation stress.The total hemocyte count(THC)and gene expressions of proPO,FcFer and LGBP at the end of waterless transportation were significantly lower(P<0.05)than the fresh values while no significant difference(P?0.05)was found between the revival results and the fresh values for the activities of PO,Lys,GGT,content of Gln and the gene expression of GRP 78.Besides,the microstructures of haemocytes were still intact,and there were only slight distortions of some organelles and the nuclear membrane.Waterless and low temperature stress activated the immune system initially and influenced the efficacy of it after long time of stress,but may not lead to irreversible damages of shrimp.3.The contents of glucose(Glu)and lactic acid(LD),activities of lactate dehydrogenase(LDH),phosphofructokinase(PFK),hexokinase(HK),pyruvate kinase(PK),crustaceanhyperglycemic hormone(CHH)and relative mRNA expression of CHH in hemolymph of shrimp were determined to study the glucose metabolism and related neuroendocrine responses of live shrimp(Penaeus vannamei)under waterless and low temperature stress.Live transportation led to changes of glucose metabolism and neuroendocrine system of shrimp.The contents of Glu,activity of CHH and gene expression of CHH increased rapidly after cold shock and then decreased after 3 h of transportation.Hormone was sensitive to stress hormone levels and then caused alterations in glucose metabolism.In the late period of transportation,energy consumption and adaption to the environment led to the decreasing trend.With the prolong of transportation,LD content and LDH,HK,PK,PFK activities increased significantly after 3 h of transportation and reached the peak at 6 h,and then decreased to a stable level.3-6 h of waterless transportation was the active period of anaerobic metabolism and long time of stress may cause adaptability or damage to the metabolic system,leading to the decrease after 6 h.After revival,LD content and LDH activity were still higher than the initial levels before treatment and the content of Glu was lower,while the activities of HK,PFK,PK,CHH and CHH gene expression level did not show significant difference(P?0.05)from the initial values.Short term of revival in water could not completely eliminate the anoxic effects and energy loss under waterless and low temperature stress,but the effects of waterless and low temperature stress on the glucose metabolism and neuroendocrine system of shrimp were restorable.4.Based on the environmental needs of live transportation without water,the technical equipment needed for capture and transportation of fish and shrimp were designed,including a shrimp cage used for capture and transportation,a simple waterless transportation box for fish and shrimp as well as a professional waterless transportation box.The shrimp cage used for capture and transportation can reduce stress from repeated transfers from nets to containers and protect from injuries.Waterless transportation box can provide proper environments(temperature,humidity and oxygen)for live shrimp with reasonable layouts.These technologies and equipment can meet the environmental needs of the shrimp during waterless transportation,reduce injuries and improve transport efficiency,which can provide technical support for the practice of waterless transportation.