The Correlationp Among Growth, Disease-resistant , Stress-resistance And Enzymatic Activity Of Immunity Of Penaeus Monodon

Penaeus monodon is also called black tiger shrimp and grass shrimp. They are widely distributed in the western Pacific and most of the Indian Ocean.In China,we can see them along the coast of Zhejiang, Fujian, Guangdong, Hainan, Guangxi and Taiwan.The shrimps have many advantages,such as fast growth, mixed diet, individual large, delicious meat and so on.It was once the main type of shrimp farming in China.In recent years, the white spot virus (WSSV) in the large-scale outbreak and the deterioration of water environment result in a large number of black tiger shrimp aquaculture production cuts.So new varieties of shrimps which have a fast growth, disease resistance and stress tolerance is needed for the sustainable development of Penaeus monodon.In this study,we analysised the ability to resist WSSV among different families of Penaeus monodon.we also aimed to find the relationship between growth and resistance to wssv. With the families of Penaeus monodon as the research object,15 families of Penaeus monodon were produced by completely different shrimps.Through experiment of growth and resistance to wssv,the family 072 with higher special growth rates and lower resistance to wssv and families 242,007,480 with lower special growth rates and higher resistance to wssv were selected.With another 10 families of Penaeus monodon,we also find a obvious difference of special growth rate among the 10 families after the 30-day growth test. 3941 and 370 families grow the fastest and 017 and 4822 grow the slowest . The specific growth rate of families were negatively correlated with the activities of phosphatase(ACP), superoxide dismutase(SOD), phenoloxi- dase(PO). The activities of SOD and ACP had significant correlation with the specific growth rate and coefficients of correlation were -0.515** (P<0.01)and -0.441* (P<0.05) .The second study was aimed to find the characteristics of death and the trend of immune factors of wssv-infected Penaeus monodon. It's found that shrimp's mortality peak appeared around 50 hours and white spots were occurred on most died shrimps after 60 hours.The activities of PO,POD,SOD and ACP in blood was lower at first,then higher and lower at last and it had a peak at 60 hours after wssv-infected. The activity trends of SOD and ACP in liver and muscle was similar to it in blood. But the activities of SOD and ACP in liver was higher than that in muscle.The mean SOD activities of higher resisting disease family group was significantly higher than the mid-resisting disease family group (P<0.05)and bad resisting disease family group(P<0.01).The mean ACP activities of resisting disease family group was significantly higher than the bad resisting disease family group(P<0.05).The mean AKP activities of higher resisting disease family group had no significantly difference with the mid-resisting disease family group and bad resisting disease family group but was still higher.The activities of SOD and ACP had significant correlation with the survival time for resistance to wssv and coefficients of correlation were 0.936 (P<0.01)and 0.826(P<0.05) .Finally,we want to find out the trends of PO,ACP and SOD of Penaeus monodon under the low temperature stress and high ammonia stress.When temperature dopped from 27℃to 20℃,The activities of ACP and SOD first increased and then decreased;The activities of PO reduced prolonged cold stress.When under the high ammonia stress, the activities of ACP increased prolonged the high ammonia stress, the activities of SOD increased in 0 h -8 h and then decreased, the activities of PO reduced in 0 h-48 h.After 48 hours under the low temperature stress,we found out that family 3941 and 017 had a high growth rate and low immunity,077 and 4822 had a low grotwh rate and high immunity,370 had both high growth rate and high immunity. When under high ammonia stress, the 10 families had a similar situation as under the low temperature stress.