Effects Of Temperature And Salinity On Enzymatic Activi Ty Of Digestive And Immunity In Lutraria Sieboldii Reeve

Lutraria sieboldii Reeve is a high economic value shellfish. This paper studied the effects of temperature and salinity on two kinds of digestive enzymes and three kinds of immune enzymes in Lutraria sieboldii Reeve, finding the optimum temperature and the optimum salinity of two kinds of digestive enzymes and three kinds of immune enzymes by single factor method, analyzing the impact of the combined effect of temperature and salinity on digestive enzymes and immune enzymes through central composite design and response surface methodology. The main results were as follows:1. Single temperature factor experiments showed that pepsin and amylase enzymes activity went up as the temperature added and got suppressed when lowing the temperature within a certain temperature range(12~27℃), but beyond the optimum temperature range,the high temperature would suppress it after some time. Low temperature and high temperature stress would lead to increased activity in SOD, POD and ACP activity, which was significantly higher than group 17℃ and group 22℃. As the time went by, immune activity in low and high temperature group decreased and all drop back to normal level, but group 32℃ had a higher mortality rate, significantly higher than 27℃ and 12℃ group.Combining the digestive enzymes, immune enzymes and mortality data, 17~27℃ was the optimum temperature range to Lutraria sieboldii Reeve.2. Single salinity factor experiments showed pepsin and amylase enzymes activity increased under low salt and high salinity stress in short term. High salinity caused more absorption to maintain osmotic pressure and low salt caused pipe enlargement and more food intake, which consumed more energy to maintain osmotic pressure. After a period of time, digestive enzyme activity began to decline in high salinity stress group; group 23 and28 were significantly higher than the other group; the group of low salinity beyond their range gradually died. Both low salinity and high salinity stress would lead to increased activity in SOD, POD and ACP. After a period of time, high salinity stress groups’ immune activity decreased gradually. According to the digestive enzymes, immune enzymes and mortality data, the optimum salinity range was 23 to 33.3. Studied the different temperatures(12℃~32℃) and different salinities’(18 to 38)interaction effects on two kinds of digestive and three kinds of immune enzymatic.Established quantitative relational model. Experimental results were as follows:Primacy effect of temperature on protease activity was extremely significant(P<0.01),on amylase was significant(P<0.05). Primacy effect of salinity on protease and amylase were extremely significant(P<0.01). Thermohaline interaction effects on two digestive enzyme activity were extremely significant(P<0.01). Quadratic effect of temperature on two digestive enzymes activity were extremely significant(P<0.01). Quadratic effect of salinity on two digestive enzyme activities were extremely significant(P<0.01). In the established quantitative relational model, the coefficient of determination of protease and amylase regression equations were 0.9998 and 0.9870; correction coefficients of determination were 0.9996 and 0.9741; prediction coefficient of determination were 0.9979 and 0.8693. Four equations were fitting high and appropriate.Primacy effect of temperature on SOD and ACP were extremely significant(P<0.01),on POD was significant(P<0.05). Primacy effect of salinity on POD is extremely significant(P<0.01); no significant effect on the ACP. Thermohaline interaction effects on three immune enzymes activity were extremely significant(P<0.01). Quadratic effect of salinity on ACP and SOD were extremely significant(P<0.01), no significant effect on the POD. Quadratic effect of salinity on two digestive enzyme activities were extremely significant(P<0.01). In the established quantitative relational model, the coefficient of determination of SOD、POD and ACP of regression equations were 0.9770、0.9827 and0.9884; correction coefficients of determination were0.9541、0.9655 and 0.9768; prediction coefficient of determination were 0.7794、0.8603 and 0.8794. Four equations were fitting high and appropriate.