南美白对虾血蓝蛋白对酚氧化酶活性的影响

Variation of phenoloxidase activity affected by hemocyanin in shrimp Penaeus vannamei

以采自厦门的南美白对虾(Penaeusvannamei)为研究对象,运用病原菌人工感染、血蓝蛋白浓度和酚氧化酶(phenoloxidase,PO)活性测定等方法探索南美白对虾血蓝蛋白在体内、外对其血清酚氧化酶活性的影响。结果表明,南美白对虾人工感染副溶血弧菌后,其血淋巴中血蓝蛋白浓度和PO活性的变化趋势基本一致。在体外实验中将一定量的血蓝蛋白重组蛋白添加至血清中,其PO活性可明显升高;但同时添加血蓝蛋白重组蛋白和E.coliK12超声破碎液后,其PO活力反而降低。研究提示,血蓝蛋白在一定范围内确实可以正反馈调节PO活性,但在细菌等干扰之下,其又可表现出一定的负反馈抑制活性。

It has been confirmed that hemocyanin is a kind of important multifunctional protein found in the hemolymph of both arthropod and mollusk. And phenoloxidase is a type of vital immune protein in invertebrate. Recently,interest has been focused on comparative research between hemocyanin and phenoloxidase. In the paper,a preliminary study was made to characterize the variation of phenoloxidase activity affected by in vivo hemocyanin and in vitro hemocyanin recombinant protein in shrimp Penaeus vannamei obtained from Xiamen. The methods of artificial infection by V. parahaemolyticus and measurement of both concentration of hemocyanin and phenoloxidase activity were used. The results showed that the variational trend of hemocyanin's concentration was similar to that of phenoloxidase activity after the shrimp was infected by V. parahaemolyticus,both of which increased to their maximum in 24?h,then descended slowly,finally came back to normal level in 36?h. In comparison with control group in vitro, the shrimp serum's phenoloxidase activity increased obviously after hemocyanin recombinant protein was added in at the concentration of 200?μg/mL or ultrasonic solution of E. coli K12 at the concentration of 35?mg/mL. However,when both hemocyanin recombinant protein and ultrasonic solution of E. coli K12 were added into the shrimp serum, its phenoloxidase activity descended immediately. It suggests that hemocyanin can adjust the phenoloxidase activity by means of positive feedback,but it also can adjust the phenoloxidase activity by means of negative feedback when its reactive solution is involved in some bacteria. In summary,these results are the latest discovery in the field of the immune function of hemocyanin and phenoloxidase,which will be helpful for elucidating the immune mechanism of hemocyanin and interrelation between hemocyanin and phenoloxidase.