Vip3Aa及Cry1Ac对棉铃虫幼虫多种酶活力的影响

Effects of Vip3Aa and Cry1Ac on enzyme activity in cotton bollworm Helicoverpa armigera larvae

为了明确Vip3Aa的作用机制,为其作为新毒素策略重要蛋白的应用提供理论依据,本文比较了Vip3Aa、Cry1Ac对棉铃虫Helicoverpa armigera(Hübner)主要蛋白酶、解毒酶、APN活性的影响,并研究了Vip3Aa和Cry1Ac共同使用对几种酶活力的作用。室内生测结果表明,Vip3Aa对棉铃虫的杀虫效果低于Cry1Ac,但Vip3Aa对棉铃虫幼虫生长有明显的抑制作用。取食含Cry1Ac、Vip3Aa或Cry1Ac+Vip3Aa饲料的棉铃虫,总蛋白酶和类胰凝乳蛋白酶活性很快升高;但经Cry1Ac处理12 h后这2种酶活性与对照差异不显著或低于对照,而取食含Vip3Aa饲料的棉铃虫酶活力显著高于对照的时间明显延长,而且类胰蛋白酶活性也显著高于对照;表明Cry1Ac降解速度比Vip3Aa快,可能是由于降解2种蛋白参与的酶系存在差异,同时Cry1Ac+Vip3Aa混用可以延长蛋白被酶解的时间。谷胱甘肽S-转移酶和α-乙酸萘酯酶活性在棉铃虫取食含Vip3Aa、Cry1Ac或Cry1Ac+Vip3Aa蛋白的饲料后活性升高,说明这2种酶可能参与了对Cry1Ac、Vip3Aa的解毒作用。但Cry1Ac、Vip3Aa对氨肽酶活性影响不大,可能在毒蛋白发挥毒性的过程中与氨肽酶活力变化无关。

In order to clarify the activity of Vip3Aa and provide a theoretical basis for its application in the ＂New toxin strategy＂, the effects of Vip3Aa and Cry1Ac on protease, dctoxification enzymes were and aminopeptidase N （APN） activity in larvae of the cotton bollworm Helicoverpa armigera （Hfibner） were compared and the impacts of Cry1Ac ＋ Vip3Aa on these enzymes were investigated. The lethality of Vip3Aa was lower than that of Cry1Ac, but Vip3Aa had an obvious inhibitory effect on larval development. Total protease and trypsin-like enzyme activity quickly increased in H. armigera fed an artificial diet containing either Cry1Ac or Vip3Aa or Cry1Ac ＋ Vip3Aa. However, compared to the control, there was no significant difference in the activity of these two enzymes after 12 h of feeding on the Cry1Ac diet. While the period during which the activity of these two enzymes increased was dearly prolonged in larvae fed on diets containing Vip3Aa, that of the chymotrypsin-like enzyme was also higher than in the control. This indicates that the degradation rate of Cry1 Ac was faster than that of Vip3Aa, and that the enzyme systems involved in degradation could be different. Meanwhile, the diet containing Cry1Ac and Vip3Aa together extended the degradation time. The activities of glutathione-S-transferase and a-naphthalene acetate esterase increased in 1-1. armigera fed on a diet containing either Cry1Ae or Vip3Aa or Cry1Ac ＋ Vip3Aa. This indicates that these enzymes may be involved in the detoxification of Vip3Aa and Cry1Ac. However, Vip3Aa and Cry1Ac had little effect on aminopeptidase N activities, suggesting that the toxicity of the latter has no relationship to APN enzyme activity.