赤拟谷盗乙酰胆碱酯酶生化及毒理学特性研究

为了阐明赤拟谷盗Triboliumcastaneum(Herbst)]体内乙酰胆碱酯酶(AChE)在其各虫态间的变化关系,以期为该虫的综合治理提供一定的理论依据,本试验采用微量滴度酶标板法,分别对其10d龄和20d龄幼虫、蛹及成虫体内AChE的生化及毒理学特性进行了较为系统的研究。结果表明,赤拟谷盗各虫态AChE酶源蛋白含量、酶活力和比活力差异显著,酶源蛋白含量从低到高依次为:10d龄幼虫<20d龄幼虫<成虫<蛹;AChE活力和比活力依次为:成虫<蛹<10d龄幼虫<20d龄幼虫。酶动力学分析发现,AChE米氏常数Km值大小依次为:蛹<成虫<10d龄幼虫<20d龄幼虫,但成虫和蛹之间的差异不显著。此外,幼虫AChE的最大反应速度Vmax亦显著高于成虫和蛹。通过对幼虫AChE离体抑制作用测定表明,毒扁豆碱、马拉氧磷和西维因对20d龄幼虫的抑制中浓度I50均高于10d龄幼虫,说明20d龄幼虫体内的AChE对3种抑制剂的抑制作用更不敏感。

Toxicological and Biochemical Characterizations of Acetylcholinesterase in Tribolium castaneum (Herbst)

To clarify the acetylcholinesterase (AChE) changes among different developmental stages of Tribolium castaneum (Herbst), the toxicological and biochemical characterizations of AChE in 10-d larvae, 20-d larvae, pupae and adults were investigated, respectively with the microplate reader method. The results showed that there were significant differences of protein content and the AChE activity and specific activity among the four developmental stages of T. castaneum. The protein contents of AChE were 10-d larvae < 20-d larvae < pupae < adults, while the AChE activity and specific activity were adults < pupae < 10-d larvae < 20-d larvae. The kinetic analysis of AChE revealed that the apparent Michaelis-Menten constants (Km) by magnitude were as follows: pupae < adults <10-d larvae < 20-d larvae. And no significant difference appeared between the Km values of pupae and adults. In addition, the maximum velocity (Vmax) in larvae was significant higher than those in pupae and adults. In vitro inhibition studies of larvae AChE indicated that the I50 values of 20-d larvae were higher than those of 10-d larvae when treated with eserine, malaoxon and carbaryl, respectively, suggesting that AChE in 20-d larvae was less sensitive to the inhibitors.