甲酸乙酯对米象乙酰胆碱酯酶和羧酸酯酶的影响

报道了甲酸乙酯对米象[Sitophilus oryzae(Linnaeus)]乙酰胆碱酯酶(AChE)和羧酸酯酶(CarE)的活性影响,甲酸乙酯对米象表现出很高的毒力,25℃下熏蒸处理24 h的LC₅₀为28.65μL/L。亚致死剂量的甲酸乙酯可以使米象成虫体内AChE的比活力显著下降,用20μL/L的浓度处理24 h,AChE的比活力由15.684 nmol/mg.min下降至9.530 nmol/mg.min;酶动力学研究表明,甲酸乙酯可使米象成虫体内AChE的K_m值明显增加。对于羧酸酯酶,在活体条件下表现为先抑制后激活的规律,离体条件下则主要表现为抑制作用,且随着药剂浓度的增大抑制率也增大。

Effects of ethyl formate on acetylcholinesterase and carboxylesterase in Sitophilus oryzae

The effects of ethyl formate on carboxylesterase (CarE) and acetylcholinesterase (AChE) in Sitophilus oryzae Linnaeus were studied. The results of bioassay revealed that LC50 of ethyl formate was 28.65 μL/L with a 24 hours treatment at 25 ℃, and there was a significant decline in AChE specific activity of S. oryzae treated with sub lethal concentration. Compared to the control, the specific activity of AChE decreased from 15.684 nmol/mg·min to 9.530 nmol/mg·min. In addition, the kinetics study showed that a higher Km value was induced when S. oryzae was treated with ethyl formate. As for CarE, its activity in vivo was firstly inhibited, and then activated, while ethyl formate showed a significant inhibition on CarE activity in vitro and the inhibition percentage ascended with the increase of pesticide concentration.