转sck/cry1Ac基因稻谷对米蛾幼虫解毒酶系的影响

Effects of transgenic sck/cry1Acrice grain expressing SCK/Cry1Ac toxin on the activities of the detoxification enzymes in the larvae of Corcyra cephalonica

采用酶活力测定及酯酶同工酶电泳方法研究米蛾(Corcyra cephalonica)幼虫取食表达SCK/Cry1Ac毒蛋白的转基因稻谷后体内重要解毒酶活力的变化,明确其代谢毒蛋白的主要酶类。结果表明:取食转Bt基因稻谷米蛾幼虫体内的α-乙酸萘酯酶、碱性磷酸酯酶的活力在24～72h显著低于对照;酸性磷酸酯酶活力在12、48h和72h时也显著低于对照;而α-乙酸萘酯羧酸酯酶和乙酰胆碱酯酶的活力显著高于对照。谷胱甘肽-S-转移酶的活性除饲喂24h的处理外,其他处理与对照无显著差异。此外处理72h后米蛾幼虫体内酯酶同工酶谱有4条酯酶酶带,4种酯酶Est1、Est2、Est3、Est4的活性均受到不同程度的抑制,酯酶Est4的抑制效果最明显。这些解毒酶和酯酶同工酶直接参与Bt毒蛋白的代谢作用。

The objective of this study is to reveal the activity of the detoxification enzymes （α-naphthylacetate es- terase, a-naphthylacetate carboxylesterase, acetylcholinesterase, glutathione-S-transferase, acid-phosphatase, al- kaline-phosphatase） in the 3rd instar larvae of Corcyra cephalonica after fed with transgenic rice sck/crylAc grains, and identify the main metabolic enzymes of the toxic protein. The assay methods of this study were enzyme activity and electrophoresis of esterase isozyme. The results showed that the activities of a-naphthylacetate esterase and alkaline-phosphatase in the larvae fed with Bt rice grain for 24--72 h were greatly lower than that of the con- trol fed with the non-transgenic rice grains. However, the α-naphtbylacetate carboxylesterase and the acetylcho- linesterase activities of the larvae fed with Bt rice grains increased markedly. The acid-phosphatase activity of the larvae fed with Bt rice grains for 12 h, 48 h and 72 h decreased markedly, greatly lower than that of the control. The activity of the glutathione-S-transferase in the larvae fed with Bt rice grains for 24 h was greatly lower than that of the control. Esterase isoenzymes from both 3rd instar larvae fed with Bt-transgenic rice grains for 72 h and that of the control were compared by polyacrylamide gel elcctrophoresis. The results showed that there were four bands of the esterase in both treatments. The enzymes of the larvae fed with Bt rice grains were less active than that of the control, but the removal distance did not change compared with the control.