Cry8Ga1蛋白对华北大黑鳃金龟幼虫主要酶活性的影响

Effects of Cry8Ga1 toxin on the activities of main enzymes in Holotrichia oblita larvae

华北大黑鳃金龟[Holotrichia oblita(Faldermann)]是一种危害严重的地下害虫,Cry8Ga1蛋白对其幼虫具有明显杀虫活性。本文比较了华北大黑鳃金龟幼虫取食Cry8Ga1蛋白后6种酶活性的变化,发现取食高浓度(5×LC50,50.767μg/g土)Cry8Ga1蛋白幼虫的总蛋白酶、类胰凝乳蛋白酶、乙酰胆碱酯酶(AChE)、谷胱甘肽-S-转移酶(GST)以及氨肽酶(APN)的活性较对照均有不同程度的升高,在大多数处理时段差异显著(P<0.05),其中高浓度处理组的GST酶活性在12h后升高倍数最大,是同时段对照的23.37倍;而取食低浓度(0.5×LC50,5.076 7μg/g土)Cry8Ga1蛋白时,乙酰胆碱酯酶和氨肽酶活性无明显差异(P≥0.05)。类胰蛋白酶在整个试验中活性变化与对照相比仅有个别处理时段存在差异,由此推断,类胰蛋白酶不是华北大黑鳃金龟幼虫对Cry8Ga1蛋白的主要活化酶。

Holotrichia oblita, an underground insect pest, causes serious damages on crops in China. It is well known that Cry8Gal has a larvicidal activity against H. oblita. In this study, the larvae of H. oblita was fed with two concentrations of Cry8Gal. Subsequently, the activities of 6 enzymes were assayed. It was found that when only applied with higher concentration of Cry8Gal （5 X×LC50.767μgg/g soil）, the activities of total protease, chymotrypsin-like enzyme, acetylcholinesterase （ACHE）, glutathione-S-transferase （GST） and aminopeptidase （APN） in larvae would significantly rise in most time of the experiment （P〈0.05）. And the GST activity after 12 h in higher-concentration group was 23.37 times as much as the control, which was the largest multiple of the elevatory enzymes activities. However, the differences of the activities of AChE and APN in larvae were insignifi- cant between the lower concentration （0.5 ×LC50,5.076μg/g soil） group and control （P^0. 05）. The activi- ties of the trypsin-like enzyme showed difference occasionally. It is therefore deduced that the elastase-like pro- teinases were not the main digestive enzymes of Cry8Gal in the larvae of H. oblita.