天然产物梣酮对粘虫围食膜的影响

【目的】梣酮是从芸香科植物白鲜Diatamnus dasycarpus根皮中分离出的一种化合物, 对试虫表现出胃毒活性。本研究旨在检测梣酮对粘虫Mythimna separata 6龄幼虫中肠围食膜的影响, 从而进一步阐明梣酮的杀虫作用机理。【方法】经活体及离体处理, 通过生化分析和扫描电镜观察等方法, 研究了梣酮处理对粘虫幼虫中肠围食膜糖含量, 蛋白质含量和组分以及围食膜表面结构的影响。【结果】梣酮(20 mg/mL)活体处理降低了粘虫6龄幼虫围食膜的蛋白质含量, 却使糖含量升高。活体(20 mg/mL梣酮)及离体(8 mg/mL梣酮)处理条件下, 围食膜糖含量分别为对照组的1.75倍及2.17倍。SDS-PAGE结果显示, 离体及活体条件下经梣酮处理, 围食膜部分蛋白质降解。围食膜解剖扫描电镜观察表明, 梣酮处理可造成围食膜微纤丝排列紊乱。【结论】天然产物梣酮处理对粘虫中肠围食膜的糖含量及蛋白质含量和组分有影响，且改变了围食膜表面结构。本研究为深入地研究梣酮杀虫作用机理奠定了基础。

Effects of fraxinellone on the peritrophic memebrane of Mythimna separata (Lepidoptera: Noctuidae)

【Aim】 Isolated from the rootbark of Diatamnus dasycarpus Turcz., fraxinellone exhibits stomach toxicity against pests. This study aims to clarify the insecticidal mechanism of fraxinellone by investigating the effects of fraxinellone on the peritrophic membrane of the 6th instar larvae of Mythimna separata.【Methods】 Through biochemical methods and SEM observation, the content of carbohydrates, the contents and components of proteins and the surface structure of the peritrophic membrane of the 6th instar larvae of M. separata after in vivo and in vitro treatments with fraxinellone were studied. 【Results】 In vivo treatment of fraxinellone (20 mg/mL) resulted in a drop of the protein content in the 6th instar larvae of M. separata. However, after M. separata larvae were subjected to in vivo (20 mg/mL fraxinellone) and in vitro (8 mg/mL fraxinellone) treatments with fraxinellone, the contents of carbohydrates of both treatments increased, which were 1.75 and 2.17 folds as high as those of the control, respectively. SDS-PAGE result showed that partial proteins were hydrolyzed in the 6th instar larvae of M. separata subjected to in vivo and in vitro treatment with fraxinellone. SEM observation showed that the surface structure of peritrophic membrane changed after the 6th instar larvae of M. separata were treated with fraxinellone in vivo and in vitro. 【Conclusion】 These results showed that fraxinellone affected the contents of carbohydrates and the contents and components of proteins, and altered the surface structure of the peritrophic membrane of M. separata larvae. This study provides a basis for further research on the insecticidal mechanisms of fraxinellone against pests.