杠柳新苷T作用东方粘虫幼虫中肠细胞的免疫定位研究

Immunolocalization of periplocoside T from Periploca sepium Bunge in larvae midgut of oriental amyworm,Mythimna separata Walker(Lepidoptera:Noctuidae)

【目的】明确杠柳新苷T作用后在东方粘虫幼虫中肠肠壁细胞中的分布,探讨其杀虫作用机制。【方法】鉴于杠柳新苷T对东方粘虫幼虫具有明显的胃毒活性,而对小地老虎幼虫无杀虫活性,采用胶体金免疫电镜技术,比较观察了杠柳新苷T处理的东方粘虫幼虫和小地老虎幼虫中肠肠壁细胞的变化。【结果】东方粘虫幼虫经杠柳新苷T处理后,胶体金颗粒首先出现在微绒毛上,且密度随着处理时间延长而逐渐增大,最终破坏微绒毛;同时,胶体金颗粒在细胞内的细胞器膜上也有出现,并损伤细胞器。小地老虎幼虫经杠柳新苷T处理后,中肠肠壁细胞及细胞器均没有明显变化,其上也没有发现胶体金颗粒的存在。【结论】杠柳新苷T对东方粘虫幼虫和小地老虎幼虫的选择性与其在2种试虫中肠肠壁细胞上的特异性结合存在显著差异有关,杠柳新苷T作用东方粘虫幼虫后的初始结合部位可能是其中肠肠壁细胞,推测杠柳新苷T的靶蛋白可能存在于中肠肠壁细胞膜及细胞器膜上。

【Objective】The objective of this research was to figure out the distribution of periplocoside T（PST）in midgut cell of Mythimna separatalarvae after treatment by PST and explore its action mechanism.【Method】Since PST has stomach toxicity to M.separatalarvae while has no activity to Agrotis ypsilonlarvae,the changes of midgut wall cells of these two insects after treatment with PST were observed comparatively using immune-electron microscopy（TEM）.【Result】After treatment with PST,gold particles appeared on the microvilli layer of the midgut of M.separatalarvae firstly.The density of gold particles gradually increased and destructed microvilli layer severely at last.Meantime,gold particles also appeared on the intracellular organelles membrane and the organelles were also destructed.For the control of A.ypsilonlarvae,there was no effect and no gold particle appeared.【Conclusion】The selectivity of PST to these insects was related to the significant difference of its special binding with these two insects.The mid-gut intestinal wall cells may be the original binding site of PST.It was speculated that the target protein of PST may exist on cell membranes and organelles membranes.