Hu MeiYing

THE BIOLOGICAL ACT'IVITIES OF YELLOW AZALEA, RHODODENDRON MOLLE G. DON AGAINST THE VEGETABLE LEAFMINER, LIRIOMYZA SATIVAE (DIPTERA: AGROMYZIDAE) *

Abstract  The results of laboratory and greenhouse bioassays indicated that Rhodojaponin‐ III (Abbr. R‐ 1) and extracts of flowers from Rhododendron molle G. Don possessed signficant feeding inhibition and insectcidal properties against the larvae and adults of Liromyzia sativae. Treated with 500 mg/L R‐ III 1 000 mg/L molosul‐tap, and 10 000 mg/L methanol(MeOH) ethyl acetate (EtOAc), CH2Cl2, methanol‐water (MeOH‐H2O) extracts the rates of feeding inhibition were 77. 34 % 74.30 % 82.15 % 77.50 % 67. 33 % 62.85 % against the 2nd instar larvae, and were 67.66% 55.21 % 49.72% 54.26% 46.81 % 38.53% against the 3rd instar larvae, respectively;LC50 values against the 2nd instar larvae were 208.65, 166.05, 2.74 ± 103,766.72, 5.95 ± 103, 1.85 ± 103mg/L, and against 3rd larvae were 300.62, 256.00, 4.33 ±103, 1.03 ± 103,9.79 ± 103, and 2.62± 103mg/L, respectively. Against the adults, LC50 values of R‐III EtOAc extract and molosultap were 159.07.723.87 and 134.55mgL respectively after treatment for 24 h.

草地贪夜蛾组织蛋白酶B的基因克隆、序列分析、三维结构预测及其分子对接模拟

昆虫组织蛋白酶B(Cathepsin B)在昆虫发育和代谢过程中发挥重要作用。本研究首先克隆了草地贪夜蛾Spodoptera frugiperda(J.E.Smmith)的组织蛋白酶B基因Cathepsin B(SCB)，获得其开放阅读框(ORF)序列(GenBank登录号:HQ110064)。生物信息学分析表明，该基因的开放阅读框包含1 026 bp的片段，编码341个氨基酸，预测N-末端含有长度为20个氨基酸残基的信号肽序列，去除信号肽序列后，预测成熟蛋白分子量为35.6 kD，等电点为6.59。氨基酸序列与15种物种Cathepsin B比较有51.2%-96.2%的一致性，与甜菜夜蛾Spodoptera exigua(Hiibner)相似度最高，达96.2%。利用同源建模预测SCB的三维结构，经动力学的优化，SCB折叠成紧密而稳定的球状结构，含6个对结构有稳定作用的二硫键，亲水性氨基酸主要包被在蛋白表面。同时分子对接模拟结果表明，SCB结合口袋比较浅，形状不规则，袋口较宽。ARG19、VAL23和ASN24为活性位点关键氨基酸残基，抑制剂CA与SCB活性位点3个关键氨基酸残基有较强的相互作用，且均主要表现为静电相互作用能，其中VAL23、ASN24与CA形成氢键。以期为进一步运用生物实验手段研究Cathepsin B的结构和功能，设计和开发昆虫组织蛋白酶类抑制剂类杀虫剂奠定基础。