Molecular Mechanisms of Self-defense system in Insect

1.蓖麻蚕(Samia Cynthia Ricini)细菌诱导基因的筛选用差异克隆法比较幼虫和注菌幼虫脂肪体中的mRNAs，分离出12个注菌幼虫特异的DNA片段。以这些DNA片段为探针，筛选免疫后萨米亚脂肪体的cDNA文库，获得溶菌酶的cDNA，2.溶菌酶和黏附素的分离与鉴定：从免疫的蓖麻链霉菌血淋巴中分离到一种溶菌酶，其N端氨基酸序列与其他鳞翅目昆虫溶菌酶的氨基酸序列完全一致。该酶的性质与其他鳞翅目昆虫溶菌酶的性质相似。阿曲菌素仅对革兰氏阴性菌有杀菌作用。3.家蚕和蓖麻链霉菌的肽聚糖结合蛋白的分离和鉴定。用亲和标记法检测肽聚糖(PGN)结合活性。125&gt；I-PGN是从菜蛾血淋巴中分离到的三种不同于PGRP的蛋白，其中一种是血淋巴蛋白(C-19)，其大小为31kd，其生理功能尚不清楚，不仅与PGN结合，还与寡聚甲壳素和脂多糖结合。第二种蛋白是促进蛋白，作为刺激核型多角体病毒复制的蛋白，从免疫的萨米亚幼虫血淋巴中分离到两种PGRP。

1. Screening of bacteria-induced genes in Eri-silkworm, Samia cynthia riciniComparing mRNAs in the fat bodies from naive and bacteria-injected larvae by means differential cloning method,12 DNA fragments,which were specific for bacteria-injected larvae,were isolated.After screened a cDNA library of immunized Samia fat body with these DNA fragments as probes,cDNAs for a lysozyme,three attacins and two peptidoglycan recognition proteins(PGRP)have been cloned and sequenced.2.Isolation and characterization of lysozyme and attacin.A lysozyme was isolated from immunized hemolymph of S.ricini.The N-terminal amino acid sequence was in perfect match of that deduced from the cDNA.The properties of the enzyme was compared with other lepidopteran lysozyme.An attacin was similarly isolated and characterized.The attacin was bactericidal only to Gram-negatives.3.Isolation and characterization of peptidoglycan-binding proteins from Bombyx mori and S.ricini.Detecting peptidoglycan (PGN) binding activity by means of photo affinity labeling with ^<125>I-PGN,three proteins,which were different from PGRP,were isolated and characterized from the hemolymph of B.mori.One of the proteins (31kd) was the hemolymph protein (C-19),which had been isolated and sequenced,but whose physiological role was not known.The protein binds not only to PGN but oligo chitin and LPS. The second protein was promoting protein,which had been isolated as the protein stimulated replication of nucleopolyhedrovirus.Two PGRP were isolated from immunized hemolymph of Samia larvae.