Molecular Mechanisms of Self-defense system in Insect

1.利用减法杂交的方法，分离出了几个细菌注射后幼虫所特有的cDNA片段。以这些DNA片段为探针，对免疫后的Samia脂肪体cDNA文库进行筛选，克隆出功能未知蛋白Hdd11、新型白素样蛋白、酪氨酸3-羟化酶、丝氨酸蛋白酶等全长cDNA，并对其进行测序。所有这些基因都被细菌细胞或肽聚糖注射强烈诱导。家蚕和蓖麻毒素肽聚糖结合蛋白的分离与鉴定及PGRP的cDNA克隆利用^<125>I-PGN光亲和标记的方法从家蚕和蓖麻毒素血淋巴中分离到肽聚糖（PGN）结合活性检测蛋白、PGRP蛋白和其他3种蛋白。从免疫后的蓖麻杆菌脂肪体中克隆了两个PGRP cdna，其中一个编码分离得到的PGRP蛋白。另一个PGRP cDNA与果蝇PGRP- lb具有显著的同源性，在中肠中被强烈诱导。

1.cDNA cloning and expression of bacteria-induced genes in the Eri-silkworm, Samia cynthia riciniWith use of subtractive hybridization method, several cDNA 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, full length cDNAs encoding Hdd11 (a function unknown protein), novel lebocin-like protein, tyrosine 3-hydroxylase, two serine proteases have been cloned and sequenced. All of these genes were strongly induced by an injection of bacterial cells or peptidoglycan.3.Isolation and characterization of peptidoglycan-binding proteins from Bombyx mori and S.ricini, and cDNA cloning of PGRPDetecting peptidoglycan (PGN) binding activity by means of photo affinity labeling with ^<125>I-PGN, a PGRP and three other proteins were isolated and characterized from the hemolymph of B.mori and S.ricini. Two PGRP cDNAs were cloned from the fat body of immunized S.ricini, one of which coded the isolated PGRP protein. The other PGRP cDNA had significant homology with PGRP-LB of Drosophila, and strongly induced in midgut.