Induction mechanism for antibacterial protein synthesis in insect.

1. 用不同肽桥结构或糖链长度的多肽聚糖（PG）作为家蚕抗菌蛋白合成的启动子进行了实验，确定了诱导抗菌蛋白合成所需的最小结构。未免疫幼虫血淋巴溶菌酶含量较高，注射pg后血淋巴溶菌酶活性提高10倍，体外脂肪体培养系统动力学研究阐明了血淋巴溶菌酶在抗菌蛋白诱导中的作用。从免疫后的幼虫脂肪体中提取并测序了天蚕A和天蚕B的cdna。以cdna为探针，研究了cecropin基因的组织特异性表达。分离得到天蚕素A基因，并对其结构进行了分析。在启动子上游区域发现了一个新的NF-kappa B结合基序。提示nf - κ b样蛋白可能参与了昆虫免疫基因表达的调控。

1. Variou baterial peptidoglycans (PG), which were different in peptide bridge structure or sugar-chain length, were tested for elicitor of antibacterial protein synthesis in the silkworm, Bombyx mori, and the minimum structure required for the induction was elucidated.2. The hemolymph from non-immunized larvae was found to contain high levels of lysozyme, and the activity increased 10-times after injection of PG.The roles of hemolymph lysozyme in the induction of antibacterial protein were clarified by kinetic studies with in vitro fat body culture system.3. cDNAs for cecropns A and B were coned and sequenced from immunized larval fat body. Using the cDNAs as probes, tissue specific expression of the cecropin genes was investigated.4. The gene for cecropin A was solated and the structure was analyzed. A novel NF-kappa B binding motif was fund in upstream region of the promoter. The finding suggests that NF-kappa B-like protein may be involved in the regulatin of immune gene expression in insect.