【作者】 黎群英；

【导师】 夏玉先；

【作者基本信息】 重庆大学 ， 微生物学， 2008， 硕士

【摘要】 昆虫没有获得性免疫系统,其免疫防御体系主要依赖其高效的先天性免疫,包括细胞免疫和体液免疫。其中由昆虫脂肪体合成、分泌抗菌肽而形成的体液免疫比细胞免疫更快更早地产生防御应答。抗菌肽的合成由两条不同的信号通道调节:Toll信号途径和Imd信号途径,它们介导合成不同的抗菌肽。其中Toll信号途径能够介导机体对入侵的病原真菌和革兰氏阳性细菌的感染快速地产生相应的抗菌肽。Toll受体是昆虫Toll信号转导途径的一个重要组成成员,主要功能是将胞外识别蛋白探测到的危险信号传递到胞内,激活昆虫机体对入侵病原微生物的先天性免疫应答,在昆虫的先天性免疫系统中起着十分重要的作用。本研究采用RT-PCR和RACE方法从东亚飞蝗(Locusta migratoria manilensi)中克隆了Toll-9受体基因(缩写名为LmToll-9)的部分cDNA序列(GeneBank登录号:EU573213),分析了该基因在不同组织的表达特征。获得的cDNA包括3’端,长1231 bp,含一个长918 bp的开放阅读框,编码305个氨基酸,推测的氨基酸序列与其他昆虫的Toll-9受体基因有较高的相似性。已经获得的东亚飞蝗Toll-9受体部分氨基酸序列具有昆虫Toll受体家族的部分典型结构,包括胞内的TIR结构域和跨膜区域。半定量RT-PCR研究表明,LmToll-9基因只在东亚飞蝗的中肠组织中表达,而在东亚飞蝗的头部、脂肪体、后腿和血细胞中均未发现该基因的转录。更多还原

【Abstract】 Insects lack an acquired immune system, but have a well-developed innate response. The innate immune system of insects is divided into humoral and cellular defense responses. Humoral that comprised of rapid and massive syntheses of antimicrobial peptides provides a local first line of defense against microorganisms. The synthese of antimicrobial peptides are mediated by two different signaling pathway, Toll and Imd signaling transduction pathway. The two pathway control expression of different kinds of antimicrobial peptides genes. Toll signaling pathway can activate rapid syntheses and secretion of antifungal and antibacterial peptides against invading fungi and Gram-positive bacteria infection. Toll-receptor family is an important member in Toll signaling pathway. It mainly transfers danger signals that extracellular recognition protein detected into cytoplasm, which is important to activate innate immune response of insects. The partial cDNA of Toll-9 receptor gene of Locusta migratoria manilensis (Meyen) was cloned by means of RT-PCR and 3’-RACE (GeneBank accession number: EU573213). The result showed that the cDNA was 1231bp in length and contained an open reading frame (ORF) of 918bp, which encoded 305 amino acids. The deduced amino acdi sequence, which was composed of Toll/IL-1 receptor homologous region (TIR) and transmembrane domain, showed a high similarity with Toll-9 receptors of other insects. Semi-quantitative RT-PCR indicated that LmToll-9 expressed only in the midgut, but not in the head, hind-leg, fat body and blood corpuscle of L. migratoria manilensis.更多还原