Tissue Expression Of Toll-9 Receptor Gene Of Locusta Migratoria Manilensis (Meyen)

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.