Cloning And Expression Of Chitinase CDNA From Cotton Boll Worm ,Helicoverpa Armigera

The cuticle and the peritrophic matfix of insects acted as physicalbarriers to pathogens and environmental hazards. Both were composedprimarily of chitin and protein. The degradation of chitin by chitinasewas vital step in the life cycle of insects because insects undergoperiodic ecdysis and metamorphosis. The old layers of the cuticularexoskeleton should be digested prior to ecdysis and metamorphosis.During the molting process, chitin in insect cuticle was degraded bychitinase. In l993, a gene encoding the chitinase of M sexta was clonedand its expression during metamorphosis was explored.The cloning and characterization of chitinase genes of insects mightprovide a importam clue fOr the utilization of these enZymes as abiocontfol agent of insect pests, and insect chitinase might be used insynergism with other insecticidal proteins, such as Bt toxins, proteinaseinhibitors or lectins, to control insect pests.In this study we firstly determined the time when the chitinase ofHelicoverPa armlerra produced in high activity and we cloned acDNA encoding a chitinase of HelicoverPa armlerra by RACEmethod which was about l.6kb and included comPlete 5'-end CAP and5'-UTR. The sequence of the chitinase cDNA from HelicoverPa.armigera was analysed and then registered in GenBank and accessionnumber was AF515667. The cDNA encodes a protein with a plltative 2lamino-acid signal pePtide and a 425 amino-acid mature protein withmolecular mass of 50 kDa. And we have also studied its exPression inprotoryotes and the conserved regions of insect chitinase genes indifferent insects pests.