Proteolytic gut activities in the rice water weevil, Lissorhoptrus brevirostris suffrian (Coleoptera: curculionidae)

Digestive endoprotease activities of the rice water weevil, Lissorhoptrus brevirostris Suffrian (Coleoptera: Curculionidae), were characterized based on the ability of gut extracts to hydrolyze specific synthetic substrates, optimal pH, and hydrolysis sensitivity to protease inhibitors. Larvae of this species were found to use a complex proteolytic system that includes cathepsin D‐, cathepsin B‐, trypsin‐, and chymotrypsin‐like activities. Trypsin‐like activity was evenly distributed among the anterior, middle, and posterior portions of the gut, whereas cathepsin B– and cathepsin D–like activities were mainly located in the anterior and middle sections, and the chymotrypsin‐like activity was highest in the middle and posterior sections. Gelatin‐containing native‐PAGE gels indicated the presence of several aspartyl, cysteine, and serine protease forms and confirmed the spatial organization of the proteolytic digestive process. Arch. Insect Biochem. Physiol. 53:19–29, 2003. © 2003 Wiley‐Liss, Inc.