Midgut proteinase activities in larvae ofAnoplophora glabripennis (Coleoptera: Cerambycidae) and their interaction with proteinase inhibitors

Abstract

The major proteinase activities in the larval midgut of a common poplar tree borer, Anoplophora glabripennis, were characterised. Overall digestive capacity, as measured by casein hydrolysis, showed a pH optimum between 10 and 11.5, suggestive of serine endopeptidase activity. Trypsin, chymotrypsin, and chymotrypsin‐like activities were detected using specific p‐nitroanilide synthetic substrates and by use of specific serine endopeptidase inhibitors. These activities also showed pH optima in the extreme alkaline range. The absence of cysteine, aspartic, and metallo‐endopeptidases were confirmed using class specific proteinase inhibitors. The dominant exopeptidase in the midgut is leucine aminopeptidase with a pH optimum of 7–9. Carboxypeptidase a and b activity were barely detectable. A large range of serine endopeptidase inhibitors were screened and were found to vary widely in their ability to inhibit casein hydrolysis. Potato proteinase inhibitor 1 (a chymotrypsin inhibitor) and wheat‐germ trypsin inhibitor 1 inhibited particularly effectively in tandem and represent possible candidates for gene transformation to produce plants tolerant to this pest. © 1996 Wiley‐Liss, Inc.

First Comprehensive Study of a Giant among the Insects, Titanus giganteus: Basic Facts from Its Biochemistry, Physiology, and Anatomy

“…Several explanations are available for the absence of proteinase activity in the adult Titanus gut. Protease activity is highly dependent on gut pH [80]; alkaline environments are assumed to be optimal for the gut of Cerambycidae representatives [17][18][19]. Therefore, a slightly alkaline pH was used in our protease experiments, nevertheless, due to a limited amount of the tested material, a detailed study of optimal pH determination could not be performed.…”

“…Most of these studies deal with the digestive system function in larvae of the pest species; works on adults are rare. Thus, there are studies that describe the gut microflora and its importance in digestion [12,13]; the activity of amylases [14,15], carbohydrases [16], and proteases [17][18][19]; and methods of cellulose digestion [20][21][22][23].…”

Effects of class‐specific, synthetic, and natural proteinase inhibitors on life‐history traits of the cotton bollworm Helicoverpa armigera

“…Trypsin and chymotrypsin activities were assayed using a modified protocol (Bian, Shaw, Han, & Christeller, 1996) in a total volume of 100 µl in wells of a microtiter plate. Assays contained 85 µl of 0.1 M Tris-HCl pH 7.8, 5 µl of lumen sample and 10 µl of N-benzoyl-DL-arginine-p-nitroanilide and N-succinyl-alanine-alanine-prolinephenylalanine-p-nitroanilide as specific substrates for trypsin and chymotrypsin, respectively.…”