CARBOXYPEPTIDASE-B IN ANOPHELES-GAMBIAE (DIPTERA, CULICIDAE) - EFFECTS OF ABDOMINAL DISTENSION AND BLOOD INGESTION

Carboxypeptidase B (CPB) activity was detected in the puts of strain G -3 of Anopheles gambiae (Giles) and Aedes aegypti (L.). Mosquitoes wer e examined 3-5 d after. emergence following exposure to 20% sucrose, f rom 0 to 4 h after feeding on a meal of Inter Leads in saline, and fro m 0 to 96 h after blood feeding. CPB activity. was assayed in whole-gu t homogenates, including lumenal contents and peritrophic matrix, by f ollowing the hydrolysis of a substrate specific for CPB-[H-3]-benzoyl- L-Phe-L-Arg Homogenates were divided into cytosolic plus lumenal compo nents and membrane-associated components. Activity levels changed in r esponse to feeding, decreasing in response to distention by saline plu s latex and increasing only in response to blood. Overall, CPB activit y was higher in unfed An. gambiae than in unfed Ae. aegypti. Detection of CPB activity in the peritrophic matrix of both species indicated t hat this enzyme was secreted actively into the gut lumen. Ln An. gambi ae, CPB activity was optimal at pH 8, and thiol-type CPB was the predo minant form detected. The data indicated that CPB in An, gambiae was r egulated by both physical and chemical factors.