Properties of larval and imaginal membrane‐bound digestive enzymes from Trichosia pubescens

Abstract

Trichosia pubescens larval midgut ceca cells display in their plasma membranes a-glucosidases (M, 95,000; pH, 5.5; K , 5.7 mM; Ki for TRlS 8.9 mM), trehalases (M, 69,000; pH, 5.3; K, 0.92 mM; Ki for TRlS 57 mM), and aminopeptidases (M, 95,000; pH, 8.7; K, 0.19 mM) which are solubilized by Triton X-100. The enzymes were purified by electrophoresis and used to raise antibodies in a rabbit. T. pubescens imaginal midgut cells display in their plasma membranes an a-glucosidase (M, 156,000; pH, 5.8; K , 2.3 mM; Ki for TRlS 0.2 mM), a trehalase (M, 93,000; pH, 5.5; K, 0.72 mM; Ki for TRlS 45.5 mM), and an aminopeptidase (M, 210,000; pH, 9.0; K , 0.47 mM). Antiserum produced against the larval enzymes shows no precipitation arc when tested by double imrnunodiffusion or by imrnunoelectrophoresis with Triton X-100-solubilized membrane proteins from imaginal midguts. Otherwise, a similar test showed that larval midgut cecal enzymes and larval ventriculus enzymes display complete immunological identity. The data suggest that, despite the fact the larval and imaginal arninopeptidase, a-glucosidase, and trehalase probably have similar functions, the genes coding for them in larvae and imagoes must differ.

Midgut amylase, lysozyme, aminopeptidase, and trehalase from larvae and adults of Musca domestica

“…This led. Espinoza-Fuentes and Terra [30] to hypothesize that holometabolous insects have originated from insects displaying a general trend to duplicate genes. As a consequence of the hypothetical gene duplication, genes coding for digestive enzymes in larvae and imagoes would diverge, owing to independent selection.…”