Electrophoretic and histochemical analysis of esterase synthesis in the ovariole of the milkweed bug Oncopeltus fasciatus (Dall.)

The synthesis of esterases was analysed in the ovariole of the milkweed bug using electrophoretic and histochemical methods. We found a total of 12 esterases from whole ovaries. Using the inhibitors p-hydroxymercuribenzoate, diisopropyl phosphorofluoridate and eserine, 3 of the bands were classed as acetylesterases, 7 carboxylesterases, and 2 arylesterases. No change in esterase patterns occurred during oogenesis. The esterase activity in the follicular epithelium was primarily arylesterase and carboxylesterase. A carboxylesterase was also identified from the central region of the follicle cell. The yolk cells contained mainly carboxylesterase. There was an apparent activation of enzyme activity following pre-treatment with eserine.