Changes in the titre of a juvenile hormone III binding lipophorin in the haemolymph of Diploptera punctata during development and reproduction: Functional significance

Abstract

A monoclonal antibody specific to juvenile hormone binding lipophorin was used in an enzyme-linked immunosorbent assay (ELISA) to determine titre of this protein in the haemolymph during the fourth stadium and the first reproductive cycle of adult female Diploptera punctata. Juvenile hormone binding lipophorin was present in the haemolymph at all times at concentrations between 3.75 and 16 μg/μl and its titre exhibited some changes which were not coincident with those in total haemolymph protein concentration. Three aspects of juvenile hormone binding lipophorin function were examined: (1) Plasma juvenile hormone esterase activity and partially purified juvenile hormone esterase activity was inhibited by exogenous juvenile hormone binding lipophorin in a dose-dependent manner by up to 92%. 10 R-juvenile hormone III was metabolized faster by diluted plasma than racemic juvenile hormone III, both in the presence and absence of exogenous juvenile hormone binding lipophorin. (2) Exogenous juvenile hormone binding lipophorin did not affect the biosynthesis and release of juvenile hormone from the corpora allata of day-2 virgin females in vitro. (3) The amount of juvenile hormone binding lipophorin-immunoreactive material in the ovaries of mated females was determined by ELISA. Juvenile hormone binding lipophorin-immunoreactive material reached a maximum in day-3 mated female ovaries (23 μg/pair) at the start of vitellogenesis and declined rapidly thereafter.