Stage-specific production and release of juvenile hormone esterase from the ovary of Diploptera punctata

Juvenile hormone esterase (JHE) is a catabolic enzyme that specifically deg rades juvenile hormone (JH) and has been identified in hemolymph and tissue s in both larvae and adults of numerous insect species. This study investig ates the presence of JHE in ovaries of the viviparous cockroach, Diploptera punctata, and the in vitro release of JHE from these ovaries during the fi rst gonadotrophic cycle. JHE is released in vitro from maturing basal (most posterior) follicles and from follicle cells isolated from oocytes during the short period of time between spermatophore release and chorion formatio n. Enzyme release is dependent upon the presence of calcium in the medium. This released ovarian JHE appears to be larger than and to display ionic ch aracteristics that are different from the isolated hemolymph and fat body J HEs. In addition, JHE activity measured in homogenates of whole ovaries and subsequently oviposited basal oocytes increases dramatically following spe rmatophore release, coincident with a previously described decline in JH ti ter in the ovary. A likely role for ovarian JHE is the site-specific degrad ation of JH in and around the oocyte prior to fertilization and embryonic d evelopment. (C) 2000 Elsevier Science Ltd. All rights reserved.