Hormonal regulation of yolk protein uptake by vitellogenic oocytes in diapausing and mutant female Drosophila melanogaster.

David S. Richard, Jennifer M. Jones, Brandy Crum, Matthew Gilbert, Michael Barbarito and Suzanne Schelble. Department of Biology, Susquehanna University, Selinsgrove, PA 17870-1164.

Female Drosophila melanogaster, undergo a photoperiodic pre-vitellogenic ovarian diapause associated with suppressed ovarian ecdysteroid levels and corpus allatum juvenile hormone (JH) production. However, diapause termination is associated with an increase in ecdysteroid, but not JH production prior to the onset of vitellogenesis. However, a role for JH in vitellogenesis is suggested by the application of JH III to otherwise JH-deficient ap56f females. This application reverses the vitellogenic delay associated with this allele. JH therefore may stimulate follicle cell (early) YP synthesis. Late YP synthesis by the fat body appears to be regulated by ovarian ecdysteroids and the YPs are sequestered from the hemolymph by receptor mediated endocytosis via nurse cells under the control of the ecdysteroids. Double-immuno-staining for adaptin and YP-receptors (YPR) show co-localization to those nurse cells immediately adjacent to vitellogenic stage 9-13 oocytes. Clathrin is localized more broadly to pre-vitellogenic oocytes. Adaptin and YPR levels increase during diapause termination suggesting that they may be regulated by ecdysteroids and not by the juvenile hormones. Preliminary data suggest that exogenous 20-hydroxyecdysone, but not warming in vitro, may initiate adaptin and YPR production by isolated ovaries. These observations support novel modifications of the mechanism for the endocrine regulation of vitellogenesis. (Supported in part by NIH GM/OD54905 to DSR).

Abstract submitted for consideration for inclusion in the the JH and reproduction section of the JHVII conference to be held in Jerusalem in August, 1999.