Adaptin and the Yolk Protein Receptor appear to localize to Follicle Cells in Early Vitellogenic Oocytes in Drosophila melanogaster.

Deborah E. Cline *, Gina M. Zuretti and David S. Richard, Department of Biology, Susquehanna University, Selinsgrove, PA 17870-1164.

Receptor-mediated endocytosis in developing oocytes of female Drosophila melanogaster utilizes non-specific proteins such as clathrin and adaptin and specific yolk protein receptors (YPRs) to sequester yolk proteins (YPs) from the insect hemolymph. Vitellogenesis in Drosophila is a two stage process, with early YP uptake resulting from follicle cell YP synthesis and trafficking into the developing oocyte while late YP uptake involves YP synthesized by the fat body and moved through nurse cells by receptor mediated endocytosis. In this paper, we present laser confocal immunofluorescence image data localizing early YP endocytotic machinery to the basal membrane of the follicle cells surrounding the oocyte. Under certain circumstances, we believe that vitellogenesis can occur in the absence of early YP uptake. We shall examine the process of vesicle trafficking in follicle cells in these deficient animals to determine if indeed this is the case. The rescue of follicle cell vesicle transport by topically applied juvenile hormones will be attempted. These investigations of normal and aberrant reproduction, and during diapause termination indicate that YP-uptake during vitellogenesis is primarily regulated by ecdysteroids and not by the juvenile hormones as previously determined. These observations support a novel mechanism for the endocrine regulation of vitellogenesis and may ultimately provide a basis for novel mechanisms of insect control. (Supported in part by NIH GM/OD54905, to DSR).