Description. This proposal continues the re-evaluation of the roles of
ecdysteroids and juvenile hormones (JH) in vitellogenesis in female Drosophila
melanogaster initiated during the original granting period (NIH GM/OD54905)
and is a revised version of an application submitted in January, 2001.
Our recent work has demonstrated that JHs may be involved in the regulation
of early yolk protein (YP) synthesis by follicle cells of the developing
egg chamber. However, in apterous mutant, and in diapausing females, vitellogenesis
can occur in the absence of JHs, but never in the absence of ecdysteroids.
These observations support the model for the endocrine regulation of YP
synthesis and uptake (Richard et al.,1998, 2001a). This proposal studies
the levels of production and action of ecdysteroids, juvenile hormones,
sex peptide and yolk proteins (YPs) by wild-type Canton-S females, Canton-S
females in diapause, apterous56f and apterous4, mutants. A successful goal
of the previous granting period was to examine the processes of receptor
mediated endocytosis in the trafficking of early YPs from the follicle cells,
and late YPs from the hemolymph into the developing oocytes (Richard et
al., 2001b). We now propose to examine further the mechanisms by which the
production of the proteins _-adaptin, clathrin and the YP-receptor may be
controlled. Expressed sequence tag microarray analysis of gene expression
patterns in ovaries following treatment with JHs and ecdysteroids is proposed
as a simple initial step towards the incorporation of microarray technology
into our laboratory. The significance of these experiments lies with the
unique position that D. melanogaster occupies in biological research as
both a model insect and a model dipteran. No other insect is as well characterized
in terms of its genetic make-up and while it is small, it has proved possible
to surgically dissect and manipulate the organs involved in the endocrine
system. Given the importance of some cyclorrhaphous dipteran species as
vectors of human disease, it is of obvious importance that we understand
the role of the endocrine system in the regulation of reproductive development.