Abstract submitted to the Pennsylvania Academy of Science
for inclusion in the April 11-13, 1997 meeting held in Malvern, PA.
Ecdysteroids stimulate vitellogenesis in ovaries from diapausing female
Drosophila melanogaster
Noel Watkins*, Robert Serafin and David S. Richard. Department of Biology,
Susquehanna University, Selinsgrove PA 17870.
As part of a reassessment of the relative importance of ecdysteroids and
juvenile hormones (JH) in the regulation of reproductive development in
Drosophila melanogaster, 1mg of 20-hydroxyecdysone in 23nl MEM was
injected into the abdomens of 14-day old diapausing females reared from
eclosion under a diapausing photoperiod (LD 12:12) at 11oC.
Following a further 7-day incubation in the same conditions, the ovaries
were removed and signs of diapause termination observed (an increase in
size, and the appearance of vitellogenic oocytes). The endogenous production
of ecdysteroids by isolated ovaries following transfer to 25oC
was examined to more accurately define the timing of an increase in production
relative to yolk protein (YP) deposition in the oocyte. An increase in ecdysteroid,
but not JH production precedes YP accumulation. These results are consistent
with the proposed new model for the regulation of vitellogenesis in which
ecdysteroids, and not JHs, play the prominent role.