Dopamine and sensory tissue development in Drosophila melanogaster

Dopamine is an important signaling molecule in the nervous system; it also plays a vital role in the development of diverse non-neuronal tissues in th e fruit fly Drosophila melanogaster. The current study demonstrates that ma les depleted of dopamine as third instar larvae (via inhibition of the bios ynthetic enzyme tyrosine hydroxylase) demonstrated abnormalities in courtsh ip behavior as adults, These defects were suggestive of abnormalities in se nsory perception and/or processing. Electroretinograms (ERGs) of eyes from adults depleted of dopamine for 1 day as third instar larvae revealed dimin ished or absent on- and off-transients, These sensory defects were rescued by the addition of L-DOPA in conjunction with tyrosine hydroxylase inhibiti on during the larval stage. Depletion of dopamine in the first or second la rval instar was lethal, but this was not due to a general inhibition of pro liferative cells. To establish that dopamine was synthesized in tissues des tined to become part of the adult sensory apparatus, transgenic lines were generated containing 1 or 4 kb of 5' upstream sequences from the Drosophila tyrosine hydroxylase gene (DTH) fused to the E, coli P-galactosidase repor ter. The DTH promoters directed expression of the reporter gene in discrete and consistent patterns within the imaginal discs, in addition to the expe cted expression in gonadal, brain, and cuticular tissues, The beta -galacto sidase expression colocalized with tyrosine hydroxylase protein. These resu lts are consistent with a developmental requirement for dopamine in the nor mal physiology of adult sensory tissues. (C) 2001 John Wiley & Sons. Inc.