SCUTOID MUTATION OF DROSOPHILA-MELANOGASTER SPECIFICALLY DECREASES OLFACTORY RESPONSES TO SHORT-CHAIN ACETATE ESTERS AND KETONES

A molecular-genetic approach has been taken to identify genes involved in olfactory transduction in Drosophila melanogaster. Two independent lines of research led to the finding that the dominant Scutoid (Sco) mutation causes a diminished extracellular electroantennogram response to the odorants ethyl acetate (EtAC) and acetone (AC), Sco flies show ed about 4- and 2.5-fold reduced responses to EtAC and AC, respectivel y, compared to Canton-S wild-type and sibling control flies lacking th e Sco mutation when electroantennogram recordings were made from the p roximal anterior third antennal segment. The responses to five other o dors from three different chemical classes were unaltered, The maximum response to either EtAC or AC was decreased with no change in apparen t affinity. Responses to short-chain (but not long-chain) acetate este rs and ketones were dramatically affected at all antennal locations te sted. Only in the proximal quadrants, were responses to ethyl acetoace tate also reduced. Most Sco revertants tested had a normal olfactory r esponse; duplications of the region including no-ocelli partially supp ress the Sco bristle as well as olfactory phenotypes. Sco adults had a n impaired behavioral response to EtAC but not to banana or propionate . There was no effect of the mutation on larval chemosensory behavior or extracellularly recorded adult compound eye and ocellar visual resp onses. These findings suggest the involvement of Sco in an olfactory p athway in adults which is specific for short-chain acetate esters and ketones. (C) 1995 John Wiley & Sons, Inc.