Division of Molecular Genetics, Glasgow University, Glasgow, Schottland,
We are interested in the role of the mushroom bodies in Drosophila courtship behaviour. As previously reported, we have screened the behaviour of males from P[GAL4] enhancer trap lines that show P[GAL4] expression primarily restricted to the mushroom bodies. Using P[GAL4]-mediated expression of the sex-determining gene transformer (which should feminise specific P[GAL4]-expressing regions of otherwise male brains), we have shown that feminisation of specific mushroom body sub-domains leads to bisexual (non-discriminatory) behaviour. However, it has also been reported that ectopic expression of the mini-white gene in heat-shock constructs also leads to males finding other males attractive, and we find that in the absence of transformer expression some homozygous P[GAL4] males court other males. To address this problem we have EMS mutated the mini-white gene in situ in our P[GAL4] lines to discover whether the bisexual behaviour in homozygous P[GAL4] males is simply a consequence of ectopic mini-white expression.