Department of Biology, York University, 4700 Keele Street, North York, M3J 1P3, Canada,
In nature, Drosophila melanogaster are polymorphic in their foraging behaviour on yeast paste, with approximately 70% of the animals exhibiting a rover phenotype, that is having a long pathlength, while the remainder have a significanly shorter pathlength and are called sitters1. Despite the quantitative nature of this foraging phenotype, linking it to the qualitative trait lethality allowed de Belle et al.2,3 to isolate 10 mutations in the major gene, foraging (for). This screen also demonstrated that for is a vital gene since 8 of the 10 alleles isolated are homozygous lethal. Besides the change in behaviour seen in all of the mutants generated, the lethal alleles also exhibit a central nervous system phenotype. for was subsequently localized to 24A3-5 on the polytene chromosome map3. This is the same position as dg2, the gene encoding a cyclic GMP dependent protein kinase (PKG)4. Several pieces of evidence indicate that for and dg2 are synonymous, the most convincing of these is the change in behaviour from sitter to rover in lines transgenic for the T2 transcript of dg2. Based on these results our lab has initiated localization studies to gain insight into this interesting behavioural polymorphism and the central nervous system phenotype associated with some alleles.