Genetic analysis of odor-guided behavior in Drosophila melanogaster

Abstract

The ability to respond to and interact with the chemical environment is fundamental to the survival of many species. It governs predator-prey relationships, kin and mate selection, food localization, maternal behaviors and avoidance of environmental toxins. Olfactory behavior is determined by the concerted action of multiple genes that interact with one another and with the environment, be it external, genetic or sexual. Like a number of other quantitative traits, odor-guided behavior shows significant sex-specificity in its phenotypic expression. However, the molecular basis of sexual dimorphism remains poorly defined. This study provides the first example of an autosomal pleiotropic gene that undergoes sex-specific transcriptional regulation to provide the potential for sexually dimorphic olfactory behavior. The phenotypic and molecular characterization of a P-element tagged locus, smi97B, reveals that the multiple PDZ (PSD-95, Discs-large, Zo-1) and LRR (Leucine-Rich Repeat) domain protein, Scribble (Scrib) is responsible for olfactory behavior in adult and larval stages of Drosophila melanogaster. In the adult, scrib is alternatively spliced to generate sex-specific transcripts that are correlated with sexually dimorphic olfactory phenotypes. Head-derived scrib splice variants differ in the number and positions of protein-interaction (PDZ and LRR) domains they encode. Since, Scrib is a synaptic scaffolding protein, these differences may direct the organization of sexually dimorphic synaptic signaling assemblies that contribute to odor-guided behavior.