Peptide Signaling in Drosophila Courtship Behavior

Innate behaviors are determined genetically and executed in a stereotyped fashion. How such behaviors are programmed in neural circuitry is a major question for understanding brain function. The Dr. Dickson`s laboratory (Research Institute of Molecular Pathology, Vienna) together with others has established that Drosophila courtship behavior, a sex-specific innate behavior, is assembled and organized in central neurons expressing the sexually dimorphic transcript of the fruitless (fru) gene. The goal of this proposal is to identify key peptidergic neurons for courtship behavior among ~3000 fruGAL4 neurons, which were previously implicated in sex-specific behaviors. The first objectives of the proposal are to define the peptidergic signals involved in the courtship behavior. I will ask if fruGAL4 neurons are peptidergic, and what roles these neurons play in courtship. Using RNAi-based gene silencing, I will characterize behavioral roles of signaling peptides and their receptors. This phase of the study also will include the generation of signaling peptide (SP)-specific GAL4 transgenes, which can be utilized to visualize and manipulate behaviorally relevant sets of peptidergic neurons. Having identified peptidergic neurons and their behavioral roles, and genetic tools to manipulate them, I will examine their neural activities during the courtship behavior using real-time optical imaging techniques and recapitulate behavioral steps by activating them selectively in live animals. Courtship behavior is an excellent model for relating gene expressions and neural signaling processes to animal behavior. Drosophila offers powerful genetic tools to manipulate expression of key genes in these processes. Combining genetic tools and optical imaging techniques will allow me to pose testable hypotheses at many levels and to mobilize genetic and physiological approaches appropriate to each objective. Our proposal aims to define the precise roles of peptide signaling in generating courtship behavior. This study will facilitate a mechanistic understanding of neural circuitry underlying complex sexual behavior, and hence offer new insights into how behaviors in general are programmed and executed in the brain.