Abstracts Biological Sciences

Cellular Components of Naturally Varying Behaviours in the Fruit Fly, Drosophila melanogaster

by Amsale Taddes Belay

It is now well accepted, through the use of mutational studies, that genes influence behavioural variation. However, we have little knowledge of the cellular and neuronal mechanisms underlying the effects of specific genes. This thesis broadens our understanding of the neurogenetic underpinnings of naturally occurring differences in behaviour using the genetically tractable model organism Drosophila melanogaster. The thesis focuses on allelic variation at the foraging (for) gene which influences both larval and adult behaviour. In particular, for’s cellular/neural contributions to food-related behaviours and learning and memory is investigated. In the first study, we map FOR protein distribution patterns in the adult brain and use this knowledge to demonstrate a neural-specific function for the for gene in adult food-related behaviour. In the second study we demonstrate a novel role for for in the regulation of naturally existing differences in fly learning and memory in the mushroom bodies of the fly brain. In the third study, I explore FOR distribution patterns in larval tissues. I show that FOR is expressed both in neural and non-neural tissues suggesting a distributed function for FOR in food-related behaviours in the larva. In the last study, I describe naturally existing differences in fat metabolism in the Drosophila larva fat storage tissue. FOR is expressed in the fat storage tissue and may regulate lipid packaging, a trait linked to foraging. In general, my thesis is a cellular and neurogenetic analysis of natural variation in behavioural and physiological traits of D. melanogaster. The functions of FOR in food-related behaviours, nutrient physiology and cognition are conserved across taxa. The findings of this thesis should provide a framework to understand these phenomena in a wide range of organisms.