Abstract

Invertebrate model systems such as Drosophila have greatly contributed to our understanding of how motor neurons develop and control our voluntary muscles. By contrast, the power of Drosophila genetics has not yet been harnessed to investigate the development and physiology of visceral innervation. We have approached this issue at multiple levels: from the genes involved in specifying defined visceral lineages, to their functional output and integration into mature circuits. We have identified several defined neuronal lineages in the Drosophila central nervous system that send out axons to internal organs such as the digestive or reproductive tracts. Some of this innervation is motor, whereas other subsets of neurons express Drosophila homologues of brain-gut peptides such as insulin/IGF/relaxins. We are investigating the genes and developmental mechanisms regulating the specification and pathfinding of visceral neurons. In parallel, we have developed simple behavioural and physiological assays to assess normal digestive/excretory function. The wealth of genetic tools in Drosophila allows us to mutate single genes in subsets of cells as well as “silencing” defined neurons. By doing so, we are identifying specific peptides and visceral neurons that regulate different aspects of gut physiology, thereby beginning to unravel the interplay between the nervous system and organismal physiology.