Using a Drosophila model to determine how neuronal clock circuits couple visual inputs to sleep/wake rhythms (360G-Wellcome-211977_Z_18_Z)

An internal daily timekeeper, known as the circadian clock dictates a 24-hour cycle in behaviour and physiology. In organisms as diverse humans and the genetic model Drosophila melanogaster light perceived by the eyes signals to molecular clock cells in the brain to set their phase. A regular environmental light/dark cycle helps preserve synchrony among different bodily functions, while out-of-phase or abnormal patterns of light exposure can be disruptive to daily timekeeping and result in negative outcomes for both physical mental health and well-being. Given the similarity between the molecular clock circuits of the fruit fly Drosophila and those of mammals, genetic and molecular studies in Drosophila are likely to provide important insight in how visual organs contribute to the control of daily rhythms. To avoid the impact of the invertebrate-specific blue light photoreceptor CRYPTOCHROME, experiments in this proposal will make use of visual organ-detected red light to map light input pathways connecting the Drosophila visual organs to sleep/wake rhythms. In particular, histamine, a known signalling intermediate between the compound eyes and clock neurons, will be examined for its role in synchronizing cellular clocks and regulating intercellular clock signals .