PROJECT SUMMARY: TRP channel regulation of feeding behavior in Drosophila Feeding is one of the most fundamental of all animal behaviors. In mammals, diverse signals, including chemosensory responses to food properties and mechanical stimulation of the gut, regulate satiation and feeding behavior. These mechanisms, or analogous systems, are well-conserved in invertebrates. Although many neuropeptides and neurotransmitters have been identified that signal satiation or satiety, much less is known about how gut stretch and other mechanosensory forces are signaled to regulate feeding behavior. Due to the remarkable conservation in their basic physiological and neurological properties, studies in Drosophila have revolutionized our broad understanding of animal behavior. Despite the successful use of flies in investigating paradigms such as sleep, circadian rhythm, and memory, only recently have tools for measuring fly food intake facilitated the study of feeding behavior. This project will use Drosophila melanogaster to investigate the regulation of meal intake. New methods allow undisturbed real-time measurements of food consumption in freely behaving adult flies that resolve with unrivalled accuracy the effects of diet and hunger on meal size. An experimental framework is established for defining fly meals and to show their basic regulation by manipulation of the diet, internal hunger state, and circadian rhythms. Using the powerful genetic tools available in Drosophila, preliminary results reveal the involvement of transient receptor potential (TRP) channels in the regulation of meal intake. TRP channels define a large family of sensory receptors, and much is still unknown about how they function as chemo-, mechano-, and other types of receptors. The proposed studies will dissect the role of TRP channel signaling in satiation and meal size control, taking advantage of the tools available in the simplified Drosophila model. Given the increasing importance of meal intake and patterning on physiology and health—regardless of total caloric intake—the proposed studies have the potential to reveal key insights on the role of TRP channel signaling on regulating prandial behavior, physiology, and metabolism. The proposed studies may also eventually inform the design of pesticides targeting TRP channels or feeding behavior in other insects, including agricultural pests and disease vectors such as mosquitos.