The curious case of CCHamide1: a role for CCHamide1 in sleep, metabolism and fitness in Drosophila melanogaster

Circadian clocks regulate a myriad of physiological processes rhythmically throughout the day in most organisms. Our study focuses on a relatively less-studied neuropeptide CCHamide1 (CCHa1), expressed in the Drosophila melanogaster gut and the central circadian clock in the brain. We investigated the role of ccha1 on sleep under altered dietary conditions, as well as its impact on metabolism and fitness in Drosophila. We assayed sleep under ad libitum fed, starved and altered protein diets using ccha1 mutant males and females. We found that both the mutant males and females showed sleep fragmentation when fed ad libitum. We also found that ccha1 specifically influences daytime sleep in males under starvation conditions and contributes strongly to sleep consolidation under normal and high-protein conditions, but to a lesser extent under low-protein diet conditions in male flies. Both ccha1 mutant males and females fared better under starvation stress and had higher triglyceride reserves. The ccha1 mutants also exhibited a delay in pupariation, likely because of an altered expression of the early ecdysone-responsive genes. In addition, the mutants had an increased mid-life fecundity and reduced lifespan. These results suggest a possible role for the protein sensing molecule ccha1 in integrating nutritional status with sleep, as well as in regulating triglyceride levels and some of the fitness related traits such as longevity and fecundity in Drosophila.