INTRODUCTION: Circadian rhythms are endogenous ~24-hour oscillations that regulate physiological processes and rhytmic regulation of gene expression. In Drosophila melanogaster, circadian organization is controlled by a central brain clock and peripheral clocks in many tissues, including the midgut. Rhythmic expression of core clock genes in the intestine suggests that the gut clock may influence metabolism, behavior, fitness, survival, and communication with the central nervous system.

AIM(S): This study investigated the role of the intestinal circadian clock in regulating physiological and behavioral processes in Drosophila melanogaster. We examined whether silencing the period (per) gene in the midgut affects locomotor activity, survival, intestinal gene expression, and the function of central PDF neurons.

METHOD(S): Tissue-specific silencing of per was performed using the GAL4/UAS system (mex-GAL4 > UAS-perRNAi). Locomotor activity and survival were analyzed in progeny. Expression of core clock genes (per, tim) and intestine-associated genes (ninaD, itd) was measured by qPCR in isolated midguts. The potential impact on PDF neurons was also assessed.

RESULTS: Silencing per in the intestine disrupted rhythmic expression of clock-controlled and functional genes in the midgut. Such alterations influenced physiological performance, survival, and behavioral rhythms, potentially through modified signaling between the intestinal clock and central PDF neurons.

CONCLUSIONS: The intestinal circadian clock appears to function as an active component of the circadian network in Drosophila melanogaster. Disruption of per in the midgut may affect not only local gene regulation but also systemic physiology and behavioral rhythms. These findings highlight the importance of peripheral clocks in coordinating vital processes and their interaction with central circadian mechanisms.