Brain Control of Embryonic Circadian Rhythms in the Silkmoth Antheraea pernyi

The clock protein PER is necessary for circadian control of egg-hatching behavior in the silkmoth Antheraea pernyi. Since the brain and midgut of the silkmoth embryo contain PER-positive cells, we examined the circadian clock potential of these embryonic tissues. Transplantation experiments indicate that the circadian clock controlling egg-hatching behavior resides in brain, and that a humoral factor mediates this circadian regulation. We also used ligation experiments on first instar larvae to show that the circadian control of PER movement into the nuclei of midgut epithelial cells is dependent on an intact (connected) brain. These results implicate a novel brain factor in the circadian regulation of egg-hatching behavior and provide further evidence for differing mechanisms of PER control among species.