BRAIN CONTROL OF EMBRYONIC CIRCADIAN-RHYTHMS IN THE SILKMOTH ANTHERAEA-PERNYI

The clock protein PER is necessary for circadian control of egg-hatchi ng behavior in the silkmoth Antheraea pernyi. Since the brain and midg ut 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 ci rcadian regulation. We also used ligation experiments on first instar larvae to show that the circadian control of PER movement into the nuc lei of midgut epithelial cells is dependent on an intact (connected) b rain. These results implicate a novel brain factor in the circadian re gulation of egg-hatching behavior and provide further evidence for dif fering mechanisms of PER control among species.