Circadian clock controlling gut-purge rhythm of the saturniidSamia cynthia ricini: its characterization and entrainment mechanism

Summary Experiments using various light-dark (LD) conditions demonstrated that an endogenous circadian clock controls gut-purge timing in the saturniid mothSamia cynthia ricini. A phase-response curve (PRC) based on the application of brief (15 min) light pulses is used to characterize the underlying pacemaking oscillation. The entrainment of the pacemaker to various LD cycles is interpreted in terms of this PRC. The effect of light immediately preceding gut purge was analyzed to account for the deviation of the actual gut-purge rhythm from the prediction made by considering only the action of the oscillation. Lack of precision in gut-purge timing in LD cycles with a very short scotophase has been explained by the failure of the oscillation in these conditions to attain the specific phase-point at which the clock information dictating gut-purge timing is released.Abbreviations AZT arbitrary Zeitgeber time - CT circadian time - PRC phase response curve