Several clocks may simplify the circadian system of Gonyaulax

The circadian system of Gonyaulax involves at least two pacemaking oscillators. These oscillators have been shown to be distinct at the physiological level by an examination of their rhythmic periods under different conditions, their phase response to pulses of light and darkness and their ability to compensate the rhythms for changes in temperature. It is also known that Gonyaulax can restrict synthesis of different proteins to at least three different times of day. We suggest that the two known oscillators may each control synthesis of a differently timed class of proteins.