NEW INSIGHTS INTO THE SYNCHRONIZATION MECHANISM WITH FORCED SYNCHRONOUS CULTURES OF SACCHAROMYCES-CEREVISIAE

Small amounts of carbon and energy substrate pulsed repetitively into spontaneously synchronous cultures of baker's yeast were found to strongly influence the synchronization properties. The period and the degree of synchrony of the originally spontaneously oscillating culture could be manipulated experimentally by such pulses. The higher the triggered oscillation frequency, the smaller was the synchronizing effect. Experiments with such forced synchronous yeast cultures showed how cell cycle activity can be initiated by weak external substrate signals. These informations enable the understanding of the spontaneous synchronization behaviour and to formulate a plausible hypothesis for the synchronization mechanism. Substrate shifts during synchronous growth caused by changing substrate uptake properties are proposed to be responsible for the cyclic initiation of proliferation activity.