Is the orcadian clock of gonyaulax held stationary after a strong pulse of anisomycin?

Abstract

1. 1. Gonyaulax polyedra cells were treated with two sequential pulses of a protein synthesis inhibitor (anisomycin) in order to analyse a possible stopping of the circadian clock by the first pulse. 2. 2. Inhibition of protein synthesis during these pulses and after centrifugation and resuspension of the cells was determined by measuring the incorporation of labelled amino acids. 3. 3. The effects of the second pulses on the clock were measured as phase shifts of the glow rhythm with respect to a control rhythm that had been subjected to the initial pulse only. 4. 4. From the observed phase shifts of the second pulses we conclude that the clock is not stopped by the first pulse but is immediately shifted to a different phase.