Comparison of phase shifting by temperature of wild typeNeurospora crassaand the clock mutant,frq‐7

Abstract

Phase shifting of the circadian conidiation rhythm of Neurospora crassa by pulse treatments with different temperatures, which ranged from 10° to 35°, was compared for the wild type and the clock mutant, frq‐7, in liquid culture. Both strains showed similar phase response curves’ for high temperature (35°) but different phase response curves for low temperature (15°). In the wild type strain, pulses with temperatures higher than 25° caused small shifts in phase in the subjective day phase but pulses with temperatures lower than 25° caused large phase‐delay in the same phase. The clock mutant, frq‐7, showed similar responses to temperature pulses in phases other than the late subjective day phase (CT 9 to CT 14), during which frq‐7 was almost intensitive to pulses with temperatures lower than 25°. This phase (CT 9 to CT 14) coincided with the phase which has previously been proposed to be affected by mutations at the frq locus.