Inhibitors of protein synthesis on 80S ribosomes phase shift theGonyaulaxclock

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Abstract
One-hour pulses of anisomycin (0.3 microM), streptimidone (30 microM) and cycloheximide (5 microM) caused strong phase-shifts (either advances or delays, of up to 12 h) in the circadian rhythm of the bioluminescence glow in the marine photosynthetic dinoflagellate, Gonyaulax polyedra. Similar pulses of emetine (0.1-100 microM) caused small (less than 4 h) phase shifts. Drug pulses have quantitatively different effects when applied at different phases of the circadian cycle, thus giving rise to ‘phase response curves’ (PRC's). The results lend additional support to the generalization, based on results from several different organisms, that 80s ribosome protein synthesizing system is of key importance in the mechanism responsible for circadian rhythms.