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Inhibitors of protein synthesis on 80S ribosomes phase shift the Gonyaulax clock
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.
Insights
Marine dinoflagellates exhibit strong circadian rhythm phase shifts when exposed to protein synthesis inhibitors like anisomycin. These findings highlight the critical role of the 80S ribosome system in regulating circadian rhythms across organisms.
Area of Science:
- * Chronobiology
- * Marine biology
- * Molecular biology
Background:
- * Circadian rhythms are endogenous biological processes that regulate daily cycles.
- * The marine dinoflagellate Gonyaulax polyedra is a model organism for studying circadian rhythms.
- * Protein synthesis is hypothesized to be involved in the molecular mechanisms of circadian clocks.
Purpose of the Study:
- * To investigate the effects of protein synthesis inhibitors on the circadian rhythm of Gonyaulax polyedra.
- * To determine if the 80S ribosome protein synthesizing system is crucial for circadian rhythmicity.
Main Methods:
- * Exposing Gonyaulax polyedra to one-hour pulses of various protein synthesis inhibitors: anisomycin, streptimidone, cycloheximide, and emetine.
- * Measuring the impact of these pulses on the circadian rhythm of bioluminescence.
- * Analyzing the resulting phase response curves (PRCs) to quantify phase shifts.
Main Results:
- * Anisomycin, streptimidone, and cycloheximide induced significant phase shifts (up to 12 hours) in the circadian rhythm.
- * Emetine caused smaller phase shifts (less than 4 hours).
- * The magnitude of phase shifts varied depending on the timing of drug application, generating distinct PRCs.
Conclusions:
- * The 80S ribosome protein synthesizing system plays a key role in the mechanism of circadian rhythms.
- * These findings support the generalization that protein synthesis is fundamental to circadian clock function across diverse organisms.