An inhibitor of protein phosphorylation stops the circadian oscillator and blocks light-induced phase shifting in Gonyaulax polyedra.
The expression of circadian rhythmicity in Gonyaulax polyedra is strikingly altered by an inhibitor of protein phosphorylation. The effects of 6-dimethylaminopurine (6-DMAP), known to reversibly block cell division in many systems through inhibition of protein kinase activity, are described here for Gonyaulax. Its action appears to be exclusively tonic in nature; in cells continuously exposed, the period is lengthened in a concentration-dependent fashion. Shorter treatments at a higher concentration of 6-DMAP (5 mM) apparently stop the circadian oscillator, but reversibly so, since the rhythm resumes after drug removal with a phase delay approximately equal to the duration of the treatment. Pulses of the inhibitor are effective in causing phase delays at all times of the circadian cycle. In addition, 6-DMAP completely blocks light-induced phase advances and is effective in inhibiting many Gonyaulax protein kinases in vitro.
Comolli
J
J
Department of Cellular and Molecular Biology, Harvard University, Cambridge, Massachusetts 02138.
Taylor
W
W
Hastings
J W
JW
D000225:Adenine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D001683:Biological Clocks / Q000187:drug effects*; D002940:Circadian Rhythm / Q000187:drug effects; D004141:Dinoflagellida / Q000187:drug effects / Q000502:physiology*; D008163:Luminescent Measurements; D010766:Phosphorylation / Q000187:drug effects; D017440:Photoperiod; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases / Q000378:metabolism
D047428:Protein Kinase Inhibitors; C001020:N(6),N(6)-dimethyladenine; D011494:Protein Kinases; D000225:Adenine