Light-induced phase shifting of the circadian conidiation rhythm is inhibited by calmodulin antagonists in Neurospora crassa.
The effects of calmodulin antagonists and inhibitors of protein kinases and phosphatases on light-induced phase shifting were investigated in Neurospora crassa. Calmodulin antagonists, namely, trifluoperazine, chlorpromazine, and W-7, almost completely inhibited the light-induced phase shifting without having any effect on the circadian clock itself. Chlorpromazine was less effective in inhibiting the light-induced phase shifting than trifluoperazine. W-5, a dechlorinated analogue of W-7, failed to inhibit the light-induced phase shifting at the same concentration as that at which W-7 was effective. These results suggest that calmodulin is required during signal transduction from the light-perceiving system to the circadian clock in N. crassa. Inhibitors of protein phosphorylation did not inhibit the light-induced phase shifting, although these inhibitors completely inhibited mycelial growth. Trifluoperazine partially inhibited the phosphorylation of three proteins when phosphorylation was assayed in vitro.
Sadakane
Y
Y
Department of Biology, Faculty of Science, Okayama University, Japan.
Nakashima
H
H
D002147:Calmodulin / Q000037:antagonists & inhibitors*; D002746:Chlorpromazine / Q000494:pharmacology; D002940:Circadian Rhythm / Q000502:physiology*; D018492:Dopamine Antagonists / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D007166:Immunosuppressive Agents / Q000494:pharmacology; D008027:Light; D009492:Neurospora crassa / Q000254:growth & development* / Q000528:radiation effects*; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors; D015398:Signal Transduction / Q000502:physiology; D016559:Tacrolimus / Q000494:pharmacology; D014268:Trifluoperazine / Q000494:pharmacology
D002147:Calmodulin; D018492:Dopamine Antagonists; D004791:Enzyme Inhibitors; D007166:Immunosuppressive Agents; D047428:Protein Kinase Inhibitors; D014268:Trifluoperazine; D010749:Phosphoprotein Phosphatases; D002746:Chlorpromazine; D016559:Tacrolimus