Circadian periodicity a neurospora: alteration by inhibitors of cyclic AMP phosphodiesterase.

Three methyl xanthine inhibitors of adenosine 3',5'-monophosphate phosphodiesterase-theophylline, aminophyline, and caffeine-lengthen the period of the circadian conidiation rhythm of Neurospora. The effect are seen in wild-type strains and in three mutant strains with genetically altered period lengths. These results suggest the possible involvement of adenosine 3', 5'-monophosphate in the control of circadian rhythmicity.