Cyclic AMP and cyclic GMP in germinating conidia of Neurospora crassa.

A new method for obtaining synchronous germination allowed accurate time-course studies of endogenous levels of cyclic adenosine 3',5'-monophosphate and cyclic guanosine 3',5'-phosphate in germinating conidia of Neurospora crassa. The levels of both cyclic nucleotides remained constant throughout germination, showing that they neither signal nor respond to any of the biochemical changes which are known to occur in the germination process. Conidal germination was approximately normal in three cr-1 mutants of Neurospora which have been shown to be deficient in adenylate cyclase activity. Cyclic AMP levels in the mycelia of cr-1 mutants were low, but surprisingly, the levels in conidia were normal.