Changes in cyclic nucleotide levels and dimorphic transition in Candida albicans

The relationship between the levels of cyclic nucleotides and dimorphic transition in Candida albicans was examined. The results showed that cells of this pathogenic fungus contained both cyclic adenosine 3',5'-monophosphate (cAMP) and cyclic guanosine 3',5'-monophosphate (cGMP), the concentration of the latter being about one-tenth that of the former in stationary-phase cells of the yeast form. Our results further indicated that germ tube formation induced by incubation at 40 degrees C followed a rise in cAMP concentration in the cell with no accompanying change in cGMP content. Cysteine, which suppressed germination, also reversed the increase in intracellular cAMP concentration. Dibutyryl cAMP (1 MM) significantly promoted germination in proline medium at temperatures of 32 to 34 degrees C. These results suggested that cAMP was one of the controlling factors in the morphological transition in Candida albicans.