Extracellular Cyclic AMP-Phosphodiesterase Accelerates Differentiation in Dictyostelium discoideum

Extracellular cyclic AMP-phosphodiesterase accelerates the development of aggregation competence in Dictyostelium discoideum when present during the pre-aggregation stage. The effect on development appears to depend only on hydrolysis of extracellular cyclic AMP and not on other properties of the phosphodi-esterase molecule. Extracellular cyclic AMP-phosphodiesterase, as a promoter of differentiation, acts mainly throughout the first half of interphase. Our evidence supports the proposal that cyclic AMP oscillations control the rate and possibly the initiation of development. Since extracellular cyclic AMP-phosphodiesterase acts from the beginning of interphase cyclic AMP oscillations may also occur from early interphase, at least in the presence of this enzyme. This would imply that the cyclic AMP oscillator is a determinant, but not a product, of the developmental programme.