On induction of cell differentiation by cyclic AMP pulses in Dictyostelium discoideum

Repeated pulses of cyclic AMP, applied at intervals of 5 min, efficiently induced differentiation in cells of agip 53, a morphogenetic mutant of Dictyostelium discoideum, strain Ax-2. In contrast, pulses applied at intervals of 2 min did not induce cell differentiation. To analyze this phenomenon the hydrolysis of cyclic AMP between the pulses as well as the effect of the pulses on the intracellular concentration of cyclic GMP were investigated. Experiments performed in the presence of added cyclic AMP phosphodiesterase revealed that incomplete hydrolysis of cyclic AMP was not the reason for the inefficiency of the pulses applied with a 2-min rhythm. Cyclic AMP pulses applied at intervals of 2 min induced discrete increases of the cyclic GMP concentration. Limited time resolution at the level of cyclic GMP cannot account for the inefficiency of the 2-min pulses.Based on material presented at the Symposium Intercellular Communication Stuttgart, September 16–17, 1982