Extracellular cyclic AMP during development of the cellular slime mold Polysphondylium violaceum: comparison of accumulation in the wild type and an aggregation-defective mutant.

Cyclic AMP was synthesized by Polysphondylium violaceum after starvation and during the preaggregation stage of development. Most of the newly synthesized cyclic AMP accumulated in the extracellular medium, with very little change in the intracellular cyclic AMP concentration. The addition of 10(-3) to 10(-6) M exogenous cyclic AMP to starved amoebae caused a 20 to 50% decrease in the number of aggregation centers formed compared with untreated controls. An aggregation-defective mutant of P. violaceum (strain aggA586) excreted or accumulated very little cyclic AMP. Strain aggA586 aggregated normally in the presence of a dialyzable, excreted product (D factor) produced by wild-type amoebae. When the mutant was incubated with D factor, cyclic AMP accumulated in the medium, and the amount accumulated depended on the amount of D factor added to the mutant amoebae.