Changes in actin associated with the cytoskeleton following chemotactic stimulation of dictyostelium discoideum.

Chemotactic stimulation of Dictyostelium discoideum amoebae with pulses of cAMP or folate causes a series of rapid changes in the amount of actin protein associated with the Triton-insoluble cytoskeleton. The first of these changes occurs within 3 sec. of stimulation. The changes are dose-dependent and are within the physiological range of concentrations of cAMP or folate eliciting chemotaxis. These effects on the cytoskeleton show a pattern of regulation during development matching the respective chemotactic sensitivities of D.discoideum to cAMP (most sensitive at 4-8 hr of development) and to folate (rapidly decreasing sensitivity over 0-4 hr). At twelve hr, however, the responsiveness to folate unexpectedly reappears, suggesting a function of folate later in development than previously reported.