Efficient induction by DIF-1 and 8-bromo cyclic AMP of prespore-to-stalk conversion in Dictyostelium discoideum

Abstract

We have examined the in vitro effects of DIF-1 (differentiation-inducing factor-1), DIF-2, cAMP, and/or 8-bromo cAMP (Br-cAMP) on prespore cells isolated from normally formed slugs of the cellular slime mold, Dictyostelium discoideum (strain NC4). Without these factors, the isolated cells remained amoeboid at 24 hr of incubation (at 5 × 10 3 cells/cm 2). DIF-1 (100 nM) poorly induced the prespore cells to differentiate into stalk cells (< 15%), and DIF-2 (100 nM) was a less effective inducer of stalk cells (< 1%). Cyclic AMP (200 μM) itself induced neither stalk- nor spore-formation but was inhibitory to the DIF-1-induced stalk cell formation. Br-cAMP (10 mM) alone induced prespore-to-spore maturation. It was found that prespore cells were converted to stalk cells efficiently (> 85%) in the presence of both Br-cAMP and DIF-1.