Figure 3. Validation of the Dictyostelium chemotaxis-dependent aggregation assay for inhibitor screens.
(A) Effects of latrunculin A on chemotaxis-dependent aggregation (GFP expression). 8,000 cells per well were incubated with different concentrations of the chemotaxis inhibitor latrunculin A in the 1536-well plate. GFP intensity (with standard deviations) was measured after 48 hr. (B) ATP content assay as a counter screen for cytotoxicity. Parallel wells with different concentrations of the cytotoxic compound hygromycin B were assayed for viability (500 cells/well) after 3 days and chemotaxis-dependent aggregation (8,000 cells/well) after 2 days. Inhibition of cell viability was assayed by loss of cellular ATP and inhibition of aggregation was assayed by loss relative GFP intensity. The viability and aggregation inhibition curves (with standard deviations) superimpose.