Fig. 6. Plaque expansion and phagocytosis assays. (A) The deficiency of HS1 cells in the plaque expansion assay was largely reversed by expression of Dd-Wt, less well by expression of Ch-Ac and only slightly by expression of Ch-Sm. Seven to ten drops of Dictyostelium amoebae in a suspension of heat-killed bacteria were spotted onto black filters and micrographs were taken 5 days later when the expanding amoeba plaques had ingested the bacteria and exposed the black filter. (B) Phagocytosis of latex beads was only 25% inhibited in HS1 cells and was completely rescued by expression of Dd-Wt and Ch-Ac. HS1 cells expressing Ch-Sm were no different than HS1 cells. Each point is the mean of five independent experiments for AX3 and three independent experiments for the other cell lines. Standard deviations were about 10% for the later time points in experiments with AX3, Dd-Wt and Ch-Ac, and 20-30% for HS1 and Ch-Sm. Uptake was based on protein concentration rather than cell number to compensate for any differences in cell size. Cells expressing Ch-Sm were larger than the other cell lines, which were all about the same size.