MyoJ-null cells exhibit impairment in CV function and a dramatic redistribution of their CV membranes. (A) Percentage of WT and myoJ-null cells that survived exposure to water for 0, 3, and 24 h. For the 0-h measurement, viability was measured immediately after the transfer of cells from growth media to water. The values for WT and mutant cells (n = 3) were significantly different at both 3 h (P < 0.01) and 24 h (P < 0.025) (Mann-Whitney). (B–E) Transmitted (B and D) and fluorescent (C and E) images of WT (B and C) and myoJ-null cells (D and E) expressing GFP-dajumin. For reasons explained in the text, the image for WT cells is a ventral confocal section, whereas the image for the mutant cells is a confocal section through the center of the cell. As is typical for Dictyostelium, although these cells are clonal isolates of stable transformants for GFP-dajumin, the expression of GFP-dajumin is strong in only a subset of cells. (F and G) Field of myoJ-null cells stained for calmodulin and for myoJ, respectively, to demonstrate that CV membranes are aggregated in every mutant cell. Bars: (C and E) 3 µm; (G) 9 µm.