Fig. 8. Endocytosis of the fluorescent endocytic marker FM 4-64 to vacuolar membranes is slowed down in V-ATPase null mutants. (A) Wild-type (WT) and vma3 cells were stained with FM 4-64 as described in Materials and methods. Samples were removed for microscopy after staining for the indicated times (min), in order to monitor the internalization kinetics of the dye. (B) The indicated strains were stained with FM 4-64 and photographed after a 60 min chase in YPD medium. Top panels show FM 4-64 fluorescence; bottom panels show visible light images of the same cells.