FIGURE 5. The cleavage furrow of racE null cells does not constrict to the same extent as that of wild-type cells. Wild-type (A) and racE null (B) cells were fixed in suspension culture and stained with DAPI to visualize their nuclei. Cells in anaphase (which display two condensed nuclei with no nucleoli) were photographed and measured. The internuclear distance increases as the cells progress through anaphase and telophase. In wild-type cells, an increase in the internuclear distance is correlated with a constriction of the cleavage furrow (equatorial diameter). In racE null cells the cleavage furrow fails to constrict to the same extent as in wild-type cells. The R values for these linear regressions are: wild-type = 0.74; mutant = 0.31