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Fig. 4. Development of ef2-null (B,D,F) and parental Ax-2 cells (A,C,E)
under submerged conditions. ef2-null and Ax-2 cells were harvested
during the exponential growth phase, washed twice in BSS and plated in a
24-well titer plate at a density of 5x105 cells/ml (1 ml of
cell suspension/ well). This was followed by incubation at 22°C for 6.0
hours (A,B), for 7.5 hours (C,D) and 10.0 hours (E,F). At 6.0 hours of
incubation, Ax-2 cells acquire aggregation competence (A), while
ef2-null cells show no sign of cell aggregation (B). At 7.5 hours,
aggregation streams are formed in Ax-2 cells (C), but not in ef2-null
cells (D). At 10.0 hours, Ax-2 cells form tight aggregation streams (E), but
ef2-null cells still remain as aggregation-competent cells (F).
Similar results were obtained by observations in at least three independent
experiments. Bars, 200 µm.