Figure 4

dhkL^- cells exhibit accelerated development. Wild-type (WT) and dhkL^- cells were developed on buffered agar. A. Developmental morphology at 10, 12 and 14 hours as indicated. Bar - 1 mm. The dhkL^- mutants were indistinguishable from the wild type cells during the first 8 hours of development (data not shown). At 10 hours, the mutants formed fingers and tipped aggregates, while the wild-type cells only formed tight aggregates. At 14 hours, the mutants progressed to the slug stage, while the wild-type cells just entered the finger stage. After 20 hours, the mutants resembled the wild type cells again (data not shown). B. We counted the number of spores at 2-hour intervals during development of dhkL^- (circles and dashed lines) and wild type cells (squares and solid lines). The sporulation efficiency (% of cells that became spores) is plotted as a function of time (14-24 hrs), the average and standard error from 3 independent replications. Error bars are not shown when smaller than the symbol. Asterisks indicate a significant difference between the wild type and the mutant values (Student's t-test, p < 0.05).