Figure 5.

Examination of the reversal window in M. xanthus cells. Reversal period is the average obtained from counting the number of reversals observed per cell over time. Reversal window is the amount of time elapsed between two observed reversals. The model does not predict the long reversal windows of 30 to 60 min reported for FrzCD mutants, which prompted a reexamination of the reversal window (a–c, e) and period (d) in M. xanthus cells. Cell behavior was tracked in 1 hr blocks and the reversal window measured, i.e., the amount of time elapsed between each observed cell reversal. Note that the timescale for (a–c) only goes up to 30 min because no cells were observed to display reversal windows above this length. (a) Wildtype DZ2 cells show the expected average of 7 min between reversals but with a wide variance between 3 to 11 min, whereas (b) hyper-reversing frzCDc cells have a peak reversal of 3 min and reduced variance. (c) Although rare, reversals are observed in the hypo-reversing ΔfrzCD strain and the average reversal window of ΔfrzCD cells shows a peak at 6 min and a 2nd peak at 12 min. (d) The total number of reversals in ΔfrzCD cells ranged from 0 to 6, with many ΔfrzCD cells observed to move for 60 min with zero or one reversal, such that reversals appear to be suppressed, rather than slowed. (e) Reversal measurements are provided for five individual wildtype cells, showing that variance in reversal window is observed at the level of the individual cell.