Figure 6.

Modeling external stimuli impact on behavior in M. xanthus. The irregular pattern of cellular reversals seen in Fig. 5 prompted us to consider the effects of stimuli on cell behavior. (a) Impact of stimuli (arrows) on FrzCD results in a change in the output timing of cell reversals, through monitoring AglZ activity. The change in timing depends on the refractory period (Supplement S4). The first stimulus occurs during the sensitive period and results in a ∼ 2 min period between reversals, whereas the second occurs during a relative refractory period and results in a ∼ 4 min period between reversals. (b,c) Impact of stimuli on Mgl (via Mot) acting below the level of the Frz system. (b) Shows a stimulus from Mot in the wildtype model, which is similar to an external stimulus acting on FrzCD. Here the reversal time after the stimulus is ∼ 3.3 min. (b) Plot showing the effect of a stimulus from Mot in a FrzCD mutant model, that causes two cellular reversals ∼ 8.1 min apart before returning to a prolonged nonoscillating state. To see this figure in color, go online.