Inverted response to temperature changes and bacterial thermotaxis.

<p>(A) The steady-state methylation level subtract the critical methylation level, , and the receptor response to temperature changes, , as a function of temperature. The critical temperature is determined by the crossing point where (or equivalently ). Tar acts as a warm sensor for and a cold sensor for , which drives the cells towards from both sides. (B) The steady-state cell distribution, , as a function of temperature. For illustrative purposes, we assume that the swimming speed, , increases linearly with temperature and that the motor dissociation constant is , with a constant parameter . Three cases are considered. The red solid line corresponds the case where both and are constant; the blue dot-dashed lines is for the case of constant (i.e. ) and ; the green dashed line is generated by using and . Evidently, the steady-state cell distribution can be changed by the temperature dependence of the speed , but it is insensitive to the temperature dependence of motor sensitivity . Here, we fix in all numerical examples. Other parameters used include: , , , , , , , , , and .