A Generic Mechanism for Adaptive Growth Rate Regulation
Figure 2
Selection of a Higher Growth State by Noise
(A) Time series of protein expressions xi(t). Ten out of 96 protein species are displayed. The vertical axis represents the expression levels of proteins, and the horizontal axis represents time.
(B) Change in growth rate vg observed during the time interval shown in (A). Initially, the growth rate of the cell fluctuates due to the highly stochastic time course of protein expression. After a few short-lived nearly optimal states (c.f. 4,800 ∼ 5,600 time steps), the cell finds a state of protein expression that realizes a high rate of growth. The parameters are θ = 0.5, μ = 10, ρa = ρi = 0.03, ɛ = 0.1, and D = 0.1. In addition, we enhanced the rate of positive autoregulatory paths, i.e., Wii = 1 for i-th gene, so that the regulatory network has multiple attractors. In the simulations, 30% of activating paths are chosen as autoregulatory paths.