Figure 5.

(Color online) Regularity of stochastic oscillations. In panels A–C, the value of the Fano factor F, which quantifies spiking regularity, is shown as a function of two parameters (grayscale color-code; level lines are displayed in red). (Yellow lines in panels A and B) The region where the TME model predicts oscillations based on numerical analysis (thick lines) or analytical criterion Eq. 7 (thin lines). The regularity of stochastic oscillations is favored by balanced protein and mRNA degradation rates (corresponding to δ ≃ 1) as well as (A) a resonance parameter ρ close to 1, and (B) a high value of the overall production rate Λ. (C) The ratio β/δ controlling the relative mRNA to protein concentration has no effect on spike regularity. (D) The oscillation period (or protein average interspike time interval) is controlled by the resonance parameter ρ. The variation of χ, the average number of on/off cycles in an interspike interval, is displayed (grayscale code) as a function of the lifetime ratio δ and of the resonance parameter ρ. (Red) Level lines. Stochastic simulations of the biochemical network have been carried out with k_off/k_on = 100; β = 10δ (A, B, and D); ρ = 1 (B and C); Λ = 100 (A–C). To see this figure in color, go online.