Fig 3. Stochastic single-cell simulations in the absence of extrinsic noise.

A. Typical single-cell simulations with Ω = 4. Green curves represent the fluorescence intensity and the black curve is the average of 500 simulations (results of 50 simulations are shown). B. Dependence of variability in oscillation amplitude on the scaling parameter, Ω. Decreasing Ω increased the level of intrinsic noise and hence the variability in the amplitude of the oscillations (red circles). The experimentally observed amplitude variability (dashed line) is achieved when Ω = 0.9. The solid black curve corresponds to $0.44/\sqrt{\Omega }$, obtained by fitting a function proportional to $1/\sqrt{\Omega }$ to simulated data. C. Single-cell simulations with Ω = 0.9 show that, while amplitude variability matches that seen in experiments, the model period is much more variable (CV = 0.47).