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

<p><b>A.</b> 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>B.</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 <math><mrow><mn>0</mn><mo>.</mo><mn>44</mn><mo>/</mo><msqrt><mo>Ω</mo></msqrt></mrow></math>, obtained by fitting a function proportional to <math><mrow><mn>1</mn><mo>/</mo><msqrt><mo>Ω</mo></msqrt></mrow></math> to simulated data. <b>C.</b> 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).