Figure 6

Amplification of noise-induced oscillation by gene copy number control. Highly periodic expression of mRNAs and proteins from a single promoter with negative feedback is shown in (a). In contrast the expression of 10 genes (b) using the same parameters attenuates the oscillations without apparent periodicities. The average power spectrum of the protein oscillations as obtained from the SSA and the LNA is shown for a single (c) and ten promoters (d). Note that while in (c) the LNA underestimates the amplitude of the oscillations it also fails to accurately predict their period. The power spectrum in (d) reveals the weak oscillatory behavior of the time traces in (b) in good agreement with the SSA. The parameters used are given in Table 2 except for a volume of 50 × 10^-15l with $\tilde{\mathrm{\Omega }}=\mathsf{\text{ 3}}0{\left(nM\right)}^{-\mathsf{\text{1}}}$ and $k_0=3\times 10^3{N}_G^{-1}{\left(nM\right)}^{-1}$ where N _G is the gene copy number.