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Fig. 3 | BMC Biology

Fig. 3

From: Generation and filtering of gene expression noise by the bacterial cell cycle

Fig. 3

Production rates of single cells. a Description of variables used for noise decomposition. The protein production rate p(ϕ, x) (red line) is the sum of three contributions: (1) the population-average cell cycle fluctuations \( \overline{p_c}\left(\phi \right) \) (black line), (2) the contribution due to stochastic replication timing (difference between blue and black line, δp c (ϕ, ν)), and (3) stochasticity resulting from other, unknown, noise sources (difference between red and blue line, δp nc (x)). The sum of δp c (ϕ, ν) and δp nc (x) represents all of the stochastic contributions δp(ϕ, x). The phase at which replication occurs is denoted by v. b Experimental traces of three different cells (thick lines) and fitted step functions (thin lines). See Additional file 2 for definition of step function. Initial value was set to 1 and data is slightly vertically shifted for clarity. c Histogram of v. Data is from 53 cells in which a step-function could be discerned from the rest of the noise (13.5 % of the traces). d Comparison of experimental average production rate curve (gray line) and mean of ideal step functions (orange line). Experimental curve is the same as in Fig. 1b, which was obtained from binning the data according to cell cycle phase and averaging over n = 393 cells

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