Fig. 2.

hb and otd have distinct noise properties in relation to the Bcd input noise. The experimentally measured η_tot (blue circles) in hb (A) and otd (C) intron dot numbers is dissected into η_ext (green diamonds) and η_int (red squares) according to Equations (5) and (6), and the results are plotted against ρ. Solid lines are theoretical predictions based on Equation (10) in the simplified gene regulatory model. The adjusted R₂-values of fitting the experimental data with the model for η_ext, η_int and η_tot of hb are, respectively: 0.85, 0.99 and 1.00; the adjusted R₂-values for η_ext, η_int and η_tot of otd are, respectively: −0.48, 0.97 and 0.98. The negative R₂ suggests that, constrained by the measured parameter values, the model cannot predict η_ext of otd. Arrowheads show the boundary positions of ρ=ρ_max/2. Here, K–values are measured as the mean Bcd concentrations at the marked boundary positions and h–values are extracted by fitting Equation (7) with the experimentally measured B–ρ profiles (He et al., 2011). Since fluctuations in Bcd concentration are dominated by Poisson-like molecular noise (He et al., 2010a), we perform a simple fitting of the experimentally measured Bcd noise to Poissonian distribution for extracting v-values. Figure 2B and D are scatter plots of dissected η_ext (same as in Figures 2A and C but showing data only from the activation boundary regions for better data spread) against converted η_ext (see text for details). Here, Figures 2B and C are for hb and otd, respectively. A linear regression line is also shown (with the equation in the inset box) for each panel.