Figure 2.
Simulated nuclear Bcd gradient profiles. (A) Nuclear Bcd concentration [Bn], in arbitrary units, within the cortical layer of a simulated embryo was obtained in a biologically realistic 2-D model.12 Here the simulated [Bn] profiles as a function of fractional embryo length x/L are shown for nuclear cycles 10 to 14. These simulated [Bn] profiles, as seen experimentally,20 differ by <10%, with a calculated g value of −0.09 (for details see ref. 12). This simulation was performed using ω = 0.0008 s−1 and D = 8 µm2s−1. All other parameters used here were the same as in the main model described in reference 12, except the center coordinate of the bcd mRNA sphere (55 µm in current work). (B) Comparison between simulated [Bn] profile and the experimentally measured mean Bcd profile (with standard deviation shown).23 Both profiles are from early nuclear cycle 14 and each has a length constant λ of ∼100 µm.