Movie 7.

Sevilletor implementation of the Clock and Gradient (CG) model. 2D simulation of the Clock and Gradient model implemented in the Sevilletor framework (Fig. 4H). Left: wild type simulation. Modulations promoted by R (k₁) and FG (k₃, k₄), and u and v signaling are shown side-by-side. The virtual tail grows with a constant speed by addition of a line of cells at the bottom (posterior). The posterior side (bottom) has k₁ = 1 that promotes out of phase oscillations of the two reactants. The anterior side (top) has a bistable behavior that promotes a progressive freezing of oscillations, which generates a periodic somite pattern with k₁ = 4. Phase waves are promoted by a gradient of k₃ and k₄ that controls the frequency of oscillations. Right: Simulation with 5% multiplicative noise added to phase values (u, v) and 0.5%multiplicative noise to parameters (k₁, k₃, k₄). The model is robust to noise but as time progresses, the noise that accumulates in the frequency gradient begins to disorganize the somite pattern.