Figure 6

Convergence states achieved by a 100 cell system from 20 biologically feasible randomly chosen initial conditions. The position of each cell in the system is on the abscissa and on the ordinates the index of a random initial condition. A black rectangle indicates that, at the converged state, the cell in that position has been differentiated into a heterocyst: A: Wild type in presence of nitrogen. No heterocysts are formed. B: Wild type in the absence of nitrogen. On average 1/10 cells differentiates into a heterocyst. C: patS knock-out in the absence of nitrogen. Clusters of heterocysts are formed. D: hetR over-expressed in the absence of nitrogen. Clusters of heterocysts are formed at a lower frequency than for patS knock-out. E: hetR over-expressed in the presence of nitrogen. Differentiation into heterocysts at a lower frequency than for hetR over-expression in the absence of nitrogen.