Figure 5.

Modelling the equilibration of a molecule synthesised in the heterocyst. The model represents a 22-cell filament. Cells 6 and 17 are heterocysts and the remainder are vegetative cells. The heterocysts begin to synthesise a molecule at time zero, and then continue to produce it at a constant rate. Spread of the molecule is modelled assuming E=0.022 s⁻¹ (heterocyst–vegetative cell exchange) and 0.29 s⁻¹ (exchange between vegetative cells) (Table I). The predicted relative concentration in each cell is shown for various time points.