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. 2012 Jul 31;7(7):e41019. doi: 10.1371/journal.pone.0041019

Figure 4. (a) Load to the Repressor triggers a Non-functional Clock.

Figure 4

The plots illustrate the trajectories of system (14) with two different amounts of load. The parameters in the simulation were Inline graphic, Inline graphic, Inline graphic, Inline graphic, Inline graphic, Inline graphic, Inline graphic and Inline graphic. The amount of DNA binding sites in the system with no load is Inline graphic whereas in the system with repressor load is Inline graphic. (b) Hopf Bifurcation with Inline graphic as a parameter. A continuation of the equilibrium as a function of the load parameter Inline graphic shows that, for this set of parameters, the amount of load required to activate the clock is in the same order of magnitude as that of the the affinity coefficient Inline graphic, with bifurcation occurring at Inline graphic. This plot was obtained via continuation of system (14) with the same parameters as before. Solid lines indicate a stable trajectory (limit cycle to the right of the Hopf bifurcation and the equilibrium to its right). The dotted line indicates an unstable equilibrium point. (c) Period increases as a function of the repressor load Inline graphic.