Figure 3:

Analysis of the synthetic gene circuit with a gene with an inducible promoter and a self-activation module. (A) Diagram of interaction between a synthetic gene circuit with a gene with an inducible promoter (x₁) and self-activation (x₂) modules and growth rate. (B) The bifurcation diagram of x₂ with respect to R₁. Solid and dashed lines correspond to stable and unstable steady state points. Solid circles denote the saddle-node bifurcation points (blue, orange, yellow, and purple for SN1-4, respectively). (C-D) Two-parameter bifurcation diagram shows the dependence of the saddle-nodes (SN1-4) on J (Q in (D)) and R₁. SN1 (blue line), SN2 (orange line), SN3 (yellow line), and SN4 (purple line) correspond to the saddle-node bifurcation points. The red region represents the ON-state of x₂ Module, the green region corresponds to the system bistability, and the white region represents the OFF-state of the x₂ module