Figure 5.

ComparisonResponse of the negative feedback module. This module is simulated with a (A) gradient signal and a (B) localized signal input. The response of the module when the feedback strength is varied is shown for when the feedback element Y is non-diffusible and highly diffusible. (A) R^∗is shown for (non-diffusible case) k_yx = 14.0 (solid line) and (diffusible case) k_yx = 14.0 (dashed line). (B) R^∗is shown for (the non-diffusible case) k_yx = 10.0 (solid line) and 14.0 (solid line with circles) and (the diffusible case) k_yx = 10.0 (dashed line) and 14.0 (solid line with x markers). The response exhibits a profile qualitatively similar to the signal but the concentration everywhere is reduced due to the negative feedback. As the feedback constant k_yx increases, the total concentration of the response decreases everywhere. The spatial profile of R^∗in the diffusible case shows stronger spatial variation than the corresponding non-diffusible case.