Figure 1.

The network of the Drosophila circadian clock. (a) Cartoon depicting the Drosophila circadian molecular network; protein and mRNA are represented by capital letters and lower case, respectively. Red arrows and cyan lines indicate stimulatory and inhibitory interactions, respectively. The green arrow ending in X indicates that CRY protein enhances the degradation of TIM. The amounts of CYC and DBT are assumed to be constant. (b) Loop diagram of the network showing the CWO autorepressive loop (cwo, CWO), the per/tim and vri negative loops, and the Pdp1 (pd) positive loop. (c) Cartoon depicting a hypothetical example of molecules x_j, where 1 ≤ j ≤ n, regulating the state of molecule x_i by positive (red arrows) or negative (cyan lines) interactions. Positive and negative real parameters are regulatory weights that simulate stimulation and repression, respectively (see Eq. 1).