(A) Wiring diagram of the oscillator. A messenger RNA encodes the synthesis of a protein, which can convert into a repressor, i.e. due to post-translational modifications of the protein. The repressor impedes the synthesis of the messenger RNA, which creates a negative feedback loop allowing sustained oscillations in the levels of RNA, protein, and repressor. Here, a miRNA can regulate the level of RNA by forming an inhibitory complex, RNAi. Time evolution of RNA, miRNA and protein is shown in the absence (V
SMIRNA = 0 in B, D) or in the presence of miRNA (V
SMIRNA = 0.1 in C, E); as well as in the presence of intermediate (n = 4 in B, C) or high degree of oligomerization (n = 12 in D, E) amongst repressor molecules to down-regulate the synthesis of RNA. The model shows that the presence of miRNA promotes sustained oscillations of large amplitude. Parameter values are as in Table 2.