Figure 6: Model of the interplay between the molecular clockwork and PDF signalling.

Nighttime-specific role of PDF in the LNv and DN1 clock neurons in the pacemaker circuit. At night, PDF depolarizes the membrane potential and leads to the upregulation of CLK/CYC-mediated transcription. PDF also promotes PER stability in a manner independent of neuronal activity via cAMP-PKA signalling. This nighttime-specific action of PDF on the molecular clock can amplify molecular oscillations and contribute to the synchrony of the pacemaker neurons. Dotted arrows indicate possible indirect controls.