Fig. 9 PRCs for treatments which affect intracellular Ca⁺⁺  and /or calmodulin. Resetting by the calcium ionophore A23187 is shown in 9A (Aplysia) and 9B (Neurospora). The calmodulin inhibitor trifluoperazine phase-shifts the rhythm of Neurospora (9C). Finally, the calcioum-channel blocker verapamil resets the clock of Euglena (9D).