A new technique called CaST (calcium-activated split-TurboID) uses an enzyme to rapidly tag cells that have elevated calcium levels in living animals, marking activated cells within 10 minutes. The tagging signal increases with both calcium concentration and labeling time, acting as a time-gated integrator of total calcium activity. Unlike transcriptional reporters that take hours to produce a signal, CaST provides readout immediately after activity labeling. The method was used to tag prefrontal cortex neurons activated by psilocybin in untethered mice, and the CaST signal correlated with psilocybin-induced head-twitch responses.
A new enzyme-based method called CaST (Ca2+-activated Split-TurboID) biochemically tags cells with elevated calcium levels in living animals within 10 minutes, without requiring implants or light delivery. The signal increases with calcium concentration and labeling time, acting as a time-gated integrator of calcium activity. Unlike transcriptional reporters that take hours, CaST allows immediate read-out after activity labeling. The approach was used to tag prefrontal cortex neurons activated by psilocybin in untethered mice, and the CaST signal correlated with psilocybin-induced head-twitch responses.