Properties of calcium signal spreading are independent of the amounts of photolysis-induced calcium transients. A through E, in the inserts, the 5 μm2 areas that were illuminated with UV light for photolysis of NP-EGTA are indicated with white circles; the positioning of the uncaging spot was guided by MitoTracker staining shown in red. Arrows point towards the positions of calcium measurements at the indicated distances from the uncaging spot. Time courses of calcium transients were measured at the indicated distances in squares of 6 × 6 pixels (filled white squares). A and B, propagation of a photolysis-induced cytosolic calcium signal within the cytosol. C, propagation of a photolysis-induced cytosolic calcium signal within the cytosol and across the NE. D and E, propagation of photolysis-induced smaller size nuclear (D) or cytosolic (E) calcium signals within the compartment and across the NE. UV light was switched on as indicated by the dashed line (A, B, and C, t
= 16.4 msec; D and E, t
= 10.2 msec). Images were taken every 401 msec. Scale bar is 5 μm.