Fig. 1.

Optogenetic stimulation of PA-Rac1 on a lattice light-sheet microscope. a Volumetric acquisition using LLSM. b Top-down view of LLSM acquisition of a cell, in comparison to the lattice light-sheet excitation plane. c Schematic representation of optogenetic excitation using the SLM to produce controlled 445-nm excitation, shown in right panel. Using the SLM in the excitation path results in discontinuous excitation. d RPE1 cell stimulated using SLM-based excitation (as described in c) of PA-Rac1 does not suppress filopodia (red arrows) and no ruffles are observed. Scale bar = 5 μm. e Schematic representation of wide-field optogenetic excitation passed through the detection objective leading to continuous excitation, shown in right panel. f Dorsal membrane ruffles (magenta arrows) and increased protrusion along the coverslip (green arrows) produced following wide-field optogenetic stimulation (as described in e). Scale bar = 10 μm. g Growth of PA-Rac1 ruffles in response to photoactivation. Scale bar = 3 μm. h Boxplot of PA-Rac1 ruffle length (μm) vs photoactivation laser power (mW). Outer range shows total range, box height shows the standard deviation, and inner bar shows mean (n = 45 ruffles)