Advection is a general property of PAR proteins. (A) Sample trajectories (>15 frames) from a region in the embryo posterior shown for HaloTag-labeled PAR-1, PAR-2, and PAR-6. Corresponding flow fields derived from PIV analysis of NMY-2 shown on the right. Vector lengths were normalized to highlight direction of vectors. Scale bar = 5 µm. (B) Plots of displacements parallel and perpendicular to the flow axis fit with a Gaussian distribution. Difference calculated via unpaired t-test, two-tailed. (C) Fit values for advection velocity for PAR-1, PAR-2, and PAR-6 from displacements parallel (υx, red) and perpendicular (υy, blue) to the local flow axis highlight drift along the flow axis (τ = 0.5 s). Lines connect paired data from single embryos. (D) Coupling coefficients for PAR-1, PAR-2, and PAR-6 are similar to those observed for PAR-3. Individual embryo data points and mean shown. (E) Mean diffusivity per embryo (τ = 0.2 s) for PAR-1, PAR-2, PAR-3, and PAR-6 highlight lack of correlation between diffusivity and coupling coefficient. Note, PAR-3 data reproduced from Fig. 3 F for comparison. Tukey’s multiple comparison test.
