Dynamics of Granules Entering Protrusions
(A) Representative time-lapse images of a single granule (shown by orange arrow) entering a protrusion. Scale bar, 5 μm.
(B) (i) Representative transient profile showing that granule speed (dashed blue line) increases with coil width (solid red line). Inset plots of granule position show near-stationary granules translocate persistently at high speeds during coiling cycle, following which they become near-stationary again. (ii, iii) Speed and persistence of the granules increase with increasing protrusive fiber diameter. (iv) Representative MSD versus time profiles and their calculated MSD for granules on different protrusive fiber diameters show that on all tested diameters, the granules enter the protrusions in a superdiffusive manner (exponent of the scaling law fit >1). Inset, MSD exponent as a function of protrusive fiber diameter shows an increase (on average) with increasing diameter. n values are as follows: 135 nm, 19; 270 nm, 17; 450 nm, 12; 600 nm, 21; 1,000 nm, 20.
See Methods section for a discussion of the statistical significance parameters. Data are represented as mean ± SEM. ∗p < 0.05 and ∗∗∗p < 0.001.