In vivo microrheology of C. elegans yolk-granule mobility. (a) Three representative DIC image time series of the midplane of a C. elegans embryo taken from the Valfort et al. data set (32) (N2 embryo time-series N2_15, N2_18, and N2_20 taken from http://www.ens-lyon.fr/LBMC/NematodeCell/2010/12/) are marked to highlight the regions of the embryo in which yolk-granule mobility was analyzed: the anterior (A; red), posterior (P; blue), and two transverse regions, T1 (green) and T2 (magenta). Scale bar, 5 μm. (b) The change in position along x (Δx) across the transverse axes and in y (Δy) across the A-P axes of individual granules are plotted as a function of time (gray lines). Colored lines represent the mean profiles for the A (red), P (blue), T1 (green), and T2 (magenta) regions. (c) The probability of oscillatory frequencies, P(f), is plotted from mean distance-time data for A (red), P (blue), T1 (green), and T2 (magenta) regions (open circle). Solid circles indicate the dominant frequencies. For color references, please refer to the online edition. To see this figure in color, go online.