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Fig. 4 Directional movement of vegetal cortical granules is dependent on parallel microtubule arrays. (A-D) Schematics showing position of beads relative to the arrays. DMSO bead is shown as a solid black circle (A); nocodazole beads are shown as solid blue circles (B-D); parallel arrays are shown as solid green lines (A-D), nocodazole-disrupted arrays as dashed green lines (B-D), and granules are depicted as open black circles (A-D). (E-H) Dclk2-GFP-labeled arrays show extent of disruption of microtubules in bead-treated embryos (time of image in mpf at bottom right of each panel; yellow asterisks indicate granules tracked). (I-L) Granules in embryos treated with DMSO control beads and granules at a distance from nocodazole-soaked beads travel faster (A,C,I,K), than granules adjacent to nocodazole beads (B,D,J,L), which do not show much movement. Graphs in K,L are from granules at different locations in the same embryo. (M-P) Tracking the trajectory of the granules shows that DMSO control beads do not affect directed granule movement (M), similar to granules at a distance from nocodazole-soaked beads (O). By contrast, granules near nocodazole-soaked beads show random movement, and sudden changes in the direction of movement (N,P). Trajectory of individual granules is shown as hatched black lines; blue open arrowheads show initial granule position. (Q,R) Absence of nuclear β-Catenin accumulation in dorsal cells (R) indicates the effect of transient and local nocodazole treatment on dorsal specification in comparison to control DMSO treatment (Q; yellow arrowheads indicate β-Catenin-positive nuclei). (S) Distance traveled by individual cortical granules in control bead or nocodazole bead-treated embryos. Scale bars: in E-H, 15 μm; in Q,R, 50 μm.