Live imaging in X. laevis embryos reveals actin cables around the mitotic spindle, which are unaffected in Myo10 morphants. (a) Images taken from a video showing F-actin organization in a control mitotic spindle (see Video 7) using mCherry–α-tubulin (red) to visualize the spindle and the GFP-Utr-CH probe (green) to visualize F-actin. Highly dynamic F-actin cables surround the spindle as it assembles (t = 0:00–2:00, arrows) and are concentrated around the poles later in mitosis, especially during anaphase (t = 11:00 and 13:00, arrows). (b) An enlarged view of the uppermost spindle pole from panel a showing that F-actin (GFP-Utr-CH, green) is concentrated around the pole, with some F-actin cables appearing to emanate from the pole (t = 0:00 and 0:06, arrows) and others from the cortex (t = 0:12, arrows). (c) Stills taken from a video of a second control spindle (see Video 8) demonstrating that the assembly of F-actin cables between the spindle and the cell cortex coincide with spindle movement (t = 0:00–0:18, arrows) and concentrate as a pole is drawn toward the cortex (t = 0:24 and 0:30, arrows). (d) Images taken from a video showing F-actin (GFP-Utr-CH, green) organization during Myo10 morphant spindle assembly (see Video 9). F-actin cables associate with the morphant spindle as it assembles (arrow), just as occurs in controls. (e) Stills of a multipolar spindle in a Myo10 morphant (see Video 9) demonstrating that F-actin associates with each of the poles and follows the motion of the spindle (arrows). In each panel, time stamps indicate time in minutes and seconds.