Video 8. Single and double centrosome ablations in a sand dollar embryo coexpressing ensconsin-3xGFP (cyan) and mC-H2B (yellow). Time-lapse sequence of single confocal sections (Atto CARV). Video corresponds to Fig. S5 B. Real times are indicated, and the video is encoded at 15 frames/s. Bar, 25 µm.
Animal cells decide where to build the cytokinetic apparatus by sensing the position of the mitotic spindle. Reflecting a long-standing presumption that a furrow-inducing stimulus travels from spindle to cortex via microtubules, debate continues about which microtubules, and in what geometry, are essential for accurate cytokinesis.
In normal cells, the cytokinetic apparatus forms in a region of lower cortical microtubule density. Ablation of a single centrosome displaces furrows away from the remaining centrosome; ablation of both centrosomes causes broad, inefficient furrowing.