16-cell purple urchin embryo expressing three tandem GFPs fused to the ensconsin microtubule-binding domain (EMTB-3G; Faire et al., 1999). The embryo was treated with 20 µM trichostatin A (TSA), an inhibitor of HDAC6 (a tubulin deacetylase) that selectively disrupts dynamic microtubules in mammalian cells, at time 00:00. Within minutes of TSA addition in metaphase, asters were reduced to nearly nothing (04:00). Despite reduction in spindle length, cells enter anaphase (07:20) and complete cytokinesis (11:20–16:10). No microtubules connecting the mitotic apparatus to the cortex are visible. Embryos were imaged with a laser scanning confocal microscope (Radiance 2000; Bio-Rad Laboratories) mounted on a compound microscope (E800; Nikon) using a 40× 1.3 NA Plan-Fluor oil lens at room temperature. Corresponds to Figure 4A and first segment of video 4 in J Cell Biol. 2009 Dec 14;187(6):831-45.