Fig. 5: Chromosomes are separated with no obvious anaphase spindle elongation.

a Live-cell images of EGFP-α-tubulin and RCC1-mCherry from metaphase to anaphase. b Graphs showing changes of distances between centrosomes (black, n = 8), spindle poles (green, n = 8), separating chromosomes (red, n = 8), and chromosome and spindle pole (blue, n = 16) in (a) from 8 embryos. c Graphs of fluorescence intensities for line scans of spindles in (a) showing that EGFP-α-tubulin intensities remain between separating chromosomes during anaphase. The positions of chromosomes (magenta arrowhead), spindle poles (gray arrow), and centrosomes (gray arrowhead) were defined based on the fluorescent intensity profile along the long axis of the spindle. d Immunofluorescence images using anti-α-tubulin antibody showing metaphase (top) and anaphase spindles. e, f Live-cell images of EMTB-3xGFP (e) or EGFP-EB1 (f) from metaphase to anaphase. g Live-cell images of control (top) and nocodazole-treated (bottom) 4-cell spindles in anaphase. h Graphs showing the duration of mitosis in DMSO or nocodazole-treated 4-cell blastomeres. i 330 nM nocodazole-treated 4-cell blastomeres showing fewer MTs around metaphase chromosomes and abnormal chromosome segregation. j Quantification of abnormal segregation phenotypes. k Live-cell images of EGFP-α-tubulin and RCC1-mCherry in the presence of 170-nM nocodazole. l Graphs showing changes of distances between spindle poles (green, n = 11), separating chromosomes (red, n = 11), and chromosome and spindle pole (blue, n = 22) in (k) from 11 embryos. m A model of anaphase spindle MTs showing chromosome segregation without spindle elongation. Error bars indicate mean ± SD. Scale bars = 100 μm. Source data for (b, c, h, j, l) are provided as a Source Data file.