Micronuclei in KIF18A KO cells exhibit chromatin expansion upon exit from mitosis. (A) Stills from time-lapse imaging of micronuclei (arrowheads) in KIF18A KO and nocodazole-treated cells transfected with GFP-H2B to label DNA. (B) Representative traces displaying fold change in micronuclear chromatin area beginning immediately after completion of chromosome segregation at the time of initial micronucleus formation until chromatin was decondensed. Traces shown in B match representative images shown in A. An individual fold change trace indicates a single representative micronucleus per condition. (C) Plot of final fold change in micronuclear area (final area divided by initial recorded micronuclear area) for the indicated conditions. Data points represent individual micronuclei. n = 35 (RPE1 + nocodazole), n = 19 (KIF18A KO untreated), n = 16 (KIF18A KO + DMSO), n = 32 (KIF18A KO + nocodazole). Data were collected from four independent experiments. *, P < 0.0001. Data points indicate individual micronuclei. Error bars indicate SD. (D) Final ratio of fold change in primary nuclear area from the same cells in which micronuclei were measured in C. n = 18 (RPE1 + nocodazole), n = 18 (KIF18A KO untreated), n = 12 (KIF18A KO + DMSO), n = 16 (KIF18A KO + nocodazole). P = 0.80, ns. Data points indicate individual primary nuclei. Error bars indicate SD. Statistical comparisons were made using a one-way ANOVA with Tukey’s multiple comparisons test. Noc., nocodazole.