Chromosome deviations in cell populations. (A–C) RPE1 (A), HCT116 (B), and HT29 (C) cells were grown in flasks and were untreated or treated with monastrol or nocodazole. Mitotic cells were harvested by shake-off, washed to remove the mitotic inhibitor, and plated in growth medium to allow the completion of mitosis. Cells were then harvested for FISH analysis at the indicated times. Mean deviation from the mode for two different chromosomes in each of two independent experiments, with 600 nuclei counted per chromosome per time point and condition for each experiment. Error bars are SEM. *, P < 0.05, χ2 test. (D) Diploid cells showing two pairs of chromosomes (one red and one blue) that segregate faithfully during most mitoses. A chromosome missegregation event occurs, generating two nondiploid daughter cells that do not propagate efficiently, so the overall karyotype of the culture remains diploid (top). A phenotypic change (gray cells) arises either independently of chromosome missegregation (as shown) or coordinated with the missegregation that permits nondiploid cells to propagate (bottom). Chromosome missegregation subsequently generates aneuploid cells in this population as those cells continue to accrue abnormal chromosome numbers.
