Supplementary Material for: Variation in Missegregation Rates among Human Chromosomes in Hybrid Cells

Chinese hamster ovary-human hybrid cells containing chromosomes 16, 18, X, or 21 have been used to test the ability of human kinetochores to successfully bind to spindle microtubules and to be distributed to daughter cells. The intrinsic rates of non-disjunction among these human chromosomes have been determined and compared to non-disjunction rates in cells presented with taxol as a mitotic challenge. Cells grown on culture slides were fixed and processed for immunofluorescence and fluorescence in situ hybridization. Daughter cell pairs were identified by staining with anti-α-tubulin to identify midbodies. DNA probes specific for human centromeres were used to test for the successful passage of human chromosomes to daughter cells. Our data indicate that different human kinetochores vary in their ability to properly engage the spindle and to be successfully distributed. In addition, our data indicate that the 4 human chromosomes studied can be divided into 2 groups, based on their overall intrinsic rate of non-disjunction and their response to microtubule perturbation. The mechanism of this effect is not yet known.