Figure 2.
B-type cyclins induce distinct chromosome missegregation when overexpressed. (a) Representative images of cells with indicated chromosome segregation errors. Scale bar, 10μm. (b) Live-eel I imaging analysis of chromosome segregation errors in Ccnb1r7 and Ccnb2n6 transgenic primary MEFs with and without transgene induction for 72 h. Anaphase failure refers to complete failure of sister chromatid separation producing one daughter with 4N DNA and one with out DNA. The analysis was carried out on three independent MEF I ines per genotype (>20 cells per line were analysed). Statistical significance was determined by a two-tailed, unpaired t-test. Statistics source data are provided in Supplementary Table 2. *P < 0.05; **P <0.01. (c) Schematic representation of the separase activity biosensor (top) and time-lapse images of biosensor-positive Ccnb1r7 MEFs progressing through mitosis in the absence or presence of transgenic eye I in Bl. hSCCl, human sister chromatid cohesion protein l. Sea le bars, 5μm. (d) Quantification of biosensor fluorescence at chromosomes as cells progress through mitosis. Data represent mean ± s.e.m. from five independent experiments. We note that the level of overexpression varied among dox-treated Ccnbzr7 MEFs, with those showing anaphase bridges expressing significantly higher levels of HA-cyclin B1 than those without bridges.