Aurora B kinase-dependent spreading of centromeric cohesin during mitosis. (a) Synchronous progression through mitosis after release from cdc25-22-imposed G2 arrest. Examples of cells at the indicated time points are shown. Microtubules were visualized by a GFP-Atb2 fusion protein; DNA is counterstained with DAPI. The percentages of cells with short metaphase (meta) or elongated anaphase (ana) spindles, as well as the septation (sept.) index, were counted in at least 100 cells at each time point. (b) Chromatin immunoprecipitation against Rad21-Pk9 during the timecourse in (a) is compared to G1-arrested cells, and to cdc25-22-synchronized anaphase cells lacking aurora B kinase activity due to chemical inhibition of ark1-as3. A 100 kb region including the centromere of chromosome 2 is shown. Outer, dg2 and dh2, and inner, imr2, centromeric repeat sequences and the central core, cnt2, are indicated. Additional blue bars above and below the midline represent ORFs transcribed from left to right and opposite, respectively. A ribosomal protein gene is highlighted in red.