Loss of Csi1 results in mitotic delays and sensitivity to perturbations in kinetochore–microtubule interactions. (A) Time-lapse microscopy of Sid4-RFP and Mis6-GFP during mitosis. Pictures were taken at 2-min intervals. (B) The distribution of time to finish anaphase A. Time was measured from separation of SPB to the reclustering of centromeres at the SPB, indicated by arrows in A. n represents number of mitosis counted from a single experiment. (C) The percentage of cells showing Bub1-GFP foci in populations of asynchronously growing cells. n represents number of cells counted from a single experiment. (D) Genetic interaction profiles of csi1Δ. Tetrad dissection of individual crosses was performed to analyze genetic interactions between csi1Δ and other mutants. For a conclusion of lethal genetic interactions, ≥50 tetrads from each cross were dissected, and no double mutants were obtained. (E) A model showing that centromere clustering during interphase facilitates kinetochore capture by microtubules during mitosis. The clustered centromeres serve as a higher affinity platform for concerted capture by microtubules. MAP, microtubule-associated protein; WT, wild type. Bar, 1 µm.