Merotelic attachment leads to the cut phenotype and asymmetric division when interdigitated MTs are defective. (A–D, top) Image series showing an ndc80-gfp cdc11-cfp myo2-gfp cell (A), a rad21-K1 ndc80-gfp cdc11-cfp myo2-gfp cell (B), or an ase1Δ rad21-K1 ndc80-gfp cdc11-cfp myo2-gfp cell (C and D) during mitosis from metaphase to anaphase up to cytokinesis. The six Kts (green) are located between the two SPBs (red) with the actomyosin ring located at the midzone. (middle) Automated tracking analysis of the cell shown above. The number of Kts at each SPB is indicated for each time point on both sides of the kymograph. Kt dynamics (middle) and cytokinesis (bottom, ring contraction) were filmed simultaneously. Arrowheads indicate the positions of the stretched merotelic Kts. (B) After correction (43 min), the Kt moves to the SPB, and cytokinesis takes place. (C) Example of an asymmetric spindle collapse in an ase1Δ mutant in the presence of a merotelic attachment. After completion of cytokinesis, the formation of an anucleate cell and a diploid cell is observed. (D) Example of a symmetric spindle collapse seen in an ase1 mutant in the presence of merotelic attachment. After the execution of cytokinesis, the formation of a cut phenotype is observed.