Spindle length and variation increase upon depletion of cohesin and condensin. (A) Spindle length was measured between the spindle pole bodies (Spc29-RFP) in metaphase cells of WT, Gal-CDC20, Gal-H3, cohesin mutants mcm21Δ and mcd1-1, and condensin mutants brn1-9 and smc4-1. Cells were followed over time to ensure that measurements were taken in metaphase and not in linearly increasing anaphase spindles. The micrograph depicts a WT metaphase spindle. The white bracket represents spindle length as measured by the distance between the two spindle pole bodies. The error bars represent SEM. Bar, 1 µm. (B) Spindle length variation over time in metaphase is graphed for WT, Gal-CDC20, Gal-H3, cohesin mutants mcm21Δ and mcd1-1, condensin mutants brn1-9 and smc4-1, and cells containing an active dicentric chromosome. Spindle pole bodies were filmed at 35-s intervals for 11.7 min. Variation in spindle length was calculated by the absolute value of the difference between spindle length at each time point and the mean spindle length over a time lapse. The error bars represent 95% confidence. (A and B) Mutants that are statistically significantly different (P < 0.05) from WT are marked with an asterisk. Mutants with the same number of asterisks are statistically similar (P > 0.05), whereas those with a different number of asterisks are statistically different (P < 0.05). (C) Representative graphs of spindle length over time for Gal-H3, mcm21Δ, brn1-9, and mcd1-1 (black lines). WT is graphed (dashed gray lines) for comparison.