Microtubule dynamics during spindle movement. (A) Time series images of GFP-Tub1 in a WT cell during a dynein-dependent sliding event. Each image is a maximum intensity projection from a confocal Z series. Black arrowheads point to the plus end of the sliding microtubule. The red arrowhead points to the plus end at the time of a catastrophe event. Bar, 1 µm. (B) Life plot of the microtubule depicted in A. Sliding Event denotes the time during which the microtubule is moving laterally along the cell cortex and the spindle is moving. Black and gray dots are the total length of the microtubule measured from the SPB to the microtubule plus end at 14 successive time points. Blue dots are the length on the microtubule laterally touching the cell cortex during nine successive time points. (C) Time series images of GFP-Tub1 in a WT cell during a dynein-dependent sliding event with the microtubule catastrophe at the start of the sliding event. Black arrowheads point to the plus end of the sliding microtubule. The red arrowhead points to the plus end at the time of a catastrophe event. Bar, 1 µm. (D) Life plot of the microtubule depicted in C. (E) Dot plot of time during a sliding event (seconds) the microtubule spent in polymerization (Polym) or depolymerization (Depolym). n = 39 for each. Horizontal bars show the mean of values. (F) Mean catastrophe frequency during sliding events, compared with all other times in pre-anaphase WT cells. Error bars are SEM, and p-value is determined by t test. Nonsliding microtubules, n = 24; sliding microtubules, n = 41. (G) Scatter plot depicting the coefficient of determination for microtubule time spent in depolymerization (seconds) and sliding duration. n = 33 sliding events. The dotted line is the best fit to a linear correlation. (H) Scatter plot depicting the coefficient of determination for maximum microtubule (MT) length during a sliding event and sliding duration. n = 35 sliding events.