MT dynamics are altered in cyclin A2 knockout oocytes. (a) Representative time-lapse images of MII-stage cyclin A2^fl/fl and cyclin A2^−/− oocytes. PAGFP-α-tubulin (green) was photoactivated (PA) using a 405-nm laser, and the time course of PAGFP fluorescence decay was monitored. Spindle MTs were visualized using X-rhodamine (red), and chromosomes were visualized using Hoechst 33342 (blue). Bars, 2 μm. (b) Normalized fluorescence decay curves obtained by measuring the loss of PAGFP fluorescence in cyclin A2^fl/fl (n = 7) and cyclin A2^−/− oocytes (n = 8). Decay plots show fast and slow components assumed to represent non-kMTs and kMTs, respectively. Fluorescence decay after Taxol treatment is used to determine the bleaching coefficient for each time point. Error bars represent SEM. (c) Calculated half-life of fast (non-kMTs) and slow (kMTs) shows that MTs have a longer half-life in cyclin A2^−/− oocytes. Error bars represent SEM. *, P < 0.05 by t test.