Files in this Data Supplement:
Fig. S1. Mitotic variability in kif9 null cells. (A,B) Mitotic timing in wild-type and kif9 null cells respectively. Traces plot the distance between spindle poles as a function of time, green tracks distance in mononucleated cells, blue traces represent one spindle in a multinucleated cell. In all cases, there are no extra cytosolic centrosomes. Panel A shows WT cells (n = 12); Panel B shows kif9 null cells (n = 20). Time 0 represents the earliest point that we observe a cell enter mitosis. The point where the poles begin to separate in a linear fashion marks the transition between prometaphase and metaphase. (C) A histogram where the data are binned in 10 min intervals. In wild-type cells, prometaphase is complete within a 10 min window.
Fig. S2. All centrosomes trigger cytokinetic furrows. A GFP-tubulin labeled binucleate kif9 null cell containing (after duplication) two nuclear spindles and four cytosolic daughter centrosomes (eight centrosomes altogether). As karyokinesis concludes, the cell volume is constricted into eight portions. Note that four of these cytokinetic fragments contain normal centrosome/DNA content, whereas the extra cytosolic centrosomes are ejected as cytoplasts. Time, min:sec, bar, 5 µm.
Fig. S3. Nuclear import of tubulin at the G2/M transition. Line scan of pixel intensity across a kif9 null cell before (A) and 90 s after (B) the nucleus becomes permeable to GFP-tubulin. The area roughly between pixels 40–80 corresponds to the position of the nucleus. In A the nuclear intensity is depressed relative to the cytoplasm and the nucleus appears dark (e.g. Fig. 1, 0:00). In B the level is increased relative to the cytosol, and the nucleus is brighter than the surrounding area (e.g. Fig. 1, 0:30). This result suggests that tubulin import is an active, tightly regulated process.
