Fig. 5. Centrosome reduplication.

A GFP-tubulin labeled binucleate kif9 null cell with a centrosome pair in one nucleus (upper circle in panel 0:00), one unoccupied nucleus (lower circle in panel 0:00), and a cytosolic centrosome that has separated into daughters (arrowheads). Over the next 8 min, one of the cytosolic daughter centrosomes (right arrowhead) moves to and into the unoccupied nucleus (visible at 8:50 as enhanced fluorescence). The cell remains in this configuration for about one hour, at which time both nuclear centrosomal complexes appear to reduplicate. The top pair forms an aberrant spindle complex with four poles, the bottom daughter centrosome forms an abbreviated spindle with two poles. This cell eventually cleaved into six parts. Time, min:sec, bar, 5 µm.