Fig. 2. Contractile ring position is uncoupled from nuclear position in pom1 mutant. (A) Time-lapse video-microscopy of wild-type (a) or pom1 cells (b,c) that express mid1-4GFP and were grown at 25°C during entry into mitosis. Cells were imaged for GFP fluorescence every 4 minutes. Note that, in pom1 cells the contractile ring forms away from the position of the premitotic nucleus (star), closer to the non-growing end where mid1-4GFP spots were distributed before mitosis. Bar, 5 µm. (B) Localization of myo2p in the pom1 mutant: myo2-GFP fluorescence in pom1 cells grown at 25°C (left) and time-lapse video-microscopy of a similar cell in early mitosis (right). Note the asymmetrical distribution of myo2-GFP cortical spots in early mitosis (arrow). In the early mitotic cell on the right, asymmetrically distributed spots of myo2-GFP (t=0-6 minutes) compact into an offset tight ring (t=14 minutes) that contracts (t=34 and 50 minutes) to form two daughter cells of unequal size (t=78 minutes). Star, position of the premitotic nucleus. Bar, 5 µm.