Fig. 1. Myo2 rings form after the onset of mitosis. (A) A series of images from a movie of Myo2 ring contraction in a myo2-gc cell. In the CAR shown, contraction took place in 24 minutes. (B) myo2-gc cut12-gsp; SPB separation (upper cell) occurs before Myo2 ring formation (lower cell). Left hand panel: Myo2-GFP and Cut12 GFP fluorescence; middle panel: DAPI- phase; right hand panel: DNA (blue) and Myo2-GFP and Cut12-GFP signal overlay (green). (C) Timing of cell cycle events in myo2-gc cut12-gfp cells synchronised by size selection. Cells with two SPBs (filled red triangles) appear slightly ahead of cells also containing Myo2 rings (filled green circles), that is, Myo2 rings are seen only in cells in which SPB duplication and separation has occurred. Binucleate cells (filled blue diamonds) and septa (filled black squares) appear after Myo2 ring formation. (D) Timing of cell cycle events in myo2-gc cut12-gfp cdc25-22 cells synchronised by transient temperature shift. The relationship between Myo2 ring formation and SPB separation is as in (B). Bar, 10 µm.