Fig. 1

Spindles reassemble by rotational movements of MTs. a Spindle reassembly assay. Mitotic cells were cooled to 1 °C to depolymerize MTs (Methods). Once the temperature was increased to 24 °C, MTs grew from the SPBs and reassembled the spindle. b Time-lapse images of spindle reassembly in a wild-type cell expressing GFP-tubulin and Sid4-GFP (strain KI061). Images are maximum-intensity projections, time is given in min:s, scale bar, 1 μm. Corresponding schemes are shown to the right. c Scheme showing how the formation of an antiparallel MT bundle occurs in two steps. SPBs are represented as spheres and MTs as rods. d Reassembly time, defined as the time from the onset of MT growth until the formation of the antiparallel MT bundle (spindle) between the SPBs, as a function of the distance between the SPBs at the onset of MT growth. n = 87 cells; pink data points denote cells in which the spindle was not reassembled within 10 min. e Number of polar MTs per cell during the first 5 min following the onset of MT growth, n = 28 cells, error bars, s.e.m.