Figure 4.

Distance from SPB proximal to neck 1 min before spindle pole elongation. Wild-type, bud6, bni1, kar9, kip3, and dhc1 mutants containing Tub1-GFP were grown to midlogarithmic growth and examined by fluorescence microscopy. Cells containing a 1–1.5 μm spindle were examined and followed by time-lapse microscopy through spindle elongation. At 1 min before anaphase spindle elongation, a point at the center of the neck was determined in DIC and was used as the origin when measuring the distance to the center of SPB fluorescence. Track Points software in Metamorph (Universal Imaging Corp.) recorded the SPB position at each time point. The distance was determined by converting pixels to microns using the image of the stage micrometer. Values are the average of ten to twenty cells. Wild-type spindles are statistically closer to the neck than spindles in bud6, bni1, kar9, and kip3 mutants as determined by 2-tailed unequal variance Students t test (95% confidence). kar9 spindles are significantly further from the neck relative to bud6, bni1, kip3, and wild-type. Spindle position in bud6, bni1, kip3, and dhc1 are statistically indistinguishable.