Mitosis in living budding yeast: anaphase A but no metaphase plate.

Chromosome movements and spindle dynamics were visualized in living cells of the budding yeast Saccharomyces cerevisiae. Individual chromosomal loci were detected by expression of a protein fusion between green fluorescent protein (GFP) and the Lac repressor, which bound to an array of Lac operator binding sites integrated into the chromosome. Spindle microtubules were detected by expression of a protein fusion between GFP and Tub1, the major alpha tubulin. Spindle elongation and chromosome separation exhibited biphasic kinetics, and centromeres separated before telomeres. Budding yeast did not exhibit a conventional metaphase chromosome alignment but did show anaphase A, movement of the chromosomes to the poles.