MITOSIS IN LIVING BUDDING YEAST - ANAPHASE A BUT NO METAPHASE PLATE

Chromosome movements and spindle dynamics were visualized in living ce lls of the budding yeast Saccharomyces cerevisiae. Individual chromoso mal loci were detected by expression of a protein fusion between green fluorescent protein (GFP) and the Lac repressor, which bound to an ar ray of Lac operator binding sites integrated into the chromosome. Spin dle microtubules were detected by expression of a protein fusion betwe en GFP and Tub1, the major alpha tubulin. Spindle elongation and chrom osome separation exhibited biphasic kinetics, and centromeres separate d before telomeres. Budding yeast did not exhibit a conventional metap hase chromosome alignment but did show anaphase A, movement of the chr omosomes to the poles.