TIME-LAPSE MICROSCOPY REVEALS UNIQUE ROLES FOR KINESINS DURING ANAPHASE IN BUDDING YEAST

The mitotic spindle is a complex and dynamic structure. Genetic analys is in budding yeast has identified two sets of kinesin-like motors, Ci n8p and Kip1p, and Kar3p and Kip3p, that have overlapping functions in mitosis. We have studied the role of three of these motors by video m icroscopy of motor mutants whose microtubules and centromeres were mar ked with green fluorescent protein. Despite their functional overlap, each motor mutant has a specific defect in mitosis: cin8 Delta mutants lack the rapid phase of anaphase B, kip1 Delta mutants show defects i n the slow phase of anaphase B, and kip3 Delta mutants prolong the dur ation of anaphase to the point at which the spindle becomes longer tha n the cell. The kip3 Delta and kip1 Delta mutants affect the duration of anaphase, but cin8 Delta does not.