Cytoplasmic dynein is required for poleward chromosome movement during mitosis in Drosophila embryos

The movement of chromosomes during mitosis occurs on a bipolar, microtubule -based protein machine, the mitotic spindle. It has long been proposed that poleward chromosome movements that occur during prometaphase and anaphase A are driven by the microtubule motor cytoplasmic dynein, which binds to ki netochores and transports them toward the minus ends of spindle microtubule s. Here we evaluate this hypothesis using time-lapse confocal microscopy to visualize, in real time, kinetochore and chromatid movements in living Dro sophila embryos in the presence and absence of specific inhibitors of cytop lasmic dynein. Our results show that dynein inhibitors disrupt the alignmen t of kinetochores on the metaphase spindle equator and also interfere with kinetochore- and chromatid-to-pole movements during anaphase A. Thus, dynei n is essential for poleward chromosome motility throughout mitosis in Droso phila embryos.