Low number of kinetochores in taxol-treated cells display crescent-like morphology resembling unattached kinetochores. (A and A′) WF (A) and structured-illumination (A′) images (maximum-intensity projection) of a taxol-treated metaphase cell stained for CenpT (red) and Hec1 (green). Full optical series through the centromere region of a chromosome (box) with an expanded crescent-like kinetochore is shown at higher magnification. Black numbers indicate height of each optical slice (nm) within the volume. One sister kinetochore is compact, whereas the outer layer (Hec1) of the sister forms an extended crescent. The difference in the organization of sister kinetochores is particularly prominent in SI microscopy. Bars: (main) 5 µm; (insets) 1 µm. (B) SI image (maximum intensity projection, MIP) of a metaphase cell treated with 3 µM nocodazole for 15 min during metaphase. Centromere regions of chromosomes from the boxed areas are shown at higher magnification. The outer kinetochores (Hec1) consistently form crescents that encircle the centromere. Formation of the crescents is not always apparent in planar views (maximum intensity projections) because of orientation of the centromere in space. However, expansion of the outer layer is consistently detected in complete optical series through the centromere region. Bars: (main) 5 µm; (insets) 1 µm.