Fig. 5. Maximum intensity projections from a 4D sequence of a dividing neuroblast containing GFP-tagged kinetochores and centrosomes. Kinetochores are labeled with GFP-fzy and centrosomes with GFP-fzr. GFP-fzy appears on kinetochores (A, arrows and small arrowheads) at NEB, while GFP-fzr is present on centrosomes (A, large arrowheads) as cells enter mitosis. After attaching to the spindle, sister kinetochores (e.g. gray and white arrows and arrowheads in A-F; filled and open circles and triangles in G) rapidly achieve a stable equatorial position. During early prometaphase some attaching kinetochores (A,B, gray arrows) exhibit a sudden rapid motion towards the proximal pole (A,B, large gray arrowhead). In the example here, the chromosome then moves away from the pole along a vector that does not intersect the distal centrosome (small white and gray arrows in B,C). These sister kinetochores then exhibited an arc-like motion that positioned them on the metaphase plate (C,D), after which they remained stationary (E,F). By comparison, sister kinetochores on chromosomes more centrally located between the centrosomes at NEB quickly become bioriented, after which they congress in one relatively smooth motion (small arrowheads in A-C; open and filled triangles in G). Time is in minutes and seconds. Bar, 10 µm. (G) Plot showing the behavior of sister kinetochores marked by the gray and white arrows/arrowheads in A-F. The positions of sister kinetochores denoted by the gray and white small arrows/arrowheads, relative to their respective poles, are plotted on the graph as filled and open circles and triangles. Letters at the top of the graph note the time points corresponding to panels (A-F).

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