Fig. 5. During anaphase B, microtubule plus ends are dynamic but do not show depolymerization at minus ends. (A) Images of anaphase B spindle elongation. The region of overlap between the two half spindles gradually decreases as the spindle elongates. The strain used here is 2694. The GFP:Swi6-stained centromeres mark the location of the spindle poles in each daughter nucleus. Bar, 2 µm. (B) Kymograph of the anaphase B time-lapse movie seen in A. The increased fluorescence in the center of the kymograph, delineated by arrows, reflects the overlap of oppositely oriented polar microtubule plus ends. The triangular patterns reflect the growth and shrinkage of individual microtubules. The asterisk marks the distance between unique fluorescence patterns in the spindle microtubules due to uneven incorporation of GFP:-tubulin and the bright spindle pole labeled by GFP:Swi6 at the centromeres. This distance remains constant as the spindle elongates. SP, spindle pole; midzone, zone of overlap of antiparallel microtubules. Bar, 2 µm.