Figure 4.

Inactivation of Bir1 stabilizes kinetochore attachments. Kinetochores (Mtw1-Venus, green) are detached from the spindle axis (spindle pole bodies marked by Spc97-CFP, red) in the ndc80-1 mutant at the nonpermissive temperature (PWY329-19C). In a bir1-107, ndc80-1 double mutant, bipolar attachment is restored (PWY329-16D). Cells were shifted asynchronously to 37°C for 60 min. Localization of kinetochores was quantified when both spindle pole bodies were in focus and both spindle pole bodies were still in the mother cell. Spindles were scored as attached if no Mtw1-Venus signal was seen outside of the spindle axis. Images are scaled equally. Bar, 1 μm.