Figure 2.

Persistent total centromere dissociation in csi1Δ lem2Δ cells results in spindle failure. (A) In wt cells, all centromeres are clustered beneath the SPB during mitotic interphase. Double deletion of csi1 and lem2, or sad1.2 cells grown at restrictive temperature (36°C), lead to centromere dissociation from the SPB during interphase. (B) Series of frames of films of mitotic cells harboring Sid4-mCherry (SPB), Mis6-GFP (centromeres) and ectopically expressed mCherry-Atb2 (Tubulin). Bars, 5 µm. Numbers indicate mitotic progression in minutes; t = 0 is the SPB duplication stage. Yellow arrowheads point to SPBs failing to separate. (C-D) Quantitation of centromere dissociation exemplified in (B). Total centromere dissociation of the centromeres from the SPB is never observed in wt or csi1Δ cells. sad1.2 grown for 4h at 36 °C commence total centromere dissociation from the SPB.