Fig. 2. (A) Partial nuclear division in slk19 cells occurs prior to initiation of anaphase. cdc20 GAL-CDC20 (US3398) and cdc20 slk19 GAL-CDC20 (US3399) cells were arrested in G1 using factor and released into YEPD at 24°C. At the end of 4 hours, the cells were collected and analyzed for the state of nuclear (DAPI) division (top panel and bottom graph; for each time point, 150 cells were counted). In a parallel experiment, G1 synchronized cdc20 (US3568) and cdc20 slk19 (US3579) cells containing SCC1-cmyc₁₈ were released into YEPD at 24°C. Samples were analyzed for the levels of Scc1, Clb2 and tubulin, and DNA content. ^*Denotes cleaved Scc1 (middle panel). To check whether partial nuclear division occurs in another kinetochore-component-defective mutant, cdc20 ndc10-1 GAL-CDC20 (US4708) cells were subjected to identical experimental regime as described above (bottom panel). (B) Spindles in slk19 cells. Samples taken at 240 minutes from both US3398 and US3399 cells as described in (A) were stained using anti-Tub4 antibodies.