Figure 3.

Mitotic cell-cycle progression and spindle behavior of wild-type and the dynein mutant. (A) Cell-cycle progression of wild-type and the mutant cells synchronized by hydroxyurea. Wild-type (upper graph) and the dynein mutant (lower graph) cells grown in YEA medium were arrested in S phase with hydroxyurea (Materials and Methods), and synchronously released from the arrest by removing the drug from the medium. After release from arrest, a portion of the cells were fixed at intervals and analyzed for cell types. More than 100 cells were examined at each time point. Percentage of cells containing one nucleus (closed diamonds) and those containing two nuclei, with (closed triangles) or without (open squares) a septum are shown. (B) Time-lapse series of wild-type (left) and dhc1-d2 (right) cells expressing GFP-tagged α-tubulin on a multicopy plasmid. Wild-type (strain CRL152) and mutant (strain CRL1521) cells bearing a GFP-tubulin plasmid, pDQ105 (Ding et al., 1998), were grown in EMM medium supplemented with appropriate amino acids for growth and 5 μM thiamine for the low-level expression of GFP-tubulin, and examined for spindle dynamics at 30°C. Representative series from wild-type and mutant cells are shown. Numbers indicate time in minutes.