Figure 4.

Most mps1 alleles share the mps1–1 SPB phenotype. (A) In mps1–1 cells, a single SPB with very prominent half-bridge (arrow) is seen at the nonpermissive temperature (Winey et al., 1991). (B and C) Strains with the mps1–6 (B; AS181–2b) or mps1–3796 (C; AS131–2d) mutations were shifted to the nonpermissive temperature for 4 h, and their SPB phenotypes were examined by electron microscopy. Both strains exhibited the same SPB morphology seen in panel A: a single enlarged SPB with prominent half-bridge (arrows). This was also observed in mps1–412 and mps1–1237 strains (our unpublished results). Bar, 0.1 μm.