Fig. 4. Morphology of clb1 conditional cells. (A) Morphology of the wild-type and mutant cells in restrictive conditions. FB1 and UMP25 cells were incubated for 9 hours in MM-NH₄. Two clear morphologies can be seen: unbudded and budded cells, all of them with a single nucleus per cell (right panel shows DNA stained with DAPI). Scale bar: 10 µm. (B) Microtubule organization in UMP25 cell arrested after 6 hours in rich medium. Note that in arrested cells long microtubules reach from the neck to the growing tip. (C) UMP25 cells incubated for 25 hours in rich medium have a distinct phenotype characterized by a extensive polarized growth (upper horizontal panel) disorganized tubulin cytoskeleton (middle horizontal panel) and empty sections behind that are separated by septa (stained with calcofluor in lower horizontal panel, arrows point the septa) generated by formation of basal vacuoles (arrow; vertical panel). Scale bars: (horizontal panels) 10 µm; (vertical panel) 5 µm.