FIG. 5.

Srb11p is required for reestablishing polarized actin microtubules following transfer to sporulation medium. (A) Wild-type RSY335 (SRB11) or mutant RSY389 (srb11Δ) cells were harvested at the indicated times and stained with phalloidin (see Materials and Methods for details). Cells were scored as small buds (sizes, <10% those of the mothers) or large buds (arrowheads). Image 6 contains a cell with small (left) and large (right) buds. Image 20 contains a large-budded cell (left) and a small-budded cell (right). Final magnification, ×860. (B) Quantitation of actin studies. Wild-type and mutant cells were identified as cells with large and small buds as defined in panel A. Polarized growth was scored as ≥50% the total actin localized to the bud and neck region in the cell (13). At least 100 cells were counted for each time point, except for the wild-type 240-min sample; for this sample, only 25 cells were counted due to the infrequency of finding budded cells in wild-type sporulating cultures after 4 h.