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Figure S2. The rga1Δ phenotype in diploid cells, the effects of deletion of bud-site selection genes on the rga1Δ phenotype in haploid cells, and an aborted attempt to bud within the old division site. (A) Bud-scar distribution in wild-type and rga1Δ diploid cells. This experiment was performed as described for Fig. 1 A except that the two yeast strains are YEF473 (wild-type diploid) and YEF1233 (rga1Δ/rga1Δ). (B) Effects of bud-site selection genes on the phenotype of rga1Δ haploid cells. This experiment was performed as described for Fig. 1 A except that the following haploid yeast strains were used: YEF473A (WT), YEF2324 (rga1Δ), AM100 (bud3Δ), YZT146 (rga1Δ bud3Δ), LRSy359 (rsr1Δ), and YZT139 (rga1Δ rsr1Δ). Please note that bud3Δ and rsr1Δ strains appear to have more cells with multiple bud scars than the wild-type strain does, which may reflect some underscoring of this class of cells in the wild-type strain because of potential masking of adjacent scars in this strain. (C) Mother cell aborts the attempt to bud within the old division site and ultimately chooses the distal pole for budding. Please note that a new rotational angle of the 3D images for time points 32 min 53 s to 44 min 34 s was chosen for better visualization of the aborted septin ring (within the old division site) and the second new septin ring at the distal pole of the cell. Arrowhead, old septin ring at the previous division site of the mother cell; arrow, the first new septin ring within the old ring. Because the old septin ring and the first new septin ring are at almost exactly the same position, which is certainly consistent with the stacked bud scars of nearly identical diameter for most rga1Δ cells, a clear distinction of the old septin ring versus the first new septin ring could sometimes be difficult. However, based on ring size and brightness (a new ring is invariably smaller and brighter than the old ring), we can make the judgments with confidence, at least for the majority of the cells. Bar, 1 μm.