Electron micrographs of sft1Δ
cells containing either the 2 μ SFT1 (SARY160) 2 μ
BET1 (SARY181), or 2 μ SNC2 plasmids
(SARY208). Yeast strains were grown at 25°C for 4 h and
permanganate fixed to accentuate membranes. (A) sft1Δ
2 μ SFT1 (SARY160). Overexpression of Sft1p results in
some vacuolar fragmentation as well as the accumulation of some dark
membranous structures. (B) sft1Δ 2 μ
BET1 (SARY181). Cells are indistinguishable from
wild-type (D). (C) sft1Δ 2 μ SNC2
cells (SARY208). Note no significant differences in amount of ER
membranes (compare with A, B, and D) but fragmentation of the vacuoles
and the appearance of numerous dark membranous structures. (D)
Wild-type parental strain (SEY6210, Table 1). The bar in the bottom
right-hand side of each micrograph corresponds to 0.5 μm. N, nucleus;
V, vacuole. The doubling times for each of the strains at 25°C were
pSFT1 sft1Δ (SARY160), 2.0 h; pBET1
sft1Δ (SARY181), 2.3 h; pSNC2
sft1Δ (SARY 208), 6.7 h; and wild-type (SEY6210),
1.9 h (Table 1).