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. 1999 Jul 20;96(15):8522–8527. doi: 10.1073/pnas.96.15.8522

Figure 3.

Figure 3

Disruption of HSL7 stimulates haploid invasive growth and diploid pseudohyphal development. (A) Elongated cell morphology of the haploid hsl7Δ and diploid hsl7Δ/hsl7Δ strains. Deletion of STE20 abolished their elongated cell morphology. Yeast strains were cultured at 30°C in yeast extract/peptone/dextrose (YPD) medium for 3 days. Cells were visualized under the microscope with Nomarski optics. (B) Disruption of HSL7-stimulated invasive growth in haploid cells. (Left) Genotypes of the strains examined. (Center) Total growth. (Right) Haploid invasive growth. Σ1278b-derived strains: YAF1108 (MATa HSL7+ STE20+ leu2 ura3) and its otherwise isogenic derivatives YAF1191 (MATa hsl7Δ∷LEU2), YAF1192 (MATa ste20Δ), and YAF1193 (MATa hsl7Δ∷LEU2 ste20Δ). Strains were streaked onto YPD plates and grown for 3 days at 30°C. The plate shown in Center was rinsed under a stream of running water to distinguish surface growth from invasive growth by the degree of agar penetration (8). (C) Disruption of HSL7 enhanced pseudohyphal growth in diploid cells. Diploid strain YAF1111 (MATa/MATα HSL7/HSL7 STE20/STE20 leu2/leu2 ura3/ura3) was constructed from YAF1108 and YAF1110 (MATα HSL7+ STE20+ leu2 ura3) in the Σ1278b background. Diploid strains YAF1194 (MATa/MATα hsl7Δ∷LEU2/hsl7Δ∷LEU2), YAF1195 (MATa/MATα ste20Δ/ste20Δ) and YAF1196 (MATa/MATα hsl7Δ∷LEU2/hsl7Δ∷LEU2 ste20Δ/ste20Δ) are YAF1111 derivatives. Every diploid strain contained vectors carrying URA3 and/or LEU2 to complement the ura3 and/or leu2 auxotrophies. These transformants were streaked on SLAD medium (15) and allowed to grow for 4 days. Resulting colonies were photographed. (D and E) Expression of the FRE-lacZ reporter gene. The eight strains described in B and C were transformed with a plasmid YEpU-FTyZ (6) (and a LEU2-containing vector to complement leu2), and β-galactosidase activity was measured. (D) Haploid strains on SD medium. (E) Diploid strains on nitrogen-starved medium. Activities were normalized to protein concentration and are shown as relative to the activities of wild-type strain. Values are the averages of measurements made in triplicate.