Table 4. Genetic interactions between ppa2-6, ppa2–Δ, ppa1–Δ, ypa1–Δ, ypa2-7, and ypa2–Δ.

Mutant	ppa1−Δ	ppa2−Δ	ppa2-6	ypa1−Δ	ypa2−Δ	ypa2-7
ppa1−Δ	ND	Synthetically lethal: single, small, rounded cell	Synthetically lethal: 1 or 2 small rounded cells at 32° and 36°	Cold sensitive at 19°, similar to ypa1−Δ	Cold sensitive at 19°, similar to ypa2−Δ	Cold sensitive at 19°, similar to ypa2-7
ppa2−Δ		ND	ND (allelic)	Cells are wee-like ppa2−Δ at >29° and cold sensitive-like ypa1−Δ at 19°	Additive negative effect: cells are cold sensitive at 19°, very slow growing wee at >29°	Cells are wee at >25° and cold sensitive at 19°
ppa2-6			ND	Slow growing colony of rounded, lysed cells	Synthetically lethal: 1–2 rounded cells after germination	Synthetically lethal: 1–2 rounded cells after germination
ypa1−Δ				ND	Synthetically lethal: cells undergo 1–2 divisions dying as rounded cells	Synthetically lethal: cells undergo 1–2 divisions dying as rounded cells
ypa2−Δ					ND	ND (allelic)
ypa2-7						ND

Mutants were crossed at 25°. Tetrads were dissected and spores were germinated on complete medium at 32°. In cases were lethal interactions were observed, other temperatures were tested, but no temperature in the range of 19°–36° altered the result obtained. At least 10 tetrads were analyzed for all double mutant combinations. ND, not done.