Table 1.

[PSI+ss] is more stable in siw14Δ than in the siw14Δ/+ host

Isolate no.	Ura+/total subclones
	siw14Δ	siw14Δ/+
1	48/48	4/25
2	41/41	9/29
3	35/35	1/16
4	39/40	0/26
5	31/31	1/17
6	31/36	2/22
7	50/50	2/12
8	41/41	2/23

Ura+, guanidine-curable clones induced in strain 5255 (siw14Δ [PIN+]) were subcloned on YPAD medium or mated with strain 4729 (SIW14 [psi−]) and then subcloned on YPAD medium. Subclones were tested for [PSI+] by replica-plating on −Ura plates.