Table 3.

Spontaneous mutation rates of S. cerevisiae strains

Strain	Key alleles	Mutation rate* × 109	Relative rate†
DBY747	Wild type	7.0  ±  4.4	1
SBU	mms2	216.6  ±  50.0	31.0
WXY9382	rev3Δ	8.7  ±  5.0	1.2
SBUr3L	mms2 rev3Δ	8.7  ±  5.0	1.2

^*All strains are isogenic and carry the revertable trp1-289 amber mutation. Rates are expressed as number of revertants per cell per generation. The results shown are the mean ± SD of five (DBY747 and SBU) or three (WXY9382 and SBUr3L) sets of experiments. 

^†Relative to the wild-type strain.