Table 1. Mutation rates and sequencing data for the yeast strains used in this study.

The 95% confidence intervals (CI) were calculated as described in reference [18]. The sequencing data for the POL2⁺ rnh201Δ strain are from reference [11]. The total number of FOA^r mutants sequenced exceeds the number of mutations because some of the mutants had no sequence change in the URA3 open reading frame. These mutants may have arisen due to sequence changes in the URA3 promoter or another gene that affects resistance to 5-FOA. Because these mutants contribute to the overall mutation rate, they are included in the calculation of rates for individual mutation classes.

URA3 orientation	OR1	OR2	OR1	OR2
Strain	POL2+ rnh201Δ		pol2–4 rnh201Δ
Mutation rate (× 10−8)	3.1	3.7	21	36
95% CI	(2.7–3.5)	(3.3–4.5)	(18–26)	(29–45)
ura3 mutants sequenced	251	273	216	200
Single base substitutions	86	89	154	57
Single base indels	27	14	26	15
Total 2–5 base deletions	25	96	11	27
Other*	19	13	3	0

^*Other mutations include mutations involving multiple bases (deletions of >5 bases, insertions of >1 base, duplications and complex mutations). Sequencing data for the POL2⁺ rnh201Δ strain is from [11].