TABLE 3.

Effects of ogg and dbh on spontaneous mutation

Mutation typea	Wild type				ogg				dbh				ogg dbh
	Countb	%	Observed ratec	Relative to WT	Count	%	Observed rate	Relative to WT	Countb	%	Observed rate	Relative to WT	Count	%	Observed rate	Relative to WT
Tract expansion	46	42.2			23	27.4			29	26.1			5	4.9
Tract contraction	22	20.2			10	11.9			18	16.2			0	0.0
Isolated base pairs inserted	1	0.9			0	0.0			5	4.5			0	0.0
Isolated base pairs deleted	2	1.8			0	0.0			1	0.9			1	1.0
Total indels <5 bp	71	65.1	3.76	1	33	39.3	1.74	0.46	53	47.7	0.87	0.23	6	5.8	1.68	0.45
G to T + C to A	2	1.8	0.11d	1d	35	41.7	1.85d	17.43d	26	23.4	0.43d	4.05d	95	92.2	26.6d	251d
Other transversions	8	7.3			2	2.4			5	4.5			0	0.0
Transitions	18	16.5			9	10.7			17	15.3			0	0.0
Total BPS	28	25.7	1.48	1	46	54.8	2.43	1.64	48	43.2	0.79	0.53	95	92.2	26.6	17.9
Tandem dupl >4 bp	8	7.3			3	3.6			9	8.1			1	1.0
Deletions >4 bp	2	1.8			2	2.4			1	0.9			1	1.0
Total indels >4 bp	10	9.2	0.53	1	5	6.0	0.26	0.50	10	9.0	0.16	0.31	2	1.9	0.56	1.06
All mutations	109	100	5.77e	1	84	100	4.43e	0.77	111	100	1.83	0.31	103	100	28.8	4.99

^aIndel, insertion or deletion; dupl, duplication.

^bpyrE mutations in wild-type (DG185) and dbh (CS2) strains were determined by Sakofsky et al. (12); spectra for Δogg (RJ13) and Δogg Δdbh (RJ803) strains were determined in the present study, using the same procedure (see Materials and Methods).

^cMutation rates for wild-type, ogg, dbh, and ogg dbh strains (RJ12, RJ13, RJ401, and RJ803, respectively) were determined in the present study (see Materials and Methods). The rate for each major type of mutation was calculated as the indicated percentage of the overall mutation rate.

^dValues for G-to-T transversions are provided for comparison to the aggregate categories.

^eThe 95% confidence intervals of the mutation rates for strains RJ12 (wild type) and RJ13 (ogg) overlap.