Table 1. Sequence alterations in metronidazole-resistant mutants.

Alteration	Wild type		polA		PolA++
	No. recovered*	Rate (10−8)	No. recovered*	Rate (10−8)	No. recovered*	Rate (10−8)
1 bp substitutions	19 (65)	43	6 (11)	0.6	14 (39)	10725
transversions	6 (21)	14	4 (7)	0.4	13 (36)	9960
transitions	13 (44)	29	2 (4)	0.2	1 (3)	321
1 bp insertion	2 (7)	4	16 (29)	1.6	15 (42)	11491
1 bp deletion	6 (21)	14	4 (7)	0.4	6 (17)	4596
>1 bp insertion	1 (3)	2	22 (41)	2.2	0 (0)	0
>1 bp deletion	1 (3)	2	6 (11)	0.6	1 (3)	550

*( ): percent of total events.