Table 2. Mutation spectrum of secondary mutations in the β-lactamase gene.

	100-500*		500-1,050*		100-1,050*
Mutations	n	%	n	%	n	%
Transitions
AT → GC	10	33.3	7	36.8	17	34.7
GC → AT	13	43.3	9	47.4	22	44.9
Transversions
AT → TA	5	16.7	2	10.5	7	14.3
AT → CG	1	3.3	0	0	1	2.0
GC → TA	1	3.3	1	5.3	2	4.1
GC → CG	0	0	0	0	0	0
Total	30	100	19	100	49	100

These data exclude frameshifts, which were not scored in this assay.

^*Location of sequence is relative to the origin of replication.