TABLE 1.

Summary of mutation frequencies and error rates

RT	Total no. of mutations	Total no. of colonies	Mutation frequency	Error rate
HIV-1	176	13,186	0.013	7.5 × 10−5
PFV	208	7,033	0.03	1.7 × 10−4

The total number of mutations detected by DNA sequencing was divided by the number of colonies screened by using the blue/white colorimetric assay. This gives the mutation frequency (mutations/colony). The total length of the target sequence is defined as being 174 nt (from the starting GGA codon to the end of the first termination codon). Dividing the mutation frequency by the length of the LacZα coding region gives the error rate (mutations/nt).