Clustered third-base substitutions among wild strains of Escherichia coli

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Science  22 Jul 1983:
Vol. 221, Issue 4608, pp. 378-380
DOI: 10.1126/science.6346486


Nucleotide sequences of translated regions of the trp operon in 12 wild strains of Escherichia coli reveal striking uniformity among eight strains (suggesting recent common ancestry and supporting the importance of periodic selection in natural populations) and clustered substitutions in four strains (implicating events affecting runs of nucleotides).