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Conservation And Variation Of Nucleotide Sequences In Escherichia Coli Strains Isolated From Nature, Lawrence G. Harshman, Monica Riley

Lawrence G. Harshman Publications

A group of Escherichia coli isolates from nature were compared with one another and with laboratory strains of E. coli with respect to size distribution of chromosomal restriction endonuclease fragments and differences in nucleotide sequences in selected small portions of the genomes. The estimated frequency of base substitutions in nucleotide sequences in and near the trp operons of 26 of the 28 E. coli strains examined ranged from 0.008 to 0.066. Nucleotide sequences in or near λ prophage homologs were significantly more variable than the sequences in or near trp, tnaA, and thyA genes. Thus, the λ-homologous regions …