FIG. 1.

Mapping of the 16S rRNA positions where intragenomic heterogeneity was observed among the 111 bacterial species analyzed. Intragenomic heterogeneity is represented by nucleotide substitutions between multiple copies of the 16S rRNA gene present in a single organism. Heterogeneous positions were mapped on the secondary structure of one of the E. coli K-12 16S rRNAs. Helices (H) are numbered as described by Cannone et al. (8). Positions indicated in blue are heterogeneous in one species, and those in red are heterogeneous in two or more species.