Analysis of the distribution of runs of As and Ts in selected genomes. Run length is indicated on the x-axis; the ratio of pattern occurrence on the y-axis. (a) Ratio of occurrences in coding regions and in entire genomic sequences. (b) Ratio of occurrences of A runs in real genomes and average occurrence in 1,000 randomized genomes. Biases preserved during the randomization procedure are indicated above each pair of graphs. Accession numbers are as follows: NC_000913 E. coli K12; NC_000915 Helicobacter pylori; NC_000963 Rickettsia prowazekii; NC_001318 Borrelia burgdorferi; NC_002163 Campylobacter jejuni; NC_003450 Corynebacterium glutamicum; NC_003364 Pseudomonas aeruginosa; NC_004344 Wigglesworthia glossinidia.