Figure 3

Odds ratios of having a poly(A) or poly(T) HT with a given length in the first 10% of coding genes. Observed frequencies for poly(A) or poly(T) HT (with length between 5 and 9 nt) located in the region encompassing the 5' 10% of all genes (based on pooled data for all 99 genomes) were compared to expected frequencies (calculated based on a randomly generated dataset created under the assumption that the location of the respective HTs are uniformly distributed within coding genes). Y axis shows the odds ratios, e.g. an odds ratio of 2.3 for an A₉ tract indicates that A₉ HTs are 2.3 fold more likely to occur in the first 10% of a coding gene as compared to their expected frequency. The lower limits of 95% confidence intervals for all Odds Ratios were > 1, indicating that all poly(A) or poly(T) HT shown (i.e, those with sizes between 5 and 9 nt) occur significantly more commonly in the 5' 10% of genes in the prokaryotic genomes evaluated than expected by chance.