Statistical analysis of adenine substitutions. Frequencies of the four bases were determined for each adenine-corresponding position in the VRs of our data set. Bars represent the mean values of these frequencies over the total results set (A) or the Bacteroides cluster 1 (B). Error bars are +/− standard deviation. The frequencies of the three nucleotides C, T and G in (A) were significantly different from each other (p < 0.001, χ2 test).
Schillinger et al. BMC Genomics 2012 13:430 doi:10.1186/1471-2164-13-430