SC frequency based on the third nucleotide shows disequilibrium among exons and differs between algal (A) and land plant (B-E) genomes. NNA, NNT, NNC and NNG are defined as the ratio of total SCs with A, T, C and G at the third position, respectively to 59 SCs. The equivalent ratios in the other genomes investigated are shown in Figure S5.
Qin et al. BMC Genomics 2013 14:56 doi:10.1186/1471-2164-14-56