Nucleotide frequencies of several gene classes, separated according to the concentration of a dinucleotide in the [-400,400] region around the TSS. A. Human genes with few CpG doublets. B. Human genes with many CpG doublets. C. Fugu genes with few CpGs. D. Fugu genes with many CpGs. E. Fly genes with many ApTs. F. Fly genes with few ApTs.