Figure 2.

CNEs share a striking nucleotide signature from C. elegans to vertebrates. The plot shows the percentage of A+T nucleotides for 200 bp of sequence flanking CNEs (black) and 15 bp of CNE (red) at the CNE border defined by sequence conservation (the sequence on one end of each CNE is reverse complemented) for (a) F. rubripes, (b) H. sapiens, (c) C. elegans and (d) D. melanogaster. In all four species there is a decrease of A+T content in the 200 bp of sequence flanking the CNEs followed by a sharp A+T increase at the CNE border.