Fig. 1

Patterns of GC content and G/C stretches in avian and other vertebrate genes. a Dot plot of avian genes, displaying the GC-content and average length of stretches containing G or C nucleotides. G/C-stretch was defined as an undisrupted sequence of at least three consecutive G or C nucleotides. The complete set of approximately six thousand chicken RefSeq genes from the UCSC genome browser database [17] is depicted by blue circles. Only coding sequences longer than 299 nucleotides were analyzed. The set of 86 avian genes reported to be missing in chicken genome [1] are depicted by open circles, and 23 avian genes newly assembled in this study are shown as red circles. Additionally, a histogram showing the distribution of average G/C-stretch length in the chicken RefSeq gene category is depicted by a blue line. b Dot plots of selected avian genes, compared with their vertebrate orthologs. GC-content and average length of G/C stretches in coding sequences of chicken MMP14 and LPPR2 (reported as missing in birds [1]), and genes from the EPO and EPOR loci are shown. If available, orthologous genes from other birds, turtles, mammals, lizards and crocodilians are included in the plots. The blue dots show the distribution of chicken RefSeq genes. Sequences of newly assembled avian genes represented in this figure, and GenBank accession numbers of sequences plotted in panel B are listed in Additional file 1 and Additional file 4, respectively