G+C content distribution of N. furzeri compared with medaka, stickleback, tetraodon and zebrafish. (a) Histogram of the G+C content of the 5.4 Mb genomic sample of N. furzeri GRZ. The average G+C content is 44.9%. Note G+C distortions, which are seen in a second peak at approximately 62% G+C and an unusually high number of sequences with approximately 41% G+C. Green: sequences containing the most frequent G+C poor 348-nucleotide satellite repeat. Red: sequences containing the most frequent G+C-rich 77-nucleotide minisatellite repeat. (b) G+C content distribution of ten samples of random sequence sets of zebrafish (black), medaka (blue), stickleback (red) and tetraodon (green), respectively. Each data set of the four fish genomes is shown with respect to sequence length distribution and occupied genomic fraction similar to the N. furzeri GRZ 5.4 Mb sample, which, for comparison, is shown as a grey area. Average G+C content values are 36.6% for zebrafish, 40.5% for medaka, 44.6% for stickleback and 46.6% for tetraodon.