Evolutionary scenario for the vertebrate SSTR gene-bearing chromosome regions

Published in: Ocampo Daza D, Sundström G, Bergqvist CA, Larhammar D. The evolution of vertebrate somatostatin receptors and their gene regions involves extensive chromosomal rearrangements. BMC Evolutionary Biology 2012, 12:231 doi:10.1186/1471-2148-12-231. Please refer to this article if using this figure. <strong>Figure 6 Evolutionary scenario for the vertebrate SSTR gene-bearing chromosome<br>regions. </strong>Two ancient vertebrate chromosomes bearing one SSTR gene each duplicated in 2R,<br>generating two vertebrate paralogons; one bearing <em>SSTR1, -4</em> and <em>-6</em> genes (purple, pink, blue<br>and turquoise blocks) and one bearing <em>SSTR2, -3</em> and <em>-5</em> genes (red, yellow, orange and green<br>blocks). After the divergence of lobe-finned fishes (including tetrapods) and ray-finned fishes<br>(including teleosts), three of the 2R-generated blocks fused in the ray-finned fish lineage before 3R. Both paralogons duplicated in 3R, followed by rearrangements between<br>paralogous chromosome blocks, obscuring the ancestral conserved synteny. One of the fused,<br>duplicated and rearranged chromosome blocks split through a fission event. The paralogous<br>chromosome regions have been reconstructed for the chicken, human and medaka genomes<br>by mapping the identified paralogous gene families. The upper color blocks represent<br>ancestral chromosome regions in each lineage. Dashed boxes represent losses of chromosome<br>blocks. Chromosome rearrangements involving blocks of genes are represented by arrows,<br>while smaller translocations of genes are represented by dashed arrows. The full datasets are<br>presented in Tables S4 and S5 (see Additional files 3 and 4).