Proposed somatostatin receptor evolutionary scheme

<p>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.</p> <p><strong>Figure 2 Proposed somatostatin receptor evolutionary scheme. </strong>Numbers denote<br>chromosome or linkage group assignments of SSTR genes in mapped genomes. Some of the<br>SSTR genes have not been mapped to chromosomes or linkage groups, which is indicated by<br>asterisks. Evolutionary scheme: Two ancestral vertebrate SSTR genes located on two<br>different chromosomes duplicated in 2R, generating the vertebrate SSTR gene repertoire of<br><em>SSTR1, -4</em> and <em>-6</em>, and <em>SSTR2, -3</em> and <em>-5</em> respectively. <em>SSTR6</em> was lost from the lobe-finned<br>fish lineage some time after the divergence of the coelacanth, and <em>SSTR4</em> was lost from the<br>ray-finned fish lineage some time before the divergence of the spotted gar. Following<br>chromosome fusions, the ancestral teleost <em>SSTR2, -3</em> and <em>-5</em> genes duplicated in 3R, while<br>only one gene for each of <em>SSTR1</em> or <em>-6</em> genes were conserved in some teleost lineages.<br>Subsequent chromosome rearrangements in teleost evolution moved SSTR genes to different<br>chromosomes. Data from neighboring genes families are consistent with these chromosome<br>rearrangements. Not all SSTR subtype genes could be identified in some teleost genomes<br>(Table 1). This could be either due to genuine gene losses, or perhaps due to the incomplete<br>nature of these genome databases.</p>