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Figure 5 | BMC Evolutionary Biology

Figure 5

From: Phylogenetic analysis of the vertebrate Excitatory/Neutral Amino Acid Transporter (SLC1/EAAT) family reveals lineage specific subfamilies

Figure 5

Selective gene loss within the vertebrate lineage leads to species specific SLC1 subfamilies. (A) Schematic representation of the vertebrate phylogenetic tree. Major superclasses, classes and infraclasses are indicated and color coded for easier comparison and identification. The species used in the following phylogenetic analysis are shown by representative pictures. (B) The number of active SLC1 genes varies within different species. Due to the fish specific genome duplication (R3), ray finned fish have an increased number of SLC1 genes as indicated by the presence of 'b' paralogs, which cannot be found in other vertebrates. Note that also within the actinopterygian lineage selective gene loss occurs (striped background) as no SLC1A7b paralog can be found in the medaka genome. Within the tetrapod lineage, theria have lost both the SLC1A8 and the SLC1A9 gene, whereas prototheria and archosauromorpha have only lost the SLC1A9 and lepidosauromorpha have lost the SLC1A8 gene. Further gene loss can be observed in some avian species (SLC1A5) and in the green lizard Anolis carolinensis (SLC1A6). (C) Maximum likelihood phylogeny of analyzed vertebrate species. The phylogenetic tree was build using 361 representative amino acids residues determined by the program Gblocks after sequence alignment using MUSCLE. Bootstrap values above 50% (0.5) are shown. Species belonging to the different superclasses, classes and infraclasses are highlighted in the same colors as used in Figure 5A. Note that members of the newly identified SLC1A8 and SLC1A9 subgroups all group together forming indeed a separate branch within the SLC1 tree (highlighted in red). The scale bar shows the percentage (0.3 equals 30%) of amino acid substitutions required to generate the corresponding tree.

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