The NK Homeobox Gene Cluster Predates the Origin of Hox Genes Claire Larroux, Bryony Fahey, Sandie M. Degnan, Marcin Adamski, Daniel S. Rokhsar, Bernard M. Degnan  Current Biology  Volume 17, Issue 8, Pages 706-710 (April 2007) DOI: 10.1016/j.cub.2007.03.008 Copyright © 2007 Elsevier Ltd Terms and Conditions

Figure 1 Bayesian Phylogenetic Tree of ANTP Class Genes Clades containing sponge (Amphimedon queenslandica) and cnidarian (Nematostella vectensis) genes are indicated by a star and a circle, respectively. Three circles for NK2/3/4 and NK5/6/7 clades reflect the presence of NK2, NK3, NK4, NK5, NK6, and NK7 genes in the Nematostella genome. Asterisks indicate strong Bayesian support (greater than or equal to 95% posterior probability) for branches separating NK-related and Hox-related clades. Current Biology 2007 17, 706-710DOI: (10.1016/j.cub.2007.03.008) Copyright © 2007 Elsevier Ltd Terms and Conditions

Figure 2 The Amphimedon NK Cluster All NK-related genes are in blue; they are all in the sense direction, except Tlx- and Hex-related genes. Gray ovals indicate nonhomeobox genes that encode proteins most similar to the following: 1, lysophospatidic acid acyl transferase; 4, kinesin 2 family member KIF3B/C; 5, Drosophila rolling stone; 6, tetracycline resistance gene; 7, vacuolar protein sorting 8; 10, inositol-triphosphate phosphatase; 11, kinesin 5 family member KIF11; and 12, FGF receptor. Ovals 2, 3, 8, and 9 represent unknown hypothetical open reading frames. Ovals indicate the approximate positions of genes within the contig but do not represent comparative gene size. Current Biology 2007 17, 706-710DOI: (10.1016/j.cub.2007.03.008) Copyright © 2007 Elsevier Ltd Terms and Conditions

Figure 3 Evolution of ANTP Genes LIM-HD, Prd, Six, POU, and ANTP metazoan-specific homeobox classes originated prior to the divergence of sponge and eumetazoan lineages (the TALE class predates opisthokont cladogenesis). The original ANTP gene (shown in blue) was NK like and expanded through cis-duplication to give rise to an ancestral NK cluster consisting of five or six genes. Genes present in the ancestral NK cluster are based on phylogenetic analyses (Figure 1 and Figure S3) and conserved ordering of these genes in demosponges and bilaterians (Figure S4). Parentheses indicate low phylogenetic support for orthology between sponge and bilatrerian NK genes. This cluster continued to expand and rearrange in the eumetazoan lineage to give rise to a cluster that includes the full complement of NK-like genes and the ProtoHox gene (shown in green). In this scheme, ProtoHox (Hox) and Dlx dissociated from the ancestral NK cluster. Current Biology 2007 17, 706-710DOI: (10.1016/j.cub.2007.03.008) Copyright © 2007 Elsevier Ltd Terms and Conditions