Figure 3

Genomic organisation of human LBX/TLX cluster paralogons and putative orthologous counterparts. Genomic organisation of human (Hs) Lbx/Tlx paralogons and the putative orthologous counterparts identified in Mus musculus (Mm), Xenopus tropicalis (Xt), Gallus gallus (Gg), Danio rerio (Dr), Tetraodon nigroviridis (Tn) and Takifugu rubripes (Fr). For simplicity, only three teleosts are included in this figure: additional data for Oryzias latipes (medaka) and Gasterosteus aculeatus (stickleback) can be found in additional file 1. The main genes characteristic of each paralogon are included in the figure; additional genes and linked genes found further away can be found in additional file 1. Schematic representations of the orthologous genomic regions are depicted in panels 1–4, which correspond to human paralogons 1–4 in figure 2. Gene orthology is indicated by colour code and was inferred from molecular phylogenetics (see additional files). Genes appearing in more than one orthologous region are underlined. Numbers at the ends of each line indicate chromosome (chr) or scaffold (s) numbers. A parallel red line marks gaps in the sequence, while triple black lines indicate large intergenic distances. Blue dots mark sites of inversions, red arrows the end of a contig. Boxes off-line represent genes for which genomic sequences are incomplete; where no chromosome or scaffold number is given, no linkage data is available. In some cases, "missing" genes can be found on different scaffolds or chromosomes. This data is shown in additional file 1. In addition, we do not show the dispersed 2^nd teleost Lbx2 paralogon that no longer contains an Lbx or Tlx gene, but this information is included in additional file 1. The genes our phylogenetic analysis identified as Lbx1 are found in a similar genomic environment, linked to orthologs of the genes present at the human LBX1/TLX1 locus. In addition, non-mammalian Lbx1 genes are linked to the Slc2a15 gene not found at any other Lbx locus. Lbx2 genes are linked to Loxl3, Aup1 and Pcgf1 genes (genomic information incomplete for chicken and frog), while Tlx3 genes are linked to the orthologs of human KCNIP1, NMP1, FGF18 and BTRC2. In teleosts, Fgf24 and Npm4 are part of the Lbx2 locus, while in all species examined, Fgf17 and Npm2 are no longer linked to Lbx/Tlx genes.