Figure 1.

Teleost wnt4a is the ortholog of tetrapod WNT4. (A) Phylogenetic analysis shows that vertebrates have two Wnt4-related clades (designated Wnt4a and Wnt4b). The Wnt4a clade includes teleosts and gar as ray-finned fish and coelacanth, birds, and mammals as lobe-finned fish. The Wnt4b clade also includes teleosts and gar as ray-finned fish as well as coelacanth and birds, but not mammals, as lobe-finned fish. This result shows that the duplication event that produced the wnt4a and wnt4b clades predated the divergence of ray-finned (e.g., gar, teleost) and lobed-finned (e.g., coelacanth, bird, mammal) lineages. (B) A dot plot comparing zebrafish orthologs and paralogs of genes on the short arm of human chromosome 1 (Hsa1p) shows conserved syntenies along zebrafish chromosome Dre11 (wnt4a) and Dre16 (wnt4b). (C) Conserved synteny analysis shows that the zebrafish chromosome segments containing wnt4a and wnt4b are orthologous to regions on different spotted gar chromosomes, and that these two spotted gar chromosomes show ancient paralogy. Based on phylogenetic and conserved synteny analyses, wnt4a and wnt4b were both in the last common ancestor of zebrafish and humans but mammals lost the ortholog of wnt4b, and wnt4a in teleosts is the ortholog of WNT4 in mammals.