title: The origin of the bifurcated axial skeletal system in the twin-tail goldfish.
abstract: Twin-tail goldfish possess a bifurcated caudal axial skeleton. The scarcity of this trait in nature suggests that a rare mutation, which drastically altered the mechanisms underlying axial skeleton formation, may have occurred during goldfish domestication. However, little is known about the molecular development of twin-tail goldfish. Here we show that the bifurcated caudal skeleton arises from a mutation in the chordin gene, which affects embryonic dorsal-ventral (DV) patterning. We demonstrate that formation of the bifurcated caudal axial skeleton requires a stop-codon mutation in one of two recently duplicated chordin genes; this mutation may have occurred within approximately 600 years of domestication. We also report that the ventral tissues of the twin-tail strain are enlarged, and form the embryonic bifurcated fin fold. However, unlike previously described chordin-deficient embryos, this is not accompanied by a reduction in anterior-dorsal neural tissues. These results provide insight into large-scale evolution arising from artificial selection.
authors.affiliation: Laboratory of Aquatic Zoology, Marine Research Station, Institute of Cellular and Organismic Biology, Academia Sinica, Yilan 26242, Taiwan.
authors.forename: Gembu
authors.initials: G
authors.lastname: Abe
authors.affiliation: Laboratory of Aquatic Zoology, Marine Research Station, Institute of Cellular and Organismic Biology, Academia Sinica, Yilan 26242, Taiwan.
authors.forename: Shu-Hua
authors.initials: SH
authors.lastname: Lee
authors.affiliation: Laboratory of Aquatic Zoology, Marine Research Station, Institute of Cellular and Organismic Biology, Academia Sinica, Yilan 26242, Taiwan.
authors.forename: Mariann
authors.initials: M
authors.lastname: Chang
authors.affiliation: Laboratory of Aquatic Zoology, Marine Research Station, Institute of Cellular and Organismic Biology, Academia Sinica, Yilan 26242, Taiwan.
authors.forename: Shih-Chieh
authors.initials: SC
authors.lastname: Liu
authors.affiliation: Laboratory of Aquatic Zoology, Marine Research Station, Institute of Cellular and Organismic Biology, Academia Sinica, Yilan 26242, Taiwan.
authors.forename: Hsin-Yuan
authors.initials: HY
authors.lastname: Tsai
authors.affiliation: Laboratory of Aquatic Zoology, Marine Research Station, Institute of Cellular and Organismic Biology, Academia Sinica, Yilan 26242, Taiwan.
authors.forename: Kinya G
authors.initials: KG
authors.lastname: Ota
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D019521:Body Patterning / Q000235:genetics*; D004625:Embryo, Nonmammalian / Q000196:embryology / Q000378:metabolism; D029941:Fish Proteins / Q000145:classification / Q000235:genetics*; D018507:Gene Expression Regulation, Developmental; D005838:Genotype; D006023:Glycoproteins / Q000145:classification / Q000235:genetics*; D006054:Goldfish / Q000196:embryology / Q000235:genetics* / Q000254:growth & development; D017403:In Situ Hybridization; D036341:Intercellular Signaling Peptides and Proteins / Q000145:classification / Q000235:genetics*; D007814:Larva / Q000235:genetics / Q000254:growth & development; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
chemical_list: D029941:Fish Proteins; D006023:Glycoproteins; D036341:Intercellular Signaling Peptides and Proteins; C054234:chordin