title: Ectopic Six3 expression in the dragon eye goldfish.
abstract: For goldfish (Carassius auratus), there are many varieties with different eye phenotypes due to artificial selection and adaptive evolution. Dragon eye is a variant eye characterized by a large-size eyeball protruding out of the socket similar to the eye of dragon in Chinese legends. In this study, anatomical structure of the goldfish dragon eye was compared with that of the common eye, and a stretching of the retina was observed in the enlarged dragon eye. Moreover, the homeobox-containing transcription factor Six3 cDNAs were cloned from the two types of goldfish, and the expression patterns were analyzed in both normal eye and dragon eye goldfish. No amino acid sequence differences were observed between the two deduced peptides, and the expression pattern of Six3 protein in dragon eye is quite similar to common eye during embryogenesis, but from 2 days after hatching, ectopic Six3 expression began to occur in the dragon eye, especially in the outer nuclear layer cells. With eye development, more predominant Six3 distribution was detected in the outer nuclear layer cells of dragon eye than that of normal eye, and fewer cell-layers in outer nuclear layer were observed in dragon eye retina than in normal eye retina. The highlight of this study is that higher Six3 expression occurs in dragon eye goldfish than in normal eye goldfish during retinal development of larvae.
authors.affiliation: State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Graduate School of the Chinese Academy of Sciences, Wuhan 430072, China.
authors.forename: Dong-Mei
authors.initials: DM
authors.lastname: Ma
authors.forename: Hua-Ping
authors.initials: HP
authors.lastname: Zhu
authors.forename: Jian-Fang
authors.initials: JF
authors.lastname: Gui
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D005123:Eye / Q000033:anatomy & histology / Q000196:embryology / Q000378:metabolism*; D005136:Eye Proteins / Q000235:genetics* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D006054:Goldfish / Q000196:embryology / Q000235:genetics* / Q000378:metabolism; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution; D015854:Up-Regulation; D000097607:Homeobox Protein SIX3
chemical_list: D005136:Eye Proteins; D018398:Homeodomain Proteins; D009419:Nerve Tissue Proteins; D000097607:Homeobox Protein SIX3