title: The medaka zic1/zic4 mutant provides molecular insights into teleost caudal fin evolution.
abstract: Teleosts have an asymmetrical caudal fin skeleton formed by the upward bending of the caudal-most portion of the body axis, the ural region. This homocercal type of caudal fin ensures powerful and complex locomotion and is regarded as one of the most important innovations for teleosts during adaptive radiation in an aquatic environment. However, the mechanisms that create asymmetric caudal fin remain largely unknown. The spontaneous medaka (teleost fish) mutant, Double anal fin (Da), exhibits a unique symmetrical caudal skeleton that resembles the diphycercal type seen in Polypterus and Coelacanth. We performed a detailed analysis of the Da mutant to obtain molecular insight into caudal fin morphogenesis. We first demonstrate that a large transposon, inserted into the enhancer region of the zic1 and zic4 genes (zic1/zic4) in Da, is associated with the mesoderm-specific loss of their transcription. We then show that zic1/zic4 are strongly expressed in the dorsal part of the ural mesenchyme and thereby induce asymmetric caudal fin development in wild-type embryos, whereas their expression is lost in Da. Comparative analysis further indicates that the dorsal mesoderm expression of zic1/zic4 is conserved in teleosts, highlighting the crucial role of zic1/zic4 in caudal fin morphogenesis.
authors.affiliation: Department of Biological Sciences, Graduate School of Science, University of Tokyo, Tokyo, Japan.
authors.forename: Yuuta
authors.initials: Y
authors.lastname: Moriyama
authors.forename: Toru
authors.initials: T
authors.lastname: Kawanishi
authors.forename: Ryohei
authors.initials: R
authors.lastname: Nakamura
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Tsukahara
authors.forename: Kenta
authors.initials: K
authors.lastname: Sumiyama
authors.forename: Maximiliano L
authors.initials: ML
authors.lastname: Suster
authors.forename: Koichi
authors.initials: K
authors.lastname: Kawakami
authors.forename: Atsushi
authors.initials: A
authors.lastname: Toyoda
authors.forename: Asao
authors.initials: A
authors.lastname: Fujiyama
authors.forename: Yuuri
authors.initials: Y
authors.lastname: Yasuoka
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Nagao
authors.forename: Etsuko
authors.initials: E
authors.lastname: Sawatari
authors.forename: Atsushi
authors.initials: A
authors.lastname: Shimizu
authors.forename: Yuko
authors.initials: Y
authors.lastname: Wakamatsu
authors.forename: Masahiko
authors.initials: M
authors.lastname: Hibi
authors.forename: Masanori
authors.initials: M
authors.lastname: Taira
authors.forename: Masataka
authors.initials: M
authors.lastname: Okabe
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Naruse
authors.forename: Hisashi
authors.initials: H
authors.lastname: Hashimoto
authors.forename: Atsuko
authors.initials: A
authors.lastname: Shimada
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Takeda
mesh_terms: D058500:Animal Fins / Q000196:embryology* / Q000378:metabolism; D000818:Animals; D005075:Biological Evolution; D004251:DNA Transposable Elements; D029941:Fish Proteins / Q000235:genetics* / Q000378:metabolism; D008648:Mesoderm / Q000196:embryology / Q000378:metabolism; D008969:Molecular Sequence Data; D009024:Morphogenesis; D009154:Mutation; D009990:Oryzias / Q000196:embryology* / Q000235:genetics* / Q000378:metabolism; D016133:Polymerase Chain Reaction; D013623:Tail / Q000196:embryology / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D016335:Zinc Fingers
chemical_list: D004251:DNA Transposable Elements; D029941:Fish Proteins; D014157:Transcription Factors