title: Reiterative expression of pax1 directs pharyngeal pouch segmentation in medaka.
abstract: A striking characteristic of vertebrate development is the pharyngeal arches, which are a series of bulges on the lateral surface of the head of vertebrate embryos. Although each pharyngeal arch is segmented by the reiterative formation of endodermal outpocketings called pharyngeal pouches, the molecular network underlying the reiterative pattern remains unclear. Here, we show that pax1 plays crucial roles in pouch segmentation in medaka (Oryzias latipes) embryos. Importantly, pax1 expression in the endoderm prefigures the location of the next pouch before the cells bud from the epithelium. TALEN-generated pax1 mutants did not form pharyngeal pouches posterior to the second arch. Segmental expression of tbx1 and fgf3, which play essential roles in pouch development, was almost non-existent in the pharyngeal endoderm of pax1 mutants, with disturbance of the reiterative pattern of pax1 expression. These results suggest that pax1 plays a key role in generating the primary pattern for segmentation in the pharyngeal endoderm by regulating tbx1 and fgf3 expression. Our findings illustrate the crucial roles of pax1 in vertebrate pharyngeal segmentation and provide insights into the evolutionary origin of the deuterostome gill slit.
authors.affiliation: Graduate School of Life and Environmental Sciences, University of Tsukuba, 111 Tennoudai, Tsukuba 305-8572, Japan Okazaki Institute for Integrative Bioscience and National Institute for Basic Biology, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji-cho, Okazaki 444-8787, Japan tobiuo126@gmail.com stakada@nibb.ac.jp hwada@biol.tsukuba.ac.jp.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Okada
authors.affiliation: Department of Biological Information, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8501, Japan.
authors.forename: Keiji
authors.initials: K
authors.lastname: Inohaya
authors.affiliation: Graduate School of Life and Environmental Sciences, University of Tsukuba, 111 Tennoudai, Tsukuba 305-8572, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Mise
authors.affiliation: Department of Biological Information, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8501, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Kudo
authors.affiliation: Okazaki Institute for Integrative Bioscience and National Institute for Basic Biology, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji-cho, Okazaki 444-8787, Japan Department for Basic Biology, SOKENDAI (The Graduate University for Advanced Studies), 5-1 Higashiyama, Myodaiji-cho, Okazaki 444-8787, Japan tobiuo126@gmail.com stakada@nibb.ac.jp hwada@biol.tsukuba.ac.jp.
authors.forename: Shinji
authors.initials: S
authors.lastname: Takada
authors.affiliation: Graduate School of Life and Environmental Sciences, University of Tsukuba, 111 Tennoudai, Tsukuba 305-8572, Japan tobiuo126@gmail.com stakada@nibb.ac.jp hwada@biol.tsukuba.ac.jp.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Wada
mesh_terms: D000818:Animals; D019521:Body Patterning; D001934:Branchial Region / Q000196:embryology* / Q000378:metabolism*; D002356:Cartilage / Q000378:metabolism; D003391:Cranial Nerves / Q000378:metabolism; D004625:Embryo, Nonmammalian; D004707:Endoderm / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D053263:Gene Regulatory Networks; D005880:Gills / Q000378:metabolism; D008954:Models, Biological; D009154:Mutation / Q000235:genetics; D009990:Oryzias / Q000196:embryology* / Q000378:metabolism*; D051761:Paired Box Transcription Factors / Q000235:genetics / Q000378:metabolism*; D013950:Thymus Gland / Q000196:embryology
chemical_list: D051761:Paired Box Transcription Factors; C070835:PAX1 transcription factor
keywords: Evolution; Gill slit; Pax1; Pharyngeal arch; Pharyngeal pouch; Segmentation