title: Mutations affecting somite formation in the Medaka (Oryzias latipes).
abstract: The metameric structure of the vertebrate trunk is generated by repeated formation of somites from the unsegmented presomitic mesoderm (PSM). We report the initial characterization of nine different mutants affecting segmentation that were isolated in a large-scale mutagenesis screen in Medaka (Oryzias latipes). Four mutants were identified that show a complete or partial absence of somites or somite boundaries. In addition, five mutations were found that cause fused somites or somites with irregular sizes and shapes. In situ hybridization analysis using specific markers involved in the segmentation clock and antero-posterior (A-P) polarity of somites revealed that the nine mutants can be compiled into two groups. In group 1, mutants exhibit defects in tailbud formation and PSM prepatterning, whereas A-P identity in the somites is defective in group 2 mutants. Three mutants (planlos, pll; schnelles ende, sne; samidare, sam) have characteristic phenotypes that are similar to those in zebrafish mutants affected in the Delta/Notch signaling pathway. The majority of mutants, however, exhibit somitic phenotypes distinct from those found in zebrafish, such as individually fused somites and irregular somite sizes. Thus, these Medaka mutants can be expected to provide clues to uncovering novel components essential for somitogenesis.
authors.affiliation: Department of Physiological Chemistry I, Biocenter, University of Wuerzburg, Am Hubland, D-97074 Wuerzburg, Germany.
authors.forename: Harun
authors.initials: H
authors.lastname: Elmasri
authors.forename: Christoph
authors.initials: C
authors.lastname: Winkler
authors.forename: Daniel
authors.initials: D
authors.lastname: Liedtke
authors.forename: Takao
authors.initials: T
authors.lastname: Sasado
authors.forename: Chikako
authors.initials: C
authors.lastname: Morinaga
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Suwa
authors.forename: Katsutoshi
authors.initials: K
authors.lastname: Niwa
authors.forename: Thorsten
authors.initials: T
authors.lastname: Henrich
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Hirose
authors.forename: Akihito
authors.initials: A
authors.lastname: Yasuoka
authors.forename: Hiroki
authors.initials: H
authors.lastname: Yoda
authors.forename: Tomomi
authors.initials: T
authors.lastname: Watanabe
authors.forename: Tomonori
authors.initials: T
authors.lastname: Deguchi
authors.forename: Norihisa
authors.initials: N
authors.lastname: Iwanami
authors.forename: Sanae
authors.initials: S
authors.lastname: Kunimatsu
authors.forename: Masakazu
authors.initials: M
authors.lastname: Osakada
authors.forename: Felix
authors.initials: F
authors.lastname: Loosli
authors.forename: Rebecca
authors.initials: R
authors.lastname: Quiring
authors.forename: Matthias
authors.initials: M
authors.lastname: Carl
authors.forename: Clemens
authors.initials: C
authors.lastname: Grabher
authors.forename: Sylke
authors.initials: S
authors.lastname: Winkler
authors.forename: Filippo
authors.initials: F
authors.lastname: Del Bene
authors.forename: Joachim
authors.initials: J
authors.lastname: Wittbrodt
authors.forename: Keiko
authors.initials: K
authors.lastname: Abe
authors.forename: Yousuke
authors.initials: Y
authors.lastname: Takahama
authors.forename: Katsuhito
authors.initials: K
authors.lastname: Takahashi
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Katada
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nishina
authors.forename: Hisato
authors.initials: H
authors.lastname: Kondoh
authors.forename: Makoto
authors.initials: M
authors.lastname: Furutani-Seiki
mesh_terms: D000818:Animals; D019521:Body Patterning / Q000235:genetics; D009154:Mutation; D009990:Oryzias / Q000196:embryology* / Q000235:genetics*; D019170:Somites