Mutations affecting somite formation in the Medaka (Oryzias latipes).
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.
Elmasri
Harun
H
Department of Physiological Chemistry I, Biocenter, University of Wuerzburg, Am Hubland, D-97074 Wuerzburg, Germany.
Winkler
Christoph
C
Liedtke
Daniel
D
Sasado
Takao
T
Morinaga
Chikako
C
Suwa
Hiroshi
H
Niwa
Katsutoshi
K
Henrich
Thorsten
T
Hirose
Yukihiro
Y
Yasuoka
Akihito
A
Yoda
Hiroki
H
Watanabe
Tomomi
T
Deguchi
Tomonori
T
Iwanami
Norihisa
N
Kunimatsu
Sanae
S
Osakada
Masakazu
M
Loosli
Felix
F
Quiring
Rebecca
R
Carl
Matthias
M
Grabher
Clemens
C
Winkler
Sylke
S
Del Bene
Filippo
F
Wittbrodt
Joachim
J
Abe
Keiko
K
Takahama
Yousuke
Y
Takahashi
Katsuhito
K
Katada
Toshiaki
T
Nishina
Hiroshi
H
Kondoh
Hisato
H
Furutani-Seiki
Makoto
M
D000818:Animals; D019521:Body Patterning / Q000235:genetics; D009154:Mutation; D009990:Oryzias / Q000196:embryology* / Q000235:genetics*; D019170:Somites