Genetic dissection of the formation of the forebrain in Medaka, Oryzias latipes.
The forebrain, consisting of the telencephalon and diencephalon, is essential for processing sensory information. To genetically dissect formation of the forebrain in vertebrates, we carried out a systematic screen for mutations affecting morphogenesis of the forebrain in Medaka. Thirty-three mutations defining 25 genes affecting the morphological development of the forebrain were grouped into two classes. Class 1 mutants commonly showing a decrease in forebrain size, were further divided into subclasses 1A to 1D. Class 1A mutation (1 gene) caused an early defect evidenced by the lack of bf1 expression, Class 1B mutations (6 genes) patterning defects revealed by the aberrant expression of regional marker genes, Class 1C mutation (1 gene) a defect in a later stage, and Class 1D (3 genes) a midline defect analogous to the zebrafish one-eyed pinhead mutation. Class 2 mutations caused morphological abnormalities in the forebrain without considerably affecting its size, Class 2A mutations (6 genes) caused abnormalities in the development of the ventricle, Class 2B mutations (2 genes) severely affected the anterior commissure, and Class 2C (6 genes) mutations resulted in a unique forebrain morphology. Many of these mutants showed the compromised sonic hedgehog expression in the zona-limitans-intrathalamica (zli), arguing for the importance of this structure as a secondary signaling center. These mutants should provide important clues to the elucidation of the molecular mechanisms underlying forebrain development, and shed new light on phylogenically conserved and divergent functions in the developmental process.
Kitagawa
Daiju
D
Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan.
Watanabe
Tomomi
T
Saito
Kota
K
Asaka
Satoshi
S
Sasado
Takao
T
Morinaga
Chikako
C
Suwa
Hiroshi
H
Niwa
Katsutoshi
K
Yasuoka
Akihito
A
Deguchi
Tomonori
T
Yoda
Hiroki
H
Hirose
Yukihiro
Y
Henrich
Thorsten
T
Iwanami
Norimasa
N
Kunimatsu
Sanae
S
Osakada
Masakazu
M
Winkler
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Elmasri
Harun
H
Wittbrodt
Joachim
J
Loosli
Felix
F
Quiring
Rebecca
R
Carl
Matthias
M
Grabher
Clemens
C
Winkler
Sylke
S
Del Bene
Filippo
F
Momoi
Akihiro
A
Katada
Toshiaki
T
Nishina
Hiroshi
H
Kondoh
Hisato
H
Furutani-Seiki
Makoto
M
D000818:Animals; D009154:Mutation; D009990:Oryzias / Q000196:embryology* / Q000235:genetics*; D010641:Phenotype; D016548:Prosencephalon / Q000002:abnormalities / Q000196:embryology*