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Phenotypic analyses of a medaka mutant reveal the importance of bilaterally synchronized expression of isthmic fgf8 for bilaterally symmetric formation of the optic tectum
Author(s) -
Takashima Shigeo,
Kage Takahiro,
Yasuda Takako,
Inohaya Keiji,
Maruyama Kouichi,
Araki Kazuo,
Takeda Hiroyuki,
Ishikawa Yuji
Publication year - 2008
Publication title -
genesis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.093
H-Index - 110
eISSN - 1526-968X
pISSN - 1526-954X
DOI - 10.1002/dvg.20424
Subject(s) - fgf8 , neural tube , biology , oryzias , phenotype , embryo , tectum , anatomy , mutant , optic tectum , asymmetry , neuroscience , microbiology and biotechnology , genetics , central nervous system , midbrain , gene , physics , receptor , fibroblast growth factor , quantum mechanics
Developing neural tubes are bilaterally symmetric in all vertebrate embryos, irrespective of the presence of gene networks that generate left‐right asymmetry. To explore the mechanisms that underlie the bilaterally symmetric formation of the neural tube, we examined a medaka ( Oryzias latipes ) dominant mutant, Oot , the neural tube of which transiently lacks normal symmetry in the optic tectum. We found that spatial changes in isthmic fgf8 expression do not occur on one side of the mutant, resulting in a transient desynchronized expression that correlates with tectal asymmetry. The application of exogenous FGF8 on one side of a wild‐type embryo mimics the Oot phenotype, indicating that the bilaterally equivalent expression of isthmic fgf8 is crucial for the bilaterally symmetric development of the tectum. These results suggest that tectal symmetry is not a “default” state, but rather is maintained actively by a bilaterally coupled and synchronized regulation of isthmic fgf8 expression. genesis 46:537–545, 2008. © 2008 Wiley‐Liss, Inc.