title: An anterior limit of FGF/Erk signal activity marks the earliest future somite boundary in zebrafish.
abstract: Vertebrate segments called somites are generated by periodic segmentation of the anterior extremity of the presomitic mesoderm (PSM). During somite segmentation in zebrafish, mesp-b determines a future somite boundary at position B-2 within the PSM. Heat-shock experiments, however, suggest that an earlier future somite boundary exists at B-5, but the molecular signature of this boundary remains unidentified. Here, we characterized fibroblast growth factor (FGF) signal activity within the PSM, and demonstrated that an anterior limit of downstream Erk activity corresponds to the future B-5 somite boundary. Moreover, the segmentation clock is required for a stepwise posterior shift of the Erk activity boundary during each segmentation. Our results provide the first molecular evidence of the future somite boundary at B-5, and we propose that clock-dependent cyclic inhibition of the FGF/Erk signal is a key mechanism in the generation of perfect repetitive structures in zebrafish development.
authors: Gene Regulation Research, Nara Institute Science and Technology, 8916-5 Takayama, Nara 630-0101, Japan.
authors: Ryutaro
authors: R
authors: Akiyama
authors: Miwa
authors: M
authors: Masuda
authors: Shoichiro
authors: S
authors: Tsuge
authors: Yasumasa
authors: Y
authors: Bessho
authors: Takaaki
authors: T
authors: Matsui
mesh_terms: D000818:Animals; D019521:Body Patterning / Q000235:genetics / Q000502:physiology; D005346:Fibroblast Growth Factors / Q000235:genetics / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental / Q000235:genetics / Q000502:physiology; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology; D019170:Somites / Q000166:cytology / Q000378:metabolism*; D015027:Zebrafish; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D029961:Zebrafish Proteins; D005346:Fibroblast Growth Factors
keywords: Clock; FGF signalling; Segmentation; Somitogenesis