title: Induction of the Xenopus organizer: expression and regulation of Xnot, a novel FGF and activin-regulated homeo box gene.
abstract: We have searched for homeo box-containing genes expressed during gastrulation in Xenopus embryos with the expectation that analysis of the spatial and temporal expression of these genes will lead to greater understanding of the regionalization of the mesoderm. We describe the cloning and expression of Xnot, a novel homeo box-containing gene expressed primarily in the gastrula organizing region. We have studied the regulation of Xnot by signaling molecules involved in mesoderm induction and regionalization. Surprisingly, we found that FGF signaling is required for expression of Xnot in the gastrula organizing region, clearly implicating FGF in the induction of dorsal mesoderm. Furthermore, we found that Xnot is initially expressed throughout the embryo and that progressive translation of an unknown protein restricts expression of Xnot to the organizing region. Our results provide experimental evidence supporting the proposed division of Spemann's organizer into independently regulated organizing centers.
authors.affiliation: Department of Biochemistry, University of Washington, Seattle 98195.
authors.forename: G
authors.initials: G
authors.lastname: von Dassow
authors.forename: J E
authors.initials: JE
authors.lastname: Schmidt
authors.forename: D
authors.initials: D
authors.lastname: Kimelman
mesh_terms: D028341:Activins; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004625:Embryo, Nonmammalian / Q000502:physiology; D005314:Embryonic and Fetal Development; D005346:Fibroblast Growth Factors / Q000502:physiology*; D005775:Gastrula / Q000502:physiology; D005786:Gene Expression Regulation; D005801:Genes, Homeobox; D006133:Growth Substances / Q000502:physiology*; D018398:Homeodomain Proteins; D007265:Inhibins / Q000502:physiology*; D008648:Mesoderm / Q000502:physiology; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides; D016366:Open Reading Frames; D016133:Polymerase Chain Reaction; D017433:Protein Structure, Secondary; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D015534:Trans-Activators / Q000737:chemistry / Q000235:genetics*; D014158:Transcription, Genetic; D014981:Xenopus / Q000196:embryology*; D029867:Xenopus Proteins
chemical_list: D006133:Growth Substances; D018398:Homeodomain Proteins; C080209:Not protein, Xenopus; D009838:Oligodeoxyribonucleotides; D012333:RNA, Messenger; D015534:Trans-Activators; D029867:Xenopus Proteins; D028341:Activins; D007265:Inhibins; D005346:Fibroblast Growth Factors