title: Regional specification of the head and trunk-tail organizers of a urodele (Cynops pyrrhogaster) embryo is patterned during gastrulation.
abstract: The dorsal marginal zone (DMZ) of an amphibian early gastrula is thought to consist of at least two distinct domains: the future head and trunk-tail organizers. We studied the mechanism by which the organizing activities of the lower half of the DMZ (LDMZ) of the urodelean (Cynops pyrrhogaster) embryo are changed. The uninvoluted LDMZ induces the notochord and then organizes the trunk-tail structures, whereas after cultivation in vitro or suramin treatment, the same LDMZ loses the notochord-inducing ability and organizes the head structures. A cell-lineage experiment indicated that the change in the organizing activity of the LDMZ was reflected in the transformation of the inductive ability: from notochord-inducing to neural-inducing activity. Using RT-PCR, we showed that the LDMZ expressed gsc, lim-1, chordin, and noggin, but not the mesoderm marker bra. In the sandwich assay, the LDMZ induced bra expression in the animal cap ectoderm, but the inductive activity was inhibited by cultivation or suramin treatment. The present study indicates that the change in the organizing activity of the LDMZ from trunk-tail to head is coupled with the loss of notochord-inducing activity. Based on these results, we suggest that this change is essential for the specification of the head and trunk-tail organizers during gastrulation.
authors.affiliation: Department of Bioengineering, Advanced Course for Bioengineering, Yatsushiro National College of Technology, 2627 Hirayama Shin-Machi, Yatsushiro, 866-8501, Japan. kaneda@as.yatsushiro-nct.ac.jp
authors.forename: Teruo
authors.initials: T
authors.lastname: Kaneda
authors.forename: Keiko
authors.initials: K
authors.lastname: Miyazaki
authors.forename: Risa
authors.initials: R
authors.lastname: Kudo
authors.forename: Kazutoshi
authors.initials: K
authors.lastname: Goto
authors.forename: Koji
authors.initials: K
authors.lastname: Sakaguchi
authors.forename: Miwako
authors.initials: M
authors.lastname: Matsumoto
authors.forename: Syouen
authors.initials: S
authors.lastname: Todaka
authors.forename: Keisuke
authors.initials: K
authors.lastname: Yoshinaga
authors.forename: Akio S
authors.initials: AS
authors.lastname: Suzuki
mesh_terms: D000818:Animals; D019521:Body Patterning / Q000187:drug effects / Q000502:physiology*; D002454:Cell Differentiation; D004475:Ectoderm / Q000187:drug effects / Q000502:physiology; D004625:Embryo, Nonmammalian / Q000502:physiology*; D005775:Gastrula / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D006257:Head / Q000196:embryology; D008954:Models, Biological; D009024:Morphogenesis / Q000187:drug effects / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013498:Suramin / Q000494:pharmacology; D013623:Tail / Q000196:embryology; D014562:Caudata / Q000196:embryology*
chemical_list: D013498:Suramin