title: Dorsal-ventral patterning and differentiation of noggin-induced neural tissue in the absence of mesoderm.
abstract: In Xenopus development, dorsal mesoderm is thought to play a key role in both induction and patterning of the nervous system. Previously, we identified a secreted factor, noggin, which is expressed in dorsal mesoderm and which can mimic that tissue's neural-inducing activity, without inducing mesoderm. Here the neural tissue induced in ectodermal explants by noggin is further characterized using four neural-specific genes: two putative RNA-binding proteins, nrp-1 and etr-1; the synaptobrevin sybII; and the lipocalin cpl-1. First we determine the expression domain of each gene during embryogenesis. Then we analyze expression of these genes in noggin-treated explants. All markers, including the differentiated marker sybII, are expressed in noggin-induced neural tissue. Furthermore, cpl-1, a marker of dorsal brain, and etr-1, a marker absent in much of the dorsal forebrain, are expressed in non-overlapping territories within these explants. We conclude that the despite the absence of mesoderm, noggin-induced neural tissue shows considerable differentiation and organization, which may represent dorsal-ventral patterning of the forebrain.
authors.affiliation: Department of Molecular and Cell Biology, University of California at Berkeley 94720, USA.
authors.forename: A K
authors.initials: AK
authors.lastname: Knecht
authors.forename: P J
authors.initials: PJ
authors.lastname: Good
authors.forename: I B
authors.initials: IB
authors.lastname: Dawid
authors.forename: R M
authors.initials: RM
authors.lastname: Harland
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins; D051959:ELAV Proteins; D004475:Ectoderm / Q000502:physiology*; D004627:Embryonic Induction; D015870:Gene Expression; D005796:Genes; D005819:Genetic Markers; D008565:Membrane Proteins / Q000235:genetics; D008969:Molecular Sequence Data; D009024:Morphogenesis / Q000235:genetics; D009419:Nerve Tissue Proteins / Q000235:genetics; D009420:Nervous System / Q000196:embryology*; D011506:Proteins / Q000235:genetics / Q000502:physiology*; D050683:R-SNARE Proteins; D016601:RNA-Binding Proteins / Q000235:genetics; D012261:Ribonucleoproteins / Q000235:genetics; D014981:Xenopus / Q000196:embryology* / Q000235:genetics; D029867:Xenopus Proteins; D000099176:Noggin Protein
chemical_list: D002352:Carrier Proteins; D051959:ELAV Proteins; D005819:Genetic Markers; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D011506:Proteins; D050683:R-SNARE Proteins; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins; D029867:Xenopus Proteins; D000099176:Noggin Protein; C094526:CELF3 protein, Xenopus; C068598:Msi1 protein, Xenopus