title: Systematic screening for genes specifically expressed in the anterior neuroectoderm during early Xenopus development.
abstract: A cDNA library derived from the anterior neuroectoderm (ANE) of Xenopus late-gastrula embryos was systematically screened to isolate novel developmental regulatory genes involved in early brain development. We isolated 1,706 5 expressed sequence tags (ESTs), which were subdivided into 1,383 clusters and categorized into 19 classes based on predicted functions according to their similarities to other known genes. Of these, 757 clusters that were considered possible novel regulatory genes or unknown genes were subjected to expression pattern analysis using whole-mount in situ hybridization. Genes from 69 clusters (9%) were expressed in the ANE region. Based on their expression patterns and predicted amino acid sequences, 25 genes were selected for further analysis as novel Xenopus genes expressed broadly or region-specifically in the ANE. Eighteen genes were expressed in postulated patterning centers in the neuroectoderm, including the anterior (four genes) and lateral (nine genes) neural ridges, the midbrain-hindbrain boundary region (one gene) and the midline region of the neural plate (two genes), whereas 13 genes were expressed in the eye anlagen. Therefore, early regionalization of the neuroectoderm appears to occur mainly in those neural patterning centers and the eye anlagen. We determined the entire coding regions of p54nrb, Semaphorin 6D and a novel gene designated scribble-related protein 1 (SCRP1). Interestingly, Semaphorin 6D is expressed in the mesoderm with a dorsoventral gradient, as well as in the ectoderm at the gastrula stage, implying a new role for this protein in development other than in axon guidance.
authors.affiliation: Department of Biological Sciences, Graduate School of Science, University of Tokyo, Japan.
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Takahashi
authors.forename: Naoko
authors.initials: N
authors.lastname: Tochimoto
authors.forename: Shin-Ya
authors.initials: SY
authors.lastname: Ohmori
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Mamada
authors.forename: Mari
authors.initials: M
authors.lastname: Itoh
authors.forename: Masako
authors.initials: M
authors.lastname: Inamori
authors.forename: Jun
authors.initials: J
authors.lastname: Shinga
authors.forename: Shin-Ichi
authors.initials: S
authors.lastname: Osada
authors.forename: Masanori
authors.initials: M
authors.lastname: Taira
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D018076:DNA, Complementary / Q000302:isolation & purification; D004475:Ectoderm / Q000502:physiology*; D004625:Embryo, Nonmammalian / Q000502:physiology; D020224:Expressed Sequence Tags; D020869:Gene Expression Profiling; D015723:Gene Library; D008969:Molecular Sequence Data; D009420:Nervous System / Q000196:embryology*; D039961:Semaphorins / Q000096:biosynthesis / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid; D014982:Xenopus laevis
chemical_list: D018076:DNA, Complementary; D039961:Semaphorins