title: The Xenopus XIHbox 6 homeo protein, a marker of posterior neural induction, is expressed in proliferating neurons.
abstract: XIHbox 6 is an early spatially restricted marker for molecular studies of neural induction. The sequence of the full-length XIHbox 6 protein is reported. An antibody raised against a beta-galactosidase/XIHbox 6 fusion protein was used to analyze the expression of XIHbox 6 proteins during frog embryogenesis. The anterior border of XIHbox 6 expression lies just posterior of the hindbrain/spinal cord junction. Immunostaining extends the entire length of the spinal cord. A much weaker transient expression with a similar anterior border is observed in mesoderm. Almost all nuclei in the newly closed spinal cord contain XIHbox 6. The number of positive nuclei decreases over the next stages of development, until in later embryos XIHbox 6 is restricted to nuclei of the dividing neuroepithelium, and not the mantle or marginal zones of the spinal cord. When the limb buds begin to grow, there is a second burst of XIHbox 6 expression in proliferating neurons of the cervical and lumbar enlargements, where nerves arise that supply the limbs. The data suggest that XIHbox 6 expression is spatially and temporally restricted to immature neurons of the spinal cord, before their differentiation into mature neurons.
authors.affiliation: Department of Biological Chemistry, University of California School of Medicine, Los Angeles 90024-1737.
authors.forename: C V
authors.initials: CV
authors.lastname: Wright
authors.forename: E A
authors.initials: EA
authors.lastname: Morita
authors.forename: D J
authors.initials: DJ
authors.lastname: Wilkin
authors.forename: E M
authors.initials: EM
authors.lastname: De Robertis
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002455:Cell Division; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000276:immunology; D015870:Gene Expression; D005801:Genes, Homeobox; D007150:Immunohistochemistry; D008648:Mesoderm / Q000378:metabolism; D008969:Molecular Sequence Data; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D012689:Sequence Homology, Nucleic Acid; D013116:Spinal Cord / Q000196:embryology / Q000378:metabolism; D014982:Xenopus laevis / Q000196:embryology / Q000235:genetics*
chemical_list: D004268:DNA-Binding Proteins; C066011:HOXA9 protein, Xenopus