ZFIN ID: ZDB-PUB-990107-15
Evidence for non-axial A/P patterning in the nonneural ectoderm of Xenopus and zebrafish pregastrula embryos
Read, E.M., Rodaway, A.R., Neave, B., Brandon, N., Holder, N., Patient, R.K., and Walmsley, M.E.
Date: 1998
Source: The International journal of developmental biology   42: 763-774 (Journal)
Registered Authors: Holder, Nigel, Neave, Byron, Patient, Roger K., Rodaway, Adam
Keywords: none
MeSH Terms:
  • Animals
  • Blastocyst
  • Body Patterning/genetics*
  • Bone Morphogenetic Protein 4
  • Bone Morphogenetic Protein Receptors
  • Bone Morphogenetic Proteins/physiology
  • DNA-Binding Proteins/genetics*
  • Ectoderm/physiology*
  • Embryonic Induction
  • Fibroblast Growth Factors/physiology
  • GATA2 Transcription Factor
  • GATA3 Transcription Factor
  • Gastrula
  • Gene Expression Regulation, Developmental
  • Mesoderm
  • Proteins/physiology
  • RNA/analysis
  • RNA/pharmacology
  • Receptors, Cell Surface
  • Receptors, Fibroblast Growth Factor
  • Receptors, Growth Factor*
  • Trans-Activators/genetics*
  • Transcription Factors/genetics*
  • Tretinoin/pharmacology
  • Wnt Proteins
  • Wnt3 Protein
  • Xenopus
  • Xenopus Proteins
  • Zebrafish
  • Zebrafish Proteins
PubMed: 9727832
Recent studies in early Xenopus and zebrafish embryos have demonstrated that posteriorizing, non-axial signals arising from outside the organizer (or shield) contribute to A/P patterning of the neural axis, in contradiction to the classical Spemann model in which such signals were proposed to be solely organizer derived. Our studies on the early expression of the transcription factors GATA-2 and 3 in both Xenopus and zebrafish nonneural ectoderm lend support to the existence of such non-axial signaling in the A/P axis. Thus we find that the earliest expression of GATA-2 and 3 is located in nonneural ectoderm and is strongly patterned in a graded manner along the A/P axis, being high anteriorly and absent from the most posterior regions. This results by early neurula stages in three broad zones: an anterior region which is positive for both GATA-2 and 3, a middle region which is positive for GATA-2 alone and a posterior region in which neither gene is expressed. These regions correspond to head, trunk and tail ectoderm and may represent the beginnings of functional segmentation of nonneural ectoderm, as suggested in the concept of the 'ectomere'. We find that A/P patterning of GATA expression in nonneural ectoderm may occur as early as late blastula/early gastrula stages. We investigate which posteriorizing signals might contribute to such distinct non axial ectodermal patterning in the A/P axis and provide evidence that both FGF and a Wnt family member contribute towards the final A/P pattern of GATA expression in nonneural ectoderm.