PUBLICATION

Delta-mediated specification of midline cell fates in zebrafish embryos

Authors
Appel, B., Fritz, A., Westerfield, M., Grunwald, D.J., Eisen, J.S., and Riley, B.B.
ID
ZDB-PUB-990302-45
Date
1999
Source
Current biology : CB   9: 247-256 (Journal)
Registered Authors
Appel, Bruce, Eisen, Judith S., Fritz, Andreas, Grunwald, David, Riley, Bruce, Westerfield, Monte
Keywords
none
MeSH Terms
  • Animals
  • Cell Differentiation
  • Gastrula
  • Gene Expression
  • Intracellular Signaling Peptides and Proteins
  • Membrane Proteins/biosynthesis*
  • Membrane Proteins/genetics
  • Mutation
  • Notochord
  • Zebrafish/embryology*
PubMed
10074451 Full text @ Curr. Biol.
Abstract
BACKGROUND: Fate mapping studies have shown that progenitor cells of three vertebrate embryonic midline structures - the floorplate in the ventral neural tube, the notochord and the dorsal endoderm - occupy a common region prior to gastrulation. This common region of origin raises the possibility that interactions between midline progenitor cells are important for their specification prior to germ layer formation. RESULTS: One of four known zebrafish homologues of the Drosophila melanogaster cell-cell signaling gene Delta, deltaA (dlA), is expressed in the developing midline, where progenitor cells of the ectodermal floorplate, mesodermal notochord and dorsal endoderm lie close together before they occupy different germ layers. We used a reverse genetic strategy to isolate a missense mutation of dlA, dlAdx2, which coordinately disrupts the development of floorplate, notochord and dorsal endoderm. The dlAdx2 mutant embryos had reduced numbers of floorplate and hypochord cells; these cells lie above and beneath the notochord, respectively. In addition, mutant embryos had excess notochord cells. Expression of a dominant-negative form of Delta protein driven by mRNA microinjection produced a similar effect. In contrast, overexpression of dlA had the opposite effect: fewer trunk notochord cells and excess floorplate and hypochord cells. CONCLUSION: Our results indicate that Delta signaling is important for the specification of midline cells. The results are most consistent with the hypothesis that developmentally equivalent midline progenitor cells require Delta-mediated signaling prior to germ layer formation in order to be specified as floorplate, notochord or hypochord.
Genes / Markers
Figures
Expression
Phenotype
Mutation and Transgenics
Human Disease / Model Data
Sequence Targeting Reagents
Fish
Antibodies
Orthology
Engineered Foreign Genes
Mapping
Errata and Notes