The maternally expressed zebrafish T-box gene eomesodermin regulates organizer formation

Ashley E.E. Bruce, Cristin Howley, Yi Zhou, Sarah L. Vickers, Lee M. Silver, Mary Lou King, Robert K. Ho

Research output: Contribution to journalArticlepeer-review

55 Scopus citations


Early embryonic development in many organisms relies upon maternal molecules deposited into the egg prior to fertilization. We have cloned and characterized a maternal T-box gene in the zebrafish, eomesodermin (eomes). During oogenesis, the eomes transcript becomes localized to the cortex of the oocyte. After fertilization during early cleavage stages, eomes is expressed in a vegetal to animal gradient in the embryo, whereas Eomesodermin protein (Eom) is distributed cytoplasmically throughout the blastoderm. Strikingly, following midblastula transition, nuclear-localized Eomesodermin is detected on the dorsal side of the embryo only. Overexpression of eomes results in Nodal-dependent and nieuwkoid/dharma (nwk/dhm) independent ectopic expression of the organizer markers goosecoid (gsc), chordin (chd) and floating head (flh) and in the formation of secondary axes. The same phenotypes are observed when a VP16-activator construct is injected into early embryos, indicating that eomes acts as a transcriptional activator. In addition, a dominant-negative construct and antisense morpholino oligonucleotides led to a reduction in gsc and flh expression. Together these data indicate that eomes plays a role in specifying the organizer.

Original languageEnglish (US)
Pages (from-to)5503-5517
Number of pages15
Issue number22
StatePublished - Nov 2003
Externally publishedYes


  • Bozozok
  • Chordin
  • Eomesodermin
  • Floating head
  • Goosecoid
  • Maternal
  • Nieuwkoid/dharma
  • Nodal
  • Squint
  • T-box
  • VegT
  • Zebrafish

ASJC Scopus subject areas

  • Anatomy
  • Cell Biology


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