Abstract
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 language | English (US) |
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Pages (from-to) | 5503-5517 |
Number of pages | 15 |
Journal | Development |
Volume | 130 |
Issue number | 22 |
DOIs | |
State | Published - Nov 2003 |
Keywords
- Bozozok
- Chordin
- Eomesodermin
- Floating head
- Goosecoid
- Maternal
- Nieuwkoid/dharma
- Nodal
- Squint
- T-box
- VegT
- Zebrafish
ASJC Scopus subject areas
- Anatomy
- Cell Biology