ZFIN ID: ZDB-PUB-031009-2
The maternally expressed zebrafish T-box gene eomesodermin regulates organizer formation
Bruce, A.E., Howley, C., Zhou, Y., Vickers, S.L., Silver, L.M., King, M.L., and Ho, R.K.
Date: 2003
Source: Development (Cambridge, England) 130(22): 5503-5517 (Journal)
Registered Authors: Bruce, Ashley, Ho, Robert K., Howley, Cristin, Vickers, Sarah, Zhou, Yi
Keywords: none
MeSH Terms: Animals; Cell Nucleus/metabolism; Nodal Protein; Nodal Signaling Ligands; Organizers, Embryonic/metabolism* (all 15) expand
PubMed: 14530296 Full text @ Development
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.
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