... an early mesendodermal inducer signaling from the extraembryonic yolk syncytial layer. Dev. Biol. 204 , 361 -372. Fekany, K., Yamanaka, Y., Leung, T., Sirotkin, H. I.,Topczewski, J., Gates, M. A., Hibi, M., Renucci, A., Stemple, D.,Radbill, A. et al. (1999). The zebrafish bozozok locus encodes...

... that activate the expression of Bmps. How the balance between dorsalizing and ventralizing factors is shifted towards organizer establishment at late blastula stages is not well understood. Mutations in zebrafish bozozok (boz) cause severe defects in axial mesoderm and anterior neurectoderm and affect organizer...

... in bozozok mutants, in which inactivation of a homeobox gene causes ectopic wnt8 expression. In addition, the bozozok forebrain reduction is suppressed in bozozok;squint;cyclops triple mutants, and is associated with reduced wnt8 expression, as seen in cyclops;squint mutants. Hence, whereas boz and Nodal...

... oligonucleotides has little or no effect on the embryo. In contrast, embryos that lack both vox and vent function have a dorsalized phenotype. Expression of dorsal mesodermal genes, including chordin , goosecoid and bozozok , is strongly expanded in embryos that lack vox and vent function, indicating...

... encoding the nodal-related factor, Squint, and homeodomain protein, Bozozok, both of which are expressed in the YSL, suggested that the YSL has a role in mesendoderm induction. However, these genes, and a second nodal -related factor, cyclops , are also expressed in the overlying marginal blastomeres...

... of dorsal axial structures are the homeobox gene bozozok (boz) and the nodal-related (TGF-P family) gene squint (sqt) . Both genes are expressed in the dorsal yolk syncytial layer, a source of dorsal mesoderm inducing signals, and mutational analysis has indicated that boz and sqt are required for dorsal...

... a properly patterned head, and how they are regulated in vivo, is not understood. Here we demonstrate that the loss of anterior neural fates observed in zebrafish bozozok (boz) mutants occurs during gastrulation due to a reduction and subsequent posteriorization of neuroectoderm. The neural induction defect...

... a fundamental role in establishment of the vertebrate axis. We demonstrate that the zebrafish bozozok (boz) locus is required at the blastula stages for formation of the embryonic shield, the equivalent of the gastrula organizer and expression of multiple organizer-specific genes. Furthermore, boz is essential...