zic gene expression marks anteroposterior pattern in the presumptive neurectoderm of the zebrafish gastrula

Anteroposterior (A/P) patterning of the vertebrate neurectoderm. begins early during development. In vitro explant assays have been used to show that an A/P subdivision of the zebrafish neurectoderm. is in place by early gastrulation. However, no direct markers of this subdivision had been described. We report, isolation of two members of the zic gene family, zic2 and zic3, which mark distinct regions in the developing nervous system. zic3 is expressed in early gastrula embryos in a posterior domain, directly demonstrating that All? pattern is present in the future neurectoderm. by this stage. Analysis of mutants in genes encoding bone morphogenetic proteins (BMPs) shows that dorsal restriction of zic3 expression requires intact BMP function, and that posterior restriction of zic3 expression is regulated independently of BMP signaling. These data show an early subdivision of the A/P axis in the presumptive neurectoderm. (C) 2001 Wiley-Liss, Inc.