The zebrafish organizer requires chordino

Abstract

[Introduction] The dorsoventral pattern of vertebrate embryos is established and regulated by opposing gradients of ventralizing bone morphogenetic proteins (BMPs) and BMP antagonists^1,2,3 (such as Chordin²,⁴, Noggin⁵,⁶ and Follistatin⁷,⁸ in the frog embryo) secreted by a dorsal organizer. In the zebrafish, Danio rerio, mutations in a number of genes that affect dorsoventral patterning of the early embryo have been identified⁹,¹⁰, but only two, dino and mercedes, are involved in dorsal specification¹¹, with dino mutants displaying the stronger, ventralized phenotype. Here we show that the dino phenotype is caused by a mutation in the zebrafish chordin gene, revealing that Chordin is an essential component of the dorsal organizer. Furthermore, we provide evidence that Chordin and BMPs are antagonistic, not only at the protein level but also at the transcriptional level.

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