Genes establishing dorsoventral pattern formation in the zebrafish embryo: the ventral specifying genes

Citations Over TimeTop 10% of 1996 papers

Abstract

We identified 6 genes that are essential for specifying ventral regions of the early zebrafish embryo. Mutations in these genes cause an expansion of structures normally derived from dorsal-lateral regions of the blastula at the expense of ventrally derived structures. A series of phenotypes of varied strengths is observed with different alleles of these mutants. The weakest phenotype is a reduction in the ventral tail fin, observed as a dominant phenotype of swirl, piggytail, and somitabun and a recessive phenotype of mini fin, lost-a-fin and some piggytail alleles. With increasing phenotypic strength, the blood and pronephric anlagen are also reduced or absent, while the paraxial mesoderm and anterior neuroectoderm is progressively expanded. In the strong phenotypes, displayed hy homozygous embryos of snailhouse, swirl and somitabun, the somites circle around the embryo and the midbrain region is expanded laterally. Several mutations in this group of genes are semidominant as well as recessive indicating a strong dosage sensitivity of the processes involved. Mutations in the piggytail gene display an unusual dominance that depends on both a maternal and zygotic heterozygous genotype, while somitabun is a fully penetrant dominant maternal-effect mutation. The similar and overlapping phenotypes of mutants of the 6 genes identified suggest that they function in a common pathway, which begins in oogenesis, but also depends on factors provided after the onset of zygotic transcription, presumably during blastula stages. This pathway provides ventral positional information, counteracting the dorsalizing instructions of the organizer, which is localized in the dorsal shield.

Related Papers

• → Endodermal Nodal-related signals and mesoderm induction in Xenopus(2000)416 cited
• → Establishment of the Mesoderm-Neuroectoderm Boundary in the Drosophila Embryo(1991)245 cited
• → Mesoderm formation in Xenopus ectodermal explants overexpressing Xwnt8: evidence for a cooperating signal reaching the animal pole by gastrulation(1993)44 cited
• → Distribution of Dorsal-Forming Activity in Precleavage Embryos of the Japanese Newt, Cynops pyrrhogaster: Effects of Deletion of Vegetal Cytoplasm, UV Irradiation, and Lithium Treatment(2000)16 cited
• → Neuroectoderm in Drosophila embryos is dependent on the mesoderm for positioning but not for formation.(1991)59 cited