Structure of the zebrafish <i>snail1</i> gene and its expression in wild-type, <i>spadetail</i> and <i>no tail</i> mutant embryos

TLDR

Mesoderm formation is essential for animal body plan establishment, and in Drosophila this process requires the snail gene. The study aims to clone the zebrafish snail1 gene and characterize its spatial and temporal expression pattern. The authors cloned snail1 and examined its expression by in situ hybridization across embryonic stages. In situ hybridization revealed that snail1 RNA is transiently expressed in involuting mesodermal cells at the blastoderm margin, later restricted to paraxial mesoderm, tail bud, and posterior somite borders, and persists in cephalic neural crest derivatives, with expression markedly reduced or absent in spadetail and no tail mutants, indicating a role in gastrulation, somitogenesis, and neural crest development and suggesting that the no tail gene positively regulates snail1.

Abstract

ABSTRACT Mesoderm formation is critical for the establishment of the animal body plan and in Drosophila requires the snail gene. This report concerns the cloning and expression pattern of the structurally similar gene snail1 from zebrafish. In situ hybridization shows that the quantity of snail1 RNA increases at the margin of the blastoderm in cells that involute during gastrulation. As gastrulation begins, snail1 RNA disappears from the dorsal axial mesoderm and becomes restricted to the paraxial mesoderm and the tail bud. snail1 RNA increases in cells that define the posterior border of each somite and then disappears when somitic cells differentiate. Later in development, expression appears in cephalic neural crest derivatives. Many snail1-expressing cells were missing from mutant spadetail embryos and the quantity of snail1 RNA was greatly reduced in mutant no tail embryos. The work presented here suggests that snail1 is involved in morphogenetic events during gastrulation, somitogenesis and development of the cephalic neural crest, and that no tail may act as a positive regulator of snail1.