Hammerschmidt M, Nüsslein-Volhard C
Max-Planck-Institut für Entwicklungsbiologie, Abteilung Genetik, Tübingen, Germany.
Development. 1993 Dec;119(4):1107-18. doi: 10.1242/dev.119.4.1107.
Snail, a zinc finger protein, is required for the formation of the ventral furrow and the mesoderm during gastrulation of the Drosophila embryo. snail homologues have been cloned from Xenopus and mouse. We have isolated a zebrafish homologue of snail, designated sna-1. Like its Drosophila counterpart, Sna-1 protein is nuclear. Maternal and zygotic sna-1 transcripts are ubiquitously distributed in zebrafish embryos of cleavage and blastula stages. In gastrulating embryos, sna-1 is expressed in involuting cells of the germ ring, but not in those at the dorsal midline, the presumptive notochordal region. After involution, the expression is maintained in the paraxial mesoderm and becomes prominent in the muscle pioneer precursors, followed by expression at the posterior somite boundaries. Later, sna-1 is expressed in neural crest and mesodermal derivatives of the head region. Sna-1 expression is induced in animal cap cells by activin A. The early sna-1 expression pattern in gastrulating zebrafish no tail (ntl) mutant embryos is normal except a reduction in the level of sna-1 transcription, suggesting that Ntl protein is not the key activator of sna-1 transcription in vivo, but might be involved in the enhancement or maintenance of sna-1 transcription. Data obtained in studies with ectopic ntl expression support this model.
蜗牛蛋白是一种锌指蛋白，在果蝇胚胎原肠胚形成过程中，对于腹沟和中胚层的形成是必需的。已经从非洲爪蟾和小鼠中克隆出了蜗牛蛋白的同源物。我们分离出了斑马鱼的蜗牛蛋白同源物，命名为sna-1。与果蝇中的对应物一样，Sna-1蛋白定位于细胞核。母源和合子源的sna-1转录本在卵裂期和囊胚期的斑马鱼胚胎中广泛分布。在原肠胚形成期的胚胎中，sna-1在胚环内卷细胞中表达，但不在背中线（假定的脊索区域）的细胞中表达。内卷后，该表达在近轴中胚层中维持，并在肌肉先驱前体细胞中变得显著，随后在后体节边界处表达。之后，sna-1在神经嵴和头部区域的中胚层衍生物中表达。激活素A可诱导动物帽细胞中sna-1的表达。在原肠胚形成期的斑马鱼无尾（ntl）突变体胚胎中，早期sna-1的表达模式正常，只是sna-1转录水平有所降低，这表明Ntl蛋白在体内不是sna-1转录的关键激活因子，但可能参与sna-1转录的增强或维持。异位表达ntl的研究获得的数据支持这一模型。
