HOMEOBOXES IN XENOPUS DEVELOPMENT

同源异型盒基因的研究大大增加了我们对 脊椎动物胚胎发生的过程 过去几年的工作表明， 脊椎动物的同源结构域蛋白，像果蝇的对应物一样， 身体区域的前后（A-P）一致性。 我们现建议 研究同源异型盒基因如何指定脊椎动物的逐渐发育 A-P轴 我们最近发现，将同源框mRNA显微注射到 非洲爪蟾胚胎细胞足以引起新的 移植到宿主胚胎后的轴向结构。 这提供 一种强有力的直接方法， 赋予区域特异性，如果是这样，蛋白质的哪些部分是 责任 其他体内方法，如显微注射纯化的 mRNA和抗体，胚层移植，外植体培养， 以及转基因动物的产生。 两栖动物发展的三个关键阶段已经被确定 胚胎学研究。 我们建议研究爪蟾同源盒基因： a）在未受精卵中积累 B）在胚孔的背唇中激活 c）在神经胚阶段在中胚层套中表达。 通过研究这些基因，这些基因在不同的阶段发挥作用， 同样的调节途径，我们希望。了解脊椎动物的身体 计划正在逐步建立。 拟议的实验利用爪蟾的可及性 在艾滋病确定之前的阶段，以及 在哺乳动物胚胎中进行的同等实验 难 然而，由于所有脊椎动物的发育都是相似的， 预计这些研究将提供深入了解的原因， 所有脊椎动物的先天畸形和胚胎浪费，包括 伙计

The study of homeobox genes has substantially increased our understanding of vertebrate embryogenesis. Work in the past Eve years has shown that vertebrate homeodomain proteins, like their fruit fly counterparts, specify the antero-posterior (A-P) identity of body regions. We now propose to study how homeobox genes specify the gradual elaboration of the vertebrate A-P axis. We have recently found that microinjection of homeobox mRNA into Xenopus laevis embryonic cells is sufficient to cause induction of new axial structures after transplantation into a host embryo. This provides a powerful direct method for testing whether different homeobox genes confer regional specificity and, if so, which parts of the protein are responsible. Other in vivo methods, such as microinjection of purified mRNAs and antibodies, transplantation of germ layers, culture of explants, and the generation of transgenic animals, will also be utilized. Three crucial stages in amphibian development have been defined by embryological studies. We propose to study Xenopus homeobox genes: a) accumulated in the unfertilized egg b) activated in the dorsal lip of the blastopore c) expressed in the mesodermal mantle at the neurula stage. By studying these genes, which act at different stages of the same regulatory pathway, we hope to. understand how the vertebrate' body plan is gradually established. The proposed experiments exploit the accessibility of Xenopus embryos to manipulation at stages before the aids is determined, and during which equivalent experiments in mammalian embryos would be much more difficult. However, because all vertebrates develop similarly, it is expected that these studies will provide insights into the causes of congenital malformation and embryo wastage in all vertebrates, including man.