Fletcher Russell B, Watson Alice L, Harland Richard M
Division of Genetics and Development, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA.
Gene Expr Patterns. 2004 Dec;5(2):225-30. doi: 10.1016/j.modgep.2004.08.001.
We report the identification of two distinct noggin genes in the tetrapod Xenopus tropicalis. Noggin functions to antagonize BMP signaling in many developmental contexts, and much work has explored its role in early vertebrate development. We have identified two noggin genes in the tropical clawed frog, X. tropicalis, a diploid anuran which is being explored for its potential as a genetic model system for early vertebrate development. Here we report the cloning and characterization of the Xenopus tropicalis noggin1 and noggin2 genes, which have distinct expression domains in the early embryo with one overlapping domain in the anterior neural tissue. X. tropicalis noggin1 expression is very similar to that of noggin in Xenopus laevis, with expression beginning in the blastula organizer region and continuing through gastrulation and neurulation in the organizer and notochord. Later, it is also expressed in the anterior neural ridge and subsequent forebrain; noggin1 is also expressed in the pharyngeal arches after neural tube closure. At the tadpole stage expression is maintained in the dorsal neural tube and is present in the otic vesicle. However, the expression of noggin2 is much more similar to the expression of noggin2 in D. rerio with expression in the forebrain, hindbrain, and somites, but unlike D. rerio, X. tropicalis noggin2 is expressed in the heart by stage 28. This work presents the first example of a tetrapod with at least two noggin genes.
我们报告了在四足动物热带爪蟾中鉴定出两个不同的头蛋白基因。头蛋白在许多发育过程中发挥着拮抗骨形态发生蛋白（BMP）信号传导的作用，并且已有大量研究探索了其在早期脊椎动物发育中的作用。我们在热带爪蟾（一种二倍体无尾两栖动物，正因其作为早期脊椎动物发育遗传模型系统的潜力而被研究）中鉴定出了两个头蛋白基因。在此，我们报告热带爪蟾头蛋白1和头蛋白2基因的克隆及特征，这两个基因在早期胚胎中具有不同的表达域，在前神经组织中有一个重叠域。热带爪蟾头蛋白1的表达与非洲爪蟾中头蛋白的表达非常相似，表达始于囊胚组织者区域，并在组织者和脊索中持续到原肠胚形成和神经胚形成阶段。之后，它也在前神经嵴和随后的前脑中表达；神经管闭合后，头蛋白1也在咽弓中表达。在蝌蚪阶段，其表达维持在背神经管中，并存在于耳泡中。然而，头蛋白2的表达与斑马鱼中头蛋白2的表达更为相似，在其前脑、后脑和体节中表达，但与斑马鱼不同的是，热带爪蟾头蛋白2在第28期时在心脏中表达。这项工作展示了首例具有至少两个头蛋白基因的四足动物。
