Nodal is a signaling molecule that belongs to the transforming growth factor‐β superfamily that plays key roles during the early stages of development of animals. In vertebrates Nodal forms an heterodimer with a GDF1/3 protein to activate the Nodal pathway. Vertebrates have a paralog of nodal in their genomes labeled Nodal‐related, but the evolutionary history of these genes is a matter of debate, mainly because of the presence of a variable numbers of genes in the vertebrate genomes sequenced so far. Thus, the goal of this study was to investigate the evolutionary history of the Nodal and Nodal‐related genes with an emphasis in tracking changes in the number of genes among vertebrates. Our results show the presence of two gene lineages (Nodal and Nodal‐related) that can be traced back to the ancestor of jawed vertebrates. These lineages have undergone processes of differential retention and lineage‐specific expansions. Our results imply that Nodal and Nodal‐related duplicated at the latest in the ancestor of gnathostomes, and they still retain a significant level of functional redundancy. By comparing the evolution of the Nodal/Nodal‐related with GDF1/3 gene family, it is possible to infer that there are several types of heterodimers that can trigger the Nodal pathway among vertebrates.

中文翻译：

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节点和节点相关基因的进化以及触发脊椎动物节点路径的异二聚体的推测组成。

Nodal是一种信号分子，属于转化生长因子-β超家族，在动物发育的早期阶段起关键作用。在脊椎动物中，Nodal与GDF1 / 3蛋白形成异源二聚体以激活Nodal途径。脊椎动物在其基因组中有一个与节点有关的节点类似物，但这些基因的进化史尚待商,，主要是因为迄今为止测序的脊椎动物基因组中存在数量不定的基因。因此，本研究的目的是研究Nodal和Nodal相关基因的进化历史，重点是追踪脊椎动物中基因数量的变化。我们的结果表明，存在两个基因谱系（节点和与节点相关），可以追溯到有颚脊椎动物的祖先。这些谱系经历了差异保留和谱系特定扩展的过程。我们的结果表明，与节点相关的节点和节点相关的复制最晚在造牙术的祖先中得以复制，并且它们仍然保留了相当大的功能冗余。通过比较与GDF1 / 3基因家族相关的Nodal / Nodal的进化，可以推断出有几种类型的异二聚体可以触发脊椎动物之间的Nodal途径。