Abstract：
Homology in vertebrate body plans is traditionally ascribed to the high-level conservation of regulatory components within the genetic programs governing them, particularly during the \"phylotypic stage.\" However, advancements in embryology and molecular phylogeny have unveiled the dynamic nature of gene repertoires responsible for early development. Notably, the Nodal and Lefty genes, members of the transforming growth factor-beta superfamily producing intercellular signaling molecules and crucial for left-right (L-R) symmetry breaking, exhibit distinctive features within their gene repertoires. These features encompass among-species gene repertoire variations resulting from gene gain and loss, as well as gene conversion. Despite their significance, these features have been largely unexplored in a phylogenetic context, but accumulating genome-wide sequence information is allowing the scrutiny of these features. It has exposed hidden paralogy between Nodal1 and Nodal2 genes resulting from differential gene loss in amniotes. In parallel, the tandem cluster of Lefty1 and Lefty2 genes, which was thought to be confined to mammals, is observed in sharks and rays, with an unexpected phylogenetic pattern. This article provides a comprehensive review of the current understanding of the origins of these vertebrate gene repertoires and proposes a revised nomenclature based on the elucidated history of vertebrate genome evolution.
摘要：
传统上，脊椎动物身体计划中的同源性归因于控制它们的遗传程序中调节成分的高度保守性，特别是在“生理阶段”。\"然而,胚胎学和分子系统发育的进步揭示了负责早期发育的基因库的动态性质。值得注意的是,Nodal和Lefty基因,转化生长因子-β超家族的成员产生细胞间信号分子，对左右（L-R）对称破坏至关重要，在他们的基因库中表现出独特的特征。这些特征包括由基因获得和丢失引起的物种间基因库变异，以及基因转换。尽管意义重大,这些特征在系统发育背景下大部分尚未被探索，但是积累全基因组序列信息允许对这些特征进行审查。它暴露了羊膜中差异基因丢失导致的Nodal1和Nodal2基因之间的隐藏旁系同源。并行,Lefty1和Lefty2基因的串联簇，被认为仅限于哺乳动物，在鲨鱼和射线中观察到，具有意想不到的系统发育模式。本文提供了对这些脊椎动物基因库起源的当前理解的全面回顾，并根据脊椎动物基因组进化的阐明历史提出了修订的命名法。
