Davis Gregory K, D'Alessio Joseph A, Patel Nipam H
Committee on Developmental Biology, University of Chicago, Chicago, IL 60637, USA.
Dev Biol. 2005 Sep 1;285(1):169-84. doi: 10.1016/j.ydbio.2005.06.014.
Several features of Pax3/7 gene expression are shared among distantly related insects, including pair-rule, segment polarity, and neural patterns. Recent data from arachnids imply that roles in segmentation and neurogenesis are likely to be played by Pax3/7 genes in all arthropods. To further investigate Pax3/7 genes in non-insect arthropods, we isolated two monoclonal antibodies that recognize the products of Pax3/7 genes in a wide range of taxa, allowing us to quickly survey Pax3/7 expression in all four major arthropod groups. Epitope analysis reveals that these antibodies react to a small subset of Paired-class homeodomains, which includes the products of all known Pax3/7 genes. Using these antibodies, we find that Pax3/7 genes in crustaceans are expressed in an early broad and, in one case, dynamic domain followed by segmental stripes, while myriapods and chelicerates exhibit segmental stripes that form early in the posterior-most part of the germ band. This suggests that Pax3/7 genes acquired their role in segmentation deep within, or perhaps prior to, the arthropod lineage. However, we do not detect evidence of pair-rule patterning in either myriapods or chelicerates, suggesting that the early pair-rule expression pattern of Pax3/7 genes in insects may have been acquired within the crustacean-hexapod lineage.
Pax3/7基因表达的几个特征在亲缘关系较远的昆虫中是共有的，包括体节极性、节段极性和神经模式。来自蛛形纲动物的最新数据表明，Pax3/7基因可能在所有节肢动物的体节形成和神经发生中发挥作用。为了进一步研究非昆虫节肢动物中的Pax3/7基因，我们分离出了两种单克隆抗体，它们能识别广泛分类群中Pax3/7基因的产物，使我们能够快速调查所有四个主要节肢动物类群中Pax3/7的表达情况。表位分析表明，这些抗体与一小部分配对类同源结构域发生反应，其中包括所有已知Pax3/7基因的产物。利用这些抗体，我们发现甲壳类动物中的Pax3/7基因在早期广泛表达，在一种情况下是动态表达域，随后是节段条纹，而多足类动物和螯肢动物则表现出在胚带最后部早期形成的节段条纹。这表明Pax3/7基因在节肢动物谱系内部深处或之前就获得了它们在体节形成中的作用。然而，我们在多足类动物或螯肢动物中均未检测到体节极性模式的证据，这表明昆虫中Pax3/7基因早期的体节极性表达模式可能是在甲壳类-六足动物谱系中获得的。
