Treffkorn Sandra, Mayer Georg
Animal Evolution & Development, Institute of Biology, University of Leipzig, Talstraße 33, D-04103 Leipzig, Germany.
Gene Expr Patterns. 2013 Dec;13(8):384-94. doi: 10.1016/j.gep.2013.07.004. Epub 2013 Jul 17.
The gene decapentaplegic (dpp) and its homologs are essential for establishing the dorsoventral body axis in arthropods and vertebrates. However, the expression of dpp is not uniform among different arthropod groups. While this gene is expressed along the dorsal body region in insects, its expression occurs in a mesenchymal group of cells called cumulus in the early spider embryo. A cumulus-like structure has also been reported from centipedes, suggesting that it might be either an ancestral feature of arthropods or a derived feature (=synapomorphy) uniting the chelicerates and myriapods. To decide between these two alternatives, we analysed the expression patterns of a dpp ortholog in a representative of one of the closest arthropod relatives, the onychophoran Euperipatoides rowelli. Our data revealed unique expression patterns in the early mesoderm anlagen of the antennal segment and in the dorsal and ventral extra-embryonic tissue, suggesting a divergent role of dpp in these tissues in Onychophora. In contrast, the expression of dpp in the dorsal limb portions resembles that in arthropods, except that it occurs in the mesoderm rather than in the ectoderm of the onychophoran limbs. A careful inspection of embryos of E. rowelli revealed no cumulus-like accumulation of dpp expressing cells at any developmental stage, suggesting that this feature is either a derived feature of chelicerates or a synapomorphy uniting the chelicerates and myriapods.
基因“背腹分化蛋白”（dpp）及其同源物对于节肢动物和脊椎动物背腹体轴的建立至关重要。然而，dpp在不同节肢动物类群中的表达并不一致。在昆虫中，该基因沿身体背侧区域表达，而在早期蜘蛛胚胎中，其表达发生在一组称为积云细胞的间充质细胞中。在蜈蚣中也报道了类似积云的结构，这表明它可能是节肢动物的一个祖先特征，或者是一个将螯肢动物和多足动物联系起来的衍生特征（=共近裔性状）。为了在这两种可能性之间做出抉择，我们分析了dpp直系同源基因在节肢动物最亲近的亲属之一——栉蚕Euperipatoides rowelli中的表达模式。我们的数据揭示了触角节早期中胚层原基以及背侧和腹侧胚外组织中的独特表达模式，这表明dpp在栉蚕的这些组织中发挥着不同的作用。相比之下，dpp在背侧肢体部分的表达与节肢动物中的相似，只是它发生在栉蚕肢体的中胚层而非外胚层中。对Euperipatoides rowelli胚胎的仔细检查发现，在任何发育阶段都没有dpp表达细胞的积云状聚集，这表明这个特征要么是螯肢动物的一个衍生特征，要么是一个将螯肢动物和多足动物联系起来的共近裔性状。
