Schierwater Bernd, Dellaporta Stephen, DeSalle Rob
ITZ, Ecology and Evolution, TiHo Hannover, Bünteweg 17d, D-30559 Hannover, Germany.
Mol Phylogenet Evol. 2002 Sep;24(3):374-8. doi: 10.1016/s1055-7903(02)00238-5.
Understanding the evolution of metazoan bauplans is linked to understanding the evolution of Hox and ParaHox genes. At the base of metazoan radiation we see in both cases a quite confusing picture yet. Here Cnox-2 is one of the best studied diploblast Hox genes. Homologs of this gene are known from Placozoa and several Cnidaria. In those cases where full length gene sequences, or at least full length homeobox sequences, are available the relationship to Hox genes from triploblastic animals as well as the classification to Hox or ParaHox genes can be controversially discussed. The existing data on possible gene functions also reveal a quite heterogeneous picture. It seems conceivable that part of the "multicolored" picture relates to a "polygenealogical" origin of the Cnox-2 gene.
理解后生动物躯体模式的演化与理解Hox基因和ParaHox基因的演化相关联。然而，在后生动物辐射演化的基础阶段，我们在这两种情况下看到的都是一幅相当令人困惑的图景。在这里，Cnox-2是研究得最为透彻的双胚层动物Hox基因之一。该基因的同源基因在扁盘动物门和几种刺胞动物门动物中均有发现。在那些可获取全长基因序列，或至少是全长同源异型框序列的情况下，与三胚层动物Hox基因的关系以及对Hox基因或ParaHox基因的分类可能会引发争议性的讨论。关于可能的基因功能的现有数据也呈现出一幅相当多样化的图景。似乎可以想象，这幅“五彩斑斓”的图景部分与Cnox-2基因的“多谱系”起源有关。
