Manzanares Miguel, Blanco María José, Nieto M Angela
Instituto de Investigaciones Biomédicas, CSIC-UAM, Arturo Duperier 4, 28029 Madrid, Spain.
Dev Genes Evol. 2004 Jan;214(1):47-53. doi: 10.1007/s00427-003-0373-1. Epub 2003 Dec 4.
Snail genes comprise a family of zinc-finger transcription factor coding genes with multiple roles in early embryonic development of metazoans. The evolutionary history of this family has been studied in detail, revealing an initial duplication in Snail and Scratch genes preceding the protostome/deuterostome split, and posterior independent duplication events in the lineages leading to insects and vertebrates. The distribution of mammalian and teleost Snail genes fits with current models for whole genome duplication events at the base of the vertebrate lineage, plus an extra duplication in teleosts. However, two very divergent Snail genes, one from mammals and the other from teleost fishes, fit poorly into the phylogenetic analysis of the family. By means of database mining and synteny analysis, we provide evidence for these genes being orthologues, and evidence that they originated in an early duplication at the base of the vertebrates resulting in three and not two Snail genes. We further show that all three Snail genes lie in regions of extensive paralogy, revealing their common origin through segmental or chromosomal duplication.
蜗牛基因构成了一个锌指转录因子编码基因家族，在后生动物的早期胚胎发育中具有多种作用。该家族的进化史已得到详细研究，结果显示在原口动物/后口动物分化之前，蜗牛基因和Scratch基因发生了首次复制，并且在导致昆虫和脊椎动物的谱系中出现了后续的独立复制事件。哺乳动物和硬骨鱼的蜗牛基因分布与脊椎动物谱系基部全基因组复制事件的当前模型相符，另外硬骨鱼中还有一次额外的复制。然而，两个差异极大的蜗牛基因，一个来自哺乳动物，另一个来自硬骨鱼，在该家族的系统发育分析中却不太契合。通过数据库挖掘和共线性分析，我们提供了证据证明这些基因是直系同源基因，并且它们起源于脊椎动物基部的一次早期复制，从而产生了三个而非两个蜗牛基因。我们进一步表明，所有三个蜗牛基因都位于广泛旁系同源区域，揭示了它们通过片段或染色体复制的共同起源。
