Bailey W J, Kim J, Wagner G P, Ruddle F H
Department of Biology, Yale University, New Haven, Connecticut 06520-8103.
Mol Biol Evol. 1997 Aug;14(8):843-53. doi: 10.1093/oxfordjournals.molbev.a025825.
In vertebrates and the cephalochordate, amphioxus, the closest vertebrate relative, Hox genes are linked in a single cluster. Accompanying the emergence of higher vertebrates, the Hox gene cluster duplicated in either a single step or multiple steps, resulting in the four-cluster state present in teleosts and tetrapods. Mammalian Hox clusters (designated A, B, C, and D) extend over 100 kb and are located on four different chromosomes. Reconstructing the history of the duplications and its relation to vertebrate evolution has been problematic due to the lack of alignable sequence information. In this study, the problem was approached by conducting a statistical analysis of sequences from the fibrillar-type collagens (I, II, III, and IV), genes closely linked to each Hox cluster which likely share the same duplication history as the Hox genes. We find statistical support for the hypothesis that the cluster duplication occurred as multiple distinct events and that the four-cluster situation arose by a three-step sequential process.
在脊椎动物以及头索动物文昌鱼（脊椎动物最近的亲属）中，Hox基因在单个基因簇中相连。随着高等脊椎动物的出现，Hox基因簇以单步或多步方式复制，导致硬骨鱼和四足动物中出现四个基因簇的状态。哺乳动物的Hox基因簇（命名为A、B、C和D）延伸超过100 kb，位于四条不同的染色体上。由于缺乏可比对的序列信息，重建复制历史及其与脊椎动物进化的关系一直存在问题。在本研究中，通过对纤维状胶原蛋白（I、II、III和IV）的序列进行统计分析来解决这个问题，这些胶原蛋白基因与每个Hox基因簇紧密相连，可能与Hox基因共享相同的复制历史。我们发现有统计学证据支持这样的假设：基因簇复制是作为多个不同事件发生的，并且四个基因簇的情况是通过三步连续过程产生的。
