摘要
The ParaHox genes consist of 3 homeobox gene families, Gsx, Xlox, and Cdx, all of which have fundamental roles in development. Xlox (known as IPF1 or PDX1 in vertebrates), for example, is crucial for development of the vertebrate pancreas and is also involved in regulation of insulin expression. The invertebrate amphioxus has a gene cluster containing one gene from each of the gene families, whereas in all vertebrates examined to date there are additional copies resultant from ParaHox gene cluster duplications at the base of the vertebrate lineage. Extant vertebrates basal to bony and cartilaginous fish are central to the question of when and how these multiple genes arose in the vertebrate genome. Here, we report the mapping of a ParaHox gene cluster in 2 species of hagfishes. Unexpectedly, these basal vertebrates have lost a functional Xlox gene from this cluster, unlike every other vertebrate examined to date. Furthermore, our phylogenetic analyses suggest that hagfishes may have diverged from the vertebrate lineage before the duplications, which created the multiple ParaHox clusters in jawed vertebrates.
摘要译文
ParaHox基因由3个同源异型盒基因家族组成，Gsx，Xlox和Cdx，它们都在发育中起着重要的作用。例如，Xlox（在脊椎动物中称为IPF1或PDX1）对于脊椎动物胰腺的发育至关重要，并且也参与调节胰岛素表达。无脊椎动物文昌鱼具有包含来自每个基因家族的一个基因的基因簇，而在迄今为止检查的所有脊椎动物中，脊椎动物谱系底部的ParaHox基因簇重复产生了额外的拷贝。现存的脊椎动物基底骨骼和软骨鱼类是这些多基因何时以及如何在脊椎动物基因组中出现的问题的核心。这里，我们报告了2种ha鱼中ParaHox基因簇的图谱。出乎意料的是，这些基底脊椎动物已经失去了这个簇的功能性Xlox基因，与迄今为止所检查的其他脊椎动物不同。此外，我们的系统发育分析表明，在复制之前，海may可能已经与脊椎动物谱系分离，它在颌下脊椎动物中创建了多个ParaHox群集。
Rebecca F. Furlong;Ruth Younger;Masanori Kasahara;Richard Reinhardt;Michael Thorndyke;Peter W. H. Holland. A Degenerate ParaHox Gene Cluster in a Degenerate Vertebrate[J]. Molecular Biology and Evolution, 2007,24(12): 2681–2686