The single amphioxus Hox cluster contains 15 genes and may well resemble the ancestral chordate Hox cluster. We have sequenced the Hox genomic complement of the European amphioxus Branchiostoma lanceolatum and compared it to the American species, Branchiostoma floridae, by phylogenetic footprinting to gain insights into the evolution of Hox gene regulation in chordates. We found that Hox intergenic regions are largely conserved between the two amphioxus species, especially in the case of genes located at the 3' of the cluster, a trend previously observed in vertebrates. We further compared the amphioxus Hox cluster with the human HoxA, HoxB, HoxC, and HoxD clusters, finding several conserved noncoding regions, both in intergenic and intronic regions. This suggests that the regulation of Hox genes is highly conserved across chordates, consistent with the similar Hox expression patterns in vertebrates and amphioxus.

中文翻译：

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出乎意料的是，祖先脊索动物 Hox 簇中有大量保守的非编码区域。

单一的 amphioxus Hox 簇包含 15 个基因，很可能类似于祖先的脊索动物 Hox 簇。我们通过系统发育足迹法对欧洲两栖类斑节鱼的 Hox 基因组补体进行了测序，并将其与美国物种佛罗里达州斑节鱼进行了比较，以深入了解脊索动物中 Hox 基因调控的进化。我们发现 Hox 基因间区域在两种文鱼属物种之间很大程度上是保守的，特别是在位于簇 3' 的基因的情况下，这是先前在脊椎动物中观察到的趋势。我们进一步比较了文昌鱼 Hox 簇与人类 HoxA、HoxB、HoxC 和 HoxD 簇，发现了几个保守的非编码区，包括基因间和内含子区域。这表明 Hox 基因的调控在脊索动物中是高度保守的，