Department of Genetics, University of Barcelona, Spain.
Genomics Proteomics Bioinformatics. 2011 Jun;9(3):65-76. doi: 10.1016/S1672-0229(11)60010-7.
Hox and ParaHox genes constitute two families of developmental regulators that pattern the Anterior-Posterior body axis in all bilaterians. The members of these two groups of genes are usually arranged in genomic clusters and work in a coordinated fashion, both in space and in time. While the mechanistic aspects of their action are relatively well known, it is still unclear how these systems evolved. For instance, we still need a proper model of how the Hox and ParaHox clusters were assembled over time. This problem is due to the shortage of information on gene complements for many taxa (mainly basal metazoans) and the lack of a consensus phylogenetic model of animal relationships to which we can relate our new findings. Recently, several studies have shown that the Acoelomorpha most probably represent the first offshoot of the Bilateria. This finding has prompted us, and others, to study the Hox and ParaHox complements in these animals, as well as their activity during development. In this review, we analyze how the current knowledge of Hox and ParaHox genes in the Acoelomorpha is shaping our view of bilaterian evolution.
Hox 和 ParaHox 基因构成了两组发育调控因子，它们在所有两侧对称动物中构建了前后体轴。这两组基因的成员通常在基因组簇中排列，并在空间和时间上协调工作。虽然它们作用的机制方面相对较为清楚，但这些系统的进化方式仍不清楚。例如，我们仍然需要一个合适的模型来解释 Hox 和 ParaHox 簇是如何随着时间的推移而组装的。这个问题是由于许多分类群（主要是基础后生动物）的基因组合信息不足，以及缺乏我们可以将新发现与之相关联的动物关系的共识系统发育模型所致。最近，几项研究表明，扁盘动物门最有可能代表两侧对称动物的第一个分支。这一发现促使我们和其他人研究这些动物中的 Hox 和 ParaHox 基因及其在发育过程中的活性。在这篇综述中，我们分析了扁盘动物门中 Hox 和 ParaHox 基因的现有知识如何塑造我们对两侧对称动物进化的看法。
