A general scenario of Hox gene inventory variation among major sarcopterygian lineages.
A general scenario of Hox gene inventory variation among major sarcopterygian lineages.
复制标题
主要肉翅目谱系中 Hox 基因库存变异的一般情况
DOI：
10.1186/1471-2148-11-25
复制
发表时间：
2011-01-26
影响因子：
3.4
通讯作者：
Zhang P
中科院分区：
文献类型：
--
作者：
Liang D;Wu R;Geng J;Wang C;Zhang P
众所周知，Hox 基因在塑造后生动物的身体结构方面发挥着关键作用。因此，这些基因的进化动力学对于解释进化多样性的模式至关重要。在现存的肉翅目动物中，包括叶鳍鱼和四足动物，我们对 Hox 基因和簇的了解很大程度上局限于几种模式生物，如青蛙、鸟类和哺乳动物。一些进化差距仍然存在，特别是对于那些具有派生身体形态或在生命树上占据关键位置的群体来说，阻碍了我们对 Hox 基因库存如何沿着肉翅目谱系变化的理解。我们通过全面的 PCR 调查和基因组行走确定了六个肉翅目类群的 Hox 基因库存：肺鱼、蚓螈、蝾螈、蛇、海龟和鳄鱼。与人类 Hox 基因库存相比，六个肉翅目类群代表中每一个的可变 Hox 基因通过 PCR 调查在代表该类群广泛进化覆盖范围的许多相关物种中进一步验证其存在/不存在。海龟、鳄鱼、鸟类和胎盘哺乳动物拥有相同的 39 个 Hox 基因。 HoxD12 在蛇、两栖动物和肺鱼中不存在。 HoxB13 在青蛙和蚓螈中丢失。叶鳍鱼类、两栖动物和有鳞爬行动物拥有 HoxC3。 HoxC1 仅存在于蚓螈和叶鳍鱼中。与腔棘鱼类似，肺鱼也含有 HoxA14，迄今为止仅在叶鳍鱼中发现。我们的 Hox 基因变异数据有利于肺鱼-四足动物、龟-主龙和青蛙-蝾螈之间的关系，这意味着 HoxD12 的缺失与趾数减少没有直接关系。我们新确定的 Hox 库存数据为肉翅目沿线的 Hox 基因的进化动态提供了更完整的场景。无肢、蠕虫状蚓螈和蛇与身体形态较少的动物拥有相似的 Hox 基因库存，这表明它们身体形态的变化可能是由于其他修饰而不是 Hox 基因数量的变化。此外，我们的结果为未来对这些动物的整个 Hox 簇进行测序提供了基础。
Hox genes are known to play a key role in shaping the body plan of metazoans. Evolutionary dynamics of these genes is therefore essential in explaining patterns of evolutionary diversity. Among extant sarcopterygians comprising both lobe-finned fishes and tetrapods, our knowledge of the Hox genes and clusters has largely been restricted in several model organisms such as frogs, birds and mammals. Some evolutionary gaps still exist, especially for those groups with derived body morphology or occupying key positions on the tree of life, hindering our understanding of how Hox gene inventory varied along the sarcopterygian lineage. We determined the Hox gene inventory for six sarcopterygian groups: lungfishes, caecilians, salamanders, snakes, turtles and crocodiles by comprehensive PCR survey and genome walking. Variable Hox genes in each of the six sarcopterygian group representatives, compared to the human Hox gene inventory, were further validated for their presence/absence by PCR survey in a number of related species representing a broad evolutionary coverage of the group. Turtles, crocodiles, birds and placental mammals possess the same 39 Hox genes. HoxD12 is absent in snakes, amphibians and probably lungfishes. HoxB13 is lost in frogs and caecilians. Lobe-finned fishes, amphibians and squamate reptiles possess HoxC3. HoxC1 is only present in caecilians and lobe-finned fishes. Similar to coelacanths, lungfishes also possess HoxA14, which is only found in lobe-finned fishes to date. Our Hox gene variation data favor the lungfish-tetrapod, turtle-archosaur and frog-salamander relationships and imply that the loss of HoxD12 is not directly related to digit reduction. Our newly determined Hox inventory data provide a more complete scenario for evolutionary dynamics of Hox genes along the sarcopterygian lineage. Limbless, worm-like caecilians and snakes possess similar Hox gene inventories to animals with less derived body morphology, suggesting changes to their body morphology are likely due to other modifications rather than changes to Hox gene numbers. Furthermore, our results provide basis for future sequencing of the entire Hox clusters of these animals.