Developmental basis of limblessness and axial patterning in snakes
Developmental basis of limblessness and axial patterning in snakes
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DOI：
10.1038/20944
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发表时间：
1999-06-03
期刊：
影响因子：
64.8
通讯作者：
Tickle, C
中科院分区：
文献类型：
--
作者：
Cohn, MJ;Tickle, C
蛇的进化涉及脊椎动物身体平面组织的重大变化，但这些变化的发育基础尚不清楚。蟒蛇的轴骨由数百个相似的脊椎组成，前肢缺失，后肢严重减少，在许多脊椎动物中发现了合并的肢体缺失和躯干延长[1]，表明这些变化可能与共同的发育机制有关。在这里，我们发现在蟒蛇胚胎中，HOX基因的表达区域沿着体轴扩展，这既可以解释前肢缺失的原因，也可以解释在中轴骨骼中胸部特征的扩展。后肢芽被启动，但通常肢体发育所需的尖脊和极化区信号通路：不被激活，蟒蛇的腿芽生长和声波刺猬发出的信号可以通过应用成纤维细胞生长因子或与鸡尖脊重组来挽救。在正常的蟒蛇发育过程中，未能激活这些信号通路也可能源于蛇进化早期发生的HOX基因表达的变化。
The evolution of snakes involved major changes in vertebrate body plan organization, but the developmental basis of those changes is unknown. The python axial skeleton consists of hundreds of similar vertebrae, forelimbs are absent and hindlimbs are severely reduced, Combined limb loss and trunk elongation is found in many vertebrate taxa(1), suggesting that these changes may be linked by a common developmental mechanism. Here we show that Hox gene expression domains are expanded along the body axis in python embryos, and that this can account for both the absence of forelimbs and the expansion of thoracic identity in the axial skeleton, Hindlimb buds are initiated, but apical-ridge and polarizing-region signalling pathways that are normally required for limb development: are not activated, Leg bud outgrowth and signalling by Sonic hedgehog in pythons can be rescued by application of fibroblast growth factor or by recombination with chick apical ridge. The failure to activate these signalling pathways during normal python development may also stem from changes in Hox gene expression that occurred early in snake evolution.