The origin and evolution of animal appendages.
The origin and evolution of animal appendages.
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DOI：
10.1073/pnas.94.10.5162
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发表时间：
1997-05
影响因子：
11.1
通讯作者：
G. Panganiban;Steven M. Irvine;C. Lowe;H. Roehl;L. S. Corley;B. Sherbon;J. Grenier;J. Fallon;J. Kimble;M. Walker;G. Wray;B. Swalla;M. Martindale;S. Carroll
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文献类型：
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作者：
G. Panganiban;Steven M. Irvine;C. Lowe;H. Roehl;L. S. Corley;B. Sherbon;J. Grenier;J. Fallon;J. Kimble;M. Walker;G. Wray;B. Swalla;M. Martindale;S. Carroll
动物进化出了不同的附肢，适应于运动、进食和其他功能。昆虫和脊椎动物对附肢形成的遗传学了解最深。节肢动物肢体生长过程中无末端(DLL)同源蛋白的表达以及DLL同源基因(DLX)在鱼鳍和四足肢芽中的表达使我们研究这种调控基因的表达是否可能是原口和后口附肢形成的一般特征。我们发现Dll在发育中的多毛类环节动物附足、甲壳类叶足、海鞘壶腹、甚至棘皮管足的近端轴线上均有表达。Dll/DLX在这6个体腔纲的不同附属物中的表达可能是趋同的，但这需要Dll/DLX在进化过程中多次独立的共同选择。似乎更有可能的是，外胚层DLL/DLX沿着近端轴线的表达起源于一个共同的祖先，并随后被用来在各种生物中形成体壁突起。我们认为，大多数原口动物和后口动物的这个前寒武纪祖先拥有形成附肢的遗传机制的元素，甚至可能有附肢。
Animals have evolved diverse appendages adapted for locomotion, feeding and other functions. The genetics underlying appendage formation are best understood in insects and vertebrates. The expression of the Distal-less (Dll) homeoprotein during arthropod limb outgrowth and of Dll orthologs (Dlx) in fish fin and tetrapod limb buds led us to examine whether expression of this regulatory gene may be a general feature of appendage formation in protostomes and deuterostomes. We find that Dll is expressed along the proximodistal axis of developing polychaete annelid parapodia, onychophoran lobopodia, ascidian ampullae, and even echinoderm tube feet. Dll/Dlx expression in such diverse appendages in these six coelomate phyla could be convergent, but this would have required the independent co-option of Dll/Dlx several times in evolution. It appears more likely that ectodermal Dll/Dlx expression along proximodistal axes originated once in a common ancestor and has been used subsequently to pattern body wall outgrowths in a variety of organisms. We suggest that this pre-Cambrian ancestor of most protostomes and the deuterostomes possessed elements of the genetic machinery for and may have even borne appendages.