Holland P
Department of Zoology, University of Oxford, UK.
Bioessays. 1992 Apr;14(4):267-73. doi: 10.1002/bies.950140412.
A wide range of anatomical features are shared by all vertebrates, but absent in our closest invertebrate relatives. The origin of vertebrate embryogenesis must have involved the evolution of new regulatory pathways to control the development of new features, but how did this occur? Mutations affecting regulatory genes, including those containing homeobox sequences, may have been important: for example, perhaps gene duplications allowed recruitment of genes to new roles. Here I ask whether comparative data on the genomic organization and expression patterns of homeobox genes support this hypothesis. I propose a model in which duplications of particular homeobox genes, followed by the acquisition of gene-specific secondary expression domains, allowed the evolution of the neural crest, extensive organogenesis and craniofacial morphogenesis. Specific details of the model are amenable to testing by extension of this comparative approach to molecular embryology.
所有脊椎动物都具有一系列广泛的解剖学特征，但在与我们亲缘关系最近的无脊椎动物中却不存在。脊椎动物胚胎发育的起源必定涉及新调控途径的演化，以控制新特征的发育，但这是如何发生的呢？影响调控基因的突变，包括那些含有同源框序列的基因，可能起到了重要作用：例如，基因复制或许使得基因能够承担新的功能。在此，我探讨关于同源框基因的基因组组织和表达模式的比较数据是否支持这一假说。我提出一个模型，其中特定同源框基因的复制，随后获得基因特异性的二级表达结构域，促成了神经嵴、广泛器官发生和颅面形态发生的演化。该模型的具体细节可通过将这种比较方法扩展到分子胚胎学来进行检验。
