Zardoya R, Abouheif E, Meyer A
Department of Ecology and Evolution, State University of New York, Stony Brook 11794-5245, USA.
Proc Natl Acad Sci U S A. 1996 Nov 12;93(23):13036-41. doi: 10.1073/pnas.93.23.13036.
The study of development has relied primarily on the isolation of mutations in genes with specific functions in development and on the comparison of their expression patterns in normal and mutant phenotypes. Comparative evolutionary analyses can complement these approaches. Phylogenetic analyses of Sonic hedgehog (Shh) and Hoxd-10 genes from 18 cyprinid fish species closely related to the zebrafish provide novel insights into the functional constraints acting on Shh. Our results confirm and extend those gained from expression and crystalline structure analyses of this gene. Unexpectedly, exon 1 of Shh is found to be almost invariant even in third codon positions among these morphologically divergent species suggesting that this exon encodes for a functionally important domain of the hedgehog protein. This is surprising because the main functional domain of Shh had been thought to be that encoded by exon 2. Comparisons of Shh and Hoxd-10 gene sequences and of resulting gene trees document higher evolutionary constraints on the former than on the latter. This might be indicative of more general evolutionary patterns in networks of developmental regulatory genes interacting in a hierarchical fashion. The presence of four members of the hedgehog gene family in cyprinid fishes was documented and their homologies to known hedgehog genes in other vertebrates were established.
发育研究主要依赖于分离在发育中具有特定功能的基因突变，并比较它们在正常和突变表型中的表达模式。比较进化分析可以补充这些方法。对与斑马鱼密切相关的18种鲤科鱼类的音猬因子（Shh）和Hoxd-10基因进行系统发育分析，为作用于Shh的功能限制提供了新的见解。我们的结果证实并扩展了从该基因的表达和晶体结构分析中获得的结果。出乎意料的是，在这些形态上不同的物种中，即使在第三密码子位置，Shh的外显子1也几乎不变，这表明该外显子编码刺猬蛋白的一个功能重要结构域。这令人惊讶，因为Shh的主要功能结构域一直被认为是由外显子2编码的。对Shh和Hoxd-10基因序列以及由此产生的基因树的比较表明，前者比后者受到更高的进化限制。这可能表明在以层次方式相互作用的发育调控基因网络中存在更普遍的进化模式。记录了鲤科鱼类中刺猬基因家族的四个成员的存在，并确定了它们与其他脊椎动物中已知刺猬基因的同源性。
