Williams N A, Holland P W
School of Animal and Microbial Sciences, The University of Reading, UK.
Brain Behav Evol. 1998;52(4-5):177-85. doi: 10.1159/000006562.
The molecular basis of regionalisation and patterning of the developing brain is an area of current intense interest. Members of the Otx, Pax-2/5/8 and Hox gene families appear to play important roles in these processes in vertebrates, but functional divergence and genetic redundancy arising from gene duplication events obscures our view of the roles played by these genes during the evolution of vertebrate brains. Determination of the ancestral gene copy number in chordates through molecular phylogenetics, accompanied by gene expression analysis in all three chordate subphyla (vertebrates, cephalochordates and urochordates) may distinguish between ancestral and derived expression domains and give clues to the roles played by these genes in chordate ancestors. Application of this comparative approach indicates evolutionary homologous brain regions (fore-/midbrain, isthmus/cerebellum and hindbrain) in chordates and supports homology of the frontal eye of cephalochordates to the paired eyes of vertebrates.
发育中大脑区域化和模式形成的分子基础是当前备受关注的领域。Otx、Pax - 2/5/8和Hox基因家族的成员似乎在脊椎动物的这些过程中发挥着重要作用，但基因复制事件导致的功能分歧和遗传冗余模糊了我们对这些基因在脊椎动物大脑进化过程中所起作用的认识。通过分子系统发育学确定脊索动物中的祖先基因拷贝数，并结合对所有三个脊索动物亚门（脊椎动物、头索动物和尾索动物）的基因表达分析，可能会区分祖先和衍生的表达域，并为这些基因在脊索动物祖先中所起的作用提供线索。这种比较方法的应用表明了脊索动物中进化同源的脑区（前脑/中脑、峡部/小脑和后脑），并支持头索动物的额眼与脊椎动物的双眼具有同源性。
