ARCHETYPAL ORGANIZATION OF THE AMPHIOXUS HOX GENE-CLUSTER
ARCHETYPAL ORGANIZATION OF THE AMPHIOXUS HOX GENE-CLUSTER
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DOI：
10.1038/370563a0
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发表时间：
1994-08-18
期刊：
影响因子：
64.8
通讯作者：
HOLLAND, PWH
中科院分区：
文献类型：
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作者：
GARCIAFERNANDEZ, J;HOLLAND, PWH
组织成基因簇是Hox基因的基本特征和诊断特征（1）。昆虫和线虫基因组具有单个Hox基因簇（在Dvosophila中分裂）;在哺乳动物中，在不同染色体上的四个簇中有38个Hox基因（2，3）。染色体位置、激活时间和脊椎动物Hox基因的前表达极限之间的共线关系表明，聚类对于精确的时空基因调控以及胚胎模式化可能是重要的（2，4）。Hox基因在后生动物中具有广泛的系统发育分布，并参与控制沿着前后体轴的区域化（2，5）。有人认为，Hox基因数量和基因组结构的变化在后生动物的体型进化中发挥了作用（6-8），但识别显著的变化是困难的，因为Hox基因结构只在很少的和广泛不同的分类群（主要是昆虫，线虫和脊椎动物）中已知（3）。在这里，我们分析了头索动物文昌鱼中Hox基因的复杂性和组织，文昌鱼被认为是脊椎动物的姐妹群（9）。我们发现文昌鱼基因组只有一个Hox基因簇。它具有类似的基因组组织的四个哺乳动物Hox集群，并包含同源物的至少前十个旁系同源组的脊椎动物Hox基因的共线阵列。值得注意的是，这个组织是兼容的推断为脊椎动物的直接祖先，我们的结论是，文昌鱼是一个关键的中间阶段的Hox集群进化的活代表。
ORGANIZATION into gene clusters is an essential and diagnostic feature of Hox genes(1). Insect and nematode genomes possess single Hox gene clusters (split in Dvosophila); in mammals, there are 38 Hox genes in four clusters on different chromosomes(2,3). A collinear relationship between chromosomal position, activation time and anterior expression limit of vertebrate Hox genes suggests that clustering may be important for precise spatiotemporal gene regulation and hence embryonic patterning(2,4). Hox genes have a wide phylogenetic distribution within the metazoa, and are implicated in the control of regionalization along the anteroposterior body axis(2,5). It has been suggested that changes in Hox gene number and genomic organization played a role in metazoan body-plan evolution(6-8), but identifying significant changes is difficult because Hox gene organization is known from only very few and widely divergent taxa (principally insects, nematodes and vertebrates)(3). Here we analyse the complexity and organization of Hox genes in a cephalochordate, amphioxus, the taxon thought to be the sister group of the vertebrates(9). We find that the amphioxus genome has only one Hox gene cluster. It has similar genomic organization to the four mammalian Hox clusters, and contains homologues of at least the first ten paralogous groups of vertebrate Hox genes in a collinear array. Remarkably, this organization is compatible with that inferred for a direct ancestor of the vertebrates; we conclude; that amphioxus is a living representative of a critical intermediate stage in Hox cluster evolution.