THE ETA-GLOBIN GENE - ITS LONG EVOLUTIONARY HISTORY IN THE BETA-GLOBIN GENE FAMILY OF MAMMALS
THE ETA-GLOBIN GENE - ITS LONG EVOLUTIONARY HISTORY IN THE BETA-GLOBIN GENE FAMILY OF MAMMALS
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DOI：
10.1016/0022-2836(84)90258-4
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发表时间：
1984-01-01
影响因子：
5.6
通讯作者：
SLIGHTOM, JL
中科院分区：
文献类型：
--
作者：
GOODMAN, M;KOOP, BF;SLIGHTOM, JL
在用简约法进行的系统发育重建中，利用62个已测序的珠蛋白基因和假基因(包括34个。-珠蛋白基因家族来自真兽目灵长类、狐形目、偶蹄目和啮齿目)，灵长类的分支。假基因与山羊胚胎表达。epsilon。作为一个共同祖先基因（标记为。eta.）的同源基因在单系上共同存在，与。epsilon的同源基因不同。,可以利用。delta和beta…这个灵长类动物。山羊.eta。分支在进化上更接近。并可以利用。而不是。delta。和度量。分支。在每个真兽目中，基因转换取代了部分。delta。通过度量。而在灵长类动物的后裔中。,可以利用。和.eta。在Eutheria辐射之前，它们的所有外显子和非编码区大多保留了它们单独的古代身份。祖先的基因座。-珠蛋白基因簇存在于基础真动物和原始灵长类动物中。-星团代表4-eutherian数列，由- epsilon - - gamma - - delta - - - β - -3 "与- epsilon相连。,可以利用。和.eta。是胚胎表达的基因，还有。和度量。个体发育上后来表达的基因。通过删除。在偶蹄动物的进化中消失了。在动物和啮齿类动物的进化中，以及在.eta外显子23”边界之间的所有DNA。和.delta。原狐猴进化中（狐猴具有杂交假基因。psi…eta…delta.）猿类灵长类完整地保留了祖先群的5个位点。不仅。在进化到今天的猿人的过程中，它完好无损地保留了下来，但在进化到类人猿的过程中，它在过去的4000万年中以减慢了1.1倍的速度进化。每个位点每年有10-9个取代，这是预期中性速率的1/5。有一种可能性是…位于猴的胎儿和成人染色体区域之间的位点。-珠蛋白基因簇可能在珠蛋白基因表达的个体发生开关机制中起一定作用。灵长类动物和其他哺乳动物的基因序列和基因间区数据尚不充分，尚无法确定这一缓慢速率是否为1。10-9反映了一个保守功能基因的速率，或者主要反映了类人猿DNA进化的减速中性速率，可以想象，这是由于类人猿DNA修复能力增强和生育时间延长所致。进一步的可能性是，基因校正（修复受损的DNA，防止新的等位基因的出现）和基因转换更多地涉及到保守DNA的链复制，而不是快速进化的DNA。
In phylogenetic reconstructions by the parsimony method, utilizing 62 sequenced globin genes and pseudogenes (including 34 of the .beta.-globin gene family from eutherian orders Primates, Lagomorpha, Artiodactyla and Rodentia), the branch of primate .psi..beta. pseudogenes and the goat embryonically expressed .epsilon.II gene group monophyletically together as orthologues of a common ancestral gene (labeled .eta.) distinct from orthologues of .epsilon., .gamma., .delta., and .beta.. This primate .psi..eta.-goat .eta. branch is cladistically closer to .epsilon. and .gamma. than to .delta. and .beta. branches. In each eutherian order gene conversions replaced portions of .delta. by .beta. sequences, whereas in descent of Primates .epsilon., .gamma. and .eta. mostly retained their separate ancient identities predating the radiation of Eutheria in all their exons and non-coding regions. The loci of the ancestral .beta.-globin gene cluster in basal eutherians and proto-primates, as deduced from .beta.-clusters representing the 4-eutherian orders, were linked 5''-.epsilon.-.gamma.-.eta.-.delta.-.beta.-3'' with .epsilon., .gamma. and .eta. being embryonically expressed genes, and .delta. and .beta. ontogenetically later expressed genes. Through deletions .gamma. was lost in artiodactyl evolution, .eta. in lagomorph and rodent evolution, and all DNA between exon 2 3'' boundaries of .eta. and .delta. in prosimian lemuriform evolution (lemur having the hybrid pseudogene .psi..eta..delta.). Simian primates retained intact the 5 loci of the ancestral cluster. Not only did .eta., after it became a pseudogene in the basal primates, persist intact in descent to present-day simians but in the line to hominoids it evolved during the last 40 million yr as the decelerated rate of 1 .times. 10-9 substitutions/site per yr which is 1/5 the expected neutral rate. The possibility is suggested that the .psi..eta. locus situated between fetal and adult chromosomal domains of the simian .beta.-globin gene cluster might play some role in a mechansim for ontogenetic switches of globin gene expression. Not enough sequence data on genes and intergenic regions in DNA of species of primates and other mammals as yet exist to know if the slow rate of 1 .times. 10-9 reflects the rate of a conserved functional gene or primarily reflects a decelerated neutral rate of hominoid DNA evolution, conceivably from enhanced DNA repair and longer generation times in hominoids. The further possibility is raised that gene correction (repair of damaged DNA that prevents emergence of new alleles) and gene conversion both more often involve strand copying of conserved than of rapidly evolving DNA.