Mitochondrial and nuclear genes present conflicting portraits of human origins
Mitochondrial and nuclear genes present conflicting portraits of human origins
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DOI：
10.1093/oxfordjournals.molbev.a025749
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发表时间：
1997-02-01
影响因子：
10.7
通讯作者：
Hey, J
中科院分区：
文献类型：
--
作者：
Hey, J
人类线粒体 DNA (mtDNA) 序列揭示了大量多态性位点，其中分离碱基的频率差异很大。典型的多态性涉及低频碱基和高频碱基。相反，核基因数据集往往显示出过多的多态性，其中两个分离碱基都处于中间频率。对这种差异的新统计测试发现文献中报道的线粒体DNA和核基因数据集之间存在显着差异。然而，多态性模式的差异可能是由不同数据集的不同样本来源引起的。为了更仔细地检查 mtDNA 与核的差异，从 8 个个体（其中 4 个来自撒哈拉以南非洲）中的每一个的 X 连锁丙酮酸脱氢酶 E1 α 亚基 (PDHA1) 位点的一部分和线粒体控制区 I (CRI) 的一部分生成了 DNA 序列。两个基因的多态性位点频率分布存在显着差异。 PDHA1 显示出过多的中频多态性，而 CRI 显示出过多的低频-高频多态性位点。这种差异表明线粒体变异是由自然选择决定的，对于某些有关人类起源的问题可能并不理想。
Human mitochondrial DNA (mtDNA) sequences reveal an abundance of polymorphic sites in which the frequencies of the segregating bases are very different. A typical polymorphism involves one base at low frequency and the other base at high frequency. In contrast, nuclear gene data sets tend to show an excess of polymorphisms in which both segregating bases are at intermediate frequencies. A new statistical test of this difference finds significant differences between mtDNA and nuclear gene data sets reported in the literature. However, differences in the polymorphism patterns could be caused by different sample origins for the different data sets. To examine the mtDNA-nuclear difference more closely, DNA sequences were generated from a portion of the X-linked pyruvate dehydrogenase E1 alpha subunit (PDHA1) locus and from a portion of mitochondrial control region I (CRI) from each of eight individuals, four from sub-Saharan Africa. The two genes revealed a significant difference in the site frequency distribution of polymorphic sites. PDHA1 revealed an excess of intermediate-frequency polymorphisms, while CRI showed an excess of sites with the low-high frequency pattern. The discrepancy suggests that mitochondrial variation has been shaped by natural selection, and may not be ideal for some questions on human origins.