Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, D-04103 Leipzig, Germany.
Curr Biol. 2010 Feb 9;20(3):231-6. doi: 10.1016/j.cub.2009.11.068. Epub 2009 Dec 31.
The recovery of DNA sequences from early modern humans (EMHs) could shed light on their interactions with archaic groups such as Neandertals and their relationships to current human populations. However, such experiments are highly problematic because present-day human DNA frequently contaminates bones [1, 2]. For example, in a recent study of mitochondrial (mt) DNA from Neolithic European skeletons, sequence variants were only taken as authentic if they were absent or rare in the present population, whereas others had to be discounted as possible contamination [3, 4]. This limits analysis to EMH individuals carrying rare sequences and thus yields a biased view of the ancient gene pool. Other approaches of identifying contaminating DNA, such as genotyping all individuals who have come into contact with a sample, restrict analyses to specimens where this is possible [5, 6] and do not exclude all possible sources of contamination. By studying mtDNA in Neandertal remains, where contamination and endogenous DNA can be distinguished by sequence, we show that fragmentation patterns and nucleotide misincorporations can be used to gauge authenticity of ancient DNA sequences. We use these features to determine a complete mtDNA sequence from a approximately 30,000-year-old EMH from the Kostenki 14 site in Russia.
从早期现代人 (EMHs) 中恢复 DNA 序列可以揭示他们与尼安德特人等古代群体的相互作用以及与当前人类群体的关系。然而，此类实验存在很大的问题，因为现代人类的 DNA 经常会污染骨骼 [1, 2]。例如，在最近对新石器时代欧洲骨骼的线粒体 (mt) DNA 的研究中，只有当序列变体在现代人群中不存在或很少见时，才被认为是真实的，而其他变体则必须被视为可能的污染 [3, 4]。这限制了对携带稀有序列的 EMH 个体的分析，从而导致对古代基因库的偏颇看法。其他识别污染 DNA 的方法，例如对与样本接触过的所有个体进行基因分型，将分析限制在可以进行分析的标本上 [5, 6]，但并不能排除所有可能的污染来源。通过研究尼安德特人遗骸中的 mtDNA，其中可以通过序列区分污染和内源性 DNA，我们表明可以使用片段化模式和核苷酸错误掺入来评估古代 DNA 序列的真实性。我们使用这些特征来确定来自俄罗斯科斯特尼茨 14 遗址的大约 30,000 年前的 EMH 的完整 mtDNA 序列。
