Optimal Ancient DNA Yields from the Inner Ear Part of the Human Petrous Bone (original) (raw)
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World Archaeology, 2020
Advances in NGS sequencing technologies, improved laboratory protocols and new bioinformatic workflows have seen huge increases in ancient DNA (aDNA) research on archaeological materials. A large proportion of aDNA work now utilizes the petrous portion of the temporal bone (pars petrosa), which is recognized as an excellent skeletal element for long-term ancient endogenous (host) DNA survival. This has been significant due to the often low endogenous content of other skeletal elements, meaning that large amounts of sequencing are frequently required to obtain sufficient genetic coverage. However, exclusive sampling of the petrous for aDNA analysis introduces a new set of potential biases into our scientific studies – and these issues are yet to be considered by ancient DNA researchers. This paper aims to outline the possible biases of utilizing petrous bones to undertake aDNA analyses and highlight how these complications may potentially be overcome in future research.
American Journal of Physical Anthropology, 2006
We present a method to distinguish authentic ancient DNA from contaminating DNA in a human bone. This is achieved by taking account of the spatial distribution of the various sequence families within the bone and the extent of degradation of the template DNAs, as revealed by the error content of the sequences. To demonstrate the veracity of the method, we handled two ancient human tibiae in order to contaminate them with modern DNA, and then subjected segments of the bones to various decontaminating treatments, including removal of the outer 1–2 mm, before extracting DNA, cloning, and obtaining a total of 107 mitochondrial DNA sequences. Sequences resulting from the deliberate contamination were located exclusively in the outer 1–2 mm of the bones, and only one of these 27 sequences contained an error that could be ascribed to DNA degradation. A second, much smaller set of relatively error-free sequences, which we ascribe to contamination during excavation or curation, was also located exclusively in the outer 1–2 mm. In contrast, a family of 72 sequences, displaying extensive degradation products but identifiable as haplogroup U5a1a, was distributed throughout one of the bones and represents the authentic ancient DNA content of this specimen. Am J Phys Anthropol, 2006. © 2006 Wiley-Liss, Inc.
Improving access to endogenous DNA in ancient bones and teeth
2015
Poor DNA preservation is the most limiting factor in ancient genomic research. In the vast majority of ancient bones and teeth, endogenous DNA molecules only represent a minor fraction of the whole DNA extract, rendering traditional shot-gun sequencing approaches cost-ineffective for whole-genome characterization. Based on ancient human bone samples from temperate and tropical environments, we show that an initial EDTA-based enzymatic 'pre-digestion' of powdered bone increases the proportion of endogenous DNA several fold. By performing the pre-digestion step between 30 min and 6 hours on five bones, we identify the optimal pre-digestion time and document an average increase of 2.7 times in the endogenous DNA fraction after 1 hour of pre-digestion. With longer pre-digestion times, the increase is asymptotic while molecular complexity decreases. We repeated the experiment with n=21 and t=15-30', and document a significant increase in endogenous DNA content (one-sided pair...