Dealing with minor differences in bone matrix: can spectra follow the DNA preservation?

Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy is a relatively fast and inexpensive but reliable method that can be used as a rough screening tool for DNA preservation. Although it is an excellent analytical tool, it only provides relative information on the chemical structure of heterogeneous materials such as bone and its usefulness and accuracy for predicting the preservation of DNA in samples originating from different body regions of minimally altered remains was never tested before. 144 bone samples were collected from different body regions of three individuals discovered in a Second World War mass grave. DNA was extracted and quantified, followed by STR typing. Samples were analysed with ATR-FTIR spectroscopy. Comparing the preservation state of DNA and chemometric indices, the usefulness of the method was tested. Correlations between the DNA preservation and chemometric indices were highly variable, especially when considering different body regions. Best DNA preservation was correlated with a balanced ratio between carbonates and phosphates, and with high collagen quality and quantity. It seems that, when dealing with relatively young and well-preserved remains, more attention should be paid to collagen quality. In addition, the results indicate that DNA quality and DNA quantity correlate differently with chemometric indices.

衰减全反射傅里叶变换红外（ATR-FTIR）光谱法是一种快速便捷、成本低廉且结果可靠的分析手段，可作为DNA保存状态的初步筛查工具。尽管该方法是性能优异的分析工具，但仅能提供骨骼等异质材料化学结构的相对信息；且此前从未有研究对该方法用于预测轻度改变遗骸不同身体部位来源样本的DNA保存状态的实用性与准确性进行验证。
本研究从第二次世界大战集体墓葬中出土的3具个体的不同身体部位采集了144份骨骼样本。提取并定量DNA后开展短串联重复（STR）分型，并采用ATR-FTIR光谱法对所有样本进行检测分析。通过对比DNA保存状态与化学计量学指标，本研究验证了该方法的实用性。
DNA保存状态与化学计量学指标间的相关性存在显著异质性，尤其在针对不同身体部位样本进行分析时更为明显。DNA保存状态最优的样本，其碳酸盐与磷酸盐比例均衡，且胶原蛋白的质量与含量均处于较高水平。由此可见，在针对相对年轻且保存完好的遗骸开展研究时，应更加关注胶原蛋白的质量。此外，研究结果显示，DNA质量与DNA数量分别与化学计量学指标呈现不同的相关性模式。