Intra- and Inter-Element Variability in Mitochondrial and Nuclear DNA from Fresh and Environmentally Exposed Skeletal Remains.

Successful identification of skeletonized remains often relies upon DNA analyses, frequently focusing on the mid-diaphysis of weight-bearing long bones. This study explored intra-bone DNA variability using bovine and porcine femora, along with calcanei and tali. DNA from fresh and short-term environmentally exposed bone was extracted utilizing demineralization and standard lysis buffer protocols, and DNA quantity and quality were measured. Overall, femoral epiphyses, metaphyses, and the tarsals had more nuclear and mitochondrial DNA than did the femoral diaphyses. DNA loss was much more rapid in buried bones than in surface exposed bones, while DNA quality differed based on environment, but not bone region/element. The demineralization protocol generated more DNA in some bone regions, while the standard lysis was more effective in others, and neither significantly affected DNA quality. Taken together, these findings reinforce the importance of considering inter- and intra-bone heterogeneity when sampling skeletal material for forensic DNA-based identifications.