Overview of DNA Extraction
The proper selection of DNA samples is a complex, extremely important task in the forensic context. Teeth and bones are among the most environmentally resistant tissues and can persist for thousands of years, even as soft tissues decay (Dairawan & Shetty, 2020). Since bones and teeth are biological tissue, they contain cells from which DNA can be extracted (Gaeta, 2021). The sampling strategy depends on the age of the remains being sampled and the degree to which they have been degraded by environmental factors (Zeng et al., 2019). Studies in the forensic context have shown that more DNA is preserved in tubular bones, such as the femur and tibia, than in skeletal elements characterized by a higher proportion of tubular bone tissue, including skull bones, ribs, and vertebrae.
Phenol Method
The phenol method is universal and suitable for DNA extraction from almost any object containing DNA, particularly from blood, teeth, hair, and bones. When using this method, the complete removal of proteins and various cellular components takes place, resulting in high-purity DNA suitable for long-term storage (Zhang et al., 2021). The method has several disadvantages, including the requirement for highly toxic reagents and the lengthy duration of the DNA extraction procedure (Dash et al., 2022).
Ion-Exchange Resin
The method of DNA extraction using the ion-exchange resin Chelex 100 can be used only when the analyzed object does not contain large amounts of proteins, its cells are efficiently lysed, and the object has not been subjected to long-term storage (Vinueza‐Espinosa et al., 2020). Compared to the phenolic method, this method does not require the use of toxic reagents and is carried out in a shorter time. It is typically used to isolate nucleic acids from blood, sperm, saliva, and hair (Finaughty et al., 2022). The cetavlon method is also used to obtain purified DNA in soft tissues and bioliquids, without impurities that inhibit the PCR reaction, by dissolving precipitated cetavlon salts of nucleic acids in ethanol.
References
Dairawan, M., & Shetty, P. J. (2020). The evolution of DNA extraction methods. American Journal of Biomedical Science & Research, 8, 39-45.
Dash, H. R., Shrivastava, P., & Das, S. (2020). Principles and practices of DNA analysis: a laboratory manual for forensic DNA typing. Humana Press.
Finaughty, C., Heathfield, L. J., Kemp, V., & Márquez-Grant, N. (2022). Forensic DNA extraction methods for human hard tissue: A systematic literature review and meta-analysis of technologies and sample type. Forensic Science International: Genetics, 1, 1-10.
Gaeta, R. (2021). Ancient DNA and paleogenetics: Risks and potentiality. Pathologica, 113(2), 141.
Vinueza‐Espinosa, D. C., Santos, C., Martínez‐Labarga, C., & Malgosa, A. (2020). Human DNA extraction from highly degraded skeletal remains: How to find a suitable method? Electrophoresis, 41(24), 2149-2158.
Zeng, X., Elwick, K., Mayes, C., Takahashi, M., King, J. L., Gangitano, D., & Hughes-Stamm, S. (2019). Assessment of impact of DNA extraction methods on analysis of human remain samples on massively parallel sequencing success. International Journal of Legal Medicine, 133, 51-58.
Zhang, M., Cao, P., Dai, Q. Y., Wang, Y. Q., Feng, X. T., Wang, H. R.,… & Fu, Q. M. (2021). Comparative analysis of DNA extraction protocols for ancient soft tissue museum samples. Zoological Research, 42(3), 280.