Evaluation of DNA Extraction Methods from Waterlogged Bones: A Pilot Study

Area of Science:

• Forensic Science
• Molecular Biology
• Bioarchaeology

Background:

• Postmortem soft tissue decomposition in aquatic environments necessitates DNA extraction from bone for identification.
• Bone DNA integrity is influenced by environmental factors like water submersion and temperature (accumulated degree days).

Purpose of the Study:

• To evaluate the impact of water submersion on bone DNA purity and quantity.
• To compare the efficacy of three DNA extraction methods for submerged bone samples.
• To identify optimal bone types and extraction techniques for forensic DNA analysis.

Main Methods:

• DNA was extracted from submerged humerus and rib samples using phenol-chloroform, ChargeSwitch® gDNA Plant Kit, and DNeasy Blood and Tissue Kit.
• DNA purity was assessed using the 260/280 absorbance ratio.
• DNA quantity was determined by quantification assays, with results analyzed across bone types and extraction methods.

Main Results:

• The phenol-chloroform method yielded DNA with optimal purity (~1.8), while ChargeSwitch® and DNeasy kits produced fair and unacceptable purity, respectively.
• Rib samples and the ChargeSwitch® gDNA Plant Kit showed the lowest mean Ct values, indicating higher DNA yield.
• DNA purity remained consistent across accumulated degree days for humerus and rib samples.

Conclusions:

• Magnetic bead technology (e.g., ChargeSwitch® gDNA Plant Kit) and rib bones are recommended for processing DNA from submerged skeletal remains.
• Optimized extraction methods and bone selection are critical for successful DNA identification from aquatic forensic cases.