Assessing eDNA capture method from aquatic environment to optimise recovery of human mt-eDNA

Area of Science:

• Environmental DNA (eDNA) analysis
• Forensic science applications
• Molecular biology techniques

Background:

• Human environmental DNA (eDNA) in aquatic environments can aid forensic investigations.
• Knowledge gaps exist regarding factors influencing human eDNA detection and optimal sampling.
• Understanding the particle size association of eDNA is crucial for efficient capture.

Purpose of the Study:

• To assess the association of human mitochondrial eDNA with different particle sizes.
• To determine the optimal filter pore size for capturing eDNA from human blood and skin cells in freshwater.
• To evaluate how eDNA particle size association changes over time as degradation occurs.

Main Methods:

• Human blood and skin cells were introduced into freshwater tanks.
• Water samples were filtered through various pore sizes (0.1–8 µm) at different time points (0–72 hours).
• Human-specific quantitative PCR (qPCR) targeting the HV1 mitochondrial gene was used to quantify eDNA.

Main Results:

• For human blood, 0.45 µm filters captured the most eDNA initially, shifting to 5 µm filters after 48 hours.
• Human skin cells showed maximum eDNA recovery with 8 µm filters consistently over time.
• A ten-fold dilution improved eDNA recovery from 8 µm filters, mitigating PCR inhibition from hemoglobin.

Conclusions:

• Optimal filter pore size for human eDNA recovery varies by cell type (5 µm for blood, 8 µm for skin).
• Employing a combination of filter sizes may maximize human DNA recovery in mixed-cell scenarios.
• This research provides foundational data for optimizing human eDNA sampling strategies in forensic and environmental science.