Salmon sperm DNA increases sample recovery from cotton swabs

Area of Science:

• Forensic Science
• Molecular Biology
• Genetics

Background:

• Low DNA template amounts in forensic samples pose analytical challenges.
• Carrier nucleic acids improve DNA yields when added during extraction or storage.
• Application of carrier nucleic acids to sampling substrates like cotton swabs is unexplored.

Purpose of the Study:

• To investigate if carrier nucleic acids applied to cotton swabs before DNA collection enhance DNA recovery.
• To assess potential interference of carrier nucleic acids with downstream forensic DNA analysis.

Main Methods:

• Carrier nucleic acids (Poly (A) RNA or salmon sperm DNA) were spotted onto cotton swabs.
• Human genomic DNA was applied to the swabs post-carrier application.
• DNA recovery, real-time PCR quantitation, STR amplification, and capillary electrophoresis were evaluated.

Main Results:

• Poly (A) RNA did not improve human DNA recovery.
• Salmon sperm DNA carrier significantly increased human DNA recovery from cotton swabs.
• DNA recovery increased proportionally with carrier DNA amount, reaching ~100% with 10 µg.
• No inhibitory effects on downstream forensic DNA profiling were observed.

Conclusions:

• Salmon sperm DNA carrier applied to cotton swabs enhances human DNA yield.
• Optimal carrier DNA amount for increased recovery is 10 µg.
• This method improves DNA recovery without compromising forensic DNA analysis integrity.