Exploring the Quality of Historic DNA From Pinned Beetles

Area of Science:

• Genomics
• Molecular Biology
• Entomology

Background:

• Obtaining fresh DNA for biodiversity studies is difficult.
• Historical natural history collections contain DNA but it's often degraded and contaminated.
• Assessing DNA quality from preserved specimens is crucial for genomic research.

Purpose of the Study:

• To evaluate DNA isolation methods for degraded, dry-preserved insect specimens.
• To determine the impact of specimen age and DNA quantity on DNA sequence quality.
• To assess the suitability of museum specimens for next-generation sequencing.

Main Methods:

• Tested three DNA isolation methods on ethanol and dry-preserved beetle specimens.
• Applied the best method to fresh and historical Cleridae (Coleoptera) specimens (74 Trichodes species).
• Assessed DNA quality using fragment length analysis and whole-genome sequencing.

Main Results:

• A silica-column oligo isolation protocol for short DNA fragments outperformed other methods for historical DNA.
• DNA fragment length slightly decreased with specimen age, but DNA quantity remained stable.
• Higher DNA amounts correlated with more recovered loci and longer, less gapped sequence alignments.
• Dry-preserved samples showed significantly higher contamination levels.

Conclusions:

• Common DNA isolation kits are suitable for dry-preserved museum specimens for next-generation sequencing.
• The amount of isolated DNA, rather than specimen age, significantly impacts DNA sequence quality.
• Substantial genomic information can be retrieved from old, dry-preserved insect specimens using simple DNA isolation protocols.