Once extracted, the DNA must be prepared for Next-Generation Sequencing (NGS).
All work must be done in a dedicated "Clean Lab" with HEPA filtration, positive air pressure, and UV sterilization. Researchers wear full-body suits to prevent shedding their own DNA onto the samples.
To handle chemical damage, researchers may use Uracil-DNA-Glycosylase (UDG) to remove uracil bases, reducing sequencing errors, though this can sometimes shorten already tiny fragments.
The exterior of the bone or tooth is usually mechanically removed (sanding) or treated with bleach and UV light to remove surface contaminants. 3. Extraction Methods
Samples are ground into a fine powder and soaked in EDTA, which chelates calcium and dissolves the bone matrix.
Modern DNA from researchers or the environment is "fresher" and more intact than aDNA, making it easy for a tiny amount of modern DNA to overwhelm the ancient sample. 2. Sample Selection and Preparation