Using PCR to amplify the DNA of long dead specimens can provide researchers and archaeologists with a wealth of information about the subjects.
However, the process is not always straightforward; the DNA decays, often leaving so little behind that study becomes impossible.
A study published in the Journal of Separation Science has looked at using the racemization of amino acids as a proxy for DNA preservation, giving archaeologists a rapid screening method for samples too badly damaged to extract.
Amino acids in living species exist mostly in L-form, rather than D-form, with enzymes working to maintain this dominance.
Upon death the enzymes stop working and the amino acids racemize to D-form. This process is influenced by many of the same factors that affect DNA decay, so the researchers developed a method to use HPLC to determine the D/L ratio of certain amino acids.
The method was applied to bones recovered from seven mummies and treated with hydrochloric acids to remove any proteins from external sources.
It revealed a D/L ratio less than 0.1, indicating sufficient DNA for extraction and PCR amplification.
As the pre-treatment, extraction and analysis only took a few minutes each, the study concludes that the method represents a fast and inexpensive way to examine the state of DNA in old bones and could find use in the archaeological community.
Source: The Column [September 16, 2010]
