Staying clean

Credit: Left: José-Manuel Benito / wikimedia.org " /> Credit: Left: José-Manuel Benito / wikimedia.org  User: Noreen Tuross, Harvard University, Cambridge, Mass. Project: Using genetic techniques to establish relationships among ancient hominids. Problem: Almost all the DNA in archeological samples is rife with contamination —

Josh P. Roberts
Apr 1, 2008
<figcaption> Credit: Left: José-Manuel Benito / wikimedia.org </figcaption>
Credit: Left: José-Manuel Benito / wikimedia.org 

User:
Noreen Tuross, Harvard University, Cambridge, Mass.

Project:
Using genetic techniques to establish relationships among ancient hominids.

Problem:
Almost all the DNA in archeological samples is rife with contamination — bacterial, fungal, or just plain unidentified. Avoiding amplification of human DNA, either from other samples or from lab personnel, can be a challenge.

Solution:
Tuross uses a combination of precautions and double-checks to minimize incidences of artifactual DNA becoming data. "Because of the way we have to do PCR in ancient samples — which is low annealing temperatures, high cycle numbers, and sometimes a lot of Taq — that's sort of a recipe for brewing up a contaminant," notes Tuross.

Using a HEPA-filtered clean room, Tuross' lab extracts DNA from ancient artifacts such as bones. From there, the DNA samples...