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 are brought to a separate building for amplification and sequencing. "And the amplicand never, ever comes back into the lab," ...
