PCR sneakiness

I found this little detail from a chapter of Tears of the Cheetah on whales to be quite amusing. A whale researcher named Scott Baker had done a lot of genetic work on various species of cetaceans, and had collected enough DNA sequences (mitochondrial and nuclear) to identify a random sample to species unambiguously. Using this genetic database as a reference, he covertly sampled whale meat (kujira) from Japanese and Korean fish markets. Kujira can be legally sold in these countries provided endangered species (which are legally protected) are not harvested. However, because Baker suspected that some of his samples were actually illegally harvested endangered species, he couldn't take them out of the country for analysis due to CITES Appendix I restrictions on moving tissue samples (or even DNA) across international borders. So what's a researcher to do? Simple, just replicate the DNA using PCR!!!!

Baker continued his work for several years, and discovered that 10% of the kujira sampled came from illegally harvested endangered species. Most of the meat came from minke whales, which are not endangered, but Baker did discover that 1/3 of the minke whale meat came from a small, endangered (and legally protected) population of minkes in the Sea of Japan. His results were published, and the proper authorities (the International Whaling Commision, or IWC) now use his techniques to monitor kujira meat.

I find it fascinating that DNA generated through PCR does not suffer the same restrictions as a whale's original DNA. On a molecular level they are pretty much exactly the same; the only difference is where the base pairs, etc. originated from. I'm not saying there's anything wrong with that (indeed, it allowed Scott Baker to complete his research which led to tighter controls on the harvest of whale meat), but it does illustrate the artificiality of definitions. The PCR products are still whale DNA, but because they didn't come from a whale they're not legally "whale DNA." Fascinating.

References:

O'brien, S.J. 2003. Tears of the Cheetah: And Other Tales From the Genetic Frontier. St. Martin's Press, New York, NY.