Think that sheep's milk cheese comes from a sheep? DNA doesn't lie
Who says scientists with PhD.s should have all the fun? Not us, especially after a high school class project involving DNA analysis resulted in the discovery of an invasive insect species and several mislabeled food items. Enjoying that sturgeon caviar? It might be Mississippi paddlefish.
Brenda Tan and Matt Cost, both students at Trinity School in New York City, did a projected last year they called DNAHouse, collecting specimens from around their homes and nearby areas, and analyzing them via the Barcode of Life Database used to identify various species. (They had help from DNA barcoding experts from Rockefeller University and the American Museum of Natural History, both in New York City.) In an article in the January issue of the journal BioScience, the two reported they found readable DNA in 151 out of 217 items, including DNA from 95 different animal species.
Among the findings: Inside a box of grapefruit shipped from Texas was an Oriental latrine fly, considered an invasive species common to the South. In a packaged snack of dried shredded squid was DNA of the jumbo flying squid, which can grow up to 100 pounds. Tan and Cost also took hair samples from several classmates and wrote, "We were happy to report that our classmates came back as 100% human" (That must have been a relief.) A cockroach at first looked like Periplaneta americana, an American cockroach, but its DNA differed enough to possibly render it a new species or subspecies.
Among the food tested, not everything was as it seemed. A pricey bit of sheep's milk cheese was actually made from cow's milk, fish labeled smelt was really Japanese anchovy, and venison dog treats were made from beef.
In their paper, the authors wrote, "We do not know where or why the mislabeling occurred, but most cases appeared to involve substitution of a less expensive or less desirable item, suggesting the possibility of deliberate mislabeling for economic gain. We also think mislabeling is a serious problem because certain individuals have allergies or dietary restrictions regarding certain foods. ... Like a powerful flashlight, DNA exposes hidden identities of living and once-living things. We look forward to more explorations!"
Trinity has produced other sleuthing students: Last year Kate Stoeckle and Louisa Strauss discovered that one-fourth of the fish they bought at Manhattan markets and restaurants were mislabeled. The two will address the American Assn. for the Advancement of Science annual meeting this year.
-- Jeannine Stein
Photo: The mystery cockroach. Credit: Brenda Tan and Matt Cost