Herbert’s group proposed that the CO1 gene could work as a barcode for several reasons: all animals have it; it accumulates small differences as species diverge; and it’s relatively easy to extract, as the gene is found outside the cell nucleus in structures called mitochondria. Herbert's team also showed that screening the gene can distinguish closely related species with 98% accuracy. For them, it made sense to pick a small region to sequence, rather than spending considerably more time analysing the whole genome. “Whenever one has a job to do, one is always looking for the simplest way to do it,” Herbert says. If everyone uses the same little snippet, they can build a good database to use.
Since its inception, scientists have come up with all sorts of creative applications for DNA barcoding in the commercial and academic world. Researchers have used it to figure out what’s inside an eel’s stomach, identify bird flu and figure out what plants the bees that made your honey were pollinating. Damon Little, a curator at the New York Botanical Gardens has used it to see whether there’s really gingko in gingko supplements. The answer is usually no, he says. “No one can tell the difference between one set of green powder and the other.”
One particularly fertile avenue looks like being the murky world of fraudulent seafood imports. Illegal, unreported and unregulated fishing is not only a lucrative business globally, estimated to be worth between $10 and $30 billion a year, it’s the biggest threat to the sustainable management of fish stocks.
Using DNA barcoding, the Boston Globe revealed last year that 48% of the fish their reporters purchased in restaurants, grocery stores and markets in Massachusetts was mislabeled – typically serving cheaper seafood instead of more expensive species on their menus. As a result the US Food and Drug Administration announced at the end of last year it will expand its use of DNA testing in inspections of seafood manufacturers and restaurants.
The Newark facility is the first in the United States to use barcoding for customs and national security. It cost about a half a million dollars to set up – but it’s a worthwhile investment to have the barcoding technology in place, says Laura Goldstein, the lab director. “Its usefulness to us is almost unlimited,” she says. “There are so many things that we do that we can use DNA barcoding for, and we’re trying do use all of them.”
Birck says that sometimes barcoding can tell even more than just what species a sample is from. One importer was labelling some salmon as “farm raised.” Customs asked Birck to confirm if it was, in fact, raised on a farm. That’s not usually something DNA barcoding could do, except that only Atlantic salmon is farmed. Pacific salmon is almost always caught in the wild. So by figuring out which species they were looking at, Birck could tell customs whether or not the importers were lying or not.
However, the method isn’t without its glitches. While the CO1 gene works most of the time, there are still species immune to barcoding. Sturgeons, for example, simply can’t be barcoded using the CO1 gene – the gene hasn’t evolved enough between different species – so identifying their caviar through barcoding is impossible. Plants are also quite difficult. To sequence them, scientists don’t use the CO1 gene at all; instead two little regions of DNA are used as “barcodes”, and often even that can’t quite identify certain species. But, overall, the method works for the vast majority of animal species, and because it’s standardized, scientists all over the world can contribute to the archive.