DNA Barcoding is the Modern Tricorder

By Wesley Fenlon

Biologists can identify most species on the planet with a unique piece of DNA, almost like scanning a fingerprint database.

Watching certain episodes of the the original Star Trek, it's hard not to laugh at the show's 1960s-era technology transplanted into the future. But one of the series' most famous pieces of technology, the science tricorder, is still ahead of its time--it may be bulky, but it's still able to identify any known life form in a way modern scientists dream of. More than forty years later, we're still jealous of the tricorder, but scientists have actually figured out how to replicate its technology using a process called DNA barcoding. It's almost as good as Spock's magic box.

In "The technologhy that links taxonomy and Star Trek," BoingBoing describes the advances biologists have made in being able to identify different animal species. Ironically, the computational power needed for DNA barcoding fills a lab, much like the gigantic computers that existed when Star Trek was on the air in the 1960s. Spock's tricorder still has an advantage when it comes to portability, but as BoingBoing writes, we really can identify most organisms on the world with DNA barcoding.

Photo credit: Flickr user hartsell via Creative Commons.

"Canadian biologist Paul Hebert...thought there might be an easy way to quickly identify species using short DNA sequences that are unique to one species or another. If you had a database of these sequences, then all you'd have to do would be to match a sample to a sequence and you'd know what species you were looking at. It's similar to the way we store fingerprints, and then use those to match prints from a crime scene with an individual person."

Sounds easy! But it's not, of course. Here's the problem: DNA barcoding animals commonly relies on a gene called COI, which is a piece of mtDNA found within a cell's mitochondria. This DNA is passed down from generation to generation in the egg cells of organisms, picking up errors and changes in the sequence from one mother to another. Those changes in the sequence are what make DNA barcoding work, but they're also what make it tough.

"The idea is that the changes that happen to CO1 should be able to serve as a marker between species," writes BoingBoing. "In order for that to work, though, the mutation rate has to hit a sweet spot, said Karen James, a staff scientist at Mount Desert Island Biological Laboratory. She does a lot of work with DNA barcoding and described the ideal amount of variation in the DNA sequence as being a Goldilocks sort of problem. If you have too little variation (i.e., if the mtDNA doesn't change fast enough) then you'll have too many different species that share the same barcode. But if the mutations happen too quickly and you have too much variation, then you could get a bunch different barcodes within the same species. Either way, the barcode would be useless — just as if lots of people shared the same set of fingerprints."

Thankfully, the system works for most animal species. It doesn't work for plants, as their mtDNA changes too slowly. But there are some important functions for DNA barcoding beyond simple identification--one scientist points out that by studying which species are in a particular environment over a certain period of time, it's possible to judge biodiversity and environmental changes.

There's no telling how long it will take to cram the tech behind DNA barcoding into a tricorder, but BoingBoing has more on the technology and how it's currently being used to identify different animal species.