Every Plant Has Meaning On 'Island Of Bar Codes'

  • Plummers Island, on the edge of the Potomac River a few miles upstream from Washington, D.C., is touted as the "most studied island in North America."
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    Plummers Island, on the edge of the Potomac River a few miles upstream from Washington, D.C., is touted as the "most studied island in North America."
    Melisa Goh/NPR
  • More biologists — looking at worms, flowers, birds, snails and more — have crawled over the 12-acre island  than any other spot on the East Coast, Smithsonian botanist John Kress says.
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    More biologists — looking at worms, flowers, birds, snails and more — have crawled over the 12-acre island than any other spot on the East Coast, Smithsonian botanist John Kress says.
    Melisa Goh/NPR
  • Tropical plants, like this papaw tree, share the sunlight with the more temperate oaks, maples and walnuts.
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    Tropical plants, like this papaw tree, share the sunlight with the more temperate oaks, maples and walnuts.
    Melisa Goh/NPR
  • Every single plant species on the island has had its DNA analyzed and cataloged.
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    Every single plant species on the island has had its DNA analyzed and cataloged.
    Melisa Goh/NPR
  • Scientists at the Smithsonian research labs say they only need a small sample of an organism –- "two hole-punches" — to sequence its DNA.
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    Scientists at the Smithsonian research labs say they only need a small sample of an organism –- "two hole-punches" — to sequence its DNA.
    Melisa Goh/NPR
  • Samples of plants and animals from Plummers Island are stored in cryogenic containers at minus 123 degrees Celsius.
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    Samples of plants and animals from Plummers Island are stored in cryogenic containers at minus 123 degrees Celsius.
    Melisa Goh/NPR
  • Tiny glass beads are inserted with the samples to grind them up and break the cell walls for DNA analysis.
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    Tiny glass beads are inserted with the samples to grind them up and break the cell walls for DNA analysis.
    Melisa Goh/NPR
  • Once analyzed, data are converted into a visual representation of each species' DNA. Scientists isolate some of this data to create what Kress calls a "genetic bar code" unique to each species.
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    Once analyzed, data are converted into a visual representation of each species' DNA. Scientists isolate some of this data to create what Kress calls a "genetic bar code" unique to each species.
    Melisa Goh/NPR

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Islands are often the playgrounds of imaginary scientists, from Dr. Moreau to the researchers on the TV show Lost. But this place is real: an island where every single plant species has had its DNA analyzed and cataloged.

Plummers Island is just on the edge of the Potomac River and holds the distinction of being "the most studied island in North America."

That's according to John Kress, a botanist at the Smithsonian Institution. "There's been more biologists out here looking at everything from worms to flowers to birds, mammals, snails ... than any other spot on the East Coast," he says.

The 12-acre island is an obscure little place a few miles upstream from Washington, D.C. Getting there requires a hike through a dense forest of tulip poplars, maple trees and spice bush — and a few hops over some conveniently located rocks.

Kress comes here at least once a month. Much of his research on plant life has taken him to places like Myanmar (also called Burma) and Ecuador, where there's far more biodiversity than on Plummers Island. But it's here, on this tiny little patch of land in Maryland, where a microclimate creates an unusual environment.

"We're surrounded by tropical plants," Kress says. "Papaws, spice bush — when I look in here, I feel like I'm in Costa Rica sometimes. It's the sorts of things I'd see if I was in a lowland forest in Central America."

At the highest point of the island sits a ramshackle wood cabin. This serves as a clubhouse of sorts for a super-exclusive club called the Washington Biologists Field Club. It's been around for 100 years, and membership is strictly limited — there are only 65 spots. Even with his distinguished record of research, Kress didn't get in until 10 years ago. The only way a spot opens is if a member passes away, leaves the area or resigns.

The members are the stewards of the island. They actually owned it until a few years ago, when they donated it to the federal government.

They've been studying this place for a century, but Kress brought us here to talk about one project in particular: a database of DNA markers that could potentially revolutionize the way we understand plants.

"This DNA marker we call a 'DNA bar code,' " Kress says. "We have to locate it on a certain part of the genome, but it's variable enough that it's different for all species."

While Kress refers to it as a "bar code," it isn't an actual UPC sticker like you'd find at the store. It's something that already exists within the plant's DNA.

"We have to sequence that DNA to actually identify the plant," Kress says. "We're not there yet in terms of me picking a leaf off the ground and telling you immediately from its DNA bar code what that is. We would have to take it back to the lab, sequence it. But technology is heading in the direction where we expect [that] what now sits on top of a desk as a DNA sequencer will eventually fit in the palm of your hand."

Within a few years, Kress imagines kids wandering through forests around the world with portable scanners that could analyze a sample of any plant, check it against the DNA database, and know within a few seconds what species they're looking at.

But to get to that future requires some lab work. That work happens in Suitland, Md. — at the Smithsonian Museum Support Center.

The center is a giant campus where the Smithsonian stores all the stuff you don't see in the museums. It also hosts dozens of research labs where groundbreaking work happens every day.

Kress says scientists refer to it lovingly as "The Death Star" because it's one of the cleanest places you've ever seen.

Here, Kress' partner Dave Erickson analyzes the plant samples sent to him from around the world, including those collected on Plummers Island.

"We literally take two hole-punches out, and that's the source of all the DNA we use," Erickson says. "That is more than enough DNA to do all the sequencing — in fact, it's so much DNA, we can save it for whole genome sequencing down the line if we get to that."

Once the samples come in, Erickson grinds them up and sends them to a DNA extractor machine. Eventually, the DNA is analyzed and the data from the gene is converted into the "DNA bar code." That bar code is what goes into the DNA database.

A DNA reference library could serve a great number of uses. For example, "say there's a kid in the hospital," Erickson says. "He's sick, he barfs up something. They can recover that fragment of leaf tissue he ate, do a DNA extraction."

"Because we have a reference library," he says, "they know exactly which gene to target and sequence, and they can figure out what this kid ate."

Back on Plummers Island, Kress says the future is pretty far away — there are literally millions of species to sequence, and thousands more yet to be discovered.

But at least here, on these 12 acres in the Potomac, the job is complete.

"It's pretty amazing to walk through here and know we have a DNA bar code for every plant that's here," Kress says.

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