Soil and water

Scientists suck DNA from zoo animals out of the air


The researchers were able to detect the DNA of elephants at the Copenhagen Zoo simply by sampling the air nearby.

IDA MARIE ODGAARD ​​/ Ritzau Scanpix / AFP via Getty Ima

A key part of protecting endangered species is figuring out where they live. Now, researchers say they’ve found a powerful new tool that may help: suck DNA out of the air.

“It’s a bit of a crazy idea,” admits Elizabeth Clare, molecular ecologist at York University in Toronto, Canada. “We are literally sucking DNA from the sky.”

But it works. Clare’s group were one of two to publish articles in the newspaper Current biology Thursday showing that dozens of animal species could be detected by a simple sample of air.

A “crazy” idea takes off

The use of environmental DNA, or eDNA, to track species is not new. In recent years, researchers have used DNA in water to track aquatic animals. They were also able to recover DNA from plants floating in the air.

“One thing we found in the eDNA research is that any environmental medium (water, soil, snow, etc.) has the potential to contain DNA that we can sample,” Stephen F. Spear, biologist research in the United States. Geological Survey, written by email. Spear used eDNA to track a species of aquatic salamander known as the Ruler of Hell.

But the idea of ​​using DNA from the air to track a large land animal like a rhino or a giraffe still seemed “crazy” to Kristine Bohmann, a researcher at the GLOBE Institute at the University of Copenhagen in Denmark, and principal author of the second article in current biology.

Bohmann and his team came up with the idea independently of Clare’s group a few years ago. She was trying to come up with a wacky research idea for a Danish foundation that funds a distant science.

“In the end, I was so frustrated that I blurted out, ‘No! It must be crazier! It must be like sucking animal DNA out of the air!’” She recalls.

The idea stuck and she eventually got funding and hired a postdoctoral fellow named Christina Lynggaard. Lynggaard’s first job was to figure out what kind of device the team could use to aspirate eDNA from the air.

“We tried three different devices, and one of them was a commercial vacuum cleaner,” says Lynggaard.

It worked. They could sample DNA just by using it, even though it was “super noisy”. Lynggaard also used homemade samplers that used a small fan, like a computer fan, mounted in a 3D printed case. They performed just as well and were much quieter and more energy efficient. Bohmann thinks they will be more useful in actual sampling in the wild.

The story of two zoos

For the experiment to be successful, the team also needed a good place to search for animal DNA.

“We realized we were based in Copenhagen… we had the Copenhagen Zoo,” Bohmann recalls. It was almost as if the zoo had been custom-built for this experiment: most of the animals are not native, so they really stand out in a DNA analysis.

“If we do spot a flamingo, well, we’re sure it’s not just from that flamingo enclosure,” she says.

The team collected samples from across the zoo. And they were shocked. They picked up 49 animal species, including rhinos, giraffes and elephants.

“We even detected the guppy that lived in the rainforest house’s pond,” says Bohmann. “It was absolutely breathtaking.”

Meanwhile, Elizabeth Clare, who is also affiliated with Queen Mary University in London, was sampling at an open-air zoo in Cambridgeshire, UK.

His team was able to detect 25 species, even some animals outside the zoo: “Things like the Eurasian hedgehog, which is critically endangered in the UK,” says Clare. Zookeepers have verified that hedgehogs have been seen roaming the area.

The two groups were about to submit to a scientific review when they learned of their respective work.

“I woke up to this flurry of texts from my co-authors saying, ‘There’s another article, have you seen this? “” Clare recalls.

Clare and Bohmann knew each other and rather than competing to publish a publication first, the two groups got in touch and decided to publish their findings together.

“We independently confirm that it works for ourselves and for everyone,” Clare said. “I think, we both thought, the papers are stronger together.”

Could airborne DNA help track endangered species?

There are a lot of unanswered questions. On the one hand, says Clare, researchers are still not sure what electronic DNA they are actually detecting. It can be skin, saliva, or even urine or feces.

In addition, “there were species that we just never detected even though we know they were there,” she notes. The maned wolves missed her group, although she could smell them all over the zoo grounds. Lynggaard says their team missed the hippos at Copenhagen Zoo.

“I consider the current state of airborne eDNA to be very similar to the publication of the first aquatic eDNA papers over ten years ago,” says Stephen Spear, the USGS biologist who does was affiliated with neither group.

He believes much more research will be needed to show how eDNA air sampling can be applied: “Will this technique work consistently for smaller or more mobile animals?” How does it compare to other methods such as camera traps? best way to sample and collect eDNA in the air? “

For her part, Clare is eager to answer these questions and develop eDNA air sampling into a basic technology for conservation.

“I have this vision of samplers deployed around the world that can suck DNA from all these different sources, from soil to honey, rain, snow, air and water, sequence them. on site, transmit the data to the servers, ”she says. The goal would be a global biomonitoring system for the world’s animals. “We don’t have a coordinated system for this.”

Clare believes the answers to some of the toughest conservation questions could literally be right in front of our eyes, hanging in the air.

Copyright 2022 NPR. To learn more, visit https://www.npr.org.