Producer: The Secret Garden of the Cattle Herding Class
Source: NPR, Wired
Compiled: Sail2008
Editor-in-Charge: Sunnisky
This is the first time eDNA sampling technology has been used to collect animal DNA from the air.
A key part of protecting endangered species is figuring out their habitats. Now, the researchers say they've discovered a powerful new tool: extracting DNA from the air.
"The idea is a bit crazy," admits Elizabeth Claire, a molecular ecologist at York University in Toronto, Canada. "Exactly, we're pulling DNA out of the air."
But it worked. As one of two papers published last Thursday in the journal Contemporary Biology, Claire's team's paper shows that dozens of animal species can be detected just by sampling the air.
They took 72 samples and used a laboratory technique called polymerase chain reaction to amplify the amount of material collected until there was enough evidence to identify genetic markers for individual species.
She says DNA filters work like coffee filters: "Let the air through and any particles will be trapped, just like filtering through water but trapping coffee grounds." All we have to do is intercept DNA, cells, or tiny tissue fragments in the air on this filter, and then go back to the sterile laboratory, open the test tube, take out this micro filter, and extract the DNA directly from it. ”
What is "crazy creativity"
Tracking species with environmental DNA (eDNA) is nothing new, and researchers have been tracking aquatic animals with water DNA for years, and they can also obtain eDNA from plants floating in the air.
"One thing we found in our eDNA study is that any environmental medium (water, soil, snow, etc.) has the potential to harbor DNA that we can sample," Stephen Spear, a biologist at the U.S. Geological Survey, said by email. Spear used eDNA to track an aquatic salamander known as the "American Giant Salamander."
But according to Kristine Bohmann, a researcher at the Global Institute at the University of Copenhagen in Denmark and the first author of a second paper published in Contemporary Biology, using eDNA obtained from the air to track large land animals such as rhinos or giraffes is called "madness."
Bowman's team came up with the idea a few years ago, independent of Claire's team, when she was working on crazy research ideas for a Danish foundation that funded advanced science.
"In the end I was dissatisfied and blurted out: 'No! It has to be crazier! It's like pulling animal DNA out of the air! She recalled.
The idea was adopted, and she eventually received funding and recruited a postdoc named Christina Lingard. Lingard's first job was figuring out what kind of equipment the team could use to extract eDNA from the air.
"We tried three different devices, one of which is a commercial vacuum cleaner," Lingard said. ”
The results are good. They used it to take DNA samples, even though it was "super noisy." Lingard also used a homemade sampler to install a small fan similar to a computer fan in a 3D printed case. They are equally effective, but they are also much quieter and more power efficient. Bowman even thinks they will be more useful in actual sampling in the wild.
The story told by two zoos
For the experiment to be successful, Bowman's team also needed a good place to look for animal DNA.
The place where they work is in Copenhagen, where there is Copenhagen Zoo, which is pretty much tailored to this experiment: most of the animals here are non-native, so they will be very prominent in DNA analysis.
"If we detect the flamingo's DNA, then we'll be sure it's not coming from somewhere else, but from the flamingo paddock," Bowman said. ”
The team set up three sample-taking air filters around Copenhagen Zoo to capture tiny genetic material floating in the breeze for 30 hours each, and the results were astounding: They extracted DNA from 49 animals, including rhinos, giraffes and elephants.
An air DNA sampling object at Copenhagen Zoo, sloth
They even detected peacock fish DNA in the pond of the rainforest pavilion, which made them ecstatic.
Meanwhile, Elizabeth Claire of Queen Mary University of London also sampled at an outdoor zoo in Cambridgeshire, England.
Her team found 25 species of animals, including 17 captive animals such as gibbons, dingoes, mongooses, sloths and donkeys. They also found random visitors, such as squirrels that forage for food in zoos, and even some non-zoo animals, such as the Eurasian hedgehog, which is critically endangered in the UK.
At the UK Zoo, several dingoes stand in front of the air sampling equipment
The two teams only learned of each other's research when they were about to submit their papers to a scientific journal, but Claire and Boman knew each other, so the two teams did not rush to publish first, but instead got in touch and decided to publish the results jointly.
Can aerial DNA help track endangered species?
Claire said there are still many questions that go unanswered. First, the researchers are still unsure what the eDNA they detected is actually, possibly skin, saliva, or even urine or feces.
In addition, the DNA of some species is not extracted at all, even if we know they are there. Claire's team missed the maned wolf, and although they could be smelled throughout the zoo, the Bowman team missed the hippopotamus at Copenhagen Zoo.
Stephen Spear argues that the current state of research on aerial eDNA is very similar to when the first papers on aquatic eDNA were published more than a decade ago, and more research is needed to show how air sampling eDNA can be done, such as: "Is this technology always effective for smaller or larger animals?" How does it compare to other methods such as camera traps? What is the best way to take an eDNA sample from the air?"
Claire is eager to answer these questions in depth and has developed eDNA air sampling as a cornerstone technology for environmental protection. Her goal is to establish a global biological surveillance system, which does not yet exist.
"My idea is to deploy samplers around the globe to extract DNA from different sources like soil, honey, rain and snow, air and water, sequence it on site, and then send the data to a server," she said. ”
Claire believes that the answers to some of the toughest questions about environmental protection may lie right in front of us, hanging in the air.
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