We left DNA everywhere, including in the air, and for the first time, researchers collected DNA from animals from mere air samples, according to a new study.
O DNA that living beings, human or not, spilled into the environment are called environmental DNA (eDNA). Collecting eDNA from the water to learn about the species that live there has become quite common, but until now, no one had tried to collect animal eDNA from the air.
“What we wanted to know was whether we could filter eDNA from the air to track the presence of terrestrial animals,” said study author Elizabeth Clare, an ecologist at Queen Mary University of London, in a video summary for the study, published on March 31 in the journal PeerJ. “We were interested in whether we could use this ‘airDNA’ as a way of assessing which species were present in a den or cave where we could not easily see or capture them,” she added.
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As a proof-of-concept experiment, Clare and her colleagues tried to collect DNA from the air at an animal facility that housed a model organism, the naked mole rat. The researchers detected human and mole rat DNA in the air from both the mole rat compartments and the room where the compartments are housed.
“The demonstration that the DNA of relatively large animals can also be detected in air samples dramatically expands the potential for airborne eDNA analysis,” said Matthew Barnes, an ecologist at Texas Tech University in Lubbock, who was not involved in the new study. .
In the past decade, eDNA collection and analysis to study and manage plant and animal populations has taken off, said Barnes. “The analogy I use is like the detective at the crime scene, finding a cigarette butt and cleaning the DNA to locate the criminal at the crime scene. We do this with eDNA, except that instead of looking for criminals, we are looking for a rare or indescribable species, “said Barnes. The species may be endangered or an invasive species new to an environment, he said.
Before this study, some researchers collected plant DNA from the air, but most of these experiments involved plants that “should intentionally release DNA plumes into the air in the form of pollen and seed dispersal,” said Barnes. Animals, on the other hand, do not do this. “We had no idea if this would work,” Clare told Live Science.
But while animals do not release pollen spores into the air, they release DNA in the form of saliva and dead skin cells, for example. To see if animal eDNA from these sources could be collected, Clare and her colleagues drew in air from a compartment of naked mole rats and the room that housed the compartments through filters similar to HEPA filters commonly found in heating and ventilation systems. . The researchers then extracted the DNA from the filters and sequenced it. To identify the species of DNA origin, the researchers compared the sequences to reference sequences in a database.
The discovery of human DNA inside the animal shell initially surprised the researchers, Clare told Live Science. However, since humans care for mole rats, it makes sense in retrospect, said Clare.
The presence of human DNA in almost all samples in the study is “a major obstacle,” said Barnes. On the one hand, it shows in an encouraging way that the detection method is sensitive, said Barnes. But “it may also suggest that airborne samples are particularly easy to contaminate with the research team’s DNA, especially when mammals are the target of the analysis,” he added.
To avoid such contamination, researchers may have to use clean room techniques – such as air filters, aprons and hair nets – to avoid adding their DNA to the environments they are studying or to DNA samples they are working with, he said .
In the future, scientists hope to use the technique to monitor animal species in hard-to-reach homes. “I can imagine stuffing a tube into a perch or tunnel system and sucking the air out of that system, instead of trying to track animals to find out what is present,” Clare told Live Science.
It can also be a good way to detect species that are present, but rare in a given environment, such as a endangered species, she added. And it can help detect a species without interacting with it, which can have advantages, said Barnes. “[The method might] gives us the opportunity to research organisms without having to manipulate and stress them, “he said.
Whether eDNA analysis would allow scientists to estimate the size of the population or the number of animals that live in a home is a subject for debate, but Clare said she does not think it is good for that. “There are many steps in the procedure that can cause the amount of DNA collected to vary,” she said.
Now Clare and his colleagues are studying how far aerial DNA can travel and how the size of the space affects the amount of eDNA that can be detected, said Clare in the video summary.
Another important step in studying animal air DNA will be to try to collect DNA from animal air outdoors, rather than in a research laboratory, Barnes said.
Originally published on Live Science.