We leave DNA everywhere, including in the air, and for the first time, researchers have collected animal DNA from just air samples, according to a new study.
The DNA that living things, human and otherwise, released in the environment are called environmental DNA (eDNA). Collecting eDNA from 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 detect the presence of terrestrial animals,”
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As a proof-of-concept experiment, Clare and her colleagues tried to collect DNA from the air in an animal facility that houses a model organism, naked mole rat. The researchers discovered both human and mole rat DNA in air from both the mole rat enclosure and the room where the encapsulation is located.
“The demonstration that DNA from 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.
Over the past decade, the collection and analysis of eDNA to study and manage plant and animal populations has declined, Barnes said. “The analogy I use is like the detective at the scene, finding a piece of cigarette and blackening it for DNA to place the criminal at the scene. We do it with eDNA but instead of looking for criminals, we look for a rare or evasive species, “said Barnes. The species may be endangered or an invasive species that is new to an environment, he said.
Prior to this study, some researchers had collected plant DNA from the air, but most of these experiments involved plants that “are expected to deliberately release DNA plumes into the air in the form of pollen and disperse seeds,” Barnes said. Animals, on the other hand, do not. “We had no idea this would work,” Clare told WordsSideKick.com.
But while animals do not shoot pollen spores into the air, for example, they throw DNA into saliva and dead skin cells. To see if animal eDNA from these sources could be collected, Clare and her colleagues vacuumed air from an enclosure of naked mole rats and from the room that houses the enclosures through filters similar to the HEPA filters often found in heating and ventilation systems. The researchers then extracted DNA from the filters and sequenced it. To identify the species the DNA came from, the researchers compared the sequences with reference sequences in a database.
The discovery of human DNA in the animal’s enclosure first surprised scientists, Clare told WordsSideKick.com. But given that people care about the mole rats, it made sense in retrospect, Clare said.
The presence of human DNA in almost all samples from the study is “a major obstacle,” Barnes said. On the one hand, it shows encouraging that the detection method is sensitive, Barnes said. But “this may also indicate that airborne samples are particularly easy to contaminate with DNA from the research team, especially when mammals are the target of analysis,” he added.
To avoid such pollution, researchers may have to use clean space techniques – think air filters, dresses and hair nets – to avoid adding DNA to the environments they study or to DNA samples they work with, he said.
In the future, researchers hope to use the technique to monitor animal species in hard-to-reach places. “I can imagine sticking a pipe into a shelf or down a tunnel system and sucking the air out of the system instead of having to try to track the animals to find out what’s present,” Clare told WordsSideKick.com.
It can also be a good way to spot 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 benefits, Barnes said. “[The method might] give us an opportunity to map for organisms without having to deal with them and stress them, “he said.
Whether eDNA analysis will allow researchers to estimate population sizes, or the number of animals living in a home, is the subject of debate, but Clare said she does not think it is good for it. “There are too many steps in the procedure that can cause the amount of DNA you collect to vary,” she said.
Clare and colleagues are now studying how far airDNA can travel and how the size of the room affects how much eDNA can be detected, Clare said in the video abstract.
Another important step in the study of animal airDNA will be to try to collect airDNA from animals outdoors, rather than in a research laboratory, Barnes said.
Originally published on WordsSideKick.com.
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