We leave DNA everywhere, including in the air, and for the first time, researchers have collected animal DNA from mere air samples, according to a new study.
That DNA that living things, human and otherwise, are shed in the environment is called environmental DNA (eDNA). Collecting eDNA from water to learn about the species that lives 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, nude mole rat. The researchers discovered both human and mole rat DNA in air from both the mole rats and the room where the enclosures are 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.
In the last decade, the collection and analysis of eDNA for the study and management of plant and animal populations has gained momentum, Barnes said. “The analogy I use is like the detective at the crime scene, finding a cigarette butt and polishing it for DNA to place the criminal at the crime scene. We do it with eDNA except instead of looking for criminals we are looking for a rare or evasive nature, “Barnes said. 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 were “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 if this would work,” Clare told WordsSideKick.com.
But while animals do not shoot pollen spores into the air, they do, for example, shed DNA in the form of saliva and dead skin cells. To see if animal eDNA from these sources could be collected, Clare and her colleagues vacuumed air from a cabinet of naked mule rats and from the room that housed the cabinets, through filters similar to HEPA filters commonly found in heating and ventilation systems. The researchers then extracted DNA from the filters and sequenced it. To identify the species from which the DNA came, the researchers compared the sequences with reference sequences in a database.
The discovery of human DNA in domestic animals first surprised researchers, Clare told WordsSideKick.com. But considering humans take care of the mole ferrets, it made sense backwards, 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 encourages showing that the detection method is sensitive, Barnes said. But “this may also suggest 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 contamination, researchers may need to use clean room techniques – think air filters, dresses and hair nets – to avoid adding their 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 homes. “I can imagine sticking a pipe down a roost 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 could help detect a species without interacting with it, which could have benefits, Barnes said. “[The method might] give us an opportunity to study 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 dwelling 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.
Now, Clare and colleagues are investigating how far airDNA can travel and how the size of the space 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.