For the first time, scientists have shown that human DNA can be collected from air samples. Though the work is still in its early days, the proof-of-concept could pave the way towards exciting developments in forensics, ecology, and even medicine.
The technique uses what’s known as environmental DNA (eDNA), scraps of stray genetic material that have been shed from an organism into the environment, most notably skin and hair, but also urine and other waste. Scientists have previously developed a reliable way of gathering eDNA from aquatic environments and used it to identify the species found in those waters. It's also proved possible to harness eDNA from soil and snow.
However, gathering eDNA from air samples has proved a trickier task. In a new study, detailed in the journal PeerJ, scientists at Queen Mary University of London have shown how animal DNA can be collected from air sampling.
The researchers sucked out air samples from the burrows of naked mole-rats, as well as the room they were housed in, and then used existing techniques to check for DNA sequences within the sampled air. Low and behold, they detected the presence of naked mole rats in burrows, but they also detected eDNA of the species within the surrounding too.
Furthermore, they were also able to identify the presence of human DNA in both the room and burrows. They initially speculated that this might be due to contamination, but it became apparent that the genetic material was moving away from its original source and spreading thoughout the environment.
The technique still needs further refining, however. While it’s evidentally possible to collect "airDNA" from a confined room, it may prove difficult in an open environment where there’s a huge amount of dilution. Nevertheless, given the recent successes of gathering eDNA from water samples, the researchers believe the work has some promising potential applications in the future. For instance, in theory, researchers could head into a hard-to-access animal environment, like a pokey cave, and identify the species living within just by using air samples.
"The use of eDNA has become a topic of increasing interest within the scientific community particularly for ecologists or conservationists looking for efficient and non-invasive ways to monitor biological environments. Here we provide the first published evidence to show that animal eDNA can be collected from air, opening up further opportunities for investigating animal communities in hard to reach environments such as caves and burrows,” Dr Elizabeth Clare, first study author and Senior Lecturer at Queen Mary University of London, said in a statement.
The idea of scooping up eDNA from air might additionally have some profound implications in the human world too, from criminal forensics to the tracking of infectious disease.
“This technique could help us to better understand the transmission of airborne diseases such as Covid-19. At the moment social distancing guidelines are based on physics and estimates of how far away virus particles can move, but with this technique we could actually sample the air and collect real-world evidence to support such guidelines,” explains Dr Clare.