When we think of city air, we might consider the temperature, smell, wind speed, or even smoke levels. But we probably don't think much about DNA. Research has shown, however, that DNA molecules can float in the air. Advances in DNA technology have shown that DNA can even be collected from the air and sequenced, which can reveal all sorts of stuff. For example, in new research about so-called environmental DNA, scientists have shown that the air in Dublin, Ireland contains DNA from a variety of illicit substances, including cannabis, poppy, and psychedelic mushrooms. The study of environmental DNA (eDNA) also has some important practical applications such as tracking wildlife. The findings have been reported in Nature Ecology & Evolution, and this burgeoning field of research is opening up new ethical questions about genetic research.
"The level of information that's available in environmental DNA is such that we're only starting to consider what the potential applications can be, from humans, to wildlife to other species that have implications for human health," said senior study author David Duffy, Ph.D., a professor of wildlife disease genomics at the University of Florida.
Duffy and colleagues have created new techniques for dealing with eDNA so that they can learn more about the genetics of sea turtles. Eventually, they broadened their work so they were studying all species whose DNA was collected from water, sand, or soil samples; that has included humans as well. But DNA doesn't even have to fall into some kind of sediment or material so it can be collected; it is floating around in the air.
Scientists have shown that air filters can collect genetic material. By running an air filter for a few weeks, days, or even just hours, genetic material that ends up in that filter can then be sequenced and analyzed. This tool can reveal who or what has been moving around the area.
"When we started, it seemed like it would be hard to get intact large fragments of DNA from the air; but that's not the case. We're actually finding a lot of informative DNA," Duffy said. "That means you can study species without directly having to disturb them, without ever having to see them. It opens up huge possibilities to study all the species in an area simultaneously, from microbes and viruses all the way up to vertebrates like bobcats and humans, and everything in between."
To demonstrate the utility of this method, the investigators set up air filters in Dublin. After sequencing the genetic material that collected on the filters and comparing those sequences to known sequences, the researchers identified all sorts of things. They found microbes like bacteria and viruses, showing that this tool can help identify emerging pathogens. This approach could also be used to track things like pollen to a very precise degree.
When the tool was turned on in Florida, the researchers identified spiders and bobcats living in a local forest. Endangered species could be identified and tracked without needing to disturb their habitats by collecting scat or visually identifying the animals. One wonders what they'd find if they had turned it on at other locations in Florida.
The method is also rapid; a lone scientist can collect and process DNA from this technique within about one day with inexpensive equipment. Many scientists around the world might be able to apply this approach to their own work.
But it does raise questions about how this tool could be applied. Sensitive human genetic data might be easy to obtain by simply suctioning up the air around certain groups or individuals. Duffy and other experts have noted that ethical rules should be established for this field, and quickly. Policymakers may also want to consider making these rules enforceable in some way.
"It seems like science fiction, but it's becoming science fact," Duffy said. "The technology is finally matching the scale of environmental problems."
