A crucial discovery for biodiversity: DNA fragments are available in the ambient air

This is a discovery that could allow monitoring of life on an unprecedented scale. One million species are now endangered According to a UN report, "one of the biggest problems facing the planet today is the accelerated loss of biodiversity," says Elizabeth Clare, assistant professor at York University in Toronto. His team has recently been working on the possibility of studying owls, hedgehogs, fungi, etc. from minute traces of DNA in the air. The paper, of which she is a signatory, was published in "Current Biology" on Monday, June 5.

More than 180 species of plants and animals already identified

The principle is simple, living beings disperse fragments of their DNA in several forms (hair, pollen, secretions ...), this is called environmental DNA (eDNA). Well known to researchers, this eDNA can be taken from environments (river, soil, tree moss) and analyzed to identify diversity. These samples are previously carried out on a small scale, and make it possible to study the populations of very localized areas.

The York University researchers' good idea was to analyze the filters of air pollution measuring stations. This new tool paves the way for a large-scale study. For the article, the researchers placed their tag in London and Scotland. "By testing just two locations, we found evidence of environmental DNA for more than 180 different plants and animals," says Clare.

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"Almost every country has an air pollution monitoring system or network," says Joanne Littlefair of Queen Mary University of London, UK, lead author of the paper. Thousands of stations around the world are therefore capturing, for the moment without processing data, on biodiversity. This is good news for research. "We will get in touch with the researchers to discuss the technical aspects. This strategy is of particular interest to us," explains Antoine Trouche, an engineer at Airparif, the Île-de-France air quality monitoring network, which plans to deploy it by 2030.

For this, it will first be necessary to specify certain variables, such as the rate of degradation of eDNA once filtered. Antoine Trouche is enthusiastic "There are about fifty air measuring stations in Île-de-France, and just as many in each region. We could potentially study the biodiversity of the entire French territory, including overseas. »

Our self-service DNA?

In a study, published on May 15, 2023 in "Nature ecology & evolution", David Buffy raised several ethical questions raised by these human eDNA captures. A professor at the University of Florida, he cautions, "Society and regulators need to decide what to do with retrieved human genetic information and where to use it." He mentions in particular the issues of confidentiality, the risks of hacking of genetic data, and the lack of prior consent, since it is impossible to know in advance from whom the DNA will be retrieved.

So is our DNA available for self-service? Yes and no, says Elizabeth Clare. Since humans are animals like any other, their DNA can be captured. "The method we use only looks for very small fragments of DNA. It's just enough to identify species, but nothing more." According to the researcher, the samples used do not identify the individuals present. "We could say humans were present," but nothing else.

She adds that filtering the ambient air is far from the most effective way. "Many countries continue to dump raw sewage into waterways," which theoretically allows human eDNA to be taken. Observing the ambient air would therefore not increase the risks.