Forget fingerprints, strands of hairs and saliva swabs – scientists have now come up with a way of detecting even the smallest traces of DNA in the air.
The discovery – made independently by British and Danish researchers earlier this year – could pave the way for experts to study rare wildlife, but it could also have consequences for crime investigations as well.
It will mean that scientists can now further research animals that typically live in hard-to-reach environments, including deserts, rainforests and caves, as well as helping police investigations by revealing the DNA of any person suspected to have passed through a crime scene.
A new technique that detects DNA fragments in the air could help forensic investigations
Professor Elizabeth Clare of York University, Canada, tested out the innovative technique last December at Hamerton Zoo Park in Cambridgeshire.
The academic has previously said that the method ‘opens up some interesting questions’ about how the technology could potentially be used not only for animal research, but also in forensics.
Clare, previously at Queen Mary University in London, and her team placed sensitive filters fitted to vacuum pumps at 20 locations around the site.
Speaking to The Observer, she said: ‘We realised a zoo would be an excellent place to test a technique like this because there animals there are non-native and are spatially confined in enclosures.’
The team found 17 species of DNA fragments, including tiger, during the experiment last year
The team collected 72 samples and used polymerase chain reaction (PCR) to amplify the miniscule amounts of DNA found in the filters.
They discovered 17 species of DNA fragments, including tiger, dingo and most prolifically, black and white ruffed lemurs.
The scientists believe this was down to how active the animals were, with the lemurs shedding more DNA as a result.
The DNA of black and white lemurs was found most prolifically in the samples collected
A similar experiment was carried out by Christina Lynggaard and Kristine Bohmann of Copenhagen University with similar results.
They collated 49 species of DNA from air collected around Copenhagen Zoo.
‘We got DNA from mammals, fish, birds and reptiles, from big animals and small animals, from creatures with feathers and others with scales. We even detected the DNA of guppy fish that swim in a pond in the zoo’s tropical house.’
The equipment was so sensitive that the team even traced DNA from local wildlife, nearby pets and animals kept as feed for the zoo animals.
The latest technique means that DNA can be captured from the atmosphere to detect animals
Both teams are excited by the findings and believe it could transform how scientists study biodiversity, but first accuracy needs to improve on dating the samples.
Clare said this would be part on ongoing research into the technique, adding: ‘You might detect a piece of tiger DNA but at present we are not sure when it might have been released by the animal. It could be minutes or hours or days ago.’
The possibility of tracing human DNA has equally excited researchers into this new technology.
HOW DOES IT WORK?
DNA, or deoxyribonucleic acid, is a complex chemical in almost all organisms that carries genetic information.
It is located in chromosomes of the cell nucleus and almost every cell in a person’s body has the same DNA.
It is composed of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T).
The structure of the double-helix DNA comes from adenine binding with thymine and cytosine binding with guanine.
Scientists have now found a way of collecting DNA from the air in a room.
Air is sucked from a room and pumped through an ultra-fine filter.
The equipment is so sensitive it can detect environmental DNA (eDNA) shed by an animal or human.
eDNA could only previously be detected in water, soil and snow.
Source: US National Library of Medicine
In March, MailOnline revealed how air sucked from a room and pumped through an ultra-fine filter was able to capture DNA shed by a person’s body.
The study, published in the journal PeerJ, found naked mole-rat DNA from the air of their lab-based burrows and also the room they are housed in.
So-called ‘AirDNA’ was extracted from the filters and successfully sequenced.
Human DNA from the mole-rats’ carers was also identified by the technology, which the researchers say was a surprise, but reveals the sensitivity of the technique.
Researchers believe the human DNA was from the carers of the naked mole-rats, despite these people spending far less time in the room than the animals.
Clare, who also led this research project, said at the time: ‘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.’
She adds it ‘opens up some interesting questions’ about how the technology could be used in forensics or archaeology.
For example, studying the air of a tomb may be a way to obtain DNA samples of long-dead mummies or skeletons.
But using the technique in this way could prove tricky and advancements are still needed.
The emerging technology relies on sucking the air in a room into a filter, and this, Clare says, means it may be harder to obtain DNA from a larger room or air space.