Scientists have successfully extracted DNA from insects trapped in amber. But before you start dreaming of a certain park, there’s one huge caveat to mention – any creatures you might revive from this would hail from the not-so-distant past of about 2014. Rather than resurrecting the dinosaurs, the study is more about working backwards to figure out the limits of DNA preservation.
Jurassic Park made it seem like amber – fossilized tree resin – was a surefire way to preserve ancient DNA. Just stick a needle in, suck the blood out of a trapped mosquito or tick, and bingo – dino DNA. Patch up the holes with frog DNA and you’ve got all the makings of a dinosaur zoo doomed to collapse.
But of course, real life doesn’t quite work like that. There’s ongoing scientific debate about just how long DNA can last in various forms. Controversial studies claim to have detected DNA in 75-million-year-old dinosaur fossils, but all too often these later turn out to be contamination from much more recent samples.
Amber may seem like a more viable preservation method, since it’s able to preserve soft tissues like feathers, skin, and even blood cells. In the 1990s reports were made of ancient insect DNA being retrieved from amber dating back tens of millions of years, but these exciting discoveries were unable to be reproduced in later studies, leading the overall scientific community to dismiss the original findings.
So for the new study, a team of scientists led by the University of Bonn set out to find just how long DNA could be preserved. But rather than starting with the extremely old samples, they worked backwards from the youngest samples of hardened tree resin which hasn’t even had the time to become amber.
“Instead of looking for DNA in amber of 100 million years old or more, to dream about the resurrection of dinosaurs, we should start by detecting it in insects trapped a few years ago in resin,” says David Peris, lead author of the study. "Our new results show that it is indeed possible to genetically study organisms that were embedded in resin, although we do not know the time limit yet.”
The team worked with two pieces of resin from Madagascar, which are just two and six years old. They obtained samples from ambrosia beetles trapped inside, then used a variation of a technique called polymerase chain reaction. This method allows scientists to multiply the amount of genetic material to a level where it can be identified, and it’s commonly used in forensics to match DNA samples to suspects, or in tests for viruses such as SARS-CoV-2. And sure enough, the researchers were able to extract DNA from the beetles.
“This method allowed us to perform several authenticity checks, so that we could say certain that the detected DNA in our experiments was indeed from the beetles preserved in the resin,” says Kathrin Janssen, second lead author of the study.
Interestingly, the team found that water lasts longer in the resin-encased insects than was previously thought. That’s bad news for DNA’s chances of long-term preservation though, since water speeds up the degradation.
Now that the team has found that it is technically possible to extract DNA from resin, the next steps are to analyze gradually older samples, using more sensitive sequencing methods, to determine just how long DNA could last. After all, there’s quite a window between two years and 100 million.
The research was published in the journal PLOS ONE.
Source: University of Bonn