The First RNA Recovered From an Extinct Animal

A team of paleogeneticists is a winner of the 2024 Gizmodo Science Fair for recovering RNA from a museum specimen of a thylacine, the extinct marsupial popularly known as the Tasmanian tiger.

The question

Can ribonucleic acid (RNA) be recovered from an extinct animal? Sequencing the DNA of extinct species and long-dead individuals is regular practice nowadays, thanks to decades of work on ancient DNA and the birth of modern paleogenomics. But paleogenomics hasn’t devoted as much attention to single-stranded RNA, which regulates genes, carries information necessary for making proteins, and catalyzes chemical reactions in cells, among other things.

The results

The team managed to recover RNA from a 130-year-old specimen of thylacine, a species last seen alive in 1936. The findings have implications for several scientific disciplines, including gene-editing technologies and in-vitro fertilization.

“We knew from a few previous studies that, under certain preservation conditions (i.e. permafrost, desiccation, or chemical conservation), not only DNA but also RNA is indeed still present in very old animal remains,” said Emilio Mármol-Sánchez, a paleogeneticist at Stockholm University and the Centre for Paleogenetics in Stockholm and the study’s lead author. “This is the first time that we have been able to catch a glimpse of the actual biology and metabolism of Tasmanian tiger cells right before they died.”

Why they did it

“Marc Friedländer (who is an RNA specialist) and I had been talking about trying to get RNA from ancient/historical samples,” said Love Dalén, an evolutionary geneticist at the Swedish Museum of Natural History and co-author of the paper describing the findings. “The reason we tried the thylacine was partly that we wanted to try a species where getting RNA would really matter, due to that there is no closely related living relative one could use.”

The thylacine was a carnivorous marsupial about the size of a dog. It also looked like one, except for the distinctive black stripes on its rump and despite it being more closely related to the mouse-like dunnart. By the early 19th century, the Tasmanian public made the thylacine a scapegoat for dead livestock, despite evidence that mismanagement and feral dogs were more responsible. A government-issued bounty on the animals lasted from 1888 until 1909. Approximately 5,000 thylacines lived on Tasmania when Europeans arrived, according to The Australian Museum, and about 3,500 were killed between 1830 and 1920. The last known thylacine died in a zoo in 1936 due to suspected neglect.

“This is the first study to show that we can get RNA from old and dried tissues,” Dalén added. “This is important, since natural history museums around the world are full of such samples, so there is great potential for another work, including on historical RNA viruses.”

Besides it being a first for the field, recovering the RNA helped the team understand how future work could build on their methods. “The process of developing the pipeline, both in the laboratory and the bioinformatics computationally was difficult,” Mármol-Sánchez said. “There were many trials and errors. But eventually we said the thylacine is more or less the low-hanging fruit we have now.”

Why they’re a winner

It will take some time for RNA recovery to get up to speed with DNA recovery, a more proven practice. But the ability to recover strands from extinct and perhaps even ancient organisms will help scientists understand fundamental biological processes, like how genes were regulated and expressed in long-gone organisms. The technique could even be applied to things that are not truly living—specifically, viruses. Improving our understanding of RNA virus genomes could help scientists reduce the risks posed by these pathogens.

There were “highs and lows on a daily basis,” Mármol-Sánchez said. “You get very, very excited one day, and then the next day you think you are the worst because you have gone down a path where what you thought you saw is not real, or whatever. It’s not until the end that you more or less decode what is going on.”

What’s next

Besides better understanding the biology of extinct animals, some believe RNA recovery in an extinct species could lend itself to de-extinction, or the creation of proxy species for extinct animals. In 20222, “de-extinction company” Colossal Biosciences announced plans to attempt to bring back the Tasmanian tiger; earlier this year, Colossal’s chief science officer talked with Gizmodo about what it will take to make proxy species a reality.

Next up for the team? A woolly mammoth. “We are working on extracting, analyzing, and getting some biology out of mammoth tissues that have been recovered from the permafrost,” Mármol-Sánchez said.

The team

Emilio Mármol-Sánchez, Bastian Fromm, Nikolay Oskolkov, Zoé Pochon, Panagiotis Kalogeropoulos, Eli Eriksson, Inna Biryukova, Vaishnovi Sekar, Erik Ersmark, Björn Andersson, Love Dalén, Marc R. Friedländer

Click here to see all of the winners of the 2024 Gizmodo Science Fair.