Emilio Marmol Sanchez
Researchers took tissue samples from a 130-year-old Tasmanian tiger specimen stored at room temperature at the Swedish Museum of Natural History in Stockholm.
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Geneticists have for the first time isolated and decoded RNA molecules from a creature that died out a long time ago.
The genetic material – which came from a 130-year-old Tasmanian tiger, or thylacine, specimen in the collection of the Swedish Museum of Natural History in Stockholm – has enabled scientists to better understand how the animal’s genes worked. The researchers shared their findings in a study published Tuesday in the journal Science Genome research.
“RNA gives you the chance to go through the cell, the tissues and find the real biology that has been preserved in time for that animal, the thylacine species, right before they died,” said lead author of the study Emilio Mármol Sánchez, a computational biologist. at the Center for Paleogenetics and SciLifeLab in Sweden.
About the size of a coyote, the thylacine was a marsupial. It disappeared around 2,000 years ago virtually everywhere except the Australian island state of Tasmania, where the population was hunted to extinction by European settlers. The last captive thylacine, named Benjamin, died of exposure in 1936 at Beaumaris Zoo in Hobart, Tasmania.
Mármol Sánchez said that while extinction was not the goal of his team’s research, a better understanding of the Tasmanian tiger’s genetic makeup could help recently launched efforts to bring the animal back in some form.
Andrew Pask, there leads a project aimed at reviving the thylacine, said the paper was “groundbreaking”.
“We had previously thought that only DNA was left in old museums and old samples, but this paper shows that you can also get RNA from tissue,” said Pask, a professor at the University of Melbourne in Australia and head of the Thylacine Integrated Genetic Restoration Research Lab.
“This will add significant depth to our understanding of the biology of extinct animals and help us build much better extinct genomes,” he added.
Ancient DNA, under the right conditions, can last for more than a million years and has revolutionized scientists’ understanding of the past.
RNA, a temporary copy of a section of DNA, is more fragile and degrades more quickly than DNA and, until very recently, was not thought to last for long.
In 2019 a team sequenced RNA from the skin of a 14,300-year-old wolf that was preserved in permafrost, but the latest research is the first time that RNA has been obtained from an animal that is now extinct.
Mármol Sánchez said this study is a proof of concept, and his colleagues now hope to recover RNA from animals that died out much longer ago, such as the woolly mammoth.
The research team was able to sequence RNA from skin and skeletal muscle tissue from the specimen and identify thylacine-specific genes. This information is part of what is known as the animal’s transcriptome, just as the information stored in DNA is known as a genome.
DNA is often described as an instruction manual for life contained in each of the body’s cells. In addition to other cellular functions, RNA produces proteins by making a copy of a specific stretch of DNA in a process known as transcription.
Understanding RNA allows scientists to piece together a more complete picture of an animal’s biology, Mármol Sánchez said. He uses an analogy of a city where every restaurant gets one huge recipe book – the DNA. But it is RNA that allows each restaurant to produce different dishes from that reference book.
“If you just focus on the DNA, you won’t be able to capture differences between all these restaurants,” said Mármol Sánchez. “Using RNA … you can now go to the restaurant and taste the food, taste the paella, the sushi or the sandwiches.”
“You can learn a lot … by reading those recipes,” he added, “but you’re going to miss the real pieces of metabolism, biology, that all these restaurants or cells have between them.”