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Geneticists have isolated and decoded RNA molecules from an extinct creature for the first time long ago.
The genetic material, from a 130-year-old Tasmanian tiger, or thylacine, preserved in the collection of the Swedish Museum of Natural History in Stockholm, allowed scientists to better understand how the animal’s genes worked. The researchers shared their findings in a study published Tuesday in the scientific journal Genome Research.
“RNA gives you the ability to go through the cell, through the tissues and find the true biology that has been preserved over time for that animal, the thylacine species, right before they died,” said study lead author 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 predator. It disappeared about 2,000 years ago virtually everywhere except the Australian island state of Tasmania, where the population was driven to extinction by European settlers. The last living thylacine in captivity, named Benjamin, died of cold exposure in 1936 at Beaumaris Zoo in Hobart, Tasmania.
Mármol Sánchez said that while de-extinction is 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 to life in some form.
Resurrecting a lost species
Andrew Pask, who leads a project aiming to resurrect the thylacine, said the study was “revolutionary”.
“We had previously thought that only DNA remained in old museums and ancient specimens, but this paper shows that it is possible to obtain RNA even from tissues,” 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 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 breaks down more quickly than DNA and, until recently, was not thought to last for any length of time.
In 2019, a team sequenced RNA from the skin of a 14,300-year-old wolf preserved in permafrost, but the latest research is the first time RNA has been recovered from a now-extinct animal.
Mármol Sánchez said that this study is a proof of concept and that his colleagues now hope to recover RNA from animals that went extinct much longer ago, such as the woolly mammoth.
Recipes book
The research team was able to sequence RNA of skin and skeletal muscle tissues from the sample and identify thylacin-specific genes. This information is part of the animal’s so-called transcriptome, just as the information stored in DNA is known as the genome.
DNA is often described as an instruction manual for the life contained in each cell of the body. In addition to other cellular functions, RNA produces proteins by making a copy of a particular 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 the analogy of a city where every restaurant is provided with a huge recipe book: DNA. However, it is the RNA that allows each restaurant to produce different dishes from that reference book.
“If you just focus on DNA, you won’t be able to grasp the differences between all these restaurants,” Mármol Sánchez said. “Using RNA… now you can go to a restaurant and taste the food, taste the paella, the sushi or the rolls.”
“You can learn a lot… reading those recipes,” he added, “but you’ll miss the real pieces of the metabolism, the biology that all those restaurants or cells have between them.”
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