By Will Dunham
(Reuters) – The Tasmanian tiger, a dog-sized striped carnivorous marsupial also called a thylacine, once roamed the Australian mainland and adjacent islands, an apex predator that hunted kangaroos and other prey. Because of man, the species is now extinct.
But that doesn’t mean scientists have stopped learning more. In a scientific first, researchers announced Tuesday that they had recovered RNA – genetic material found in all living cells that has structural similarities to DNA – from the desiccated skin and muscles of a tiger. Tasmania stored since 1891 in a museum in Stockholm.
In recent years, scientists have extracted DNA from ancient animals and plants, some of which are more than 2 million years old. But this study marked the first time that RNA – much less stable than DNA – had been recovered from an extinct species.
Although this is not the focus of this research, the ability to extract, sequence and analyze old RNA could boost other scientists’ efforts to recreate extinct species. Recovering RNA from ancient viruses could also help decipher the cause of past pandemics.
DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) – biomolecular cousins – are fundamental molecules in cell biology.
DNA is a double-stranded molecule that contains an organism’s genetic code, carrying the genes that give rise to all living things. RNA is a single-stranded molecule that carries the genetic information it receives from DNA, thereby putting this information into practice. RNA synthesizes the array of proteins an organism needs to live and acts to regulate cellular metabolism.
“RNA sequencing gives you a taste of the true regulation of biology and metabolism that was occurring in the cells and tissues of Tasmanian tigers before they went extinct,” said geneticist and bioinformatician Emilio Mármol Sánchez from the Center for Paleogenetics and SciLifeLab in Sweden, lead author of the study published in the journal Genome Research.
“If we want to understand extinct species, we need to understand what genetic complements they had, as well as what these genes did and which were active,” said geneticist and study co-author Marc Friedländer from the University from Stockholm and SciLifeLab.
Questions arose about how long RNA could survive in the kind of conditions — room temperature in a cabinet — in which these remains had been stored. The remains at the Swedish Museum of Natural History were in a state of semi-mummification, with skin, muscles and bones preserved but internal organs lost.
“Most researchers thought that RNA would survive only a very short time – such as days or weeks – at room temperature. This is probably true when the samples are wet, but apparently not when they are dried,” he said. declared the evolutionary geneticist. Love Dalén from the Paleogenetics Center.
The Tasmanian tiger looked like a wolf, except for the tiger-like stripes on its back. The arrival of humans in Australia around 50,000 years ago led to massive population losses. The arrival of European colonizers in the 18th century sounded the death knell for the remaining populations concentrated on the island of Tasmania, who were then placed on a price after being declared dangerous to livestock. The last known Tasmanian tiger died in a Tasmanian zoo in 1936.
“The story of the thylacine’s disappearance is in one sense one of the best-documented and most proven human-caused extinction events. Unfortunately, Tasmanian tigers were declared protected only two months before the last known individual dies in captivity, too late to save them from extinction,” Mármol said.
Private “de-extinction” initiatives have been launched aimed at resurrecting certain extinct species such as the Tasmanian tiger, the dodo or the woolly mammoth.
“While we remain skeptical that it is possible to actually recreate an extinct species using gene editing on living animal relatives – and the time needed to reach an end point might be underestimated – we advocate for more research on the biology of these extinct animals,” said Mármol.
(Reporting by Will Dunham in Washington, Editing by Rosalba O’Brien)