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Basis of the current analysis: a dead Tasmanian tiger from a Swedish museum

Photo: Emilio Mármol Sánchez (photograph) / Panagiotis Kalogeropoulos (editing)

In Australia in the 19th century, there was a dollar bounty for every adult Tasmanian tiger killed, also known as a thylacine. During European colonization, the species was declared an agricultural pest there. As a result of hunting, the animals became extinct. The last known living Tasmanian tiger died in captivity at a zoo in Hobart, Tasmania in 1936.

Now, with the help of a specimen from a Swedish museum, researchers have succeeded in isolating and examining RNA molecules that are more than a hundred years old. For the first time, a team writes in a study in the journal Genome Research, it has been possible to reconstruct such information from an extinct species. So could the Tasmanian tiger soon be "revived"?

The experiment is worthwhile, the researchers write. The Tasmanian tiger (Thylacine) was a carnivorous marsupial that was distributed across the Australian continent and the island of Tasmania during its lifetime. Its former habitat is still largely preserved in Tasmania. He was out of ecological balance, the thylacine could possibly fix it.

»Reviving the Tasmanian tiger is not a trivial task«

In order to retrieve extinct animals, it is necessary to know which genes were active in which area of the body and how these genes were regulated – information that is only contained in RNA, DNA alone does not provide a complete picture of genetic information. In previous studies, scientists have already shown that RNA can be extracted from old animals preserved in permafrost, for example; however, no experiments have been made on extinct species so far, writes the team of the current publication.

For some scientists around the world, reviving extinct species is a major goal. But the project is difficult – regardless of whether it is a woolly rhinoceros, woolly mammoth or the thylacine. "The revival of the Tasmanian tiger is not a trivial task and requires a comprehensive knowledge of both the genome and the transcriptome regulation of such famous species, which is only now emerging," said Emilio Mármol, lead author of the study, according to a statement. Transcriptome refers to the sum of all RNA molecules produced in a cell.

The subject of the current research was a 130-year-old, dried Tasmanian tiger that was kept at room temperature at the Swedish Museum of Natural History in Stockholm. The researchers took the skeletal muscle tissue from the inside of the left shoulder blade, the skin tissue from three different sections, including the groin area, according to the study. The quality of the RNA information that the scientists were able to obtain was good despite the age.

It's better not to let it die out in the first place

The technique used for the study could also be helpful in other areas. "In the future, we could extract RNA not only from extinct animals, but also RNA viral genomes such as Sars-CoV-2 and their evolutionary precursors from the skins of bats and other host organisms stored in museum collections," said Love Dalén of Stockholm University.

Activists have criticised plans to revive extinct species. Rather, the causes of species extinction should be addressed, the overexploitation of nature and increased global warming.

Ani