Scientists recover RNA from an extinct species for the first time

Scientists recover RNA from an extinct species for the first time
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Washington, US: A new study demonstrated the isolation and sequencing of RNA molecules from a Tasmanian tiger specimen kept at room temperature in a museum collection over a century ago.

For the first time, skin and skeletal muscle transcriptomes from an extinct species were reconstructed. The researchers emphasise that their findings have ramifications for international efforts to restore extinct animals, such as the Tasmanian tiger and the woolly mammoth, as well as studies into pandemic RNA viruses.

The Tasmanian tiger, commonly known as the thylacine, was a magnificent apex carnivorous marsupial that formerly roamed the Australian continent and Tasmania. This unusual species met its end following European colonisation, when it was considered an agricultural pest and a bounty of £1 was imposed by 1888 for each full-grown animal slain. The last known surviving Tasmanian tiger died in captivity in 1936 at Hobart's Beaumaris Zoo.

Recent de-extinction attempts have concentrated on the Tasmanian tiger, whose native habitat in Tasmania is still mostly maintained, and whose restoration could assist in restoring past environmental equilibriums lost following its extinction. However, rebuilding a functional living Tasmanian tiger requires not only a thorough understanding of its genome (DNA), but also of tissue-specific gene expression dynamics and gene control, which can only be obtained by researching its transcriptome (RNA).

“Resurrecting the Tasmanian tiger or the woolly mammoth is not a trivial task, and will require a deep knowledge of both the genome and transcriptome regulation of such renowned species, something that only now is starting to be revealed”, said Emilio Mármol, the lead author of a study recently published in the Genome Research journal by researchers at SciLifeLab in collaboration with the Centre for Palaeogenetics*, a joint venture between the Swedish Museum of Natural History and Stockholm University.

The researchers behind this study have sequenced, for the first time, the transcriptome of the skin and skeletal muscle tissues from a 130-year-old desiccated Tasmanian tiger specimen preserved at room temperature in the Swedish Museum of Natural History in Stockholm.

This led to the identification of tissue-specific gene expression signatures that resemble those from living extant marsupial and placental mammals.

The recovered transcriptomes were of such good quality that it was possible to identify muscle- and skin-specific protein-coding RNAs, and this led to the annotation of missing ribosomal RNA and microRNA genes, the latter following MirGeneDB recommendations.

“This is the first time that we have had a glimpse into the existence of thylacine-specific regulatory genes, such as microRNAs, that got extinct more than one century ago”, said Marc R. Friedländer, Associate Professor at the Department of Molecular Biosciences, The Wenner-Gren Institute at Stockholm University and SciLifeLab.

This pioneering study opens up new exciting opportunities and implications for exploring the vast collections of specimens and tissues stored at museums across the globe, where RNA molecules might await to be uncovered and sequenced.

“In the future, we may be able to recover RNA not only from extinct animals but also RNA virus genomes such as SARS-CoV2 and their evolutionary precursors from the skins of bats and other host organisms held in museum collections”, said Love Dalén, Professor of evolutionary genomics at Stockholm University and the Centre for Palaeogenetics.