RNA From Museum Specimen of Tasmanian Tiger Offers Clues for De-Extinction

RNA (ribonucleic acid) is a molecule that carries genetic information and regulates gene expression in living cells.

Unlike DNA (deoxyribonucleic acid), which can be preserved for millions of years under certain conditions, RNA is more fragile and degrades rapidly after death.

Therefore, retrieving RNA from ancient or extinct organisms has been considered impossible, until now.

How did scientists recover RNA from an extinct species?

A team of researchers from the Centre for Palaeogenetics and SciLifeLab in Sweden, led by Emilio Mármol Sánchez, achieved a remarkable feat: they isolated and sequenced RNA molecules from a 130-year-old specimen of a Tasmanian tiger, or thylacine.

The thylacine was a carnivorous marsupial that went extinct in 1936 due to hunting and habitat loss. The last known individual died in captivity at the Hobart Zoo in Tasmania.

The researchers used a tissue sample from a thylacine specimen that was stored at room temperature at the Swedish Museum of Natural History in Stockholm.

They extracted RNA from both skin and muscle tissues and used advanced computational methods to filter out contamination from environmental sources, such as human or bacterial DNA or RNA.

They then reconstructed the transcriptomes of the skin and muscle cells, which are the sets of all RNA molecules expressed by a cell.

The study, published in the journal Genome Research, is the first to report the recovery of RNA from an extinct species.

It also demonstrates that RNA can survive for longer than previously thought, even in specimens that are not preserved in optimal conditions, such as freezing or desiccation.

What are the implications of recovering RNA from an extinct species?

Recovering RNA from an extinct species has several implications for paleogenomics, the study of ancient genomes.

RNA can provide more information than DNA about the biology and function of extinct organisms, as it reflects the activity and regulation of genes in different tissues and conditions.

RNA can also help fill in gaps and improve the quality of ancient DNA sequences, as it can be used to infer the original DNA sequence.

For example, the researchers identified a novel microRNA sequence that was unique to the thylacine and not found in any other marsupial.

MicroRNAs are small RNA molecules that regulate gene expression by binding to messenger RNAs and inhibiting their translation into proteins.

The discovery of this microRNA suggested that the thylacine had a distinct gene regulatory network that may have contributed to its evolution and adaptation.

Recovering RNA from an extinct species may also have implications for de-extinction, the attempt to resurrect extinct organisms using genetic engineering or cloning techniques.

RNA can help identify genes that are essential for the development and survival of extinct organisms, and potentially modify them in living relatives or surrogate hosts.

For instance, some researchers are trying to revive the thylacine by editing the genome of its closest living relative, the Tasmanian devil.

RNA from an extinct species is a breakthrough in paleogenomics that opens new possibilities for studying the biology and function of ancient and extinct organisms.