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Scientists in Sweden recovered RNA from an extinct, 130-year-old Tasmanian tiger, also known as a thylacine. They then traced which genes were active in its tissues.
DNA can show what genes exist, but gene expression, which genes are active in a tissue, needs RNA in living cells.
The study was led by Dr. Marc R. Friedländer at Stockholm University in Sweden, with support from nearby research centers.
His work focuses on RNA biology and gene regulation in cells, especially the tiny regulators that shape development.
RNA usually breaks apart faster than DNA, so most old samples lose their transcriptome, the full set of RNA messages from those tissues.
Dry storage can slow the chemical reactions that chew up RNA, and museum skins sometimes hold more than expected.
A 2019 paper showed RNA can survive in permafrost and old wolf skins long enough to retain tissue signals.
Thylacine, RNA, and tissue
The thylacine was a marsupial predator with a pouch that vanished after intense hunting and habitat loss.
On September 7, 1936, the last known thylacine died at Beaumaris Zoo in Hobart, according to the National Museum of Australia record.
That specimen sat dried at room temperature in a Swedish museum, and it provided skin and muscle tissue for sequencing.
To avoid modern contamination, the team worked in clean rooms built for ancient molecules and tracked possible human handling.
Proving the RNA was from a thylacine
How could anyone be sure this RNA came from a thylacine and not from a modern contaminant?
Most reads matched the thylacine genome, and human sequences appeared at lower levels that fit typical museum handling.
They also used metatranscriptomics, which is a way of scanning all RNA to identify species and microbes, to separate thylacine fragments from contaminants.
Chemical scars, called deamination, damage that changes one RNA letter into another, rose near fragment ends as expected.
Reading gene activity in muscle
In muscle, the strongest signals came from genes tied to contraction and energy use, including the huge protein titin.
The RNA profile pointed to slow muscle fibers, which fit the location where researchers took tissue from near the shoulder blade.
They also detected messages involved in oxygen storage and fuel recycling, hints about how those cells worked when alive.
Even with millions of fragments, the team captured only a small slice of the full muscle transcriptome, so rare signals stayed quiet.
RNA and thylacine skin samples
Skin samples carried many RNA fragments from keratin genes, matching the tough outer layer that protects animals from wear.
Two skin sections also contained hemoglobin RNA, a sign of blood left in the tissue when the specimen was prepared.
Because skin sits on the outside, it can pick up microbes later, yet thylacine reads still dominated the data.
When the team compared these profiles with living marsupials and dogs, skin looked like skin and muscle looked like muscle.
MicroRNAs: The small regulators
MicroRNAs, short RNAs that tune how much protein a gene makes, often run about 22 building blocks long.
RNA evidence also confirmed a thylacine-specific microRNA form, showing how gene regulation can differ even between close relatives.
These small regulators varied sharply between skin and muscle, giving another check that the sequences came from the right tissues.
Fixing the thylacine genome map
Scientists use annotation, labeling genes on a genome map, to turn raw DNA into a usable reference for biology.
Because RNA comes from finished messages, it can expose missing exons and patch gaps that confuse DNA-only gene lists.
In the thylacine, RNA data pointed to the likely location of ribosomal RNA genes that were absent from earlier assemblies.
A better genome map helps researchers compare extinct animals with living ones, and it also reduces false signals in future studies.
Tracing old viruses in dead tissue
The team also detected traces of RNA viruses, viruses that store their genes as RNA, in the thylacine material.
Those signals were thin, and the authors urged caution, yet the result hints that museum specimens might preserve viral history.
If future work confirms these hints, researchers could compare related viruses across time and track how they changed.
That kind of work demands careful lab controls, because modern viral RNA can sneak in through reagents or human contact.
Lessons from thylacine RNA
This work pushes paleotranscriptomics, studying ancient RNA to learn past gene activity, beyond permafrost and into dry museum drawers.
RNA profiles can reveal cell types, damage, and even signs of disease, giving extinct species a more detailed record.
Different preservatives may change what survives, so curators and scientists will need shared rules for sampling without ruining specimens.
The study drew on one preserved animal, so it cannot capture variation across age, season, health, or life history.
RNA fragments were short and uneven, which makes it hard to measure low-level genes or rebuild complete messages.
Short fragments can map to many genomes, so reference databases can mislabel reads unless teams apply strict filters.
More samples from other extinct animals, paired with DNA and protein work, should show how widely this approach can scale.
The study is published in Genome Research.
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