Scientists in Sweden have successfully recovered RNA from an extinct Tasmanian tiger, also known as a thylacine, that has been preserved for 130 years. This groundbreaking study allowed researchers to analyze which genes were active in its tissues. While DNA can reveal the presence of genes, understanding gene expression requires RNA, which is typically found in living cells. The research was conducted under the leadership of Dr. Marc R. Friedländer at Stockholm University, with support from nearby institutes focusing on RNA biology and genetic regulation in cells.
RNA tends to degrade faster than DNA over time, leading to the loss of the transcriptome, or the complete profile of RNA messages from tissues. However, storing samples in dry conditions can slow down the chemical breakdown, meaning preserved specimens in museums may contain more viable RNA than expected. A 2019 study highlighted RNA’s ability to survive in permafrost and older wolf skins long enough to retain meaningful tissue signals.
The thylacine, a marsupial predator with a pouch, faced extinction primarily due to overhunting and habitat destruction. The last known thylacine died at Beaumaris Zoo in Hobart on September 7, 1936, according to records from the National Museum of Australia. The dried specimen provided skin and muscle tissues that were vital for the sequencing process. To prevent contamination from modern sources, researchers conducted their work in specially designed clean rooms and carefully monitored human interaction with the samples.
To ensure the RNA isolated was genuinely from a thylacine rather than contamination, the majority of the genetic readings matched the known genome of the species, with incidental human sequences detected at expected lower levels, consistent with museum handling. The team also applied metatranscriptomics, a method for scanning all RNA present, to effectively differentiate thylacine fragments from contaminants. They identified chemical markers indicating age-related damage to the RNA, supporting their findings.
In the muscle tissue, researchers observed strong gene activity signals associated with contraction and energy metabolism, including those for the large protein titin. The RNA profile suggested the presence of slow muscle fibers, correlating with the tissue samples taken from near the shoulder blade. Additionally, they noted the presence of RNA messages involved in oxygen storage and metabolic recycling, providing insights into the animal’s physiological function when it was alive.
Skin samples yielded a high number of RNA fragments from keratin genes, which correspond to the protective outer layer of the thylacine. Some skin samples also contained hemoglobin RNA, indicating the presence of blood when the specimen was processed. Despite the potential for later microbial contamination, the majority of the RNA data remained consistent with thylacine profiles. Comparative analyses showed distinct differences: skin RNA matched that of other marsupials, while muscle RNA was similarly aligned with expected patterns.
Moreover, the study confirmed the existence of thylacine-specific microRNAs, short RNA molecules that regulate protein production, showcasing how gene regulation can differ even among closely related species. These regulators varied notably between skin and muscle, further validating the tissue origin of the sequences.
The research advances our understanding of paleotranscriptomics, the study of ancient RNA to learn about past gene expression. RNA profiles can reveal information about cell types, cellular damage, and potential disease indicators, enriching our knowledge of extinct species. The study underscores the importance of careful preservation methods, as different techniques may affect what genetic material remains viable for analysis.
This investigation focused on a single preserved thylacine, limiting its ability to capture variations related to age, seasonal changes, health, or life history. The short and fragmented nature of the RNA also complicates the extraction of complete genetic information, challenging overall interpretations. Moving forward, additional samples from other extinct species, along with DNA and protein analyses, could demonstrate the scalability of these findings. The comprehensive study has been published in Genome Research.
Original Source: https://www.earth.com/news/scientists-uncover-rna-from-extinct-animal-for-first-time-pr25/
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Publish Date: 2025-12-30 03:54:00
