A team of Swedish scientists has achieved a significant breakthrough, successfully retrieving and sequencing RNA from a 130-year-old extinct Tasmanian tiger specimen. This marks the first time researchers have recovered RNA from an extinct animal, offering unprecedented insights into the biology of a species lost to history. The discovery, detailed in the scientific journal Genome Research in September 2023, opens new avenues for genetics research and the understanding of extinct life.[indiandefencereview+3]
Unlocking Ancient Gene Activity
Ribonucleic acid, or RNA, is a molecule found in all living cells. Unlike DNA, which serves as a stable blueprint of genetic information, RNA acts as a messenger, carrying instructions from DNA to create proteins and regulate cellular functions. Scientists previously believed RNA was too fragile to survive for long periods, degrading rapidly outside of living cells. This new research challenges that assumption, demonstrating that RNA can persist for over a century in preserved specimens.[indiandefencereview+3]
The ability to study RNA from an extinct species provides a dynamic "snapshot" of which genes were active at the time of the animal's death. This goes beyond what DNA alone can reveal. DNA tells researchers what genes an animal possessed, but RNA shows how those genes were actually functioning and expressed within the animal's tissues.[indiandefencereview+2]
The Vanished Thylacine
The Tasmanian tiger, officially known as the thylacine (Thylacinus cynocephalus), was a unique carnivorous marsupial. It once roamed across mainland Australia and the island of Tasmania. Shaped like a wolf with distinctive stripes on its back, the thylacine was hunted to extinction, primarily by European settlers who viewed it as a threat to livestock. The last known thylacine died in captivity at the Beaumaris Zoo in Hobart, Tasmania, in 1936.[scitechdaily+4]
For decades, museum specimens have offered glimpses into the physical characteristics of the thylacine. However, understanding its cellular and genetic activity remained a mystery until now. This recent study utilized a specimen preserved at room temperature in the Swedish Museum of Natural History in Stockholm.[scitechdaily+3]
A Meticulous Retrieval
The Swedish research team, led by Dr. Marc R. Friedländer of Stockholm University and co-led by Professor Love Dalén, an evolutionary genomics expert from Stockholm University and the Centre for Palaeogenetics, meticulously extracted RNA. They analyzed skin and muscle samples from the 130-year-old thylacine specimen. Emilio Mármol Sánchez, a computational biologist at the Centre for Palaeogenetics and SciLifeLab in Sweden, was also a lead author on the study.[indiandefencereview+2]
Toensure the authenticity of the ancient RNA and avoid modern contamination, the scientists worked in specialized clean rooms. They adapted modern RNA extraction techniques to work with the aged and delicate samples. This careful methodology allowed them to isolate millions of authentic RNA sequences from the preserved tissues.[indiandefencereview+3]
What the RNA Revealed
The recovered RNA provided specific details about the thylacine's biology. In skin samples, researchers found many RNA fragments from keratin genes, which are essential for the tough outer layer that protects animals. Muscle tissue samples showed strong expression of genes related to contraction, including titin, and indicators of slow-twitch muscle fibers. These findings suggest the thylacine might have had adaptations for endurance, aligning with its role as a predator.[indiandefencereview+2]
The team also identified over 250 thylacine-specific microRNAs. These tiny RNA molecules play a crucial role in regulating cell functioning. Emilio Mármol Sánchez described microRNAs as "the policemen of the cell," highlighting their importance in controlling gene expression. Furthermore, the RNA data helped to refine the existing thylacine genome map, pointing to the likely location of ribosomal RNA genes that were previously absent.[indiandefencereview+1]
Broadening Scientific Horizons
This groundbreaking achievement establishes a new field called paleotranscriptomics, which focuses on exploring ancient RNA to understand lost biology. "RNA gives you the chance to go through the cell, the tissues and find the real biology that has been preserved in time for that animal, the thylacine species, right before they died," said Emilio Mármol Sánchez, a co-author of the study.[indiandefencereview]
The implications extend beyond just understanding extinct animals. The team's analysis also hinted at the presence of ancient RNA viruses within the thylacine samples. While these signals were faint and require further verification, they suggest that museum specimens could serve as reservoirs of lost virological data, allowing scientists to trace the evolution of viruses over millennia.[accuweather]
Professor Love Dalén noted the potential for future de-extinction efforts. "The ability to recover RNA from extinct species constitutes a small step (toward) maybe being able to resurrect extinct species in the future," Dalén told CBS News. While de-extinction was not the primary goal of this research, a deeper understanding of the thylacine's genetic makeup, including gene expression, is vital for such ambitious projects. Andrew Pask, a professor at the University of Melbourne leading a project to resurrect the thylacine, called the paper "groundbreaking."[indiandefencereview+2]
The Future of Paleotranscriptomics
The success in retrieving RNA from the thylacine demonstrates that even fragile genetic material can endure under certain preservation conditions. Dr. Marc Friedländer emphasized that this new technique marks a "proof of concept" because RNA is typically very transient and easily destroyed.
This pioneering study opens exciting opportunities for exploring the vast collections of specimens and tissues housed in museums worldwide. Scientistshope to recover RNA from animals that died out much longer ago, such as the woolly mammoth. This research will significantly deepen our understanding of extinct animals' biology and help build more complete extinct genomes, offering a clearer picture of life on Earth throughout history.[cbsnews+2]
