Acting like a natural time capsule, permafrost can perfectly preserve the prehistoric remnants of the Ice Age, including species that have fallen into extinction. For the first time, scientists have successfully recovered RNA from incredibly preserved woolly mammoths, offering fresh insights into the biology of these long-lost giants.
DNA – very, very old DNA – has previously been recovered from woolly mammoths. While DNA provides a genetic blueprint for building an organism, RNA carries copies of specific instructions from DNA to make proteins. In other words, RNA shows which genes were actively being used at a particular time.
“RNA can tell us which genes were ‘turned on’ in a given tissue around the time of death. The RNA activity is what makes different types of cells different. All cells have the same DNA, so what makes them different is which genes are activated. Therefore, recovering RNA tells us which genes were active in specific tissues, giving insight into the biology of extinct animals,” Love Dalén, professor of evolutionary genomics at Stockholm University and the Centre for Palaeogenetics, told IFLScience.
Dalén and a team from multiple research institutions studied the tissues of 10 woolly mammoths found in the permafrost of northeastern Siberia.
One of those specimens was Yuka, a juvenile mammoth unearthed in the coastal region of Oyogos Yar. Despite being almost 40,000 years old, the body is in remarkably good shape, with its muscles and wiry hair still intact.
One of Yuka’s legs, illustrating the exceptional preservation of the lower part of the leg after the skin had been removed, which enabled recovery of ancient RNA molecules.
Image credit: Valeri Plotnikov
“Yuka is one of the best-preserved mammoths ever found, and to be able to work with such material felt like a rare privilege. Normally, when we deal with Ice Age remains, the tissues are highly degraded, so just seeing recognizable muscle fibers and intact hair is impressive in itself,” added Dalén. “To recover RNA, which is one of the most fragile biological molecules, from such an old specimen was amazing and beyond what I thought possible just a few years ago.”
The RNA from Yuka was able to reveal the animal’s gene expression just hours, perhaps minutes, before it died. This revealed that the muscle was undergoing metabolic stress – possibly due to a cave lion attack just before its demise.
“This might be a reflection of Yuka escaping from predators, probably cave lions, given the signs present in its body, although it is actually not possible to accurately discern,” explained Emilio Mármol, lead author of the study, who was formerly a postdoctoral researcher at Stockholm University, but is now based at the Globe Institute in Copenhagen.
It was previously assumed that Yuka was a female based on its external anatomy. However, this recent RNA data revealed that this young individual had a Y chromosome, indicating it was male.
The researchers hope to carry out further RNA analysis on other parts of mammoths. This could open up all kinds of corridors of insight into their behavior and the world they inhabited.
“In the future, we could, for example, profile mammoth hair follicles to find which genes controlled their woolly coats. This opens a new window onto how traits evolved and functioned, and could help us understand physiological differences between extinct species and their modern relatives,” commented Dalén.
The study is published in the journal Cell.
Source Link: World's Oldest RNA Recovered From Baby Mammoth Beautifully Preserved In Permafrost For 40,000 Years
