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RNA – transcripts of short-lived genes – of the "Tumat puppy", a wolf of the Pleistocene epoch was isolated and its sequence badyzed in a new study by Oliver Smith of the University of Copenhagen and colleagues publishing in July 30 in the open access journal PLOS Biology. The results establish the possibility of examining a range of RNA transcripts from ancient organisms, a possibility previously thought to be extremely unlikely due to the short life span of RNA.
DNA, which encodes the "hard copy" genes, is known to survive for thousands of years under favorable conditions. But the RNA – the ephemeral working copy of a gene, which is transcribed from the DNA in the cell and constitutes the instructions for the making of proteins – is quickly broken down in living tissues by a suite of recycling enzymes. This instability usually persists after death and because of this, researchers have generally badumed that the probability of finding intact the RNA complement of an old cell, its transcriptome, was extremely low. There were, however, some exceptions, mainly in plants, which led the authors to wonder whether there were any animal transcriptomes that were sufficiently preserved to be sequenced.
They isolated and badyzed the liver tissue RNA from a 14,300-year-old canine, possibly a wolf or a creature similar to a partially domesticated wolf, which had been preserved in Siberian permafrost up to the age of 15 years. at his discovery, as well as fabrics from both 19th and 20th centuries. wolves of the century for comparison. Using various transcriptomic techniques and quality control measures, the team has shown that Pleistocene canid sequenced RNA is truly representative of the animal's RNA, with many liver-specific transcripts corresponding to specific samples. more modern wolves and dogs.
The transcriptome of Siberian canine is the oldest sequenced RNA by far, at least 13 000 years older than the oldest transcriptome. The authors note that, unlike paleo-genomics, it is unlikely that paleo-transcriptomics will become a routine, because even under the best of conditions, RNA is not as well preserved as it is in the past. ; DNA.
Nevertheless, there are probably a large number of other naturally frozen specimens for which the decoding of the transcriptome is possible, which opens up to researchers not only the genes of ancient organisms, but also the flow of activity cell encoded by the transcriptome.
"Ancient DNA researchers previously hesitated to sequence old RNA because it is generally more unstable than DNA and more subject to enzymatic degradation," said Dr. Smith. "However, as a result of our recent successes in sequencing old RNA from plant material, we have badumed that a well-preserved animal specimen, frozen in permafrost, could retain enough material to sequence." To our delight, we discovered that RNA from various tissues, but in some cases the signal was so strong that we could distinguish between tissues in a way that has a biological meaning.
"Knowing that RNA plays the role of an intermediary between DNA and proteins, which are both more stable, it might be tempting to ask," So what? "But we believe that the future of ancient RNA has great potential.Nowadays, the most clinically relevant viruses have RNA genomes, and the stage of the RNA genome. RNA is often crucial to understanding the intricacies and complexities of gene regulation.This could have repercussions when we discuss environmental stresses and strains that cause evolution. "
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