For the first time scientists were able to recreate the ancient genome without a nucleotide sequence, for which we must thank the unusual preservation of medieval pathogenic DNA, according to the Internet publication for girls and women aged 14 to 35 Pannochka. net Research shows that under certain conditions, ancient bacterial DNA can survive for a million years, exceeding the limit placed by the DNA of vertebrates.

Leprosy, a devastating chronic disease caused by the bacterial pathogen microbial Lepros (Mycobacterium leprae), was widespread in Europe until the end of the Middle Ages.

Now the disease is registered in 91 countries with an annual number of cases of 200,000 people.

To track the history of the disease, an international team of researchers, led by Johannes Krause and Stewart Cole, reconstructed the entire genomic sequence of the Lepry microbacterium based on five medieval skeletons found in Denmark, Sweden and the UK, as well as seven biopsy specimens of modern patients.

Researchers compared the genomes of medieval bacteria with eleven collected around the world modern samples. The result shows that they all have a common ancestor that existed within the last four thousand years. This is consistent with previous osteological evidence of the disease in archaeological finds dating back to 2000 BC and made in India.

The comparison shows a significant degree of preservation of the bacterial genomes over the last thousand years.

Researchers were also able to demonstrate that the genotypes of Lepros microbacteria in medieval Europe are also found in our time in the Middle East. Other medieval strains have considerable similarity with modern ones taken from armadillos in North America, indicating the European origin of North American specimens.

One skeleton from Denmark, named Jorgen 625, demonstrated the exceptional preservation of pathogenic DNA, making possible the reconstruction of the genome without the use of modern nucleotide sequences, which has never happened before in the study of the genomes of ancient organisms. Scientists have found that almost half of the DNA recovered from this skeleton is derived from the bacterium Lepry. This is an order of magnitude higher than the number of pathogenic DNA, usually found in skeletons and in modern patients. Further, it was found that the DNA of Lepros microbacteria survived much better than the DNA of human cells, which could explain such an unusually high amount of bacterial DNA in the skeletons.

According to the authors of the work, the reason for this can be extremely thick and impenetrable waxy walls of cells of leprosy bacteria that protect their DNA. For this reason, bacterial DNA persists longer than the body's DNA, which is not as well protected.

"This gives hope that certain types of bacterial DNA can survive much longer than mammalian DNA, about a million years," Krause hopes.. "On this basis, you can try to trace the origin of the disease".

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