Scientists at the University of Copenhagen have become the first to reconstruct the nuclear genome of an extinct human being. It is the first time an ancient genome has been reconstructed in detail.
The innovative technique can be applied to museum materials and ancient remains found in nature and can help reconstructing human phenotypic traits of extinct cultures from where only limited remains have been recovered. It also allows for finding those contemporary populations most closely related to extinct cultures revealing ancient human expansions and migrations. Finally, the discovery improves our understanding of heredity and the disease risk passed down from our ancestors.
The spectacular results of the research are being published in the journal Nature.
Professor Eske Willerslev and his PhD student Morten Rasmussen, from Centre of Excellence in GeoGenetics at the Natural History Museum, University of Copenhagen, Denmark, led the international team of scientists responsible for the findings.
Professor Willerslev, 38, and his team grabbed international attention last year when they reconstructed the complete mitochondrial genomes of a woolly mammoth and an ancient human. However, the current discovery is the first time scientists have been able to reconstruct the 80% of the nuclear genome that is possible to retrieve from fossil remains. From the genomic sequences, the team has managed to construct a picture of a male individual who lived in Greenland 4,000 years ago and belonged to the first culture to settle in the New World Arctic.
The discovery was made by analysing a tuft of hair that belonged to a man from the Saqqaq culture from north-western Greenland 4,000 years ago. The scientists have named the ancient human “Inuk,” which means “man” or “human” in Greenlandic. Although Inuk is more closely related to contemporary north-eastern Siberian tribes than to modern Inuits of the present day New World Arctic, the scientists wants to acknowledge that the discovery was made in Greenland.
Professor Willerslev discovered the existence of the hair tuft by coincidence after several unsuccessful attempts to find early human remains in Greenland.
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The technique for making recombinant DNA was first developed in the early-1970s by Herbert Boyer and Stanley Norman Cohen. Their original paper described a method to use recombinant DNA to create transgenic bacteria. Their work was built on the work of Daniel Nathans, Hamilton Smith, and Werner Arber, who discovered restriction endonucleases. In 1978 the three were awarded the Nobel Prize for Medicine for this discovery.
The use of cloning is interrelated with Recombinant DNA in classical biology, as the term “clone” refers to a cell or organism derived from a parental organism, with modern biology referring to the term as a collection of cells derived from the same cell that remain identical.
At its most basic, recombinant DNA is just putting strands of DNA together that wouldn’t otherwise appear together. These could simply be multiple strands of cloned DNA from the same organism, combined to create something new or different. Usually, however, in the popular mind recombinant DNA is used to refer to so-called chimeric plasmids. These are DNA molecules which contain strands from multiple animals, named after the mythological creature which contained various animal parts.
Once these plasmids have been created, they are introduced to an organism through a vehicle. The most common vehicles for recombinant DNA are the E. coli bacteria and subsequent derivatives. Once introduced, these plasmids replicate and can make actual changes in the organism itself manifest.