Neandertals and modern humans diverged approximately 600,000 years ago and probably did not interbreed, according to a recent analysis of the complete Neandertal mitochondrial genome sequence by scientists at the Max Planck Institute for Evolutionary Anthropology in Leipzig.
In a talk last night here at the Biology of Genomes meeting at Cold Spring Harbor Laboratory, Svante Pääbo gave an update on the Neandertal genome project that his group in Leipzig is pursuing in collaboration with Roche’s 454 Life Sciences in Branford, Conn.
So far, the researchers have sequenced approximately 70 megabases of Neandertal DNA from three different individuals, the vast majority from a 38,000-year-old male from Vindija, Croatia.
From this data, they were able to reconstruct a complete mitochondrial genome, which is 16 kilobases long and was sequenced at 35-fold coverage. At 133 positions, the genome differs from almost all modern humans.
Based on a comparison with mitochrondrial DNA from modern human populations, Pääbo concluded that Neandertals and modern humans diverged about 600,000 years ago. According to the data, it is also unlikely that the two populations interbred, although more data from the entire genome will be required to increase the certainty of this.
The Neandertal mitochrondrial genome has also enabled the researchers to assess contamination of their data with modern DNA. Pääbo mentioned that about 10 percent of the DNA library they initially sequenced – data they published in late 2006 – consisted of modern human DNA. But over the last two years, they have been guarding against contamination by generating DNA libraries in a clean room and by barcoding the Neandertal DNA.
By October of this year, Pääbo said he and his colleagues want to generate approximately 50-fold more, or 3.8 gigabases, of Neandertal sequence data, equivalent to about one-fold coverage of the entire genome.
Over the next few years, they hope to increase this coverage to about 12-fold.
From GenomeWeb Daily News
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