Since the findings reported in this Science paper suggest that only about 0.5-percent of Neanderthal genome differs from the human genome, focusing scientific attention on those sequences promises to be more efficient and cost-effective than trying to directly sequence the entire Neanderthal genome. Also, the metagenomic library approach enables scientists to obtain specific sequences from multiple Neanderthal specimens precisely and without having to generate lots of random sequences.
For the results reported in their Science paper, Rubin and Noonan and their colleagues extracted all the DNA in the femur bone of a 38,000-year-old male Neanderthal specimen from Vindija, Croatia. Using a combination of the sequencing technologies deployed in the Human Genome Project, plus a new massively parallel pyrosequencing technology, in which enormous amounts of DNA sequence is rapidly and inexpensively generated, they were able to recover 65,250 base pairs of Neanderthal DNA from the approximately 6 million base pairs of contaminating DNA in the fossil. A critical factor in helping to confirm that the recovered DNA was Neanderthal rather than human was the short length of the individual Neanderthal sequences.
Said Rubin, "We determined that the ancient DNA fragments from Neanderthal in the sample were about 50 to 70 base pairs in length, compared to the hundreds to thousands of base pair lengths of contemporary human DNA that could have contaminated the fossil. This makes sense because modern human DNA wouldn't have suffered the 38,000 years of insults that the Neanderthal DNA experienced."
Comparing Neanderthal to human and chimpanzee genomes showed that at multipl
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Contact: Lynn Yarris
lcyarris@lbl.gov
510-486-5375
DOE/Lawrence Berkeley National Laboratory
15-Nov-2006