March 1, 2009 (Vol. 29, No. 5)
Scientists Also Complete the Draft Sequence of the Endangered Bonobo
Scientists from the Max Planck Institute for Evolutionary Anthropology and 454 Life Sciences reported completion of the 1X draft sequence of the Neanderthal genome. The team, which began the project in July 2006, also announced the completion of the 18-fold draft sequence of the Bonobo genome, an endangered ape closely related to the common chimpanzee and distantly to humans.
Detailed analysis of both the Neanderthal and Bonobo genomes will significantly advance our understanding of the human evolutionary history, said the researchers.
The Neanderthal project, led by Svante Pääbo, Ph.D., director of the institute’s department of evolutionary anthropology, and Michael Egholm, chief technology officer at 454 Life Sciences, developed from the results of a study published in Nature in 2006, detailing the ability of 454 Sequencing to determine large amounts of nuclear DNA sequences from late Pleistocene animals such as cave bears, mammoths, as well as the Neanderthal.
Genetic Changes that Define Humans
The goal of the project is to identify areas in the genome where humans have undergone rapid evolution since the split from Neanderthals. This analysis is achieved by comparing the Neanderthal reference to the human and chimpanzee reference genome sequences as well as to the genomic variation among humans today.
The scientists said they had to overcome a number of steep technical obstacles to arrive at this first view of the extinct form of human, including difficulties with highly degraded and contaminated DNA and the limited availability of precious fossil material. A number of key milestones have been achieved over the course of the project, including the complete mitochondrial genome sequence, published in Cell in 2008.
Using the chimpanzee and human mitochondrial DNA sequences as reference points, the number of nucleotide differences found in the Neanderthal mitochondrial DNA establishes the divergence date between human and Neanderthal mtDNAs at 660,000 +/- 140,000 years.
The final draft sequence includes more than three billion bases of Neanderthal DNA and covers approximately two-thirds of the genome. During the last phase of the project, microreads generated by the Solexa technology were used to achieve the onefold coverage.
To aid in the analysis of the Neanderthal genome, Dr. Pääbo has organized a consortium of researchers from around the world that plans to publish their results later this year.