Chimpanzee Genome Project for Understanding Ourselves

Sakaki, Y., Watanabe, H., Fujiyama, A., Hattori, M., Toyoda, A., and Taylor, T.D.

RIKEN Genomic Sciences Center

Human genome (draft) sequence revealed various characteristics of our genome: (1) The genome has 30000-40000 genes in total, (2) nearly 50% of the genome is shared by so-called repetitive sequences, (3) there exist a few million of SNPs (Single Nucleotide Polymorphisms) in the human population, and so on. The genome contains all the genetic information for our life, but the information extracted from the human genome sequence alone is quite limited. Even the genes cannot be predicted precisely. We thus need a variety of approaches for understanding our genome in more depth, including human genetics, transcriptome/proteome analysis, comparative genomics, bioinformatics and so on. Among them, comparative genomics is a powerful approach　for zooming up functionally important and interesting regions/sequences in the genome. Since the functionally important sequences/structures are well conserved during evolution, the potentially important sequences/structures for biological functions will be extracted as the "conserved sequences" by comparing the evolutionaly distant species. Indeed, human-mouse comparison has successfully identified various biologically interesting sequences without any prior knowledge. On the other hand, each species should have the genetic information defining its own characteristic features, so that the genome comparison of closely related species allow us to extract the sequences/structures defining the phenotypes specific to the species.

Comparison between humans and chimpanzees are the most efficient and effective approach to zoom up the genetic information that makes us human. As the first step, we constructed a first generation human-chimpanzee comparative genome map through paired alignment of 77,461chimpanzee BAC-end sequences (BESs) with human genomic sequences obtained from international DNA databanks. By using the BESs mapped with high confidence, the difference between the chimpanzee and human genomes were calculated to be 1.23% at the nucleotide level. This value is consistent with previous observations. The comparative map revealed not only base substations but also a considerable number of intra- and inter- chromosome rearrangements have taken place during evolution. For more precise understanding, the sequencing of the chimpanzee genome was initiated. In the meeting some preliminary data of the sequencing analysis will be presented.