HOPE Report No.1 2004-07-07
Program No.1 (Joint research)
Oral presentation on "The DNA Sequence of Chimpanzee Chromosome 22 and Comparative Analysis with Human Chromosome 21" in the workshop of "Primate
Genomics" in HGM2004 in Berlin and the discussion with Dr. Svante Pääbo
about the speciation of chimpanzees and bonobos.
By Hidemi Watanabe
Place of visit: Max Planck Institute for Evolutionary Anthropology,
Period of visit: 15th-21th MApril 2004
I attended the HGM2004in Berlin. In April 5th, 2004. I participated in the
workshop titled "Primate Genomics" and gave a talk on "The DNA Sequence of
Chimpanzee Chromosome 22 and Comparative Analysis with Human Chromosome 21".
This is an outcome of the collaborative research with Dr. Svante Pääbo
and his colleagues in MPIEVA. After the congress, I talked with Dr. Pääbo on the speciation of chimpanzees and bonobos in relation to the
potential influence of the geographical separation by the formation of Congo River.
The summary of my talk was as follows. To backtrack the genomic changes during human evolution, we have decided to sequence
chimpanzee genomes and recently sequenced chimpanzee chromosome 22 (PTR22),
the orthologous chromosome of human chromosome 21 (HSA21). Through the comparison between HSA21 and PTR22, we revealed a large number of
differences between them. Surprisingly enough, 50% of the genes in these chromosomes showed differences in their amino acid sequences, though the
nucleotide difference level was around 1%.
We further sequenced the genomic portions in gorillas and orangutans that corresponded to some of the
differences, and we inferred the states of these loci in the LCA of humans
and chimpanzees with a cladistical way and revealed the evolutionary events
occurred in the human and the chimpanzee lineages. One of the significant differences between these lineages was the frequency of Alu and L1PA2
insertions. We found many differences in the expression and the structures
of genes that were involved in immune systems, implying that these differences are the cause of the phenotypic differences in susceptibilities
to various infectious diseases.
Click to enlarge.