NEW YORK, May 26 (GenomeWeb News) - Researchers have published the complete sequences of three primate chromosomes this week -- chimpanzee chromosome 22 and human chromosomes 9 and 10 -- in separate papers appearing in tomorrow's issue of Nature.
The International Chimpanzee Chromosome 22 Consortium, led by Japan's RIKEN, reported the complete sequence of chimpanzee (Pan troglodytes) chromosome 22 and also compared this sequence to its human ortholog, chromosome 21. The consortium reported that 1.44 percent of the chimpanzee chromosome contains single-base substitutions when compared to its human counterpart, in addition to 68,000 insertions or deletions.
Out of 272 annotated chimpanzee genes, the researchers compared coding sequences in 231 genes for which they could identify a non-ambiguous open reading frame in both human and chimpanzee, and found that genetic differences were sufficient to generate protein-level changes in 83 percent of those sequences. "[G]ross structural changes affecting gene products are far more common than previously estimated," the authors wrote, concluding that "the biological consequences due to the genetic differences are much more complicated than previously speculated."
Human chromosome 9, meanwhile, was sequenced to more than 99.99 percent coverage by an international team led by the Wellcome Trust Sanger Institute. The chromosome, which includes genes implicated in sex reversal, cancer, and neurodegenerative disease, contains 109,044,351 base pairs, 1,149 genes, and 426 pseudogenes. Additionally, the authors found that chromosome 9 contains the largest interferon gene cluster in the human genome.
The Sanger Institute also led the sequencing effort for human chromosome 10, which contains 131,666,441 base pairs. The team annotated 1,357 genes, of which 816 are protein coding, and 430 are pseudogenes.