A large team of genetic researchers from the United States, Europe and China has sequenced and analyzed the complete genome of the Northern white-cheeked gibbon (Nomascus leucogenys).
Female and male Northern white-cheeked gibbon. Image credit: Linda, Jinterwas / CC BY 2.0.
For many decades, scientists have known that gibbon chromosomes evolve quickly and have many breaks and rearrangements, but up until now there has been no explanation why.
“Chromosomes play an essential role in the packaging of DNA. When there are rearrangements in chromosomes, the genes and gene regulation are often disrupted or broken. Cancer is clearly the biggest medical example of the impact of chromosome rearrangements. The gibbon sequence gives us more insight into this process,” said Prof Kim Worley of the Baylor College of Medicine’s Human Genome Sequencing Center in Houston, Texas, a team member and a co-author of the paper published in Nature.
Co-author Dr Jeffrey Rogers, also of the Human Genome Sequencing Center, added: “the number of chromosomal rearrangements in the gibbons is remarkable. It is like the genome just exploded and then was put back together. Up until recently, it has been impossible to determine how one human chromosome could be aligned to any gibbon chromosome because there are so many rearrangements.”
“We do this work to learn as much as we can about gibbons, which are some of the rarest species on the planet. But we also do this work to better understand our own evolution and get some clues on the origin of human diseases,” said lead author Dr Lucia Carbone of Oregon Health & Science University and Oregon National Primate Research Center.
According to the team, the gibbon genome contains all previously described classes of genetic repeat elements (segments of DNA that occur in multiple copies throughout the genome) that are mostly also present in other primates.
“Repeat elements have the capability to disrupt a gene and change their biological function,” Prof Worley explained.
In the gibbons, the scientists also identified a novel repeat element, dubbed LAVA, which emerged exclusively in gibbons and preferentially hits genes involved in chromosome segregation.
“This explains why the gibbons have undergone so much change. Similar disruptions cause disease, which is why everything we learn from this helps us better understand human biology and chromosomal structures,” Dr Rogers said.
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Lucia Carbone et al. 2014. Gibbon genome and the fast karyotype evolution of small apes. Nature 513, 195-201; doi: 10.1038/nature13679
