Rhesus macaque genome helps illuminate what makes us human 12/4/07. By the American Association for the Advancement of Science The genome of the rhesus macaque monkey provides insights into how humans are genetically different from our primate relatives.

The rhesus macaque, a primate species that had a common ancestor with humans and chimps but diverged from the human-chimp lineage approximately 25 million years ago, still shares about 93 per cent of its genome sequence with humans. This makes the macaque an integral part of primate evolutionary studies and could allow researchers to gain a better understanding of HIV/AIDS in humans.

The rhesus macaque is the third primate to have its genome sequenced: the human genome was sequenced in 2001 and the chimp genome in 2005. The Rhesus Macaque Genome Sequencing and Analysis Consortium, an international team of more than 170 scientists from 35 institutions, described their results in the 13 April issue of the journal 'Science'.

The research found that the three primate species share about 93 per cent of their DNA. Rhesus macaque genes are about 97.5 percent similar to those of chimps and humans, while chimps and humans have 99 percent of their gene sequences in common.

About 200 genes show evidence of positive selection during evolution, making them potential candidates for determining the differences among primate species. These genes are involved in hair formation, immune response, membrane proteins and sperm-egg fusion.

Even though macaques are used in human disease research, scientists were surprised to find some instances where the normal form of the macaque protein looks like the diseased human protein. One example occurs in phenylketonuria (PKU), which can lead to brain damage and mental retardation in humans because of a defect in an important enzyme.

A further study, also reported in the 13 April issue of 'Science', looked at genetic differences between Chinese and Indian macaques. The analysis suggests that the two populations separated about 162 000 years ago.

Both Indian and Chinese macaques are used in biomedical research, and understanding the genetic differences between the two populations is important. For example, the simian immunodeficiency virus (SIV) is used as a model for the human immunodeficiency virus (HIV), but when exposed, Chinese macaques develop AIDS-like symptoms more slowly than Indian macaques.

Adapted from a news release by the American Association for the Advancement of Science.

References

Gibbs RA et al. Evolutionary and Biomedical Insights from the Rhesus Macaque Genome. Science 2007;316(5822):222-234. Abstract

Hernandez RD et al. Demographic Histories and Patterns of Linkage Disequilibrium in Chinese and Indian Rhesus Macaques. Science 2007;316(5822):240-243. Abstract