Research monkey’s genetic code deciphered

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Research monkey's genetic code deciphered

Genome could guide future research into human diseases, scientists

say

Moglia / Science via AP

A rhesus macaque monkey sits on a perch at the National Institutes

of Health's Animal Center in Poolesville, Md.

http://www.msnbc.msn.com/id/18079607/

WASHINGTON - Scientists have unraveled the DNA of another of our

primate relatives, this time a monkey named the rhesus macaque — and

the work has far more immediate impact than just to study evolution.

These fuzzy animals are key to testing the safety of many medicines,

and understanding such diseases as AIDS, and the new research will

help scientists finally be sure when they're a good stand-in for

humans.

" The thing we're all fascinated with is what makes us different from

these animals who are so close to us, " said Dr. Gibbs of the

Baylor College of Medicine, who led a team of more than 170

scientists that collaborated on the project.

In Friday's edition of the journal Science, the researchers report

deciphering the macaque's DNA and comparing it to the genetic

blueprints of humans and chimpanzees, our closest living relatives.

Among the most intriguing discoveries so far: a list of diseases

where the same genetic mutation that makes people ill seems normal

for the macaques.

" That is really quite a stunner, " said Dr. Francis , genetics

chief at the National Institutes of Health, which funded the

research. " It gives you a glimmer of how subtle changes in DNA cause

big trouble. "

Third primate genome

The mapping of the human genome in 2001 sparked an explosion of work

to similarly decipher the DNA of other animals, so scientists could

compare species in the effort to understand the functions of various

genes.

The rhesus macaque is the third primate genome to be completed, work

that promises to greatly enhance understanding of primate evolution,

perhaps even to help explain what makes us human.

Not surprisingly, the DNA of humans, chimps and macaques are highly

similar. Humans and chimps have evolved separately since splitting

from a common ancestor about 6 million years ago, but still have

almost 99 percent of their gene sequences in common.

Macaques branched off from the ape family tree far earlier, about 25

million years ago — yet still share about 93 percent of their DNA

with humans, the new work shows.

Here's the key: Six million years isn't long in evolutionary

history. So if a particular gene is different in the human and the

chimp, it's impossible to know which version came first. Add these

more ancient Old World monkeys into the mix, however, and it may be

possible to tease out genetic changes that were important for key

traits of modern humans, such as higher brain power and walking

upright.

" That does point us, in a much more powerful way, to answering the

question, 'What does humanness mean?' at the DNA level, " said

, director of NIH's National Human Genome Research Institute.

Important biomedical questions

But right away, the work raises some important biomedical questions,

because rhesus macaques are ubiquitous in medical research. Most

vaccines and many drugs are tested in the monkeys before ever

reaching people. And they're used as models of many human diseases,

most notably the AIDS virus.

" As models, we expect them to behave like us, " noted Baylor's Gibbs.

Yet consider some of the differences found so far:

About one in 14,000 babies is born with PKU, or phenylketonuria,

meaning their bodies can't process a protein found in most foods

called phenylalanine. Without treatment, PKU causes mental

retardation. But in macaques, the gene defect that causes PKU seems

to cause no harm, suggesting they may somehow compensate in a way

people can't. The researchers found a list of such mutations, from

ones linked with cystic fibrosis to blood diseases, that are bad

news for people but seem normal in the monkeys. Most involved

metabolic disorders that in turn can harm the brain, a link Gibbs

found particularly compelling.

The monkeys had triple the number of genes that people do not run

one arm of the immune system. That raises immediate questions about

how they react in vaccine or AIDS research. " It would make sense

that a comprehensive knowledge of their immune machinery should be a

part of those studies, " Gibbs said.

On the other hand, macaques had far fewer of a family of cancer-

related genes than either humans or chimps.

Gibbs said the work has importance for the animals, too — because

knowing their genetic makeup should cut the number of monkeys needed

in many biomedical experiments.

" It's really about experimenting less and being able to learn more, "

he said.

Stay tuned: More primate gene maps are on the way, including

blueprints for orangutans, gorillas and gibbons.