Comparing Chimp, Human DNA

Oct 12, 2006

Most of the big differences between human and chimpanzee DNA lie in regions that do not code for genes, according to a new study. Instead, they may contain DNA sequences that control how gene-coding regions are activated and read.

"The differences between chimps and humans are not in our proteins, but in how we use them," said Katherine Pollard, assistant professor at the UC Davis Genome Center and the Department of Statistics.

Pollard and colleagues at UC Santa Cruz led by David Haussler looked for stretches of DNA that were highly conserved between chimpanzees, mice and rats. Then they compared those sequences to the human genome sequence, to find pieces of DNA that had undergone the most rapid change since the ancestors of chimps and humans diverged about five million years ago.

They found 202 "highly accelerated regions" or HARs, which showed a high rate of evolution between humans and chimps. Only three of those regions contain genes that are likely to encode proteins. The most dramatically accelerated region, HAR1, appears to make a piece of RNA that may have a function in brain development.

DNA, deoxyribonucleic acid, carries the genetic instructions for making a chimp, a human, a tulip or an amoeba. RNA (ribonucleic acid) is an intermediate molecule that transcribes those instructions to make proteins.

The other highly accelerated regions do not appear to code for genes at all, but many are located close to genes involved in controlling when other genes get made, or in growth and development.

"They're not in genes, but they're near genes that do some very important stuff," Pollard said.

Typically, noncoding regions of DNA evolve more rapidly than regions carrying genes, as there is no selective pressure to stop mutations from accumulating. But the human-accelerated regions are highly conserved across the other groups of animals the researchers looked at, suggesting that they do have important functions that stop them from varying too much.

The work is published in the journal Public Library of Science (PLoS) Genetics. A separate paper on HAR1 was published Aug. 17 in the journal Nature. The study was funded by the National Institutes of Health and the Howard Hughes Medical Institute.

Source: UC Davis

Explore further: Immunity, signaling genes may be linked to schizophrenia

add to favorites email to friend print save as pdf

Related Stories

CRISPR system can promote antibiotic resistance

Jul 14, 2014

CRISPR, a system of genes that bacteria use to fend off viruses, is involved in promoting antibiotic resistance in Francisella novicida, a close relative of the bacterium that causes tularemia. The finding contrasts with p ...

Head formation of clawed frog embryos

Jul 11, 2014

On July 9, 2014, Dr. Yuuri Yasuoka in the Okinawa Institute of Science and Technology Graduate University's Marine Genomics Unit, published a research paper explaining a key mechanism in formation of ...

Recommended for you

Schizophrenia's genetic architecture revealed (w/ Video)

15 hours ago

Queensland scientists are closer to effective treatments for schizophrenia after uncovering dozens of sites across the human genome that are strongly associated with a genetic predisposition to schizophrenia.

Mysterious esophagus disease is autoimmune after all

Jul 22, 2014

(Medical Xpress)—Achalasia is a rare disease – it affects 1 in 100,000 people – characterized by a loss of nerve cells in the esophageal wall. While its cause remains unknown, a new study by a team of researchers at ...

Diagnostic criteria for Christianson Syndrome

Jul 21, 2014

Because the severe autism-like condition Christianson Syndrome was only first reported in 1999 and some symptoms take more than a decade to appear, families and doctors urgently need fundamental information ...

User comments : 0