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Small differences in gene regulators separate humans and chimps

A new study has revealed a key difference in the genetic makeup of humans, chimps, and other primates.

Bonobos and chimpanzees are our closest relatives, sharing 99 percent of the same DNA.

Genome sequencing of chimps, bonobos, and other primates has revealed many similarities, but recently, a good deal of research has been devoted to understanding the genetic differences that separate humans from other primates.

A new study conducted by researchers from the Cold Spring Harbor Laboratory (CSHL) and Cornell University found that a key difference between humans and primates has to do with the way our genes are regulated.

The research included complete genome analyses of three different primate species including human, chimpanzees, and rhesus macaques.

The study focused primarily on gene enhancers and promoters which regulate the genes. Both promoters and enhancers regulate and activate the genes, but enhancers are located much farther from the genes they regulate than promoters.

The researchers measured the generation of RNA copies of genomic DNA using PRO-Seq technology. Measuring the RNA copies up and downstream of the original genes allowed the researchers to identify which promoters and enhancers regulate different genes.

The results showed differences in the way the genes were regulated across the three different species, particularly with a group of enhancers that work together to target a gene. This group of enhancers is called an ensemble.

“These ensembles come in various sizes,” said Adam Siepel, a member of the research team. “And we found that when they are large, the expression levels of the target genes tend to be stable over evolutionary time. When they are small, the expression levels are less stable.”

The ensemble of enhancers work together and determine gene expression depending on the species. The study shows that these differences are responsible for the evolutionary genetic  differences that separate humans from other primate species.

By Kay Vandette, Staff Writer

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