Part of the answer to how and why primates differ from other mammals, and humans differ from other primates, may lie in the repetitive stretches of the genome that were once considered "junk."
A new study by researchers at the University of Iowa Carver College of Medicine finds that when a particular type of repetitive DNA segment, known as an Alu element, is inserted into existing genes, they can alter the rate at which proteins are produced -- a mechanism that could contribute to the evolution of different biological characteristics in different species. The study was published in the Feb. 15 issue of the journal Proceedings of the National Academy of Sciences (PNAS).
"Repetitive elements of the genome can provide a playground for the creation of new evolutionary characteristics," Xing said. "By understanding how these elements function, we can learn more about genetic mechanisms that might contribute to uniquely human traits."
Alu elements are a specific class of repetitive DNA that first appeared about 60 to 70 million years ago during primate evolution. They do not exist in genomes of other mammals. Alu elements are the most common form of mobile DNA in the human genome, and are able to transpose, or jump, to different positions in the genome sequence. When they jump into regions of the genome containing existing genes, these elements can become new exons -- pieces of messenger RNAs that carry the genetic information.
Although scientists have known for more than a decade that these Alu elements are an important source of new exons in the human genome, it has been more difficult to determine if these new exons are biologically important.
"It's been hard to say whether these Alu-derived exons actually do anything on a genome-wide level," said senior study author Yi Xing, Ph.D., assistant professor of internal medicine and biomedical engineering, who holds a joint appointment in the UI Carver College of M
|Contact: Jennifer Brown|
University of Iowa Health Care