Researchers have decoded the DNA of the western painted turtle in the hopes that a greater understanding of these reptiles could one day improve treatment for people who suffer a heart attack or stroke.
The researchers identified 19 genes in the turtles' brain and 23 in the heart that are activated in situations with low oxygen. These genes also occur in humans. The study authors said their findings might lead to treatments to repair tissue damage due to oxygen deprivation associated with cardiovascular emergencies.
Mystery of turtles
"Turtles are nothing short of an enigma," senior study author Richard Wilson, director of Washington University's Genome Institute, said in a university news release. "They may be slowly evolving, but turtles have developed an array of enviable features. They resist growing old, can reproduce even at advanced ages and their bodies can freeze solid, thaw and survive without damaging delicate organs and tissues. We could learn a lot from them."
Turtles evolve very slowly - at about one-third of the rate of human evolution - found the team of researchers from several institutions, including Washington University School of Medicine in St. Louis, St. Louis University and the University of California, Los Angeles. The body design of turtles has not changed much in 210 million years.
By examining the turtle's DNA, the researchers found that turtles are more closely related to birds than other reptiles, such as lizards and snakes. They are also able to withstand oxygen deprivation not by relying on new genes, but by activating gene networks found in humans and most other vertebrates and using those genes in new ways.
"This is a backdoor route for turtles to evolve," study co-author Patrick Minx, of the Genome Institute, said in the news release. "Rather than evolve new genes, they adapted existing genes for new uses."
Up to 5% of the 330 turtle species worldwide are considered threatened, however, primarily due to human consumption, the researchers said. Although claims have been made that eating turtles can help people live longer or cure cancer, these are unsubstantiated, the researchers added.
Changes in turtles' habitats have also played a role in their global decline.
"The challenge is to preserve the rich diversity of turtles that still exist on Earth as we continue to unravel their secrets for success," study first author H. Bradley Shaffer, of UCLA, said in the news release. "Turtles have a tremendous amount to tell us about evolution and human health, but time is running out."
The study was published online recently in the journal Genome Biology.
Visit the University of California Museum of Paleontology for more about evolution.