By Deborah Netburn
This post has been corrected, as indicated below.
7:00 AM PDT, April 10, 2013
Look beyond the western painted turtle's colorful stripes and you’ll find an animal that seems to have nearly magical powers.
A baby western painted turtle can freeze solid, and as long as nothing cracks it in half or tampers with it too much, the turtle will be just fine when the temperature warms up and its body thaws out. An adult western painted turtle can go without oxygen for up to 30 hours at room temperature, and if the temperature drops to 37 degrees, it can hold its breath for up to four months at a stretch.
So when more than 50 international researchers launched a project to sequence the painted turtle genome several years ago, they weren't just hoping to answer questions about how it would differ from the genome of other animals but also to discover the unique genes that allow it to freeze without getting frostbite and exhibit no brain damage even after living for months without oxygen.
What they discovered is that the turtle’s genome is not that different from our own.
In a paper published in Genome Biology, the authors found that the genes the painted turtle was using for freeze tolerance and anoxia tolerance (the ability to go without oxygen) were the same genes that are present in all vertebrates — it’s just that the turtle expresses them differently.
“They used the machinery that all vertebrates have, but they modified it to build a better organism,” said UCLA’s Brad Shaffer, the lead author of the paper. “These are genes and pathways that we have too, but we are not using them in the same way.”
The researchers found 19 genes in the brain and 23 in the heart that became more active when the turtle experienced low-oxygen conditions. One gene that humans share became 130 times more active.
The researchers believe that further study of the turtle’s genome could be relevant for human health and well-being, especially concerning issues related to oxygen deprivation, hypothermia and longevity.
Scientists estimate that turtles have been around for more 210 million years, making their lineage one of the oldest on Earth. This study also revealed that turtle genomes evolve at about one-third the rate seen in humans and about one-fifth the rate of other reptiles, including the python.
The paper was published in Genome Biology on March 28.
[For the record, 4:40 p.m., April 10: An earlier version of the headline suggested humans have the same genome as the western painted turtle. That is incorrect, but we share many of the same genes.]
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