Naked Mole-Rats Can Live Without Oxygen, They Just Act Like Plants … Wait, What?

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In the ever beautifully bizarre world of nature’s strangest mammal, the naked-mole rat can live for nearly 20 minutes without oxygen. Here’s how.

Behold the naked mole-rat, one of the world’s best creatures. OK, so maybe the festive teeth and beady eyes and wrinkled hairless skin aren’t exactly cuddly – they’re like the exact opposite of a kitten – but they are exquisitely designed to live in the habitat of their choice, tunnels beneath the hot African desert. And for that, they are the rock stars of the rodent realm.

Leading such an extreme subterranean life has bestowed naked mole-rats with some pretty impressive talents. They don’t get tumors, they’re immune to chronic pain and the irritating components of chili peppers. Like social insects, they live in eusocial colonies, some 300-strong and governed by a queen. Oh, and although they are mammals – you know, warm-blooded – they are actually cold-blooded.

And now the latest discovery in their magical bag of tricks? They can live without oxygen.

Ben Guarino reports in the Washington Post on a new study that revealed not only that the wonder rodents can live completely deprived of oxygen for at least 18 minutes without suffering evident harm, but that they “switch their energy source from glucose – what humans and virtually all other mammals use – to fructose.” Or, the sugar that plants use.

Guarino notes that if you take away a mouse's oxygen, it will die in a mere 20 seconds.

For us less-oxygen-skilled humans, the Occupational Health & Safety Administration says “oxygen-deficient” air is less than 19.5 percent. From The Post:

Humans, unless they go through a careful acclimation process, stop functioning well at around 10 percent. Thrust into a cage with air at 5 percent oxygen, humans would die.
When Thomas Park, an expert on naked mole-rats, placed the first animal in a chamber containing only 5 percent oxygen, the mood, he said, was “tense.” The scientists began their stopwatches and waited for the slightest twitch of distress. The animal, though, seemed unaware that three-fourths of the oxygen in its environment had vanished. Fifteen minutes passed. The animal was unperturbed. Minutes bled into hours. The scientists called time after 300 minutes.
“They didn’t even go to sleep,” says study co-author Park, a neurobiologist at the University of Illinoi

At zero percent oxygen, their heart rate dropped from 200 beats per minute to a subtle 50. Once the scientists turned the oxygen back on, the rodents perked right back up.

“They were able to survive up to 18 minutes without any apparent neurological damage,” says Jane Reznick, another co-author of the study at the Max Delbrück Center for Molecular Medicine in Berlin.

It’s not news that naked mole-rats don’t need a lot of oxygen, especially given that their underground digs, so to speak, aren’t exactly oxygen-rich. Earlier research discovered that their oxygen-moving red blood cells came with an unique efficiency-boosting hemoglobin.

What surprised the authors of the new study were the levels of fructose molecules found in the oxygen-deprived rodents. Whereas humans require an oxygen-glucose relationship, the mole-rats, just like plants, turn fructose into fuel without the presence of oxygen as the key metabolic component.

What other wonders does the marvel of a mole-rat have in store? “We still don’t know where the fructose comes from,” Reznick says. Guarino muses that maybe the mole-rats have some sort of fructose storage system. “If the rodents' bodies somehow produced fructose, that would be even stranger,” he writes. “But it's hard to rule out oddity when it comes to the mole-rats.”