CARBONDALE — Dr. Diana Sarko calls it “a face only a mother could love.”
Sarko, an assistant professor of anatomy with the Southern Illinois University School of Medicine, has been studying naked mole rats for the past several years, and she’s quick to acknowledge the burrowing rodents’ unusual appearance: they have tiny eyes, protruding teeth and almost completely hairless, pink-yellow skin.
But Sarko and other researchers believe naked mole rats could have a lot to tell us — about aging, about sensory systems and about fighting cancer.
Native to Africa, naked mole rats prefer hot, humid environments, so the colony at SIU Carbondale is located in a dark room that is kept between 82 and 84 degrees, with two humidifiers running at all times.
In the wild, they feed primarily on tubers; at the SIU Carbondale laboratory, they’re fed sweet potatoes, other veggies and fruits.
Sarko obtained the animals from another colony at University of Illinois Chicago — she transported them to SIU herself, with the heat in her car turned up all the way.
“Our original colony started out with two colonies of five animals each and now one of them has almost 40 animals in it, because they’ve been reproducing happily,” Sarko said.
Like bees and ants, naked mole rats have a eusocial colony structure, with a single queen that reproductively suppresses other females. All individuals in the colony help care for the queen’s brood.
There are two queens in the SIUC colonies, named Daenerys and Cersei after the characters in “Game of Thrones.”
Sarko is studying the ways in which the species has adapted to maximize its advantages in its environment.
“Usually, rodents about this size would live to be about two to three years old. These guys live to be 30 years or older,” Sarko said.
As a result of their extraordinary longevity, naked mole rats are often used for aging studies and for cancer research, as they have a high resistance to tumors.
Naked mole rats are also remarkable for their specialized incisors. They use their teeth for digging through tunnels and for “incisor fencing" — locking teeth with each other to fight.
“For one thing, they (the incisors) are super sensitive. They take up a huge amount of what we call the somatosensory cortex, which is the tactile representation of your body in your cerebral cortex,” Sarko said.
In lab rats, the representation from those teeth in the somatosensory cortex is about 7 percent; in naked mole rats, it’s 30 percent.
“We’re trying to use these guys as a model for tooth loss in humans, because that happens really often, especially in aging populations and lower-income individuals, tooth loss is a really common thing and is very much associated with some sensory issues and also some pain,” Sarko said.
Naked mole rats can also move their lower incisors independently and voluntarily. For their body size, their bite is as strong as a lion’s.
“Most of their muscle mass is concentrated in their heads, so they have these huge jaw muscles that help them to really have a strong bite for their size, so we’re looking into characterizing some of that, and also some of that individual tooth movement as well, since that’s such a unique feature to them,” she said.
Sarko has never been bitten by a naked mole rat. For the most part, they’re docile creatures — although her lab manager did get bitten once when he was covering a tunnel exit.
“Honestly, it’s much worse with a lab rat or a lab mouse. It’s much more common to be bitten by them than these guys, even though they’ve got some very impressive teeth,” Sarko said.
Naked mole rats are functionally blind, so they primarily use their teeth to navigate. They also have some fine tactile hairs on their bodies to sense their environments.
The tunnel system in the SIUC lab features a number of chambers connected by small tubes.
“They decide which of those segregated spaces is going to be sort of a snuggle spot, where they all pile on top of each other and sleep — and we have a heat lamp there, so it’s extra warm — and one of them’s a toilet chamber, and there’s a food area, so they decide that and have these different segregated areas in their colony,” Sarko said.
Sarko has been conducting her research on naked mole rats at SIU for the past three years. Previously, she studied them as a postdoctoral researcher at Vanderbilt University. She plans to publish two to three papers in the next year.
“When you look at these animals that are sort of the extremes of evolution, you can really learn a lot about different ways where sensory systems and motor systems can be pushed and pulled, and you can learn some really interesting things,” Sarko said.