After years of development, a synthetic version of exendin-4, known as exenatide and marketed as Byetta, was approved by the FDA in 2005. It is currently used to manage type 2 diabetes, and it might even help to protect against degenerative brain diseases like Alzheimer’s or Lou Gehrig’s disease.
“The pharma industry has studied exendin-4 extensively but nothing else about the Gila monster’s genome,” says Wilson Sayres. The creature’s other genes are largely a mystery; the closest living relative whose genome has been fully sequenced is the green anole—a slender, tree-dwelling lizard. “It’s like saying we want to study humans but all we have is a kangaroo genome,” she adds. “We don’t even know very much about how exendin-4 works in the monsters.”
She plans to change that by sequencing the lizard’s full genome, and looking at the genes that it activates in its salivary glands and its tail. To do that, she raised more than $10,000 in a crowdfunding campaign and did a lot of outreach, from appearances on local TV to a delightfully snarky Twitter account.
The monster’s genome might reveal more medically useful substances like exendin-4, as well as offering clues about the lizard’s many weird traits—their venom, their fatty tails, and more. For example, unlike other lizards, Gila monsters can’t break off and grow back their tails, presumably because they use store fat there. “If you drop your tail, that’s a lot of calories you just lost and fed to someone else,” says Wilson Sayres. One of her colleagues is looking for the genes responsible for the regenerative abilities of other lizards, and it might be easier to find those genes by looking for those that have changed significantly in the Gila monster.
The Gila monster genome might also tell us something about another group of reptiles—snakes. It’s clear that snakes evolved from lizards, but it’s unclear which group they originated from. Currently, snakes are positioned as the cousins to a large group of lizards that includes the Gila monster, monitor lizards, iguanas, chameleons, and anoles.
Here’s the twist: The green anole determines its sex using X and Y chromosomes, just like us. Males have a mismatched XY and females have a matching XX. But both Gila monsters and snakes have Z and W chromosomes, where the males have matching ZZ and the females have mismatched ZW. If they're genetically identical (or similar, at least) that tells you that both the snakes and Gilas inherited their ZW from a common ancestor (rather than evolving them independently), and thus are more closely related than they are to anoles.That would shift their position in the lizard family tree and provide new clues about how they evolved.
As is increasingly the case, research like this is a race against time. As the world warms, the Sonoran’s spring rains will become more inconsistent and the summer monsoons will arrive later. The Gila monster is well-adapted to persisting through that dry spell, but may not be able to cope with longer droughts. By the end of spring, “they’ve pretty much filled their abdomen with as much water as possible,” says DeNardo. “If there’s no room to get larger, they won’t be able to stretch out much longer.” By changing the climate, we may be inadvertently slaying the monster.
And that, Wilson Sayres thinks, would be an incredible shame. “It’s such a cool animal, and it’s so lovable.” We’re now sitting in her office, and she’s holding a 3D-printed model of a Gila monster skull. It looks rather nightmarish—distinctly reptilian, full of sharp curved teeth, and covered in knobby bone. This, I venture, does not look like the skull of a lovable animal.
“I mean, if you had no flesh on your face, you probably wouldn’t be adorable either,” she says.