Snake and lizard 'urates' point to new approaches for human disease
Scientists studying the solid excretions of more than 20 snake and lizard species say the way reptiles crystallize nitrogenous waste could someday inform treatments for gout and kidney stones in people.
Unlike humans, who eliminate excess nitrogen mainly as dissolved urea, uric acid and ammonia, many reptiles conserve water by converting some waste into solid deposits called urates, which are expelled through the cloaca. A team led by Jennifer Swift, a chemistry professor at Georgetown University, reported in the Journal of the American Chemical Society that every species they examined contained microscopic spherical uric-acid structures.
“The work began from wanting to understand how reptiles safely excrete this material, with the hope it could suggest new ways to prevent and treat disease,” said Jennifer Swift in a news release.
Using high-powered electron and optical microscopy, the researchers found that species such as pythons and Madagascan tree boas produce textured microspheres no larger than 0.0004 inches (about 10 micrometers). Those microspheres are assembled from still-smaller nanocrystals composed of uric acid and water.
Importantly, the study suggests uric acid within these structures may help convert toxic ammonia into a safer, solid form — a strategy that lets reptiles eliminate waste without large water losses. In humans, however, elevated uric acid can form painful crystalline deposits in joints (gout) or in the urinary tract (kidney stones).
The authors emphasize that more research is needed to determine whether the chemistry reptiles use can be adapted to prevent or treat uric-acid–related conditions in people. Still, understanding how animals safely package and remove uric acid could inspire new preventative strategies or therapies.
Takeaway: Reptile urates — tiny, structured spheres of uric acid — reveal a natural, water-saving method of waste crystallization that may point to future biomedical applications for gout and kidney-stone prevention.
For background on high uric acid in humans, see resources such as the Cleveland Clinic on hyperuricemia.
