Greenland Shark's DNA Repair Mechanism May Hold Key to Preserving Human Vision
核心洞察
A UC Irvine-led study published in Nature Communications found that Greenland sharks, the longest-living vertebrates, show no signs of retinal degeneration despite living up to 400 years.
Researchers identified a DNA repair mechanism that may protect the shark retina from age-related decline, with rhodopsin (搜索) remaining active and tuned to blue light for low-light vision.
The findings challenge the long-held assumption that Greenland sharks are functionally blind due to eye parasites and their dark Arctic habitat.
A new study led by Dorota Skowronska-Krawczyk, associate professor of physiology and biophysics at the University of California, Irvine, suggests that Greenland sharks—the longest-living vertebrates known to science, with some individuals surviving up to 400 years—may preserve useful vision across centuries. Published in Nature Communications, the research points to a DNA repair mechanism that may help protect the shark retina from age-related decline, challenging the long-held assumption that these animals are functionally blind.
The study, co-authored by University of Basel researchers Walter Salzburger and Lily G. Fogg, who examined the evolutionary aspects of the work, found no signs of retinal degeneration and showed that the sharks are adapted to extremely low-light environments.
A Moving Eye Raises Questions
Skowronska-Krawczyk studies the molecular processes involved in aging and eye disease, so the Greenland shark presented an unusual biological puzzle. If an animal can live for centuries, its tissues must somehow resist damage that accumulates with age. The eye, which is especially vulnerable to degeneration in humans, offered a direct way to investigate that resilience.
Her curiosity began with a 2016 research paper by John Fleng Steffensen published in Science. The paper noted that many Greenland sharks carry parasites on their eyes, a detail that could help explain why their vision had been dismissed.
"One of my takeaway conclusions from the Science paper was that many Greenland sharks have parasites attached to their eyes—which could impair their vision," she says. "Evolutionarily speaking, you don't keep the organ that you don't need. After watching many videos, I realized this animal is moving its eyeball toward the light."
That observation turned the question around. Instead of asking why the shark's eyes looked damaged, Skowronska-Krawczyk wanted to know whether the eyes were still working.
Rare Eyes Reach the Lab
The sharks examined in the study were caught between 2020 and 2024 on scientific long lines off the coast of the University of Copenhagen's Arctic Station on Disko Island, Greenland. Steffensen, a professor of marine biology at the University of Copenhagen, worked with Peter G. Bushnell of Indiana University South Bend and Richard W. Brill of the Virginia Institute of Marine Science to dissect and preserve the eyes in a fixative solution.
The preserved tissue eventually reached UC Irvine, where Emily Tom, a UC Irvine Ph.D. student and physician-scientist in training in Skowronska-Krawczyk's lab, faced a very different specimen from the tiny mouse eyes she normally handled.
"I opened the package, and there was a giant, 200-year-old eyeball sitting on dry ice just staring back at me," the 28-year-old says. "We're used to working with mouse eyeballs, which are the size of a papaya seed, so we had to figure out how to scale up to a baseball-sized eyeball."
Handling the tissue required careful timing. If it thawed too much, the sample could degrade once it reached room temperature. Tom carried out histological and vision-specific analyses, looking closely at tissue structure and markers of visual function. She found no signs of cell death and showed that rhodopsin (搜索)—a protein essential for vision in dim light—remained active in the shark retina and was tuned to blue light.
No Signs of Retinal Cell Death
The researchers found no evidence of cell death in the retina. They also discovered that rhodopsin (搜索) remained active in the shark retina, tuned to detect blue light—an adaptation that could help Greenland sharks see in the faint light available deep beneath Arctic waters.
"Not a lot of people are working on sharks, especially shark vision," Tom says. "We can learn so much about vision and longevity from long-lived species like the Greenland shark, so having the funds to do research like this is very important."
The results suggest that the Greenland shark's remarkable lifespan does not necessarily come with the severe retinal deterioration that might be expected in such an old animal.
What Greenland Sharks Could Teach Us About Aging
For Skowronska-Krawczyk, the value of the work reaches beyond shark biology. If Greenland sharks can keep retinal tissue healthy for centuries, the mechanisms behind that protection could help scientists think differently about age-related vision loss in people.
The findings may eventually inform research on eye diseases such as macular degeneration (搜索) and glaucoma (搜索). They also raise broader questions about how vision evolves, how long-lived tissues avoid damage, and how lessons from extreme animals might guide human medicine.
Skowronska-Krawczyk notes that with federal research funding under threat, future support for her studies is a concern, but she believes that "we will prevail."
"What I love about my work is that we are the first in the world to see results—at the forefront, finding new mechanisms, rules and discoveries," Skowronska-Krawczyk says. "Then, being able to share this joy with students—that's the best part of it."