Dr. Glen Watson and his graduate students are working to answer an intriguing question: can a sea anemone help cure deafness in humans? Since arriving at UL in 1989, Watson has received more than $1.3M in federal funding to answer that question.

A cell biologist, Watson has studied sea anemones since 1978.  The starlet sea anemone (Nematostella vectensis) possesses an extraordinary ability, Watson said. When the cells they use to detect brine shrimp prey are damaged, they can heal themselves.

Watson and his team are exploring cellular and genetic connections among sea anemones, zebrafish and humans, with the hope of someday contributing to a cure for deafness. The three species are among the relatively few whose entire genetic code is known and readily available to researchers.

The species also have similarities at the cellular level, Watson explained. Hair cells are found on anemone tentacles, on fish scales, and in human inner ears. At the tip of these cells are finger-like projections called stereocilia, which are interconnected by linkages called tip links.

Hair cells on the anemone detect the movements of brine shrimp as they swim by. Hair cells on the lateral lines of fish allow them to orient themselves while swimming. Human hair cells respond to vibrations and movement in inner ear fluid, sending both sound and position signals to the brain.

What’s interesting, said Watson, is what happens when the hair cells’ tip links are damaged in the different species. "Most forms of human deafness come from a death of the hair cells," he explained. Noise-induced hearing loss can be caused by a single event, such as an explosion, or by exposure to loud sounds over an extended period of time. "The hair cell pivots in response to sound, but when it pivots too much, the tip links are ripped apart. As a result, the hair cells die and hearing is lost."

In mammals, including humans, hearing loss is typically painless and permanent. But in some fish and in the anemones, it’s a different story. The fish regrow damaged hair cells and tip links, replacing them in a few days. Starlet sea anemones work even faster, making the fix in a matter of hours, using a mix of proteins that bind with calcium to repair the tip links. "Tip links use calcium as a kind of glue, giving the tip link its structure," Watson explained.

Watson and his team have discovered that the protein mixture produced by the anemones can be used to heal the damaged hair cells of blind cave fish. The research team is also studying the effects of the protein mixture on zebrafish.

Nesha Calais, a doctoral student pursuing a degree in environmental and evolutionary biology, carried out the experiments. She placed healthy fish in a tank containing calcium-depleted water for 15 seconds, which is long enough for their tip links to be broken. Then the fish became disoriented and their movements chaotic.

Calais then placed them in water that contained anemone hair-cell proteins. "They were perfectly fine. It’s as if they were never damaged," she said.

Watson finds that result amazing. "Proteins from a primitive, invertebrate animal can not only repair anemone hair cells, they can repair vertebrate hair cells as well."

He suspects the starlet sea anemone proteins might have an effect on some types of human deafness. The two species share a number of common genes, including a gene anemones use to produce the calcium-dependent protein cadherin 23, which forms tip links. Mutations in that gene cause deafness in both mice and humans.

Watson thinks that the next logical research subject would be the mouse, whose genetic code has also been unlocked. He remains hopeful that one day his work might lead to a cure for deafness and other disorders, such as impaired balance. "If you can make new hair cells, as fish do, or if you can keep the hair cells you have from dying, then you can cure deafness."

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