Watson researches sea anemone potential to help hearing loss
At the University of Louisiana at Lafayette, students and staff have the opportunity to conduct research for student projects or based on general interest. Recently, Glen Watson, Ph.D., a biology professor, had a breakthrough with his research on sea anemones. His research was published in “The Journal of Experimental Biology” in August.
Watson, along with assistant biology professor Karen Smith and former UL Lafayette graduate student Pei-Ciao Tang, recently discovered that sea anemones are potentially able to help hearing loss. The goal for this research was to prevent hair cells in humans’ cochleae from dying after experiencing a severe trauma, such as being exposed to a loud noise or an explosion.
“It turns out that sea anemones have — along their tentacles — hair bundle mechanoreceptors that are surprisingly like those that we have in our ears,” Watson said. This was surprising to the researchers because sea anemones are the most primitive animal to have a nervous system.
Sea anemones use their hair bundle mechanoreceptors to detect the movements of their prey. When caught by the anemone, the prey starts to struggle, which destroys some of the mechanoreceptors on their tentacles. In order to survive, sea anemones have evolved with a very sophisticated mechanism by which they can repair those damaged hair bundles. This process takes them a period of about four hours, and they do this by secreting proteins into the water around them. Then, the proteins work outside of the cell to restore the structure of the hair bundles so they work properly. This part of the research took Watson and his team from 1988 to 1998 to discover.
The next step was determining whether or not the proteins that repaired the anemone’s own hair bundles could repair those of another animal. Watson used blind cave fish — fish whose eyes degenerate over time. These fish can be found in caves in the south of Texas or Mexico. Because they are blind, the fish use their hair bundle mechanoreceptors to detect the current or to detect if something is in their path. Some of these blind cave fish were brought into an aquarium to be observed.
“It turns out that the fish spent about 80 percent of their time orienting to the current,” Watson said.
If the fish’s hair cells are destroyed, then it cannot orient to the current. Just like the anemones, it can repair them, but it takes nine days. To see if the anemone’s proteins could speed up the process, a batch of fish whose hair cells were damaged were put into water that had secreted sea anemone proteins. Afterwards, their hair cells were perfect. To be sure they had not made a mistake, they took another batch of fish to test again. This time, half were put in the water, while the other half healed on their own. Those treated with the water were perfect, while those who weren’t treated took the normal nine days to recover. This discovery was made in 2001.
The next step was to see if the proteins would work on mammals — more specifically, baby mice.
“The ability to test on a mammal has only recently become available with the culturing of the cochlea from baby mice,” Watson said. “In this case, they’ll last about a week.”
Tang tested the cochlea for function by intake of a particular dye. The hair cells in the healthy cochleae took up a certain amount of dye, whereas the damaged ones did not do that very well. They were also disorganized in shape. Once the anemone proteins were inserted into the cochlea, they looked close to how they originally were an hour after, and they took up the same amount of dye as the healthy hair cells. This discovery was made in 2014.
“Severe trauma to hair cells results in the death of those hair cells,” said Watson. “But in humans, those hair cells are not repairable.” Therefore, here’s a permanent deficit, and that deficit results in deafness. There are varying forms of deafness, depending on how many hair cells were lost. The proteins would only work on a human if they are inserted in the cochlea as soon as someone has experienced a severe trauma to a very loud noise. The question then becomes: could the sea anemone proteins be delivered to the damaged hair cells in time?
Watson’s long-term hope for this research is that they can offer some help to people who have lost their hearing due to sudden exposure to a very loud noise, because there’s not much help that can be done for them otherwise.