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Fish used to research immunity, pathogens at University Medical Center

Catfish in the basement?

The Mississippi Delta is not the only place where one can find catfish living in a mad-made environment. The University of Mississippi Medical Center (UMC) has approximately 150 of the bottom-feeders swimming around in its basement.

Catfish in UMC’s basement?

It is true, and has been for the last 30 years. UMC is using the fish to research their immune system and the genes that support that system, important work not only for the science community as a whole, but also for the catfish industry.

While UMC researchers studying catfish may sound unlikely, the work has proven a success, and has launched the career of many microbiologists. Over the years, dozens of students have participated in the research.

“A large number of our students have stayed in an academic setting,” said Dr. Norman Miller, who has been working on the catfish project since its inception in 1979. “I guess this work lit a fire under them. It’s very satisfying to see your students go on to do rewarding, important work.”

The project began with the late Dr. Bill Clem, who came to UMC from the University of Florida. While in Florida, Clem began studying sharks and other aquatic life. When he came to Mississippi, he asked what fish is important to the Magnolia State, and the answer he got was catfish.

Today, Miller, who is retiring in June, along with Dr. Gregory Chinchar, UMC professor of microbiology, Dr. Mel Wilson, Dr. Eva Bengten and six doctoral candidates are still studying the immune system of the channel catfish. Some of this work involves understanding just how catfish’s immune system works; other efforts focus on how pathogens such as the channel catfish virus are controlled.

Catfish have proven a great test bed for immunity research. As Bengten points out, catfish thrive in a muddy, murky environment, yet are affected by relatively few pathogens. Unlocking the mysteries of the fish’s immune system could provide information that helps not only catfish, but also other organisms, including humans, cope with their environment.

Another plus in studying catfish, and one of the discoveries UMC researchers made, was that catfish cells have “spontaneous immortalization.” When catfish cells are extracted and placed in a culture, they continue to grow. (Miller spent his first two years on the project learning how to grow catfish tissue in a lab dish.) Thus, researchers are afforded a large number of cells from which to work.

Researchers, through an ingenious process of introducing radiated sperm into fertilized cells, thus “tricking” the eggs into believing that fertilization has taken place, has allowed them to work from “cloned” fish, giving them highly controlled subjects. Thus, researchers can mismatch genes, look at the effect this has, and draw firm conclusions about how the fish’s immunity works and how it defends against pathogens.

The catfish cell lines, first isolated by Miller, are supplied to research institutions around the globe. UMC scientists, over the program’s history, have published approximately 250 papers and articles on catfish-immune responses alone.

However, the work has been beneficial and applicable here at home. A good example is work researchers did on winter kill.

Every winter, catfish producers lost large amounts of their fish, and no one was quite sure why. UMC researchers discovered that when temperatures fall, the fish’s cells were affected, losing some of their ability to fight off diseases. At the same time, a fungus-like organism found to be responsible for killing the fish thrived in the cooler waters.

Researchers found an answer close to the farm. A herbicide catfish farmers were already using, but only in the summer, killed the lethal organisms. It was applied to ponds in the winter, and the seasonal kill was stopped.

Wilson points out that UMC’s work generally is basic science. It is not transitional science — looking at a specific problem or disease and trying to find an answer or antidote. While she said transitional science is important, often it is limited because of a lack of broader knowledge. The work to develop anti-HIV vaccines has been hindered by this lack of a broader understanding, she says.

All of the researchers believe that their work, indeed, could one day lead to the cure for many diseases that afflict humans such as AIDS. They are quick to emphasize that fruit fly research has led to a plethora of breakthroughs in understanding cancer. In that light, catfish research that could make humans healthier is not farfetched at all. The precedent has already been set.

With 30 years under its belt, the catfish project is far from complete. One goal the researchers said they would like to see completed is the development of the catfish genome expression map. That could come as quickly as two years, but Miller said other work could go on for decades to come.

Contact MBJ staff writer Wally Northway at wally.northway@msbusiness.com.

About Wally Northway

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