Sharks 'untapped resource' for medicine, researcher says

Robert Henry Becker Arizona Daily Wildcat Sam Schluter, research assistant professor in microbiology and immunology holds DNA taken from sharks. Shark DNA is similar to that of human DNA and may help scientists to better understand the human immune system.

"Sharks are an untapped resource for new antibiotics," said John Marchalonis, head of the microbiology and immunology department at the University of Arizona.

Marchalonis is directing a laboratory at the College of Medicine, researching sharks' primitive antibodies, proteins produced by the body's immune system as a defense against foreign bacteria and viruses.

Marchalonis' research could be used to better understand the human body's immune response to autoimmune diseases and disorders where the immune system works against the body.

His lab has brought in over $1.5 million in federal research grants, primarily from the National Institute of Health and the National Science Foundation. His lab obtained $330,000 last August from the National Science Foundation to continue its research.

Marchalonis said molecular biology and immunology research is done everywhere.

"This is a university that has very strong programs in neurobiology," he said.

Marchalonis began his research 30 years ago at Yale University.

"I was the first to find sharks had antibodies that were structurally very simple, very similar to ours," he said.

Sharks are the most primitive, jawed vertebrates, Marchalonis said. Their immune system closely resembles that of a human fetus. However, the human's immune system becomes more complex with age, which allows for higher vulnerability to certain attacks.

Marchalonis said he primarily wants to know, "How did the (immune) system start?"

Scientists can get a better perspective on how the human immune system works by researching sharks' systems, as opposed to studying the human system alone.

Marchalonis' lab focuses on large sharks, including Galapagos, Tiger, Sandbar and Great White sharks, said Sam Schluter, a research assistant professor in microbiology and immunology.

The lab analyzes the DNA sequence of genes responsible for directing the production of antibodies.

Three major breakthroughs have been made in shark research since Marchalonis came to the UA in 1989.

Valerie Hohman, a former UA graduate student who is doing postdoctoral work at the American Cancer Society at the Massachusetts Institute of Technology, discovered a similarity between the arrangement of human and shark gene chains.

Ralph Bernstein, another former UA graduate student, now doing postdoctoral work at the Food and Drug Administration, discovered the gene responsible for "recognizing" pathogens, foreign bacteria and viruses. This gene "scrambles" gene segments, making it possible to recognize more pathogens through different gene combinations.

He showed these genes were analogous to human and bacteria genes also responsible for "recombination" of gene segments.

The third breakthrough was made by a former honors undergraduate in chemistry. Paul Sarazin showed sharks have natural antibodies to HIV, the virus which is often the forerunner to AIDS.

Kathy Zast, Marchalonis' lab manager, said all of the students previously working with his research have graduated.

"We're waiting to hear about grant funding before we hire more students," Zast said.

She added one way undergraduates can get involved is through the Undergraduate Biology Research Program.

Marchalonis said his lab has two goals. The first is to continue studying the gene segment recombination process in both sharks and humans. The second goal is to extend the lab's studies to include gene organization, autoimmunolgy and research against infections.

The problem with studying methods to combat viruses is that they mutate between infections, Marchalonis said. The body can only eliminate 99 percent of a virus infection. The other 1 percent can mutate enough so the human body can't recognize it before a second infection.

In the case of AIDS, there are a variety of viruses.

"Immunologists are always a step behind," Marchalonis said.

He said it is possible that shark antibodies will pick up all or most of the HIV antigens.

Shark research could lead to new understandings in human autoimmunity as well as developments in human immune systems, he said.

Marchalonis added that the tissue materials the lab uses to extract DNA comes from sharks that are accidentally killed during routine captures when scientists obtain population data.

"We don't actually go out and kill the sharks," Schluter said.

Marchalonis added, "They're very fragile."

Their population is rapidly declining due to over fishing, he said.

"Our department has a very active graduate program," Marchalonis said.

The department has graduated 28 people with doctorate degrees in the last four years, all of whom have jobs.