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KNOXVILLE — Two University of Tennessee scientists are working to develop an inexpensive way of identifying a toxin in contaminated fish that often causes food poisoning in humans.

Drs. Gary Sayler and Steve Ripp have received a $227,037 grant from the U.S. Department of Agriculture to develop organisms that light up in the presence of histamine, a chemical by-product that can taint tuna and other food fish. Sayler and Ripp are researchers in UT’s Center for Environmental Biotechnology.

“Current methods for detecting histamine are costly and complex,” Sayler said. “Right now because of the expense, the U.S. Food and Drug Administration requires that only tuna and mahi-mahi be tested.

“We hope to develop a monitor that will be simple, rapid and inexpensive to use.”

The illness, called scombrotoxicosis or scombroid fish poisoning, is caused when bacteria convert a harmless amino acid in fish muscle into histamine. Symptoms of the disease are typically mild and include diarrhea, nausea, vomiting, abdominal pain and rash. Ripp said the disease usually subsides after a few hours but can continue for several days.

“The Centers for Disease Control ranks seafood as the third most common cause of food-borne disease outbreaks,” Ripp said.

Sayler and Ripp are leaders in developing bioluminescent bioreporters, the “critter on a chip” technology that combines light-sensing electronic circuitry with organisms genetically engineered to emit light in the presence of target substances. The electronic components detect and measure the light emitted by the organisms.

Previous uses for the technology have included organisms that light up in the presence of toxic chemicals in the environment.