UT professor and colleagues find genes behind evolution of electric organs in electric fish

Eunice Ali

A research team led by Harold Zakon, integrative biology and neuroscience professor, discovered how genes and pathways in electric fish caused their electricity-producing organs to evolve independently six times throughout their evolutionary history.

This study, which was initiated around eight years ago, was published in the journal “Science” on June 27.

“My colleagues and I are very proud,” Zakon said. “‘Science’ is one of the premier journals in [the sciences].”

Zakon said that many traits in most animals, including mammals, evolved only once throughout the evolutionary history.

“Evolutionary biologists are always interested in knowing how things evolved,” Zakon said. “Vertebrate limbs evolved once. Our teeth and hair [also] evolved once. In this case, you would never ask, ‘would’ve it evolved the same way at another time?’”

The study found electric fish were shown to be different. Their muscles, which developed into electricity-producing organs, evolved six times independently. Now that they have identified the genes expressed in these electric organs, Zakon and his colleagues plan to manipulate those genes in the muscles of a standard lab fish. Zakon said this will cause some of those genes to be expressed at higher levels and some others at lower levels, resembling the evolutionary process in the electric organs.

“This will give us a much stronger sense of proof that these genes are in fact the ones that make the electric organs,” Zakon said. “One very far out idea is people can have their own bio-batteries, say, heart pacemakers. [We can] make human cells into electric-organ cells [by constructing] little implantable bio-batteries.”

For the study, Zakon worked with Manoj Samanta of the Systemix Institute in Washington and Michael Sussman, University of Wisconsin-Madison biochemistry professor.

“I do want to stress that this is a group effort,” Sussman said. “We met on the phone every week. It [wasn’t always] easy, but we hung in there.”

Neuroscience senior Evan DeLord, who took an evolutionary biology class taught by Zakon last semester, experienced firsthand Zakon’s passion for electric fish.

“He’s a humble, but awesome, disciple of Charles Darwin,” DeLord said. “He’s just in love with evolution and the natural world.”