UT Austin scientists discover secrets behind the evolution of electric fish: 'We can see how a small change in the gene can completely change where it’s expressed'

UT Austin researchers confirmed that the genetic control region they discovered only controls the expression of a sodium channel gene in muscle and no other tissues. In this image, a green fluorescent protein lights up only in the trunk muscle of a developing zebrafish embryo.

Researchers from The University of Texas at Austin and Michigan State University have discovered how electric fish, such as the electric eel, evolved electric organs through small genetic changes.

The findings, published in Science Advances, reveal that electric fish turned off one duplicate of the sodium channel gene in muscles and turned it on in other cells, which created a new organ capable of sending and receiving signals akin to bird songs. The researchers discovered a short section of the sodium channel gene that controls whether the gene is expressed in any given cell. In electric fish, this control region is either altered or entirely missing, which explains why one of the two sodium channel genes is turned off in the muscles of electric fish.

The implications of this finding could help scientists to identify the genetic mutations behind some human diseases. The study’s senior authors are Harold Zakon, professor of neuroscience and integrative biology at The University of Texas at Austin; Johann Eberhart, a professor of molecular biosciences at UT Austin; and Jason Gallant, associate professor of integrative biology at Michigan State University.

"This is exciting because we can see how a small change in the gene can completely change where it’s expressed," Zakon said.