Scientists Sequence Electric Eel Genome

Posted on June 26, 2014

Scientists have sequenced the genome of the electric eel. The researchers say the study identifies the genetic factors and developmental pathways the animals use to grow an organ that can deliver an electric charge. The electric eel can deliver a jolt several times more powerful than the current from a standard household electrical outlet. The research was co-led by Michigan State University, University of Wisconsin-Madison, University of Texas-Austin and the Systemix Institute.

Jason Gallant, MSU zoologist and co-lead author of the paper, says in a statement, "It's truly exciting to find that complex structures like the electric organ, which evolved completely independently in six groups of fish, seem to share the same genetic toolkit. Biologists are starting to learn, using genomics, that evolution makes similar structures from the same starting materials, even if the organisms aren't even that closely related."

The researchers say the ability of electric fish to discharge electricity evolved from muscle cells. All muscle and nerve cells have electric potential. A contraction of a muscle will release a small amount of voltage. Around 100 to 200 million years ago some fish amplified this potential by evolving electrocytes from muscle cells that can generate higher voltages when organized in a sequence.

Lindsay Traeger, U-W graduate student and co-author of the study, says electrocytes push ions across a membrane to create a massive flow of positive charge. Michael Sussman, U-W biochemist, says the "in-series alignment" of the electrocytes and unique polarity of each cell allows for a "summation of voltages" sort of like batteries stacked in series in a flashlight. An electric eel's body contains millions of these "batteries" working together and firing their electric discharge simultaneously.

Sussman also says, "A six-foot eel is a top predator in the water and is in essence a frog with a built-in five-and-a-half-foot cattle prod. Since all of the visceral organs are near the face, the remaining 90 percent of the fish is almost all electric organ."

The electric eel genome research was published here in Science.

ANIMALS
GENOME