The shocking truth about electric fish: Sequencing electric eel genome

Writing June 27, 2014 in the journal Science, a team of researchers led by Michael Sussman of the University of Wisconsin-Madison, Harold Zakon of the University of Texas at Austin and Manoj Samanta of the Systemix Institute in Redmond, Washington identifies the regulatory molecules involved in the genetic and developmental pathways that electric fish have used to convert a simple muscle into an organ capable of generating a potent electrical field.

The work establishes the genetic basis for the electric organ, an anatomical feature found only in fish and that evolved independently half a dozen times in environments ranging from the flooded forests of the Amazon to murky marine environments.

"These fish have converted a muscle to an electric organ," explains Sussman, a professor of biochemistry and director of the UW-Madison Biotechnology Center, who first undertook the exploration of the electric organ almost a decade ago. The study published in Science provides evidence to support the idea that the six electric fish lineages, all of which evolved independently, used essentially the same genes and developmental and cellular pathways to make an electric organ, needed for defense, predation, navigation and communication.

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New genus of electric fish discovered in remote Guyana

Electric eel doesn't stun prey

October 2013. A previously unknown genus of electric fish has been identified in a remote region of South America by a team of international researchers including University of Toronto Scarborough (UTSC) professor Nathan Lovejoy.

The Akawaio penak, a thin, eel-like electric fish, was discovered in the shallow, murky waters of the upper Mazaruni River in northern Guyana. Lovejoy's team at UTSC analyzed tissue samples collected during a recent expedition by a researchers led by Hernán López-Fernández at the Royal Ontario Museum. By sequencing its DNA and reconstructing an evolutionary tree, Lovejoy's team discovered the fish is so distinct it represents a new genus, the taxonomic classification level above species.

Biological diversity hotspot

The upper Mazaruni River is a hotspot for biological diversity, yet remains largely unexplored because of its remote location. The area contains countless rivers on top of a series of uplands that have remained isolated from the rest of South America for more than 30 million years.

"The fact this area is so remote and has been isolated for such a long time means you are quite likely to find new species," says Lovejoy. Like other electric knifefish, Akawaio penak has a long organ running along the base of the body that produces an electric field. The electric field is too weak to stun prey but is instead used to navigate, detect objects and to communicate with other electric fish. This trait is advantageous given the murky habitats of the fish.

Gold mining degradation

The species is named in honour of the Akawaio Amerindians that populate the upper Mazaruni. The region is increasingly suffering from freshwater habitat degradation as a consequence of gold-mining in the area.

"The Mazaruni contains many unique species that aren't found anywhere else in the world. It's an extremely important area in South America in terms of biodiversity," says Lovejoy.

The results of the discovery are published in the recent edition of the journal Zoologica Scripta.

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