Scientists find how electric fish got its jolt

Scientists, including one of Indian-origin, have found how the electric fish evolved its jolt which can be several times more powerful than standard household current.
Researchers have identified 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.
"These fish have converted a muscle to an electric organ," said Michael Sussman of the University of Wisconsin-Madison.
Sussman led the study along with Harold Zakon of the University of Texas at Austin and Manoj Samanta of the Systemix Institute in Redmond, Washington.

The study 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.
"The surprising result of our study is that electric fish seem to use the same 'genetic toolbox' to build their electric organ, despite the fact that they evolved independently," said Jason Gallant, an assistant professor of zoology at Michigan State University.

Worldwide, there are hundreds of electric fish in six broad lineages. Charles Darwin himself cited electric fishes as critical examples of convergent evolution, where unrelated animals independently evolve similar traits to adapt to a particular environment or ecological niche.

The new work, which includes the first draft assembly of the complete genome of an electric fish, the South American electric eel, identifies the genetic factors and developmental paths the animals used to create an organ that, in some instances, can deliver a jolt several times more powerful than the current from a standard household electrical outlet.
In addition to sequencing and assembling DNA from the electric eel genome, the team produced protein sequences from the cells of the electric organs and skeletal muscles of three other electric fish lineages using RNA sequencing and analysis.
A computationally intense comparative study of the sequences showed that electric organs in fish worldwide used the same genetic tools and cellular and developmental pathways to independently create the electric organ.