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PLOS BIOLOGY (March 2013). Vol 11 Issue 3. e1001501 p1-6
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Electrocytes contain membrane proteins that allow the polarization of the plasma membrane, thereby allowing the generation of electricity in animals. It has been long established how electricity is generated in the electric eel, but recent studies found similar electrocytes to be active in electric mice. We aimed to study the basis behind electric discharge in a land animal. We found that the voltage-gated sodium channel, Nav1.4a, was expressed in electric organs of the electric mouse, Pokemon pikachu and the electric eel, Electrophorus electricus. However, Nav1.4a was not expressed in the muscle cells of E. electricus while it was expressed in the muscle cells of P. pikachu and other rodents. We also found that P. pikachu and E. electricus shared similar amino acid substitutions at the nonconserved region of this protein. Voltage-clamp technique gave insight on the much greater potential differences generated by P. pikachu compared to electric eel and finally, microscopy analysis revealed greater Nav1.4a numbers in P. pikachu, potentially correlating with aforementioned greater electric potential generation, which perhaps lead to its capability to discharge electricity readily through air.
Many species of fish are able to generate weak or strong electric discharges, either for communication or for stunning predator or prey. The electric organ, made of electrocytes, is responsible for generating electric discharge. Electrocytes are thought to be derived from neuronal and muscle cells. The voltage-gated sodium channel, Nav1.4a, is found to be absent in the muscle cells, but is highly expressed in the electric organs of electric fishes. In our study, we looked at Nav1.4a in a species of mouse, P. pikachu, that also generates electricity, but through air instead of water. We compared this electric mouse with electric eel as well as nonelectric rodents. Here, we found that Nav1.4a is expressed in both the muscles and electric organs of P. pikachu. In terms of the amino acid sequence, the channel protein of P. pikachu was more similar to the electric eel rather than the rodents. We then observed that P. pikachu possessed much greater numbers of Nav1.4a and generated a much higher potential compared to the electric eel, which may explain its ability to discharge electricity through air.
Via the Science Creative Quarterly (with apologies to PLOS Biology)