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Electroreception in the Sea Lamprey
Weiming Li 1, Yu-Wen Chung-Davidson 1, and John Teeter 2
1 Department of Fisheries and Wildlife, Michigan State University, East Lansing, MI 48824, U.S.A.
2 Monell Chemical Senses Center, Philadelphia, PA19104, U.S.A.
We characterized the behavioral and brain responses of parasitic sea lampreys (Petromyzon marinus) to weak electric fields. Parasitic sea lampreys showed preferences for the cathodal end of the testing aquarium after electric stimulation. Within a range of cathodal fields (-0.1 to -30 μV/cm), parasitic sea lampreys exhibited increased active behaviors. In contrast, anodal fields decreased most active behaviors below baseline in parasitic sea lampreys. Exposure to electric fields resulted in changes in western blot patterns for the neuronal activity markers Fos, Fos-B and Jun in whole brain homogenate of parasitic sea lampreys. Electric stimulation also increased Fos-B immunoreactivity in the octavolateral and the habenula-fasciculus retroflexus-interpeduncular systems in parasitic sea lampreys. We also characterized the behavioral and endocrine responses of adult sea lampreys to weak electric fields. Adult sea lampreys exhibited limited active behaviors after weak electric field stimulation and they spent most time attached to the wall of the testing arena. Exposure to electric fields resulted in changes in brain lamprey (l) GnRH expression and plasma 15α-hydroxyprogesterone levels in adult sea lampreys. These results suggest that electroreception may temporarily modulate the reproductive systems in adult sea lampreys. On the other hand, larval sea lampreys did not show behavioral responses to weak electric fields.