title: Proton conductivity in ampullae of Lorenzini jelly.
abstract: In 1678, Stefano Lorenzini first described a network of organs of unknown function in the torpedo ray-the ampullae of Lorenzini (AoL). An individual ampulla consists of a pore on the skin that is open to the environment, a canal containing a jelly and leading to an alveolus with a series of electrosensing cells. The role of the AoL remained a mystery for almost 300 years until research demonstrated that skates, sharks, and rays detect very weak electric fields produced by a potential prey. The AoL jelly likely contributes to this electrosensing function, yet the exact details of this contribution remain unclear. We measure the proton conductivity of the AoL jelly extracted from skates and sharks. The room-temperature proton conductivity of the AoL jelly is very high at 2 ± 1 mS/cm. This conductivity is only 40-fold lower than the current state-of-the-art proton-conducting polymer Nafion, and it is the highest reported for a biological material so far. We suggest that keratan sulfate, identified previously in the AoL jelly and confirmed here, may contribute to the high proton conductivity of the AoL jelly with its sulfate groups-acid groups and proton donors. We hope that the observed high proton conductivity of the AoL jelly may contribute to future studies of the AoL function.
authors.affiliation: Department of Electrical Engineering, University of Washington, Seattle, WA 98195, USA.; Department of Materials Science and Engineering, University of Washington, Seattle, WA 98195, USA.
authors.forename: Erik E
authors.identifier: 0000-0002-4034-7303
authors.initials: EE
authors.lastname: Josberger
authors.affiliation: Department of Materials Science and Engineering, University of Washington, Seattle, WA 98195, USA.; Department of Electrical Engineering, University of California, Santa Cruz, Santa Cruz, CA 95064, USA.
authors.forename: Pegah
authors.initials: P
authors.lastname: Hassanzadeh
authors.affiliation: Department of Materials Science and Engineering, University of Washington, Seattle, WA 98195, USA.
authors.forename: Yingxin
authors.identifier: 0000-0003-4091-6462
authors.initials: Y
authors.lastname: Deng
authors.affiliation: Department of Electrical Engineering, University of California, Santa Cruz, Santa Cruz, CA 95064, USA.; Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.
authors.forename: Joel
authors.identifier: 0000-0001-8894-8979
authors.initials: J
authors.lastname: Sohn
authors.affiliation: Benaroya Research Institute, Seattle, WA 98101, USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Rego
authors.affiliation: Benaroya Research Institute, Seattle, WA 98101, USA.; Department of Biology, University of Washington, Seattle, WA 98195, USA.
authors.forename: Chris T
authors.identifier: 0000-0002-3841-989X
authors.initials: CT
authors.lastname: Amemiya
authors.affiliation: Department of Materials Science and Engineering, University of Washington, Seattle, WA 98195, USA.; Department of Electrical Engineering, University of California, Santa Cruz, Santa Cruz, CA 95064, USA.
authors.forename: Marco
authors.initials: M
authors.lastname: Rolandi
mesh_terms: D000818:Animals; D004553:Electric Conductivity; D004555:Electric Fish; D055724:Electrophysiological Phenomena; D011522:Protons; D011984:Sensory Receptor Cells / Q000502:physiology
chemical_list: D011522:Protons
keywords: Ampullae of Lorenzini; Elasmobranchii; Sharks; Skates; electrosensing cells; hydrogels; proton conductors