Chemosensory Ion Channels in Amphibian Skins

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Amphibians are unique among the vertebrates in obtaining salt and water by absorption across the skin rather than by mouth. To do this, toads adopt a characteristic behavior, called the water-absorption response, pressing the belly to a moist surface. The ability of some toads to survive in desert environments requires them to correctly identify surfaces where water is available, and not filled inappropriately with salts. The toad skin appears to serve an analogous function to the way the tongue tastes solutions before swallowing. This project tests the novel hypothesis that the cellular process of tasting sodium salts by the toad skin is similar to that for taste bud cells in the tongue. This project uses desert toads to evaluate the process of salt taste transduction at the behavioral, cellular, and neurophysiological levels in this unique model system. Results will clarify how cells at the surface of an animal can communicate the salt content of water in the environment to the nervous system, to allow a decision of how to utilize that water. This work will have an impact beyond neuroscience on general physiology, in clarifying perception is coupled to behavior to maintain water and salt balance. Results will also be important for environmental biology, in clarifying how amphibians tolerate extremes in water availability and water quality, and how environmental degradation may affect survival of amphibian populations.