HR: 10:45h
AN: NB22D-02    [Abstracts]
TI: Arginine: A Potent Prey Attractant to Predatory Newts in Mountain Streams
AU: * Ferrer, R P
EM: rferrer@ucla.edu
AF: University of California, Los Angeles, Department of Ecology and Evolutionary Biology 621 Charles E. Young Drive South, Los Angeles, CA 90095-1606 United States
AU: Zimmer, R K
EM: z@biology.ucla.edu
AF: University of California, Los Angeles, Department of Ecology and Evolutionary Biology 621 Charles E. Young Drive South, Los Angeles, CA 90095-1606 United States
AB: Chemoreception of aquatic organisms has been well-studied in the laboratory, but rarely in the field. The California newt, Taricha torosa, in natural stream habitats is an excellent animal for exploring behavioral responses to prey odors. Here, we selected 13 amino acids for field bioassays based on their concentrations in prey tissue extracts. Bioassays were calibrated for stimulus dilution by means of fluorescent dye releases and flow-through spectrofluorometry. Moreover, hydrodynamic properties of stream flows were determined using an electromagnetic current meter. Of all amino acids tested, only arginine, alanine and glycine were significantly attractive (relative to stream water controls). These three substances caused free-ranging newts to turn upstream and swim towards the odor sources. Additional experiments showed that arginine was the most effective attractant, evoking plume-tracking behavior at concentrations as low as 10 nM. In subsequent trials, nine arginine analogs were tested, but each compound failed to elicit a significant response. Even subtle changes to arginine, such as the addition of a single carbon to the side chain, destroyed all bioactivity. Within its natural habitat, the California newt thus exhibits keen sensitivity and narrow tuning to the free amino acid, arginine, a chemical signal of its prey.
DE: 4899 General or miscellaneous
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly