First published online May 8, 2007
Journal of Experimental Biology 210, 1776-1785 (2007)
Published by The Company of Biologists 2007
doi: 10.1242/jeb.001727
Chemosensory reception, behavioral expression, and ecological interactions at multiple trophic levels
Ryan P. Ferrer1 and
Richard K. Zimmer1,2,*
1 Department of Ecology and Evolutionary Biology, University of California,
Los Angeles, California 90095-1606, USA
2 Neurosciences Program and Brain Research Institute, University of
California, Los Angeles, California 90095-1606, USA

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Fig. 2. (A) Tested adult newts inhabited stream pools along a 4 km stretch of Tuna
Canyon Creek in Malibu, California, USA. In each 5-min trial, an investigator
hid behind rock boulders that lined the stream, and continuously released
solution (treatment or control) though transparent polyethylene tubing. The
tip of the tubing was placed, nominally, 30 cm upstream of a free-ranging
adult newt. (BE) Successive images (at 3 s intervals) showing an adult
(gray arrow) detecting an attractant (arginine, at 105 mol
l1) odor plume, turning, and swimming upstream to the source
(white open circle). The principal along-channel axis of stream flow is
denoted by a white arrow.
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Fig. 3. Percentage of newts swimming upstream to the site of amino acid or stream
water (control) release. Each compound was tested at 105 mol
l1; functional groups are illustrated above respective bars.
Arg, arginine; Ala, alanine; Gly, glycine; Tau, taurine; Glu, glutamate; Lys,
lysine; Cys, cysteine; Leu, leucine; Phe, phenylalanine; Met, methionine; Asp,
aspartate; Trp, tryptophan; Val, valine; WF, worm fluids with a corresponding
arginine concentration of 105 mol l1).
Asterisks denote a significant difference between larval responses to test and
control (stream water) solutions, using a Fisher exact test
(P<0.05).
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Fig. 4. Effects of concentration of arginine on percentage of newts swimming
upstream (open circles) to the site of solution release. Stream water (striped
triangle) and worm fluids (closed square; with a corresponding arginine
concentration of 105 mol l1) served as
controls. Concentrations are not corrected for dilution associated with
chemical release and delivery.
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Fig. 5. Percentage of newts swimming upstream to the site of arginine analog or
control (stream water) solution release. Each compound was tested at
105 mol l1, with separate experiments
performed for (A) carboxyl substitutions, (B) amine substitutions, (C) carbon
chain substitutions, and (D) guanidinium substitutions. Arg, arginine; Guan,
guanidine; AGB, agmatine; AME, arginine methyl ester; GAA, guanidinacetate;
GBA, guanidinobutyrate; HA, homoarginine; AGPA,
-amino-ß-guanidinopropionate; Lys, lysine; NA,
N- -nitro-L-arginine; NV, norvaline. Asterisks
denotes a significant difference between larval responses to test and control
(stream water) solutions, using a Fisher exact test (P<0.05).
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Fig. 6. Percentage of newts swimming upstream to the site of 105
mol l1 arginine or stream water (control) release. Inert
silicon gel was applied either to the forehead (control) or to the nares of
newts to block the nasal cavities. Asterisk denotes a significant difference
between newt responses to arginine and control (stream water) solutions, using
a Fisher exact test (P<0.01).
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Fig. 7. Schematic depiction of predatorprey interactions involving
Taricha torosa, and the chemosensory cues that mediate them. Arg,
arginine; TTX, tetrodotoxin. This graphic summarizes combined results from
eight published investigations (Elliot et
al., 1993 ; McAllister et al.,
1997 ; Kerby and Kats,
1998 ; Mobley and Stidham,
2000 ; Brodie et al.,
2005 ; Zimmer et al.,
2006 ; Ferrer and Zimmer,
2007 ) (present study).
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© The Company of Biologists Ltd 2007