Classes and Narrowing Selectivity of Olfactory Receptor Neurons of <i>Xenopus laevis</i> Tadpoles

Manzini, Ivan; Schild, Detlev

doi:10.1085/jgp.200308970

Cited by 49 publications

(80 citation statements)

References 32 publications

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“…[Ca 2ϩ ] i imaging is a well established tool to reveal the sensitivity to odors (28), but it gives no direct information regarding whether the signal is relayed to higher brain centers. This can be concluded unambiguously only by directly measuring electrical activity of individual cells.…”

Section: Discussionmentioning

confidence: 99%

Cannabinoid action in the olfactory epithelium

Czesnik¹,

Schild

Kuduz³

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

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The perception of odors is influenced by a variety of neuromodulators, and there is growing evidence that modulation already takes place in the olfactory epithelium. Here we report on cannabinergic actions in the olfactory epithelium of Xenopus laevis tadpoles. First we show that CB1 receptor-specific antagonists AM251, AM281, and LY320135 modulate odor-evoked calcium changes in olfactory receptor neurons. Second, we localize CB1-like immunoreactivity on dendrites of olfactory receptor neurons. Finally, we describe the cannabinergic influence on odor-induced spike-associated currents in individual olfactory receptor neurons. Here we demonstrate that the cannabinergic system has a profound impact on peripheral odor processing and discuss its possible function.CB1 antagonist ͉ dendrite ͉ modulation ͉ odor processing ͉ olfactory receptor neuron

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Section: Discussionmentioning

confidence: 99%

Cannabinoid action in the olfactory epithelium

Czesnik¹,

Schild

Kuduz³

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

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“…Notably, vomeronasal cells of some reptile species detect arginine (Hatanaka, 1990). Sensitivity to this compound in amphibians is, however, attributed to olfaction (Vogler and Schild, 1999;Manzini and Schild, 2004).…”

Section: Discussionmentioning

confidence: 99%

The scent of danger: arginine as an olfactory cue of reduced predation risk

Ferrer

Zimmer

2007

Journal of Experimental Biology

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SUMMARY Animal perception of chemosensory cues is a function of ecological context. Larvae of the California newt (Taricha torosa), for example, exhibit predator-avoidance behavior in response to a chemical from cannibalistic adults. The poison tetrodotoxin (TTX), well known as an adult chemical defense, stimulates larval escape to refuges. Although they are cannibals,adult newts feed preferentially on worms (Eisenia rosea) over conspecific young. Hence, larval avoidance reactions to TTX are suppressed in the presence of odor from these alternative prey. The free amino acid,arginine, is abundant in fluids emitted by injured worms. Here, we demonstrate that arginine is a natural suppressant of TTX-stimulated larval escape behavior. Compared to a tapwater control, larvae initiated vigorous swimming in response to 10–7 mol l–1 TTX. This excitatory response was eliminated when larval nasal cavities were blocked with an inert gel, but not when gel was placed on the forehead (control). In additional trials, a binary mixture of arginine and 10–7 mol l–1 TTX failed to induce larval swimming. The inhibitory effect of arginine was, however, dose dependent. An arginine concentration as low as 0.3-times that of TTX was significantly suppressant. Further analysis showed that suppression by arginine of TTX-stimulated behavior was eliminated by altering the positively-charged guanidinium moiety, but not by modifying the carbon chain, carboxyl group, or amine group. These results are best explained by a mechanism of competitive inhibition between arginine and TTX for common, olfactory receptor binding sites. Although arginine alone has no impact on larval behavior, it nevertheless signals active adult predation on alternative prey, and hence, reduced cannibalism risk.

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“…As a function of larval age, olfactory receptor neurons in Xenopus laevis increase specificity for certain amino acids. This finding suggests an ontogenetic shift in patterns of receptor protein expression (Manzini and Schild, 2004). Furthermore, frog olfactory epithelium and olfactory bulb undergo extreme reorganization to accommodate the transition from a totally aquatic larva to a semi-terrestrial adult form (Altner, 1962;Freitag et al, 1995;Reiss and Burd, 1997).…”

Section: The Ontogenetic Basis For Shifts In Chemosensory Receptionmentioning

confidence: 95%

“…Both olfactory and vomeronasal organs are housed in the nasal cavity (Døving et al, 1993;Døving and Trotier, 1998). Although vomeronasal sensory cells of some reptiles detect arginine (Hatanaka, 1990), chemosensitivity to this compound in amphibians is attributed at present to olfaction (Vogler and Schild, 1999;Manzini and Schild, 2004).…”

Section: The Ontogenetic Basis For Shifts In Chemosensory Receptionmentioning

confidence: 99%

Chemosensory reception, behavioral expression, and ecological interactions at multiple trophic levels

Ferrer

Zimmer

2007

Journal of Experimental Biology

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SUMMARY Chemoreception may function throughout an entire animal lifetime, with independent, stage-specific selection pressures leading to changes in physiological properties, behavioral expression, and hence, trophic interactions. When the California newt (Taricha torosa) metamorphoses from an entirely aquatic larva to a semi-terrestrial juvenile/adult form, its chemosensory organs undergo dramatic reorganization. The relationship between newt life-history stage and chemosensory-mediated behavior was established by comparing responses of adults (as determined here) to those of conspecific larvae (as studied previously). Bioassays were performed in mountain streams,testing responses of free-ranging adults to 13 individual l-amino acids. Relative to stream water (controls), adults turned immediately upcurrent and moved to the source of arginine, glycine or alanine release. These responses were indicative of predatory search. Arginine was the strongest attractant tested, with a response threshold (median effective dose)of 8.3×10–7 mol l–1 (uncorrected for dilution associated with chemical release and delivery). In contrast to adult behavior, arginine suppressed cannibal-avoidance and failed to evoke search reactions in larvae. For a common set of arginine analogs, the magnitudes of adult attraction and larval suppression were not positively correlated. Suppression of cannibal-avoidance behavior in larvae was unaffected by most structural modifications of the arginine molecule. Adult behavior, on the other hand, was strongly influenced by even subtle alterations in the parent compound. Reactions to arginine in both adults and larvae were eliminated by blocking the external openings of the nasal cavity. Stimulating adult predatory search in one case and inhibiting larval cannibal avoidance in the other, arginine is a chemical signal with opposing behavioral effects and varying ecological consequences. Significant differences between responses of adults and larvae to changes in arginine structure suggest alternative, chemosensory receptor targets. Although arginine reception functions throughout an entire newt lifetime, an ontogenetic shift in larval and adult chemoreceptive ability changes behavioral expression, and thus, reflects the unique selection pressures that act at each life-history stage.

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Classes and Narrowing Selectivity of Olfactory Receptor Neurons of Xenopus laevis Tadpoles

Cited by 49 publications

References 32 publications

Cannabinoid action in the olfactory epithelium

Cannabinoid action in the olfactory epithelium

The scent of danger: arginine as an olfactory cue of reduced predation risk

Chemosensory reception, behavioral expression, and ecological interactions at multiple trophic levels

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