Receptor sites for amino acids in the facial taste system of the channel catfish

Wegert, Sandra; Caprio, John

doi:10.1007/bf00218412

Cited by 37 publications

(35 citation statements)

References 20 publications

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“…However, fish detect amino acids not only by T1R1/3 but also by multiple T1R2/3s. This is consistent with the experimental data that fish have multiple amino acid receptors in their taste systems (Kanwal et al, 1987;Wegert and Caprio, 1991;Finger et al, 1996;Caprio, 1999, 2000). The finding that the receptors of L-Ala and L-Arg exist in different taste cells of channel catfish (Finger et al, 1996) may be explained by the existence of T1R1/3 and T1R2/3, although some reports suggest the existence of the ligandgated ion channel in channel catfish as the L-Arg receptor (Teeter et al, 1990;Grosvenor et al, 2004).…”

Section: Discussionsupporting

confidence: 91%

Characterization of Ligands for Fish Taste Receptors

Oike¹,

Nagai²,

Furuyama³

et al. 2007

J. Neurosci.

149

157

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Recent progress in the molecular biology of taste reception has revealed that in mammals, the heteromeric receptors T1R1/3 and T1R2/3 respond to amino acids and sweeteners, respectively, whereas T2Rs are receptors for bitter tastants. Similar taste receptors have also been characterized in fish, but their ligands have not been identified yet. In the present study, we conducted a series of experiments to identify the fish taste receptor ligands. Facial nerve recordings in zebrafish (Danio rerio) demonstrated that the fish perceived amino acids and even denatonium, which is a representative of aversive bitter compounds for mammals and Drosophila. Calcium imaging analysis of T1Rs in zebrafish and medaka fish (Oryzias latipes) using an HEK293T heterologous expression system revealed that both T1R1/3 and a series of T1R2/3 responded to amino acids but not to sugars. A triple-labeling, in situ hybridization analysis demonstrated that cells expressing T1R1/3 and T1R2/3s exist in PLC␤2-expressing taste bud cells of medaka fish. Functional analysis using T2Rs showed that zfT2R5 and mfT2R1 responded to denatonium. Behavior observations confirmed that zebrafish prefer amino acids and avoid denatonium. These results suggest that, although there may be some fish-specific way of discriminating ligands, vertebrates could have a conserved gustatory mechanism by which T1Rs and T2Rs respond to attractive and aversive tastants, respectively.

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Section: Discussionsupporting

confidence: 91%

Characterization of Ligands for Fish Taste Receptors

Oike¹,

Nagai²,

Furuyama³

et al. 2007

J. Neurosci.

149

157

View full text Add to dashboard Cite

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“…Such a fixed order of stimulus efficacies was found also in Tau sensitive cells in Panulirus argus (Fuzessery et al 1978) and in Arg cells in crayfish dactyl chemoreceptors (Bauer et al 1981) and may imply a single broadly tuned receptor. Overall our results of multiple, independent receptors speak against the idea of a few broadly tuned receptor sites for basic and neutral amino acids as argued from studies in catfish (Bruch and Rulli 1988;Caprio et al 1989;Wegert and Caprio 1991).…”

Section: Hyp-best Cell Comparisoncontrasting

confidence: 58%

Tuning of chemoreceptor cells of the second antenna of the American lobster (Homarus americanus) with a comparison of four of its other chemoreceptor organs

Voigt

Atema

1992

J Comp Physiol A

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Summary. 1. We determined the spectral tuning properties of 47 chemoreceptor cells of the antenna of Homarus americanus to amino acids and other compounds. Tests with 17 single compounds at 10 -4 M showed 40 of 47 cells responded best to hydroxyproline, 4 cells to taurine and 3 cells to betaine. Mean tuning breadth (H-metric) doubled with 10 fold increase in concentration.2. In hydroxyproline-best cells the mean threshold for hydroxyproline (Hyp) was found between 10 -7 M and 10 -8 M. An equimolar mixture of the 17 compounds generated a shallower stimulus-response function with thresholds similar to Hyp function (mixture suppression). Hyp-best cells were relatively narrowly tuned, often with arginine or leucine as second best stimuli.3. Thus, physiologically the second antenna of H. americanus is a major chemoreceptor organ. It is more than any of the 5 chemoreceptor organs studied so far dominated by a single best-cell type (Hyp). Receptor cell composition of antennae resembles that of antennules more than legs or maxillipeds. Hyp-best cells in antennae and lateral antennules have similar tuning spectra. 4. Our cell tuning studies argue for independent receptors for all amino acids tested. We conclude that diversity of receptor cell tuning is created by cell-specific blends of receptors. At the organ level, differences in organ tuning result from different blends of receptor cells.

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“…In addition, crossadaptation experiments have revealed a 'generalized reduction effect', in which there is always some basal reduction in the response to a chemical following adaptation to any other chemical. In the taste and olfactory systems of catfish, this generalized reduction effect is usually between 10-50%, and occurs even if the two compounds mediate their excitatory effects through different receptor sites (Caprio and Byrd 1984;Bryant et al 1989;Wegert and Caprio 1991;Michel et al 1993b). A similar generalized reduction effect during cross-adaptation experiments has been observed in taste and olfaction in clawed lobsters Johnson et al 1989) and olfaction in spiny lobsters (Daniel et al 1994).…”

Section: Physiological Correlates Of Binding Inhibition Between Mixtumentioning

confidence: 64%

“…Cross-adaptation experiments on chemosensory systems of a number of species have been used to identify specific compounds that cause cross-adaptational reduction in responses due to competitiv e binding to the same receptor sites Wegert and Caprio 1991;Michel et al 1993b). In addition, crossadaptation experiments have revealed a 'generalized reduction effect', in which there is always some basal reduction in the response to a chemical following adaptation to any other chemical.…”

Section: Physiological Correlates Of Binding Inhibition Between Mixtumentioning

confidence: 99%

Inhibition of taurine and 5?AMP olfactory receptor sites of the spiny lobster Panulirus argus by odorant compounds and mixtures

Olson

Derby

1995

J Comp Physiol A

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1. The effects of the odorant compounds adenosine-5'-monophosphate (5'AMP), ammonium, betaine, L-cysteine, L-glutamate, DL-succinate, and taurine and of mixtures of these compounds on binding of taurine and 5'AMP to dendritic membrane from the olfactory organ of spiny lobsters (Panulirus argus) were quantified to evaluate the contribution of inhibition of odorant-receptor binding to the generation of physiological responses to mixtures. 2. Taurine binding sites belong to two affinity classes, while 5'AMP binding sites belong to a single affinity class. Binding of either taurine or 5'AMP was partially inhibited in an apparently noncompetitive, concentration dependent fashion by most odorant compounds, with 25-40% inhibition by 1 mM of odorant. Mixtures of two or more odorant compounds also inhibited binding of taurine or 5'AMP to its sites. However, the inhibition by mixtures was often significantly less than expected from the inhibition produced by a mixture's components assuming either a noncompetitive or competitive mechanism. 3. By including this binding inhibition between compounds into models for predicting physiological responses to mixtures from the responses to the components, the predictive power of the models is significantly improved. This result strongly suggests that binding inhibition can influence the physiological responsiveness of chemoreceptor cells to mixtures.

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Receptor sites for amino acids in the facial taste system of the channel catfish

Cited by 37 publications

References 20 publications

Characterization of Ligands for Fish Taste Receptors

Characterization of Ligands for Fish Taste Receptors

Tuning of chemoreceptor cells of the second antenna of the American lobster (Homarus americanus) with a comparison of four of its other chemoreceptor organs

Inhibition of taurine and 5?AMP olfactory receptor sites of the spiny lobster Panulirus argus by odorant compounds and mixtures

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