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The full repertoire of Drosophila gustatory receptors for detecting an aversive compound.

Shim J, Lee Y, Jeong YT, Kim Y, Lee MG, Montell C, Moon SJ - Nat Commun (2015)

Bottom Line: Furthermore, misexpression of all three Grs enables salt- or sweet-sensing GRNs to respond to L-canavanine.Introduction of these Grs in sweet-sensing GRNs switches L-canavanine from an aversive to an attractive compound.We conclude that three GRs collaborate to produce a functional L-canavanine receptor.

View Article: PubMed Central - PubMed

Affiliation: Department of Oral Biology, BK21 PLUS Project Yonsei University College of Dentistry, Yonsei-ro 50-1, Seodaemun-gu, Seoul 120-752, Korea.

ABSTRACT
The ability to detect toxic compounds in foods is essential for animal survival. However, the minimal subunit composition of gustatory receptors required for sensing aversive chemicals in Drosophila is unknown. Here we report that three gustatory receptors, GR8a, GR66a and GR98b function together in the detection of L-canavanine, a plant-derived insecticide. Ectopic co-expression of Gr8a and Gr98b in Gr66a-expressing, bitter-sensing gustatory receptor neurons (GRNs) confers responsiveness to L-canavanine. Furthermore, misexpression of all three Grs enables salt- or sweet-sensing GRNs to respond to L-canavanine. Introduction of these Grs in sweet-sensing GRNs switches L-canavanine from an aversive to an attractive compound. Co-expression of GR8a, GR66a and GR98b in Drosophila S2 cells induces an L-canavanine-activated nonselective cation conductance. We conclude that three GRs collaborate to produce a functional L-canavanine receptor. Thus, our results clarify the full set of GRs underlying the detection of a toxic tastant that drives avoidance behaviour in an insect.

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Attraction to L-canavanine induced by ectopic expression of Grs in sugar-sensing GRNs.Two-way choice assays testing for attraction or aversion to L-canavanine in flies misexpressing Gr8a, Gr66a and Gr98b in sweet-sensing GRNs. The Grs were ectopically expressed in a Gr66aex83 mutant background. n=5 for each genotype. Data are mean±s.e.m. *P<0.05 (analysis of variance with post hoc Tukey test).
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f5: Attraction to L-canavanine induced by ectopic expression of Grs in sugar-sensing GRNs.Two-way choice assays testing for attraction or aversion to L-canavanine in flies misexpressing Gr8a, Gr66a and Gr98b in sweet-sensing GRNs. The Grs were ectopically expressed in a Gr66aex83 mutant background. n=5 for each genotype. Data are mean±s.e.m. *P<0.05 (analysis of variance with post hoc Tukey test).

Mentions: Because expression of Gr8a, Gr66a and Gr98b was sufficient to endow L-canavanine sensitivity to sweet-sensing GRNs, we tested whether ectopic expression of these Grs induced attraction to L-canavanine. Control flies (w1118) strongly preferred 1 mM sucrose over 1 mM sucrose laced with 30 mM L-canavanine (Fig. 5). In contrast, Gr66aex83 mutants had no preference for either alternative. Gr66aex83 flies expressing just two Grs (Gr8a/Gr66a, Gr8a/Gr98b or Gr66a/Gr98b) in sweet-sensing GRNs were also nearly indifferent to sucrose alone versus sucrose plus L-canavanine (Fig. 5). However, introduction of all three Grs (Gr8a/Gr66a/Gr98b) induced significant attraction to the L-canavanine-containing food (Fig. 5).


The full repertoire of Drosophila gustatory receptors for detecting an aversive compound.

Shim J, Lee Y, Jeong YT, Kim Y, Lee MG, Montell C, Moon SJ - Nat Commun (2015)

Attraction to L-canavanine induced by ectopic expression of Grs in sugar-sensing GRNs.Two-way choice assays testing for attraction or aversion to L-canavanine in flies misexpressing Gr8a, Gr66a and Gr98b in sweet-sensing GRNs. The Grs were ectopically expressed in a Gr66aex83 mutant background. n=5 for each genotype. Data are mean±s.e.m. *P<0.05 (analysis of variance with post hoc Tukey test).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4660205&req=5

f5: Attraction to L-canavanine induced by ectopic expression of Grs in sugar-sensing GRNs.Two-way choice assays testing for attraction or aversion to L-canavanine in flies misexpressing Gr8a, Gr66a and Gr98b in sweet-sensing GRNs. The Grs were ectopically expressed in a Gr66aex83 mutant background. n=5 for each genotype. Data are mean±s.e.m. *P<0.05 (analysis of variance with post hoc Tukey test).
Mentions: Because expression of Gr8a, Gr66a and Gr98b was sufficient to endow L-canavanine sensitivity to sweet-sensing GRNs, we tested whether ectopic expression of these Grs induced attraction to L-canavanine. Control flies (w1118) strongly preferred 1 mM sucrose over 1 mM sucrose laced with 30 mM L-canavanine (Fig. 5). In contrast, Gr66aex83 mutants had no preference for either alternative. Gr66aex83 flies expressing just two Grs (Gr8a/Gr66a, Gr8a/Gr98b or Gr66a/Gr98b) in sweet-sensing GRNs were also nearly indifferent to sucrose alone versus sucrose plus L-canavanine (Fig. 5). However, introduction of all three Grs (Gr8a/Gr66a/Gr98b) induced significant attraction to the L-canavanine-containing food (Fig. 5).

Bottom Line: Furthermore, misexpression of all three Grs enables salt- or sweet-sensing GRNs to respond to L-canavanine.Introduction of these Grs in sweet-sensing GRNs switches L-canavanine from an aversive to an attractive compound.We conclude that three GRs collaborate to produce a functional L-canavanine receptor.

View Article: PubMed Central - PubMed

Affiliation: Department of Oral Biology, BK21 PLUS Project Yonsei University College of Dentistry, Yonsei-ro 50-1, Seodaemun-gu, Seoul 120-752, Korea.

ABSTRACT
The ability to detect toxic compounds in foods is essential for animal survival. However, the minimal subunit composition of gustatory receptors required for sensing aversive chemicals in Drosophila is unknown. Here we report that three gustatory receptors, GR8a, GR66a and GR98b function together in the detection of L-canavanine, a plant-derived insecticide. Ectopic co-expression of Gr8a and Gr98b in Gr66a-expressing, bitter-sensing gustatory receptor neurons (GRNs) confers responsiveness to L-canavanine. Furthermore, misexpression of all three Grs enables salt- or sweet-sensing GRNs to respond to L-canavanine. Introduction of these Grs in sweet-sensing GRNs switches L-canavanine from an aversive to an attractive compound. Co-expression of GR8a, GR66a and GR98b in Drosophila S2 cells induces an L-canavanine-activated nonselective cation conductance. We conclude that three GRs collaborate to produce a functional L-canavanine receptor. Thus, our results clarify the full set of GRs underlying the detection of a toxic tastant that drives avoidance behaviour in an insect.

Show MeSH
Related in: MedlinePlus