Limits...
Bitter taste receptors confer diverse functions to neurons.

Delventhal R, Carlson JR - Elife (2016)

Bottom Line: Expression of individual Grs conferred strikingly different effects in different neurons.The results support a model in which bitter Grs interact, exhibiting competition, inhibition, or activation.The results have broad implications for the problem of how taste systems evolve to detect new environmental dangers.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, United States.

ABSTRACT
Bitter compounds elicit an aversive response. In Drosophila, bitter-sensitive taste neurons coexpress many members of the Gr family of taste receptors. However, the molecular logic of bitter signaling is unknown. We used an in vivo expression approach to analyze the logic of bitter taste signaling. Ectopic or overexpression of bitter Grs increased endogenous responses or conferred novel responses. Surprisingly, expression of Grs also suppressed many endogenous bitter responses. Conversely, deletion of an endogenous Gr led to novel responses. Expression of individual Grs conferred strikingly different effects in different neurons. The results support a model in which bitter Grs interact, exhibiting competition, inhibition, or activation. The results have broad implications for the problem of how taste systems evolve to detect new environmental dangers.

No MeSH data available.


Related in: MedlinePlus

Sensillum types on the labellum.Left: The four bitter-responsive types, S-a (green), S-b (blue), I-a (purple) and I-b (red), are differently distributed on the labellar surface. L sensilla (gray) show little if any response to bitter compounds. Right: S-a and S-b have four gustatory receptor neurons (GRNs), one of which is bitter-responsive, and I-a and I-b sensilla have two GRNs, one of which is bitter-responsive. The bitter-responsive neuron (B) of each sensillum type expresses a different combination of Grs. Five Grs, referred to as 'Commonly Expressed Receptors' (CERs; in rectangles), are expressed in every bitter neuron on the labellum. Many or all sensilla also contain a sugar-sensitive neuron (S). Mapping of Grs to neurons is based on GAL4 driver expression. Figure adapted from Weiss et al. (2011).DOI:http://dx.doi.org/10.7554/eLife.11181.003
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4764594&req=5

fig1: Sensillum types on the labellum.Left: The four bitter-responsive types, S-a (green), S-b (blue), I-a (purple) and I-b (red), are differently distributed on the labellar surface. L sensilla (gray) show little if any response to bitter compounds. Right: S-a and S-b have four gustatory receptor neurons (GRNs), one of which is bitter-responsive, and I-a and I-b sensilla have two GRNs, one of which is bitter-responsive. The bitter-responsive neuron (B) of each sensillum type expresses a different combination of Grs. Five Grs, referred to as 'Commonly Expressed Receptors' (CERs; in rectangles), are expressed in every bitter neuron on the labellum. Many or all sensilla also contain a sugar-sensitive neuron (S). Mapping of Grs to neurons is based on GAL4 driver expression. Figure adapted from Weiss et al. (2011).DOI:http://dx.doi.org/10.7554/eLife.11181.003

Mentions: The principal taste organ of the Drosophila head is the labellum (Figure 1). The labellum contains ~31 taste sensilla that fall into morphological classes based on length: short (S; green and blue in Figure 1), intermediate (I; purple and red), and long (L; gray in Figure 1) (Stocker, 1994). Each sensillum has a pore at its tip. When a sensillum makes contact with a potential food source, compounds from the food source diffuse through the pore and activate gustatory receptor neurons inside.10.7554/eLife.11181.003Figure 1.Sensillum types on the labellum.


Bitter taste receptors confer diverse functions to neurons.

Delventhal R, Carlson JR - Elife (2016)

Sensillum types on the labellum.Left: The four bitter-responsive types, S-a (green), S-b (blue), I-a (purple) and I-b (red), are differently distributed on the labellar surface. L sensilla (gray) show little if any response to bitter compounds. Right: S-a and S-b have four gustatory receptor neurons (GRNs), one of which is bitter-responsive, and I-a and I-b sensilla have two GRNs, one of which is bitter-responsive. The bitter-responsive neuron (B) of each sensillum type expresses a different combination of Grs. Five Grs, referred to as 'Commonly Expressed Receptors' (CERs; in rectangles), are expressed in every bitter neuron on the labellum. Many or all sensilla also contain a sugar-sensitive neuron (S). Mapping of Grs to neurons is based on GAL4 driver expression. Figure adapted from Weiss et al. (2011).DOI:http://dx.doi.org/10.7554/eLife.11181.003
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4764594&req=5

fig1: Sensillum types on the labellum.Left: The four bitter-responsive types, S-a (green), S-b (blue), I-a (purple) and I-b (red), are differently distributed on the labellar surface. L sensilla (gray) show little if any response to bitter compounds. Right: S-a and S-b have four gustatory receptor neurons (GRNs), one of which is bitter-responsive, and I-a and I-b sensilla have two GRNs, one of which is bitter-responsive. The bitter-responsive neuron (B) of each sensillum type expresses a different combination of Grs. Five Grs, referred to as 'Commonly Expressed Receptors' (CERs; in rectangles), are expressed in every bitter neuron on the labellum. Many or all sensilla also contain a sugar-sensitive neuron (S). Mapping of Grs to neurons is based on GAL4 driver expression. Figure adapted from Weiss et al. (2011).DOI:http://dx.doi.org/10.7554/eLife.11181.003
Mentions: The principal taste organ of the Drosophila head is the labellum (Figure 1). The labellum contains ~31 taste sensilla that fall into morphological classes based on length: short (S; green and blue in Figure 1), intermediate (I; purple and red), and long (L; gray in Figure 1) (Stocker, 1994). Each sensillum has a pore at its tip. When a sensillum makes contact with a potential food source, compounds from the food source diffuse through the pore and activate gustatory receptor neurons inside.10.7554/eLife.11181.003Figure 1.Sensillum types on the labellum.

Bottom Line: Expression of individual Grs conferred strikingly different effects in different neurons.The results support a model in which bitter Grs interact, exhibiting competition, inhibition, or activation.The results have broad implications for the problem of how taste systems evolve to detect new environmental dangers.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, United States.

ABSTRACT
Bitter compounds elicit an aversive response. In Drosophila, bitter-sensitive taste neurons coexpress many members of the Gr family of taste receptors. However, the molecular logic of bitter signaling is unknown. We used an in vivo expression approach to analyze the logic of bitter taste signaling. Ectopic or overexpression of bitter Grs increased endogenous responses or conferred novel responses. Surprisingly, expression of Grs also suppressed many endogenous bitter responses. Conversely, deletion of an endogenous Gr led to novel responses. Expression of individual Grs conferred strikingly different effects in different neurons. The results support a model in which bitter Grs interact, exhibiting competition, inhibition, or activation. The results have broad implications for the problem of how taste systems evolve to detect new environmental dangers.

No MeSH data available.


Related in: MedlinePlus