Functional divergence of bitter taste receptors in a nectar-feeding bird

Nectar may contain many secondary metabolites that are commonly toxic and bitter-tasting. It has been hypothesized that such bitter-tasting secondary metabolites might keep the nectar exclusive to only a few pollinators. To test this hypothesis, we examined functional changes of bitter taste receptor genes ( Tas2r s) in a species of nectar-feeding bird (Anna's hummingbird) by comparing these genes with those from two closely related insect-feeding species (chimney swift and chuck-will's widow). We previously identified a larger number of Tas2r s in the hummingbird than in its close insectivorous relatives. In the present study, we demonstrate higher sensitivity and new functions in the hummingbird Tas2r gene copies generated by a lineage-specific duplication, which has been shaped by positive selection. These results suggest that the bitter taste may lead to increased sensitivities and specialized abilities of the hummingbird to detect bitter-tasting nectar. Moreover, this study potentially supports the hypothesis that bitter-tasting nectar may have been specialized for some pollinators, thus enforcing plant–pollinator mutualism.

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Bitter Taste Receptor Agonist (Quinine) Induces Traction Force Reduction and Calcium Flux Increase in Airway Smooth Muscle Cells from Ovalbumin-Sensitized and Challenged Rats

Journal of Advances in Biomedical Engineering and Technology ◽

10.15379/2409-3394.2015.02.01.3 ◽

2015 ◽

Vol 2 (1) ◽

pp. 20-27 ◽

Cited By ~ 4

Author(s):

Linhong Deng ◽

◽

Huilong Zeng ◽

Yue Wang ◽

Mingzhi Luo ◽

...

Keyword(s):

Smooth Muscle ◽

Receptor Agonist ◽

Bitter Taste ◽

Taste Receptor ◽

Traction Force ◽

Calcium Flux ◽

Airway Smooth Muscle Cells ◽

Bitter Taste Receptor ◽

Force Reduction ◽

Flux Increase

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Faculty Opinions recommendation of Diet-induced regulation of bitter taste receptor subtypes in the mouse gastrointestinal tract.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.718882745.793523444 ◽

2016 ◽

Author(s):

Jonathan Kaunitz

Keyword(s):

Gastrointestinal Tract ◽

Bitter Taste ◽

Taste Receptor ◽

Receptor Subtypes ◽

Bitter Taste Receptor

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A Cross-Sectional Study of Bitter-Taste Receptor Genotypes, Oral Health, and Markers of Oral Inflammation

Oral ◽

10.3390/oral1020013 ◽

2021 ◽

Vol 1 (2) ◽

pp. 122-138

Author(s):

Kiranjit Kaur ◽

Alexandria Turner ◽

Patrice Jones ◽

Dean Sculley ◽

Martin Veysey ◽

...

Keyword(s):

Oral Health ◽

Bitter Taste ◽

Taste Receptor ◽

Cross Sectional Study ◽

Sectional Study ◽

Bitter Taste Receptor ◽

Cross Sectional ◽

Tnf Α ◽

Oral Inflammation ◽

Major Allele

(1) Background: The aetiology of oral disease is multifactorial, involving genetic and environmental factors, including dietary ones. Bitter taste genetics may be related to oral health through dietary modulation or non-gustatory roles, including modulation of inflammation. Investigations of bitter taste and oral health associations to date have been restricted to specific polymorphisms, limited outcomes (caries), and age-groups (children), and links to inflammation remain to be elucidated. (2) Methods: A cross-sectional study (n = 65) investigated the correlations between bitter taste genotypes, oral health outcomes, and oral inflammation markers. Oral examinations were conducted, including saliva testing with evaluation of flow rate, pH, and buffering and antioxidant capacity (FRAP) and IL-1β, TNF-α, IL-6 levels. DNA was collected via buccal swabs and used to evaluate the presence of multiple bitter-taste receptor gene polymorphisms. (3) Results: The major allele for TAS2R4-rs2233998, TAS2R5-rs2227264, TAS2R50-rs1376251, and TAS2R9-rs3741845 was associated with a higher mean of unstimulated salivary flow rate, FRAP, TNF-α, IL-1β, and likelihood of filled teeth. Presence of the major allele for TAS2R4-rs2234001 and TAS2R9-rs3741845 was associated with lower means FRAP, TNF-α, IL-1β, DMFT index, and likelihood of missing teeth. (4) Conclusions: These findings suggest relationships between bitter-taste genotypes, oral health outcomes, and inflammatory markers. These findings justify the need for further studies that could help identify risk groups and develop novel agents for maintaining oral health.

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Taste perception and expression in stomach of bitter taste receptor tas2r38 in obese and lean subjects

Appetite ◽

10.1016/j.appet.2021.105595 ◽

2021 ◽

pp. 105595

Author(s):

Antonietta Robino ◽

Natalia Rosso ◽

Martina Guerra ◽

Pio Corleone ◽

Biagio Casagranda ◽

...

Keyword(s):

Bitter Taste ◽

Taste Receptor ◽

Taste Perception ◽

Bitter Taste Receptor

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Bitter taste receptor mTas2r105 is expressed in small intestinal villus and crypts

Biochemical and Biophysical Research Communications ◽

10.1016/j.bbrc.2015.06.038 ◽

2015 ◽

Vol 463 (4) ◽

pp. 934-941 ◽

Cited By ~ 14

Author(s):

Fu Gu ◽

Xin Liu ◽

Jie Liang ◽

Jiaying Chen ◽

Fuxue Chen ◽

...

Keyword(s):

Bitter Taste ◽

Taste Receptor ◽

Bitter Taste Receptor ◽

Intestinal Villus ◽

Small Intestinal ◽

Small Intestinal Villus

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Evaluation of the Bitter-Masking Potential of Food Proteins for EGCG by a Cell-Based Human Bitter Taste Receptor Assay and Binding Studies

Journal of Agricultural and Food Chemistry ◽

10.1021/jf4030823 ◽

2013 ◽

Vol 61 (42) ◽

pp. 10010-10017 ◽

Cited By ~ 18

Author(s):

Maxime C. Bohin ◽

Wibke S. U. Roland ◽

Harry Gruppen ◽

Robin J. Gouka ◽

Harry T. W. M. van der Hijden ◽

...

Keyword(s):

Bitter Taste ◽

Taste Receptor ◽

Bitter Taste Receptor ◽

Binding Studies ◽

Food Proteins ◽

Receptor Assay ◽

A Cell

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Vampire bats exhibit evolutionary reduction of bitter taste receptor genes common to other bats

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2014.1079 ◽

2014 ◽

Vol 281 (1788) ◽

pp. 20141079 ◽

Cited By ~ 28

Author(s):

Wei Hong ◽

Huabin Zhao

Keyword(s):

Bitter Taste ◽

Food Selection ◽

Taste Receptor ◽

Selective Constraint ◽

Behavioural Response ◽

Bitter Taste Receptor ◽

Pathway Gene ◽

Vampire Bats ◽

Vampire Bat ◽

Strong Functional Constraint

The bitter taste serves as an important natural defence against the ingestion of poisonous foods and is thus believed to be indispensable in animals. However, vampire bats are obligate blood feeders that show a reduced behavioural response towards bitter-tasting compounds. To test whether bitter taste receptor genes ( T2R s) have been relaxed from selective constraint in vampire bats, we sampled all three vampire bat species and 11 non-vampire bats, and sequenced nine one-to-one orthologous T2R s that are assumed to be functionally conserved in all bats. We generated 85 T2R sequences and found that vampire bats have a significantly greater percentage of pseudogenes than other bats. These results strongly suggest a relaxation of selective constraint and a reduction of bitter taste function in vampire bats. We also found that vampire bats retain many intact T2R s, and that the taste signalling pathway gene Calhm1 remains complete and intact with strong functional constraint. These results suggest the presence of some bitter taste function in vampire bats, although it is not likely to play a major role in food selection. Together, our study suggests that the evolutionary reduction of bitter taste function in animals is more pervasive than previously believed, and highlights the importance of extra-oral functions of taste receptor genes.

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