T2Rs Function as Bitter Taste Receptors

Chandrashekar, Jayaram; Mueller, Ken L.; Hoon, Mrinalini; Adler, Elliot; Feng, Luxin; Guo, Wenlei; Zuker, Charles S.; Ryba, Nicholas J. P.

doi:10.1016/s0092-8674(00)80706-0

Cited by 1,233 publications

(922 citation statements)

References 44 publications

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“…39 Other bitter molecules stimulate multiple receptors, and the loss of one may decrease but not eliminate the ability to detect that particular bitter molecule. 30,39,47,65-73 The perception of PTC is probably an extreme case of individual variation in bitter perception.…”

Section: Bitter: Poisoned With Pleasurementioning

confidence: 99%

Genetics of Taste and Smell

Reed

Knaapila

2010

Progress in Molecular Biology and Translational Science

216

118

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Eating is dangerous. While food contains nutrients and calories that animals need to produce heat and energy, it may also contain harmful parasites, bacteria, or chemicals. To guide food selection, the senses of taste and smell have evolved to alert us to the bitter taste of poisons and the sour taste and off-putting smell of spoiled foods. These sensory systems help people and animals to eat defensively, and they provide the brake that helps them avoid ingesting foods that are harmful. But choices about which foods to eat are motivated by more than avoiding the bad; they are also motivated by seeking the good, such as fat and sugar. However, just as not everyone is equally capable of sensing toxins in food, not everyone is equally enthusiastic about consuming high-fat, high-sugar foods. Genetic studies in humans and experimental animals strongly suggest that the liking of sugar and fat is influenced by genotype; likewise, the abilities to detect bitterness and the malodors of rotting food are highly variable among individuals. Understanding the exact genes and genetic differences that affect food intake may provide important clues in obesity treatment by allowing caregivers to tailor dietary recommendations to the chemosensory landscape of each person.

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Section: Bitter: Poisoned With Pleasurementioning

confidence: 99%

Genetics of Taste and Smell

Reed

Knaapila

2010

Progress in Molecular Biology and Translational Science

216

118

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“…Putative taste receptors were discovered almost simultaneously in Drosophila and mammals. Although all these receptors belong to the large super family of GTP-binding (G) protein-coupled receptors (GPCRs), the fly GRs share no significant sequence similarity with their mammalian counterparts [33][34][35][36][37][38][39][40][41][42]. The fly Gr gene family was discovered by analyzing the Drosophila genome database using algorithms that identify multitransmembrane proteins or by performing reiterated Basic Local Alignment Search Tool searches with Drosophila olfactory receptor proteins as query sequences [35,36,42], and once the entire Drosophila genome sequence was determined, a total of 68 Gr genes were found (Fig.…”

Section: Gustatory Receptor Familymentioning

confidence: 99%

“…These analyses indicate that two distinct groups of GRNs mediate the response to attractive and repulsive chemical compounds. This arrangement is somewhat reminiscent of the mammalian taste system, where distinct cells in the taste buds of the tongue express either the T1Rs or T2Rs, receptors that detect sweet/umami or bitter-tasting substances, respectively [33,34,48,60]. However, several questions about Drosophila bitter and sweet sensation remain.…”

Section: Grns Mediate (At Least) Two Different Taste Qualitiesmentioning

confidence: 99%

Taste and pheromone perception in the fruit fly Drosophila melanogaster

Ebbs

Amrein

2007

Pflugers Arch - Eur J Physiol

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Taste is an essential sense for detection of nutrient-rich food and avoidance of toxic substances. The Drosophila melanogaster gustatory system provides an excellent model to study taste perception and taste-elicited behaviors. "The fly" is unique in the animal kingdom with regard to available experimental tools, which include a wide repertoire of molecular-genetic analyses (i.e., efficient production of transgenics and gene knockouts), elegant behavioral assays, and the possibility to conduct electrophysiological investigations. In addition, fruit flies, like humans, recognize sugars as a food source, but avoid bitter tasting substances that are often toxic to insects and mammals alike. This paper will present recent research progress in the field of taste and contact pheromone perception in the fruit fly. First, we shall describe the anatomical properties of the Drosophila gustatory system and survey the family of taste receptors to provide an appropriate background. We shall then review taste and pheromone perception mainly from a molecular genetic perspective that includes behavioral, electrophysiological and imaging analyses of wild type flies and flies with genetically manipulated taste cells. Finally, we shall provide an outlook of taste research in this elegant model system for the next few years.Keywords Drosophila . Gustatory receptor neurons . GTP-binding protein-coupled receptors Like most animals, Drosophila monitor their chemical world with two distinct senses: the olfactory system, which is used for the detection of volatile chemicals, and the gustatory (taste) system, which enables the fly to detect soluble compounds. The olfactory sensory system (or the fly nose) is comprised of two pairwise head appendages, the third segments of the antennae, and the maxillary palps (Fig. 1). These appendages are covered with hundreds of sensory hairs, each of which contains two to four olfactory sensory neurons (OSNs) [1]. In contrast, the gustatory system is widely distributed over the animal's body. The main taste organ, the proboscis or labial palps (i.e., the fly tongue), is located on the distal end of the labellum (also a head appendage), but flies, like many other insects, have taste sensilla on legs and wings and, in females, on the genitalia [1,2].The roles of the olfactory and taste systems are clearly separated with regard to the physical state of chemicals they detect (volatile vs solubilized). However, the two systems often cooperate to fulfill specific functions in related processes and behaviors, the most obvious of them being the location and identification of food. For example, chemical cues such as the specific odor of a flower and the sugar compounds present in its nectar are by nature associated with one another. Thus, the odor cue provides a primary sensory input for an insect such as a honeybee to locate a food source (nectar), whose particular chemical composition is subsequently verified by the taste system. Similarly, the typical odor of yeast, which produces high amounts of t...

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“…Given the critical importance of chemosensation for the worm's survival, it is perhaps not surprising that nearly 10% of the C. elegans genome is devoted to encoding predicted chemosensory receptors (CRs), a current total of ∼1,500 molecules [58, [116][117][118]. In comparison, the Drosophila genome is predicted to encode ∼62 olfactory and ∼68 gustatory receptors [119][120][121][122][123], whereas the mouse genome encodes ∼1,200 olfactory and 38 gustatory GPCRs [93,94,[124][125][126][127][128]. Although the expression patterns of only a handful of CR genes have been examined [58,129], it is clear that in stark contrast to the vertebrate or Drosophila olfactory systems, each chemosensory neuron in C. elegans expresses multiple CR genes, perhaps as many as 20 per neuron type (Fig.…”

Section: The Molecules For Taste and Smellmentioning

confidence: 99%

Generation and modulation of chemosensory behaviors in C. elegans

Sengupta

2007

Pflugers Arch - Eur J Physiol

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C. elegans recognizes and discriminates among hundreds of chemical cues using a relatively compact chemosensory nervous system. Chemosensory behaviors are also modulated by prior experience and contextual cues. Because of the facile genetics and genomics possible in this organism, C. elegans provides an excellent system in which to explore the generation of chemosensory behaviors from the level of a single gene to the motor output. This review summarizes the current knowledge on the molecular and neuronal substrates of chemosensory behaviors and chemosensory behavioral plasticity in C. elegans.

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T2Rs Function as Bitter Taste Receptors

Cited by 1,233 publications

References 44 publications

Genetics of Taste and Smell

Genetics of Taste and Smell

Taste and pheromone perception in the fruit fly Drosophila melanogaster

Generation and modulation of chemosensory behaviors in C. elegans

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