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Wang J, Liu R, Ma H, Zhang W. The Pathogenesis of COVID-19-Related Taste Disorder and Treatments. J Dent Res 2023; 102:1191-1198. [PMID: 37729625 DOI: 10.1177/00220345231182926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/22/2023] Open
Abstract
COVID-19, mainly manifested as acute respiratory distress syndrome, has afflicted millions of people worldwide since 2019. Taste dysfunction is a common early-stage symptom of COVID-19 infection that burdens patients for weeks or even permanently in some cases. Owing to its subjectivity and complexity, the mechanism of taste disorder is poorly studied. Previous studies have reported that the COVID-19 entry receptors are highly expressed in taste buds, thereby intensifying the cytocidal effect. Taste receptor cells are vulnerable to inflammation, and the COVID-19-induced cytokine storm causes secondary damage to taste function. Interferon and various proinflammatory cytokines can trigger cell apoptosis and disrupt the renewal of taste bud stem cells. This immune response can be further enhanced by the accumulation of Angiotensin II (Ang II) caused by an unbalanced local renin-angiotensin system (RAS) system. In addition, severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) is neurotropic and can invade the brain through the olfactory bulb, affecting the nervous system. Other factors, such as host zinc deficiency, genetic susceptibility, sialic acid, and some neurotransmitters, also contribute to the pathogenesis process. Although several medical interventions have displayed effectiveness, only a few strategies exist for the treatment of postinfectious dysgeusia. Stem cell-based taste regeneration offers promise for long-term taste disorders. Clinical studies have demonstrated that stem cells can treat long COVID-19 through immune regulation. In dysgeusia, the differentiation of taste bud stem cells can be stimulated through exogenous epithelial-derived and neural-derived factors to regenerate taste buds. Tongue organoids are also emerging as functional taste buds, offering new insights into the study of taste regeneration. This review presents the current evidence of the pathogenesis of COVID-19-related dysgeusia, summarizes currently available treatments, and suggests future directions of taste regeneration therapy.
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Affiliation(s)
- J Wang
- Department of Prosthodontics, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Engineering Research Center of Advanced Dental Technology and Materials, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Stomatology & Shanghai Research Institute of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- National Clinical Research Center for Oral Disease, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Ninth People's Hospital, College of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - R Liu
- Department of Prosthodontics, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Engineering Research Center of Advanced Dental Technology and Materials, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Stomatology & Shanghai Research Institute of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- National Clinical Research Center for Oral Disease, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Ninth People's Hospital, College of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - H Ma
- Department of Prosthodontics, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Engineering Research Center of Advanced Dental Technology and Materials, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Stomatology & Shanghai Research Institute of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- National Clinical Research Center for Oral Disease, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Ninth People's Hospital, College of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - W Zhang
- Department of Prosthodontics, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Engineering Research Center of Advanced Dental Technology and Materials, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Stomatology & Shanghai Research Institute of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- National Clinical Research Center for Oral Disease, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Ninth People's Hospital, College of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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Zhao L, Li XD, Jiang T, Wang H, Dan Z, Xu SQ, Guan DL. The Chromosome-Level Genome of Hestina assimilis (Lepidoptera: Nymphalidae) Reveals the Evolution of Saprophagy-Related Genes in Brush-Footed Butterflies. Int J Mol Sci 2023; 24:ijms24032087. [PMID: 36768416 PMCID: PMC9917059 DOI: 10.3390/ijms24032087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 01/06/2023] [Accepted: 01/16/2023] [Indexed: 01/21/2023] Open
Abstract
Most butterflies feed on nectar, while some saprophagous butterflies forage on various non-nectar foods. To date, little is known about the genomic and molecular shifts associated with the evolution of the saprophagous feeding strategy. Here, we assembled the high-quality chromosome-level genome of Hestina assimilis to explore its saprophagous molecular and genetic mechanisms. This chromosome-level genome of H. assimilis is 412.82 Mb, with a scaffold N50 of 15.70 Mb. In total, 98.11% of contigs were anchored to 30 chromosomes. Compared with H. assimilis and other Nymphalidae butterflies, the genes of metabolism and detoxification experienced expansions. We annotated 80 cytochrome P450 (CYP) genes in the H. assimilis genome, among which genes belonging to the CYP4 subfamily were significantly expanded (p < 0.01). These P450 genes were unevenly distributed and mainly concentrated on chromosomes 6-9. We identified 33 olfactory receptor (OR), 20 odorant-binding protein (OBP), and six gustatory receptor (GR) genes in the H. assimilis genome, which were fewer than in the nectarivorous Danaus plexippus. A decreased number of OBP, OR, and GR genes implied that H. assimilis should resort less to olfaction and gustation than their nectarivorous counterparts, which need highly specialized olfactory and gustatory functions. Moreover, we found one site under positive selection occurred in residue 996 (phenylalanine) of GR genes exclusive to H. assimilis, which is conservative in most lineages. Our study provides support for the adaptive evolution of feeding habits in butterflies.
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Affiliation(s)
- Lu Zhao
- College of Life Sciences, Shaanxi Normal University, Xi’an 710119, China
| | - Xiao-Dong Li
- School of Chemistry and Bioengineering, Hechi University, Yizhou 546300, China
| | - Tao Jiang
- College of Life Sciences, Shaanxi Normal University, Xi’an 710119, China
| | - Hang Wang
- College of Life Sciences, Shaanxi Normal University, Xi’an 710119, China
| | - Zhicuo Dan
- College of Life Sciences, Shaanxi Normal University, Xi’an 710119, China
| | - Sheng-Quan Xu
- College of Life Sciences, Shaanxi Normal University, Xi’an 710119, China
- Correspondence: (S.-Q.X.); (D.-L.G.)
| | - De-Long Guan
- College of Life Sciences, Shaanxi Normal University, Xi’an 710119, China
- School of Chemistry and Bioengineering, Hechi University, Yizhou 546300, China
- Correspondence: (S.-Q.X.); (D.-L.G.)
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3
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Zheng X, Wang L, Liu Y, Yang Z, Li F, Yan L, Shen Y, Yue B, Zhou C. Improved genome assembly provides new insights into the environmental adaptation of the American cockroach, Periplaneta americana. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2022; 111:e21956. [PMID: 35933728 DOI: 10.1002/arch.21956] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 06/23/2022] [Accepted: 07/21/2022] [Indexed: 06/15/2023]
Abstract
The synanthropic pest and a model organism for entomological research, American cockroach, Periplaneta americana (Linnaeus), can survive in unfavorable environments for humans. To investigate the genetic mechanisms of success in environmental adaptation of P. americana, we de novo reassembled its whole genome based on next-generation sequencing and PacBio sequencing. The final genome reassembly consisted of approximately 3.34 Gb with scaffold N50 of 465.51 Kb. The completeness (95.4%) of the complete genome was evaluated with single-copy orthologous genes using BUSCO. We identified 18,618 protein-coding genes, 16,443 (88.32%) of which were well supported by public protein databases. We identified 482.04 Mb (approximately 14.45%) repeat elements, 1,385,093 perfect microsatellites simple sequence repeats in P. americana genome, which was higher than other four Blattaria insects. Comparative genomics analysis revealed obvious expansion in the gene families associated with chemoreception (olfactory receptors, gustatory receptors, ionotropic glutamate receptors, chemosensory protein, and sensory neuron membrane protein), which provided the necessary information for functional characterization of the chemosensory receptors of P. americana, with potential for new or refined applications of semiochemicals-based control of this pest insect. Similarly, gene families (cytochrome P450s, carboxyl/choline esterases, and UDP-glycosyl-transferases) encoding receptors for bitter or toxic substances and detoxification enzymes were obviously expanded in P. americana, enabling its ability to detect and detoxify many toxins. Enrichment analysis of positively selected genes in P. americana revealed items associated with metabolic process and catalytic activity, which possibly contributed to the pesticide resistance of P. americana. We also analyzed the homologs to antimicrobial peptide genes reported in the Drosophila genome, and identified two attacins and seven defensins in P. americana. Our data and findings will substantially facilitate molecular studies in P. americana, including elucidation of detoxification mechanisms of xenobiotic, as well as development of new pest management strategies for the control of pests like P. americana.
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Affiliation(s)
- Xiaofeng Zheng
- Key Laboratory of Bioresources and Ecoenvironment (Ministry of Education), College of Life Sciences, Sichuan University, Chengdu, People's Republic of China
| | - Lei Wang
- Key Laboratory of Bioresources and Ecoenvironment (Ministry of Education), College of Life Sciences, Sichuan University, Chengdu, People's Republic of China
| | - Yi Liu
- Key Laboratory of Bioresources and Ecoenvironment (Ministry of Education), College of Life Sciences, Sichuan University, Chengdu, People's Republic of China
| | - Zhen Yang
- Key Laboratory of Bioresources and Ecoenvironment (Ministry of Education), College of Life Sciences, Sichuan University, Chengdu, People's Republic of China
| | - Fengjun Li
- Key Laboratory of Bioresources and Ecoenvironment (Ministry of Education), College of Life Sciences, Sichuan University, Chengdu, People's Republic of China
| | - Lin Yan
- Key Laboratory of Bioresources and Ecoenvironment (Ministry of Education), College of Life Sciences, Sichuan University, Chengdu, People's Republic of China
| | - Yongmei Shen
- Sichuan Key Laboratory for Medicinal American Cockroach, Chengdu, Sichuan, People's Republic of China
| | - Bisong Yue
- Key Laboratory of Bioresources and Ecoenvironment (Ministry of Education), College of Life Sciences, Sichuan University, Chengdu, People's Republic of China
| | - Chuang Zhou
- Key Laboratory of Bioresources and Ecoenvironment (Ministry of Education), College of Life Sciences, Sichuan University, Chengdu, People's Republic of China
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Wooding SP, Ramirez VA, Behrens M. Bitter taste receptors: Genes, evolution and health. Evol Med Public Health 2022; 9:431-447. [PMID: 35154779 PMCID: PMC8830313 DOI: 10.1093/emph/eoab031] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 10/05/2021] [Indexed: 02/01/2023] Open
Abstract
Bitter taste perception plays vital roles in animal behavior and fitness. By signaling the presence of toxins in foods, particularly noxious defense compounds found in plants, it enables animals to avoid exposure. In vertebrates, bitter perception is initiated by TAS2Rs, a family of G protein-coupled receptors expressed on the surface of taste buds. There, oriented toward the interior of the mouth, they monitor the contents of foods, drinks and other substances as they are ingested. When bitter compounds are encountered, TAS2Rs respond by triggering neural pathways leading to sensation. The importance of this role placed TAS2Rs under selective pressures in the course of their evolution, leaving signatures in patterns of gene gain and loss, sequence polymorphism, and population structure consistent with vertebrates' diverse feeding ecologies. The protective value of bitter taste is reduced in modern humans because contemporary food supplies are safe and abundant. However, this is not always the case. Some crops, particularly in the developing world, retain surprisingly high toxicity and bitterness remains an important measure of safety. Bitter perception also shapes health through its influence on preference driven behaviors such as diet choice, alcohol intake and tobacco use. Further, allelic variation in TAS2Rs is extensive, leading to individual differences in taste sensitivity that drive these behaviors, shaping susceptibility to disease. Thus, bitter taste perception occupies a critical intersection between ancient evolutionary processes and modern human health.
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Affiliation(s)
- Stephen P Wooding
- Department of Anthropology and Health Sciences Research Institute, University of California, Merced, CA, USA
| | - Vicente A Ramirez
- Department of Public Health, University of California, Merced, CA, USA
| | - Maik Behrens
- Maik Behrens, Leibniz-Institute for Food Systems Biology at the Technical University of Munich, Freising, Germany
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5
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Abstract
During the last couples of years, a number of studies have increasingly accumulated on the gustatory perception of dietary fatty acids in rodent models and human beings in health and disease. There is still a debate to coin a specific term for the gustatory perception of dietary fatty acids either as the sixth basic taste quality or as an alimentary taste. Indeed, the psycho-physical cues of orosensory detection of dietary lipids are not as distinctly perceived as other taste qualities like sweet or bitter. The cellular and molecular pharmacological mechanisms, triggered by the binding of dietary long-chain fatty acids (LCFAs) to tongue taste bud lipid receptors like CD36 and GPR120, involve Ca2+ signaling as other five basic taste qualities. We have not only elucidated the role of Ca2+ signaling but also identified different components of the second messenger cascade like STIM1 and MAP kinases, implicated in fat taste perception. We have also demonstrated the implication of Calhm1 voltage-gated channels and store-operated Ca2+ (SOC) channels like Orai1, Orai1/3, and TRPC3 in gustatory perception of dietary fatty acids. We have not only employed siRNA technology in vitro and ex vivo on tissues but also used animal models of genetic invalidation of STIM1, ERK1, Orai1, Calhm1 genes to explore their implications in fat taste signal transduction. Moreover, our laboratory has also demonstrated the importance of LCFAs detection dysfunction in obesity in animal models and human beings.
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Affiliation(s)
- Aziz Hichami
- Physiologie de la Nutrition and Toxicologie (NUTox), UMR1231 INSERM/Université de Bourgogne, Dijon, France
| | - Amira Sayed Khan
- Physiologie de la Nutrition and Toxicologie (NUTox), UMR1231 INSERM/Université de Bourgogne, Dijon, France
| | - Naim Akhtar Khan
- Physiologie de la Nutrition and Toxicologie (NUTox), UMR1231 INSERM/Université de Bourgogne, Dijon, France.
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Zhong H, Huang J, Shang S, Yuan B. Evolutionary insights into umami, sweet, and bitter taste receptors in amphibians. Ecol Evol 2021; 11:18011-18025. [PMID: 35003653 PMCID: PMC8717283 DOI: 10.1002/ece3.8398] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 11/06/2021] [Accepted: 11/11/2021] [Indexed: 12/19/2022] Open
Abstract
Umami and sweet sensations provide animals with important dietary information for detecting and consuming nutrients, whereas bitter sensation helps animals avoid potentially toxic or harmful substances. Enormous progress has been made toward animal sweet/umami taste receptor (Tas1r) and bitter taste receptor (Tas2r). However, information about amphibians is mainly scarce. This study attempted to delineate the repertoire of Tas1r/Tas2r genes by searching for currently available genome sequences in 14 amphibian species. This study identified 16 Tas1r1, 9 Tas1r2, and 9 Tas1r3 genes to be intact and another 17 Tas1r genes to be pseudogenes or absent in the 14 amphibians. According to the functional prediction of Tas1r genes, two species have lost sweet sensation and seven species have lost both umami and sweet sensations. Anurans possessed a large number of intact Tas2rs, ranging from 39 to 178. In contrast, caecilians possessed a contractive bitter taste repertoire, ranging from 4 to 19. Phylogenetic and reconciling analysis revealed that the repertoire of amphibian Tas1rs and Tas2rs was shaped by massive gene duplications and losses. No correlation was found between feeding preferences and the evolution of Tas1rs in amphibians. However, the expansion of Tas2rs may help amphibians adapt to both aquatic and terrestrial habitats. Bitter detection may have played an important role in the evolutionary adaptation of vertebrates in the transition from water to land.
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Affiliation(s)
- Huaming Zhong
- College of Biology and FoodShangqiu Normal UniversityShangqiuChina
| | - Jie Huang
- College of Biology and FoodShangqiu Normal UniversityShangqiuChina
| | - Shuai Shang
- College of Biological and Environmental EngineeringBinzhou UniversityBinzhouChina
| | - Baodong Yuan
- College of Biology and FoodShangqiu Normal UniversityShangqiuChina
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7
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Abstract
Sour taste, the taste of acids, is one of the most enigmatic of the five basic taste qualities; its function is unclear and its receptor was until recently unknown. Sour tastes are transduced in taste buds on the tongue and palate epithelium by a subset of taste receptor cells, known as type III cells. Type III cells express a number of unique markers, including the PKD2L1 gene, which allow for their identification and manipulation. These cells respond to acid stimuli with action potentials and release neurotransmitters onto afferent nerve fibers, with cell bodies in geniculate and petrosal ganglia. Here, we review classical studies of sour taste leading up to the identification of the sour receptor as the proton channel, OTOP1. Expected final online publication date for the Annual Review of Physiology, Volume 84 is February 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Heather N Turner
- Department of Biological Sciences, Section of Neurobiology, University of Southern California, Los Angeles, California, USA; ,
| | - Emily R Liman
- Department of Biological Sciences, Section of Neurobiology, University of Southern California, Los Angeles, California, USA; ,
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8
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Is dietary intake associated with salt taste function and perception in adults? A systematic review. Food Qual Prefer 2021. [DOI: 10.1016/j.foodqual.2021.104174] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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9
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Fat taste signal transduction and its possible negative modulator components. Prog Lipid Res 2020; 79:101035. [DOI: 10.1016/j.plipres.2020.101035] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 04/26/2020] [Accepted: 04/29/2020] [Indexed: 02/07/2023]
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10
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Preference for dietary fat: From detection to disease. Prog Lipid Res 2020; 78:101032. [PMID: 32343988 DOI: 10.1016/j.plipres.2020.101032] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 03/22/2020] [Accepted: 03/25/2020] [Indexed: 12/11/2022]
Abstract
Recent advances in the field of taste physiology have clarified the role of different basic taste modalities and their implications in health and disease and proposed emphatically that there might be a distinct cue for oro-sensory detection of dietary long-chain fatty acids (LCFAs). Hence, fat taste can be categorized as a taste modality. During mastication, LCFAs activate tongue lipid sensors like CD36 and GPR120 triggering identical signaling pathways as the basic taste qualities do; however, the physico-chemical perception of fat is not as distinct as sweet or bitter or other taste sensations. The question arises whether "fat taste" is a basic or "alimentary" taste. There is compelling evidence that fat-rich dietary intervention modulates fat taste perception where an increase or a decrease in lipid contents in the diet results, respectively, in downregulation or upregulation of fat taste sensitivity. Evidently, a decrease in oro-sensory detection of LCFAs leads to high fat intake and, consequently, to obesity. In this article, we discuss recent relevant advances made in the field of fat taste physiology with regard to dietary fat preference and lipid sensors that can be the target of anti-obesity strategies.
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11
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Abstract
The anatomical structure and function of beaks, bills and tongue together with the mechanics of deglutition in birds have contributed to the development of a taste system denuded of macrostructures visible to the human naked eye. Studies in chickens and other birds have revealed that the avian taste system consists of taste buds not clustered in papillae and located mainly (60 %) in the upper palate hidden in the crevasses of the salivary ducts. That explains the long delay in the understanding of the avian taste system. However, recent studies reported 767 taste buds in the oral cavity of the chicken. Chickens appear to have an acute sense of taste allowing for the discrimination of dietary amino acids, fatty acids, sugars, quinine, Ca and salt among others. However, chickens and other birds have small repertoires of bitter taste receptors (T2R) and are missing the T1R2 (related to sweet taste in mammals). Thus, T1R2-independent mechanisms of glucose sensing might be particularly relevant in chickens. The chicken umami receptor (T1R1/T1R3) responds to amino acids such as alanine and serine (known to stimulate the umami receptor in rodents and fish). Recently, the avian nutrient chemosensory system has been found in the gastrointestinal tract and hypothalamus related to the enteroendocrine system which mediates the gut-brain dialogue relevant to the control of feed intake. Overall, the understanding of the avian taste system provides novel and robust tools to improve avian nutrition.
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12
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The genomic and functional landscapes of developmental plasticity in the American cockroach. Nat Commun 2018; 9:1008. [PMID: 29559629 PMCID: PMC5861062 DOI: 10.1038/s41467-018-03281-1] [Citation(s) in RCA: 88] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Accepted: 02/02/2018] [Indexed: 11/08/2022] Open
Abstract
Many cockroach species have adapted to urban environments, and some have been serious pests of public health in the tropics and subtropics. Here, we present the 3.38-Gb genome and a consensus gene set of the American cockroach, Periplaneta americana. We report insights from both genomic and functional investigations into the underlying basis of its adaptation to urban environments and developmental plasticity. In comparison with other insects, expansions of gene families in P. americana exist for most core gene families likely associated with environmental adaptation, such as chemoreception and detoxification. Multiple pathways regulating metamorphic development are well conserved, and RNAi experiments inform on key roles of 20-hydroxyecdysone, juvenile hormone, insulin, and decapentaplegic signals in regulating plasticity. Our analyses reveal a high level of sequence identity in genes between the American cockroach and two termite species, advancing it as a valuable model to study the evolutionary relationships between cockroaches and termites.
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13
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Berberine activates bitter taste responses of enteroendocrine STC-1 cells. Mol Cell Biochem 2018; 447:21-32. [DOI: 10.1007/s11010-018-3290-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 01/18/2018] [Indexed: 12/15/2022]
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14
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Nitric oxide contributes to high-salt perception in a blood-sucking insect model. Sci Rep 2017; 7:15551. [PMID: 29138480 PMCID: PMC5686212 DOI: 10.1038/s41598-017-15861-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 11/02/2017] [Indexed: 11/08/2022] Open
Abstract
In all organisms, salts produce either appetitive or aversive responses depending on the concentration. While low-salt concentration in food elicits positive responses to ingest, high-salt triggers aversion. Still the mechanisms involved in this dual behavior have just started to be uncovered in some organisms. In Rhodnius prolixus, using pharmacological and behavioral assays, we demonstrated that upon high-salt detection in food a nitric oxide (NO) dependent cascade is activated. This activation involves a soluble guanylate cyclase (sGC) and the production of cyclic guanosine monophosphate (cGMP). Thus, appetitive responses to low-salt diets turn to aversion whenever this cascade is activated. Conversely, insects feed over aversive high-salt solutions when it is blocked by reducing NO levels or by affecting the sGC activity. The activation of NO/sGC/cGMP cascade commands the avoidance feeding behavior in R. prolixus. Investigations in other insect species should examine the possibility that high-salt aversion is mediated by NO/sSG/cGMP signaling.
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15
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Bitter taste receptors: Novel insights into the biochemistry and pharmacology. Int J Biochem Cell Biol 2016; 77:184-96. [PMID: 26995065 DOI: 10.1016/j.biocel.2016.03.005] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2016] [Revised: 03/14/2016] [Accepted: 03/15/2016] [Indexed: 01/14/2023]
Abstract
Bitter taste receptors (T2Rs) belong to the super family of G protein-coupled receptors (GPCRs). There are 25 T2Rs expressed in humans, and these interact with a large and diverse group of bitter ligands. T2Rs are expressed in many extra-oral tissues and can perform diverse physiological roles. Structure-function studies led to the identification of similarities and dissimilarities between T2Rs and Class A GPCRs including amino acid conservation and novel motifs. However, the efficacy of most of the T2R ligands is not yet elucidated and the biochemical pharmacology of T2Rs is poorly understood. Recent studies on T2Rs characterized novel ligands including blockers for these receptors that include inverse agonist and antagonists. In this review we discuss the techniques used for elucidating bitter blockers, concept of ligand bias, generic amino acid numbering, the role of cholesterol, and conserved water molecules in the biochemistry and pharmacology of T2Rs.
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16
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Teeling EC, Jones G, Rossiter SJ. Phylogeny, Genes, and Hearing: Implications for the Evolution of Echolocation in Bats. BAT BIOACOUSTICS 2016. [DOI: 10.1007/978-1-4939-3527-7_2] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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17
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Heinze JM, Preissl H, Fritsche A, Frank S. Controversies in fat perception. Physiol Behav 2015; 152:479-93. [PMID: 26340857 DOI: 10.1016/j.physbeh.2015.08.033] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Revised: 08/25/2015] [Accepted: 08/26/2015] [Indexed: 12/22/2022]
Abstract
Nutritional fat is one of the most controversial topics in nutritional research, particularly against the background of obesity. Studies investigating fat taste perception have revealed several associations with sensory, genetic, and personal factors (e.g. BMI). However, neuronal activation patterns, which are known to be highly sensitive to different tastes as well as to BMI differences, have not yet been included in the scheme of fat taste perception. We will therefore provide a comprehensive survey of the sensory, genetic, and personal factors associated with fat taste perception and highlight the benefits of applying neuroimaging research. We will also give a critical overview of studies investigating sensory fat perception and the challenges resulting from multifaceted methodological approaches. In conclusion, we will discuss a multifactorial approach to fat perception to gain a better understanding of the underlying mechanisms that cause varying fat sensitivity which could be responsible for overeating. Such knowledge might be beneficial in new treatment strategies for obesity and overweight.
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Affiliation(s)
- Jaana M Heinze
- Institute of Medical Psychology and Behavioral Neurobiology/fMEG Center, University of Tübingen, Otfried Müller Str. 47, 72076 Tübingen, Germany; Department of Internal Medicine IV, University Hospital Tübingen, Otfried Müller Str. 10, 72076 Tübingen, Germany; Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the University of Tübingen, Otfried Müller Str. 47, 72076 Tübingen, Germany; German Center for Diabetes Research, Otfried Müller Str. 47, 72076 Tübingen, Germany
| | - Hubert Preissl
- Department of Internal Medicine IV, University Hospital Tübingen, Otfried Müller Str. 10, 72076 Tübingen, Germany; Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the University of Tübingen, Otfried Müller Str. 47, 72076 Tübingen, Germany; German Center for Diabetes Research, Otfried Müller Str. 47, 72076 Tübingen, Germany.
| | - Andreas Fritsche
- Department of Internal Medicine IV, University Hospital Tübingen, Otfried Müller Str. 10, 72076 Tübingen, Germany; Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the University of Tübingen, Otfried Müller Str. 47, 72076 Tübingen, Germany; German Center for Diabetes Research, Otfried Müller Str. 47, 72076 Tübingen, Germany
| | - Sabine Frank
- Institute of Medical Psychology and Behavioral Neurobiology/fMEG Center, University of Tübingen, Otfried Müller Str. 47, 72076 Tübingen, Germany
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Yu Y, Hao G, Zhang Q, Hua W, Wang M, Zhou W, Zong S, Huang M, Wen X. Berberine induces GLP-1 secretion through activation of bitter taste receptor pathways. Biochem Pharmacol 2015. [PMID: 26206195 DOI: 10.1016/j.bcp.2015.07.012] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Our previous studies revealed that berberine-mediated GLP-1 secretion was a possible mechanism for berberine exerting good effects on hyperglycemia. This study was designed to ascertain whether berberine-induced secretion of GLP-1 was related with activation of bitter taste receptors expressed in gastrointestinal tract. Western blotting results showed that TAS2R38, a subtype of bitter taste receptor, was expressed on human enteroendocrine NCI-H716 cells. GLP-1 secretion induced by berberine from NCI-H716 cells was inhibited by incubation with anti-TAS2R38 antibody. We further performed gene silencing using siRNA to knockdown TAS2R38 from NCI-H716 cells, which showed that siRNA knockdown of the TAS2R38 reduced berberine-mediated GLP-1 secretion. We adopted inhibitors of PLC and TRPM5 known to be involved in bitter taste transduction to investigate the underlying pathways mediated in berberine-induced GLP-1 secretion. It was found that PLC inhibitor U73122 inhibited berberine-induced GLP-1 release in NCI-H716 cells, while TRPM5 blocker quinine failed to attenuate berberine-induced secretion of GLP-1. The present results demonstrated that berberine stimulated GLP-1 secretion via activation of gut-expressed bitter taste receptors in a PLC-dependent manner. Because berberine was found to be a ligand of bitter taste receptor, the results of present study may provide an explanation for some bitter taste substance obtain hypoglycemic effect.
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Affiliation(s)
- Yunli Yu
- Department of Clinical Pharmacology, The Second Affiliated Hospital of Soochow University, Suzhou 215004, PR China.
| | - Gang Hao
- Suzhou Institute for Food and Drug Control, 215104, PR China.
| | - Quanying Zhang
- Department of Clinical Pharmacology, The Second Affiliated Hospital of Soochow University, Suzhou 215004, PR China.
| | - Wenyan Hua
- Department of Clinical Pharmacology, The Second Affiliated Hospital of Soochow University, Suzhou 215004, PR China.
| | - Meng Wang
- Department of Clinical Pharmacology, The Second Affiliated Hospital of Soochow University, Suzhou 215004, PR China.
| | - Wenjia Zhou
- Department of Clinical Pharmacology, The Second Affiliated Hospital of Soochow University, Suzhou 215004, PR China.
| | - Shunlin Zong
- Department of Clinical Pharmacology, The Second Affiliated Hospital of Soochow University, Suzhou 215004, PR China.
| | - Ming Huang
- Department of Clinical Pharmacology, The Second Affiliated Hospital of Soochow University, Suzhou 215004, PR China.
| | - Xiaozhou Wen
- Jiangsu Province Hospital of Traditional Chinese Medicine, 210029, PR China.
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Tordoff MG, Ellis HT, Aleman TR, Downing A, Marambaud P, Foskett JK, Dana RM, McCaughey SA. Salty taste deficits in CALHM1 knockout mice. Chem Senses 2014; 39:515-28. [PMID: 24846212 DOI: 10.1093/chemse/bju020] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Genetic ablation of calcium homeostasis modulator 1 (CALHM1), which releases adenosine triphosphate from Type 2 taste cells, severely compromises the behavioral and electrophysiological responses to tastes detected by G protein-coupled receptors, such as sweet and bitter. However, the contribution of CALHM1 to salty taste perception is less clear. Here, we evaluated several salty taste-related phenotypes of CALHM1 knockout (KO) mice and their wild-type (WT) controls: 1) In a conditioned aversion test, CALHM1 WT and KO mice had similar NaCl avoidance thresholds. 2) In two-bottle choice tests, CALHM1 WT mice showed the classic inverted U-shaped NaCl concentration-preference function but CALHM1 KO mice had a blunted peak response. 3) In brief-access tests, CALHM1 KO mice showed less avoidance than did WT mice of high concentrations of NaCl, KCl, NH(4)Cl, and sodium lactate (NaLac). Amiloride further ameliorated the NaCl avoidance of CALHM1 KO mice, so that lick rates to a mixture of 1000 mM NaCl + 10 µM amiloride were statistically indistinguishable from those to water. 4) Relative to WT mice, CALHM1 KO mice had reduced chorda tympani nerve activity elicited by oral application of NaCl, NaLac, and sucrose but normal responses to HCl and NH(4)Cl. Chorda tympani responses to NaCl and NaLac were amiloride sensitive in WT but not KO mice. These results reinforce others demonstrating that multiple transduction pathways make complex, concentration-dependent contributions to salty taste perception. One of these pathways depends on CALHM1 to detect hypertonic NaCl in the mouth and signal the aversive taste of concentrated salt.
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Affiliation(s)
- Michael G Tordoff
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA 19104, USA,
| | - Hillary T Ellis
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA 19104, USA
| | - Tiffany R Aleman
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA 19104, USA
| | - Arnelle Downing
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA 19104, USA
| | - Philippe Marambaud
- Litwin-Zucker Research Center for the Study of Alzheimer's Disease, Feinstein Institute for Medical Research, 350 Community Drive, Manhasset, NY 11030, USA
| | - J Kevin Foskett
- Department of Physiology, University of Pennsylvania, 415 Curie Boulevard, Philadelphia, PA 19104, USA
| | - Rachel M Dana
- Department of Biology, Cooper Life Sciences Building, CL121, Ball State University, Muncie, IN 47306, USA and
| | - Stuart A McCaughey
- Center for Medical Education, IUSM-Muncie at Ball State University, 221 N. Celia Avenue, MT 201, Muncie, IN 47306, USA
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20
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Gilbertson TA, Khan NA. Cell signaling mechanisms of oro-gustatory detection of dietary fat: advances and challenges. Prog Lipid Res 2013; 53:82-92. [PMID: 24269201 DOI: 10.1016/j.plipres.2013.11.001] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Accepted: 11/08/2013] [Indexed: 01/19/2023]
Abstract
CD36 and two G-protein coupled receptors (GPCR), i.e., GPR120 and GPR40, have been implicated in the gustatory perception of dietary fats in rodents. These glycoproteins are coupled to increases in free intracellular Ca²⁺ concentrations, [Ca²⁺](i), during their activation by dietary long-chain fatty acids (LCFA). The transient receptor potential type M5 (TRPM5) channel, activated by [Ca²⁺](i), participates in downstream signaling in taste bud cells (TBC). The mice, knocked-out for expression of CD36, GPR120, GPR40 or TRPM5 have a reduced spontaneous preference for fat. The delayed rectifying K⁺ (DRK) channels believed to lie downstream of these receptors are also important players in fat taste transduction. The trigeminal neurons by triggering increases in [Ca²⁺](i) may influence the taste signal to afferent nerve fibers. Why are there so many taste receptor candidates for one taste modality? We discuss the recent advances on the role of CD36, GPR120, GPR40, TRPM5 and DRK channels, in signal transduction in TBC. We shed light on their cross-talk and delineate their roles in obesity as a better understanding of the molecular mechanisms behind their regulation could eventually lead to new strategies to fight against this condition.
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Affiliation(s)
- Timothy A Gilbertson
- Department of Biology, Utah State University, 5305 Old Main Hill, Logan, UT 84322, USA
| | - Naim A Khan
- INSERM U866, Université de Bourgogne/AgroSup, Dijon 2100, France.
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21
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Poothullil JM. Recognition of oral sensory satisfaction and regulation of the volume of intake in humans*. Nutr Neurosci 2013; 8:245-50. [PMID: 16491650 DOI: 10.1080/10284150500449029] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Sensory awareness contributes to the enjoyment of eating and drinking. This study tested the hypothesis that changes in the intensity of oral sensations could be used to regulate the volume of intake. Forty women (< 36 years) volunteered. The participants consumed distilled water, salt water and two concentrations of glucose water under four study conditions. Participants drank until they felt satisfied (basal); satisfied based on taste (taste); satisfied based on fullness (fullness); while watching television (distraction). The treatments were randomized. The study was done in the laboratory between 0830 and 0900. Volume of intake, time taken for intake and thirst intensity variation were measured during each treatment. Analysis of the results showed the taste condition with the lowest volumes and the fullness condition with the highest volumes (p < 0.0001) and time (p < 0.0001). Oral sensory satisfaction could be used to regulate intake of water and water-soluble foods. Sensory distraction may interfere with this regulatory methodology.
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Affiliation(s)
- John M Poothullil
- Brazosport Memorial Hospital, 201 Oak Drive South, #106, Lake Jackson, TX 77566, USA.
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Jones G, Teeling EC, Rossiter SJ. From the ultrasonic to the infrared: molecular evolution and the sensory biology of bats. Front Physiol 2013; 4:117. [PMID: 23755015 PMCID: PMC3667242 DOI: 10.3389/fphys.2013.00117] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Accepted: 05/07/2013] [Indexed: 01/06/2023] Open
Abstract
Great advances have been made recently in understanding the genetic basis of the sensory biology of bats. Research has focused on the molecular evolution of candidate sensory genes, genes with known functions [e.g., olfactory receptor (OR) genes] and genes identified from mutations associated with sensory deficits (e.g., blindness and deafness). For example, the FoxP2 gene, underpinning vocal behavior and sensorimotor coordination, has undergone diversification in bats, while several genes associated with audition show parallel amino acid substitutions in unrelated lineages of echolocating bats and, in some cases, in echolocating dolphins, representing a classic case of convergent molecular evolution. Vision genes encoding the photopigments rhodopsin and the long-wave sensitive opsin are functional in bats, while that encoding the short-wave sensitive opsin has lost functionality in rhinolophoid bats using high-duty cycle laryngeal echolocation, suggesting a sensory trade-off between investment in vision and echolocation. In terms of olfaction, bats appear to have a distinctive OR repertoire compared with other mammals, and a gene involved in signal transduction in the vomeronasal system has become non-functional in most bat species. Bitter taste receptors appear to have undergone a "birth-and death" evolution involving extensive gene duplication and loss, unlike genes coding for sweet and umami tastes that show conservation across most lineages but loss in vampire bats. Common vampire bats have also undergone adaptations for thermoperception, via alternative splicing resulting in the evolution of a novel heat-sensitive channel. The future for understanding the molecular basis of sensory biology is promising, with great potential for comparative genomic analyses, studies on gene regulation and expression, exploration of the role of alternative splicing in the generation of proteomic diversity, and linking genetic mechanisms to behavioral consequences.
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Affiliation(s)
- Gareth Jones
- School of Biological Sciences, University of Bristol Bristol, UK
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Romanov RA, Rogachevskaja OA, Bystrova MF, Kolesnikov SS. Electrical excitability of taste cells. Mechanisms and possible physiological significance. BIOCHEMISTRY MOSCOW SUPPLEMENT SERIES A-MEMBRANE AND CELL BIOLOGY 2012. [DOI: 10.1134/s1990747812010126] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Ríos JM, Mangione AM, Marone L. Tolerance to dietary phenolics and diet breadth in three seed-eating birds: implications for Graminivory. ACTA ACUST UNITED AC 2012; 317:425-33. [PMID: 22696310 DOI: 10.1002/jez.1735] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Revised: 03/02/2012] [Accepted: 04/03/2012] [Indexed: 01/17/2023]
Abstract
The ability to cope with plant secondary compounds (PSCs) has profound implications for an animal's behavior. In the present study, we assessed the tolerance to dietary phenolics in three seed-eating birds: Zonotrichia capensis, Saltatricula multicolor, and Diuca diuca, which differ in their diet breadth. Seeds in their habitat have distinct chemical composition: grass seeds have less PSCs, specifically, less total phenolics than forb seeds. Based on the detoxification limitation hypothesis and using published data of the natural history of these birds in the central Monte desert, we postulate that predominantly and exclusively graminivorous birds such as D. diuca and S. multicolor, respectively, are less tolerant due, in part, to a lower detoxification capacity than those with greater diet breadth, Z. capensis. To achieve this goal, we measured the food intake of diets varying in their concentration of tannic acid (TA). Indicators of tolerance were body mass change, food, TA and water intake, and glucuronic acid output throughout the experiment. Zonotrichia capensis performed better along the tolerance experiment: it maintained body mass from 0 to 4% TA diet, food and TA intake were higher than the other two species at the end of the experiment, and glucuronic acid output by Z. capensis was greater than D. diuca and S. multicolor from 2% TA diet until the end of the experiment. Our results suggest that Z. capensis is the most tolerant species and this physiological trait may explain their greater diet breadth.
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Affiliation(s)
- Juan Manuel Ríos
- Laboratory of Nutritional Ecology, Multidisciplinary Institute of Biological Research (IMIBIO), CCT-CONICET San Luis, San Luis, Argentina
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25
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Henkin RI, Velicu I. Etiological relationships of parotid saliva cyclic nucleotides in patients with taste and smell dysfunction. Arch Oral Biol 2012; 57:670-7. [PMID: 22310165 DOI: 10.1016/j.archoralbio.2012.01.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2010] [Revised: 12/29/2011] [Accepted: 01/08/2012] [Indexed: 11/25/2022]
Abstract
OBJECTIVE We previously demonstrated that parotid saliva cAMP and cGMP were lower in patients with taste and smell dysfunction than in normal subjects. We subsequently demonstrated parotid saliva cAMP and cGMP were inversely correlated with smell loss degree such that as smell loss severity increased parotid saliva cAMP and cGMP decreased proportionately. To learn more about these relationships we studied parotid saliva cAMP and cGMP with respect to aetiology of sensory loss in these patients. DESIGN Parotid saliva cAMP and cGMP in patients with smell loss (hyposmia) who participated in an open label fixed design controlled clinical trial with treatment with oral theophylline were evaluated with respect to their initial etiological diagnosis. Levels of cyclic nucleotides in each etiological category were compared to each other, to the entire patient group and to normal subjects. RESULTS Mean cAMP and cGMP in all patients combined were below those in normals, as previously described. However, categorized by aetiology, there was a stratification of levels of both cyclic nucleotides; some levels were below the normal mean and some were at or above the normal mean. CONCLUSIONS Parotid saliva cyclic nucleotides characterised in hyposmic patients by aetiology indicate (1) there are differential alterations in these nucleotides related to aetiology of sensory dysfunction and (2) these moieties measured prior to treatment indicate which patient groups may benefit from treatment with phosphodiesterase (PDE) inhibitors which increase levels of these moieties and thereby correct their sensory dysfunction.
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Affiliation(s)
- Robert I Henkin
- Center for Molecular Nutrition and Sensory Disorders, The Taste and Smell Clinic, 5125 MacArthur Blvd, NW, Washington, DC 20016, USA.
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26
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Zhao H, Xu D, Zhang S, Zhang J. Genomic and genetic evidence for the loss of umami taste in bats. Genome Biol Evol 2011; 4:73-9. [PMID: 22117084 PMCID: PMC3318850 DOI: 10.1093/gbe/evr126] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/20/2011] [Indexed: 01/29/2023] Open
Abstract
Umami taste is responsible for sensing monosodium glutamate, nucleotide enhancers, and other amino acids that are appetitive to vertebrates and is one of the five basic tastes that also include sour, salty, sweet, and bitter. To study how ecological factors, especially diets, impact the evolution of the umami taste, we examined the umami taste receptor gene Tas1r1 in a phylogenetically diverse group of bats including fruit eaters, insect eaters, and blood feeders. We found that Tas1r1 is absent, unamplifiable, or pseudogenized in each of the 31 species examined, including the genome sequences of two species, suggesting the loss of the umami taste in most, if not all, bats regardless of their food preferences. Most strikingly, vampire bats have also lost the sweet taste receptor gene Tas1r2 and the gene required for both umami and sweet tastes (Tas1r3), being the first known mammalian group to lack two of the five tastes. The puzzling absence of the umami taste in bats calls for a better understanding of the roles that this taste plays in the daily life of vertebrates.
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Affiliation(s)
- Huabin Zhao
- Department of Ecology and Evolutionary Biology, University of Michigan
| | - Dong Xu
- Institute of Molecular Ecology and Evolution, Institutes of Advanced Interdisciplinary Research, East China Normal University, Shanghai, China
| | - Shuyi Zhang
- Institute of Molecular Ecology and Evolution, Institutes of Advanced Interdisciplinary Research, East China Normal University, Shanghai, China
| | - Jianzhi Zhang
- Department of Ecology and Evolutionary Biology, University of Michigan
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27
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Haga M, Yoshie S. Fixation conditions affect the immunoreactivity of gustducin in rat vallate taste buds. ACTA ACUST UNITED AC 2011; 73:91-3. [PMID: 21566335 DOI: 10.1679/aohc.73.91] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
This study aimed to examine gustducin immunoreactivities when adopting various immunostaining conditions in rat vallate taste buds. The occurrence and intensity of the immunoreactivities exhibited specific patterns in accordance with the fixation time. The immunoreactions were localized to only taste hairs, the upper part of the taste bud, after short fixation periods but then to the cell-body cytoplasm excluding the taste hairs after long fixation periods. These immunohistochemical data suggest that the staining protocols, especially the fixation time, cause discrepancies in gustducin immunoreactivities.
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Affiliation(s)
- Maiko Haga
- Department of Histology, The Nippon Dental University School of Life Dentistry at Niigata, Japan.
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28
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Vermehren-Schmaedick A, Scudder C, Timmermans W, Morton DB. Drosophila gustatory preference behaviors require the atypical soluble guanylyl cyclases. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2011; 197:717-27. [PMID: 21350862 DOI: 10.1007/s00359-011-0634-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2010] [Revised: 02/08/2011] [Accepted: 02/13/2011] [Indexed: 11/27/2022]
Abstract
The intracellular messenger cGMP has been suggested to play a role in taste signal transduction in both vertebrates and invertebrates. In the present study, we have examined the role of the Drosophila atypical soluble guanylyl cyclases (sGCs), Gyc-89Da and Gyc-89Db, in larval and adult gustatory preference behaviors. We showed that in larvae, sucrose attraction requires Gyc-89Db and caffeine avoidance requires Gyc-89Da. In adult flies, sucrose attraction is unaffected by mutations in either gene whereas avoidance of low concentrations of caffeine is eliminated by loss of either gene. Similar defective behaviors were observed when cGMP increases were prevented by the expression of a cGMP-specific phosphodiesterase. We also showed that both genes were expressed in gustatory receptor neurons (GRNs) in larval and adult gustatory organs, primarily in a non-overlapping pattern, with the exception of a small group of cells in the adult labellum. In addition, in adults, several cells co-expressed the bitter taste receptor, Gr66a, with either Gyc-89Da or Gyc-89Db. We also showed that the electrophysiological responses of a GRN to caffeine were significantly reduced in flies mutant for the atypical sGCs, suggesting that at least part of the adult behavioral defects were due to a reduced ability to detect caffeine.
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29
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Baquero AF, Gilbertson TA. Insulin activates epithelial sodium channel (ENaC) via phosphoinositide 3-kinase in mammalian taste receptor cells. Am J Physiol Cell Physiol 2010; 300:C860-71. [PMID: 21106690 DOI: 10.1152/ajpcell.00318.2010] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Diabetes is a profound disease that results in a severe lack of regulation of systemic salt and water balance. From our earlier work on the endocrine regulation of salt taste at the level of the epithelial sodium channel (ENaC), we have begun to investigate the ability of insulin to alter ENaC function with patch-clamp recording on isolated mouse taste receptor cells (TRCs). In fungiform and vallate TRCs that exhibit functional ENaC currents (e.g., amiloride-sensitive Na(+) influx), insulin (5-20 nM) caused a significant increase in Na(+) influx at -80 mV (EC(50) = 7.53 nM). The insulin-enhanced currents were inhibited by amiloride (30 μM). Similarly, in ratiometric Na(+) imaging using SBFI, insulin treatment (20 nM) enhanced Na(+) movement in TRCs, consistent with its action in electrophysiological assays. The ability of insulin to regulate ENaC function is dependent on the enzyme phosphoinositide 3-kinase since treatment with the inhibitor LY294002 (10 μM) abolished insulin-induced changes in ENaC. To test the role of insulin in the regulation of salt taste, we have characterized behavioral responses to NaCl using a mouse model of acute hyperinsulinemia. Insulin-treated mice show significant avoidance of NaCl at lower concentrations than the control group. Interestingly, these differences between groups were abolished when amiloride (100 μM) was added into NaCl solutions, suggesting that insulin was regulating ENaC. Our results are consistent with a role for insulin in maintaining functional expression of ENaC in mouse TRCs.
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Affiliation(s)
- Arian F Baquero
- Department of Biology and The Center for Advanced Nutrition, Utah State University, Logan, USA.
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THURGOOD J, MARTINI S. EFFECTS OF THREE EMULSION COMPOSITIONS ON TASTE THRESHOLDS AND INTENSITY RATINGS OF FIVE TASTE COMPOUNDS. J SENS STUD 2010. [DOI: 10.1111/j.1745-459x.2010.00311.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Isono K, Morita H. Molecular and cellular designs of insect taste receptor system. Front Cell Neurosci 2010; 4:20. [PMID: 20617187 PMCID: PMC2896210 DOI: 10.3389/fncel.2010.00020] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2010] [Accepted: 05/16/2010] [Indexed: 12/05/2022] Open
Abstract
The insect gustatory receptors (GRs) are members of a large G-protein coupled receptor family distantly related to the insect olfactory receptors. They are phylogenetically different from taste receptors of most other animals. GRs are often coexpressed with other GRs in single receptor neurons. Taste receptors other than GRs are also expressed in some neurons. Recent molecular studies in the fruitfly Drosophila revealed that the insect taste receptor system not only covers a wide ligand spectrum of sugars, bitter substances or salts that are common to mammals but also includes reception of pheromone and somatosensory stimulants. However, the central mechanism to perceive and discriminate taste information is not yet elucidated. Analysis of the primary projection of taste neurons to the brain shows that the projection profiles depend basically on the peripheral locations of the neurons as well as the GRs that they express. These results suggest that both peripheral and central design principles of insect taste perception are different from those of olfactory perception.
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Affiliation(s)
- Kunio Isono
- Graduate School of Information Sciences, Tohoku University Sendai, Japan
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Zhao H, Zhou Y, Pinto CM, Charles-Dominique P, Galindo-González J, Zhang S, Zhang J. Evolution of the sweet taste receptor gene Tas1r2 in bats. Mol Biol Evol 2010; 27:2642-50. [PMID: 20558596 DOI: 10.1093/molbev/msq152] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Taste perception is an important component of an animal's fitness. The identification of vertebrate taste receptor genes in the last decade has enabled molecular genetic studies of the evolution of taste perception in the context of the ecology and dietary preferences of organisms. Although such analyses have been conducted in a number of species for bitter taste receptors, a similar analysis of sweet taste receptors is lacking. Here, we survey the sole sweet taste-specific receptor gene Tas1r2 in 42 bat species that represent all major lineages of the order Chiroptera, one of the most diverse groups of mammals in terms of diet. We found that Tas1r2 is under strong purifying selection in the majority of the bats studied, with no significant difference in the strength of the selection between insect eaters and fruit eaters. However, Tas1r2 is a pseudogene in all three vampire bat species and the functional relaxation likely started in their common ancestor, probably due to the exclusive feeding of vampire bats on blood and their reliance on infrared sensors rather than taste perception to locate blood sources. Our survey of available genome sequences, together with previous reports, revealed additional losses of Tas1r2 in horse, cat, chicken, zebra finch, and western clawed frog, indicating that sweet perception is not as conserved as previously thought. Nonetheless, we found no common dietary pattern among the Tas1r2-lacking vertebrates, suggesting different causes for the losses of Tas1r2 in different species. The complexity of the ecological factors that impact the evolution of Tas1r2 calls for a better understanding of the physiological roles of sweet perception in different species.
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Affiliation(s)
- Huabin Zhao
- School of Life Sciences, East China Normal University, Shanghai 200062, China
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Kawaguchi H, Yamanaka A, Uchida K, Shibasaki K, Sokabe T, Maruyama Y, Yanagawa Y, Murakami S, Tominaga M. Activation of polycystic kidney disease-2-like 1 (PKD2L1)-PKD1L3 complex by acid in mouse taste cells. J Biol Chem 2010; 285:17277-81. [PMID: 20406802 DOI: 10.1074/jbc.c110.132944] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Five basic tastes (bitter, sweet, umami, salty, and sour) are detected in the four taste areas where taste buds reside. Although molecular mechanisms for detecting bitter, sweet, and umami have been well clarified, those for sour and salty remain poorly understood. Several channels including acid-sensing ion channels have been proposed as candidate sour receptors, but they do not encompass all sour-sensing abilities in vivo. We recently reported a novel candidate for sour sensing, the polycystic kidney disease-2-like 1 (PKD2L1)-PKD1L3 channel complex. This channel is not a traditional ligand-gated channel and is gated open only after removal of an acid stimulus, called an off response. Here we show that off responses upon acid stimulus are clearly observed in native taste cells from circumvallate, but not fungiform papillae, of glutamate decarboxylase 67-green fluorescent protein (GAD67-GFP) knock-in mice, from which Type III taste cells can be visualized, using Ca(2+) imaging and patch clamp methods. Off responses were detected in most cells where PKD2L1 immunoreactivity was observed. Interestingly, the pH threshold for acid-evoked intracellular Ca(2+) increase was around 5.0, a value much higher than that observed in HEK293 cells expressing the PKD2L1-PKD1L3 complex. Thus, PKD2L1-PKD1L3-mediated acid-evoked off responses occurred both in HEK293 cells and in native taste cells, suggesting the involvement of the PKD2L1-PKD1L3 complex in acid sensing in vivo.
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Affiliation(s)
- Hitoshi Kawaguchi
- Division of Cell Signaling, Okazaki Institute for Integrative Bioscience, National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki 444-8787, Japan
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Dangore-Khasbage SB, Degwekar SS, Bhowate RR, Motwani MB, Indurkar AD, Lohe VK, Babar VY. Comparative evaluation of gustatory function between postmenopausal women and age-matched men. Oral Dis 2010; 16:469-75. [DOI: 10.1111/j.1601-0825.2010.01658.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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Caenorhabditis elegans TRPV channels function in a modality-specific pathway to regulate response to aberrant sensory signaling. Genetics 2010; 185:233-44. [PMID: 20176974 DOI: 10.1534/genetics.110.115188] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Olfaction and some forms of taste (including bitter) are mediated by G protein-coupled signal transduction pathways. Olfactory and gustatory ligands bind to chemosensory G protein-coupled receptors (GPCRs) in specialized sensory cells to activate intracellular signal transduction cascades. G protein-coupled receptor kinases (GRKs) are negative regulators of signaling that specifically phosphorylate activated GPCRs to terminate signaling. Although loss of GRK function usually results in enhanced cellular signaling, Caenorhabditis elegans lacking GRK-2 function are not hypersensitive to chemosensory stimuli. Instead, grk-2 mutant animals do not chemotax toward attractive olfactory stimuli or avoid aversive tastes and smells. We show here that loss-of-function mutations in the transient receptor potential vanilloid (TRPV) channels OSM-9 and OCR-2 selectively restore grk-2 behavioral avoidance of bitter tastants, revealing modality-specific mechanisms for TRPV channel function in the regulation of C. elegans chemosensation. Additionally, a single amino acid point mutation in OCR-2 that disrupts TRPV channel-mediated gene expression, but does not decrease channel function in chemosensory primary signal transduction, also restores grk-2 bitter taste avoidance. Thus, loss of GRK-2 function may lead to changes in gene expression, via OSM-9/OCR-2, to selectively alter the levels of signaling components that transduce or regulate bitter taste responses. Our results suggest a novel mechanism and multiple modality-specific pathways that sensory cells employ in response to aberrant signal transduction.
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Sharma RK. Membrane guanylate cyclase is a beautiful signal transduction machine: overview. Mol Cell Biochem 2009; 334:3-36. [PMID: 19957201 DOI: 10.1007/s11010-009-0336-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2009] [Accepted: 11/09/2009] [Indexed: 01/08/2023]
Abstract
This article is a sequel to the four earlier comprehensive reviews which covered the field of membrane guanylate cyclase from its origin to the year 2002 (Sharma in Mol Cell Biochem 230:3-30, 2002) and then to the year 2004 (Duda et al. in Peptides 26:969-984, 2005); and of the Ca(2+)-modulated membrane guanylate cyclase to the year 1997 (Pugh et al. in Biosci Rep 17:429-473, 1997) and then to 2004 (Sharma et al. in Curr Top Biochem Res 6:111-144, 2004). This article contains three parts. The first part is "Historical"; it is brief, general, and freely borrowed from the earlier reviews, covering the field from its origin to the year 2004 (Sharma in Mol Cell Biochem, 230:3-30, 2002; Duda et al. in Peptides 26:969-984, 2005). The second part focuses on the "Ca(2+)-modulated ROS-GC membrane guanylate cyclase subfamily". It is divided into two sections. Section "Historical" and covers the area from its inception to the year 2004. It is also freely borrowed from an earlier review (Sharma et al. in Curr Top Biochem Res 6:111-144, 2004). Section "Ca(2+)-modulated ROS-GC membrane guanylate cyclase subfamily" covers the area from the year 2004 to May 2009. The objective is to focus on the chronological development, recognize major contributions of the original investigators, correct misplaced facts, and project on the future trend of the field of mammalian membrane guanylate cyclase. The third portion covers the present status and concludes with future directions in the field.
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Affiliation(s)
- Rameshwar K Sharma
- Research Divisions of Biochemistry and Molecular Biology, The Unit of Regulatory and Molecular Biology, Salus University, Elkins Park, PA 19027, USA.
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ROS-GC subfamily membrane guanylate cyclase-linked transduction systems: taste, pineal gland and hippocampus. Mol Cell Biochem 2009; 334:199-206. [PMID: 19953306 DOI: 10.1007/s11010-009-0334-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2009] [Accepted: 11/04/2009] [Indexed: 10/20/2022]
Abstract
In the continuous efforts to test the validity of the theme that the Ca(2+)-modulated ROS-GC subfamily system is a universal transduction component of the sensory and sensory-linked network of neurons, this article focuses on the presence and variant biochemical forms of this transduction system in the gustatory epithelium, the site of gustatory transduction; in the pineal, a light-sensitive gland; and in the hippocampus neurons, linked with the perception of all SENSES.
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Gilbertson T, Yu T, Shah B. Gustatory Mechanisms for Fat Detection. Front Neurosci 2009. [DOI: 10.1201/9781420067767-c3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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Shi P, Zhang J. Extraordinary diversity of chemosensory receptor gene repertoires among vertebrates. Results Probl Cell Differ 2009; 47:1-23. [PMID: 19145414 DOI: 10.1007/400_2008_4] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Chemosensation (smell and taste) is important to the survival and reproduction of vertebrates and is mediated by specific bindings of odorants, pheromones, and tastants by chemoreceptors that are encoded by several large gene families. This review summarizes recent comparative genomic and evolutionary studies of vertebrate chemoreceptor genes. It focuses on the remarkable diversity of chemoreceptor gene repertoires in terms of gene number and gene sequence across vertebrates and the evolutionary mechanisms that are responsible for generating this diversity. We argue that the great among-species variation of chemoreceptor gene repertoires is a result of adaptations of individual species to their environments and diets.
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Affiliation(s)
- P Shi
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, The Chinese Academy of Sciences, Arthur-Scheunert-Allee 114-116, 650223, Kunming, China.
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40
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Abstract
Astringency plays an important role in the sensory experience of many foods and beverages, ranging from wine to nuts. Given the recent trend toward fortifying consumables with astringent compounds and the evidence regarding the health benefits of some astringents, the mechanisms and perceptual characteristics of astringency warrant further discussion and investigation. This paper reviews the current state of the literature, including consideration of new methods for describing and measuring astringency, and provides an overview of research concerned with elucidating the physical, physiological, and psychological factors that underlie and mediate perception of this sensation.
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Affiliation(s)
- Martha R Bajec
- Department of Biological Sciences, Brock University, St. Catharines, Ontario, Canada
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41
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Kovacs P, Hajnal A. Altered pontine taste processing in a rat model of obesity. J Neurophysiol 2008; 100:2145-57. [PMID: 18550724 DOI: 10.1152/jn.01359.2007] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The increased palatability of modern diet contributes to eating beyond homeostatic need and in turn to the growing prevalence of obesity. How palatability is coded in taste-evoked neural activity and whether this activity differs between obese and lean remains unknown. To investigate this, we used extracellular single-unit recording in the second central gustatory relay, the pontine parabrachial nucleus while stimulating the tongue with various concentrations of sucrose (0.01-1.5 M) in Otsuka Long Evans Tokushima Fatty (OLETF) rats, lacking CCK-1R. The analyses included a total of 179 taste-responsive neurons in age-matched prediabetic, obese OLETF and lean Long Evans Tokushima Otsuka (LETO) controls. Compared with LETO, we found more NaCl-, and fewer sucrose-responsive neurons (67 vs. 47% and 14 vs. 32%), and an overall reduced response magnitude to sucrose in the OLETF rats. Further, in the obese rats there was a rightward shift in sucrose concentration-response functions relative to lean controls with a higher response-threshold (0.37+/-0.05 vs. 0.23+/-0.2 M, P<0.05) and maximal neural response to higher sucrose concentrations (0.96+/-0.07 vs. 0.56+/-0.5 M, P<0.001). These findings demonstrate altered central gustatory processing for sucrose in obese OLETF rat and further support the notion that palatability is encoded in the across neuron pattern.
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Affiliation(s)
- Peter Kovacs
- Department of Neural and Behavioral Sciences H181, College of Medicine, The Pennsylvania State University, Hershey, PA 17033, USA
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42
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McCaughey SA. The taste of sugars. Neurosci Biobehav Rev 2008; 32:1024-43. [PMID: 18499254 DOI: 10.1016/j.neubiorev.2008.04.002] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2007] [Revised: 03/27/2008] [Accepted: 04/10/2008] [Indexed: 10/22/2022]
Abstract
Sugars evoke a distinctive perceptual quality ("sweetness" in humans) and are generally highly preferred. The neural basis for these phenomena is reviewed for rodents, in which detailed electrophysiological measurements have been made. A receptor has been identified that binds sweeteners and activates G-protein-mediated signaling in taste receptor cells, which leads to changes in neural firing rates in the brain, where perceptions of taste quality, intensity, and palatability are generated. Most cells in gustatory nuclei are broadly tuned, so quality perception presumably arises from patterns of activity across neural populations. However, some manipulations affect only the most sugar-oriented cells, making it useful to consider them as a distinct neural subtype. Quality perception may also arise partly due to temporal patterns of activity to sugars, especially within sugar-oriented cells that give large but delayed responses. Non-specific gustatory neurons that are excited by both sugars and unpalatable stimuli project to ventral forebrain areas, where neural responses provide a closer match with behavioral preferences. This transition likely involves opposing excitatory and inhibitory influences by different subgroups of gustatory cells. Sweeteners are generally preferred over water, but the strength of this preference can vary across time or between individuals, and higher preferences for sugars are often associated with larger taste-evoked responses.
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Affiliation(s)
- Stuart A McCaughey
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA 19104-3308, United States.
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Abstract
STC-1 cells have been established as an enteroendocrine cell line from the small intestine. By monitoring the level of intracellular Ca using a calcium-imaging technique, cellular responses of intestinal STC-1 cells to compounds of five basic tastants were investigated. Although this cell line was known to respond to bitter compounds, we found that compounds of the other four basic tastants also stimulate STC-1 cells. When solutions containing glutamate, sucrose, HCl, or NaCl were applied, the intracellular Ca concentration in STC-1 cells significantly increased. We thus demonstrated that the gastrointestinal system can sense all five basic taste stimuli, and that STC-1 cells emerge as a new cell model for studying the molecular mechanism of signaling pathways of the five basic tastants.
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Merigo F, Benati D, Galie M, Crescimanno C, Osculati F, Sbarbati A. Immunohistochemical Localization of Cystic Fibrosis Transmembrane Regulator and Clara Cell Secretory Protein in Taste Receptor Cells of Rat Circumvallate Papillae. Chem Senses 2007; 33:231-41. [DOI: 10.1093/chemse/bjm082] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
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Ramos Da Conceicao Neta ER, Johanningsmeier SD, McFeeters RF. The chemistry and physiology of sour taste--a review. J Food Sci 2007; 72:R33-8. [PMID: 17995849 DOI: 10.1111/j.1750-3841.2007.00282.x] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Sour taste is the key element in the flavor profile of food acidulants. Understanding the chemistry and physiology of sour taste is critical for efficient control of flavor in the formulation of acid and acidified foods. After a brief introduction to the main applications of food acidulants, several chemical parameters associated with sour taste are discussed. Special emphasis is given to hydrogen ions, protonated (undissociated) acid species, titratable acidity, anions, molar concentration, and physical and chemical properties of organic acids. This article also presents an overview of the physiology of sour taste and proposed theories for the transduction mechanisms for sour taste. The physiology of sour taste perception remains controversial and significant diversity exists among species with regard to cellular schemes used for detection of stimuli. The variety of mechanisms proposed, even within individual species, highlights the complexity of elucidating sour taste transduction. However, recent evidence suggests that at least one specific sour taste receptor protein has been identified.
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Affiliation(s)
- Edith Ramos Ramos Da Conceicao Neta
- U.S. Dept. of Agriculture, Agricultural Research Service, and North Carolina Agricultural Research Service, Dept. of Food Science, North Carolina State Univ., Raleigh, NC, 27695-7624, USA
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Kamerud JK, Delwiche JF. Individual differences in perceived bitterness predict liking of sweeteners. Chem Senses 2007; 32:803-10. [PMID: 17646203 DOI: 10.1093/chemse/bjm050] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Although recent molecular studies suggest that only one receptor and one signaling pathway are involved in the perception of sweetness, this seems to contradict everyday experience that people not only have different likes and dislikes of certain sweeteners but also perceive the sweeteners differently. One possible explanation is that variation in liking of sweeteners is due, in part, to variation across individuals in sensitivity to nonsweet tastes, such as bitterness, which are transduced by a variety of receptors. Fifty individuals were asked to rate intensities of several taste attributes of 10 sweeteners and to give hedonic assessments of each sweetener. Additionally, their sensitivity to 6-n-propyl-3-thiouracil (PROP) was determined. Results indicated that when matched for sweetness, the perception of bitterness and the sweetener compound were the 2 largest factors contributing to overall liking of a sweetener. Sensitivity to PROP did not contribute significantly to the model.
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Affiliation(s)
- Jennifer K Kamerud
- Department of Food Science and Technology, The Ohio State University, Columbus, OH 43210, USA
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Choi S, Lee M, Shiu AL, Yo SJ, Halldén G, Aponte GW. GPR93 activation by protein hydrolysate induces CCK transcription and secretion in STC-1 cells. Am J Physiol Gastrointest Liver Physiol 2007; 292:G1366-75. [PMID: 17290006 DOI: 10.1152/ajpgi.00516.2006] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
In the intestinal lumen, protein hydrolysate increases the transcription and release of cholecystokinin (CCK) from enteroendocrine cells of the duodenal-jejunal mucosa. Our recent discovery that a G protein-coupled receptor, GPR93, is activated by dietary protein hydrolysate causing induced intracellular calcium-mediated signaling events in intestinal epithelial cells raises a possibility that GPR93 might be involved in the protein hydrolysate induction of CCK expression and/or secretion. Using the enteroendocrine STC-1 cells as a model, the present study demonstrates that increasing expression of GPR93 amplifies the peptone induction of endogenous CCK mRNA levels. A similar increase in CCK transcription, indicated by the luciferase reporter activity driven by an 820-bp CCK promoter, is also observed in response to peptone at a dose as little as 6.25 mg/ml, but not to lysophosphatidic acid (LPA), an agonist of GPR93. We discovered that the upregulation of CCK transcription involves ERK1/2, PKA, and calmodulin-dependent protein kinase-mediated pathways. Additionally, GPR93 activation by peptone induces a response in CCK release at 15 min, which continues over a 2-h period. The cAMP level in STC-1 cells overexpressing GPR93 is induced at a greater extent by peptone than by LPA, suggesting a possible explanation of the different effects of peptone and LPA on CCK transcription and secretion. Our data indicate that GPR93 can contribute to the observed induction of CCK expression and secretion by peptone and provide evidence that G protein-coupled receptors can transduce dietary luminal signals.
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Affiliation(s)
- Sungwon Choi
- Dept. of Nutritional Sciences and Toxicology, Univ. of California, 119 Morgan Hall, Berkeley, CA 94720-3104, USA
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48
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Yoshida R, Yasumatsu K, Shigemura N, Ninomiya Y. Coding channels for taste perception: information transmission from taste cells to gustatory nerve fibers. ACTA ACUST UNITED AC 2007; 69:233-42. [PMID: 17287578 DOI: 10.1679/aohc.69.233] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Taste signals are first detected by the taste receptor cells, which are located in taste buds existing in the tongue, soft palate, larynx and epiglottis. Taste receptor cells contact with the chemical compounds in oral cavity through the apical processes which protrude into the taste pore. Interaction between chemical compounds and the taste receptor produces activation of taste receptor cells directly or indirectly. Then the signals are transmitted to gustatory nerve fibers and higher order neurons. A recent study demonstrated many similarities between response properties of taste receptor cells with action potentials and those of the gustatory nerve fibers innervating them, suggesting information derived from receptor cells generating action potentials may form a major component of taste information that is transmitted to gustatory nerve fibers. These findings may also indicate that there is no major modification of taste information sampled by taste receptor cells in synaptic transmission from taste cells to nerve fibers although there is indirect evidence. In the peripheral taste system, gustatory nerve fibers may selectively contact with taste receptor cells that have similar response properties and convey constant taste information to the higher order neurons.
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Affiliation(s)
- Ryusuke Yoshida
- Section of Oral Neuroscience, Graduate School of Dental Sciences, Kyushu University, Japan
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49
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Romanov RA, Rogachevskaja OA, Bystrova MF, Jiang P, Margolskee RF, Kolesnikov SS. Afferent neurotransmission mediated by hemichannels in mammalian taste cells. EMBO J 2007; 26:657-67. [PMID: 17235286 PMCID: PMC1794384 DOI: 10.1038/sj.emboj.7601526] [Citation(s) in RCA: 265] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2006] [Accepted: 12/05/2006] [Indexed: 01/06/2023] Open
Abstract
In mammalian taste buds, ionotropic P2X receptors operate in gustatory nerve endings to mediate afferent inputs. Thus, ATP secretion represents a key aspect of taste transduction. Here, we characterized individual vallate taste cells electrophysiologically and assayed their secretion of ATP with a biosensor. Among electrophysiologically distinguishable taste cells, a population was found that released ATP in a manner that was Ca(2+) independent but voltage-dependent. Data from physiological and pharmacological experiments suggested that ATP was released from taste cells via specific channels, likely to be connexin or pannexin hemichannels. A small fraction of ATP-secreting taste cells responded to bitter compounds, indicating that they express taste receptors, their G-protein-coupled and downstream transduction elements. Single cell RT-PCR revealed that ATP-secreting taste cells expressed gustducin, TRPM5, PLCbeta2, multiple connexins and pannexin 1. Altogether, our data indicate that tastant-responsive taste cells release the neurotransmitter ATP via a non-exocytotic mechanism dependent upon the generation of an action potential.
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Affiliation(s)
- Roman A Romanov
- Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, Russia
| | - Olga A Rogachevskaja
- Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, Russia
| | - Marina F Bystrova
- Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, Russia
| | - Peihua Jiang
- Department of Physiology and Biophysics, Mount Sinai School of Medicine, New York, NY, USA
| | - Robert F Margolskee
- Department of Physiology and Biophysics, Mount Sinai School of Medicine, New York, NY, USA
| | - Stanislav S Kolesnikov
- Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, Russia
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50
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Sternini C. Taste receptors in the gastrointestinal tract. IV. Functional implications of bitter taste receptors in gastrointestinal chemosensing. Am J Physiol Gastrointest Liver Physiol 2007; 292:G457-61. [PMID: 17095755 DOI: 10.1152/ajpgi.00411.2006] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Changes in the luminal contents of the gastrointestinal tract modulate gastrointestinal functions, including absorption of nutrients, food intake, and protection against harmful substances. The current notion is that mucosal enteroendocrine cells act as primary chemoreceptors by releasing signaling molecules in response to changes in the luminal environment, which in turn activate nerve terminals. The recent discovery that taste receptors and G protein subunits alpha-gustducin and alpha-transducin, involved in gustatory signal transduction, are expressed in the gastrointestinal mucosa supports the concept of a chemosensory machinery in the gastrointestinal tract. An understanding of luminal sensing processes responsible for the generation of the appropriate functional response to specific nutrients and nonnutrients is of clinical importance since aberrant or unsteady responses to changes in luminal contents might result in disease states ranging from intoxication to feeding disorders and inflammation. The purpose of this theme article is to discuss the functional implications of bitter taste signaling molecules in the gastrointestinal tract deduced by their localization in selected populations of epithelial cells and their relationship with neural pathways responsible for the generation of specific responses to luminal contents.
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Affiliation(s)
- Catia Sternini
- CURE Digestive Diseases Research Center, VAGLAHS, Los Angeles, CA 90073, USA.
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