Regional Differences in Taste Responsiveness: Effect of Stimulus and Tasting Mode.

Regional Differences in Taste Responsiveness: Effect of Stimulus and Tasting Mode.

Chem Senses. 2018 Aug 27;:

Authors: Colvin JL, Pullicin AJ, Lim J

Abstract
Previous studies have shown that there are differences in taste responses between various regions of the tongue. Most of those studies used a controlled 'passive' tasting mode due to the nature of investigation. However, food is rarely tasted in a passive manner. In addition, recent studies have suggested that humans can taste maltooligosaccharides (MOS) and that the gustatory detection of MOS is independent of the known sweet receptor. It is unknown whether regional differences in responsiveness to MOS exist. This study was set up to revisit previous work by investigating the effects of tasting mode ('passive' vs. 'active') on regional differences in taste responsiveness to sucrose, monopotassium glutamate (MPG), and quinine, while also investigating potential regional differences in responsiveness to MOS. The stimuli were applied to one of four target areas, the left and right sides of the front and back of the tongue, using cotton-tipped swabs. In the passive tasting condition, the front of the tongue was found to be more responsive to both sucrose and MOS, but no regional differences were seen for quinine and MPG. In contrast, in the active tasting condition, the back of the tongue was found to be more responsive to quinine and MPG, but no differences were found of sucrose or MOS. These findings indicate that there are regional differences in taste responsiveness between the front and back of the tongue, and that regional responsiveness is dependent on stimulus and tasting mode.

PMID: 30165578 [PubMed - as supplied by publisher]

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G protein γ subunit Gγ13 is essential for olfactory function and aggressive behavior in mice.

G protein γ subunit Gγ13 is essential for olfactory function and aggressive behavior in mice.

Neuroreport. 2018 Aug 28;:

Authors: Liu Q, Li S, Lu C, Yu CR, Huang L

Abstract
Most olfactory receptors in vertebrates are G protein-coupled receptors, whose activation by odorants initiates intracellular signaling cascades through heterotrimeric G proteins consisting of α, β, and γ subunits. Abolishment of the α subunits such as Gαolf in the main olfactory epithelium and Gαi2 and Gαo in the vomeronasal organ resulted in anosmia and/or impaired behavioral responses. In this study, we report that a G protein γ subunit, Gγ13, is expressed in a spatiotemporal manner similar to those of Gαolf and Gαi2 in the olfactory system and vomeronasal organ, respectively. In addition, Gγ13 was found in the glomeruli of the main olfactory bulb but was largely absent in the glomeruli of the accessory olfactory bulb. Using the Cre-loxP system, the Gγ13's gene Gng13 was nullified in the mature olfactory sensory neurons and apical vomeronasal sensory neurons where the Cre recombinase was expressed under the promoter of the Omp gene for the olfactory marker protein. Immunohistochemistry indicated much reduced expression of Gγ13 in the apical vomeronasal epithelium of the mutant mice. Behavioral experiments showed that the frequency and duration of aggressive encounters in the male mutant mice were significantly lower than in WT male mice. Taken together, these data suggest that the Gγ13 subunit is a critical signaling component in both the main olfactory epithelium and apical vomeronasal epithelium, and it plays an essential role in odor-triggered social behaviors including male-male aggression.This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. https://ift.tt/1hexVwJ.

PMID: 30157062 [PubMed - as supplied by publisher]

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The crystal structure of gurmarin, a sweet-taste suppressing protein: Identification of the amino acid residues essential for inhibition.

The crystal structure of gurmarin, a sweet-taste suppressing protein: Identification of the amino acid residues essential for inhibition.

Chem Senses. 2018 Aug 18;:

Authors: Sigoillot M, Brockhoff A, Neiers F, Poirier N, Belloir C, Legrand P, Charron C, Roblin P, Meyerhof W, Briand L

Abstract
Gurmarin is a highly specific sweet-taste suppressing protein in rodents that is isolated from the Indian plant Gymnemasylvestre. Gurmarin consists of 35 amino acid residues containing three intramolecular disulfide bridges that form a cystine knot. Here, we report the crystal structure of gurmarin at a 1.45 Å resolution and compare it with previously reported NMR solution structures. The atomic structure at this resolution allowed us to identify a very flexible region consisting of hydrophobic residues. Some of these amino acid residues had been identified as a putative binding site for the rat sweet taste receptor in a previous study. By combining alanine-scanning mutagenesis of the gurmarin molecule and a functional cell-based receptor assay, we confirmed that some single point mutations in these positions drastically affect sweet taste receptor inhibition by gurmarin.

PMID: 30137256 [PubMed - as supplied by publisher]

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Self-reported smoking status, TAS2R38 variants, and propylthiouracil phenotype: an exploratory crowdsourced cohort study.

Self-reported smoking status, TAS2R38 variants, and propylthiouracil phenotype: an exploratory crowdsourced cohort study.

Chem Senses. 2018 Aug 18;:

Authors: Baker AN, Miranda AM, Garneau NL, Hayes JE

Abstract
TAS2R38 gene variants, which confer sensitivity to specific bitter tastants (e.g., 6-n-propylthiouracil), have been repeatedly associated with lower alcohol use via greater bitterness perception, but research exploring TAS2R38 variation in relation to smoking shows mixed results. In both, the working hypothesis is that 1 or more copies of the functional allele increase bitterness and may provide a barrier to early use. Such a barrier to initiation may, conceivably, manifest as differential rates of current use across diplotypes. Here, an age-diverse convenience sample (n=886) of Denver Museum of Nature & Science guests was used to explore cross-sectional relationships between TAS2R38 diplotype, self-reported tobacco use (current, former, never smoker), and a rapid measure of 6-n-propylthiouracil (PROP) phenotype (bitterness of filter paper discs). TAS2R38 diplotypes were determined by Sanger sequencing. After excluding rare diplotypes, data from 814 participants were analyzed. A mix of current (~10%), former (25%), and never smokers (65%) were included. As expected, there was a relationship between TAS2R38 diplotype and PROP bitterness. However, contrary to our hypothesis, there was no evidence of a relationship between diplotype and smoker status among participants with common TAS2R38 diplotypes. Notably, we observed a relationship between PROP bitterness and smoking status, but the effect was opposite of what was expected: current smokers perceived higher (not lower) bitterness than never smokers. When all the various factors (diplotype, age, sex and smoking status) were included in ANOVA, all remained predictive of PROP bitterness. Reasons for greater phenotypic bitterness among current smokers is unknown and merits further study.

PMID: 30137252 [PubMed - as supplied by publisher]

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Combining Two Selection Principles: Sensor Arrays Based on Both Biomimetic Recognition and Chemometrics.

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Combining Two Selection Principles: Sensor Arrays Based on Both Biomimetic Recognition and Chemometrics.

Front Chem. 2018;6:268

Authors: Cuypers W, Lieberzeit PA

Abstract
Electronic noses mimic smell and taste senses by using sensor arrays to assess complex samples and to simultaneously detect multiple analytes. In most cases, the sensors forming such arrays are not highly selective. Selectivity is attained by pattern recognition/chemometric data treatment of the response pattern. However, especially when aiming at quantifying analytes rather than qualitatively detecting them, it makes sense to implement chemical recognition via receptor layers, leading to increased selectivity of individual sensors. This review focuses on existing sensor arrays developed based on biomimetic approaches to maximize chemical selectivity. Such sensor arrays for instance use molecularly imprint polymers (MIPs) in both e-noses and e-tongues, for example, to characterize headspace gas compositions or to detect protein profiles. Other array types employ entire cells, proteins, and peptides, as well as aptamers, respectively, in multisensor systems. There are two main reasons for combining chemoselectivity and chemometrics: First, this combined approach increases the analytical quality of quantitative data. Second, the approach helps in gaining a deeper understanding of the olfactory processes in nature.

PMID: 30128311 [PubMed]

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Evolutionary ecology of chemosensation and its role in sensory drive.

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Evolutionary ecology of chemosensation and its role in sensory drive.

Curr Zool. 2018 Aug;64(4):525-533

Authors: Yohe LR, Brand P, Handling editor: Rebecca Fuller

Abstract
All behaviors of an organism are rooted in sensory processing of signals from its environment, and natural selection shapes sensory adaptations to ensure successful detection of cues that maximize fitness. Sensory drive, or divergent selection for efficient signal transmission among heterogeneous environments, has been a useful hypothesis for describing sensory adaptations, but its current scope has primarily focused on visual and acoustic sensory modalities. Chemosensation, the most widespread sensory modality in animals that includes the senses of smell and taste, is characterized by rapid evolution and has been linked to sensory adaptations to new environments in numerous lineages. Yet, olfaction and gustation have been largely underappreciated in light of the sensory drive hypothesis. Here, we examine why chemosensory systems have been overlooked and discuss the potential of chemosensation to shed new insight on the sensory drive hypothesis and vice versa. We provide suggestions for developing a framework to better incorporate studies of chemosensory adaptation that have the potential to shape a more complete, coherent, and holistic interpretation of the sensory drive.

PMID: 30108633 [PubMed]

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Sensory Adaptation to Chemical Cues by Vomeronasal Sensory Neurons.

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Sensory Adaptation to Chemical Cues by Vomeronasal Sensory Neurons.

eNeuro. 2018 Jul-Aug;5(4):

Authors: Wong WM, Nagel M, Hernandez-Clavijo A, Pifferi S, Menini A, Spehr M, Meeks JP

Abstract
Sensory adaptation is a source of experience-dependent feedback that impacts responses to environmental cues. In the mammalian main olfactory system (MOS), adaptation influences sensory coding at its earliest processing stages. Sensory adaptation in the accessory olfactory system (AOS) remains incompletely explored, leaving many aspects of the phenomenon unclear. We investigated sensory adaptation in vomeronasal sensory neurons (VSNs) using a combination of in situ Ca2+ imaging and electrophysiology. Parallel studies revealed prominent short-term sensory adaptation in VSNs upon repeated stimulation with mouse urine and monomolecular bile acid ligands at interstimulus intervals (ISIs) less than 30 s. In such conditions, Ca2+ signals and spike rates were often reduced by more than 50%, leading to dramatically reduced chemosensory sensitivity. Short-term adaptation was reversible over the course of minutes. Population Ca2+ imaging experiments revealed the presence of a slower form of VSN adaptation that accumulated over dozens of stimulus presentations delivered over tens of minutes. Most VSNs showed strong adaptation, but in a substantial VSN subpopulation adaptation was diminished or absent. Investigation of same- and opposite-sex urine responses in male and female VSNs revealed that adaptation to same-sex cues occurred at ISIs up to 180 s, conditions that did not induce adaptation to opposite-sex cues. This result suggests that VSN sensory adaptation can be modulated by sensory experience. These studies comprehensively establish the presence of VSN sensory adaptation and provide a foundation for future inquiries into the molecular and cellular mechanisms of this phenomenon and its impact on mammalian behavior.

PMID: 30105301 [PubMed - in process]

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Plant odour and sex pheromone are integral elements of specific mate recognition in an insect herbivore.

Plant odour and sex pheromone are integral elements of specific mate recognition in an insect herbivore.

Evolution. 2018 Aug 10;:

Authors: Borrero-Echeverry F, Bengtsson M, Nakamuta K, Witzgall P

Abstract
Specific mate recognition relies on the chemical senses in most animals, and especially in nocturnal insects. Two signal types mediate premating olfactory communication in terrestrial habitats: sex pheromones, which blend into an atmosphere of plant odorants. We show that host plant volatiles affect the perception of sex pheromone in males of the African cotton leafworm Spodoptera littoralis and that pheromone and plant volatiles are not perceived as independent messages. In clean air, S. littoralis males are attracted to single synthetic pheromone components or even the pheromone of a sibling species, Oriental cotton leafworm S. litura. Presence of host plant volatiles, however, reduces the male response to deficient or heterospecific pheromone signals. That plant cues enhance discrimination of sex pheromone quality confirms the idea that specific mate recognition in noctuid moths has evolved in concert with adaptation to host plants. Shifts in either female host preference or sex pheromone biosynthesis give rise to new communication channels that have the potential to initiate or contribute to reproductive isolation. This article is protected by copyright. All rights reserved.

PMID: 30095166 [PubMed - as supplied by publisher]

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Calculation of Canine Dose Rate Conversion Factors for Photons and Electrons.

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Calculation of Canine Dose Rate Conversion Factors for Photons and Electrons.

Health Phys. 2018 Jan;114(1):20-26

Authors: Trevino JF, Marianno C

Abstract
Urban search and rescue (USAR) dogs are valuable members of their teams and play key roles in performing successful missions. A pair of dogs can do the work of dozens of people, the dogs are able to quickly sniff around collapsed structures and zip through constricted hallways with far greater accuracy than their plodding human counterparts. While in contaminated areas, their human counterparts are afforded the benefit of personal protective equipment (PPE) to keep exposures to chemical, biological and radiological substances to a minimum; USAR dogs, on the other hand, are not. In an effort to allow USAR dogs to be used to their full potential, PPE is often not worn as it inhibits their ability to move in and around obstacles to use their strong senses of smell and hearing. In addition, these animals may snag or be snagged on debris or structures, which may require rescue of the animal. In a collaborative effort between Texas A&M University's Department of Nuclear Engineering and the College of Veterinary Medicine, researchers are attempting to estimate the extent of the radiation doses received by these valuable team members during missions where radioactive contamination is present. Currently there are no dose rate conversion factors for USAR dogs, and those that are available are calculated at a height of 1 m. To address this issue, a more suitable height of 40 cm was chosen, and dose conversion factors were calculated for monoenergetic photon sources ranging from 15 keV to 15 MeV and for monoenergetic electron sources ranging from 10 keV to 10 MeV. The radioactivity is assumed to be uniformly distributed on the surface of the ground. Forty centimeters was chosen as the height of interest for the three breeds FEMA prefers as USAR dogs. These dose conversion factors will permit dose estimates to be made, allowing these animals to do their jobs successfully while keeping their radiation doses as low as possible.

PMID: 30085966 [PubMed - in process]

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BioBits™ Explorer: A modular synthetic biology education kit.

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BioBits™ Explorer: A modular synthetic biology education kit.

Sci Adv. 2018 Aug;4(8):eaat5105

Authors: Huang A, Nguyen PQ, Stark JC, Takahashi MK, Donghia N, Ferrante T, Dy AJ, Hsu KJ, Dubner RS, Pardee K, Jewett MC, Collins JJ

Abstract
Hands-on demonstrations greatly enhance the teaching of science, technology, engineering, and mathematics (STEM) concepts and foster engagement and exploration in the sciences. While numerous chemistry and physics classroom demonstrations exist, few biology demonstrations are practical and accessible due to the challenges and concerns of growing living cells in classrooms. We introduce BioBits™ Explorer, a synthetic biology educational kit based on shelf-stable, freeze-dried, cell-free (FD-CF) reactions, which are activated by simply adding water. The FD-CF reactions engage the senses of sight, smell, and touch with outputs that produce fluorescence, fragrances, and hydrogels, respectively. We introduce components that can teach tunable protein expression, enzymatic reactions, biomaterial formation, and biosensors using RNA switches, some of which represent original FD-CF outputs that expand the toolbox of cell-free synthetic biology. The BioBits™ Explorer kit enables hands-on demonstrations of cutting-edge science that are inexpensive and easy to use, circumventing many current barriers for implementing exploratory biology experiments in classrooms.

PMID: 30083608 [PubMed - in process]

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Influence of Tannin Extract and Yeast Extract on Color Preservation and Anthocyanin Content of Mulberry Wine.

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Influence of Tannin Extract and Yeast Extract on Color Preservation and Anthocyanin Content of Mulberry Wine.

J Food Sci. 2018 Apr;83(4):1084-1093

Authors: You Y, Li N, Han X, Guo J, Liu G, Huang W, Zhan J

Abstract
The color of mulberry wine is extremely unstable in processing and aging. This paper investigates the effects of tannin extract and yeast extract on the color and color-preserving characteristics of mulberry wine made from the Dashi cultivar. The results showed that the maximum absorption wavelength in both tannin extract and yeast extract groups changed generating the red shift effect. The color of the tannin extract maintained a good gloss in the first 4 months, while the yeast extract group showed remarkable color preservation for the first 3 months. The total anthocyanin and cyanidin-3-rutinoside contents in both experiment groups were significantly higher than that of the control group, thus proving that tannin extract and yeast extract both exert a remarkably positive effect on preserving the color of mulberry wine during its aging. Moreover, sensory analysis indicated that the quality of mulberry wine treated with tannin extract was significantly higher than that of the control.
PRACTICAL APPLICATION: The distinct color of mulberry wine is one of the foremost qualities that imprints on consumers' senses, but it is extremely unstable in processing and aging. However, the color protection of mulberry wine was not studied previously. In this study, we found that tannin extract and yeast extract both exert a remarkably positive effect on preserving the color of mulberry wine during aging. The study is of great significance as a guide to improving the color stability of mulberry wine, thereby also improving and promoting the development of the mulberry deep processing industry.

PMID: 29538798 [PubMed - indexed for MEDLINE]

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