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1
Jacquemont, Guillaume. "Vivre sans odorat." Cerveau & Psycho N° 120, no. 4 (April 20, 2020): 11b. http://dx.doi.org/10.3917/cerpsy.120.0011b.
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Tran Ba Huy, Patrice. "Odorat et histoire sociale." Communication et langages 126, no. 1 (2000): 85–107. http://dx.doi.org/10.3406/colan.2000.3046.
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Manus, Jean-Marie. "Être NEZ sans odorat." Revue Francophone des Laboratoires 2024, no. 566 (November 2024): 12. http://dx.doi.org/10.1016/s1773-035x(24)00350-2.
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Bonfils, Pierre. "Odorat : de l’aéroportage au cortex." Bulletin de l'Académie Nationale de Médecine 198, no. 6 (June 2014): 1109–22. http://dx.doi.org/10.1016/s0001-4079(19)31262-2.
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Delavaud-Roux, Marie-Hélé€ne. "La métrique des hallucinations dans Les Bacchantes d'Euripide." Dramaturgias, no. 13 (April 21, 2020): 352–263. http://dx.doi.org/10.26512/dramaturgias.vi13.31070.
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Les hallucinations des Ménades mettent en jeu suivant les cas un ou plusieurs sens (vue, ouíˆe, toucher, odorat, gouÌ‚t), comme nous l'avons déjà analysé dans une précédente étude1. Nous souhaitons les réexaminer sous un autre angle, celui de la métrique. Toutes ces hallucinations s'expriment en différentes combinaisons métriques, qui seront l'objet de notre étude.
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Sabiniewicz, Agniezska. "Les femmes enceintes ont-elles un odorat plus développé ?" Cerveau & Psycho N° 164, no. 4 (March 25, 2024): 90–91. http://dx.doi.org/10.3917/cerpsy.164.0090.
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Ningsih, Purnama, Nurul Pratiwi, Supriadi, Dewi Staria Ahmar, Vanny Maria Tiwow, Sri Hastuti Virgianti Pulukadang, and Sitti Rahmawati. "Quantification of Tannin in Chromolaena Odorat (Kirinyu) Leaf Extract." International Journal of Design & Nature and Ecodynamics 19, no. 4 (August 28, 2024): 1341–46. http://dx.doi.org/10.18280/ijdne.190426.
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Lambert, Hervé-Pierre. "Imagination, Neuroscience and Olfaction: Confirmations and Extrapolations." Imaginaire et perception, no. 33 (June 30, 2012): 37–51. http://dx.doi.org/10.35562/iris.2456.
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La prise en compte de l’olfaction dans les sciences cognitives et les neurosciences a notamment permis de s’intéresser aussi aux dysfonctionnements de ce sens et d’examiner certains phénomènes linguistiques (inadéquation entre langage et odorat) ou littéraires (la mémoire proustienne). Neurologie et anthropologie semblent en arriver à la même conclusion sur l’inadéquation universelle entre le langage humain et les odeurs, à l’opposé de la relation entre langage et couleurs.
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Meunier, Nicolas. "Odorat et virus respiratoires :une relation révélée par la Covid-19." médecine/sciences 39, no. 2 (February 2023): 119–28. http://dx.doi.org/10.1051/medsci/2023007.
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L’odorat, sens pendant longtemps sous-estimé chez l’homme, a été mis sur le devant de la scène par sa soudaine disparition, survenue pendant la pandémie de Covid-19, dont l’anosmie est un des symptômes majeurs. Pourtant, depuis longtemps, les virus respiratoires ont été associés aux troubles de l’odorat, dont 25 % seraient liés à une infection virale. L’olfaction débute dans le nez, au sein d’un épithélium olfactif qui a la particularité de contenir des neurones en contact direct avec l’environnement. Plusieurs virus respiratoires sont connus pour leur capacité réplicative au sein de cet épithélium. C’est notamment le cas du virus de la grippe (influenza) et du virus de la bronchiolite (VRS, pour virus respiratoire syncytial), mais leur tropisme pour ce tissu est bien moindre que celui du SARS-CoV-2. La physiopathologie de ce virus dans la cavité nasale a permis de commencer à comprendre les liens existant entre une infection virale et les troubles de l’olfaction.
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Castellani, Marie-Madeleine. "Forbidden Senses in the Different Versions of Florimont." Bien Dire et Bien Aprandre, no. 37 (October 10, 2022): 45–56. http://dx.doi.org/10.54563/bdba.1707.
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La présence des sens interdits – odorat, toucher et goût – dans Florimont, qu’il s’agisse de la mise en prose bourguignonne ou de l’imprimé de 1529 d’Olivier Arnoullet, se révèle très limitée. L’imprimé offre davantage de termes mais se signale aussi par un manque d’intérêt pour des descriptions qui nécessiteraient l’emploi d’adjectifs ou d’adverbes précis et nombreux. La mise en prose fait surtout de certains des sens, notamment du toucher, les signes d’un rituel social et leur donne dans le récit un rôle fonctionnel plus que véritablement sensoriel. S’ils ne sont donc pas « interdits » – nos textes ne font place à aucun jugement moral –, ces sens, comme dans une certaine mesure les sens plus élevés de l’ouïe et de la vue, sont essentiellement présents pour faire avancer et nourrir l’action.
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Qin, Liyu, Mengyue Wang, and Peng Zhang. "The Properties and Development of Sulfur-Free Odorant for Town Gas." Academic Journal of Science and Technology 10, no. 2 (April 15, 2024): 235–38. http://dx.doi.org/10.54097/1vskzh04.
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In this paper, the characteristics, advantages and disadvantages of natural gas sulfur-free odorants and traditional sulfide odorants, as well as the application examples of sulfur-free odorants at home and abroad are analyzed and compared, and the differences between the two odorants in natural gas treatment are discussed. The research shows that the natural gas sulfur-free odorant has the advantages of being more environmentally friendly, safer and more economical than the traditional sulfide odorant. Combined with the actual application cases, the future development trend and prospect of sulfur-free odorant in the natural gas industry are prospected.
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Schwartz, Mathieu, Franck Menetrier, Jean-Marie Heydel, Evelyne Chavanne, Philippe Faure, Marc Labrousse, Frédéric Lirussi, et al. "Interactions Between Odorants and Glutathione Transferases in the Human Olfactory Cleft." Chemical Senses 45, no. 8 (August 21, 2020): 645–54. http://dx.doi.org/10.1093/chemse/bjaa055.
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Abstract Xenobiotic metabolizing enzymes and other proteins, including odorant-binding proteins located in the nasal epithelium and mucus, participate in a series of processes modulating the concentration of odorants in the environment of olfactory receptors (ORs) and finely impact odor perception. These enzymes and transporters are thought to participate in odorant degradation or transport. Odorant biotransformation results in 1) changes in the odorant quantity up to their clearance and the termination of signaling and 2) the formation of new odorant stimuli (metabolites). Enzymes, such as cytochrome P450 and glutathione transferases (GSTs), have been proposed to participate in odorant clearance in insects and mammals as odorant metabolizing enzymes. This study aims to explore the function of GSTs in human olfaction. Using immunohistochemical methods, GSTs were found to be localized in human tissues surrounding the olfactory epithelium. Then, the activity of 2 members of the GST family toward odorants was measured using heterologously expressed enzymes. The interactions/reactions with odorants were further characterized using a combination of enzymatic techniques. Furthermore, the structure of the complex between human GSTA1 and the glutathione conjugate of an odorant was determined by X-ray crystallography. Our results strongly suggest the role of human GSTs in the modulation of odorant availability to ORs in the peripheral olfactory process.
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Youngentob, S. L., P. F. Kent, and F. L. Margolis. "OMP Gene Deletion Results in an Alteration in Odorant-Induced Mucosal Activity Patterns." Journal of Neurophysiology 90, no. 6 (December 2003): 3864–73. http://dx.doi.org/10.1152/jn.00806.2002.
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Previous behavioral work, using a complex five-odorant identification task, demonstrated that olfactory marker protein (OMP) is critically involved in odor processing to the extent that its loss results in an alteration in odorant quality perception. Exactly how the lack of OMP exerts its influence on the perception of odorant quality is unknown. However, there is considerable neurophysiological evidence that different odorants produce different spatiotemporal patterns of neural activity at the level of the mucosa and that these patterns predict the psychophysically determined perceptual relationship among odorants. In this respect, OMP gene deletion is known to result in a constellation of physiologic defects (i.e., marked reduction in the electroolfactogram (EOG) and altered response and recovery kinetics) that would be expected to alter the odorant-induced spatiotemporal activity patterns that are characteristic of different odorants. This, in turn, would be expected to alter the spatiotemporal patterning of information that results from the mucosal projection onto the bulb, thereby changing odorant quality perception. To test the hypothesis that odorant-induced mucosal activity patterns are altered in mice lacking the gene for OMP, we optically recorded the fluorescent changes in response to odorant stimulation from both the septum and turbinates of both OMP-null and control mice using a voltage-sensitive dye (di-4-ANEPPS Molecular Probes, Eugene, OR) and a Dalsa 120 × 120, 12-bit CCD camera. To maintain continuity with the previous behavioral work, the odorants 2-propanol, citral, carvone, ethylacetoacetate, and propyl acetate were again used. Each odorant was randomly presented to each mucosal surface in a Latin-Square design. The results of this study demonstrated that, for both mouse strains, there do indeed exist different spatiotemporal activity patterns for different odorants. More importantly, however, these patterns significantly differed between OMP-null and control mice. That is, although the general regions of characteristic activity for different odorants were the same in both mouse strains, the patterns in the null animals were degraded relative to controls. These data suggest therefore that the alterations in mucosal activity may serve as the substrate for the behaviorally observed changes in odorant quality perception in the null mutant.
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Mackay-Sim, A., and S. Kesteven. "Topographic patterns of responsiveness to odorants in the rat olfactory epithelium." Journal of Neurophysiology 71, no. 1 (January 1, 1994): 150–60. http://dx.doi.org/10.1152/jn.1994.71.1.150.
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1. Regional differences in odorant-induced responsiveness of the rat olfactory epithelium were measured via electrophysiological recordings [negative component of electro-olfactogram (Veog(-)) made from the surface of the olfactory epithelium on the nasal septum]. The nasal septum provided a flat surface from which multiple recordings could be made. 2. Veog(-)s were recorded from a standardized grid of 16 sites. This grid of recording sites extended over most of the surface of the olfactory epithelium on the nasal septum. 3. Twenty-one animals were tested for their responses to seven odorants. The animals were divided into three groups, each of which was tested with two different odorants plus amyl acetate, which provided a comparison between the groups. 4. For each odorant in each animal, topographic maps of relative responsiveness were derived to test whether odorants elicited different patterns of responses in the same individual. Topographic maps of responsiveness were derived also for the animal groups to test for the generality of the form of the maps for different odorants. Response latencies were also measured for each odorant at each recording site. 5. All individuals showed different topographic patterns of responses to the three test odorants. For most odorants, the location of the most responsive site was similar in all animals. In different animals the topographic maps for the same odorant were remarkably similar. Topographic maps for the odorants were all different from one another. 6. These results are consistent with the hypothesis that odorant quality is encoded in the differential spatial distribution of receptor cells whose differences in responsiveness appear to be distributed as a continuum across the epithelium. The results establish for a mammalian species what was previously reported in amphibians. These differences are presumed to be due to differential expression of odorant receptor proteins. 7. The mean response latency was 32 ms. This period was similar for all odorants, all animals, and all recording sites and was independent of Veog(-) amplitude. It is concluded that diffusion through the mucus contributed approximately 6 ms to the latency of onset of the responses to these odorants.
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Burton, Shawn D., Mia Wipfel, Michael Guo, Thomas P. Eiting, and Matt Wachowiak. "A Novel Olfactometer for Efficient and Flexible Odorant Delivery." Chemical Senses 44, no. 3 (January 18, 2019): 173–88. http://dx.doi.org/10.1093/chemse/bjz005.
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Abstract Understanding how sensory space maps to neural activity in the olfactory system requires efficiently and flexibly delivering numerous odorants within single experimental preparations. Such delivery is difficult with current olfactometer designs, which typically include limited numbers of stimulus channels and are subject to intertrial and interchannel contamination of odorants. Here, we present a novel olfactometer design that is easily constructed, modular, and capable of delivering an unlimited number of odorants in air with temporal precision and no detectable intertrial or interchannel contamination. The olfactometer further allows for the flexible generation of odorant mixtures and flexible timing of odorant sequences. Odorant delivery from the olfactometer is turbulent but reliable from trial to trial, supporting operant conditioning of mice in an odorant discrimination task and permitting odorants and concentrations to be mapped to neural activity with a level of precision equivalent to that obtained with a flow dilution olfactometer. This novel design thus provides several unique advantages for interrogating olfactory perception and for mapping sensory space to neural activity in the olfactory system.
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Atasi, Khalil Z., Theping Chen, Judith I. Huddleston, Connie C. Young, and I. H. (Mel) Suffet. "Factor Screening for Ozonating the Taste- and Odor-Causing Compounds in Source Water at Detroit, USA." Water Science and Technology 40, no. 6 (September 1, 1999): 115–22. http://dx.doi.org/10.2166/wst.1999.0276.
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Three odorants, geosmin (earthy), MIB (2-methylisoborneol) (musty), and IPMP (2-isopropyl-3-methoxypyrazine) (decaying vegetation/musty) were spiked into raw water taken from the Detroit River and subjected to bench-scale ozonation (with and without hydrogen peroxide). Statistical experiment design was employed to investigate operating variables such as ozone dose, ozone addition point, temperature, odorant spike level, and presence of hydrogen peroxide. Two additional odorants, cis-3-hexenyl acetate (grassy) and trans,trans-2,4-heptadienal (fishy) were also tested. Results showed that ozonation was capable of mitigating the spiked odorants in the Detroit source water. Ozone dose was the single most important factor in removing the odorants. Presence of hydrogen peroxide (without dose optimization) had a limited effect on odorant removal at tested pH and alkalinity conditions. Ozone application point and water temperature had significant impacts on ozone residual, but not on odorant removal. MIB was most difficult to remove by ozonation among the five spiked odorants.
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McClintock, Timothy S., Qiang Wang, Tomoko Sengoku, William B. Titlow, and Patrick Breheny. "Mixture and Concentration Effects on Odorant Receptor Response Patterns In Vivo." Chemical Senses 45, no. 6 (May 19, 2020): 429–38. http://dx.doi.org/10.1093/chemse/bjaa032.
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Abstract Natural odors are mixtures of volatile chemicals (odorants). Odors are encoded as responses of distinct subsets of the hundreds of odorant receptors and trace amine-associated receptors expressed monogenically by olfactory sensory neurons. This is an elegantly simple mechanism for differentially encoding odors but it is susceptible to complex dose–response relationships and interactions between odorants at receptors, which may help explain olfactory phenomena, such as mixture suppression, synthetic versus elemental odor processing, and poorly predictable perceptual outcomes of new odor mixtures. In this study, in vivo tests in freely behaving mice confirm evidence of a characteristic receptor response pattern consisting of a few receptors with strong responses and a greater number of weakly responding receptors. Odorant receptors responsive to an odor are often unrelated and widely divergent in sequence, even when the odor consists of a single species of odorant. Odorant receptor response patterns to a citrus odor broaden with concentration. Some highly sensitive receptors respond only to a low concentration but others respond in proportion to concentration, a feature that may be critical for concentration-invariant perception. Other tests find evidence of interactions between odorants in vivo. All of the odorant receptor responses to a moderate concentration of the fecal malodor indole are suppressed by a high concentration of the floral odorant, α-ionone. Such suppressive effects are consistent with prior evidence that odorant interactions at individual odorant receptors are common.
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Castro, Tarsila G., Carla Silva, Teresa Matamá, and Artur Cavaco-Paulo. "The Structural Properties of Odorants Modulate Their Association to Human Odorant Binding Protein." Biomolecules 11, no. 2 (January 22, 2021): 145. http://dx.doi.org/10.3390/biom11020145.
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The binding of known odorant molecules to the human odorant-binding protein (hOBP) was evaluated in silico. Docking experiments elucidate the preferable binding site and binding affinity of odorant molecules to hOBP. The physicochemical properties molecular weight (MW), vapor pressure (Vp), hydrophobicity level (logP), number of double bonds (NºDB), degree of unsaturation (DoU) and the chemical classification, were selected for the study of odorant modulation. Here, these properties were analyzed concerning 30 pleasant and 30 unpleasant odorants, chosen to represent a wide variety of compounds and to determine their influence on the binding energy to hOBP. Our findings indicate that MW, logP and Vp are the most important odorant variables, directly correlated to odorant-binding energies (ΔGbinding) towards hOBP. Understanding how the odorants behave when complexed with the OBP in human olfaction opens new possibilities for the development of future biotechnological applications, including sensory devices, medical diagnosis, among others.
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Cinelli, A. R., K. A. Hamilton, and J. S. Kauer. "Salamander olfactory bulb neuronal activity observed by video rate, voltage-sensitive dye imaging. III. Spatial and temporal properties of responses evoked by odorant stimulation." Journal of Neurophysiology 73, no. 5 (May 1, 1995): 2053–71. http://dx.doi.org/10.1152/jn.1995.73.5.2053.
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1. Activity patterns across and within the laminae of the olfactory bulb were analyzed by imaging voltage-sensitive dye responses during odorant stimulation of all or part of the ventral olfactory mucosa. 2. The time course of the signals was generally characterized by a brief, small hyperpolarization, followed by a period of depolarization, and then a longer-lasting hyperpolarization similar to that seen with electric stimulation but with longer durations. 3. The activity was distributed nonhomogeneously across the bulbar laminae in the form of spatially segregated clusters having bandlike appearances. Clusters were observed with three monomolecular odorants, amyl acetate, ethyl-n-butyrate, and limonene, and with the complex odor of meal worms. Although response patterns to different odorants overlapped, they also showed differences in overall distribution. 4. Delivery of high odorant concentrations increased the size of the activated areas and accentuated the degree of response pattern overlap among different odorants. The general properties of the response patterns generated by each odorant were, however, similar at different odorant concentrations and in each of the animals tested. 5. The spatial and temporal distributions of the bulbar responses were somewhat similar regardless of whether the odorants were applied to local epithelial regions via punctate stimulation or to the entire mucosa. Certain regions did, however, have lower thresholds than others for eliciting bulbar activity in response to particular odorants. 6. Odorants applied to regions of the epithelium outside the areas of maximum sensitivity elicited odorant-related activity patterns with depolarizing and hyperpolarizing components similar to those seen with overall stimulation, but only if higher concentrations were used. Activation of distributed odorant sensitivities presumably gave rise to these patterns. 7. These data suggest that subsets of odorant receptor types are found in different areas of the olfactory epithelium, and demonstrate that there is widespread distribution across the epithelium of receptors sensitive to particular odorants. On the basis of the structure of these epithelial fields and the bulb response patterns that they relate to, these findings also provide evidence for complex spatial relationships between the olfactory epithelium and bulb. 8. The findings from this study suggest that representation of odor information in the salamander olfactory bulb does not occur by activation of a few selective bulbar regions, each related to a different odorant species. Instead, large regions of bulbar circuitry are involved in which molecular epitopes may be the unit of representation. Incorporation of new data presented here into a hypothesis of odor coding is discussed.
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Nagayama, Shin, Yuji K. Takahashi, Yoshihiro Yoshihara, and Kensaku Mori. "Mitral and Tufted Cells Differ in the Decoding Manner of Odor Maps in the Rat Olfactory Bulb." Journal of Neurophysiology 91, no. 6 (June 2004): 2532–40. http://dx.doi.org/10.1152/jn.01266.2003.
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Mitral and tufted cells in the mammalian olfactory bulb are principal neurons, each type having distinct projection pattern of their dendrites and axons. The morphological difference suggests that mitral and tufted cells are functionally distinct and may process different aspects of olfactory information. To examine this possibility, we recorded odorant-evoked spike responses from mitral and middle tufted cells in the aliphatic acid- and aldehyde-responsive cluster at the dorsomedial part of the rat olfactory bulb. Homologous series of aliphatic acids and aldehydes were used for odorant stimulation. In response to adequate odorants, mitral cells showed spike responses with relatively low firing rates, whereas middle tufted cells responded with higher firing rates. Examination of the molecular receptive range (MRR) indicated that most mitral cells exhibited a robust inhibitory MRR, whereas a majority of middle tufted cells showed no or only a weak inhibitory MRR. In addition, structurally different odorants that activated neighboring clusters inhibited the spike activity of mitral cells, whereas they caused no or only a weak inhibition in the middle tufted cells. Furthermore, responses of mitral cells to an adequate excitatory odorant were greatly inhibited by mixing the odorant with other odorants that activated neighboring glomeruli. In contrast, odorants that activated neighboring glomeruli did not significantly inhibit the responses of middle tufted cells to the adequate excitatory odorant. These results indicate a clear difference between mitral and middle tufted cells in the manner of decoding the glomerular odor maps.
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Shirley, S. G., E. H. Polak, D. A. Edwards, M. A. Wood, and G. H. Dodd. "The effect of concanavalin A on the rat electro-olfactogram at various odorant concentrations." Biochemical Journal 245, no. 1 (July 1, 1987): 185–89. http://dx.doi.org/10.1042/bj2450185.
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We have studied the effect of concanavalin A (Con A) on the rat electro-olfactogram response to several odorants. Each odorant was applied over a range of concentrations. For hydrophobic odorants whose response was affected by Con A, the diminution in response was maximal at odorant concentrations of about 1 microM in the olfactory mucus. The (odour) concentration-dependence of the change is compatible with the idea that Con A inactivates one or more types of olfactory receptor that normally bind odorants with dissociation constants of the order of 100 nM. With hydrophilic odorants we had to apply concentrations very much higher than this to elicit any response from the system. At these high concentrations we could observe Con A-induced diminutions in response.
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Kanyoma, Isna R., Oksil Venriza, and Kushariyadi Kushariyadi. "Optimalisasi Penambahan Odorant pada Gas Mengunakan Metode Time Series di PT. XYZ." Lembaran publikasi minyak dan gas bumi 57, no. 2 (August 1, 2023): 43–53. http://dx.doi.org/10.29017/lpmgb.57.2.1584.
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Gas alam merupakan sumber energi yang dihasilkan dari fosil tanaman, hewan dan mikroorganisme, bahan bakar tidak berwarna, tidak berodor dan tidak beracun. Odorant merupakan zat kimia yang di tambahkan ke gas alam untuk memberikan bau yang kuat dan khas, tetapi penambahannya masih belum teroptimalkan. Syarat odorant yang digunakan harus memiliki spesifikasi gas alam yang berodor. Dimana aturan pemakaian odorant yang benar pada PT. XYZ sebesar 3 mg/m3, tetapi odorant PT ini memakai odorant sebesar kira-kira 4 - 6 mg/m3 yang mana masih berdasarkan stroke atau waktu. Hasil penilitian ini dapat di optimasi efisiensi odorant pada gas dengan menggunakan metode time series. Dari perhitungan yang di dapatkan rata-rata pemakaian odorant selama 3 bulan sebesar 1,13 mg/m3 sedangkan untuk perhitungan yang di dapatkan dari rata-rata pemakaian odorant selama 3 bulan pada PT YZ sebesar 2,26206E-05 mg/m3 dari hasil kedua hasil perhitungan di atas di hitunglah nilai efisiensi odorant pada gas di dapatkan nilai efisiensi nya sebesar 0,14125 mg/m3 atau 1,41 cc yang mana berdasarkan peritungan efisiensi dari pemakaian ketetapan odoran tersebut untuk pemakaian nilai yang efesien ialah 1,41 cc per stroke yang setara dengan 4.7%. Adapun faktor efisiensi odorant meliputi odorant yang di gunakan, konsentrasi odorant ,suhu, tekanan dan faktor lingkungan lainnya.
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Wachowiak, Matt, Lawrence B. Cohen, and Michal R. Zochowski. "Distributed and Concentration-Invariant Spatial Representations of Odorants by Receptor Neuron Input to the Turtle Olfactory Bulb." Journal of Neurophysiology 87, no. 2 (February 1, 2002): 1035–45. http://dx.doi.org/10.1152/jn.00522.2001.
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We sought to characterize how odorants are represented at the level of afferent input to the olfactory bulb of the box turtle, a terrestrial reptile that, like mammals, detects airborne odorants. Using methods developed first in zebrafish, we selectively labeled olfactory receptor neurons with Calcium Green-1 dextran and imaged odorant-evoked input to glomeruli in vivo. Odorant representations were imaged at a glomerular level of resolution over a portion of the dorsal olfactory bulb and at a regional level of resolution over the entire dorsal surface. We report two new findings. First, even at low concentrations, odorants typically elicited input to a large fraction of all imaged glomeruli. Second, while the amplitude of the odorant-evoked input to glomeruli was concentration dependent, the relative pattern of input to the bulb changed only slightly over a concentration range of up to three log units. These results suggest the hypothesis that odorant representations in the turtle involve differential levels of input to many glomeruli, and that detecting relative patterns of distributed glomerular activation may be an important strategy for encoding odor quality independent of intensity.
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Stasenko, Sergey V., Alexey N. Mikhaylov, and Victor B. Kazantsev. "Model of Neuromorphic Odorant-Recognition Network." Biomimetics 8, no. 3 (June 28, 2023): 277. http://dx.doi.org/10.3390/biomimetics8030277.
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We propose a new model for a neuromorphic olfactory analyzer based on memristive synapses. The model comprises a layer of receptive neurons that perceive various odors and a layer of “decoder” neurons that recognize these odors. It is demonstrated that connecting these layers with memristive synapses enables the training of the “decoder” layer to recognize two types of odorants of varying concentrations. In the absence of such synapses, the layer of “decoder” neurons does not exhibit specificity in recognizing odorants. The recognition of the ’odorant’ occurs through the neural activity of a group of decoder neurons that have acquired specificity for the odorant in the learning process. The proposed phenomenological model showcases the potential use of a memristive synapse in practical odorant recognition applications.
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Youngentob, S. L., P. F. Kent, P. R. Sheehe, J. E. Schwob, and E. Tzoumaka. "Mucosal inherent activity patterns in the rat: evidence from voltage-sensitive dyes." Journal of Neurophysiology 73, no. 1 (January 1, 1995): 387–98. http://dx.doi.org/10.1152/jn.1995.73.1.387.
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1. Fluorescence changes in the dye di-4-ANEPPS were monitored on the rat's nasal septum and medial surface of the turbinates in response to odorant stimuli. For each mucosal surface a 6.0 x 6.0-mm area was sampled at 100 contiguous sites with a 10 x 10 photodiode array. The odorants were propyl acetate, 2-propanol, citral, L-carvone and ethylacetoacetate, each presented at a low and high concentration. 2. Like previous work using optical recording techniques and potential-sensitive dyes on the amphibian epithelium, the fluorescence signals elicited by odorant stimuli in the rat preparation were nearly identical in shape, time course, and response characteristics as the electroolfactogram (EOG). As with the EOG, a response could only be recorded in the presence of odorant stimuli (that is, no response was detected when nonodorized, humidified air was presented as the stimulus); the amplitude depended on odorant concentration, and the response was abolished both by ether and Triton X-100. 3. Although the entire expanse of each sampled tissue (i.e., septum and medial surface of the turbinates) responded to stimulation with each odorant, each stimulus induced a distinct spatial pattern of activity that was independent of odorant concentration and consistent from animal to animal. Furthermore, the spatial activity patterns recorded for the septum were mirror images of those recorded from the medial surface of the turbinates. 4. Formal statistical analysis of the loci of maximal activity or "hot spot" indicated highly significant effects of the odorants for both the septum and medial surface of the turbinates. 5. The results of these studies give further support to the hypothesis that odorant quality is encoded by differential spatial activity patterns in the olfactory epithelium that are characteristic of different odorants.
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Zelano, C., J. Montag, B. Johnson, R. Khan, and N. Sobel. "Dissociated Representations of Irritation and Valence in Human Primary Olfactory Cortex." Journal of Neurophysiology 97, no. 3 (March 2007): 1969–76. http://dx.doi.org/10.1152/jn.01122.2006.
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Irritation and negative valence are closely associated in perception. However, these perceptual aspects can be dissociated in olfaction where irritation can accompany both pleasant and unpleasant odorants. Whereas the sensation of odor reflects transduction at olfactory receptors, irritation reflects concurrent transduction of the odorant at trigeminal receptors. Thus a stimulus can be either a pure olfactant activating the olfactory receptors only or a bimodal odorant activating both types of receptors. Using event-related functional magnetic resonance imaging and a 2 × 2 experimental design contrasting odorant valence (pleasant/unpleasant) and odorant type (pure olfactant/bimodal) we found activity in piriform cortex to be associated with valence, and not type, of odors. In contrast, activity in the olfactory tubercle was associated with type, and not valence, of odors. Importantly, this was found when perceived intensity was held equal across odorants. These findings suggest that dissociable neural substrates subserve the encoding of irritation and valence in olfaction.
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Lodovichi, Claudia, and Leonardo Belluscio. "Odorant Receptors in the Formation of the Olfactory Bulb Circuitry." Physiology 27, no. 4 (August 2012): 200–212. http://dx.doi.org/10.1152/physiol.00015.2012.
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In mammals, smell is mediated by odorant receptors expressed by sensory neurons in the nose. These specialized receptors are found both on olfactory sensory neurons' cilia and axon terminals. Although the primary function of ciliary odorant receptors is to detect odorants, their axonal role remains unclear but is thought to involve axon guidance. This review discusses findings that show axonal odorant receptors are indeed functional and capable of modulating neural connectivity.
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Kim, Soyoun, Benjamin H. Singer, and Michal Zochowski. "Changing Roles for Temporal Representation of Odorant During the Oscillatory Response of the Olfactory Bulb." Neural Computation 18, no. 4 (April 1, 2006): 794–816. http://dx.doi.org/10.1162/neco.2006.18.4.794.
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It has been hypothesized that the brain uses combinatorial as well as temporal coding strategies to represent stimulus properties. The mechanisms and properties of the temporal coding remain undetermined, although it has been postulated that oscillations can mediate formation of this type of code. Here we use a generic model of the vertebrate olfactory bulb to explore the possible role of oscillatory behavior in temporal coding. We show that three mechanisms—synaptic inhibition, slow self-inhibition and input properties—mediate formation of a temporal sequence of simultaneous activations of glomerular modules associated with specific odorants within the oscillatory response. The sequence formed depends on the relative properties of odorant features and thus may mediate discrimination of odorants activating overlapping sets of glomeruli. We suggest that period-doubling transitions may be driven through excitatory feedback from a portion of the olfactory network acting as a coincidence modulator. Furthermore, we hypothesize that the period-doubling transition transforms the temporal code from a roster of odorant components to a signal of odorant identity and facilitates discrimination of individual odorants within mixtures.
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Zernecke, R., B. Vollmer, J. Albrecht, A. M. Kleemann, K. Haegler, J. Linn, G. Fesl, H. Bruckmann, and M. Wiesmann. "Comparison of two different odorants in an olfactory detection threshold test of the Sniffin’ Sticks." Rhinology journal 48, no. 3 (September 1, 2010): 368–73. http://dx.doi.org/10.4193/rhino09.212.
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The olfactory test battery Sniffin’ Sticks is a test of nasal chemosensory function that is based on pen-like devices for odour presentation. It consists of three olfactory subtests: threshold, discrimination, and identification. The detection threshold can be measured using two different odorants--n-butanol or PEA (phenylethyl alcohol). Both tasks are commonly applied in published studies, but little is known about the formal comparison of values obtained using them. Unlike the Sniffin’ Sticks with n-butanol as odorant, there is poor validation for the threshold subtest with the odorant PEA. The purpose of this study was to compare these two different odorants. Both odorants were applied to 100 normosmic, healthy subjects (50 females). The experiment was divided into two sessions performed on two different days. After each threshold test the discrimination and identification subtests were conducted. We obtained significant differences in detection thresholds of PEA and n-butanol. The mean score of PEA threshold and PEA TDI (sum of threshold, discrimination, identification) was significantly higher compared to n-butanol. No significant correlation between individual PEA and n-butanol thresholds was observed. The differences between both odorants indicate that a formal validation of the Sniffin’ Sticks with PEA as odorant for probing olfactory thresholds may be required.
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Quintana, Pamela, Kévin Nolet, Oliver Baus, and Stéphane Bouchard. "The Effect of Exposure to Fear-Related Body Odorants on Anxiety and Interpersonal Trust Toward a Virtual Character." Chemical Senses 44, no. 9 (September 5, 2019): 683–92. http://dx.doi.org/10.1093/chemse/bjz063.
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Abstract A growing body of literature documents how exposure to another person's fear-related body odorants can increase one's own anxiety and interfere with processing of social information, such as facial expression and impression formation. Building on these results, we aimed to 1) test the hypothesis that exposure to fear-related odorant would affect impression formation through fear contagion and 2) verify whether these effects can be observed in an ecologically valid (i.e., virtual) environment. We proposed that exposure to fear-related odorant would cause receivers to feel more anxious, which in turn would lead them to report less trust toward an unknown virtual character. This study had 2 distinct phases. First, we collected perspiration odorants from the armpits of 12 male senders (i.e., the source of the odorant) during the viewing of either fear or joy inducing film clips. In the second phase, 53 women receivers were exposed to either a fear, joy, or neutral odorant (i.e., between-subjects design) by breathing through a gauze attached to a disposable respirator mask while immersed in a virtual bar. As expected, receivers exposed to fear odorants felt significantly more stressed. Mediation analysis also revealed an indirect effect of exposure on trust through anxiety. More specifically, the more anxious the receiver felt, the less she trusted the virtual character. Our results show for the first time that the impact of exposure to fear-related body odorants on negative interpersonal impression formation is mediated by the anxiety induced in the receiver.
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SMITH, BRIAN H. "The Olfactory Memory of the Honeybee Apis Mellifera: I. Odorant Modulation of Short- and Intermediate-Term Memory After Single-Trial Conditioning." Journal of Experimental Biology 161, no. 1 (November 1, 1991): 367–82. http://dx.doi.org/10.1242/jeb.161.1.367.
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In the first 15 min after a single learning trial the olfactory memory of the honeybee, Apis mellifera, proceeds through different processing phases during which time the memory is differentially sensitive to a cooling treatment that causes amnesia. During learning about floral odours in a natural situation, several decisions would normally be made about floral choice within that period. In order to study these phenomena in more detail, single-trial proboscis extension conditioning to different odorants was used. Several stimulus-specific effects on memory consolidation in the honeybee are shown. From previous experiments it was predicted that certain odorants would be more salient conditioning stimuli. This result is confirmed. Second, generalization from the conditioned odorant to a different odorant depends on the conditioned odorant and the time postconditioning. In some combinations, responses to a novel odorant are significantly stronger than responses to the conditioning odorant after memory consolidation. These data indicate that memory recall in the honeybee, as it is evidenced by proboscis extension, is sensitive to several aspects of stimulus identity and presentation. The acquisition and recall processes are therefore much more dynamic processes than realized previously.
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Mori, K. "Grouping of odorant receptors: odour maps in the mammalian olfactory bulb." Biochemical Society Transactions 31, no. 1 (February 1, 2003): 134–36. http://dx.doi.org/10.1042/bst0310134.
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The olfactory system is unique in that the sensory input is in the form of molecular information carried in a vast variety of odorants. Nearly 1000 types of odorant receptors mediate the initial detection and discrimination of odorants at the molecular-feature level. The discrimination at the molecular level is converted into that at the cellular level (olfactory sensory neurons) by the one sensory neuron–one odorant receptor rule, and then into that at the neuronal circuit level in the olfactory bulb by the specific olfactory axon connectivity pattern. Individual glomeruli in the olfactory bulb represent a single odorant receptor, and the glomerular sheet at the olfactory bulb surface forms odorant receptor maps. This review focuses on the spatial organization of the glomerular sensory map in the olfactory bulb. The analysis using the optical imaging method suggests that odorant receptors having a common molecular-feature receptive site are grouped together and represented by glomeruli that are localized in topographically fixed domains in the olfactory bulb. The domain organization may be a structural unit for the spatial organization of the glomerular sensory map, and might relate to the olfactory submodality.
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Nakamura, Tadashi, Yoshihiro Noumi, Hiroyuki Yamakawa, Atsushi Nakamura, Durige Wen, Xing Li, Xiong Geng, Ken Sawada, and Tatsuo Iwasa. "Enhancement of the Olfactory Response by Lipocalin Cp-Lip1 in Newt Olfactory Receptor Cells: An Electrophysiological Study." Chemical Senses 44, no. 7 (July 26, 2019): 523–33. http://dx.doi.org/10.1093/chemse/bjz048.
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Abstract Previously, we have detected the expression of 2 lipocalin genes (lp1 and lp2) in the olfactory epithelium of the Japanese newt Cynops pyrrhogaster. Recombinant proteins of these genes (Cp-Lip1 and Cp-Lip2, respectively) exhibited high affinities to various odorants, suggesting that they work like the odorant-binding proteins (OBPs). However, the physiological functions of OBP generally remain inconclusive. Here, we examined the effect of Cp-Lip1 on the electrophysiological responses of newt olfactory receptor cells. We observed that the electro-olfactogram induced by the vapor of an odorant with high affinity to Cp-Lip1 appeared to increase in amplitude when a tiny drop of Cp-Lip1 solution was dispersed over the olfactory epithelium. However, the analysis was difficult because of possible interference by intrinsic components in the nasal mucus. We subsequently adopted a mucus-free condition by using suction electrode recordings from isolated olfactory cells, in which impulses were generated by puffs of odorant solution. When various concentration (0–5 µM) of Cp-Lip1 was mixed with the stimulus solution of odorants highly affinitive to Cp-Lip1, the impulse frequency increased in a concentration-dependent manner. The increase by Cp-Lip1 was seen more evidently at lower concentration ranges of stimulus odorants. These results strongly suggest that Cp-Lip1 broadens the sensitivity of the olfactory cells toward the lower concentration of odorants, by which animals can detect very low concentration of odorants.
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Igarashi, Kei M., and Kensaku Mori. "Spatial Representation of Hydrocarbon Odorants in the Ventrolateral Zones of the Rat Olfactory Bulb." Journal of Neurophysiology 93, no. 2 (February 2005): 1007–19. http://dx.doi.org/10.1152/jn.00873.2004.
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The glomerular sheet of the olfactory bulb (OB) forms odorant receptor maps that are parceled into zones. We previously reported the molecular receptive range (MRR) property of individual glomeruli in the dorsal zone (zone 1) of the OB and showed that polar functional groups play a major role in activating glomeruli in this zone. However, the MRR property of glomeruli in zones 2–4 is not well understood yet. Using the method of intrinsic signal imaging, we recorded odorant-induced glomerular activity from the ventrolateral surface (zones 2–4) of rat OB. While hydrocarbon odorants that lack polar functional groups activate only a few glomeruli in zone 1, we found that a series of hydrocarbon odorants consistently activated many glomeruli in the ventrolateral surface. The hydrocarbon-responsive glomeruli were grouped into two clusters; glomeruli in one cluster (cluster H) responded to benzene-family hydrocarbons but not to cyclic terpene hydrocarbons. Glomeruli in the other cluster (cluster I) responded to both classes of hydrocarbons. Detailed analyses of MRR properties of individual glomeruli using hydrocarbon odorants and polar-functional-group-containing odorants showed that the common and characteristic molecular features effective in activating glomeruli in the clusters H and I are the hydrocarbon skeleton. These results suggest that ORs represented by glomeruli in these clusters recognize primarily the hydrocarbon skeleton of odorants, and thus imply a systematic difference in the manner of recognizing odorant molecular features between ORs in zone 1 and ORs in zones 2–4.
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Williams, Ellie, and Adam Dewan. "Olfactory Detection Thresholds for Primary Aliphatic Alcohols in Mice." Chemical Senses 45, no. 7 (July 1, 2020): 513–21. http://dx.doi.org/10.1093/chemse/bjaa045.
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Abstract Probing the neural mechanisms that underlie each sensory system requires the presentation of perceptually appropriate stimulus concentrations. This is particularly relevant in the olfactory system as additional odorant receptors typically respond with increasing stimulus concentrations. Thus, perceptual measures of olfactory sensitivity provide an important guide for functional experiments. This study focuses on aliphatic alcohols because they are commonly used to survey neural activity in a variety of olfactory regions, probe the behavioral limits of odor discrimination, and assess odor-structure activity relationships in mice. However, despite their frequent use, a systematic study of the relative sensitivity of these odorants in mice is not available. Thus, we assayed the ability of C57BL/6J mice to detect a homologous series of primary aliphatic alcohols (1-propanol to 1-heptanol) using a head-fixed Go/No-Go operant conditioning assay combined with highly reproducible stimulus delivery. To aid in the accessibility of our data, we report the animal’s threshold to each odorant according to the 1) ideal gas condition, 2) nonideal gas condition (factoring in the activity of the odorant in the solvent), and 3) the liquid dilution of the odorant in the olfactometer. Of the odorants tested, mice were most sensitive to 1-hexanol and least sensitive to 1-butanol. These updated measures of murine sensitivity will hopefully guide experimenters in choosing appropriate stimulus concentrations for experiments using these odorants.
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Ukhanov, Kirill, Elizabeth A. Corey, Daniela Brunert, Katharina Klasen, and Barry W. Ache. "Inhibitory Odorant Signaling in Mammalian Olfactory Receptor Neurons." Journal of Neurophysiology 103, no. 2 (February 2010): 1114–22. http://dx.doi.org/10.1152/jn.00980.2009.
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Odorants inhibit as well as excite olfactory receptor neurons (ORNs) in many species of animals. Cyclic nucleotide-dependent activation of canonical mammalian ORNs is well established but it is still unclear how odorants inhibit these cells. Here we further implicate phosphoinositide-3-kinase (PI3K), an indispensable element of PI signaling in many cellular processes, in olfactory transduction in rodent ORNs. We show that odorants rapidly and transiently activate PI3K in the olfactory cilia and in the olfactory epithelium in vitro. We implicate known G-protein–coupled isoforms of PI3K and show that they modulate not only the magnitude but also the onset kinetics of the electrophysiological response of ORNs to complex odorants. Finally, we show that the ability of a single odorant to inhibit another can be PI3K dependent. Our collective results provide compelling support for the idea that PI3K-dependent signaling mediates inhibitory odorant input to mammalian ORNs and at least in part contributes to the mixture suppression typically seen in the response of ORNs to complex natural odorants.
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Yang, Xufei, Yaowapa Lorjaroenphon, Hong Li, Keith R. Cadwallader, Xinlei Wang, and Yuanhui Zhang. "Quantification of Odorants in Animal Feeds at Commercial Swine and Poultry Operations." Transactions of the ASABE 61, no. 2 (2018): 693–98. http://dx.doi.org/10.13031/trans.12611.
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Abstract. Odorants in animal feeds may come from various processes, such as fermentation and decay of feed ingredients, contamination by fecal materials, and sorption of volatiles in the air of animal houses. Those odorants may affect feed flavor and may serve as indicators of feed quality. The objective of this study was to examine the composition and concentration of odorants in animal feeds and to explore the variability of those odorants with animal operation type and season. Thirty-seven feed samples were collected from 14 swine and poultry operations in the U.S. Midwest and were submitted for gas chromatography-mass spectrometry (GC-MS) analysis. A total of 55 organic odorants were quantitated, including fatty acids, alcohols, aldehydes, ketones, phenols, and nitrogen-containing compounds. Those compounds together accounted for 0.46% ±0.20% of fresh feed mass, with the highest percentage (0.54% ±0.19%) found at layer hen houses and the lowest percentage (0.38% ±0.14%) at swine farrowing houses. Acetic acid and ethanol were most abundant, accounting for 0.22% ±0.13% and 0.13% ±0.07% of fresh feed mass, respectively. Fecal indicators, including indole and skatole, were <5 ppm by mass. Principal component analysis (PCA) revealed that the variability in odorant composition was largely ascribed to two loading factors that were dominated by acetic acid and ethanol, respectively. The odorant composition of feed samples showed no significant effect by animal operation type, while a gradual seasonal change was noted. This study is expected to improve the understanding of the causes of odorants in animal feeds and their implications for animal health and production performance. Keywords: Animal feed, Animal operation, GC-MS, Odorant, Principal component analysis.
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Peterlin, Zita, Stuart Firestein, and Matthew E. Rogers. "The state of the art of odorant receptor deorphanization: A report from the orphanage." Journal of General Physiology 143, no. 5 (April 14, 2014): 527–42. http://dx.doi.org/10.1085/jgp.201311151.
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The odorant receptors (ORs) provide our main gateway to sensing the world of volatile chemicals. This involves a complex encoding process in which multiple ORs, each of which detects its own set of odorants, work as an ensemble to produce a distributed activation code that is presumably unique to each odorant. One marked challenge to decoding the olfactory code is OR deorphanization, the identification of a set of activating odorants for a particular receptor. Here, we survey various methods used to try to express defined ORs of interest. We also suggest strategies for selecting odorants for test panels to evaluate the functional expression of an OR. Integrating these tools, while retaining awareness of their idiosyncratic limitations, can provide a multi-tiered approach to OR deorphanization, spanning the initial discovery of a ligand to vetting that ligand in a physiologically relevant setting.
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Emani, Lakshmareddy, Suryachandrarao Ravada, Bharani Meka, Machiraju Garaga, and Trimurtulu Golakoti. "A New Flavanone from the Leaves of Chromolaena odorata." Natural Product Communications 10, no. 9 (September 2015): 1934578X1501000. http://dx.doi.org/10.1177/1934578x1501000918.
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Chromolaena odorata (Syn: Eupatorium odoratum) is a perennial plant belonging to the Asteraceae family. Extracts of C. odorata have shown strong anti-oxidant and moderate anti-adipogenenesis activities. Detailed phytochemical investigation of C. odorata led to the isolation of 21 secondary metabolites, which include a new flavanone (3), and a chalcone, 3,2′-dihydroxy-4,4′,5′,6′-tetramethoxychalcone (2), reported for the first time from a natural source, besides three known compounds 1, 4 and 5, all of which are reported for the first time from C. odorata. Some of these compounds exhibited potent anti-oxidant and anti-adipogenesis activities and these may be partly responsible for the activity of the extract.
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Takeuchi, Hiroko, and Takashi Kurahashi. "Identification of Second Messenger Mediating Signal Transduction in the Olfactory Receptor Cell." Journal of General Physiology 122, no. 5 (October 27, 2003): 557–67. http://dx.doi.org/10.1085/jgp.200308911.
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One of the biggest controversial issues in the research of olfaction has been the mechanism underlying response generation to odorants that have been shown to fail to produce cAMP when tested by biochemical assays with olfactory ciliary preparations. Such observations are actually the original source proposing a possibility for the presence of multiple and parallel transduction pathways. In this study the activity of transduction channels in the olfactory cilia was recorded in cells that retained their abilities of responding to odorants that have been reported to produce InsP3 (instead of producing cAMP, and therefore tentatively termed “InsP3 odorants”). At the same time, the cytoplasmic cNMP concentration ([cNMP]i) was manipulated through the photolysis of caged compounds to examine their real-time interactions with odorant responses. Properties of responses induced by both InsP3 odorants and cytoplasmic cNMP resembled each other in their unique characteristics. Reversal potentials of currents were 2 mV for InsP3 odorant responses and 3 mV for responses induced by cNMP. Current and voltage (I-V) relations showed slight outward rectification. Both responses showed voltage-dependent adaptation when examined with double pulse protocols. When brief pulses of the InsP3 odorant and cytoplasmic cNMP were applied alternatively, responses expressed cross-adaptation with each other. Furthermore, both responses were additive in a manner as predicted quantitatively by the theory that signal transduction is mediated by the increase in cytoplasmic cAMP. With InsP3 odorants, actually, remarkable responses could be detected in a small fraction of cells (∼2%), explaining the observation for a small production of cAMP in ciliary preparations obtained from the entire epithelium. The data will provide evidence showing that olfactory response generation and adaptation are regulated by a uniform mechanism for a wide variety of odorants.
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Hirata, Yusuke, Yuya Morimoto, Eunryel Nam, and Shoji Takeuchi. "Portable biohybrid odorant sensors using cell-laden collagen micropillars." Lab on a Chip 19, no. 11 (2019): 1971–76. http://dx.doi.org/10.1039/c9lc00131j.
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Reisert, Johannes. "Origin of basal activity in mammalian olfactory receptor neurons." Journal of General Physiology 136, no. 5 (October 25, 2010): 529–40. http://dx.doi.org/10.1085/jgp.201010528.
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Mammalian odorant receptors form a large, diverse group of G protein–coupled receptors that determine the sensitivity and response profile of olfactory receptor neurons. But little is known if odorant receptors control basal and also stimulus-induced cellular properties of olfactory receptor neurons other than ligand specificity. This study demonstrates that different odorant receptors have varying degrees of basal activity, which drives concomitant receptor current fluctuations and basal action potential firing. This basal activity can be suppressed by odorants functioning as inverse agonists. Furthermore, odorant-stimulated olfactory receptor neurons expressing different odorant receptors can have strikingly different response patterns in the later phases of prolonged stimulation. Thus, the influence of odorant receptor choice on response characteristics is much more complex than previously thought, which has important consequences on odor coding and odor information transfer to the brain.
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Hosler, J. S., and B. H. Smith. "Blocking and the detection of odor components in blends." Journal of Experimental Biology 203, no. 18 (September 15, 2000): 2797–806. http://dx.doi.org/10.1242/jeb.203.18.2797.
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Recent studies of olfactory blocking have revealed that binary odorant mixtures are not always processed as though they give rise to mixture-unique configural properties. When animals are conditioned to one odorant (A) and then conditioned to a mixture of that odorant with a second (X), the ability to learn or express the association of X with reinforcement appears to be reduced relative to animals that were not preconditioned to A. A recent model of odor-based response patterns in the insect antennal lobe predicts that the strength of the blocking effect will be related to the perceptual similarity between the two odorants, i.e. greater similarity should increase the blocking effect. Here, we test that model in the honeybee Apis mellifera by first establishing a generalization matrix for three odorants and then testing for blocking between all possible combinations of them. We confirm earlier findings demonstrating the occurrence of the blocking effect in olfactory learning of compound stimuli. We show that the occurrence and the strength of the blocking effect depend on the odorants used in the experiment. In addition, we find very good agreement between our results and the model, and less agreement between our results and an alternative model recently proposed to explain the effect.
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Takahashi, Yuji K., Masahide Kurosaki, Shuichi Hirono, and Kensaku Mori. "Topographic Representation of Odorant Molecular Features in the Rat Olfactory Bulb." Journal of Neurophysiology 92, no. 4 (October 2004): 2413–27. http://dx.doi.org/10.1152/jn.00236.2004.
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Individual glomeruli in the mammalian olfactory bulb (OB) most probably represent a single odorant receptor (OR). The assembly of glomeruli thus forms the maps of ORs. How is the approximately 1,000 ORs represented spatially in the glomerular map? Using the method of optical imaging of intrinsic signals and systematic panels of stimulus odorants, we recorded odorant-induced glomerular activity from the dorsal and dorsolateral areas of the rat OB, and examined the molecular receptive range (MRR) of individual glomeruli. We then deduced the characteristic molecular features that were shared by odorants effective in activating individual glomeruli. Analysis of the spatial representation of the MRR showed that glomeruli with similar MRRs gathered in close proximity and formed molecular feature clusters and subclusters. Although the shape of the clusters varied among different OBs, the clusters were arranged at stereotypical positions in relation to the zonal organization of the OB. Examination of the spatial representation of the characteristic molecular features of odorants using structurally semirigid aromatic compounds suggest a systematic and gradual change in the characteristic molecular features according to the position of subclusters in the map. The topographic map of the characteristic molecular features may reflect a systematic spatial representation of the ORs and may participate in the neural bases for the odorant structure–odor quality relationship.
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Kent, P. F., S. L. Youngentob, and P. R. Sheehe. "Odorant-specific spatial patterns in mucosal activity predict perceptual differences among odorants." Journal of Neurophysiology 74, no. 4 (October 1, 1995): 1777–81. http://dx.doi.org/10.1152/jn.1995.74.4.1777.
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1. Using operant techniques, rats were trained to differentially report (i.e., identify) the odorants propanol, carvone, citral, propyl acetate, and ethylacetoacetate. After acquisition training, the animals were tested using a 5 x 5 confusion matrix design. The results of the behavioral tests were used to measure the degree of perceptual dissimilarity between any pair of odorants. These dissimilarity measures were then subjected to multidimensional scaling analysis to establish a two-dimensional perceptual odor space for each rat. 2. At the completion of behavioral testing, the fluorescence changes in the dye di-4-ANEPPS were monitored on the rat's nasal septum and medial surface of the turbinates in response to the same odorants. For each mucosal surface a 6.0 x 6.0 mm area was sampled at 100 contiguous sites with a 10 x 10 photodiode array. 3. Formal statistical analysis indicated a highly significant predictive relationship between the relative position of an odorant's mucosal loci of maximal activity or “hot spot” and the relative position of the same odorant in a psychophysically determined perceptual odor space (F = 15.6, P < 0.001). 4. The results of this study suggest for the first time that odorant-induced mucosal activity patterns serve as the substrate for the perception of odorant quality.
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Schuckel, Julia, Päivi H. Torkkeli, and Andrew S. French. "Two Interacting Olfactory Transduction Mechanisms Have Linked Polarities and Dynamics in Drosophila melanogaster Antennal Basiconic Sensilla Neurons." Journal of Neurophysiology 102, no. 1 (July 2009): 214–23. http://dx.doi.org/10.1152/jn.00162.2009.
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We measured frequency response functions between concentrations of fruit odorants and individual action potentials in large basiconic sensilla of the Drosophila melanogaster antenna. A new method of randomly varying odorant concentration was combined with rapid, continuous measurement of concentration at the antenna by a miniature photoionization detector. All frequency responses decreased progressively at frequencies approaching 100 Hz, providing an upper limit for the dynamics of Drosophila olfaction. We found two distinct response patterns: excitatory band-pass frequency responses were seen with ethyl acetate, ethyl butyrate, and hexanol, whereas inhibitory low-pass responses were seen with methyl salicylate and phenylethyl acetate. Band-pass responses peaked at 1–10 Hz. Frequency responses could be well fitted by simple linear filter equations, and the fitted parameters were consistent within each of the two types of responses. Experiments with equal mixtures of excitatory and inhibitory odorants gave responses that were characteristic of the inhibitory components, indicating that interaction during transduction causes inhibitory odorants to suppress the responses to excitatory odorants. Plots of response amplitude versus odorant concentration indicated that the odorant concentrations used were within approximately linear regions of the dose response relationships. We also estimated linear information capacity from the coherence function of each recording. Although coherence was relatively high, indicating a large signal-to-noise ratio, information capacity for olfaction was much lower than comparable estimates for mechanotransduction or visual transduction because of the limited bandwidth of olfaction. These data offer new insights into transduction by primary chemoreceptors and place temporal constraints on Drosophila olfactory behavior.
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Ko, Hwi Jin, and Tai Hyun Park. "Dual signal transduction mediated by a single type of olfactory receptor expressed in a heterologous system." Biological Chemistry 387, no. 1 (January 1, 2006): 59–68. http://dx.doi.org/10.1515/bc.2006.009.
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Abstract Controversy exists over the relationship between the cAMP and IP3 pathways in vertebrate olfactory signal transduction, as this process is known to occur by either of the two pathways. Recent studies have shown that a single olfactory neuron responds to both cAMP- and IP3-producing odorants, suggesting the existence of an olfactory receptor protein that can recognize both ligands. In this study we found that the rat olfactory receptor I7, stably expressed in HEK-293 cells, triggers the cAMP pathway upon stimulation by a specific odorant (octanal) at concentrations lower than 10-4 M; however, the receptor triggers both pathways at higher concentrations. This indicates that a single olfactory receptor, stimulated by a single pathway-inducing odorant, can evoke both pathways at high odorant concentrations. Using this heterologous system, both the dose-dependent response and receptor I7 specificity were analyzed. The dose-dependent Ca2+ response curve, which also includes the release of Ca2+ ions from internal stores at high odorant concentrations, was not monotonous, but had a local maximum and minimum with 10-10 and 10-7 M octanal, respectively, and reached a plateau at 10-2 M octanal. The specificity of the I7 receptor was lower when exposed to higher concentrations of odorants.
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Shirley, S. G., E. H. Polak, R. A. Mather, and G. H. Dodd. "The effect of concanavalin A on the rat electro-olfactogram. Differential inhibition of odorant response." Biochemical Journal 245, no. 1 (July 1, 1987): 175–84. http://dx.doi.org/10.1042/bj2450175.
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When the rat olfactory mucosa is treated with concanavalin A, it subsequently shows diminished sensitivity towards 60% of the 112 odorants tested (as judged by the amplitude of the electro-olfactogram response). Odorants containing four to six carbon atoms tend to show the largest (absolute) diminutions, suggesting a receptor for this kind of odorant, although the structural specificity is weak. The receptor seems to be of particular importance in the detection of thiols, carboxylic acids and hydrocarbons of the above size, since these compounds loose the highest proportion of their original signal. The concanavalin A appears to be binding to the glycan of one or more cell-surface proteins. The binding may be at, or close to, at least one odorant receptor.
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Smith, Steven A., and Richard A. Paselk. "Olfactory Sensitivity of the Turkey Vulture (Cathartes aura) to Three Carrion-associated Odorants." Auk 103, no. 3 (July 1, 1986): 586–92. http://dx.doi.org/10.1093/auk/103.3.586.
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Abstract The Turkey Vulture (Cathartes aura) is generally thought to rely on olfactory cues to locate carrion. Because vertically rising odorants are dispersed rapidly by wind turbulence, we predict that Turkey Vultures should be highly sensitive to these chemicals to detect them at foraging altitudes. Olfactory thresholds to three by-products of animal decomposition (1× 10-6 M for butanoic acid and ethanethiol, and 1× 10-5-5 M for trimethylamine) were determined from heart-rate responses. These relatively high thresholds indicate that these odorants are probably not cues for foraging Turkey Vultures. Odorant thresholds, food habits of Turkey Vultures, and the theoretical properties of odorant dispersion cast some doubt on the general importance of olfaction in food location by this species.
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Sato, T., J. Hirono, M. Tonoike, and M. Takebayashi. "Tuning specificities to aliphatic odorants in mouse olfactory receptor neurons and their local distribution." Journal of Neurophysiology 72, no. 6 (December 1, 1994): 2980–89. http://dx.doi.org/10.1152/jn.1994.72.6.2980.
Full textAbstract:
1. Odor responses to two homologous series of n-fatty acids (nFA) and n-aliphatic alcohols (nAA) with a straight chain of three to nine carbons were examined by measuring odor-induced [Ca2+]i increase in mouse olfactory receptor neurons (ORNs) isolated by the tissue-printing method. 2. One-third of the ORNs responsive to nFA and/or nAA were alternately sensitive to either type of odorant. Their sensitivities were usually near maximal for one or two odorants and decreased with differences in the carbon chain length from the tuned odorants. 3. Two-thirds of the ORNs responsive to nFA and/or nAA were sensitive to both types of odorants. Most of them were also tuned to one or two odorants in each series with similar carbon chain lengths and showed a decrease of sensitivity with increasing stereochemical discrepancy, similar to nFA/nAA discriminating ORNs. 4. In 10 of 20 non-nFA/nAA discriminating ORNs, the sensitivity to nFA was > 10 times greater than to nAA, and 80% of them were localized in a central region of olfactory epithelium on the septum wall where ORNs preferentially project to the dorsomedial or centromedial regions of the olfactory bulb. In addition, the sensitivity to three series of n-aliphatic odorants with an added amino group was examined. Sensitivity became higher as the electronegativity of the functional groups increased, suggesting that a hydrogen bond might partly mediate affinity in one type of non-nFA/nAA discriminating ORNs. 5. The diversity in odorant tuning specificity and sensitivity of the individual ORNs indicated that their receptor sites were finely tuned to the stereochemical structures of numerous odorants by changes in the three-dimensional size and intermolecular positions of the hydrophobic domains for hydrophobic bond, as well as the proton-acceptor or donor for the hydrogen bond and the electrical charge for the ionic bond. 6. The subpopulation of ORNs tuned to an individual odorant increased as the length of carbon chain of the odorant increased from three to nine. This tendency was more marked for nFA than for nAA in the case of non-nFA/nAA discriminating ORNs. 7. Data obtained by the in vitro approach using the tissue-printing method suggested that three or more subtypes of ORNs, which were similar in some cases and significantly different in other cases, were located within close proximity to one another.