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PloS One 2023Living in environments whose ecologies vary in periods as short as 24 h is a challenge for animals as Drosophila species that inhabit pear and apple orchards. These...
Living in environments whose ecologies vary in periods as short as 24 h is a challenge for animals as Drosophila species that inhabit pear and apple orchards. These orchards have sunny and shady sections. The size and shape of these habitats change daily according to the position of the sun in the sky. Sunny areas are related to dryness and water loss, and shady places have lower temperatures and higher humidity. The presence of heterospecific flies may lead to competition for space and food. In sunny habitats we did not find adult Drosophila. In shady sections we found conspecific groups D. melanogaster, D. simulans, D. immigrans, D. subobscura, and the Chilean endemic D. pavani perched on grasses and herbs at 8-10 cm from fruits that had fallen on the ground. In the fruits, 99% of the adults were females and they were not grouped. The way in which daily changes in the size and shape of shady habitats together with the presence of heterospecific adults influence the selection of places to live is poorly understood in Drosophila. Our experiments show that adults of the five species prefer dark areas. The experimental results show that the odors of each species: i) influence conspecifics to select similar perch sites and decrease mobility, and ii) increase mobility in heterospecific adults and modify their perch site preferences. Attractions between conspecifics, the repulsions between species, and preferences for shaded areas matter in choosing a place to live in the five Drosophila species. These behaviors seem to have evolved as coordinated routines, contributing to the coexistence of the five Drosophila species in the apple and pear orchards examined.
Topics: Animals; Female; Male; Drosophila; Drosophila melanogaster; Sexual Behavior, Animal; Ecosystem; Odorants
PubMed: 37440503
DOI: 10.1371/journal.pone.0278427 -
Nature Nanotechnology May 2024Biological olfactory systems are highly sensitive and selective, often outperforming engineered chemical sensors in highly complex and dynamic environments. As a result,...
Biological olfactory systems are highly sensitive and selective, often outperforming engineered chemical sensors in highly complex and dynamic environments. As a result, there is much interest in using biological systems to build sensors. However, approaches to read-out information from biological systems, especially neural signals, tend to be suboptimal due to the number of electrodes that can be used and where these can be placed. Here we aim to overcome this suboptimality in neural information read-out by using a nano-enabled neuromodulation strategy to augment insect olfaction-based chemical sensors. By harnessing the photothermal properties of nanostructures and releasing a select neuromodulator on demand, we show that the odour-evoked response from the interrogated regions of the insect olfactory system can not only be enhanced but can also improve odour identification.
Topics: Animals; Smell; Odorants; Nanotechnology; Insecta; Nanostructures; Neurotransmitter Agents
PubMed: 38272973
DOI: 10.1038/s41565-023-01592-z -
Behavioral Neuroscience Oct 2023Mental representations of stimuli that are not physically present are critical for a range of cognitive capacities, including perception, memory, and learning. Overly...
Mental representations of stimuli that are not physically present are critical for a range of cognitive capacities, including perception, memory, and learning. Overly robust mental representations, however, can contribute to hallucinations in healthy individuals and those diagnosed with psychotic illness. Measuring the strength of mental representations can thus provide insight into how the contents of the mind influence both adaptive and maladaptive behaviors. In rodents, the robustness of mental representations has been tested using the representation-mediated learning (RML) task, in which animals respond less to a cue after a stimulus that has previously been associated with this cue has been paired with illness. This suggests that the mental representation of the cue enters into a negative association during aversive learning, even though the cue is not physically present. Here, we developed a human version of the RML task in which participants initially learned associations between two visual symbols and two different appetitive food odors. Preference for the food odors was then tested immediately before and after a session in which one symbol was paired with an aversive noise. We observed that mediated learning, in the form of selective decrease in preference for the odor previously paired with the noise-predicting symbol, was directly proportional to direct aversive learning for the symbols themselves. These findings suggest that a mental representation of the odor entered into a negative association with the sound and pave the way for future studies aimed at characterizing the neural circuits of mediated learning in the human brain. (PsycInfo Database Record (c) 2023 APA, all rights reserved).
Topics: Animals; Humans; Avoidance Learning; Brain; Odorants
PubMed: 37410433
DOI: 10.1037/bne0000565 -
Current Opinion in Insect Science Oct 2023Extracting spatial information from temporal stimulus patterns is essential for sensory perception (e.g. visual motion direction detection or concurrent sound... (Review)
Review
Extracting spatial information from temporal stimulus patterns is essential for sensory perception (e.g. visual motion direction detection or concurrent sound segregation), but this process remains understudied in olfaction. Animals rely on olfaction to locate resources and dangers. In open environments, where odors are dispersed by turbulent wind, detection of wind direction seems crucial for odor source localization. However, recent studies showed that insects can extract spatial information from the odor stimulus itself, independently from sensing wind direction. This remarkable ability is achieved by detecting the fine-scale temporal pattern of odor encounters, which contains information about the location and size of an odor source, and the distance between different odor sources.
Topics: Animals; Odorants; Insecta; Smell; Wind
PubMed: 37419251
DOI: 10.1016/j.cois.2023.101082 -
International Journal of Cosmetic... Feb 2024Fragrance is added to almost all dermocosmetic emulsions, as it has been found to be a key driver in consumer choice and contributes to the perception of product... (Review)
Review
Fragrance is added to almost all dermocosmetic emulsions, as it has been found to be a key driver in consumer choice and contributes to the perception of product performance. Fragrance is a complex mixture of odorant chemicals at different concentrations. When incorporated into a formulation, the individual fragrance chemicals partition between the emulsion phases depending on their physicochemical properties, which can impact the structure, stability, texture and odour of the final product. On the other hand, it is well known in the food industry how the composition and structure of food emulsion matrices influence the release of aroma chemicals. Fragranced dermocosmetic emulsions have been studied to a lesser extent but it is interesting to apply findings from the food domain since emulsion structure, composition and aroma compounds share common features. This review aims to give an overview of the literature dealing with the interactions between fragrance and dermocosmetic emulsions. The effects of fragrance on emulsion microstructure, stability and texture are highlighted and discussed. The effects of composition and structure of emulsion on the release of fragrance molecules are also presented. Finally, the interactions between skin and fragranced emulsions are addressed.
Topics: Emulsions; Odorants; Skin
PubMed: 37622240
DOI: 10.1111/ics.12896 -
The Journal of Neuroscience : the... Nov 2023In the mammalian nose, two chemosensory systems, the trigeminal and the olfactory mediate the detection of volatile chemicals. Most odorants are able to activate the...
In the mammalian nose, two chemosensory systems, the trigeminal and the olfactory mediate the detection of volatile chemicals. Most odorants are able to activate the trigeminal system, and vice versa, most trigeminal agonists activate the olfactory system as well. Although these two systems constitute two separate sensory modalities, trigeminal activation modulates the neural representation of an odor. The mechanisms behind the modulation of olfactory response by trigeminal activation are still poorly understood. We addressed this question by looking at the olfactory epithelium (OE), where olfactory sensory neurons (OSNs) and trigeminal sensory fibers co-localize and where the olfactory signal is generated. Our study was conducted in a mouse model. Both sexes, males and females, were included. We characterize the trigeminal activation in response to five different odorants by measuring intracellular Ca changes from primary cultures of trigeminal neurons (TGNs). We also measured responses from mice lacking TRPA1 and TRPV1 channels known to mediate some trigeminal responses. Next, we tested how trigeminal activation affects the olfactory response in the olfactory epithelium using electro-olfactogram (EOG) recordings from wild-type (WT) and TRPA1/V1-knock out (KO) mice. The trigeminal modulation of the olfactory response was determined by measuring responses to the odorant, 2-phenylethanol (PEA), an odorant with little trigeminal potency after stimulation with a trigeminal agonist. Trigeminal agonists induced a decrease in the EOG response to PEA, which depended on the level of TRPA1 and TRPV1 activation induced by the trigeminal agonist. This suggests that trigeminal activation can alter odorant responses even at the earliest stage of the olfactory sensory transduction. Most odorants reaching the olfactory epithelium (OE) can simultaneously activate olfactory and trigeminal systems. Although these two systems constitute two separate sensory modalities, trigeminal activation can alter odor perception. Here, we analyzed the trigeminal activity induced by different odorants proposing an objective quantification of their trigeminal potency independent from human perception. We show that trigeminal activation by odorants reduces the olfactory response in the olfactory epithelium and that such modulation correlates with the trigeminal potency of the trigeminal agonist. These results show that the trigeminal system impacts the olfactory response from its earliest stage.
Topics: Male; Humans; Female; Mice; Animals; Smell; Olfactory Receptor Neurons; Olfactory Mucosa; Odorants; Mice, Knockout; Phenylethyl Alcohol; Mammals
PubMed: 37813571
DOI: 10.1523/JNEUROSCI.0489-23.2023 -
Food Chemistry Nov 20234-Methylphenol is a food-related odor-active volatile with a high recognition factor, due to its horse stable-like, fecal odor quality. Its ambivalent hedonic impact as...
4-Methylphenol is a food-related odor-active volatile with a high recognition factor, due to its horse stable-like, fecal odor quality. Its ambivalent hedonic impact as key aroma compound, malodor, and semiochemical has spurred the search for its cognate, chemosensory odorant receptors across species. A human odorant receptor for the highly characteristic 4-methylphenol has been elusive. Here, we identified and characterized human receptor OR9Q2 to be tuned to purified 4-methylphenol, but not to its contaminant isomer 3-methylphenol. This highly selective function of OR9Q2 complements an exclusive phenol detection gap in the ancient, most broadly tuned human odorant receptor OR2W1. Moreover, a 4-methylphenol function is evolutionary conserved in phylogenetically related OR9Q2 orthologs from chimpanzee, mouse, and cow. Notably, the cow receptor outperformed human OR9Q2 10-fold in signal strength, consonant with previous reports of 4-methylphenol as a bovine pheromone. Our results suggest OR9Q2 as best sensor for the key food odorant, malodor, and semiochemical 4-methylphenol.
Topics: Female; Animals; Cattle; Humans; Mice; Horses; Odorants; Receptors, Odorant; Phenols; Pheromones
PubMed: 37295052
DOI: 10.1016/j.foodchem.2023.136492 -
PloS One 2023Organic volatiles produced by fruits can result in overestimation of sweetness by humans, but it is unknown if a comparable phenomenon occurs in other species. Honey...
Organic volatiles produced by fruits can result in overestimation of sweetness by humans, but it is unknown if a comparable phenomenon occurs in other species. Honey bees collect nectar of varying sweetness at different flowering plants. Bees discriminate sugar concentration and generally prefer higher concentrations; they encounter floral volatiles as they collect nectar, suggesting that they, like humans, could be susceptible to sweetness enhancement by odorant. In this study, limonene, linalool, geraniol, and 6-methyl-5-hepten-2-ol were tested for their ability to alter behaviors related to perception of sweetness by honey bees. Honey bees were tested in the laboratory using proboscis extension response-based assays and in the field using feeder-based assays. In the laboratory assays, 6-methyl-5-hepten-2-ol and geraniol, but neither linalool nor limonene, significantly increased responses to low concentrations of sucrose compared with no odorant conditions in 15-day and 25-day-old adult worker honey bees, but not in 35-day-old bees. Limonene reduced responding in 15-day-old bees, but not in the older bees. There was no odorant-based difference in performance in field assays comparing geraniol and limonene with a no odorant control. The interaction of the tested plant volatiles with sucrose concentration revealed in laboratory testing is therefore unlikely to be a major determinant of nectar choice by honey bees foraging under natural conditions. Because geraniol is a component of honey bee Nasonov gland pheromone as well as a floral volatile, its impact on responses in the laboratory may reflect conveyance of different information than the other odorants tested.
Topics: Humans; Bees; Animals; Plant Nectar; Odorants; Limonene; Sucrose; Perception
PubMed: 38150461
DOI: 10.1371/journal.pone.0290129 -
STAR Protocols Dec 2023Perceptual measures of odor threshold provide a mechanism to compare sensitivity across species and to gauge stimulus concentrations for functional experiments. Here, we...
Perceptual measures of odor threshold provide a mechanism to compare sensitivity across species and to gauge stimulus concentrations for functional experiments. Here, we present a protocol to precisely quantify the odor detection threshold of mice. We describe the construction of a head-fixed operant conditioning behavioral rig and provide details of the training and testing procedures. This approach can be used to compare the sensitivity of mice across odorants and to quantify detection differences associated with genetic mutations or pharmacological manipulations. For complete details on the use and execution of this protocol, please refer to Johnson et al. (2023), Jennings et al. (2022), Williams and Dewan (2020), and Dewan et al. (2018)..
Topics: Animals; Mice; Odorants; Smell; Conditioning, Operant
PubMed: 37805920
DOI: 10.1016/j.xpro.2023.102635 -
Journal of Agricultural and Food... May 2024Gas chromatography-olfactometry (GC-O) has made significant advancements in recent years, with breakthroughs in its applications and the identification of its... (Review)
Review
Gas chromatography-olfactometry (GC-O) has made significant advancements in recent years, with breakthroughs in its applications and the identification of its limitations. This technology is widely used for analyzing complex odor patterns. The review begins by explaining the principles of GC-O, including sample preparation, separation methods, and olfactory evaluation techniques. It then explores the diverse range of applications where GC-O has found success, such as food and beverage industries, environmental monitoring, perfume and aroma development, and forensic analysis. One of the major breakthroughs in GC-O analysis is the improvement in separation power and resolution of odorants. Techniques like rapid GC, comprehensive two-dimensional GC, and multidimensional GC have enhanced the identification and quantification of odor-active chemicals. However, GC-O also has limitations. These include the challenges in detecting and quantifying trace odorants, dealing with matrix effects, and ensuring the repeatability and consistency of results across laboratories. The review examines these limitations closely and discusses potential solutions and future directions for improvement in GC-O analysis. Overall, this review presents a comprehensive overview of the recent advances in GC-O, covering breakthroughs, applications, and limitations. It aims to promote the wider usage of GC-O analysis in odor analysis and related industries. Researchers, practitioners, and anyone interested in leveraging the capabilities of GC-O in analyzing complex odor patterns will find this review a valuable resource. The article highlights the potential of GC-O and encourages further research and development in the field.
Topics: Odorants; Olfactometry; Chromatography, Gas; Humans; Smell; Volatile Organic Compounds
PubMed: 38640191
DOI: 10.1021/acs.jafc.3c08129