Study of structural and electronic origin of ambergris odor of some compounds

The correlation between structural, stereochemical as well as electronic features and ambergris odor of some tricyclic ethers is established based on quantum chemical calculation method. A definite structural fragment (a “new ambergris triangle”) with certain electronic properties determining the origin of the odor is revealed. The influence of HOMO-LUMO energy gaps and total energies of some ambergris compounds on their odor intensity is investigated.     

Structure and function of the antennal sensilla of the palm weevil Rhynchophorus palmarum (Coleoptera, Curculionidae)

The distribution, fine structure and function of the sensilla present on the antennal club of Rhynchophorus palmarum were studied. No sex dimorphism was observed. Scanning and transmission electron microscopy showed five types of hair-like structures, four of which were evenly distributed on the antennal club. Two types of hair (IV and V) showed wall pores, a characteristic of olfactory sensilla. The antenna numbers 11,190 +/- 3040 type IV and 7360 +/- 1500 type V hairs. Using single sensillum recording, we identified 17 types of olfactory receptor neurons (ORNs) on the basis of their responses to pheromone and host plant odors, triggering synergic behavioral responses. We characterized highly specific and sensitive ORNs tuned to the aggregation pheromone (18% ORNs; 0.01-1 ng response threshold) and to host plant odors such as ethyl acetate, ethanol, acetoin and guaiacol (10% ORNs; 1-10 ng response threshold). Eleven percent of the ORNs were more generalist, responding to several odors with low sensitivity. Nine percent of the ORNs showed a complex pattern of responses, being co-activated by the pheromone and plant odors. This suggests an interaction at the sensory neuron level between pheromone and plant odors, triggering synergic behavioral responses.     

Biofiltration eliminates nuisance chemical odors from industrial air streams

This paper focuses on recent developments of biofiltration technology used in treating nuisance chemical odors from industrial and municipal air streams. In the biofiltration process, odorous chemical constituents in the air are first transported to biofilms by diffusion, solubilization and adsorption processes. Bacteria within the biofilms oxidize odor constituents into harmless and odorless products. Through successful laboratory and pilot research on biofiltration of odorous air-stream constituents, numerous commercial biofilters have been designed and installed across North America. In this paper, case studies related to biofiltration of air emissions from meat rendering plants, municipal wastewater treatment applications, and printed circuit board production are discussed to demonstrate the robustness of this technology in eliminating a wide variety of compounds. Electronic Publication     

Ca2+-dependent K+ channels from rat olfactory cilia characterized in planar lipid bilayers

Olfactory cilia contain cyclic nucleotide-gated and Ca2+-dependent Cl- conductances that underlie excitatory chemotransduction, and a Ca2+-dependent K+ (KCa) conductance, apparently involved in inhibitory transduction. Previous single-channel patch-clamp studies on olfactory cilia revealed four different KCas, with different conductances and kinetics. Here, we further characterized these channels in planar bilayers, where blockers could be properly tested. All four ciliary KCas were observed: The 16 pS channel, K0.5,Ca=40 microM and apamin-sensitive; the 30 and 50 pS channel, K0.5,Ca=59 microM, clotrimazole-sensitive and charybdotoxin-insensitive; the 60 pS channel, clotrimazole-sensitive and charybdotoxin-insensitive; and the 210 pS channel, K0.5,Ca=63 microM, blocked by charybdotoxin and iberiotoxin. The presence of the 16 and 210 pS channels was confirmed by immunoblotting.     

Discriminating parts from the whole: determinants of odor mixture perception in squirrel monkeys,Saimiri sciureus

In a task designed to simulate olfactory-guided foraging, the ability of squirrel monkeys to discriminate an artificial 12-component odorant from 3-, 6-, 9- or 11- component submixtures was investigated. A combination of factors was found to contribute to the animals' performance:

Odor discrimination in classical conditioning of proboscis extension in two stingless bee species in comparison to Africanized honeybees

Learning in insects has been extensively studied using different experimental approaches. One of them, the proboscis extension response (PER) paradigm, is particularly well suited for quantitative studies of cognitive abilities of honeybees under controlled conditions. The goal of this study was to analyze the capability of three eusocial bee species to be olfactory conditioned in the PER paradigm. We worked with two Brazilian stingless bees species, Melipona quadrifasciata and Scaptotrigona aff. depilis, and with the invasive Africanized honeybee, Apis mellifera. These three species present very different recruitment strategies, which could be related with different odor-learning abilities. We evaluated their gustatory responsiveness and learning capability to discriminate floral odors. Gustatory responsiveness was similar for the three species, although S. aff. depilis workers showed fluctuations along the experimental period. Results for the learning assays revealed that M. quadrifasciata workers can be conditioned to discriminate floral odors in a classical differential conditioning protocol and that this discrimination is maintained 15 min after training. During conditioning, Africanized honeybees presented the highest discrimination, for M. quadrifasciata it was intermediate, and S. aff. depilis bees presented no discrimination. The differences found are discussed considering the putative different learning abilities and procedure effect for each species.     

Can ambient odors influence the recognition of emotional words? A behavioral and event-related potentials study

Odor context can affect the recognition of facial expressions. However, there is no evidence to date that odor can regulate the processing of emotional words conveyed by visual words. An emotional word recognition task was combined with event-related potential technology. Briefly, 49 adults were randomly divided into three odor contexts (pleasant odor, unpleasant odor, and no odor) to judge the valence of emotional words (positive, negative, and neutral). Both behavioral and Electroencephalography (EEG) data were collected. Both the pleasant odor and unpleasant odor contexts shortened the response time of the subjects to emotional words. In addition, negative words induced greater amplitudes of early posterior negativity (EPN) and late positive potential (LPP) than the positive and neutral words. However, the neutral words induced a larger N400 amplitude than the positive and negative words. More importantly, the processing of emotional words was found to be modulated by external odor contexts. For example, during the earlier (P2) processing stages, pleasant and unpleasant odor contexts induced greater P2 amplitudes than the no odor context. In the unpleasant odor context, negative words with the same odor valence induced greater P2 amplitudes than the positive words. During the later (N400) stages, various regions of the brain regions exhibited different results. For example, in the left and right frontal areas of the brain, exposure to positive words in a pleasant odor context resulted in a smaller N400 amplitude than exposure to neutral words in the same context. Meanwhile, in the left and right central regions, emotional words with the same valence as pleasant or unpleasant odor contexts elicited the minimum N400 amplitude. Individuals are very sensitive to emotional information. With deeper processing, different cognitive processes are reflected and they can be modulated by external odors. In the early and late stages of word processing, both pleasant and unpleasant odor contexts exhibited an undifferentiated dominance effect and could specifically modulate affectively congruent words.     

Odorant-receptor interactions and odor percept: a chemical perspective

Receptor-ligand interaction models are generally based on a 'lock and key' concept. How far this holds true for olfactory receptors and odor molecules is currently uncertain. Here, we have investigated the response of a human olfactory receptor, OR1D2, to a broad array of odorants and found that there is no simple, direct correlation between a molecule's ability to activate this receptor and the odor impression elicited in the brain. In a parallel study on specific anosmia, we have found no evidence for odor-specific anosmia to either musk or amber, but rather to specific molecules within these categories. Cluster analysis confirmed that there is no simple correlation between molecular structure and impaired perception in either odor type. There are some differences in patterns of impairment between the two odor types and some evidence to suggest that subjects with specific anosmia to a given substance can identify its presence in a mixture. Taken together, our results show that simplistic 'lock and key' models of olfaction based on a concept of odor-quality-tuned receptors are inadequate, irrespective of the nature of the lock-key interaction. Receptor activation is only one step in a long chain of events leading from inhalation of odorants to perception of odor in the higher brain, and, therefore, although structure-odor correlations are useful tools for the design of novel odorants, caution should be exercised when extrapolating them to models of olfactory perception. Those seeking to understand the odorant-receptor interaction should use receptor activation rather than odor as input data.     

食物限制对异性大仓鼠气味选择的影响

通过Y型迷宫实验 ,以巢垫物为气味选择源 ,研究了大仓鼠对 60 %限食异性鼠和对照异性鼠气味选择的偏好。结果表明 ,雌雄大仓鼠均较多地选择对照异性鼠的气味 ,但这种选择上的差异并不显著(P >0 0 5 )。12 5I放射免疫法对实验鼠血清中睾酮 (雄性 )和雌二醇 (雌性 )含量的测定结果表明 ,对照鼠血清中睾酮 (雄性 )和雌二醇 (雌性 )激素与 60 %限食鼠无显著差异。表明 60 %限食对大仓鼠异性间气味选择的影响较小。