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In humans, food choice, nutrient intake, and meal size are strongly influenced by sense of smell. It is known that individuals differ in their olfactory abilities and may show a normal, reduced, or absent sense of smell. Previous findings have also suggested that males are more deficient than females in their olfactory performance. Recent studies have shown that humans could perceive the odor of free fatty acids, providing information about the nutritional content of foods. The aim of this research was to study the orthonasal perception of palmitic, oleic, and linoleic fatty acids in 70 healthy subjects (38 females and 32 males). First, participants were classified as normosmic or hyposmic by means of the Sniffin’ Sticks test. Second, the ability to detect the odor of fatty acids was assessed using the gas chromatography–olfactometry technique, a combination of sensory and instrumental analysis that allows for simultaneous chromatographic separation and odor evaluation by a human subject. Finally, the olfactory threshold to fatty acids was also evaluated by means of a three-way forced-choice test, using a presentation procedure of ascending concentration with seven dilution steps. The results highlighted differences in perception ability, perception intensity, and olfactory threshold in relation to the lipophilicity of the molecule, olfactory function, and sex. Our findings confirm the human ability to perceive the odor of fatty acids, with females and normosmic individuals performing better than males and hyposmic ones, respectively. They also show that the intensity of perception increases with the decreasing lipophilicity of fatty acids; consequently, the olfactory perception threshold also decreases.

Objective : This cross-sectional study evaluates the impact of active or non-active lifestyle in terms of physical, cognitive and social activity on the olfactory function in Elderly Subjects (ES) and aims at looking for a correlation between the time devoted to life activities and the score obtained during the olfactory tests by each individual. Methods : One hundred and twenty-two elderly volunteers were recruited in Sardinia (Italy) and divided into active ES ( n = 60; 17 men, 43 women; age 67.8 ± 1.12 years) and inactive ES ( n = 62; 21 men, 41 women, age 71.1 ± 1.14 years) based on their daily physical activities. The olfactory function was evaluated using the “ Sniffin’s Sticks ” battery test, while the assessment of daily activities was made by means of personal interviews. Results : A significant effect of active or inactive lifestyle was found on the olfactory function of ES ( F (1,120) > 10.16; p < 0.005). A positive correlation was found between the olfactory scores and the number of hours per week dedicated to physical activities (Pearson’s r > 0.32, p ≤ 0.014) in both active and inactive ES. Conclusions : High levels of exercise and non-exercise physical activity are strongly associated with the olfactory function and, consequently, with the quality of life of the elderly. Given the limited physical exercise of elderly people, they can benefit from a more active lifestyle by increasing non-exercise physical activities.

[...]a large amount of scientific knowledge in genetics has been obtained from fruit fly experiments, as well as population biology in flour beetle studies. Alternatively, the possibility exists that global species numbers might be underestimated because of cryptic diversity [2,8]. [...]the use of good morphological methods and intensive studies with large specimen numbers from many localities would help separate most species previously found to be cryptic. The availability of host plants and an insect’s ability to find them are key factors for the survival of a species because they represent both suitable oviposition sites for adult females and potential food sources for the offspring [18,19,20]. By analyzing the distribution pattern, species richness, and biodiversity in the Mongolian ecoregions and correlating them with environmental variables, the authors concluded that annual precipitation and the maximum temperature of the warmest month were the most important environmental variables that correlated in an analysis of geometrid assemblages

One of the still-debated topics regarding the olfactory function concerns the presence or absence of sex-related differences in individuals. In this study, we checked for a relationship between the olfactory function of females and males and their ability to perceive single molecules, and researched how this can influence the intensity with which the complex odor formed by a set of single molecules is perceived. First, females and males were classified as normosmic or hyposmic based on the TDI olfactory score obtained using the Sniffin’ Sticks test. Subsequently, the headspace of roasted coffee beans, as a complex olfactory stimulus, was broken down into single molecules by means of a chromatographic column; these were simultaneously conveyed to a mass spectrometer (for their subsequent classification) and to the human nose, which acts as a chemical sensor by means of an olfactometer port. The results obtained with this gas chromatography–olfactometry approach show both qualitative and quantitative differences between females and males, with females performing better than males. In addition, the odor intensity reported by females when sniffing pen #10, containing coffee aroma, is significantly higher than that reported by males. In conclusion, these data highlight that the human ability to perceive both single compounds and complex odors is strongly conditioned, not only by the olfactory function of individuals, but also by their sex.

“Calling behaviour” is a stereotyped rhythmic motor pattern displayed by female moths, by which they emit the sex pheromone to attract of conspecific males. Calling occurs through a squeezing mechanism based on the turtleneck-like folding and unfolding of the ovipositor cuticle during its telescopic extensions and retractions. This mechanism is under the control of the terminal abdominal ganglion (TAG). By combining anatomical and electrophysiological approaches, here we studied the morpho-functional organisation of the abdominal muscles and the activity of motoneurons from TAG nerve N4-N6 as correlated to the ovipositor movements during calling in the female spongy moth Lymantria dispar. Our results show that the three abdominal segments S7, S8 and S9 (ovipositor) are highly specialized structures containing cuticular appendages, hinges, apodemes and several large muscles, innervated by N4 and especially by N5. N6 mainly innervates the oviductal tract. We also identified a number of motor units from N4 and N5, the spike activity of which is correlated with the ovipositor movements during calling. In conclusion, the release of sex pheromones in the female spongy moth is obtained by extensions and retractions of the ovipositor operated by a coordinated motor program, which is mainly sustained by the activity of a few motor units under the control of TAG nerves N4 and N5.

Practical and reliable methods for the objective measure of taste function are critically important for studying eating behavior and taste function impairment. Here, we present direct measures of human gustatory response to a prototypical bitter compound, 6-n-propyltiouracil (PROP), obtained by electrophysiological recordings from the tongue of subjects who were classified for taster status and genotyped for the specific receptor gene ( TAS2R38 ), and in which taste papilla density was determined. PROP stimulation evoked negative slow potentials that represent the summated depolarization of taste cells. Depolarization amplitude and rate were correlated with papilla density and perceived bitterness, and associated with taster status and TAS2R38 . Our study provides a robust and generalizable research tool for the quantitative measure of peripheral taste function, which can greatly help to resolve controversial outcomes on the PROP phenotype role in taste perception and food preferences, and be potentially useful for evaluating nutritional status and health.

The peripheral sensitivity and palatability of different carbohydrates was evaluated and their nutritional value assessed in adult females of D. suzukii by means of an electrophysiological, behavioural and metabolic approach. The electrophysiological responses were recorded from the labellar \"l\" type sensilla stimulated with metabolizable mono- and disaccharides (glucose and maltose) and a non-metabolizable sugar (sucralose); the response rating and the palatability to the same sugars, evaluated by recording the proboscis extension reflex (PER), was maltose>glucose>sucralose. The nutritional value of carbohydrates was assessed by means of survival trials and fatty acids profile. Flies fed on a diet containing maltose had a longer lifespan than flies on monosaccharides, while flies fed on a diet containing sucralose had a shorter one. In addition, the ability to store fat seems to be influenced by the different sugars in the diet and is in relationship with their palatability. In fact, data showed a higher synthesis of palmitic and palmitoleic acids, most likely derived from de-novo lipogenesis with glucose as precursor, in flies fed with maltose and glucose than with non-metabolizable sucralose. In conclusion, these results suggest that the ability to select different sugars on the basis of their palatability may favour the storage of energy reserves such as fat by de-novo lipogenesis, determining a longer survival capability during prolonged periods of fasting.

The flavor of foods and beverages is generally composed of a mixture of volatile compounds, however not all the molecules that form an aroma are sensorially relevant. The odor-active compounds present in a mixture are different for each subject, both in quantitative and qualitative terms. This means that the ability of the human nose to act as a chemical sensor varies among individuals. In this study, we used the headspace of roasted coffee beans as a complex olfactory stimulus and, by means of the coupled Gas Chromatography-Olfactometry (GC-O) technique, the single components of coffee flavor were separated. Each subject, previously classified for his/her olfactory status (normosmic, hyposmic or anosmic) by means of the Sniffin’ Sticks battery (composed of Threshold, Discrimination and Identification subtests), had to identify and evaluate each smelled molecule. The results show that the individual ability to detect individual compounds during the GC-O experiments and the odor intensity reported during the sniffing of pen #10 (the pen of the identification test) containing coffee aroma were related to TDI olfactory status (based on the score obtained from the sum composed of Threshold, Discrimination and Identification scores). We also found that the number of total molecules and of molecules smelling of coffee is linearly related to the TDI olfactory score. Finally, the odor intensity reported when sniffing pen #10 containing coffee aroma is positively correlated with the number of molecules detected and the average intensity reported. In conclusion, our findings show that the human perception of both individual compounds and complex odors is strongly conditioned by the olfactory function of subjects.

Orosensory perception of dietary fat varies in individuals, thus influencing nutritional status. Several studies associated fat detection and preference with CD36 or 6-n-propylthiouracil (PROP) sensitivity. Other studies have not confirmed the latter association. We analyzed the relationship between orosensory perception of oleic acid, two CD36 variants, and PROP tasting. Thresholds of oleic acid perception were assessed in 64 subjects using a modification of the three-alternative forced-choice procedure. Subjects were classified for PROP taster status and genotyped for TAS2R38 and CD36 (SNPs: rs1761667 and rs1527483). Subjects homozygous for GG of the rs1761667 polymorphism showed higher sensitivity to oleic acid than AA subjects. The capability to detect oleic acid was directly associated with TAS2R38 or PROP responsiveness. PROP non-tasters had a lower papilla density than tasters, and those with genotype GG of the rs1761667 polymorphism had lower oleic acid thresholds than PROP non-tasters with genotype AA. In conclusion, results showed a direct association between orosensory perception of oleic acid and PROP tasting or rs1761667 polymorphism of CD36, which play a significant role in PROP non-tasters, given their low number of taste papillae. Characterization of individual capability to detect fatty acids may have important nutritional implications by explaining variations in human fat preferences.

TAS2R38 is the T2R receptor primarily associated with the innate immune response of the respiratory system. It activates a response mediated by nitric oxide (NO), which has been shown to inhibit the replication of SARS-CoV-2. TAS2R38 polymorphisms (SNPs) that decrease receptor functionality contributing to individual differences in susceptibility to airway infections. DNA methylation (DNAm) may affect gene expression influencing disease development, including COVID-19. We analyzed the effect of SARS-CoV-2 on the methylation pattern of TAS2R38 (at cg25481253, a CpG site located in the coding region) during infection and after the cessation of the exposure to the virus, also considering the disease severity and TAS2R38 SNPs. Our results showed a positive relationship between TAS2R38 DNAm levels and disease severity in the COVID-19 patients and a return to a normal state after the infection. In addition, our results showed an association between DNAm level and the TAS2R38 genotype in participants who recovered from the disease. PAV/PAV genotypes showed lower TAS2R38 DNAm levels than heterozygous and AVI homozygous. In conclusion, our results clearly indicate the involvement of TAS2R38 DNAm alteration in COVID-19 severity and suggest a role of the methylation changes at cg25481253 in the regulation of the TAS2R38 expression.