Genetic sensitivity to the bitter taste of 6-n-propylthiouracil (PROP) and its association with Physiological mechanisms controlling Body Mass Index (BMI)

Taste sensitivity to the bitter compound 6-n-propylthiouracil (PROP) is considered a marker for individual differences in taste perception that may influence food preferences and eating behavior, and thereby energy metabolism. This review describes genetic factors that may contribute to PROP sensitivity including: (1) the variants of the TAS2R38 bitter receptor with their different affinities for the stimulus; (2) the gene that controls the gustin protein that acts as a salivary trophic factor for fungiform taste papillae; and (3) other specific salivary proteins that could be involved in facilitating the binding of the PROP molecule with its receptor. In addition, we speculate on the influence of taste sensitivity on energy metabolism, possibly via modulation of the endocannabinoid system, and its possible role in regulating body composition homeostasis

Marked increase in PROP taste responsiveness following oral supplementation with selected salivary proteins or their related free amino acids

The genetic predisposition to taste 6-n-propylthiouracil (PROP) varies among individuals and is associated with salivary levels of Ps-1 and II-2 peptides, belonging to the basic proline-rich protein family (bPRP). We evaluated the role of these proteins and free amino acids that selectively interact with the PROP molecule, in modulating bitter taste responsiveness. Subjects were classified by their PROP taster status based on ratings of perceived taste intensity for PROP and NaCl solutions. Quantitative and qualitative determinations of Ps-1 and II-2 proteins in unstimulated saliva were performed by HPLC-ESI-MS analysis. Subjects rated PROP bitterness after supplementation with Ps-1 and II-2, and two amino acids (L-Arg and L-Lys) whose interaction with PROP was demonstrated by (1)H-NMR spectroscopy. ANOVA showed that salivary levels of II-2 and Ps-1 proteins were higher in unstimulated saliva of PROP super-tasters and medium tasters than in non-tasters. Supplementation of Ps-1 protein in individuals lacking it in saliva enhanced their PROP bitter taste responsiveness, and this effect was specific to the non-taster group.(1)H-NMR results showed that the interaction between PROP and L-Arg is stronger than that involving L-Lys, and taste experiments confirmed that oral supplementation with these two amino acids increased PROP bitterness intensity, more for L-Arg than for L-Lys. These data suggest that Ps-1 protein facilitates PROP bitter taste perception and identifies a role for free L-Arg and L-Lys in PROP tasting

Global properties of dilatonic Gauss-Bonnet black holes

We study the phase space of the spherically symmetric solutions of Einstein Gauss-Bonnet system nonminimally coupled to a scalar field and show that in four dimensions the only regular black hole solutions are asymptotically flatComment: 12 pages, plain TeX; v.2: phase space is described in more detai

A polymorphism in the human gene encoding OBPIIa affects the perceived intensity of smelled odors

Among the factors that contribute to the physiological variability of the olfactory function of individuals, an important role seems to be played by the OBPs present in the mucus that bathes the ciliated terminals of the olfactory sensory neurons, facilitating the access of odorants to the olfactory receptors. It was recently highlighted that the rs2590498 polymorphism in the odor binding-protein (OBPIIa) gene it is associated with the olfactory threshold in healthy individuals. Aim of this study was to evaluate: 1) the presence of a relationship between the threshold olfactory performance of healthy subjects and the intensity with which they perceive the smelled odorants, and 2) the effect of the rs2590498 polymorphism of the OBPIIa gene on perceived intensity. We found a positive correlation between threshold olfactory and perceived intensity, and that AA homozygous subjects reported a perceived intensity higher than heterozygous and GG homozygous subjects. By showing a positive effect of the rs2590498 polymorphism of the hOBPIIa gene on the intensity perceived, these results suggest that it allows a larger number of molecules in an odorous mixture to reach the olfactory receptors

Mid to late Holocene environmental changes along the coast of western Sardinia (Mediterranean Sea)

Multiproxy analysis composed of biostratigraphy and pollen analysis allowed reconstructing the palaeoecological and palaeoenvironmental evolution of the Tirso river coastal plain in Sardinia (NW Mediterranean) in the last 6 millennia. We demonstrated that interplay between littoral and fluvial processes have significantly controlled the environmental evolution of the area and have played a key role in the pattern of historical and prehistorical settlements of this wide portion of western Sardinian coastline. At the end of Neolithic period (ca. 6.0 to 5.5 cal. ka BP) the area close to the shoreline was most likely characterized by large coastal lagoons intermittently connected to the open sea. Such saltwater influence is corroborated by faunal and pollen assemblages found in the landward portion of the Tirso coastal plain up to 2 km inland from the modern shoreline. Our data robustly document the end of the transgressive trend at ca. 5.5 cal. ka BP, and a dominant fluvial sedimentation since Final Neolithic period. At this time, a progradational trend started, causing the seaward migration of shoreline and, consequently, of the barrier-lagoon system. The major landscape modification tracked along the last 6 millennia may also explain the low density of historical and prehistorical remains in the Tirso coastal plain, especially if compared to the nearby rocky area of Sinis Peninsula densely inhabited since the Neolithic. Our data further provide new insights into the Relative Sea Level (RSL) evolution in this sector of the Mediterranean. In particular, we improved the mid-Holocene RSL record in Sardinia, where only scarce data were previously available

Changes of taste, smell and eating behavior in patients undergoing bariatric surgery: Associations with prop phenotypes and polymorphisms in the odorant-binding protein OBPIIa and CD36 receptor genes

Bariatric surgery is the most effective long-term treatment for severe obesity and related comorbidities. Although patients who underwent bariatric surgery report changes of taste and smell perception, results from sensory studies are discrepant and limited. Here, we assessed taste and smell functions in 51 patients before, one month, and six months after undergoing bariatric surgery. We used taste strip tests to assess gustatory function (including sweetness, saltiness, sourness, uma-miness, bitterness and oleic acid, a fatty stimulus), the “Sniffin’ Sticks” test to assess olfactory identification and the 3-Factor Eating Questionnaire to assess eating behavior. We also explored associations between these phenotypes and flavor-related genes. Results showed an overall improvement in taste function (including increased sensitivity to oleic acid and the bitterness of 6-n-propylthiou-racil (PROP)) and in olfactory function (which could be related to the increase in PROP and oleic acid sensitivity), an increase in cognitive restraint, and a decrease in disinhibition and hunger after bariatric surgery. These findings indicate that bariatric surgery can have a positive impact on olfactory and gustatory functions and eating behavior (with an important role of genetic factors, such PROP tasting), which in turn might contribute to the success of the intervention