The Bitter Taste Receptor TAS2R14 as a Drug Target

G protein-coupled receptors (GPCRs) mediate most of our physiological responses to hormones, neurotransmitters and environmental stimulants. Besides human senses like vision and olfaction, taste perception is mostly mediated by GPCRs. Hence, the bitter taste receptor family TAS2R comprises 25 distinct receptors and plays a key role in food acceptance and drug compliance. The TAS2R14 subtype is the most broadly tuned bitter taste receptor, recognizing a range of chemically highly diverse agonists. Besides other tissues, it is expressed in human airway smooth muscle and may represent a novel drug target for airway diseases. Several natural products as well as marketed drugs including flufenamic acid have been identified to activate TAS2R14, but higher potency ligands are needed to investigate the ligand-controlled physiological function and to facilitate the targeted modulate for potential future clinical applications. A combination of structure-based molecular modeling with chemical synthesis and in vitro profiling recently resulted in new flufenamic acid agonists with improved TAS2R14 potency and provided a validated and refined structural model of ligand–TAS2R14 interactions, which can be applied for future drug design projects

Leaf-Level Field Spectroscopy to Discriminate Invasive Species (Psidium guajava L. and Hovenia dulcis Thunb.) from Native Tree Species in the Southern Brazilian Atlantic Forest

Invasive species are known to have potential advantages over the native community and can be expressed in their leaf functional traits. Thus, leaf-level traits with spectral reflectance can provide valuable insights for distinguishing invasive trees from native trees in complex forest environments. We conducted field spectroscopy measurements in a subtropical area, where we also collected trait data for 12 functional traits of invasive (Psidium guajava and Hovenia dulcis), and native species (Psidium cattleianum and Luehea divaricata). We found that photosynthetic pigments were responsible for the greatest interspecific variability, especially in the green region of the spectrum at 550 nm, therefore contributing to detection of invasive species. In addition, according to LDA and stepwise procedures, the most informative reflectance spectra were concentrated in the visible range that is closely related to pigment absorption features. Furthermore, we aimed to understand the leaf optical properties of the target invasive species by using a combination of narrow bands and linear regression models. P. guajava showed high correlations with specific leaf area, Car/Chl and relative water content. H. dulcis had a strong correlation with water content, specific leaf area and Chla/Chlb. Overall, this methodology proved to be appropriate for discriminating invasive trees, although parameterization by species is necessary

Junctions and thin shells in general relativity using computer algebra I: The Darmois-Israel Formalism

We present the GRjunction package which allows boundary surfaces and thin-shells in general relativity to be studied with a computer algebra system. Implementing the Darmois-Israel thin shell formalism requires a careful selection of definitions and algorithms to ensure that results are generated in a straight-forward way. We have used the package to correctly reproduce a wide variety of examples from the literature. We present several of these verifications as a means of demonstrating the packages capabilities. We then use GRjunction to perform a new calculation - joining two Kerr solutions with differing masses and angular momenta along a thin shell in the slow rotation limit.Comment: Minor LaTeX error corrected. GRjunction for GRTensorII is available from http://astro.queensu.ca/~grtensor/GRjunction.htm

Intradiurnal and seasonal variability of soil temperature, heat flux, soil moisture content, and thermal properties under forest and pasture in Rondônia.

Soil temperatures depend on the soil heat flux, an important parameter in meteorological and plant growth-energy balance models. Thus, they were measured, together with soil moisture contents, within the LBA program at forest (Reserva Jaru) and pasture (Fazenda Nossa Senhora) sites in Rondônia, Brazilian Amazonia during wet (February) and dry (August) periods of 1999. The wet period showed maxima of the heat flux into the soil around five to six times smaller at the forest than at the pasture, except for some spikes that are related to stronger solar forcing, such as those due to sunspecks in the forest. This pattern remained during the dry period, but with doubled maximum values. Also, the soil heat flux and the soil temperatures responded very significantly to the passage of cold fronts in both periods at both sites. Temperature profiles measured in the 0.10-0.40 m soil layer showed daily averages and ranges smaller at the forest than at the pasture. The daily average of the soil moisture content in the same layer, during the wet season, increased with depth at both sites, with consistently lower values at the forest. However, their ranges were smaller at the pasture, except for the 0.40 m depth. During the dry period, these ranges were much higher at the pasture, but with nearer average values. Finally, the computed daily apparent soil thermal diffusivities, volumetric heat contents, and thermal conductivities are presented, with the first ones crossed with the measured soil moisture content

Can Astrophysical Gamma Ray Sources Mimic Dark Matter Annihilation in Galactic Satellites?

The nature of the cosmic dark matter is unknown. The most compelling hypothesis is that dark matter consists of weakly interacting massive particles (WIMPs) in the 100 GeV mass range. Such particles would annihilate in the galactic halo, producing high-energy gamma rays which might be detectable in gamma ray telescopes such as the GLAST satellite. We investigate the ability of GLAST to distinguish between the WIMP annihilation spectrum and the spectrum of known astrophysical source classes. Focusing on the emission from the galactic satellite halos predicted by the cold dark matter model, we find that the WIMP gamma-ray spectrum is unique; the separation from known source classes can be done in a convincing way. We discuss the follow-up of possible WIMP sources with Imaging Atmospheric Cerenkov Telescopes. Finally we discuss the impact that Large Hadron Collider data might have on the study of galactic dark matter

Evaporation from Pinus caribaea plantations on former grassland soils under maritime tropical conditions.

Wet canopy and dry canopy evaporation from young and mature plantations of Pinus caribaea on former grassland soils under maritime tropical conditions in southwestern Viti Levu, Fiji, were determined using micrometeorological and hydrological techniques. Modeled annual evaporation totals (ET) of 1926 and 1717 mm were derived for the 6- and the 15-year-old stands, respectively. Transpiration made up 72 and 70 of annual ET, and modeled rainfall interception by the trees and litter layer was 20-22 and 8-9 in the young and the mature stands respectively. Monthly ET was related to forest leaf area index and was much higher than that for the kind of tall fire-climax Pennisetum polystachyon grassland replaced by the forests. Grassland reforestation resulted in a maximum decrease in annual water yield of 1180 mm on a plot basis, although it is argued that a reduction of (at least) 500-700 mm would be more realistic at the catchment scale. The impact of reforesting grassland on the water resources in southwest Viti Levu is enhanced by its location in a maritime, seasonal climate in the outer tropics, which favors a larger difference between annual forest and grassland evaporation totals than do equatorial regions