Modulation of postendocytic sorting of G protein-coupled receptors

Recycling of the mu opioid receptor to the plasma membrane after endocytosis promotes rapid resensitization of signal transduction, whereas targeting of the delta opioid receptor (DOR) to lysosomes causes proteolytic down-regulation. We identified a protein that binds preferentially to the cytoplasmic tail of the DOR as a candidate heterotrimeric GTP-binding protein (G protein)-coupled receptor-associated sorting protein (GASP). Disruption of the DOR-GASP interaction through receptor mutation or overexpression of a dominant negative fragment of GASP inhibited receptor trafficking to lysosomes and promoted recycling. The GASP family of proteins may modulate lysosomal sorting and functional down-regulation of a variety of G protein-coupled receptors.     

Infiltration of inorganic compounds from the Glatt River,Switzerland, into a groundwater aquifer

The behavior of dissolved (<0.45 μm) inorganic compounds during infiltration of river water into the adjacent aquifer (unconsolidated glacio-fluvial sediments) was investigated at the Glatt River, Switzerland, field site. The water was sampled in the river and from wells at distances of 2.5, 5, 13, and 110 m along an estimated groundwater flow line. Sodium, K, Ca, Mg, Sr, Cr, Cu, Zn, Cd, Pb, Cl^?, NO₃ ^?, SO₄ ^2?, and PO₄ ^3? were measured using AAS, NAA, and ion chromatography. Groundwater concentrations of these species are mainly determined by the concentrations in the river. However, the concentrations of NO₃ ^?, (PO₄ ^3?), Cr, Cu, Zn, Cd, and Pb are also subject to seasonal variations in the near infiltration field (≤ 5 m). These variations are probably triggered by temperature dependent biological processes which influence parameters such as pH, redox potential and complexing agents. The redox potential controls the chemical behavior of Mn, which influences the solubility of heavy metal compounds. The extent of inorganic pollution in the investigated system is still much below drinking water standards, but for Cd, reaches the toxicity limit for aquatic organisms.     

Matrix modification to improve the recovery of MMHg from clear water using distillation

The use of distillation from aqueous solution dramatically improves the recovery of methyl mercury (MMHg) from complex water samples, as compared to solvent extraction techniques. However, low and irreproducible spike recoveries are often observed when distillation is applied to very clear water samples (i.e., precipitation, double deionized water (DDW), etc.) or those containing high chloride concentrations. Based upon the observation that recoveries and reproducibility are higher for waters containing strong complexing compounds, such as humic matter, we investigated the potential of matrix modification to improve the reproducibility of MMHg by distillation from more difficult matrices. At sample acid concentrations of less than 0.1M hydrochloric acid (HCl), we found that the addition of complexers such as ammonium pyrrolidine dithiocarbamate (APDC), and aqueous humic substances improved distillation spike recoveries and reproducibility. The use of complexers was also found to suppress the co-distillation of divalent mercury (Hg(II), which, in highly contaminated samples can be an interferant with the MMHg determination. At higher HCl concentrations, irreproducibility was dominated by the interference caused by chloride co-distilled with the water. In these cases, neither the addition of complexing agents, or buffers to bind the free hydrogen ions (H⁺) in solution were effective in improving results.     

Quantitative Mineralbestimmung in der Schlufffraktion von Böden auf der Grundlage der chemischen Analyse und unter Anwendung der Karl-Fischer-Titration. I. Verfahren

Quantitative estimation of the mineralogical composition of silt fractions of soils based on both, chemical analysis and application of Karl-Fischer-titration. I. Method This paper describes a method for calculating the mineralogical composition of the silt fractions of soils. The chemical analysis and the temperature dependence of water release are used for determining micas and feldspars, each in three components in a relatively short procedure. The release of water was measured by Karl-Fischer-titration at controlled temperatures. At temperatures above 550°C the water release of the particle size fractions correlates with their content of micas. The quantity of micas can be obtained from the amount of released water and the results of the chemical analysis. The influence of kaolinite, amphibole and the fluoride content on the calculation is described. By considering the potassium content of the mica fraction results of the chemical analysis are used to quantify feldspars.     

Wasserhaushalt und Dickenwachstum von Kiefern in Abhängigkeit des Grundwasserflurabstandes

Water budget and annual ring growth of pines for different groundwater depth conditions Relation between annual ring width and water supply was examined for different groundwater depth in an old pine stand on a sandy soil. The quotient Ereal/Epot is a suitable parameter to quantify water stress. Multiple regression analyses were used to describe the dependence between annual ring width and water stress. Mean growth of basal area can be expressed by Ereal/Epot of the actual and previous year. This site specific function was used to quantify growth reduction affected by ground-water lowering for various soil conditions.