The Archaeal Na+/Ca2+ Exchanger (NCX_Mj) as a Model of Ion Transport for the Superfamily of Ca2+/CA Antiporters

The superfamily of Calcium/Cation (Ca2+/CA) antiporters extrude Ca2+ from the cytosol or subcellular compartments in exchange with Na+, K+, H+, Li+, or Mg2+ and thereby provide a key mechanism for Ca2+ signaling and ion homeostasis in biological systems ranging from bacteria to humans. The structure-dynamic determinants of ion selectivity and transport rates remain unclear, although this is of primary physiological significance. Despite wide variances in the ion selectivity and transport rates, the Ca2+/CA proteins share structural motifs, although it remains unclear how the ion recognition/binding is coupled to the ion translocation events. Here, the archaeal Na+/Ca2+ exchanger (NCX_Mj) is considered as a structure-based model that can help to resolve the ion transport mechanisms by using X-ray, HDX-MS, ATR-FTIR, and computational approaches in conjunction with functional analyses of mutants. Accumulating data reveal that the local backbone dynamics at ion-coordinating residues is characteristically constrained in apo NCX_Mj, which may predefine the affinity and stability of ion-bound species in the ground and transition states. The 3Na+ or 1Ca2+ binding to respective sites of NCX_Mj rigidify the backbone dynamics at specific segments, where the ion-dependent compression of the ion-permeating four-helix bundle (TM2, TM3, TM7, and TM8) induces the sliding of the two-helix cluster (TM1/TM6) on the protein surface to switch the OF (outward-facing) and IF (inward-facing) conformations. Taking into account the common structural elements shared by Ca2+/CAs, NCX_Mj may serve as a model for studying the structure-dynamic and functional determinants of ion-coupled alternating access, transport catalysis, and ion selectivity in Ca2+/CA proteins.

INVESTIGATION OF METHODS FOR REMOVAL OF PHOSPHATES FROM HOUSEHOLD WASTE WATER

A study of the reagent removal of phosphates from domestic wastewater is presented. The research involved works, the authors of which describe methods for extracting phosphorus compounds from water. The article compares the removal of phosphates from wastewater by various methods in comparison with reagent methods. The analysis of existing technologies for regenerative dephosphorization of wastewater has shown that a promising direction is the search for new reagents for extracting phosphates from wastewater. Preference is given to such reagents as calcium oxide and hydroxide, iron chloride and sulfate, aluminum sulfate. The most eff ective for binding phosphates is the calcium cation, since a greater amount of hardly soluble compounds are formed with it.

MOLECULAR MECHANISM OF RELAXATION ABSORPTION OF ULTRASONIC WAVES IN AN AQUEOUS SOLUTION OF CALCIUM ACETATE

The absorption of ultrasonic waves in the frequency range from 6 to 146 MHz in aqueous solutions of sodium acetate, sodium chloride and calcium has been studied. It was found that only in solutions of calcium cations and acetate anion present simultaneously, relaxation absorption of ultrasonic waves is observed. The experimental data obtained indicate that the observed relaxation absorption of ultrasound in the studied frequency range by an aqueous solution of calcium acetate is associated with the interaction of the acetate anion with the calcium cation in the solution.

Physicochemical weathering conditions of the characteristic white soil horizon at Al Firjah area and it’s vicinity in North Kordofan State, Central Sudan.

Mineral deposits and valuable materials are deposited, concentrated, and purified by natural processes during long or short time, chemical weathering reactions is a major one. Satelliteimages exhibit distinct white horizon of high reflectance. Investigation of this phenomenonreveals that these areas were associatedwith the distal reaches of the major part of the drainage system. Exposures of the basement rocks include metasediments marl, marble, and other silicate rocks(granite, granodiorite,meta andesite,….etc) at high land where the proximal reaches of the drainage system. These rock were subjected to chemical disintegration process of hydrolysis for silicateconstituent and dissolutionfor carbonate constituent and consequently these material were transportedby the drainage system as colloidal (kaolinite) and dissolved material(calcium cation and bicarbonate), eventually these material were deposited due to evaporation at flash delta to form the kaolinite carbonatesoil at Alfirjah area and it’s vicinity. Field observations in addition to rock and soil sample analysis forearm the above mentioned hypothesis.

Study of the relationships between the builders of crystal formation in table wines

Изучались процессы формирования тартратных солей калия и кальция в винах в зависимости от различных соотношений компонентов и рН. В работе использовано 212 образцов белых столовых сухих вин, выработанных на предприятиях Крыма. В образцах определяли значения рН, массовую концентрацию винной кислоты и ее форм, катионов калия и кальция, температуру насыщения вин битартратом калия (Тнас KHTar) и тартратом кальция (Тнас СаТ). По экспериментальным данным рассчитывали соотношения: винной кислоты к рН, битартратной формы к катиону калия (HT/К), тартратной формы к катиону кальция (T/Са), а также двух последних соотношений к рН. Полученные данные обрабатывались в программной среде Exсel MS Office. Установлен различный характер процессов, протекающих в винах под влиянием рН: повышение значения Тнас KHTar сопровождается снижением рН, повышение Тнас СаТ - возрастанием рН. Увеличение вклада содержания винной кислоты на единицу рН приводит к повышению склонности образцов к образованию тартратных солей. Между температурой насыщения вин битартратом калия и тартратом кальция установлена линейная зависимость (R = 0,963 и 0,968). Общим признаком формирования калиевых и кальциевых тартратных солей в вине является зависимость температуры насыщения от соотношений (HT/К)/рН и (T/(Са)/рН. Полученные результаты будут использованы для совершенствования методики диагностики кристаллических помутнений вин. The processes of formation of potassium and calcium tartrate salts in wines were studied in accordance with the equivalence ratio and pH. During the work we used 212 samples of white table dry wines produced in the enterprises of Crimea. The values of pH, mass concentration of tartaric acid and its forms, potassium and calcium cations, temperature of wine saturation with potassium bitartrate (Тsat KHTar) and calcium tartrate (Тsat CaT) were determined in samples. Experimental entries were used to calculate the ratios: tartaric acid to pH, bitartrate form to potassium cation (HT/К), tartrate form to calcium cation (T/Са), as well as the last two ratios to pH. The entries obtained were processed in Excel MS Office software. Different nature of processes in wines under the influence of pH was established: an increase in the value of Тsat KHTar is accompanied by a decrease in pH, an increase in Тsat CaT - by an increase in pH. An increase in the contribution of tartaric acid content per pH unit leads to an increase in the tendency of samples to form tartrate salts. A linear dependence was established between the saturation temperature of wines with potassium bitartrate and calcium tartrate (R= 0.963 and 0.968). A common feature of the formation of potassium and calcium tartrate salts in wine is the dependence of the saturation temperature on the ratios (HT/К)/рН and (T/(Са)/рН. The results obtained will be used to improve the methods of diagnosing the crystalline haze of wines.

Formation of water chemistry in the Modonkul river under the action of mine drainage effluent

The Dzhida ore field in the Zakamensk district of Buryatia features high concentration of mineralization within a small area. The Dzhida deposit is composed of complex ore. The ore field contains commercial-value primary deposits: Pervomai stockwork of molybdenum, Kholtoson tungsten lode and Inkur stockwork of tungsten. The Modonkul river catchment basin lies inside the Dzhida ore field. A real threat to the town of Zakamensk is created by manmade sand-bulk (old) tailings and slurry dump. By now, the concentrated flow of natural and man-made sand enters the low terrace and floodplain of the Modonkul river in the form of a talus train. This study is focused on the influence of the mine drainage effluent and the Inkur tributary on the water chemistry in the Modonkul river. 80 water samples were taken from the surface layer 0-0.5 m thick at five stations. Physicochemical indices of water were measured at the water sampling points, and the water chemistry was analyzed in a laboratory. In the background conditions, cations and anions in the Modonkul water chemistry range in decreasing order as follows: Са2+ > Mg2+ > Na++К+ и HCO - > SO 2- > Cl-. In the zone of mixture of natural and mine process water, the chemistry changes: from hydrocarbonate to sulfate (anion), from calcium-magnesium to sodium-calcium (cation). Downstream the natural chemistry changes to the hydrocabonate-sulfate composition, with prevailing content of calcium in cations. Iron content of water lowers 3-4 times after influx of mine effluents, while the contents of Mn, Zn, Co and Cd grow and then decrease downstream.

Calcium-sensing receptor antagonism as a novel therapeutic for pulmonary fibrosis

ABSTRACTBackgroundIdiopathic pulmonary fibrosis (IPF) is a disease with very poor prognosis and no curative therapies. The G protein-coupled, calcium/cation-sensing receptor (CaSR) is activated by environmental pollutants and by arginine-derived polyamines, which are thought to play a role in IPF. Whether the CaSR is involved in the pathogenesis of pulmonary fibrosis is unknown.ObjectiveTo investigate the CaSR as a novel drug target for the treatment of pulmonary fibrosis (PF).Methods and resultsCaSR protein expression is found in the airway epithelium in the neuroepithelial bodies of the healthy and IPF human lung. Expression of arginine pathway-linked polyamines is increased in PF patient saliva samples compared to non-PF patients. Arginine pathway metabolites, ornithine and spermine, activate the CaSR in primary normal human lung fibroblasts (NHLF), effects prevented by CaSR antagonism using the calcilytic NPS2143. In NHLF calcilytic also reversed the pro-fibrotic effects of exogenous TGFβ1 administration on Rho kinase and αSMA expression, proliferation, collagen production and IL-8 secretion. Targeted CaSR ablation from fibroblasts and smooth muscle cells protects mice from spontaneously occurring, age-related lung fibrosis.ConclusionsSustained CaSR activation in the lung drives pro-fibrotic processes, which can be reversed by calcilytic. Pharmacological and genetic CaSR blockade reduce both TGFβ1-induced and naturally occurring pro-fibrotic changes. This work provides the scientific rationale for developing inhaled calcilytics as novel therapeutics for IPF.KEY MESSAGESKey questionHow does the calcium/cation-sensing receptor (CaSR) promote pulmonary fibrosis?Bottom lineThe CaSR is expressed in human IPF and experimental models of PF where receptor inhibition prevents pro-fibrotic changes and pulmonary remodeling.Why read onCaSR blockers, calcilytics, represent a novel treatment for IPF.