Dependence of the Osmotic Pressure and Electrical Conductivity of Soil Solutions on the Soil Water Content

Eurasian Soil Science - The osmotic pressure and electrical conductivity were determined with the use of instrumental methods (centrifuging, conductometry, and cryoscopy) in equilibrium soil...     

Change of hydrophysical properties of clayed minerals due to the influence of soluble salts

It was revealed that the influence of soluble salts on the hydrophysical properties of clayed minerals depends on the nature of minerals, the properties and state of salt (in solution or sorbing), and the region of fundamental hydrophysical characteristics (FHCH). The treatment of clayed minerals by NaCl, MgCl₂, Ca(CH₃COO)₂, and ZnCl₂ solutions increased their water-retention in the range NaCl > MgCl₂ > Ca(CH₃COO)₂ ≈ ZnCl₂. Pb(CH₃COO)₂ decreased the water-retaining ability of clayed minerals in all the FHCH range. A differential characteristic of the action MgCl₂, Ca(CH₃COO)₂, and ZnCl₂ on smectite is decrease of capillary water deduction.     

Geographical aspects of forest litters

Litter and humus formations are considered as two interrelated processes. On the basis of analysis of geographic patterns of litter formation, we set up a hypothesis for the capacity invariance of the modern area where there is conversion of terrestrial detritus, which correlates with the level of functioning of terrestrial ecosystems measured according to the level of soil respiration. It is discovered that not only the single ecological space, which is optimal for humification, gets narrow, but also its major centers are shifted within the limits of geochemically conjugated landscapes.     

Corpus Luteum Development and Function after Supplementation of Long‐Acting Progesterone During the Early Luteal Phase in Beef Cattle

Strategic supplementation of P4 may be used to increase conception rates in cattle, but timing of supplementation in relation to ovulation, mass of supplementary P4 and formulation of the P4‐containing supplement has not been determined for beef cattle. Effects of supplementation of long‐acting progesterone (P4) on Days 2 or 3 post‐ovulation on development, function and regression of corpus luteum (CL) were studied in beef cattle. Cows were synchronized with an oestradiol/P4‐based protocol and treated with 150 or 300 mg of long‐acting P4 on Day 2 or 3 post‐ovulation (6–7 cows/group). Colour‐doppler ultrasound scanning and blood sample collection were performed from Day 2–21.5. Plasma P4 concentrations were greater (p < 0.05) from Day 2.5–5.5 in the Day 2‐treated groups and from Day 3.5–5.5 in the Day 3‐treated cows than in the control group. CL area and blood flow during Day 2–8.5 did not differ (p > 0.05) among groups, suggesting no effect of P4 treatment on luteal development. The frequency of cows that began luteolysis before Day 15 was greater (p < 0.04) in cows treated with 300 mg than in the controls, but there were no differences between non‐treated and 150 mg‐treated cows. The interval from pre‐treatment ovulation to functional and structural luteolysis was shorter (p < 0.01) in the combined P4‐treated groups than in the control cows. In conclusion, was showed for the first time that long‐acting P4 supplementation on Day 2 or 3 post‐ovulation increases P4 concentrations for ≥3 day, has no effect on luteal development, but anticipates the beginning of luteolysis in beef cattle.     

Cellular and extracellular vesicular origins of miRNAs within the bovine ovarian follicle

The ovarian follicle components must provide an ideal environment to ensure the success of reproductive processes, and communication between follicular cells is crucial to support proper oocyte growth. Recently, it has been demonstrated that the presence of extracellular vesicles (EVs) carrying microRNAs (miRNAs) in follicular fluid represents an important autocrine and paracrine communication mechanism inside the ovarian follicle. In this study, we tested the hypothesis that the miRNA content of EVs isolated from ovarian follicular (granulosa and cumulus–oocyte complexes) cell‐conditioned culture media is dependent upon cell type. We initially screened bovine granulosa cells (GCs) and cumulus–oocyte complexes (COCs), as well as their derived EVs for 348 miRNAs using real‐time PCR, and detected 326 miRNAs in GCs and COCs cells and 62 miRNAs in GCs and COCs EVs. A bioinformatics analysis of the identified cell‐specific and differentially expressed miRNAs predicted that they likely modulate important cellular processes, including signalling pathways such as the PI3K‐Akt, MAPK and Wnt pathways. By investigating the origins of miRNAs within the follicular fluid, the results of this study provide novel insights into follicular miRNA content and intercellular communication that may be of invaluable use in the context of reproductive technologies, diagnostic of ovarian‐related diseases and/or the identification of biomarkers for oocyte and embryo quality.     

A mathematical model for the adsorption of water vapor by soils

A two-parameter mathematical model based on some physical assumptions was developed for the adsorption of water vapor by soils: W = W _mh[(p/p ₀) − (p/p ₀)³ + (p/p ₀)⁶] + W _res. It was shown that one of the model’s parameters is close to a conventional soil-hydrological constant, namely, the maximum hygroscopic moisture, or maximum hygroscopicity W _mh. The second parameter reflects the residual water content W _res as the content of immobilized water, which is bound to the most active part of the adsorbing surface, is adsorbed at the initial stage of adsorption (0 ≤ p/p ₀ ≤ 0.05), and later does not participate in the adsorption processes. Methods were proposed for the differential calculation of singular points and parameters of the model corresponding to the characteristic physical phenomena of water vapor adsorption in soils. The model was tested for the quantitative assessment of the interaction between the soil solid phase and the water vapor in different soils (a soddy-strongly podzolic soil, an ordinary chernozem, a chestnut soil, and a medium-columnar solonetz). A method was proposed for calculating the integral adsorption energy E _max of the soil solid phase-water vapor interaction. It was shown that the E _max values are determined by the physicochemical properties of the soils and characterize the capacity of the separate soil horizons for adsorbing water vapor. The relationship of the integral adsorption energy of the soils with the relative pressure of the water vapor and the water content was studied.     

Theoretical and experimental substantiation of a thermogravimetric method for assessing the water-retention capacity and specific surface area of disperse systems

A conceptually new instrumental method has been proposed for the determination of the sorption fragment of the soil water retention curve and the specific surface area of soils and sediments by drying samples at different temperatures, which is based on fundamental models for relative air humidity and thermodynamic water potential (Ψ) as functions of temperature (T). The basic equation for the calculation of water potential in the first (linear) approximation is as follows: Ψ = Q–аТ, where Q is the specific heat of evaporation, and a is the physically substantiated parameter related to the initial relative air humidity in the laboratory. The setting of model parameters necessary for quantitative calculations has been performed from tabulated data for the saturated water vapor pressure as a function of temperature and results of an independent experiment with gradual air heating and synchronous automated control of air humidity and temperature with DS 1923 hydrochrons. The potentialities of the method have been demonstrated using literature data on the dehydration of soil colloids and our own results on the drying of a silty sandy soil (Arenosol) from Dubai, a light loamy soddy-podzolic soil (Albic Retisol) and a low-moor peat soil (Histosol) from Moscow oblast, and a loamy ordinary chernozem (Haplic Chernozem) from Krasnodar region.     

Interaction of microbial β-glucuronidase with vegetable pectins

The purpose of this study was to investigate the in vitro effects of vegetable carbohydrates on the activity of microbial β-glucuronidase (βG) and the adsorption of the enzyme on carbohydrates. This study used pectin-protein complexes (PPCs) with molecular weights of 300 kDa isolated under conditions simulating a gastric environment from cabbage (HCl-PPCC and HCl+pepsin-PPCCP) and sweet pepper (PPCP and PPCPP). As a sample for comparison, microcrystalline cellulose was used. The activity of βG from Escherichia coli was determined spectrophotometrically by the formation of the colored product from the breakdown of phenolphthalein-β-D-glucuronide. Adsorption of βG on biopolymers was studied by the retention of the enzyme on the membrane of a concentrator with a pore diameter of 300 kDa and by native PAGE. PPCCP and PPCC were established to increase the activity of βG by 50 and 100%, respectively. Cellulose had a weak effect, whereas pepper PPC had no effect. All studied carbohydrates adsorb on βG. The maximum βG adsorption (15%) was observed with PPCC, whereas PPCCP absorbed 5% of the enzyme. Pepper PPCs and cellulose adsorbed up to 10% of the enzyme. There was a positive correlation between the increase of βG activity in the presence of carbohydrates and enzyme adsorption on the polymers (r=0.80; P<0.01). The activity of the enzyme in the gel after electrophoresis of the PPCC+βG mixture was inversely proportional to the concentration of PPCC in the mixture. A model explaining the effects of cabbage PPCs on the excretion of estrogens is proposed.