Microtomography of partially molten rocks: three-dimensional melt distribution in mantle peridotite

The permeability of the upper mantle controls melt segregation beneath spreading centers. Reconciling contradictory geochemical and geophysical observations at ocean ridges requires a better understanding of transport properties in partially molten rocks. Using x-ray synchrotron microtomography, we obtained three-dimensional data on melt distribution for mantle peridotite with various melt fractions. At melt fractions as low as 0.02, triple junctions along grain edges dominated the melt network; there was no evidence of an abrupt change in the fundamental character of melt extraction as melt fraction increased to 0.2. The porosity of the partially molten region beneath ocean ridges is therefore controlled by a balance between viscous compaction and melting rate, not by a change in melt topology.     

Natural selection favors a newly derived timeless allele in Drosophila melanogaster

Circadian and other natural clock-like endogenous rhythms may have evolved to anticipate regular temporal changes in the environment. We report that a mutation in the circadian clock gene timeless in Drosophila melanogaster has arisen and spread by natural selection relatively recently in Europe. We found that, when introduced into different genetic backgrounds, natural and artificial alleles of the timeless gene affect the incidence of diapause in response to changes in light and temperature. The natural mutant allele alters an important life history trait that may enhance the fly's adaptation to seasonal conditions.     

Influence of milking units and working vacuum level on the mechanical milking of goats

The objectives of this study were to evaluate and compare the effect of working vacuum levels (35 and 44 kPa) and liners dimensions (mouthpiece lip diameter and overall length, 20–185 and 22–170 mm) on the main milking characteristics of goats. The results highlight that both the working vacuum level and the liner dimension have influenced the milk flow curve parameters. The maximum variations were found for peak flow rate, which increased significantly with liner dimensions of 20–185 mm at a working vacuum level of 44 kPa as well as average milk flow rate and for plateau phase duration. The incorrect adoption of operative parameters and unsuitable milking machine components, might affect the performance of the mechanical milking and negatively affecting animal productions and welfare.     

Sorption and degradation of azimsulfuron on iron(III)-rich soil colloids

The sorption of N-[[(4,6-dimethoxypyrimidin-2-yl)amino]carbonyl]-1-methyl-4-(2-methyl-2H-tetrazole-5-yl)1H-pyrazole-5-sulfonamide (AZS) on an iron oxide, iron(III)-humate, and an Fe3+-saturated clay was studied using a batch equilibrium method. Generally, 20 mg of each colloid was equilibrated with 20 mL of AZS solution (1.5-12.7 microM). The sorption on iron-montmorillonite and iron oxide was rapid, and the equilibrium was attained within 1.5 and 5 h, respectively. In the case of Fe-saturated humic acid the equilibrium time was 20 h. After equilibration, the phases were centrifuged (19000g, 15 min) and the supernatant was sampled and analyzed by HPLC. The values of Freundlich constants indicate that iron oxide (Kads = 199.5) shows the highest sorptive capacity toward AZS, followed by iron(III)-clay (Kads = 146.6) and iron(III)-humate (Kads = 108.2). With elapsing time, AZS degradation was observed in all colloidal suspensions. Iron-humate (t(1/2) = 136 h) is most effective in promoting AZS degradation, followed by iron oxide (t(1/2) = 204 h) and iron-clay (t(1/2) = 385 h). The metabolites 2-amino-4,6-dimethoxypyrimidine and 1-methyl-4-(2-methyl-2H-tetrazole-5-yl)-1H-pyrazole-5-sulfonamide, arising from a hydrolytic cleavage of the sulfonylurea bridge, were the only byproducts observed. A Fourier transform infrared study suggests that the sorption of AZS on iron-clay involves the protonation of one of the two basic pyrimidine nitrogens induced by the acidic water surrounding the saturating Fe3+ ions. Instead, the formation of a six-membered chelated complex favors the sorption of AZS on iron oxide.     

Relative quantification of N(epsilon)-(Carboxymethyl)lysine,imidazolone A,and the Amadori product in glycated lysozyme by MALDI-TOF mass spectrometry

The nonenzymatic glycation of proteins by reducing sugars, also known as the Maillard reaction, has received increasing recognition from nutritional science and medical research. In this study, we applied matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) to perform relative and simultaneous quantification of the Amadori product, which is an early glycation product, and of N(epsilon)-(carboxymethyl)lysine and imidazolone A, two important advanced glycation end products. Therefore, native lysozyme was incubated with d-glucose for increasing periods of time (1, 4, 8, and 16 weeks) in phosphate-buffered saline pH 7.8 at 50 degrees C. After enzymatic digestion with endoproteinase Glu-C, the N-terminal peptide fragment (m/z 838; amino acid sequence KVFGRCE) and the C-terminal peptide fragment (m/z 1202; amino acid sequence VQAWIRGCRL) were used for relative quantification of the three Maillard products. Amadori product, N(epsilon)-(carboxymethyl)lysine, and imidazolone A were the main glycation products formed under these conditions. Their formation was dependent on glucose concentration and reaction time. The kinetics were similar to those obtained by competitive ELISA, an established method for quantification of N(epsilon)-(carboxymethyl)lysine and imidazolone A. Inhibition experiments showed that coincubation with N(alpha)-acetylargine suppressed formation of imidazolone A but not of the Amadori product or N(epsilon)-(carboxymethyl)lysine. The presence of N(alpha)-acetyllysine resulted in the inhibition of lysine modifications but in higher concentrations of imidazolone A. o-Phenylenediamine decreased the yield of the Amadori product and completely inhibited the formation of N(epsilon)-(carboxymethyl)lysine and imidazolone A. MALDI-TOF-MS proved to be a new analytical tool for the simultaneous, relative quantification of specific products of the Maillard reaction. For the first time, kinetic data of defined products on specific sites of glycated protein could be measured. This characterizes MALDI-TOF-MS as a valuable method for monitoring the Maillard reaction in the course of food processing.     

Azimsulfuron sorption--desorption on soil

The sorption and desorption of the herbicide azimsulfuron, N-[[(4-dimethoxypyrimidin-2-yl)amino]carbonyl]1-methyl-4-(2-methyl-2H-tetrazole-5-yl)1H-pyrazole-5-sulfonamide, were studied using five soils. Sorption isotherms conformed to the Freundlich equation. It was found that pH is the main factor influencing the sorption and that the sorption on soils was negatively correlated with pH. The highest level of sorption was measured on soils with low pH and high organic carbon content. Moreover, inorganic soil colloids, for example, smectite clay minerals and iron oxides, contributed to the sorption of azimsulfuron. Desorption was hysteretic on soils with high organic and inorganic colloid contents.     

Maillard reaction products inhibit oxidation of human low-density lipoproteins in vitro

Dietary intake of antioxidants has been associated with a reduced risk of cardiovascular diseases, which is very likely caused by their capability of prevent oxidation of low-density lipoproteins (LDL). During food processing and storage, substances with antioxidative properties are formed by Maillard reactions. In this study, the activity of Maillard products to inhibit copper-induced oxidation of human LDL in vitro was investigated. d-Glucose was heated with an equimolar amount of glycine, l-lysine, or l-arginine, for 1 h under reflux. The increase of the antioxidative activity (AOA) of the Maillard mixtures was highly significant compared to the control mixtures. Additionally, two defined Maillard products with amino reductone structure were tested. 3-Hydroxy-4-(morpholino)-3-buten-2-one (1) and amino hexose reductone (2) showed a significant and dose dependent AOA. Compound 1 was about half as active as ascorbic acid, which served as positive control. Thus, it can be concluded that Maillard products, particularly those with amino reductone structure, have the strong potential to inhibit LDL oxidation.     

Adsorption and desorption of triasulfuron by soil

The adsorption and desorption of the herbicide triasulfuron [2-(2-chloroethoxy)-N-[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino]carbonyl]benzenesulfonamide] by three soils, soil organic matter (H(+) and Ca(2+)-saturated), and an amorphous iron oxide were studied. Adsorption isotherms conformed to the Freundlich equation. It was found that pH is the main factor influencing the adsorption in all of the systems. Indeed, the adsorption on soils was negatively correlated with pH. The highest level of adsorption was measured on soils with low pH and high organic carbon content. Moreover, it was found that humic acid is more effective in the adsorption compared with calcium humate (the pH values of the suspensions being 3.5 and 6, respectively). Experiments on amorphous iron oxide confirmed the pH dependence. Desorption was hysteretic on soils having high organic carbon content.