Identification and quantification of inhibitors for Angiotensin-converting enzyme in hypoallergenic infant milk formulas

The potential of hypoallergenic (HA) infant milk formulas containing hydrolyzed milk proteins as main constituents to inhibit angiotensin-converting enzyme (ACE) in vitro was investigated. Seven commercially available HA products designed for babies up to 4 months showed a potent inhibition of ACE in vitro, with IC 50 values ranging between 3.2 and 68.5 mg of nitrogen/L. For six samples of conventional milk-based infant formulas and three breast milk samples, no inhibition was observed. Inhibitory potential did not correlate with the degree of hydrolysis. Using reversed-phase high-pressure liquid chromatography (RP-HPLC) coupled to electrospray ionization-time of flight-mass spectrometry (ESI-TOF-MS), 15 peptides known to inhibit ACE were identified. Among them, the highly potent ACE inhibitor Ile-Trp (IC 50 = 0.7 microM) was detected and quantified for the first time in the HA samples, representing the most effective ACE-inhibiting peptide that has ever been detected in food items. The overall inhibitory potential of the HA infant milk formulas could partly be explained by Ile-Trp.     

Mid-infrared spectroscopy for topsoil layer identification according to litter type and decompositional stage demonstrated on a large sample set of Austrian forest soils

When forest soils are investigated, the identification of litter and soil layers is a key step. Mid-infrared spectroscopy seems to be promising for this due to its capability to provide fingerprint information. In this study, a large data set of mid-infrared spectra of different forest soils (L, FH and Ah horizons of coniferous, mixed and deciduous forests) was available together with general analyses data (among others organic carbon, total nitrogen and carbonate contents). This set was used for devising models for the identification of different soil layers and to follow the characteristics of different forest types in the different layers. Canonical discriminant functions were calculated using nine mid-infrared bands occurring in both organic layers and mineral soil layers. The discriminant analysis of the topsoil layers showed that aliphatic mid-infrared bands dominated the first function and yielded a clear separation of mineral and organic layers. Further, this analysis reflected the higher chemical diversity in the organic layers visible by a high scattering of the calculated data points. Two tests with two separate data sets showed a reliable and reproducible performance of the model. Separations of forest types were best possible in the organic layers, in which the deciduous forests were separated best from mixed and coniferous forests. Also for these discriminations, aliphatic bands were dominating. Advanced degradation of soil organic matter resulted in small distances of equidistant forest-type group-centers in the 5-10 cm layers of the mineral soils. Dominating molecular moieties in the discriminant functions in these layers were carbonates and aliphatic bands. The applied methodology suggests mid-infrared spectroscopy as an appropriate tool for soil layer identification, allowing for unequivocal discrimination between organic and mineral soil layers. Discriminations of forest types delivered information about dominating mid-infrared bands in the single layers and allowed conclusions about functional groups dominating these differences.     

Small Scale Heterogeneity of Soil Chemical Properties: Effects on Spring Water Chemistry

Previous soil and spring water analyses in small catchments revealed low pH values in the spring water during high discharge events. This paper analyses the potential which small scale heterogeneity of soil acidity may have to explain decreasing spring water pH as a result of high discharge. Soil aggregates were collected from a C‐horizon of a Spodosol in the Fichtelgebirge. Exchangeable cations and soil solution were examined on both samples from the surfaces and the cores of aggregates which were obtained by a mechanical separation procedure. The Reuss‐Johnson soil chemical equilibrium model was used to predict soil and spring water pH values as a function of acidic input and soil air CO₂ concentration in equilibrium with both aggregate fractions. Ranges of acidic input from 160—570 μeq L⁻¹ and soil air CO₂ concentrations from 0.1 to 3 Vol. % were considered. The model predicted spring water pH values from 5.0 to 5.3 for the acidic aggregate surface samples (base saturation = 12.5%) and from 6.8 to 7.2 for the aggregate core samples (base saturation = 32.1%). The results suggest that small scale acidity gradients may expand the range of predictable spring water pH values. However, very low pH values (<5) still need additional explanation.     

Quantification of airborne N‐input in long‐term field experiments and its validation through measurements using 15N isotope dilution

The N‐deposition in Germany is commonly calculated as values of about 20—30 kg/ha·yr. This range is based on the measurements of the nitrate and ammonium nitrogen bulk deposition, which does not include the gaseous N‐deposition and the direct N‐uptake by plants. The calculation of airbone N‐deposition from N‐balances of the Static Fertilization Experiment Bad Lauchstädt came to 50—58 kg/ha·yr. This is consistent with results from other European long‐term experiments. Using the newly developed ¹⁵N‐based ITNI‐system, the total airborne N‐deposition can be determined. For Bad Lauchstädt analogous to results of former measuring periods an annual N‐deposition of 65 kg/ha·yr was measured in 1998, a figure greater than the balanced values. The balanced and measured values show, that airborne N‐deposition is often underestimated and amounts to at least 50 kg/ha·yr, which is a significant burden on natural ecosystems. By taking this extra N‐input into account in calculations for fertilizer recommendations in agriculture a decrease of N‐losses can be achieved which, in turn can also induce a decrease in airborne N‐deposition.     

Asymmetric adsorption of alanine by quartz

Radioactive D- and L-alanine hydrochloride in 10(-5) molar dimethylformamide solution was adsorbed by d- and 1-quartz to the extent of 20 to 30 percent, as shown by radioactivity loss. d-Quartz preferentially adsorbs D-alanine and 1-quartz adsorbs L-alanine. The extent of asymmetric preferential adsorption is about 1.0 to 1.8 percent, at the 99.9 percent confidence level.     

Cross-evaluation of measurements of peatland methane emissions on microform and ecosystem scales using high-resolution landcover classification and source weight modelling

The methane exchange in an oligotrophic mire complex was measured on the ecosystem and microform scale with the eddy covariance (EC) and the closed chamber technique, respectively. Information about the distribution of three distinct microform types in the area of interest and in each 30 min EC flux source area was derived from a high-resolution (1 m²) landcover map in combination with an analytical source weight model (Kormann and Meixner, 2001). The mean weighted coverage of flark, lawn and hummock microforms in the EC source area (0.3% : 57% : 43%) closely mirrors the overall distribution in the area of interest (0.5% : 50.1% : 49.4%), despite great differences in microform coverage between individual 30 min EC source areas. The measured ecosystem flux was fitted to the sum of three microform flux models based on environmental variables and weighted by their fractional coverage in the EC source area. This method resulted in a better representation of the ecosystem flux compared to an approach based on only one flux model for the whole ecosystem (R² = 0.87, RMSE = 0.44 vs. R² = 0.74, RMSE = 0.61, n = 5181) and thus constitutes a successful down-scaling of measured ecosystem scale flux to the microform scale. A comparison of down-scaled and measured microform fluxes reveals a good agreement for lawn microforms and systematic differences for flark and hummock microforms. Reasons for the differences are thought to be the limited resolution of the landcover classification and the systematic underestimation of hummock fluxes by the closed chamber technique. As a result, hummock fluxes derived by down-scaling of EC fluxes are considered to be more dependable than closed chamber fluxes. The seasonal ecosystem methane budget from gap-filled EC measurements was 9.4 ± 0.2 g CH₄ m⁻²; the budget derived from up-scaled microform measurements was 8.0 ± 0.8 g CH₄ m⁻². The lower value of the latter budget is attributed to the underestimation of flark and hummock fluxes by closed chamber measurements and to the microform gap-filling procedure. Generally, estimates from up-scaled microform measurements are found to be less certain than estimates from EC measurements.     

Elevated temperature and water stress accelerate mesocarp cell death and shrivelling, and decouple sensory traits in Shiraz berries

Both water deficit and elevated temperature are likely to accelerate shrivelling in Shiraz berries with consequences for fruit yield and quality. The process of shrivelling is partially related to mesocarp cell death and it has been proposed that enhancement of berry flavour and aroma also correlates with mesocarp cell death. However, the combined effects of water deficit and elevated temperature on berry shrivelling, mesocarp cell death and berry sensory traits are unknown. We tested the hypotheses that (1) the effects of water deficit and elevated temperature on the dynamics of mesocarp cell death and shrivelling are additive, and that (2) faster cell death, as driven by warming and water deficit, negatively contributes to grape sensory balance. Using open-top chambers to elevate day and night temperature, we compared heated vines against controls at ambient temperature. Thermal regimes were factorially combined with two irrigation regimes, fully irrigated and water deficit, during berry ripening. The dynamic of cell death was characterised by a bilinear model with three parameters: the onset of rapid cell death and the rate of cell death before and after the onset of rapid cell death. Statistical comparison of these three parameters indicated that there was not interaction between water and temperature on the dynamics of berry mesocarp cell death. Warming advanced the onset of cell death by ~9 days (P = 0.0002) and water stress increased the rate of cell death in the period post onset (P = 0.0007). Both water stress and elevated temperature increased the proportion of cell death and shrivelling at harvest. An interaction between water deficit and elevated temperature was found whereby the onset of berry net water loss was advanced by elevated temperature under water deficit but not in the fully irrigated treatment. Sensory traits typical of ripened berries were associated with higher cell death; however, warming and water deficit hastened ripening and altered the balance of berry sensory traits.