Functional adaptation of BabA, the H. pylori ABO blood group antigen binding adhesin

Adherence by Helicobacter pylori increases the risk of gastric disease. Here, we report that more than 95% of strains that bind fucosylated blood group antigen bind A, B, and O antigens (generalists), whereas 60% of adherent South American Amerindian strains bind blood group O antigens best (specialists). This specialization coincides with the unique predominance of blood group O in these Amerindians. Strains differed about 1500-fold in binding affinities, and diversifying selection was evident in babA sequences. We propose that cycles of selection for increased and decreased bacterial adherence contribute to babA diversity and that these cycles have led to gradual replacement of generalist binding by specialist binding in blood group O-dominant human populations.     

Simultaneous measurement of soil organic and inorganic carbon: evaluation of a thermal gradient analysis

Purpose

The best method for determining soil organic carbon (SOC) in carbonate-containing samples is still open to debate. The objective of this work was to evaluate a thermal gradient method (ThG), which can determine simultaneously inorganic carbon (SIC) and SOC in a wide range of soil samples.

Materials and methods

The determination of SOC by ThG (SOC_ThG) was compared to the following widespread standard methods: (1) acidification (ACI) as pretreatment and subsequent dry combustion (SOC_ACI) and (2) volumetric quantification of SIC by a calcimeter (CALC) and subtraction of the total carbon content as determined by dry combustion (SOC_CALC). Precision (F test) and bias (t test) were tested on a subset of seven samples (n?=?3). Comparison of the ThG and CALC methods was performed by regression analysis (n?=?76) on samples representing a wide range of SOC (5.5 to 212.0 g kg^?1) and SIC (0 to 59.2 g kg^?1) contents.

Results and discussion

Tests on the replicated subset showed that the precision of ThG was not significantly different from ACI or CALC (F values?<?39, n?=?3) for SOC and SIC measurements. However, SOC_ACI and SOC_CALC contents were systematically and significantly lower compared to SOC_ThG contents. The positive bias for SOC_ThG relative to SOC_CALC contents appeared also in the regression analysis (given numbers?±?standard errors) of the whole data set (y?=?(4.67?±?0.70)?+?(0.99?±?0.01)x, R ²?=?0.99, n?=?76). When performing a regression with carbonate-free samples, the bias between the methods was negative (?2.90?±?0.63, n?=?29) but was positive in the set with carbonate-containing samples (3.95?±?1.41, n?=?47). This observation corroborated the suspicion that the use of acid for carbonate decomposition can lead to an underestimation of SOC.

Conclusions

All methods were suitable for differentiation between SIC and SOC, but the use of acid resulted in lower estimates of SOC contents. When comparing soil samples with different carbonate concentrations, the use of the ThG method is more reliable.     

Der gegenwärtige Stand der Züchtung von Erucasäure-, Linolensäure- und Glucosinolat-Armen Rapssorten

By repeated backcrossing the characteristics for the absence of erucic acid in the oil as well as for a low content of glucosinolates in the meal were introduced into German varieties of winter rapeseed. The desirable genetic progress in respect to the ratio of the polyenoic fatty acids in rapeseed oil appears to be physiologically limited. Sensitive methods for the quantitative determination as well as simple and quick prescreening techniques have been developed for the use in breeding for all these traits.

---

---

Vortrag gehalten auf der gemeinsamen Tagung der Internationalen Vereinigung zur Erforschung der Qualität von Nahrungspflanzen (CIQ) und der Deutschen Gesellschaft für Qualitätsforschung (Pflanzliche Nahrungsmittel) e.V. (DGQ) in Berlin am 5. Oktober 1972.     

New tetromycin derivatives with anti-trypanosomal and protease inhibitory activities

Four new tetromycin derivatives, tetromycins 1-4 and a previously known one, tetromycin B (5) were isolated from Streptomyces axinellae Pol001(T) cultivated from the Mediterranean sponge Axinella polypoides. Structures were assigned using extensive 1D and 2D NMR spectroscopy as well as HRESIMS analysis. The compounds were tested for antiparasitic activities against Leishmania major and Trypanosoma brucei, and for protease inhibition against several cysteine proteases such as falcipain, rhodesain, cathepsin L, cathepsin B, and viral proteases SARS-CoV M(pro), and PL(pro). The compounds showed antiparasitic activities against T. brucei and time-dependent inhibition of cathepsin L-like proteases with K(i) values in the low micromolar range.     

Evaluation of the photo stabilising efficiency of clear coatings comprising organic UV absorbers and mineral UV screeners on wood surfaces

A study of the surface discolouration of clear coated wood during artificial and outdoor weathering and its prevention using clear coatings comprising organic UV absorbers (UVA) and mineral UV screeners was carried out. It was shown that the use of UVA and UV screeners in clear coatings was very effective in reducing photodegradation of the wood surface. Preliminary irradiation trials with Xenon arc light showed that the UV screener TiO₂ led to the least discolouration of the coated wood surface, closely followed by UVA of the hydroxyphenyl-s-triazine class (HPT). The artificial and outdoor weathering trials indicated that UVA of the HPT class stabilised the colour of the wood surface better than UVA of the 2-(2-hydroxyphenyl)-benzotriazole class (BTZ). Comparison of different artificial weathering methods indicated that Xenon arc light weathering showed the best match to the proceeding discolouration of the clear coated wood panels during outdoor weathering.     

Modelling flowering of plants using time-to-event methods

Climate and environmental factors are known to influence the propensity of plants to flower. In order to capture the time dynamics in the underlying biological processes, this paper proposes to use a grouped-data survival analysis methodology. We formulate a semi-parametric model for the hazard rate of flowering, which allows all available climatic and environmental data to be included. Estimation can be carried using a generalized linear model approach. In addition, the model can be validated by means of recently developed residual-based model-checking procedures similar to what is available for ordinary regression models. The main finding is that the model proposed captures the major trends and is a first step in the direction of a model-based quantification of some climatic and environmental factors that influence the flowering of plants.     

Development of high-performance strand boards: multiscale modeling of anisotropic elasticity

The interrelationships between microstructural characteristics and anisotropic elastic properties of strand-based engineered wood products are highly relevant in order to produce custom-designed strand products with tailored properties. A model providing a link between these characteristics and the resulting elastic behavior of the strand products is a very valuable tool to study these relationships. Here, the development, the experimental validation, and several applications of a multiscale model for strand products are presented. In a first homogenization step, the elastic properties of homogeneous strand boards are estimated by means of continuum micromechanics from strand shape, strand orientation, elastic properties of the used raw material, and mean board density. In a second homogenization step, the effective stiffness of multi-layer strand boards is determined by means of lamination theory, where the vertical density profile and different layer assemblies are taken into account. On the whole, this model enables to predict the macroscopic mechanical performance of strand-based panels from microscopic mechanical and morphological characteristics and, thus, constitutes a valuable tool for product development and optimization.     

Zoonotic tick-borne flaviviruses

Tick-borne flaviviruses are among the medically most important arboviruses in Europe and Asia. Tick-borne encephalitis causes between 10,000 and 15,000 human cases every year in both continents. Besides this disease there are several other tick-borne flaviviruses which may be of local medical importance, and which are less known, but may be important as differential diagnosis. Among them are louping-ill disease which is present mainly on the British Islands, Omsk hemorrhagic fever, which is prevalent in parts of Russia, Kyasanur Forest Disease, which is distributed in parts of India, Alkhumra hemorrhagic fever, occurring in Saudi Arabia, Powassan encephalitis, which is known to be the only tick-borne flavivirus of human pathogenicity so far detected in North America and some other flaviviruses. Most of these viruses are also more or less important for veterinary medicine. Several other tick-borne flaviviruses so far have neither been associated with human nor animal diseases, and their potential pathogenicity for humans and animals is unknown. Changes in human behaviour, land use, or climate may change the actual geographical distribution and transmission intensity so that tick-borne flaviviruses are potential winners of the changing environment and may increase in medical and veterinary importance.