Environmental effects on soil NO concentrations and root N uptake in beech and spruce forests

This study aimed to investigate the shifts in net nitrogen (N) uptake and N compounds of fine roots over the vegetation period (i.e., spring, summer, autumn) and correlate this with NO concentration in the soil. Soil NO concentration was measured using gas lysimeters for collection and a chemiluminescence analyzer for quantification. Net N uptake by the roots was determined using the ¹⁵N enrichment technique. N pools were quantified using spectrophotometric techniques. Soil NO concentrations at beech and spruce forest sites were highest in spring (June), and lowest in winter (December). Total N of the roots was similar during the seasons and between the two years under study despite considerable variation of different N compounds. Net N uptake generally increased with higher N supply. Correlation analysis revealed a positive relationship between soil NO concentration and net N uptake only for spruce trees. This relationship seemed to be modulated by environmental factors and tree species.     

Relation between soil organic matter and yield levels of nonlegume crops in organic and conventional farming systems

The aim of this study was to evaluate the interaction between yield levels of nonleguminous crops and soil organic matter (SOM) under the specific conditions of organic and conventional farming, respectively, and to identify implications for SOM management in arable farming considering the farming system (organic vs. conventional). For that purpose, correlations between yield levels of nonlegume crops and actual SOM level (C_org, N_t, C_hwe, N_hwe) as well as SOM‐level development were examined including primary data from selected treatments of seven long‐term field experiments in Germany and Switzerland. Yield levels of nonlegume crops were positively correlated with SOM levels, but the correlation was significant only under conditions of organic farming, and not with conventional farming treatments. While absolute SOM levels had a positive impact on yield levels of nonlegumes, the yield levels of nonlegumes and SOM‐level development over time correlated negatively. Due to an increased demand of N from SOM mineralization, higher yield levels of nonlegumes obviously indicate an increased demand for OM supply to maintain SOM levels. Since this observation is highly significant for farming without mineral‐N fertilization but not for farming with such fertilization, we conclude that the demand of SOM‐level maintenance or enhancement and thus adequate SOM management is highly relevant for crop production in organic farming both from an agronomical and ecological point of view. Under conventional management, the agronomic relevance of SOM with regard to nutrient supply is much lower than under organic management. However, it has to be considered that we excluded other possible benefits of SOM in our survey that may be highly relevant for conventional farming as well.     

Microbial community structure in forest soils treated with a fire retardant

The influence of a fire retardant (Firesorb, an acrylic–acrylamide copolymer) on the microbial community structure determined by phospholipid fatty acid (PLFA) analysis was examined under laboratory conditions using two different textured soils under pine forest. Firesorb was added to unheated and heated soil samples (350°C for 10 min followed by reinoculation, to mimic a forest fire) at three levels of application (none, usual and three times the usual levels), and measurements were made after 12 weeks of incubation. The relative importance of the three factors considered on the PLFA profiles was as follows: soil heating ≫ soil texture ≈ Firesorb treatment. In the unheated soils, Firesorb had a larger effect than soil texture, while the opposite was found in the heated soils. Soil heating reduced the total PLFAs, while Firesorb tended to increase them in both the unheated and heated soils. Soil heating decreased the PLFAs indicative of gram-positive (G⁺) bacteria and tended to increase the fatty acids associated with gram-negative (G⁻) bacteria and, to a lesser extent, the PLFA 18:2ω6, considered to be predominantly of fungal origin. Firesorb treatment decreased the G⁻/G⁺ bacteria ratio in the heated soils but tended to increase it in the unheated soils, the effect being dose dependent.     

Optimization of a pilot-scale process for producing lupin protein isolates with valuable technological properties and minimum thermal damage

This paper describes a pilot process for obtaining protein isolates from white lupin seed with improved water solubility and technofunctional properties as well as reduced thermal damage. After a careful optimization of the process parameters, two valuable food ingredients were prepared: lupin protein isolate type E, with a useful emulsifying capacity, and lupin protein isolate type F, with a high capability of foam formation and stabilization. The spray-drying process was particularly critical for inducing some thermal damage, but a careful selection of the conditions permitted ingredients having only marginally impaired lysine bioavailability to be obtained. The reproducibility of the protein extraction process was tested on two different lupin varieties.     

Influence of mycotoxin producing fungi (Fusarium, Aspergillus, Penicillium) on gluten proteins during suboptimal storage of wheat after harvest and competitive interactions between field and storage fungi

Cereals contaminated by Aspergillus spp., Penicillium spp., and Fusarium spp. and their mycotoxins, for example, ochratoxin A (OTA) and deoxynivalenol (DON), are not only a risk to human and animal health but can also show poor technological properties and baking quality. The influence of these genera on the sulfur speciation of low molecular weight (LMW) subunits of glutenin was characterized by investigating suboptimally stored wheat samples in situ by X-ray absorption near edge structure (XANES) spectroscopy and baking tests. Field fungi of the genus Fusarium have hardly any influence on both the sulfur speciation of wheat gluten proteins and the baking properties, whereas storage fungi of the genera Aspergillus and Penicillium have a direct influence. An increased amount of sulfur in sulfonic acid state was found, which is not available for thiol/disulfide exchange reactions in the gluten network, and thus leads to a considerably reduced baking volume. From changes of the composition of the mould flora during suboptimal storage of wheat and from the mycotoxin contents, it can be concluded that microbial competitive interactions play an important role in the development of the mould flora and the mycotoxin concentrations during (suboptimal) storage of wheat.     

Comparison of the bioavailability of natural palm oil carotenoids and synthetic beta-carotene in humans

Palm oil carotenoids are a mixture of alpha- and beta-carotenes, which are used as food colorants. They may also be applied as a functional food ingredient because of the provitamin A activity of alpha- and beta-carotenes and their proposed beneficial roles in the prevention of chronic diseases. This paper discusses the results of an incomplete balanced crossover study with 69 healthy adult volunteers to compare palm oil carotenoids with synthetic beta-carotene in their efficacies to increase plasma levels of carotenoids. Four days of supplementation with natural palm oil carotenoids (7.6 mg/day of alpha-carotene, 11.9 mg/day of all-trans-beta-carotene, 7.5 mg/day of cis-beta-carotene) or synthetic beta-carotene (23.8 mg/day of all-trans-beta-carotene, 4.4 mg/day of cis-beta-carotene), added to a mixed meal, resulted in significant increases in plasma levels of the supplied carotenoids as compared to consumption of a low-carotenoid meal (i.e., 7.2-fold increase in alpha-carotene and 3.5-fold increase in all-trans-beta-carotene following palm oil carotenoids; 6.9-fold increase in all-trans beta-carotene following synthetic beta-carotene). As the carotenoid content differed between the treatments, the relative plasma responses were calculated per milligram of beta-carotene intake. These were similar for the two supplements, suggesting that the presence of alpha-carotene does not affect the bioavailability of beta-carotene from palm oil. It was concluded that 4 days of supplementation with palm oil carotenoids or synthetic beta-carotene improves the plasma beta-carotene status substantially, whereas alpha-carotene is additionally delivered by the palm oil supplement.     

Nitrogen and phosphorus use in maize sole cropping and maize/cowpea mixed cropping systems on an Alfisol in the northern Guinea Savanna of Ghana

Summary The use of N and P by mixed and by sole cropping (crop rotation) of maize and cowpeas were compared in a field experiment on an Alfisol at the Nyankpala Agricultural Experiment Station in the northern Guinea Savanna of Ghana, using two levels of N (0 and 80 kg N ha^-1 year^-1 as urea) and P application (0 and 60 kg P ha^-1 year^-1 as Volta phosphate rock). Maize grain yields were significantly reduced in the mixed cropping system. This yield difference became smaller with the application of N and P fertilizer. The N and P concentrations in maize ear leaves at silking indicated that a deficiency in N and P contributed to the maize yield depression in mixed cropping. Competition for soil and fertilizer N between maize and cowpeas was suggested by: (1) A similarity in total N uptake between the two cropping systems; (2) efficient use of soil nitrate by the cowpeas; and (3) low N₂ fixation by the cowpeas, calculated with the aid of an extended-difference method. In general, N₂ fixation was low, with the highest values in the sole cropping (53 kg ha^-1) and a substantial reduction in the mixed cropping system. The application of N fertilizer further reduced N₂ fixation. This was substantiated by nodule counts. The lower N₂ fixation in the mixed cropping system was only partly explained by the lower density of cowpeas in this system. In addition, dry spells during the cropping season and shading by the maize component could have reduced the nodulation efficiency. No N transfer from the legume/rhizobium to the non-legume crop was observed. Impaired P nutrition in the mixed compared with the sole-cropped maize might have been due to less P mobility in the soil. This was indicated by lower soil moisture contents in the topsoil under mixed cropping, especially during the dry year of 1986. The results show that mixed cropping of maize and cowpeas did not lead to improved use of soil and fertilizer N and P or to an enhanced N₂ fixation. On the contrary, an annual rotation of maize and cowpeas was clearly superior.     

Remediation of Soils Contaminated with Molybdenum using Soil Amendments and Phytoremediation

For ruminants, there is a narrow span betweennutritional deficiency of Molybdenum and its potential toxicity. Molybdenosis occurs among cattlefeeding on forage with Mo concentrations above10 μg g^-1 or a Cu:Mo ratio <2. In the areaunder investigation forage Mo contents in the valleyare as high as 180 μg g^-1 due to industrialpollution, while the alpine pastures, where cattlegraze during summer, are nutrient (e.g. Cu) deficient.When driven to the valley pastures in fall, animalsoften fell ill with molybdenosis, and several died.The aim of the study was to remediate this 300 ha area. Two approaches were attempted: (1) to reduce theMo contents of the forage by immobilizing soil Mo, and(2) to increase plant Mo contents by mobilizing soilMo to increase plant Mo which may then be removed fromthe system (phytoremediation).In a soil extraction experiment we demonstrated thatphosphate fertilization, ammonium sulfate amendment,vermiculite, humic acid and sewage sludge increased Moleaching by 30 to 110%. Fe-humate and Mn-humateapplication decreased Mo in the leachate from96 μg L^-1 to 55 and 7 μg L^-1,respectively. Plant Mo contents were increased up to170% by P-fertilizer and up to 150% by vermiculite.Conversely, sewage sludge, Fe- and Mn-humate decreasedplant Mo contents by 60, 40 and 75% in thegreenhouse. In the field study, the effects weresmaller, but Mo export through plant harvest increasedby 88% after P-fertilization and 84% aftervermiculite amendment. Mn-humate and sewage sludgedecreased plant Mo content by 25 and 40%,respectively, rendering the forage suitable forfeeding of ruminants. P-fertilization and vermiculitemay thus be recommended for the severely contaminatedsites to enhance phytoremediation through Mo export,and Mn-humate and sewage sludge application appearsuited to remediate the less severely contaminated sites.     

CD46 in meningococcal disease

The human-specific bacterial pathogen Neisseria meningitidis is a major cause of sepsis and/or meningitis. The pili of N. meningitidis interact with CD46, a human cell-surface protein involved in regulation of complement activation. Transgenic mice expressing human CD46 were susceptible to meningococcal disease, because bacteria crossed the blood-brain barrier in these mice. Development of disease was more efficient with piliated bacteria after intranasal, but not intraperitoneal, challenge of CD46 transgenic mice, suggesting that human CD46 facilitates pilus-dependent interactions at the epithelial mucosa. Hence, the human CD46 transgenic mice model is a potentially useful tool for studying pathogenesis and for vaccine development against meningococcal disease.     

Role of adenine nucleotide translocator 1 in mtDNA maintenance

Autosomal dominant progressive external ophthalmoplegia is a rare human disease that shows a Mendelian inheritance pattern, but is characterized by large-scale mitochondrial DNA (mtDNA) deletions. We have identified two heterozygous missense mutations in the nuclear gene encoding the heart/skeletal muscle isoform of the adenine nucleotide translocator (ANT1) in five families and one sporadic patient. The familial mutation substitutes a proline for a highly conserved alanine at position 114 in the ANT1 protein. The analogous mutation in yeast caused a respiratory defect. These results indicate that ANT has a role in mtDNA maintenance and that a mitochondrial disease can be caused by a dominant mechanism.