A broad spectrum screening of Schmallenberg virus antibodies in wildlife animals in Germany

To identify native wildlife species possibly susceptible to infection with Schmallenberg virus (SBV), a midge-transmitted orthobunyavirus that predominantly infects domestic ruminants, samples from various free-living ruminants, but also carnivores, small mammals and wild boar were analyzed serologically. Before 2011, no SBV-specific antibodies were detectable in any of the tested species, thereafter, a large proportion of the ruminant population became seropositive, while every sample taken from carnivores or small mammals tested negative. Surprisingly, SBV-specific-antibodies were also present in a large number of blood samples from wild boar during the 2011/2012 and 2012/2013 hunting seasons. Hence, free-ranging artiodactyls may play a role as wildlife host.     

Climate and forest management influence nitrogen balance of European beech forests: microbial N transformations and inorganic N net uptake capacity of mycorrhizal roots

The effects of local climate and silvicultural treatment on the inorganic N availability, net N uptake capacity of mycorrhizal beech roots and microbial N conversion were assessed in order to characterise changes in the partitioning of inorganic N between adult beech and soil microorganisms. Fine root dynamics, inorganic N in the soil solution and in soil extracts, nitrate and ammonium uptake kinetics of beech as well as gross ammonification, nitrification and denitrification rates were determined in a beech stand consisting of paired sites that mainly differed in aspect (SW vs. NE) and stand density (controls and thinning treatments). Nitrate was the only inorganic N form detectable in the soil water. Its concentration was high in control plots of the NE aspect, but only in canopy gaps and not influenced by thinning. Neither thinning nor aspect affected the abundance of root tips in the soil. Maximum nitrate net uptake by mycorrhizal fine roots of beech, however, differed with aspect, showing significantly lower values at the SW aspect with warm–dry local climate. There were no clear-cut significant effects of local climate or thinning on microbial N conversion, but a tendency towards higher ammonification and nitrification and lower denitrification rates on the untreated controls of the SW as compared to the NE aspect. Apparently, the observed sensitivity of beech towards reduced soil water availability is at least partially due to impaired N acquisition. This seems to be mainly a consequence of reduced N uptake capacity rather than of limited microbial re-supply of inorganic N or of changed patterns of inorganic N partitioning between soil bacteria and roots.     

Competition modifies effects of enhanced ozone/carbon dioxide concentrations on carbohydrate and biomass accumulation in juvenile Norway spruce and European beech

Elevated concentrations of carbon dioxide ([CO2]) and ozone ([O3]) affect primary metabolism of trees in opposite ways. We studied their potential interactions on carbohydrate concentrations and contents. Two hypotheses currently under debate were tested. (1) Stimulation of primary metabolism by prolonged exposure to elevated [CO2] does not compensate for the adverse effects of O3 on carbohydrate accumulation and biomass partitioning to the root. (2) Growth in a mixed-species planting will repress plant responses to elevated [O3] and [CO2] relative to conditions in a monoculture. To this end, European beech (Fagus sylvatica L.) and Norway spruce (Picea abies (L.) Karst.) saplings grown under conditions of intra- and interspecific competition were pre-acclimated for 1 year to ambient or elevated [CO2]. In the following 2-year phytotron study, trees were exposed to factorial combinations of ambient and elevated [O3] and [CO2]. The total carbohydrate content (sugar and starch) of spruce was greater in plants exposed to elevated [CO2] than in plants exposed to ambient [CO2]. In beech, the opposite response was observed, especially when this species was grown in combination with spruce. Overall, the data did not support Hypothesis 1, because the adverse effects of O3 were counteracted by elevated [CO2]. Support for Hypothesis 2 was species-dependent. In beech saplings, reduction of carbohydrates by elevated [O3] and stimulation by elevated [CO2] were repressed by competitive interaction with spruce. In contrast, in spruce, stimulation of carbohydrates by elevated [CO2] was similar in mono- and mixed cultures. Thus Hypothesis 2 was supported for beech but not spruce. We conclude that, in juvenile beech and spruce, a 3-year exposure to elevated [CO2] counteracts the adverse effects of O3 on carbohydrate concentrations and contents. For beech, sensitivity to elevated [CO2] and [O3] was high in monoculture but was largely repressed by interspecific competition with spruce. In contrast, the response of spruce to perturbations of atmospheric chemistry was not significantly affected by either intra- or interspecific competition.     

Molecular characterization of a collection of the tropical multipurpose shrub legume Flemingia macrophylla

Random amplified polymorphic DNA (RAPD) markers were used for assessing genetic diversity and its structure in a collection of the drought-tolerant, tropical multipurpose shrub legume Flemingia macrophylla (Willd.) Merrill. The species is especially suited to low-input smallholder production systems and is used as dry season forage supplement, live soil cover, mulch and living barrier, among others. Genetic groups identified by RAPD analysis related closely to four morphotypes revealed by multivariate analysis of morphological, agronomic and forage quality characteristics. Overall genetic diversity in the collection was moderate (H _T = 0.241), with 79% differentiation among and high genetic similarity (GS) within groups (0.672–0.965). Results indicate a closer relationship of the semi-erect morphotypes M3 and M4 with F. stricta rather than with the erect morphotype M1. The latter was genetically the most depauperate, followed by morphotypes M2 and M4. New evidence is provided that non-Asian accessions collected in Africa and South America are derived from introduced Southeast Asian material. Furthermore, RAPD data suggest the presence of duplicates in the collection, especially in the overrepresented erect morphotype M1.     

Distribution of essential oils in leaf tissue of an F2 population of Citrus

Summary The identification and distribution of 17 mono- and sesquiterpenes in an F₂ population produced from selfing of an interspecific F₁ hybrid is presented. A mode of inheritance for most of these components is attempted, percentages of leaf oil components and a correlation matrix are given.     

Mid-term tracing of <Superscript>15</Superscript>N derived from urine and dung in soil microbial biomass

Large amounts of C and N are returned to pasture soils by grazing animals in the form of urine and dung. Therefore, a field trial was carried out to investigate the mid-term effects of ¹⁵N-labeled excrements, produced by feeding a cow with ¹⁵N-labeled grass silage, on the soil microbial biomass. Simulating the deposition of excrements, ¹⁵N-labeled urine and dung were applied to a 0.09-m2 area of a sandy pasture soil in October 2000 and 2001. Applied amounts of N were 1,030 and 1,052 kg ha⁻¹, respectively. Soil was sampled at 0–15 cm depth, three times over 7 months and analyzed for total C and N, and microbial biomass C and N. Recovery of urine and dung N in microbial biomass was determined by ¹⁵N analysis of K₂SO₄ extracts of pre-extracted fumigated and unfumigated soils. Under dung patches, microbial biomass C was 16% and 45% higher, and microbial biomass N was 24% and 57% higher than under the untreated soil in 2001 and 2002, respectively. Under urine patches, microbial biomass C was increased after 12 weeks and decreased after 27 weeks. Microbial biomass assimilated 7% to 17% and 10% to 21% of the ¹⁵N applied initially as urine and dung, respectively. These percentages were considerably higher than those for artificially with spiked ¹⁵N urea-created and labeled manures reported in previous experiments. An important reason may be that the naturally ¹⁵N-labeled N components behave differently in soil than urea spikes.     

Simultaneous determination and differentiation of glycidyl esters and 3-monochloropropane-1,2-diol (MCPD) esters in different foodstuffs by GC-MS

The aim of this study was the development of a method for the simultaneous determination and differentiation of fatty acid esters of 3-monochloropropane-1,2-diol (3-MCPD esters) and glycidol (glycidyl esters) in different foodstuffs. The esters were isolated from fat-rich food samples using a single extraction step and separated from interfering substances. For differentiation of 3-MCPD esters and glycidyl esters the glycidol moiety was converted into 3-methoxypropane-1,2-diol (3-MPD) by acidic alcoholysis. Subsequent determination was achieved by isotope dilution GC-MS after transesterification using an isotope-labeled 3-MCPD ester as internal standard. During optimization of the procedure, critical parameters affecting simultaneous determination and differentiation of these analytes were investigated. Rapid ester cleavage and derivatization at ambient temperature proved to be essential for the simultaneous determination of these analytes. The method was validated for various fat-rich foodstuffs such as bakery products, sweets, gravy, and soup powders as well as edible fats and oils. LODs of 8 and 15 μg/kg (fat-rich foodstuffs) as well as 50 and 65 μg/kg (edible oils and fats) were obtained for 3-MCPD esters and glycidyl esters, respectively. Recoveries for 3-MCPD esters and glycidyl esters ranged within 98 ± 4 and 88 ± 2% in all tested foodstuffs (0.05-2.5 mg/kg) and within 99 ± 16 and 93 ± 13% for edible oils and fats (0.15-3 mg/kg) over a wide concentration range. These results proved an accurate and differentiated determination of 3-MCPD esters and glycidyl esters with successful application to the fast screening of samples, avoiding tedious and laborious sample preparation.     

Rhizodeposition: Its contribution to microbial growth and carbon and nitrogen turnover within the rhizosphere

A greenhouse rhizobox experiment was carried out to investigate the fate and turnover of ¹³C‐ and ¹⁵N‐labeled rhizodeposits within a rhizosphere gradient from 0–8 mm distance to the roots of wheat. Rhizosphere soil layers from 0–1, 1–2, 2–3, 3–4, 4–6, and 6–8 mm distance to separated roots were investigated in an incubation experiment (42 d, 15°C) for changes in total C and N and that derived from rhizodeposition in total soil, in soil microbial biomass, and in the 0.05 M K₂SO₄–extractable soil fraction. CO₂‐C respiration in total and that derived from rhizodeposition were measured from the incubated rhizosphere soil samples. Rhizodeposition C was detected in rhizosphere soil up to 4–6 mm distance from the separated roots. Rhizodeposition N was only detected in the rhizosphere soils up to 3–4 mm distance from the roots. Microbial biomass C and N was increased with increasing proximity to the separated roots. Beside ¹³C and ¹⁵N derived from rhizodeposits, unlabeled soil C and N (native SOM) were incorporated into the growing microbial biomass towards the roots, indicating a distinct acceleration of soil organic matter (SOM) decomposition and N immobilization into the growing microbial biomass, even under the competition of plant growth. During the soil incubation, microbial biomass C and N decreased in all samples. Any decrease in microbial biomass C and N in the incubated rhizosphere soil layers is attributed mainly to a decrease of unlabeled (native) C and N, whereas the main portion of previously incorporated rhizodeposition C and N during the plant growth period remained immobilized in the microbial biomass during the incubation. Mineralization of native SOM C and N was enhanced within the entire investigated rhizosphere gradient. The results indicate complex interactions between substrate input derived from rhizodeposition, microbial growth, and accelerated C and N turnover, including the decomposition of native SOM (i.e., rhizosphere priming effects) at a high spatial resolution from the roots.