Influence of litter chemistry and stoichiometry on glucan depolymerization during decomposition of beech (Fagus sylvatica L.) litter

Glucans like cellulose and starch are a major source of carbon for decomposer food webs, especially during early- and intermediate-stages of decomposition. Litter quality has previously been suggested to notably influence decomposition processes as it determines the decomposability of organic material and the nutrient availability to the decomposer community. To study the impact of chemical and elemental composition of resources on glucan decomposition, a laboratory experiment was carried out using beech (Fagus sylvatica, L.) litter from four different locations in Austria, differing in composition (concentration of starch, cellulose and acid unhydrolyzable residue or AUR fraction) and elemental stoichiometry (C:N:P ratio). Leaf litter was incubated in mesocosms for six months in the laboratory under controlled conditions. To investigate the process of glucan decomposition and its controls, we developed an isotope pool dilution (IPD) assay using (13)C-glucose to label the pool of free glucose in the litter, and subsequently measured the dilution of label over time. This enabled us to calculate gross rates of glucose production through glucan depolymerization, and glucose consumption by the microbial community. In addition, potential activities of extracellular cellulases and ligninases (peroxidases and phenoloxidases) were measured to identify effects of resource chemistry and stoichiometry on microbial enzyme production. Gross rates of glucan depolymerization and glucose consumption were highly correlated, indicating that both processes are co-regulated and intrinsically linked by the microbial demand for C and energy and thereby to resource allocation to enzymes that depolymerize glucans. At early stages of decomposition, glucan depolymerization rates were correlated with starch content, indicating that starch was the primary source for glucose. With progressing litter decomposition, the correlation with starch diminished and glucan depolymerization rates were highly correlated to cellulase activities, suggesting that cellulose was the primary substrate for glucan depolymerization at this stage of decomposition. Litter stoichiometry did not affect glucan depolymerization or glucose consumption rates early in decomposition. At later stages, however, we found significant negative relationships between glucan depolymerization and litter C:N and AUR:N ratio and a positive relationship between glucan depolymerization and litter N concentration. Litter C:N and C:P ratios were negatively related to cellulase, peroxidase and phenoloxidase activities three and six months after incubation, further corroborating the importance of resource stoichiometry for glucan depolymerization after the initial pulse of starch degradation.     

Ralstonia solanacearum as a potato pathogen in Serbia: Characterization of strains and influence on peroxidase activity in tubers

Since 2011, the outbreaks of brown rot caused by Ralstonia solanacearum race 3, biovar 2, phylotype IIB-1 (R3/B2/PIIB-1) have significantly compromised potato production in Serbia. During 6 years of monitoring (2013–2018) among 3,524 potato tuber samples, 344 were found positive for brown rot disease. R. solanacearum R3/B2/PIIB-1 was isolated from seven cultivars among 12 monitored, and in five localities among 17 monitored. Cultivar Lady Claire was found to have the highest disease frequency (31.98%). A total of 78 isolates were identified by R. solanacearum-specific primer pairs (PS-1/PS-2 and OLI-1/Y-2), as well as the following tests: restriction fragment length polymorphism analysis, biovar determination, immunofluorescence, biochemical analysis, and pathogenicity. The genetic composition of 36 selected isolates assessed using multilocus sequence analysis with seven genes (adk, gapA, gdhA, gyrB, ppsA, hrpB, and fliC) showed that all isolates originating from Serbian potato were homogeneous. By using the TCS algorithm of concatenated sequences to get insight into the phylogeography of isolates and other R. solanacearum strains deposited in the NCBI database, we showed that their origin is undetermined. Peroxidase (POD) activity was measured in brown rotted potato tubers. A positive correlation was found between POD activity and disease severity rated on the analysed tubers. In general, POD activity increased by 2–22 times in vascular necrotic tissues compared to non-necrotic ones, and depended on disease severity but not on cultivar. Native polyacrylamide gel electrophoresis analysis of POD profiles resulted in a total of 10 distinct POD isoforms, of which PODs 3–5 were highly intensified in response to R. solanacearum.     

Antimicrobial and free radical scavenging activities of Teucrium montanum

The antimicrobial and free radical scavenging activities of petroleum ether, chloroform, ethyl acetate, n-butanol and water extracts of Teucrium montanum were investigated. Ethyl acetate, chloroform and n-butanol extracts expressed a wide range of inhibiting activity against both Gram (+) and Gram (-) bacteria. n-Butanol extract possessed potent DPPH free radical scavenging activity.     

Stenotic nasopharyngeal dysgenesis in the dachshund: seven cases (2002-2004)

Medical records of seven dachshunds with congenital nasopharyngeal stenosis from abnormally thickened palatopharyngeal muscles were reviewed. The intrapharyngeal ostium in all cases consisted of only a narrow slit. Dogs were presented with various clinical signs--the most common being dyspnea, expiratory cheek puff, salivation, pharyngeal dysphagia, oral dysphagia (to a lesser extent), and macroglossia. Diagnostic procedures included direct pharyngeal inspection, pharyngeal and thoracic radiography, fluoroscopy, lingual ultrasonography, biopsies in two dogs, and a postmortem examination in one dog. Diagnoses were readily made with radiographs and visual examinations. Macroglossia was confirmed with transcutaneous ultrasonography or a transmandibular finger test.     

<Emphasis Type="Italic">Fusarium langsethiae</Emphasis> (Torp and Nirenberg), investigation of alternative infection routes in oats

Fusarium langsethiae is a recently characterized fungus within the genus Fusarium. It is found as a grain contaminant of small grain cereals such as oats and barley, and to a lesser extent wheat. Fusarium langsethiae is particularly widespread in the Nordic countries and the UK where it poses a serious problem as the main producer of T-2 and HT-2 mycotoxins. The biology of F. langsethiae and its interaction with the plant remains poorly understood, partly hampered by difficulties reproducing a natural level of infection under controlled conditions. The reported study was designed as a series of glasshouse experiments to advance our understanding of F. langsethiae biology by investigating alternative infection routes and its proliferation in oats, Avena sativa. Various methods of seed, soil, and seedling inoculation, boot injection and spray inoculation, were tested. The results clearly show a strong preference of F. langsethiae for the panicle, ruling out alternative infection routes. At relatively low temperatures spray infection, accompanied by prolonged humidity, ensured a thorough establishment of the fungus both at flowering and at early dough stage. Boot injection proved to be a reliable working tool for production of an even and predictable grain infection. Apart from in the panicle, considerable fungal proliferation was only detected in flag leaf nodes, and was a direct consequence of the boot injection method. Fungal presence in the node tissue also correlated with significant stunting of infected shoots. In light of the results the pathogenic and endophytic abilities of F. langsethiae are discussed.     

Comparative study of the main top-down approaches for the estimation of measurement uncertainty in multiresidue analysis of pesticides in fruits and vegetables

Practical "top-down" approaches appear to be the most suitable for the evaluation of measurement uncertainty in pesticide residue testing laboratories, where analytical procedures are routinely applied to a large number of pesticide/food combinations. The opposite approach, "bottom-up" evaluation of measurement uncertainty, leads to great difficulties in evaluating all of the pesticides in a consistent way. Among the top-down approaches, there are two main ways in which measurement uncertainty can be estimated: One is based on default values, which are based on previous extensive interlaboratory experience and the proven accuracy of the laboratory; these include the Horwitz equation or the fit-for-purpose relative standard deviation (FFP-RSD). The other is based on experimental data from the quality control work of the laboratory: within-laboratory reproducibility, interlaboratory validation, or a combination of results obtained in proficiency tests. The principal existing guidelines from various bodies (Eurachem, Nordtest, and Eurolab) all propose different approaches for calculating measurement uncertainty. In this paper, the main top-down approaches are evaluated and compared using the data from the European Proficiency Test Database for Fruits and Vegetables and the Multiresidue Method validation databases obtained from the National Reference and Official Laboratories in Europe. The main conclusion of the comparative study is that a default expanded measurement uncertainty value of 50% could satisfy all of the requirements for facilitating and harmonizing, worldwide, the intercomparability of the pesticide residue confidence results between laboratories.     

Gene Localization of Aspartate Aminotransferase and Endopeptidase Isozymes in Wheat and Rye Using Developmental and Organ-Specific Patterns

Wheat, rye and wheat-rye addition lines have been investigated regarding their developmental and organ-specific isozyme patterns of aspartate amino-transferase (AAT) and endopeptidase (EP). Evidence is given, that development-specific isozymes of AAT are encoded by chromosomes 3R and 4R of ‘Imperial’ rye which can be used as biochemical markers up to leaf age of 14 days. Organ-specific increase of intensity of bands for AAT in stems could be assigned to genes or alleles of chromosome 3A of ‘Chinese Spring’ wheat. For EP new markers were localized on chromosomes 4R and 6R of ‘Imperial’ rye showing variability. Utilization of these markers is possible at all developmental stages of the leaves. Mechanisms of gene regulation are discussed.     

Farmer goals and management styles: Implications for advancing biologically based agriculture

This paper examines differences in the management styles of a purposive sample of almond and winegrape growers in California’s Central Valley, including participants and non-participants in biologically integrated farming systems programs. Using Q methodology, we elicited rankings of economic and social values and goals as they relate to farm production, environmental stewardship, family and community, and leisure. These rankings led to three distinct management styles, labeled as Environmental Stewards, Production Maximizers, and Networking Entrepreneurs. The results demonstrate that farmers make decisions following diverse management strategies and suggest that outreach programs aimed at advancing biologically based farming practices must address these differences to be most effective.     

Entwicklung,Eigenschaften und Klassifikation von Dünenböden der Ostfriesischen Inseln – am Beispiel Spiekeroogs

Pedogenesis, properties, and classification of dune soils of the East Frisian Islands (southern North Sea coast of Germany)—exemplified by the island Spiekeroog The aim of this study was a detailed pedological investigation and exact classification of dune soils of the East Frisian Islands. The following soil‐forming processes were identified on a laboratory‐data basis: humus accumulation and dislocation, carbonate loss, acidification, modification of exchangeable cations, and base‐saturation decrease. A slight iron oxide accumulation was visible in the field, but not confirmed by laboratory data. Applying the qualitatively and quantitatively defined horizons from the German classification, these soils cannot be classified as Regosols, Braunerden, and Podsols but they fit perfectly in the Arenosols as defined in the WRB.