Impact odorants contributing to the fungus type aroma from grape berries contaminated by powdery mildew (Uncinula necator); incidence of enzymatic activities of the yeast Saccharomyces cerevisiae

Powdery mildew due to the fungus Uncinula necator is an important disease for the vineyard. The development of the fungus at the surface of the berries leads to the occurrence of a very characteristic and sometimes intense mushroom-type odor cited as an important default for grapes quality. Gas chromatography/olfactometry, gas chromatography, and multidimensional gas chromatogaphy/mass spectrometry techniques were used to investigate the most important odorants of grapes diseased by powdery mildew. Among 22 odorants detected, strongly odorant compounds were identified or tentatively identified in purified extracts obtained from grapes diseased by powdery mildew. Aroma extraction dilution analysis (AEDA) analysis revealed that 1-octen-3-one (mushroom odor), (Z)-1,5-octadien-3-one (geranium-leaf odor), and an unidentified odorous zone (fishy-mushroom like odor) were the most potent volatiles of the diseased grapes. In the presence of nonproliferating Saccharomyces cerevisiae yeast cells, and consequently during alcoholic fermentation, the enzymatic reduction of 1-octen-3-one and (Z)-1,5-octadien-3-one to much less odorant compounds, namely 3-octanone and (Z)-5-octen-3-one, was shown. Those results explain to some extent the disappearance of the fungal aroma specific to powdery mildew grapes during alcoholic fermentation.     

Alginate and chitosan functionalization for micronutrient encapsulation

A new method for encapsulation of micronutrients was successfully developed. The encapsulation matrix consisted of two polymers (alginate and chitosan), which were functionalized by acylation with palmitoyl chloride. The structural modifications of polymers were confirmed by Fourier transform infrared (FTIR) spectroscopy. Beads were formed by ionic gelation, and their mechanical and physical characteristics (puncture strength and deformation, viscoelasticity, water vapor permeability, and rate of gel swelling) were evaluated using beads or films made of bead-forming solutions. Functionalization increased elasticity and water impermeability of polymer films. Stability of selected encapsulated micronutrients (ferrous fumarate, ascorbic acid, and beta-carotene) was also evaluated under two levels of temperature (23 and 45 degrees C) and relative humidity (56 and 100%) for 6 months. Encapsulation strongly increased the stability of micronutrients. No difference was observed in the encapsulated micronutrients' stability between nonfunctionalized and functionalized beads. Finally, a release study in gastrointestinal media was conducted. Results showed that beads were not susceptible to enzymatic and acidic attacks during stomach transit. This research demonstrates the potential of a new encapsulation method to protect bioactive molecules from temperature, moisture, and acidic conditions.     

Monitoring fish stocks in relation to acidification in Norwegian watersheds

The Norwegian Monitoring Programme for Long-Range Transported Air Pollutants started in 1980. The biological part of this programme includes besides invertebrate studies in streams, (i) fish community status in lakes by means of interviews, test-fishing in lakes by using standard gill-net series, recruitment studies of brown trout in inland streams, and juvenile stock assess and monitoring of fish kills in salmon rivers. Damaged fish stocks are recognized within a land area of 51,500 km² in southern Norway and 30 km² in northern Norway. At least 6,000 lake-dwelling fish stocks have either been lost or are at various stages of reduction. Brown trout (Salmo trutta) is the most widespread and abundant species of fish in Norwegian watersheds, and is also most severe affected by acidification. More recently, there are some indications of an increase in the abundance of brown trout in some areas. However, analysis of age structure in lakes, and fry densities in streams in such areas revealed large annual variations in recruitment rate, which indicates unstable water chemical conditions. Atlantic salmon (Salmo salar) is virtually extinct in 25 rivers in southernmost, southwestern and western Norway.     

Quantitative determination and structure elucidation of type A- and B-trichothecenes by HPLC/ion trap multiple mass spectrometry.

A method is presented for the quantification and structure confirmation of trichothecenes in wheat by high-performance liquid chromatography combined with multiple mass spectrometry (MS(n)()). Nine type A- and B-trichothecenes were determined (nivalenol, deoxynivalenol, fusarenon-X, 3-acetyldeoxynivalenol, 15-acetyldeoxynivalenol, neosolaniol, diacetoxyscirpenol, HT-2 toxin, and T-2 toxin). Extraction was carried out with acetonitrile/water. The extract was purified on a MycoSep column. Quantification was based on an internal standard and atmospheric pressure chemical ionization in the positive ion mode. Recoveries from spiked wheat were in the range of 80-106% at levels of 500 ppb. The limits of quantification for the whole method were between 10 and 100 ppb. Ion adduct formation with ammonium and acetate ions and MS(n) experiments provided information about substitution and fragmentation behavior of the mycotoxins. A scheme has been established for the partial structure elucidation of type A- and B-trichothecenes in fungal cultures.     

Indirect host effect on ectomycorrhizal fungi: Leaf fall and litter quality explain changes in fungal communities on the roots of co-occurring Mediterranean oaks

Host trees can modify their soil abiotic conditions through their leaf fall quality which in turn may influence the ectomycorrhizal (ECM) fungal community composition. We investigated this indirect interaction using a causal modelling approach. We identified ECM fungi on the roots of two coexisting oak species growing in two forests in southern Spain - Quercus suber (evergreen) and Quercus canariensis (winter deciduous)-using a PCR-based molecular method. We also analysed the leaf fall, litter and soil sampled beneath the tree canopies to determine the concentrations of key nutrients. The total mycorrhizal pool was comprised of 69 operational taxonomic units (OTUs). Tomentella and Russula were the most species-rich, frequent and abundant genera. ECM fungi with epigeous and resupinate fruiting bodies were found in 60% and 34% of the identified mycorrhizas, respectively. The calcium content of litter, which was significantly higher beneath the winter-deciduous oak species due to differences in leaf fall quality, was the most important variable for explaining ECM species distribution. The evaluation of alternative causal models by the d-sep method revealed that only those considering indirect leaf fall-mediated host effects statistically matched the observed covariation patterns between host, environment (litter, topsoil, subsoil) and fungal community variables.     

Carbon dioxide emissions of soils under pure and mixed stands of beech and spruce, affected by decomposing foliage litter mixtures

Soil respiration is the largest terrestrial source of CO₂ to the atmosphere. In forests, roughly half of the soil respiration is autotrophic (mainly root respiration) while the remainder is heterotrophic, originating from decomposition of soil organic matter. Decomposition is an important process for cycling of nutrients in forest ecosystems. Hence, tree species induced changes may have a great impact on atmospheric CO₂ concentrations. Since studies on the combined effects of beech-spruce mixtures are very rare, we firstly measured CO₂ emission rates in three adjacent stands of pure spruce (Picea abies), mixed spruce-beech and pure beech (Fagus sylvatica) on three base-rich sites (Flysch) and three base-poor sites (Molasse; yielding a total of 18 stands) during two summer periods using the closed chamber method. CO₂ emissions were higher on the well-aerated sandy soils on Molasse than on the clayey soils on Flysch, characterized by frequent water logging. Mean CO₂ effluxes increased from spruce (41) over the mixed (55) to the beech (59) stands on Molasse, while tree species effects were lower on Flysch (30-35, mixed > beech = spruce; all data in mg CO₂-C m⁻² h⁻¹). Secondly, we studied decomposition after fourfold litter manipulations at the 6 mixed species stands: the O_i - and O_e horizons were removed and replaced by additions of beech -, spruce - and mixed litter of the adjacent pure stands of known chemical quality and one zero addition (blank) in open rings (20 cm inner diameter), which were covered with meshes to exclude fresh litter fall. Mass loss within two years amounted to 61-68% on Flysch and 36-44% on Molasse, indicating non-additive mixed species effects (mixed litter showed highest mass loss). However, base cation release showed a linear response, increasing from the spruce - over the mixed - to the beech litter. The differences in N release (immobilization) resulted in a characteristic converging trend in C/N ratios for all litter compositions on both bedrocks during decomposition. In the summers 2006 and 2007 we measured CO₂ efflux from these manipulated areas (a closed chamber fits exactly over such a ring) as field indicator of the microbial activity. Net fluxes (subtracting the so-called blank values) are considered an indicator of litter induced changes only and increased on both bedrocks from the spruce - over the mixed - to the beech litter. According to these measurements, decomposing litter contributed between 22-32% (Flysch) and 11-28% (Molasse) to total soil respiration, strengthening its role within the global carbon cycle.     

Detailed physicochemical characterization of the 2S storage protein from rape (Brassica napus L.)

Chromatographic, chemical, and spectroscopic techniques were used to characterize the physicochemical properties of napin purified by preparative chromatography. The molar extinction coefficient was determined (epsilon = 0.56), and static and dynamic light scattering measurements enabled the average molecular weight (M(w) = 13919), the second virial coefficient (A(2) = 23.95 x 10(-)(5) mol cm(3) g(-)(2)), and the hydrodynamic radius (R(H) = 1.98 nm) to be determined. No conformational changes were observed by fluorescence and circular dichroism measurements in different buffers at pH 3, 4.6, 7, and 12, confirming the high pH stability of this protein. From MALDI-TOF analysis and after enzymatic digestion, it was found that this purified sample, extracted from the rapeseed variety Express, contained mainly isoform 2SS3_BRANA.     

The influence of basic aerosols on throughfall fluxes of sulfate,ammonium and nitrate in three oak stands along a distance gradient from a lime quarry

Three oak stands (Quercus petraea and Quercus robur) in the Weinviertel, Lower Austria, located along a distance gradient from a lime quarry, were studied to determine the effects of basic aerosols on the deposition of ammonium, nitrate and sulfate. Higher concentrations of limestone aerosols in the vicinity of the quarry are suggested by higher Ca²⁺ fluxes and pH in throughfall and precipitation. The ammonium/nitrate ratio in throughfall decreases with distance from the quarry, though monitoring of NH₃ and NO₂ concentrations in the air with passive samplers shows the opposite trend. These findings support the theory of discrimination against NH₃ in dry deposition due to the presence of Ca ²⁺ particles on leaf surfaces resulting from limestone aerosols. Higher sulfate deposition near the quarry is consistent with higher atmospheric SO₂ concentrations and co-deposition between calcium and sulfate.     

Biological activity of peanut (Arachis hypogaea) phytoalexins and selected natural and synthetic Stilbenoids

The peanut plant (Arachis hypogaea L.), when infected by a microbial pathogen, is capable of producing stilbene-derived compounds that are considered antifungal phytoalexins. In addition, the potential health benefits of other stilbenoids from peanuts, including resveratrol and pterostilbene, have been acknowledged by several investigators. Despite considerable progress in peanut research, relatively little is known about the biological activity of the stilbenoid phytoalexins. This study investigated the activities of some of these compounds in a broad spectrum of biological assays. Since peanut stilbenoids appear to play roles in plant defense mechanisms, they were evaluated for their effects on economically important plant pathogenic fungi of the genera Colletotrichum, Botrytis, Fusarium, and Phomopsis. We further investigated these peanut phytoalexins, together with some related natural and synthetic stilbenoids (a total of 24 compounds) in a panel of bioassays to determine their anti-inflammatory, cytotoxic, and antioxidant activities in mammalian cells. Several of these compounds were also evaluated as mammalian opioid receptor competitive antagonists. Assays for adult mosquito and larvae toxicity were also performed. The results of these studies reveal that peanut stilbenoids, as well as related natural and synthetic stilbene derivatives, display a diverse range of biological activities.