Transmission and storage properties of a tropical loamy sand soil as influenced by organic-based and inorganic fertilizers

Short-term effect of organic and inorganic amendments on soil physical quality (SPQ) is marked when dealing with tropical soils which are naturally exposed to a high risk of water erosion. This study assessed the suitability of Tithonia diversifolia (Mexican Sunflower) when incorporated as green manure (GM) and also composted with poultry manure (PM) and other organic-based and inorganic fertilizers to improve some hydraulic properties of an Alfisol subject to excessive drainage. Treatments applied include fresh T. diversifolia (GM), PM, T. diversifolia composted with PM, organo-mineral fertilizers (OMF), neem fertilizer (NF), inorganic fertilizer (20-10-10 NPK), and control in a randomized complete block design and replicated four times. Soil samples were collected at 0–20 cm depth to determine near steady-state infiltration rates (I_s), sorptivity, transmissivity, saturated hydraulic conductivity (K_s), macroporosity (MacP), microporosity (MicP), air capacity (AC), and relative water capacity (RWC). The I_s rates were significantly (P ≤ 0.05) reduced to optimum range with the addition of the organic fertilizers over very high value (128.7 cm hr^?1) observed for control. Whereas, K_s was enhanced in the order: GM > compost (CP) > NF > inorganic fertilizer > control > organo-mineral fertilizer > PM. Sorptivity and transmissivity were highest in control and inorganic fertilizer plots, indicating that the addition of organic fertilizers lowered these parameters while MacP, MicP, AC, and RWC were generally increased with the addition of organic-based and inorganic fertilizers. Specifically, NF increased MicP by 34% over control. Values for RWC which were within the optimum range (0.60–0.70) were only obtained with NF (0.74), OMF (0.72), NPK (0.70), and GM (0.60). The SPQ parameters assessed in this study were enhanced by the addition of fresh T. diversifolia applied as GM and CP compared to other treatments. Therefore, T. diversifolia usually burned by farmers should instead be incorporated into the soil as manure.     

Occurrence of Odorant Polyfunctional Thiols in Beers Hopped with Different Cultivars. First Evidence of an S-Cysteine Conjugate in Hop ( Humulus lupulus L.)

Forty-one thiols, mainly β-sulfanylalkyl acetates, β-sulfanylalkyl alcohols, and β-sulfanylalkyl carbonyls, were recently evidenced in hop. In a beer hopped with the Tomahawk cultivar, most of them were found at higher levels than expected. The aim of the present work was to investigate the polyfunctional thiols in beers hopped with different varieties. A few thiols proved not to come only from hop (mainly 2-sulfanylethyl acetate, μg/L levels, and 1-sulfanylpentan-3-one and 1-sulfanylpentan-3-ol, ng/L levels, internal standard (IST) equivalents). The thiol profile of Saaz-hopped beer proved similar to that of the reference beer produced without hop. A high level of 3-sulfanyloctan-1-ol emerged as an indicator of the use of Tomahawk hop (140 ng/L, IST equivalents; FD (flavor dilution) = 65536). In both Cascade- and Tomahawk-hopped beers, 3-sulfanylhexan-1-ol and 3-sulfanylheptan-1-ol were smelled at high flavor dilutions, although only for the latter, significant amounts of the unreduced 3-sulfanylheptanal were found in hop. As already claimed for hop authentication, 3-sulfanyl-4-methylpentan-1-ol remains a good marker of Nelson Sauvin-hopped beers (548 ng/L, IST equivalents; FD = 65536), together with 4-sulfanyl-4-methylpentan-2-one (128 ng/L, FD = 4096). As illustrated by the huge production occurring during fermentation, accurate prediction of hop varietal impact requires quantitating thiol adducts in hop. S-3-(1-Hydroxyhexyl)cysteine was evidenced here for the first time in Cascade hop.     

Natural mechanisms for cereal resistance to the accumulation of <Emphasis Type="Italic">Fusarium</Emphasis> trichothecenes

This review describes the naturally occurring mechanisms in cereals that lead to a reduction of Fusarium trichothecene mycotoxin accumulation in grains. A reduction in mycotoxin contamination in grains could also limit fungal infection, as trichothecenes have been reported to act as virulence factors. The mechanisms explaining the low toxin accumulation trait, generally referred to as type V resistance to Fusarium, can be subdivided into two classes. Class 1 includes mechanisms by which the plants chemically transform the trichothecenes, leading to their degradation or detoxification. Among the detoxification strategies, glycosylation of trichothecenes is a natural process already reported in wheat. According to the structure and the toxicity of trichothecenes, two other detoxification processes, acetylation and de-epoxidation, can be expressed, at least in transgenic plants. Class 2 comprises mechanisms that lead to reduced mycotoxin accumulation by inhibition of their biosynthesis through the action of plant endogenous compounds. These include both grain constitutive compounds and compounds induced in response to pathogen infection. There are already many compounds with antioxidant properties, like phenolic compounds, peptides or carotenoids, and with prooxidant properties, like hydrogen peroxide or linoleic acid-derived hydroperoxides, that have been described as ‘modulators’ of mycotoxin biosynthesis. This review addresses for the first time different studies reporting specific in vitro effects of such compounds on the biosynthesis of Fusarium mycotoxins. A better understanding of the natural processes limiting accumulation of trichothecenes in the plant will open the way to the development of novel breeding varieties with reduced ‘mycotoxin risk’.     

Environmental factors at different spatial scales governing soil fauna community patterns in fragmented forests

Spatial and temporal changes in community structure of soil organisms may result from a myriad of processes operating at a hierarchy of spatial scales, from small-scale habitat conditions to species movements among patches and large-sale landscape features. To disentangle the relative importance of spatial and environmental factors at different scales (plot, patch and landscape), we analyzed changes in Collembola community structure along a gradient of forest fragmentation, testing predictions of the Hierarchical Patch Dynamics Paradigm (HPDP) in different European biogeographic regions (Boreal, Continental, Atlantic, Mediterranean, Alpine). Using variance partitioning methods, based on partial CCAs, we observed that the independent effect of environmental processes was significantly explaining Collembola community variance in all regions, while the relative effect of spatial variables was not significant, due to the observed high levels of landscape heterogeneity along the gradient. Environmental factors at the patch and plot scales were generally significant and explained the larger part of community changes. Landscape variables were not significant across all study sites. Yet, at the landscape level, an increase in forest habitat and proximity of forest patches were showed to have an indirect influence on local community changes, by influencing microhabitat heterogeneity at lower spatial scales in all studied regions. In line with HPDP, large-scale landscape features influenced spatio-temporal changes in soil fauna communities by constraining small-scale environmental processes. In turn, these provided mechanistic understanding for diversity patterns operating at the patch scale, via shifts in community weighted mean of Collembola life-forms occurring in local communities along the fragmentation gradient.     

Screening for methicillin-resistant staphylococci in dogs admitted to a veterinary teaching hospital

This study investigated the nasal carriage of methicillin-resistant staphylococci (MRS) in dogs (n=177) prior to medical examination or surgery in a veterinary teaching hospital. Nasal swab samples were collected after induction of anaesthesia and incubated overnight in salt enriched trypticase-soy broth. Cultures were analysed on two different agar media containing cefoxitin. Suspected MRS isolates were genotypically identified and characterised by antimicrobial susceptibility testing and staphylococcal cassette chromosome mec (SCCmec)-typing. Methicillin-resistant Staphylococcus aureus (MRSA) isolates were additionally characterised by spa-typing and multilocus sequence typing. The presence of Panton-Valentine leukocidin (pvl) genes was determined by PCR. MRS carriage was compared between animals with or without an infectious process. Two MRSA were isolated, both belonging to typical Belgian human hospital clones and lacking pvl. Additionally a methicillin-resistant Staphylococcus haemolyticus carrying a type V SCCmec was detected. No relationship was observed between MRS carriage and presence of infections. The results suggest that MRS are present in dogs originating from the community, albeit at a low prevalence. This could pose risks for cross contamination of dogs and their owners.     

Photosynthesis limitations of grapevine after treatment with the fungicide fludioxonil

The aim of this work was to determine the major limitations to photosynthesis induced by the fungicide fludioxonil (fdx) on nontarget grapevines using cutting as a model. The fdx treatments (1.2, 6, and 30 mM) induced a net photosynthetic rate ( P n) decrease without changes in stomatal conductance, suggesting a nonstomatal limitation. Fdx effects on P n were related neither to photosynthetic capacity alteration in leaves nor to loss in PSII activity. The mechanism underlying photosynthesis reduction differed according to the concentration. Fdx at 6 mM led to an increase of light requirement for photosynthesis while 30 mM fdx induced an increase in the respiration rate in the light. P n decrease after 1.2 mM fdx could rather be related to wetness caused by the spraying than to fungicide toxicity. P n recovered 10 days after treatment, meaning that fdx had little deleterious effect on plant physiology or that grapevine has a great capacity to overcome this temporary stress.     

Improvements required for the detection of Salmonella Pullorum and Gallinarum

Detection of the specific Salmonella serovar Gallinarum, which is divided into the biovars Pullorum and Gallinarum, is compulsory under the national hygienic and sanitary control regulations of France for breeding flocks whose offspring are exported. Our aim was to examine the suitability of bacteriologic and serologic methods routinely used in France to screen serum samples and organs for S. Gallinarum. Since bacteriologic reference techniques are designed to isolate the commonly occurring non-typhoid serovars, such as S. Typhimurium, S. Enteritidis, and others that cause outbreaks of foodborne illness, they may not be particularly suitable for detecting S. Pullorum and S. Gallinarum. This hypothesis was confirmed by the inoculation of 10-wk-old chickens and 1-d-old chicks with various strains of S. Pullorum and S. Gallinarum. The most reliable enrichment media were selenite cystine and Rappaport-Vassiliadis broths. Moreover, on the usual plating media, colonies were small, grew more slowly than the common serovars (in 48 h instead of 24 h), and had an unusual appearance. Since the rapid slide agglutination (RSA) test is based only on antigens from standard and variant strains of S. Pullorum, it may not readily detect S. Gallinarum. In our study, it detected infection in all 10-wk-old chickens inoculated with S. Pullorum strains but did not detect any antibodies against S. Gallinarum. Therefore, S. Gallinarum antigens must be added to the S. Pullorum antigens used in the RSA test in order to detect antibodies produced by birds infected with either biovar.     

In vitro antimicrobial activity of orbifloxacin against Staphylococcus intermedius isolates from canine skin and ear infections

The objective of the study was to evaluate the in vitro activity of orbifloxacin against Staphylococcus intermedius strains isolated in France from canine skin and ear infections. The minimum inhibitory concentrations (MICs) of orbifloxacin against 240 field S. intermedius isolates (69 skin and 171 ear isolates) ranged from 0.016 to 8 mg l(-1), with MIC50 and MIC90 equal to 0.5 and 1 mg l(-1), respectively. Only one strain, a pyoderma isolate was resistant (MIC=8 mg l(-1)). Orbifloxacin was tested at different concentrations for killing rate against five isolates obtained from pyoderma cases and against a reference strain (Staphylococcus aureus ATCC 29213). Orbifloxacin expressed a concentration-dependent bactericidal activity against the S. aureus reference strain, but a time-dependent bactericidal activity against S. intermedius. Orbifloxacin induced bactericidal effect against the S. intermedius strains tested with concentrations equal to or two times MIC.