Assessment of performance of selected serological tests for diagnosing brucellosis in pigs

Swine brucellosis due to Brucella suis is considered an emerging zoonotic disease whose control is based on serological testing and the subsequent culling of seropositive animals or the full depopulation of affected flocks. Here we assessed the performance of several serological tests (Rose Bengal Test [RBT], indirect ELISA [i-ELISA], blocking ELISA [b-ELISA], and two competitive ELISAs [c-ELISA]) for diagnosing swine brucellosis caused by B. suis biovar 2. Both frequentistic and Bayesian statistical inference were used. A frequentistic analysis, using sera from known gold standard (GS) populations (i.e., from truly infected or brucellosis free animals), resulted in maximum (100%) diagnostic sensitivity (Se) and specificity (Sp) in the RBT, i-ELISA and b-ELISA tests. However, c-ELISAs resulted in lower diagnostic Se (ranging from 68.5% to 92.6%, according to the different cut-offs selected). A Bayesian analysis of tests yielding the best diagnostic performance with GS sera (RBT, i-ELISA and b-ELISA), but using a large collection of field sera, resulted in similar Se among tests but markedly lower (≈ 80%) than that resulting from the frequentistic analysis using the GS serum populations. By contrast, the estimated Sp in the Bayesian analysis was only slightly lower than 100%, thus similar to that obtained frequentistically. Our results show that adequate diagnostic tests for brucellosis in swine are available, but also emphasize the need for more extensive validation studies before applying these tests under field conditions.     

Postharvest litchi (Litchi chinensis Sonn.) quality preservation by Lactobacillus plantarum

The objective of this work was to preserve the postharvest quality of litchi cv Brewster by the application of Lactobacillus plantarum. A suspension of 1 × 10⁹ CFU/mL of the bacteria was sprayed on ripe litchis and then stored at 10 °C with 75% of relative humidity. Treated fruit exhibited a significantly higher Gram positive bacteria growth on the rind (4–5 log CFU/g) than that detected in control fruit (2.5–3.75 log CFU/g). This result was corroborated by observing a high population of lactobacilli in scanning electron micrographs and by measurement of the content of lactic acid produced. Treated fruit displayed significantly (α ≤ 0.05) reduced color losses as indicated by the higher L* and C* values in comparison with the untreated ones. Additionally, cyanidin-3-rutinoside and total anthocyanin contents supported the measured color retention, since the pericarp of fruit treated with Lb. plantarum showed a significantly higher concentration of pigments than those used as control. In addition, a high concentration of phenolic compounds was found in the rind of treated fruit.     

Characterization of Italian Durum Wheat Semolina by Means of Chemical Analytical and Spectroscopic Determinations

Proton high‐resolution magic angle spinning nuclear magnetic resonance (¹H HR‐MAS NMR) has been applied for the analysis of two cultivars of durum wheat produced in different Italian geographical areas. Furthermore, on the same samples, isotopic ratios were measured by mass spectrometry (IRMS). The application of chemometrics to these results permitted the discrimination of semolina by cultivar and geographical origin. A similar approach has been applied to the results obtained from chemical analyses. The comparison showed that NMR spectroscopy can provide a faster method for the detection of differences among the durum wheat semolina according to geographical and varietal origin. Furthermore, IRMS data are suitable to provide information about the geographical origin of samples. This present investigation is part of an extensive research project to find a scientific method capable of classifying wheat foods for the assignment of a “denomination of origin” trademark.     

Thermotolerant Campylobacters in domestic animals in a defined population in Buenos Aires,Argentina

We assessed the prevalence of Campylobacter jejuni in animals in a region of unsatisfied basic needs in the city of Buenos Aires and studied a few risk factors. First we conducted a census to identify all dwellings having pet animals (dogs, cats, and birds). Fecal samples were then taken for isolation and identification of strains. We observed 17% prevalence for dogs (95% CI: 13, 22), 16% for cats (95% CI: 8, 27) and 19% for birds (95% CI: 5, 42). In dogs, the highest prevalences were found in summer and in animals <1 year old; in cats, in autumn and those aged 3-5 years. Strains were identified as C. jejuni biotype II in 70% of isolates. In the population described here, dogs, cats and birds kept in households were potential sources of human Campylobacter infections.     

Fusarium solani f. sp. passiflorae: a new forma specialis causing collar rot in yellow passion fruit

The aim of this study was to characterize a Fusarium population obtained from yellow passion fruit (YPF) with collar rot using pathogenicity, morphocultural characteristics and molecular tests. Pathogenicity and disease severity were assessed in six plant species: YPF, zucchini, tomato, bean, soya bean and cucumber. Potato dextrose agar medium (PDA) was used to determine mycelial growth at five temperatures (15–35°C). The colour produced by isolates was also determined on PDA at 25°C. Synthetic nutrient agar medium was used to evaluate: (i) type of mycelium and phialides; (ii) size, shape and number of septa from conidia; and (iii) production of chlamydospores and perithecia. Molecular tests consisted of sequencing the ITS–5·8S rDNA region and elongation factor 1α (EF‐1α) gene. The isolates caused large lesions on YPF, zucchini and tomato, with YPF having the highest mean disease severity and being the only one that showed wilt symptoms and death of the plant. Thus the isolates showed host specificity. Maximum mycelial growth occurred at 25°C and the predominant colour was bluish‐white. The isolates produced long phialides, dense aerial mycelium, oval microconidia with a mean size of 9·5 × 2·6 μm, macroconidia of 32·7 × 3·4 μm with 3·3 septa, and chlamydospores; only one isolate lacked perithecia. Phylogenetic trees of the ITS region and EF‐1α gene showed that isolates from YPF formed a distinct group within the F. solani group and the formae speciales of F. solani. It is proposed to name all isolates from YPF as F. solani f. sp. passiflorae.     

Determination of the grape invertase content (using PTA-ELISA) following various fining treatments versus changes in the total protein content of wine. relationships with wine foamability

Proteins have proven to play a major role in the stabilization of foam in Champagne wines despite their low concentration that ranges from 4 to 20 mg/L. The aim of this study was to evaluate the effect of fining on total protein and grape invertase contents of champenois base wines and their foaming properties. Data showed that fining and especially the use of bentonite at doses ranging from 10 to 50 g/hL leads to a significant decrease in the total protein content of wines together with that of the grape invertase content, with such a decrease being very detrimental to the foaming properties of the treated wines in terms of foam height (HM) and foam stability (HS). Only a slight decrease in the total protein content, in the grape invertase concentration, and in the foam quality of wines was observed when using casein (10 and 20 g/hL) or bentonite combined with casein (both at 20 g/hL). Our study thus clearly establishes the good correlation existing between the wine protein concentration and its foaming properties. A remarkable correlation was observed between the decrease in the grape invertase content and the total protein content of wines, following bentonite treatments, suggesting that the grape invertase (which represents at least 10-20% of the wine proteins) follows a similar behavior upon fining to other proteins of Champagne wines, despite the high molecular mass and the highly glycosylated structure of this particular protein. Moreover, the decrease in total protein and grape invertase contents of wine after fining with bentonite was found to be correlated with a decrease in the foaming properties of the corresponding wines (with respectively R(2) = 0.89 and 0.95).     

Biological control and agricultural modernization: Towards resolution of some contradictions

An emergent contradiction in the contemporary development of biological control is that of the prevalence of the substitution of periodic releases of natural enemies for chemical insecticides and the dominance of biotechnologically developed transgenic crops. Input substitution leaves in place the monoculture nature of agroecosystems, which in itself is a key factor in encouraging pest problems. Biotechnology, now under corporate control, creates more dependency and can potentially lead to Bt resistance, thus excluding from the market a key biopesticide. Approaches for putting back biological control into the hands of farmers (from artesanal biotechnology for grassroots biopesticide production Cuban style to farmer-to-farmer IPM networks, etc.) have been developed as a way to create a farmer centered approach to biological control     

Risk assessment of Arbutus unedo L. fruits from plants growing on contaminated soils in the Panasqueira mine area,Portugal

Purpose

In the Panasqueira mine area, Arbutus unedo L. (arbutus tree) grows on soils developed on waste materials and on soils impacted by mining activity. The arbutus berry brandy is considered a product with economic value. The aims of this study were to evaluate the biogeochemical impact of the mining activity on soils and arbutus trees, to assess the possible risks associated with human consumption of the fruits and the derived brandy, and to evaluate the potential of the arbutus tree in phytostabilization.

Materials and methods

Soil samples (10–15 cm deep) developed on waste materials, on schists affected by seepage water or treatment plant effluents and on colluvium-alluvium materials were characterized (fraction <2 mm) for pH, particle size distribution, organic carbon (C_org), cation exchange capacity (CEC) and NPK by classical methodologies. Plant (A. unedo) samples (roots, leaves and twigs, and fruits) were collected at the same sites as the sampled soils, washed with tap and distilled water and dried at 40 °C. The elements’ concentrations in soils (total fraction—four-acid digestion and available fraction—diethylenetriaminepentaacetic acid extraction), plants (ashing followed by acid digestion) and brandy samples produced with fruits collected on contaminated and non-contaminated sites were determined by inductively coupled plasma atomic emission spectroscopy.

Results and discussion

The soils are mainly acid, silty loam, with variable values for C_org, CEC and NPK. They are contaminated with As (158–7,790 mg/kg), Cd (0.6–79 mg/kg), Cu (51–4,080 mg/kg), W (19–1,450 mg/kg) and Zn (142–12,300 mg/kg). The available fraction of the soils is quite variable between <0.04 and 76 % of the total, depending on the element. Trace elements’ concentrations, in leaves and twigs, are within the normal range for plants, except for Cd and Zn that, in some samples, are above the normal values, but without phytotoxic symptoms. Trace elements’ concentrations in fruits are low. The calculated hazard quotient for all trace elements in arbutus berry was <0.1. In the brandy, elemental concentrations are within the legal standards, except for Pb, whose higher concentrations may result from distillery equipment.

Conclusions

According to the EC 466/2001 legislation and with a hazard quotient of <1, the arbutus berry consumption does not constitute health risks for humans. The fruits can be used to produce local brandy. The concentration of copper in brandy is within the range established by the Portuguese legislation. Arbutus unedo can be used in the phytostabilization programs in the Panasqueira area, for it is a pioneer species and a non-accumulator of trace elements.