Structure-activity relationship (SAR) studies of benzoxazinones, their degradation products, and analogues. Phytotoxicity on problematic weeds Avena fatua L. and Lolium rigidum Gaud

Avena fatua L. (wild oat) and Lolium rigidum Gaud. (rigid ryegrass) are highly problematic weeds affecting a wide variety of cereal crops worldwide. The fact that both of these weeds have developed resistance to several herbicide groups made them optimal candidates as target organisms for ongoing research about the potential application of allelochemicals and analogue compounds as natural herbicide models. Benzoxazinones, a family of natural allelochemicals present in corn, wheat, and rye, including 2,4-dihydroxy-(2H)-1,4-benzoxazin-3(4H)-one and 2,4-dihydroxy-7-methoxy-(2H)-1,4-benzoxazin-3(4H)-one, together with some degradation products, found in crop soils as well as in other systems, and some synthetic analogues of them were tested on wild oat and rigid ryegrass seeds; the results were statistically treated, and some structure-activity relationships, useful in further development of natural herbicide models, were elucidated. The most active compounds were the synthetic benzoxazinone 2-acetoxy-(2H)-1,4-benzoxazin-3(4H)-one and the degradation product 2-aminophenoxazin-3-one, with highly significant inhibition on the development of both weeds. The ecological role of these compounds is discussed by considering both degradability and phytotoxicity. The bioactivity of aminophenoxazines has been correlated by their aqueous solubility-lipophilicity predicted by means of computational methods.     

Detection of the presence of hazelnut oil in olive oil by FT-raman and FT-MIR spectroscopy

The detection of the presence of refined hazelnut oil in refined olive oil at low percentages is still a challenge with the current official standards. FT-Raman and FT-MIR spectroscopies have been used to determine the level of detection of the presence of hazelnut oil in olive oil. Spectroscopic analysis has been made not only with the entire oil but also with its unsaponifiable matter. Univariate and multivariate statistical models have been designed with this objective. This study shows that a complete discrimination between olive and hazelnut oils is possible and that adulteration can be detected if the presence of hazelnut oil in olive oil is >8% and if the blends are of Turkish olive and hazelnut oils. The limit of detection is higher when the blends are of edible oils from diverse geographical origins.     

Virgin olive oil quality classification combining neural network and MOS sensors

A model based on neural networks has been designed to detect lampante virgin olive oils, a category of olive oil that cannot be consumed without a previous refining process according to the current regulation of the European Communities. The response of 7 metal oxide sensors analyzing 114 olive oil samples has been used in the design, training, and internal validation of the neural network with only 4.5% error in validation. The designed mathematical model, the equations of which are fully described, has been validated also with an external set of 13 samples of diverse varieties and geographical origins with 100% correct classification.     

Monitoring benthic microflora in river bed sediments: a case study in the Anllóns River (Spain)

Purpose

The objectives of this study were to investigate the abundance and composition of the superficial biofilm on the bed sediments of the Anllóns River (NW Spain), to evaluate the relationships between biochemical parameters and biological methods based on identification and counting, and to explore the relationships between biofilm growth and the properties of the sedimentary habitat, mainly the trophic state.

Materials and methods

Bed sediment samples (0–5 cm) were collected in two different seasons (winter and summer) at four sampling sites along the river course. Physicochemical properties of pore waters and sediments were determined. Biological properties included the determination of dehydrogenase activity (DHA) and phytopigment (Chl a Chl b and total carotenoids) concentrations, as well as taxonomic identification. For taxonomic identification, two sampling methods were compared: the Pasteur pipette method and a mini-corer method. Total and relative algal abundances (TA and RA, respectively) and genus richness were calculated. The relationships between the different variables were examined using Pearson correlations and principal component analysis.

Results and discussion

The main taxa belonged to Chlorophyta, Cyanophyta, Euglenophyta, and Heterokontophyta. The most abundant class was Bacillariophyceae, which represents >86 % of the total abundances in the superficial sediments. The highest total algal abundance and genus richness were observed in summer at the river mouth, where DHA and phytopigment concentrations were also the highest. The statistical analysis revealed positive correlations between TA and the biochemical parameters (DHA and phytopigments) as well as positive relationships of these three parameters with the physicochemical properties of the sediments, such as electrical conductivity, and the concentrations of fine particles, C, N, S, and total P.

Conclusions

The results of this study reveal the positive relationships between the biochemical properties (phytopigments and respiratory activity) and total algal abundances determined by taxonomic identification and counting. All of these properties presented evidence of a clear influence of the nutrients and organic matter contents of the sediments, pointing to the importance of the site conditions, particularly the trophic state, in the development of benthic microflora.

     

Prevention of patulin toxicity on rumen microbial fermentation by SH-containing reducing agents

Patulin, a toxic fungal metabolite, negatively affects rumen fermentation. This mycotoxin has also been associated with intoxication cases in cattle. This study investigates the use of SH-containing reducing compounds to prevent patulin's negative effects on the rumen microbial ecosystem. The effect of 50 microg/mL patulin on the fermentation of alfalfa hay was measured in batch cultures with and without reducing agents. Sulfhydryl-containing cysteine and glutathione prevented the negative effects of the toxin on dry matter degradation, gas, and volatile fatty acid production (P < 0.01). However, non-sulfhydryl-containing ascorbic and ferulic acids did not protect against patulin's toxicity (P > 0.01). Patulin was unstable in buffered rumen fluid as the concentration decreased by half after 4 h of incubation. In the presence of sulfhydryl groups, the toxin disappeared rapidly and was not detected after 1 h of incubation. The utilization of sulfhydryl-containing compounds such as cysteine to avert patulin toxicity could have practical implications in ruminant nutrition.     

Prey density, prey detectability and food habits: the case of Bonelli’s eagle and the conservation measures

In the diet of raptors the presence of prey-species is influenced by their abundance and the ground-level vegetation in territories, this situation being analysed for the Bonelli’s eagle (Hieraaetus fasciatus) in south-eastern Spain. First, the minimum number of prey-items for the reliability of results was tested, obtaining between 15 and 30 prey-items depending of pair. Second, differences in prey frequency and productivity among pairs was analysed, finding an interpair shift in both variables, but there was no relationship between the frequency of prey-species in the diet and productivity. Third, it was found that the percentage of European wild rabbit in the diet was less correlated with its abundance in territories than with the surface of open land in the same. This suggests that accessibility to rabbits would be more important for the Bonelli’s eagle that the absolute abundance of this prey type. Thus, open land is the single variable selected by a multiple multiple-regression analysis explaining the frequency of rabbits in this raptor’s diet. Birds as prey complemented the diet when open-land scarcity in the territories implies low rabbit detectability and consumption. Conservation measures proposed concerning the increase of prey availability in this declining population should consider both the absolute prey density and prey detectability, avoiding extensive reforestation in territories and favouring vegetation structure suitable for prey detection by eagles.     

Detection of vinegary defect in virgin olive oils by metal oxide sensors

An array of metal oxide sensors has been set up for detecting the vinegary defect in virgin olive oil. The optimization process was carried out evaluating the variables affecting the process by three desirability functions. Repeatability studies for 6 months and within day were done to evaluate the sensor responses and remove those with high relative standard deviation. The sensor responses were preprocessed applying five weight functions previously to build a regression model. Samples of Spanish Arbequina and Picual virgin olive oil varieties spiked with different amounts of acetic acid (15-200 mg/L) were used as a training set for the regression model. The test set was composed of samples of Italian Coratina virgin olive oil spiked with the vinegary standard at five percentages (10, 25, 40, 50, and 75). A fine-adjusted regression coefficient (R(adj)(2) = 0.98) was computed with the test set.     

Biomechanics of the fresh and conserved bovine pericardium

The use of biological membranes in surgeries is a reality for years, and one of the most used is the bovine pericardium, so the purpose of this research is to describe the bovine pericardium's biomechanics by comparing two directions of a test, one parallel to the longitudinal heart axis and one perpendicular. 20 adult bovine pericardium were tested for the maximum rupture force and rupture elongation, collecting four samples of each pericardium direction. In phase 2, eight pericardia were conserved for 4 months in a 98% glycerine solution, and the solution in which they were submerged was microbiologically analysed monthly. The Mann–Whitney test was used; there was a very significant difference between the perpendicular and parallel groups (p = .0001). The T test showed no significant difference for the rupture elongation (p = .0938). In pericardium preserved in glycerine, the outliers were removed regarding the maximum rupture force, and a Boxcox transformation was performed (λ = 0.25). Outliers were removed for the rupture elongation, and Bartlett's test (p = .7836), and Cramer–Von Mises (p = .5033) were performed and then, the analysis of variance (p < .0001), followed by the Tukey test at 5%. In the microbiological analysis, there was no presence of microorganisms during conservation. The research has shown that the pericardium collection direction influences its resistance and it can be stored in glycerine for 4 months without losing biomechanical characteristics.     

Diagnosis of Eimeria species using traditional and molecular methods in field studies

The objective of this study was to identify and characterize species of Eimeria in broiler chickens using traditional morphological and pathological plus molecular (DNA amplification) diagnostic methodologies. Using a combination of those techniques it was possible to identify the presence of multiple circulating species in the flock as well as higher frequencies for some of them, especially Eimeria praecox and Eimeria maxima, which were identified in 100% of the flocks. The frequencies of the other species were Eimeria mitis and Eimeria necatrix (93.3%), Eimeria tenella (76,7%), Eimeria acervulina (56.7%) and Eimeria brunetti (16.7%). However using the lesion score, the most common species were E. maxima (46.7%), E. acervulina (30%), E. tenella (23.3%), and E. necatrix (10%). E. brunetti and E. praecox were not identified by using lesion score. DNA amplification had detection sensitivity for Eimeria species in the field samples of at least 20 oocysts. The implementation of DNA amplification as a routine diagnostic technique in aviaries can assist Eimeria population.