Identification of galegine, an isoprenyl guanidine, as the toxic principle of Schoenus asperocarpus (poison sedge)

SUMMARY An Isoprenyl guanldine, galegine, was isolated from the Western Australian sedge Schoenus asperocarpus (Cyperaceae). Synthetic galegine was shown to reproduce the clinical and pathological features of poisoning by this plant. Preliminary results suggest that the massive thoracic effusion observed in sedge poisoning is the result of a direct effect on pulmonary vascular permeability.     

Residues from long-acting antimicrobial preparations in injection sites in cattle

Objective To investigate tissue residues of two longacting oxytetracycline (OTC) preparations in cattle.
Design A randomised drug residue trial.  

Animals

Two hundred and forty beef cattle in 24 groups of ten.
Procedure Two blind-coded 200 mg/mL OTC preparations were used in five treatment regimens of various combinations of injection sites (from one to five) and administrations (one or two). Five cattle from each group were slaughtered at 21, 30 and 60 days after injection and the injection site, urine, kidney and diaphragm muscle analysed for residues.
Results The OTC concentration exceeded the maximum residue limit in kidney in animals slaughtered 21 days after treatment, which is the prescribed withholding period. Concentration at the injection site was much greater than the maximum residue limit 30 days post-treatment, but not 45 days post-treatment. The residue was smaller when OTC had been injected in multiple sites. There was no difference between the two OTC preparations.
Conclusion A review of the maximum injection volume, site of injection and the withholding period is needed for long-acting OTC formulations.     

Endocrine Disruptors and Other Food-contaminating Environmental Pollutants as Risk Factors in Animal Reproduction

Pollutants of many chemical classes, derived primarily from anthropogenic activities, are ubiquitous in the environment, persistent, biologically available and can exert adverse effects on the reproductive and other, indirectly related, physiological systems. Food is generally considered to be the major route of animal exposure in vertebrate species but the relative contributions of other routes of exposure such as through lungs, gills or skin are not well studied and may be of importance for certain animal groups, depending on their immediate environment. Animals are particularly sensitive to exposure during developmental stages but the pattern of exposure to chemicals is likely to be different to that of adults. Quantification of the risk posed by the ingestion of pollutants in food is complex and depends on many factors including species, diet composition, duration of exposure to the food, efficiency of pollutant absorption, subsequent metabolism, sensitivity of target organs and stage of development. While the effects of high doses of single chemicals are proven, dietary exposure to pollutants generally involves prolonged, low-level exposure to a large number of compounds, each of which has different chemical characteristics, exerts different biological effects and is present at varying concentrations. Thus, while exposure to pollutants through feed is undoubtedly a significant risk factor for many species and may be the most important one for many terrestrial vertebrates, other routes of exposure may be more important in other groups.     

Improving Phosphorus Use Efficiency in the Future

World demand for phosphorus (P) fertilizer and increasing environmental regulations concerning water quality will continue to motivate the search for ways to improve P use efficiency in potato production. While much effort has gone into understanding P availability and uptake from soil, relatively little is known about the possibility of increasing uptake efficiency through genetic improvement or improved root health. Potato exhibits considerable genetic variation in uptake efficiency of nutrients like nitrogen, and it is likely that genetic variation also exists in P use efficiency. Increased efficiency may be due to differences in tuber yield per unit of available P (utilization efficiency), or in rate of P absorption from the soil (uptake efficiency). Likewise, genetic improvements in resistance to root-decaying pathogens, such as Verticillium dahliae, and improved control practices are likely to help maintain a healthy root mass to aid in maintaining P uptake during periods of higher P demand during the growing season.     

Proceedings from the 2012 PAA Symposium: Potato Phosphorus Management and Utilization for Today and Tomorrow

Sustainable management of phosphorus (P) is a critical component of potato production systems because of a comparatively high plant P requirement, soil reactions that create management challenges, and potential environmental degradation from inappropriate P management. Phosphorus affects potato plant growth in many ways including its effects on plant metabolism, cellular structural components, canopy development, tuber set, nutritional quality, and resistance to some diseases.     

Quantitative analysis of N-phenylpropenoyl-L-amino acids in roasted coffee and cocoa powder by means of a stable isotope dilution assay

Since recent reports on the role of N-phenylpropenoyl-L-amino acids as powerful antioxidants and key contributors to the astringent taste of cocoa nibs, there is an increasing interest in the concentrations of these phytochemicals in plant-derived foods. A versatile analytical method for the accurate quantitative analysis of N-phenylpropenoyl-L-amino acids in plant-derived foods by means of HPLC-MS/MS and synthetic stable isotope labeled N-phenylpropenoyl-L-amino acids as internal standards was developed. By means of the developed stable isotope dilution assay (SIDA), showing recovery rates of 95-102%, 14 N-phenylpropenoyl-L-amino acids were quantified for the first time in cocoa and coffee samples. On the basis of the results of LC-MS/MS experiments as well as cochromatography with the synthetic reference compounds N-[3',4'-dihydroxy-(E)-cinnamoyl]-L-tryptophan, N-[4'-hydroxy-(E)-cinnamoyl]-L-tryptophan, and N-[4'-hydroxy-3'-methoxy-(E)-cinnamoyl]-L-tyrosine, respectively, were detected for the first time in cocoa powder, and (-)-N-[4'-hydroxy-(E)-cinnamoyl]-L-tyrosine, (-)-N-[3',4'-dihydroxy-(E)-cinnamoyl]-L-tyrosine, N-[4'-hydroxy-3'-methoxy-(E)-cinnamoyl]-L-tyrosine, (+)-N-[3',4'-dihydroxy-(E)-cinnamoyl]-L-aspartic acid, (+)-N-[4'-hydroxy-(E)-cinnamoyl]-L-aspartic acid, N-[3',4'-dihydroxy-(E)-cinnamoyl]-L-tryptophan, N-[4'-hydroxy-(E)-cinnamoyl]-L-tryptophan, and N-[4'-hydroxy-3'-methoxy-(E)-cinnamoyl]-L-tryptophan, respectively, were detected for the first time in coffee beverages.     

Nonenzymatic C-glycosylation of flavan-3-ols by oligo- and polysaccharides

Model reactions between the polysaccharide amylose and the polyphenol (-)-epicatechin followed by partial enzymatic hydrolysis of the reaction products formed led to the detection of mono- and oligo-C-glucosylated flavan-3-ols by means of LC-MS/MS experiments. To confirm the structure of these putative flavan-3-ol/oligosaccharide conjugates, (-)-epicatechin was reacted with maltose and maltotriose, respectively, giving rise to a series of previously unreported flavan-3-ol/maltose and flavan-3-ol/maltotriose conjugates, namely, (-)-epicatechin-8-C-beta-D-glucopyranosyl-(4-->1)-O-alpha-D-glucopyranoside, (-)-catechin-8-C-beta-D-glucopyranosyl-(4-->1)-O-alpha-D-glucopyranoside, (-)-catechin-6- C-beta-D-glucopyranosyl-(4-->1)-O-alpha-D-glucopyranoside, (-)-catechin-8-C-beta-D-glucopyranosyl-(4-->1)-O-alpha-D-glucopyranosyl-(4-->1)-O-alpha-D-glucopyranoside, (-)-catechin-6-C-beta-D-glucopyranosyl-(4-->1)- O-alpha-D-glucopyranosyl-(4-->1)-O-alpha-D-glucopyranoside, and (-)-epicatechin-6/8-C-beta-D-glucopyranosyl-(4-->1)-O-alpha-D-glucopyranosyl-(4-->1)-O-alpha-D-glucopyranoside. Furthermore, quantitative analysis of flavan-3-ol-C-glucosides in an enzymatic total hydrolysate using a newly developed stable isotope dilution assay (SIDA) enabled a first insight into the yield of the formation of polyphenol/polysaccharide cross-links, for example, an amount of 14.0, 9.0, and 0.15 micromol of flavan-3-ol-6-C-beta-D-glucopyranoside, flavan-3-ol-8-C-beta-D-glucopyranoside, and flavan-3-ol-6- C,8-C-beta-D-glucopyranoside were per mmol (-)-epicatechin when reacted with amylose.     

Small-scale spatial variability of selected soil biological properties

A strategy for sampling soil from intact monolith lysimeters was established based on measurements of spatial heterogeneity within the lysimeter area. This was part of an ongoing study to determine relationships between soil microbial diversity and nutrient loss by leaching. The sampling protocol had to allow collection of soil on a regular basis (as opposed to destructive sampling) and ensure high spatial independence of subsamples. On each of the two sites (one developed under organic crop management and the other under conventional crop management), ten 15 cm soil cores (sampling points) were taken from three areas (replicates) of 50 cm diameter (lysimeter surface area) and separately analysed for biotic (microbial biomass carbon and nitrogen; arginine deaminase activity) and abiotic (total carbon and nitrogen) soil properties. The data were tested for variability, expressed as coefficient of variance (biotic and abiotic), and spatial heterogeneity using geostatistics (biotic properties). The biotic soil properties showed significant differences among sampling points, whereas the abiotic parameters were useful in differentiating on a larger scale, i.e. between sites. For all soil properties tested, the differences among the replicates were smaller than those between the sites or among points indicating that, in the main experiment, all treatments can be sampled following the same pattern. Geostatistical analysis and fitting of an exponential model showed that a spatial structure exists in the biotic soil properties and that the samples are independent beyond separation distances of 25-30 cm. A revised sampling pattern consisting of 11 samples per lysimeter is described.