Evaluation of protein hydrolysis in raw sources by digestive proteases of Senegalese sole (Solea senegalensis,Kaup 1858) using a combination of an in vitro assay and sodium dodecyl sulphate polyacrylamide gel electrophoresis analysis of products

The hydrolysis of protein in different animal and plant sources by the intestinal proteases of Senegalese sole (Solea senegalensis) was studied using a combination of an in vitro digestibility assay and the evaluation of the protein fractionation by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS‐PAGE). In vitro hydrolysis was performed for 90 min in a closed reactor maintained at constant pH and temperature. Samples of the reaction mixture at different time intervals were developed in SDS‐PAGE gels to evaluate the progressive hydrolysis of the different protein fractions in each protein source. A numerical value [coefficient of protein degradation (CPD)], which integrates the information obtained after image analysis of the gels, is proposed for comparison among proteins, according to the intensity of the hydrolysis produced by sole proteases. Additionally, the total free amino acid released from proteins was measured during the in vitro assay. Casein, squid meal and soybean concentrate (SBC) proteins showed very similar degradation patterns, with a quick and almost complete proteolysis within the first minutes of the enzymatic reaction. Fish and krill meals were hydrolysed more progressively. On the contrary, pea meal (PM) and corn gluten meal (CGM) showed scarce changes in their protein profile after 90 min of reaction. For animal protein sources, the final CPD values ranged from 77.6% to 87.0%, showing not significant differences. By contrast, PM (30.5%) and CGM (32.3%) presented significantly lower CPD values (P<0.05) as compared with SBC (90.6%). In general, a linear fitting was found between CPD and the release of free amino acids during in vitro protein hydrolysis. The present study provides detailed information, which, combined with the conventional in vitro digestibility studies, may help in the evaluation of different raw sources according to their protein degradation patterns. This information can be applied directly to estimate the protein nutritional quality of ingredients for Senegalese sole feeds.     

Contribution of Hydrophobic Soluble Gluten Proteins,Fractionated by Hydrophobic Interaction Chromatography in Highly Acetylated Agarose,to Dough Rheological Properties

Hydrophobic interaction chromatography with highly acetylated agarose in 1‐mL columns was used to fractionate gliadins and acid‐soluble glutenins. Proteins were eluted in two fractions, the first with acetate buffer (pH 3.6) containing 35% propanol, and the second with Tris buffer in 8M urea. The proportion of eluted protein in the second fraction was called the surface hydrophobicity index. The study included 20 wheat samples of different baking qualities. Multiple regression analysis using the general linear model combined with the stepwise technique was used to relate the surface hydrophobicity index of soluble gluten proteins to specific dough rheological characteristics. Surface hydrophobicity index of gliadins and acetic acid soluble glutenins explained part of the variability of swelling index, extensibility, and work of deformation (dough strength) measured with the alveograph, and part of the farinograph water absorption variability, but showed no relationship to dough mixing characteristics. Hydrophobic soluble gluten proteins fractionated by hydrophobic interaction chromatography (HIC) explained a part of the variability of dough rheological properties.     

The Spanish barley core collection

Spanish barleys constitute a germplasm group of particular interest for breeding purposes, as Spain has been proposed as a possible centre of origin of the crop. The Spanish National Germplasm Bank (Banco Nacional de Germoplasma, BNG), holds a collection of about 2000 barley accessions, mostly landraces collected in Spain prior to extensive introduction of modern varieties. The objective of this work is to create a core collection of barleys representative of old barley genotypes grown in Spain. The core collection will be constituted by three groups of germplasm: successful old varieties (15); entries in common with previously existing barley core collections (15); and 2-row (8) and 6-row (122) entries from the BNG, for a total of 160 entries. Entries were allocated by stratified sampling in agro-ecological uniform zones of barley cultivation in Spain. Classification of agro-ecological regions for barley was based on historical yield records for Spanish provinces. The number of entries for each region was determined in proportion to the logarithm of historical barley acreage. Final choice of accessions within provinces tried to maximize the diversity and avoid duplications by looking at passport data, and to agronomic evaluation data available for a group of about 900 accessions.     

Application of Six Detection Methods for Analysis of Paralytic Shellfish Toxins in Shellfish from Four Regions within Latin America

With the move away from use of mouse bioassay (MBA) to test bivalve mollusc shellfish for paralytic shellfish poisoning (PSP) toxins, countries around the world are having to adopt non-animal-based alternatives that fulfil ethical and legal requirements. Various assays have been developed which have been subjected to single-laboratory and multi-laboratory validation studies, gaining acceptance as official methods of analysis and approval for use in some countries as official control testing methods. The majority of validation studies conducted to date do not, however, incorporate shellfish species sourced from Latin America. Consequently, this study sought to investigate the performance of five alternative PSP testing methods together with the MBA, comparing the PSP toxin data generated both qualitatively and quantitatively. The methods included a receptor binding assay (RBA), two liquid chromatography with fluorescence detection (LC-FLD) methods including both pre-column and post-column oxidation, liquid chromatography with tandem mass spectrometry (LC-MS/MS) and a commercial lateral flow assay (LFA) from Scotia. A total of three hundred and forty-nine shellfish samples from Argentina, Mexico, Chile and Uruguay were assessed. For the majority of samples, qualitative results compared well between methods. Good statistical correlations were demonstrated between the majority of quantitative results, with a notably excellent correlation between the current EU reference method using pre-column oxidation LC-FLD and LC-MS/MS. The LFA showed great potential for qualitative determination of PSP toxins, although the findings of high numbers of false-positive results and two false negatives highlighted that some caution is still needed when interpreting results. This study demonstrated that effective replacement methods are available for countries that no longer wish to use the MBA, but highlighted the importance of comparing toxin data from the replacement method using local shellfish species of concern before implementing new methods in official control testing programs.     

Soil bulk density and porosity of homogeneous morphological units identified by the Cropping Profile Method in clayey Oxisols in Brazil

Soil structure is important to root development and crop yield. The objective of this study was to test the Cropping Profile Method in Brazilian soils, in order to evaluate the soil structure in the field. Grouped different structures determined by the Cropping Profile Method were compared to laboratory determinations for soil bulk density, total porosity and mercury porosity. The study was conducted in clayey Oxisols submitted to different uses and management including annual crops, orchards and natural forests in the State of Paraná, southern Brazil. Homogeneous morphological units (HMUs) were determined in trenches using the Cropping Profile Method, and the different structures were grouped as: (a) non-compacted; (b) compacted; (c) in-process-of-compacting. Results of field evaluation were compatible with those obtained in the laboratory. More compacted and in-process-of-compacting structures corresponded to soil bulk density values of 1.42 and 1.33 Mg m⁻³, which were significantly higher than the 1.18 Mg m⁻³ value obtained for soil bulk density in non-compacted HMU. The total porosity of compacted HMU and in-process-of-compacting HMU was 0.49 and 0.52 m³ m⁻³, respectively. These were significantly lower than the value obtained for the non-compacted HMU (0.60 m³ m⁻³). The Cropping Profile Method is useful mainly in field research works when it is important to verify the effect of management practices on soil structure.     

Antimicrobial activity of olive solutions from stored Alpeorujo against plant pathogenic microorganisms

The aim of this work was to assess the in vitro antimicrobial effects that wastewaters from alpeorujo oil extraction have against phytopathogenic bacteria and fungi. Alpeorujo was stored for 6 months and then processed to extract its oil, pomace, and a new liquid waste (OWSA), which was characterized by its content in phenolic compounds. OWSA at 20% decreased bu >4 log the population of Erwinia spp., Pseudomonas spp., and Clavibacter spp. viable cells in test tubes, whereas OWSA at 50% in agar medium was necessary to inhibit mycelial growth of most fungi. It was found that the bactericidal effect was due to the joint action of low molecular mass phenolic compounds, although neither hydroxytyrosol, its glucosides, hydroxytyrosol glycol, nor a glutaraldehyde-like compound individually explained this bioactivity. Hence, OWSA constitutes a promising natural solution to fight plant phytopathogenic bacteria and fungi.     

A synthetic conjugate polysaccharide vaccine against Haemophilus influenzae type b

Glycoconjugate vaccines provide effective prophylaxis against bacterial infections. To date, however, no commercial vaccine has been available in which the key carbohydrate antigens are produced synthetically. We describe the large-scale synthesis, pharmaceutical development, and clinical evaluation of a conjugate vaccine composed of a synthetic capsular polysaccharide antigen of Haemophilus influenzae type b (Hib). The vaccine was evaluated in clinical trials in Cuba and showed long-term protective antibody titers that compared favorably to licensed products prepared with the Hib polysaccharide extracted from bacteria. This demonstrates that access to synthetic complex carbohydrate-based vaccines is feasible and provides a basis for further development of similar approaches for other human pathogens.     

Zeolites and diatom growth

Zeolites are widely used in some Asiatic countries, as they are believed to improve water quality and selectively enhance diatom growth through silicon leaching. Culture experiments with the diatom Chaetoceros sp. in medium f, with no silicate, and enriched with two natural and three artificial zeolitic products, showed an enhancement of between 0.2 and 0.6 cell duplications, which cannot be as a result of higher silicate availability because solubility experiments showed that natural zeolites do not leach any silicon, and that the amounts released by the artificial products are too small to improve diatom growth.