Defoliation and fertiliser influences on the soil microbial community associated with two contrasting Lolium perenne cultivars

The influence of repeated defoliation on soil microbial community (SMC) structure and root turnover was assessed in two contrasting Lolium perenne cultivars (AberDove and S23) grown in fertilised (+F) and non-fertilised (NF) soil. BiOLOG sole carbon source utilisation profiles (SCSUPs) indicated consistently greater potential carbon utilisation in defoliated (+D) compared to non-defoliated (ND) soils regardless of cultivar and fertiliser, and was accounted for in a variety of substrate groups (sugars, carboxylic, amino and phenolic acids). Potential carbon utilisation was also stimulated in +F compared to NF soils, primarily through increased potential utilisation of carboxylic acids. PLFA indicators for the bacterial biomass did not significantly differ between cultivar, soil fertilisation, or defoliation. Defoliated swards grown in fertilised soil (+F+D) had a higher fungal:bacterial ratio and a greater bacterial stress index (cy19:0/18:1w7c), compared to that of +F ND, NF ND and NF+D, and regardless of cultivar. Overall SMC structure (canonical variate (CV) analysis of PLFAs) discriminated based on cultivar, defoliation and soil fertilisation. Primary discrimination of the SMCs could be related to differences in root density and total plant biomass, and in the case of NF soils, secondary community shifts, evident with defoliation, related to root disappearance over the growing season. Despite the strong common effects of defoliation, and to a lesser extent soil fertilisation, cultivar specific drivers of the soil microbial community were maintained, resulting in consistent, but subtle, discrimination of the SMC associated with the contrasting L. perenne cultivars.     

Can sodium regulation be used to predict the relative acid-sensitivity of various life-stages and different species of aquatic fauna?

Fishes, Zooplankton, insect larvae, and benthic invertebrates differ in their sensitivity to acidic waters. Some species are able to survive and complete their life-cycle below pH 3.5 while others are eliminated once the pH drops below 5.5. Generally, acid-sensitive fauna are highly water permeable and have difficulty regulating osmotically essential ions, such as sodium and chloride, at low pH. Increased permeability during certain stages of a life-cycle (post-molt crayfish, for example) are often associated with increased acid-sensitivity. Special adaptations, including enlarged anal papillae in Chironomids and the number and morphology of chloride cells in such diverse organisms as crustaceans, insect larvae, and fishes, may enhance acid-tolerance. To test the hypothesis that Na⁺ regulation can be used to predict relative acid-sensitivity of aquatic fauna we will need a mechanism for standardizing Na⁺ regulatory capability.     

Hydrogen ion speciation in the acid precipitation of the northeastern United States

The acidity of precipitation in rural, forested areas of the northeastern United States is dominated by the strong mineral acids: H₂SO₄ and HN0₃. Weak acids have a negligible effect on the measured acidity (pH) of precipitation. These conclusions are based on total acidity titrations and detailed analysis of organic and inorganic components in precipitation.     

Ability of surfactant micelles to alter the physical location and reactivity of iron in oil-in-water emulsion

The purpose of this research was to determine how surfactant micelles influence iron partitioning and iron-promoted lipid oxidation in oil-in-water emulsions. Lipids containing ferric ions were used to produce oil-in-water emulsions, and continuous-phase iron concentrations in emulsions were measured as a function of varying continuous-phase polyoxyethylene 10-lauryl ether (Brij) concentrations. Continuous-phase iron concentrations increased with increasing surfactant micelle concentrations (0.1-2.0%) and storage time (1-7 days). At pH 3.0, the concentration of continuous-phase iron was higher than at pH 7.0. Similar trends in iron solubilization by Brij micelles were observed when either hexadecane or corn oil was used as the lipid phase. Lipid oxidation rates, as determined by the formation of lipid hydroperoxides and headspace hexanal, in corn oil-in-water emulsions containing iron decreased with increasing surfactant concentrations (0.5-2.0%). These results indicate that surfactant micelles could alter the physical location and prooxidant activity of iron in oil-in-water emulsions.     

Factoring species, non-species values and threats into biodiversity prioritisation across the ecoregions of Africa and its islands

Biodiversity in Africa, Madagascar and smaller surrounding islands is both globally extraordinary and increasingly threatened. However, to date no analyses have effectively integrated species values (e.g., richness, endemism) ‘non-species’ values (e.g., migrations, intact assemblages), and threats into a single assessment of conservation priorities. We present such an analysis for the 119 ecoregions of Africa, Madagascar and smaller islands. Biodiversity is not evenly distributed across Africa and patterns vary somewhat among taxonomic groups. Analyses of most vertebrates (i.e., birds, mammals, amphibians) tend to identify one set of priority ecoregions, while plants, reptiles, and invertebrates highlight additional areas. ‘Non-species’ biological values are not correlated with species measures and thus indicate another set of ecoregions. Combining species and non-species values is therefore crucial for assembling a comprehensive portfolio of conservation priorities across Africa. Threats to biodiversity are also unevenly distributed across Africa. We calculate a synthetic threat index using remaining habitat, habitat block size, degree of habitat fragmentation, coverage within protected areas, human population density, and the extinction risk of species. This threat index is positively correlated with all three measures of biological value (i.e., richness, endemism, non-species values), indicating that threats tend to be focused on the region’s most important areas for biodiversity. Integrating biological values with threats allows identification of two distinct sets of ecoregion priority. First, highly imperilled ecoregions with many narrow endemic species that require focused actions to prevent the loss of further habitat leading to the extinction of narrowly distributed endemics. Second, less threatened ecoregions that require maintenance of large and well-connected habitats that will support large-scale habitat processes and associated area-demanding species. By bringing these data together we can be much more confident that our set of conservation recommendations serves the needs of biodiversity across Africa, and that the contribution of different agencies to achieving African conservation can be firmly measured against these priorities.     

Use of caseinophosphopeptides as natural antioxidants in oil-in-water emulsions

Chelators are valuable ingredients used to improve the oxidative stability of food emulsions. Caseins and casein peptides have phosphoseryl residues capable of binding transition metals. Thus, the ability of enriched caseinophosphopeptides to inhibit lipid oxidation in corn oil-in-water emulsions was investigated. Enriched caseinophosphopeptides (25 microM) inhibited the formation of lipid oxidation at both pH 3.0 and 7.0 as determined by lipid hydroperoxides and hexanal. Calcium (0-100 mM) had no influence on the antioxidant activity of the enriched caseinophosphopeptides. Casein hydrolysates were more effective inhibitors of lipid oxidation than the enriched caseinophosphopeptides at equal phosphorus content. Thus, antioxidant properties might not be uniquely attributed to chelating metals by phosphoseryl residues but also by scavenging free radicals. Overall, the observed antioxidant activity of casein hydrolysates means they could be utilized to decrease oxidative rancidity in foods.     

Detection of irradiated ingredients included in low quantity in non-irradiated food matrix. 1. Extraction and ESR analysis of bones from mechanically recovered poultry meat

Protocol EN 1786 for the detection of irradiated food by electron spin resonance (ESR) spectroscopy was not conceived for the detection of irradiated bone-containing ingredients included in low concentration in non-irradiated food. An enzymatic hydrolysis method, realized at 55 degrees C, has been developed for the extraction of the bone fraction. When followed by a purification of the extracts by an aqueous solution of sodium polytungstate, this method made possible the detection of irradiated mechanically recovered poultry meat at very low inclusions (0.5%, wt/wt by ESR) in various meals (quenelles and precooked meals).