Liquid extraction of low molecular mass organic acids and hydroxamate siderophores from boreal forest soil

Low molecular mass organic acids (LMMOAs) and hydroxamate siderophores (HS) are molecules secreted by microbes and have previously been found in soil solution and in cultures. Mycorrhizal fungi are suggested to be involved in the nutrient uptake processes of trees and weathering of minerals. In this study soil samples taken from the O and E horizons of a podzol were extracted with 10 mM potassium phosphate buffer at pH 7.2. Variable parameters included addition of methanol to the extraction buffer and the use of ultrasonication or rotary shaking during extraction. LMMOAs and HS content of the soil extracts were determined. Analysis of soil extracts were carried out by liquid chromatography mass spectrometry (LC–MS) and the extraction results compared to results for soil solution samples obtained by centrifugation of the soils sampled. The extraction yields were significantly increased by addition of methanol to the extraction buffer, especially for the O horizon samples. Rotary shaking of the samples for 90 min gave slightly higher yields than ultrasonication for 15 min but the reduction in extraction time makes ultrasonication an attractive option. Of the HSs determined, ferricrocin was found in all samples. Optimal extraction conditions showed citric acid and isocitric acid to be the most abundant organic acids in the O and E horizons, respectively.     

Endocrine growth regulation of adult Atlantic salmon in seawater: The effects of light regime on plasma growth hormone, insulin-like growth factor-I, and insulin levels

Plasma growth hormone (GH), insulin-like growth factor-I (IGF-I), and insulin were measured in two groups of Salmo salar L. during a one-year study. The fish were reared under either a simulated natural photoperiod (SNP) from January to December or a regime of continuous light from January to June, followed by SNP until December (LL/SNP). Plasma GH levels during spring were low, and lower in the LL/SNP fish (< 0.9 ng ml^− 1) than in the SNP fish (> 1.9 ng ml^− 1), although the LL/SNP grew better (0.8% per day) than the SNP fish (0.5% per day). Plasma IGF-I levels increased transiently from January (64.7 ng ml^− 1) to maximum in late September in the LL/SNP (85.8 ng ml^− 1) and in November in the SNP group (87.3 ng ml^− 1). The ratio GH:IGF-I was lower in the LL/SNP group during spring when this group grew better than the SNP group.     

The mineral content affects vertebral morphology in underyearling smolt of Atlantic salmon (Salmo salar L.)

This study investigated the individual variation in vertebral morphology and mineral content (as % of bone dry weight) in rapid growing underyearling smolt (n = 33) twelve weeks after transfer to seawater. The smolt, which were reared in triplicate tanks, had a large individual variation in vertebral bone mineral content (Tank A: 36.2% min, 45.2% max, 39.6% mean. Tank B: 32.6% min, 46.6% max, 40.0% mean. Tank C: 38.5% min, 47.9% max, 42.4% mean), and were subdivided into two groups based on mean within each tank: high mineral content (HMC, above tank mean, n = 15) and low mineral content (LMC, below tank mean, n = 18). Vertebrae of smolt with a low mineral content were more compressed in the anterior–posterior direction (HMC vertebral length/dorso-ventral diameter ratio 0.83, LMC 0.80). This was related to a change in the growth direction of the vertebral cone. This change occurred around transfer to seawater and was characterised by an increased angle between the wall of the cone of the vertebrae and the cranial–caudal axis, and gave the vertebrae a compressed appearance. Smolt with a high mineral content were significantly longer (HMC 28.1 cm, LMC 26.5 cm) and heavier (HMC 270 g, LMC 210 g) twelve weeks after transfer to seawater.     

Initial Effects of Wood Ash Application on the Stream Water Chemistry in a Boreal Catchment in Central Sweden

Due to increased whole-tree harvesting in Swedish forestry, concern has been raised that a depletion of nutrients in forest soil will arise. The Swedish Forest Agency recommends compensation fertilization with wood ash to ensure that unwanted effects are avoided in the nutrient balance of the forest soil and in the quality of surface water. In this investigation, the chemistry of two first-order streams, of which one was subjected to a catchment scale treatment with 3 tonnes of self-hardened wood ash/ha in the fall of 2004, was monitored during 2003?C2006. Large seasonal variations in stream water chemistry made changes due to ash application difficult to detect, but evaluating the ash treatment effects through comparison of the stream water of the treated catchment with the reference was possible via statistical tools such as randomized intervention analysis in combination with cumulative sum charts. The wood ash application did not yield any significant effect on the pH in the stream water and hence did not affect the bicarbonate system. However, dissolved organic carbon increased, a previously unreported effect of WAA, bringing about an increase of organic anions in the stream water. The wood ash application also induced significant increases for Ca, Mg, K, Si, Cl and malonate, of which K was most prominent. Although significant, the changes induced by the wood ash application were all small compared to the seasonal variations. As a tool to counteract acidification of surface waters, WAA seems to have limited initial effects.     

Effects of tyrosinase and laccase on oat proteins and quality parameters of gluten-free oat breads

Effects of a Trichoderma reesei tyrosinase (TYR) and a Trametes hirsuta laccase (LAC) on breadmaking performance of gluten-free oat flour were investigated by SDS-PAGE analysis of oat protein fractions, large deformation rheology, and microscopy of the doughs, as well as on the basis of specific volume and firmness of the gluten-free breads. TYR induced the formation of higher molecular weight proteins in the SDS-PAGE assay. Microscopical analysis showed more intensive protein aggregation in the TYR-treated dough than in the dough without TYR. TYR also increased the firmness of the dough, which was assumed to be because of the cross-linking of oat globulins. LAC did not affect the oat globulins. TYR alone, or together with a commercial Thermomyces lanuginosus xylanase (XYL), increased significantly the specific volume of the gluten-free oat bread. A combination of TYR and XYL also increased the softness of the bread, whereas a combination of LAC and XYL improved the specific volume but did not affect the softness of oat bread. The results thus indicate that cross-linking of oat globulins by TYR, especially with the addition of XYL, was beneficial for improving the texture of gluten-free oat bread.     

A polymorphism within the G6PC2 gene is associated with fasting plasma glucose levels

Several studies have shown that healthy individuals with fasting plasma glucose (FPG) levels at the high end of the normal range have an increased risk of mortality. To identify genetic determinants that contribute to interindividual variation in FPG, we tested 392,935 single-nucleotide polymorphisms (SNPs) in 654 normoglycemic participants for association with FPG, and we replicated the most strongly associated SNP (rs560887, P = 4 x 10(-7)) in 9353 participants. SNP rs560887 maps to intron 3 of the G6PC2 gene, which encodes glucose-6-phosphatase catalytic subunit-related protein (also known as IGRP), a protein selectively expressed in pancreatic islets. This SNP was associated with FPG (linear regression coefficient beta = -0.06 millimoles per liter per A allele, combined P = 4 x 10(-23)) and with pancreatic beta cell function (Homa-B model, combined P = 3 x 10(-13)) in three populations; however, it was not associated with type 2 diabetes risk. We speculate that G6PC2 regulates FPG by modulating the set point for glucose-stimulated insulin secretion in pancreatic beta cells.     

Endosperm and aleurone cell structure in barley and wheat as studied by optical and Raman microscopy

Grain ultrastructure is of utmost importance when designing grain processing procedures in the food industry. In this study, wheat and barley grain components were localised using optical and Raman microscopy. The optical microscopic analyses were performed using several selective stains to localise β-glucan, protein and starch or autofluorescence to image the ferulic acid and other fluorescing substances. Alternatively, Raman microscopy was applied to localise the grain components without any need for preceding staining or other sample pretreatment. Both methods provided consistent information on the grain structures, illustrating the distribution of polysaccharides, aromatics and protein in endosperm and aleurone layers. In aleurone layers of both barley and wheat, a distinct difference between the anticlinal and periclinal cell walls was observed. The anticlinal cell walls were enriched with aromatic substances which were present in remarkably lower concentrations in the inner periclinal cell walls but for barley, an even higher concentration in the outer periclinal cell wall was observed. In addition, Raman spectroscopy illustrated the detailed distribution of substances across the aleurone cell walls: β-glucan was adjacent to proteins and it was deficient in the middle lamella whereas arabinoxylan was enriched in the outer cell wall layers and middle lamella.     

Cell-mediated and humoral immune responses in pigs following primary and challenge-exposure to Lawsonia intracellularis

ABSTRACT: To investigate immune responses upon re-infection with Lawsonia intracellularis, local and peripheral humoral and cell-mediated immune responses to primary and challenge inoculations were studied in 22 pigs. Pigs were orally inoculated with virulent L. intracellularis at the age of 5-6 weeks, treated with antibiotics and challenged with a re-inoculation (RE) at the age of 12 weeks. Treatment control (TC) pigs received only the primary inoculation and challenge control (CC) pigs received only the secondary inoculation at 12 weeks of age. Following this regimen, all RE pigs were protected against the re-infection as defined by reduced colonisation and pathology of intestinal mucosa, absence of bacterial shedding and without increase in serum acute phase protein response. In the protected RE pigs, serum IgG responses were variable with both high and low responders. Serum IgA responses were not boosted by the re-inoculation, since identical intestinal IgA responses developed in response to the inoculation in both the susceptible CC pigs and the protected RE pigs. A memory recall cell-mediated immune response developed in RE pigs which was significantly stronger compared to the primary response in age-matched CC pigs as assessed by whole blood IFN-γ assay and by calculation of IFN-γ integrated median fluorescence intensity (iMFI) after flow cytometry. The major IFN-γ producing cells were identified as CD8+ and CD4+CD8+ double positive lymphocytes. The results indicate that cell-mediated immune responses are likely mediators of protective immunity against L. intracellularis, with CD8+ effector cells and CD4+CD8+ double positive memory T cells as main contributors to the antigen-specific IFN-γ production.     

Potential of dry fractionation of wheat bran for the development of food ingredients,part II: Electrostatic separation of particles

Wheat bran is a composite material made of several layers, such as pericarp, testa and aleurone. It could be fractionated into purified fractions, which might either be used as food ingredients, or serve as a starting material for extraction of bioactive compounds. The aim of this work was to evaluate the potential of using electrostatic separation as a way to obtain purified fractions from wheat bran. Ultrafine-ground bran obtained either by cryogenic grinding or by grinding at ambient temperature was used as starting material. The ultrafine bran was then charged by tribo-electrification and introduced in a chamber containing two high voltage electrodes, where bran particles were separated depending on their acquired charge, allowing positively and negatively charged fractions to be collected separately. The particle size distribution, microstructure and biochemical composition of the obtained fractions were studied. The charge of the particles was influenced by their biochemical composition: particles rich in highly branched and cross-linked arabinoxylans (pericarp) were separated from particles rich in β-glucan, ferulic acid and para-coumaric acid (aleurone cell walls). The testa and the intracellular compounds from aleurone were not highly charged, neither positively nor negatively. The most positively charged fraction represented 34% of the initial bran, and contained 62% of the ferulic acid present in the initial bran. The yield of the separation process was good (5.4% loss), and could be further increased.