Enhanced ozone exposure of European beech (Fagus sylvatica) stimulates nitrogen mobilization from leaf litter and nitrogen accumulation in the soil

Abstract

In a lysimeter study with young beech trees, the effects of elevated ozone concentration on the decomposition and fate of nitrogen in ¹⁵N‐labeled leaf litter were analyzed after one growing season. Nitrogen in the litter was dominated by a relatively inert, residual fraction, but easily decomposable nitrogen was present in substantial amounts. Nitrogen loss was significantly higher at twice‐ambient ozone which was largely attributed to an enhanced mobilization of residual nitrogen. Enhanced mobilization of nitrogen from litter at twice‐ambient ozone exposure resulted in additional ¹⁵N incorporation into the soil down to 30 cm depth. Only 0.41–0.62% of the nitrogen in the litter was incorporated into plant material at both ozone concentrations. Twice‐ambient ozone exposure changed the distribution of the nitrogen taken up from litter inside the beech trees in favor of the shoot, where it may have been used in biosynthetic processes required for defense reactions.     

Anti-salmonella properties of kefir yeast isolates: An in vitro screening for potential infection control

The rise of antibiotic resistance has increased the need for alternative ways of preventing and treating enteropathogenic bacterial infection. Various probiotic bacteria have been used in animal and human. However, Saccharomyces boulardii is the only yeast currently used in humans as probiotic. There is scarce research conducted on yeast species commonly found in kefir despite its claimed potential preventative and curative effects. This work focused on adhesion properties, and antibacterial metabolites produced by Kluyveromyces lactis and Saccharomyces unisporus isolated from traditional kefir grains compared to Saccharomyces boulardii strains. Adhesion and sedimentation assay, slide agglutination, microscopy and turbidimetry assay were used to analyze adhesion of Salmonella Arizonae and Salmonella Typhimurium onto yeast cells. Salmonella growth inhibition due to the antimicrobial metabolites produced by yeasts in killer toxin medium was analyzed by slab on the lawn, turbidimetry, tube dilution and solid agar plating assays. Alcohol and antimicrobial proteins production by yeasts in killer toxin medium were analyzed using gas chromatography and shotgun proteomics, respectively. Salmonella adhered onto viable and non-viable yeast isolates cell wall. Adhesion was visualized using scanning electron microscope. Yeasts-fermented killer toxin medium showed Salmonella growth inhibition. The highest alcohol concentration detected was 1.55%, and proteins with known antimicrobial properties including cathelicidin, xanthine dehydrogenase, mucin-1, lactadherin, lactoperoxidase, serum amyloid A protein and lactotransferrin were detected in yeasts fermented killer medium. These proteins are suggested to be responsible for the observed growth inhibition effect of yeasts-fermented killer toxin medium. Kluyveromyces lactis and Saccharomyces unisporus have anti-salmonella effect comparable to Saccharomyces boulardii strains, and therefore have potential to control Salmonella infection.     

Adjuvanted oral vaccines should not induce allergic responses to dietary antigens

Oral vaccines may contain adjuvants which might elicit allergies against dietary proteins. Four antigens were used to measure such an effect--ovalbumin, soya bean protein, lactalbumin and gluten. Neither guinea pigs nor mice showed IgE responses after oral administration of adjuvanted vaccines containing lactalbumin and gluten. No IgE responses were detected in mice with any of these antigens after oral immunization, but, in the guinea pig, nine out of 18 animals reacted to either ovalbumin or soya bean protein and none reacted to lactalbumin and gluten. It is concluded that the risk of allergy induction against normal dietary proteins is low but such tests should be applied to potential adjuvanted oral vaccines to measure any possible contraindication, especially with atopic individuals.     

Selection and Identification of Aptamers Against B Cell Activating Factor

Systemic lupus erythematosus (SLE) is the most common autoimmune disease in China. B cell activating factor (BAFF) is an important target for the treatment and detection of SLE. It is of great significance to develop novel molecular recognition elements with high affinity for BAFF. In this study, artificial nucleic acid aptamers against BAFF were screened from a 78 nt single-stranded DNA random library by systematic evolution of ligands exponential enrichment (SELEX) in vitro based on several selection and amplification steps. Through ten rounds of selection, the aptamers with high specificity and affinity for BAFF were identified. After high-throughput sequencing, several aptamers were selected and further examined for binding affinity and specificity. The investigation by dot blotting, Eastern blotting analyses and enzyme-linked oligonucleotide assay (ELONA) showed that the aptamers Apt 7 and Apt 12 with dissociation constants of 241.00±19.75 nmol/L and 413.51±46.94 nmol/L were able to recognize BAFF specifically. After molecular docking analysis, Apt 7 was truncated to Apt 7～1, and the dissociation constant was 192.10±28.61 nmol/L. A sandwich ELONA using Apt 7～1 and BAFF antibodies was established to detect BAFF. The detection limit was estimated to be 0.227 nmol/L. This study provides new molecular recognition elements for the detection of BAFF and the study of antagonists.     

Glycoproteomics Landscape of Asymptomatic and Symptomatic Human Alzheimer’s Disease Brain

Molecular changes in the brain of individuals afflicted with Alzheimer's disease (AD) are an intense area of study. Little is known about the role of protein abundance and posttranslational modifications in AD progression and treatment, in particular large-scale intact N-linked glycoproteomics analysis. To elucidate the N-glycoproteome landscape, we developed an approach based on multi-lectin affinity enrichment, hydrophilic interaction chromatography, and LC-MS–based glycoproteomics. We analyzed brain tissue from 10 persons with no cognitive impairment or AD, 10 with asymptomatic AD, and 10 with symptomatic AD, detecting over 300 glycoproteins and 1900 glycoforms across the samples. The majority of glycoproteins have N-glycans that are high-mannosidic or complex chains that are fucosylated and bisected. The Man5 N-glycan was found to occur most frequently at >20% of the total glycoforms. Unlike the glycoproteomes of other tissues, sialylation is a minor feature of the brain N-glycoproteome, occurring at <9% among the glycoforms. We observed AD-associated differences in the number of antennae, frequency of fucosylation, bisection, and other monosaccharides at individual glycosylation sites among samples from our three groups. Further analysis revealed glycosylation differences in subcellular compartments across disease stage, including glycoproteins in the lysosome frequently modified with paucimannosidic glycans. These results illustrate the N-glycoproteomics landscape across the spectrum of AD clinical and pathologic severity and will facilitate a deeper understanding of progression and treatment development.     

Recent Advances in the Development of a Diagnostic Test for Irradiated Foodstuffs

Recent advances in the development and application of diagnostic tests for irradiated foodstuffs are reviewed. Exposure of water, the major chemical constituent of most foodstuffs to a source of ionising radiation initially generates the highly reactive radical species H', -OH and e^- (aq) which react very rapidly with a wide variety of biological molecules. The detection of foodstuffs subjected to irradiation processing requires the identification and/or quantification of ‘unnatural’ chemical species (i.e. those not usually formed by normal metabolic processes) produced by the attack of ·OH radical or e^-(aq) on suitable ‘target’ molecules. Modern methods for the analysis of a series of these ‘unnatural’ products arising from the interaction of radiolytically-generated ·OH radical or e^-(aq) with polyunsaturated fatty acids, DNA, aromatic compounds and other biologically important scavenger molecules are examined. It is concluded that the analytical test to be conducted is highly dependent on the nature of the foodstuff to be tested.     

Dopamine signaling in food addiction: role of dopamine D2 receptors

Dopamine (DA) regulates emotional and motivational behavior through the mesolimbic dopaminergic pathway. Changes in DA signaling in mesolimbic neurotransmission are widely believed to modify reward-related behaviors and are therefore closely associated with drug addiction. Recent evidence now suggests that as with drug addiction, obesity with compulsive eating behaviors involves reward circuitry of the brain, particularly the circuitry involving dopaminergic neural substrates. Increasing amounts of data from human imaging studies, together with genetic analysis, have demonstrated that obese people and drug addicts tend to show altered expression of DA D2 receptors in specific brain areas, and that similar brain areas are activated by food-related and drug-related cues. This review focuses on the functions of the DA system, with specific focus on the physiological interpretation and the role of DA D2 receptor signaling in food addiction. [BMB Reports 2013; 46(11): 519-526]