Purification and characterization of vanilla bean (Vanilla planifolia Andrews) beta-D-glucosidase

Vanilla bean beta-D-glucosidase was purified to apparent homogeneity by successive anion exchange, hydrophobic interaction, and size-exclusion chromatography. The enzyme is a tetramer (201 kDa) made up of four identical subunits (50 kDa). The optimum pH was 6.5, and the optimum temperature was 40 degrees C at pH 7.0. K(m) values for p-nitrophenyl-beta-D-glucopyranoside and glucovanillin were 1.1 and 20.0 mM, respectively; V(max) values were 4.5 and 5.0 microkat.mg(-1). The beta-D-glucosidase was competitively inhibited by glucono-delta-lactone and 1-deoxynojirimycin, with respective K(i) values of 670 and 152 microM, and not inhibited by 2 M glucose. The beta-D-glucosidase was not inhibited by N-ethylmaleimide and DTNB and fully inhibited by 1.5-2 M 2-mercaptoethanol and 1,4-dithiothreitol. The enzyme showed decreasing activity on p-nitrophenyl-beta-D-fucopyranoside, p-nitrophenyl-beta-D-glucopyranoside, p-nitrophenyl-beta-D-galactopyranoside, and p-nitrophenyl-beta-D-xylopyranoside. The enzyme was also active on prunasin, esculin, and salicin and inactive on cellobiose, gentiobiose, amygdalin, phloridzin, indoxyl-beta-D-glucopyranoside, and quercetin-3-beta-D-glucopyranoside.     

Antioxidant activity of cysteine, tryptophan, and methionine residues in continuous phase beta-lactoglobulin in oil-in-water emulsions

Proteins dispersed in the continuous phase of oil-in-water emulsions are capable of inhibiting lipid oxidation reactions. The antioxidant activity of these proteins is thought to encompass both free radical scavenging by amino acid residues and chelation of prooxidative transition metals; however, the precise mechanism by which this occurs remains unclear. In this study, the oxidative stability of cysteine, tryptophan, and methionine residues in continuous phase beta-lactoglobulin (beta-Lg) in a Brij-stabilized menhaden oil-in-water emulsion was determined. The presence of low concentrations of continuous phase beta-Lg (250 and 750 microg/mL) significantly inhibited lipid oxidation as determined by lipid hydroperoxides and thiobarbituric acid reactive substances analysis. It was observed that cysteine oxidized before tryptophan in beta-Lg, and both residues oxidized before lipid oxidation could be detected. No oxidation of the methionine residues of beta-Lg was observed despite its reported high oxidative susceptibility. It is conceivable that surface exposure of amino acid residues greatly affects their oxidation kinetics, which may explain why some residues are preferentially oxidized relative to others. Further elucidation of the mechanisms governing free radical scavenging of amino acids could lead to more effective applications of proteins as antioxidants within oil-in-water food emulsions.     

Importance of rhizodeposition in the coupling of plant and microbial productivity

Plant roots influence the biological, chemical and physical properties of rhizosphere soil. These effects are a consequence of their growth, their activity and the exudation of organic compounds from them. In natural ecosystems, the linkages between inputs of carbon from plants and microbial activity driven by these inputs are central to our understanding of nutrient cycling in soil and the productivity of these systems. This coupling of plant and microbial productivity is also of increasing importance in agriculture, where the shift towards low‐input systems increases the dependence of plant production on nutrient cycling, as opposed to fertilizers. This review considers the processes by which plants can influence the cycling of nutrients in soil, and in particular the importance of organic inputs from roots in driving microbially mediated transformations of N. This coupling of plant inputs to the functioning of the microbial community is beneficial for acquisition of N by plants, particularly in low‐input systems. This occurs through stimulation of microbes that produce exoenzymes that degrade organic matter, and by promoting cycling of N immobilized in the microbial biomass via predation by protozoa. Also, plants increase the cycling of N by changes in exudation in response to nitrogen supply around roots, and in response to browsing by herbivores. Plants can release compounds in exudates that directly affect the expression of genes in microbes, and this may be an important way of controlling their function to the benefit of the plant.     

BIOREGULATORS INFLUENCE CALCIUM CONCENTRATION AND COLD HARDINESS OF YOUNG ‘DELICIOUS’ (MALUS DOMESTICA,BORKH) APPLE TREES

Calcium concentration and cold hardiness in woody shoots of young ‘Delicious’ apple trees increased during the first half of the dormant season by early-fall whole-tree application of bioregulators and/or plant protectant. Compared with untreated controls, the plant protectant, α-[(1,3-dioxolan-2-ylmethoxy) imino] benzene acetonitcile [Hytech Polymer, (formerly ProTec^TM), Agro-K, Corp., Minneapolis, MN, USA] applied in September at 5 or 10% induced more cold hardiness in late October and November, whereas treating at 0.05% with the bioregulator, 2-chloroethyl-methyl-bis(phenylmethoxy)silane [CGA-15281, Novartis International AG, (formerly Ciba-Geigy Limited) Basel, Switzerland], induced greater cold hardiness and higher woody tissue calcium concentration in November and December. Applied in October, CGA-15281 resulted in woody tissue with the highest cold hardiness rating from November through March. From October 28 through 8 December, tissue from control trees had the lowest calcium concentration and frequently the least amount of cold hardiness. In woody stems of young apple trees, cold hardiness was more closely related to calcium concentration than that of the other eleven measured mineral elements; this was especially apparent from November to March (r = ?0.856).     

Clopyralid and Compost: Formulation and Mowing Effects on Herbicide Content of Grass Clippings

The presence of clopyralid, a selective broadleaf herbicide, in compost near Spokane, Washington in 2000 was attributed to grass clippings collected from area lawns and subsequently used as compost feedstock. A field study was conducted in 2001 to evaluate the effects of herbicide formulation and mowing practice on the clopyralid content of grass clippings. The objective was to develop guidelines that would limit the concentration of clopyralid in clippings, thereby reducing the amount of clopyralid entering the compost production stream. Clopyralid was applied to turfgrass as either a sprayable (S) or granular (G) formulation. Grass clippings were either collected in a bagging lawn mower and removed from the plots or returned into the plant canopy using a mulching mower designed to finely chop and disperse the leaf blades. Clippings were sampled for a period of ten weeks after application, and again in the summer of 2002, and analyzed for clopyralid content. Mowing treatment had no significant effect on clopyralid content of grass clippings. The S formulation resulted in higher concentration than the G at 4 hours after treatment (193 mg kg^?1 and 53 mg kg^?1, respectively). At 10 weeks after treatment (WAT), clopyralid concentration averaged 0.9 mg kg^?1, and cumulative recovery of clopyralid in grass clippings was 35% and 29% of the amount applied for the S and G formulations, respectively. By 56 and 98 WAT, clopyralid concentration in clippings was 0.06 and 0.02 mg kg^?1, respectively. Based on these results, and depending on feedstock dilution and composting conditions, a waiting period of up to one year after application of clopyralid could be necessary for treated grass clippings to be safely used as compost feedstock.     

Therapeutic Potential of Hemoglobin Derived from the Marine Worm Arenicola marina (M101): A Literature Review of a Breakthrough Innovation

Oxygen (O₂) is indispensable for aerobic respiration and cellular metabolism. In case of injury, reactive oxygen species are produced, causing oxidative stress, which triggers cell damaging chemical mediators leading to ischemic reperfusion injuries (IRI). Sufficient tissue oxygenation is necessary for optimal wound healing. In this context, several hemoglobin-based oxygen carriers have been developed and tested, especially as graft preservatives for transplant procedures. However, most of the commercially available O₂ carriers increase oxidative stress and show some adverse effects. Interestingly, the hemoglobin derived from the marine lugworm Arenicola marina (M101) has been presented as an efficient therapeutic O₂ carrier with potential anti-inflammatory, anti-bacterial, and antioxidant properties. Furthermore, it has demonstrated promise as a supplement to conventional organ preservatives by reducing IRI. This review summarizes the properties and various applications of M101. M101 is an innovative oxygen carrier with several beneficial therapeutic properties, and further research must be carried out to determine its efficacy in the management of different pathologies.     

Chemical composition of silage residues sustaining the larval development of the Culicoides obsoletus/Culicoides scoticus species (Diptera: Ceratopogonidae)

Culicoides (Diptera: Ceratopogonidae) are biological vectors of bluetongue virus (BTV). Bluetongue is a viral disease that affects domestic and wild ruminants. Since its recent emergence in northern Europe, this disease has caused considerable economic losses to the sheep and cattle industry. The biotopes, and more particularly the chemical characteristics which are suitable for larval development of the main vector species, are still relatively unknown. This study shows that the larvae of biting midges belonging to the species Culicoides obsoletus and Culicoides scoticus are able to breed in different types of silage residue (maize, grass, sugar beet pulp and their combinations). The chemical composition of substrates strongly influences the presence of the immature stages of these biting midges. Higher lignin and insoluble fibre contents seem to favour their presence and could play the role of a physical support for semi-aquatic larvae. In contrast, higher concentrations of magnesium and calcium are negatively correlated with the presence of these two species. These data will help to locate and monitor the breeding sites of these species and could contribute to the control of these insects on farms.     

Serologic Responses of West Nile Virus Seronegative Mature Horses to West Nile Virus Vaccines

A 42-day study was conducted to assess the impact of three West Nile virus vaccines given either as separate injections or incorporated with their counterpart equine encephalitis and tetanus vaccines on serological responses under field use conditions. Two hundred forty mature, West Nile virus seronegative (<4) horses were followed serologically pre- and postprimary and secondary vaccination with six different vaccination programs, all including West Nile virus antigens. Forty horses were unvaccinated sentinel horses. All vaccines stimulated both a primary and secondary (booster) response to vaccination that was significantly higher than that of seronegative controls. However, inclusion of West Nile virus with equine encephalitis viruses and tetanus toxoid in vaccines had a significant detrimental impact on West Nile virus serum neutralization antibody production to both the primary and secondary vaccinations.