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PubMed2001

Determination of cellular carbohydrates in peanut fungal pathogens and baker's yeast by capillary electrophoresis and electrochromatography.

In this work, the quantitation of cellular carbohydrates, namely chitin and glucan, in peanut fungal pathogens and baker's yeast was carried out by capillary electrophoresis (CE) and capillary electrochromatography (CEC). The chitin and glucan of the fungi were hydrolyzed by the enzymes chitinase and glucanase, respectively, to their corresponding sugar monomers N-acetylglucosamine (GlcNAc) and glucose (Glc). These two monosaccharides were then tagged with 6-aminoquinoline (6-AQ) to allow their separation and detection in CE and CEC. The 6-AQ derivatives of GlcNAc and Glc formed the basis for the determination by CE and CEC of chitin and glucan in peanut fungi and baker's yeast. Several parameters affecting the separation of the 6-AQ derivatives of GlcNAc and Glc, including the separation voltage and the composition of the running electrolyte, were investigated. Under the optimized separation conditions, the contents of cellular carbohydrates including N-acetylglucosamine, chitin, glucose, and glucan in some fungi, such as Sclerotinia minor, Sclerotium rolfsii, and baker's yeast, were successfully determined. The method described here allowed the assessment of genetic differences in Sclerotium rolfsii isolates from various locations.

Arachis↗
PubMed2004

A rapid aflatoxin B1 ELISA: development and validation with reduced matrix effects for peanuts, corn, pistachio, and Soybeans.

Among the competitive ELISAs for aflatoxins that have been described, few have been adequately validated for reduced matrix effects. Using an aflatoxin B(1) (AFB(1))-specific polyclonal antibody (produced from AFB(1)-oxime conjugated to bovine serum albumin (BSA)) and AFB(1)- and AFB(2)-enzyme conjugates, four direct competitive ELISAs based on 96-microwell plates (two standard assays and two rapid assays) were developed, paying special attention to producing a robust assay relatively free of interferences for a range of agricultural products. The antibody was AFB(1)-specific, detecting only AFB(1) in a mixture of four aflatoxins (AFB(1), AFB(2), AFG(1), and AFG(2)), but showed significant cross-reaction with AFG(1) (57-61%) when an individual compound was tested. Standard assays (long assays) exhibited higher sensitivities than rapid assays (short assays) with IC(50) values of 12 +/- 1.5 and 9 +/- 1.5 microg/kg in sample (with 1 in 5 dilution of sample extract) for AFB(1) and AFB(2)-enzyme conjugates, respectively. These assays have narrower detection ranges (7.1-55.5 microg/kg in sample) and required dilution of sample extracts to overcome solvent and matrix interferences, making these assays less ideal as analytical methods. Rapid assays exhibited IC(50) values of 21.6 +/- 2.7 and 12 microg/kg in sample for AFB(1)- and AFB(2)-enzyme conjugates, respectively. These assays have ideally broader detection ranges (4.2-99.9 microg/kg in sample) and showed no methanol effects up to 80% with significantly reduced matrix interferences as a result of the shorter incubation times and increasing the amounts of enzyme conjugate used. Therefore, the rapid assays were formatted to perform without a need for extract dilution. The rapid assays can be completed within 15 min, potentially suitable for receival bays where quick decision-making to segregate low and high contamination is critical. Further validation using the rapid assay with AFB(1)-enzyme conjugate indicated relatively good recoveries of AFB(1) spiked in corn, peanuts, pistachio, and soybeans, which were free from significant matrix effects. It can be concluded that this rapid assay would be suitable for monitoring aflatoxin AFB(1) at current legal maximum residue limits of 10 microg/kg in food such as corn, peanuts, pistachio, and soybeans.

Aflatoxin B1↗
PubMed2005

Sandwich immunoassays for the determination of peanut and hazelnut traces in foods.

People suffering from food allergies are dependent on accurate food labeling, as an avoidance diet is the only effective countermeasure. Even a small amount of allergenic protein can trigger severe reactions in highly sensitized patients. Therefore, sensitive and reliable tests are needed to detect potential cross-contamination. In this paper two fast sandwich immunoassays are described for the determination of peanut (Arachis hypogaea) and hazelnut (Corylus avellana) traces in complex food matrices. Mouse monoclonal antibodies were used as capture antibodies, and labeled rabbit polyclonal antibodies were used as detection antibodies in both assays. The assay time was 30 min in total, and cross-reactivities against a variety of fruits and seeds were found to be in the low 10(-4)% (ppm) level or in some cases not detectable. The recoveries in all tested food matrices ranged from 86 to 127%, and the limits of detection were in the range of 0.2-1.2 mg/kg (ppm) in food for both peanut and hazelnut, respectively.

Allergens↗
PubMed2005

Common physical-chemical properties correlate with similar structure of the IgE epitopes of peanut allergens.

Although many sequences and linear IgE epitopes of allergenic proteins have been identified and archived in databases, structural and physicochemical discriminators that define their specific properties are lacking. Current bioinformatics tools for predicting the potential allergenicity of a novel protein use methods that were not designed to compare peptides. Novel tools to determine the quantitative sequence and three-dimensional (3D) relationships between IgE epitopes of major allergens from peanut and other foods have been implemented in the Structural Database of Allergenic Proteins (SDAP; http://fermi.utmb.edu/SDAP/). These peptide comparison tools are based on five-dimensional physicochemical property (PCP) vectors. Sequences from SDAP proteins similar in their physicochemical properties to known epitopes of Ara h 1 and Ara h 2 were identified by calculating property distance (PD) values. A 3D model of Ara h 1 was generated to visualize the 3D structure and surface exposure of the epitope regions and peptides with a low PD value to them. Many sequences similar to the known epitopes were identified in related nut allergens, and others were within the sequences of Ara h 1 and Ara h 2. Some of the sequences with low PD values correspond to other known epitopes. Regions with low PD values to one another in Ara h 1 had similar predicted structure, on opposite sides of the internal dimer axis. The PD scale detected epitope pairs that are similar in structure and/or reactivity with patient IgE. The high immunogenicity and IgE reactivity of peanut allergen proteins might be due to the proteins' arrays of similar antigenic regions on opposite sides of a single protein structure.

2S Albumins, Plant↗
PubMed2006

Allergen Ara h 1 occurs in peanuts as a large oligomer rather than as a trimer.

Ara h 1, a major peanut allergen, is known as a stable trimeric protein. Nevertheless, upon purification of native Ara h 1 from peanuts using only size exclusion chromatography, the allergen appeared to exist in an oligomeric structure, rather than as a trimeric structure. The oligomeric structure was independent of the salt concentration applied. Subjecting the allergen to anion exchange chromatography induced the allergen to dissociate into trimers. Ammonium sulfate precipitation did not bring about any structural changes, whereas exposing the allergen to hydrophobic interaction chromatography caused it to partly dissociate into trimers, with increasing amounts of trimers at higher ionic strengths. The (partial) dissociation into trimers led to a change in the tertiary structure of the monomeric subunits of the allergen, with the monomers in Ara h 1 oligomers having a more compact tertiary structure compared with the monomers in Ara h 1 trimers. As structural characteristics are important for a protein's allergenicity, this finding may imply a different allergenicity for Ara h 1 than previously described.

Allergens↗
PubMed2000

Characterization of methanol-soluble and methanol-insoluble proteins from developing peanut seed.

The 85% methanol-soluble proteins are known to specifically contribute to the production of flavor of roasted peanut. To determine the nature of the 85% methanol-soluble proteins, they were isolated from the peanut seed, and the 85% methanol-soluble (MS) and 85% methanol-insoluble (MIS) fractions were characterized using polyacrylamide gel electrophoresis (PAGE) and capillary electrophoresis. The results showed that the 85% MS fraction contained lower amounts (9-10%) of protein than the MIS fraction (15-33%). Protein content of the MIS fraction increased more significantly during seed maturation than it did in the MS fraction. Unlike the protein, free amino acids and soluble sugars levels of the MS fraction decreased significantly during seed maturation. The 85% MS fraction contained predominantly low molecular weight (<20 kDa) proteins/polypeptides, whereas the MIS fraction contained a mixture of polypeptides with molecular weight between 14 kDa and 90 kDa. SDS-PAGE showed no major changes in the polypeptide composition of the MS fraction during seed maturation. Capillary electrophoretic analysis revealed major qualitative and quantitative changes in the protein and polypeptide composition of the MS and MIS fractions during seed maturation. Fatty acid analysis of these fractions indicated that the MS fraction is lipoprotein in nature and rich in oleic and linoleic acids.

Amino Acids↗
PubMed2000

One step purification of peanut phospholipase D by precipitation with alginate.

A simple titrimetric assay with soybean lecithin has been used for screening phospholipase D activity from some plant sources, viz. peanut, wheat germ, cabbage and carrot. The enzyme from peanut has been purified by binding to alginate which is a water soluble polymer. The purification consisted of co-precipitation of enzyme with alginate upon addition of 0.06 M Ca++. The enzyme was eluted from the polymer using 0.2 M sodium chloride. The activity recovery was 61% with 34 fold purification.

Alginates↗
PubMed1999

Oral gene delivery with chitosan--DNA nanoparticles generates immunologic protection in a murine model of peanut allergy.

Food allergy is a common and often fatal disease with no effective treatment. We describe here a new immunoprophylactic strategy using oral allergen-gene immunization to modulate peanut antigen-induced murine anaphylactic responses. Oral administration of DNA nanoparticles synthesized by complexing plasmid DNA with chitosan, a natural biocompatible polysaccharide, resulted in transduced gene expression in the intestinal epithelium. Mice receiving nanoparticles containing a dominant peanut allergen gene (pCMVArah2) produced secretory IgA and serum IgG2a. Compared with non-immunized mice or mice treated with 'naked' DNA, mice immunized with nanoparticles showed a substantial reduction in allergen-induced anaphylaxis associated with reduced levels of IgE, plasma histamine and vascular leakage. These results demonstrate that oral allergen-gene immunization with chitosan-DNA nanoparticles is effective in modulating murine anaphylactic responses, and indicate its prophylactic utility in treating food allergy.

2S Albumins, Plant↗
PubMed1999

Specific immunoglobulin E to peanut, hazelnut and brazil nut in 731 patients: similar patterns found at all ages.

BACKGROUND: Previous studies have reported reactions to an increasing range of nuts as patients with nut allergy grow older. Most patients with symptoms suggesting nut allergy have specific IgE to more than one nut. Furthermore, fatal reactions have followed eating nuts different from any causing the deceased's previous reactions. OBJECTIVE: To explore the pattern of specific IgE to three distantly related nuts in patients of all ages with nut allergy. METHODS: This study includes all patients referred to our laboratory for nut allergy testing from January 1994 to August 1998 who were tested for peanut, hazelnut and brazil nut, and had specific IgE to at least one of these nuts. All tests were performed using the Pharmacia Unicap system. RESULTS: Seven hundred and thirty-one patients (age 7 months to 65 years, median 6.6 years) had specific IgE >0.35 kU(A)/L to at least one of these three nuts: 282 had IgE to one nut, 130 to two nuts, and 319 to all three nuts. When analysed by gender and age quartile, very similar patterns were found in all subgroups though significant age trends and age interactions were found for IgE to individual nuts and combinations of nuts. CONCLUSIONS: The probability of a patient with nut allergy having specific IgE to a particular combination of peanut, hazelnut and brazil nut is similar, whatever their age or sex. The apparent increase in multiple nut reactivity with increasing age may therefore be due to exposure of previously unchallenged sensitivity. The frequency of multiple-nut specificity is sufficiently high that patients should always be tested for allergy to a range on nuts if they have a history of reacting to any nut.

Adolescent↗
PubMed2003

Transformation of peanut using a modified bacterial mercuric ion reductase gene driven by an actin promoter from Arabidopsis thaliana.

In order to test an alternative selectable marker system for the production of transgenic peanut plants (Arachis hypogaea), the bacterial mercuric ion reductase gene, merA, was introduced into embryogenic cultures via microprojectile bombardment. MerA reduces toxic Hg(II) to the volatile and less toxic metallic mercury molecule, Hg(0), and renders its source Gram-negative bacterium mercury resistant. A codon-modified version of the merA gene, MerApe9, was cloned into a plant expression cassette containing the ACT2 promoter from Arabidopsis thaliana and the NOS terminator. The expression cassette also was inserted into a second vector containing the hygromycin resistance gene driven by the UBI3 promoter from potato. Stable transgenic plants were recovered through hygromycin-based selection from somatic embryo tissues bombarded with the plasmid containing both genes. However, no transgenic somatic embryos were recovered from selection on 50-100 micromol/L HgCl2. Expression of merA as mRNA was detected by Northern blot analysis in leaf tissues of transgenic peanut, but not in somatic embryos. Western blot analysis showed the production of the mercuric ion reductase protein in leaf tissues. Differential responses to HgCl2 of embryo-derived explants from segregating R1 seeds of one transgenic line also were observed.

Actins↗
PubMed2001

Differences detected in vivo between samples of aflatoxin-contaminated peanut meal, following decontamination by two ammonia-based processes.

A sample of peanut meal, highly contaminated with aflatoxins, has been subjected to decontamination by two commercial ammonia-based processes. The original contaminated and the two decontaminated meals were fed to rats for 90 days. No lesions associated with aflatoxin-induced hepatocarcinogenesis were detected histologically following feeding with the two detoxified meals. There were, however, clear differences between the two meals in respect of growth rates of the rats. In addition, feeding one of the detoxified meals resulted in hepatic abnormalities detected using novel immunohistochemical reagents. Differences between the two detoxified meals were also indicated by the results of studies using meals 'spiked' with [14C]-aflatoxin B1 prior to being subjected to the detoxification processes. The meals differed in the bioavailability of the label. It was concluded that peanut meal where an initial, unacceptable level of contamination with aflatoxins had been reduced by two ammonia-based processes to comparable, acceptable levels, may still have different effects in vivo when incorporated into animal diets.

Aflatoxins↗
PubMed2001

Genotoxicity testing of extracts from aflatoxin-contaminated peanut meal, following chemical decontamination.

One of the most important concerns in the decontamination of aflatoxin-containing feed commodities is the safety of the products for food-producing animals and for human consumption of products derived from these animals. A new method, based on the use of florisil and C18 solid phase extraction columns, was developed for the preparation of extracts from decontaminated peanut meal, which allowed testing with in vitro genotoxicity assays without interference of the residual aflatoxin B1. Recovery of degradation products in the extracts was evaluated by the use of radiolabelled [14C]-aflatoxin B1 (AFB1) added to naturally-contaminated peanut meal (3.5 mg AFB1/kg). The meal was treated by a small-scale version of an industrial decontamination process based on ammoniation. Following decontamination, more than 90% of the label could not be extracted from the meal. AFB1 accounted for about 10% of the radiolabel present in the extractable fraction, indicating a total AFB1 reduction of more than 99%. Decontamination of the meal by a number of other small- and industrial-scale ammonia-based processes resulted in similar efficiencies. Application of the extraction procedure resulted in AFB1-rich and AFB1-poor fractions, the latter containing half of the extractable decontamination products but less than 1% of the residual AFB1. Testing in the Salmonella/microsome mutagenicity assay (TA 100, with S9-mix) of the original crude extracts and AFB1-rich fractions prepared from non-treated and decontaminated meal, showed the positive results expected from the AFB1 contents as determined by HPLC analysis. Analysis and testing of the AFB1-poor fractions showed that the various decontamination processes not only resulted in a successful degradation of AFB1 but also did not produce other potent mutagenic compounds. Slight positive results obtained with these extracts were similar for the untreated and treated meals and may be due to unknown compounds originally present in the meal. Results obtained with an unscheduled DNA synthesis (UDS) and Comet assay with rat hepatocytes supported this conclusion. Positive results obtained with the micronucleus assay, using immortalized mouse hepatocytes (GKB), did not clearly reflect the mycotoxin levels and require further examination. It is concluded that the newly developed extraction procedure yields highly reproducible fractions and hence is very suitable for examining the possible formation of less potent degradation products of aflatoxins in short-term genotoxicity tests.

Aflatoxins↗
PubMed2005

Multi-allergen screening immunoassay for the detection of protein markers of peanut and four tree nuts in chocolate.

A multiresidue enzyme immunoassay was developed to check for the presence of markers of peanut, hazelnut, almond, cashew and Brazil nuts in a single run. The assay was designed under the competitive indirect format and adapted for screening purposes applied to chocolate samples. The limit of detection for this assay was below 1 microg g-1 protein for each allergenic food. In most cases, the high specificity of the antibodies used allowed the identification of each particular allergenic food with no possible confusion. This assay was proven to be useful as part of an analytical procedure involving the identification of the unknown allergenic food among peanut and other tree nuts in recalled samples before the application of a quantitative technique to determine the level of cross-contamination.

Allergens↗
PubMed2006

Co-occurrence of aflatoxin B1, fumonisin B1, ochratoxin A and zearalenone in cereals and peanuts from Côte d'Ivoire.

This survey examined 30 samples of rice (n = 10), maize (n = 10) and peanuts (n = 10) from Côte d'Ivoire for aflatoxin B1, fumonisin B1 and zearalenone using immunoassays, and ochratoxin A using a validated HPLC method with fluorescence detection. In Côte d'Ivoire, as in other countries, several mycotoxins are present in the same commodities. These mycotoxins are from different structural families: aflatoxin B1, fumonisin B1, zearalenone and ochratoxin A, normally produced by fungal species from Aspergillus, Penicillium and Fusarium genera. Some samples contained four mycotoxins (86%). Four peanuts samples did not show ochratoxin A (14%), whereas they contained aflatoxin B1 concentrations above the EU regulatory limits. Concentrations of ochratoxin A, zearalenone and fumonisin B1 were low and may not cause problems per se; however, fears remain that the tolerable daily intake may be exceeded due to eating habits and synergistic effects could be important with the combination of several mycotoxins. Investigations in this direction are underway, together with isolation and characterization of the fungal species involved.

Aflatoxin B1↗
PubMedDate not supplied

Enzyme-linked immunosorbent (ELISA) determination of aflatoxin B1 in peanut butter: collaborative trial.

Fourteen laboratories in the United Kingdom participated in a collaborative trial of a commercially available ELISA test kit for the determination of aflatoxin B1 in peanut butter. Each laboratory carried out six replicate analyses of each of six individual samples. Collaborators received a control, uncontaminated sample, together with samples prepared by blending naturally-contaminated and control material to give target levels of 8 micrograms/kg, 25 micrograms/kg and 75 micrograms/kg. Two of these samples (8 micrograms/kg and 25 micrograms/kg) were supplied as undisclosed duplicates. The repeatabilities of the assay ranged from 6.2 to 16.7 micrograms/kg. The reproducibilities for aflatoxin B1 concentrations in naturally-contaminated samples ranged from 3.6 to 18.7 micrograms/kg using uncontaminated peanut butter as a reference blank. Modifications to the format of the commercial kit were recommended as a result of the collaborative trial.

Aflatoxin B1↗
PubMedDate not supplied

Mycological evaluation of chemically-treated unshelled peanuts.

In the present work, the effect of propionic acid (ammonium salt) at 3000 mg/kg of unshelled peanuts (PA1) and at 5000 mg/kg (PA2), grapefruit seed extract at 5000 mg/kg (GF1) and 10,000 mg/kg (GF2), sodium orthophenylphenate at 2500 mg/kg (SOP1) and at 5000 mg/kg (SOP2) and thiabendazole at 1000 mg/kg (TBZ1) and at 5000 mg/kg (TBZ2) was studied for controlling total and potentially aflatoxigenic fungi in unshelled peanuts (UP). Samples of sound mature UP were moistened by adding water and kept refrigerated till they reached ca 16% moisture. The samples were then sprayed with the chemical solutions and incubated at 30 +/- 2 degrees C for 28 days. Control samples were sprayed with water. An evaluation of total and aflatoxigenic fungi was made, in pods of UP and in kernels obtained aseptically, before and at 7, 14, 21 and 28 days of incubation, by serial dilution in culture media Dichloran Rose Bengal Chloramphenicol (total fungi count) and in Aspergillus flavus parasiticus Agar (potentially aflatoxigenic count). In relation to the period and conditions of this experiment the overall best treatment was PA2, when the lowest average value of total and aflatoxigenic fungi were obtained in UP and were maintained in its kernels. Although SOP2 treatment could control fungal contamination in pods, it was not effective in controlling contamination through the kernels. The other treatments were ineffective.

Arachis↗
PubMedDate not supplied

Laboratory evaluation of chemical control of aflatoxin production in unshelled peanuts (Arachis hypogaea L.).

Propionic acid (ammonium salt) at 3000 mg/kg (PA1) and 5000 mg/kg (PA2) of unshelled peanuts (UP); grapefruit seed extract at 5000 mg/kg (GF1) and 10,000 mg/kg (GF2); sodium orthophenylphenate at 2500 mg/kg (SOP1) and 5000 mg/kg (SOP2); thiabendazole 1000 mg/kg (TBZ1) and 5000 mg/kg (TBZ2) were studied in the laboratory, to verify their efficiency in controlling fungal growth and aflatoxin (AF) production on moist UP (16-18% moisture content). Moist UP were put into polyethylene bags with cotton plugs and incubated at 30 +/- 2 degrees C for 28 days. Treatments were considered efficient when the AF content (B1 + G1) remained under 30 micrograms/kg. PA1 treatment was efficient till 14 days of incubation and PA2 during the whole incubation period (28 days). All other treatments were not efficient, showing AF contents from 150 to 108,333 micrograms/kg during the incubation periods. Propionic acid, used as ammonium propionate, at 5000 mg/kg shows promise in controlling aflatoxin production when applied to moist unshelled peanuts.

Aflatoxins↗
PubMed1998

Partial characterization of the lipopolysaccharides of peanut specific Bradyrhizobium strains.

Hexoses, heptose, hexuronic acids, 2-keto-3-deoxyoctonic acid (Kdo) contents of the lipopolysaccharides (LPS) isolated from peanut (A. hypogaea) specific Bradyrhizobium strains NC 92, IGR 92, IGR 40 and IGR 6 were found to vary considerably. Sodium dodecyl sulphate polyacrylamide gel electrophoresis showed a heterogeneous LPS population and distinct heterogeneity was observed in NC and IGR strains. Sepharose gel filtration chromatography removed the hexose contaminants from NC 92 LPS. Polysaccharides obtained by mild acid hydrolysis of Sepharose purified NC 92 LPS were further purified on Sephadex G-50 gel filtration. Immunoblot analysis indicated cross reactivity amongst the peanut specific Bradyrhizohium strains but not with B. japonicum(SB 16). Antibodies raised against native NC 92 LPS showed higher binding towards the Sephadex purified polysaccharides suggesting the antigenic property of polysaccharide moiety in LPS molecule.

Arachis↗