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Molecular cloning, recombinant expression and IgE-binding epitope of omega-5 gliadin, a major allergen in wheat-dependent exercise-induced anaphylaxis.

Wheat omega-5 gliadin has been identified as a major allergen in wheat-dependent exercise-induced anaphylaxis. We have detected seven IgE-binding epitopes in primary sequence of the protein. We newly identified four additional IgE-binding epitope sequences, QQFHQQQ, QSPEQQQ, YQQYPQQ and QQPPQQ, in three patients with wheat-dependent exercise-induced anaphylaxis in this study. Diagnosis and therapy of food allergy would benefit from the availability of defined recombinant allergens. However, because omega-5 gliadin gene has not been cloned, recombinant protein is currently unavailable. We sought to clone the omega-5 gliadin gene and produce the homogeneous recombinant protein for use in an in vitro diagnostic tool. Using a PCR-based strategy we isolated two full-length omega-5 gliadin genes, designated omega-5 and omega-5b, from wheat genomic DNA and determined the nucleotide sequences. The protein encoded by omega-5a was predicted to be 439 amino acids long with a calculated mass of 53 kDa; the omega-5b gene would encode a 393 amino acid, but it contains two stop codons indicating that omega-5b is pseudogene. The C-terminal half (178 amino acids) of the omega-5a gliadin protein, including all 11 IgE-binding epitope sequences, was expressed in Escherichia coli by means of the pET system and purified using RP-HPLC. Western blot analysis and dot blot inhibition assay of recombinant and native omega-5 gliadin purified from wheat flour demonstrated that recombinant protein had IgE-binding ability. Our results suggest that the recombinant protein can be a useful tool for identifying patients with wheat-dependent exercise-induced anaphylaxis in vitro.

Allergens↗

The Key Trichoderma-Induced Gene Encoding a DUF568 Domain-Containing Protein Mediates Defense Responses in Wheat.

Genes encoding DUF568 domain-containing proteins participate in plant stress adaptation. To elucidate the functional role of DUF568 domain-containing genes in Trichoderma-induced wheat defense responses against wheat Fusarium crown rot, we performed a genome-wide identification and characterization of the TaDUF568 gene family in hexaploid wheat (Triticum aestivum L.). In this study, a total of 33 TaDUF568 family genes were systematically identified and characterized at the genome-wide level, exhibiting uneven chromosomal distribution and diverse physicochemical properties. Phylogenetic, structural, and collinearity analyses revealed conserved family characteristics among monocot species. Segmental duplication was verified as the primary driver of gene family expansion. Expression profiling revealed divergent tissue-specific expression patterns among TaDUF568 family members, among which TaDUF568.18 was strongly induced by Trichoderma M2. Subcellular localization assays confirmed that TaDUF568.18 is a plasma membrane-localized protein. Functional validation via stable transgenes demonstrated that overexpression of TaDUF568.18 restricted lesion expansion, improved agronomic traits, and enhanced disease resistance. This study is the first to characterize the wheat DUF568 family and confirm that TaDUF568.18 (annotated as TaAIR12) acts as a positive regulator of Trichoderma-mediated wheat defense, providing a valuable gene resource for wheat disease-resistance breeding.

DUF568↗

Assessment of exposure to wheat flour and the shape of its relationship with specific sensitization.

OBJECTIVES: Dust and wheat-allergen exposure were assessed among bakers, flour millers, and bakery-ingredient producers, and the risk for sensitization was studied. METHODS: About 520 inhalable dust and wheat-allergen measurements were made among 270 Dutch workers. Data on sensitization to wheat and common allergens (atopy) were also available. Exposure was estimated according to the sector of industry, job title, and tasks. The shape of the relationship between sensitization and exposure was studied using a two-stage modeling approach: semi-parametric generalized additive modeling and, consequently, a simple description of the relationship using a parametric logistic model. To reduce the effect of exposure measurement errors (attenuation), a combination of the actual measured exposure and variance-weighted estimates of exposure was used. Results The effect of exposure to both inhalable dust and wheat allergens on sensitization was described best by a linear relationship in three industries and a quadratic relationship in one industry. The relation for the whole study population was best described as quadratic, and the probability of sensitization increased with exposure up to -2.7 mg/m3 for inhalable dust and approximately 25.7 microg EQ/m3 for wheat allergens. The risk decreased at higher exposures (P = 0.0121 and P = 0.0731 for dust and wheat, respectively). Atopy and sector of industry modified the sensitization risk significantly in all the analyses. Using a variant-weighted estimator to calculate exposures corrected for the bias and resulted in almost the same point risk estimators. Conclusions Exposure-response relationships for allergens may be nonlinear and differ between industries. A threshold is not indicated on which to base occupational exposure standards; alternatively, other approaches, such as benchmarking, seem warranted.

Allergens↗

[Wheat anaphylaxis enhanced by administration of acetylsalicylic acid or by exercise].

A 23-year-old woman experienced generalized urticaria and loss of consciousness during walking after ingestion of wheat. Skin prick test and CAP-RAST were positive for gluten. An oral challenge test using 100g wheat was positive without exercise. The patient was given diagnosis of wheat allergy. In addition, not only exercise but also administration of 500mg aspirin were found to exacerbate her symptoms after the ingestion of wheat, suggesting that acetylsalicylic acid could be an augmentation factor in wheat allergy. Etodorac failed to enhance the symptoms. Further, oral administration of Fexofenadine could prevent allergic reactions induced by ingestion of 100g wheat, but sodium cromoglycate partially reduced the reactions.

Administration, Oral↗

Wheat flour exposure results in recruitment of inflammatory cells in the lungs of healthy individuals.

BACKGROUND: Flour dust in bakeries is known to cause allergic as well as nonallergic respiratory symptoms. Fungal alpha-amylase is a commonly used baking additive that has been shown to have allergenic properties. The aim of this study was to investigate any effects on bronchoalveolar lavage (BAL) cells and peripheral blood lymphocytes (PBL) of healthy individuals exposed to airborne wheat flour dust with or without fungal alpha-amylase added. METHODS: Fifteen subjects were exposed during 1 hr in an exposure chamber, ten individuals to wheat flour alone and five with alpha-amylase added. BAL was performed 2-6 weeks before and 1 day after the exposure. BAL cells were differentially counted and flowcytometric analysis of the expression of activation, adhesion, and subset markers on alveolar macrophages (AM) and T cells in BAL fluid and peripheral blood were carried out. RESULTS: Exposure to wheat flour dust increased the total number of cells in BAL fluid from 75.4 (i.q. range 70.4-104.1) to 127.4 (92.1-187.4) cells x 10(6)/L, P < 0.01. There was a significant difference in the change of total BAL cell concentration between the study group exposed to wheat flour only (n = 10; increase with 91.9 x 10(6)/L) and the group exposed to wheat flour with the baking additive fungal alpha-amylase (n = 5; decrease with 5.4 x 10(6)/L). The exposure level of respirable dust was lower in the group that received alpha-amylase and the increase in BAL cell concentration showed a positive correlation with the concentration of respirable dust in the exposure chamber (r = 0.80, P < 0.001). The phenotypic analysis of AM indicated an influx of monocytic cells. CONCLUSIONS: The results indicate that the concentration of respirable dust, but not alpha-amylase, is of importance for the recruitment of inflammatory cells to the peripheral airways in healthy individuals exposed to wheat flour dust.

Adult↗

Effect of thermal processing on the nutritive value of wheat germ protein.

Wheat germs are used as industrial products for nourishment so that it was necessary to determine the nutritive value of proteins in raw and in roasted wheat germs (temperature: 130-150 degrees C for 20 min). Protein quality evaluation has been determined by a biological method--feeding young growing rats. The rats were fed 10% level protein diets, based on raw and roasted wheat germs. The results show that protein of roasted wheat germs has higher digestibility (D) and protein efficiency ratio (PER) than the raw wheat germs which proves that roasting destroyed digestion enzymes inhibitors. Furthermore, the net protein utilization (NPU) has also been improved by roasting. Biological value (BV) of raw germs approximates to the value of roasted germs. The results lead us to the conclusion that roasting saves and improves protein parameters in wheat germs.

Animals↗

Wheat proteomics: relationship between fine chromosome deletion and protein expression.

To explore the relationship between fine chromosome deletion and protein expression in common wheat, the changes in protein composition of wheat seed proteome were investigated by using chromosome 1B. A momosomic alien chromosome addition line of common wheat was used to produce the fine deletion lines. Endosperm and embryo proteins were separated by two-dimensional gel electrophoresis (2-DE) and visualized by staining with Commassie Brilliant Blue, and gel images were analyzed with a computer assisted image analyzer. For the first time, fine gene locations of a few endosperm and embryo proteins were identified on the chromosome 1B. These proteins with their specific gene location on the chromosome can be used as protein markers in breeding programs for quality of wheat proteins. To identify wheat seed proteins and to understand their expression in relation to chromosome deletion, the feasibility of a new analytical approach based on isotope coded affinity tag labeling (ICAT) of peptides in tryptic digests followed by electrospray ionization mass spectrometry has been described. Simplification of the complex tryptic digest prior to mass spectral analysis was performed by treating the samples with light and heavy ICAT labeling reagents. A clear separation of peptide fragment containing the light and heavy reagents was achieved in mass spectral analysis. Out of the 14 peptides detected by mass fragment analysis of the euploid, four were down-regulated, nine up-regulated and one did not show any change due to the terminal deletion of chromosome 1B. Selected peptide fragments were subjected to tandem mass spectrometry analysis for sequence information and the resulting sequence information was submitted to databases for protein identification. Of the five proteins submitted, four were identified as alpha-amylase inhibitor, alpha-amylase/subtilisin inhibitor precursor, proteasome subunit alpha-type 7 and 1,4 alpha-glucan-D-maltohydrolase. With this approach it is possible to identify wheat seed proteins and to understand their expression, which have been reported to be difficult by 2-DE due to cosynthesis of proteins by genes from three genomes, A, B and D.

Chromosome Deletion↗

Wheat cultivar-specific proteins in grain revealed by 2-DE and their application to cultivar identification of flour.

Wheat flour proteins were studied to identify the cultivar-specific proteins and use them to identify cultivars in flours. Proteins extracted from flours of Japanese wheat (cultivars Hokushin, Horoshirikomugi, Kitanokaori and Kachikei 33) and Canadian wheat (Canada Western Red Spring Wheat No. 1; 1CW) were analyzed by 2-DE with IEF gels over three pH ranges: pH 4-7, pH 5-8, and pH 6-11. This system enabled detection of more than 1600 protein spots. We recognized that among 50 protein spots showing cultivar-dependent qualitative changes, 25 proteins were wheat cultivar specific. These 50 protein spots were analyzed by N-terminal Edman degradation microsequencing and MALDI-TOF-MS; 21 protein spots were storage proteins, such as gliadin and low-molecular mass glutenin subunit. Five protein spots were identified as dehydroascorbate reductase (Triticum aestivum), triticin precursor (T. aestivum), alpha-amylase inhibitor (Oryza sativa), DNA-binding with one finger (Dof) zinc family protein (O. sativa), and nonphototropic hypocotyl 1 (NPH1) protein (Avena sativa). The other protein spots appeared to be hypothetical proteins (O. sativa or Arabidopsis thaliana) or functional unknown proteins. These specific proteins can be used as markers to identify wheat cultivars in blended flour composed of two or three flours.

Electrophoresis, Gel, Two-Dimensional↗

Induction of wheat and maize glutathione S-transferase by some herbicide safeners and their effect on enzyme activity against butachlor and terbuthylazine.

The expression of glutathione S-transferase (GST) activity in wheat and maize shoots was investigated in response to treatments with the herbicide safeners benoxacor, cloquintocet-mexyl, fenchlorazole-ethyl, fenclorim, fluxofenim and oxabetrinil. These safeners significantly enhanced the GST activity towards 1-chloro-2,4-dinitrobenzene (CDNB) as a 'standard' substrate, with the exception of oxabetrinil in maize. The enhancements of GST (CDNB) activity were found to be concomitant with increases in V(max) (the reaction rate when the enzyme is fully saturated by the substrate) in wheat following cloquintocet-mexyl and fenchlorazole-ethyl treatments, and in maize following fenchlorazole-ethyl treatment. Otherwise, decreases in V(max) were observed in wheat and maize following fenclorim and fluxofenim treatments. With the exception of oxabetrinil, all the safeners significantly reduced the apparent K(M) (the substrate concentration required for 50% of maximum GST activity) of both wheat and maize GST. The V(max) and K(M) variations following safener treatments are discussed in terms of an increased expression of GST enzymes and an increased affinity for the CDNB substrate. The activity of wheat and maize GST was also assayed towards butachlor and terbuthylazine respectively; the results indicate the ability of cloquintocet-mexyl, fenchlorazole-ethyl and fluxofenim to enhance the enzyme activity in wheat and of benoxacor and fenchlorazole-ethyl to do so in maize.

Acetanilides↗

Contribution of contact toxicity and wheat condition to mortality of stored-product insects exposed to spinosad.

Spinosad, a reduced-risk commercial insecticide derived from a bacterial fermentation product, possesses both contact and oral toxicities against insects. Contact toxicity of spinosad to adults of Rhyzopertha dominica (F), Sitophilus oryzae (L), and Tribolium castaneum (Herbst) was evaluated by exposure for 24 or 48 h to treated glass Petri dishes. Adults were exposed to different deposits (0.001-0.79 mg cm(-2)) of spinosad in 24-h tests and to deposits of 0, 0.0016 and 0.016mg cm(-2) in 48-h tests. Rhyzopertha dominica was most susceptible to spinosad in 24- and 48-h tests, followed by S. oryzae, and T. castaneum. The 24-h LD50 values were 0.0004, 0.077 and 0.189mg cm(-2) for R. dominica, S. oryzae, and T. castaneum, respectively. All R. dominica adults were dead following 48 h exposure to both spinosad deposits, whereas mortality of S. oryzae and T. castaneum ranged from 10 to 85% and 12 to 48%, respectively. Rhyzopertha dominica, T. castaneum, and O. surinamensis adults were exposed for 14 days to whole wheat, cracked wheat and wheat flour treated with 0, 0.1 and 1.0 mg kg(-1) of spinosad. Rhyzopertha dominica adults were highly susceptible to spinosad, followed by O. surinamensis and T. castaneum. Immatures (eggs and larvae) of T. castaneum and O. surinamensis exposed for 14 days were more susceptible on spinosad-treated whole wheat than on treated cracked wheat and wheat flour. This is the first report documenting contact activity of spinosad, and the effect of grain condition on spinosad toxicity, to stored-product insects.

Animals↗

Management of five stored-product insects in wheat with pirimiphos-methyl and pirimiphos-methyl plus synergized pyrethrins.

Hard red winter wheat was treated with pirimiphos-methyl at 4, 6 and 8 mg kg(-1), synergized pyrethrins at 0.38, 0.75, 1.13 and 1.5 mg kg(-1), and combinations of the two insecticides, to conduct laboratory bioassays against four beetle pests of stored grain, red flour beetle Tribolium castaneum (Herbst), rusty grain beetle Cryptolestes ferrugineus (Stephens), lesser grain borer Rhyzopertha dominica (F), and rice weevil Sitophilus oryzae (L), and one moth pest, Indianmeal moth Plodia interpunctella (Hubner). Beetle adults and P interpunctella larvae survived well on control wheat, producing a large number of progeny (65-1037 insects per container). Kernel damage in control wheat among the insect species ranged from 9 to 99%. On pirimiphos-methyl-treated wheat, mortality of R dominica adults was > or =72%, but that of the other beetle species and P interpunctella larvae was 100%. Progeny were not produced on pirimiphos-methyl-treated wheat, and the kernel damage was negligible (< or =1%). Synergized pyrethrins were ineffective against the five insect pests. Pirimiphos-methyl combined with synergized pyrethrins was not superior to pirimiphos-methyl alone against the five insect pests. Pirimiphos-methyl is not registered in the USA for use on wheat, but our results suggest that it could be a viable grain protectant at rates of 4-8 mg kg(-1).

Animals↗

Identification of plant sterols in hexaploid and tetraploid wheats using gas chromatography with mass spectrometry.

Free sterols from hexaploid and tetraploid free-threshing wheats (Triticum aestivum L. and T. durum Desf.) and from their respective hulled wheats (T. spelta L. and T. dicoccon Schrank) were analysed by gas chromatography with mass spectrometry. The qualitative analysis of sterols showed a similar pattern either between hexaploid (T. aestivum, T. spelta) and tetraploid (T. durum, T. dicoccon) wheats or between free-threshing (T. aestivum, T. durum) and hulled (T. spelta, T. dicoccon) wheats. However, quantitative differences were found between tetraploid and hexaploid wheats, in that free sterol amounts in tetraploid wheats were 40% higher than in hexaploid ones. The mass spectra of the sterols were classified into four groups, taking into account the structural features of rings A and B. Typical mass spectral fragmentations of the four classes, and additional evidence related to the side chain of each molecule, were investigated together with their chromatographic behaviour, allowing identification of all the detected sterols.

Gas Chromatography-Mass Spectrometry↗

Studies on wheat acetyl CoA carboxylase and the cloning of a partial cDNA.

Wheat germ acetyl CoA carboxylase (ACCase) was purified by liquid chromatography and electroelution. During purification bovine serum albumin (BSA) was used to coat Amicon membranes used to concentrate partially pure ACCase. Despite further SDS-PAGE/electroelution and microbore HPLC steps BSA remained associated. This presented serious protein sequencing artefacts which may reflect the affinity of BSA for fatty acids bound to ACCase. To avoid these artefacts the enzyme was digested in gel with Endoproteinase LysC protease without the presence of BSA, and the resulting peptides blotted and sequenced. A partial cDNA (1.85 kb) encoding ACCase from a wheat embryo library was cloned, which hybridised to a 7.5 kb RNA species on northern blot of wheat leaf poly(A)+ RNA. The partial cDNA therefore represents about 0.25 of the full-length cDNA. The clone was authenticated by ACCase peptide sequencing and immuno cross-reactivity of the overexpressed clone. The derived amino acid sequence showed homology with both rat and yeast ACCase sequences (62%). Antibodies raised against wheat acetyl CoA carboxylase were specific for a 220 kDa protein from both wheat embryo and leaf. In addition, by using a novel quick assay for ACCase that utilised 125I-streptavidin, we showed the major biotin containing protein to be 220 kDa in both leaf and germ. This is in marked contrast to the previously published molecular mass of 75 kDa allocated to wheat leaf ACCase.

Acetyl-CoA Carboxylase↗

New 18S.26S ribosomal RNA gene loci: chromosomal landmarks for the evolution of polyploid wheats.

Three new 18S.26S rRNA gene loci were identified in common wheat by sequential N-banding and in situ hybridization (ISH) analysis. Locus Nor-A7 is located at the terminal area of the long arm of 5A in both diploid and polyploid wheats. Locus Nor-B6 is located in N-band 1BL2.5 of the long arm of chromosome 1B in Triticum turgidum and Triticum aestivum. ISH sites, similar to Nor-B6, were also detected on the long arms of chromosomes 1G in Triticum timopheevii and 1S in Aegilops speltoides, but their locations on the chromosomes were different from that of Nor-B6, indicating possible chromosome rearrangements in 1GL and 1BL during evolution. The third new locus, Nor-D8, was only found on the short arm of chromosome 3D in the common wheat Wichita. The loss of rRNA gene locus Nor-A3 and gain of repetitive DNA sequence pSc119 on the terminal part of 5AS suggest a structural modification of 5AS. Comparative studies of the location of the 18S.26S rRNA gene loci in polyploid wheats and putative A and B (G) genome progenitor species support the idea that: (1) Triticum monococcum subsp. urartu is the donor of both the A and A(t) genome of polyploid wheats. (2) Ae. speltoides is closer to the B and G genome of polyploid wheats than Aegilops longissima and is the most probable progenitor of these two genomes.

Biological Evolution↗

[The influence of germination on the nutritional value of wheat, mung beans and chickpeas].

The changes in nutrients during the germination of wheat, mung beans and chickpeas were investigated. Germination was performed under conditions commonly used in the household. The amount of water taken up during 4 days of germination varied from 159 g/100 g (chickpeas) to 450 g/100 g (mung beans). For all three seeds losses of dry matter and carbohydrates were observed. In wheat and mung beans, phytic acid was partially hydrolyzed. In mung beans, the total fat content decreased. Increases in the content of polyunsaturated fatty acids in wheat and of dietary fibre in wheat and mung beans were noted. At a constant level of crude protein, a measurable rise in limiting amino acids was observed in wheat and mung beans. Frequent watering during germination caused losses of Fe, between 9% and 21%, K (27% in chickpeas) and Cu (17% in chickpeas). Except for vitamin B6 in both legumes and vitamin B1 in chickpeas, accumulation of the vitamins under investigation (B1, B2, B6, C, E) was noted. Owing to these changes during germination, the nutritional value of the three seeds has been improved to various extents, most distinctly in wheat and least noticeably in chickpeas. Compared with other vegetables, sprouted seeds can be considered a valuable addition to the diet.

Fabaceae↗

Comparative physico-chemical studies on purified trypsin inhibitors from the endosperm of barley, rye, and wheat.

The dominant trypsin inhibitors of the endosperm of barley, rye and wheat were investigated in a series of comparative studies. The barley and rye inhibitors showed a reaction of partial immunochemical identity, whereas no immunological cross-reactions between the wheat inhibitor and the inhibitors from barley and rye were detected. The molecular weight of the barley inhibitor is about 14,500, and of the rye and wheat inhibitors about 12,000. The three inhibitors had very similar amino acid compositions, but the wheat inhibitor seemed to contain nine disulfide bridges whereas the barley and rye inhibitor contain five and four, respectively. This may explain the higher stability of the wheat inhibitor towards proteolytic inactivation by pepsin and chymotrypsin. All three inhibitors were very stable to temperatures at 100 degrees C. The barley inhibitor was much less active against porcine trypsin, and especially human trypsin, than against bovine trypsin, whereas the inhibition by the rye and wheat inhibitor was less dependent on the origin of the enzyme.

Amino Acids↗

Effects of gamma irradiation on mycotoxin disappearance and amino acid contents of corn, wheat, and soybeans with different moisture contents.

The effects of gamma irradiation on degradation of aflatoxin B1 in wheat, corn, and soybeans and of T-2 toxin in wheat, deoxynivalenol (DON) in soybeans, and zearalenone in corn at 9, 13, and 17% moisture were studied. Radiation doses of 5, 7.5, 10 or 20 kGy were applied to spiked grain samples, and the residual toxins were measured using an enzyme linked immunosorbent assay (ELISA). Irradiation does of up to 20 kGy did not significantly affect aflatoxin B1 in any of the three grains, but significant reductions occurred in T-2 toxin, DON, and zearalenone concentration at doses of 10 or 20 kGy and in T-2 toxin at the 7.5 kGy dose. Two-way analysis of variance with Tukey's Multiple Range Test showed no significant interaction between radiation dose and grain moisture level. Irradiation of the ground grains at doses higher than 5 kGy resulted in small, but significant, losses of lysine in corn (only at 7.5 kGy), wheat, and soybeans, and methionine was reduced in wheat and corn samples. In some cases, phenylalamine decreased in corn and wheat, and histidine levels in wheat were reduced in samples receiving 7.5 kGy of irradiation. Other essential amino acids were not affected significantly by irradiation.

Aflatoxin B1↗

The homoeologous relationships of the arms of wheat chromosomes 2A and 2D to chromosome 2B and their effect on homoeologous pairing.

Homoeologous relationships between the arms of wheat group 2 chromosomes were analysed by studying homoeologous pairing in wheat-rye hybrids. Chromosomes 2A and 2D were identified using telocentrics 2AS, 2DS or 2DL. The remaining wheat chromosomes and their arms were identified by C-banding. Wheat chromosomes in the hybrids were derived from plants which were heterozygous (Ph1/ph1b) and monotelocentric for 2AS, 2DS or 2DL. In these plants, chromosome 2B and the telocentric showed regular bivalent pairing. From the results of homoeologous pairing in wheat-rye hybrids, normal homoeologous relationships between 2AS, 2BS and 2DS, as well as between 2AL, 2BL and 2DL, were deduced. There was no evidence that wheat group 2 chromosomes were involved in evolutionary chromosome rearrangements. The existence of a pairing promoter gene on chromosome arm 2DS was supported.

Chromosomes↗