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At least 433 records · Page 24Linked to original sources
PubMed1998

Selective identification by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry of different types of gluten in foods made with cereal mixtures.

The gluten toxic fractions responsible for the mucosal damage in coeliac disease (CD), so-called gliadins, hordeins, secalins and avenins from a large number (30-40) of wheat, barley, rye and oats cultivars respectively, have been mass analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Gliadin, secalin and avenin characteristic mass profiles are nearly identical amongst distinct cultivars from the corresponding cereal, while hordeins profiles show more variability depending on the particular barley cultivar. On the basis of these four distinguishable characteristic mass patterns spreading within the 20,000-40,000 Da range, MALDI-TOF-MS has permitted the direct and simultaneous visualization of gliadins, hordeins, secalins and avenins in foods elaborated with cereal mixtures of wheat, barley, rye and oats. This capacity has been demonstrated by mass analyzing foods made with these four cereals in varying ratios. Thus MALDI-TOF-MS can be preliminarily established as a unique system with the ability to discriminate the specific type of gluten toxic fractions present in food samples.

Avena↗
PubMed1999

In vitro screening of food peptides toxic for coeliac and other gluten-sensitive patients: a review.

Experience gained through investigations on coeliac disease makes it possible to propose a screening method based on agglutination of isolated K562(S) cells to evaluate the occurrence in food protein of amino acid sequences that are able to adversely affect coeliac and related gluten-sensitive patients. The method consists of in vitro sequential peptic and tryptic digestion of food protein fractions under optimal pH, temperature and time conditions and in vitro incubation of the digest with K562(S) cells; the toxic potential is detected as an agglutination of K 562 (S) cells after a short incubation. Other in vitro test systems, including atrophic coeliac intestinal mucosa and rat fetal intestine, can be used to confirm the results obtained with the isolated cells. A fractionation step of the proteolytic digest on a sepharose-mannan column before exposure of the in vitro systems to the separated peptide fractions adds to the sensitivity of the method. This screening method is not only very useful to investigate action mechanisms in coeliac disease, but also to assess the safety of genetically-modified plant foods and novel foods for gluten-sensitive patients.

Amino Acid Sequence↗
PubMed2002

Plasticity of seed protein composition in response to nitrogen and sulfur availability.

Seed composition is genetically programmed, but the implementation of that program is affected by many factors including the nutrition of the parent plant. In particular, seeds demonstrate a remarkable capacity to maintain nitrogen homeostasis in conditions of varying sulfur supply. They do this by altering the expression of individual genes encoding abundant storage proteins. The signal transduction pathways that modulate gene expression in seeds in response to N and S availability involve both transcriptional and post-transcriptional mechanisms.

Albumins↗
PubMed1999

Degradation of oat mRNAs during seed development.

The genes AV1, AV10, and Z1 encode proteins that accumulate during oat seed development. In developing endosperm of Avena sativa (cultivated oat), AV1, AV10 and Z1 mRNAs reach maximal levels midway through seed development but fall to very low levels in mature seeds. Similarly, mRNAs for these proteins peak during endosperm development of Avena fatua (wild oat) and are later degraded. However, during late maturation of A. fatua seeds, populations of mRNA fragments shorter than the intact transcripts accumulate as the full-length transcripts decline in abundance. The smaller RNA molecules, which are apparently long-lived decay intermediates, are derived randomly from the entire transcripts and are most likely not generated by cleavage at precisely defined sites. Other A. fatua endosperm mRNAs that are degraded during late seed development, such as those for ADP glucose pyrophosphorylase and starch synthase, do not produce detectable decay intermediates. Decay intermediates of AV1 and Z1 mRNAs persist at high levels during late seed development of two other undomesticated oat species, Avena strigosa and Avena barbata. The persistence of decay intermediates for these endosperm mRNAs in wild grass species may represent a model system for studying RNA decay process in plant tissues.

Amino Acid Sequence↗
PubMed2002

Towards the identification of cassava root protein genes.

The protein population of cassava root layers was characterized by SDS-PAGE and bidimensional polyacrylamide gel electrophoresis. SDS-Page revealed the presence of a protein population in the molecular weight range between 94 and 20 kDa. The expression pattern of these proteins was well-defined within the different layers. Partial protein sequence analyses and preliminary results on the layer-specific expression pattern obtained with Northern analyses are presented.

Amino Acid Sequence↗
PubMed1988

Hydrophobic-cluster analysis of plant protein sequences. A domain homology between storage and lipid-transfer proteins.

Hydrophobic-cluster analysis was used to characterize a conserved domain located near the C-terminal amino acid sequence of wheat (Triticum aestivum) storage proteins. This domain was transformed into a linear template for a global search for similarities in over 5200 protein sequences. In addition to proteins that had already been found to exhibit homology to wheat storage proteins, a previously unreported homology was found with non-specific lipid-transfer proteins from castor bean (Ricinus communis) and from spinach (Spinacia oleracea) leaf. Hydrophobic-cluster analysis of various members of the present protein group clearly shows a typical domain structure where (i) variable and conserved domains are located along the sequence at precise positions, (ii) the conserved domains probably reflect a common ancestor, and (iii) the unique properties of a given protein (chain cut into subunits, repetitive domains, trypsin-inhibitor active site) are associated with the variable domains.

Amino Acid Sequence↗
PubMed2002

Plant protein families and their relationships to food allergy.

The analysis of plant proteins has a long and distinguished history, with work dating back over 250 years. Much of the work has focused on seed proteins, which are important in animal nutrition and food processing. Early studies classified plant proteins into groups based on solubility ('Osborne fractions') or protein function. More recently, families have been defined based on stuctural and evolutionary relationships. One of the most widespread groups of plant proteins is the prolaminin superfamily, which comprises cereal seed storage proteins, a range of low-molecular-mass sulphur-rich proteins (many of which are located in seeds) and some cell wall glycoproteins. This superfamily includes several major types of plant allergen: non-specific lipid transfer proteins, cereal seed inhibitors of alpha-amylase and/or trypsin, and 2 S albumin storage proteins of dicotyledonous seeds.

Animals↗
PubMed2000

A beta-turn rich oats peptide as an antigen in an ELISA method for the screening of coeliac disease in a paediatric population.

BACKGROUND: ELISA methods for the measurement of IgA antigliadin antibodies (AGA), both home-made and commercial systems, routinely employ wheat gliadin fractions as coating antigens. We investigate the sensitivity and specificity for CD diagnosis of a new ELISA method using a highly immunoreactive beta-turn rich gamma3-avenin peptide as an alternative coating antigen. METHODS: The assay was standardized with antihuman IgA peroxidase-conjugated as the second antibody. Alternatively, an ELISA based on the use of protein A-peroxidase was assayed to measure both IgG plus IgA antibodies. Sixty-three sera from healthy controls were analyzed to establish the system's cut-off point. Sera from 103 coeliac and from 65 noncoeliac children were tested; for diagnosis purposes, a small intestinal biopsy had been performed in all of them. RESULTS: For the IgA class antibodies assay a high sensitivity and specificity of 90.3% and 98.5%, respectively, was obtained, comparable to those achieved for IgA antiendomysium antibodies (EmA) with the same sera. CONCLUSIONS: In view of the high sensitivity and specificity obtained together with water solubility of the peptide and easiness for large-scale reproducible synthesis, the new AGA IgA avenin peptide ELISA represents a significant improvement in CD diagnosis in comparison with conventional established AGA IgA ELISA using crude gliadins as coating antigens.

Adolescent↗
PubMed2006

Coeliac children on a gluten-free diet with or without oats display equal anti-avenin antibody titres.

OBJECTIVE: Recent studies report negligible toxicity of oats in the majority of coeliac disease (CD) patients. It has previously been shown that children with untreated CD have circulating antibodies to oats avenin. In this study we performed serial assessments of anti-avenin antibodies in children under investigation for CD on a gluten-free diet with or without oats. MATERIAL AND METHODS: The study involved 116 children, randomized to a standard gluten-free diet or a gluten-free diet supplemented with oats. Sera were obtained from 86 children, 48 in the standard gluten-free group and 38 in the gluten-free oats group, of which 33 consumed at least 10 g of oats daily. IgA and IgG anti-avenin antibodies were monitored at 0, 3, 6 and 12 months. Nitric oxide metabolites were measured in 7 patients, with deviating antibody results. RESULTS: There was a significant decrease in anti-avenin antibodies in both groups at the end as compared to the beginning of the study, (p<0.001), but no difference was found between the two groups. IgA titres already declined after 3 months. IgG titres, although significantly decreased, remained high in the majority of patients in both groups. Nitric oxide levels were high in four of the analysed samples. CONCLUSIONS: Oats per se, do not seem to produce a humoral immune reaction in children with CD when given in an otherwise gluten-free diet, indicating that the reaction requires gluten challenge. Anti-avenin antibodies were equal in the two study groups, and these findings strengthen the clinical impression that oats can be tolerated by the majority of patients with CD.

Antibodies↗
PubMed2003

Inter-relationship between electrophoretic characteristics of pseudocereal and cereal proteins and their microscopic structure for possible substitution based on nutritional evaluation.

Amaranth, soybean and maize were screened for proteins and their nutritional value. Isopropanol-soluble protein and buffer-soluble protein fractions were extracted from seeds and separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The comparison of the identity and differences between investigated plants was carried out by the obtained SDS-PAGE electrophoretic patterns, and their microstructure was determined by scanning electron microscopy. Electrophoretic patterns of extracted proteins have shown that the main protein subunits were concentrated between 10 and 50 kDa. Variations were found in major fractions and minor bands as well as in the fine structure. The microstructure of pseudocereal and cereal protein fractions was inter-related with the results obtained by their electrophoretic separation. Pseudocereal amaranth can be used as a nutritive substitute of cereal maize in functional foods.

2-Propanol↗
PubMed1992

Evidence for a novel route of wheat storage proteins to vacuoles.

Wheat seed storage proteins are deposited in protein bodies (PB) inside vacuoles, but their subcellular site of aggregation and their route to vacuoles are still controversial. In the present work, an ultra structural analysis of developing wheat endosperm at early to mid maturation was performed to address these issues. Golgi complexes were rarely detected, indicating that their role in wheat storage protein transport is limited. In contrast, a considerable amount of PB was detected in the cytoplasm. Many of these PB were surrounded by RER membranes and were enlarged by fusion of smaller PB. Small, electron lucent vesicles were detected around the surfaces of the PB in the cytoplasm, or attached to them, suggesting that such attachments and subsequent fusion of the vesicles with each other lead to the formation of small vacuoles containing PB inclusions. Immunogold labeling with serum raised against yeast-BiP, an ER-localized protein, demonstrated that the wheat BiP homolog was present within the PB in the cytoplasm as well as inside vacuoles. This confirmed that the PB were formed within the RER and that the Golgi complex was not involved in their transport to vacuoles. It is concluded that a considerable part of the wheat storage proteins aggregate into PB within the RER and are then transported as intact PB to the vacuoles by a novel route that does not utilize the Golgi complex.

Biological Transport↗
PubMed2001

Immunologic evidence of no harmful effect of oats in celiac disease.

BACKGROUND: It was recently shown that antiendomysial antibodies (EMAs), which are highly sensitive and specific for celiac disease, are produced by intestinal mucosa. Furthermore, EMAs were detected previously in supernatant fluid from cultured duodenal mucosa specimens collected from untreated celiac disease patients and in culture media of biopsy specimens collected from treated celiac disease patients after an in vitro challenge with gliadin. Moreover, it was recently shown in vivo that oats are not toxic to celiac disease patients, suggesting the safety of oats in a gluten free-diet. OBJECTIVE: The objective was to better define the controversial role of oats in celiac disease to determine whether oats can be safely included in a gluten-free diet. DESIGN: We used an in vitro model to test whether oats induce EMA production in supernatant fluid from cultured duodenal mucosa specimens collected from 13 treated celiac disease patients. The biopsy specimens were cultured with and without peptic-tryptic digest (PT) of gliadin and avenin (from oats) and in medium alone. Samples from 5 of the 13 patients were cultured with the C fraction of PT-avenin. Indirect immunofluorescence was used to detect EMAs. RESULTS: EMAs were detected in specimens from all 13 patients after the challenge with gliadin but not after culture in medium alone. By contrast, no EMAs were detected in any of the specimens cultured with PT-avenin and its C fraction. CONCLUSIONS: Because the in vitro challenge with PT-avenin and its C fraction did not induce EMA production in treated celiac disease patients, it appears that oats have no harmful effect on celiac disease. Therefore, oats can be safely included in a gluten-free diet.

Adolescent↗
PubMed2006

Hordeins are expressed in microspore-derived embryos and also during male gametophytic and very early stages of seed development.

Microspore-derived embryos induced by anther or isolated-microspore culture display certain characteristics of zygotic embryos. Furthermore, the expression of certain endosperm genes has been described in these non-zygotic embryos. The expression of hordein genes encoding the main barley endosperm proteins has been studied using a wide range of methods (RT-PCR, in situ hybridization, ELISA sandwich, western blotting immunocytochemistry, and cytochemistry) to ascertain their presence or absence during the induction and first stages of microspore embryogenesis. Due to the very sensitive techniques used it was possible to detect for the first time hordein expression during microspore embryogenesis. Surprisingly, these hordeins were also detected at different stages of male gametophytic development as well as during the very early stages of seed development, when they have not hitherto been detected. The expression and localization of these storage proteins and their corresponding transcripts provide new information about barley microspore embryogenesis and its relationship to zygotic embryogenesis. Although only small quantities of hordeins are accumulated during microspore embryogenesis they seem to be necessary for the initial development of the microspore-derived embryo. This idea is supported by the changes detected in their concentration throughout this process and is in accordance with previously published data concerning the importance of endosperm proteins for embryo development in both microspore culture and in planta.

Blotting, Western↗
PubMed2004

Expression of the sorghum 10-member kafirin gene cluster in maize endosperm.

Functional analysis of chromosomal segments containing linked genes requires the insertion of contiguous genomic sequences from bacterial artificial chromosomes (BACs) into the genome. Therefore, we introduced a 90-kb large BAC clone carrying a 10-copy tandem array of kafirin storage protein genes from sorghum linkage group J, mixed with a selectable marker gene, directly into maize cells using the particle bombardment method. Transgenic plants were regenerated and seeds from eight different transgenic lines were produced. One such transgenic plant was selected that had the entire kafirin gene cluster on a single continuous DNA fragment spanning more than 45 kb integrated into its genome. When alcohol-soluble proteins from individual T2 and T3 seeds of this event were analyzed, significant levels of kafirin were found in addition to the endogenous zein storage proteins, demonstrating that the large exogenous DNA segment is stably integrated into the maize genome and expressed at high levels in subsequent generations. Therefore, we could provide a new utility of plant transformation by the particle bombardment method for functional genomics of multigene families and the modification of the nutritive quality of cereal grains. Despite a tandem array of highly homologous sequences at the transgenic locus, no gene silencing was observed, probably owing to the effects of co-transformed flanking sequences. The expression studies of the transgenic locus also revealed new features of storage protein gene promoters that differed from previous transient gene expression studies, thereby illustrating the significance of the concentration and configuration of DNA-protein interactions in the regulation of gene expression.

Chromatin↗