During caryopsis development, prolamins are initially stored in individual protein bodies, then generate a protein matrix in the ripe caryopsis. The ontogeny of the protein bodies was analyzed by ...fluorescence and electron microscopy from 7 to 43 days after anthesis (dAA), a period of time from the cellularization of endosperm to its desiccation. A series of antibodies specific to each prolamin type (
α/
β-,
γ-,
ω-gliadins, low-molecular weight and high-molecular weight glutenin subunits) made it possible to localize and co-localize the different prolamins in organelles of endosperm cells at different developmental stages. Protein bodies containing prolamins were observed as early as 7
dAA. At the early developmental stages, protein bodies were spherical with diameters around 1–2
μm. Later, around 15
dAA, the PBs enlarged, and aggregation and/or coalescence were prominent at 21
dAA. From 33
dAA, individual PBs were no longer visible, but a protein matrix was confined in the space between starch granules. All prolamins were found in the same protein bodies, without any segregation according to their types. Immunochemical labelling of prolamins failed to reveal in TEM analyses any particular internal organization in protein bodies. Glutenin subunits and gliadins were observed in the Golgi apparatus at the early stages of endosperm development.
Detailed studies of wheat glutenin subunits have provided novel details of their molecular structures and interactions which allow the development of a model to explain their role in determining the ...visco-elastic properties of gluten and dough. The construction and analysis of near-isogenic and transgenic lines expressing novel subunit combinations or increased amounts of specific subunits allows differences in gluten properties to be related to the structures and properties of individual subunits, with potential benefits for the production of cultivars with improved properties for food processing or novel end users
Allergy to wheat in foods occurs in both children and adults and induces various symptoms. Specific allergens were found in adults with wheat-dependent exercise-induced anaphylaxis (WDEIA). However, ...no data clearly indicated whether the immunoglobulin E (IgE) responses of children or adults with other symptoms were linked to similar or different allergens. Profiles of IgE-binding proteins were compared in wheat-allergic patients with atopic dermatitis (AD), with or without asthma, urticaria, anaphylaxis or WDEIA. Fluorimetric (F)-ELISA was used to analyze the reactivity of IgE antibodies from 60 sera to purified gliadin, glutenin and lipid transfer protein (LTP) fractions and an albumin/globulin extract. Of patients suffering from AD with and without asthma, 80 and 92%, respectively, had IgE to albumins/globulins. Children's sera frequently contained IgE directed to α-, β- and γ-gliadins, whereas all patients with anaphylaxis or WDEIA and 55% of those with urticaria had IgE to ω
5-gliadins. IgE directed to LTP was found in 28% of the sera. Different IgE-binding profiles were observed in food allergy to wheat. The major allergens were albumins/globulins for patients with AD (mainly children) and ω
5-gliadins for adults with anaphylaxis or urticaria.
Wheat presents an important genetic diversity that could be useful to look for cultivars with reduced allergencity. ω5-Gliadins have been described as major allergens for wheat allergic patients ...suffering from wheat-dependent exercise-induced anaphylaxis (WDEIA) and some cases of chronic urticaria (U). Our objective was to study the influence of genetic variability at the Gli-B1 locus encoding for ω5-gliadins on the reactivity of IgE antibodies from these patients. We selected cultivars expressing 13 alleles at Gli-B1 including a wheat/rye translocation and studied the reactivity to gliadins of a rabbit antiserum specific for ω5-gliadins and of IgE from 10 patients. The antiserum and IgE from nine patients with WDEIA and U strongly detected ω5-gliadins expressed by most of the Gli-B1 alleles but showed no or faint responses to the gliadins and secalins extracted from the translocated wheat. The selection of genotypes lacking the Gli-B1 locus may reduce wheat allergenicity. Keywords: Wheat; food allergy; exercise induced anaphylaxis; ω5-gliadins; allelic variants
The general objective of this work was to study the feasibility of preparing small-sized carriers from vegetal macromolecules. For this purpose, gliadin (a vegetal protein fraction from wheat gluten) ...nanoparticles were chosen as drug carriers for
all-trans-retinoic acid (RA). The systems were prepared by a desolvation method for macro-molecules, which enabled us to obtain gliadin nanoparticles of about 500 nm, with a yield close to 90% of the initial protein. All experiments were performed using environmentally acceptable solvents such as ethanol and water. Moreover, due to the low solubility of this protein in water and to its high hydrophobicity, nanoparticles from gliadin do not need any further chemical or physical treatment to harden them. Gliadin nanoparticles were quite stable over 4 days in phosphate-buffered saline (PBS), but were degraded rapidly over 3 h when incubated in PBS solution containing trypsin. However, chemical cross-linkage of nanoparticles with glutaraldehyde significantly increased their stability. Under our experimental conditions, the payload limit was 76.4 μg RA/mg nanoparticles (for an RA/initial protein ratio of 90 μg/mg), which corresponded to a RA entrapment efficiency of about 75% of added drug. Nevertheless, the entrapment efficiency was high (between 97 and 85%) for RA/initial protein ratios up to 90 μg/mg. Finally, the in vitro release profiles of RA-loaded gliadin nanoparticles showed a biphasic pattern. An initial burst effect (in which about 20% RA was released) followed by zero-order diffusion (release rate 0.065 mg RA/h) were observed.
Films were prepared by casting alkaline solutions of gliadin, a major wheat storage protein fraction. Their compositions and mechanical and surface properties were analyzed. Five polyols of the ...ethylene glycol series and glycerol were compared as plasticizers. The plasticized film-forming solutions exhibited viscosities almost independent of shear rate. Glycerol-containing protein solutions had, however, a higher viscosity than others. After drying, concentrations of plasticizers in films were explained mainly, but not uniquely, by their volatility. At equal concentrations in films, glycerol and tetraethylene glycol were more efficient than the other plasticizers studied. A wide range of elongation (10−600%) was obtained when the plasticizer contents were varied, but the tensile strength (2−12 MPa) was always lower than that of usual synthetic polymer films. A negative relationship, independent of the plasticizing molecules used, was found between tensile strength and elongation at break of gliadin films. Surface hydrophobicity of films was high and no influence of plasticizers was observed. Keywords: Film; gliadins; wheat; plasticizer; polyols
KEY MESSAGE : Wheat low-molecular-weight-glutenin and α-gliadin were accumulated in the endoplasmic reticulum and formed protein body-like structures in tobacco cells, with the participation of BiP ...chaperone. Possible interactions between these prolamins were investigated. Wheat prolamins are the major proteins that accumulate in endosperm cells and are largely responsible for the unique biochemical properties of wheat products. They are accumulated in the endoplasmic reticulum (ER) where they form protein bodies (PBs) and are then transported to the storage vacuole where they form a protein matrix in the ripe seeds. Whereas previous studies have been carried out to determine the atypical trafficking pathway of prolamins, the mechanisms leading to ER retention and PB formation are still not clear. In this study, we examined the trafficking of a low-molecular-weight glutenin subunit (LMW-glutenin) and α-gliadin fused to fluorescent proteins expressed in tobacco cells. Through transient transformation in epidermal tobacco leaves, we demonstrated that both LMW-glutenin and α-gliadin were retained in the ER and formed mobile protein body-like structures (PBLS) that generally do not co-localise with Golgi bodies. An increased expression level of BiP in tobacco cells transformed with α-gliadin or LMW-glutenin was observed, suggesting the participation of this chaperone protein in the accumulation of wheat prolamins in tobacco cells. When stably expressed in BY-2 cells, LMW-glutenin fusion was retained longer in the ER before being exported to and degraded in the vacuole, compared with α-gliadin fusion, suggesting the involvement of intermolecular disulphide bonds in ER retention, but not in PBLS formation. Co-localisation experiments showed that gliadins and LMW-glutenin were found in the same PBLS with no particular distribution, which could be due to their ability to interact with each other as indicated by yeast two-hybrid assays.
Wheat low-molecular-weight-glutenin and alpha-gliadin were accumulated in the endoplasmic reticulum and formed protein body-like structures in tobacco cells, with the participation of BiP chaperone. ...Possible interactions between these prolamins were investigated. Wheat prolamins are the major proteins that accumulate in endosperm cells and are largely responsible for the unique biochemical properties of wheat products. They are accumulated in the endoplasmic reticulum (ER) where they form protein bodies (PBs) and are then transported to the storage vacuole where they form a protein matrix in the ripe seeds. Whereas previous studies have been carried out to determine the atypical trafficking pathway of prolamins, the mechanisms leading to ER retention and PB formation are still not clear. In this study, we examined the trafficking of a low-molecular-weight glutenin subunit (LMW-glutenin) and alpha-gliadin fused to fluorescent proteins expressed in tobacco cells. Through transient transformation in epidermal tobacco leaves, we demonstrated that both LMW-glutenin and alpha-gliadin were retained in the ER and formed mobile protein body-like structures (PBLS) that generally do not co-localise with Golgi bodies. An increased expression level of BiP in tobacco cells transformed with alpha-gliadin or LMW-glutenin was observed, suggesting the participation of this chaperone protein in the accumulation of wheat prolamins in tobacco cells. When stably expressed in BY-2 cells, LMW-glutenin fusion was retained longer in the ER before being exported to and degraded in the vacuole, compared with alpha-gliadin fusion, suggesting the involvement of intermolecular disulphide bonds in ER retention, but not in PBLS formation. Co-localisation experiments showed that gliadins and LMW-glutenin were found in the same PBLS with no particular distribution, which could be due to their ability to interact with each other as indicated by yeast two-hybrid assays.PUBLICATION ABSTRACT
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