Establishing the safety of foods derived from GM crops requires a multidisplinary approach with methods adapted from the biochemical, nutritional, toxicological and immunological sciences. The core principle of the process has been articulated as substantial equivalence, which is a comparative evaluation of a large number of analytes from transgenic and non-transgenic crop varieties. For allergy, it is essential to evaluate the introduced protein and, for highly allergenic crops, it may also be necessary to evaluate potential changes in endogenous allergens. The prevalence of food allergies appears to be on the rise, particularly in developed countries. Since no cure is available for those afflicted with food allergy, disease management is achieved by avoidence of the offending food. As a result, significant weight in the assessment is given to the need for prevention, which in the context of safety assessment, means, among other approaches, reducing the likelihood of transferring offending allergens from one food to another. Genetic engineering of food crops should have little practical consequence for the occurrence, frequency, and natural history of food allergy if this evaluation is robust. Essential aspects of allergy assessment are discussed in this chapter.
Proteomics is currently tested as a complementary tool for the safety assessment of genetically modified (GM) crops. Understanding the natural variability of the proteome is crucial for the interpretation of biological differences between transgenic and nontransgenic parental lines. The natural variation of seed protein profiles among a set of 12 Arabidopsis thaliana ecotypes was determined by utilizing two-dimensional electrophoresis (2DE). The total number of different resolved protein spots found among the 12 ecotypes was 931 with a range of 573 (Mt-0) to 653 (Condara) in any one ecotype. Although the ecotypes were grown side-by-side in an environmentally controlled growth chamber, almost half of the resolved spots varied with respect to their presence/absence, and 95% of the spots present in all ecotypes varied in spot quantity (2−53-fold). In the evaluation of unintended effects of genetic modification, it is concluded that the experimental design must account for existing natural variability, which, in the case of the expressed proteome, can be substantial. Keywords: Two-dimensional gel electrophoresis; Arabidopsis thaliana; seed proteome; natural variability
We have cloned, sequenced and expressed a recombinant group IX pollen allergen from barley (Hordeum vulgare). Hor v 9 is a polypeptide of 313 amino acids. The Hor v 9 cDNA clone was engineered into the E. coli protein expression vector pMAL and expressed as a fusion of maltose binding protein and truncated Hor v 9. Polyclonal antibodies to the fusion protein were raised in mice. Cross-reactive proteins, RNA and DNA homologues were found in many agricultural species including wheat, rye, triticale, oats, maize, sunflower and flax. The presence of group IX-like proteins in a variety of agricultural crops may represent a previously uncharacterized aeroallergenic occupational hazard. Sequence comparisons of the barley allergen, Hor v 9, with Poa p 9 and other cloned group IX pollen allergens revealed putative structural domains common to all. These include a signal peptide, two conserved immunoglobulin-like motifs, a 150 amino acid highly conserved carboxyterminal domain and a carboxyterminal transmembrane helix. This structural arrangement is also found in cell adhesion molecules. The highly conserved T-cell epitope previously characterized and mapped in group IX allergens (and present in Hor v 9) was found in several human cell adhesion molecule sequences (VCAM, NCAM and CD2). This T-cell epitope corresponded to the most highly conserved amino acid residues common to all group IX homologues sequenced to date. CD2 and VCAM are known to play a role in allergic inflammation: VCAM is involved in the recruitment of lymphocytes to sites of inflammation, and cross-linking CD2 leads to T-cell activation. We anticipate that the similar structural arrangement of group IX allergens and human cell adhesion molecules, as well as the presence of a T-cell epitope common to group IX pollen allergens and cell adhesion molecules, will have important consequences in the natural history of the atopic immune response.
Abstract Low linolenic acid soybean oil (LLSO) has been developed as a substitute for hydrogenated soybean oil to reduce intake of trans FA while improving stability and functionality in processed foods. We assessed the dietary impact of substitution of LLSO for hydrogenated soybean oil (HSBO) used in several food categories. All substitutions were done using an assumption of 100% market penetration. The impact of this substitution on the intake of five FA and trans FA was assessed. Substitution of LLSO for current versions of HSBO resulted in a 45% decrease in intake of trans FA. Impacts on other FA intakes were within the realm of typical dietary intakes. No decrease in intake of α‐linolenic acid was associated with the use of LLSO in place of HSBO because LLSO substitutes for HSBO that are already low in α‐linolenic acid.
Grass pollen allergens are one of the major causes of type I allergic reactions (allergic rhinoconjunctivitis, allergic bronchial asthma, and hayfever) in temperate climates afflicting 15-20% of a genetically predisposed population.Workers have found considerable physicoand immunochemical heterogeneity within the grass pollen allergens which has made them difficult to purify for both therapeutic uses and further biochemical study.We recently reported the construction of a cDNA library in Xgtll using mRNA extracted from dehydrated Kentucky bluegrass (KBG, Poa pratensis).Here, we present the nucleotide and deduced amino acid sequences for three KBG pollen allergen cDNA clones, KBG 41,60, and 31, which were isolated from the above library using a pool of six sera from grass pollen allergic patients.These clones exhibit an exceptionally high degree of sequence similarity to one another, only minor similarity to other known allergens, and no homologies to other known proteins or genes.The predicted molecular mass for the cloned proteins range from 28.3 to 37.8 kDa with PI values of 9.6-10.2.All three clones appear to possess leader peptides and lack asparagine sequons required for N-glycosylation.Therefore, the molecular mass of the post-translationally modified proteins were calculated to be 28.4-34.9kDa, which is consistent with the size of the polypeptides revealed in Western blots of pollen proteins using an antiserum to a recombinant peptide encoded by the partial cDNA clone KBG 8.3.Northern blotting analysis indicates that expression of the genes corresponding to these clones is confined to pollen tissue.The results suggest that the clones code for a group of proteins that represent a new and previously uncharacterized group of grass pollen isoallergens, which have been hereby designated as Poa p IX.Aero-allergenic proteins originate from a wide variety of sources including pollens of grasses, weeds, and trees, spores
