Application of Deamidated Gliadin Antibodies in the Follow-Up of Treated Celiac Disease

Introduction

The role of serological tests such as IgA anti-transglutaminase autoantibodies has become increasingly important in celiac disease (CD) diagnosis. However, the efficiency of these tests for patient follow-up is controversial. We investigated the correlation of 12 different serological tests, including recent deamidated gliadin and actin IgA tests, with villous atrophy (VA) in a retrospective cohort of treated celiac patients.

Materials and Methods

Serum samples were collected from 100 treated CD patients who had intestinal biopsy in the course of their follow-up. Antibodies against transglutaminase, deamidated gliadin peptides, and native gliadin were measured, along with IgA anti-actin. The biopsy slides were all blind-reviewed and scored according to Marsh classification.

Results

For all deamidated gliadin and transglutaminase tests, we found that a positive result was significantly associated with persistence of intestinal VA, with a diagnostic efficacy up to 80%. Furthermore, antibodies titers directly correlated with the degree of VA, indicating a strong link between disease activity and presence of antibodies in the serum. Interestingly, the tests with the highest association with persistent VA were those for deamidated gliadin IgG. Using a test positivity pattern analysis, we were also able to identify several groups of patients with distinct antibody profiles that showed significant differences in intestinal damage and diet compliance.

Conclusions

Altogether, these results show that deamidated gliadin antibodies are strongly correlated with VA and should be considered valuable tools in CD follow-up and that multiplex serologic analysis for treated CD represents a promising tool for personalized patient management.     

Microsatellite diversity correlated with ecological-edaphic and genetic factors in three microsites of wild emmer wheat in North Israel

This study was conducted to test the effects of internal (genetic) and external factors on allelic diversity at 27 dinucleotide microsatellite (simple sequence repeat [SSR]) loci in three Israeli natural populations of Triticum dicoccoides from Ammiad, Tabigha, and Yehudiyya, north of the Sea of Galilee. The results demonstrated that SSR diversity is correlated with the interaction of ecological and genetic factors. Genetic factors, including genome (A vs. B), chromosome, motif, and locus, affected average repeat number (ARN), variance in repeat number (sigma), and number of alleles (NA) of SSRs, but the significance of some factors varied among populations. Genome effect on SSR variation may result from different motif types, particularly compound (or imperfect) versus perfect motifs, which may be related to different evolutionary histories of genomes A and B. Ecological factors significantly affected SSR variation. Soil-unique and soil-specific alleles were found in two edaphic groups dwelling on terra rossa and basalt soils across macro- and microgeographical scales. The largest contributions of genetic and ecological effects were found for diversity of ARN and NA, respectively. Multiple regression indicated that replication slippage and unequal crossing over could be important mutational mechanisms, but their significance varied among motifs. Edaphic stresses may affect the probability of replication errors and recombination intermediates and thus control diversity level and divergence of SSRs. The results may indicate that SSR diversity is adaptive, channeled by natural selection and influenced by both internal and external factors and their interactions.     

Natural selection causing microsatellite divergence in wild emmer wheat at the ecologically variable microsite at Ammiad, Israel

Genetic diversity at 28 microsatellite loci was studied in a natural population of Triticum dicoccoides at the Ammiad microsite, north of the Sea of Galilee, Israel. This microsite was subdivided into four major habitats, North, Valley, Ridge and Karst, and further subdivided into nine subhabitats. The units thus defined showed strong and highly significant differentiation in ecological factors; in particular with respect to cover, proximity and height of rocks, and surface soil moisture after early rains. The results showed that allele distributions at microsatellite loci were nonrandom and associated with habitats. Significant genetic differentiation and variation in repeat number were found among subpopulations in the four major habitats and nine subhabitats. Habitat-specific and -unique alleles and linkage disequilibria were observed in the Karst subpopulation. The subpopulations dwelling in drier habitats and subhabitats showed higher genetic diversities at microsatellite loci. These results suggest that natural selection, presumably through aridity stress, acts upon microsatellite divergence predominantly on noncoding sequences, thereby contributing to differences in fitness. Received: 9 September 1999 / Accepted: 16 September 1999     

Grain zinc, iron and protein concentrations and zinc-efficiency in wild emmer wheat under contrasting irrigation regimes

Micronutrient malnutrition, and particularly deficiency in zinc (Zn) and iron (Fe), afflicts over three billion people worldwide, and nearly half of the world’s cereal-growing area is affected by soil Zn deficiency. Wild emmer wheat [Triticum turgidum ssp. dicoccoides (Körn.) Thell.], the progenitor of domesticated durum wheat and bread wheat, offers a valuable source of economically important genetic diversity including grain mineral concentrations. Twenty two wild emmer wheat accessions, representing a wide range of drought resistance capacity, as well as two durum wheat cultivars were examined under two contrasting irrigation regimes (well-watered control and water-limited), for grain yield, total biomass production and grain Zn, Fe and protein concentrations. The wild emmer accessions exhibited high genetic diversity for yield and grain Zn, Fe and protein concentrations under both irrigation regimes, with a considerable potential for improvement of the cultivated wheat. Grain Zn, Fe and protein concentrations were positively correlated with one another. Although irrigation regime significantly affected ranking of genotypes, a few wild emmer accessions were identified for their advantage over durum wheat, having consistently higher grain Zn (e.g., 125 mg kg^?1), Fe (85 mg kg^?1) and protein (250 g kg^?1) concentrations and high yield capacity. Plants grown from seeds originated from both irrigation regimes were also examined for Zn efficiency (Zn deficiency tolerance) on a Zn-deficient calcareous soil. Zinc efficiency, expressed as the ratio of shoot dry matter production under Zn deficiency to Zn fertilization, showed large genetic variation among the genotypes tested. The source of seeds from maternal plants grown under both irrigation regimes had very little effect on Zn efficiency. Several wild emmer accessions revealed combination of high Zn efficiency and drought stress resistance. The results indicate high genetic potential of wild emmer wheat to improve grain Zn, Fe and protein concentrations, Zn deficiency tolerance and drought resistance in cultivated wheat.     

Wheat Stripe Rust Resistance Protein WKS1 Reduces the Ability of the Thylakoid-Associated Ascorbate Peroxidase to Detoxify Reactive Oxygen Species

Stripe rust is a devastating fungal disease of wheat caused by Puccinia striiformis f. sp tritici (Pst). The WHEAT KINASE START1 (WKS1) resistance gene has an unusual combination of serine/threonine kinase and START lipid binding domains and confers partial resistance to Pst. Here, we show that wheat (Triticum aestivum) plants transformed with the complete WKS1 (variant WKS1.1) are resistant to Pst, whereas those transformed with an alternative splice variant with a truncated START domain (WKS1.2) are susceptible. WKS1.1 and WKS1.2 preferentially bind to the same lipids (phosphatidic acid and phosphatidylinositol phosphates) but differ in their protein-protein interactions. WKS1.1 is targeted to the chloroplast where it phosphorylates the thylakoid-associated ascorbate peroxidase (tAPX) and reduces its ability to detoxify peroxides. Increased expression of WKS1.1 in transgenic wheat accelerates leaf senescence in the absence of Pst. Based on these results, we propose that the phosphorylation of tAPX by WKS1.1 reduces the ability of the cells to detoxify reactive oxygen species and contributes to cell death. This response takes several days longer than typical hypersensitive cell death responses, thus allowing the limited pathogen growth and restricted sporulation that is characteristic of the WKS1 partial resistance response to Pst.     

Genetic diversity for grain nutrients in wild emmer wheat: potential for wheat improvement

Background and Aims

Micronutrient malnutrition, particularly zinc and iron deficiency, afflicts over three billion people worldwide due to low dietary intake. In the current study, wild emmer wheat (Triticum turgidum ssp. dicoccoides), the progenitor of domesticated wheat, was tested for (1) genetic diversity in grain nutrient concentrations, (2) associations among grain nutrients and their relationships with plant productivity, and (3) the association of grain nutrients with the eco-geographical origin of wild emmer accessions.

Methods

A total of 154 genotypes, including wild emmer accessions from across the Near Eastern Fertile Crescent and diverse wheat cultivars, were characterized in this 2-year field study for grain protein, micronutrient (zinc, iron, copper and manganese) and macronutrient (calcium, magnesium, potassium, phosphorus and sulphur) concentrations.

Key Results

Wide genetic diversity was found among the wild emmer accessions for all grain nutrients. The concentrations of grain zinc, iron and protein in wild accessions were about two-fold greater than in the domesticated genotypes. Concentrations of these compounds were positively correlated with one another, with no clear association with plant productivity, suggesting that all three nutrients can be improved concurrently with no yield penalty. A subset of 12 populations revealed significant genetic variation between and within populations for all minerals. Association between soil characteristics at the site of collection and grain nutrient concentrations showed negative associations between soil clay content and grain protein and between soil-extractable zinc and grain zinc, the latter suggesting that the greatest potential for grain nutrient minerals lies in populations from micronutrient-deficient soils.

Conclusions

Wild emmer wheat germplasm offers unique opportunities to exploit favourable alleles for grain nutrient properties that were excluded from the domesticated wheat gene pool.