Effect of High‐Molecular‐Weight Glutenin Subunit Allelic Composition on Wheat Flour Tortilla Quality

Wheat cultivars possessing quality attributes needed to produce optimum quality tortillas have not been identified. This study investigated the effect of variations in high‐molecular‐weight glutenin subunits encoded at the Glu‐1 loci (Glu‐A1, Glu‐B1, and Glu‐D1) on dough properties and tortilla quality. Flour protein profiles, dough texture, and tortilla physical quality attributes were evaluated. Deletion at Glu‐D1 resulted in reduced insoluble polymeric protein content of flour, reduced dough compression force, and large dough extensibility. These properties produced very large tortillas (181 mm diameter) compared with a control made with commercial tortilla wheat flour (161 mm). Presence of a 7 + 9 allelic pair at Glu‐B1 increased dough strength (largest compression force, reduced extensibility, and small‐diameter tortillas). Deletion at Glu‐A1 produced large tortillas (173 mm) but with unacceptable flexibility during storage (score <3.0 at day 16). In general, presence of 2* at Glu‐A1, in combination with 5 + 10 at Glu‐D1, produced small‐diameter tortillas that required large force to rupture (tough texture). Presence of 2 + 12 alleles instead of 5 + 10 at Glu‐D1 produced tortillas with a good compromise between diameter (>165 mm) and flexibility during storage (>3.0 at day 16). These allele combinations, along with deletion at Glu‐D1, show promise for tortilla wheat development.     

Growth responses of maize,soybean, and tomato to sulphur dioxide and ozone exposure patterns utilizing an incomplete block factorial experimental design

Maize (Zea mays L.), soybean (Glycine max L.), and tomato (Lycopersicon esculentum Mill.) plants were grown in a controlled environment and exposed for 6 hr daily for 7 days to O₃ at 0.15 μL L^?1 and/or SO₂ at 0.30 μL L^?1 (daily exposures). Some plants exposed daily to O₃ were also exposed to SO₂ for 6 hr on the first, third, fifth, or seventh day of O₃ exposure (variable exposures) and some plants exposed daily to SO₂ were treated similarly with O₃ to determine the growth effects of O₃ or S0₂ pre- and/or post-treatments on S0₂ and O₃ mixture response. Growth sensitivity to 6 hr S0₂ or 6 hr O₃ treatments was generally affected by the previous history of O₃ or SO₂ exposure, respectively. Species differed in the number of days of O₃ or SO₂ treatments required to elicit maximum sensitivity to a single 6 hr O₃ and SO₂ treatment. Linear contrasts compared variable with daily exposures for the S0₂ and O₃ regimes. Plants exposed to the gas mixture for a single day (variable exposures) tended to be smaller than those exposed to the gas mixture daily, with the exception of soybean exposed to SO₂ during daily O₃. The six treatments were carried out in eight exposure chambers, as a partially balanced incomplete block design in blocks of four due to separate environmental control of the exposure facilities. The partially balanced incomplete block design proved to be about 2.6 times as efficient as a complete block design. The inclusion of covariates further increased precision.     

Detection of Cryptosporidium parvum and Cryptosporidium muris in soil samples

 The flotation procedure for the detection of Cryptosporidium parvum and Cryptosporidium muris oocysts in feces was adapted for use on soil samples. Soil samples were seeded with known amounts of purified C. parvum or C. muris oocysts and Cryptosporidium spp.-free bovine feces. The limit of detection for this procedure was determined at different levels of inoculation for each species. At each level of inoculation, 30 control samples were processed and the observer was blind to the status of the sample. All samples were examined for the presence of Cryptosporidium spp. oocysts using phase-contrast microscopy. The samples were seeded with the following estimated counts of C. parvum oocysts: 1000/g, 1250/g, and 1500/g. These levels had sensitivities of 88%, 90%, and 93%, respectively. All inoculation levels had a specificity of 100%. Thirty additional samples were inoculated with C. muris and the limit of detection was found to be 76 oocysts/g sample, with a sensitivity of 97% and a specificity of 100%. Received: 4 October 1999     

Identification and quantification of aminophospholipid-linked Maillard compounds in model systems and egg yolk products

While the Maillard reaction of free amino acids and proteins is a well-established process, no defined structures from the nonenzymatic browning of aminophospholipids in foodstuffs have been described so far. Phosphatidylethanolamine (PE)-linked glucosylamines (Schiff-PE), Amadori products (Amadori-PE), 5-hydroxymethylpyrrole-2-carbaldehydes (Pyrrole-PE), and carboxymethyl (CM-PE) as well as carboxyethyl (CE-PE) derivatives were detected and quantified by liquid chromatography- electrospray mass spectrometry (LC-(ESI)MS). Model incubations of soy-PE and D-glucose were employed to firmly establish the LC-(ESI)MS procedure. Analyses of spray-dried egg yolk powders and lecithin products derived therefrom show one-fourth of the native D-glucose content of egg yolk to be transformed to Amadori-PE, corresponding to a PE derivatization quota of 11-15.5 mol %. Schiff-PE and Pyrrole-PE were present only in low amounts, no CM-PE and CE-PE could be identified in any of the investigated samples. The high glycation rate of egg yolk PE will influence the emulsifying properties and perhaps even the oxidation resistance of the respective products.     

Effect of chemical composition on the release of nitrogen from agricultural plant materials decomposing in soil under field conditions

Summary In two field experiments, plant materials labelled with ¹⁵N were buried separately within mesh bags in soil, which was subsequently sown with barley. In the first experiment, different parts of white clover (Trifolium repens), red clover (T. pratense), subterranean clover (T. subterraneum), field bean (Vicia faba), and timothy (Phleum pratense) were used, and in the second, parts of subterranean clover of different maturity. The plant materials were analysed for their initial concentrations of total N, ¹⁵N, C, ethanol-soluble compounds, starch, hemicellulose, cellulose, lignin, and ash. After the barley had been harvested, the bags were collected and analysed for their total N and ¹⁵N. In the first experiment the release of N was highest from white clover stems + petioles (86%) and lowest from field bean roots (20%). In stepwise regression analysis, the release of N was explained best by the initial concentrations of lignin, cellulose, hemicellulose, and N (listed according to decreasing partial correlations). Although the C/N ratio of the plant materials varied widely (11–46), statistically the release of N was not significantly correlated with this variable. The results of the second experiment using subterranean clover of different maturity confirmed those of the first experiment.     

Effect of mycorhiza-forming fungus <Emphasis Type="Italic">Glomus intraradices</Emphasis> on phytoextraction of nickel and copper and status of microbe cenoses under conditions of a model experiment

Effect of inoculation of plants by mycorhiza-forming fungus Glomus intraradices on nickel and copper phytoextraction from soddy-podzolic soil has been studied. The soil was intentionally contaminated by these elements. Mycorhization may cause both a rise and a drop in the content of the elements in the above ground parts of plants. It is shown that inoculation of plants by mycorhiza-forming fungus by its application to the soil at seeding does not result in the destabilization of microbe cenoses in the variants with application of heavy metals and in control variants.     

坡面过程、块体移动和土壤侵蚀研究进展

Soil erosion and land degradation are global problems and pose major issues in many countries.Both soil erosion and mass movement are two forms of land degradation and humans play important roles in these geomorphological processes.This paper reviews slope processes associated with mass movement and soil erosion and contributory factors,including physical and human agents.Acting together,these cause diverse geomorphological features.Slope processes are illustrated by reference to case studies from Brazil and UK.The causes and impacts of erosion are discussed,along with appropriate remedial bioengineering methods and the potential of the measures to prevent these types of environmental degradation.Although there are several agents of erosion,water is the most important one.Cultivation can promote soil erosion,due to ploughing and harvesting,which moves soil down slopes.Soil erosion and mass movement data would inform the viability of soil conservation practices.Integrated management of drainage basins offers a promising way forward for effective soil conservation and soil remedial bioengineering in Brazil and UK.     

Spatial Inference of Nitrate Concentrations in Groundwater

We develop a method for multiscale estimation of pollutant concentrations, based on a nonparametric spatial statistical model. We apply this method to estimate nitrate concentrations in groundwater over the mid-Atlantic states, using measurements gathered during a period of 10 years. A map of the fine-scale estimated nitrate concentration is obtained, as well as maps of the estimated county-level average nitrate concentration and similar maps at the level of watersheds and other geographic regions. The fine-scale and coarse-scale estimates arise naturally from a single model, without refitting or ad hoc aggregation. As a result, the uncertainty associated with each estimate is available, without approximations relying on high spatial density of measurements or parametric distributional assumptions.     

Characteristics of bacterial communities in hydromorphic soils of northern regions

An analysis of the abundance and taxonomical structure of the heterotrophic block of aerobic and conditionally anaerobic bacteria in hydromorphic tundra and taiga soils was carried out. The decline of the cultivating temperature from 20° to 5° did not result in the reduction of bacterial abundance. The spectrum of the bacterial dominants in the northern cryogenic soils is wider under 4–6°, which is indicative of the lowtemperature adaptation of bacteria. Oligotrophs and copiotrophs predominate the bacterial communities of the explored soils. However, among hydrolytic bacteria, active chitin destructors, represented by Bacillus and Janthinobacterium, were found.     

Moisture regime of typical chernozems under the mown Steppe and plowland of Kursk oblast under the anomalous weather conditions of the last decades

The analysis of long-term (since 1947) data on the water content of the upper 3-m-thick layer in the Streletskaya Steppe chernozems under annual mowing showed that the weather changes during the last decades (from 1972–1973 to 2005–2006) resulted in an increase in the soil wetting depth during the fall-winter-spring period and the frequency of the percolation, a decrease in the water consumption from the 150- to 300-cm layer during the growing season, and a decrease in the water deficit in the fall. Therefore, the total water content of the steppe chernozems increased, although to a significantly lesser degree than that found for the steppe plot with a succession of woody-shrub vegetation. In a perennial fallow, the water content of the soil layer also increased. The water supply of the 0- to 160-cm layer of chernozems under winter wheat and corn underwent no significant changes.