Use of quantitative real-time PCR to estimate maize endogenous DNA degradation after cooking and extrusion or in food products

Polymerase chain reaction (PCR) is being used increasingly to detect DNA sequences for food quality testing for GM content, microbial contamination, and ingredient content. However, food processing often results in DNA degradation and therefore may affect the suitability of PCR or even DNA sequence detection for food quality assurance. This paper describes a novel approach using quantitative real-time PCR (qPCR) to estimate the extent of DNA degradation. With use of two maize endogenous nuclear sequences, sets of four qPCR assays were developed to amplify target sequences ranging from<100 bp to approximately 1000 bp. The maize nuclear sequences used encode chloroplastic glyceraldehyde-3-phosphate dehydrogenase and cell wall invertase. The utility of the qPCR approach for quantifying the effective concentration of maize DNA that is needed to amplify variable length DNA sequences was demonstrated using samples of maize cornmeal cooked in water for variable times, extrusion products developed using different barrel temperature and torque settings, and a range of food products from supermarket shelves. Results showed that maize DNA was substantially degraded by a number of processing procedures, including cooking for 5 min or more, extrusion at high temperatures and/or high torque settings, and in most processed foods from supermarket shelves. Processing also reduced the effective concentration of DNA sequences capable of directing amplification of the <100 bp assays as well, particularly after popping of popping corn or extrusion at a combination of high temperature and torque settings. The approach for quantifying DNA degradation described in this paper may also be of use in disciplines where understanding the extent of DNA degradation is important, such as in environmental, forensic, or historical samples.     

粮食作物锌的吸收运转分配和改善子粒锌含量的理论与技术途径

基于前人取得的主要成果，系统分析了从土壤锌有效性到锌在子粒部位的积累主要过程及其控制点，从三方面：1）植株对锌的吸收过程；2）锌在地上部各营养器官间的运转分配过程；3）锌从营养器官向子粒部位的运转过程，总结并提出今后应利用作物锌高效性的种质资源特点，通过传统育种与生物技术方法选育出锌高效积累型品种和合理配套的栽培技术等农艺措施，提高作物子粒锌的含量。     

Use of force-deformation curves to estimate Young's modulus and its applications to soil aggregate breakdown

Soil aggregates from a clay and a sandy loam were subjected to uniaxial compression and their force-deformation relationships determined. From these relationships the elastic deformation was identified, and estimates were made of Young's modulus, elastic strain energy and work of fracture. Also estimated were the increases in surface area produced on breakdown and hence surface energies. The results were interpreted in terms of Griffith's crack theory, and apparent crack lengths were calculated. The calculated values were high, but the variability of the data prevented a full assessment of this approach to the study of brittle failure of aggregates.     

Effect of dietary ligands and food matrices on zinc uptake in Caco-2 cells: implications in assessing zinc bioavailability

The kinetics, depletion/repletion of zinc, and effects of dietary ligands/food matrices on (65)Zn uptake was studied in Caco-2 cells. The uptake of zinc showed a saturable and nonsaturable component, depending upon the media zinc concentrations. Intracellular depletion increased zinc uptake, whereas zinc loading did not. Phytic acid and histidine inhibited zinc uptake, while tannic acid, tartaric acid, arginine, and methionine increased zinc uptake. Tannic acid at a 1:50 molar ratio promoted zinc uptake from wheat- and rice-based food matrices. Further, Caco-2 cells responded similarly with zinc and iron uptake when fed Indian bread prepared from low- and high-extraction wheat flour, representing low and high phytate content. However, inclusion of tea extract or red grape juice as a source of polyphenols enhanced the uptake of zinc while decreasing that of iron. These results suggest that the Caco-2 cells predict the correct direction of response to dietary ligands even from complex foods.     

湖北江汉平原农田生态系统锌素的平衡分析

湖北江汉平原农田生态系统麦-稻、稻-稻、油菜-大豆、油菜-花生、小麦-芝麻、小麦-棉花、青椒-大白菜、萝卜-茄子等8种种植模式农田Zn素的循环研究表明,土壤Zn的输入途径和输入量顺序菜田和水田为有机肥>降雨>归还>灌溉>种子(种苗),旱地为降雨>有机肥>归还>灌溉>种子(种苗),输出途径作物收获占96％～97.6％,平均96.7％,农田Zn流失和淋溶损失相对较少。该区域菜田Zn素盈余较多,稻田一盈一亏,旱田施有机肥和施Zn肥处理Zn有盈余,不施Zn肥和有机肥2种模式出现亏缺。     

Using farmland prices to evaluate cost-efficiency of national versus regional reserve selection in Denmark

The current study focuses on the influence of geopolitical coordination of conservation strategies on cost and efficiency in terms of species representation when selecting network of protected areas. Conservation policies in the EU are implemented at many different administrative levels: from the European Union and national levels, to regional or/county levels within member countries. This arise the question what size of efficiency gains could be achieved if planning of conservation priorities could be coordinated between geopolitical units. Using data for the nationwide distribution of 763 species, representing all Danish species within eight taxa, we compared illustrative costs for the addition of new areas to the existing conservation network in order to ensure full coverage of all species. We found that the cost of independent regional planning is 20-fold higher than an inter-regional and nationally co-ordinated strategy. We also found that substituting land prices for a simple land-area measure in our analyses increased the expected conservation costs differential significantly, without increasing coverage of species representations. We suggest that in economic and biodiversity terms it can largely be a win-win situation to set a common goal, to develop priority-strategies, and to coordinate actions at higher rather than lower levels of administration.     

Potential Use of Nitrogen Reflectance Index to estimate Plant Parameters and Yield of Maize

Estimating the spatial variability of various plant parameters during the growing season can assist in timely correction of stress conditions within a field. This research illustrates that the nitrogen reflectance index (NRI) developed to estimate plant nitrogen status can be used to estimate plant parameters and yield potential. The study was conducted on two experimental maize sites. Selected maize hybrids were ‘Pioneer 3790’, which was a planophile canopy architecture and ‘NC+ 1598’ with an erectophile canopy architecture. The first site consisted of six non-replicated fertiliser plots. Data from these plots were used to develop the relationships between reflectance data and the plant parameters. The second site contained four plots with various nitrogen (N) and water treatments on which the developed relationships were verified. Leaf area, biomass, and plant reflectance data were collected almost weekly from both sites during the 1996 growing season. Measured and estimated yield, leaf area index (LAI) and dry matter were mapped in ArcVIEW geographical information system. Results showed that the NRI was a comparable estimator of potential yield to the normalised difference vegetation index or to the modified soil adjusted vegetation index. For the LAI and biomass, all vegetation indices produced similar coefficients of determination. Results showed that the NRI could be used to estimate the within-field variation of yield potential and plant parameters.     

Nature conservation in Italy: Proposed national and regional parks and other areas deserving protection

The complex geological history of Italy is responsible for the remarkable number of different landscapes and ecosystems present today. The immigration of animals and plants from neighbouring lands, when natural bridges were available, the survival of warm species along the coast during the Quaternary glaciations, and the relict populations which remained in the Apennines after the withdrawal of the ice, have all contributed to the richness of wildlife. In order to preserve adequately this biotic variety it is necessary to protect a large number of separate areas as National or Regional Parks or as nature reserves. In addition, the existence of important bird migration routes along or across the Italian peninsula and islands makes it necessary to provide safe areas where these birds can rest and feed. In spite of these needs, the State and the Regional Governments are not sufficiently concerned with wildlife and environmental conservation and so far have done very little to improve the protection of nature in Italy. In this paper 56 main areas are discussed which are in urgent need of protection from commercial speculation and the threat of irreparable damage. The authors hope that national and international public opinion will encourage the Italian Government to establish many more protected territories and to provide the resources for realistic management.     

Use of mineralization kinetics to estimate the potentially mineralizable nitrogen of rock phosphate-enriched composts-amended soil

Predicting nitrogen (N) mineralization has been one of the greatest challenges to improving N management in agriculture. A laboratory incubation experiment was conducted to study the N mineralization of soil amended with rock phosphate (RP)-enriched composts. The RP-enriched rice straw compost amended soil mineralized highest N as compared to compost prepared from mustard stover and tree leaves. The first-order model was found to be the most suitable for N because it provided the best fit to the experimental data and for its simplicity. The model predicted that potentially mineralized N (N₀) was varied from 4.0 to 52.1 mg kg^?1 and the mineralization rate k varied from 0.015 to 0.066 day^?1. The rice straw compost amended soil had higher N₀ value than mustard stover and tree leaves compost amended soil. This study demonstrated the importance of application of rock phosphate-enriched composts in improving N supplying capacity of soil.     

国内外主要粮食作物对施用锌肥响应的研究进展

【目的】 锌 (Zn) 对于人体健康至关重要，缺Zn会影响人体正常发育，并易受致病菌的入侵，降低人体耐受氧化胁迫的能力。人体主要通过摄食的方式补Zn，占全球50%的用于种植粮食作物的耕地缺Zn，主要粮食作物中可食部分的Zn含量普遍偏低，世界上50%的人口健康受到了影响。本文通过探讨国内外主要粮食作物对Zn肥施用的响应，旨在为以后相关的作物富Zn研究提供理论依据。 主要进展 施用Zn肥可以有效改善主要粮食作物籽粒部分的缺Zn状况，土施与叶面喷施均可提高主要粮食作物小麦、水稻和玉米可食部分的Zn含量，并能够增加产量。但由于受到土壤pH、有机质含量等的影响，土施Zn肥有效性偏低，施用的量较大，Zn肥的表观利用率低于叶喷Zn肥，叶喷Zn肥的增产效果显著低于土施Zn肥；锌肥的效果还受营养元素之间交互作用的影响，Zn与P和Fe存在拮抗作用，与Cu存在协同作用；Zn元素在籽粒的不同组份中为不均匀分配，在麦麸、小麦籽粒、白面粉中的含量依次递减，在水稻籽粒、糙米、精米中的含量也依次下降，Zn元素在主要食用的白面和精米中的分配较低；小麦籽粒部分的Zn来自于根的吸收以及茎和叶的再分配，水稻籽粒部分的Zn主要来自于根的吸收。 问题与展望 目前有关Zn在肥–土–作物系统中的迁移分配规律尚不清楚，施用Zn肥的成本较高，肥料中各营养元素的最佳投入量与最佳配比还不确定。因此，Zn肥施用可在以下六个方面进行深入研究:1) Zn元素在肥–土–作物系统中的吸收分配机制，清楚掌握Zn元素在肥–土–作物系统中的富集与分配规律，建立全国主要农田土壤的Zn数据库，构建产量、富Zn量与Zn肥之间的响应模型；2) 研发肥料施用技术及新型廉价肥料，降低补施Zn肥的成本；3) 继续研究Zn与其它营养元素之间的协同和拮抗作用，找到最佳投入量与最佳配比，整体提升粮食作物的营养价值；4) 改善土壤理化性质，提高Zn肥对于农作物的有效性及其肥效的持久性；5) 加强高富Zn品种的筛选，获得对Zn肥高产量与高富Zn量响应的品种类型；6) 研究主要粮食作物富Zn的分子生物学机制，进行品种的改良。      

Use of organic carbon and loss-on-ignition to estimate soil organic matter in different soil types and horizons

Summary Loss-on-ignition (LOI) and the organic C content have been used to estimate soil organic matter. Organic matter is often estimated from organic C by applying a factor of 1.724. Several authors have examined the relationship between LOI, used as an estimate of organic matter, and C by simple linear regressions. In the present study, this approach was examined in relation to two sets of data. LOI overestimates organic matter in soils with significant proportions of clay minerals because of bound water, and correcting for bound water gives some LOI: C ratios of less than 1. It is concluded that differences in the nature of the organic matter in different soils and horizons make the simple regression approach unsuitable. More attention needs to be paid to studies of the nature of the organic matter.     

Use of the RothC model to estimate the carbon sequestration potential of organic matter application in Japanese arable soils

We estimated the carbon (C) sequestration potential of organic matter application in Japanese arable soils at a country scale by applying the Rothamsted carbon (RothC) model at a 1-km resolution. After establishing the baseline soil organic carbon (SOC) content for 1990, a 25-year simulation was run for four management scenarios: A (minimum organic matter application), B (farmyard manure application), C (double cropping for paddy fields) and D (both B and C). The total SOC decreased during the simulation in all four scenarios because the C input in all four scenarios was lower than that required to maintain the baseline 1990 SOC level. Scenario A resulted in the greatest depletion, reflecting the effects of increased organic matter application in the other scenarios. The 25-year difference in SOC accumulation between scenario A and scenarios B, C and D was 32.3, 11.1 and 43.4 Mt C, respectively. The annual SOC accumulation per unit area was similar to a previous estimate, and the 25-year averages were 0.30, 0.10 and 0.41 t C ha⁻¹ year⁻¹ for scenarios B, C and D, respectively. The system we developed in the present study, that is, linking the RothC model and soil spatial data, can be useful for estimating the potential C sequestration resulting from an increase in organic matter input to Japanese arable soils, although more feasible scenarios need to be developed to enable more realistic estimation.     

Use of the RothC model to estimate the carbon sequestration potential of organic matter application in Japanese arable soils

Abstract

We estimated the carbon (C) sequestration potential of organic matter application in Japanese arable soils at a country scale by applying the Rothamsted carbon (RothC) model at a 1-km resolution. After establishing the baseline soil organic carbon (SOC) content for 1990, a 25-year simulation was run for four management scenarios: A (minimum organic matter application), B (farmyard manure application), C (double cropping for paddy fields) and D (both B and C). The total SOC decreased during the simulation in all four scenarios because the C input in all four scenarios was lower than that required to maintain the baseline 1990 SOC level. Scenario A resulted in the greatest depletion, reflecting the effects of increased organic matter application in the other scenarios. The 25-year difference in SOC accumulation between scenario A and scenarios B, C and D was 32.3, 11.1 and 43.4?Mt?C, respectively. The annual SOC accumulation per unit area was similar to a previous estimate, and the 25-year averages were 0.30, 0.10 and 0.41?t?C?ha^?1?year^?1 for scenarios B, C and D, respectively. The system we developed in the present study, that is, linking the RothC model and soil spatial data, can be useful for estimating the potential C sequestration resulting from an increase in organic matter input to Japanese arable soils, although more feasible scenarios need to be developed to enable more realistic estimation.     

Zinc transport in Caco-2 cells and zinc balance in rats: influence of the heat treatment of a casein-glucose-fructose mixture

The effects of the heat treatment of casein in the presence of glucose-fructose on Zn bioavailability were studied. Changes in Zn speciation were compared after in vitro digestion of heated (HC) and unheated mixture (C) alone and as part of the diet. The uptake and transport of digested soluble Zn was investigated in Caco-2 cells grown in bicameral chambers; balance studies were done in rats fed diets containing the different samples. After in vitro digestion, the precipitated Zn was significantly higher in HC than in C. In assays with Caco-2 cells, the amount of Zn transferred from the apical to the basolateral chamber was significantly greater when the culture medium contained raw or heated casein. However, because a larger proportion of Zn was precipitated by in vitro digestion, Zn utilization was less efficient in the presence of casein. In biological experiments, food efficiency of the heated casein-glucose-fructose diet was lower, and feeding this diet increased the urinary Zn excretion and lowered Zn absorption and retention. The effects of browning products generated during food processing should be taken into account, especially in diets containing marginally adequate levels of Zn, to prevent possible deficiency.     

Arsenic, lead, and zinc compounds in contaminated soils according to EXAFS spectroscopic data: A review

The application of the synchrotron technique of the third generation in soil science has permitted researchers to perform a quantitative mineralogical microanalysis in undisturbed samples and to reveal the relationship between the microelements and the solid phase of soils. Three principal methods are used in this technique: microfluorescence (μXRF), microdiffraction (μXRD), and the expanded analysis of the fine structure of the adsorption spectra. By the data of EXAFS spectroscopy, secondary arsenic was found to occur in three forms in soils, i.e., As adsorbed on iron hydroxides, scorodite (FeAsO₄ · 2H₂O, and As⁵⁺ containing jarosite. Despite the high share of carboxyl groups in the organic substance of soils, lead is more readily chelated by the functional groups of aromatic rings to form bidentant complexes. Lead phosphates are the most stable form of Pb in soils. One of the phosphates, i.e., pyromorphite Pb₅(PO₄)₃Cl has been found in ore tailings, lawn soils, soils near some chemical plants, and in soils within geochemical anomalies. The secondary Zn compounds are represented by Zn-containing silicate (kerolith) Si₄Zn₃O₁₀(OH)₂ and, to a lesser extent, by zinc fixed by manganese oxides (birnessite) and iron hydroxides (feroxyhyte).     

Use of an inverse method and geostatistics to estimate soil hydraulic conductivity for spatial variability analysis

A field method for determining the soil hydraulic properties using a parameter estimation technique is presented. Input data for the inverse problem are soil-water potentials and soil-water contents measured at different soil depths and different times during a field transient drainage experiment. For the water retention function the parametric relation suggested by Van Genuchten was adopted. For the hydraulic conductivity function the relation proposed by Van Genuchten and the exponential relation were adopted.

With the proposed method soil hydraulic properties along a transect of a volcanic Vesuvian soil were determined using as boundary condition the unit gradient of total potential at the bottom of the soil profile. Geostatistics were used to describe the spatial variability of hydraulic conductivity characteristics of the soil here considered.

Finally, results obtained using this method were compared with those of the simplified method suggested by Sisson and Van Genuchten based on a unit gradient water flow model.     

东北黑土区侵蚀沟发展状况及其对粮食安全的影响

通过对东北黑土区典型流域1965和2005年各种类型侵蚀沟的数量、长度、密度、面积(主要为吞食耕地面积)和分布情况以及40年来侵蚀沟的时空变化特征等进行分析,研究东北黑土区侵蚀沟发展状况对粮食安全的影响。结果表明:1)从1965至2005年的40年,研究区侵蚀沟总面积增加85.27 km2,条数增加13 168条,总长度增加6 183.70 km,沟壑密度由1965年的0.034 km/km2变化为2005年的0.193 km/km2,侵蚀沟条数、面积和密度呈快速增加趋势;2)40年间,耕地上的侵蚀沟面积增加81.83 km2,条数增加12 825条,长度增加5 981.23 km,沟壑密度增加0.271 km/km2,林地与其他用地上的侵蚀沟面积增加3.44 km2,条数增加343条,长度增加202.47 km,沟壑密度增加0.02 km/km2;3)典型黑土区侵蚀沟发生在耕地上的比例极大,其中面积所占比例达96%,条数所占比例达97.4%,说明40年来侵蚀沟的发展主要在耕地上。研究结果对区域的粮食生产和国家的粮食安全具有重要意义。