Fate of prions in soil: detergent extraction of PrP from soils

The transmissible spongiform encephalopathies (TSEs) are caused by infectious agents whose structures have not been fully characterized but include abnormal forms of the host protein PrP, designated PrP(Sc), which are deposited in infected tissues. The transmission routes of scrapie and chronic wasting disease (CWD) seem to include environmental spread in their epidemiology, yet the fate of TSE agents in the environment is poorly understood. There are concerns that, for example, buried carcasses may remain a potential reservoir of infectivity for many years. Experimental determination of the environmental fate requires methods for assessing binding/elution of TSE infectivity, or its surrogate marker PrP(Sc), to and from materials with which it might interact. We report a method using Sarkosyl for the extraction of murine PrP(Sc), and its application to soils containing recombinant ovine PrP (recPrP). Elution properties suggest that PrP binds strongly to one or more soil components. Elution from a clay soil also required proteinase K digestion, suggesting that in the clay soil binding occurs via the N-terminal of PrP to a component that is absent from the sandy soils tested.     

Fate of Listeria monocytogenes in bovine manure-amended soil

The survival and growth of Listeria monocytogenes in soil amended with bovine manure was studied under different environmental conditions of temperature, nutrients, and soil microflora. Autoclaved soil was compared with unautoclaved soil for assessing the influence of competitive soil microflora on the survival of L. monocytogenes. Initial L. monocytogenes cell numbers of 5 to 6 log CFU/g survived for up to 43, 43, and 14 days in manure-amended autoclaved soil at 5, 15, and 21 degrees C, respectively. In manure-amended unautoclaved soil, the pathogen was detectable for up to 43, 21, and 21 days at 5, 15, and 21 degrees C, respectively. L. monocytogenes was inactivated more rapidly in autoclaved soil amended with manure at a manure/soil ratio of 1:10 than in the more dilute (1:100) manure in soil samples at both 15 and 21 degrees C. However, in manure-amended unautoclaved soil, L. monocytogenes survived longer in samples with ratios of 1:10 than in the more dilute (1:100) manure-amended soil. The persistence of L. monocytogenes for several weeks in manure-amended soil suggests listeriae could be transmitted through soil to fresh produce or to shoes, clothing, and hands of field workers, especially during the cold months.     

Changes in zinc speciation in field soil after contamination with zinc oxide

Recent studies on the speciation of Zn in contaminated soils confirmed the formation of Zn-layered double hydroxide (LDH) and Zn-phyllosilicate phases. However, no information on the kinetics of the formation of those phases under field conditions is currently available. In the present study, the transformation of Zn in a field soil artificially contaminated with ZnO containing filter dust from a brass foundry was monitored during 4 years using extended X-ray absorption fine structure (EXAFS) spectroscopy. Soil sections were studied by micro-X-ray fluorescence (micro-XRF) and micro-EXAFS spectroscopy. EXAFS spectra were analyzed by principal component analysis (PCA) and linear combination fitting (LCF). The results show that ZnO dissolved within 9 months and that half of the total Zn reprecipitated. The precipitate was mainly of the Zn-LDH type (>75%). Only a minor fraction (<25%) may be of Zn-phyllosilicate type. The remaining Zn was adsorbed to soil organic and inorganic particles. No significant changes in Zn speciation occurred from 9 to 47 months after the contamination. Thermodynamic calculations show that both Zn-LDH and Zn-phyllosilicate may form in the presence of ZnO but that the formation of Zn-phyllosilicate would be thermodynamically favored. Thus, the dominance of Zn-LDH found by spectroscopy suggests that the formation of the Zn precipitates was not solely controlled bythermodynamics but also contained a kinetic component. The rate-limiting step could be the supply of Al and Si from soil minerals to the Zn-rich solutions around dissolving ZnO grains.     

Fate of sulphur compounds released from cellulose xanthate during its action as a soil conditioner

The distribution of the sulphur-containing compounds released from cellulose xanthate after its application to soil has been investigated by laboratory experiments using ³⁵S-labelled cellulose xanthate. It was shown that more than half of the sulphur contained in cellulose xanthate applied to soil was dispersed into the atmosphere, presumably as carbon disulphide. This release occurred rapidly during the first few hours and was virtually complete within 48 h. About 25% of the sulphur added was water soluble, and was leached through the soil by simulated rain. About 20% of the sulphur added remained attached to the soil in an insoluble form, some of it acid resistant. Ageing the cellulose xanthate for up to 14 days at 20°C before application had only minor effects on this fractionation. It is unlikely that the use of cellulose xanthate as a soil conditioner would have any appreciably harmful or unpleasant side effects, or cause damage to the environment.     

Fate of prions in soil: adsorption and extraction by electroelution of recombinant ovine prion protein from montmorillonite and natural soils

Prions, the infectious agents thought to be responsible for transmissible spongiform encephalopathies, may contaminate soils and have been reported to persist there for years. We have studied the adsorption and desorption of a model recombinant prion protein on montmorillonite and natural soil samples in order to elucidate mechanisms of prion retention in soils. Clay minerals, such as montmorillonite, are known to be strong adsorbents for organic molecules, including proteins. Montmorillonite was found to have a large and selective adsorption capacity for both the normal and the aggregated prion protein. Adsorption occurred mainly via the N-terminal domain of the protein. Incubation with standard buffers and detergents did not desorb the full length protein from montmorillonite, emphasizing the largely irreversible trapping of prion protein by this soil constituent. An original electroelution method was developed to extract prion protein from both montmorillonite and natural soil samples, allowing quantification when coupled with rapid prion detection tests. This easy-to-perform method produced concentrated prion protein extracts and allowed detection of protein at levels as low as 0.2 ppb in natural soils.     

Fate of brominated flame retardants and organochlorine pesticides in urban soil: volatility and degradation

As the uses of polybrominated diphenyl ethers (BDEs) are being phased out in many countries, soils could become a secondary emission source to the atmosphere. It is also anticipated that the demand for alternative brominated flame retardants (BFRs) will grow, but little is known about their environmental fate in soils. In this study, the volatility and degradation of BFRs and organochlorine pesticides (OCPs) in soil was investigated. A low organic carbon (5.6%) urban soil was spiked with a suite of BFRs and OCPs, followed by incubation under laboratory condition for 360 days. These included BDE- 17, -28, -47, -99; α- and β-1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH), β-1,2,5,6-tetrabromocyclooctane (TBCO), and 2,3-dibromopropyl-2,4,6-tribromophenyl ether (DPTE), OCPs: α-hexachlorocyclohexane (α-HCH) and (13)C(6)-α-HCH, trans-chlordane (TC), and (13)C(10)-TC. The volatility of spiked chemicals was investigated using a fugacity meter to measure the soil-air partition coefficient (K(SA)). K(SA) of some spiked BFRs and OCPs increased from Day 10 to 60 or 90 and leveled off afterward. This suggests that the volatility of BFRs and OCPs decreases over time as the chemicals become more strongly bound to the soil. Degradation of alternative BFRs (α- and β-TBECH, β-TBCO, DPTE), BDE-17, and α-HCH ((13)C-labeled and nonlabeled) was evident in soils over 360 days, but no degradation was observed for the BDE-28, -47, -99, and TC ((13)C-labeled and nonlabeled). A method to separate the enantiomers of α-TBECH and β-TBCO was developed and their degradation, along with α-HCH ((13)C-labeled and nonlabeled) was enantioselective. This is the first study which reports the enantioselective degradation of chiral BFRs in soils. Discrepancies between the enantiomer fraction (EF) of chemicals extracted from the soil by dichloromethane (DCM) and air were found. It is suggested that DCM removes both the sequestered and loosely bound fractions of chemicals in soil, whereas air accesses only the loosely bound fraction, and these two pools are subject to different degrees of enantioselective degradation. This calls for caution when interpreting EFs obtained from DCM extraction of soil with EFs in ambient air.     

Fate of prions in soil: interactions of RecPrP with organic matter of soil aggregates as revealed by LTA-PAS

The contribution of soil organic matter (OM) to the adsorption of a recombinant prion protein (RecPrP) was studied in microcosm systems (soil aggregates from two different soils) before and after OM removal by low temperature ashing (LTA). The LTA technique allows a controlled removal of OM layer by layer, like a peeling of an onion skin, with minimal disturbance of the mineral matrix. Soil aggregates were selected as a representative model of the "in situ" conditions. Adsorption from batch vs percolation experiments were compared, and the aggregates were characterized by photoacustic Fourier-transform IR spectroscopy (PAS-FTIR). High affinity (H-type) adsorption isotherms were found with complete removal of RecPrP from solution for protein/soil ratios up to 1:62.5. OM removal from aggregates decreased the adsorbed RecPrP in amounts corresponding to 330-1000 microg mg(-1) of soil organic carbon (OC) indicating that native OM has specific adsorption capacity comparable and/or superior to the mineral matrix. The coupled LTA-PAS-FTIR approach demonstrated that, albeit OM composition was homogeneous throughout the aggregates, its presence in the most external surfaces of the aggregates affects the diffusion dynamics of RecPrP within the aggregates during percolation.     

Fate of lysostaphin in milk from individual cows through pasteurization and cheesemaking

Transgenic cows secreting over 3 μg of lysostaphin/ mL of milk are protected against mastitis caused by Staphylococcus aureus, but it is unknown if active lysostaphin persists through dairy processing procedures or affects the production of fermented dairy foods. The objective of this study was to determine the fate of lysostaphin as milk was pasteurized and then processed into cheese. Raw milk from transgenic cows was heat treated at 63°C for 30 min, 72°C for 15 s (high temperature, short time), or 140°C for 2 s (UHT). Portions of the high temperature, short-time milk were manufactured into semi-hard cheeses. Aliquots taken at each processing step were assayed to determine the quantity (ELISA) and activity (ability to inhibit S. aureus growth) of lysostaphin. Results indicated that most of the lysostaphin was present in the aqueous portion of the milk and was not affected by pasteurization, although UHT treatment reduced enzyme concentration by 60%. The quantity and activity of the lysostaphin decreased during cheesemaking. Based on the amount of lysostaphin present in the starting cheesemilk, 10 to 15% of the lysostaphin was recovered in the whey, 21 to 55% in the cheese curd at d 1, and 21 to 36% in cheese stored at 4°C for 90 d. Enough of the lysostaphin secreted into milk by transgenic cows survived typical dairy processing conditions to impart potential value as a bioprotective agent against staphylococci in dairy foods.     

食品级丙酸锌的合成工艺研究

以丙酸钙和硫酸锌为原料,经复分解反应合成了一种新型食品添加剂-丙酸锌。此反应的优化条件是:丙酸钙∶硫酸锌=1.16∶1,丙酸钙=1.075mol/L,硫酸锌=1.239mol/L,反应温度为80℃,反应时间为40min。丙酸锌产率可达93.6%,其各项技术指标经检测符合同类产品食品级标准要求。     

曲靖市植烟土壤有效锌含量状况及与土壤因素的关系分析

研究了曲靖烟区土壤有效锌的分布状况及其与土壤类型、土壤质地与机械组成、pH、有机质的关系.结果表明:(1)曲靖烟区土壤有效锌含量较高,平均为4.37±8.45 mg/kg,变幅为0.05~194.19 mg/kg,变异系数高达193.09%,少部分烟区存在缺锌状况;(2)土壤有效锌含量随海拔升高、有机质含量增加而增大,随土壤粘粒含量增加、pH值升高呈现抛物线趋势;(3)不同土壤类型有效锌含量表现为:红壤>新积土>水稻土>石灰岩土>黄壤>酸性紫色土.     

Assessment of zinc deficiency and effect of dietary carrot, amchur and onion on zinc status during repletion in zinc-deficient rats

BACKGROUND: Food acidulants, β‐carotene‐rich vegetables and sulfur compound‐rich Allium spices are known to improve zinc bioaccessibility from food grains. This animal study evaluated the positive influence of these promoters of zinc bioaccessibility on zinc status during zinc repletion in Wistar rats previously rendered zinc‐deficient by feeding a zinc‐deficient semi‐synthetic diet for 4 weeks. Groups of these zinc‐deficient animals were subsequently maintained on a zinc‐containing grain‐based diet for 2 weeks. Various experimental diets consisted of the grain‐based diet supplemented with (1) carrot, (2) onion, (3) amchur, (4) carrot + amchur and (5) onion + amchur. RESULTS: Zinc deficiency was confirmed by lower zinc concentration in tissues and bones and lower activity of zinc‐containing enzymes. Zinc concentration was 10–15% lower in serum, liver and kidney of zinc‐deficient rats. Bone weight in zinc‐deficient rats was 20% lower than that in normal rats. Activities of zinc‐containing enzymes (hepatic superoxide dismutase and alcohol dehydrogenase and serum alkaline phosphatase) were lower in the zinc‐deficient group. Animals fed diets supplemented with these promoters of zinc bioaccessibility showed better zinc status in tissues and bones compared with those repleted with the control stock diet. CONCLUSION: This animal study supports the claim of promoters of zinc bioaccessibility for improving zinc status, which may find practical application. Copyright © 2011 Society of Chemical Industry     

Comparison of chemical tests for estimation of the availability of soil zinc

Tests for determining the availability of soil Zn were evaluated by simple and multiple correlation analysis. The soil tests included total Zn, and Zn extractable from soil by 0.2 M MgSO₄, 0.1 N HCl or dithizone. In simple correlation analyses, each of the tests correlated significantly with the uptake of soil Zn by maize (Zea mays L.) plants grown in the glasshouse. The predictions were improved significantly with all tests by the inclusion of one or more of the soil variables, pH and clay and organic matter contents, in multiple correlation analyses. The plant uptake of soil Zn could best be predicted from a multiple regression equation which included soil pH and logarithmic functions of 0.1 N HCl-extractable Zn and soil clay content as the independent variables.     

Fate of pentabrominated diphenyl ethers in soil: abiotic sorption, plant uptake, and the impact of interspecific plant interactions

Polybrominated diphenyl ethers (PBDEs) are potentially harmful and persistent environmental pollutants. Despite evidence that soils are a major sink for PBDEs, little is known regarding their behavior in this medium. An environmentally relevant level of a commercial penta-BDE mixture (75 microg kg(-1)) was added to topsoil, and the extractability of three congeners (BDE-47, -99, and -100) was monitored over 10 weeks in planted and unplanted treatments. The extractability of each congener decreased rapidly in the experimental soil due largely to abiotic sorption to soil particles, which was demonstrated by low PBDE recovery from sterilized and dry soils. Monoculture plantings of zucchini and radish did not affect the recovery of PBDEs from soil. However, PBDE recovery from mixed species plantings was nearly 8 times higher than that of unplanted and monoculture treatments, indicating that interspecific plant interactions may enhance PBDE bioavailablity in soil. Evidence for competitive interactions between the two species was revealed by reduced shoot biomass of zucchini plants in mixed treatments relative to pots containing only zucchini. Both plant species accumulated PBDEs in root and shoot tissue (<5 microg kg(-1) plant tissue). PBDE uptake was higher in zucchini, and translocation of PBDEs to zucchini shoots was congener-specific. Our results suggest that although abiotic sorption may limit the potential for human exposure to PBDEs in soil, plants may increase the exposure risk by taking up and translocating PBDEs into aboveground tissues and by enhancing bioavailability in soil.     

Inhibitory effect of zinc on beta-hexosaminidase release from RBL-2H3 cells by synthetic chemicals

The effects of foods and chemicals related to food hygiene on degranulation were evaluated using a method for assaying the enzyme activity of beta-hexosaminidase as an index of chemical mediator release from RBL-2H3 cells in vitro. Using a previously developed assay system, we had found a large number of inhibitors and promoters of degranulation of RBL-2H3 cells. In the present study, we examined the inhibitory effect of zinc chloride on the degranulation (beta-hexosaminidase release) from RBL-2H3 cells with or without antigen in the presence of the degranulation-promotive chemicals, namely, 4 food additives, 7 pesticides and 2 veterinary drugs. These promotive chemicals were classified into two types on the basis of inhibitory profile by zinc chloride: 1) those which showed marked degranulation-inhibitory action when the cells were stimulated with antigen, such as butylhydroxyanisole, dibutylhydroxytoluene, EPN, cis- and trans-permethrin, prothiofos, pyridaben, terbufos, 2) those which showed marked degranulation-inhibitory action whether the cells were stimulated with antigen or not, such as butyl p-hydroxybenzoate, o-phenylphenol, bitertanol, salinomycin. In conclusion, zinc had a dramatic inhibitory effect on enhanced degranulation induced by synthetic chemicals in vitro.     

Sequestration of zinc from zinc oxide nanoparticles and life cycle effects in the sediment dweller amphipod Corophium volutator

We studied the effects of ZnO nanoparticles [ZnO NPs, primary particle size 35 ± 10 nm (circular diameter, TEM)], bulk [160 ± 81 nm (circular diameter, TEM)], and Zn ions (from ZnCl(2)) on mortality, growth, and reproductive endpoints in the sediment dwelling marine amphipod Corophium volutator over a complete lifecycle (100 days). ZnO NPs were characterized by size, aggregation, morphology, dissolution, and surface properties. ZnO NPs underwent aggregation and partial dissolution in the seawater exposure medium, resulting in a size distribution that ranged in size from discrete nanoparticles to the largest aggregate of several micrometers. Exposure via water to all forms of zinc in the range of 0.2-1.0 mg L(-1) delayed growth and affected the reproductive outcome of the exposed populations. STEM-EDX analysis was used to characterize insoluble zinc precipitates (sphaerites) of high sulfur content, which accumulated in the hepatopancreas following exposures. The elemental composition of the sphaerites did not differ for ZnO NP, Zn(2+), and bulk ZnO exposed organisms. These results provide an illustration of the comparable toxicity of Zn in bulk, soluble, and nanoscale forms on critical lifecycle parameters in a sediment dwelling organism.