Determination of erodibility of a subtropical clay soil: a laboratory rainfall simulator experiment

Erodibility of tropical soils changes according to land use and management. It is important to monitor these changes so that farming practices can be designed to conserve the soil. On a fersiallitic clay soil in Zimbabwe, the mean weight diameter of water-stable aggregates was highly significant in explaining variations in both soil loss and runoff. Percent water-stable aggregates > 2 mm diameter was also significant and had the practical advantage of being easier to measure. Organic carbon in the soil largely explains the proportion of water-stable aggregates. These indices will aid management decisions on arable and grazing lands on this soil type, within the limits of the ranges tested.     

Effect of copper on the volatility of aroma compounds in a model mouth system

Copper is thought to influence aroma perception by affecting volatility of aroma compounds in the mouth through interaction with salivary components, especially proteins. Our objective was to identify the effect of copper on the volatility of aroma compounds and the role of copper-protein interaction in volatile chemistry in the mouth. Copper (2.5 mg/L) and four aroma compounds (hexanal, butyl acetate, 2-heptanone, and ethyl hexanoate, 0.5 microL/L each) were added to model systems containing water, electrolytes, and artificial saliva at different pH levels. Headspace concentration of each volatile was measured using SPME-GC analysis. Copper in the model systems increased headspace concentration of volatiles at pH 6.5, but no change in volatility was observed at pH 7.0. At pH 7.5, the presence of copper in the artificial saliva system containing mucin and alpha-amylase decreased headspace volatile concentration, whereas histatin did not cause any changes in volatility. Effect of copper on volatiles at pH 6.5 may be due to increased solubility of copper at lower pH. Salivary proteins seem to interact with copper at pH 7.5. The interaction may change configuration of binding sites for aroma compounds in mucin.     

Biological measurements in a nationwide soil monitoring network

In the Netherlands soil biological measurements are undertaken in a nationwide monitoring programme. The measurements are combined in the Biological Indicator of Soil Quality (BISQ). About 300 locations were selected in a random stratified design comprising stringent combinations of land use and soil type. All locations were sampled in a six-year cycle. In this contribution we describe the monitoring network and the BISQ and present average values for biomass, abundances and taxonomic diversity of various soil dwelling organisms derived from 10 years of measurements. We further highlight some results and discuss the possibilities in soil and land management policy frameworks for improving sustainable land management.     

Characterization of subtropical soils by mineral magnetic measurements

Abstract

This paper reports the use of mineral magnetic measurement techniques to characterize the iron oxide assemblage within soils of varying parent material type and water regime from subtropical region in Zhejiang Province, China. Results show that dryland soils formed on Quaternary red clay, limestone, arenaceous shale, and diluvium, exhibit a distinct ferrimagnetic profile with a magnetic susceptibility (χ) enhancement in surface horizon. This enhancement is interpreted as being due to pedogenic superparamagnetic (SP) ferrimagnetic grains, which is supported by a higher frequency dependent susceptibility (χ_fd) values. The χ and χ_fd have highly significant positive linear relationship with dithionite‐citrate‐bicarbonate (DCB) extractable iron (Fed) content. The upper horizon of paddy soil has extremely lower χ and χ_fd values than dryland soils formed on the same parent material. Soil with poorly‐drained condition has distinctly lower absolute χ and saturation isothermal remanent magnetization (SIRM) value than associated well‐drained soil. It indicates that reduction state is an important factor responsible for loss of SP ferrimagnetic minerals in soils.     

Ecological and genetic measurements of dispersal in a threatened dragonfly

Leucorrhinia caudalis is a rare dragonfly, threatened throughout its European distribution. The species was formerly widespread in the Swiss lowlands, but only a single population remained in the 1980s. However, a spread has recently been observed, with additional ponds being colonised, sometimes at considerable distance. Despite this evidence of recent long-distance dispersal, it is unknown whether L. caudalis regularly moves among ponds or whether this is a rather rare event. A combination of an ecological mark-resight and a population genetic study was applied to investigate contemporary dispersal and the genetic footprint of the recent population history of L. caudalis in Switzerland. DNA for genetic microsatellite analysis was extracted from exuviae. The mark-resight study and the genetic analysis gave congruent results. They showed that L. caudalis is mostly a sedentary species, with only a few contemporary dispersal events over distances up to 5 km being observed. The genetic analysis was in agreement with the recent population history of the Swiss populations. The oldest and largest population showed large genetic diversity and acted as source population for the recent spread of L. caudalis in Switzerland. Recurrent gene flow among this source population and close populations caused substantial local genetic variation in the latter, as well as low population differentiation. The two recently founded distant populations (?30 km distance) were genetically less diverse and highly differentiated. These distant populations and another recently colonised population also expressed signatures of genetic bottlenecks.     

Verification of identities in global cacao germplasm collections

The ex situ conservation of cacao genetic resources is in the form of field genebanks. Misidentified trees though, represent a serious problem to (i) curators, who need to capture genetic diversity, and (ii) users of germplasm material, who must be certain of the identities of the accessions for proper evaluation of their results. The presence of mislabelled trees was assessed from data compiled in the International Cocoa Germplasm Database (ICGD) 2000 v4.1CD-ROM, which contains the published records of cacao accessions in global holdings. Circumstantial evidence revealed that many germplasm collections, especially those in Brazil (CEPEC), Colombia (ICA), Costa Rica (CATIE), Côte d'Ivoire, Mexico, Malaysia, Togo, Trinidad (ICG,T) and Venezuela (EEC) probably possessed misidentified material. The severity of the problem ranged from 15–44 % and is suggested as an area for immediate resolution. Based upon the morphological data provided by the ICGD CD-ROM, several accessions were highly suspect, including 'EET 19 [ECU]', 'EET 48 [ECU]', 'EET 162 [ECU]', 'ICS 1', 'ICS 6', 'ICS 43', 'ICS 89', 'ICS 100', 'IMC 67', 'PA 121 [PER]', 'POUND 7 [POU]', 'SCA 6', 'SPA 9 [COL]', 'UF 29', 'UF 613' and 'UF 667'. However, the identification of mislabelled trees should depend ultimately on molecular analysis. Hence, the use of voucher specimens for verification is forwarded and the concept of a public domain database for microsatellite analyses of germplasm holdings is raised.     

Effect of apple particle state on the release of volatile compounds in a new artificial mouth device

Varying the crushing parameters in a model mouth apparatus gave different crushed apple samples, which were compared to apples crushed in the human mouth by six people. An image analysis method was developed to measure the similarity between apple particles after crushing in the artificial mouth and in the human mouth. Thus, experimental conditions were determined that produced fruit in a state closest to that obtained after mastication in a human mouth. The influence of these different conditions on the quantity of released volatile compounds was then studied.     

Mercury reactions in the human mouth with dental amalgams

This is a preliminary study of the reactions of mercury (Hg) in the human mouth with dental amalgams. It was conducted by analysing saliva samples from subjects with amalgam fillings and control subjects with no amalgams. Samples were collected both prior to and after cleaning the mouth. These samples were analyzed for elemental mercury (Hg⁰), inorganic mercury (Hg²⁺) and methylmercury (MeHg). We concluded that the concentrations after cleaning represented the systemic concentrations. Hg²⁺ and MeHg were found in all systemic samples from both subjects and controls, while Hg⁰ was found only in the samples from subjects with amalgams. In the control group, the concentrations found before and after cleaning the mouth were equivalent. In the amalgam group, concentrations of Hg²⁺ found before cleaning the mouth were 10 to 40 times higher than those found after cleaning, suggesting that the oxidation reaction of Hg° into Hg²⁺ takes place. For MeHg, a similar but less pronounced pattern as Hg²⁺ was found, supporting methylation in the mouth.     

Creatinine measurements in 24 h urine by liquid chromatography--tandem Mass Spectrometry

A simple, sensitive, and specific liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for determining urinary creatinine was developed and used to evaluate 24 h urine samples collected during an exposure study. Urine (1 microL) was diluted with methanol and then directly applied to LC-MS/MS. Under electrospray ionization (ESI) conditions, the transition molecules of creatinine and creatinine- d3 were observed at m/ z 114 > 44 and m/ z 117 > 47, respectively. The retention time of creatinine was 0.59 min. The linear range was 1-2000 ng/mL, with a detection limit in urine of 1 ng/mL. LC-MS/MS and colorimetric end-point methods were significantly associated ( R2 = 0.8785, p < 0.0001). The LC-MS/MS method to determine creatinine in 24 h urine samples had shorter retention times, was more sensitive, reliable, reproducible, simple, selective, and used a smaller sample size than other LC-MS/MS or commercial methods.     

Stability of ingested methylcellulose in the rat determined by polymer molar mass measurements by light scattering

Methylcellulose (MC) is ingested by humans in food and pharmaceutical formulations. The functional properties of MC like those of other linear polymers depend primarily on polymer length or molar mass for largely linear polymers. Although many studies in animals and humans have shown complete excretion of MC, in vitro human fecal fermentation studies indicate that MC can be degraded and presumably lose some of its functionality. In this study, MC polymer distribution in the feces from rats fed a diet containing 8% methylcellulose were compared to the fed MC. The water-soluble polymers in the feces were separated by a size exclusion chromatography (SEC) and the polymer distributions determined by multiple angle laser light scattering (MALLS). Detection of the fluorescent MC-calcofluor complex was used to confirm the identity of the eluting MC peak. All dietary MC was recovered in the feces. There is a small shift (P < 0.06) in the weight-averaged molecular weight of polymer distribution of MC extracted from the feces to 2.71 +/- 0.15 x 10(5) g/mol from 3.15 +/- 0.02 x 10(5) g/mol in the standard. There is also an increase in the polydispersity from 1.21 in the standard to 1.8 in the fecal extract. The distribution of the substituted methoxylated glucose monomers by gas chromatography also confirms the stability of MC fed to rats. The amount of actual hydrolysis is estimated to be about 0.1 glycosidic linkage/molecule. MC is not easily determined by standard dietary fiber methods, and SEC with MALLS and/or fluorescence may be a useful alternative.     

Widespread endocrine activity in river sediments in Hesse, Germany, assessed by a combination of in vitro and in vivo bioassays

Purpose  

There is a growing concern regarding the effects of endocrine disrupting compounds on humans and wildlife. Since some of them have the ability to bind to particulate matter, high concentrations can be reached in sediments of surface waters. The objective of this study was an assessment of 50 sediment samples from predominantly small rivers in the German federal state of Hesse with emphasis on endocrine activity.     

Groundwater Deterioration Caused by Induced Recharge: Field Survey and Verification of the Deterioration Mechanism by Stochastic Numerical Simulation

Our field survey showed that thequality of shallow groundwater around the KatsuraRiver in the Kyoto Basin was strongly affected by theinfiltration of river water. Furthermore, that thedeterioration of the groundwater in the southern areato the west of the Katsura River may be related to theincrease in groundwater extraction. To clarify themechanism of groundwater deterioration, we havedeveloped a stochastic method to simulate groundwaterflow. The results showed that there was a largereduction in the groundwater level where groundwaterextraction was intense and recharge flowed from theKatsura River to the high extraction areas in thesouthern region. Another simulation showed that if thegroundwater extraction was 10% of the present removalrate, there would be little recharge from the KatsuraRiver into the groundwater and the quality of thegroundwater would be improved. Thus, we conclude thatthe cause of groundwater deterioration is probably dueto the induced recharge of deteriorated river waterfrom the Katsura River.     

Atmospheric measurements of nitrogen dioxide with a sensitive luminol instrument

A highly sensitive, lightweight, portable instrument has been developed for continuous monitoring of N0₂ in air. It operates by detecting the chemiluminescence produced when N0₂ encounters a surface wetted with a specially formulated solution containing luminol. Unlike other chemiluminescent instruments it measures N0₂ directly and does not require prior conversion of N0₂ to NO. It does not respond to H₂0₂, NO, HNO₃, NH₃, CO, C0₂, S0₂ or organic nitrates. The only interferences encountered to date are from 0₃ and PAN with the response to 0₃ being less than 0.2% of its response to N0₂. The response time of the instrument is less than 1 s and its sensitivity is better than 5 pptv. The instrument shows a negative temperature dependence of about 2% °C^?1 which is compensated electronically. Measurements have been made with the instrument during a number of field missions in polluted urban and relatively clean rural air. The relative influences of photochemistry and transport from local sources has been observed. Simultaneous measurements made with this instrument and the unequivocal tunable diode laser absorption spectroscopy method have shown excellent agreement.     

Licochalcone a inhibits lipopolysaccharide-induced inflammatory response in vitro and in vivo

Licochalcone A (Lico A), a flavonoid found in licorice root (Glycyrrhiza glabra), is known for its antimicrobial activity and its reported ability to inhibit cancer cell proliferation. In the present study, we found that Lico A exerted potent anti-inflammatory effects in in vitro and in vivo models induced by lipopolysaccharide (LPS). The concentrations of TNF-α, interleukin (IL)-6, and IL-1β in the culture supernatants of RAW 264.7 cells were determined at different time points following LPS administration. LPS (0.5 mg/kg) was instilled intranasally (i.n.) in phosphate-buffered saline to induce acute lung injury, and 24 h after LPS was given, bronchoalveolar lavage fluid was obtained to measure pro-inflammatory mediator and total cell counts. The phosphorylation of mitogen-activated protein kinases (MAPKs) and nuclear factor-κB (NF-κB) p65 protein was analyzed by Western blotting. Our results showed that Lico A significantly reduced the amount of inflammatory cells, the lung wet-to-dry weight (W/D) ratio, protein leakage, and myeloperoxidase activity and enhances oxidase dimutase activity in mice with LPS-induced acute lung injury (ALI). Enzyme-linked immunosorbent assay results indicated that Lico A can significantly down-regulate TNF-α, IL-6, and IL-1β levels in vitro and in vivo, and treatment with Lico A significantly attenuated alveolar wall thickening, alveolar hemorrhage, interstitial edema, and inflammatory cells infiltration in mice with ALI. In addition, we further demonstrated that Lico A exerts an anti-inflammation effect in an in vivo model of acute lung injury through suppression of NF-κB activation and p38/ERK MAPK signaling in a dose-dependent manner.     

Kinetic solvent effects on phenolic antioxidants determined by spectrophotometric measurements

The effects of polar (acetonitrile and tert-butyl alcohol) and apolar (cyclohexane) solvents on the peroxyl-radical-trapping antioxidant activity of some flavonoids, catechol derivatives, hydroquinone, and monophenols have been studied. The inhibition rate constants k(inh) of the antioxidants have been determined by following the increase in absorbance at 234 nm of a dilute solution of linoleic acid at 50 degrees C containing small amounts of antioxidant and radical initiator. Despite the low concentration of linoleic acid, the peroxidation process has been confirmed to be a free radical chain reaction described by the classical kinetic laws for this process. However, in the evaluation of k(inh), a careful analysis of the peroxidation curve, absorbance versus time, must be done because the final oxidation products of phenols may absorb at 234 nm. Phenols with two ortho-hydroxyls are the most active antioxidants, with inhibition rate constants in the range of (3-15) x 10(5) M(-1) x s(-1) (in cyclohexane). Nevertheless, it has been observed that in tert-butyl alcohol (a strong hydrogen bond acceptor) the rate constants dramatically decline to values not detectable by the present kinetic method. In acetonitrile (a weaker hydrogen bond acceptor) instead, the phenols with two ortho-hydroxyls scavenge the peroxyl radicals with rate constants close to those in cyclohexane. From the kinetic solvent effect, the equilibrium constant of the first solvation step of hydroquinone with tert-butyl alcohol has been determined at 50 degrees C, K(1) = 2.5 +/- 0.5 M(-1).     

Calculation of radionuclide ground deposition by means of measurements on sewage sludge

The concentrations of various radionuclides have been measured in the incoming water, the outgoing water and the sludge from the sewage treatment plant serving the town of Lund in southern Sweden. The mean residence time for the water in the plant is 1 to 2 days, whereas for the sludge it is 3 to 4 weeks. Variations in the residence time, which may influence the efficiency of the plant, are related to the season of the year and the load on the plant. Measurements show that for ⁷Be, ⁵¹Cr, ¹³⁴Cs, and ¹³⁷Cs between 37 and 56% of the incoming activity leaves the plant with the sludge. For ¹⁰⁶Ru and ¹³¹I these figures lie between 6 and 14%. The deposition of ⁷Be has been measured at Lund and the relation between the deposition on the ground (Bq m^?2) and the activity concentration in the sludge (Bq kg^?1 dry weight) has been studied and found to by relatively constant at ?(0.8 ±0.2) kg m^?2. In measurements on sewage sludge, the detection limit for deposition of ⁷Be on the ground is around 16 Bq m^?2.     

Fast and local assessment of stilbene content in grapevine leaf by in vivo fluorometry

Stilbenes are grapevine phytoalexins. These highly fluorescent molecules are generally analyzed by HPLC. This technique allows accurate assay of different stilbenes, but it is destructive, time-consuming, and neglects their spatial distribution. This is why we have tested a new method based on in vivo fluorescence using commercial spectrofluorometers that allowed fast and local assessment of stilbene content in grapevine leaves. Stilbene synthesis in grapevine Vitis vinifera var. Muscat Ottonel leaves was induced by Plasmopara viticola inoculation or UV-C irradiation. Fluorescence was measured both from the abaxial and adaxial sides of leaves, then stilbene content was analyzed by HPLC. It varied from 0 in control leaves to 15 mg g-1 dry weight in UV-treated leaves. Highly significant regressions were found between HPLC stilbene content and the corresponding leaf UV-induced blue fluorescence. Thus, in vivo fluorescence is a good tool for a rapid study of stilbenes synthesis in grapevine leaves that can potentially be extended to other fluorescent molecules.     

核糖体展示模拟抗体Anticalin基因文库的构建及初步鉴定

脂质运载蛋白(lipocalin)是一类广泛存在于生物界的小分子蛋白质家族,具备一些抗体所没有的优点。为了构建库容量大、多样性好的核糖体展示模拟抗体Anticalin文库,本研究以脂质运载蛋白家族之一大菜粉蝶(Pieris brassicae)中提取到的胆汁三烯结合蛋白基因(bilin-binding protein,bbp)(GenBank登录号:X76568.1)为模板,设计了包含16个随机突变位点的引物,采用重叠延伸PCR技术(gene splicing by overlap extension PCR,SOE-PCR)构建bbp基因文库。然后,利用SOE-PCR法引入核糖体展示元件(T片段与P片段),体外构建核糖体展示模拟抗体Anticalin基因文库。结果表明,本研究成功构建了模拟抗体Anticalin基因文库,其库容达到3.76×1023,文库的可扩增性、完整性及多样性良好,为筛选多种小分子化学残留的模拟抗体提供了基础资料。     

Mechanistic Model for Predicting NO3-N Uptake by Plants and Its Verification

Some mechanistic models have been proposed to predict the No3^- concentrations in the soil solution at root surface and the NO3-N uptake by plants,but all these relatively effective non-steady state models have not yet been verified by and soil culture experiment.In the present study,a mathematical model based on the nutrient transport to the roots,root length and root uptake kinetics as well as taking account of the inter-root competition was used for calculation,and soil culture experiments with rice,wheat and rape plants grown on alkali,neutral and acid soils in rhizoboxes with nylon screen as a isolator were carried out to evaluate the prediction ability of the model through comparing the measured NO3-concentrations at root surface and N uptake with the calculated values.Whether the inter-root competition for nutrients was accounted for in the model was of less importance to the calculated N uptake but could induce significant changes in the relative concentrations of NO3^- at root surface.For the three soils and crops,the measured NO3-N uptake agreed well with the calculated one,and the calculated relative concentrations at root surface were approximate to the measured values.But an appropriate rectification for some conditions is necessary when the plant uptake parameter obtained in solution culture experiment is applied to soil culture.In contrast with the present non-steady state model,the predicted relative concentrations,which show an accumulation,by the Phillips‘ steady-state model were distinct from the measured values which show a depletion,indicating that the present model has a better prediction ability than the steady-state model.