A mannose-binding protein from the cell surface of flocculent Saccharomyces cerevisiae (NCIM 3528): its role in flocculation

A cell surface lectin was isolated and purified to homogeneity from the cell walls of a highly flocculent strain of Saccharomyces cerevisiae (NCIM 3528) by chromatography on DEAE-cellulose, phenyl Sepharose and Sephacryl S-300. It showed a molecular mass of 40 kDa on SDS-PAGE. It is an acidic protein with a pI of 4.0 and contains 44% hydrophobic amino acids. The N-terminal sequence up to 10 amino acid residues showed at least 70% homology with the predicted N-terminal sequence of the putative FLO1 as well as FLO5 gene products. The mannose-binding nature of the lectin was indicated by its high affinity and specificity towards the branched trisaccharide of mannose, a ligand which also inhibits the flocculation of yeast cells. Immunofluorescence studies confirmed the presence of lectin on the yeast cell surface and lectin-specific IgGs prevented flocculation of the cells. This cell surface mannose-specific lectin probably plays an important role in flocculation, with the branched trimannoside on the cell wall being the apparent carbohydrate receptor. The N-terminal sequence data gives a primary indication that the lectin could be a product of one of the FLO genes.     

GE POL钻石鉴定:第二步

提出了 GE POL处理钻石的两步鉴定方法。第一 ,几乎所有的 GE POL钻石均为 a型 ,用 SSEF a型钻石检测仪可以区分近无色 a型钻石与其它类似颜色的钻石 ;第二 ,用拉曼光谱仪的 51 4 nm激光线可以获得这些 a型钻石的拉曼光谱。如果观察到 3 760 cm-1发光峰 ,则证明在钻石中存在少量 N-V心。所有研究的 GE POL钻石均显示这种发射。认为这是 GE处理钻石的特征 ,因此 ,显示 N-V心的近无色 a型钻石很可能是 GE POL处理钻石。还需要更多的样品来证实这一点。     

粘胶长丝应用的新的可能性

本文介绍了粘胶长丝的应用 ,特别是采用连续纺丝技术生产的粘胶长丝 (CSY粘胶长丝 )的特殊工艺要求 ,这些结论是意大利纺织时装行业和Radici集团多年的实验和竞争的结果。     

Use of diffusive gradients in thin films to measure cadmium speciation in solutions with synthetic and natural ligands: comparison with model predictions

The performance of the technique of diffusive gradients in thin films (DGT) was characterized in well-defined systems containing cadmium with chloride and nitrate ions, simple organic ligands (nitrilotriacetic acid and diglycolic acid), and Suwannee river fulvic acid for the pH range 5-8. Cd was fully labile in all Cd, Cl-, and NO3- solutions tested (I= 0.1 and 0.01 M), even atvery low Cd concentrations (10 nM), consistent with there being no binding of Cd to the diffusive gel. Diffusion coefficients of Cd-nitritotriacetic acid (NTA) and Cd-diglycolic acid (DGA) species were measured and found to be ca. 25-30% lower than the equivalent coefficient for free metal ions. These values were used to calculate concentrations of labile Cd from DGT measurements in solutions of Cd with NTA or DGA. Cd-NTA and Cd-DGA species were found to be fully DGT-labile. DGT devices that used a diffusive gel with a reduced pore size, which retarded the passage of fulvic acid species through the gel, were used to estimate the proportion of Cd complexed by fulvic acid. These results were compared with predictions of the solution speciation from models with default parameter values. ECOSAT, incorporating the NICA-Donnan model, correctly predicted the magnitude of the binding and its pH dependence, while predictions from WHAM V (with humic ion binding model V) and WHAM 6 (with humic ion binding model VI) were less satisfactory at predicting the pH dependence. Reasonable fits to the data could be obtained from WHAM 6 when the effective binding constant log K(MA) was changed from 1.6 to 1.5, the value of deltaLK1 from 2.8 to 1.0 to minimize the dependence on pH, and the value of deltaLK2 from 1.48 to 1.0 to decrease the strength of the strong bidentate and tridentate binding sites.     

Metabolism of [14C]-2,4,6-trinitrotoluene in tobacco cell suspension cultures

The metabolism of 2,4,6-trinitrotoluene (TNT) was investigated in tobacco cell suspension cultures amended with [14C]-TNT. Five metabolites were purified and characterized. Temporal evolution of metabolites was monitored during a 120 h incubation period. Metabolites structure was identified by acid and enzymatic hydrolysis, followed by electrospray ionization mass spectrometry and 1H and 13C NMR spectroscopy analyses. The majority of metabolites were conjugates formed by glycose conjugation on the hydroxylamine group of either 2-hydroxylamino-4,6-dinitrotoluene (2-HADNT) or 4-hydroxylamino-2,6-dinitrotoluene (4-HADNT), which led to monoglycoside then to diglycoside. Various diglycosides were observed with gentiobioside or sophoroside formation. Bound residues represented a small fraction (<10% of initial 14C) irrespective of the interval after TNT amendment. Free ADNT was detected only in the medium. This study highlights the central role played by HADNT in the TNT metabolic pathway in tobacco cell suspension culture, and the key role of these compounds and of glycosyltransferases in TNT phytoremediation processes.     

Behavior of Yersinia enterocolitica strains inoculated in model cheese treated with high hydrostatic pressure

The effects of high hydrostatic pressure treatment and the ability for survival, repair, and growth of three human pathogenic serotypes (O:1, O:3, O:8) of Yersinia enterocolitica were investigated in washed-curd model cheese made with pasteurized bovine milk. Samples were treated at 300, 400, and 500 MPa for 10 min at 20 degrees C and analyzed at 0, 1, 7, and 15 days to assess the viability of the Yersinia population. A long-term study (up to 60 days of ripening after high hydrostatic pressure treatment) was also undertaken. Treatments at 400 and 500 MPa caused maximum lethality, and only the treatment at 300 MPa showed significant differences (P < 0.05) between serotypes; the most baroresistant was O:3. Ability to repair and grow was not observed after 15 days of storage at 8 degrees C. Yersinia counts in untreated cheese samples also decreased below the detection limit at day 45 in the long-term study. These results suggest that the cheese environment did not allow recovery of injured cells or growth. A primary contributing factor to this effect seemed to be the low pH resulting from the production of lactic acid during cheese ripening.     

Role of humic acid and ouinone model compounds in bromate reduction by zerovalent iron

Experiments were conducted to examine the role of humic acid and quinone model compounds in bromate reduction by Fe(0). The reactivity of Fe(0) toward bromate declined by a factor of 1.3-2.0 in the presence of humic acid. Evidence was obtained that the quick complexation of humic acid with iron species and its adsorption passivated the iron surface and decreased the rate of bromate reduction by Fe(0). On the other hand, in the long run, the reduced functional groups present in humic acid were observed to regenerate Fe(II) and reduce bromate abiotically. Compared with the case of humic acid only, the simultaneous presence of Fe(II) and humic acid significantly increased the bromate removal rate. Fe(III)/Fe(II) acted as a catalyst in the oxidation of humic acid by bromate. Anthraquinone-2,6-disulfonate (AQDS) and lawsone did not cause any significant effect on the bromate reduction rate by Fe(0). However, the redox reactivity of lawsone in the presence of Fe(III) was evident, while AQDS did not show any under the tested conditions. The difference was attributable to the presence/ absence of reducing functional groups in the model compounds. The electron spin resonance further demonstrated that the redox functional groups in humic acid are most likely quinone-phenol moieties. Although the bromate reduction rate by regenerated Fe(II) is a few times slower than that by Fe(0), the reactive Fe(II) can be, alternatively, reductively formed to maintain iron surface activation and bromate reduction to prolong the lifetime of the zerovalent iron.     

Incorporation of hydroxypyridinone ligands into self-assembled monolayers on mesoporous supports for selective actinide sequestration

In this study, three isomers of hydroxypyridinones (1,2-HOPO, 3,2-HOPO, and 3,4-HOPO) were attached to self-assembled monolayers on mesoporous silica (SAMMS). The HOPO-SAMMS materials have superior solid adsorbents properties: they do not suffer from solvent swelling; their rigid, open pore structure allows rapid sorption kinetics; their extremely high surface area enables the installation of high functional density; and being silica-based, they are compatible with vitrification into a final vitreous waste form. Kinetics, equilibrium, and selectivity of the adsorptions of actinide on the HOPO-SAMMS at various pH values and in the presence of other metal cations, anions, and competing ligands are reported. Rapid sequestration of U(VI), Np(V), and Pu(IV) was observed. Very little competition from transition metal cations and common species was observed.     

Identification of temperature-dependent water quality changes during a deep well injection experiment in a pyritic aquifer

Artificial recharge is a technique used increasingly to supplement drinking water supplies. To assess the potential water quality changes that occur during subsurface passage, a comprehensive deep-well injection experiment was carried out for a recharge scheme, where pretreated, aerobic surface water was injected at 300 m depth into an anaerobic aquifer. Water quality parameters were recorded over the 854-days long injection phase. The evolution of the major ion and redox chemistry was analyzed with a three-dimensional reactive multicomponent transport model. It was found that the oxidation of pyrite was the main driverforwater quality changes and that reaction rates depended significantly on the spatially/temporally varying groundwater temperature. With the temperature-dependency of the oxidation reactions incorporated into the model, the simulations give an accurate picture of the temporal and spatial evolution of the hydrochemical changes that occurred during the experiment. To delineate the influence of physical and chemical processes on local concentration changes the results of the reactive transport model simulations were compared with the corresponding results from nonreactive simulations. The study emphasizes the suitability of mechanistic multicomponent reactive transport modeling as an integrative tool for data analysis when physical transport and chemical processes interact.     

In vivo visual reporter system for detection of estrogen-like substances by transgenic medaka

Detection of endocrine disrupting chemicals, in particular, environmental estrogens with living organisms, has many advantages if compared to chemical analysis. The screening of novel pollutants with meaningful endpoints, the integration of uptake, bioconcentration, and excretion as well as the evaluation of endocrine disrupting effects with respect to toxicity require in vivo biotests for estrogen-like substances (ELSs). Critical disadvantages of whole organism biotests are their low sensitivity and the need for laborious and time-consuming work. To overcome these problems, we have developed a transgenic medaka strain harboring the green fluorescence protein (GFP) gene driven by choriogenin H gene regulatory elements. Choriogenin H is an egg envelope protein induced by estrogens in the liver. With yolk sac larvae of this strain, GFP induction in liver was observed 24 h after onset of aqueous exposure to 0.63 nM 17beta-estradiol (E2), 0.34 nM ethynylestradiol, or 14.8 nM estrone. Furthermore, concentrated sewage treatment effluent induced GFP expression. Comparison of E2 equivalents estimated by GFP-induction in transgenic medaka, a YES assay, and GC/MS showed detection limits in the same order of magnitude. These results indicated that the sensitivity of the transgenic medaka strain was sufficient for application as an alternative model in monitoring environmental water samples for ELSs.