Sample records for affecting metal tolerance

  1. Regulatory focus affects physician risk tolerance. (United States)

    Veazie, Peter J; McIntosh, Scott; Chapman, Benjamin P; Dolan, James G


    Risk tolerance is a source of variation in physician decision-making. This variation, if independent of clinical concerns, can result in mistaken utilization of health services. To address such problems, it will be helpful to identify nonclinical factors of risk tolerance, particularly those amendable to intervention-regulatory focus theory suggests such a factor. This study tested whether regulatory focus affects risk tolerance among primary care physicians. Twenty-seven primary care physicians were assigned to promotion-focused or prevention-focused manipulations and compared on the Risk Taking Attitudes in Medical Decision Making scale using a randomization test. Results provide evidence that physicians assigned to the promotion-focus manipulation adopted an attitude of greater risk tolerance than the physicians assigned to the prevention-focused manipulation (p = 0.01). The Cohen's d statistic was conventionally large at 0.92. Results imply that situational regulatory focus in primary care physicians affects risk tolerance and may thereby be a nonclinical source of practice variation. Results also provide marginal evidence that chronic regulatory focus is associated with risk tolerance (p = 0.05), but the mechanism remains unclear. Research and intervention targeting physician risk tolerance may benefit by considering situational regulatory focus as an explanatory factor.

  2. Defect-Tolerant Monolayer Transition Metal Dichalcogenides

    DEFF Research Database (Denmark)

    Pandey, Mohnish; Rasmussen, Filip Anselm; Kuhar, Korina;


    -principles investigation of defect tolerance in 29 monolayer transition metal dichalcogenides (TMDs) of interest for nanoscale optoelectronics. We find that the TMDs based on group VI and X metals form deep gap states upon creation of a chalcogen (S, Se, Te) vacancy, while the TMDs based on group IV metals form only...... shallow defect levels and are thus predicted to be defect-tolerant. Interestingly, all the defect sensitive TMDs have valence and conduction bands with a very similar orbital composition. This indicates a bonding/antibonding nature of the gap, which in turn suggests that dangling bonds will fall inside...... the gap. These ideas are made quantitative by introducing a descriptor that measures the degree of similarity of the conduction and valence band manifolds. Finally, the study is generalized to nonpolar nanoribbons of the TMDs where we find that only the defect sensitive materials form edge states within...

  3. Heavy metal pollutant tolerance of Azolla pinnata

    Energy Technology Data Exchange (ETDEWEB)

    Sarkar, A.; Jana, S.


    The effects of Hg, As, Pb, Cu, Cd, and Cr (1,2 and 5 mg L/sup -1/ each) on Azolla pinnata R. Br. were analyzed. The treatments (2 and 5 mg L/sup -1/) of the heavy metal pollutants decreased Hill activity, chlorophyll, protein and dry wt, and increased tissue permeability over control values. The effects were most pronounced with the treatment of 5 mg L/sup -1/. The harmful effects of the metals were, in general, found by the treatments in the order: Cd > Hg > Cu > As > Pb > Cr. There was no significant change in these parameters at 1 mg L/sup -1/ of the metals over control. Thus Azolla pinnata shows tolerance to the heavy metals tested up to 1 mg L/sup -1/ each.

  4. Differential tolerance of Sulfolobus strains to transition metals (United States)

    Miller, K.W.; Sass, Risanico S.; Risatti, J.B.


    Sulfolobus acidocaldarius strains 98-3 and B12, and S. solfataricus ATCC 35091 were evaluated for tolerance to Cd, Co, Cu, Ni, Zn and Mg. The tolerance of strains 98-3 and ATCC 35091 to these metals was Mg > Zn > Cd > Cu ??? Co > Ni. For B12, however, the order of tolerance was Mg > Cd > Zn = Co > Ni > Cu. Tolerance to these metals is also presented as a potentially useful taxonomic indicator.

  5. Phenol degradation and heavy metal tolerance of Antarctic yeasts. (United States)

    Fernández, Pablo Marcelo; Martorell, María Martha; Blaser, Mariana G; Ruberto, Lucas Adolfo Mauro; de Figueroa, Lucía Inés Castellanos; Mac Cormack, Walter Patricio


    In cold environments, biodegradation of organic pollutants and heavy metal bio-conversion requires the activity of cold-adapted or cold-tolerant microorganisms. In this work, the ability to utilize phenol, methanol and n-hexadecane as C source, the tolerance to different heavy metals and growth from 5 to 30 °C were evaluated in cold-adapted yeasts isolated from Antarctica. Fifty-nine percent of the yeasts were classified as psychrotolerant as they could grow in all the range of temperature tested, while the other 41% were classified as psychrophilic as they only grew below 25 °C. In the assimilation tests, 32, 78, and 13% of the yeasts could utilize phenol, n-hexadecane, and methanol as C source, respectively, but only 6% could assimilate the three C sources evaluated. In relation to heavy metals ions, 55, 68, and 80% were tolerant to 1 mM of Cr(VI), Cd(II), and Cu(II), respectively. Approximately a half of the isolates tolerated all of them. Most of the selected yeasts belong to genera previously reported as common for Antarctic soils, but several other genera were also isolated, which contribute to the knowledge of this cold environment mycodiversity. The tolerance to heavy metals of the phenol-degrading cold-adapted yeasts illustrated that the strains could be valuable as inoculant for cold wastewater treatment in extremely cold environments.

  6. Hydroponic screening of black locust families for heavy metal tolerance and accumulation. (United States)

    Župunski, Milan; Borišev, Milan; Orlović, Saša; Arsenov, Danijela; Nikolić, Nataša; Pilipović, Andrej; Pajević, Slobodanka


    Present work examines phytoextraction potential of four black locust families (half-sibs 54, 56, 115, and 135) grown hydroponically. Plants were treated with 6 ppm of cadmium (Cd), 100 ppm of nickel (Ni), and 40 ppm of lead (Pb) added in Hoagland nutrient solution, accompanying with simultaneously applied all three metals. Responses to metals exposure among families were different, ranging from severe to slight reduction of root and shoot biomass production of treated plants. Calculated tolerance indices are indicating tested families as highly tolerant (Ti > 60). Family 135 had the lowest tolerance index, pointing that it was highly susceptible to applied metals. Comparing photosynthetic activities of tested families it has been noticed that they were highly sensitive to stress induced by heavy metals. Net photosynthetic rate of nickel treated plants was the most affected by applied concentration. Cadmium and nickel concentrations in stems and leaves of black locust families exceeded 100 mg Cd kg(-1) and 1000 mg Ni kg(-1), in both single and multipollution context. On the contrary, accumulation of lead in above ground biomass was highly affected by multipollution treatment. Tf and BCF significantly varied between investigated treatments and families of black locust. Concerning obtained results of heavy metals accumulation and tolerance of black locust families can be concluded that tested families might be a promising tool for phytoextraction purposes, but it takes to be further confirmed in field trials.

  7. Tolerance

    DEFF Research Database (Denmark)

    Tønder, Lars

    Tolerance: A Sensorial Orientation to Politics is an experiment in re-orientation. The book is based on the wager that tolerance exceeds the more prevalent images of self-restraint and repressive benevolence because neither precludes the possibility of a more “active tolerance” motivated...... by the desire to experiment and to become otherwise. The objective is to discuss what gets lost, conceptually as well as politically, when we neglect the subsistence of active tolerance within other practices of tolerance, and to develop a theory of active tolerance in which tolerance's mobilizing character...... is linked to a different set of circumstances than the ones suggested by existing models in contemporary democratic theory. Reorienting the discussion of tolerance, the book raises the question of how to disclose new possibilities within our given context of affect and perception. Once we move away from...

  8. Metal resistance or tolerance? Acidophiles confront high metal loads via both abiotic and biotic mechanisms

    Directory of Open Access Journals (Sweden)

    Mark eDopson


    Full Text Available All metals are toxic at high concentrations and consequently their intracellular concentrations must be regulated. Acidophilic microorganisms have an optimum growth pH < 3 and proliferate in natural and anthropogenic low pH environments. Some acidophiles are involved in the catalysis of sulfide mineral dissolution, resulting in high concentrations of metals in solution. Acidophiles are often described as highly metal resistant via mechanisms such as multiple and/or more efficient active resistance systems than are present in neutrophiles. However, this is not the case for all acidophiles and we contend that their growth in high metal concentrations is partially due to an intrinsic tolerance as a consequence of the environment in which they live. In this perspective, we highlight metal tolerance via complexation of free metals by sulfate ions and passive tolerance to metal influx via an internal positive cytoplasmic transmembrane potential. These tolerance mechanisms have been largely ignored in past studies of acidophile growth in the presence of metals and should be taken into account.

  9. [Research advances in drought resistance and heavy metals tolerance of transgenic plant]. (United States)

    Zhang, Yu-Xiu; Xu, Jin; Wang, Xiao; Chai, Tuan-Yao


    Drought and heavy metals contamination greatly affect plant growth, while the cloning and function analysis of stress-inducible genes provide an effective approach to improve the stress tolerance and yield of crops by genetic engineering. The expression of LEA (late embryogenesis abundant protein) gene could be induced by various stresses such as drought, high salinity, cold, and heavy metals. The study on transgenic plants showed that LEA could increase plant tolerance to water stress, had ion-binding activity, and acted as an antioxidant under abiotic stresses. Aquaporins largely presented in plasma membrane and vacuolar membrane, and played a key role in root water uptake and transportation both at cellular and at whole plant level. The expression of aquaporins was up-regulated in response to drought and salinity, and conferred the water stress tolerance in plant. Cation-efflux transport proteins were involved in the absorption, transportation, and accumulation of heavy metals in plants. All of the proteins mentioned above could have potential applied profits on improving the biological water-saving, drought resistance, and heavy metals tolerance of lawny grass.

  10. Molecular mechanisms of heavy metal tolerance and evolution n invertebrates

    Institute of Scientific and Technical Information of China (English)

    Thierry K.S.Janssens; Dick Roelofs; Nico M.van Straalen


    Following the genomics revolution,our knowledge of the molecular mechanisms underlying defenses against stress has been greatly expanded.Under strong selective pressure many animals may evolve an enhanced stress tolerance.This can be achieved by altering the structure of proteins(through mutations in the coding regions of genes)or by altering the amount of protein(through changes in transcriptional regulation).The latter type of evolution Can be achieved by substitutions in the promoter of the gene of interest(cis-regulatory change)or by altering the structure or anaount of transcriptional regulator proteins (trans-regulatory change).The metallothionein system is one of the best studied stress response systems in the context of heavy metals.Metallothionein expression is assumed to be regulated by metal transcription factor 1(MTF-1);however,up to now the involvement of MTF-1 has only been proven for some vertebrates and Drosophila.Data on invertebrates such as nematodes and earthworms suggest that other mechanisms of metallothionein induction may be present.A detailed study of Cd tolerance was done for a species of soilliving springtail,Orchesella cincta.The metallothionein gene of this species is overexpressed in metal-exposed field populations.Analysis of the metallothionein promoter has demonstrated extensive polymorphisills that have a functional significance,as shown in bioreporter assays.In a study comparing 20 different populations,the frequency of a high-expresser promoter allele Was positively correlated with the concentration of metals in soil,especially Cd.The springtail study shows that cis-regulatory change of genes involved in the cellular stress response may contribute to evolution of metal tolerance.

  11. Re-Evaluation of Reportedly Metal Tolerant Arabidopsis thaliana Accessions (United States)

    Silva-Guzman, Macarena; Addo-Quaye, Charles; Dilkes, Brian P.


    Santa Clara, Limeport, and Berkeley are Arabidopsis thaliana accessions previously identified as diversely metal resistant. Yet these same accessions were determined to be genetically indistinguishable from the metal sensitive Col-0. We robustly tested tolerance for Zn, Ni and Cu, and genetic relatedness by growing these accessions under a range of Ni, Zn and Cu concentrations for three durations in multiple replicates. Neither metal resistance nor variance in growth were detected between them and Col-0. We re-sequenced the genomes of these accessions and all stocks available for each accession. In all cases they were nearly indistinguishable from the standard laboratory accession Col-0. As Santa Clara was allegedly collected from the Jasper Ridge serpentine outcrop in California, USA we investigated the possibility of extant A. thaliana populations adapted to serpentine soils. Botanically vouchered Arabidopsis accessions in the Jepson database were overlaid with soil maps of California. This provided no evidence of A. thaliana collections from serpentine sites in California. Thus, our work demonstrates that the Santa Clara, Berkeley and Limeport accessions are not metal tolerant, not genetically distinct from Col-0, and that there are no known serpentine adapted populations or accessions of A. thaliana. PMID:27467746


    Directory of Open Access Journals (Sweden)

    Mathan Jayaraman


    Full Text Available The influence of Cr6+, Pb2+, Cu2+, Ni2+, Zn2+ and Cd2+ on the development of 24 fungi was investigated for Metal Tolerance Index (MTI at 1mg ml-1 Cr6+, Pb2+, Cu2+, Ni2+, Zn2+ and Cd2+ concentrations and also for Minimum Inhibitory Concentration (MIC. The MIC ranged from 0.5 to 1.5 mg ml-1 depending on the isolate Aspergillus, Fusarium and Penicillium sp. were tested for their metal tolerance index. Out of these Aspergillus flavus (ED4 shows a better tolerance index of 0.80 Cr6+, 0.72 for Pb2+ , 0.63 for Cu2+, 0.58 for Ni2+, 0.46 for Zn2+ and 0.60 Cd2+ for MIC value for the removal of heavy metals from contaminated soil and wastewaters.

  13. Model systems to unravel the molecular mechanisms of heavy metal tolerance in the ericoid mycorrhizal symbiosis. (United States)

    Daghino, Stefania; Martino, Elena; Perotto, Silvia


    Ericoid mycorrhizal plants dominate in harsh environments where nutrient-poor, acidic soil conditions result in a higher availability of potentially toxic metals. Although metal-tolerant plant species and ecotypes are known in the Ericaceae, metal tolerance in these plants has been mainly attributed to their association with ericoid mycorrhizal fungi. The mechanisms underlying plant protection by the fungal symbiont are poorly understood, whereas some insights have been achieved regarding the molecular mechanisms of heavy metal tolerance in the fungal symbiont. This review will briefly introduce the general features of heavy metal tolerance in mycorrhizal fungi and will then focus on the use of "omics" approaches and heterologous expression in model organisms to reveal the molecular bases of fungal response to heavy metals. Functional complementation in Saccharomyces cerevisiae has allowed the identification of several ericoid mycorrhizal fungi genes (i.e., antioxidant enzymes, metal transporters, and DNA damage repair proteins) that may contribute to metal tolerance in a metal-tolerant ericoid Oidiodendron maius isolate. Although a powerful system, the use of the yeast complementation assay to study metal tolerance in mycorrhizal symbioses has limitations. Thus, O. maius has been developed as a model system to study heavy metal tolerance mechanisms in mycorrhizal fungi, thanks to its high metal tolerance, easy handling and in vitro mycorrhization, stable genetic transformation, genomics, transcriptomic and proteomic resources.

  14. Chloroplast targeting of phytochelatin synthase in Arabidopsis: effects on heavy metal tolerance and accumulation. (United States)

    Picault, N; Cazalé, A C; Beyly, A; Cuiné, S; Carrier, P; Luu, D T; Forestier, C; Peltier, G


    The enzymatically synthesized thiol peptide phytochelatin (PC) plays a central role in heavy metal tolerance and detoxification in plants. In response to heavy metal exposure, the constitutively expressed phytochelatin synthase enzyme (PCS) is activated leading to synthesis of PCs in the cytosol. Recent attempts to increase plant metal accumulation and tolerance reported that PCS over-expression in transgenic plants paradoxically induced cadmium hypersensitivity. In the present paper, we investigate the possibility of synthesizing PCs in plastids by over-expressing a plastid targeted phytochelatin synthase (PCS). Plastids represent a relatively important cellular volume and offer the advantage of containing glutathione, the precursor of PC synthesis. Using a constitutive CaMV 35S promoter and a RbcS transit peptide, we successfully addressed AtPCS1 to chloroplasts, significant PCS activity being measured in this compartment in two independent transgenic lines. A substantial increase in the PC content and a decrease in the glutathione pool were observed in response to cadmium exposure, when compared to wild-type plants. While over-expressing AtPCS1 in the cytosol importantly decreased cadmium tolerance, both cadmium tolerance and accumulation of plants expressing plastidial AtPCS1 were not significantly affected compared to wild-type. Interestingly, targeting AtPCS1 to chloroplasts induced a marked sensitivity to arsenic while plants over-expressing AtPCS1 in the cytoplasm were more tolerant to this metalloid. These results are discussed in relation to heavy metal trafficking pathways in higher plants and to the interest of using plastid expression of PCS for biotechnological applications.

  15. Adaptive Engineering of Phytochelatin-based Heavy Metal Tolerance. (United States)

    Cahoon, Rebecca E; Lutke, W Kevin; Cameron, Jeffrey C; Chen, Sixue; Lee, Soon Goo; Rivard, Rebecca S; Rea, Philip A; Jez, Joseph M


    Metabolic engineering approaches are increasingly employed for environmental applications. Because phytochelatins (PC) protect plants from heavy metal toxicity, strategies directed at manipulating the biosynthesis of these peptides hold promise for the remediation of soils and groundwaters contaminated with heavy metals. Directed evolution of Arabidopsis thaliana phytochelatin synthase (AtPCS1) yields mutants that confer levels of cadmium tolerance and accumulation greater than expression of the wild-type enzyme in Saccharomyces cerevisiae, Arabidopsis, or Brassica juncea. Surprisingly, the AtPCS1 mutants that enhance cadmium tolerance and accumulation are catalytically less efficient than wild-type enzyme. Metabolite analyses indicate that transformation with AtPCS1, but not with the mutant variants, decreases the levels of the PC precursors, glutathione and γ-glutamylcysteine, upon exposure to cadmium. Selection of AtPCS1 variants with diminished catalytic activity alleviates depletion of these metabolites, which maintains redox homeostasis while supporting PC synthesis during cadmium exposure. These results emphasize the importance of metabolic context for pathway engineering and broaden the range of tools available for environmental remediation.

  16. Physiological and proteomic changes suggest an important role of cell walls in the high tolerance to metals of Elodea nuttallii. (United States)

    Larras, Floriane; Regier, Nicole; Planchon, Sébastien; Poté, John; Renaut, Jenny; Cosio, Claudia


    Macrophytes bioaccumulate metals, the suggestion being made that they be considered for phytoremediation. However, a thorough understanding of the mechanisms of metal tolerance in these plants is necessary to allow full optimization of this approach. The present study was undertaken to gain insight into Hg and Cd accumulation and their effects in a representative macrophyte, Elodea nuttallii. Exposure to methyl-Hg (23 ng dm(-3)) had no significant effect while inorganic Hg (70 ng dm(-3)) and Cd (281 μg dm(-3)) affected root growth but did not affect shoots growth, photosynthesis, or antioxidant enzymes. Phytochelatins were confirmed as having a role in Cd tolerance in this plant while Hg tolerance seems to rely on different mechanisms. Histology and subcellular distribution revealed a localized increase in lignification, and an increased proportion of metal accumulation in cell wall over time. Proteomics further suggested that E. nuttallii was able to efficiently adapt its energy sources and the structure of its cells during Hg and Cd exposure. Storage in cell walls to protect cellular machinery is certainly predominant at environmental concentrations of metals in this plant resulting in a high tolerance highlighted by the absence of toxicity symptoms in shoots despite the significant accumulation of metals.

  17. Metal tolerance potential of filamentous fungi isolated from soils irrigated with untreated municipal effluent

    Directory of Open Access Journals (Sweden)

    Shazia Akhtar, Muhammad Mahmood-ul-Hassan, Rizwan Ahmad, Vishandas Suthor and Muhammad Yasin


    Full Text Available Considering the importance of filamentous fungi for bioremediation of wastewater and contaminated soils, this study was planned to investigate the metal tolerance potential of indigenous filamentous fungi. Nineteen fungal strains were isolated from soils irrigated with untreated municipal/industrial effluent using dilution technique and 10 prominent isolates were used for metal tolerance. The isolated fungal isolates were screened for metal tolerance index (MTI at I mM cadmium (Cd, nickel (Ni and copper (Cu concentrations and for minimum inhibitory concentration (MIC and metal tolerance by growing on potato dextrose agar plates amended with varying amounts of Cd, Cu and Ni. Seven out of 10 isolated fungi belonged to the genera Aspergillus and three belonged to Curvularia, Acrimonium and Pithyum. The results revealed that the order of tolerance of isolates for metals was Cd > Cu > Ni and Aspergillus sp. were more tolerant than other fungi. Tolerance ranged from 900 – 9218 mg L-1 for Cd, followed by 381 - 1780 mg L-1 for Cu and 293-1580 mg L-1for Ni. The isolated fungi exhibiting great tolerance to metals (Cd, Cu and Ni can be used successfully for bioremediation of metals from contaminated soil and wastewaters.

  18. On the metal tolerance and resilience capacity of Helichrysum italicum G. Don growing on mine soils (United States)

    Maleci, Laura; Tani, Corrado; Bini, Claudio; Wahsha, Mohammad


    Heavy metal accumulation produces significant physiological and biochemical responses in vascular plants. Plants growing on abandoned mine sites are of particular interest, since they are genetically tolerant to high metal concentrations. In this work we examined the effects of heavy metals (HM) on the morphology of Helichrysum italicum growing on mine soils, with the following objectives: to determine the fate of HM within the soil-plant system; to highlight morphological modifications at anatomical and cytological level; to ascertain the plant tolerance to heavy metals, and their resilience capacity. Wild specimens of Helichrysum italicum, with their soil clod, were gathered from sites with different contamination levels by heavy metals (Cd, Cu, Fe, Pb, Zn) in the abandoned Niccioleta mine (Tuscany, Italy). Plants were brought to the botanical laboratory of the University of Florence, and appeared macroscopically not affected by toxic signals (e.g. reduced growth, leaf necrosis) induced by soil HM concentration. Leaves and roots taken at the same growing season were observed by light microscopy (LM) and transmission electron microscopy (TEM). Light microscopy observations show a clear difference in the cell organization of not-contaminated and contaminated samples. In particular, the secreting trichomes, which are responsible for the characteristic flavour of the plant, present a different morphology in the polluted specimens with respect to the not-polluted ones. Indeed, the latter present the typical trichomes of the Asteraceae family, with two lines of cells bearing the secretion accumulated on the apical cuticular space. Trichomes of the polluted plants, instead, present a completely different morphology, with a stalk of 3-4 cells and a large secreting apical cell (i.e. they are capitate hairs). Samples from contaminated sites, moreover, present a palisade parenchyma less organized, and a reduction of leaf thickness proportional to HM concentration. The poor

  19. Heavy metal tolerance (Cr, Ag AND Hg) in bacteria isolated from sewage (United States)

    Lima de Silva, Agostinho A.; de Carvalho, Márcia A. Ribeiro; de Souza, Sérgio A. L; Dias, Patrícia M. Teixeira; da Silva Filho, Renato G.; de Meirelles Saramago, Carmen S.; de Melo Bento, Cleonice A.; Hofer, Ernesto


    Samples of sewage from a university hospital and a chemistry technical school were analysed for the percentage of bacterial tolerance to chromium (Cr), silver (Ag) and mercury (Hg). Additionally, we investigated the effect of these metals on pigmentation and on some enzymatic activities of the metal tolerant strains isolated, as well as antimicrobial resistance in some metal tolerant Enterobacteriaceae strains. Tolerance to Cr was observed mainly in Gram positive bacteria while in the case of Ag and Hg the tolerant bacteria were predominately Gram negative. Hg was the metal for which the percentage of tolerance was significantly higher, especially in samples from the hospital sewage (4.1%). Mercury also had the most discernible effect on color of the colonies. Considering the effect of metals on the respiratory enzymes, one strain of Ag-tolerant Bacillus sp. and one of Hg-tolerant P. aeruginosa were unable to produce oxidase in the presence of Ag and Hg, respectively, while the expression of gelatinase was largely inhibited in various Gram negative strains (66% by Cr). Drug resistance in Hg-tolerant Enterobacteriaceae strains isolated from the university hospital sewage was greater than 80%, with prevalence of multiple resistance, while the Ag-tolerant strains from the same source showed about 34% of resistance, with the predominance of mono-resistance. Our results showed that, despite the ability of metal tolerant strains to survive and grow in the presence of these elements, the interactions with these metals may result in metabolic or phisiological changes in this group of bacteria. PMID:24031994

  20. Heavy metal tolerance (Cr, Ag and Hg in bacteria isolated from sewage

    Directory of Open Access Journals (Sweden)

    Agostinho A. de Lima e Silva


    Full Text Available Samples of sewage from a university hospital and a chemistry technical school were analysed for the percentage of bacterial tolerance to chromium (Cr, silver (Ag and mercury (Hg. Additionally, we investigated the effect of these metals on pigmentation and on some enzymatic activities of the metal tolerant strains isolated, as well as antimicrobial resistance in some metal tolerant Enterobacteriaceae strains. Tolerance to Cr was observed mainly in Gram positive bacteria while in the case of Ag and Hg the tolerant bacteria were predominately Gram negative. Hg was the metal for which the percentage of tolerance was significantly higher, especially in samples from the hospital sewage (4.1%. Mercury also had the most discernible effect on color of the colonies. Considering the effect of metals on the respiratory enzymes, one strain of Ag-tolerantBacillus sp. and one of Hg-tolerant P. aeruginosa were unable to produce oxidase in the presence of Ag and Hg, respectively, while the expression of gelatinase was largely inhibited in various Gram negative strains (66% by Cr. Drug resistance in Hg-tolerant Enterobacteriaceae strains isolated from the university hospital sewage was greater than 80%, with prevalence of multiple resistance, while the Ag-tolerant strains from the same source showed about 34% of resistance, with the predominance of mono-resistance. Our results showed that, despite the ability of metal tolerant strains to survive and grow in the presence of these elements, the interactions with these metals may result in metabolic or phisiological changes in this group of bacteria.

  1. Effect of genomic rearrangement on heavy metal tolerance in the plant-growth-promoting rhizobacterium Azospirillum brasilense Sp245. (United States)

    Shelud'ko, Andrei V; Varshalomidze, Olga E; Petrova, Lilia P; Katsy, Elena I


    A derivative of Azospirillum brasilense Sp245, Sp245.5, which spontaneously lost 85 and 120 MDa replicons upon the formation of a new megaplasmid, has been shown to produce a novel lipopolysaccharide and to lose Calcofluor-binding polysaccharides. As compared to Sp245, the derivative displays notably increased heavy metal tolerance. The phenotypes of Sp245 and Sp245.5 are characterized by the following minimal inhibitory concentrations (MICs) of heavy metals: 0.5 and 0.9 μmol l(-1) of Ag(+), 0.4 and 0.7 mmol l(-1) of Co(2+), 0.9 and 4.7 mmol l(-1) of Cu(2+), and 3.1 and 11.5 mmol l(-1) of Zn(2+), respectively. In Sp245, in the presence of a nonlethal concentration (0.625 μmol l(-1)) of the efflux pump inhibitor carbonyl cyanide m-chlorophenylhydrazone (CCCP), the MIC of cobalt, copper, and zinc drop 1.3- to 1.6-fold, but the low tolerance to silver is unaffected. In Sp245.5, CCCP does not affect cobalt tolerance, suppresses tolerance to copper and silver to the wild-type levels, and causes a 1.4-fold decrease in resistance to zinc. Therefore, significant elevation of heavy metal tolerance in Sp245.5 seems caused by the induction/overexpression of the proton-dependent efflux of certain metal ions. The novel cell surface and other unknown factors could also be responsible for the increased tolerance of A. brasilense Sp245.5 to heavy metals.

  2. Conductivity of graphene affected by metal adatoms (United States)

    Zhang, Peng; Li, Jing-Tian; Meng, Jian-Wei; Jiang, An-Quan; Zhuang, Jun; Ning, Xi-Jing


    It has been a mystery how metal atoms adsorbed on perfect graphene impact the conductivity. We deposited Al, Cu, or Ag atoms onto graphene sheet on SiO2 substrate at room temperature or 573 K by pulsed laser ablation and measured the zero-gate resistance in-situ, showing that the resistance increased suddenly just after each of the deposition pulse and then decayed slowly to an elevated plateau, forming a sequential jagged peaks. Based on the fact that most areas of the graphene sheet are of perfect lattice structure, our calculations via first principles suggest that the resistance peaks result directly from the contribution of metal atoms landed on the perfect regions, and decaying of the peaks corresponds to the clustering process of the metal atoms.

  3. Cultivable endophytic bacteria from heavy metal(loid)-tolerant plants. (United States)

    Román-Ponce, Brenda; Ramos-Garza, Juan; Vásquez-Murrieta, María Soledad; Rivera-Orduña, Flor Nohemí; Chen, Wen Feng; Yan, Jun; Estrada-de Los Santos, Paulina; Wang, En Tao


    To evaluate the interactions among endophytes, plants and heavy metal/arsenic contamination, root endophytic bacteria of Prosopis laevigata (Humb and Bonpl. ex Willd) and Sphaeralcea angustifolia grown in a heavy metal(loid)-contaminated zone in San Luis Potosi, Mexico, were isolated and characterized. Greater abundance and species richness were found in Prosopis than in Sphaeralcea and in the nutrient Pb-Zn-rich hill than in the poor nutrient and As-Cu-rich mine tailing. The 25 species identified among the 60 isolates formed three groups in the correspondence analysis, relating to Prosopis/hill (11 species), Prosopis/mine tailing (4 species) and Sphaeralcea/hill (4 species), with six species ungrouped. Most of the isolates showed high or extremely high resistance to arsenic, such as ≥100 mM for As(V) and ≥20 mM for As(III), in mineral medium. These results demonstrated that the abundance and community composition of root endophytic bacteria were strongly affected by the concentration and type of the heavy metals and metalloids (arsenic), as well as the plant species.

  4. Evaluating the Metal Tolerance Capacity of Microbial Communities Isolated from Alberta Oil Sands Process Water.

    Directory of Open Access Journals (Sweden)

    Mathew L Frankel

    Full Text Available Anthropogenic activities have resulted in the intensified use of water resources. For example, open pit bitumen extraction by Canada's oil sands operations uses an estimated volume of three barrels of water for every barrel of oil produced. The waste tailings-oil sands process water (OSPW-are stored in holding ponds, and present an environmental concern as they are comprised of residual hydrocarbons and metals. Following the hypothesis that endogenous OSPW microbial communities have an enhanced tolerance to heavy metals, we tested the capacity of planktonic and biofilm populations from OSPW to withstand metal ion challenges, using Cupriavidus metallidurans, a known metal-resistant organism, for comparison. The toxicity of the metals toward biofilm and planktonic bacterial populations was determined by measuring the minimum biofilm inhibitory concentrations (MBICs and planktonic minimum inhibitory concentrations (MICs using the MBEC ™ assay. We observed that the OSPW community and C. metallidurans had similar tolerances to 22 different metals. While thiophillic elements (Te, Ag, Cd, Ni were found to be most toxic, the OSPW consortia demonstrated higher tolerance to metals reported in tailings ponds (Al, Fe, Mo, Pb. Metal toxicity correlated with a number of physicochemical characteristics of the metals. Parameters reflecting metal-ligand affinities showed fewer and weaker correlations for the community compared to C. metallidurans, suggesting that the OSPW consortia may have developed tolerance mechanisms toward metals present in their environment.

  5. Molecular Mechanisms and Genetic Basis of Heavy Metal Tolerance/Hyperaccumulation in Plants

    Institute of Scientific and Technical Information of China (English)

    Xiao-E YANG; Xiao-Fen JIN; Ying FENG; Ejazul ISLAM


    Phytoremediation has gained increased attention as a cost-effective method for the remediation of heavy metal-contaminated sites. Because some plants possess a range of potential mechanisms that may be involved in the detoxification of heavy metals, they manage to survive under metal stresses. High tolerance to heavy metal toxicity could rely either on reduced uptake or increased plant internal sequestration,which is manifested by an interaction between a genotype and its environment. The growing application of molecular genetic technologies has led to increased understanding of mechanisms of heavy metal tolerance/accumulation in plants and, subsequently, many transgenic plants with increased heavy metal resistance,as well as increased uptake of heavy metals, have been developed for the purpose of phytoremediation. In the present review, our major objective is to concisely evaluate the progress made so far in understanding the molecular/cellular mechanisms and genetic basis that control the uptake and detoxification of metals by plants.

  6. Sperm Affects Head Sensory Neuron in Temperature Tolerance of Caenorhabditis elegans

    Directory of Open Access Journals (Sweden)

    Satoru Sonoda


    Full Text Available Tolerance to environmental temperature change is essential for the survival and proliferation of animals. The process is controlled by various body tissues, but the orchestration of activity within the tissue network has not been elucidated in detail. Here, we show that sperm affects the activity of temperature-sensing neurons (ASJ that control cold tolerance in Caenorhabditis elegans. Genetic impairment of sperm caused abnormal cold tolerance, which was unexpectedly restored by impairment of temperature signaling in ASJ neurons. Calcium imaging revealed that ASJ neuronal activity in response to temperature was decreased in sperm mutant gsp-4 with impaired protein phosphatase 1 and rescued by expressing gsp-4 in sperm. Genetic analysis revealed a feedback network in which ASJ neuronal activity regulates the intestine through insulin and a steroid hormone, which then affects sperm and, in turn, controls ASJ neuronal activity. Thus, we propose that feedback between sperm and a sensory neuron mediating temperature tolerance.

  7. Endomorphins and β-Endorphin Do Not Affect Heart Tolerance to the Pathogenic Effect of Reperfusion. (United States)

    Mukhomedzyanov, A V; Maslov, L N; Tsibulnikov, S Yu; Pei, J M


    Selective agonists of μ1- and μ2-opioid receptors endomorphin-2 and endomorphin-1 injected intravenously in a dose of 4500 nmol/kg in 5 min before coronary blood flow resumption had no effect on cardiac reperfusion damage. Consequently, μ1- and μ2-opioid receptors are not involved in the regulation of heart tolerance to reperfusion injury. Nonselective opioid receptor agonist β-endorphin (100 nmol/kg) also did not affect heart tolerance to the pathogenic effect of reperfusion.

  8. Constitutional tolerance to heavy metals of a fiber crop, ramie (Boehmeria nivea), and its potential usage

    Energy Technology Data Exchange (ETDEWEB)

    Yang, B.; Zhou, M.; Shu, W.S.; Lan, C.Y. [State Key Laboratory of Biocontrol, and School of Life Sciences, Sun Yat-sen (Zhongshan) University, Guangzhou 510275 (China); Ye, Z.H., E-mail: [State Key Laboratory of Biocontrol, and School of Life Sciences, Sun Yat-sen (Zhongshan) University, Guangzhou 510275 (China); Qiu, R.L. [Guangdong Provincial Key Lab of Environmental Pollution Control and Remediation Technology, and School of Sciences and Engineering, Sun Yat-sen (Zhongshan) University, Guangzhou 510275 (China); Jie, Y.C. [Institute of Bast Fiber Crops, Chinese Academy of Agricultural Sciences, Changsha 410205 (China); Cui, G.X. [Ramie Research Institute, Hunan Agricultural University, Changsha 410128 (China); Wong, M.H., E-mail: [Croucher Institute for Environmental Sciences, and Department of Biology, Hong Kong Baptist University, Kowloon Tong (Hong Kong)


    It is observed that ramie (Boehmeria nivea), an economic fiber crop, can establish and colonize metal-contaminated sites in China. Metal tolerance and accumulation by ramie originating from 13 metal-contaminated and 4 'clean' sites in China were compared under field and hydroponic conditions. All selected populations and germplasms displayed good growth performance under diverse metal-contaminated habitats; while growth responses, metal accumulation and tolerance were similar among the 8 populations and 2 germplasms when exposed to solutions containing elevated As, Cd, Pb, or Zn in the laboratory. These revealed that ramie possesses a certain degree of constitutional metal tolerance. To our knowledge, this is the first report of constitutional metal tolerance possessed by a fiber crop. Ramie can be considered as a good candidate for both fiber production and phytoremediation of sites contaminated by multi-metals, as it accumulates relative low metal concentrations, but possesses both high biomass and high economic value. - Ramie possesses economic and environmental values in phytoremediation

  9. Electronic hybridisation implications for the damage-tolerance of thin film metallic glasses (United States)

    Schnabel, Volker; Jaya, B. Nagamani; Köhler, Mathias; Music, Denis; Kirchlechner, Christoph; Dehm, Gerhard; Raabe, Dierk; Schneider, Jochen M.


    A paramount challenge in materials science is to design damage-tolerant glasses. Poisson’s ratio is commonly used as a criterion to gauge the brittle-ductile transition in glasses. However, our data, as well as results in the literature, are in conflict with the concept of Poisson’s ratio serving as a universal parameter for fracture energy. Here, we identify the electronic structure fingerprint associated with damage tolerance in thin film metallic glasses. Our correlative theoretical and experimental data reveal that the fraction of bonds stemming from hybridised states compared to the overall bonding can be associated with damage tolerance in thin film metallic glasses. PMID:27819318

  10. Engineered Bacterial Metal-binding Proteins for Nanoscale Self-assembly and heavy Metal Tolerance (United States)

    Hall Sedlak, Ruth Amanda

    Implementing biological principles in material synthesis and assembly is one way to expand our abilities to efficiently assemble nanoscale materials and devices. Specifically, recent advances in identifying peptides that bind inorganic materials with high affinity and specificity has spurred investigation of protein models for nanoscale inorganic assembly. This dissertation presents the results of my studies of several E. coli proteins engineered to bind inorganic materials through simple peptide motifs. I demonstrate that these proteins modulate the self-assembly of DNA-based nanostructures and can introduce heavy metal tolerance into metal-sensitive bacteria. Chapter 2 explores use of the engineered F plasmid DNA relaxase/helicase TraI for the self-assembly of complex DNA-protein-gold nanostructures. The full-length protein is engineered with a gold binding motif at an internal permissive site (TraI369GBP1-7x), while a truncated version of TraI is engineered with the same gold binding motif at the C-terminus (TraI361GBP1-7x). Both constructs bind gold nanoparticles while maintaining their DNA binding activity, and transmission electron microscopy reveals TraI369GBP1-7x utilizes its non-specific DNA binding activity to decorate single-stranded and double-stranded DNA with gold nanoparticles. The self assembly principles demonstrated in this work will be fundamental to constructing higher ordered hybrid nanostructures through DNA-protein-nanoparticle interactions. Chapter 3 studies the effects of expressing inorganic binding peptides within cells. I identified a silver binding peptide that, when fused to the periplasmic maltose binding protein, protects E. coli from silver toxicity in batch culture and reduces silver ions to silver nanoparticles within the bacterial periplasm. Engineered metal-ion tolerant microorganisms such as this E. coli could potentially be used in applications ranging from remediation to interrogation of biomolecule-metal interactions in vivo

  11. Arbuscular Mycorrhizal Fungi Can Benefit Heavy Metal Tolerance and Phytoremediation (United States)

    Forgy, David


    Sites contaminated by heavy metals, such as industrial waste sites, create unwelcoming environments for plant growth. Heavy metals can have a wide range of toxic effects such as replacing essential elements or disrupting enzyme function. While some heavy metals are essential to plant nutrition at low concentrations, high concentrations of any…

  12. Battlefield Acquired Immunogenicity to Metals Affects Orthopaedic Implant Outcome (United States)


    Award Number: W81XWH-10-2-0138 TITLE: "Battlefield-Acquired Immunogenicity to Metals Affects Orthopaedic Implant Outcome." PRINCIPAL...Orthopaedic Implant Outcome." 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Nadim James Hallab, PhD 5d. PROJECT NUMBER 5e. TASK NUMBER 5f...battlefield injuries resulting in increased exposure to metal may sensitize individuals and lead to excessive immune responses to orthopedic implants

  13. Tolerance

    NARCIS (Netherlands)

    Doorn, van M.


    Tolerance entails acceptance of the very things one disagrees with, disapproves of or dislikes. Tolerance can be seen as ‘a flawed virtue’ (Schuyt, 2001), because it concerns acceptance of the differences between others and ourselves we would rather fight, ignore or overcome. Although tolerance carr

  14. Phenol degradation by halophilic fungal isolate JS4 and evaluation of its tolerance of heavy metals. (United States)

    Jiang, Yu; Shang, Yu; Yang, Kai; Wang, Hongyu


    Phenol is one of the most common pollutants in many kinds of industrial wastewater, some of which are in high salinity, resulting in more difficulties of biodegradation. In this work, a halophilic strain capable of utilizing phenol as sole source of carbon and energy in both hypersaline and no-salt media was isolated and identified as genus Debaryomyces. The optimization of environmental parameters including phenol concentration, pH, dissolved oxygen as well as salinity was carried out and tolerance of heavy metals by the strain was evaluated. The strain Debaryomyces sp. was able to grow in culture when initial phenol concentration, pH, agitation and salinity were at wide ranges (0-1200 mg L(-1), 4.0-10.0, 50-200 rpm, 0 %-15 %, respectively). High removal efficiency was hardly affected in the presence of 5 mM of Zn (II) and Mn (II). Under optimal conditions (pH 6.0, 200 rpm, 1 % of salinity without heavy metals), 500 mg L(-1) of phenol could be completely degraded within 32 h. The high removal efficiency of phenol by the strain with significant variations of process parameters might contribute to the bioremediation of phenol-polluted environments under hypersaline or no-salt conditions.

  15. Caddisflies as biomonitors identifying thresholds of toxic metal bioavailability that affect the stream benthos. (United States)

    Rainbow, Philip S; Hildrew, Alan G; Smith, Brian D; Geatches, Tim; Luoma, Samuel N


    It has been proposed that bioaccumulated concentrations of toxic metals in tolerant biomonitors be used as indicators of metal bioavailability that could be calibrated against the ecological response to metals of sensitive biotic assemblages. Our hypothesis was that metal concentrations in caddisfly larvae Hydropsyche siltalai and Plectrocnemia conspersa, as tolerant biomonitors, indicate metal bioavailability in contaminated streams, and can be calibrated against metal-specific ecological responses of mayflies. Bioaccumulated concentrations of Cu, As, Zn and Pb in H. siltalai from SW English streams were related to the mayfly assemblage. Mayflies were always sparse where bioavailabilities were high and were abundant and diverse where bioavailabilities of all metals were low, a pattern particularly evident when the combined abundance of heptageniid and ephemerellid mayflies was the response variable. The results offer promise that bioaccumulated concentrations of metals in tolerant biomonitors can be used to diagnose ecological impacts on stream benthos from metal stressors.

  16. Influence of the soil Ca on the tolerance of Festuca rubra populations against toxic metals

    Energy Technology Data Exchange (ETDEWEB)

    Karataglis, S.S.


    Festuca rubra populations from toxic or non-toxic areas were studied. Their tolerance against the soil content in toxic metals and in combination with the Ca content was also correlated. It was demonstrated that the Festuca rubra populations developed in an environment with high concentrations of toxic metals and with high concentrations of Ca at the same time, showed very little or almost no tolerance against these metals. On the contrary, populations from other mines with normal Ca concentrations in their soil indicated increased tolerance against the toxic metals found in it. This behaviour expressed by the Festuca rubra populations of the Ecton mine is probably due to the high Ca concentration found in the soil in the form of CaCO/sub 2/. CaCO/sub 3/ along with the heavy metals has the ability to form undissolved or not easily dissolved carbonate salts. As a result there are no free ions of toxic metals in the immediate environment of the root and consequently the plants cannot be selected against these metals.

  17. Tolerance of Chrysantemum maximum to heavy metals: The potential for its use in the revegetation of tailings heaps

    Institute of Scientific and Technical Information of China (English)

    Ma.del Carmen A; González-Chávez; Rogelio Carrillo-González


    To find if ornamental plants are applicable to the remediation of metal-polluted areas,the tolerance of chrysanthemum plants (Chysanthemum maximum) var.Shasta to different metals under hydroponic conditions was studied.Their responses as influenced by the mycorrhizal fungus Glomus mosseae (Nicol.& Gerd.) Gerdemann & Trappe BEG25 on substrates containing mine residues were also investigated.Our results showed that chrysanthemum is a metal-tolerant plant under hydroponic conditions,plants behaving as Pb-excluders,whereas Cd,Cu and Ni were accumulated in roots.Low accumulation in flowers was observed for Cd and Cu but it was concentration-dependent.Ni and Pb were not translocated to flowers.Shoot biomass was not significantly affected by the different rates of mine residue addition for both mycorrhizal and non-mycorrhizal plants.Mycorrhizal plants accumulated less Pb and Cu in both shoots and roots than non-mycorrhizal plants.Chysanthemum could be a prospective plant for revegetation of tailings and the use of inoculation may decrease plant metal accumulation in polluted soils.

  18. Escitalopram tolerability as mono- versus augmentative therapy in patients with affective disorders: a naturalistic study

    Directory of Open Access Journals (Sweden)

    Dell'Osso B


    Full Text Available Bernardo Dell’Osso, Chiara Arici, Cristina Dobrea, Giulia Camuri, Beatrice Benatti, A Carlo AltamuraUniversity of Milan, Department of Psychiatry, Fondazione IRCSS Ca’ Granda, Ospedale Maggiore Policlinico, Milano, ItalyBackground: Escitalopram is a selective serotonin reuptake inhibitor, widely used in the treatment of affective disorders. The purpose of this study was to examine its safety and tolerability, as mono- versus augmentative therapy, in a group of patients with affective disorders.Materials and methods: The sample consisted of 131 patients suffering from different affective disorders, including major depressive disorder, bipolar disorder, and generalized anxiety disorder, who received escitalopram for at least 4 weeks. Data were analyzed on the basis of mono- versus augmentative therapy, as well as age, gender, mean daily dosage, and patterns of combination therapy.Results: Sixty-seven (51.1% patients were treated with monotherapy (mean dose of 11.76 mg/day and 64 (48.9% with augmentative escitalopram (mean dose of 12.81 mg/day. The mean duration of escitalopram treatment was 14 months. The most frequently combined compounds were: other antidepressants (36.5%, mood stabilizers (33.4%, and atypical antipsychotics (30.1%. Side effects were reported in 5.3% of the total sample and the most common were insomnia (2.3%, nausea (2.3%, and dizziness (0.8%. No significant difference, in terms of tolerability, in mono- versus augmentative therapy groups was found. In addition, neither age nor gender was significantly correlated with a greater presence of side effects. Finally, no significant correlation between dosage and side effects was observed.Conclusion: Over a 14-month observation period, escitalopram, either as monotherapy or an augmentative treatment, was found to be well tolerated in a large sample of patients with affective disorders, with an overall low rate of side effects.Keywords: affective disorders, escitalopram

  19. Gomphrena claussenii, the first South American metallophyte species with indicator-like Zn and Cd accumulation and extreme metal tolerance

    Directory of Open Access Journals (Sweden)

    Mina eT. Villafort Carvalho


    Full Text Available Plant species with the capacity to tolerate heavy metals are potentially useful for phytoremediation since they have adapted to survive and reproduce under toxic conditions and to accumulate high metal concentrations. Gomphrena claussenii Moq., a South-American species belonging to the Amaranthaceae, is found at a zinc (Zn mining area in the state of Minas Gerais, Brazil. Through soil and hydroponic experiments, the metal tolerance and accumulation capacities of G. claussenii were assessed and the effects on physiological characteristics were compared with a closely-related non-tolerant species, Gomphrena elegans Mart. Gomphrena. claussenii plants grown in soil sampled at the Zn smelting area accumulated up to 5318 µg g-1 of Zn and 287 µg g-1 of Cd in shoot dry biomass after 30 days of exposure. Plants were grown in hydroponics containing up to 3000 µM of Zn and 100 µM of Cd for G. claussenii and 100 µM of Zn and 5 µM of Cd for G. elegans. Gomphrena claussenii proved to be an extremely tolerant species to both Zn and Cd, showing only slight metal toxicity symptoms at the highest treatment levels, without significant decrease in biomass and no effects on root growth, whereas the non-tolerant species G. elegans showed significant toxicity effects at the highest exposure levels. Both species accumulated more Zn and Cd in roots than in shoots. In G. elegans over 90% of the Cd remained in the roots, but G. claussenii showed a root:shoot concentration ratio of around 2, with shoots reaching 0.93 % Zn and 0.13 % Cd on dry matter base. In G. claussenii shoots, the concentrations of other minerals, such as Fe and Mn, were only affected by the highest Zn treatment while in G. elegans the Fe and Mn concentrations in shoots decreased drastically at both Zn and Cd treatments. Taking together, these results indicate that G. claussenii is a novel metallophyte, extremely tolerant of high Zn and Cd exposure and an interesting species for further

  20. Mechanisms of metal tolerance in marine macroalgae, with emphasis on copper tolerance in Chlorophyta and Rhodophyta. (United States)

    Moenne, Alejandra; González, Alberto; Sáez, Claudio A


    Green and red macroalgae are closely related organisms, and with terrestrial plants, and constitute the base of marine food webs in coastal ecosystems. Green and red seaweeds, as all living organisms, require essential metals, such as copper, iron, zinc, which can act as co-factors for several proteins and enzymes; however, these metals in excess can induce stress and impair cell viability. Most important negative effects of metal excess are related to the induction of an oxidative stress condition, characterized by the over-accumulation of Reactive Oxygen Species (ROS). In this respect, copper, abundant in wastewaters disposed to coastal environments from domestic and industrial activities, has been one of the most studied metals. Different investigations have provided evidence that green and red macroalgae display several defenses against copper excess to prevent, or at least reduce, stress and damage, among which are cellular exclusion mechanisms, synthesis of metal-chelating compounds, and the activation of the antioxidant system. Most important defense mechanisms identified in green and red seaweed involve: metal-binding to cell wall and epibionts; syntheses of metallothioneins and phytochelatins that accumulate in the cytoplasm; and the increase in the activity of antioxidant enzymes such as superoxide dismutase, ascorbate peroxidase, glutathione peroxidase and catalase, and greater production of antioxidant metabolites as glutathione and ascorbate in organelles and the cytoplasm. In this review, we go through historical records, latest advances, and pending tasks aiming to expand our current knowledge on defense mechanisms to copper excess in green and red macroalgae, with emphasis on biochemical and molecular aspects.

  1. Heavy Metal Tolerance in Plants: Role of Transcriptomics, Proteomics, Metabolomics, and Ionomics. (United States)

    Singh, Samiksha; Parihar, Parul; Singh, Rachana; Singh, Vijay P; Prasad, Sheo M


    Heavy metal contamination of soil and water causing toxicity/stress has become one important constraint to crop productivity and quality. This situation has further worsened by the increasing population growth and inherent food demand. It has been reported in several studies that counterbalancing toxicity due to heavy metal requires complex mechanisms at molecular, biochemical, physiological, cellular, tissue, and whole plant level, which might manifest in terms of improved crop productivity. Recent advances in various disciplines of biological sciences such as metabolomics, transcriptomics, proteomics, etc., have assisted in the characterization of metabolites, transcription factors, and stress-inducible proteins involved in heavy metal tolerance, which in turn can be utilized for generating heavy metal-tolerant crops. This review summarizes various tolerance strategies of plants under heavy metal toxicity covering the role of metabolites (metabolomics), trace elements (ionomics), transcription factors (transcriptomics), various stress-inducible proteins (proteomics) as well as the role of plant hormones. We also provide a glance of some strategies adopted by metal-accumulating plants, also known as "metallophytes."

  2. Prospecting metal-tolerant rhizobia for phytoremediation of mining soils from Morocco using Anthyllis vulneraria L. (United States)

    El Aafi, N; Saidi, N; Maltouf, A Filali; Perez-Palacios, P; Dary, M; Brhada, F; Pajuelo, E


    The aim of this work was using the legume plant Anthyllis vulneraria L. (ecotype metallicolous) as a trap plant, in order to isolate metal-tolerant rhizobial strains from metal-contaminated soils from Morocco, with pollution indexes spanning three orders of magnitude. As bioindicator, soil bacterial density was inversely correlated to the pollution index. Forty-three bulk soil bacteria and sixty two bacteria from nodules were isolated. The resistance of bacteria from nodules to heavy metals was four to ten times higher than that of bulk soil bacteria, reaching high maximum tolerable concentrations for Cd (2 mM), Cu (2 mM), Pb (7 mM), and Zn (3 mM). Besides, some strains show multiple metal-tolerant abilities and great metal biosorption onto the bacterial surface. Amplification and restriction analysis of ribosomal 16S rDNA (ARDRA) and 16S ribosomal DNA (rDNA) sequencing were used to assess biodiversity and phylogenetic position among bacteria present in nodules. Our results suggest that a great diversity of non-rhizobial bacteria (alpha- and gamma-proteobacteria) colonize nodules of Anthyllis plants in contaminated soils. Taking together, our results evidence that, in polluted soils, rhizobia can be displaced by non-rhizobial (and hence, non-fixing) strains from nodules. Thus, the selection of metal-resistant rhizobia is a key step for using A. vulneraria symbioses for in situ phytoremediation.

  3. 77 FR 50576 - Fatigue Tolerance Evaluation of Metallic Structures; OMB Approval of Information Collection (United States)


    ... Federal Aviation Administration 14 CFR Part 29 RIN 2120-AJ51 Fatigue Tolerance Evaluation of Metallic Structures; OMB Approval of Information Collection AGENCY: Federal Aviation Administration, DOT. ACTION: Final rule; OMB approval of information collection. SUMMARY: This document notifies the public of...

  4. Metal (Pb, Zn and Cu) uptake and tolerance by mangroves in relation to root anatomy and lignification/suberization. (United States)

    Cheng, Hao; Jiang, Zhao-Yu; Liu, Yong; Ye, Zhi-Hong; Wu, Mei-Lin; Sun, Cui-Ci; Sun, Fu-Lin; Fei, Jiao; Wang, You-Shao


    Metal pollution has been widely reported in mangrove wetlands; however, the mechanisms involved in metal detoxification by mangroves are still poorly understood. This study aimed to investigate the possible function of root anatomy and lignification/suberization on metal uptake and tolerance in seedlings of six species of mangroves. The results revealed that the three rhizophoraceous species (Bruguiera gymnorrhiza (L.) Poir, Kandelia obovata Sheue, Liu & Yong and Rhizophora stylosa Griff) consistently exhibited higher metal tolerances than the three pioneer species (Aegiceras corniculatum (Linn.) Blanco, Acanthus ilicifolius L. and Avicennia marina (Forsk.) Viern.). Moreover, metal-tolerant species often exhibited a thick exodermis with high lignification and suberization. The tolerance indices of the mangroves were found to be positively correlated with the amounts of lignin and suberin deposition within the exodermal cell walls. The observed metal uptake by the excised roots further illustrated that a lignified/suberized exodermis directly delayed the entry of metals into the roots, and thereby contributed to a higher tolerance to heavy metals. In summary, the present study proposes a barrier property of the lignified/suberized exodermis in dealing with the stresses of heavy metals, such that the mangroves which possessed more extensive lignification/suberization within the exodermis appeared to exhibit higher metal tolerance.

  5. Heavy metal tolerance in the psychrotolerant Cryptococcus sp. isolated from deep-sea sediments of the Central Indian Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Singh, P.; Raghukumar, C.; Parvatkar, R.R.; Mascarenhas-Pereira, M.B.L.

    dismutase as a defensive mechanism (Abe et al., 2001). The greater capacity of deep-sea isolates towards metal tolerance abilities may be attributed to their ability to survive under extreme conditions by expression of genes involved in combating... these stress mechanism (Abe and Minegishi, 2008; Singh et al., 2012). Since the exposure to heavy metals also impose similar stress conditions in microorganisms, deep-sea microbes for the metal tolerance studies may prove highly effective for bioremediation...

  6. Fractionation of Heavy Metals in Soils as Affected by Soil Types and Metal Load Quantity

    Institute of Scientific and Technical Information of China (English)


    Two series of soil subsamples, by spiking copper (Cu), lead (Pb), zinc (Zn) and cadmium (Cd) in anorthogonal design, were prepared using red soil and brown soil, respectively. The results indicated that heavymetal fractions in these soil subsamples depended not only on soil types, but also on metal loading quantityas well as on interactions among metals in soil. Lead and Cu in red soil appeared mostly in weakly specificallyadsorbed (WSA), Fe and Mn oxides bound (OX), and residual (RES) fractions. Zinc existed in all fractionsexcept organic bound one, and Cd was major in water soluble plus exchangeable (SE) one. Different fromthe results of red soil, Pb and Cu was present in brown soil in all fractions except organic one, but over 75%of Zn and 90% of Cd existed only in SE fraction. Meanwhile, SE fraction for any metal in red soil was lowerthan that in brown soil and WSA and OX fractions were higher. It is in agreement with low cation exchangecapacity and large amounts of metal oxides included in red soil. Metal fractions in soil, especially for watersoluble plus exchangeable one, were obviously influenced by other coexisting metals. The SE fraction ofheavy metals increased with increasing loading amounts of metals in red soil but not obviously in brown soil,which suggest that metal availability be easily affected by their total amounts spiked in red soil. In addition,more metals in red soil were extracted with 0.20 mol L-1 NH4Cl (pH 5.40) than that with 1.0 mol L-1Mg(NO3)2 (pH 7.0), but the reverse happened in brown soil, implicating significantly different mechanismsof metal desorption from red soil and brown soil.

  7. The effects of an anxiety sensitivity intervention on anxiety, depression, and worry: mediation through affect tolerances. (United States)

    Norr, Aaron M; Allan, Nicholas P; Macatee, Richard J; Keough, Meghan E; Schmidt, Norman B


    Recently there has been increased interest in emotional and physical tolerance risk factors for mood and anxiety disorders. Three tolerance risk factors that have been shown to be related are anxiety sensitivity (AS), distress tolerance (DT), and discomfort intolerance (DI). Although previous research has demonstrated these constructs are malleable, no research has investigated the effects of an AS intervention on DT or DI. Further, no studies have investigated whether changes in DT or DI play a role in mood and anxiety symptom amelioration due to an AS intervention. Participants (N = 104), who were selected for elevated levels of AS, completed a single-session computer-assisted AS intervention or a control intervention and follow-up assessments at 1-week and 1-month post intervention. Results revealed that the intervention reduced AS and increased DT, but did not affect DI at the 1-week follow-up. Mediation analyses revealed that changes in AS and DT both mediated changes in symptoms (depression, anxiety, worry) due to the intervention at 1-month follow-up, however, when AS and DT were considered in the same model only the effect via AS remained significant. These results have important implications for the nature of the relationships between AS, DT, and DI as well as the specific mechanistic pathways through which an AS intervention ameliorates symptoms.

  8. Defect-tolerant single-electron charging at room temperature in metal nanoparticle decorated biopolymers

    Energy Technology Data Exchange (ETDEWEB)

    Berven, C.A.; Clarke, L.; Wybourne, M.N. [Dartmouth Coll., Hanover, NH (United States). Dept. of Physics and Astronomy; Mooster, J.L.; Hutchison, J.E. [Oregon Univ., Eugene, OR (United States). Dept. of Chemistry


    Gold nanoparticles assembled on a biopolymer template between metal electrodes on an insulating substrate are shown to exhibit unambiguous single electron charging effects that are found to depend on the nanoparticle properties and the geometrical contraints imposed by the biopolymer. The results support the idea of using nanoparticles in conjunction with biomolecular organization to produce nanoscale systems with defect-tolerant current-voltage behavior. (orig.)

  9. Study of Metal Resistance Potential of the Cd, Cr Tolerant Alligator Weed

    Directory of Open Access Journals (Sweden)

    Suparna Pal


    Full Text Available Background – Environmental deterioration due to heavy metal pollution is a major global concern for its immense importance in the ecosystem. Indiscriminate use of heavy metals for rapid urbanization and industrial exploration is a pressing threat to human health. Among this Cd and Cr contamination is most dangerous as these metals directly enter into the food chain due to their higher solubility and mobility. Identification of a metal tolerant native plant species would be helpful to decontaminate Cd and Cr polluted land. In our previous study, field investigations were conducted to evaluate the tolerance potential of Alligator weed to Cd and Cr.Alligator weed [Alternanthera philoxeroides (Mart. Griseb ],is the most widely distributed perennial stoloniferous herb in these contaminated areas in and around Kolkata. Purpose of the study – To establish metal tolerant capacity of the species , different biochemical parameters assessing its metal accumulation capacity and reflecting its detoxification mechanism were studied. For these purpose, the same plant collected from the highest metal contaminated area was grown under laboratory condition with external application of various concentration of Cd and Cr individually and synergistically (0.5, 0.8, 1.0, 1.2, 1.5, 1.8 mM. To estimate the hazardous effects of Cd and Cr on this weed, membrane damage was quantified in form of lipid peroxidation i.e MDA production. The metal uptake and accumulation potential was estimated by measuring the Cd and Cr concentration in root and shoot. Some soil parameters such as Orgnaic Carbon, Cation exchange capacity were also studied to explain the bio availability of metals. Various biochemical parameters such as free proline content, non protein- thiol content and zymogram analysis of antioxidative isozymes (such as, Guiacol peroxidase, superoxide dismutase, glutathione reductase and ascorbate peroxidase were studied to assess its metal resistant capacity. Result

  10. Ceylon cinnamon does not affect postprandial plasma glucose or insulin in subjects with impaired glucose tolerance. (United States)

    Wickenberg, Jennie; Lindstedt, Sandra; Berntorp, Kerstin; Nilsson, Jan; Hlebowicz, Joanna


    Previous studies on healthy subjects have shown that the intake of 6 g Cinnamomum cassia reduces postprandial glucose and that the intake of 3 g C. cassia reduces insulin response, without affecting postprandial glucose concentrations. Coumarin, which may damage the liver, is present in C. cassia, but not in Cinnamomum zeylanicum. The aim of the present study was to study the effect of C. zeylanicum on postprandial concentrations of plasma glucose, insulin, glycaemic index (GI) and insulinaemic index (GII) in subjects with impaired glucose tolerance (IGT). A total of ten subjects with IGT were assessed in a crossover trial. A standard 75 g oral glucose tolerance test (OGTT) was administered together with placebo or C. zeylanicum capsules. Finger-prick capillary blood samples were taken for glucose measurements and venous blood for insulin measurements, before and at 15, 30, 45, 60, 90, 120, 150 and 180 min after the start of the OGTT. The ingestion of 6 g C. zeylanicum had no significant effect on glucose level, insulin response, GI or GII. Ingestion of C. zeylanicum does not affect postprandial plasma glucose or insulin levels in human subjects. The Federal Institute for Risk Assessment in Europe has suggested the replacement of C. cassia by C. zeylanicum or the use of aqueous extracts of C. cassia to lower coumarin exposure. However, the positive effects seen with C. cassia in subjects with poor glycaemic control would then be lost.

  11. Dark septate endophyte (DSE) fungi isolated from metal polluted soils: their taxonomic position, tolerance, and accumulation of heavy metals in vitro. (United States)

    Zhang, Yujie; Zhang, Yan; Liu, Maojun; Shi, Xiaodong; Zhao, Zhiwei


    To understand the possible role of the plant root associated fungi on metal tolerance, their role in the uptake of heavy metals and the potential transfer of these metal ions to the plant, three strains of dark septate endophytic (DSE) fungi were isolated from a waste smelter site in southwest China, and one strain was isolated from a non-contaminated site. According to molecular phylogenetic analysis of the ITS 1-5.8S rDNA-ITS 2 gene regions and morphological characteristics, one is identified as Exophiala pisciphila, and the other three are non-sporulating fungi under the experiment condition with the nearest phylogenetic affinities to the Thysanorea papuana strain EU041814. Tolerance and accumulation abilities of the three DSE strains for metals were investigated in liquid culture. Minimum inhibitory concentrations (MIC) of Pb, Zn, and Cd were determined. It was demonstrated that the tolerance of the DSE strains varied between metal species and strains. The E. pisciphila strain is able to accumulate lead and cadmium over 20% and 5% of dry weight of biomass, respectively. Partial of the sequestrated metals can be washed with CaCh. Morphological and enzyme activity changes taking place in the presence of excessive Pb, Cd, and/or Zn also indicate that the mechanism of heavy metal tolerance and accumulation of the DSE strains would be a complex process. The findings indicated promising tolerance and accumulation of the DSE strains with potential values in metal cycling and restoration of soil and water system.

  12. Galápagos mockingbirds tolerate introduced parasites that affect Darwin's finches. (United States)

    Knutie, Sarah A; Owen, Jeb P; McNew, Sabrina M; Bartlow, Andrew W; Arriero, Elena; Herman, Jordan M; DiBlasi, Emily; Thompson, Michael; Koop, Jennifer A H; Clayton, Dale H


    Introduced parasites threaten native host species that lack effective defenses. Such parasites increase the risk of extinction, particularly in small host populations like those on islands. If some host species are tolerant to introduced parasites, this could amplify the risk of the parasite to vulnerable host species. Recently, the introduced parasitic nest fly Philornis downsi has been implicated in the decline of Darwin's finch populations in the Galápagos Islands. In some years, 100% of finch nests fail due to P. downsi; however, other common host species nesting near Darwin's finches, such as the endemic Galápagos mockingbird (Mimus parvulus), appear to be less affected by P. downsi. We compared effects of P. downsi on mockingbirds and medium ground finches (Geospiza fortis) on Santa Cruz Island in the Galápagos. We experimentally manipulated the abundance of P. downsi in nests of mockingbirds and finches to measure the direct effect of the parasite on the reproductive success of each species of host. We also compared immunological and behavioral responses by each species of host to the fly. Although nests of the two host species had similar parasite densities, flies decreased the fitness of finches but not mockingbirds. Neither host species had a significant antibody-mediated immune response to P. downsi. Moreover, finches showed no significant increase in begging, parental provisioning, or plasma glucose levels in response to the flies. In contrast, parasitized mockingbird nestlings begged more than nonparasitized mockingbird nestlings. Greater begging was correlated with increased parental provisioning behavior, which appeared to compensate for parasite damage. The results of our study suggest that finches are negatively affected by P. downsi because they do not have such behavioral mechanisms for energy compensation. In contrast, mockingbirds are capable of compensation, making them tolerant hosts, and a possible indirect threat to Darwin's finches.

  13. Metal toxicity differently affects the Iris pseudacorus-arbuscular mycorrhiza fungi symbiosis in terrestrial and semi-aquatic habitats. (United States)

    Wężowicz, K; Turnau, K; Anielska, T; Zhebrak, I; Gołuszka, K; Błaszkowski, J; Rozpądek, P


    Phytoremediation offers an environmental friendly alternative to conventional cleanup techniques. In this study, mycorrhizal fungi isolated from the roots of Mentha longifolia grown in the basin of the Centuria River (S Poland) were used. Iris pseudacorus was grown in substratum from an industrial waste, enriched in Pb, Fe, Zn, and Cd in a terrestrial and water-logged habitat. Plant yield and photosynthetic performance was the highest in the aquatic environment; however, the presence of toxic metals (TM) negatively affected photosystem II (PSII) photochemistry as shown by the JIP test. Fungi colonization and Cd accumulation within plant tissues was decreased. In the terrestrial habitat, neither arbuscular mycorrhizal fungi (AMF) nor metal toxicity affected plant growth, although metal uptake, Cd in particular, as well as photosynthesis were affected. Inoculated plants accumulated significantly more Cd, and photosynthesis was downregulated. The results presented in this study clearly indicate that the I. pseudacorus-AMF symbiosis adapts itself to the presence of toxic metals in the environment, optimizing resource supply, energy fluxes, and possibly stress tolerance mechanisms. Plant/AMF consortia grown in terrestrial and water-logged habitats utilize different strategies to cope with metal toxicity. The use of AMF in improving the phytoremediation potential of I. pseudacorus needs, however, further research.

  14. Propensity to metal accumulation and oxidative stress responses of two benthic species (Cerastoderma edule and Nephtys hombergii): are tolerance processes limiting their responsiveness?

    KAUST Repository

    Marques, Ana


    The chronic exposure of benthic organisms to metals in sediments can lead to the development of tolerance mechanisms, thus diminishing their responsiveness. This study aims to evaluate the accumulation profiles of V, Cr, Co, Ni, As, Cd, Pb and Hg and antioxidant system responses of two benthic organisms (Cerastoderma edule, Bivalvia; Nephtys hombergii, Polychaeta). This approach will provide clarifications about the ability of each species to signalise metal contamination. Organisms of both species were collected at the Tagus estuary, in two sites with distinct contamination degrees (ALC, slightly contaminated; BAR, highly contaminated). Accordingly, C. edule accumulated higher concentrations of As, Pb and Hg at BAR compared to ALC. However, antioxidant responses of C. edule were almost unaltered at BAR and no peroxidative damage occurred, suggesting adjustment mechanisms to the presence of metals. In contrast, N. hombergii showed a minor propensity to metal accumulation, only signalising spatial differences for As and Pb and accumulating lower concentrations of metals than C. edule. The differences in metal accumulation observed between species might be due to their distinctive foraging behaviour and/or the ability of N. hombergii to minimise the metal uptake. Despite that, the accumulation of As and Pb was on the basis of the polychaete antioxidant defences inhibition at BAR, including CAT, SOD, GR and GPx. The integrated biomarker response index (IBRv2) confirmed that N. hombergii was more affected by metal exposure than C. edule. In the light of current findings, in field-based studies, the information of C. edule as a bioindicator should be complemented by that provided by another benthic species, since tolerance mechanisms to metals can hinder a correct diagnosis of sediment contamination and of the system’s health. Overall, the present study contributed to improve the lack of fundamental knowledge of two widespread and common estuarine species, providing

  15. Trifolium isthmocarpum Brot, a salt-tolerant wild leguminous forage crop in salt-affected soils

    Directory of Open Access Journals (Sweden)

    Kawtar Bennani


    Full Text Available Plant scientists are investigating the potential of previously unexploited legume species where environmental and biological stresses constrain the use of more conventional forage crops or where these species are better suited to the needs of sustainable agriculture. Trifolium isthmocarpum Brot., Moroccan clover, occurs as a weed in different habitats in Morocco. It grows in moderately saline areas, where traditional forage legumes cannot be cultivated; however, it has not been widely studied despite its good palatability. The salt tolerance was studied between natural field conditions and glasshouse. The extensive field studies have recorded the species in many different habitats ranging from healthy agricultural lands to abandoned saline areas. The plants maintained high nodulation capacity (ranging between 60% and 97% and nitrogenase activities (average 2.04 µmol C2H4 plant-1 h-1 in different habitats. Shoot systems of plants collected from salt-affected soils exhibited higher concentrations of Na+ and Cl- than those collected from healthy soils. Greenhouse experiments showed that germination percentage and vigor value of the studied species was not significantly (P > 0.05 affected at 160 mM NaCl, and that 25% of the germination ability was maintained when growing on substrats containing 240 mM NaCl. The growth rate of seedlings was not signicantly affected by 160 mM NaCl but was reduced by 38% under 240 mM NaCl. Leaf succulence and indices of leaf water status did not differ among the salt treatments, whereas relative water content was reduced by only 8% and water content at saturation increased by about 12% at high salt concentrations in the growing medium. This study suggest recommending the cultivation of T. isthmocarpum in salt-affected soils, which are widespread and pose a problem for the farmers of Morocco and other countries in the world’s arid belt.

  16. Metal ions affecting the pulmonary and cardiovascular systems. (United States)

    Corradi, Massimo; Mutti, Antonio


    Some metals, such as copper and manganese, are essential to life and play irreplaceable roles in, e.g., the functioning of important enzyme systems. Other metals are xenobiotics, i.e., they have no useful role in human physiology and, even worse, as in the case of lead, may be toxic even at trace levels of exposure. Even those metals that are essential, however, have the potential to turn harmful at very high levels of exposure, a reflection of a very basic tenet of toxicology--"the dose makes the poison." Toxic metal exposure may lead to serious risks to human health. As a result of the extensive use of toxic metals and their compounds in industry and consumer products, these agents have been widely disseminated in the environment. Because metals are not biodegradable, they can persist in the environment and produce a variety of adverse effects. Exposure to metals can lead to damage in a variety of organ systems and, in some cases, metals also have the potential to be carcinogenic. Even though the importance of metals as environmental health hazards is now widely appreciated, the specific mechanisms by which metals produce their adverse effects have yet to be fully elucidated. The unifying factor in determining toxicity and carcinogenicity for most metals is the generation of reactive oxygen and nitrogen species. Metal-mediated formation of free radicals causes various modifications to nucleic acids, enhanced lipid peroxidation, and altered calcium and sulfhydryl homeostasis. Whilst copper, chromium, and cobalt undergo redox-cycling reactions, for metals such as cadmium and nickel the primary route for their toxicity is depletion of glutathione and bonding to sulfhydryl groups of proteins. This chapter attempts to show that the toxic effects of different metallic compounds may be manifested in the pulmonary and cardiovascular systems. The knowledge of health effects due to metal exposure is necessary for practising physicians, and should be assessed by inquiring

  17. Improved tolerance of maize (Zea mays L.) to heavy metals by colonization of a dark septate endophyte (DSE) Exophiala pisciphila

    Energy Technology Data Exchange (ETDEWEB)

    Li, T.; Liu, M.J.; Zhang, X.T. [Key Laboratory of Conservation and Utilization for Bioresources, Yunnan University, Kunming, 650091 Yunnan (China); Zhang, H.B. [Key Laboratory of Conservation and Utilization for Bioresources, Yunnan University, Kunming, 650091 Yunnan (China); Department of Biology, Yunnan University, Kunming, 650091 Yunnan (China); Sha, T. [Key Laboratory of Conservation and Utilization for Bioresources, Yunnan University, Kunming, 650091 Yunnan (China); Zhao, Z.W., E-mail: [Key Laboratory of Conservation and Utilization for Bioresources, Yunnan University, Kunming, 650091 Yunnan (China)


    Dark septate endophytes (DSE) are ubiquitous and abundant in stressful environments including heavy metal (HM) stress. However, our knowledge about the roles of DSE in improving HM tolerance of their host plants is poor. In this study, maize (Zea mays L.) was inoculated with a HM tolerant DSE strain Exophiala pisciphila H93 in lead (Pb), zinc (Zn), and cadmium (Cd) contaminated soils. E. pisciphila H93 successfully colonized and formed typical DSE structures in the inoculated maize roots. Colonization of E. pisciphila H93 alleviated the deleterious effects of excessive HM supplements and promoted the growth of maize (roots and shoots) under HM stress conditions, though it significantly decreased the biomass of inoculated maize under no HM stress. Further analysis showed that the colonization of E. pisciphila H93 improved the tolerance of maize to HM by restricting the translocation of HM ions from roots to shoots. This study demonstrated that under higher HM stress, such a mutual symbiosis between E. pisciphila and its host (maize) may be an efficient strategy to survive in the stressful environments. - Research Highlights: {yields}Effect of DSE (E. pisciphila) on heavy metal tolerance of maize host was studied. {yields}DSE alleviated the deleterious effect of excessive heavy metals on maize. {yields}DSE restricted the transfer of heavy metals from the roots to shoots in maize. {yields}DSE colonization improved the tolerance of their host plants to heavy metals.

  18. Tolerance to Cadmium of Agave lechuguilla (Agavaceae Seeds and Seedlings from Sites Contaminated with Heavy Metals

    Directory of Open Access Journals (Sweden)

    Alejandra Méndez-Hurtado


    Full Text Available We investigated if seeds of Agave lechuguilla from contaminated sites with heavy metals were more tolerant to Cd ions than seeds from noncontaminated sites. Seeds from a highly contaminated site (Villa de la Paz and from a noncontaminated site (Villa de Zaragoza were evaluated. We tested the effect of Cd concentrations on several ecophysiological, morphological, genetical, and anatomical responses. Seed viability, seed germination, seedling biomass, and radicle length were higher for the non-polluted site than for the contaminated one. The leaves of seedlings from the contaminated place had more cadmium and showed peaks attributed to chemical functional groups such as amines, amides, carboxyl, and alkenes that tended to disappear due to increasing the concentration of cadmium than those from Villa de Zaragoza. Malformed cells in the parenchyma surrounding the vascular bundles were found in seedlings grown with Cd from both sites. The leaves from the contaminated place showed a higher metallothioneins expression in seedlings from the control group than that of seedlings at different Cd concentrations. Most of our results fitted into the hypothesis that plants from metal-contaminated places do not tolerate more pollution, because of the accumulative effect that cadmium might have on them.

  19. Tolerance to cadmium of Agave lechuguilla (Agavaceae) seeds and seedlings from sites contaminated with heavy metals. (United States)

    Méndez-Hurtado, Alejandra; Rangel-Méndez, René; Yáñez-Espinosa, Laura; Flores, Joel


    We investigated if seeds of Agave lechuguilla from contaminated sites with heavy metals were more tolerant to Cd ions than seeds from noncontaminated sites. Seeds from a highly contaminated site (Villa de la Paz) and from a noncontaminated site (Villa de Zaragoza) were evaluated. We tested the effect of Cd concentrations on several ecophysiological, morphological, genetical, and anatomical responses. Seed viability, seed germination, seedling biomass, and radicle length were higher for the non-polluted site than for the contaminated one. The leaves of seedlings from the contaminated place had more cadmium and showed peaks attributed to chemical functional groups such as amines, amides, carboxyl, and alkenes that tended to disappear due to increasing the concentration of cadmium than those from Villa de Zaragoza. Malformed cells in the parenchyma surrounding the vascular bundles were found in seedlings grown with Cd from both sites. The leaves from the contaminated place showed a higher metallothioneins expression in seedlings from the control group than that of seedlings at different Cd concentrations. Most of our results fitted into the hypothesis that plants from metal-contaminated places do not tolerate more pollution, because of the accumulative effect that cadmium might have on them.

  20. Preliminary tests for Salix sp. tolerance to heavy metals (Cd, Ni, Pb) (United States)

    Corneanu, Mihaela; Hernea, Cornelia; Butnariu, Monica; Corneanu, Gabriel; Sărac, Ioan; Hollerbach, Wilhelm; Neţoiu, Constantin; Petcov, Andreea Adriana


    The species of Salix genus constitute potential sources of germplasm in the prevention of the environment degradation, and offer remedy for about two third from the all degradation types. The majority of the willow species, present a good adaptation to hypoxic conditions, feature which suggest that they manifest a preference for mineral nutrition in comparison with organic one. Thus, many of willow species can be developed on soils with a big amount of minerals and/or radionuclides, being both phytoremediatory species, as well as pioneer ones, contributing to the restoration of soil. Thus, the willow species, posses the capacity for development in degraded areas, natural or anthropic, as swamps, abandoning crops areas, sandy dune, riparian sandy areas, gravels, a.o. In this paper are present some laboratory comparative tests of heavy metals tolerance on four Salix sp. genotypes: clone 202 (Salix alba), hybrid 892 (Salix alba), Inger (Salix viminalis) and Gudrun (Salix viminalis). The genotypes of Salix alba are native from Romania, produced in the Forest Research and Management Institute Bucharest, while the genotypes of Salix viminalis are native from Sweden, but the plant material was produced under license in Romania by REBINA Agrar SRL. As plant material were used one-year-old cuttings (5-10 cm long), with 2-6 buds each. Per genotype, per heavy metal and each of three concentration five replication were used. There were ten experimental variants for each genotype: three concentrations for each of the heavy metals; concentrations selected, in the accordance SR ISO 11269-2/March 1999 and Control (tap water). The cuttings were maintained in metalic solutions for 15 days. In the days 7th and 15th, were performed biometrical observations on: the roots number and length, the shoots number and length, the leaves number/shoot, viability of the shoots. At the end of the experiment the content in heavy metals was determined in roots and shoots (by atomic absorption

  1. Identification of quantitative trait loci affecting tolerance to low phosphorus in rice (Oryza Sativa L.)

    Institute of Scientific and Technical Information of China (English)


    Phosphorus (P)-deficiency in rice (Oryza.Sativa.L) may cause yield reductions.This research has been conducted to map quantitative trait loci (QTLs) for tolerance to low phosphorus stress in a doubled haploid (DH) population.By using the linkage map of this population,the QTLs for relative dry weight,relative P content and relative P utilization efficiency have been located.The results indicate that one RFLP marker located on chromosome 6 is closely associated with relative root dry weight,relative shoot dry weight and relative total dry weight,which explain 24.9%,20.5% and 25.2% of the total phenotypic variations,respectively.Two QTLs affect relative P uptake content,which account for 20.7% of the total phenotypic variations.One micro-effect QTL has been found to be associated with relative P utilization efficiency.It is suggested that the P uptake efficiency is more associated with P efficiency.Among the secondary physiological indices of P uptake efficiency,the root dry weight is more important than others.

  2. Rhizobacteria containing ACC-deaminase confer salt tolerance in maize grown on salt-affected fields. (United States)

    Nadeem, Sajid Mahmood; Zahir, Zahir Ahmad; Naveed, Muhammad; Arshad, Muhammad


    Salt stress is one of the major constraints hampering agricultural production owing to its impact on ethylene production and nutritional imbalance. A check on the accelerated ethylene production in plants could be helpful in minimizing the negative effect of salt stress on plant growth and development. Four Pseudomonas, 1 Flavobacterium, and 1 Enterobacter strain of plant growth promoting rhizobacteria containing 1-aminocyclopropane-1-carboxylate (ACC)-deaminase were selected and their effects on growth and yield of maize were investigated to improve the salt tolerance of maize grown on salt-affected fields. The selected rhizobacterial isolates reduced or eliminated the classical "triple" response, indicating their ability to reduce stress-induced ethylene levels. Results showed that rhizobacterial strains, particularly Pseudomonas and Enterobacter spp., significantly promoted the growth and yield of maize compared with the non-inoculated control. Pseudomonas fluorescens increased plant height, biomass, cob yield, grain yield, 1000 grain mass, and straw yield of maize up to 29%, 127%, 67%, 60%, 17%, and 166%, respectively, over the control. Under stress conditions, more N, P, and K uptake and high K+-Na+ ratios were recorded in inoculated plants compared with the control. The results imply that inoculation with plant growth promoting rhizobacteria containing ACC-deaminase could be a useful approach for improving growth and yield of maize under salt-stressed conditions.

  3. Children's and Adolescents' Tolerance for Divergent Beliefs: Exploring the Cognitive and Affective Dimensions of Moral Conviction in Our Youth (United States)

    Wright, Jennifer C.


    Moral conviction predicts interpersonal tolerance in adults, but its role in children and adolescents is not as well understood. This study measured moral conviction for a variety of issues along two separate dimensions--cognitive and affective--in children and adolescents (4th-12th grade). Results showed that, like adults, when children and…

  4. Adaptive alterations in the fatty acids composition under induced oxidative stress in heavy metal-tolerant filamentous fungus Paecilomyces marquandii cultured in ascorbic acid presence. (United States)

    Słaba, Mirosława; Gajewska, Ewa; Bernat, Przemysław; Fornalska, Magdalena; Długoński, Jerzy


    The ability of the heavy metal-tolerant fungus Paecilomyces marquandii to modulate whole cells fatty acid composition and saturation in response to IC50 of Cd, Pb, Zn, Ni, and Cu was studied. Cadmium and nickel caused the most significant growth reduction. In the mycelia cultured with all tested metals, with the exception of nickel, a rise in the fatty acid unsaturation was noted. The fungus exposure to Pb, Cu, and Ni led to significantly higher lipid peroxidation. P. marquandii incubated in the presence of the tested metals responded with an increase in the level of linoleic acid and escalation of electrolyte leakage. The highest efflux of electrolytes was caused by lead. In these conditions, the fungus was able to bind up to 100 mg g(-1) of lead, whereas the content of the other metals in the mycelium was significantly lower and reached from 3.18 mg g(-1) (Cu) to 15.21 mg g(-1) (Zn). Additionally, it was shown that ascorbic acid at the concentration of 1 mM protected fungal growth and prevented the changes in the fatty acid composition and saturation but did not alleviate lipid peroxidation or affect the increased permeability of membranes after lead exposure. Pro-oxidant properties of ascorbic acid in the copper-stressed cells manifested strong growth inhibition and enhanced metal accumulation as a result of membrane damage. Toxic metals action caused cellular modulations, which might contributed to P. marquandii tolerance to the studied metals. Moreover, these changes can enhance metal removal from contaminated environment.

  5. Preliminary screening of Ni(II metal tolerance and dye-decolorizing by Nocardiopsis sp. SD8

    Directory of Open Access Journals (Sweden)

    Ramasamy Thangaraj


    Full Text Available Objective: To reveal the screening of metal tolerance and dye-decolorizing of Nocardiopsis sp. Methods: NiSO4 and Congo red dye were used for evaluating the metal tolerance and dyedecolorizing of the randomly selected actinobacterial isolates. Results: Nocardiopsis sp. SD8 showed a better efficiency in Ni(II tolerance, though a longer lag phase was observed for this microorganism grown for 7 days in integrated mismatch negativity. Interestingly, we also found that Nocardiopsis sp. SD8 had dye-decolorizing, hemolytic, lipase and protease activity. Conclusions: The present results revealed the bioremediation of metal resistant and diverse properties of Nocardiopsis sp. SD8 and further investigations are needed to extract and identify the potent molecule.

  6. Preliminary screening of Ni(II) metal tolerance and dye-decolorizing byNocardiopsis sp. SD8

    Institute of Scientific and Technical Information of China (English)

    Ramasamy Thangaraj; Saha Subhasish; Dharumadurai Dhanasekaran; Nooruddin Thajuddin


    Objective:To reveal the screening of metal tolerance and dye-decolorizing ofNocardiopsis sp. Methods: NiSO4 and Congo red dye were used for evaluating the metal tolerance and dye-decolorizing of the randomly selected actinobacterial isolates. Results:Nocardiopsis sp.SD8 showed a better efficiency in Ni(II) tolerance, though a longer lag phase was observed for this microorganism grown for 7 days in integrated mismatch negativity. Interestingly, we also found thatNocardiopsis sp.SD8 had dye-decolorizing, hemolytic, lipase and protease activity. Conclusions:The present results revealed the bioremediation of metal resistant and diverse properties ofNocardiopsis sp.SD8 and further investigations are needed to extract and identify the potent molecule.

  7. A System Gone Berserk: How Are Zero-Tolerance Policies Really Affecting Schools? (United States)

    Martinez, Stephanie


    School administrators continue to use zero-tolerance policies as a one-size-fits-all, quick-fix solution to curbing discipline problems with students. Originally intended to address serious offenses such as possession of firearms, zero-tolerance policies are also now meant to address fighting and disrespect. Despite the seeming popularity of…


    NARCIS (Netherlands)

    Stuiver, C.E.E.; De Kok, Luit J.; Kuiper, P.J.C.


    Fumigation of winter wheat with H2S during low temperature acclimation substantially reduced the development of freezing tolerance of the leaves. After 6 weeks of low temperature exposure (3-degrees-C), the freezing tolerance was increased by 6 and 2-degrees-C at 0 and 0.25-mu-l l-1 H2S, respectivel

  9. Aluminum-Tolerant Pisolithus Ectomycorrhizas Confer Increased Growth, Mineral Nutrition, and Metal Tolerance to Eucalyptus in Acidic Mine Spoil

    Directory of Open Access Journals (Sweden)

    Louise Egerton-Warburton


    Full Text Available Ectomycorrhizal fungi (ECM may increase the tolerance of their host plants to Al toxicity by immobilizing Al in fungal tissues and/or improving plant mineral nutrition. Although these benefits have been demonstrated in in vitro (pure culture or short-term nutrient solution (hydroponic experiments, fewer studies have examined these benefits in the field. This study examined the growth, mineral nutrition, and Al levels in two Eucalyptus species inoculated with three Pisolithus ecotypes that varied in Al tolerance (in vitro and grown in mine spoil in the greenhouse and field. All three ecotypes of Pisolithus improved Eucalyptus growth and increased host plant tolerance to Al in comparison to noninoculated plants. However, large variations in plant growth and mineral nutrition were detected among the Pisolithus-inoculated plants; these differences were largely explained by the functional properties of the Pisolithus inoculum. Seedlings inoculated with the most Al-tolerant Pisolithus inoculum showed significantly higher levels of N, P, Ca, Mg, and K and lower levels of Al than seedlings inoculated with Al-sensitive ecotypes of Pisolithus. These findings indicate an agreement between the fungal tolerance to Al in vitro and performance in symbiosis, indicating that both ECM-mediated mineral nutrient acquisition and Al accumulation are important in increasing the host plant Al tolerance.

  10. Invertebrate grazers affect metal/metalloid fixation during litter decomposition. (United States)

    Schaller, Jörg; Brackhage, Carsten


    Plant litter and organic sediments are main sinks for metals and metalloids in aquatic ecosystems. The effect of invertebrates as key species in aquatic litter decomposition on metal/metalloid fixation by organic matter is described only for shredders, but for grazers as another important animal group less is known. Consequently, a laboratory batch experiment was conducted to examine the effect of invertebrate grazers (Lymnaea stagnalis L.) on metal/metalloid fixation/remobilization during aquatic litter decomposition. It could be shown that invertebrate grazers facilitate significantly the formation of smaller sizes of particulate organic matter (POM), as shown previously for invertebrate shredders. The metal/metalloid binding capacity of these smaller particles of POM is higher compared to leaf litter residuals. But element enrichment is not as high as shown previously for the effect by invertebrate shredders. Invertebrate grazers enhance also the mobilization of selected elements to the water, in the range also proven for invertebrate shredders but different for the different elements. Nonetheless invertebrate grazers activity during aquatic litter decomposition leads to a metal/metalloid fixation into leaf litter as part of sediment organic matter. Hence, the effect of invertebrate grazers on metal/metalloid fixation/remobilization contrasts partly with former assessments revealing the possibility of an enhanced metal/metalloid fixation.

  11. Biologics formulation factors affecting metal leachables from stainless steel. (United States)

    Zhou, Shuxia; Schöneich, Christian; Singh, Satish K


    An area of increasing concern and scientific scrutiny is the potential contamination of drug products by leachables entering the product during manufacturing and storage. These contaminants may either have a direct safety impact on the patients or act indirectly through the alteration of the physicochemical properties of the product. In the case of biotherapeutics, trace amounts of metal contaminants can arise from various sources, but mainly from contact with stainless steel (ss). The effect of the various factors, buffer species, solution fill volume per unit contact surface area, metal chelators, and pH, on metal leachables from contact with ss over time were investigated individually. Three major metal leachables, iron, chromium, and nickel, were monitored by inductively coupled plasma-mass spectrometry because they are the major components of 316L ss. Iron was primarily used to evaluate the effect of each factor since it is the most abundant. It was observed that each studied factor exhibited its own effect on metal leachables from contact with ss. The effect of buffer species and pH exhibited temperature dependence over the studied temperature range. The metal leachables decreased with the increased fill volume (mL) per unit contact ss surface area (cm(2)) but a plateau was achieved at approximately 3 mL/cm(2). Metal chelators produced the strongest effect in facilitating metal leaching. In order to minimize the metal leachables and optimize biological product stability, each formulation factor must be evaluated for its impact, to balance its risk and benefit in achieving the target drug product shelf life.

  12. Ultra-strong and damage tolerant metallic bulk materials: A lesson from nanostructured pearlitic steel wires. (United States)

    Hohenwarter, A; Völker, B; Kapp, M W; Li, Y; Goto, S; Raabe, D; Pippan, R


    Structural materials used for safety critical applications require high strength and simultaneously high resistance against crack growth, referred to as damage tolerance. However, the two properties typically exclude each other and research efforts towards ever stronger materials are hampered by drastic loss of fracture resistance. Therefore, future development of novel ultra-strong bulk materials requires a fundamental understanding of the toughness determining mechanisms. As model material we use today's strongest metallic bulk material, namely, a nanostructured pearlitic steel wire, and measured the fracture toughness on micron-sized specimens in different crack growth directions and found an unexpected strong anisotropy in the fracture resistance. Along the wire axis the material reveals ultra-high strength combined with so far unprecedented damage tolerance. We attribute this excellent property combination to the anisotropy in the fracture toughness inducing a high propensity for micro-crack formation parallel to the wire axis. This effect causes a local crack tip stress relaxation and enables the high fracture toughness without being detrimental to the material's strength.

  13. Ultra-strong and damage tolerant metallic bulk materials: A lesson from nanostructured pearlitic steel wires (United States)

    Hohenwarter, A.; Völker, B.; Kapp, M. W.; Li, Y.; Goto, S.; Raabe, D.; Pippan, R.


    Structural materials used for safety critical applications require high strength and simultaneously high resistance against crack growth, referred to as damage tolerance. However, the two properties typically exclude each other and research efforts towards ever stronger materials are hampered by drastic loss of fracture resistance. Therefore, future development of novel ultra-strong bulk materials requires a fundamental understanding of the toughness determining mechanisms. As model material we use today’s strongest metallic bulk material, namely, a nanostructured pearlitic steel wire, and measured the fracture toughness on micron-sized specimens in different crack growth directions and found an unexpected strong anisotropy in the fracture resistance. Along the wire axis the material reveals ultra-high strength combined with so far unprecedented damage tolerance. We attribute this excellent property combination to the anisotropy in the fracture toughness inducing a high propensity for micro-crack formation parallel to the wire axis. This effect causes a local crack tip stress relaxation and enables the high fracture toughness without being detrimental to the material’s strength.

  14. Simultaneous production of alkaline lipase and protease by antibiotic and heavy metal tolerant Pseudomonas aeruginosa. (United States)

    Bisht, Deepali; Yadav, Santosh Kumar; Gautam, Pallavi; Darmwal, Nandan Singh


    An efficient bacterial strain capable of simultaneous production of lipase and protease in a single production medium was isolated. Thirty six bacterial strains, isolated from diverse habitats, were screened for their lipolytic and proteolytic activity. Of these, only one bacterial strain was found to be lipase and protease producer. The 16S rDNA sequencing and phylogenetic analyses revealed that strain (NSD-09) was in close identity to Pseudomonas aeruginosa. The maximum lipase (221.4 U/ml) and protease (187.9 U/ml) activities were obtained after 28 and 24 h of incubation, respectively at pH 9.0 and 37 °C. Castor oil and wheat bran were found to be the best substrate for lipase and protease production, respectively. The strain also exhibited high tolerance to lead (1450 µg/ml) and chromium (1000 µg/ml) in agar plates. It also showed tolerance to other heavy metals, such as Co(+2) , Zn(+2) , Hg(+2) , Ni(+2) and Cd(+2) . Therefore, this strain has scope for tailing bioremediation. Presumably, this is the first attempt on P. aeruginosa to explore its potential for both industrial and environmental applications.

  15. Protein sequences insight into heavy metal tolerance in Cronobacter sakazakii BAA-894 encoded by plasmid pESA3. (United States)

    Chaturvedi, Navaneet; Kajsik, Michal; Forsythe, Stephen; Pandey, Paras Nath


    The recently annotated genome of the bacterium Cronobacter sakazakii BAA-894 suggests that the organism has the ability to bind heavy metals. This study demonstrates heavy metal tolerance in C. sakazakii, in which proteins with the heavy metal interaction were recognized by computational and experimental study. As the result, approximately one-fourth of proteins encoded on the plasmid pESA3 are proposed to have potential interaction with heavy metals. Interaction between heavy metals and predicted proteins was further corroborated using protein crystal structures from protein data bank database and comparison of metal-binding ligands. In addition, a phylogenetic study was undertaken for the toxic heavy metals, arsenic, cadmium, lead and mercury, which generated relatedness clustering for lead, cadmium and arsenic. Laboratory studies confirmed the organism's tolerance to tellurite, copper and silver. These experimental and computational study data extend our understanding of the genes encoding for proteins of this important neonatal pathogen and provide further insights into the genotypes associated with features that can contribute to its persistence in the environment. The information will be of value for future environmental protection from heavy toxic metals.

  16. A new pathway for heavy metal detoxification in animals. Phytochelatin synthase is required for cadmium tolerance in Caenorhabditis elegans. (United States)

    Vatamaniuk, O K; Bucher, E A; Ward, J T; Rea, P A


    Increasing emissions of heavy metals such as cadmium, mercury, and arsenic into the environment pose an acute problem for all organisms. Considerations of the biochemical basis of heavy metal detoxification in animals have focused exclusively on two classes of peptides, the thiol tripeptide, glutathione (GSH, gamma-Glu-Cys-Gly), and a diverse family of cysteine-rich low molecular weight proteins, the metallothioneins. Plants and some fungi, however, not only deploy GSH and metallothioneins for metal detoxification but also synthesize another class of heavy metal binding peptides termed phytochelatins (PCs) from GSH. Here we show that PC-mediated heavy metal detoxification is not restricted to plants and some fungi but extends to animals by demonstrating that the ce-pcs-1 gene of the nematode worm Caenorhabditis elegans encodes a functional PC synthase whose activity is critical for heavy metal tolerance in the intact organism.

  17. Rhizosphere microbial densities and trace metal tolerance of the nickel hyperaccumulator Alyssum serpyllifolium subsp. lusitanicum. (United States)

    Becerra-Castro, C; Monterroso, C; García-Lestón, M; Prieto-Fernández, A; Acea, M J; Kidd, P S


    In this study we determine culturable microbial densities (total heterotrophs, ammonifiers, amylolytics and cellulolytics) and bacterial resistance to Co, Cr, and Ni in bulk and rhizosphere soils of three populations of the Ni-hyperaccumulator Alyssum serpyllifolium subsp. lusitanicum and the excluder Dactylis glomerata from ultramafic sites (two populations in Northeast (NE) Portugal (Samil (S), Morais (M)) and one population in Northwest (NW) Spain (Melide (L)). The relationship between bioavailable metal concentrations (H2O-soluble) and microbial densities were analysed. Significant differences in microbial densities and metal-resistance were observed between the two species and their three populations. The hyperaccumulator showed higher microbial densities (except cellulolytics) and a greater rhizosphere effect, but this was only observed in S and M populations. These populations of A. serpyllifolium also showed selective enrichment of Ni-tolerant bacteria at the rhizosphere where Ni solubility was enhanced (densities of Ni-resistant bacteria were positively correlated with H2O-soluble Ni). These rhizobacteria could solubilise Ni in the soil and potentially improve phytoextraction strategies.

  18. Key factors affecting mechanical behavior of metallic glass nanowires (United States)

    Zhang, Qi; Li, Qi-Kai; Li, Mo


    Both strengthening and weakening trends with decreasing diameter have been observed for metallic glass nanowires, sometimes even in the samples with the same chemical composition. How to reconcile the results has reminded a puzzle. Since the detailed stress state and microstructure of metallic glass nanowires may differ from each other significantly depending on preparation, to discover the intrinsic size effect it is necessary to study metallic glass nanowires fabricated differently. Here we show the complex size effects from one such class of metallic glass nanowires prepared by casting using molecular dynamics simulations. As compared with the nanowires of the same composition prepared by other methods, the cast nanowires deform nearly homogeneously with much lower strength but better ductility; and also show strengthening in tension but weakening in compression with decreasing wire diameter. The subtle size dependence is shown to be related to the key factors including internal and surface stress state, atomic structure variation, and presence of various gradients. The complex interplay of these factors at decreasing size leads to the different deformation behaviors.

  19. Factors Affecting the Binding of a Recombinant Heavy Metal-Binding Domain (CXXC motif Protein to Heavy Metals

    Directory of Open Access Journals (Sweden)

    Kamala Boonyodying


    Full Text Available A number of heavy metal-binding proteins have been used to study bioremediation. CXXC motif, a metal binding domain containing Cys-X-X-Cys motif, has been identified in various organisms. These proteins are capable of binding various types of heavy metals. In this study, heavy metal binding domain (CXXC motif recombinant protein encoded from mcsA gene of S. aureus were cloned and overexpressed in Escherichia coli. The factors involved in the metal-binding activity were determined in order to analyze the potential of recombinant protein for bioremediation. A recombinant protein can be bound to Cd2+, Co2+, Cu2+ and Zn2+. The thermal stability of a recombinant protein was tested, and the results showed that the metal binding activity to Cu2+ and Zn2+ still exist after treating the protein at 85ºC for 30 min. The temperature and pH that affected the metal binding activity was tested and the results showed that recombinant protein was still bound to Cu2+ at 65ºC, whereas a pH of 3-7 did not affect the metal binding E. coli harboring a pRset with a heavy metal-binding domain CXXC motif increased the resistance of heavy metals against CuCl2 and CdCl2. This study shows that metal binding domain (CXXC motif recombinant protein can be effectively bound to various types of heavy metals and may be used as a potential tool for studying bioremediation.

  20. Issues Affecting the Synthetic Scalability of Ternary Metal Ferrite Nanoparticles

    Directory of Open Access Journals (Sweden)

    Lauren Morrow


    Full Text Available Ternary Mn-Zn ferrite (MnxZn1-xFe2O4 nanoparticles (NPs have been prepared by the thermal decomposition of an oleate complex, sodium dodecylbenzenesulfonate (SDBS mediated hydrazine decomposition of the chloride salts, and triethylene glycol (TREG mediated thermal decomposition of the metal acetylacetonates. Only the first method was found to facilitate the synthesis of uniform, isolable NPs with the correct Mn : Zn ratio (0.7 : 0.3 as characterized by small angle X-ray scattering (SAXS, transmission electron microscopy (TEM, and inductively coupled plasma-optical emission spectroscopy (ICP-OES. Scaling allowed for retention of the composition and size; however, attempts to prepare Zn-rich ferrites did not result in NP formation. Thermogravimetric analysis (TGA indicated that the incomplete decomposition of the metal-oleate complexes prior to NP nucleation for Zn-rich compositions is the cause.

  1. Battlefield-Acquired Immunogenicity to Metals Affects Orthopaedic Implant Outcome (United States)


    Group 1 = members who sustained a metal fragment injury, Group 2 = service members who sustained a non-penetrating injury, Group 3 = healthy civilian...adaptive immune system involves the production of a very large repertoire of antigen-specific cells. An innate immune response is generally less...Briatico-Vangosa G, Kaestner W, Lally C, Bontinck WJ. Nickel, cobalt and chromium in consumer products : a role in allerg ic contact dermat itis? Contact

  2. Lemna minor tolerance to metal-working fluid residues: implications for rhizoremediation. (United States)

    Grijalbo, L; Becerril, J M; Barrutia, O; Gutierrez-Mañero, J; Lucas Garcia, J A


    For the first time in the literature, duckweed (Lemna minor) tolerance (alone or in combination with a consortium of bacteria) to spent metal-working fluid (MWF) was assessed, together with its capacity to reduce the chemical oxygen demand (COD) of this residue. In a preliminary study, L. minor response to pre-treated MWF residue (ptMWF) and vacuum-distilled MWF water (MWFw) was tested. Plants were able to grow in both residues at different COD levels tested (up to 2300 mg·l(-1) ), showing few toxicity symptoms (mainly growth inhibition). Plant response to MWFw was more regular and dose responsive than when exposed to ptMWF. Moreover, COD reduction was less significant in ptMWF. Thus, based on these preliminary results, a second study was conducted using MWFw to test the effectiveness of inoculation with a bacterial consortium isolated from a membrane bioreactor fed with the same residue. After 5 days of exposure, COD in solutions containing inoculated plants was significantly lower than in non-inoculated ones. Moreover, inoculation reduced β+γ-tocopherol levels in MWFw-exposed plants, suggesting pollutant imposed stress was reduced. We therefore conclude from that L. minor is highly tolerant to spent MWF residues and that this species can be very useful, together with the appropriate bacterial consortium, in reducing COD of this residue under local legislation limits and thus minimise its potential environmental impact. Interestingly, the lipophilic antioxidant tocopherol (especially the sum of β+γ isomers) proved to be an effective plant biomarker of pollution.

  3. Biosurfactant activity, heavy metal tolerance and characterization of Joostella strain A8 from the Mediterranean polychaete Megalomma claparedei (Gravier, 1906). (United States)

    Rizzo, Carmen; Michaud, Luigi; Graziano, Marco; De Domenico, Emilio; Syldatk, Christoph; Hausmann, Rudolf; Lo Giudice, Angelina


    The effect of heavy metals on the activity of biosurfactants produced by Joostella strain A8 from the polychaete Megalomma claparedei was investigated. Biosurfactant activity was first improved by evaluating the influence of abiotic parameters. Higher E(24) indices were achieved at 25 °C in mineral salt medium supplemented with 2 % glucose, 3 % sodium chloride (w/v) and 0.1 % ammonium chloride (w/v). Considerable surface tension reduction was never recorded. Heavy metal tolerance was preliminarily assayed by plate diffusion method resulting in the order of toxicity Cd > Cu > Zn. The activity of biosurfactants was then evaluated in the presence of heavy metals at different concentrations in liquid cultures that were incubated under optimal conditions for biosurfactant activity. The production of stable emulsions resulted generally higher in the presence of metals. These findings suggest that biosurfactant production could represent a bacterial adaptive strategy to defend cells from a stress condition derived from heavy metals in the bulk environment.

  4. Geometry Affected Delamination of Polymer/Metal Metamaterials

    NARCIS (Netherlands)

    Beusink, M.; Valega Mackenzie, F.O.; Coenen, E.W.C.


    At present several material combinations are fabricated to cover the demands of ubiquitous applications. In the case of meta materials, properties are greatly affected not only by composition and shape, but also by interfacial strength and directionality of the patterned substructure. In this work a

  5. Point mutation of H3/H4 histones affects acetic acid tolerance in Saccharomyces cerevisiae. (United States)

    Liu, Xiangyong; Zhang, Xiaohua; Zhang, Zhaojie


    The molecular mechanism of acetic acid tolerance in yeast remains unclear despite of its importance for efficient cellulosic ethanol production. In this study, we examined the effects of histone H3/H4 point mutations on yeast acetic acid tolerance by comprehensively screening a histone H3/H4 mutant library. A total of 24 histone H3/H4 mutants (six acetic acid resistant and 18 sensitive) were identified. Compared to the wild-type strain, the histone acetic acid-resistant mutants exhibited improved ethanol fermentation performance under acetic acid stress. Genome-wide transcriptome analysis revealed that changes in the gene expression in the acetic acid-resistant mutants H3 K37A and H4 K16Q were mainly related to energy production, antioxidative stress. Our results provide novel insights into yeast acetic acid tolerance on the basis of histone, and suggest a novel approach to improve ethanol production by altering the histone H3/H4 sequences.

  6. A NAC Transcription Factor Represses Putrescine Biosynthesis and Affects Drought Tolerance. (United States)

    Wu, Hao; Fu, Bing; Sun, Peipei; Xiao, Chang; Liu, Ji-Hong


    Arginine decarboxylase (ADC)-mediated putrescine biosynthesis plays an important role in plant stress responses, but the transcriptional regulation of ADC in response to abiotic stress is not well understood. We isolated a NAM, ATAF1/2, and CUC (NAC) domain-containing transcription factor, PtrNAC72, from trifoliate orange (Poncirus trifoliata) by yeast one-hybrid screening. PtrNAC72, localized to the nucleus, binds specifically to the promoter of PtADC and acts as a transcriptional repressor. PtrNAC72 expression was induced by cold, drought, and abscisic acid. ADC messenger RNA abundance and putrescine levels were decreased in transgenic tobacco (Nicotiana nudicaulis) plants overexpressing PtrNAC72 but increased, compared with the wild type, in an Arabidopsis (Arabidopsis thaliana) transfer DNA insertion mutant, nac72 While transgenic tobacco lines overexpressing PtrNAC72 were more sensitive to drought, plants of the Arabidopsis nac72 mutant exhibited enhanced drought tolerance, consistent with the accumulation of reactive oxygen species in the tested genotypes. In addition, exogenous application of putrescine to the overexpression lines restored drought tolerance, while treatment with d-arginine, an ADC inhibitor, compromised the drought tolerance of nac72 Taken together, these results demonstrate that PtrNAC72 is a repressor of putrescine biosynthesis and may negatively regulate the drought stress response, at least in part, via the modulation of putrescine-associated reactive oxygen species homeostasis.

  7. Ecological risk assessment of boreal sediments affected by metal mining: Metal geochemistry, seasonality, and comparison of several risk assessment methods. (United States)

    Väänänen, Kristiina; Kauppila, Tommi; Mäkinen, Jari; Leppänen, Matti T; Lyytikäinen, Merja; Akkanen, Jarkko


    The mining industry is a common source of environmental metal emissions, which cause long-lasting effects in aquatic ecosystems. Metal risk assessment is challenging due to variations in metal distribution, speciation, and bioavailability. Therefore, seasonal effects must be better understood, especially in boreal regions in which seasonal changes are large. We sampled 4 Finnish lakes and sediments affected by mining for metals and geochemical characteristics in autumn and late winter, to evaluate seasonal changes in metal behavior, the importance of seasonality in risk assessment, and the sensitivity and suitability of different risk assessment methods. We compared metal concentrations in sediment, overlying water, and porewater against environmental quality guidelines (EQGs). We also evaluated the toxicity of metal mixtures using simultaneously extracted metals and an acid volatile sulfides (SEM-AVS) approach together with water quality criteria (US Environmental Protection Agency equilibrium partitioning benchmarks). Finally, site-specific risks for 3 metals (Cu, Ni, Zn) were assessed using 2 biotic ligand models (BLMs). The metal concentrations in the impacted lakes were elevated. During winter stratification, the hypolimnetic O2 saturation levels were low (89%) and neutral pH (6.1-7.5) were found after the autumnal water overturn. Guidelines were the most conservative benchmark for showing an increased risk of toxicity in the all of the lakes. The situation remained stable between seasons. On the other hand, SEM-AVS, equilibrium partition sediment benchmarks (ESBs), and BLMs provided a clearer distinction between lakes and revealed a seasonal variation in risk among some of the lakes, which evidenced a higher risk during late winter. If a sediment risk assessment is based on the situation in the autumn, the overall risk may be underestimated. It is advisable to carry out sampling and risk assessment during periods in which metals are assumed to be the most

  8. An advanced field experimental design to assess plant tolerance to heavy metal pollution (United States)

    Łopata, Barbara; Szarek-Łukaszewska, Grażyna; Babst-Kostecka, Alicja


    Only a limited number of vascular plant species can survive and reproduce in toxic metalliferous environments. Among these species, pseudometallophytes are particularly interesting, as their metallicolous (M) populations on metalliferous soils and non-metallicolous (NM) populations on non-metalliferous soils show very pronounced ecological differences. Pseudometallophytes thus provide excellent opportunities for multidisciplinary research to improve phytoremediation and phytomining. Numerous methods have been developed to investigate plant adaptation to metal pollution, the majority of which has been conducted under controlled laboratory conditions. Although these efforts have significantly advanced our understanding of mechanisms underlying metal tolerance in plants, populations must be reciprocally transplanted to clearly identify natural selection. Only then is it possible to test, whether the fitness of native plants is higher than that of nonnative populations and thereby prove local adaptation. Here, we present an enhanced field experimental design aimed at verification of local adaptation to habitats with different levels of heavy metal soil contamination. At two M and two NM sites, we established a total of 12 plots (4 sites x 3 plots each), removed the existing local vegetation, and collected soil samples for chemical analyses (5 samples per plot). Plant collection (N= 480) from all four selected populations was established under laboratory conditions prior to the transplant experiment. Genotypes were randomly distributed within each plot (240 x 270 cm) and planted along a regulary spaced grid (30x30cm cell size) in spring 2015. Measurements will start in spring 2016, by which time plants are expected to have acclimatized to the local conditions. For the two subsiquent years, growth, survival, fitness, life cycle and herbivory consumption will be monitored for each transplant. On a weekly basis, we will record: 1) pictures of each transplant to determine

  9. Heavy metal tolerance in Agropyron repens (L. P. Bauv. populations from the Legnica copper smelter area, Lower Silesia

    Directory of Open Access Journals (Sweden)

    Teresa Brej


    Full Text Available The copper smelter "Legnica" is one of the oldest plants in Lower Silesia. Among the few weed species spontaneously migrating to the area around the emitter there is couch grass (Agropyron repens (L. P. Bauv.. The purpose of this study was to analyse whether the local couch grass populations, growing at various distances from the smelter, differ in tolerance to heavy metals occurring in this area. The populations were tested for tolerance to five metals (Cu, Zn, Pb, Cd, Ni using the root elongation method. The highest tolerance to Pb developed in two populations localized nearest the smelter. Similarly, all populations of couch grass from the vicinity of the smelter show a high tolerance to copper, particularly the plants from the most contaminated site. The IT for the latter population is almost 1509r, even at the highest dose of Cu. For Zn a nearing IT as for Cu was obtained. Comparing the shape of IT curves for Cd, special emphasis is put on the fact that a fixed tolerance to cadmium occurs only in the population localized closest to the emitter. The analysis of Ni-tolerance curves, of which the content in local soil is minimal, does not confirm the thesis on possibility of development of co-tolerance in the surveyed populations. It appeared that stress conditions existing near the smelter do not inhibit seed production in couch grass, but prevent a successful course of their germination on polluted soil. The improvement of soil even by 50% (addition of unpolluted soil does not improve the poor process of germination in couch grass growing nearest to the smelter. Of importance is the fact that the highest number of seeds germinated on their own, polluted soil. The need of metals' content for plant germination in populations most distant from the smelter is evidenced by an almost 30% reduction of germination ability of local seeds after addition of unpolluted soil. Another significant observation was the fact that, in spite of a poor

  10. Heavy metal tolerant halophilic bacteria from Vembanad Lake as possible source for bioremediation of lead and cadmium. (United States)

    Sowmya, M; Rejula, M P; Rejith, P G; Mohan, Mahesh; Karuppiah, Makesh; Hatha, A A Mohamed


    Microorganisms which can resist high concentration of toxic heavy metals are often considered as effective tools of bioremediation from such pollutants. In the present study, sediment samples from Vembanad Lake were screened for the presence of halophilic bacteria that are tolerant to heavy metals. A total of 35 bacterial strains belonging to different genera such as Alcaligenes, Vibrio, Kurthia, Staphylococcus and members of the family Enterobacteriaceae were isolated from 21 sediment samples during February to April, 2008. The salt tolerance and optimum salt concentrations of the isolates revealed that most of them were moderate halophiles followed by halotolerant and extremely halotolerant groups. The minimum inhibitory concentrations (MICs) against cadmium and lead for each isolate revealed that the isolates showed higher MIC against lead than cadmium. Based on the resistance limit concentration, most of them were more tolerant to lead than cadmium at all the three salt concentrations tested. Heavy metal removal efficiency of selected isolates showed a maximum reduction of 37 and 99% against cadmium and lead respectively. The study reveals the future prospects of halophilic microorganisms in the field of bioremediation.

  11. Allocation, stress tolerance and carbon transport in plants: how does phloem physiology affect plant ecology? (United States)

    Savage, Jessica A; Clearwater, Michael J; Haines, Dustin F; Klein, Tamir; Mencuccini, Maurizio; Sevanto, Sanna; Turgeon, Robert; Zhang, Cankui


    Despite the crucial role of carbon transport in whole plant physiology and its impact on plant-environment interactions and ecosystem function, relatively little research has tried to examine how phloem physiology impacts plant ecology. In this review, we highlight several areas of active research where inquiry into phloem physiology has increased our understanding of whole plant function and ecological processes. We consider how xylem-phloem interactions impact plant drought tolerance and reproduction, how phloem transport influences carbon allocation in trees and carbon cycling in ecosystems and how phloem function mediates plant relations with insects, pests, microbes and symbiotes. We argue that in spite of challenges that exist in studying phloem physiology, it is critical that we consider the role of this dynamic vascular system when examining the relationship between plants and their biotic and abiotic environment.

  12. Chitosan nanoparticles affect acid tolerance response in adhered cells of strpetococcus mutans

    DEFF Research Database (Denmark)

    Neilands, Julia; Sutherland, Duncan S; Resin, Anton


    In this study we evaluated the effect of chitosan nanoparticles on the acid tolerance response (ATR) of adhered Streptococcus mutans. An ATR was induced by exposing S. mutans to pH 5.5 for 2 h and confirmed by exposing the acid-adapted cells to pH 3.5 for 30 min, with the majority of cells...... appearing viable according to the LIVE/DEAD (R) technique. However, when chitosan nanoparticles were present during the exposure to pH 5.5, no ATR occurred as most cells appeared dead after the pH 3.5 shock. We conclude that the chitosan nanoparticles tested had the ability to hinder ATR induction...

  13. Green methods for preparing highly co2 selective and h2s tolerant metal organic frameworks

    KAUST Repository

    Eddaoudi, Mohamed


    A green route for preparing a metal organic framework include mixing metal precursor with a ligand precursor to form a solvent-free mixture; adding droplets of water to the mixture; heating the mixture at a first temperature after adding the water; and isolating the metal organic framework material including the metal and the ligand.

  14. How Environment Affects Galaxy Metallicity through Stripping and Formation History: Lessons from the Illustris Simulation

    CERN Document Server

    Genel, Shy


    Recent studies found higher galaxy metallicities in richer environments. It is not yet clear, however, whether metallicity-environment dependencies are merely an indirect consequence of environmentally-dependent formation histories, or of environment-related processes affecting metallicity directly. Here we present a first detailed study of metallicity-environment correlations in a cosmological hydrodynamical simulation, in particular the Illustris simulation. Illustris galaxies display similar relations to those observed. Utilizing knowledge of simulated formation histories, and leveraging the large simulation volume, we construct galaxy samples of satellites and centrals that are matched in formation histories. This allows us to find that ~1/3 of the metallicity-environment correlation is due to different formation histories in different environments. This is a combined effect of satellites (in particular in denser environments) having average lower z=0 star-formation rates (SFRs), and of their older stella...

  15. Physico-chemical characterization of a farmland affected by wastewater in relation to heavy metals

    Institute of Scientific and Technical Information of China (English)

    Emmanuel U. ONWEREMADU


    This study investigated selected properties of soils affected by wastewater and its relationship with some heavy metals. A free survey technique involving target sampling was used in siting soil profile pits. Soil samples were collected based on horizon differentiation and analyzed using routine and special analytical techniques. Soil data were subjected to correlation analysis using SAS program. Results show that all heavy metals studied had values above critical limits in the polluted soils using known standards and that these biotoxic metals decreased with soil depths. Highly significant (P=0.01 and 0.05) relationships were established between investigated heavy metals and some soil properties, especially soil pH and organic matter. Further studies involving more edaphic properties, biotoxic metals and their bioaccessibility in crops growing on wastewater soils will surely enhance knowledge and management of these highly anthropogenically influenced soils of the study site.

  16. Benzalkonium chloride and heavy-metal tolerance in Listeria monocytogenes from retail foods. (United States)

    Xu, Dongyang; Li, Yanli; Zahid, M Shamim Hasan; Yamasaki, Shinji; Shi, Lei; Li, Jian-rong; Yan, He


    Phenotypic and genotypic tolerance in 71 Listeria monocytogenes isolates from different varieties of foods to benzalkonium chloride (BC) and cadmium were investigated by susceptibility test and molecular methods. To investigate the role of efflux pumps in BC tolerance, reserpine, an efflux pump inhibitor, was added to the BC tolerant strains. Tolerance to BC and cadmium were 26.8% (19/71) and 49.3% (35/71) respectively. Strains with BC tolerance were significantly more frequent among those of serotype 4b (100%, 6/6) than among those of serotype 1/2a (or 3a) (13.5%, 5/37), which represent the predominant number of strains (52.1%, 37/71). Tolerance to cadmium was encountered among 62.2% (23/37) and 50.0% (3/6) of the serotype 1/2a (or 3a) and 4b strains, respectively, and among 19.0% (4/21) of the strains of the serotype 1/2c. All of the 10 (14.1%) isolates found to be BC and cadmium co-tolerance were isolated from raw meat or quick-frozen food made of wheat flour and rice. Five multi-drug resistant strains were tolerant to cadmium as well. Among 71 isolates examined, one contained qacA and three contained qacEΔ1-sul. To the best of our knowledge, this is the first detection of qacA and qacEΔ1-sul in L. monocytogenes, an indication of the possible horizontal transfer of the two genes. Addition of reserpine to the tolerant strains resulted in the loss of tolerance among seven out of 19 BC strains, suggesting a certain role the efflux pump played in mediating BC tolerance. Of the three distinct cadA types known to date in L. monocytogenes, the cadA1 and cadA2 genes were detected among 24 (33.8%) and three (4.2%) isolates respectively. The presence of cadA1 and cadA2 largely corresponded to the susceptibility phenotype. A subset (9/35 [25.7%]) of the cadmium-tolerant isolates lacked the known cadmium resistance determinants. These findings suggest that food products could act as a reservoir for L. monocytogenes harboring tolerance to BC and cadmium and will further

  17. Lead tolerance capacity of clinical bacterial isolates and change in their antibiotic susceptibility pattern after exposure to a heavy metal

    Directory of Open Access Journals (Sweden)

    Divya Garhwal


    Full Text Available Introduction: Heavy metal pollutions of soil and wastewater are a significant environmental problem as they are not degraded or destroyed. Several metal resistance mechanisms have been identified which is responsible for alteration of normal cell physiology leading to development of drug resistance in microorganisms. Heavy metals used in industry and in household products are, along with antibiotics, creating a selective pressure in the environment that leads to the mutations in microorganisms. The present study was carried out to study the heavy metal lead tolerance by bacteria and change in antibiotic-sensitivity pattern after its exposure. Materials and Methods: 30 clinical isolates from various samples received in the Department of Microbiology, Government Medical College, Surat, were included in the study. To check the lead tolerance capacity, isolates were exposed to graded concentration of lead nitrate by plate dilution method, starting from 50 up to 1000 μg/ml strength. Antibiotic susceptibility was performed by the Kirby Bauer disc diffusion method. A change in antibiotic susceptibility pattern was studied before and after lead exposure. Result: 30 clinical isolates were included in the study, 25 Gram negative (83.3% and 5 Gram positive (16.7%. MIC to lead was higher in Acinetobacter spp. and Pseudomonas spp. (600-1000 μg/ml as compared to E. coli, Klebsiella spp., S. aureus (50-150 μg/ml. Multiple antibiotic resistance indexes were changed significantly after lead exposure. Conclusion: Bacteria exposed to high levels of heavy metals in their environment have adapted to this stress by developing various resistance mechanism. Infection with antibiotic-resistant organisms create problem in treatment and management of patients. We should take efforts to prevent environmental pollution with such heavy metals and transmission of antibiotic-resistant microorganism from environment to health care set up.

  18. Isolation and characterization of a phosphate solubilizing heavy metal tolerant bacterium from River Ganga, West Bengal, India

    Directory of Open Access Journals (Sweden)

    Dipak Paul


    Full Text Available Phosphates solubilizing bacterial (PSB strains were isolated from the jute mill effluent discharge area of the Ganga river water at Bansberia, West Bengal, India. Experimental studies found that the strain KUPSB16 was effective in solubilization of phosphate with phosphate solubilization index (SI = 3.14 in Pikovskaya’s agar plates along with maximum solubilized phosphate production of 208.18 g mL-1 in broth culture. Highest drop in pH value was associated with maximum amount of phosphate solubilization by the PSB strain KUPSB16 where pH decreased to 3.53 from initial value of 7.0±0.2. The isolated PSB strains were tested for tolerance against four heavy metals such as cadmium (Cd, chromium (Cr, lead (Pb and zinc (Zn at concentrations 1-15 mM. The results showed that most of the PSB isolates grew well at low concentrations of heavy metals and their number gradually decreased as the concentration increased. Isolated PSB strain KUPSB16 was tested for its multiple metal resistances. Minimal inhibitory concentrations (MIC for Cd2+, Cr6+, Pb2+ and Zn2+ in tris-minimal broth medium were 4.2, 5.5, 3.6 and 9.5 mM respectively. The MIC values for the metals studied on agar medium was higher than in broth medium and ranged from 4.8-11.0 mM. The isolated bacterial strain KUPSB16 was subjected to morphological, physiological and biochemical characterization and identified as the species of the genus Bacillus. The phosphate solubilizing bacterium possessing the properties of multiple heavy metal tolerance in heavy metal contaminated areas might be exploited for bioremediation studies in future.

  19. Tolerance to metals and assessment of energy reserves in the polychaete Nereis diversicolor in clean and contaminated estuaries. (United States)

    Durou, C; Mouneyrac, C; Amiard-Triquet, C


    Estuaries are subject to anthropogenic activities. Because the intrasedimentary worm Nereis diversicolor has ecological characteristics and bioindicator abilities, its use was pertinent in investigating the concepts and cost of tolerance to heavy metals (Cd, Cu, Zn). In this context, two approaches were carried out, performing toxicity tests and estimating energy reserves (glycogen and lipids), in populations originating from a contaminated site (Seine estuary) compared with those from a clean site (Authie estuary). Mean lethal times (LT(50)s) of organisms exposed to zinc from the Seine estuary were higher than those from the Authie estuary, but not of organisms exposed to Cd or Cu. The influence of animal weight and salinity on the sensitivity of worms also was studied. The biggest worms were more tolerant to zinc than the smallest ones, and worms survived longer at a reduced salinity (15 per thousand). Concentrations of glycogen and lipids in each sampling season were higher in specimens from the Authie estuary than in worms from the Seine estuary. No influence of salinity on glycogen and lipid levels was observed. Glycogen concentrations were not influenced by the weight of specimens, whereas lipid concentrations were significantly and positively correlated with weight. In conclusion, worms from the Seine estuary exhibited tolerance to Zn, and the depletion of energy reserves observed in this population could be interpreted as a cost of tolerance.

  20. Deficiency of PdxR in Streptococcus mutans affects vitamin B6 metabolism, acid tolerance response and biofilm formation. (United States)

    Liao, S; Bitoun, J P; Nguyen, A H; Bozner, D; Yao, X; Wen, Z T


    Streptococcus mutans, a key etiological agent of the human dental caries, lives primarily on the tooth surface in tenacious biofilms. The SMU864 locus, designated pdxR, is predicted to encode a member of the novel MocR/GabR family proteins, which are featured with a winged helix DNA-binding N-terminal domain and a C-terminal domain highly homologous to the pyridoxal phosphate-dependent aspartate aminotransferases. A pdxR-deficient mutant, TW296, was constructed using allelic exchange. PdxR deficiency in S. mutans had little effect on cell morphology and growth when grown in brain heart infusion. However, when compared with its parent strain, UA159, the PdxR-deficient mutant displayed major defects in acid tolerance response and formed significantly fewer biofilms (P < 0.01). When analyzed by real-time polymerase chain reaction, PdxR deficiency was found to drastically reduce expression of an apparent operon encoding a pyridoxal kinase (SMU865) and a pyridoxal permease (SMU866) of the salvage pathway of vitamin B6 biosynthesis. In addition, PdxR deficiency also altered the expression of genes for ClpL protease, glucosyltransferase B and adhesin SpaP, which are known to play important roles in stress tolerance and biofilm formation. Consistently, PdxR-deficiency affected the growth of the deficient mutant when grown in defined medium with and without vitamin B6 . Further studies revealed that although S. mutans is known to require vitamin B6 to grow in defined medium, B6 vitamers, especially pyridoxal, were strongly inhibitory at millimolar concentrations, against S. mutans growth and biofilm formation. Our results suggest that PdxR in S. mutans plays an important role in regulation of vitamin B6 metabolism, acid tolerance response and biofilm formation.

  1. Salinity affects production and salt tolerance of dimorphic seeds of Suaeda salsa. (United States)

    Wang, Fengxia; Xu, Yan-Ge; Wang, Shuai; Shi, Weiwei; Liu, Ranran; Feng, Gu; Song, Jie


    The effect of salinity on brown seeds/black seeds ratio, seed weight, endogenous hormone concentrations, and germination of brown and black seeds in the euhalophyte Suaeda salsa was investigated. The brown seeds/black seeds ratio, seed weight of brown and black seeds and the content of protein increased at a concentration of 500 mM NaCl compared to low salt conditions (1 mM NaCl). The germination percentage and germination index of brown seeds from plants cultured in 500 mM NaCl were higher than those cultured in 1 mM NaCl, but it was not true for black seeds. The concentrations of IAA (indole-3-acetic acid), ZR (free zeatin riboside) and ABA (abscisic acid) in brown seeds were much greater than those in black seeds, but there were no differences in the level of GAs (gibberellic acid including GA1 and GA3) regardless of the degree of salinity. Salinity during plant culture increased the concentration of GAs, but salinity had no effect on the concentrations of the other three endogenous hormones in brown seeds. Salinity had no effect on the concentration of IAA but increased the concentrations of the other three endogenous hormones in black seeds. Accumulation of endogenous hormones at different concentrations of NaCl during plant growth may be related to seed development and to salt tolerance of brown and black S. salsa seeds. These characteristics may help the species to ensure seedling establishment and population succession in variable saline environments.

  2. Chromate tolerance and accumulation in Chlorella vulgaris L.: role of antioxidant enzymes and biochemical changes in detoxification of metals. (United States)

    Rai, U N; Singh, N K; Upadhyay, A K; Verma, S


    A concentration-dependent increase in activity of antioxidant enzymes (catalase, ascorbate peroxidase, glutathione, superoxide dismutase) and carotenoid, MDA level have been observed in the green alga Chlorella vulgaris following chromium exposure at different concentrations (0.01-100 μg ml(-1)). Simultaneously, decrease in growth rate, chlorophyll and protein contents was observed. In case of ascorbate peroxidase, glutathione peroxidase and superoxide dismutase a bell shaped dose response was evident, however, lipid peroxidation followed a linear relationship along with catalase activity, which could be used as biomarker of Cr toxicity and played important role in providing tolerance and subsequently, high accumulation potential of chromium in C. vulgaris. In present investigation, the green alga C. vulgaris respond better under chromium stress in terms of tolerance, growth and metal accumulating potential at higher concentration of Cr (VI) which could be employed in decontamination of chromium for environmental cleanup.

  3. Mixtures of herbicides and metals affect the redox system of honey bees. (United States)

    Jumarie, Catherine; Aras, Philippe; Boily, Monique


    The increasing loss of bee colonies in many countries has prompted a surge of studies on the factors affecting bee health. In North America, main crops such as maize and soybean are cultivated with extensive use of pesticides that may affect non-target organisms such as bees. Also, biosolids, used as a soil amendment, represent additional sources of metals in agroecosystems; however, there is no information about how these metals could affect the bees. In previous studies we investigated the effects of environmentally relevant doses of herbicides and metals, each individually, on caged honey bees. The present study aimed at investigating the effects of mixtures of herbicides (glyphosate and atrazine) and metals (cadmium and iron), as these mixtures represent more realistic exposure conditions. Levels of metal, vitamin E, carotenoids, retinaldehyde, at-retinol, retinoic acid isomers (9-cis RA, 13-cis RA, at-RA) and the metabolites 13-cis-4-oxo-RA and at-4-oxo-RA were measured in bees fed for 10 days with contaminated syrup. Mixtures of herbicides and cadmium that did not affect bee viability, lowered bee α- and β-carotenoid contents and increased 9-cis-RA as well as 13-cis-4-oxo-RA without modifying the levels of at-retinol. Bee treatment with either glyphosate, a combination of atrazine and cadmium, or mixtures of herbicides promoted lipid peroxidation. Iron was bioconcentrated in bees and led to high levels of lipid peroxidation. Metals also decreased zeaxanthin bee contents. These results show that mixtures of atrazine, glyphosate, cadmium and iron may affect different reactions occurring in the metabolic pathway of vitamin A in the honey bee.

  4. Tolerance of Grasses to Heavy Metals and Microbial Functional Diversity in Soils Contaminated with Copper Mine Tailings

    Institute of Scientific and Technical Information of China (English)

    TENG Ying; LUO Yong-Ming; HUANG Chang-Yong; LONG Jian; LI Zhen-Gao; P.CHRISTIE


    Copper (Cu) mine tallings,because of their high content of heavy metals,are usually hostile to plant colonization.A pot experiment was conducted to determine the tolerance of four forage grasses to heavy metals in Cu mine tailings and to examine the variation in the microbial functional diversity of soils from the tailing sites in southern China.All the four grass species survived on Cu mine tailings and Cu mine tailing-soil mixture.However,on pure mine tailings,the growth was minimal,whereas the growth was maximum for the control without mine railings.The tolerance of grasses to heavy metals followed the sequence: Paspalum notatum >Festuca arundinacea >Lolium perenne >Cynodon dactylon.The planting of forage grasses enhanced the soil microbial biomass.The Biolog data indicated that the soil microbial metabolic profile values (average well color development,community richness,and Shannon index) of the four forage grasses also followed the sequence: P.notatum > F.arundinacea > L.perenne > C.dactylon.Thus,P.notatum,under the experimental conditions of this study,may be considered as the preferred plant species for revegetation of Cu mine tailing areas.

  5. Variations in metal tolerance and accumulation in three hydroponically cultivated varieties of Salix integra treated with lead.

    Directory of Open Access Journals (Sweden)

    Shufeng Wang

    Full Text Available Willow species have been suggested for use in the remediation of contaminated soils due to their high biomass production, fast growth, and high accumulation of heavy metals. The tolerance and accumulation of metals may vary among willow species and varieties, and the assessment of this variability is vital for selecting willow species/varieties for phytoremediation applications. Here, we examined the variations in lead (Pb tolerance and accumulation of three cultivated varieties of Salix integra (Weishanhu, Yizhibi and Dahongtou, a shrub willow native to northeastern China, using hydroponic culture in a greenhouse. In general, the tolerance and accumulation of Pb varied among the three willow varieties depending on the Pb concentration. All three varieties had a high tolerance index (TI and EC50 value (the effective concentration of Pb in the nutrient solution that caused a 50% inhibition on biomass production, but a low translocation factor (TF, indicating that Pb sequestration is mainly restricted in the roots of S. integra. Among the three varieties, Dahogntou was more sensitive to the increased Pb concentration than the other two varieties, with the lowest EC50 and TI for root and above-ground tissues. In this respect, Weishanhu and Yizhibi were more suitable for phytostabilization of Pb-contaminated soils. However, our findings also indicated the importance of considering the toxicity symptoms when selecting willow varieties for the use of phytoremediation, since we also found that the three varieties revealed various toxicity symptoms of leaf wilting, chlorosis and inhibition of shoot and root growth under the higher Pb concentrations. Such symptoms could be considered as a supplementary index in screening tests.

  6. Exploring rhizosphere bacteria of Eichhornia crassipes for metal tolerance and biological activity

    Digital Repository Service at National Institute of Oceanography (India)

    PrabhaDevi; Gomez, S.; Ribeiro, M.; Deshpande, S.A; Singh, K.S.; DeSouza, L.

    With urbanization and rapid industrial progress, water bodies around the world are getting highly polluted with metals. Bacteria have evolved several mechanisms to adapt to heally metal contaminants thus representing a potential source...

  7. Gomphrena claussenii, the first South-American metallophyte species with indicator-like Zn and Cd accumulation and extreme metal tolerance

    NARCIS (Netherlands)

    Tomaz Villafort Carvalho, M.; Amaral, D.C.; Guilherme, L.R.; Aarts, M.G.M.


    Plant species with the capacity to tolerate heavy metals are potentially useful for phytoremediation since they have adapted to survive and reproduce under toxic conditions and to accumulate high metal concentrations. Gomphrena claussenii Moq., a South-American species belonging to the Amaranthaceae

  8. GOLDEN 2-LIKE transcription factors for chloroplast development affect ozone tolerance through the regulation of stomatal movement. (United States)

    Nagatoshi, Yukari; Mitsuda, Nobutaka; Hayashi, Maki; Inoue, Shin-Ichiro; Okuma, Eiji; Kubo, Akihiro; Murata, Yoshiyuki; Seo, Mitsunori; Saji, Hikaru; Kinoshita, Toshinori; Ohme-Takagi, Masaru


    Stomatal movements regulate gas exchange, thus directly affecting the efficiency of photosynthesis and the sensitivity of plants to air pollutants such as ozone. The GARP family transcription factors GOLDEN 2-LIKE1 (GLK1) and GLK2 have known functions in chloroplast development. Here, we show that Arabidopsis thaliana (A. thaliana) plants expressing the chimeric repressors for GLK1 and -2 (GLK1/2-SRDX) exhibited a closed-stomata phenotype and strong tolerance to ozone. By contrast, plants that overexpress GLK1/2 exhibited an open-stomata phenotype and higher sensitivity to ozone. The plants expressing GLK1-SRDX had reduced expression of the genes for inwardly rectifying K(+) (K(+) in) channels and reduced K(+) in channel activity. Abscisic acid treatment did not affect the stomatal phenotype of 35S:GLK1/2-SRDX plants or the transcriptional activity for K(+) in channel gene, indicating that GLK1/2 act independently of abscisic acid signaling. Our results indicate that GLK1/2 positively regulate the expression of genes for K(+) in channels and promote stomatal opening. Because the chimeric GLK1-SRDX repressor driven by a guard cell-specific promoter induced a closed-stomata phenotype without affecting chloroplast development in mesophyll cells, modulating GLK1/2 activity may provide an effective tool to control stomatal movements and thus to confer resistance to air pollutants.

  9. Performance Factors and Sulfur Tolerance of Metal Supported Solid Oxide Fuel Cells with Nanostructured Ni:GDC Infiltrated Anodes

    DEFF Research Database (Denmark)

    Nielsen, Jimmi; Persson, Åsa Helen; Sudireddy, Bhaskar Reddy;


    In recent years, there has been a growing interest in developing metal supported solid oxide fuel cells (MS-SOFCs). MS-SOFCs are interesting as they potentially offer some advantages compared to conventional electrode and electrolyte supported SOFCs, such as low materials cost, better thermal...... conductivity and ductility of the support. The two later aspects improve the shock resistance and lower internal gradients within the stacks. This enables fast start-up and provides higher tolerance towards operation under transient conditions that are particularly desirable for APU applications. Today...

  10. On Parameters Affecting Metal Flow and Friction in the Double Cup Extrusion Test

    DEFF Research Database (Denmark)

    Tan, Xincai; Bay, Niels; Zhang, Wenqi


    Friction and lubrication in metal-forming processes are usually evaluated by a process test with a friction-sensitive divided flow like the ring-compression test. Parameters affecting metal flow are not only friction, but also strain hardening, tool geometry etc. The current friction models applied...... model with constant absolute value excluding the influence of strain hardening on friction was adopted in FEM simulations, in order to more clearly study the individual influence of strain hardening and friction on the metal flow (upper and lower cup height ratio) without interference between the two...... parameters. The predicted results show a good agreement with the experimental data. The influence of material strain hardening. friction and tool geometry on the metal flow in the test has been investigated. By comparisons of the cup height ratio as a function of the punch travel estimated by experiments...

  11. Metal/metalloid fixation by litter during decomposition affected by silicon availability during plant growth. (United States)

    Schaller, Jörg


    Organic matter is known to accumulate high amounts of metals/metalloids, enhanced during the process of decomposition by heterotrophic biofilms (with high fixation capacity for metals/metalloids). The colonization by microbes and the decay rate of the organic matter depends on different litter properties. Main litter properties affecting the decomposition of organic matter such as the nutrient ratios and the content of cellulose, lignin and phenols are currently described to be changed by silicon availability. But less is known about the impact of silicon availability during plant growth on elemental fixation during decay. Hence, this research focuses on the impact of silicon availability during plant growth on fixation of 42 elements during litter decay, by controlling the litter properties. The results of this experiment are a significantly higher metal/metalloid accumulation during decomposition of plant litter grown under low silicon availability. This may be explained by the altered litter properties (mainly nutrient content) affecting the microbial decomposition of the litter, the microbial growth on the litter and possibly by the silicon double layer, which is evident in leaf litter with high silicon content and reduces the binding sites for metals/metalloids. Furthermore, this silicon double layer may also reduce the growing biofilm by reducing the availability of carbon compounds at the litter surface and has to be elucidated in further research. Hence, low silicon availability during plant growth enhances the metal/metalloid accumulation into plant litter during aquatic decomposition.

  12. Improved tolerance of maize (Zea mays L.) to heavy metals by colonization of a dark septate endophyte (DSE) Exophiala pisciphila. (United States)

    Li, T; Liu, M J; Zhang, X T; Zhang, H B; Sha, T; Zhao, Z W


    Dark septate endophytes (DSE) are ubiquitous and abundant in stressful environments including heavy metal (HM) stress. However, our knowledge about the roles of DSE in improving HM tolerance of their host plants is poor. In this study, maize (Zea mays L.) was inoculated with a HM tolerant DSE strain Exophiala pisciphila H93 in lead (Pb), zinc (Zn), and cadmium (Cd) contaminated soils. E. pisciphila H93 successfully colonized and formed typical DSE structures in the inoculated maize roots. Colonization of E. pisciphila H93 alleviated the deleterious effects of excessive HM supplements and promoted the growth of maize (roots and shoots) under HM stress conditions, though it significantly decreased the biomass of inoculated maize under no HM stress. Further analysis showed that the colonization of E. pisciphila H93 improved the tolerance of maize to HM by restricting the translocation of HM ions from roots to shoots. This study demonstrated that under higher HM stress, such a mutual symbiosis between E. pisciphila and its host (maize) may be an efficient strategy to survive in the stressful environments.

  13. Bioremediation of high molecular weight polyaromatic hydrocarbons co-contaminated with metals in liquid and soil slurries by metal tolerant PAHs degrading bacterial consortium. (United States)

    Thavamani, Palanisami; Megharaj, Mallavarapu; Naidu, Ravi


    Bioremediation of polyaromatic hydrocarbons (PAH) contaminated soils in the presence of heavy metals have proved to be difficult and often challenging due to the ability of toxic metals to inhibit PAH degradation by bacteria. In this study, a mixed bacterial culture designated as consortium-5 was isolated from a former manufactured gas plant (MGP) site. The ability of this consortium to utilise HMW PAHs such as pyrene and BaP as a sole carbon source in the presence of toxic metal Cd was demonstrated. Furthermore, this consortium has proven to be effective in degradation of HMW PAHs even from the real long term contaminated MGP soil. Thus, the results of this study demonstrate the great potential of this consortium for field scale bioremediation of PAHs in long term mix contaminated soils such as MGP sites. To our knowledge this is the first study to isolate and characterize metal tolerant HMW PAH degrading bacterial consortium which shows great potential in bioremediation of mixed contaminated soils such as MGP.

  14. Plant growth promotion, metabolite production and metal tolerance of dark septate endophytes isolated from metal-polluted poplar phytomanagement sites. (United States)

    Berthelot, Charlotte; Leyval, Corinne; Foulon, Julie; Chalot, Michel; Blaudez, Damien


    Numerous studies address the distribution and the diversity of dark septate endophytes (DSEs) in the literature, but little is known about their ecological role and their effect on host plants, especially in metal-polluted soils. Seven DSE strains belonging to Cadophora, Leptodontidium, Phialophora and Phialocephala were isolated from roots of poplar trees from metal-polluted sites. All strains developed on a wide range of carbohydrates, including cell-wall-related compounds. The strains evenly colonized birch, eucalyptus and ryegrass roots in re-synthesis experiments. Root and shoot growth promotion was observed and was both plant and strain dependent. Two Phialophora and Leptodontidium strains particularly improved plant growth. However, there was no correlation between the level of root colonization by DSEs and the intensity of growth promotion. All strains produced auxin and six also stimulated plant growth through the release of volatile organic compounds (VOCs). SPME-GC/MS analyses revealed four major VOCs emitted by Cadophora and Leptodontidium The strains exhibited growth at high concentrations of several metals. The ability of metal-resistant DSE strains to produce both soluble and volatile compounds for plant growth promotion indicates interesting microbial resources with high potential to support sustainable production of bioenergy crops within the context of the phytomanagement of metal-contaminated sites.

  15. Plant-driven removal of heavy metals from soil: uptake, translocation, tolerance mechanism, challenges, and future perspectives. (United States)

    Thakur, Sveta; Singh, Lakhveer; Wahid, Zularisam Ab; Siddiqui, Muhammad Faisal; Atnaw, Samson Mekbib; Din, Mohd Fadhil Md


    Increasing heavy metal (HM) concentrations in the soil have become a significant problem in the modern industrialized world due to several anthropogenic activities. Heavy metals (HMs) are non-biodegradable and have long biological half lives; thus, once entered in food chain, their concentrations keep on increasing through biomagnification. The increased concentrations of heavy metals ultimately pose threat on human life also. The one captivating solution for this problem is to use green plants for HM removal from soil and render it harmless and reusable. Although this green technology called phytoremediation has many advantages over conventional methods of HM removal from soils, there are also many challenges that need to be addressed before making this technique practically feasible and useful on a large scale. In this review, we discuss the mechanisms of HM uptake, transport, and plant tolerance mechanisms to cope with increased HM concentrations. This review article also comprehensively discusses the advantages, major challenges, and future perspectives of phytoremediation of heavy metals from the soil.

  16. Different behaviours in phytoremediation capacity of two heavy metal tolerant poplar clones in relation to iron and other trace elements. (United States)

    Baldantoni, Daniela; Cicatelli, Angela; Bellino, Alessandro; Castiglione, Stefano


    Plant biodiversity and intra-population genetic variability have not yet been properly exploited in the framework of phytoremediation and soil reclamation. For this reason, iron and other metal accumulation capacity of two Cu and Zn tolerant poplar clones, namely AL22 (Populus alba L.) and N12 (Populus nigra L.), was investigated in a pot experiment. Cuttings of the two clones were planted in iron rich soil collected from an urban-industrial area. Concentrations of Cd, Cu, Fe, Pb and Zn were analysed in leaves (at different times), as well as in stems and in roots (at the end of the experiment), both in control plants and in plants grown on a soil whose Fe availability was artificially enhanced. Results showed that Cd and Zn were preferentially accumulated in leaves, whereas Cu, Fe and Pb were mainly accumulated in roots. The main differences in metal accumulation between clones were related to Cd (about tenfold higher concentrations in N12) and Cu (higher concentrations in AL22). Once soil Fe availability was enhanced, the uptake and accumulation of all metals declined, with the exception of Fe at the first sampling time in AL22 leaves. The different behaviour of the two poplar clones suggests that a thoughtful choice should be made for their use in relation to soil heavy metal remediation.

  17. The addition of organic carbon and nitrate affects reactive transport of heavy metals in sandy aquifers

    KAUST Repository

    Satyawali, Yamini


    Organic carbon introduction in the soil to initiate remedial measures, nitrate infiltration due to agricultural practices or sulphate intrusion owing to industrial usage can influence the redox conditions and pH, thus affecting the mobility of heavy metals in soil and groundwater. This study reports the fate of Zn and Cd in sandy aquifers under a variety of plausible in-situ redox conditions that were induced by introduction of carbon and various electron acceptors in column experiments. Up to 100% Zn and Cd removal (from the liquid phase) was observed in all the four columns, however the mechanisms were different. Metal removal in column K1 (containing sulphate), was attributed to biological sulphate reduction and subsequent metal precipitation (as sulphides). In the presence of both nitrate and sulphate (K2), the former dominated the process, precipitating the heavy metals as hydroxides and/or carbonates. In the presence of sulphate, nitrate and supplemental iron (Fe(OH)3) (K3), metal removal was also due to precipitation as hydroxides and/or carbonates. In abiotic column, K4, (with supplemental iron (Fe(OH)3), but no nitrate), cation exchange with soil led to metal removal. The results obtained were modeled using the reactive transport model PHREEQC-2 to elucidate governing processes and to evaluate scenarios of organic carbon, sulphate and nitrate inputs. © 2010 Elsevier B.V.

  18. CorA affects tolerance of Escherichia coli and Salmonella enterica serovar Typhimurium to the lactoperoxidase enzyme system but not to other forms of oxidative stress. (United States)

    Sermon, Jan; Wevers, Eva M-R P; Jansen, Leentje; De Spiegeleer, Philipp; Vanoirbeek, Kristof; Aertsen, Abram; Michiels, Chris W


    The enzyme lactoperoxidase is part of the innate immune system in vertebrates and owes its antimicrobial activity to the formation of oxidative reaction products from various substrates. In a previous study, we have reported that, with thiocyanate as a substrate, the lactoperoxidase system elicits a distinct stress response in Escherichia coli MG1655. This response is different from but partly overlapping with the stress responses to hydrogen peroxide and to superoxide. In the current work, we constructed knockouts in 10 lactoperoxidase system-inducible genes to investigate their role in the tolerance of E. coli MG1655 to this antimicrobial system. Five mutations resulted in a slightly increased sensitivity, but one mutation (corA) caused hypersensitivity to the lactoperoxidase system. This hypersensitive phenotype was specific to the lactoperoxidase system, since neither the sensitivity to hydrogen peroxide nor to the superoxide generator plumbagin was affected in the corA mutant. Salmonella enterica serovar Typhimurium corA had a similar phenotype. Although corA encodes an Mg2+ transporter and at least three other inducible open reading frames belonged to the Mg2+ regulon, repression of the Mg stimulon by Mg2+ did not change the lactoperoxidase sensitivity of either the wild-type or corA mutant. Prior exposure to 0.3 mM Ni2+, which is also transported by CorA, strongly sensitized MG1655 but not the corA mutant to the lactoperoxidase system. Furthermore, this Ni2+-dependent sensitization was suppressed by the CorA-specific inhibitor Co(III) hexaammine. These results indicate that CorA affects the lactoperoxidase sensitivity of E. coli by modulating the cytoplasmic concentrations of transition metals that enhance the toxicity of the lactoperoxidase system.

  19. Rhizobium leguminosarum bv. viciae populations in soils with increasing heavy metal contamination: abundance, plasmid profiles, diversity and metal tolerance

    NARCIS (Netherlands)

    Lakzian, A.; Murphy, P.; Turner, A.; Beynon, J.L.; Giller, K.E.


    Populations of Rhizobium leguminosarum bv. viciae were investigated from plots of a long-term sewage sludge experiment in Braunschweig, Germany, which represented a gradient of increasing metal contamination. The number of R. leguminosarum bv. viciae decreased from 105 cells g¿1 soil in uncontaminat

  20. Heat-affected zone of metals ablated with femtosecond laser pulses (United States)

    Hirayama, Yoichi; Obara, Minoru


    The melted area is found on the surface ablated by nanosecond and picosecond laser pulses. However, the heat effect is little on the ablated surface in the case of femtosecond laser due to non-thermal ablation process. Heat-affected zone of metallic bulk crystal ablated with femtosecond Ti:sapphire laser pulses is experimentally studied. As a result of XRD (X-ray diffraction) measurements, the XRD peak signal of the area ablated with Ti:sapphire laser becomes smaller than that of the crystalline metal sample. While the crystallinity of the metal sample is crystalline before the laser ablation, the crystallinity in the ablated area is partially changed into the amorphous form. Because the residual pulse energy that is not used for the ablation process remains, leading to the formation of thin layer of melt phase. The melt layer is abruptly cooled down not to be re-crystallized, but to transform into the amorphous form. It is evident that the area ablated with femtosecond laser is changed into the amorphous metal. Additionally XRD measurements and AR+ etching are performed alternately to measure the thickness of the amorphous layer. In the case of iron, the thickness is measured to be 1 μm approximately, therefore heat-affected zone is quite small.

  1. Die Radius Affecting Sheet Metal Extrusion Quality for Fine Blanking Process

    Directory of Open Access Journals (Sweden)

    Chatkaew Suriyapha


    Full Text Available Problem statement: Sheet metal extrusion is a process in which the punch penetrates one surface of the sheet metal material to cause it to extrude and flow toward the outlet of the die. Therefore, the process can invent different thickness of sheet metal work piece. From these advantages on the sheet metal extrusion, nowadays, it is generally used in many manufacturing of industrial elements fields. The Sheet Metal Extrusions in Fine Blanking (SME-FB advantages, over a conventional extrusion, are possible due to a blank holder force, a counterpunch force and a large die radius. However, the selection on those parameter values affects on the material flow and the surface quality on the extrusion parts also. Namely, it causes the crack surface and shrinkage failure which are the general problems in the SME-FB. Approach: Objective of this research was to study the effect of die radius on the SME-FB surface which investigated the formation of the failure defection with respect to the several die radiuses by using the Finite Element Method (FEM. Results: From the results, it indicated that applying the small die radius caused the material flow difficult resulting in the decreasing of smooth surface. Vice versa, in the case of large die radius, the material flow easy is resulting in the increasing of smooth surface. Conclusion: The FEM simulation results of a larger die radius will cause the residual stress at work piece.

  2. Pollution and pollution tolerance in the case of heavy metals; Schadstoffbelastung und -belastbarkeit. Schwermetalle

    Energy Technology Data Exchange (ETDEWEB)

    Kretschmer, H.; Neumann, A.; Surkus, A.E. [Rostock Univ. (Germany). Inst. fuer Bodenkunde


    Urban soils often have high concentrations of heavy metals. This is particularly true of the technogenic substrates often found in cities and industrial and trading estates. The aim of the present project was therefore to mitigate the deficits of our present knowledge on problems relating to heavy metals in technogenic substrates. The studies presented in the following were carried out in pursuit of the following tasks: determination of the total concentration and mobility of the elements Cu, Pb, Cd, Zn, and Ni in 11 lead soil profiles from technogenic substrates in Rostock, Kiel, Eckernfjoerde and Halle/Saale; study of the dependence of heavy metal mobility on different soil characteristics (e.g. pH, clay, organic carbon, and total heavy metal content); recording of adsorption isotherms characterising the sorption and desorption behaviour of heavy metals; estimation of the heavy metal binding capacity of technogenic substrates following the method quoted by DVWK (1988) for heavy metals; and performance of percolation experiments on soil columns for deriving material transport parameters and of model calculations on heavy metal migration. [Deutsch] Urbane Boeden, besonders die in Staedten, Industrie- und Gewerbegebieten verbreitet lagernden technogenen Substrate, weisen oft hohe Schwermetallgehalte auf. Ziel dieses Projektes ist daher, Erkenntnisdefizite zur Schwermetallproblematik technogener Substrate zu verringern. Den nachfolgend dargestellten Untersuchungen liegt folgende Aufgabenstellung zugrunde: - Bestimmung der Gesamtgehalte und Mobilitaeten der Elemente Cu, Pb, Cd, Zn und Ni an 11 Leitprofilen aus technogenen Substraten in Rostock, Kiel, Eckernfoerde und Halle/Saale, - Untersuchung der Abhaengigkeit der Schwermetallmobilitaet von verschiedenen Bodenkennwerten (pH-Wert, Ton-, Corg-, Kalkgehalt, KAK, Schwermetall-Gesamtgehalt), - Aufnahme von Adsorptionsisothermen zur Kennzeichnung des Sorptions- und Desorptionsverhaltens von Schwermetallen, - Schaetzung

  3. Antimicrobial resistance and its association with tolerance to heavy metals in agriculture production. (United States)

    Yu, Zhongyi; Gunn, Lynda; Wall, Patrick; Fanning, Séamus


    Antimicrobial resistance is a recognized public health challenge that since its emergence limits the therapeutic options available to veterinarians and clinicians alike, when treatment is warranted. This development is further compounded by the paucity of new antibiotics. The agri-food industry benefits from the availability of antimicrobial compounds for food-animal production and crop protection. Nonetheless, their improper use can result in the selection for bacteria that are phenotypically resistant to these compounds. Another class of agents used in agriculture includes various cationic metals that can be included in animal diets as nutritional supplements or spread on pastures to support crop growth and protection. Heavy metals, in particular, are giving rise to concerns among public health professionals, as they can persist in the environment remaining stable for prolonged periods. Moreover, bacteria can also exhibit resistance to these chemical elements and the genes encoding this phenotype can be physically localized to plasmids that may also contain one or more antimicrobial resistance-encoding gene(s). This paper reviews our current understanding of the role that bacteria play in expressing resistance to heavy metals. It will describe how heavy metals are used in agri-food production, and explore evidence available to link resistance to heavy metals and antimicrobial compounds. In addition, possible solutions to reduce the impact of heavy metal resistance are also discussed, including using organic minerals and reducing the level of trace minerals in animal feed rations.

  4. Changes in the salinity tolerance of sweet pepper plants as affected by nitrogen form and high CO2 concentration. (United States)

    Piñero, María C; Pérez-Jiménez, Margarita; López-Marín, Josefa; Del Amor, Francisco M


    The assimilation and availability of nitrogen in its different forms can significantly affect the response of primary productivity under the current atmospheric alteration and soil degradation. An elevated CO2 concentration (e[CO2]) triggers changes in the efficiency and efficacy of photosynthetic processes, water use and product yield, the plant response to stress being altered with respect to ambient CO2 conditions (a[CO2]). Additionally, NH4(+) has been related to improved plant responses to stress, considering both energy efficiency in N-assimilation and the overcoming of the inhibition of photorespiration at e[CO2]. Therefore, the aim of this work was to determine the response of sweet pepper plants (Capsicum annuum L.) receiving an additional supply of NH4(+) (90/10 NO3(-)/NH4(+)) to salinity stress (60mM NaCl) under a[CO2] (400μmolmol(-1)) or e[CO2] (800μmolmol(-1)). Salt-stressed plants grown at e[CO2] showed DW accumulation similar to that of the non-stressed plants at a[CO2]. The supply of NH4(+) reduced growth at e[CO2] when salinity was imposed. Moreover, NH4(+) differentially affected the stomatal conductance and water use efficiency and the leaf Cl(-), K(+), and Na(+) concentrations, but the extent of the effects was influenced by the [CO2]. An antioxidant-related response was prompted by salinity, the total phenolics and proline concentrations being reduced by NH4(+) at e[CO2]. Our results show that the effect of NH4(+) on plant salinity tolerance should be globally re-evaluated as e[CO2] can significantly alter the response, when compared with previous studies at a[CO2].

  5. Optimization of physical factors affecting the production of thermo-stable organic solvent-tolerant protease from a newly isolated halo tolerant Bacillus subtilis strain Rand

    Directory of Open Access Journals (Sweden)

    Salleh Abu


    Full Text Available Abstract Background Many researchers have reported on the optimization of protease production; nevertheless, only a few have reported on the optimization of the production of organic solvent-tolerant proteases. Ironically, none has reported on thermostable organic solvent-tolerant protease to date. The aim of this study was to isolate the thermostable organic solvent-tolerant protease and identify the culture conditions which support its production. The bacteria of genus Bacillus are active producers of extra-cellular proteases, and the thermostability of enzyme production by Bacillus species has been well-studied by a number of researchers. In the present study, the Bacillus subtilis strain Rand was isolated from the contaminated soil found in Port Dickson, Malaysia. Results A thermostable organic solvent-tolerant protease producer had been identified as Bacillus subtilis strain Rand, based on the 16S rRNA analysis conducted, as well as the morphological characteristics and biochemical properties. The production of the thermostable organic solvent-tolerant protease was optimized by varying various physical culture conditions. Inoculation with 5.0% (v/v of (AB600 = 0.5 inoculum size, in a culture medium (pH 7.0 and incubated for 24 h at 37°C with 200 rpm shaking, was the best culture condition which resulted in the maximum growth and production of protease (444.7 U/ml; 4042.4 U/mg. The Rand protease was not only stable in the presence of organic solvents, but it also exhibited a higher activity than in the absence of organic solvent, except for pyridine which inhibited the protease activity. The enzyme retained 100, 99 and 80% of its initial activity, after the heat treatment for 30 min at 50, 55, and 60°C, respectively. Conclusion Strain Rand has been found to be able to secrete extra-cellular thermostable organic solvent-tolerant protease into the culture medium. The protease exhibited a remarkable stability towards temperature and organic

  6. Metal-tolerant PAH-degrading bacteria: development of suitable test medium and effect of cadmium and its availability on PAH biodegradation. (United States)

    Thavamani, Palanisami; Megharaj, Mallavarapu; Naidu, Ravi


    The use of metal-tolerant polyaromatic hydrocarbon (PAH)-degrading bacteria is viable for mitigating metal inhibition of organic compound biodegradation in the remediation of mixed contaminated sites. Many microbial growth media used for toxicity testing contain high concentrations of metal-binding components such as phosphates that can reduce solution-phase metal concentrations thereby underestimate the real toxicity. In this study, we isolated two PAHs-degrading bacterial consortia from long-term mixed contaminated soils. We have developed a new mineral medium by optimising the concentrations of medium components to allow the bacterial growth and at the same time maintain high bioavailable metal (Cd(2+) as a model metal) in the medium. This medium has more than 60 % Cd as Cd(2+) at pH 6.5 as measured by an ion selective electrode and visual MINTEQ model. The Cd-tolerant patterns of the consortia were tested and minimum inhibitory concentration (MIC) derived. The consortium-5 had the highest MIC of 5 mg l(-1) Cd followed by consortium-9. Both cultures were able to completely metabolise 200 mg l(-1) phenanthrene in less than 4 days in the presence of 5 mg l(-1) Cd. The isolated metal-tolerant PAH-degrading bacterial cultures have great potential for bioremediation of mixed contaminated soils.

  7. Large-scale biotic interaction effects - tree cover interacts with shade toler-ance to affect distribution patterns of herb and shrub species across the Alps

    DEFF Research Database (Denmark)

    Nieto-Lugilde, Diego; Lenoir, Jonathan; Abdulhak, Sylvain;


    distributions has scarcely been investigated. Here, we used species distribution modeling (SDM) to assess the effect of tree cover on the elevational range limits of 1,378 herb and shrub species across the Alps, based on 18,798 vegetation plots. We hypothesize that tree cover will have a negative effect...... on the occurrence on light-demanding species via size-asymmetric competition for light, but a facilitative effect on shade-tolerant species. In order to compare the relative importance of tree cover, four models with different combinations of variables (climate, soil and tree cover) were run for each species. Then......, we simulated a removal experiment by comparing the elevational distribution of each species under high and low tree cover. Tree cover improved model performances and species’ response curves to a tree cover gradient varied depending on their shade tolerance, supporting the hypothesized antagonistic...

  8. Responses and acclimation of Chinese cork oak (Quercus variabilis Bl.) to metal stress: the inducible antimony tolerance in oak trees. (United States)

    Zhao, Xiulian; Zheng, Lingyu; Xia, Xinli; Yin, Weilun; Lei, Jingpin; Shi, Shengqing; Shi, Xiang; Li, Huiqing; Li, Qinghe; Wei, Yuan; Chang, Ermei; Jiang, Zeping; Liu, Jianfeng


    Antimony (Sb) pollution has become a pressing environmental problem in recent years. Trees have been proven to have great potential for the feasible phytomanagement; however, little is known about Sb retention and tolerance in trees. The Chinese cork oak (Quercus variabilis Bl.) is known to be capable of growth in soils containing high concentrations of Sb. This study explored in detail the retention and acclimation of Q. variabilis under moderate and high external Sb levels. Results revealed that Q. variabilis could tolerate and accumulate high Sb (1623.39 mg kg(-1) DW) in roots. Dynamics of Sb retention in leaves, stems, and roots of Q. variabilis were different. Leaf Sb remained at a certain level for several weeks, while in roots and stems, Sb concentrations continued to increase. Sb damaged tree's PSII reaction cores but elicited defense mechanism at the donor side of PSII. It affected the electron transport flow after QA (-) more strongly than the oxygen-evolving complex and light-harvesting pigment-protein complex II. Sb also decreased leaf chlorophyll concentrations and therefore inhibited plant growth. During acclimation to Sb toxicity, Sb concentrations in leaves, stems, and roots decreased, with photosynthetic activity and pigments recovering to normal levels by the end of the experiment. These findings suggest that Sb tolerance in Q. variabilis is inducible. Acclimation seems to be related to homeostasis of Sb in plants. Results of this study can provide useful information for trees breeding and selection of Sb phytomanagement strategies, exploiting the established ability of Q. variabilis to transport, delocalize in the leaves, and tolerate Sb pollutions.

  9. Patients' tolerance of bimanual lid retraction versus a metal speculum for intravitreal injections

    Directory of Open Access Journals (Sweden)

    Alattas K


    Full Text Available Khadijah Alattas Department of Ophthalmology, College of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia Objective: To compare patients’ acceptance of and correlate their pain level for bimanual versus metal speculum fixation in intravitreal injections. Design: Prospective analysis. Participants: Seventy-three eyes of 56 patients. Methods: A questionnaire indicating patients’ discomfort and pain grading immediately after intravitreal injections using either bimanual fixation or metal speculum fixation (Barraquer Wire Speculum. Results: Fifty-six patients who underwent intravitreal injections were enrolled in this study for various conditions. Patients’ overall pain and discomfort were as follows, right eye – bimanual was 0.3 on our grading scale with a standard deviation of 0.54, right eye – metal was 1.6 on our grading scale with a standard deviation of 1.5, left eye – bimanual was 0.41 on our grading scale with a standard deviation of 0.87, and left eye – metal was 1.91 on our grading scale with a standard deviation of 1.14 (P=0.003. Conclusion: Patients who underwent bimanual fixation had a much more comfortable experience with less pain in comparison to patients who underwent metal speculum fixation. Keywords: AMD, diabetic retionpathy, Avastin, eye injection

  10. Metals other than uranium affected microbial community composition in a historical uranium-mining site. (United States)

    Sitte, Jana; Löffler, Sylvia; Burkhardt, Eva-Maria; Goldfarb, Katherine C; Büchel, Georg; Hazen, Terry C; Küsel, Kirsten


    To understand the links between the long-term impact of uranium and other metals on microbial community composition, ground- and surface water-influenced soils varying greatly in uranium and metal concentrations were investigated at the former uranium-mining district in Ronneburg, Germany. A soil-based 16S PhyloChip approach revealed 2358 bacterial and 35 archaeal operational taxonomic units (OTU) within diverse phylogenetic groups with higher OTU numbers than at other uranium-contaminated sites, e.g., at Oak Ridge. Iron- and sulfate-reducing bacteria (FeRB and SRB), which have the potential to attenuate uranium and other metals by the enzymatic and/or abiotic reduction of metal ions, were found at all sites. Although soil concentrations of solid-phase uranium were high, ranging from 5 to 1569 μg·g (dry weight) soil(-1), redundancy analysis (RDA) and forward selection indicated that neither total nor bio-available uranium concentrations contributed significantly to the observed OTU distribution. Instead, microbial community composition appeared to be influenced more by redox potential. Bacterial communities were also influenced by bio-available manganese and total cobalt and cadmium concentrations. Bio-available cadmium impacted FeRB distribution while bio-available manganese and copper as well as solid-phase zinc concentrations in the soil affected SRB composition. Archaeal communities were influenced by the bio-available lead as well as total zinc and cobalt concentrations. These results suggest that (i) microbial richness was not impacted by heavy metals and radionuclides and that (ii) redox potential and secondary metal contaminants had the strongest effect on microbial community composition, as opposed to uranium, the primary source of contamination.

  11. Assessment of heavy metal tolerance and hexavalent chromium reducing potential of Corynebacterium paurometabolum SKPD 1204 isolated from chromite mine seepage

    Directory of Open Access Journals (Sweden)

    Amal Kanti Paul


    Full Text Available Corynebacterium paurometabolum SKPD 1204 (MTCC 8730, a heavy metal tolerant and chromate reducing bacterium isolated from chromite mine seepage of Odisha, India has been evaluated for chromate reduction under batch culture. The isolate was found to tolerate metals like Co(II, Cu(II, Ni(II, Mn(II, Zn(II, Fe(III and Hg(II along with Cr(VI and was resistant to different antibiotics as evaluated by disc-diffusion method. The isolate, SKPD 1204 was found to reduce 62.5% of 2 mM Cr(VI in Vogel Bonner broth within 8 days of incubation. Chromate reduction capability of SKPD 1204 decreased with increase in Cr(VI concentration, but increased with increase in cell density and attained its maximum at 1010 cells/mL. Chromate reducing efficiency of SKPD 1204 was promoted in the presence of glycerol and glucose, while the highest reduction was recorded at pH 7.0 and 35 °C. The reduction process was inhibited by divalent cations Zn(II, Cd(II, Cu(II, and Ni(II, but not by Mn(II. Anions like nitrate, phosphate, sulphate and sulphite was found to be inhibitory to the process of Cr(VI reduction. Similarly, sodium fluoride, carbonyl cyanide m-chlorophenylhydrazone, sodium azide and N, N,-Di cyclohexyl carboiimide were inhibitory to chromate reduction, while 2,4-dinitrophenol appeared to be neither promotive nor inhibitory to the process.

  12. 香蒲植物对重金属耐性的研究进展%Advance of Cattail Plant Tolerance to Heavy Metals

    Institute of Scientific and Technical Information of China (English)



    Based on the introduction of damage of heavy metal pollution to plants and tolerance of plants to heavy metal contamination, this paper reviews the accumulation and tolerance of heavy metals in cattail plants to explore the new environmental application of cattail plants and offer new material and scientific basis for the phytoremediation of heavy metal contaminated water body and soil. Results indicate that several plants possess tolerance to heavy metal such as root accumulation, cell wall combination and vacuole compartment of heavy metals;cattail is a suitable plant for phytoremediation of environment contaminated by heavy metals due to its fast reproduction, big biomass, and strong tolerance to heavy metals.%在概述重金属污染对植物的影响与植物对重金属的耐性研究概况的基础上,综述香蒲植物对重金属的累积和耐性特征,旨在充分挖掘香蒲植物的环保新用途,为水土重金属污染的植物修复提供科学依据。研究结果表明,一些植物对重金属具有根系累积、细胞壁结合、液泡区隔化以及抗氧化等耐性机制;香蒲植物生长繁殖快,生物量大,对重金属耐性较强,根系累积重金属量较大,是重金属污染植物修复的适合物种。

  13. Enhanced tolerance and accumulation of heavy metal ions by engineered Escherichia coli expressing Pyrus calleryana phytochelatin synthase. (United States)

    Li, Hui; Cong, Yu; Lin, Jing; Chang, Youhong


    Contamination by heavy metals is a major environmental problem worldwide and microbial bioremediation is an efficient method for removing this type of pollution. The plant enzymephytochelatin synthase (PCS, also known as glutathione g-glutamylcysteinyltransferase, EC2.3.2.15) involved in the synthesis of phytochelatins (PCs), which are metal-binding cysteine-rich peptides, has a major role in the detoxification of heavy metals in plants. Expression of the PcPCS1 gene from the bean pear (Pyrus calleryana Dcne.) was induced after cadmium and copper treatments. However, functional analysis of this gene in vivo has not been reported. And it is or not suitable for bioremediation also needs to be assessed. In this study, we found Escherichia coli with over-expressed PcPCS1 had enhanced tolerance to cadmium, copper, sodium, and mercury. E. colicells transformed with pPcPCS1 was found to survive in solid M9 medium containing 2.0 mM Cd(2+), 4.0 mM Cu(2+). 4.5% (w/v) Na+, or 200 μ MHg(2+). Moreover, the growth curve showed 1.5 mM Cd(2+), 2.5 mM Cu(2+), 3.5% (w/v) Naþ, and 100 μ MHg(2+) had no effect on the growth of the E. coli cells transformed with pPcPCS1. Also, we found the contents of PCs and the accumulation of cadmium,copper, sodium, and mercury ions were enhanced in the recombinant E. coli strain Rosetta(TM) (DE3).These results suggested the PcPCS1 gene might be a candidate for heavy metal bioremediation via recombinant bacteria.

  14. Heavy metal ions affecting the removal of polycyclic aromatic hydrocarbons by fungi with heavy-metal resistance. (United States)

    Ma, Xiao-Kui; Ling Wu, Ling; Fam, Hala


    The co-occurrence of polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs) is very common in contaminated environments. It is of paramount importance and great challenge to exploit a bioremediation to remove PAHs in these environments with combined pollution. We approached this question by probing the influence of HMs coexisting with PAHs on the removal of PAHs by Acremonium sp. P0997 possessing metal resistance. A removal capability for naphthalene, fluorene, phenanthrene, anthracene, and fluoranthenepresentalone (98.6, 99.3, 89.9, 60.4, and 70 %, respectively) and in a mixture (96.9, 71.8, 67.0, 85.0, and 87.9 %, respectively) was achieved in mineral culture inoculated with Acremonium sp. P0997, and this strain also displayed high resistance to the individual HMs (Mn(2+), Fe(2+), Zn(2+), Cu(2+), Al(3+), and Pb(2+)). The removal of individual PAHs existing in a mixture was differently affected by the separately tested HMs. Cu(2+)enhanced the partition process of anthracene to dead or alive mycelia and the contribution of the biosorption by this strain but imposed a little negative influence on the contribution of biodegradation to the total removal of anthracene individually in a culture. However, Mn(2+) had an inhibitory effect on the partition process of anthracene to dead or alive mycelia and decreased the contributions of both biosorption and biodegradation to the total anthracene removal. This work showcased the value of fungi in bioremediation for the environments with combined pollution, and the findings have major implications for the bioremediation of organic pollutants in metal-organic mixed contaminated sites.

  15. Heavy metal phytoextraction by Sedum alfredii is affected by continual clipping and phosphorus fertilization amendment

    Institute of Scientific and Technical Information of China (English)

    Huagang Huang; Tingqiang Li; D.K.Gupta; Zhenli He; Xiao-e Yang; Bingnan Ni; Mao Li


    Improving the efficacy of phytoextraction is critical for its successful application in metal contaminated soils.Mineral nutrition affects plant growth and metal absorption and subsequently the accumulation of heavy metal through hyper-accumulator plants.This study assessed the effects of di-hydrogen phosphates(KH2PO4,Ca(H2PO4)2,NaH2PO4 and NH4H2PO4)application at three levels(22,88 and 352 mg P/kg soil)on Sedum alfredii growth and metal uptake by three consecutive harvests on aged and Zn/Cd combined contaminated paddy soil.The addition of phosphates(P)significantly increased the amount of Zn taken up by S.alfredii due to increased shoot Zn concentration and dry matter yield(DMY)(P < 0.05).The highest phytoextraction of Zn and Cd was observed in KH2PO4 and NH4H2PO4 treatment at 352 mg P/kg soil.The amount of Zn removed by phytoextraction increased in the order of 1st clipping < 2nd clipping < 3rd clipping,and for Cd extraction the order was 2nd clipping < 1st clipping < 3rd clipping.These results indicate that the application of P fertilizers coupled with multiple cuttings can enhance the removal of Zn and Cd from contaminated soils by S.alfredii,thus shortening the time needed for accomplishing remediation goals.

  16. Bioremediation and tolerance of humans to heavy metals through microbial processes: a potential role for probiotics? (United States)

    Monachese, Marc; Burton, Jeremy P; Reid, Gregor


    The food and water we consume are often contaminated with a range of chemicals and heavy metals, such as lead, cadmium, arsenic, chromium, and mercury, that are associated with numerous diseases. Although heavy-metal exposure and contamination are not a recent phenomenon, the concentration of metals and the exposure to populations remain major issues despite efforts at remediation. The ability to prevent and manage this problem is still a subject of much debate, with many technologies ineffective and others too expensive for practical large-scale use, especially for developing nations where major pollution occurs. This has led researchers to seek alternative solutions for decontaminating environmental sites and humans themselves. A number of environmental microorganisms have long been known for their ability to bind metals, but less well appreciated are human gastrointestinal bacteria. Species such as Lactobacillus, present in the human mouth, gut, and vagina and in fermented foods, have the ability to bind and detoxify some of these substances. This review examines the current understanding of detoxication mechanisms of lactobacilli and how, in the future, humans and animals might benefit from these organisms in remediating environmental contamination of food.

  17. Keratinase production and biodegradation of polluted secondary chicken feather wastes by a newly isolated multi heavy metal tolerant bacterium-Alcaligenes sp. AQ05-001. (United States)

    Yusuf, Ibrahim; Ahmad, Siti Aqlima; Phang, Lai Yee; Syed, Mohd Arif; Shamaan, Nor Aripin; Abdul Khalil, Khalilah; Dahalan, Farrah Aini; Shukor, Mohd Yunus


    Biodegradation of agricultural wastes, generated annually from poultry farms and slaughterhouses, can solve the pollution problem and at the same time yield valuable degradation products. But these wastes also constitute environmental nuisance, especially in Malaysia where their illegal disposal on heavy metal contaminated soils poses a serious biodegradation issue as feather tends to accumulate heavy metals from the surrounding environment. Further, continuous use of feather wastes as cheap biosorbent material for the removal of heavy metals from effluents has contributed to the rising amount of polluted feathers, which has necessitated the search for heavy metal-tolerant feather degrading strains. Isolation, characterization and application of a novel heavy metal-tolerant feather-degrading bacterium, identified by 16S RNA sequencing as Alcaligenes sp. AQ05-001 in degradation of heavy metal polluted recalcitrant agricultural wastes, have been reported. Physico-cultural conditions influencing its activities were studied using one-factor-at-a-time and a statistical optimisation approach. Complete degradation of 5 g/L feather was achieved with pH 8, 2% inoculum at 27 °C and incubation period of 36 h. The medium optimisation after the response surface methodology (RSM) resulted in a 10-fold increase in keratinase production (88.4 U/mL) over the initial 8.85 U/mL when supplemented with 0.5% (w/v) sucrose, 0.15% (w/v) ammonium bicarbonate, 0.3% (w/v) skim milk, and 0.01% (w/v) urea. Under optimum conditions, the bacterium was able to degrade heavy metal polluted feathers completely and produced valuable keratinase and protein-rich hydrolysates. About 83% of the feathers polluted with a mixture of highly toxic metals were degraded with high keratinase activities. The heavy metal tolerance ability of this bacterium can be harnessed not only in keratinase production but also in the bioremediation of heavy metal-polluted feather wastes.


    Directory of Open Access Journals (Sweden)

    Elmi Roseida Cen-Cen


    Full Text Available Los agaves son plantas que pertenecen a un género constituido por numerosas especies, adaptadas para crecer en muy diversos hábitats, algunos con condiciones ambientales extremas. Distintas especies de agave crecen sobre distintos tipos de suelos, algunas en suelos con muy bajo contenido de nutrientes minerales y otras en suelos salinos o en suelos contaminados con iones metálicos. La relación planta-suelo ha sido escasamente estudiada en este género por lo que se desconoce, entre otras cuestiones, cuál es la capacidad de los agaves para absorber, transportar y almacenar nutrientes minerales, cuáles son los mecanismos celulares y bioquímicos que utilizan, o si poseen especial sensibilidad o tolerancia a los iones metálicos. Este estudio reporta el efecto de diversas concentraciones de sulfato de cadmio, cobalto, cobre, zinc o de manganeso sobre plántulas deAgave tequilana, bajo condiciones controladas de laboratorio; la concentración mínima de esos iones metálicos requerida para inducir un efecto tóxico visualmente detectable en tiempos cortos (ocho días; describimos los efectos tóxicos que estos metales generan sobre las plántulas de agave; y reportamos la cantidad de Cu2+, Cd2+ y Co2+ que se acumula en las hojas de plántulas de agave tratadas con altas concentraciones (milimolares de esos metales. Nuestros resultados muestran que, en experimentos de toxicidad aguda y bajo las condiciones aquí establecidas, elA. tequilanaposee una notable tolerancia a altas concentraciones de los distintos metales iónicos probados, incluyendo tanto micronutrientes como metales tóxicos, así como la capacidad de transportar en altas cantidades estos metales a tejido aéreo.

  19. Molecular Mechanism of Heavy Metal Toxicity and Tolerance in Plants: Central Role of Glutathione in Detoxification of Reactive Oxygen Species and Methylglyoxal and in Heavy Metal Chelation

    Directory of Open Access Journals (Sweden)

    Mohammad Anwar Hossain


    Full Text Available Heavy metal (HM toxicity is one of the major abiotic stresses leading to hazardous effects in plants. A common consequence of HM toxicity is the excessive accumulation of reactive oxygen species (ROS and methylglyoxal (MG, both of which can cause peroxidation of lipids, oxidation of protein, inactivation of enzymes, DNA damage and/or interact with other vital constituents of plant cells. Higher plants have evolved a sophisticated antioxidant defense system and a glyoxalase system to scavenge ROS and MG. In addition, HMs that enter the cell may be sequestered by amino acids, organic acids, glutathione (GSH, or by specific metal-binding ligands. Being a central molecule of both the antioxidant defense system and the glyoxalase system, GSH is involved in both direct and indirect control of ROS and MG and their reaction products in plant cells, thus protecting the plant from HM-induced oxidative damage. Recent plant molecular studies have shown that GSH by itself and its metabolizing enzymes—notably glutathione S-transferase, glutathione peroxidase, dehydroascorbate reductase, glutathione reductase, glyoxalase I and glyoxalase II—act additively and coordinately for efficient protection against ROS- and MG-induced damage in addition to detoxification, complexation, chelation and compartmentation of HMs. The aim of this review is to integrate a recent understanding of physiological and biochemical mechanisms of HM-induced plant stress response and tolerance based on the findings of current plant molecular biology research.

  20. Molecular dynamics simulation of heat-affected zone of copper metal ablated with femtosecond laser (United States)

    Hirayama, Yoichi; Obara, Minoru


    Femtosecond laser ablation of materials with high thermal conductivity is of paramount importance, because the chemical composition and properties of the area ablated with femtosecond laser are kept unchanged. The material processing by femtosecond laser can well control the heat-affected zone, compared to nanosecond laser ablation. We report on the heat-affected zone of crystalline copper (Cu) by use of femtosecond laser experimentally and theoretically. Laser ablation of Cu is investigated theoretically by two temperature model and molecular dynamics (MD) simulation. The MD simulation takes into account of electron temperature and thermal diffusion length calculated by two temperature model. The dependence of lattice temperature on time and depth is calculated by the MD simulation and two temperature model. The heat-affected zone estimated from the temperature is mainly studied and calculated to be 3 nm at 0.02 J/cm2 which is below the threshold fluence of 0.137 J/cm2. In addition, the thickness of heat-affected zone of copper crystal ablated with femtosecond Ti:sapphire laser is experimentally studied. As a result of X-ray diffraction (XRD) of the ablated surface, the surface crystallinity is partially changed into disordered structure from crystal form. The residual energy left in the metal, which is not used for ablation, will induce liquid phase, leading to the amorphous phase of the metal during resolidification. The thickness of heat-affected zone depends on laser fluence and is experimentally measured to be less than 1 μm at higher laser fluences than the ablation threshold.

  1. Development of Coke-tolerant Transition Metal Catalysts for Dry Reforming of Methane

    KAUST Repository

    Al-Sabban, Bedour E.


    Dry reforming of methane (DRM) is an attractive and promising process for the conversion of methane and carbon dioxide which are the most abundant carbon sources into valuable syngas. The produced syngas, which is a mixture of hydrogen and carbon monoxide, can be used as intermediates in the manufacture of numerous chemicals. To achieve high conversion, DRM reaction is operated at high temperatures (700-900 °C) that can cause major drawbacks of catalyst deactivation by carbon deposition, metal sintering or metal oxidation. Therefore, the primary goal is to develop a metal based catalyst for DRM that can completely suppress carbon formation by designing the catalyst composition. The strategy of this work was to synthesize Ni-based catalysts all of which prepared by homogeneous deposition precipitation method (HDP) to produce nanoparticles with narrow size distribution. In addition, control the reactivity of the metal by finely tuning the bimetallic composition and the reaction conditions in terms of reaction temperature and pressure. The highly endothermic dry reforming of methane proceeds via CH4 decomposition to leave surface carbon species, followed by removal of C with CO2-derived species to give CO. Tuning the reactivity of the active metal towards these reactions during DRM allows in principle the catalyst surface to remain active and clean without carbon deposition for a long-term. The initial attempt was to improve the resistance of Ni catalyst towards carbon deposition, therefore, a series of 5 wt.% bimetallic Ni9Pt1 were supported on various metal oxides (Al2O3, CeO2, and ZrO2). The addition of small amount of noble metal improved the stability of the catalyst compared to their monometallic Ni and Pt catalysts, but still high amount of carbon (> 0.1 wt.%) was formed after 24 h of the reaction. The obtained results showed that the catalytic performance, particle size and amount of deposited carbon depends on the nature of support. Among the tested

  2. Factors affecting the concentrations of heavy metals in precipitation of Tehran using factor analysis method

    Directory of Open Access Journals (Sweden)

    H Kamani


    Full Text Available Backgrounds and Objectives: Quantity of trace metals in the wet precipitation can illustrate the environmental pollution of different urban areas. Up to now, there is no study regarding the chemistry of wet precipitation in Tehran .The objectives of this study are: measurement of heavy metal concentrations and identification of the main factors affecting the heavy metal concentrations in wet precipitation using factor analysis method. Materials and Methods: This was a cross-sectional study in which measurements of heavy metals were performed in 53 wet precipitation samples collected from a central site of Tehran City, capital of Iran. The samples were collected during November to May in 2010, 2011 and 2012 on the roof of the student’s dormitory building of Tehran University of Medical Sciences and then the concentration of heavy metals in each sample was measured with ICP-MS. Results: pH ranged from 4.2 to 7.1 with a mean value of 5.1 indicating in acidic range. Result of EF calculations revealed that samples were not enriched with Fe and Cr but were enriched with Zn, Cd, Ni, Pb and Cu. Factor Component Analysis with Varimax normalized rotation showed Al, Fe and Cr are originated from crustal source and Zn, Cd, Ni, Pb and Cu are originated from anthropogenic sources.  Conclusion: EF and acidic pH values indicate Tehran is under the influence of extremely anthropogenic activities. Large number of vehicles and industrial activity in the city are undoubtedly responsible for the emission of a wide range of pollution.

  3. Emulsifier type, metal chelation and pH affect oxidative stability of n-3-enriched emulsions

    DEFF Research Database (Denmark)

    Haahr, Anne-Mette; Jacobsen, Charlotte


    Recent research has shown that the oxidative stability of oil-in-water emulsions is affected by the type of surfactant used as emulsifier. The aim of this study was to evaluate the effect of real food emulsifiers as well as metal chelation by EDTA and pH on the oxidative stability of a 10% n-3...... to their ability to chelate iron, scavenge free radicals, interfere with interactions between the lipid hydroperoxides and iron as well as to form a physical harrier around the oil droplets....

  4. Phase measurements of erythrocytes affected by metal ions with quantitative interferometric microscopy (United States)

    Wang, Shouyu; Yan, Keding; Shan, Yanke; Xu, Mingfei; Liu, Fei; Xue, Liang


    Erythrocyte morphology is an important factor in disease diagnosis, however, traditional setups as microscopes and cytometers cannot provide enough quantitative information of cellular morphology for in-depth statistics and analysis. In order to capture variations of erythrocytes affected by metal ions, quantitative interferometric microscopy (QIM) is applied to monitor their morphology changes. Combined with phase retrieval and cell recognition, erythrocyte phase images, as well as phase area and volume, can be accurately and automatically obtained. The research proves that QIM is an effective tool in cellular observation and measurement.


    Institute of Scientific and Technical Information of China (English)


    Based upon an analytical model for predicting the crack growth in fiber reinforced metal laminates (FRMLs), some factors affecting the fatigue crack growth rates of FRMLs were analyzed, including the lay-up of FRMLs, the modulus of the fibers, the residual stresses in FRMLs, the bonding strength and the shear modulus of the adhesive, etc.It was shown from the present analysis that the interface number of the laminates, the modulus of the fibers and the residual stresses in FRMLs have very great effects on the fatigue lives of FRMLs, but the effects of the bonding strength and the shear modulus of the adhesive are relatively small.

  6. Biofilm inhibition and antimicrobial action of lipopeptide biosurfactant produced by heavy metal tolerant strain Bacillus cereus NK1. (United States)

    Sriram, Muthu Irulappan; Kalishwaralal, Kalimuthu; Deepak, Venkataraman; Gracerosepat, Raja; Srisakthi, Kandasamy; Gurunathan, Sangiliyandi


    Biosurfactants are worthful microbial amphiphilic molecules with efficient surface-active and biological properties applicable to several industries and processes. Among them lipopeptides represent a class of microbial surfactants with increasing scientific, therapeutic and biotechnological interests. A heavy metal tolerant Bacillus strain has been isolated and the biofilm inhibition and antimicrobial activity of biosurfactant produced by the strain have been studied. Biosurfactant production was confirmed by the conventional screening methods including hemolytic activity, drop collapsing test, oil displacement test, emulsification and lipase production assays. The biosurfactant produced by this strain was a lipopeptide and exhibited strong surface activity. The biosurfactant has been characterized using FTIR, TLC and HPLC. The minimum active dose of this biosurfactant when compared with the other chemical surfactants was found as 0.150±0.06 μg. The critical micelle concentration was found to be 45 mg/l. The biosurfactant was found to be stable and active over a wide range of pH, temperature and NaCl concentration. It was also able to emulsify a wide range of hydrocarbons and oils thereby extending its application for the bioremediation of oil contaminated sites. The biosurfactant exhibited significant reduction in biofilm formation by pathogens and showed potent antimicrobial activity against various gram positive, gram negative bacteria and fungi. Agar diffusion assay for heavy metal resistance showed that the isolate was resistant to ferrous, lead and zinc. Considering the biofilm inhibition and antimicrobial property of biosurfactant, it can be utilized as a potential therapeutic molecule for numerous microbial infections. The heavy metal resistance of the strain can also be harnessed as an invaluable biological tool for in situ bioremediation.

  7. Pseudometallophytes colonising Pb/Zn mine tailings: a description of the plant-microorganism-rhizosphere soil system and isolation of metal-tolerant bacteria. (United States)

    Becerra-Castro, C; Monterroso, C; Prieto-Fernández, A; Rodríguez-Lamas, L; Loureiro-Viñas, M; Acea, M J; Kidd, P S


    The plant-microorganism-soil system of three pseudometallophytes (Betula celtiberica, Cytisus scoparius and Festuca rubra) growing in a Pb/Zn mine was characterised. Plant metal accumulation, soil metal fractions (rhizosphere and non-vegetated) and bacterial densities were determined. Total Cd, Pb and Zn in non-vegetated soils was up to 50, 3000 and 20,000 mg kg(-1) dry weight, respectively. The residual fraction dominated non-vegetated soils, whereas plant-available fractions became important in rhizosphere soils. All plant species effectively excluded metals from the shoot. F. rubra presented a shoot:root transport factor of ≤0.2 and this population could be useful in future phytostabilisation trials. Culturable bacterial densities and diversity were low (predominantly Actinobacteria). Rhizosphere soils hosted higher total and metal-tolerant bacterial densities. Seventy-four metal-tolerant rhizobacteria were isolated, and characterised genotypically (BOX-PCR, 16S rDNA) and phenotypically [Cd/Zn tolerance, biosurfactant production and plant growth promoting (PGP) traits]. Several isolates resisted high concentrations of Cd and Zn, and only a few presented PGP traits. Fourteen isolates were evaluated for promoting plant growth of two species (Salix viminalis and Festuca pratensis). Thirteen inoculants enhanced growth of F. pratensis, while only three enhanced growth of S. viminalis. Growth enhancement could not always be related to isolate PGP traits. In conclusion, some isolates show potential application in phytostabilisation or phytoextraction techniques.

  8. Groundwater contributions to metal transport in a small river affected by mining and smelting waste. (United States)

    Coynel, Alexandra; Schäfer, Jörg; Dabrin, Aymeric; Girardot, Naïg; Blanc, Gérard


    The Riou Mort watershed, strongly affected by former coal mining and Zn ore treatment, has been the major source of the historical polymetallic pollution of the Lot-Garonne-Gironde fluvial-estuarine system. Two decades after the end of ore treatment, the former industrial area still contributes important amounts of metals/metalloids from various, partly unidentified, sources to the downstream river system. This study presents the high spatial variability of metal/metalloid (Cd, Zn, As, Sb, U, V) concentrations in water and suspended particulate matter (SPM) from eight observation sites during a short, intense flood event. Despite important dilution effects, the observed concentration levels at the different sites suggested additional Cd and Zn inputs, probably from polluted groundwater. This formerly unknown metal source was then localized and characterized by sampling water and SPM along two longitudinal profiles during different hydrological situations. Groundwater inputs of "truly dissolved" (treatment of the polluted groundwater), that are expected to strongly reduce dissolved Cd and Zn emissions into the Riou Mort River.

  9. Types and concentrations of metal ions affect local structure and dynamics of RNA (United States)

    Wang, Jun; Xiao, Yi


    The roles that metal ions play in the structure and dynamics of RNA molecules are long-standing problems that have been studied extensively but are still not well understood. Here we show that metal ions have distributions around RNA molecules that strongly depend on the types and concentrations of the metal ions and also the electrostatic surface of the molecule. In particular, the ion distributions may not balance all the local electronegativity of the molecule. These ion distributions do not only greatly affect local structures but also lead to different local dynamics of RNA. We studied the effects of different ion solutions on the structure and dynamics of RNA by taking the pre Q1 riboswitch aptamer domain as an illustrative example and using molecular dynamics simulations. Since the local structures and dynamics of RNAs are important to their functions, our results also indicate that the selection of proper ion conditions is necessary to model them correctly, in contrast to the use of diverse ion solutions in current molecular dynamics simulations.

  10. Solubilization of manganese and trace metals in soils affected by acid mine runoff. (United States)

    Green, C H; Heil, D M; Cardon, G E; Butters, G L; Kelly, E F


    Manganese solubility has become a primary concern in the soils and water supplies in the Alamosa River basin, Colorado due to both crop toxicity problems and concentrations that exceed water quality standards. Some of the land in this region has received inputs of acid and trace metals as a result of irrigation with water affected by acid mine drainage and naturally occurring acid mineral seeps. The release of Mn, Zn, Ni, and Cu following saturation with water was studied in four soils from the Alamosa River basin. Redox potentials decreased to values adequate for dissolution of Mn oxides within 24 h following saturation. Soluble Mn concentrations were increased to levels exceeding water quality standards within 84 h. Soluble concentrations of Zn and Ni correlated positively with Mn following reduction for all four soils studied. The correlation between Cu and Mn was significant for only one of the soils studied. The soluble concentrations of Zn and Ni were greater than predicted based on the content of each of these metals in the Mn oxide fraction only. Increases in total electrolyte concentration during reduction indicate that this may be the result of displacement of exchangeable metals by Mn following reductive dissolution of Mn oxides.

  11. Hormonal status and age differentially affect tolerance to the disruptive effects of delta-9-tetrahydrocannabinol (Δ9-THC on learning in female rats

    Directory of Open Access Journals (Sweden)

    Peter J Winsauer


    Full Text Available The effects of hormone status and age on the development of tolerance to D9-THC were assessed in sham-operated (intact or ovariectomized (OVX female rats that received either intraperitoneal saline or 5.6 mg/kg of D9-THC daily from postnatal day (PD 75 to 180 (early adulthood onward or PD 35 to 140 (adolescence onward. During this time, the 4 groups for each age (i.e., intact/saline, intact/THC, OVX/saline, and OVX/THC were trained in a learning and performance procedure and dose-effect curves were established for D9-THC (0.56-56 mg/kg and the cannabinoid type-1 receptor (CB1R antagonist rimonabant (0.32-10 mg/kg. Despite the persistence of small rate-decreasing and error-increasing effects in intact and OVX females from both ages during chronic D9-THC, all of the D9-THC groups developed tolerance. However, the magnitude of tolerance, as well as the effect of hormone status, varied with the age at which chronic D9-THC was initiated. There was no evidence of dependence in any of the groups. Hippocampal protein expression of CB1R, AHA1 (a co-chaperone of CB1R and HSP90β (a molecular chaperone modulated by AHA-1 was affected more by OVX than chronic D9-THC; striatal protein expression was not consistently affected by either manipulation. Hippocampal BDNF expression varied with age, hormone status, and chronic treatment. Thus, hormonal status differentially affects the development of tolerance to the disruptive effects of delta-9-tetrahydrocannabinol (D9-THC on learning and performance behavior in adolescent, but not adult, female rats. These factors and their interactions also differentially affect cannabinoid signaling proteins in the hippocampus and striatum, and ultimately, neural plasticity.

  12. Surface coating affects behavior of metallic nanoparticles in a biological environment

    Directory of Open Access Journals (Sweden)

    Darija Domazet Jurašin


    Full Text Available Silver (AgNPs and maghemite, i.e., superparamagnetic iron oxide nanoparticles (SPIONs are promising candidates for new medical applications, which implies the need for strict information regarding their physicochemical characteristics and behavior in a biological environment. The currently developed AgNPs and SPIONs encompass a myriad of sizes and surface coatings, which affect NPs properties and may improve their biocompatibility. This study is aimed to evaluate the effects of surface coating on colloidal stability and behavior of AgNPs and SPIONs in modelled biological environments using dynamic and electrophoretic light scattering techniques, as well as transmission electron microscopy to visualize the behavior of the NP. Three dispersion media were investigated: ultrapure water (UW, biological cell culture medium without addition of protein (BM, and BM supplemented with common serum protein (BMP. The obtained results showed that different coating agents on AgNPs and SPIONs produced different stabilities in the same biological media. The combination of negative charge and high adsorption strength of coating agents proved to be important for achieving good stability of metallic NPs in electrolyte-rich fluids. Most importantly, the presence of proteins provided colloidal stabilization to metallic NPs in biological fluids regardless of their chemical composition, surface structure and surface charge. In addition, an assessment of AgNP and SPION behavior in real biological fluids, rat whole blood (WhBl and blood plasma (BlPl, revealed that the composition of a biological medium is crucial for the colloidal stability and type of metallic NP transformation. Our results highlight the importance of physicochemical characterization and stability evaluation of metallic NPs in a variety of biological systems including as many NP properties as possible.

  13. Assessment of heavy metal pollution risks in Yonki Reservoir environmental matrices affected by gold mining activity. (United States)

    Kapia, Samuel; Rao, B K Rajashekhar; Sakulas, Harry


    This study reports the heavy metal (Hg, Cd, Cr, Cu, and Pb) contamination risks to and safety of two species of fresh water fish (tilapia, Oreochromis mossambicus and carp, Cyprinus carpio) that are farmed in the Yonki Reservoir in the Eastern Highlands of Papua New Guinea (PNG). The upper reaches of the reservoir are affected by alluvial and large-scale gold mining activities. We also assessed heavy metal levels in the surface waters and sediments and in selected aquatic plant species from the reservoir and streams that intersect the gold mining areas. The water quality was acceptable, except for the Cr concentration, which exceeded the World Health Organization (WHO) standard for water contamination. The sediments were contaminated with Cd and Cu in most of the sampling stations along the upstream waters and the reservoir. The Cd concentration in the sediments exceeded the US Environmental Protection Agency's Sediment Quality Guideline (SQG) values, and the geoaccumulation index (Igeo) values indicated heavy to extreme pollution. In addition, the Cd, Cu, and Pb concentrations in aquatic plants exceeded the WHO guidelines for these contaminants. Between the fish species, tilapia accumulated significantly higher (P < 0.05) Cu in their organ tissues than carp, confirming the bioaccumulation of some metals in the aquatic fauna. The edible muscles of the fish specimens had metal concentrations below the maximum permissible levels established by statutory guidelines. In addition, a human health risk assessment, performed using the estimated weekly intake (EWI) values, indicated that farmed fish from the Yonki Reservoir are safe for human consumption.

  14. The assembly of metals chelation by thiols and vacuolar compartmentalization conferred increased tolerance to and accumulation of cadmium and arsenic in transgenic Arabidopsis thaliana

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Jiangbo [Key Laboratory of Plant Resources, Institute of Botany, The Chinese Academy of Sciences, Beijing 100093 (China); Inner Mongolia Key Laboratory of Biomass-Energy Conversion, The Institute of Bioengineering and Technology, Inner Mongolia University of Science and Technology, Baotou 040100 (China); Xu, Wenzhong [Key Laboratory of Plant Resources, Institute of Botany, The Chinese Academy of Sciences, Beijing 100093 (China); Ma, Mi, E-mail: [Key Laboratory of Plant Resources, Institute of Botany, The Chinese Academy of Sciences, Beijing 100093 (China)


    Highlights: Black-Right-Pointing-Pointer Simultaneous transformation of AsPCS1 and ScYCF1 into Arabidopsis thaliana which is sensitive to heavy metals, leads to transgenic plants tolerant to Arsenic and cadmium. Black-Right-Pointing-Pointer Dual-gene transgenic Arabidopsis showed higher accumulation of Arsenic and cadmium than single and non-transgenic plants. Black-Right-Pointing-Pointer Our results proved that improved thiol peptides synthesis and vacuolar compartmentation in plant dramatically boosted the survival rates of plants when exposed to heavy metals. Black-Right-Pointing-Pointer A new strategy for efficient phytoremediation of heavy metals by stacking genes transformation in plants was developed in this article. - Abstract: Transgenic Arabidopsis thaliana were developed to increase tolerance for and accumulation of heavy metals and metalloids by simultaneous overexpression of AsPCS1 and YCF1 (derived from garlic and baker's yeast) based on the fact that chelation of metals and vacuolar compartmentalization are the main strategies for heavy metals/metalloids detoxification and tolerance in plants. Dual-gene transgenic lines had the longest roots and the highest accumulation of Cd and As than single-gene transgenic lines and wildtype. When grown on cadmium or arsenic (arsenite/arsenate), Dual-gene transgenic lines accumulated over 2-10 folds cadmium/arsenite and 2-3 folds arsenate than wild type or plants expressing AsPCS1 or YCF1 alone. Such stacking modified genes involved in chelation of toxic metals and vacuolar compartmentalization represents a highly promising new tool for use in phytoremediation efforts.

  15. Effect of metal tolerant plant growth promoting bacteria on growth and metal accumulation in Zea mays plants grown in fly ash amended soil. (United States)

    Kumar, Kalpna V; Patra, D D


    The present study was undertaken to examine the effect of the application of fly ash (FA) into Garden soil (GS), with and without inoculation of plant growth promoting bacteria (PGPB), on the growth and metal uptake by Zea mays plants. Three FA tolerant PGPB strains, Pseudomonas sp. PS5, PS14, and Bacillus sp. BC29 were isolated from FA contaminated soils and assessed for their plant growth promoting features on the Z. mays plants. All three strains were also examined for their ability to solubilize phosphate and to produce Indole Acetic Acid (IAA), siderophores, and hydrogencynide acid (HCN) production. Although inoculation of all strains significantly enhanced the growth of plants at both the concentration of FA but maximum growth was observed in plants inoculated with BC29 and PS14 at low level (25%) of FA concentration. The experimental results explored the plant growth promoting features of selected strains which not only enhanced growth and biomass of plants but also protected them from toxicity of FA.

  16. Efficient continuous biosynthesis of silver nanoparticles by activated sludge micromycetes with enhanced tolerance to metal ion toxicity. (United States)

    Tyupa, Dmitry V; Kalenov, Sergei V; Baurina, Marina M; Yakubovich, Liubov M; Morozov, Alexander N; Zakalyukin, Ruslan M; Sorokin, Vladimir V; Skladnev, Dmitry A


    The method for producing AgNPs by granules of activated sludge micromycetes with enhanced tolerance to metal ion toxicity - Penicillium glabrum, Fusarium nivale and Fusarium oxysporum has been developed; the optimum conditions for AgNP biosynthesis being found: the Ag(+) ion concentration, duration of the contact of microbial cells with silver ions, a growth phase of microorganisms, medium composition, a рН value, mixing conditions, and also lighting intensity. The effect of Cl(-), SO4(2-) and HPO4(2-) ions binding Ag(+) ions was eliminated, that brought to significant increase of the yield of NPs. Under batch conditions, silver particles of 60-110 nanometers in size were formed with a 65% yield. It was established that the nanoparticles were covered with microbial cell membrane proteins composed up to 70% by weight of the NPs that prevented their aggregation. In addition, it was the first time stable AgNPs had been formed by continuous AgNP biosynthesis by living cells of F. oxysporum with an 80% yield for a long time.

  17. Chromosome VIII disomy influences the nonsense suppression efficiency and transition metal tolerance of the yeast Saccharomyces cerevisiae. (United States)

    Zadorsky, S P; Sopova, Y V; Andreichuk, D Y; Startsev, V A; Medvedeva, V P; Inge-Vechtomov, S G


    The SUP35 gene of the yeast Saccharomyces cerevisiae encodes the translation termination factor eRF3. Mutations in this gene lead to the suppression of nonsense mutations and a number of other pleiotropic phenotypes, one of which is impaired chromosome segregation during cell division. Similar effects result from replacing the S. cerevisiae SUP35 gene with its orthologues. A number of genetic and epigenetic changes that occur in the sup35 background result in partial compensation for this suppressor effect. In this study we showed that in S. cerevisiae strains in which the SUP35 orthologue from the yeast Pichia methanolica replaces the S. cerevisiae SUP35 gene, chromosome VIII disomy results in decreased efficiency of nonsense suppression. This antisuppressor effect is not associated with decreased stop codon read-through. We identified SBP1, a gene that localizes to chromosome VIII, as a dosage-dependent antisuppressor that strongly contributes to the overall antisuppressor effect of chromosome VIII disomy. Disomy of chromosome VIII also leads to a change in the yeast strains' tolerance of a number of transition metal salts.

  18. Heavy metal accumulation and tolerance of energy grass (Elymus elongatus subsp. ponticus cv. Szarvasi-1) grown in hydroponic culture. (United States)

    Sipos, Gyula; Solti, Adám; Czech, Viktória; Vashegyi, Ildikó; Tóth, Brigitta; Cseh, Edit; Fodor, Ferenc


    Phytoremediation is a plant based, cost effective technology to detoxify or stabilise contaminated soils. Fast growing, high biomass, perennial plants may be used not only in phytoremediation but also in energy production. Szarvasi-1 energy grass (Elymus elongatus subsp. ponticus cv. Szarvasi-1), a good candidate for this combined application, was grown in nutrient solution in order to assess its Cd, Cu, Ni, Pb and Zn accumulation and tolerance. Its shoot metal accumulation showed the order Pb < Ni < Cu ∼ Cd < Zn. In parallel with this, Pb and Ni had no or very little influence on the growth, dry matter content, chlorophyll concentration and transpiration of the plants. Cu and Cd treatment resulted in significant decreases in all these parameters that can be attributed to Fe plaque formation in the roots suggested by markedly increased Fe and Cu accumulation. This came together with decreased shoot and root Mn concentrations in both treatments while shoot Cu and Zn concentrations decreased under Cd and Cu exposure, respectively. Zn treatment had no effect or even slightly stimulated the plants. This may be due to a slight stimulation of Fe translocation and a very efficient detoxification mechanism. Based on the average 300 mg kg⁻¹ (dry mass) Zn concentration which is 0.03% of the shoot dry mass the variety is suggested to be classified as Zn accumulator.

  19. Antibiotic Resistance and Heavy Metals Tolerance in Gram-Negative Bacteria from Diseased American Bullfrog (Rana catesbeiana) Cultured in Malaysia

    Institute of Scientific and Technical Information of China (English)

    M Na-jian; S W Lee; W Wendy; L W Tee; M Nadirah; S H Faizah


    A total of 140 bacterial isolates have been successfully isolated from various organs of diseased American bullfrog (Rana catesbeiana) cultured in Malaysia. The most frequently isolated bacteria was Edwardsiella spp. (46 isolates) followed by Aeromonas spp. (33 isolates), Flavobacterium spp. (31 isolates), and Vibrio spp. (30 isolates). Majority of the bacterial isolates were found sensitive to furazolidone (85.0%), chloramphenicol (85.0%), oxolinic acid (90.0%), florfenicol (95.0%), and flumequine (97.5%). On the other hand, most of the bacterial isolates were resistant to oleandomycin (77.5%) and lincomycin (87.5%). Nitrofurantoin and flumequine can be inhibited the growth of all of Vibrio spp. whereas all isolates of Edwardsiella spp. were found sensitive to florfenicol and flumequine. Multiple antibiotic resistance (MAR) index were in range of 0.30-0.40, indicating that bacterial isolates from cultured bullfrogs may have received high risk exposure to the tested antibiotics. In addition, 90-100% of the isolates were resistant to copper, cadmium, and chromium. These results provided insight information on tolerance level of bacterial isolates from cultured bullfrogs to 21 antibiotics as well as heavy metals.

  20. Groundwater contributions to metal transport in a small river affected by mining and smelting waste

    Energy Technology Data Exchange (ETDEWEB)

    Coynel, A.; Schafer, J.; Dabrin, A.; Girardot, N.; Blanc, G. [University of Bordeaux, Talence (France)


    The Riou Mort watershed, strongly affected by former coal mining and ZEE ore treatment, has been the major source of the historical polymetallic pollution of the Lot-Garonne-Gironde fluvial-estuarine system. Two decades after the end of ore treatment, the former industrial area still contributes important amounts of metals/metalloids from various, partly unidentified, sources to the downstream river system. This study presents the high spatial variability of metal/metalloid (Cd, Zn, As, Sb, U, V) concentrations in water and suspended particulate matter (SPM) from eight observation sites during a short, intense flood event. Despite important dilution effects, the observed concentration levels at the different sites suggested additional Cd and Zn inputs, probably from polluted groundwater. This formerly unknown metal source was then localized and characterized by sampling water and SPM along two longitudinal profiles during different hydrological situations. Groundwater inputs of 'truly dissolved' (<0.02pm) Cd and Zn occurred along -200m, contributing 43% and 28% to the total annual (2004) Cd and Zn fluxes in the Riou Mort River. The estimated groundwater concentrations of Cd and Zn (2500-6700 and 83,000-170,000 mu g1{sup -1}, respectively) in the source zone were consistent with values measured in samples from the near aquifer (5400-13,000 and 200,000-400,000 mu g1{sup -1}). The present work induced concrete remediation actions (pumping and treatment of the polluted groundwater), that are expected to strongly reduce dissolved Cd and Zn emissions into the Riou Mort River.

  1. Metal cycling during sediment early diagenesis in a water reservoir affected by acid mine drainage

    DEFF Research Database (Denmark)

    Torres, Ester; Ayora, Carlos; Canovas, C. R.;


    The discharge of acid mine drainage (AMD) into a reservoir may seriously affect the water quality. To investigate the metal transfer between the water and the sediment, three cores were collected from the Sancho Reservoir (Iberian Pyrite Belt, SW Spain) during different seasons: turnover event......; oxic, stratified period; anoxic and under shallow perennially oxic conditions. The cores were sliced in an oxygen-free atmosphere, after which pore water was extracted by centrifugation and analyzed. A sequential extraction was then applied to the sediments to extract the water-soluble, monosulfide......, low crystallinity Fe(III)-oxyhydroxide, crystalline Fe(III)-oxide, organic, pyrite and residual phases. The results showed that, despite the acidic chemistry of the water column (pH

  2. A spectroscopic study of factors affecting charge transfer at organo-metallic interfaces

    CERN Document Server

    Tucker, C E


    polydiacetylene and omega-tricosenoic acid LB films. The resulting analyses have allowed comparison of charge trapping within the different bulk films and also at the film to substrate interface. In addition to DBARS, Fourier Transform Infra-red (FTIR) and Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopies have been used to investigate the factors affecting the carboxylic acid group at the head of the LB molecule and the role this plays in charge transport across the organo-metallic boundary. The properties of organic films produced by the Langmuir-Blodgett (LB) technique have become more widely known in the last few decades, as the variety of organic molecules suitable for this method of production has increased. One class of LB molecule receiving particular attention has been that of conjugated polymers. These organic materials exhibit an anisotropic semi-conductor like behavior along the polymer chain, making them suitable candidate materials for use in molecular electronic devices. However,...

  3. Toxic metal interactions affect the bioaccumulation and dietary intake of macro- and micro-nutrients. (United States)

    Khan, Anwarzeb; Khan, Sardar; Alam, Mehboob; Khan, Muhammad Amjad; Aamir, Muhammad; Qamar, Zahir; Ur Rehman, Zahir; Perveen, Sajida


    The present study was conducted to evaluate the effects of heavy metals (cadmium (Cd), lead (Pb) and Cd-Pb mix) on bioaccumulation of different nutrients. Three plant species including potato, tomato and lettuce were grown in pots containing soil contaminated with Cd, Pb and Cd-Pb mix at four different levels. The edible portions of each plant were analysed for Cd, Pb and different macro- and micro-nutrients including protein, vitamin C, nitrogen (N), phosphorous (P), potassium (K), iron (Fe), manganese (Mn), calcium (Ca) and magnesium (Mg). Results indicated significant variations in selected elemental concentrations in all the three plants grown in different treatments. The projected daily dietary intake values of selected metals were significant (P < 0.001) for Fe, Mn, Ca and Mg but not significant for protein, vitamin C, N and P. The elemental contribution to Recommended Dietary Allowance (RDA) was significant for Mn. Similarly, Fe and Mg also showed substantial contribution to RDA, while Ca, N, P, K, protein and vitamin C showed the minimal contribution for different age groups. This study suggests that vegetables cultivated on Cd and Pb contaminated soil may significantly affect their quality, and the consumption of such vegetables may result in substantial negative effects on nutritional composition of the consumer body. Long term and continuous use of contaminated vegetables may result in malnutrition.

  4. Root Fungal Endophytes Enhance Heavy-Metal Stress Tolerance of Clethra barbinervis Growing Naturally at Mining Sites via Growth Enhancement, Promotion of Nutrient Uptake and Decrease of Heavy-Metal Concentration (United States)

    Shigeto, Arisa; Yui, Hiroshi; Haruma, Toshikatsu


    Clethra barbinervis Sieb. et Zucc. is a tree species that grows naturally at several mine sites and seems to be tolerant of high concentrations of heavy metals, such as Cu, Zn, and Pb. The purpose of this study is to clarify the mechanism(s) underlying this species’ ability to tolerate the sites’ severe heavy-metal pollution by considering C. barbinervis interaction with root fungal endophytes. We measured the heavy metal concentrations of root-zone soil, leaves, branches, and fine roots collected from mature C. barbinervis at Hitachi mine. We isolated fungal endophytes from surface-sterilized root segments, and we examined the growth, and heavy metal and nutrient absorption of C. barbinervis seedlings growing in sterilized mine soil with or without root fungal endophytes. Field analyses showed that C. barbinervis contained considerably high amounts of Cu, Zn, and Pb in fine roots and Zn in leaves. The fungi, Phialocephala fortinii, Rhizodermea veluwensis, and Rhizoscyphus sp. were frequently isolated as dominant fungal endophyte species. Inoculation of these root fungal endophytes to C. barbinervis seedlings growing in sterilized mine soil indicated that these fungi significantly enhanced the growth of C. barbinervis seedlings, increased K uptake in shoots and reduced the concentrations of Cu, Ni, Zn, Cd, and Pb in roots. Without root fungal endophytes, C. barbinervis could hardly grow under the heavy-metal contaminated condition, showing chlorosis, a symptom of heavy-metal toxicity. Our results indicate that the tree C. barbinervis can tolerate high heavy-metal concentrations due to the support of root fungal endophytes including P. fortinii, R. veluwensis, and Rhizoscyphus sp. via growth enhancement, K uptake promotion and decrease of heavy metal concentrations. PMID:28030648

  5. Ethylenediurea (EDU) affects the growth of ozone-sensitive and tolerant ash (Fraxinus excelsior) trees under ambient O3 conditions. (United States)

    Paoletti, Elena; Contran, Nicla; Manning, William J; Tagliaferro, Francesco


    Adult ash trees (Fraxinus excelsior L.), known to be sensitive or tolerant to ozone, determined by presence or absence of foliar symptoms in previous years, were treated with ethylenediurea (EDU) at 450 ppm by gravitational trunk infusion over the 2005 growing season (32.5 ppm h AOT40). Tree and shoot growth were recorded in May and September. Leaf area, ectomycorrhizal infection, and leaf and fine root biomass were determined in September. EDU enhanced shoot length and diameter, and the number and area of leaves, in both O3-sensitive and tolerant trees. However, no EDU effects were recorded at the fine root and tree level. Therefore, a potential for EDU protection against O3-caused growth losses of forest trees should be evaluated during longer-term experiments.

  6. Novel lipopeptide biosurfactant produced by hydrocarbon degrading and heavy metal tolerant bacterium Escherichia fergusonii KLU01 as a potential tool for bioremediation. (United States)

    Sriram, Muthu Irulappan; Gayathiri, Shanmugakani; Gnanaselvi, Ulaganathan; Jenifer, Paulraj Stanly; Mohan Raj, Subramanian; Gurunathan, Sangiliyandi


    Escherichia fergusonii KLU01, a propitious bacterial strain isolated from oil contaminated soil was identified to be hydrocarbon degrading, heavy metal tolerant and a potent producer of biosurfactant using diesel oil as the sole carbon and energy source. The biosurfactant produced by the strain was characterized to be a lipopeptide. The minimum active dose and critical micelle concentration of the biosurfactant were found as 0.165±0.08 μg and 36 mg/L, respectively. In spite of being an excellent emulsifier, the biosurfactant showed an incredible stability at extremes of temperature, pH and at various concentrations of NaCl, CaCl₂ and MgCl₂. Also the bacterium manifested tolerance towards Manganese, Iron, Lead, Nickel, Copper and Zinc. The strain emerges as a new class of biosurfactant producer with potential environmental and industrial applications, especially in hydrocarbon degradation and heavy metal bioremediation.

  7. Tolerance of non-platinum group metals cathodes proton exchange membrane fuel cells to air contaminants (United States)

    Reshetenko, Tatyana; Serov, Alexey; Artyushkova, Kateryna; Matanovic, Ivana; Sarah Stariha; Atanassov, Plamen


    The effects of major airborne contaminants (SO2, NO2 and CO) on the spatial performance of Fe/N/C cathode membrane electrode assemblies were studied using a segmented cell system. The injection of 2-10 ppm SO2 in air stream did not cause any performance decrease and redistribution of local currents due to the lack of stably adsorbed SO2 molecules on Fe-Nx sites, as confirmed by density functional theory (DFT) calculations. The introduction of 5-20 ppm of CO into the air stream also did not affect fuel cell performance. The exposure of Fe/N/C cathodes to 2 and 10 ppm NO2 resulted in performance losses of 30 and 70-75 mV, respectively. DFT results showed that the adsorption energies of NO2 and NO were greater than that of O2, which accounted for the observed voltage decrease and slight current redistribution. The cell performance partially recovered when the NO2 injection was stopped. The long-term operation of the fuel cells resulted in cell performance degradation. XPS analyses of Fe/N/C electrodes revealed that the performance decrease was due to catalyst degradation and ionomer oxidation. The latter was accelerated in the presence of air contaminants. The details of the spatial performance and electrochemical impedance spectroscopy results are presented and discussed.

  8. ARTICLES: Methanol Tolerant Non-noble Metal Co-C-N Catalyst for Oxygen Reduction Reaction Using Urea as Nitrogen Source (United States)

    Si, Yu-jun; Chen, Chang-guo; Yin, Wei; Cai, Hui


    A non-noble metal oxygen reduction reaction (ORR) catalyst labeled as Co-C-N(800) was synthesized by heat-treating a mixture of urea, cobalt chloride and acetylene black for 2 h at 800 °C in an inert nitrogen atmosphere. X-ray diffraction pattern indicates that a metallic β-Co is generated after the heat-treating process. The results from cyclic voltammograms show that the obtained Co-C-N(800) catalyst has good ORR catalytic activity in 0.5 mol/L H2SO4 solution. The catalyst is also good at methanol tolerance and stability in the acidic solution.

  9. Evaluation of remediation techniques in soils affected by residual contamination with heavy metals and arsenic. (United States)

    García-Carmona, M; Romero-Freire, A; Sierra Aragón, M; Martínez Garzón, F J; Martín Peinado, F J


    Residual soil pollution from the Aznalcóllar mine spill is still a problem in some parts of the affected area, today converted in the Guadiamar Green Corridor. Dispersed spots of polluted soils, identified by the absence of vegetation, are characterized by soil acid pH and high concentrations of As, Pb, Cu and Zn. Ex situ remediation techniques were performed with unrecovered soil samples. Landfarming, Composting and Biopiles techniques were tested in order to immobilize pollutants, to improve soil properties and to promote vegetation recovery. The effectiveness of these techniques was assessed by toxicity bioassays: Lactuca sativa L. root elongation test, Vibrio fischeri bioluminescence reduction test, soil induced respiration test, and Eisenia andrei survival and metal bioaccumulation tests. Landfarming and Composting were not effective techniques, mainly due to the poor improvement of soil properties which maintained high soluble concentrations of Zn and Cu after treatments. Biopile technique, using adjacent recovered soils in the area, was the most effective action in the reduction of soil toxicity; the improvement of soil properties and the reduction in pollutants solubility were key to improve the response of the tested organisms. Therefore, the mixture of recovered soils with polluted soils in the areas affected by residual contamination is considered a more suitable technique to reduce the residual pollution and to promote the complete soil recovery in the Guadiamar Green Corridor.

  10. Transgenerational inheritance of modified DNA methylation patterns and enhanced tolerance induced by heavy metal stress in rice (Oryza sativa L..

    Directory of Open Access Journals (Sweden)

    Xiufang Ou

    Full Text Available BACKGROUND: DNA methylation is sensitive and responsive to stressful environmental conditions. Nonetheless, the extent to which condition-induced somatic methylation modifications can impose transgenerational effects remains to be fully understood. Even less is known about the biological relevance of the induced epigenetic changes for potentially altered well-being of the organismal progenies regarding adaptation to the specific condition their progenitors experienced. METHODOLOGY/PRINCIPAL FINDINGS: We analyzed DNA methylation pattern by gel-blotting at genomic loci representing transposable elements and protein-coding genes in leaf-tissue of heavy metal-treated rice (Oryza sativa plants (S0, and its three successive organismal generations. We assessed expression of putative genes involved in establishing and/or maintaining DNA methylation patterns by reverse transcription (RT-PCR. We measured growth of the stressed plants and their unstressed progenies vs. the control plants. We found (1 relative to control, DNA methylation patterns were modified in leaf-tissue of the immediately treated plants, and the modifications were exclusively confined to CHG hypomethylation; (2 the CHG-demethylated states were heritable via both maternal and paternal germline, albeit often accompanying further hypomethylation; (3 altered expression of genes encoding for DNA methyltransferases, DNA glycosylase and SWI/SNF chromatin remodeling factor (DDM1 were induced by the stress; (4 progenies of the stressed plants exhibited enhanced tolerance to the same stress their progenitor experienced, and this transgenerational inheritance of the effect of condition accompanying heritability of modified methylation patterns. CONCLUSIONS/SIGNIFICANCE: Our findings suggest that stressful environmental condition can produce transgenerational epigenetic modifications. Progenies of stressed plants may develop enhanced adaptability to the condition, and this acquired trait is

  11. The filter feeder Dreissena polymorpha affects nutrient, silicon, and metal(loid) mobilization from freshwater sediments. (United States)

    Schaller, Jörg; Planer-Friedrich, Britta


    Organic sediments in aquatic ecosystems are well known sinks for nutrients, silicon, and metal(loid)s. Organic matter-consuming organisms like invertebrate shredders, grazers, and bioturbators significantly affect element fixation or remobilization by changing redox conditions or binding properties of organic sediments. Little is known about the effect of filter feeders, like the zebra mussel Dreissena polymorpha, an invasive organism in North American and European freshwater ecosystems. A laboratory batch experiment exposing D. polymorpha (∼1200 organisms per m(2)) to organic sediment from a site contaminated with arsenic, copper, lead, and uranium revealed a significant uptake and accumulation of arsenic, copper, iron, and especially uranium both into the soft body tissues and the seashell. This is in line with previous observations of metal(loid) accumulation from biomonitoring studies. Regarding its environmental impact, D. polymorpha significantly contributed to mobilization of silicon, iron, phosphorus, arsenic, and copper and to immobilization of uranium (p < 0.001), probably driven by redox conditions, microbial activity within the gut system, or active control of element homeostasis. No net mobilization or immobilization was observed for zinc and lead, because of their low mobility at the prevailing pH of 7.5-8.5. The present results suggest that D. polymorpha can both ameliorate (nutrient mobilization, immobilization of toxicants mobile under oxic conditions) or aggravate negative effects (mobilization of toxicants mobile under reducing conditions) in ecosystems. Relating the results of the present study to observed population densities in natural freshwater ecosystems suggests a significant influence of D. polymorpha on element cycling and needs to be considered in future studies.

  12. Heat-affected zone in microdrilling of metals by femtosecond laser pulses (United States)

    Audouard, E.; LeHarzic, R.; Huot, Nicolas; Laporte, Pierre; Valette, S.; Fourtunier, R.


    Several works on laser-matter interaction has shown the differences in sizes for the Heat Affected Zone (HAZ) obtained with nanosecond and femtosecond regimes in laser cutting or drilling. To understand more clearly the basic phenomena that occur in femtosecond regime during the absorption of light by matter, and specially in the case of metals, we have developed both an experimental and a theoretical approach. We use a new method aimed at quantifying the dimensions of the HAZ, using thin-down samples which are micro-drilled and then observed by a transmission electronic microscopy (TEM) technique. The grain size in the samples is analysed near the micro-holes. According to theoretical studies, the thermal diffusion is due to the smaller value of the electron specific heat compared to the lattice one. The thermal diffusion length is found to be a few hundred of nanometers in the case of metals. We use a thermal model to describe the heat diffusion in the sample in order to obtain a theoretical estimation of the HAZ. Holes are drilled in Aluminum using nanosecond and femtosecond laser pulses and characterized by Transmission Electronic Microscopy (TEM). The method for quantifying the dimensions of the heat affected zone (HAZ) surrounding micro-holes is based on the analyze of the grain size evolution. The experiments are using the same Ti-Sapphire laser source (1 kHz, 800 nm). The regeneratively amplified ultra-short pulses (150 fs) are utilized at a low fluence regime (typically 0.01-0.5 mJ/pulse), while the longer pulses (ns) are obtained from the regenerative amplifier without oscillator seeding (0.5 mJ,τ approximately 7-8 ns). The main conclusion is that a 40 micrometers wide HAZ is induced by nanosecond pulses, whereas the femtosecond regime does not produce any TEM observable HAZ. It has to be noticed that the width of the femtosecond HAZ is roughly less than 2 micrometers , which is our observation limit. These results are in agreement with theoretical

  13. Metal contamination in urban street sediment in Pisa (Italy) can affect the production of antioxidant metabolites in Taraxacum officinale Weber. (United States)

    Bretzel, Francesca; Benvenuti, Stefano; Pistelli, Laura


    Taraxacum officinale Weber (dandelion) is a very ubiquitous species, and it can grow in urban environments on metal-polluted sediments deposited in the gutters. This study represents a preliminary step to verify the presence of metals in sediments collected in urban streets in Pisa and to assess the alteration in dandelion metabolites in order to understand its adaptation to polluted environments. The soil and sediments were collected at three urban streets and analyzed for total and extractable Cr, Pb, Cu, Ni, and Zn. The total values of Pb and Zn in street sediments exceeded the limits for residential areas of soils. Zn was the most mobile of the metals analyzed. Floating cultivations trials were set up with dandelion seedlings and street sediments. The metals were analyzed in roots and leaves. Antioxidant power, anthocyanins, polyphenols, non-protein thiols (NP-TH) and chlorophylls were measured in dandelion leaves. The first two parameters (anthocyanins and antioxidant power) were higher in the polluted samples compared to the control; chlorophyll content was lower in the treated samples, whereas NP-TH showed no differences. NP-TH groups determined in roots were associated with the root content of Zn and Pb. These results indicate that dandelion can tolerate plant stress by altering its metabolite content.

  14. Organic acid compounds in root exudation of Moso Bamboo (Phyllostachys pubescens) and its bioactivity as affected by heavy metals. (United States)

    Chen, Junren; Shafi, Mohammad; Wang, Ying; Wu, Jiasen; Ye, Zhengqian; Liu, Chen; Zhong, Bin; Guo, Hua; He, Lizhi; Liu, Dan


    Moso bamboo (Phyllostachys pubescens) has great potential as phytoremediation material in soil contaminated by heavy metals. A hydroponics experiment was conducted to determine organic acid compounds of root exudates of lead- (Pb), zinc- (Zn), copper- (Cu), and cadmium (Cd)-tolerant of Moso bamboo. Plants were grown in nutrients solution which included Pb, Zn, Cu, and Cd applied as Pb(NO3)2 (200 μM), ZnSO4·7H2O (100 μM), CuSO4·5H2O (25 μM), and CdCl2 (10 μM), respectively. Oxalic acid and malic acid were detected in all treatments. Lactic acid was observed in Cu, Cd, and control treatments. The oxalic was the main organic acid exudated by Moso bamboo. In the sand culture experiment, the Moso bamboo significantly activated carbonate heavy metals under activation of roots. The concentration of water-soluble metals (except Pb) in sand were significantly increased as compared with control. Organic acids (1 mM mixed) were used due to its effect on the soil adsorption of heavy metals. After adding mixed organic acids, the Cu and Zn sorption capacity in soils was decreased markedly compared with enhanced Pb and Cd sorption capacity in soils. The sorption was analyzed using Langmuir and Freundlich equations with R (2) values that ranged from 0.956 to 0.999 and 0.919 to 0.997, respectively.

  15. Study of Plant Cell Wall Polymers Affected by Metal Accumulation Using Stimulated Raman Scattering Microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Shi-You [Harvard Univ., Cambridge, MA (United States)


    This project aims to employ newly-developed chemical imaging techniques to measure, in real-time, the concentration, dynamics and spatial distribution of plant cell wall polymers during biomass growth with inoculation of transgenic symbiotic fungi, and to explore a new pathway of delivering detoxified metal to plant apoplast using transgenic symbiotic fungi, which will enhance metal accumulation from soil, and potentially these metals may in turn be used as catalysts to improve the efficiency of biomass conversion to biofuels. The proposed new pathway of biomass production will: 1) benefit metal and radionuclide contaminant mobility in subsurface environments, and 2) potentially improve biomass production and process for bioenergy

  16. Heavy metals species affect fungal-bacterial synergism during the bioremediation of fluoranthene. (United States)

    Ma, Xiao-Kui; Ding, Ning; Peterson, Eric Charles; Daugulis, Andrew J


    The co-occurrence of polycyclic aromatic hydrocarbons (PAHs) with heavy metals (HMs) is very common in contaminated soils, but the influence of HMs on fungal-bacterial synergism during PAH bioremediation has not been investigated. The bioremediation of fluoranthene-contaminated sand using co-cultures of Acremonium sp. P0997 and Bacillus subtilis showed increases of 109.4 and 9.8 % in degradation compared to pure bacterial and fungal cultures, respectively, removing 64.1 ± 1.4 % fluoanthene in total. The presence of Cu(2+) reduced fluoranthene removal to 53.7 ± 1.7 %, while inhibiting bacterial growth, and reducing translocation of bacteria on fungal hyphae by 49.5 %, in terms of the bacterial translocation ratio. Cu(2+) reduced bacterial diffusion by 46.8 and 31.9 %, as reflected by D (a bulk random motility diffusional coefficient) and D eff (the effective one-dimensional diffusion coefficient) compared to the control without HM supplementation, respectively. However, Mn(2+) resulted in a 78.2 ± 1.9 % fluoranthene degradation, representing an increase of 21.9 %, while enhancing bacterial growth and bacterial translocation on fungal hyphae, showing a 12.0 % increase in translocation ratio, with no observable impact on D and D eff. Hence, the presence of HMs has been shown to affect fungal-bacterial synergism in PAH degradation, and this effect differs with HM species.

  17. Arbuscular mycorrhizal fungal phylogenetic groups differ in affecting host plants along heavy metal levels. (United States)

    He, Lei; Yang, Haishui; Yu, Zhenxing; Tang, Jianjun; Xu, Ligen; Chen, Xin


    Arbuscular mycorrhizal fungi (AMF) are important components of soil microbial communities, and play important role in plant growth. However, the effects of AMF phylogenetic groups (Glomeraceae and non-Glomeraceae) on host plant under various heavy metal levels are not clear. Here we conducted a meta-analysis to compare symbiotic relationship between AMF phylogenetic groups (Glomeraceae and non-Glomeraceae) and host plant functional groups (herbs vs. trees, and non-legumes vs. legumes) at three heavy metal levels. In the meta-analysis, we calculate the effect size (ln(RR)) by taking the natural logarithm of the response ratio of inoculated to non-inoculated shoot biomass from each study. We found that the effect size of Glomeraceae increased, but the effect size of non-Glomeraceae decreased under high level of heavy metal compared to low level. According to the effect size, both Glomeraceae and non-Glomeraceae promoted host plant growth, but had different effects under various heavy metal levels. Glomeraceae provided more benefit to host plants than non-Glomeraceae did under heavy metal condition, while non-Glomeraceae provided more benefit to host plants than Glomeraceae did under no heavy metal. AMF phylogenetic groups also differed in promoting plant functional groups under various heavy metal levels. Interacting with Glomeraceae, herbs and legumes grew better than trees and non-legumes did under high heavy metal level, while trees and legumes grew better than herbs and non-legumes did under medium heavy metal level. Interacting with non-Glomeraceae, herbs and legumes grew better than trees and non-legumes did under no heavy metal. We suggested that the combination of legume with Glomeraceae could be a useful way in the remediation of heavy metal polluted environment.

  18. ppGpp negatively impacts ribosome assembly affecting growth and antimicrobial tolerance in Gram-positive bacteria. (United States)

    Corrigan, Rebecca M; Bellows, Lauren E; Wood, Alison; Gründling, Angelika


    The stringent response is a survival mechanism used by bacteria to deal with stress. It is coordinated by the nucleotides guanosine tetraphosphate and pentaphosphate [(p)ppGpp], which interact with target proteins to promote bacterial survival. Although this response has been well characterized in proteobacteria, very little is known about the effectors of this signaling system in Gram-positive species. Here, we report on the identification of seven target proteins for the stringent response nucleotides in the Gram-positive bacterium Staphylococcus aureus We demonstrate that the GTP synthesis enzymes HprT and Gmk bind with a high affinity, leading to an inhibition of GTP production. In addition, we identified five putative GTPases--RsgA, RbgA, Era, HflX, and ObgE--as (p)ppGpp target proteins. We show that RsgA, RbgA, Era, and HflX are functional GTPases and that their activity is promoted in the presence of ribosomes but strongly inhibited by the stringent response nucleotides. By characterizing the function of RsgA in vivo, we ascertain that this protein is involved in ribosome assembly, with an rsgA deletion strain, or a strain inactivated for GTPase activity, displaying decreased growth, a decrease in the amount of mature 70S ribosomes, and an increased level of tolerance to antimicrobials. We additionally demonstrate that the interaction of ppGpp with cellular GTPases is not unique to the staphylococci, as homologs from Bacillus subtilis and Enterococcus faecalis retain this ability. Taken together, this study reveals ribosome inactivation as a previously unidentified mechanism through which the stringent response functions in Gram-positive bacteria.

  19. Accumulation and tolerance to cadmium heavy metal ions and induction of 14-3-3 gene expression in response to cadmium exposure in Coprinus atramentarius. (United States)

    Xie, Chengjian; Hu, Liujie; Yang, Yongzhu; Liao, Dunxiu; Yang, Xingyong


    Cadmium (Cd), one of the most toxic heavy-metal pollutants, has a strong and irreversible tendency to accumulate. Bioremediation is a promising technology to remedy and control heavy metal pollutants because of its low cost and ability to recycle heavy metals. Coprinus atramentarius is recognized as being able to accumulate heavy metal ions. In this work, C. atramentarius is cultivated on a solid medium containing Cd(2+) ions to analyze its ability to tolerate different concentrations of the heavy metal ion. It is found that the growth of C. atramentarius is not significantly inhibited when the concentration of Cd(2+) is less than 0.6mgL(-1). The accumulation capacity of C. atramentarius at different Cd(2+) concentrations also was determined. The results show that 76% of the Cd(2+) present can be accumulated even when the concentration of the Cd(2+) is 1mgL(-1). The different proteins of C. atramentarius exposed to Cd(2+) were further analyzed using gel electrophoresis. A 14-3-3 protein was identified and shown to be significantly up-regulated. In a further study, a full-length 14-3-3 gene was cloned containing a 759bp open reading frame encoding a polypeptide consisting of 252 amino acids and 3 introns. The gene expression work also showed that the 14-3-3 was significantly induced, and showed coordinated patterns of expression, with Cd(2+) exposure.

  20. Biogas production as affected by heavy metals in the anaerobic digestion of sludge

    Directory of Open Access Journals (Sweden)

    Hussein I. Abdel-Shafy


    The sewage sludge samples were separated from the sewage water of the pilot plant at the National Research Centre, TDC site. The effect of heavy metals on the biogas production of the anaerobic digester was studied. The inhibitory effect on the biogas production and toxic level of metals was determined in this study. The general ranking of heavy metal toxicity appears to be Hg > Cd > Cr (III. The present investigation reveals that heavy metals in addition to the anaerobic digester decreased the biogas production as an indication of efficiency of the process. A significant decrease in gas production and volatile organic matter removal was obtained. It was also noted that an accumulation of organic acid intermediates was obtained as a result of methanogenic bacterial inhibition. This accumulation was limited during the pulse feed of metals. This is due to the rapid poisoning of the active bacterial forms in the digester.

  1. Current Status of Trace Metal Pollution in Soils Affected by Industrial Activities

    Directory of Open Access Journals (Sweden)

    Ehsanul Kabir


    Full Text Available There is a growing public concern over the potential accumulation of heavy metals in soil, owing to rapid industrial development. In an effort to describe the status of the pollutions of soil by industrial activities, relevant data sets reported by many studies were surveyed and reviewed. The results of our analysis indicate that soils were polluted most significantly by metals such as lead, zinc, copper, and cadmium. If the dominant species are evaluated by the highest mean concentration observed for different industry types, the results were grouped into Pb, Zn, Ni, Cu, Fe, and As in smelting and metal production industries, Mn and Cd in the textile industry, and Cr in the leather industry. In most cases, metal levels in the studied areas were found to exceed the common regulation guideline levels enforced by many countries. The geoaccumulation index (Igeo, calculated to estimate the enrichment of metal concentrations in soil, showed that the level of metal pollution in most surveyed areas is significant, especially for Pb and Cd. It is thus important to keep systematic and continuous monitoring of heavy metals and their derivatives to manage and suppress such pollution.

  2. Growth, tolerance efficiency and phytoremediation potential of Ricinus communis (L.) and Brassica juncea (L.) in salinity and drought affected cadmium contaminated soil. (United States)

    Bauddh, Kuldeep; Singh, Rana P


    We have previously reported that Ricinus communis (castor) is more tolerant to soil cadmium (Cd) and more efficient for Cd phytoremediation than Brassica juncea (Indian mustard) (Bauddh and Singh, 2012). In the present study, R. communis was found more tolerant to salinity and drought in presence of Cd and removed more Cd in a given time than Indian mustard. R. communis produced 23 and twelve folds higher biomass in terms of fresh weight and dry weight, respectively than that in B. juncea during three months when grown in Cd contaminated soil in presence of 100mM NaCl salinity and ten day water withdrawal based drought at 90 day after sowing (DAS). Castor plants showed stronger self-protection ability in form of proline bioaccumulation (r(2)=0.949) than Indian mustard (r(2)=0.932), whereas a lower r(2) for malondialdehyde (MDA) and total soluble protein in R. communis (r(2)=0.914 and r(2)=0.915, respectively) than that of B. juncea (r(2)=0.947 and r(2)=0.927, respectively) indicated a greater damage to cell membrane in Indian mustard during the multiple stress conditions. Though, the amount of Cd accumulated in the roots and shoots of Indian mustard was higher as per unit biomass than that in castor, total removal of the metal from soil was much higher in castor on per plant basis in the same period in presence of the stresses. R. communis accumulated about seventeen and 1.5 fold higher Cd in their roots and shoots, respectively than that of B. juncea in 90 DAS under the multiple stresses. Salinity alone enhanced Cd uptake, whereas drought stress reduced its uptake in both the plants.

  3. NMR-based metabolomics and LC-MS/MS quantification reveal metal-specific tolerance and redox homeostasis in Chlorella vulgaris. (United States)

    Zhang, Wenlin; Tan, Nicole G J; Li, Sam F Y


    Live green algae are promising candidates for phytoremediation, but a suitable algal species which bio-accumulates high concentrations of heavy metals, and survives well in industrial water is yet to be identified. Potential metabolic engineering may be applied to improve algal phytoremediation performance, but the metal tolerance and bioaccumulation mechanisms in green algae have to be first fully understood. In this study, NMR-based metabolomics was used to study the effect of different metal species (copper, cadmium and lead) and metal concentrations in green microalgae, Chlorella vulgaris. High Cu concentrations influenced substantial decrease in organic osmolytes (betaine and glycerophosphocholine), which indicated Cu-induced redox imbalance. Accompanying redox imbalance, growth inhibition and photosynthesis impairments in Cu-spiked C. vulgaris revealed a clear relationship between Cu toxicity and redox homeostasis. As these metabolic changes were less prominent in Cd and Pb-spiked cultures, we inferred metal-specific toxicity in C. vulgaris, where redox active Cu(2+) is more potent than non-redox active Cd(2+) and Pb(2+) in causing redox imbalance. Subsequently, ICP-MS and LC-MS/MS quantification shed light on the metal-specific bioaccumulation and detoxification mechanisms. The metal bioconcentration factor (BCF) correlated well with the phytochelatin (PC) content in Cu and Cd-spiked C. vulgaris biomass. High BCF and PC levels with increasing Cu and Cd exposure concentrations indicated that PCs played a significant role in Cu and Cd bioaccumulation and detoxification. In contrast, the undetectable PC levels in Pb-spiked cultures despite high Pb BCF suggest an alternative detoxification mechanism for Pb: either by passive absorption to the algal cell wall or interaction with glutathione (GSH).

  4. 菌根真菌重金属耐性机制研究进展%Underlying Mechanisms of the Heavy Metal Tolerance of Mycorrhizal Fungi

    Institute of Scientific and Technical Information of China (English)

    陈保冬; 孙玉青; 张莘; 伍松林


    菌根真菌在自然界中广泛存在,能与大多数陆地植物形成共生体,菌根共生体系对于植物适应各种逆境胁迫具有重要意义。在重金属污染土壤中通常也能发现菌根真菌,某些菌根真菌对重金属表现出较强的耐受性,在污染土壤修复方面显示出应用潜力。本文从生境选择、生理适应、功能基因表达调控等层面综述了菌根真菌重金属耐性机制方面的最新研究进展,并对今后的研究方向进行了展望,旨在推进相关机制研究及菌根技术在重金属污染土壤修复中的应用。%Mycorrhizal fungi are ubiquitous in natural ecosystems and can form symbiotic associations with the majority of terrestrial plants. They can be detected even in heavy metal-contaminated soils, while some fungal strains show strong heavy metal tolerance and could potentially be used in bioremediation of contaminated soils. We reviewed current research progresses in the underlying mechanisms of heavy metal tolerance of mycorrhizal fungi, with focuses on habitat selection, physiological adaptation and functional genes. Future research perspectives were proposed to promote the basic research and development of mycorrhizal technology for remediation of heavy metal-contaminated soils.

  5. How Does Metallicity Affect the Gas and Dust Properties of Galaxies?

    CERN Document Server

    Madden, Suzanne C; Remy-Ruyer, Aurelie


    Comparison of the ISM properties of a wide range of metal-poor galaxies with normal metal-rich galaxies reveals striking differences. We find that the combination of the low dust abundance and the active star formation results in a very porous ISM filled with hard photons, heating the dust in dwarf galaxies to overall higher temperatures than their metal-rich counterparts. This results in photodissociation of molecular clouds to greater depths, leaving relatively large PDR envelopes and difficult-to-detect CO cores. From detailed modeling of the low-metallicity ISM, we find significant fractions of CO-dark H2 - a reservoir of molecular gas not traced by CO, but present in the [CII] and [CI]-emitting envelopes. Self-consistent analyses of the neutral and ionized gas diagnostics along with the dust SED is the necessary way forward in uncovering the multiphase structure of galaxies

  6. Biotherapeutic formulation factors affecting metal leachables from stainless steel studied by design of experiments. (United States)

    Zhou, Shuxia; Evans, Brad; Schöneich, Christian; Singh, Satish K


    Trace amounts of metals are inevitably present in biotherapeutic products. They can arise from various sources. The impact of common formulation factors such as protein concentration, antioxidant, metal chelator concentration and type, surfactant, pH, and contact time with stainless steel on metal leachables was investigated by a design of experiments approach. Three major metal leachables, iron, chromium, and nickel were monitored by inductively coupled plasma-mass spectrometry. It was observed that among all the tested factors, contact time, metal chelator concentration, and protein concentration were statistically significant factors with higher temperature resulting in higher levels of leached metals. Within a pH range of 5.5-6.5, solution pH played a minor role for chromium leaching at 25°C. No statistically significant difference was observed due to type of chelator, presence of antioxidant, or surfactant. In order to optimize a biotherapeutic formulation to achieve a target drug product shelf life with acceptable quality, each formulation component must be evaluated for its impact.

  7. Flood-related contamination in catchments affected by historical metal mining: an unexpected and emerging hazard of climate change. (United States)

    Foulds, S A; Brewer, P A; Macklin, M G; Haresign, W; Betson, R E; Rassner, S M E


    Floods in catchments affected by historical metal mining result in the remobilisation of large quantities of contaminated sediment from floodplain soils and old mine workings. This poses a significant threat to agricultural production and is preventing many European river catchments achieving a 'good chemical and ecological status', as demanded by the Water Framework Directive. Analysis of overbank sediment following widespread flooding in west Wales in June 2012 showed that flood sediments were contaminated above guideline pollution thresholds, in some samples by a factor of 82. Most significantly, silage produced from flood affected fields was found to contain up to 1900 mg kg(-1) of sediment associated Pb, which caused cattle poisoning and mortality. As a consequence of climate related increases in flooding this problem is likely to continue and intensify. Management of contaminated catchments requires a geomorphological approach to understand the spatial and temporal cycling of metals through the fluvial system.

  8. Tolerating Zero Tolerance? (United States)

    Moore, Brian N.


    The concept of zero tolerance dates back to the mid-1990s when New Jersey was creating laws to address nuisance crimes in communities. The main goal of these neighborhood crime policies was to have zero tolerance for petty crime such as graffiti or littering so as to keep more serious crimes from occurring. Next came the war on drugs. In federal…

  9. Performance Factors and Sulfur Tolerance of Metal Supported Solid Oxide Fuel Cells with Nanostructured Ni:GDC Infiltrated Anodes

    DEFF Research Database (Denmark)

    Nielsen, Jimmi; Sudireddy, Bhaskar Reddy; Hagen, Anke;


    stainless steel (FeCr) and showed excellent performance characteristics at 650ºC with area specific resistances (ASR) of 0.35 Ωcm2 and 0.7 Ωcm2 respectively. The sulfur tolerance testing was performed by addition/removal of 2, 5, and 10 ppm H2S in hydrogen based fuel under galvanostatic operation...

  10. Performance Factors and Sulfur Tolerance of Metal Supported Solid Oxide Fuel Cells with Nanostructured Ni:GDC Infiltrated Anodes

    DEFF Research Database (Denmark)

    Nielsen, Jimmi; Sudireddy, Bhaskar Reddy; Hagen, Anke;


    stainless steel (FeCr) and showed excellent performance characteristics at 650°C with fuel utilization corrected area specific resistances of 0.35 Ωcm2 and 0.7 Ωcm2 respectively. The sulfur tolerance testing was performed by periodic addition of 2, 5, and 10 ppm H2S in hydrogen based fuel under...

  11. Stabilization/solidification of heavy metals in sludge ceramsite and leachability affected by oxide substances. (United States)

    Xu, Guoren; Zou, Jinlong; Li, Guibai


    To investigate stabilization of heavy metals in ceramsite made from wastewater treatment sludge (WWTS) and drinking water treatment sludge (DWTS), leaching tests were conducted to find out the effect of SiO2:Al2O3, acidic oxides (SiO2 and Al2O3), Fe2O3: CaO:MgO, and basic oxides (Fe2O3, CaO, and MgO) on the binding ability of heavy metals. Results show that as ratios of SiO2: Al2O3 decrease, leaching contents of Cu and Pb increase, while leaching contents of Cd and Cr first decrease and then increase; under the variation of Fe2O3:CaO:MgO (Fe2O3 contents decrease), leaching contents of Cd, Cu, and Pb increase, while leaching contents of Cr decrease. Acidic and basic oxide leaching results show that higher contents of Al2O3, Fe2O3, and MgO are advantageous to improve the stability of heavy metals, while the binding capacity for Cd, Cu, and Pb is significantly reduced at higher contents of SiO2 and CaO. The solidifying efficiencies of heavy metals are improved by crystallization, and the main compounds in ceramsite are crocoite, chrome oxide, cadmium silicate, and copper oxide. These results can be considered as a basic understanding for new technologies of stabilization of heavy metals in heavily polluted WWTS.

  12. Fault Tolerant Feedback Control

    DEFF Research Database (Denmark)

    Stoustrup, Jakob; Niemann, H.


    An architecture for fault tolerant feedback controllers based on the Youla parameterization is suggested. It is shown that the Youla parameterization will give a residual vector directly in connection with the fault diagnosis part of the fault tolerant feedback controller. It turns out...... that there is a separation be-tween the feedback controller and the fault tolerant part. The closed loop feedback properties are handled by the nominal feedback controller and the fault tolerant part is handled by the design of the Youla parameter. The design of the fault tolerant part will not affect the design...... of the nominal feedback con-troller....

  13. Factors affecting the strength of multipass low-alloy steel weld metal (United States)

    Krantz, B. M.


    The mechanical properties of multipass high-strength steel weld metals depend upon several factors, among the most important being: (1) The interaction between the alloy composition and weld metal cooling rate which determines the as-deposited microstructure; and (2) the thermal effects of subsequent passes on each underlying pass which alter the original microstructure. The bulk properties of a multipass weld are therefore governed by both the initial microstructure of each weld pass and its subsequent thermal history. Data obtained for a high strength low alloy steel weld metal confirmed that a simple correlation exists between mechanical properties and welding conditions if the latter are in turn correlated as weld cooling rate.


    Institute of Scientific and Technical Information of China (English)

    冯保民; 麻密


    Under heavy metal stress, higher plants initiate a set of defense responses, among which biosynthesis of phytochelatins (PCs) is important. PCs are rich in cystein and biosynthesized by phytochelatin synthase. The chemical structure of PCs and their ability to form complexes with a large range of metal ions is clear. Up to now, these peptides are known to play an important role in both endogenous metal ion homeostasis and heavy metal ion detoxification. The mechanism of cadmium tolerance is illustrated in detail. A model of this mechanism suggested that the detoxification process of cadmium include such steps as PCs induction, transport of cadmium into the tonoplast, formation of the HMW-Cd-PCs complexes and sequestration in vacuole. At the same time, PCs also have other functions, such as detoxification of arsenic, protecting enzyme from metal ion inhibition and supplying metal ion as a cofactor to the enzyme potentially. However, a lot of questions about its biological function remain to be answered. In 1999, three independent labs isolated the genes encoding the PCs synthase. This breakthrough of plant heavy metal tolerance research gave us a chance to further study the heavy metal tolerance mechanism. All the results from the reserch of PCs have a ffreat application potential in phytoremidation. Fig 1, Ref 25

  15. How metal substitution affects the enzymatic activity of catechol-o-methyltransferase.

    Directory of Open Access Journals (Sweden)

    Manuel Sparta

    Full Text Available Catechol-O-methyltransferase (COMT degrades catecholamines, such as dopamine and epinephrine, by methylating them in the presence of a divalent metal cation (usually Mg(II, and S-adenosyl-L-methionine. The enzymatic activity of COMT is known to be vitally dependent on the nature of the bound metal: replacement of Mg(II with Ca(II leads to a complete deactivation of COMT; Fe(II is slightly less than potent Mg(II, and Fe(III is again an inhibitor. Considering the fairly modest role that the metal plays in the catalyzed reaction, this dependence is puzzling, and to date remains an enigma. Using a quantum mechanical / molecular mechanical dynamics method for extensive sampling of protein structure, and first principle quantum mechanical calculations for the subsequent mechanistic study, we explicate the effect of metal substitution on the rate determining step in the catalytic cycle of COMT, the methyl transfer. In full accord with experimental data, Mg(II bound to COMT is the most potent of the studied cations and it is closely followed by Fe(II, whereas Fe(III is unable to promote catalysis. In the case of Ca(II, a repacking of the protein binding site is observed, leading to a significant increase in the activation barrier and higher energy of reaction. Importantly, the origin of the effect of metal substitution is different for different metals: for Fe(III it is the electronic effect, whereas in the case of Ca(II it is instead the effect of suboptimal protein structure.

  16. Repeated annual paper mill and alkaline residuals application affects soil metal fractions. (United States)

    Gagnon, Bernard; Robichaud, Annie; Ziadi, Noura; Karam, Antoine


    The application of industrial residuals in agriculture may raise concerns about soil and crop metal accumulation. A complete study using a fractionation scheme would reveal build-up in metal pools occurring after material addition and predict the transformation of metals in soil between the different forms and potential metal release into the environment. An experimental study was conducted from 2000 to 2008 on a loamy soil at Yamachiche, Quebec, Canada, to evaluate the effects of repeated annual addition of combined paper mill biosolids when applied alone or with several liming by-products on soil Cu, Zn, and Cd fractions. Wet paper mill biosolids at 0, 30, 60, or 90 Mg ha and calcitic lime, lime mud, or wood ash, each at 3 Mg ha with 30 Mg paper mill biosolids ha, were surface applied after seeding. The soils were sampled after 6 (soybean [ (L.) Merr.]) and 9 [corn ( L.)] crop years and analyzed using the Tessier fractionation procedure. Results indicated that biosolids addition increased exchangeable Zn and Cd, carbonate-bound Cd, Fe-Mn oxide-bound Zn and Cd, organically bound Cu and Zn, and total Zn and Cd fractions but decreased Fe-Mn oxide-bound Cu in the uppermost 30-cm layer. With liming by-products, there was a shift from exchangeable to carbonate-bound forms. Even with very small metals addition, paper mill and liming materials increased the mobility of soil Zn and Cd after 9 yr of application, and this metal redistribution resulted into higher crop grain concentrations.

  17. Occupational accidents and affecting factors of metal industry in a factory in Ankara

    Directory of Open Access Journals (Sweden)

    Mustafa N. Ilhan


    Full Text Available Abstract Objective:According to the statistics of the Social Security Institution, 18672 occupational accidents occurred in the metal industry in 2008 in Turkey. Whereas 78 of these accidents resulted in death, 252 people became permanently incapable of working. In 2008, 369677 working days were lost as a result of occupational accidents. Evaluating the reasons for and the results of accidents in the metal industry and contributing to the development of recommendations for prevention in accordance with the information obtained. Method: The study was conducted with 201 of 210 workers working in heavy metal manufacturing and construction in the building company between April 2008 and June 2008. Results: The frequency of occupational accidents among the metal workers was 22% between January 2007 and June 2008. The reasons for the workers’ accidents are listed as; insufficient use of personal protective equipment (44%, carelessness (37%, and personal reasons, not to be taken of security measures at machines and looms/ unsuitable machines (both 17%.Conclusion: The study demonstrates that the accidents mostly occur because of failure to use of personal protective equipment, insufficient vocational training. Key Words: Occupational, accident, metal industry, preventionAnkara’da bir metal sanayi fabrikasında iş kazaları ve etkileyen faktörler Özet Amaç: 2008 yılında Sosyal Güvenlik Kurumu’nun verilerine göre metal sanayisinde 18672 iş kazası meydana gelmiş ve 369677 işgünü kaybı olmuştur.  Bu kazalardan 78 tanesi ölümle sonuçlanırken, 252 kişi kalıcı olarak işgöremez hale gelmiştir. Metal sanayisinde meydana gelen kazaların sebep ve sonuçlarını inceleyerek, elde edilen bilgiler doğrultusunda kazaların önlenmesine yönelik tavsiyelerin geliştirilmesi amaçlanmıştır. Yöntem: Araştırma, Ankara’da faaliyet gösteren ağır metal imalat, konstrüksiyon ve inşaat sanayi şirketinde 2008 Nisan-2008 Haziran d

  18. Trace metal partitioning over a tidal cycle in an estuary affected by acid mine drainage (Tinto estuary, SW Spain)

    Energy Technology Data Exchange (ETDEWEB)

    Hierro, A. [Department of Physics, Universitat Autònoma de Barcelona, 08193 Bellaterra (Spain); Department of Applied Physics, Facultad de Ciencias Experimentales, University of Huelva, Campus de El Carmen, Campus de Excelencia Internacional del Mar CEIMAR, 21071 Huelva (Spain); Olías, M., E-mail: [Department of Geodynamics and Paleontology, Facultad de Ciencias Experimentales, University of Huelva, Campus de El Carmen, Campus de Excelencia Internacional del Mar CEIMAR, 21071 Huelva (Spain); Cánovas, C.R. [Department of Geodynamics and Paleontology, Facultad de Ciencias Experimentales, University of Huelva, Campus de El Carmen, Campus de Excelencia Internacional del Mar CEIMAR, 21071 Huelva (Spain); Martín, J.E.; Bolivar, J.P. [Department of Applied Physics, Facultad de Ciencias Experimentales, University of Huelva, Campus de El Carmen, Campus de Excelencia Internacional del Mar CEIMAR, 21071 Huelva (Spain)


    The Tinto River estuary is highly polluted with the acid lixiviates from old sulphide mines. In this work the behaviour of dissolved and particulate trace metals under strong chemical gradients during a tidal cycle is studied. The pH values range from 4.4 with low tide to 6.9 with high tide. Precipitation of Fe and Al is intense during rising tides and As and Pb are almost exclusively found in the particulate matter (PM). Sorption processes are very important in controlling the mobility (and hence bioavailability) of some metals and particularly affect Cu below pH 6. Above pH ∼ 6 Cu is desorbed, probably by the formation of Cu(I)–chloride complexes. Although less pronounced than Cu, also Zn desorption above pH 6.5 seems to occur. Mn and Co are affected by sorption processes at pH higher than ca. 6. Cd behaves conservatively and Ni is slightly affected by sorption processes. - Highlights: • The Tinto estuary shows strong pH gradients and high trace elements concentrations. • PM has a hysteretic relationship with tides and high contents of Fe, Al, As and Pb. • Co and Mn are controlled by river and sea water mixing and sorption processes. • Sorption processes strongly affect Cu below pH 6, above this value Cu is desorpted. • Cadmium behaves conservatively along the pH range studied (4.4–6.9)

  19. Heavy metals in sediments of a large, turbid tropical lake affected by anthropogenic discharges

    Energy Technology Data Exchange (ETDEWEB)

    Rosales-Hoz, L.; Carranza-Edwards, A.; Lopez-Hernandez, M. [Universidad Nacional Autonoma de Mexico, Mexico City (Mexico). Inst. de Ciencias del Mar y Limnologia


    Bottom-water data and trace metal concentration of Cu, Cr, Ni, Pb, Co, Zn, and organic matter in surficial sediment samples from 13 sampling stations of Lake Chapala in Mexico were studied. The lake is turbid with a great amount of flocculated sediments as a result of wind mixing, sediment re-suspension, and Lerma River discharges. Al distribution pattern in sediments was used as an indicator of the Lerma River discharges into Lake Chapala. The highest values of Cu (33.27 ppm), Cr (81.94 ppm), Pb (99.8 ppm), and Zn (149.7 ppm) were detected in sediments near the lake outlet. The bioavailable metal fraction is low for all metals except Pb, which shows 65-93% of the total metal concentration in bioavailable form. The minimum energy zone in the lake was related to organic matter concentration and was located in the SE part of the lake. An analysis of the studied parameters shows two zones: eastern zone (fluvio-deltaic) and central-western zone (lacustrine). (orig.)

  20. Biological Processes Affecting Bioaccumulation, Transfer, and Toxicity of Metal Contaminants in Estuarine Sediments (United States)


    concentrations of Hg than do benthic food webs in relatively uncontaminated systems ( Karimi et al., 2007). However, whether this is true of contaminated...sediment-bound metals to marine bivalve molluscs: An overview. Estuaries 27, 826-838. Karimi , R., Chen, C.Y., Pickhardt, P.C., Fisher, N.S., Folt, C.L

  1. Processes affecting the distribution and speciation of heavy metals in the Rhine/Meuse estuary

    NARCIS (Netherlands)

    Paalman, M.A.A.


    When rivers drain areas with a high population density the sediments are often contaminated with heavy metals, such as chromium, cobalt, nickel, copper, zinc, cadmium, mercury and lead. The extent and seriousness of sediment contamination is most pronounced in the lower reaches of rivers, where rive

  2. Calibration of radiographs by a reference metal ball affects preoperative selection of implant size. (United States)

    Schropp, Lars; Stavropoulos, Andreas; Gotfredsen, Erik; Wenzel, Ann


    The aim was to evaluate the impact of a reference ball for calibration of periapical and panoramic radiographs on preoperative selection of implant size for three implant systems. Presurgical digital radiographs (70 panoramic, 43 periapical) from 70 patients scheduled for single-tooth implant treatment, recorded with a metal ball placed in the edentulous area, were evaluated by three observers with the intent to select the appropriate implant size. Four reference marks corresponding to the margins of the metal ball were manually placed on the digital image by means of computer software. Additionally, an implant with proper dimensions for the respective site was outlined by manually placing four reference marks. The diameter of the metal ball and the unadjusted length and width of the implant were calculated. Implant size was adjusted according to a "standard" calibration method (SCM; magnification factor 1.25 in panoramic images and 1.05 in periapical images) and according to a reference ball calibration method (RCM; true magnification). Based on the unadjusted as well as the adjusted implant dimensions, the implant size was selected among those available in a given implant system. For periapical radiographs, when comparing SCM and RCM with unadjusted implant dimensions, implant size changed in 42% and 58%, respectively. When comparing SCM and RCM, implant size changed in 24%. For panoramic radiographs, comparing SCM and RCM changed implant size in 48%. The use of a reference metal ball for calibration of periapical and panoramic radiographs when selecting implant size during treatment planning might be advantageous.

  3. Stability and heavy metal distribution of soil aggregates affected by application of apatite, lime, and charcoal. (United States)

    Cui, Hongbiao; Ma, Kaiqiang; Fan, Yuchao; Peng, Xinhua; Mao, Jingdong; Zhou, Dongmei; Zhang, Zhongbin; Zhou, Jing


    Only a few studies have been reported on the stability and heavy metal distribution of soil aggregates after soil treatments to reduce the availability of heavy metals. In this study, apatite (22.3 t ha(-1)), lime (4.45 t ha(-1)), and charcoal (66.8 t ha(-1)) were applied to a heavy metal-contaminated soil for 4 years. The stability and heavy metal distribution of soil aggregates were investigated by dry and wet sieving. No significant change in the dry mean weight diameter was observed in any treatments. Compared with the control, three-amendment treatments significantly increased the wet mean weight diameter, but only charcoal treatment significantly increased the wet aggregate stability. The soil treatments increased the content of soil organic carbon, and the fraction 0.25-2 mm contained the highest content of soil organic carbon. Amendments' application slightly increased soil total Cu and Cd, but decreased the concentrations of CaCl2 -extractable Cu and Cd except for the fraction 2 and 0.25-2 mm contained the highest concentrations of CaCl2-extractable Cu and Cd, accounted for about 74.5-86.8 % of CaCl2-extractable Cu and Cd in soil. The results indicated that amendments' application increased the wet soil aggregate stability and decreased the available Cu and Cd. The distribution of available heavy metals in wet soil aggregates was not controlled by soil aggregate stability, but possibly by soil organic carbon.

  4. Factors affecting the bond strength of denture base and reline acrylic resins to base metal materials

    Directory of Open Access Journals (Sweden)

    Naomi Tanoue


    Full Text Available OBJECTIVE: The shear bond strengths of two hard chairside reline resin materials and an auto-polymerizing denture base resin material to cast Ti and a Co-Cr alloy treated using four conditioning methods were investigated. MATERIAL AND METHODS: Disk specimens (diameter 10 mm and thickness 2.5 mm were cast from pure Ti and Co-Cr alloy. The specimens were wet-ground to a final surface finish of 600 grit, air-dried, and treated with the following bonding systems: 1 air-abraded with 50-70-µm grain alumina (CON; 2 1 + conditioned with a primer, including an acidic phosphonoacetate monomer (MHPA; 3 1 + conditioned with a primer including a diphosphate monomer (MDP; 4 treated with a tribochemical system. Three resin materials were applied to each metal specimen. Shear bond strengths were determined before and after 10,000 thermocycles. RESULTS: The strengths decreased after thermocycling for all combinations. Among the resin materials assessed, the denture base material showed significantly (p<0.05 greater shear bond strengths than the two reline materials, except for the CON condition. After 10,000 thermocycles, the bond strengths of two reline materials decreased to less than 10 MPa for both metals. The bond strengths of the denture base material with MDP were sufficient: 34.56 MPa for cast Ti and 38.30 for Co-Cr alloy. CONCLUSION: Bonding of reline resin materials to metals assessed was clinically insufficient, regardless of metal type, surface treatment, and resin composition. For the relining of metal denture frameworks, a denture base material should be used.

  5. Oxidative damage of workers in secondary metal recovery plants affected by smoking status and joining the smelting work. (United States)

    Chia, Taipau; Hsu, Ching Yi; Chen, Hsiu Ling


    In Taiwan, secondary copper smelters and zinc recovery plants primarily utilize recovering metal from scrap and dross, and handles mostly fly ash and slag with high temperature to produce ZnO from the iron and steel industry. The materials may contain organic impurities, such as plastic and organic chloride chemicals, and amounts of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) are produced during the smelting process. Therefore, secondary metal recovery industries are major emission sources of PCDD/Fs, which may have been demonstrated to elicit oxidative stress and to involve the production of plasma malondialdehyde (MDA). Many studies have also indicated that the intake of antioxidants, smoking, age and exposure to environmental pollutants may be implicated to DNA damage or lipid peroxidation. This study therefore aims to elucidate the roles of occupational exposure like joining the smelting work, age, smoking and alcohol status, and antioxidant intake on oxidative damage in secondary metal recovery workers in Taiwan. 73 workers were recruited from 2 secondary metal recovery plants. The analysis of 8-hydroxydeoxyguanosine (8-OH-dG) in urine, DNA strand breakage (comet assay) and lipid peroxidation (MDA) in blood samples were completed for all of the workers. The results showed that the older subjects exhibited significantly lower levels of 8-OH-dG and MDA than younger subjects. Our investigation also showed that working departments were in related to plasma MDA and DNA strand breakage levels of nonsmokers, however, the observation become negligible in smokers. And it is implicated that cigarette type might affect 8-OH-dG levels in secondary metal recovery workers. Since, adding to results above, the MDA level in production workers was significantly higher than those in managerial departments, it is important for the employers to make efforts on improving occupational environments or serving protective equipments to protect workers

  6. Soluble organic carbon and pH of organic amendments affect metal mobility and chemical speciation in mine soils. (United States)

    Pérez-Esteban, Javier; Escolástico, Consuelo; Masaguer, Alberto; Vargas, Carmen; Moliner, Ana


    We evaluated the effects of pH and soluble organic carbon affected by organic amendments on metal mobility to find out the optimal conditions for their application in the stabilization of metals in mine soils. Soil samples (pH 5.5-6.2) were mixed with 0, 30 and 60 th a(-1) of sheep-horse manure (pH 9.4) and pine bark compost (pH 5.7). A single-step extraction procedure was performed using 0.005 M CaCl2 adjusted to pH 4.0-7.0 and metal speciation in soil solution was simulated using NICA-Donnan model. Sheep-horse manure reduced exchangeable metal concentrations (up to 71% Cu, 75% Zn) due to its high pH and degree of maturity, whereas pine bark increased them (32% Cu, 33% Zn). However, at increasing dose and hence pH, sheep-horse manure increased soluble Cu because of higher soluble organic carbon, whereas soluble Cu and organic carbon increased at increasing dose and correspondingly decreasing pH in pine bark and non-amended treatments. Near the native pH of these soils (at pH 5.8-6.3), with small doses of amendments, there was minimum soluble Cu and organic carbon. Pine bark also increased Zn solubility, whereas sheep-horse manure reduced it as soluble Zn always decreased with increasing pH. Sheep-horse manure also reduced the proportion of free metals in soil solution (from 41% to 4% Cu, from 97% to 94% Zn), which are considered to be more bioavailable than organic species. Sheep-horse manure amendment could be efficiently used for the stabilization of metals with low risk of leaching to groundwater at low doses and at relatively low pH, such as the native pH of mine soils.

  7. Cell surface-engineered yeast displaying a histidine oligopeptide (hexa-His) has enhanced adsorption of and tolerance to heavy metal ions. (United States)

    Kuroda, K; Shibasaki, S; Ueda, M; Tanaka, A


    A histidine oligopeptide (hexa-His) with the ability to chelate divalent heavy metal ions was displayed on the yeast cell surface for the purpose of enhanced adsorption of heavy metal ions. We genetically fused a hexa-His-encoding gene with the gene encoding the C-terminal half of alpha-agglutinin that includes a glycosylphosphatidylinositol anchor attachment signal sequence and attached the hexa-His peptide on the cell wall of Saccharomyces cerevisiae. This surface-engineered yeast adsorbed three to eight times more copper ions than the parent strain and was more resistant to copper (4 mM) than the parent (below 1 mM at pH 7.8). It was possible to recover about a half of the copper ions adsorbed by whole cells with EDTA treatment without disintegrating the cells. Thus, we succeeded in constructing a novel yeast cell with both tolerance to toxic contaminants and enhanced adsorption of metal ions onto the cell surface.

  8. Analysis of Operational Parameters Affecting the Sulfur Content in Hot Metal of the COREX Process (United States)

    Wu, Shengli; Wang, Laixin; Kou, Mingyin; Wang, Yujue; Zhang, Jiacong


    The COREX process, which has obvious advantages in environment protection, still has some disadvantages. It has a higher sulfur content in hot metal (HM) than the blast furnace has. In the present work, the distribution and transfer of sulfur in the COREX have been analyzed and several operational parameters related to the sulfur content in HM ([pct S]) have been obtained. Based on this, the effects of the coal rate, slag ratio, temperature of HM, melting rate, binary basicity ( R 2), the ratio of MgO/Al2O3, utilization of reducing gas, top gas consumption per ton burden solid, metallization rate, oxidation degree of reducing gas, and coal and DRI distribution index on the sulfur content in HM are investigated. What's more, a linear model has been developed and subsequently used for predicting and controlling the S content in HM of the COREX process.

  9. Aspartate buffer and divalent metal ions affect oxytocin in aqueous solution and protect it from degradation

    DEFF Research Database (Denmark)

    Avanti, Christina; Oktaviani, Nur Alia; Hinrichs, Wouther L.J.


    is improved by the addition of divalent metal ions (unpublished results). The stabilizing effect of Zn2+ was by far superior compared to that of Mg2+. In addition, it was found that stabilization correlated well with the ability of the divalent metal ions to interact with oxytocin in aspartate buffer...... favorable. These interactions may explain the protection of the disulfide bridge against intermolecular reactions that lead to dimerization.Mg or Zn, using 2D NOESY, TOCSY, H-C HSQC and H- N HSQC NMR spectroscopy. Almost all H, C and N resonances of oxytocin could be assigned using HSQC spectroscopy...... that the carboxylate group of aspartate neutralizes the positive charge of the N-terminus of Cys, allowing the interactions with Zn to become more favorable. These interactions may explain the protection of the disulfide bridge against intermolecular reactions that lead to dimerization....

  10. Trace metal distribution in pristine permafrost-affected soils of the Lena River Delta and its Hinterland, Northern Siberia, Russia

    Directory of Open Access Journals (Sweden)

    I. Antcibor


    Full Text Available Soils are an important compartment of ecosystems and have the ability to immobilize chemicals preventing their movement to other environment compartments. Predicted climatic changes together with other anthropogenic influences on Arctic terrestrial environments may affect biogeochemical processes enhancing leaching and migration of trace elements in permafrost-affected soils. This is especially important since the Arctic ecosystems are considered to be very sensitive to climatic changes as well as to chemical contamination. This study characterizes background levels of trace metals in permafrost-affected soils of the Lena River Delta and its hinterland in northern Siberia (73.5° N–69.5° N representing a remote region far from evident anthropogenic trace metal sources. Investigations on total element contents of iron (Fe, arsenic (As, manganese (Mn, zinc (Zn, nickel (Ni, copper (Cu, lead (Pb, cadmium (Cd, cobalt (Co and mercury (Hg in different soil types developed in different geological parent materials have been carried out. The highest concentrations of the majority of the measured elements were observed in soils belonging to ice-rich permafrost sediments formed during the Pleistocene (ice-complex in the Lena River Delta region. Correlation analyses of trace metal concentrations and soil chemical and physical properties at a Holocene estuarine terrace and two modern floodplain levels in the southern-central Lena River Delta (Samoylov Island showed that the main factors controlling the trace metal distribution in these soils are organic matter content, soil texture and contents of iron and manganese-oxides. Principal Component Analysis (PCA revealed that soil oxides play a significant role in trace metal distribution in both top and bottom horizons. Occurrence of organic matter contributes to Cd binding in top soils and Cu binding in bottom horizons. Observed ranges of the background concentrations of the majority of trace elements were

  11. Functional and numerical responses ofCyrtorhinus lividipennis to eggs ofNilaparvata lugens are not affected by genetically modiifed herbicide-tolerant rice

    Institute of Scientific and Technical Information of China (English)

    JIANG Xian-bin; LONG Li-ping; HUANG Qian; LING Yan; CHEN Yu-chong; XIAO Guo-ying; HUANG Suo-sheng; WU Bi-qiu; HUANG Feng-kuan; CAI Jian-he


    To safely and sustainably utilize genetic breeding techniques for crop production, greater understanding of the potential effects of geneticaly modiifed herbicide-tolerant (GMHT) crops on the ecological functions of predators is required. In the laboratory, we examined the functional and numerical responses ofCyrtorhinus lividipennis Reuter to eggs of brown plan-thopper (BPH), Nilaparvata lugens (Stål), which were reared on GMHT rice Bar68-1; the untransformed parental cultivar, D68; or a BPH-susceptive rice variety, Taichung Native 1. Al stages of nymphs and female adultof C. lividipennis, either on GMHT rice or control plants, exhibited typical type II functional responses when fed on BPH eggs; the attacking rate and handling time ofC. lividipennis on GMHT rice Bar68-1 was not signiifcantly different from that on D68. The numerical responses ofC. lividipennis on GMHT rice or controls ift Beddington’s model; there were no signiifcant differences in the parameters of numerical responses between GMHT rice Bar68-1 and D68. The results indicated that the functional and numerical responses ofC. lividipennis to BPH eggs are not affected by GMHT rice Bar68-1.

  12. Metabolic rate and hypoxia tolerance are affected by group interactions and sex in the fruit fly (Drosophila melanogaster): new data and a literature survey. (United States)

    Burggren, Warren; Souder, BriAnna M; Ho, Dao H


    Population density and associated behavioral adjustments are potentially important in regulating physiological performance in many animals. In r-selected species like the fruit fly (Drosophila), where population density rapidly shifts in unpredictable and unstable environments, density-dependent physiological adjustments may aid survival of individuals living in a social environment. Yet, how population density (and associated social behaviors) affects physiological functions like metabolism is poorly understood in insects. Additionally, insects often show marked sexual dimorphism (larger females). Thus, in this study on D. melanogaster, we characterized the effects of fly density and sex on both mass-specific routine oxygen consumption (V̇O2) and hypoxia tolerance (PCrit). Females had significantly lower routine V̇O2 (∼4 μl O2·mg(-1)·h(-1)) than males (∼6 μl O2·mg(-1)·h(-1)) at an average fly density of 28 flies·respirometer chamber(-1) However, V̇O2 was inversely related to fly density in males, with V̇O2 ranging from 4 to 11 μl O2·mg(-1)·h(-1) at a density of 10 and 40 flies·chamber(-1), respectively (r(2)=0.58, Pflies showed a similar but less pronounced effect, with a V̇O2 of 4 and 7 μl O2·mg(-1)·h(-1) at a density of 10 and 40 flies·chamber(-1), respectively (r(2)=0.43, P0.5) flies, with higher fly densities having lower PCrits An extensive survey of the literature on metabolism in fruit flies indicates that not all studies control for, or even report on, fly density and gender, both of which may affect metabolic measurements.

  13. Characteristics of metal-tolerant plant growth-promoting yeast (Cryptococcus sp. NSE1) and its influence on Cd hyperaccumulator Sedum plumbizincicola. (United States)

    Liu, Wuxing; Wang, Beibei; Wang, Qingling; Hou, Jinyu; Wu, Longhua; Wood, Jennifer L; Luo, Yongming; Franks, Ashley E


    Plant growth-promoting yeasts are often over looked as a mechanism to improve phytoremediation of heavy metals. In this study, Cryptococcus sp. NSE1, a Cd-tolerant yeast with plant growth capabilities, was isolated from the rhizosphere of the heavy metal hyperaccumulator Sedum plumbizincicola. The yeast exhibited strong tolerance to a range of heavy metals including Cd, Cu, and Zn on plate assays. The adsorption rate Cd, Cu, Zn by NSE1 was 26.1, 13.2, and 25.2 %, respectively. Irregular spines were formed on the surface of NSE1 when grown in MSM medium supplemented with 200 mg L(-1) Cd. NSE1 was capable of utilizing 1-aminocyclopropane-1-carboxylate (ACC) as a sole nitrogen source and was capable of solubilization of inorganic phosphate at rates of 195.2 mg L(-1). Field experiments demonstrated that NSE1 increased phytoremediation by increasing the biomass of Cd hyperaccumulator S. plumbizincicola (46 %, p Cd accumulation by S. plumbizincicola was increased from 19.6 to 31.1 mg m(-2) though no difference in the concentration of Cd in the shoot biomass was observed between NSE1 and control. A Cd accumulation ratio of 38.0 % for NSE1 and 17.2 % for control was observed. The HCl-extractable Cd and CaCl2-extractable Cd concentration in the soil of the NSE1 treatment were reduced by 39.2 and 29.5 %, respectively. Community-level physiology profiling, assessed using Biolog Eco plates, indicated functional changes to the rhizosphere community inoculated with NSE1 by average well color development (AWCD) and measurement of richness (diversity). Values of Shannon-Weiner index, Simpson index, and McIntosh index showed a slight but no significant increases. These results indicate that inoculation of NSE1 could increase the shoot biomass of S. plumbizincicola, enhance the Cd accumulation in S. plumbizincicola, and decrease the available heavy metal content in soils significantly without overall significant changes to the microbial community.

  14. Statistical evaluation of biogeochemical variables affecting spatiotemporal distributions of multiple free metal ion concentrationsin an urban estuary (United States)

    Free metal ion concentrations have been recognized as a better indicator of metal bioavailability in aquatic environments than total dissolved metal concentrations. However, our understanding of the determinants of free ion concentrations, especially in a metal mixture, is limite...

  15. Enhanced Heavy Metal Tolerance and Accumulation by Transgenic Sugar Beets Expressing Streptococcus thermophilus StGCS-GS in the Presence of Cd, Zn and Cu Alone or in Combination.

    Directory of Open Access Journals (Sweden)

    Dali Liu

    Full Text Available Phytoremediation is a promising means of ameliorating heavy metal pollution through the use of transgenic plants as artificial hyperaccumulators. A novel Streptococcus thermophilus γ-glutamylcysteine synthetase-glutathione synthetase (StGCS-GS that synthesizes glutathione (GSH with limited feedback inhibition was overexpressed in sugar beet (Beta vulgaris L., yielding three transgenic lines (s2, s4 and s5 with enhanced tolerance to different concentrations of cadmium, zinc and copper, as indicated by their increased biomass, root length and relative growth compared with wild-type plants. Transgenic sugar beets accumulated more Cd, Zn and Cu ions in shoots than wild-type, as well as higher GSH and phytochelatin (PC levels under different heavy metal stresses. This enhanced heavy metal tolerance and increased accumulation were likely due to the increased expression of StGCS-GS and consequent overproduction of both GSH and PC. Furthermore, when multiple heavy metal ions were present at the same time, transgenic sugar beets overexpressing StGCS-GS resisted two or three of the metal combinations (50 μM Cd-Zn, Cd-Cu, Zn-Cu and Cd-Zn-Cu, with greater absorption in shoots. Additionally, there was no obvious competition between metals. Overall, the results demonstrate the explicit role of StGCS-GS in enhancing Cd, Zn and Cu tolerance and accumulation in transgenic sugar beet, which may represent a highly promising new tool for phytoremediation.

  16. Enhanced Heavy Metal Tolerance and Accumulation by Transgenic Sugar Beets Expressing Streptococcus thermophilus StGCS-GS in the Presence of Cd, Zn and Cu Alone or in Combination. (United States)

    Liu, Dali; An, Zhigang; Mao, Zijun; Ma, Longbiao; Lu, Zhenqiang


    Phytoremediation is a promising means of ameliorating heavy metal pollution through the use of transgenic plants as artificial hyperaccumulators. A novel Streptococcus thermophilus γ-glutamylcysteine synthetase-glutathione synthetase (StGCS-GS) that synthesizes glutathione (GSH) with limited feedback inhibition was overexpressed in sugar beet (Beta vulgaris L.), yielding three transgenic lines (s2, s4 and s5) with enhanced tolerance to different concentrations of cadmium, zinc and copper, as indicated by their increased biomass, root length and relative growth compared with wild-type plants. Transgenic sugar beets accumulated more Cd, Zn and Cu ions in shoots than wild-type, as well as higher GSH and phytochelatin (PC) levels under different heavy metal stresses. This enhanced heavy metal tolerance and increased accumulation were likely due to the increased expression of StGCS-GS and consequent overproduction of both GSH and PC. Furthermore, when multiple heavy metal ions were present at the same time, transgenic sugar beets overexpressing StGCS-GS resisted two or three of the metal combinations (50 μM Cd-Zn, Cd-Cu, Zn-Cu and Cd-Zn-Cu), with greater absorption in shoots. Additionally, there was no obvious competition between metals. Overall, the results demonstrate the explicit role of StGCS-GS in enhancing Cd, Zn and Cu tolerance and accumulation in transgenic sugar beet, which may represent a highly promising new tool for phytoremediation.

  17. Functional Identification and Characterization of Genes Cloned from Halophyte Seashore Paspalum Conferring Salinity and Cadmium Tolerance

    Directory of Open Access Journals (Sweden)

    Yu eChen


    Full Text Available Salinity-affected and heavy metal-contaminated soils limit the growth of glycophytic plants. Identifying genes responsible for superior tolerance to salinity and heavy metals in halophytes has great potential for use in developing salinity- and Cd-tolerant glycophytes. The objective of this study was to identify salinity- and Cd-tolerance related genes in seashore paspalum (Paspalum vaginatum, a halophytic perennial grass species, using the yeast cDNA expression library screening method. Based on the Gateway-compatible vector system, a high quality entry library was constructed, which contained 9.9×106 clones with an average inserted fragments length of 1.48 kb representing a 100% full-length rate. The yeast expression libraries were screened in a salinity-sensitive and a Cd-sensitive yeast mutant. The screening yielded 32 salinity-tolerant clones harboring 18 salinity-tolerance genes and 20 Cd-tolerant clones, including 5 Cd-tolerance genes. qPCR analysis confirmed that most of the 18 salinity-tolerance and 5 Cd-tolerance genes were up-regulated at the transcript level in response to salinity or Cd stress in seashore paspalum. Functional analysis indicated that salinity-tolerance genes from seashore paspalum could be mainly involved in photosynthetic metabolism, antioxidant systems, protein modification, iron transport, vesicle traffic, and phospholipid biosynthesis. Cd-tolerance genes from seashore paspalum could be associated with regulating pathways involved in phytochelatin synthesis, HSFA4-relsted stress protection, CYP450 complex and sugar metabolism. The 18 salinity-tolerance genes and 5 Cd-tolerance genes could be potentially used as candidate genes for genetic modification of glycophytic grass species to improve salinity and Cd tolerance and for further analysis of molecular mechanisms regulating salinity and Cd tolerance.

  18. Functional Identification and Characterization of Genes Cloned from Halophyte Seashore Paspalum Conferring Salinity and Cadmium Tolerance (United States)

    Chen, Yu; Chen, Chuanming; Tan, Zhiqun; Liu, Jun; Zhuang, Lili; Yang, Zhimin; Huang, Bingru


    Salinity-affected and heavy metal-contaminated soils limit the growth of glycophytic plants. Identifying genes responsible for superior tolerance to salinity and heavy metals in halophytes has great potential for use in developing salinity- and Cd-tolerant glycophytes. The objective of this study was to identify salinity- and Cd-tolerance related genes in seashore paspalum (Paspalum vaginatum), a halophytic perennial grass species, using yeast cDNA expression library screening method. Based on the Gateway-compatible vector system, a high-quality entry library was constructed, which contained 9.9 × 106 clones with an average inserted fragment length of 1.48 kb representing a 100% full-length rate. The yeast expression libraries were screened in a salinity-sensitive and a Cd-sensitive yeast mutant. The screening yielded 32 salinity-tolerant clones harboring 18 salinity-tolerance genes and 20 Cd-tolerant clones, including five Cd-tolerance genes. qPCR analysis confirmed that most of the 18 salinity-tolerance and five Cd-tolerance genes were up-regulated at the transcript level in response to salinity or Cd stress in seashore paspalum. Functional analysis indicated that salinity-tolerance genes from seashore paspalum could be involved mainly in photosynthetic metabolism, antioxidant systems, protein modification, iron transport, vesicle traffic, and phospholipid biosynthesis. Cd-tolerance genes could be associated with regulating pathways that are involved in phytochelatin synthesis, HSFA4-related stress protection, CYP450 complex, and sugar metabolism. The 18 salinity-tolerance genes and five Cd-tolerance genes could be potentially used as candidate genes for genetic modification of glycophytic grass species to improve salinity and Cd tolerance and for further analysis of molecular mechanisms regulating salinity and Cd tolerance. PMID:26904068

  19. Metal contaminated biochar and wood ash negatively affect plant growth and soil quality after land application. (United States)

    Jones, D L; Quilliam, R S


    Pyrolysis or combustion of waste wood can provide a renewable source of energy and produce byproducts which can be recycled back to land. To be sustainable requires that these byproducts pose minimal threat to the environment or human health. Frequently, reclaimed waste wood is contaminated by preservative-treated timber containing high levels of heavy metals. We investigated the effect of feedstock contamination from copper-preservative treated wood on the behaviour of pyrolysis-derived biochar and combustion-derived ash in plant-soil systems. Biochar and wood ash were applied to soil at typical agronomic rates. The presence of preservative treated timber in the feedstock increased available soil Cu; however, critical Cu guidance limits were only exceeded at high rates of feedstock contamination. Negative effects on plant growth and soil quality were only seen at high levels of biochar contamination (>50% derived from preservative-treated wood). Negative effects of wood ash contamination were apparent at lower levels of contamination (>10% derived from preservative treated wood). Complete removal of preservative treated timber from wood recycling facilities is notoriously difficult and low levels of contamination are commonplace. We conclude that low levels of contamination from Cu-treated wood should pose minimal environmental risk to biochar and ash destined for land application.

  20. Do weirs affect the physical and geochemical mobility of toxic metals in mining-impacted floodplain sediments? (United States)

    Bulcock, Amelia; Coleman, Alexandra; Whitfield, Elizabeth; Andres Lopez-Tarazon, Jose; Byrne, Patrick; Whitfield, Greg


    Weirs are common river structures designed to modify river channel hydraulics and hydrology for purposes of navigation, flood defence, irrigation and hydrometry. By design, weirs constrain natural flow processes and affect sediment flux and river channel forms leading to homogenous river habitats and reduced biodiversity. The recent movement towards catchment-wide river restoration, driven by the EU Water Framework Directive, has recognised weirs as a barrier to good ecological status. However, the removal of weirs to achieve more 'natural' river channels and flow processes is inevitably followed by a period of adjustment to the new flow regime and sediment flux. This period of adjustment can have knock-on effects that may increase flood risk, sedimentation and erosion until the river reaches a state of geomorphological equilibrium. Many catchments in the UK contain a legacy of toxic metals in floodplain sediments due to historic metal mining activities. The consequences of weir removal in these catchments may be to introduce 'stored' mine wastes into the river system with severe implications for water quality and biodiversity. The purpose of this study is to investigate the potential impact of a weir on the physical and geochemical mobilisation of mine wastes in the formerly mined River Twymyn catchment, Wales. Our initial investigations have shown floodplain and riverbed sediments to be grossly contaminated (up to 15,500 mg/kg Pb) compared to soil from a pre-mining Holocene terrace (180 mg/kg Pb). Geomorphological investigations also suggest that weir removal will re-establish more dynamic river channel processes resulting in lateral migration of the channel and erosion of contaminated floodplain sediments. These data will be used as a baseline for more detailed investigations of the potential impact of weirs on the physical and geochemical mobilisation of contaminated sediments. We have two specific objectives. (1) Geomorphological assessments will use unmanned

  1. Heavy metal deposition fluxes affecting an Atlantic coastal area in the southwest of Spain (United States)

    Castillo, Sonia; de la Rosa, Jesús D.; Sánchez de la Campa, Ana M.; González-Castanedo, Yolanda; Fernández-Camacho, Rocío


    The present study seeks to estimate the impact of industrial emissions and harbour activities on total atmospheric deposition in an Atlantic coastal area in the southwest of the Iberian Peninsula. Three large industrial estates and a busy harbour have a notable influence on air quality in the city of Huelva and the surrounding area. The study is based on a geochemical characterization of trace elements deposited (soluble and insoluble fractions) in samples collected at a rate of 15 days/sample from June 2008 to May 2011 in three sampling sites, one in the principal industrial belt, another in the city of Huelva, and the last, 56 km outside Huelva city in an area of high ecological interest. The industrial emissions emitted by the Huelva industrial belt exert a notable influence on atmospheric deposition. Major deposition fluxes were registered for Fe, Cu, V, Ni, P, Pb, As, Sn, Sb, Se and Bi, principally in the insoluble fraction, derived from industrial funnel emissions and from harbour activities. Metals such as Mn, Ni, Cu and Zn, and elements such as P also have a significant presence in the soluble fraction converting them into potentially bio-available nutrients for the living organism in the ocean. A principal component analysis certifies three common emissions sources in the area: 1) a mineral factor composed mainly of elements derived from silicate minerals mixed with certain anthropogenic species (Mg, K, Sr, Na, Al, Ba, LREE, Li, Mn, HREE, Ti, Fe, Se, V, SO-, Ni, Ca and P); 2) an industrial factor composed of the same trace elements in the three areas (Sb, Mo, Bi, As, Pb, Sn and Cd) thus confirming the impact of the emissions from the Huelva industrial belt on remote areas; and 3) a marine factor composed of Na, Cl, Mg and SO.

  2. Purification and characterization of an extracellular, thermo-alkali-stable, metal tolerant laccase from Bacillus tequilensis SN4. (United States)

    Sondhi, Sonica; Sharma, Prince; Saini, Shilpa; Puri, Neena; Gupta, Naveen


    A novel extracellular thermo-alkali-stable laccase from Bacillus tequilensis SN4 (SN4LAC) was purified to homogeneity. The laccase was a monomeric protein of molecular weight 32 KDa. UV-visible spectrum and peptide mass fingerprinting results showed that SN4LAC is a multicopper oxidase. Laccase was active in broad range of phenolic and non-phenolic substrates. Catalytic efficiency (kcat/Km) showed that 2, 6-dimethoxyphenol was most efficiently oxidized by the enzyme. The enzyme was inhibited by conventional inhibitors of laccase like sodium azide, cysteine, dithiothreitol and β-mercaptoethanol. SN4LAC was found to be highly thermostable, having temperature optimum at 85°C and could retain more than 80% activity at 70°C for 24 h. The optimum pH of activity for 2, 6-dimethoxyphenol, 2, 2'-azino bis[3-ethylbenzthiazoline-6-sulfonate], syringaldazine and guaiacol was 8.0, 5.5, 6.5 and 8.0 respectively. Enzyme was alkali-stable as it retained more than 75% activity at pH 9.0 for 24 h. Activity of the enzyme was significantly enhanced by Cu2+, Co2+, SDS and CTAB, while it was stable in the presence of halides, most of the other metal ions and surfactants. The extracellular nature and stability of SN4LAC in extreme conditions such as high temperature, pH, heavy metals, halides and detergents makes it a highly suitable candidate for biotechnological and industrial applications.

  3. Heavy Metal Concentration in Drinking Water Sources Affected by Dredge Mine Operations of a Gold Mining Company in Ghana

    Directory of Open Access Journals (Sweden)

    Apori Ntiforo


    Full Text Available The study assesses concentration of certain heavy metals in water sources affected by the operations of defunct dredged gold mine operations more than a decade to evaluate its quality as a source of drinking water. The concentration of heavy metals were determined from nine (9 surface water sampling points and three (3 boreholes in the Awusu-River basin in comparison with their maximum contaminant levels to assess their suitability as drinking water sources. Results obtained from the analysis of water samples indicated that the concentrations of four heavy metals (Fe, 0.01-14.93 mg/L; Cd, <0.002-0.01 mg/L; As, <0.002-0.003 mg/L and Pb, <0.005-0.05 mg/L analyzed in surface water samples were above WHO threshold values (Fe 300, Cd 3, As 10 and Pb 10 ug/L for drinking water and two (Cu, <0.002-0.05 mg/L and Zc, <0.005-0.03 mg/L were below (Cu 2000 ug/L and Zc 3000 ug/L. Dissolved iron registered the highest concentrations with the Slime Retention Area (SRA dominating with a mean concentration of 4.979 mg/L. All the sampling points were being used as drinking water sources by the two communities. An integrated approach to management of sources of drinking water quality in the mining areas is needed and should involve not only the mining companies and regulatory agencies but also the local communities to enable the latter understand and appreciate post mining issues of water quality.

  4. Normalizing effect on fatigue crack propagation at the heat-affected zone of AISI 4140 steel shielded metal arc weldings

    Directory of Open Access Journals (Sweden)

    B. Vargas-Arista


    Full Text Available The fractography and mechanical behaviour of fatigue crack propagation in the heat-affected zone (HAZ of AISI 4140 steel welded using the shielded metal arc process was analysed. Different austenitic grain size was obtained by normalizing performed at 1200 °C for 5 and 10 hours after welding. Three point bending fatigue tests on pre-cracked specimens along the HAZ revealed that coarse grains promoted an increase in fatigue crack growth rate, hence causing a reduction in both fracture toughness and critical crack length, and a transgranular brittle final fracture with an area fraction of dimple zones connecting cleavage facets. A fractographic analysis proved that as the normalizing time increased the crack length decreased. The increase in the river patterns on the fatigue crack propagation in zone II was also evidenced and final brittle fracture because of transgranular quasicleavage was observed. Larger grains induced a deterioration of the fatigue resistance of the HAZ.

  5. Purification and characterization of an extracellular, thermo-alkali-stable, metal tolerant laccase from Bacillus tequilensis SN4.

    Directory of Open Access Journals (Sweden)

    Sonica Sondhi

    Full Text Available A novel extracellular thermo-alkali-stable laccase from Bacillus tequilensis SN4 (SN4LAC was purified to homogeneity. The laccase was a monomeric protein of molecular weight 32 KDa. UV-visible spectrum and peptide mass fingerprinting results showed that SN4LAC is a multicopper oxidase. Laccase was active in broad range of phenolic and non-phenolic substrates. Catalytic efficiency (kcat/Km showed that 2, 6-dimethoxyphenol was most efficiently oxidized by the enzyme. The enzyme was inhibited by conventional inhibitors of laccase like sodium azide, cysteine, dithiothreitol and β-mercaptoethanol. SN4LAC was found to be highly thermostable, having temperature optimum at 85°C and could retain more than 80% activity at 70°C for 24 h. The optimum pH of activity for 2, 6-dimethoxyphenol, 2, 2'-azino bis[3-ethylbenzthiazoline-6-sulfonate], syringaldazine and guaiacol was 8.0, 5.5, 6.5 and 8.0 respectively. Enzyme was alkali-stable as it retained more than 75% activity at pH 9.0 for 24 h. Activity of the enzyme was significantly enhanced by Cu2+, Co2+, SDS and CTAB, while it was stable in the presence of halides, most of the other metal ions and surfactants. The extracellular nature and stability of SN4LAC in extreme conditions such as high temperature, pH, heavy metals, halides and detergents makes it a highly suitable candidate for biotechnological and industrial applications.

  6. Effect of heavy-metal-resistant bacteria on enhanced metal uptake and translocation of the Cu-tolerant plant, Elsholtzia splendens. (United States)

    Xu, Chen; Chen, Xincai; Duan, Dechao; Peng, Cheng; Le, Thu; Shi, Jiyan


    A hydroponics trial was employed to study the effects of Pseudomonas putida CZ1 (CZ1), a heavy-metal-resistant bacterial strain isolated from the rhizosphere of Elsholtzia splendens (E. splendens), on the uptake and translocation of copper (Cu) in E. splendens. Significant promotion of plant growth coupled with the obvious plant-growth-promoting (PGP) characters of the bacteria suggested that CZ1 would be a plant-growth-promoting rhizobacterium (PGPR) to E. splendens under Cu stress condition. The results of inductively coupled plasma optical emission spectrometry (ICP-OES) showed that CZ1 increased the concentration of Cu in the shoots (up to 211.6% compared to non-inoculation treatment) and translocation factor (TF) (from 0.56 to 1.83%) of those exposed to Cu. The distribution of Cu in root cross section measured by synchrotron-based X-ray fluorescence microscopy (SRXRF) indicated that CZ1 promoted the transport of Cu from cortex to xylem in roots, which contributed to the accumulation of Cu in shoots. Furthermore, CZ1 improved the uptake of nutrient elements by plants to oppose to the toxicity of Cu. In summary, P. putida CZ1 acted as a PGPR in resistance to Cu and promoted the accumulation and translocation of Cu from root to shoot by element redistribution in plant root; hence, CZ1 is a promising assistance to phytoremediation.

  7. Biodecolorization of Reactive Black-5 by a metal and salt tolerant bacterial strain Pseudomonas sp. RA20 isolated from Paharang drain effluents in Pakistan. (United States)

    Hussain, Sabir; Maqbool, Zahid; Ali, Shafaqat; Yasmeen, Tahira; Imran, Muhammad; Mahmood, Faisal; Abbas, Farhat


    Discharge of untreated azo dyes contaminated textile wastewater into soil and water bodies causes severe contamination. The present study was conducted to isolate dye degrading bacterial strains from a textile industry wastewater carrying drain in the neighborhood of Faisalabad, Pakistan. Seventy six bacterial strains were initially isolated and was screened using liquid mineral salts medium spiked with Reactive Black-5 azo dye. The strain RA20 was found to be the most efficient azo dye degrading bacterial isolate and was identified by amplifying and sequencing its 16S rRNA. Analysis indicated that this strain belonged to genus Pseudomonas and was designated as Pseudomonas sp. RA20. It had the highest decolorization activity at pH 8 and 25 °C incubation temperature under static conditions using yeast extract as an additional C source. This strain was also effective in decolorizing structurally related other reactive dyes including Reactive Orange 16, Reactive Yellow 2 and Reactive Red 120 but with varying efficacy. RA20 decolorized Reactive Black-5 significantly in the presence of up to 30 g L⁻¹ NaCl; however, the decolorization rate was significantly (p≤0.05) reduced beyond this salt concentration. Moreover, this bacterial strain also exhibited moderate tolerance to different heavy metals including zinc (Zn), cadmium (Cd), chromium (Cr), lead (Pb) and copper (Cu). RA20 also decolorized Reactive Black-5 in the presence of a mixture of the selected heavy metals depending upon their concentrations. This study highlights the importance of Pseudomonas sp. RA20 as a prospective biological resource for bioremediation of water and soils contaminated with azo dyes.

  8. Direct evidence that genetic variation in glycerol-3-phosphate and malate dehydrogenase genes (Gpdh and Mdh1) affects adult ethanol tolerance in Drosophila melanogaster. (United States)

    Eanes, Walter F; Merritt, Thomas J S; Flowers, Jonathan M; Kumagai, Seiji; Zhu, Chen-Tseh


    Many studies of alcohol adaptation in Drosophila melanogaster have focused on the Adh polymorphism, yet the metabolic elimination of alcohol should involve many enzymes and pathways. Here we evaluate the effects of glycerol-3-phosphate dehydrogenase (Gpdh) and cytosolic malate dehydrogenase (Mdh1) genotype activity on adult tolerance to ethanol. We have created a set of P-element-excision-derived Gpdh, Mdh1, and Adh alleles that generate a range of activity phenotypes from full to zero activity. Comparisons of paired Gpdh genotypes possessing 10 and 60% normal activity and 66 and 100% normal activity show significant effects where higher activity increases tolerance. Mdh1 null allele homozygotes show reductions in tolerance. We use piggyBac FLP-FRT site-specific recombination to create deletions and duplications of Gpdh. Duplications show an increase of 50% in activity and an increase of adult tolerance to ethanol exposure. These studies show that the molecular polymorphism associated with GPDH activity could be maintained in natural populations by selection related to adaptation to alcohols. Finally, we examine the interactions between activity genotypes for Gpdh, Mdh1, and Adh. We find no significant interlocus interactions. Observations on Mdh1 in both Gpdh and Adh backgrounds demonstrate significant increases in ethanol tolerance with partial reductions (50%) in cytosolic MDH activity. This observation strongly suggests the operation of pyruvate-malate and, in particular, pyruvate-citrate cycling in adaptation to alcohol exposure. We propose that an understanding of the evolution of tolerance to alcohols will require a system-level approach, rather than a focus on single enzymes.

  9. Metals at the surface of last scatter

    CERN Document Server

    Ali-Haïmoud, Yacine; Kamionkowski, Marc


    Standard big-bang nucleosynthesis (BBN) predicts only a trace abundance of lithium and no heavier elements, but some alternatives predict a nonzero primordial metallicity. Here we explore whether CMB measurements may set useful constraints to the primordial metallicity and/or whether the standard CMB calculations are robust, within the tolerance of forthcoming CMB maps, to the possibility of primordial metals. Metals would affect the recombination history (and thus CMB power spectra) in three ways: (1) Lyman-alpha photons can be removed (and recombination thus accelerated) by photoionizing metals. (2) The Bowen resonance-fluorescence mechanism may degrade Lyman-beta photons and thus enhance the Lyman-beta escape probability and speed up recombination. (3) Metals could affect the low-redshift tail of the CMB visibility function by providing additional free electrons. The last two of these provide the strongest CMB signal. However, the effects are detectable in the Planck satellite only if the primordial metal ...

  10. A Tn5051-like mer-containing transposon identified in a heavy metal tolerant strain Achromobacter sp. AO22

    Directory of Open Access Journals (Sweden)

    Bhave Mrinal


    Full Text Available Abstract Background Achromobacter sp. AO22 (formerly Alcaligenes sp. AO22, a bacterial strain isolated from a lead-contaminated industrial site in Australia, was previously found to be resistant to moderate to high levels of mercury, copper and other heavy metals. However, the nature and location of the genetic basis for mercuric ion resistance in this strain, had not been previously identified. Findings Achromobacter sp. AO22 contains a functional mer operon with all four essential genes (merRTPA and shows >99% DNA sequence identity to that of Tn501. The mer operon was present on a transposon, designated TnAO22, captured by introducing a broad-host-range IncP plasmid into Achromobacter sp. AO22 and subsequently transferring it to E. coli recipients. The transposition frequency of TnAO22 was 10-2 to 10-3 per target plasmid transferred. Analysis of TnAO22 sequence revealed it belonged to the Tn21 subgroup of the Tn3 superfamily of transposons, with the transposition module having >99% identity with Tn5051 of a Pseudomonas putida strain isolated from a water sample in New York. Conclusion TnAO22 is thus a new variant of Tn5051 of the Tn3 superfamily and the transposon and its associated mercury resistance system are among the few such systems reported in a soil bacterium. Achromobacter sp. AO22 can thus be exploited for applications such as in situ mercury bioremediation of contaminated sites, or the mobile unit and mer operon could be mobilized to other bacteria for similar purposes.

  11. Relative contribution of food and water to 27 metals and metalloids accumulated by caged Hyalella azteca in two rivers affected by metal mining

    Energy Technology Data Exchange (ETDEWEB)

    Borgmann, U. [Water Science and Technology Directorate, Environment Canada, 867 Lakeshore Road, Burlington, ON, L7R 4A6 (Canada)]. E-mail:; Couillard, Y. [Existing Substances Division, Environment Canada, 351 Saint-Joseph Boulevard, Gatineau, QC, K1A 0H3 (Canada); Grapentine, L.C. [Water Science and Technology Directorate, Environment Canada, 867 Lakeshore Road, Burlington, ON, L7R 4A6 (Canada)


    Hyalella were caged at three sites in each of the two rivers for 17 days. Food added to the cages consisted of plant and detrital material collected from the same, or other, sites. Concentrations of some metals in Hyalella (e.g., Cd and Cu), but not others (e.g., Se), appeared to reach steady-state within 5 days in one of the rivers. Metal accumulation was minimal by day 5 in the other river, possibly due to the very low temperatures in this river for the first part of the exposure period. Both analysis of variance and analysis of covariance, using site as a categorical variable and metal in food as either a categorical or continuous variable, indicated that Cd, Cu and Se were the only metals for which concentration in food had a significant effect on concentration in Hyalella. Nevertheless, water was still a major source for these metals as well. Other metals which varied by over fivefold in food but for which concentration in food had no effect on concentration in Hyalella included Ag, As, Bi, Sb, U and Zn. Concentrations of the remaining metals varied less than fourfold in food, making it difficult to determine if these were accumulated from food. - Cadmium, copper and selenium were the only metals in food that correlated with increased body concentrations of metals in Hyalella, but even these metals were accumulated largely from water.

  12. Microstructures and Mechanical Properties of Weld Metal and Heat-Affected Zone of Electron Beam-Welded Joints of HG785D Steel (United States)

    Zhang, Qiang; Han, Jianmin; Tan, Caiwang; Yang, Zhiyong; Wang, Junqiang


    Vacuum electron beam welding (EBW) process was employed to butt weld 10-mm-thick HG785D high-strength steels. The penetration into the steel was adjusted by beam current. Microstructures at weld metal and heat-affected zone (HAZ) regions were comparatively observed. Mechanical properties of the EBWed joints including Vickers hardness, tensile and Charpy impact tests were evaluated. The results indicated that microstructures at the weld metal consisted of coarse lath martensite and a small amount of acicular martensite, while that in the HAZ was tempered sorbite and martensite. The grain size in the weld metal was found to be larger than that in the HAZ, and its proportion in weld metal was higher. The hardness in the weld metal was higher than the HAZ and base metal. The tensile strength and impact toughness in the HAZ was higher than that in the weld metal. All the behaviors were related to microstructure evolution caused by higher cooling rates and state of base metal. The fracture surfaces of tensile and impact tests on the optimized joint were characterized by uniform and ductile dimples. The results differed significantly from that obtained using arc welding process.

  13. Combined Chemical and Mineralogical Evidence for Heavy Metal Binding in Mining- and Smelting-Affected Alluvial Soils

    Institute of Scientific and Technical Information of China (English)



    The binding of metallic contaminants (Pb, Cd, and Zn) and As on soil constituents was studied on four highly con-taminated alluvial soil profiles from the mining/smelting district of Pribram (Czech Republic) using a combination of mineralogical and chemical methods. Sequential extraction analysis (SEA) was supplemented by mineralogical investi-gation of both bulk samples and hcavy mineral fractions using X-ray diffraction analysis (XRD) and scanning electron microscopy with an energy dispersive X-ray spectrometer (SEM/EDS). The mineralogy of Fe and Mn oxides was studied by voltammetry of microparticles (VMP) and diffuse reflectance spectrometry (DRS). Zinc and Pb were predominantly were detected in soils by XRD and SEM/EDS. In contrast, Cd was the most mobile contaminant and was predominantly present in the exchangeable fraction. Arsenic was bound to the residual and reducible fractions (corresponding to Fe oxides or to unidentified Fe-Pb arsenates). SEM/EDS observations indicate the predominant affinity of Pb for Mn oxides,and to a lesser extent, for Fe oxidcs. Thus, a more suitable SEA procedure should be used for these mining-affected soils to distinguish between the contaminant fraction bound to Mn oxides and Fe oxides.

  14. 语言模糊容忍度对英语口语教学的效用%Affect of Tolerance of Ambiguity on Speaking Performance

    Institute of Scientific and Technical Information of China (English)

    张小林; 陈琳; 任伟亚


    Based on the definition of speaking performance by Jerry Hannmer, this paper analyzes the forming process of David. W. Carroll' s spoken language and the combination of the characteristics of spoken language in every step and the tolerance of ambiguity, this paper analyzes the influence of the tolerance of ambiguity on the forming of English speaking performance and puts forward the methods to improve the tolerance of ambiguity.%本文基于JerryHarmmer的口语能力定义,对David.W.Carroll的口语形成过程进行剖析,将口语形成的每阶段的特点与语言模糊容忍度联系起来,详细分析了提高语言模糊容忍度对英语口语能力的形成的影响,并提出了相应方法来提高学生的语言模糊容忍度。

  15. Expression of Caenorhabditis elegans PCS in the AtPCS1-deficient Arabidopsis thaliana cad1-3 mutant separates the metal tolerance and non-host resistance functions of phytochelatin synthases. (United States)

    Kühnlenz, Tanja; Westphal, Lore; Schmidt, Holger; Scheel, Dierk; Clemens, Stephan


    Phytochelatin synthases (PCS) play key roles in plant metal tolerance. They synthesize small metal-binding peptides, phytochelatins, under conditions of metal excess. Respective mutants are strongly cadmium and arsenic hypersensitive. However, their ubiquitous presence and constitutive expression had long suggested a more general function of PCS besides metal detoxification. Indeed, phytochelatin synthase1 from Arabidopsis thaliana (AtPCS1) was later implicated in non-host resistance. The two different physiological functions may be attributable to the two distinct catalytic activities demonstrated for AtPCS1, that is the dipeptidyl transfer onto an acceptor molecule in phytochelatin synthesis, and the proteolytic deglycylation of glutathione conjugates. In order to test this hypothesis and to possibly separate the two biological roles, we expressed a phylogenetically distant PCS from Caenorhabditis elegans in an AtPCS1 mutant. We confirmed the involvement of AtPCS1 in non-host resistance by showing that plants lacking the functional gene develop a strong cell death phenotype when inoculated with the potato pathogen Phytophthora infestans. Furthermore, we found that the C. elegans gene rescues phytochelatin synthesis and cadmium tolerance, but not the defect in non-host resistance. This strongly suggests that the second enzymatic function of AtPCS1, which remains to be defined in detail, is underlying the plant immunity function.

  16. A novel allele of L-galactono-1,4-lactone dehydrogenase is associated with enhanced drought tolerance through affecting stomatal aperture in common wheat. (United States)

    Zhang, Juncheng; Li, Bin; Yang, Yanping; Mu, Peiyuan; Qian, Weiqiang; Dong, Lingli; Zhang, Kunpu; Liu, Xin; Qin, Huanju; Ling, Hongqing; Wang, Daowen


    In higher plants, L-galactono-1,4-lactone dehydrogenase (GLDH) plays important roles in ascorbic acid (AsA) biosynthesis and assembly of respiration complex I. Here we report three homoeologous genes (TaGLDH-A1, -B1 and -D1) encoding common wheat GLDH isozymes and a unique allelic variant (TaGLDH-A1b) associated with enhanced drought tolerance. TaGLDH-A1, -B1 and -D1 were located on chromosomes 5A, 5B and 5D, respectively, and their transcripts were found in multiple organs. The three homoeologs each conferred increased GLDH activity when ectopically expressed in tobacco. Decreasing TaGLDH expression in wheat significantly reduced GLDH activity and AsA content. TaGLDH-A1b differed from wild type allele TaGLDH-A1a by an in-frame deletion of three nucleotides. TaGLDH-A1b was biochemically less active than TaGLDH-A1a, and the total GLDH activity levels were generally lower in the cultivars carrying TaGLDH-A1b relative to those with TaGLDH-A1a. Interestingly, TaGLDH-A1b cultivars showed stronger water deficiency tolerance than TaGLDH-A1a cultivars, and TaGLDH-A1b co-segregated with decreased leaf water loss in a F2 population. Finally, TaGLDH-A1b cultivars generally exhibited smaller leaf stomatal aperture than TaGLDH-A1a varieties in control or water deficiency environments. Our work provides new information on GLDH genes and function in higher plants. TaGLDH-A1b is likely useful for further studying and improving wheat tolerance to drought stress.

  17. Bottle gourd rootstock-grafting affects nitrogen metabolism in NaCl-stressed watermelon leaves and enhances short-term salt tolerance. (United States)

    Yang, Yanjuan; Lu, Xiaomin; Yan, Bei; Li, Bin; Sun, Jin; Guo, Shirong; Tezuka, Takafumi


    The plant growth, nitrogen absorption, and assimilation in watermelon (Citrullus lanatus [Thunb.] Mansf.) were investigated in self-grafted and grafted seedlings using the salt-tolerant bottle gourd rootstock Chaofeng Kangshengwang (Lagenaria siceraria Standl.) exposed to 100mM NaCl for 3d. The biomass and NO3(-) uptake rate were significantly increased by rootstock while these values were remarkably decreased by salt stress. However, compared with self-grafted plants, rootstock-grafted plants showed higher salt tolerance with higher biomass and NO3(-) uptake rate under salt stress. Salinity induced strong accumulation of nitrate, ammonium and protein contents and a significant decrease of nitrogen content and the activities of nitrate reductase (NR), nitrite reductase (NiR), glutamine synthetase (GS), and glutamate synthase (GOGAT) in leaves of self-grafted seedlings. In contrast, salt stress caused a remarkable decrease in nitrate content and the activities of GS and GOGAT, and a significant increase of ammonium, protein, and nitrogen contents and NR activity, in leaves of rootstock-grafted seedlings. Compared with that of self-grafted seedlings, the ammonium content in leaves of rootstock-grafted seedlings was much lower under salt stress. Glutamate dehydrogenase (GDH) activity was notably enhanced in leaves of rootstock-grafted seedlings, whereas it was significantly inhibited in leaves of self-grafted seedlings, under salinity stress. Three GDH isozymes were isolated by native gel electrophoresis and their expressions were greatly enhanced in leaves of rootstock-grafted seedlings than those of self-grafted seedlings under both normal and salt-stress conditions. These results indicated that the salt tolerance of rootstock-grafted seedlings might (be enhanced) owing to the higher nitrogen absorption and the higher activities of enzymes for nitrogen assimilation induced by the rootstock. Furthermore, the detoxification of ammonium by GDH when the GS/GOGAT pathway

  18. Urban legacies and soil management affect the concentration and speciation of trace metals in Los Angeles community garden soils. (United States)

    Clarke, Lorraine Weller; Jenerette, G Darrel; Bain, Daniel J


    Heavy metals in urban soils can compromise human health, especially in urban gardens, where gardeners may ingest contaminated dust or crops. To identify patterns of urban garden metal contamination, we measured concentrations and bioavailability of Pb, As, and Cd in soils associated with twelve community gardens in Los Angeles County, CA. This included sequential extractions to partition metals among exchangeable, reducible, organic, or residual fractions. Proximity to road increased all metal concentrations, suggesting vehicle emissions sources. Reducible Pb increased with neighborhood age, suggesting leaded paint as a likely pollutant source. Exchangeable Cd and As both increased with road proximity. Only cultivated soils showed an increase in exchangeable As with road proximity, potentially due to reducing humic acid interactions while Cd bioavailability was mitigated by organic matter. Understanding the geochemical phases and metal bioavailability allows incorporation of contamination patterns into urban planning.

  19. Tolerância da soja ao desfolhamento afetada pela redução do espaçamento entre fileiras Soybean tolerance to defoliation as affected by row spacing reduction

    Directory of Open Access Journals (Sweden)

    Geovano Parcianello


    Full Text Available A redução do espaçamento entre fileiras de 40 para 20cm incrementa a interceptação da radiação, o índice de área foliar e o rendimento de grãos. Este trabalho objetivou avaliar se a redução do espaçamento entre fileiras influencia a tolerância da soja à perda de área fotossintética. O experimento foi conduzido, em semeadura direta na Estação Experimental Agronômica da UFRGS, na safra 2000/01. Utilizou-se o delineamento experimental de blocos ao acaso, com quatro repetições, em parcelas sub-subdivididas. Os tratamentos foram desfolhamento em três estádios de desenvolvimento (V9 - nono nó, R2 - floração e R5 - inicio enchimento de grãos, dois espaçamentos entre fileiras (20 e 40cm e quatro níveis de desfolhamento (0 - testemunha, 33, 67 e 100%. Foi utilizada a cultivar FT-Abyara. Os desfolhamentos realizados no período reprodutivo reduziram o rendimento, sendo o estádio R5 o mais crítico. O rendimento médio de grãos da testemunha não desfolhada foi 21% maior no espaçamento de 20cm (4134kg ha-1 do que no de 40cm (3413kg ha-1 e manteve-se sempre superior, em todos os níveis de desfolhamento. O componente que mais influenciou o rendimento foi o número de legumes m-2. Estes resultados indicam que a redução do espaçamento entre fileiras de 40cm para 20cm é uma prática cultural favorável tanto para as plantas com área foliar intacta quando desfolhadas.The row spacing reduction from 40 to 20 cm increase radiation interception, leaf area index and grain yield. This experiment aimed to evaluate if the row spacing reduction influence soybean tolerance to loss of photosynthetic area. The research was performed using no-till tillage system at the Agronomic Experimental Station of Universidade Federal do Rio Grande do Sul, during the 2000/01 growing season. Treatments were arranged in a split-split plot randomized complete block design, with four replications. Treatments included five combination of defoliation in

  20. Heavy metal contamination of agricultural soils affected by mining activities around the Ganxi River in Chenzhou, Southern China. (United States)

    Ma, Li; Sun, Jing; Yang, Zhaoguang; Wang, Lin


    Heavy metal contamination attracted a wide spread attention due to their strong toxicity and persistence. The Ganxi River, located in Chenzhou City, Southern China, has been severely polluted by lead/zinc ore mining activities. This work investigated the heavy metal pollution in agricultural soils around the Ganxi River. The total concentrations of heavy metals were determined by inductively coupled plasma-mass spectrometry. The potential risk associated with the heavy metals in soil was assessed by Nemerow comprehensive index and potential ecological risk index. In both methods, the study area was rated as very high risk. Multivariate statistical methods including Pearson's correlation analysis, hierarchical cluster analysis, and principal component analysis were employed to evaluate the relationships between heavy metals, as well as the correlation between heavy metals and pH, to identify the metal sources. Three distinct clusters have been observed by hierarchical cluster analysis. In principal component analysis, a total of two components were extracted to explain over 90% of the total variance, both of which were associated with anthropogenic sources.

  1. Concentrations of heavy metals and aquatic macrophytes of Govind Ballabh Pant Sagar an anthropogenic lake affected by coal mining effluent. (United States)

    Mishra, Virendra Kumar; Upadhyay, Alka Rani; Pandey, Sudhir Kumar; Tripathi, B D


    Five heavy metals Cu, Cd, Mn, Pb and Hg were found in high concentration from three sampling sites located in Asia's largest anthropogenic lake Govind Ballabh Pant GBP Sagar. Concentrations of these heavy metals were measured in Water, bottom sediment and in different parts of the aquatic macrophytes collected from the reservoir. Plants collected from the lake were Eichhornia crassipes, Azolla pinnata, Lemna minor, Spirodela polyrrhiza, Potamogeton pectinatus, Marsilea quadrifolia, Pistia stratiotes, Ipomea aquqtica, Potamogeton crispus, Hydrilla verticillata and Aponogeton natans. These plants have shown the high concentrations of Cu, Cd, Mn, Pb and Hg in their different parts due to bioaccumulation. In general plant roots exhibited higher concentrations of heavy metals than corresponding sediments. A comparison between different morphological tissues of the sampled plants revealed the metal concentration in following order roots > leaves. Analyses of bottom sediment indicated the higher concentrations of Cd, Mn, Cu and Pb. Strong positive correlations were obtained between the metals in water and in plants as well as between metal in sediment and in plants. Indicating the potential of these plants for pollution monitoring of these metals.

  2. Protein and carbohydrate composition of larval food affects tolerance tothermal stress and desiccation in adult Drosophila melanogaster

    DEFF Research Database (Denmark)

    Andersen, Laila H; Kristensen, Torsten N; Loeschcke, Volker;


    as well as egg production and egg-to-adult viability. We raised larvae on a carbohydrate-enriched and a protein-enriched growth medium. We found that flies developed on the high protein medium had increased heat and desiccation tolerance compared to flies developed on the carbohydrate-enriched medium...... stress compared to males. Egg production was highest in females that had developed on the protein-enriched medium. However, there was a sex-specific effect of nutrition on egg-to-adult viability, with higher viability for males developing on the sucrose-enriched medium, while female survival was highest...... when developing on the protein-enriched medium. Our study indicates that larval nutrition has a strong impact on the ability to cope with stress, and that the optimal nutrient composition varies with the type of stress...

  3. Comparative Investigation of Copper Tolerance and Identification of Putative Tolerance Related Genes in Tardigrades (United States)

    Hygum, Thomas L.; Fobian, Dannie; Kamilari, Maria; Jørgensen, Aslak; Schiøtt, Morten; Grosell, Martin; Møbjerg, Nadja


    Tardigrades are microscopic aquatic animals renowned for their tolerance toward extreme environmental conditions. The current study is the first to investigate their tolerance toward heavy metals and we present a novel tardigrade toxicant tolerance assay based on activity assessments as a measure of survival. Specifically, we compare tolerance toward copper in four species representing different evolutionary lineages, habitats and adaptation strategies, i.e., a marine heterotardigrade, Echiniscoides sigismundi, a limno-terrestrial heterotardigrade, Echiniscus testudo, a limno-terrestrial eutardigrade, Ramazzottius oberhaeuseri, and a marine eutardigrade, Halobiotus crispae. The latter was sampled at a time of year, when the population is predominantly represented by aberrant P1 cysts, while the other species were in normal active states prior to exposure. Based on volume measurements and a general relation between body mass and copper tolerance, expected tardigrade EC50 values were estimated at 0.5–2 μg l−1. Following 24 h of exposure, tolerance was high with no apparent link to lineage or habitat. EC50s (95% CI), 24 h after exposure, were estimated at 178 (168–186) and 310 (295–328) μg l−1, respectively, for E. sigismundi and R. oberhaeuseri, whereas E. testudo and H. crispae were less affected. Highest tolerance was observed in H. crispae with a mean ± s.e.m. activity of 77 ± 2% (n = 3) 24 h after removal from ~3 mg l−1 copper, suggesting that tardigrade cysts have increased tolerance toward toxicants. In order to identify putative tolerance related genes, an E. sigismundi transcriptome was searched for key enzymes involved in osmoregulation, antioxidant defense and copper metabolism. We found high expression of Na/K ATPase and carbonic anhydrase, known targets for copper. Our transcriptome, furthermore, revealed high expression of antioxidant enzymes, copper transporters, ATOX1, and a Cu-ATPase. In summary, our results indicate that tardigrades

  4. A facile solvent-free Synthesis Route for the Assembly of Highly CO2 Selective and H2S tolerant NiSIFSIX Metal-Organic Framework

    KAUST Repository

    Eddaoudi, Mohamed


    The development of materials for CO2 capture with high selectivity and high tolerance to H2S is of prime importance for various industrially relevant gas streams (e.g. natural gas and biogas upgrading as well as pre-combustion capture). Here, we report the successful fabrication of a MOF with combined exceptional CO2 capture properties and H2S tolerance, namely Ni SIFSIX based-MOF using both solvothermal and solvent-free methodologies.

  5. Heavy Metals Affect Nematocysts Discharge Response and Biological Activity of Crude Venom in the Jellyfish Pelagia noctiluca (Cnidaria, Scyphozoa

    Directory of Open Access Journals (Sweden)

    Rossana Morabito


    Full Text Available Background: Pollution of marine ecosystems and, specifically, heavy metals contamination may compromise the physiology of marine animals with events occurring on a cellular and molecular level. The present study focuses on the effect of short-term exposure to heavy metals like Zinc, Cadmium, Cobalt and Lanthanum (2-10 mM on the homeostasis of Pelagia noctiluca (Cnidaria, Scyphozoa, a jellyfish abundant in the Mediterranean sea. This species possesses stinging organoids, termed nematocysts, whose discharge and concomitant delivery of venom underlie the survival of all Cnidaria. Methods: Nematocysts discharge response, elicited by combined chemico-physical stimulation, was verified on excised oral arms exposed to heavy metals for 20 min. In addition, the hemolytic activity of toxins, contained in the crude venom extracted from nematocysts isolated from oral arms, was tested on human erythrocytes, in the presence of heavy metals or their mixture. Results: Treatment with heavy metals significantly inhibited both nematocysts discharge response and hemolytic activity of crude venom, in a dose-dependent manner, not involving oxidative events, that was irreversible in the case of Lanthanum. Conclusion: Our findings show that the homeostasis of Pelagia noctiluca, in terms of nematocysts discharge capability and effectiveness of venom toxins, is dramatically and rapidly compromised by heavy metals and confirm that this jellyfish is eligible as a model for ecotoxicological investigations.

  6. Rapidly alternating photoperiods disrupt central and peripheral rhythmicity and decrease plasma glucose, but do not affect glucose tolerance or insulin secretion in sheep. (United States)

    Varcoe, Tamara J; Gatford, Kathryn L; Voultsios, Athena; Salkeld, Mark D; Boden, Michael J; Rattanatray, Leewen; Kennaway, David J


    Disrupting circadian rhythms in rodents perturbs glucose metabolism and increases adiposity. To determine whether these effects occur in a large diurnal animal, we assessed the impact of circadian rhythm disruption upon metabolic function in sheep. Adult ewes (n = 7) underwent 3 weeks of a control 12 h light-12 h dark photoperiod, followed by 4 weeks of rapidly alternating photoperiods (RAPs) whereby the time of light exposure was reversed twice each week. Measures of central (melatonin secretion and core body temperature) and peripheral rhythmicity (clock and metabolic gene expression in skeletal muscle) were obtained over 24 h in both conditions. Metabolic homeostasis was assessed by glucose tolerance tests and 24 h glucose and insulin profiles. Melatonin and core body temperature rhythms resynchronized within 2 days of the last photoperiod shift. High-amplitude Bmal1, Clock, Nr1d1, Cry2 and Per3 mRNA rhythms were apparent in skeletal muscle, which were phase advanced by up to 3.5 h at 2 days after the last phase shift, whereas Per1 expression was downregulated at this time. Pparα, Pgc1α and Nampt mRNA were constitutively expressed in both conditions. Nocturnal glucose concentrations were reduced following chronic phase shifts (zeitgeber time 0, -5.5%; zeitgeber time 12, -2.9%; and zeitgeber time 16, -5.7%), whereas plasma insulin, glucose tolerance and glucose-stimulated insulin secretion were not altered. These results demonstrate that clock gene expression within ovine skeletal muscle oscillates over 24 h and responds to changing photoperiods. However, metabolic genes which link circadian and metabolic clocks in rodents were arrhythmic in sheep. Differences may be due to the ruminant versus monogastric digestive organization in each species. Together, these results demonstrate that despite disruptions to central and peripheral rhythmicity following exposure to rapidly alternating photoperiods, there was minimal impact on glucose homeostasis in

  7. Heavy metal pollution across sites affecting the intestinal helminth communities of the Egyptian lizard, Chalcides ocellatus (Forskal, 1775). (United States)

    Soliman, M F M


    This study aimed to investigate the possible effects of heavy metal pollution across sites and some biological factors on helminth communities infecting the lizard, Chalcides ocellatus. The possibility of heavy metal accumulation by such helminths was also investigated. A total of 202 C. ocellatus were collected from three different sites (industrial, rural, and urban systems) in Ismailia governorate, Egypt, during summer 2009. The lizards were classified according to their sex and size and were examined for the intestinal helminths. Heavy metal levels were detected in the intestinal tissue of the lizards and the recovered helminths. Species richness was 6, 5, and 3 in rural, urban, and industrial systems, respectively. Significant site variations regarding infection prevalence, intensity, and abundance were encountered at different levels. Some noticeable effects of the host size were found. The significant differences found between the metal levels of the intestinal tissues and the recovered helminths and the other relations found in this study may be indications for a possible metals accumulation capacity by helminths. The cestode Oochoristica tuberculata could be a promising biomonitor for Cu and Pb, while the intestinal nematodes were less sensitive to the pollution. Differences in the accumulation capacity may be attributed to the intensity of infection, parasite species, and metal. The observed patterns of distribution and occurrence of helminths and the metals accumulation capacity reflect the need for more studies since this study proposes the model intestinal helminth/C. ocellatus as another promising bioindication system in the terrestrial habitat, especially in areas where the lizard C. ocellatus are available.

  8. Calcium- and ammonium ion-modification of zeolite amendments affects the metal-uptake of Hieracium piloselloides in a dose-dependent way. (United States)

    Peter, Anca; Mihaly-Cozmuta, Leonard; Mihaly-Cozmuta, Anca; Nicula, Camelia; Indrea, Emil; Tutu, Hlanganani


    The role of natural zeolite and of two types of modified zeolite (with ammonium and with calcium ions) in reducing the accumulation of ions of heavy metals in roots and leaves of Hieracium piloselloides grown on tailing ponds was investigated. The variation of the content of zeolite (5% w/w and 10% w/w) is another parameter that significantly and positively affects the accumulation of the metal ions in Hieracium piloselloides. The results showed that zeolite used as an amendment in the soil in tailing ponds significantly reduces the accumulation of heavy metal ions in Hieracium piloselloides. The highest concentrations of heavy metals were accumulated in plants grown on soil without zeolite, being followed by the plants grown on the substrate with natural zeolite. Moreover, the translocation factors of heavy metal ions uptake in roots and leaves grown on substrates with modified zeolites are lower than those calculated for the organs grown on the substrate amended with natural zeolite. This behaviour has demonstrated the positive effect of those changes of zeolite amendments in the potential phytoremediation practice.

  9. Metronomic chemotherapy following the maximum tolerated dose is an effective anti-tumour therapy affecting angiogenesis, tumour dissemination and cancer stem cells. (United States)

    Vives, Marta; Ginestà, Mireia M; Gracova, Kristina; Graupera, Mariona; Casanovas, Oriol; Capellà, Gabriel; Serrano, Teresa; Laquente, Berta; Viñals, Francesc


    In this article, the effectiveness of a multi-targeted chemo-switch (C-S) schedule that combines metronomic chemotherapy (MET) after treatment with the maximum tolerated dose (MTD) is reported. This schedule was tested with gemcitabine in two distinct human pancreatic adenocarcinoma orthotopic models and with cyclophosphamide in an orthotopic ovarian cancer model. In both models, the C-S schedule had the most favourable effect, achieving at least 80% tumour growth inhibition without increased toxicity. Moreover, in the pancreatic cancer model, although peritoneal metastases were observed in control and MTD groups, no dissemination was observed in the MET and C-S groups. C-S treatment caused a decrease in angiogenesis, and its effect on tumour growth was similar to that produced by the MTD followed by anti-angiogenic DC101 treatment. C-S treatment combined an increase in thrombospondin-1 expression with a decrease in the number of CD133+ cancer cells and triple-positive CD133+/CD44+/CD24+ cancer stem cells (CSCs). These findings confirm that the C-S schedule is a challenging clinical strategy with demonstrable inhibitory effects on tumour dissemination, angiogenesis and CSCs.

  10. Om tolerance

    DEFF Research Database (Denmark)

    Huggler, Jørgen


    Begrebet tolerance og dets betydninger diskuteres med henblik på en tydeliggørelse af begrebets forbindelse med stat, religion, ytringsfrihed, skeptisk erkendelsesteori, antropologi og pædagogik.......Begrebet tolerance og dets betydninger diskuteres med henblik på en tydeliggørelse af begrebets forbindelse med stat, religion, ytringsfrihed, skeptisk erkendelsesteori, antropologi og pædagogik....

  11. [Accumulation Characteristics and Evaluation of Heavy Metals in Soil-Crop System Affected by Wastewater Irrigation Around a Chemical Factory in Shenmu County]. (United States)

    Qi, Yan-bing; Chu, Wan-lin; Pu, Jie; Liu, Meng-yun; Chang, Qing-rui


    Soil heavy metals Cu, Pb, Zn, and Cd, are regarded as "chemical time bombs" because of their propensity for accumulation in the soil and uptake by crops. This ultimately causes human toxicity in both the short and long-term, making farmland ecosystems dangerous to health. In this paper, accumulation and spatial variability of Cu, Zn, Pb and Cd in soil-crop system affected by wastewater irrigation around a chemical factor in northern Shaanxi province were analyzed. Results showed that wastewater irrigation around the chemical factory induced significant accumulation in soils compared with control areas. The average concentrations of available Cu and total Cu were 4.32 mg x kg(-1) and 38.4 mg x kg(-1), which were twice and 1.35 times higher than those of the control area, respectively. Soil Zn and Pb were slightly accumulated. Whereas soil Cd was significantly accumulated and was higher than the critical level of soil environmental quality (II), the available and total Cd concentrations were 0.248 mg x kg(-1) and 1.21 mg x kg(-1), which were 10 and 6.1 times higher than those of the control areas. No significant correlations were found between available and total heavy metals except between available Cd and total Cd. All the heavy metals were mainly accumulated in the top layer (0-10 cm). Spatially, soils and plants high in heavy metal concentration were distributed within the radius of about 100 m from the waste water outlet for Cu, Zn and Cd and about 200 m for Pb, and decreased exponentially with the distance from the factory. Affected by wastewater irrigation, contents of Cu, Pb and Cd in maize were 4.74, 0.129 and 0.036 mg x kg(-1) which were slightly higher than those in the control area. The content of Zn was similar to that in the control area. Affected by the vehicle exhaust, the over standard rate of Pb was 5.7% in maize. All the heavy metals did not show significant correlation between soil and crop, except Cd. The square correlation coefficients were 0

  12. Effects of Heavy Metals on Activated Sludge Microorganism

    Institute of Scientific and Technical Information of China (English)

    XIE Bing; XI Dan-li; CHEN Ji-hua


    The efforts of heavy metals on activated sludge microorganisms are reviewed. Although some heavy metals play an important role in the life of microorganism, heavy metals concentrations above toxic levels inhibit biological processes. Copper, zinc, nickel,cadmium and chromium were mostly studied because of their toxicity and widely used, regardless of single or combination. The microorganism response to these heavy metals varied with species and concentrations of metals,factors such as pH, sludge age, MLSS etc. also affect toxicity on the microorganism. The acclimation could extend the microorganism tolerance of heavy metals. The effects of heavy metals on sludge microorganisms could be described with different models, such as Sigmoidal and Monod equation. The kinetic constants are the useful indexes to estimate the heavy metals inhibition on activated sludge system. Methods to measure the toxicity and effects on microorganism community were also reviewed.

  13. Evaluation of crack arrest fracture toughness of parent plate, weld metal and heat affected zone of BIS 812 EMA ship plate steel (United States)

    Burch, I. A.


    The steel chosen for the pressure hull of the Collins class submarine has undergone evaluation to compare the crack arrest fracture toughness, K(Ia), of the parent plate with that of weld metal and heat affected zone. The tests were conducted over a range of subzero temperatures on specimens slightly outside the ASTM standard test method specimen configuration. Shallow face grooved specimens were used to vary the propagating crack velocity from that of non face grooved specimens and determine if K(Ia), is sensitive to changes in crack velocity. The weld metal, heat affected zone (HAZ), and parent plate were assessed to determine if the welding process had a deleterious effect on the crack arrest properties of this particular steel. Tests on each of these regions revealed that, for the combination of parent plate, welding procedure and consumables, no adverse effect on crack arrest properties was encountered. Crack arrest fracture toughness of the weld metal and HAZ was superior to that of the parent plate at comparable temperatures.

  14. Toxicity of heavy metals and metal-containing nanoparticles on plants. (United States)

    Mustafa, Ghazala; Komatsu, Setsuko


    Plants are under the continual threat of changing climatic conditions that are associated with various types of abiotic stresses. In particular, heavy metal contamination is a major environmental concern that restricts plant growth. Plants absorb heavy metals along with essential elements from the soil and have evolved different strategies to cope with the accumulation of heavy metals. The use of proteomic techniques is an effective approach to investigate and identify the biological mechanisms and pathways affected by heavy metals and metal-containing nanoparticles. The present review focuses on recent advances and summarizes the results from proteomic studies aimed at understanding the response mechanisms of plants under heavy metal and metal-containing nanoparticle stress. Transport of heavy metal ions is regulated through the cell wall and plasma membrane and then sequestered in the vacuole. In addition, the role of different metal chelators involved in the detoxification and sequestration of heavy metals is critically reviewed, and changes in protein profiles of plants exposed to metal-containing nanoparticles are discussed in detail. Finally, strategies for gaining new insights into plant tolerance mechanisms to heavy metal and metal-containing nanoparticle stress are presented. This article is part of a Special Issue entitled: Plant Proteomics--a bridge between fundamental processes and crop production, edited by Dr. Hans-Peter Mock.

  15. Repressive Tolerance

    DEFF Research Database (Denmark)

    Pedersen, Morten Jarlbæk


    to an administrative culture of repressive tolerance of organised interests: authorities listen but only reacts in a very limited sense. This bears in it the risk of jeopardising the knowledge transfer from societal actors to administrative ditto thus harming the consultation institutions’ potential for strengthening...

  16. Towards Tolerance

    NARCIS (Netherlands)

    Lisette Kuyper; Jurjen Iedema; Saskia Keuzenkamp


    Across Europe, public attitudes towards lesbian, gay and bisexual (LGB) individuals range from broad tolerance to widespread rejection. Attitudes towards homosexuality are more than mere individual opinions, but form part of the social and political structures which foster or hinder the equality and

  17. Effect of a heavy metal on ecto- and vesicular-arbuscular mycorrhizal fungi: The physiology, ultrastructure, and ecology of copper stress and tolerance

    Energy Technology Data Exchange (ETDEWEB)

    Gruhn, C.M.


    The first chapter examines the enzyme tyrosinase in several ectomycorrhizal fungi and shows that its activity is altered in these fungi in response to copper. Polyamines are also examined, and it is shown that their levels are altered in some ectomycorrhizal fungi due to copper stress but not in others. The second chapter uses transmission electron microscopy to demonstrate that copper is bound to the hyphae of ectomycorrhizal fungi grown on solid media, but the location of the binding varies between fungal species. In vitro copper tolerances of a number of ectomycorrhizal species are compared and differences in tolerance are evident between species and between different isolates of the same species. In the third chapter, four ectomycorrhizal fungi and one nonmycorrhizal fungus are evaluated for their ability to improve the growth of Japanese Red Pine under conditions of copper stress. Improvement of pine seedling growth is not correlated with in vitro copper tolerance of the fungus, but is related to the degree of compatibility between host and fungus. Despite differences in in vitro tolerance between three isolates of the same species, there are no differences in the effect of the isolates on the tree host under conditions of copper stress. Ectomycorrhizal fungi were also inoculated in pairs on pine seedlings and the competitive abilities of the fungi are compared under stressed and nonstressed conditions. The fourth chapter discusses the results of inoculation of pine with a nonhost fungus which stimulates dichotomous branching of the root system. The compound responsible for the branching is demonstrated to be indole-3-acetic acid (IAA), a plant growth hormone. The final two chapters deal with endomycorrhizal fungi.

  18. Properties and Technology for Quasi-Composite Blanket Using Natural Reinforcement of the Metal by Strain Affected Areas

    Directory of Open Access Journals (Sweden)

    A. Kirichek


    Full Text Available Techniques for making materials with advanced performance attributes at the expense of blanket heterogeneous strengthening are considered. A new trend is defined in a multiple increase of performance attributes in metal materials by natural reinforcement with nanostructural and ultra-fine-grained fragments. The application of a wave strain hardening technique is substantiated for obtaining a heterogeneous structure in wide-area listed full-size products including bulky ones. A high carrying capacity of heavy-loaded material with a deep-strengthened blanket is determined.

  19. Metamorphosis affects metal concentrations and isotopic signatures in a mayfly (Baetis tricaudatus): Implications for the aquatic-terrestrial transfer of metals (United States)

    Wesner, Jeff S.; Walters, David; Schmidt, Travis S.; Kraus, Johanna M.; Stricker, Craig A.; Clements, William H.; Wolf, Ruth E.


    Insect metamorphosis often results in substantial chemical changes that can alter contaminant concentrations and fractionate isotopes. We exposed larval mayflies (Baetis tricaudatus) and their food (periphyton) to an aqueous zinc gradient (3-340 µg Zn/l) and measured zinc concentrations at different stages of metamorphosis: larval, subimago, and imago. We also measured changes in stable isotopes (δ15N and δ13C) in unexposed mayflies. Larval zinc concentrations were positively related to aqueous zinc, increasing 9-fold across the exposure gradient. Adult zinc concentrations were also positively related to aqueous zinc, but were 7-fold lower than larvae. This relationship varied according to adult substage and sex. Tissue concentrations in female imagoes were not related to exposure concentrations, but the converse was true for all other stage-by-sex combinations. Metamorphosis also increased δ15N by ~0.8‰, but not δ13C. Thus, the main effects of metamorphosis on insect chemistry were large declines in zinc concentrations coupled with increased δ15N signatures. For zinc, this change was largely consistent across the aqueous exposure gradient. However, differences among sexes and stages suggest that caution is warranted when using nitrogen isotopes or metal concentrations measured in one insect stage (e.g. larvae) to assess risk to wildlife that feed on subsequent life stages (e.g. adults).

  20. Factors affecting metal exchange between sediment and water in an estuarine reservoir: a spatial and seasonal observation. (United States)

    Kang, Joo-Hyon; Lee, Young Geun; Lee, Keun-Young; Cha, Sung Min; Cho, Kyung Hwa; Lee, Yun Seok; Ki, Seo Jin; Yoon, In-Ho; Kim, Kyoung-Woong; Kim, Joon Ha


    Water quality response in a reservoir has often been assessed using relatively restricted datasets that cannot provide sufficient information, thereby giving rise to a dramatic over- or underestimate of actual figures. In this paper we discuss how the levels of metallic elements between the sediment and overlying water in an estuarine reservoir can be influenced by aquatic parameters in response to spatial and seasonal conditions. To better elucidate the interfacial exchange between sediment and water, statistical analyses are employed to intensive data sets collected from the Yeongsan Reservoir (YSR), Korea, which has undergone widespread deterioration in water quality due to the continuous growth of anthropogenic sources. During three seasonal sampling campaigns, we found that oxygen deficiency at the bottom water layer promotes Fe and Ni accumulation in sediment, likely due to the formation of sulfide and oxide complexes under anoxic and suboxic environments, respectively. In addition, salinity levels as high as 11 per thousand in the bottom water layer during autumn substantially increase the release of Mn, restricting the use of YSR as a primary source of agricultural irrigation water. Although most dissolved metals are at acceptable levels for sustaining aquatic life, it is recommended that for long-term planning the elevated Fe and Mn levels in sediment should be controlled with oxygen deficiency during dry weather to ensure a sustainable water supply or, at a minimum, better coordinated operation of YSR.

  1. Colloid formation and metal transport through two mixing zones affected by acid mine drainage near Silverton, Colorado (United States)

    Schemel, L.E.; Kimball, B.A.; Bencala, K.E.


    Stream discharges and concentrations of dissolved and colloidal metals (Al, Ca, Cu, Fe, Mg, Mn, Pb, and Zn), SO4, and dissolved silica were measured to identify chemical transformations and determine mass transports through two mixing zones in the Animas River that receive the inflows from Cement and Mineral Creeks. The creeks were the dominant sources of Al, Cu, Fe, and Pb, whereas the upstream Animas River supplied about half of the Zn. With the exception of Fe, which was present in dissolved and colloidal forms, the metals were dissolved in the acidic, high-SO4 waters of Cement Creek (pH 3.8). Mixing of Cement Creek with the Animas River increased pH to near-neutral values and transformed Al and some additional Fe into colloids which also contained Cu and Pb. Aluminium and Fe colloids had already formed in the mildly acidic conditions in Mineral Creek (pH 6.6) upstream of the confluence with the Animas River. Colloidal Fe continued to form downstream of both mixing zones. The Fe- and Al-rich colloids were important for transport of Cu, Pb, and Zn, which appeared to have sorbed to them. Partitioning of Zn between dissolved and colloidal phases was dependent on pH and colloid concentration. Mass balances showed conservative transports for Ca, Mg, Mn, SO4, and dissolved silica through the two mixing zones and small losses (< 10%) of colloidal Al, Fe and Zn from the water column.

  2. Study Progress on the Tolerating and Accumulating Mechanism of Edible Mushrooms on Heavy Metals%食用菌对重金属耐受和富集机理的研究进展

    Institute of Scientific and Technical Information of China (English)

    朱华玲; 班立桐; 徐晓萍


    The possible mechanisms on edible mushrooms tolerating heavy metals were discussed from aspects such as the defense of the extracellular polymer, selective absorption of the cell membrane, the change of the enzymatic activity as well as the alexipharmic interaction of the metal sulfur protein. The mechanism on the edible fungus accumulating heavy metals was expounded from the views of biological adsorption of the cellular surface, growth necessary and “the first residence” distribution.%从胞外多聚物的防御、细胞膜的选择性吸收、酶活性的改变以及金属硫蛋白的解毒作用等方面,分析食用菌耐受重金属的可能机理;从细胞表面的生物吸附、生长所需、"优先居所"分布等方面,探讨食用菌富集重金属的机理.

  3. Mechanical tolerance stackup and analysis

    CERN Document Server

    Fischer, Bryan R


    Use Tolerance Analysis Techniques to Avoid Design, Quality, and Manufacturing Problems Before They Happen Often overlooked and misunderstood, tolerance analysis is a critical part of improving products and their design processes. Because all manufactured products are subject to variation, it is crucial that designers predict and understand how these changes can affect form, fit, and function of parts and assemblies--and then communicate their findings effectively. Written by one of the developers of ASME Y14.5 and other geometric dimension and tolerancing (GD&T) standards, Mechanical Tolerance

  4. Bauxite-supported Transition Metal Oxides: Promising Low-temperature and SO2-tolerant Catalysts for Selective Catalytic Reduction of NOx


    Xiuyun Wang; Wen Wu; Zhilin Chen; Ruihu Wang


    In order to develop low-temperature (below 200 °C) and SO2-tolerant catalysts for selective catalytic reduction (SCR) of NOx, a series of cheap M/bauxite (M = Mn, Ni and Cu) catalysts were prepared using bauxite as a support. Their SCR performances are much superior to typical V2O5/TiO2, the addition of M into bauxite results in significant promotion of NOx removal efficiency, especially at low temperature. Among the catalysts, Cu/bauxite exhibits wide temperature window over 50–400 °C, stron...

  5. [Advances in functional genomics studies underlying acetic acid tolerance of Saccharomyces cerevisiae]. (United States)

    Zhao, Xinqing; Zhang, Mingming; Xu, Guihong; Xu, Jianren; Bai, Fengwu


    Industrial microorganisms are subject to various stress conditions, including products and substrates inhibitions. Therefore, improvement of stress tolerance is of great importance for industrial microbial production. Acetic acid is one of the major inhibitors in the cellulosic hydrolysates, which affects seriously on cell growth and metabolism of Saccharomyces cerevisiae. Studies on the molecular mechanisms underlying adaptive response and tolerance of acetic acid of S. cerevisiae benefit breeding of robust strains of industrial yeast for more efficient production. In recent years, more insights into the molecular mechanisms underlying acetic acid tolerance have been revealed through analysis of global gene expression and metabolomics analysis, as well as phenomics analysis by single gene deletion libraries. Novel genes related to response to acetic acid and improvement of acetic acid tolerance have been identified, and novel strains with improved acetic acid tolerance were constructed by modifying key genes. Metal ions including potassium and zinc play important roles in acetic acid tolerance in S. cerevisiae, and the effect of zinc was first discovered in our previous studies on flocculating yeast. Genes involved in cell wall remodeling, membrane transport, energy metabolism, amino acid biosynthesis and transport, as well as global transcription regulation were discussed. Exploration and modification of the molecular mechanisms of yeast acetic acid tolerance will be done further on levels such as post-translational modifications and synthetic biology and engineering; and the knowledge obtained will pave the way for breeding robust strains for more efficient bioconversion of cellulosic materials to produce biofuels and bio-based chemicals.

  6. FE analysis of cruciform welded joints considering different mechanical properties for base material, heat affected zone and weld metal

    Directory of Open Access Journals (Sweden)

    Pasqualino Corigliano


    Full Text Available The aim of this scientific work was to investigate the behaviour of cruciform welded joints under static loading using a full-field technique: Digital Image Correlation. The material curves, relative to different zones (base material, heat affected zone, weld, were obtained by hardness measurements, which were done by means of a fully automated hardness scanner with high resolution. This innovative technique, based on the UCI method, allowed to identify the different zones and to assess their different mechanical properties, which were considered in the finite element model. Finally the finite element model was validated experimentally, comparing the results with the measurements obtained using the Digital Image Correlation technique.

  7. Contents and toxicity of heavy metals in soils of the zone affected by aerial emissions from the Severonikel Enterprise (United States)

    Evdokimova, G. A.; Kalabin, G. V.; Mozgova, N. P.


    In 2009, the zoning of the terrestrial ecosystems in the area exposed to aerial emissions from the Severonikel Enterprise (Murmansk oblast) was performed on the basis of the parameters characterizing the state of the soils, including the contents of the main heavy metal pollutants and exchangeable calcium and magnesium, the soils' pH, the ratio of the organic to mineral soil components, and the state of the soils' microbiota. Three zones differing in the degree of the soil pollution were delimited. These were the zones of heavy, moderate, and weak pollution, which extended for up to 3, 25, and 50 km from the emission source in the prevailing wind direction. The data on the amount of bacterial and fungal biomass provided evidence of the profound degradation of the soils in the heavily polluted zone. In particular, the biomass of the soil microbiota, including its prokaryotic and eukaryotic components, was two to six times lower in this zone than in the background (control) area. The soils of the heavily polluted zone can be classified as strongly toxic for plants, and most of the soils of the moderately polluted zone also fall into the same category.

  8. Alumina polymorphs affect the metal immobilization effect when beneficially using copper-bearing industrial sludge for ceramics. (United States)

    Tang, Yuanyuan; Lu, Xiuqing; Shih, Kaimin


    The feasibility of recycling copper-bearing industrial sludge as a part of ceramic raw materials was evaluated through thermal interaction of sludge with aluminum-rich precursors. To observe copper incorporation mechanism, mixtures of copper-bearing sludge with alumina polymorphs (γ-Al2O3 and α-Al2O3) were fired between 750 and 1250°C. Different copper-hosting phases were identified by X-ray diffraction, and CuAl2O4 was found to be the predominant phase throughout the reactions. The experimental results indicate different CuAl2O4 initiating temperatures for two alumina materials, and the optimal temperature for CuAl2O4 formation is around 1100°C. To monitor the stabilization effect, prolonged leaching tests were carried out to leach sintered products for up to 20d. The results clearly demonstrate a substantial decrease in copper leachability for products with higher CuAl2O4 content formed from both alumina precursors despite their different sintering behavior. Meanwhile, the leachability of aluminum was much lower than that of copper, and it decreased by more than fourfold through the formation of CuAl2O4 spinel in γ-Al2O3 system. This study clearly indicates spinel formation as the most crucial metal stabilization mechanism when sintering multiphase copper-bearing industrial sludge with aluminum-rich ceramic raw materials, and suggests a promising and reliable technique for reusing industrial sludge.

  9. Geochemistry of trace metals in shelf sediments affected by seasonal and permanent low oxygen conditions off central Chile, SE Pacific (˜36°S) (United States)

    Muñoz, Praxedes; Dezileau, Laurent; Cardenas, Lissette; Sellanes, Javier; Lange, Carina B.; Inostroza, Jorge; Muratli, Jesse; Salamanca, Marco A.


    Trace metals (Cd, U, Co, Ni, Cu, Ba, Fe, Mn), total organic carbon (TOC) and C and N stable isotope signatures (δ 13C and δ 15N) were determined in short sediments cores from the inner and outer shelf off Concepción, Chile (˜36°S). The objectives were to establish the effect of environmental conditions on trace metal distributions at two shelf sites, one affected by seasonal oxygenation and the other by permanent low oxygen conditions due to the presence of the oxygen minimum zone (OMZ). We evaluate trace metals as proxies of past changes in primary productivity and the bottom water oxygen regime. Concentrations of pore water sulfides and NH4+ were also measured as indicators of the main diagenetic pathways at each site. Our results for the inner shelf (seasonal suboxia) suggest that the oxidative state of the sediments responds to seasonal pulses of organic matter and that seasonal oxygenation develops during high and low primary productivity in the water column. Here, positive fluxes (to the water column) estimated from pore water concentrations of several elements were observed (Ba, Co, Ni, Fe and Mn). The less reduced environment at this site produces authigenic enrichment of Cu associated with the formation of oxides in the oxic surface sediment layer, and the reduction of U within deeper sediment sections occur consistently with negative estimated pore water fluxes. In the outer shelf sediments (permanent suboxia, OMZ site), negative fluxes (to the sediment) were estimated for all elements, but these sediments showed authigenic enrichments only for Cd, Cu and U. The short oxygenation period during the winter season did not affect the accumulation of these metals on the shelf. The distribution of Cu, Cd and U have been preserved within the sediments and the authigenic accumulation rates estimated showed a decrease from the deep sections of the core to the surface sediments. This could be explained by a gradual decrease in the strength of the OMZ in the

  10. Assessment of metal loads in watersheds affected by acid mine drainage by using tracer injection and synoptic sampling: Cement Creek, Colorado, USA (United States)

    Kimball, B.A.; Runkel, R.L.; Walton-Day, K.; Bencala, K.E.


    for the watershed to support remediation decisions, and quantifies processes affecting metal transport. Published by Elsevier Science Ltd.

  11. 40 CFR 180.425 - Clomazone; tolerances for residues. (United States)


    ... citations affecting § 180.425, see the List of CFR Sections Affected, which appears in the Finding Aids... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Clomazone; tolerances for residues... § 180.425 Clomazone; tolerances for residues. (a) General. Tolerances are established for residues...

  12. Tolerance of transgenic canola plants (Brassica napus) amended with plant growth-promoting bacteria to flooding stress at a metal-contaminated field site. (United States)

    Farwell, Andrea J; Vesely, Susanne; Nero, Vincent; Rodriguez, Hilda; McCormack, Kimberley; Shah, Saleh; Dixon, D George; Glick, Bernard R


    The growth of transgenic canola (Brassica napus) expressing a gene for the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase was compared to non-transformed canola exposed to flooding and elevated soil Ni concentration, in situ. In addition, the ability of the plant growth-promoting bacterium Pseudomonas putida UW4, which also expresses ACC deaminase, to facilitate the growth of non-transformed and transgenic canola under the above mentioned conditions was examined. Transgenic canola and/or canola treated with P. putida UW4 had greater shoot biomass compared to non-transformed canola under low flood-stress conditions. Under high flood-stress conditions, shoot biomass was reduced and Ni accumulation was increased in all instances relative to low flood-stress conditions. This is the first field study to document the increase in plant tolerance utilizing transgenic plants and plant growth-promoting bacteria exposed to multiple stressors.

  13. Bauxite-supported Transition Metal Oxides: Promising Low-temperature and SO2-tolerant Catalysts for Selective Catalytic Reduction of NOx. (United States)

    Wang, Xiuyun; Wu, Wen; Chen, Zhilin; Wang, Ruihu


    In order to develop low-temperature (below 200 °C) and SO2-tolerant catalysts for selective catalytic reduction (SCR) of NOx, a series of cheap M/bauxite (M = Mn, Ni and Cu) catalysts were prepared using bauxite as a support. Their SCR performances are much superior to typical V2O5/TiO2, the addition of M into bauxite results in significant promotion of NOx removal efficiency, especially at low temperature. Among the catalysts, Cu/bauxite exhibits wide temperature window over 50-400 °C, strong resistance against SO2 and H2O as well as good regeneration ability in SCR of NOx. NOx conversion is more than 80% at 50-200 °C, and N2 selectivity is more than 98%. Cu/bauxite can serve as a promising catalyst in SCR of NOx.

  14. Over-expression of gsh1 in the cytosol affects the photosynthetic apparatus and improves the performance of transgenic poplars on heavy metal-contaminated soil. (United States)

    Ivanova, L A; Ronzhina, D A; Ivanov, L A; Stroukova, L V; Peuke, A D; Rennenberg, H


    compared to the control site. Thus, poplars over-expressing γ-ECS in the cytosol were more tolerant to heavy metal stress under field conditions than wild-type plants according to the parameters analysed. Correlation analysis revealed strong dependence of cell number per leaf area unit, chloroplast parameters and mesophyll resistance with the GSH level in poplar leaves.

  15. Isolation and characterization of a mesophilic heavy-metals-tolerant sulfate-reducing bacterium Desulfomicrobium sp. from an enrichment culture using phosphogypsum as a sulfate source. (United States)

    Azabou, Samia; Mechichi, Tahar; Patel, Bharat K C; Sayadi, Sami


    A sulfate-reducing bacterium, was isolated from a 6 month trained enrichment culture in an anaerobic media containing phosphogypsum as a sulfate source, and, designated strain SA2. Cells of strain SA2 were rod-shaped, did not form spores and stained Gram-negative. Phylogenetic analysis of the 16S rRNA gene sequence of the isolate revealed that it was related to members of the genus Desulfomicrobium (average sequence similarity of 98%) with Desulfomicrobium baculatum being the most closely related (sequence similarity of 99%). Strain SA2 used thiosulfate, sulfate, sulfite and elemental sulfur as electron acceptors and produced sulfide. Strain SA2 reduced sulfate contained in 1-20g/L phosphogypsum to sulfide with reduction of sulfate contained in 2g/L phosphogypsum being the optimum concentration. Strain SA2 grew with metalloid, halogenated and non-metal ions present in phosphogypsum and with added high concentrations of heavy metals (125ppm Zn and 100ppm Ni, W, Li and Al). The relative order for the inhibitory metal concentrations, based on the IC(50) values, was Cu, Te>Cd>Fe, Co, Mn>F, Se>Ni, Al, Li>Zn.

  16. X-ray diffraction analysis and metal physics modeling of static strain aging and thermal dislocation recovery in the mechanically affected zone of surface finished hardened steel

    Energy Technology Data Exchange (ETDEWEB)

    Gegner, Juergen [SKF GmbH, Dept. of Material Physics, Schweinfurt (Germany)


    After heat treatment, finish machining of the hardened steel represents the last manufacturing step of machine elements. The practically most important operation of grinding is applied to achieve edge zone compressive residual stresses, best surface quality and dimensional accuracy. Metal removal involves high plastic deformation work. Glide and intersection processes raise the density and produce lower energy substructures of dislocations. The temperature and time behavior of post-machining thermal treatment is analyzed on ground and honed martensitic SAE 52100 rolling bearing steel. Microstructure stabilization is reflected in a large XRD line width decrease on the surface. The kinetics is modeled by rate-controlling carbide dissolution as the carbon source for Cottrell-type segregation at dislocations. This static strain aging is verified by the formation of a slight white etching surface layer. The metal physics model is extended to also consider superimposed thermal dislocation recovery. Both effects are separable. In rolling contact fatigue tests under mixed friction running conditions, air reheating of the samples below the tempering temperature, which avoids hardness loss, leads to a significant lifetime increase. Thermal post-treatment after cold working results in similar changes of the XRD line width in the larger mechanically affected edge zone.

  17. Cucumber metal tolerance protein CsMTP9 is a plasma membrane H⁺-coupled antiporter involved in the Mn²⁺ and Cd²⁺ efflux from root cells. (United States)

    Migocka, Magdalena; Papierniak, Anna; Kosieradzka, Anna; Posyniak, Ewelina; Maciaszczyk-Dziubinska, Ewa; Biskup, Robert; Garbiec, Arnold; Marchewka, Tadeusz


    Members of the plant metal tolerance protein (MTP) family have been classified into three major groups - Zn-CDF, Mn-CDF and Zn/Fe-CDF - however, the selectivity of most of the MTPs has not been confirmed yet. Cucumber gene CsMTP9 encoding a putative CDF transporter homologous to members of the Mn-CDF cluster is expressed exclusively in roots. The relative abundance of CsMTP9 transcript and protein in roots is significantly increased under Mn excess and Cd. Immunolocalization with specific antibodies revealed that CsMTP9 is a plasma membrane transporter that localizes to the inner PM domain of root endodermal cells. The plasma membrane localization of CsMTP9 was confirmed by the expression of the fusion proteins of GFP (green fluorescent protein) and CsMTP9 in yeast and protoplasts prepared from Arabidopsis cells. In yeast, CsMTP9 transports Mn(2+) and Cd(2+) via a proton-antiport mechanism with an apparent Km values of approximately 10 μm and 2.5 μm for Mn(2+) and Cd(2+) , respectively. In addition, CsMTP9 expression in yeast rescues the Mn- and Cd-hypersensitive phenotypes through the enhanced efflux of Mn(2+) and Cd(2+) from yeast cells. Similarly, the overexpression of CsMTP9 in A. thaliana confers increased resistance of plants to Mn excess and Cd but not to other heavy metals and leads to the enhanced translocation of manganese and cadmium from roots to shoots. These findings indicate that CsMTP9 is a plasma membrane H(+) -coupled Mn(2+) and Cd(2+) antiporter involved in the efflux of manganese and cadmium from cucumber root cells by the transport of both metals from endodermis into vascular cylinder.

  18. Antibiotic tolerance and microbial biofilms

    DEFF Research Database (Denmark)

    Folkesson, Anders

    Increased tolerance to antimicrobial agents is thought to be an important feature of microbes growing in biofilms. We study the dynamics of antibiotic action within hydrodynamic flow chamber biofilms of Escherichia coli and Pseudomonas aeruginosa using isogenic mutants and fluorescent gene...... expression reporters and we address the question of how biofilm organization affects antibiotic susceptibility. The dynamics of microbial killing is monitored by viable count determination, and confocal laser microscopy. Our work shows that the apparent increased antibiotic tolerance is due to the formation...... of antibiotic tolerant subpopulations within the biofilm. The formation of these subpopulations is highly variable and dependent on the antibiotic used, the biofilm structural organization and the induction of specific tolerance mechanisms....

  19. 77 FR 25904 - Acequinocyl; Pesticide Tolerances (United States)


    ..., but rather to provide a guide for readers regarding entities likely to be affected by this action..., Princeton, NJ 08540. The petition requested that 40 CFR 180.599 be amended by establishing tolerances for.... C. Revisions to Petitioned-For Tolerances Based on analysis of the residue field trial...

  20. Civic Tolerance among Honors Students (United States)

    Shepherd, Gordon; Shepherd, Gary


    As important as cognitive outcomes are in assessing the educational merits of honors programs, the authors ask whether honors programs affect the values and social attitudes of their students differently than other students: in particular, whether honors students are more or less tolerant than other students and, if so, in what ways and why. There…

  1. Subcellular localization of copper in tolerant and non-tolerant plant

    Institute of Scientific and Technical Information of China (English)

    NI Cai-ying; CHEN Ying-xv; LIN Qi; TIAN Guang-ming


    The ability of Elsholtzia splendens Naki( E. splendens) to accumulate copper appears to be governed by its high degree of copper tolerance. However, the tolerance mechanism on the physiological basis is unknown. Using transmission electron microscope (TEM) and energy dispersive analysis of X-rays(EDX), the likely location of copper within the cells of the tolerant and non-tolerant was determined. Here the role of vacuolar and cell wall compartmentalization in this copper tolerant plant were investigated. A direct comparison of copper locations of E. splendens and the non-tolerant Astragalus sinicus L. ( A. sinicus) showed that the majority of copper in the tolerant was localized primarily in the vacuolar, cell wall, on the plasmamembrane, beside lipid grains induced by copper pollution, in the chloroplasts and amyloids; but in the non-tolerant, copper precipitates only be observed on the plasmamembrane, in the chloroplasts and cytoplasm under copper exposure conditions that were toxic to both species. This revealed that the tolerant accumulates more copper in the vacuole and cell wall than the non-tolerant, where was regarded as the storage compartment of tolerant plant or hyperaccumulator for heavy metals.

  2. Isolation and Identification of Four Tolerance Bacteria and the Preliminary Study for Pollution Remediation of Heavy Metals%耐性细菌的分离鉴定及重金属污染修复初步研究

    Institute of Scientific and Technical Information of China (English)

    陈佳亮; 刘晓文; 张雅静; 方晓航


    Qing Yuan is one of the biggest electronic wastes dismantling base in China, the production pattern of individual workshop has been going on for more than 20 years. A large number of electronic wastes and treatment residuals were dumped in croplands, ditches and valleys. It made the surrounding soils polluted for a long time by Cd, Cu and Pb. There had lots of researches about the present situation analysis and health risk evaluation for heavy metals contaminated soil surrounding dismantling area. But there still had less reports on the study of bioremediation technologies for the e-waste pollution by combined heavy metals. Four tolerance bacteria was isolated from contaminated soil of e-waste dismantling area of qingyuan by this means of enrichment, domestication and isolation. The tolerance bacteria were identified by analyzed of colony morphology and scanning electron microscope and 16S rDNA technology. Four strains of HS-01, JH-02, YB-03 and JY-04 were respectively Sporosarcina aquimarina, Sporosarcina saromensis, Bacillus megaterium and Bacillus methylotrophicus. The growth characteristic experiments indicated that the bacteria of HS-01 and JY-04 had same growth cycle, the regulatory phase was 0-8 h, 8-12 h was the logarithmic phase, 12-24 h was stable phase and 24-32 h was decline phase;Bacterial JH-02 and YB-03 had same growth cycle, regulatory phase was 0-4 h, 4-12 h was logarithmic phase, 12-24 h was stable phase, and 24-32 h was decline phase. The optimum temperature and pH of HS-01, JH-02 and JY-04 was 30 ℃ and 8, while YB-03 was 35 ℃ and 7.5 respectively. With the increase of mass concentration of heavy metal ions, biosorption experiments showed that the adsorption amounts of four tolerance bacteria to heavy metal ions gradually increased, but the growth ratios of adsorption amounts and adsorption ratios were gradually decreased. The maximum adsorption amounts of four tolerance bacteria to Cd2+, Cu2+, Pb2+were 2.25, 2.05, 2.28, 2.25 mg,8.19, 4.95, 8

  3. Effects of water stress, organic amendment and mycorrhizal inoculation on soil microbial community structure and activity during the establishment of two heavy metal-tolerant native plant species. (United States)

    Fernández, D A; Roldán, A; Azcón, R; Caravaca, F; Bååth, E


    Our aim was to examine the effect of water stress on plant growth and development of two native plant species (Tetraclinis articulata and Crithmum maritimum) and on microbial community composition and activity in the rhizosphere soil, following the addition of an organic amendment, namely sugar beet residue (SBR), and/or the inoculation with an arbuscular mycorrhizal (AM) fungus, namely Glomus mosseae, in a non-sterile heavy metal-polluted soil. The AM inoculation did not have any significant effect on plant growth of both species. In T. articulata, SBR increased shoot growth, foliar P, total phospholipid fatty acids (PLFA), fungi-related PLFA, AM fungi-related neutral lipid fatty acid, bacterial gram-positive/gram-negative PLFA ratio and the β-glucosidase and dehydrogenase activities. SBR and AM inoculation increased phosphatase activity in T. articulata plants grown under drought conditions. In both plants, there was a synergistic effect between AM inoculation and SBR on mycorrhizal colonisation under drought conditions. In C. maritimum, the increase produced by the SBR on total amounts of PLFA, bacterial gram-positive-related PLFA and bacterial gram-negative-related PLFA was considerably higher under drought conditions. Our results suggest that the effectiveness of the amendment with regard to stimulating microbial communities and plant growth was largely limited by drought, particularly for plant species with a low degree of mycorrhizal colonisation.

  4. Exploring the Influence of Environmental Factors on Bacterial Communities within the Rhizosphere of the Cu-tolerant plant, Elsholtzia splendens (United States)

    Jiang, Longfei; Song, Mengke; Yang, Li; Zhang, Dayi; Sun, Yingtao; Shen, Zhenguo; Luo, Chunling; Zhang, Gan


    Bacterial communities of rhizospheric soils play an important role in the tolerance and uptake of metal-tolerant/hyperaccumulating plants to metals, e.g. the Cu-tolerant Elsholtzia splendens native to China. In this work, pyrosequencing of the bacterial 16S rRNA gene was firstly applied to investigate the rhizospheric bacterial community of E. splendens grown at Cu contaminated sites. The 47 phyla including 11 dominant phyla (>1%) in E. splendens rhizosphere were presented. The effects of Cu and other environmental factors (total organic carbon, total nitrogen and pH) on the rhizospheric bacterial community were studied comprehensively. The phyla abundances were affected by the environmental factors to different extent, and we found pH, instead of Cu concentration, influenced UniFrac distance significantly and was identified as the most important environmental factor affecting bacterial community. In addition, the influence of environmental factors on gene profiles was explored according to the predicted metagenomes obtained by PICRUSt (phylogenetic investigation of communities by reconstruction of unobserved states). Our study illustrates a view about Cu-tolerant E. splendens rhizospheric bacterial communities (composition, diversity and gene profiles) and their influencing factors, giving a hand for the understanding on bacterial community is formed and affected in rhizosphere.

  5. Pseudomonas aeruginosa capability to recruit zinc under conditions of limited metal availability is affected by inactivation of the ZnuABC transporter (United States)

    D'Orazio, Melania; Mastropasqua, Maria Chiara; Cerasi, Mauro; Pacello, Francesca; Consalvo, Ada; Chirullo, Barbara; Mortensen, Brittany; Skaar, Eric P.; Ciavardelli, Domenico; Pasquali, Paolo; Battistoni, Andrea


    The ability of a large number of bacterial pathogens to multiply in the infected host and cause disease is dependent on their ability to express high affinity zinc importers. In many bacteria ZnuABC, a transporter of the ABC family, plays a central role in the process of zinc uptake in zinc poor environments, including the tissues of the infected host. To initiate an investigation into the relevance of the zinc uptake apparatus for Pseudomonas aeruginosa pathogenicity, we have generated a znuA mutant in the PA14 strain. We have found that this mutant strain displays a limited growth defect in zinc depleted media. The znuA mutant strain is more sensitive than the wild type strain to calprotectin-mediated growth inhibition, but both the strains are highly resistant to this zinc sequestering antimicrobial protein. Moreover, intracellular zinc content is not evidently affected by inactivation of the ZnuABC transporter. These findings suggest that P. aeruginosa is equipped with redundant mechanisms for the acquisition of zinc that might favor P. aeruginosa colonization of environments containing low levels of this metal. Nonetheless, deletion of znuA affects alginate production, reduces the activity of extracellular zinc-containing proteases, including LasA, LasB and Protease IV, and decreases the ability of P. aeruginosa to disseminate during systemic infections. These results indicate that efficient zinc acquisition is critical for the expression of various virulence features typical of P. aeruginosa and that ZnuABC also plays an important role in zinc homeostasis in this microorganism. PMID:25751674

  6. Diversity of arbuscular mycorrhizal fungus populations in heavy-metal-contaminated soils

    Energy Technology Data Exchange (ETDEWEB)

    Del Val, C.; Barea, J.M.; Azcon-Aguilar, C. [CSIC, Granada (Spain)


    High concentrations of heavy metals have been shown to adversely affect the size, diversity, and activity of microbial populations in soil. The aim of this work was to determine how the diversity of arbuscular mycorrhizal (AM) fungi is affected by the addition of sewage-amended sludge containing heavy metals in a long-term experiment. Due to the reduced number of indigenous AM fungal (AMF) propagules in the experimental soils, several host plants with different life cycles were used to multiply indigenous fungi. Six AMF ecotypes were found in the experimental soils, showing consistent differences with regard to their tolerance to the presence of heavy metals. AMF ecotypes ranged from very sensitive to the presence of metals to relatively tolerant to high rates of heavy metals in soil. Total AMF spore numbers decreased with increasing amounts of heavy metals in the soil. However, species richness and diversity as measured by the Shannon-Wiener index increased in soils receiving intermediate rates of sludge contamination but decreased in soils receiving the highest rate of heavy-metal-contaminated sludge. Relative densities of most AMF species were also significantly influenced by soil treatments. Host plant species exerted a selective influence on AMF population size and diversity. The authors conclude based on the results of this study that size and diversity of AMF populations were modified in metal-polluted soils, even in those with metal concentrations that were below the upper limits accepted by the European Union for agricultural soils.

  7. Fertilizers and Mixed Crop Cultivation of Chromium Tolerant and Sensitive Plants under Chromium Toxicity

    Directory of Open Access Journals (Sweden)

    B. Dheeba


    Full Text Available Zea mays (maize and Vigna radiata (green gram are found to be the chromium (Cr tolerant and sensitive plants, respectively. In the present paper, we investigate the reduction of the toxicity of Cr in the sensitive plants by the mixed crop cultivation in the field using various amendments. Further, the potassium dichromate was used as the source of hexavalent Cr. The results indicated that Cr adversely affects both the growth and yield of plants. The soil properties vary with Cr and different fertilizer amendments and the yield of both plants were affected by Cr. We conclude that metal accumulation of seeds of green gram was higher than corn and the application of single fertilizer either farm yard manure (FYM or nitrogen, phosphorous, and potassium (NPK enhances the growth and yield of both the tolerant and sensitive plants in the mixed crop cultivations.

  8. Multiple metal resistant transferable phenotypes in bacteria as indicators of soil contamination with heavy metals

    Energy Technology Data Exchange (ETDEWEB)

    Ryan, R.P.; Ryan, D.J.; Dowling, D.N. [Dept. of Science and Health, Inst. of Tech. Carlow, Carlow (Ireland)


    Environmental contamination by heavy metals affects microbial communities. The number of single and multiple heavy metal resistant bacteria may be an indicator of the level of contamination. This paper details the isolation and characterisation of metal resistant microorganisms isolated from rhizosphere/soil samples obtained from an abandoned zinc, lead and copper mine and a local unaffected site. This data was compared to the level of heavy metal in the soils to establish the effect of metals on the microbial community and to determine the relationship between pollutant levels and resistant strains. This paper outlines the diversity of transferable resistance determinants between both sites and details the levels of heavy metal resistant bacteria and those expressing transferable multiple heavy metal tolerance. Methods. The sample sites were located in Co. Galway, Ireland. The first sample site (site A) was a former lead, zinc and copper mine, which was closed in 1961 due to exhaustion of ore. The second site (site B) was located two and a half kilometres from the mining site and was not affected by the mining operations. Composite soil samples were characterised for general soil matrix composition, organic content, pH and general chemical parameters. The soil was also enumerated for the total viable heterotrophic counts and tested on Pseudomonas selective agar (PSA) for total Pseudomonas counts and Sucrose Asparagine (SA), which is semi-selective for fluorescent Pseudomonas. (orig.)

  9. Flooding tolerance of forage legumes. (United States)

    Striker, Gustavo G; Colmer, Timothy D


    We review waterlogging and submergence tolerances of forage (pasture) legumes. Growth reductions from waterlogging in perennial species ranged from >50% for Medicago sativa and Trifolium pratense to Lotus corniculatus, L. tenuis, and T. fragiferum For annual species, waterlogging reduced Medicago truncatula by ~50%, whereas Melilotus siculus and T. michelianum were not reduced. Tolerant species have higher root porosity (gas-filled volume in tissues) owing to aerenchyma formation. Plant dry mass (waterlogged relative to control) had a positive (hyperbolic) relationship to root porosity across eight species. Metabolism in hypoxic roots was influenced by internal aeration. Sugars accumulate in M. sativa due to growth inhibition from limited respiration and low energy in roots of low porosity (i.e. 4.5%). In contrast, L. corniculatus, with higher root porosity (i.e. 17.2%) and O2 supply allowing respiration, maintained growth better and sugars did not accumulate. Tolerant legumes form nodules, and internal O2 diffusion along roots can sustain metabolism, including N2 fixation, in submerged nodules. Shoot physiology depends on species tolerance. In M. sativa, photosynthesis soon declines and in the longer term (>10 d) leaves suffer chlorophyll degradation, damage, and N, P, and K deficiencies. In tolerant L corniculatus and L. tenuis, photosynthesis is maintained longer, shoot N is less affected, and shoot P can even increase during waterlogging. Species also differ in tolerance of partial and complete shoot submergence. Gaps in knowledge include anoxia tolerance of roots, N2 fixation during field waterlogging, and identification of traits conferring the ability to recover after water subsides.

  10. Metal hyperaccumulation armors plants against disease.

    Directory of Open Access Journals (Sweden)

    Helen Fones

    Full Text Available Metal hyperaccumulation, in which plants store exceptional concentrations of metals in their shoots, is an unusual trait whose evolutionary and ecological significance has prompted extensive debate. Hyperaccumulator plants are usually found on metalliferous soils, and it has been proposed that hyperaccumulation provides a defense against herbivores and pathogens, an idea termed the 'elemental defense' hypothesis. We have investigated this hypothesis using the crucifer Thlaspi caerulescens, a hyperaccumulator of zinc, nickel, and cadmium, and the bacterial pathogen Pseudomonas syringae pv. maculicola (Psm. Using leaf inoculation assays, we have shown that hyperaccumulation of any of the three metals inhibits growth of Psm in planta. Metal concentrations in the bulk leaf and in the apoplast, through which the pathogen invades the leaf, were shown to be sufficient to account for the defensive effect by comparison with in vitro dose-response curves. Further, mutants of Psm with increased and decreased zinc tolerance created by transposon insertion had either enhanced or reduced ability, respectively, to grow in high-zinc plants, indicating that the metal affects the pathogen directly. Finally, we have shown that bacteria naturally colonizing T. caerulescens leaves at the site of a former lead-zinc mine have high zinc tolerance compared with bacteria isolated from non-accumulating plants, suggesting local adaptation to high metal. These results demonstrate that the disease resistance observed in metal-exposed T. caerulescens can be attributed to a direct effect of metal hyperaccumulation, which may thus be functionally analogous to the resistance conferred by antimicrobial metabolites in non-accumulating plants.

  11. In situ study of defect migration kinetics and self-healing of twin boundaries in heavy ion irradiated nanotwinned metals. (United States)

    Li, J; Yu, K Y; Chen, Y; Song, M; Wang, H; Kirk, M A; Li, M; Zhang, X


    High energy particles introduce severe radiation damage in metallic materials, such as Ag. Here we report on the study on twin boundary (TB) affected zone in irradiated nanotwinned Ag wherein time accumulative defect density and defect diffusivity are substantially different from those in twin interior. In situ studies also reveal surprising resilience and self-healing of TBs in response to radiation. This study provides further support for the design of radiation-tolerant nanotwinned metallic materials.

  12. ATLANTIC-DIP: raised maternal body mass index (BMI) adversely affects maternal and foetal outcomes in glucose tolerant women classified using International Association of Diabetes and Pregnancy Study Groups (IADPSG) criteria

    LENUS (Irish Health Repository)

    Dennedy, MC


    Background and aims: Raised maternal body mass index (BMI), in association with hyperglycaemia is associated with adverse pregnancy outcome. Whether BMI has an independent effect on adverse pregnancy outcome is not clear. We aimed to investigate the effects of raised maternal BMI on pregnancy outcome in glucose tolerant women, classified using the IADPSG criteria.\\r\

  13. Heavy Metal Bioaccumulation and Toxicity with Special Reference to Microalgae

    Institute of Scientific and Technical Information of China (English)


    The bioaccumulation and toxicity of heavy metals were reviewed with special reference to microalgae, the key component of the food web in aquatic ecosystems. Heavy metals enter algal cells either by means of active transport or by endocytosis through chelating proteins and affect various physiological and biochemical processes of the algae. The toxicity primarily results from their binding to the sulphydryl groups in proteins or disrupting protein structure or displacing essential elements. Metals can break the oxidative balance of the algae, inducing antioxidant enzymes, such as superoxide dismutase (SOD), glutathione peroxidase (GPX) and ascorbate peroxidase (APX). The amount of oxidized proteins and lipids in the algal cells thus indicates the severity of the stress. Algal tolerance to heavy metal is highly dependent upon the defense response against the probable oxidative damages. Production of binding factors and proteins, exclusion of metals from cells by ion-selective transporters and excretion or compartmentalization have been suggested with regard to reducing heavy metal toxicity. However, a comprehensive description on the mechanisms underlining metal toxicity of microalgae and gaining tolerance is yet to be elaborated.

  14. Tolerance and Accumulation of Heavy Metals by Exophiala pisciphila Strain Isolated From Plant Roots Growing in Metal Polluted Soils%矿区植物根内嗜鱼外瓶霉对重金属的耐性和超积累作用

    Institute of Scientific and Technical Information of China (English)

    张玉洁; 李洪超; 赵之伟


    A DSE stain was isolated from plant roots of Arundinella bengalensis (Spring.) Druce, naturally growing on the plot of lead-zinc mine areas in Huize, Yunnan Province. The isolate was identified as an Exophiala pisciphila strain by morphological characteristics and ITSI-5.8S rDNA-ITS 2 sequence analysis. The tolerance to heavy metals and accumulation abilities or the E pisciphila strain were investigated. MICs (minimum inhibitory concentration) to Pb2+, Zn2+ and Cd1+ of the fungus were 2.3,0.51, and 3.1 mg/ml, respectively. The E. pisciphila strain was able to accumulate lead, zinc and cadmium over 20%, 15% and 5% of its biomass (by dry weight), respectively. It was demonstrated that the fungi was supper accumulative and multi-tolerant to these metals. Fungi colonization in the roots may play important roles in reducing toxiciry to THe plant root cells of heavy metals in soils.%从云南会泽铅-锌矿区自然生长植物密序野古草(Arundinella bengalensis (Spreng.) Druce)的健康根内分离得到一株深色有隔内生真菌(dark septate endophytes,DSE).据其形态学特征和ITS(I)-5.8S-rDNA-ITS2序列分析,鉴定为一株嗜鱼外瓶霉(Exophlala pisciphila).纯培养条件下研究了其对P2+、Zn2+、Cd2+的耐性和超积累作用.结果表明,此菌株在液体合成培养基上可以分别耐受2、3和0.5 g/L的Pb2+、Zn2+和Cd2+;在含pb2+、Cd2+培养基中生长其菌丝可以富集超过其干重25%以上的pb2+和5%以上的Cd2+;显示此菌株属于极端耐性并具有超积景作用的真菌.此真菌在植物根系的定殖或许可以通过菌丝体对金属离子的国持作用缓解植物根围土壤微环境中超量金属离子对植物的毒害作用.

  15. RNAi-directed downregulation of betaine aldehyde dehydrogenase 1 (OsBADH1) results in decreased stress tolerance and increased oxidative markers without affecting glycine betaine biosynthesis in rice (Oryza sativa). (United States)

    Tang, Wei; Sun, Jiaqi; Liu, Jia; Liu, Fangfang; Yan, Jun; Gou, Xiaojun; Lu, Bao-Rong; Liu, Yongsheng


    As an important osmoprotectant, glycine betaine (GB) plays an essential role in resistance to abiotic stress in a variety of organisms, including rice (Oryza sativa L.). However, GB content is too low to be detectable in rice, although rice genome possesses several orthologs coding for betaine aldehyde dehydrogenase (BADH) involved in plant GB biosynthesis. Rice BADH1 (OsBADH1) has been shown to be targeted to peroxisome and its overexpression resulted in increased GB biosynthesis and tolerance to abiotic stress. In this study, we demonstrated a pivotal role of OsBADH1 in stress tolerance without altering GB biosynthesis capacity, using the RNA interference (RNAi) technique. OsBADH1 was ubiquitously expressed in different organs, including roots, stems, leaves and flowers. Transgenic rice lines downregulating OsBADH1 exhibited remarkably reduced tolerance to NaCl, drought and cold stresses. The decrease of stress tolerance occurring in the OsBADH1-RNAi repression lines was associated with an elevated level of malondialdehyde content and hydrogen peroxidation. No GB accumulation was detected in transgene-positive and transgene-negative lines derived from heterozygous transgenic T0 plants. Moreover, transgenic OsBADH1-RNAi repression lines showed significantly reduced seed set and yield. In conclusion, the downregulation of OsBADH1, even though not causing any change of GB content, was accounted for the reduction of ability to dehydrogenate the accumulating metabolism-derived aldehydes and subsequently resulted in decreased stress tolerance and crop productivity. These results suggest that OsBADH1 possesses an enzyme activity to catalyze other aldehydes in addition to betaine aldehyde (the precursor of GB) and thus alleviate their toxic effects under abiotic stresses.

  16. Extensive variation in cadmium tolerance and accumulation among populations of Chamaecrista fasciculata.

    Directory of Open Access Journals (Sweden)

    Tessa M Henson

    Full Text Available Plant populations may vary substantially in their tolerance for and accumulation of heavy metals, and assessment of this variability is important when selecting species to use in restoration or phytoremediation projects. We examined the population variation in cadmium tolerance and accumulation in a leguminous pioneer species native to the eastern United States, the partridge pea (Chamaecrista fasciculata. We assayed growth, reproduction and patterns of cadmium accumulation in six populations of C. fasciculata grown on a range of cadmium-contaminated soils. In general, C. fasciculata exhibited tolerance in low to moderate soil cadmium concentrations. Both tolerance and accumulation patterns varied across populations. C. fasciculata exhibited many characteristics of a hyperaccumulator species, with high cadmium uptake in shoots and roots. However, cadmium was excluded from extrafloral nectar. As a legume with tolerance for moderate cadmium contamination, C. fasciculata has potential for phytoremediation. However, our findings also indicate the importance of considering the effects of genetic variation on plant performance when screening plant populations for utilization in remediation and restoration activities. Also, there is potential for cadmium contamination to affect other species through contamination of leaves, fruits, flowers, pollen and root nodules.

  17. Copper tolerance of Trichoderma species

    Directory of Open Access Journals (Sweden)

    Jovičić-Petrović Jelena


    Full Text Available Some Trichoderma strains can persist in ecosystems with high concentrations of heavy metals. The aim of this research was to examine the variability of Trichoderma strains isolated from different ecosystems, based on their morphological properties and restriction analysis of ITS fragments. The fungal growth was tested on potato dextrose agar, amended with Cu(II concentrations ranging from 0.25 to 10 mmol/l, in order to identify copper-resistant strains. The results indicate that some isolated strains of Trichoderma sp. show tolerance to higher copper concentrations. Further research to examine the ability of copper bioaccumulation by tolerant Trichoderma strains is needed. [Projekat Ministarstva nauke Republike Srbije, br. TR 31080 i br. III 43010

  18. Metal uptake of tomato and alfalfa plants as affected by water source, salinity, and Cd and Zn levels under greenhouse conditions. (United States)

    Gharaibeh, Mamoun A; Marschner, Bernd; Heinze, Stefanie


    Irrigation with wastewater is a promising option to improve crop yields and to reduce pressure on freshwater sources. However, heavy metal concentrations in wastewater may cause health concerns. A greenhouse pot experiment was conducted in order to determine cadmium (Cd) and zinc (Zn) concentrations in sandy soil and plant tissues of tomato (Lycopersicon esculentum L.) and alfalfa (Medicago sativa L.). A 2 × 2 × 4 × 2 factorial treatment arrangement was utilized. Two water sources, fresh (FW) or treated wastewater (TWW), at two salinity levels (1 and 3 dS m(-1)) containing different levels of Cd and Zn were used. Samples were collected after a 90-day growth period. It was observed that the growth of both plants was depressed at the highest metal level (L3). Metal accumulation in plant parts increased with the increase of metal concentration and salinity in irrigation water. At low salinity, water source was the main factor which controlled metal accumulation, whereas, at high salinity, chloride appeared to be the principal factor controlling metal uptake regardless of water source. Metal translocation from roots to shoots increased in TWW-irrigated plants, even in the controls. Tomatoes accumulated Cd up to and above critical levels safe for human consumption, even though Cd concentration in irrigation water did not exceed the current recommended values. Therefore, food production in sandy soils may well pose a health hazard when irrigated with TWW containing heavy metals. Complexation with dissolved organic compounds (DOC) in TWW may be to be the principal factor responsible for increased metal uptake and transfer at low salinity, thereby increasing the risk of heavy metal contamination of food and forage crops.

  19. Bioavailability of heavy metals, germanium and rare earth elements at Davidschacht dump-field in mine affected area of Freiberg (Saxony) (United States)

    Midula, Pavol; Wiche, Oliver


    Bioavailability research presents an essential tool, in modern phytoremediation and phytomining technologies, allowing the estimation of plant available fractions of elements in soils. However, up to date, sufficient interdisciplinary knowledge on the biogeochemically impacted behavior of specific target elements, in particular Ge and REEs in mining affected soils and their uptake into strategically used plants is lacking. This presented work is focused on a correlation study between the concentrations of selected heavy metals, Ge and REEs in soils formed on the top of the dump-field of Davidschacht and the corresponding their concentrations in 12 vascular plant species. The mine-dump of Davidschacht, situated in the Freiberg (Saxony, Germany) municipality area was chosen as the study area, which has been considered to be a high contaminated enclave, due to the mining history of the region. In total 12 sampling sites with differing composition of plant species were selected. At each sampling site soil samples from a soil depth of 0 - 10 cm and samples of plant material (shoots) were taken. The soil samples were analysed for total concentration of elements, pH (H2O) and consequently analysed by 4-step sequential extraction (SE) to determine fractions of elements that are mobile (fraction 1), acid soluble (pH 5) (fraction 2), bound to organic and oxidizable matter (fraction 3) and bound to amorphic oxides (fraction 4). The plant material was decomposed by hydrofluoric acid in order to extract the elements. Concentrations of elements in soil extracts and digestion solutions were analysed by ICP-MS. For all species bioconcentration factor (BCF) was calculated of the total concentration of elements in order to investigate the bioaccumulation potential. Arsenic (As), cadmium (Cd) and lead (Pb) were chosen as the representative heavy metals. Within the REEs neodymium (Nd) and cerium (Ce) were selected as representatives for all REEs, since Nd and Ce correlated significant

  20. Regional probabilistic risk assessment of heavy metals in different environmental media and land uses: An urbanization-affected drinking water supply area (United States)

    Peng, Chi; Cai, Yimin; Wang, Tieyu; Xiao, Rongbo; Chen, Weiping


    In this study, we proposed a Regional Probabilistic Risk Assessment (RPRA) to estimate the health risks of exposing residents to heavy metals in different environmental media and land uses. The mean and ranges of heavy metal concentrations were measured in water, sediments, soil profiles and surface soils under four land uses along the Shunde Waterway, a drinking water supply area in China. Hazard quotients (HQs) were estimated for various exposure routes and heavy metal species. Riverbank vegetable plots and private vegetable plots had 95th percentiles of total HQs greater than 3 and 1, respectively, indicating high risks of cultivation on the flooded riverbank. Vegetable uptake and leaching to groundwater were the two transfer routes of soil metals causing high health risks. Exposure risks during outdoor recreation, farming and swimming along the Shunde Waterway are theoretically safe. Arsenic and cadmium were identified as the priority pollutants that contribute the most risk among the heavy metals. Sensitivity analysis showed that the exposure route, variations in exposure parameters, mobility of heavy metals in soil, and metal concentrations all influenced the risk estimates.

  1. Lactose tolerance tests (United States)

    Hydrogen breath test for lactose tolerance ... Two common methods include: Lactose tolerance blood test Hydrogen breath test The hydrogen breath test is the preferred method. It measures the amount of hydrogen ...

  2. The effect of metal pollution on the population genetic structure of brown trout (Salmo trutta L.) residing in the River Hayle, Cornwall, UK

    Energy Technology Data Exchange (ETDEWEB)

    Durrant, Christopher J. [King' s College London, Metals Metabolism Group, Division of Diabetes and Nutritional Sciences, Franklin Wilkins Building, 150 Stamford Street, London SE1 9NH (United Kingdom); Stevens, Jamie R. [University of Exeter, Biosciences, College of Life and Environmental Sciences, Geoffrey Pope Building, Stocker Road, Exeter EX4 4QD (United Kingdom); Hogstrand, Christer [King' s College London, Metals Metabolism Group, Division of Diabetes and Nutritional Sciences, Franklin Wilkins Building, 150 Stamford Street, London SE1 9NH (United Kingdom); Bury, Nicolas R., E-mail: [King' s College London, Metals Metabolism Group, Division of Diabetes and Nutritional Sciences, Franklin Wilkins Building, 150 Stamford Street, London SE1 9NH (United Kingdom)


    The River Hayle in south-west England is impacted with metals and can be divided into three regions depending on the copper and zinc concentrations: a low-metal upper section; a highly-contaminated middle section and a moderately contaminated lower section. Hayle river water is toxic to metal-naive brown trout, but brown trout are found in the upper and lower regions. The study aimed to evaluate the population genetic structure of River Hayle brown trout and to determine if the highly-contaminated section acts as a chemical barrier to migration. Population genetic analysis indicated that metals were not a barrier to gene flow within the river, but there was a high level of differentiation observed between fish sampled at two sites in the upper region, despite being separated by only 1 km. The metal tolerance trait exhibited by this brown trout population may represent an important component of the species genetic diversity in this region. - Highlights: > River Hayle, Cornwall, UK, water is toxic to metal-naive brown trout. > Some brown trout populations resident in the River Hayle are tolerant of elevated metals (e.g. copper and zinc). > Elevated metals do not affect the gene flow between sites on the river. > The population genetic structure of the brown trout in the River Hayle appears unaffected by elevated metals. - Aquatic metal pollution does not affect the gene flow between brown trout resident below and above a metal mining waste discharge point in the River Hayle, Cornwall, UK.

  3. Process capability indices and risk analysis for circular position tolerance zones (United States)

    Krystek, Michael P.


    Position tolerance is used in geometric dimensioning and tolerancing to specify tolerances for the location of holes. The tolerance zone for holes is usually cylindrical and the allowable position tolerance is the diameter of the tolerance zone. If holes are used in flat parts, as e. g. sheet metals, it is sufficient to use circular tolerance zones. In order to assure the quality and to reduce the risk to accept products which do not fulfil the design requirements, statistical process control is used in industry. In this paper it is shown, how process capability indices and the associated risk can be calculated for circular position tolerance zones.


    This report summarizes the results of Mine Waste Technology Program (MWTP) Activity III, Project 30. The objective of Project 30 was to select populations (i.e., ecotypes) from native, indigenous plant species that demonstrate superior growth characteristics and sustainability on...

  5. Drought Tolerance in Modern and Wild Wheat


    Hikmet Budak; Melda Kantar; Kuaybe Yucebilgili Kurtoglu


    The genus Triticum includes bread (Triticum aestivum) and durum wheat (Triticum durum) and constitutes a major source for human food consumption. Drought is currently the leading threat on world's food supply, limiting crop yield, and is complicated since drought tolerance is a quantitative trait with a complex phenotype affected by the plant's developmental stage. Drought tolerance is crucial to stabilize and increase food production since domestication has limited the genetic diversity of c...

  6. Drought tolerance in modern and wild wheat. (United States)

    Budak, Hikmet; Kantar, Melda; Kurtoglu, Kuaybe Yucebilgili


    The genus Triticum includes bread (Triticum aestivum) and durum wheat (Triticum durum) and constitutes a major source for human food consumption. Drought is currently the leading threat on world's food supply, limiting crop yield, and is complicated since drought tolerance is a quantitative trait with a complex phenotype affected by the plant's developmental stage. Drought tolerance is crucial to stabilize and increase food production since domestication has limited the genetic diversity of crops including wild wheat, leading to cultivated species, adapted to artificial environments, and lost tolerance to drought stress. Improvement for drought tolerance can be achieved by the introduction of drought-grelated genes and QTLs to modern wheat cultivars. Therefore, identification of candidate molecules or loci involved in drought tolerance is necessary, which is undertaken by "omics" studies and QTL mapping. In this sense, wild counterparts of modern varieties, specifically wild emmer wheat (T. dicoccoides), which are highly tolerant to drought, hold a great potential. Prior to their introgression to modern wheat cultivars, drought related candidate genes are first characterized at the molecular level, and their function is confirmed via transgenic studies. After integration of the tolerance loci, specific environment targeted field trials are performed coupled with extensive analysis of morphological and physiological characteristics of developed cultivars, to assess their performance under drought conditions and their possible contributions to yield in certain regions. This paper focuses on recent advances on drought related gene/QTL identification, studies on drought related molecular pathways, and current efforts on improvement of wheat cultivars for drought tolerance.

  7. Recognition and Toleration

    DEFF Research Database (Denmark)

    Lægaard, Sune


    Recognition and toleration are ways of relating to the diversity characteristic of multicultural societies. The article concerns the possible meanings of toleration and recognition, and the conflict that is often claimed to exist between these two approaches to diversity. Different forms...... or interpretations of recognition and toleration are considered, confusing and problematic uses of the terms are noted, and the compatibility of toleration and recognition is discussed. The article argues that there is a range of legitimate and importantly different conceptions of both toleration and recognition...

  8. Mechanical tolerance stackup and analysis

    CERN Document Server

    Fischer, Bryan R


    BackgroundDimensioning and TolerancingTolerance Format and Decimal PlacesConverting Plus/Minus Dimensions and Tolerances into Equal Bilaterally Toleranced DimensionsVariation and Sources of VariationTolerance AnalysisWorst-case Tolerance StackupsStatistical Tolerance StackupsGeometric Dimensioning and Tolerancing (GD&T)Converting Plus/Minus Tolerancing to Positional Tolerancing and Projected Tolerance ZonesDiametral and Radial Tolerance StackupsSpecifying Material Condition Modifiers and Their Effect on Tolerance Stackups The Tolerance Stackup SketchThe Tolerance Stackup Report FormTolerance S

  9. Assessment of metal contamination in a small mining- and smelting-affected watershed: high resolution monitoring coupled with spatial analysis by GIS. (United States)

    Coynel, Alexandra; Blanc, Gérard; Marache, Antoine; Schäfer, Jörg; Dabrin, Aymeric; Maneux, Eric; Bossy, Cécile; Masson, Matthieu; Lavaux, Gilbert


    The Riou Mort River watershed (SW France), representative of a heavily polluted, small, heterogeneous watershed, represents a major source for the polymetallic pollution of the Lot-Garonne-Gironde fluvial-estuarine system due to former mining and ore-treatment activities. In order to assess spatial distribution of the metal/metalloid contamination in the watershed, a high resolution hydrological and geochemical monitoring were performed during one year at four permanent observation stations. Additionally, thirty-five stream sediment samples were collected at representative key sites and analyzed for metal/metalloid (Cd, Zn, Cu, Pb, As, Sb, Mo, V, Cr, Co, Ni, Th, U and Hg) concentrations. The particulate concentrations in water and stream sediments show high spatial differences for most of the studied elements suggesting strong anthropogenic and/or lithogenic influences; for stream sediments, the sequence of the highest variability, ranging from 100% to 300%, is the following: Mo metalloid maps generated by GIS tool were used to establish relationships between elements, to identify metal/metalloid sources and localize geochemical anomalies attributed to local geochemical background, urban and industrial activities. Finally, this study presents an approach to assess anthropogenic trace metal inputs within this watershed by combining lithology-dependent geochemical background values, metal/metalloid concentrations in stream sediments and mass balances of element fluxes at four key sites. The strongest anthropogenic contributions to particulate element fluxes are 90-95% for Cd, Zn and Hg in downstream sub-catchments. The localisation of anthropogenic metal/metalloid sources in restricted areas offers a great opportunity to further significantly reduce metal emissions and restore the Lot-Garonne-Gironde fluvial-estuarine ecosystem.

  10. Compromise and Toleration

    DEFF Research Database (Denmark)

    Rostbøll, Christian F.

    Political compromise is akin to toleration, since both consist of an "agreement to disagree." Compromise and toleration also share a predicament of being regarded as ambiguous virtues that require of us to accept something we actually regard as wrong. However, we misunderstand the nature......, justification, and limits of compromise if we see it merely as a matter of toleration. While toleration is mainly a matter of accepting citizens' equal right to co-existence as subjects to law, political compromise includes the parties in making law – it makes them co-authors of law. Toleration entails...... respecting the plurality of conceptions of the good in society, whereas political compromise embodies the disagreements in coercive laws. This difference between toleration and compromise has two important consequences. First, political compromise is justified in a different manner than is toleration...

  11. Climate change driven plant-metal-microbe interactions. (United States)

    Rajkumar, Mani; Prasad, Majeti Narasimha Vara; Swaminathan, Sandhya; Freitas, Helena


    Various biotic and abiotic stress factors affect the growth and productivity of crop plants. Particularly, the climatic and/or heavy metal stress influence various processes including growth, physiology, biochemistry, and yield of crops. Climatic changes particularly the elevated atmospheric CO₂ enhance the biomass production and metal accumulation in plants and help plants to support greater microbial populations and/or protect the microorganisms against the impacts of heavy metals. Besides, the indirect effects of climatic change (e.g., changes in the function and structure of plant roots and diversity and activity of rhizosphere microbes) would lead to altered metal bioavailability in soils and concomitantly affect plant growth. However, the effects of warming, drought or combined climatic stress on plant growth and metal accumulation vary substantially across physico-chemico-biological properties of the environment (e.g., soil pH, heavy metal type and its bio-available concentrations, microbial diversity, and interactive effects of climatic factors) and plant used. Overall, direct and/or indirect effects of climate change on heavy metal mobility in soils may further hinder the ability of plants to adapt and make them more susceptible to stress. Here, we review and discuss how the climatic parameters including atmospheric CO₂, temperature and drought influence the plant-metal interaction in polluted soils. Other aspects including the effects of climate change and heavy metals on plant-microbe interaction, heavy metal phytoremediation and safety of food and feed are also discussed. This review shows that predicting how plant-metal interaction responds to altering climatic change is critical to select suitable crop plants that would be able to produce more yields and tolerate multi-stress conditions without accumulating toxic heavy metals for future food security.

  12. An approach to quantify sources, seasonal change, and biogeochemical processes affecting metal loading in streams: Facilitating decisions for remediation of mine drainage (United States)

    Kimball, B.A.; Runkel, R.L.; Walton-Day, K.


    Historical mining has left complex problems in catchments throughout the world. Land managers are faced with making cost-effective plans to remediate mine influences. Remediation plans are facilitated by spatial mass-loading profiles that indicate the locations of metal mass-loading, seasonal changes, and the extent of biogeochemical processes. Field-scale experiments during both low- and high-flow conditions and time-series data over diel cycles illustrate how this can be accomplished. A low-flow experiment provided spatially detailed loading profiles to indicate where loading occurred. For example, SO42 - was principally derived from sources upstream from the study reach, but three principal locations also were important for SO42 - loading within the reach. During high-flow conditions, Lagrangian sampling provided data to interpret seasonal changes and indicated locations where snowmelt runoff flushed metals to the stream. Comparison of metal concentrations between the low- and high-flow experiments indicated substantial increases in metal loading at high flow, but little change in metal concentrations, showing that toxicity at the most downstream sampling site was not substantially greater during snowmelt runoff. During high-flow conditions, a detailed temporal sampling at fixed sites indicated that Zn concentration more than doubled during the diel cycle. Monitoring programs must account for diel variation to provide meaningful results. Mass-loading studies during different flow conditions and detailed time-series over diel cycles provide useful scientific support for stream management decisions.

  13. [Metal poisoning]. (United States)

    Ferrer, A


    Metals are amongst the oldest toxic substances known to man. In today's industrialized world the sources of exposure to metals are ubiquitous both in the field of work and from polluted water, foodstuffs and the environment. Their toxicity is characterized by the metallic element in question, but this is modified by the type of compound, whether organic or inorganic, and its characteristics of hydrosolubility and liposolubility, which determines its toxicokinetics and thus the possibilities of it reaching its targets. The biomolecules most affected by metals are the proteins with enzymatic activity, which is why their pathology is multisystemic. The principal systems affected are the gastrointestinal, central and peripheral neurological, haematic and renal. Some metallic compounds are carcinogenic. Metals's treatment is conditioned by their chemical reactivity. They can be deactivated and eliminated by the administering of chelating agents that produce complex molecules, which are non-toxic and can be excreted. The principal chelating agents are: BAL (British Anti-Lewisite or dimercaprol) DMPS (2,3-Dimercapto-1-propanesulfonic Acid) and DMSA (meso-2,3-Dimercaptosuccinic or Succimer), EDTA, Penicilamine (b,b-dimethylcysteine) and Deferoxamine. Toxicokinetic characteristics, mechanism of action, clinical picture and treatment of some of the most relevant metals and metalloids: lead, mercury and arsenic, are considered.

  14. Antimicrobial Tolerance in Listeria monocytogenes

    DEFF Research Database (Denmark)

    Curtis, Thomas Darwin

    D project, Listeria monocytogenes was observed to form these antibiotic tolerant persister cells. L. monocytogenes is a Gram-positive, foodborne pathogen that causes listeriosis, a rare, but often lethal disease, even with antibiotic treatment. It typically affects pregnant women, neonates, the elderly...... of between 4.6 and 9.6, and survive NaCl concentrations as high as 40%. Given its resilience, as well as the industrial and clinical implications, we felt that L. monocytogenes would make a good model to study antibiotic tolerance and sought to further investigate persister cells and their underlying...... mechanisms in this organism. The body of work over the course of this PhD study has been organized into three manuscripts, which are summarized below. The first manuscript sought to link the Small Colony Variant (SCV) to persister cells in L. monocytogenes. SCV cells of bacteria are a slow growing phenotype...

  15. How Do Structure and Charge Affect Metal-Complex Binding to DNA? An Upper-Division Integrated Laboratory Project Using Cyclic Voltammetry (United States)

    Kulczynska, Agnieszka; Johnson, Reed; Frost, Tony; Margerum, Lawrence D.


    An advanced undergraduate laboratory project is described that integrates inorganic, analytical, physical, and biochemical techniques to reveal differences in binding between cationic metal complexes and anionic DNA (herring testes). Students were guided to formulate testable hypotheses based on the title question and a list of different metal…

  16. Remember Tolerance Differently

    DEFF Research Database (Denmark)

    Tønder, Lars


    This essay questions the linear conception of history which often accompanies the way contemporary democratic theory tends to disavow tolerance's discontinuities and remainders. In the spirit of Foucault's genealogy of descent, the idea is to develop a new sense of tolerance's history......, not by invoking a critique external to contemporary democratic theory, but by witnessing the history of tolerance paraliptically, with an eye to what it obscures and yet presupposes....

  17. Role of GSH homeostasis under Zn toxicity in plants with different Zn tolerance. (United States)

    Barrameda-Medina, Yurena; Montesinos-Pereira, David; Romero, Luis; Blasco, Begoña; Ruiz, Juan M


    Tripepthide glutathione (GSH) is a pivotal molecule in tolerance to heavy metals, including Zinc (Zn). The aim of our work is to examine the role of GSH metabolism in two different horticultural plants under Zn toxicity in order to select and/or generate plants tolerant to Zn toxicity. We show a comparative analysis of the toxic effect of 0.5mM Zn between Lactuca sativa cv. Phillipus and Brassica oleracea cv. Bronco. In L. sativa the accumulation of Zn resulted in an increase in reactive oxygen species (ROS), while enzymes of GSH metabolism and the activities of the antioxidant enzymes were negatively affected. On the contrary, B. oleracea showed the existence of a detoxification mechanism of these ROS. Moreover, while in L. sativa increased the oxidized GSH (GSSG) and phytochelatins (PCs) concentration with the reduction of leaves biomass, in B. oleracea the higher concentration of reduced GSH and its use in the detoxification of ROS seems to be a major mechanism to provide tolerance to Zn toxicity without reducing leaf biomass. Our results suggested that under Zn toxicity, B. oleracea is more efficient and tolerant than L. sativa through the detoxification of lipid peroxidation products due to the reduced GSH.

  18. Unraveling the role of fungal symbionts in plant abiotic stress tolerance. (United States)

    Singh, Lamabam Peter; Gill, Sarvajeet Singh; Tuteja, Narendra


    Fungal symbionts have been found associated with every plant studied in natural ecosystem, where they colonize and reside entirely in the internal tissues of their host plant or partially. Fungal endophytes can express/form a range of different lifestyle/relationships with different host including symbiotic, mutualistic, commensalistic and parasitic in response to host genotype and environmental factors. In mutualistic association fungal endophyte can enhance growth, increase reproductive success and confer biotic and abiotic stress tolerance to its host plant. Since abiotic stress such as, drought, high soil salinity, heat, cold, oxidative stress, heavy metal toxicity is the common adverse environmental conditions that affect and limit crop productivity worldwide. It may be a promising alternative strategy to exploit fungal endophytes to overcome the limitations to crop production brought by abiotic stress. There is increasing interest in developing the potential biotechnological applications of fungal endophytes for improving plant stress tolerance and sustainable production of food crops. Here we have described the fungal symbioses, fungal symbionts and their role in abiotic stress tolerance. A putative mechanism of stress tolerance by symbionts has also been covered.


    Institute of Scientific and Technical Information of China (English)



    As an emigrant country, the essential characteristic of America culture is its tolerance. It contributes to the formation the diversity of American culture. By tracing back to American history, this essay shows what caused American cultural tolerance. Through describing briefly the manifestation of American cultural tolerance from certain aspects and analyzing the major factors, it will give us a clue about the reason why America can be always prosperous. At last, the paper shows the limitation as well as advantages about the tolerance from the point of current status.

  20. Lead and zinc accumulation and tolerance in populations of six wetland plants

    Energy Technology Data Exchange (ETDEWEB)

    Deng, H. [Biology Department and Croucher Institute for Environmental Sciences, Hong Kong Baptist University, Kowloon, Hong Kong (China); Department of Environmental Science and Technology, East China Normal University, Shanghai (China); Ye, Z.H. [Biology Department and Croucher Institute for Environmental Sciences, Hong Kong Baptist University, Kowloon, Hong Kong (China); School of Life Sciences, Zhongshan (Sun Yat-sen) University, Guangzhou 510275 (China); Wong, M.H. [Biology Department and Croucher Institute for Environmental Sciences, Hong Kong Baptist University, Kowloon, Hong Kong (China)]. E-mail:


    Wetland plants such as Typha latifolia and Phragmites australis have been indicated to show a lack of evolution of metal tolerance in metal-contaminated populations. The aim of the present study is to verify whether other common wetland plants such as Alternanthera philoxeroides and Beckmannia syzigachne, also possess the same characteristics. Lead and zinc tolerances in populations of six species collected from contaminated and clean sites were examined by hydroponics. In general, the contaminated populations did not show higher metal tolerance and accumulation than the controls. Similar growth responses and tolerance indices in the same metal treatment solution between contaminated and control populations suggest that metal tolerance in wetland plants are generally not further evolved by contaminated environment. The reasons may be related to the special root anatomy in wetland plants, the alleviated metal toxicity by the reduced rooting conditions and the relatively high innate metal tolerance in some species. - Populations from metal contaminated sites did not have significantly higher metal tolerance indices.

  1. Spinoza and the Theory of Active Tolerance

    DEFF Research Database (Denmark)

    Tønder, Lars


    This paper considers the politics of tolerance through the lens of Spinoza’s philosophy of immanence. The contention is that Spinoza’s philosophy of immanence provides us with a better conceptualization of the relationship between tolerance and power, and that it in so doing reinvigorates a theory...... of active tolerance that, for the most part, has been lost in contemporary democratic theory. Spinoza’s philosophy of immanence does so because it animates a sensorial orientation to politics, one that heightens our attention to the affective components of political life, enabling us to better theorize how...... all modes of existence, including the so-called passive ones, harbor a degree of power that can be mobilized for purposes that go beyond the “non-practice” highlighted by advocates and critics of tolerance in contemporary democratic theory. The paper develops this argument with ongoing reference...

  2. Metal-poor dwarf galaxies in the SIGRID galaxy sample. II. The electron temperature-abundance calibration and the parameters that affect it

    CERN Document Server

    Nicholls, David C; Sutherland, Ralph S; Jerjen, Helmut; Kewley, Lisa J; Basurah, Hassan


    In this paper, we use the Mappings photoionization code to explore the physical parameters that impact on the measurement of electron temperature and abundance in HII regions. In the previous paper we presented observations and measurements of physical properties from the spectra of seventeen HII regions in fourteen isolated dwarf irregular galaxies from the SIGRID sample. Here, we analyze these observations further, together with three additional published data sets. We explore the effects of optical thickness, electron density, ionization parameter, ionization source, and non-equilibrium effects on the relation between electron temperature and metallicity. We present a standard model that fits the observed data remarkably well at metallicities between 1/10 and 1 solar. We investigate the effects of optically thin HII regions, and show that they can have a considerable effect on the measured electron temperature, and that there is evidence that some of the observed objects are optically thin. We look at the ...

  3. Objective function of cost in optimal tolerance allocation

    Institute of Scientific and Technical Information of China (English)


    An objective function model is proposed for cost in optimizing and allocating tolerance with consideration of manufacturing conditions. With the fuzzy comprehensive evaluation method, a manufacturing difficulty coefficient is derived, which takes into account of several factors affecting the manufacturing cost, including the forming means of the blank, size, machining surface features, operator's skills and machinability of materials.The coefficient is then converted into a weight factor used in the inversed square model representing the relationship between the cost and tolerance, and, hence, an objective function for cost is established in optimizing and allocating tolerance. The higher is the manufacturing difficulty coefficient, the higher is the relative manufacturing cost and the higher is the weight factor of the tolerance allocation, which indicates the increase of the tolerance's effects on the total manufacturing cost and, therefore, a larger tolerance should be allocated. The computer-aided tolerance allocation utilizing this model makes it more convenient, accurate and practicable.

  4. A Survey of Heavy Metals content of Soil and plants As Affected by Long-Term Application of Sewage Water. A Case Study

    Directory of Open Access Journals (Sweden)

    Abd El Lateef E. M.


    Full Text Available As part of a four year study evaluating the practicability and value of sewage sludge use in Egypt, soil and plant surveys were carried out on a citrus plantation, irrigated with Cairo sewage since the 1920s, in order to evaluate the long-term accumulation of trace elements and heavy metals and their bioavailability. While total and DTPA soil concentrations correlated well, no relationship could be found between soil and plant tissue concentrations, despite elevated levels of heavy metals in the soil. Study of long-term contamination of soil with potentially toxic elements (PTEs has not demonstrated a potential risk to crop quality and yield or human health from the slow accumulation of PTEs in sludge-treated agricultural soil. PTE concentrations in plant tissues remained low and within normal ranges despite significant increases in soil content after long-term irrigation with sewage effluent. Concentrations of PTEs in plant tissues were not related to total or DTPA extractable metals in contaminated soil. DTPA may not be a sufficiently reliable indicator of actual phytoavailability of trace elements in sludge-treated soil, although it is accepted that DTPA is widely used in nutrient diagnosis assessment. These data provide assurance about the minimal risk to the environment from trace elements and PTEs in sludge-treated agricultural soil, but a more detailed dietary analysis of Cd intakes under Egyptian conditions is recommended, following the approaches adopted in the UK and US for setting Cd soil limits or loading rates for this element.

  5. Inequality, Tolerance, and Growth

    DEFF Research Database (Denmark)

    Bjørnskov, Christian

    This paper argues for the importance of individuals' tolerance of inequality for economic growth. By using the political ideology of governments as a measure of revealed tolerance of inequality, the paper shows that controlling for ideology improves the accuracy with which the effects of inequality...

  6. Toleration out of respect?

    DEFF Research Database (Denmark)

    Lægaard, Sune


    Under conditions of pluralism different cultures, interests or values can come into conflict, which raises the problem of how to secure peaceful co-existence. The idea of toleration historically emerged as an answer to this problem. Recently Rainer Forst has argued that toleration should not just...

  7. Loss Tolerant Optical Qubits

    CERN Document Server

    Ralph, T C; Gilchrist, A; Gilchrist, Alexei


    We present a linear optics quantum computation scheme that employs a new encoding approach that incrementally adds qubits and is tolerant to photon loss errors. The scheme employs a circuit model but uses techniques from cluster state computation and achieves comparable resource usage. To illustrate our techniques we describe a quantum memory which is fault tolerant to photon loss.

  8. Heavy metal contamination in a vulnerable mangrove swamp in South China. (United States)

    Wang, Yutao; Qiu, Qiu; Xin, Guorong; Yang, Zhongyi; Zheng, Jing; Ye, Zhihong; Li, Shaoshan


    Concentrations of six heavy metals (Cu, Ni, Zn, Cd, Cr, and Pb) in sediments and fine roots, thick roots, branches, and leaves of six mangrove plant species collected from the Futian mangrove forest, South China were measured. The results show that both the sediments and plants in Futian mangrove ecosystem are moderately contaminated by heavy metals, with the main contaminants being Zn and Cu. All investigated metals showed very similar distribution patterns in the sediments, implying that they had the same anthropogenic source(s). High accumulations of the heavy metals were observed in the root tissues, especially the fine roots, and much lower concentrations in the other organs. This indicates that the roots strongly immobilize the heavy metals and (hence) that mangrove plants possess mechanisms that limit the upward transport of heavy metals and exclude them from sensitive tissues. The growth performance of propagules and 6-month-old seedlings of Bruguiera gymnorhiza in the presence of contaminating Cu and Cd was also examined. The results show that this plant is not sufficiently sensitive to heavy metals after its propagule stage for its regeneration and growth to be significantly affected by heavy metal contamination in the Futian mangrove ecosystem. However, older mangrove seedlings appeared to be more metal-tolerant than the younger seedlings due to their more efficient exclusion mechanism. Thus, the effects of metal contamination on young seedlings should be assessed when evaluating the risks posed by heavy metals in an ecosystem.

  9. Toleration, Groups, and Multiculturalism

    DEFF Research Database (Denmark)

    Lægaard, Sune


    . The chapter relates the different possible meanings of groups toleration to widespread criticisms of multiculturalism for being excessively 'groupist' (e.g. to essentialise or reify groups), to promote group rights over individual rights, or to deny or ignore the internal heterogeneity of groups...... or the multiple identity affiliations of individuals. The chapter suggests that some of these standard criticisms of multiculturalism for being overly tolerant of minority groups, or being so in a way elevating groups over individuals, are less pressing on some understandings of the meaning of 'group......' as an object of policies of multicultural toleration than on others. So the chapter both contributes to the conceptual understanding of toleration and groups and to the normative debates about multiculturalism insofar as these turn on the toleration of groups....


    Directory of Open Access Journals (Sweden)

    Hamdia, M. A


    Full Text Available Several environmental factors adversely affect plant growth and development and final yield performance of a crop. Drought, salinity, nutrient imbalances (including mineral toxicities and deficiencies and extremes of temperature are among the major environmental constraints to crop productivity worldwide. Development of crop plants with stress tolerance, however, requires, among others, knowledge of the physiological mechanisms and genetic controls of the contributing traits at different plant developmental stages. In the past 2 decades, biotechnology research has provided considerable insights into the mechanism of biotic stress tolerance in plants at the molecular level. Furthermore, different abiotic stress factors may provoke osmotic stress, oxidative stress and protein denaturation in plants, which lead to similar cellular adaptive responses such as accumulation of compatible solutes, induction of stress proteins, and acceleration of reactive oxygen species scavenging systems. Recently, the authores try to improve plant tolerance to salinity injury through either chemical treatments (plant hormones, minerals, amino acids, quaternary ammonium compounds, polyamines and vitamins or biofertilizers treatments (Asymbiotic nitrogen-fixing bacteria, symbiotic nitrogen-fixing bacteria and mycorrhiza or enhanced a process used naturally by plants to minimise the movement of Na+ to the shoot, using genetic modification to amplify the process, helping plants to do what they already do - but to do it much better."

  11. Characterization of Uranium Tolerance and Biomineralization Potential of Caulobacter crescentus (United States)

    Park, D.


    Due to its high toxicity and mobility, U(VI) poses a major environmental threat to ecosystems. The ubiquitous aerobic bacterium Caulobacter cresecentus is an attractive candidate for U(VI) bioremediation because of its ability to survive in low-nutrient environments (5, 6), tolerate high U concentrations and mineralize U(VI) aerobically through the formation of uranyl phosphate (U-Pi) precipitates. Despite these attractive environmental properties, both a systems level understanding of the adaptive response pathways involved in U tolerance and the environmental conditions affecting the biomineralization process and stability of biogenic U-Pi minerals remain limited. By measuring changes in both mRNA and protein expression during exposure to high U levels, we have identified the core stress response pathways involved in U tolerance. Pathways associated with heat shock, lipospolysaccharide biosynthesis and transport, outer membrane lipoprotein transport and outermembrane assembly were highly induced at both the RNA and protein levels. Correspondingly, removal of integral components of proteolysis pathways including clpA, clpS and degP significantly reduced U tolerance under biomineralization conditions. Surprisingly, in contrast to many other heavy metals, U did not cause oxidative stress or DNA damage. Together, these analyses indicate that U predominately targets the outermembrane and causes mis-folding of both cytoplasmic and extracytoplasmic proteins. Efforts are currently underway to characterize the morphological and structural properties of biogenic U-Pi minerals and the environmental factors that influence their production and stability. Preliminary AFM studies suggest that U-Pi minerals formed under biomineralization conditions appear morphologically distinct from those formed abiotically between U(VI) and inorganic phosphate. Additionally, we observed that biomineralization tolerates a wide pH range (pH 6-9). Our long-range goal is the development of a

  12. tolerance: An R Package for Estimating Tolerance Intervals


    Derek S. Young


    The tolerance package for R provides a set of functions for estimating and plotting tolerance limits. This package provides a wide-range of functions for estimating discrete and continuous tolerance intervals as well as for estimating regression tolerance intervals. An additional tool of the tolerance package is the plotting capability for the univariate and regression settings as well as for the multivariate normal setting. The tolerance package's capabilities are illustrated using simulated...

  13. SU-E-J-58: Dosimetric Verification of Metal Artifact Effects: Comparison of Dose Distributions Affected by Patient Teeth and Implants

    Energy Technology Data Exchange (ETDEWEB)

    Lee, M; Kang, S; Lee, S; Suh, T [Department of Biomedical Engineering, College of Medicine, The Catholic University of Korea, Seoul (Korea, Republic of); Research Institute of Biomedical Engineering, College of Medicine, The Catholic University of Korea (Korea, Republic of); Lee, J [Konkuk University Medical Center, Seoul (Korea, Republic of); Research Institute of Health Science, Korea University, Seoul (Korea, Republic of); Park, J [Research Institute of Biomedical Engineering, College of Medicine, The Catholic University of Korea (Korea, Republic of); Dept. of Pediatrics and Molecular Imaging Program at Stanford, Stanford University, Stanford (United States); Park, H [Department of Radiation Oncology, Ajou University School of Medicine, Suwon (Korea, Republic of); Lee, B [Research Institute of Health Science, Korea University, Seoul (Korea, Republic of); Daejeon Sun Hospital, Daejeon (Korea, Republic of)


    Purpose: Implant-supported dentures seem particularly appropriate for the predicament of becoming edentulous and cancer patients are no exceptions. As the number of people having dental implants increased in different ages, critical dosimetric verification of metal artifact effects are required for the more accurate head and neck radiation therapy. The purpose of this study is to verify the theoretical analysis of the metal(streak and dark) artifact, and to evaluate dosimetric effect which cause by dental implants in CT images of patients with the patient teeth and implants inserted humanoid phantom. Methods: The phantom comprises cylinder which is shaped to simulate the anatomical structures of a human head and neck. Through applying various clinical cases, made phantom which is closely allied to human. Developed phantom can verify two classes: (i)closed mouth (ii)opened mouth. RapidArc plans of 4 cases were created in the Eclipse planning system. Total dose of 2000 cGy in 10 fractions is prescribed to the whole planning target volume (PTV) using 6MV photon beams. Acuros XB (AXB) advanced dose calculation algorithm, Analytical Anisotropic Algorithm (AAA) and progressive resolution optimizer were used in dose optimization and calculation. Results: In closed and opened mouth phantom, because dark artifacts formed extensively around the metal implants, dose variation was relatively higher than that of streak artifacts. As the PTV was delineated on the dark regions or large streak artifact regions, maximum 7.8% dose error and average 3.2% difference was observed. The averaged minimum dose to the PTV predicted by AAA was about 5.6% higher and OARs doses are also 5.2% higher compared to AXB. Conclusion: The results of this study showed that AXB dose calculation involving high-density materials is more accurate than AAA calculation, and AXB was superior to AAA in dose predictions beyond dark artifact/air cavity portion when compared against the measurements.

  14. Soil heavy metals

    Energy Technology Data Exchange (ETDEWEB)

    Sherameti, Irena [Jena Univ. (Germany). Inst. fuer Allgemeine Botanik und Pflanzenphysiologie; Varma, Ajit (eds.) [Amity Univ., Uttar Pradesh (India). Amity Inst. of Microbial Technology; Amity Science, Technology and Innovation Foundation, Noida, UP (India)


    Human activities have dramatically changed the composition and organisation of soils. Industrial and urban wastes, agricultural application and also mining activities resulted in an increased concentration of heavy metals in soils. How plants and soil microorganisms cope with this situation and the sophisticated techniques developed for survival in contaminated soils is discussed in this volume. The topics presented include: the general role of heavy metals in biological soil systems; the relation of inorganic and organic pollutions; heavy metal, salt tolerance and combined effects with salinity; effects on abuscular mycorrhizal and on saprophytic soil fungi; heavy metal resistance by streptomycetes; trace element determination of environmental samples; the use of microbiological communities as indicators; phytostabilization of lead polluted sites by native plants; effects of soil earthworms on removal of heavy metals and the remediation of heavy metal contaminated tropical land. (orig.)

  15. 77 FR 43524 - Acetamiprid; Pesticide Tolerances (United States)


    ... rather to provide a guide for readers regarding entities likely to be affected by this action. Other...), 500 College Road East, Suite 201 W, Princeton, NJ 08540. The petition requested that 40 CFR 180.578 be... field trials are required to support this use. ] V. Conclusion Therefore, tolerances are established...

  16. 75 FR 40745 - Cyazofamid; Pesticide Tolerances (United States)


    ... rather to provide a guide for readers regarding entities likely to be affected by this action. Other...., Princeton, NJ 08540. The petition requested that 40 CFR 180.601 be amended by establishing tolerances for... fields. For the use of cyazofamid on professionally managed turf areas, short-term and...

  17. 77 FR 38199 - Propiconazole; Pesticide Tolerances (United States)


    ... rather to provide a guide for readers regarding entities likely to be affected by this action. Other..., Princeton, NJ 08540. The petition requested that 40 CFR 180.434 be amended by establishing tolerances for.... Additional refinements incorporating average field trial and/or percent crop treated information would...

  18. 75 FR 14086 - Clopyralid; Pesticide Tolerances (United States)


    ... rather to provide a guide for readers regarding entities likely to be affected by this action. Other...) by IR-4, 500 College Road East, Suite 201W, Princeton, NJ 08540. The petition requested that 40 CFR... the residue field trial data supporting the revised tolerance resulted in residues that were...

  19. 76 FR 4542 - Mefenoxam; Pesticide Tolerances (United States)


    ... rather to provide a guide for readers regarding entities likely to be affected by this action. Other...., Princeton, NJ 08540. The petition requested that 40 CFR 180.546 be amended by establishing tolerances for... athletic fields. EPA assessed residential exposure using the following assumptions: Exposure to adults...

  20. Population differences in susceptibility to stress in Littorina saxatilis from metal contaminated and uncontaminated sites in the Isle of Man

    Institute of Scientific and Technical Information of China (English)


    The population of the intertidal gastropod Littorina saxatilis from Laxey estuary in the Isle of Man is exposed to mine-related contamination of Zn (and is tolerant to Zn and Pb) compared to those of Castletown, Derbyhaven, Peel and Ramsey.Tolerances to salinity and desiccation stress were assayed to test how metal tolerance could affect tolerance to general stress. The winkles were experimentally exposed to salinities of 0, 17 and 60 practical salinity units (psu) with 34 psu as control. Desiccation stress was determined by aerial exposure of the winkles at 24℃. No control mortalities were recorded and mortalities in 17 psu were less than 50% for all populations over a 24-day exposure period. L T50 values (mean±SD, n=5) at 0 psu ranged from 6.6±0.6 to 7.5 ±1.3 d for winkles from Ramsey and Laxey respectively. The values for 60 psu ranged from 7.0 ±0.7 to 8.4 ±0.9 d. No significant differences in LT50 values were obtained for the salinity exposures(ANOVA, P>0.05) but there was a significant difterence in tolerance to desiccation (P<0.01). The winkles from Laxey showed very high susceptibility to desiccation stress probably indicating a physiological trade-off to metal tolerance.

  1. Differential tolerance of Agrostis tenuis populations growing at two mine soils to Cu, Zn, and Pb

    Energy Technology Data Exchange (ETDEWEB)

    Karataglis, S.S.


    The Cu, Zn and Pb tolerance of Agrostis tenuis Sibth. populations found in the area of two mines in England as well as in uncontaminated areas were studied by determining the effect of these metals on the rooting of tillers. The populations proved tolerant to the particular metals present in high quantities in the soil of their original habitats as compared to the populations collected from uncontaminated soil. The populations of the Trelogan mine were tolerant only to Zn and not to Cu and Pb. On the contrary, the populations in the mine of Parys Mountain were highly tolerant to all these metals. A linear correlation in the index of tolerance between Zn and Pb in both mines was found suggesting the possibility of a physiological association of the tolerance mechanisms to these two elements.

  2. Role of hydrous iron oxide formation in attenuation and diel cycling of dissolved trace metals in a stream affected by acid rock drainage (United States)

    Parker, S.R.; Gammons, C.H.; Jones, C.A.; Nimick, D.A.


    Mining-impacted streams have been shown to undergo diel (24-h) fluctuations in concentrations of major and trace elements. Fisher Creek in south-central Montana, USA receives acid rock drainage (ARD) from natural and mining-related sources. A previous diel field study found substantial changes in dissolved metal concentrations at three sites with differing pH regimes during a 24-h period in August 2002. The current work discusses follow-up field sampling of Fisher Creek as well as field and laboratory experiments that examine in greater detail the underlying processes involved in the observed diel concentration changes. The field experiments employed in-stream chambers that were either transparent or opaque to light, filled with stream water and sediment (cobbles coated with hydrous Fe and Al oxides), and placed in the stream to maintain the same temperature. Three sets of laboratory experiments were performed: (1) equilibration of a Cu(II) and Zn(II) containing solution with Fisher Creek stream sediment at pH 6.9 and different temperatures; (2) titration of Fisher Creek water from pH 3.1 to 7 under four different isothermal conditions; and (3) analysis of the effects of temperature on the interaction of an Fe(II) containing solution with Fisher Creek stream sediment under non-oxidizing conditions. Results of these studies are consistent with a model in which Cu, Fe(II), and to a lesser extent Zn, are adsorbed or co-precipitated with hydrous Fe and Al oxides as the pH of Fisher Creek increases from 5.3 to 7.0. The extent of metal attenuation is strongly temperature-dependent, being more pronounced in warm vs. cold water. Furthermore, the sorption/co-precipitation process is shown to be irreversible; once the Cu, Zn, and Fe(II) are removed from solution in warm water, a decrease in temperature does not release the metals back to the water column. ?? 2006 Springer Science+Business Media B.V.

  3. What is regressive autism and why does it occur? Is it the consequence of multi-systemic dysfunction affecting the elimination of heavy metals and the ability to regulate neural temperature?

    Directory of Open Access Journals (Sweden)

    Graham E Ewing


    Full Text Available There is a compelling argument that the occurrence of regressive autism is attributable to genetic and chromosomal abnormalities, arising from the overuse of vaccines, which subsequently affects the stability and function of the autonomic nervous system and physiological systems. That sense perception is linked to the autonomic nervous system and the function of the physiological systems enables us to examine the significance of autistic symptoms from a systemic perspective. Failure of the excretory system influences elimination of heavy metals and facilitates their accumulation and subsequent manifestation as neurotoxins: the long-term consequences of which would lead to neurodegeneration, cognitive and developmental problems. It may also influence regulation of neural hyperthermia. This article explores the issues and concludes that sensory dysfunction and systemic failure, manifested as autism, is the inevitable consequence arising from subtle DNA alteration and consequently from the overuse of vaccines. (Ewing G.W. What is regressive autism and why does it occur? Is it the consequence of multi-systemic dysfunction affecting the elimination of heavy metals and the ability to regulate neural temperature?

  4. Drought Tolerance in Modern and Wild Wheat

    Directory of Open Access Journals (Sweden)

    Hikmet Budak


    Full Text Available The genus Triticum includes bread (Triticum aestivum and durum wheat (Triticum durum and constitutes a major source for human food consumption. Drought is currently the leading threat on world's food supply, limiting crop yield, and is complicated since drought tolerance is a quantitative trait with a complex phenotype affected by the plant's developmental stage. Drought tolerance is crucial to stabilize and increase food production since domestication has limited the genetic diversity of crops including wild wheat, leading to cultivated species, adapted to artificial environments, and lost tolerance to drought stress. Improvement for drought tolerance can be achieved by the introduction of drought-grelated genes and QTLs to modern wheat cultivars. Therefore, identification of candidate molecules or loci involved in drought tolerance is necessary, which is undertaken by “omics” studies and QTL mapping. In this sense, wild counterparts of modern varieties, specifically wild emmer wheat (T. dicoccoides, which are highly tolerant to drought, hold a great potential. Prior to their introgression to modern wheat cultivars, drought related candidate genes are first characterized at the molecular level, and their function is confirmed via transgenic studies. After integration of the tolerance loci, specific environment targeted field trials are performed coupled with extensive analysis of morphological and physiological characteristics of developed cultivars, to assess their performance under drought conditions and their possible contributions to yield in certain regions. This paper focuses on recent advances on drought related gene/QTL identification, studies on drought related molecular pathways, and current efforts on improvement of wheat cultivars for drought tolerance.

  5. Heat tolerance in wheat

    DEFF Research Database (Denmark)

    Sharma, Dew Kumari

    climate, wheat is sensitive to heat stress. We need to understand how our crops will perform in these changing climatic conditions and how we can develop varieties, which are more tolerant. The PhD study focussed on understanding heat tolerance in wheat with a combined approach of plant physiology...... II (PSII), which is a fundamental process in photosynthesis. The first study was conducted to identify cultivars differing in Fv/Fm as a measure of heat tolerance during reproductive phase. The proportion of the total variation in cultivar Fv/Fm that was due to the genotypic difference was termed...... among cultivars due to heat stress as the GD of most of them remained similar in control and stress. The second study investigated if it was possible to use detached leaves to screen for heat tolerance instead of intact plants. The previously selected 41 cultivars, known to differ in v/Fm, were used...


    Piérard, G E; Piérard-Franchimont, C


    Inability to tolerate cosmetics can result from distinct mechanisms which appear as the so-called sensitive skin corresponding to one aspect of invisible dermatosis, or which corresponds to manifestations of a contact allergic or irritation dermatitis.

  7. Rh Nanoparticle Anchoring on Metal Phosphates: Fundamental Aspects and Practical Impacts on Catalysis. (United States)

    Machida, Masato


    Metal phosphates stabilize Rh nanoparticles on their surface via Rh-O-P bonds, in contrast to the Rh-O-M bonds formed on metal oxides (MOx ). The local structure, electronic structure, and redox properties of Rh nanoparticles anchored on metal phosphates, and their practical impacts on catalysis, are reviewed based on recent publications from the author's research group. Because of the covalency of the Rh-O-P bond, Rh oxide is readily reduced to metallic Rh having a higher catalytic activity, whereas Rh oxide on metal oxide supports is more difficult to reduce with an increase of the anchoring strength. Furthermore, Rh metal shows a higher tolerance to reoxidation when supported on metal phosphates because the Rh-O-P bond is preserved under reducing atmospheres. The electron deficiency of Rh metal is another feature that affects its catalytic properties, and the extent of the electron deficiency can be tuned by replacing the metal in the metal phosphate with one of higher basicity. Further impacts on practical performance (thermal stability, poisoning stability, and lean NOx purification) in automobile catalyst applications are also described.

  8. Mycorrhizal colonization does not affect tolerance to defoliation of an annual herb in different light availability and soil fertility treatments but increases flower size in light-rich environments. (United States)

    Aguilar-Chama, Ana; Guevara, Roger


    Heterogeneous distribution of resources in most plant populations results in a mosaic of plant physiological responses tending to maximize plant fitness. This includes plant responses to trophic interactions such as herbivory and mycorrhizal symbiosis which are concurrent in most plants. We explored fitness costs of 50% manual defoliation and mycorrhizal inoculation in Datura stramonium at different light availability and soil fertility environments in a greenhouse experiment. Overall, we showed that non-inoculated and mycorrhiza-inoculated plants did not suffer from 50% manual defoliation in all the tested combinations of light availability and soil fertility treatments, while soil nutrients and light availability predominately affected plant responses to the mycorrhizal inoculation. Fifty percent defoliation had a direct negative effect on reproductive traits whereas mycorrhiza-inoculated plants produced larger flowers than non-inoculated plants when light was not a limiting factor. Although D. stramonium is a facultative selfing species, other investigations had shown clear advantages of cross-pollination in this species; therefore, the effects of mycorrhizal inoculation on flower size observed in this study open new lines of inquiry for our understanding of plant responses to trophic interactions. Also in this study, we detected shifts in the limiting resources affecting plant responses to trophic interactions.

  9. A Nucleocytoplasmic Shuttling Protein in Oxidative Stress Tolerance

    Energy Technology Data Exchange (ETDEWEB)

    Ow, David W.; Song, Wen


    Plants for effective extraction of toxic metals and radionuclides must tolerate oxidative stress. To identify genes that enhance oxidative stress tolerance, an S. pombe cDNA expression plasmid library was screened for the ability to yield hypertolerant colonies. Here, we report on the properties of one gene that confers hypertolerance to cadmium and oxidizing chemicals. This gene appears to be conserved in other organisms as homologous genes are found in human, mouse, fruitfly and Arabidopsis. The fruitfly and Arabidopsis genes likewise enhance oxidative stress tolerance in fission yeast. During oxidative stress, the amount of mRNA does not change, but protein fusions to GFP relocate from the cytoplasm to the nucleus. The same pattern is observed with the Arabidopsis homologue-GFP fusion protein. This behavior suggests a signaling role in oxidative stress tolerance and these conserved proteins may be targets for engineering stress tolerant plants for phytoremediation.

  10. Fault-tolerant design

    CERN Document Server

    Dubrova, Elena


    This textbook serves as an introduction to fault-tolerance, intended for upper-division undergraduate students, graduate-level students and practicing engineers in need of an overview of the field.  Readers will develop skills in modeling and evaluating fault-tolerant architectures in terms of reliability, availability and safety.  They will gain a thorough understanding of fault tolerant computers, including both the theory of how to design and evaluate them and the practical knowledge of achieving fault-tolerance in electronic, communication and software systems.  Coverage includes fault-tolerance techniques through hardware, software, information and time redundancy.  The content is designed to be highly accessible, including numerous examples and exercises.  Solutions and powerpoint slides are available for instructors.   ·         Provides textbook coverage of the fundamental concepts of fault-tolerance; ·         Describes a variety of basic techniques for achieving fault-toleran...

  11. Excessive Cu and Zn affecting on distribution of the metals and activities of glycolytic and nitrogen incorporating key enzymes in mycelia of ectomycorrhizal fungi Suillus bovinus

    Institute of Scientific and Technical Information of China (English)


    Concentration of copper and zinc in isolated Suillus bovinus mycelia, used nutrient solution and 0.5 mol/L EDTA mycelia washing solution were measured to investigate the distribution of heavy metals in mycelia growth in excess copper or zinc nutrient solution. Treated with zinc, most of added zinc maintained in used solution, and 9.8%/14.6% was in/on mycelia in treatment, and in treetment 2 was 3.9%/8.0%in/on mycelia. In the copper applications, copper stimulated in more than on mycelis, i.e., 25.9%/4.5% in/on mycelia in treatment, and 7%/18.8% in/on mycelia while most of copper retained in used nutrient solution. Certain amount of copper or zinc uptake by mycelia led to pronounced influence on glycolysis and nitrogen incorporating process of Suillus bovinus, while the tested enzymes kept constant in treatment.In crude extracts of copper treatment 2 mycelia, activities of HK, PFK and GS were inhibited and decrease to 63%, 48% and 38% and GlDH ncreased by 68 % of the control, respectively. The behaviors of these tested enzymes toward sinc corresponded in general with that towards copper. The potential protection of Suillus bpvoninus for its host plant under excess copper or zinc threaten was discussed.

  12. Intraspecific competition facilitates the evolution of tolerance to insect damage in the perennial plant Solanum carolinense. (United States)

    McNutt, David W; Halpern, Stacey L; Barrows, Kahaili; Underwood, Nora


    Tolerance to herbivory (the degree to which plants maintain fitness after damage) is a key component of plant defense, so understanding how natural selection and evolutionary constraints act on tolerance traits is important to general theories of plant-herbivore interactions. These factors may be affected by plant competition, which often interacts with damage to influence trait expression and fitness. However, few studies have manipulated competitor density to examine the evolutionary effects of competition on tolerance. In this study, we tested whether intraspecific competition affects four aspects of the evolution of tolerance to herbivory in the perennial plant Solanum carolinense: phenotypic expression, expression of genetic variation, the adaptive value of tolerance, and costs of tolerance. We manipulated insect damage and intraspecific competition for clonal lines of S. carolinense in a greenhouse experiment, and measured tolerance in terms of sexual and asexual fitness components. Compared to plants growing at low density, plants growing at high density had greater expression of and genetic variation in tolerance, and experienced greater fitness benefits from tolerance when damaged. Tolerance was not costly for plants growing at either density, and only plants growing at low density benefited from tolerance when undamaged, perhaps due to greater intrinsic growth rates of more tolerant genotypes. These results suggest that competition is likely to facilitate the evolution of tolerance in S. carolinense, and perhaps in other plants that regularly experience competition, while spatio-temporal variation in density may maintain genetic variation in tolerance.

  13. Tolerable Intolerance: An Evolutionary Model


    Martin Gregor


    A cornerstone of liberal-democratic regimes is the right of free speech, granted even to nonliberals who manifestly oppose it. Communism and political Islamism are two primary examples of ideologies which are tolerated in spite of calls for the limits on the right of expression. Not surprisingly, it is often argued that a tolerant society needs laws preventing non-tolerant beliefs from attacking tolerance. Yet, does intolerance necessarily prosper in a tolerant society, or is deemed to decay?...

  14. Ammonium and nitrate tolerance in lichens. (United States)

    Hauck, Markus


    Since lichens lack roots and take up water, solutes and gases over the entire thallus surface, these organisms respond more sensitively to changes in atmospheric purity than vascular plants. After centuries where effects of sulphur dioxide and acidity were in the focus of research on atmospheric chemistry and lichens, recently the globally increased levels of ammonia and nitrate increasingly affect lichen vegetation and gave rise to intense research on the tolerance of lichens to nitrogen pollution. The present paper discusses the main findings on the uptake of ammonia and nitrate in the lichen symbiosis and to the tolerance of lichens to eutrophication. Ammonia and nitrate are both efficiently taken up under ambient conditions. The tolerance to high nitrogen levels depends, among others, on the capability of the photobiont to provide sufficient amounts of carbon skeletons for ammonia assimilation. Lowly productive lichens are apparently predisposed to be sensitive to excess nitrogen.

  15. Tolerable soil erosion in Europe (United States)

    Verheijen, Frank; Jones, Bob; Rickson, Jane; Smith, Celina


    Soil loss by erosion has been identified as an important threat to soils in Europe* and is recognised as a contributing process to soil degradation and associated deterioration, or loss, of soil functioning. From a policy perspective, it is imperative to establish well-defined baseline values to evaluate soil erosion monitoring data against. For this purpose, accurate baseline values - i.e. tolerable soil loss - need to be differentiated at appropriate scales for monitoring and, ideally, should take soil functions and even changing environmental conditions into account. The concept of tolerable soil erosion has been interpreted in the scientific literature in two ways: i) maintaining the dynamic equilibrium of soil quantity, and ii) maintaining biomass production, at a location. The first interpretation ignores soil quality by focusing only on soil quantity. The second approach ignores many soil functions by focusing only on the biomass (particularly crop) production function of soil. Considering recognised soil functions, tolerable soil erosion may be defined as 'any mean annual cumulative (all erosion types combined) soil erosion rate at which a deterioration or loss of one or more soil functions does not occur'. Assumptions and problems of this definition will be discussed. Soil functions can generally be judged not to deteriorate as long as soil erosion does not exceed soil formation. At present, this assumption remains largely untested, but applying the precautionary principle appears to be a reasonable starting point. Considering soil formation rates by both weathering and dust deposition, it is estimated that for the majority of soil forming factors in most European situations, soil formation rates probably range from ca. 0.3 - 1.4 t ha-1 yr-1. Although the current agreement on these values seems relatively strong, how the variation within the range is spatially distributed across Europe and how this may be affected by climate, land use and land management

  16. Is the enthalpy of fusion of tris(acetylacetonato)metal(III) complexes affected by their potential energy in the crystal state? (United States)

    Sabolović, Jasmina; Mrak, Zeljko; Kostrun, Sanja; Janeković, August


    In this Article we present enthalpies of fusion and melting points obtained from new thermochemical measurements of tris(acetylacetonato)metal(III), M(acac)(3), complexes (M = Fe, Al, Cr, Mn, Co) using differential scanning calorimetry (DSC) and evaluate them in relation to their different values found in the literature. An enthalpy of fusion of 27.67 kJ mol(-)(1) was derived for Mn(acac)(3) from a symmetrical DSC thermogram captured for the first time. The enthalpy value was indirectly confirmed with the solubility measurements of Mn(acac)(3) in acetylacetone. A hypothesis has been stated that the enthalpy of fusion and the potential energy of M(acac)(3) in the crystal state may be related. To calculate molecular in-crystal potential energy, in this Article we proposed a molecular mechanics model for the M(acac)(3) class of compounds. Nine X-ray crystal structures of M(acac)(3) complexes (M = Fe, Al, V, Mn, Co, Cr, Sc) were included in the modeling. The conformational potential energy was minimized for a molecule surrounded by other molecules in the crystal lattice. The partial charges from two schemes, the electrostatic potential (ESP) fit and the natural population analysis (NPA), were used to construct two types of force fields to examine which force field type would yield a better fit with the experimental thermal properties. The final force fields were named FF-ESP and FF-NPA. Both force field sets reproduced well the experimental crystal data of nine M(acac)(3) complexes as well as of tris(3-methyl-2,4-pentanedionato-O,O')cobalt(III). Only in-crystal potential energies derived by FF-NPA yielded a significant correlation (correlation coefficient R = -0.71) with the measured enthalpies of fusion. The enthalpy of fusion for Co(acac)(3) could not be determined experimentally because of simultaneous decomposition and fusion, and it is predicted to be 33.2 kJ mol(-)(1) from the correlation regression line.

  17. An Alternative to Precious Metals: Hg(ClO4)2·3H2O as a Cheap and Water-Tolerant Catalyst for the Cycloisomerization of Allenols. (United States)

    Alcaide, Benito; Almendros, Pedro; Luna, Amparo; Soriano, Elena


    Hg(ClO4)2·3H2O, a cheap, water-tolerant, and stable salt, catalyzes the cycloisomerization reaction or α-allenols to 2,5-dihydrofurans in an efficient and selective manner. The reaction is general and can be applied to differently functionalized substrates, including alkyl-substituted, aryl-substituted, enantiopure, and tertiary allenols. In addition, density functional theory (DFT) calculations were performed to obtain insight into various aspects of the controlled reactivity of α-allenols under mercury catalysis. They suggest a dual activation of the allenol by the Hg complex that drives the reaction to the chemoselective formation of 2,5-dihydrofurans.

  18. What is regressive autism and why does it occur? Is it the consequence of multi-systemic dysfunction affecting the elimination of heavy metals and the ability to regulate neural temperature?

    Directory of Open Access Journals (Sweden)

    Graham W. Ewing


    Full Text Available There is a compelling argument that the occurrence of regressive autism is attributable to genetic and chromosomal abnormalities, arising from the overuse of vaccines, which subsequently affects the stability and function of the autonomic nervous system and physiological systems. That sense perception is linked to the autonomic nervous system and the function of the physiological systems enables us to examine the significance of autistic symptoms from a systemic perspective. Failure of the excretory system influences elimination of heavy metals and facilitates their accumulation and subsequent manifestation as neurotoxins: the long-term consequences of which would lead to neurodegeneration, cognitive and developmental problems. It may also influence regulation of neural hyperthermia. This article explores the issues and concludes that sensory dysfunction and systemic failure, manifested as autism, is the inevitable consequence arising from subtle DNA alteration and consequently from the overuse of vaccines.

  19. Effects of alloying elements on fracture toughness in the transition temperature region of base metals and simulated heat-affected zones of Mn-Mo-Ni low-alloy steels (United States)

    Kim, Sangho; Im, Young-Roc; Lee, Sunghak; Lee, Hu-Chul; Kim, Sung-Joon; Hong, Jun Hwa


    This study is concerned with the effects of alloying elements on fracture toughness in the transition temperature region of base metals and heat-affected zones (HAZs) of Mn-Mo-Ni low-alloy steels. Three kinds of steels whose compositions were varied from the composition specification of SA 508 steel (grade 3) were fabricated by vacuum-induction melting and heat treatment, and their fracture toughness was examined using an ASTM E1921 standard test method. In the steels that have decreased C and increased Mo and Ni content, the number of fine M2C carbides was greatly increased and the number of coarse M3C carbides was decreased, thereby leading to the simultaneous improvement of tensile properties and fracture toughness. Brittle martensite-austenite (M-A) constituents were also formed in these steels during cooling, but did not deteriorate fracture toughness because they were decomposed to ferrite and fine carbides after tempering. Their simulated HAZs also had sufficient impact toughness after postweld heat treatment. These findings indicated that the reduction in C content to inhibit the formation of coarse cementite and to improve toughness and the increase in Mo and Ni to prevent the reduction in hardenability and to precipitate fine M2C carbides were useful ways to improve simultaneously the tensile and fracture properties of the HAZs as well as the base metals.

  20. Tolerance and recognition

    Directory of Open Access Journals (Sweden)

    Hans Marius Hansteen


    Full Text Available Even though “toleration” and “recognition” designate opposing attitudes (to tolerate something, implies a negative stance towards it, whereas recognition seems to imply a positive one, the concepts do not constitute mutually exclusive alternatives. However, “toleration” is often associated with liberal universalism, focusing on individual rights, whereas “recognition” often connotes communitarian perspectives, focusing on relations and identity. This paper argues that toleration may be founded on recognition, and that recognition may imply toleration. In outlining a differentiated understanding of the relationship between toleration and recognition, it seems apt to avoid an all-to-general dichotomy between universalism and particularism or, in other words, to reach beyond the debate between liberalism and communitarianism in political philosophy.The paper takes as its starting point the view that the discussion on toleration and diversity in intercultural communication is one of the contexts where it seems important to get beyond the liberal/communitarian dichotomy. Some basic features of Rainer Forst’s theory of toleration and Axel Honneth’s theory of the struggle for recognition are presented, in order to develop a more substantial understanding of the relationship between the concepts of toleration and recognition. One lesson from Forst is that toleration is a normatively dependent concept, i.e., that it is impossible to deduce principles for toleration and its limits from a theory of toleration as such. A central lesson from Honneth is that recognition – understood as a basic human need – is always conflictual and therefore dynamic.Accordingly, a main point in the paper is that the theory of struggles for and about recognition (where struggles for designates struggles within an established order of recognition, and struggles about designates struggles that challenge established orders of recognition may clarify what

  1. Den liberale tolerance

    DEFF Research Database (Denmark)

    Mchangama, Jacob; Andersen, Rasmus Fonnesbæk


    Tolerance er en kerneværdi i den liberal-demokratiske samfundsordenen, men i vor tid er det liberale tolerancebegreb om ikke at gribe ind i det, man ikke synes om, kommet under angreb fra flere sider, især som følge af problemer med indvandring og integration. Tolerance opfattes i stigende grad som...... begrænset tolerancebegreb igen bør træde i stedet for den multikulturalistisk inspirerede forståelse af tolerance, som er fremtrædende i dag, og som faktisk begrunder en institutionaliseret intolerance i form af en række begrænsninger på særligt ytringsfriheden....

  2. Technology transfer for the revegetation of phytotoxic, smelter-denuded soils -- The potential use of minimal amelioration and reciprocal transplantation of metal-tolerant grasses at Flin Flon, Manitoba

    Energy Technology Data Exchange (ETDEWEB)

    Winterhalder, K. [Laurentian Univ., Sudbury, Ontario (Canada). Dept. of Biology


    Soils in the Sudbury mining and smelting region that have been rendered phytotoxic and barren by acidification and particulate copper and nickel contamination can be detoxified and revegetated by the surface application of ground limestone, an approach referred to as minimal amelioration. Soils at Flin Flon, Manitoba have been similarly denuded, in this case by acidification and particulate copper and zinc contamination. Field plot experiments carried out in Flin Flon, a more northerly location than Sudbury, with a more severe climate, have shown that the surface application of ground limestone to barren soil leads to colonization of birches, poplars and willows, as on the Sudbury barrens. Furthermore, it has been shown that the copper/nickel tolerant ecotype of Tufted Hairgrass (Deschampsia caevpitosa) found on the Sudbury barrens can be successfully transplanted onto the Flin Flon barrens, and that the copper/zinc tolerant ecotype of Browntop (Agrostis tenuis) found on the Flin Flon barrens can be successfully transplanted onto phytotoxic soils in Sudbury. The significance of these findings, and the possibility of extending such technology transfer to similar sites, such as the copper/zinc smelters of the Kola Peninsula in Russia, are discussed.

  3. Inequality, Tolerance, and Growth

    DEFF Research Database (Denmark)

    Bjørnskov, Christian


    This paper argues for the importance of individuals' tolerance of inequality for economic growth. By using the political ideology of governments as a measure of revealed tolerance of inequality, the paper shows that controlling for ideology improves the accuracy with which the effects of inequality...... are measured. Results show that inequality reduces growth but more so in societies where people perceive it as being relatively unfair. Further results indicate that legal quality and social trust are likely transmission channels for the effects of inequality....

  4. Measurement of ambiguity tolerance. (United States)

    Norton, R W


    Presented definitions for the construct of ambiguity tolerance. The measure of ambiguity tolerance (MAT-50) had high internal reliability (r = .88) and high test-retest reliability (r = .86) over a 10-to-12 week period. A content analysis of the measure and a subjective analysis by 20 graduate students indicated adequate content validity. A multivariate comparison with two other ambiguity measures, two rigidity measures, and a short dogmatism measure provided strong evidence for criteria-related validity. Finally, four independent empirical studies showed good construct validity.

  5. Toleration out of respect?

    DEFF Research Database (Denmark)

    Lægaard, Sune


    Under conditions of pluralism different cultures, interests or values can come into conflict, which raises the problem of how to secure peaceful co-existence. The idea of toleration historically emerged as an answer to this problem. Recently Rainer Forst has argued that toleration should not just...... prescription, which Forst presents as a requirement of justice. At both levels, it is argued that Forst’s respect conception is problematic since it presupposes that answers to very substantial normative questions, which are precisely what people tend to disagree on under conditions of pluralism, are already...

  6. The rice OsNAC6 transcription factor orchestrates multiple molecular mechanisms involving root structural adaptions and nicotianamine biosynthesis for drought tolerance. (United States)

    Lee, Dong-Keun; Chung, Pil Joong; Jeong, Jin Seo; Jang, Geupil; Bang, Seung Woon; Jung, Harin; Kim, Youn Shic; Ha, Sun-Hwa; Choi, Yang Do; Kim, Ju-Kon


    Drought has a serious impact on agriculture worldwide. A plant's ability to adapt to rhizosphere drought stress requires reprogramming of root growth and development. Although physiological studies have documented the root adaption for tolerance to the drought stress, underlying molecular mechanisms is still incomplete, which is essential for crop engineering. Here, we identified OsNAC6-mediated root structural adaptations, including increased root number and root diameter, which enhanced drought tolerance. Multiyear drought field tests demonstrated that the grain yield of OsNAC6 root-specific overexpressing transgenic rice lines was less affected by drought stress than were nontransgenic controls. Genome-wide analyses of loss- and gain-of-function mutants revealed that OsNAC6 up-regulates the expression of direct target genes involved in membrane modification, nicotianamine (NA) biosynthesis, glutathione relocation, 3'-phophoadenosine 5'-phosphosulphate accumulation and glycosylation, which represent multiple drought tolerance pathways. Moreover, overexpression of NICOTIANAMINE SYNTHASE genes, direct targets of OsNAC6, promoted the accumulation of the metal chelator NA and, consequently, drought tolerance. Collectively, OsNAC6 orchestrates novel molecular drought tolerance mechanisms and has potential for the biotechnological development of high-yielding crops under water-limiting conditions.

  7. Effect of soil properties, heavy metals and emerging contaminants in the soil nematodes diversity. (United States)

    Gutiérrez, Carmen; Fernández, Carlos; Escuer, Miguel; Campos-Herrera, Raquel; Beltrán Rodríguez, M Eulalia; Carbonell, Gregoria; Rodríguez Martín, Jose Antonio


    Among soil organisms, nematodes are seen as the most promising candidates for bioindications of soil health. We hypothesized that the soil nematode community structure would differ in three land use areas (agricultural, forest and industrial soils), be modulated by soil parameters (N, P, K, pH, SOM, CaCO3, granulometric fraction, etc.), and strongly affected by high levels of heavy metals (Cd, Pb, Zn, Cr, Ni, Cu, and Hg) and emerging contaminants (pharmaceuticals and personal care products, PPCPs). Although these pollutants did not significantly affect the total number of free-living nematodes, diversity and structure community indices vastly altered. Our data showed that whereas nematodes with r-strategy were tolerant, genera with k-strategy were negatively affected by the selected pollutants. These effects diminished in soils with high levels of heavy metals given their adaptation to the historical pollution in this area, but not to emerging pollutants like PPCPs.

  8. 3HP tolerance

    DEFF Research Database (Denmark)


    Cells and cell cultures are provided that have improved tolerance to 3-hydroxypropionic acid (3HP). Genetic modifications to provide a mutated or overexpressed SFA1 gene or other enhancement of 3HP detoxification via a glutathione- dependent dehydrogenase reaction, including medium supplementation...

  9. Toleration and its enemies

    DEFF Research Database (Denmark)

    Jarvad, Ib Martin


    After a presentation of the development of freedom of expression in Danish constitutional law, to freedom of the press in European human rights law - the Jersild case- to a right to mock and ridicule other faiths in recent Danish practice, the essay of Locke on toleration is examined, its...

  10. Ethanol tolerance in yeasts. (United States)

    Casey, G P; Ingledew, W M


    It is now certain that the inherent ethanol tolerance of the Saccharomyces strain used is not the prime factor regulating the level of ethanol that can be produced in a high sugar brewing, wine, sake, or distillery fermentation. In fact, in terms of the maximum concentration that these yeasts can produce under batch (16 to 17% [v/v]) or fed-batch conditions, there is clearly no difference in ethanol tolerance. This is not to say, however, that under defined conditions there is no difference in ethanol tolerance among different Saccharomyces yeasts. This property, although a genetic determinant, is clearly influenced by many factors (carbohydrate level, wort nutrition, temperature, osmotic pressure/water activity, and substrate concentration), and each yeast strain reacts to each factor differently. This will indeed lead to differences in measured tolerance. Thus, it is extremely important that each of these be taken into consideration when determining "tolerance" for a particular set of fermentation conditions. The manner in which each alcohol-related industry has evolved is now known to have played a major role in determining traditional thinking on ethanol tolerance in Saccharomyces yeasts. It is interesting to speculate on how different our thinking on ethanol tolerance would be today if sake fermentations had not evolved with successive mashing and simultaneous saccharification and fermentation of rice carbohydrate, if distillers' worts were clarified prior to fermentation but brewers' wort were not, and if grape skins with their associated unsaturated lipids had not been an integral part of red wine musts. The time is now ripe for ethanol-related industries to take advantage of these findings to improve the economies of production. In the authors' opinion, breweries could produce higher alcohol beers if oxygenation (leading to unsaturated lipids) and "usable" nitrogen source levels were increased in high gravity worts. White wine fermentations could also, if

  11. A Comparison of Weld-Repaired and Base Metal for Inconel 718 and CRES 321 at Cryogenic and Room Temperatures (United States)

    Newman, John A.; Smith, Stephen W.; Willard, Scott A.; Piascik, Robert S.


    Fatigue crack growth tests were conducted to characterize the performance of Inconel 718 and CRES 321 welds, weld heat-affect-zone and parent metal at room temperature laboratory air and liquid nitrogen (-196oC) environments. The results of this study were required to predict the damage tolerance behavior of proposed orbiter main engine hydrogen fuel liner weld repairs. Experimental results show that the room and cryogenic temperature fatigue crack growth characteristics of both alloys are not significantly degraded by the weld repair process. However, both Inconel 718 and CRES 321 exhibited lower apparent toughness within the weld repair region compared to the parent metal.

  12. Phenotypic and genetic diversity in Sinorhizobium meliloti and S. medicae from drought and salt affected regions of Morocco

    Directory of Open Access Journals (Sweden)

    Udupa Sripada M


    Full Text Available Abstract Background Sinorhizobium meliloti and S. medicae are symbiotic nitrogen fixing bacteria in root nodules of forage legume alfalfa (Medicago sativa L.. In Morocco, alfalfa is usually grown in marginal soils of arid and semi-arid regions frequently affected by drought, extremes of temperature and soil pH, soil salinity and heavy metals, which affect biological nitrogen fixing ability of rhizobia and productivity of the host. This study examines phenotypic diversity for tolerance to the above stresses and genotypic diversity at Repetitive Extragenic Pallindromic DNA regions of Sinorhizobium nodulating alfalfa, sampled from marginal soils of arid and semi-arid regions of Morocco. Results RsaI digestion of PCR amplified 16S rDNA of the 157 sampled isolates, assigned 136 isolates as S. meliloti and the rest as S. medicae. Further phenotyping of these alfalfa rhizobia for tolerance to the environmental stresses revealed a large degree of variation: 55.41%, 82.16%, 57.96% and 3.18% of the total isolates were tolerant to NaCl (>513 mM, water stress (-1.5 MPa, high temperature (40°C and low pH (3.5, respectively. Sixty-seven isolates of S. meliloti and thirteen isolates of S. medicae that were tolerant to salinity were also tolerant to water stress. Most of the isolates of the two species showed tolerance to heavy metals (Cd, Mn and Zn and antibiotics (chloramphenicol, spectinomycin, streptomycin and tetracycline. The phenotypic clusters observed by the cluster analysis clearly showed adaptations of the S. meliloti and S. medicae strains to the multiple stresses. Genotyping with rep-PCR revealed higher genetic diversity within these phenotypic clusters and classified all the 157 isolates into 148 genotypes. No relationship between genotypic profiles and the phenotypes was observed. The Analysis of Molecular Variance revealed that largest proportion of significant (P Conclusion High degree of phenotypic and genotypic diversity is present in S

  13. Zinc, magnesium, and calcium ion supplementation confers tolerance to acetic acid stress in industrial Saccharomyces cerevisiae utilizing xylose. (United States)

    Ismail, Ku Syahidah Ku; Sakamoto, Takatoshi; Hasunuma, Tomohisa; Zhao, Xin-Qing; Kondo, Akihiko


    Lignocellulosic biomass is a potential substrate for ethanol production. However, pretreatment of lignocellulosic materials produces inhibitory compounds such as acetic acid, which negatively affect ethanol production by Saccharomyces cerevisiae. Supplementation of the medium with three metal ions (Zn(2+) , Mg(2+) , and Ca(2+) ) increased the tolerance of S. cerevisiae toward acetic acid compared to the absence of the ions. Ethanol production from xylose was most improved (by 34%) when the medium was supplemented with 2 mM Ca(2+) , followed by supplementation with 3.5 mM Mg(2+) (29% improvement), and 180 μM Zn(2+) (26% improvement). Higher ethanol production was linked to high cell viability in the presence of metal ions. Comparative transcriptomics between the supplemented cultures and the control suggested that improved cell viability resulted from the induction of genes controlling the cell wall and membrane. Only one gene, FIT2, was found to be up-regulated in common between the three metal ions. Also up-regulation of HXT1 and TKL1 might enhance xylose consumption in the presence of acetic acid. Thus, the addition of ionic nutrients is a simple and cost-effective method to improve the acetic acid tolerance of S. cerevisiae.

  14. Deconstructing tolerance with clobazam (United States)

    Wechsler, Robert T.; Sankar, Raman; Montouris, Georgia D.; White, H. Steve; Cloyd, James C.; Kane, Mary Clare; Peng, Guangbin; Tworek, David M.; Shen, Vivienne; Isojarvi, Jouko


    Objective: To evaluate potential development of tolerance to adjunctive clobazam in patients with Lennox-Gastaut syndrome. Methods: Eligible patients enrolled in open-label extension study OV-1004, which continued until clobazam was commercially available in the United States or for a maximum of 2 years outside the United States. Enrolled patients started at 0.5 mg·kg−1·d−1 clobazam, not to exceed 40 mg/d. After 48 hours, dosages could be adjusted up to 2.0 mg·kg−1·d−1 (maximum 80 mg/d) on the basis of efficacy and tolerability. Post hoc analyses evaluated mean dosages and drop-seizure rates for the first 2 years of the open-label extension based on responder categories and baseline seizure quartiles in OV-1012. Individual patient listings were reviewed for dosage increases ≥40% and increasing seizure rates. Results: Data from 200 patients were included. For patients free of drop seizures, there was no notable change in dosage over 24 months. For responder groups still exhibiting drop seizures, dosages were increased. Weekly drop-seizure rates for 100% and ≥75% responders demonstrated a consistent response over time. Few patients had a dosage increase ≥40% associated with an increase in seizure rates. Conclusions: Two-year findings suggest that the majority of patients do not develop tolerance to the antiseizure actions of clobazam. Observed dosage increases may reflect best efforts to achieve seizure freedom. It is possible that the clinical development of tolerance to clobazam has been overstated. identifier: NCT00518713 and NCT01160770. Classification of evidence: This study provides Class III evidence that the majority of patients do not develop tolerance to clobazam over 2 years of treatment. PMID:27683846

  15. Review of Tolerance of Ambiguity

    Institute of Scientific and Technical Information of China (English)



    In this paper, definitions of tolerance of ambiguity both at home and abroad are reviewed first. Then studies of tolerance of ambiguity and foreign language teaching both home and abroad are introduced. At last, the paper proposed that it is of great sig⁃nificance and practicality for us to make further studies on tolerance of ambiguity.

  16. [Effect of Arbuscular Mycorrhiza (AM) on Tolerance of Cattail to Cd Stress in Aquatic Environment]. (United States)

    Luo, Peng-cheng; Li, Hang; Wang, Shu-guang


    Hygrophytes are planted more and more in landscaping and greening in many cities, but they often encounter threat from environmental pollution. Arbuscular mycorrhiza ( AM ) have been confirmed to enhance the tolerance of terrestrial plants to environmental pollution in many previous studies, but it is unclear how they affect hygrophytes. In the present study, a hydroponic culture experiment was carried out to investigate the effects of AM fungi (Glomus etunicatum) inoculation on the tolerance of cattail (Typha latifolia) to different concentrations Cd2+ (0, 2.5, 5.0 mg x L(-1)). The aim was to provide reference for evaluating whether mycorrhizal technology can be used to enhance the tolerance of hygrophytes to environmental pollution. The results showed that symbiotic association was well established between AM fungi and cattail roots, and the mycorrhizal colonization rates (MCR) were beyond 30%. However, MCR presented downward trend one month after mycorrhizal cattails were transported to solution, and the maximal decrease was 25.5% (P < 0.05). AM increased pigment concentrations and peroxidase (POD) activity in cattail leaves, and also increased roots radial oxygen loss. However, AM only produced significant effect on increase of fresh weight in 5 mg x L(-1) Cd2+ solution. Although plant growth was inhibited by 5 mg x L(-1) Cd2+ and MCR was lower, AM increased Cd uptake of cattail at the two Cd2+ levels, and the maximal increments were 40.24% and 56.52% in aboveground and underground parts, respectively. This study indicates that AM has potential to enhance the tolerance of hygrophytes to environmental pollution and might be used to remedy heavy metal pollution.


    Directory of Open Access Journals (Sweden)

    Concepta Margaret McManus


    Full Text Available This study compared the adaptation traits in common crosses of crossbred dairy cattle in central Brazil. Twenty animals of each of three genetic groups were used: zebu (Bos indicus, Simmental x Zebu (SZ and Holstein x Zebu (HZ. The test measured variations in rectal temperature (RT, respiration rate (RR and heart rate (HR of animals in the shade and after exposure to the sun, as well as mean daily milk production throughout the lactation period. The procedure was repeated three times. There were significant interactions between test group and genetic group for the traits investigated and the correlations among traits were low. The RR of the crossbred groups may be controlling body temperature in such a way as not to cause an increase in RT. Milk production influenced RR in crossbred cows exposed to the sun, confirming their poorer adaptation in comparison with zebu cows. We observed that the adaptation can be measured in terms of production within the same genetic group. In conclusion, the crosses with European breeds produced more milk than zebu, although they were influenced by heat/solar radiation.

  18. Fault Tolerant Control Systems

    DEFF Research Database (Denmark)

    Bøgh, S.A.

    and isolation, remedial action decision, and reconfiguration. The integration of these modules in software were considered. The general methodology covered the analysis, design, and implementation of fault tolerant control systems on an overall level. Two detailed studies were presented, one on fault detection......, as for example a variable being zero, low or high. Examples were given that illustrate how such models can be established by simple means, and yet provide important information when combined into a complete system. A special achievement was a method to determine how control loops behave in case of faults......This thesis considered the development of fault tolerant control systems. The focus was on the category of automated processes that do not necessarily comprise a high number of identical sensors and actuators to maintain safe operation, but still have a potential for improving immunity to component...

  19. Damage Tolerance Assessment Branch (United States)

    Walker, James L.


    The Damage Tolerance Assessment Branch evaluates the ability of a structure to perform reliably throughout its service life in the presence of a defect, crack, or other form of damage. Such assessment is fundamental to the use of structural materials and requires an integral blend of materials engineering, fracture testing and analysis, and nondestructive evaluation. The vision of the Branch is to increase the safety of manned space flight by improving the fracture control and the associated nondestructive evaluation processes through development and application of standards, guidelines, advanced test and analytical methods. The Branch also strives to assist and solve non-aerospace related NDE and damage tolerance problems, providing consultation, prototyping and inspection services.

  20. Abuse Tolerance Improvements

    Energy Technology Data Exchange (ETDEWEB)

    Orendorff, Christopher J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Nagasubramanian, Ganesan [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Fenton, Kyle R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Allcorn, Eric [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)


    As lithium-ion battery technologies mature, the size and energy of these systems continues to increase (> 50 kWh for EVs); making safety and reliability of these high energy systems increasingly important. While most material advances for lithium-ion chemistries are directed toward improving cell performance (capacity, energy, cycle life, etc.), there are a variety of materials advancements that can be made to improve lithium-ion battery safety. Issues including energetic thermal runaway, electrolyte decomposition and flammability, anode SEI stability, and cell-level abuse tolerance continue to be critical safety concerns. This report highlights work with our collaborators to develop advanced materials to improve lithium-ion battery safety and abuse tolerance and to perform cell-level characterization of new materials.

  1. Socially-Tolerable Discrimination


    J. Atsu Amegashie


    History is replete with overt discrimination of various forms. However, these forms of discrimination are not equally tolerable. For example, discrimination based on immutable or prohibitively unalterable characteristics such as race or gender is much less acceptable. Why? I develop a simple model of conflict which is driven by either racial (gender) discrimination or generational discrimination (i.e., young versus old). I show that there exist parameters of the model where racial (gender) di...

  2. Arabidopsis thaliana Contains Both Ni2+ and Zn2+ Dependent Glyoxalase I Enzymes and Ectopic Expression of the Latter Contributes More towards Abiotic Stress Tolerance in E. coli (United States)

    Jain, Muskan; Batth, Rituraj; Kumari, Sumita; Mustafiz, Ananda


    The glyoxalase pathway is ubiquitously found in all the organisms ranging from prokaryotes to eukaryotes. It acts as a major pathway for detoxification of methylglyoxal (MG), which deleteriously affects the biological system in stress conditions. The first important enzyme of this system is Glyoxalase I (GLYI). It is a metalloenzyme which requires divalent metal ions for its activity. This divalent metal ion can be either Zn2+ as found in most of eukaryotes or Ni2+ as seen in prokaryotes. In the present study, we have found three active GLYI enzymes (AtGLYI2, AtGLYI3 and AtGLYI6) belonging to different metal activation classes coexisting in Arabidopsis thaliana. These enzymes have been found to efficiently complement the GLYI yeast mutants. These three enzymes have been characterized in terms of their activity, metal dependency, kinetic parameters and their role in conferring tolerance to multiple abiotic stresses in E. coli and yeast. AtGLYI2 was found to be Zn2+ dependent whereas AtGLYI3 and AtGLYI6 were Ni2+ dependent. Enzyme activity of Zn2+ dependent enzyme, AtGLYI2, was observed to be exceptionally high (~250–670 fold) as compared to Ni2+ dependent enzymes, AtGLYI3 and AtGLYI6. The activity of these GLYI enzymes correlated well to their role in stress tolerance. Heterologous expression of these enzymes in E. coli led to better tolerance against various stress conditions. This is the first report of a higher eukaryotic species having multiple active GLYI enzymes belonging to different metal activation classes. PMID:27415831

  3. Arabidopsis thaliana Contains Both Ni2+ and Zn2+ Dependent Glyoxalase I Enzymes and Ectopic Expression of the Latter Contributes More towards Abiotic Stress Tolerance in E. coli.

    Directory of Open Access Journals (Sweden)

    Muskan Jain

    Full Text Available The glyoxalase pathway is ubiquitously found in all the organisms ranging from prokaryotes to eukaryotes. It acts as a major pathway for detoxification of methylglyoxal (MG, which deleteriously affects the biological system in stress conditions. The first important enzyme of this system is Glyoxalase I (GLYI. It is a metalloenzyme which requires divalent metal ions for its activity. This divalent metal ion can be either Zn2+ as found in most of eukaryotes or Ni2+ as seen in prokaryotes. In the present study, we have found three active GLYI enzymes (AtGLYI2, AtGLYI3 and AtGLYI6 belonging to different metal activation classes coexisting in Arabidopsis thaliana. These enzymes have been found to efficiently complement the GLYI yeast mutants. These three enzymes have been characterized in terms of their activity, metal dependency, kinetic parameters and their role in conferring tolerance to multiple abiotic stresses in E. coli and yeast. AtGLYI2 was found to be Zn2+ dependent whereas AtGLYI3 and AtGLYI6 were Ni2+ dependent. Enzyme activity of Zn2+ dependent enzyme, AtGLYI2, was observed to be exceptionally high (~250-670 fold as compared to Ni2+ dependent enzymes, AtGLYI3 and AtGLYI6. The activity of these GLYI enzymes correlated well to their role in stress tolerance. Heterologous expression of these enzymes in E. coli led to better tolerance against various stress conditions. This is the first report of a higher eukaryotic species having multiple active GLYI enzymes belonging to different metal activation classes.

  4. Drought Tolerance in Wheat

    Directory of Open Access Journals (Sweden)

    Arash Nezhadahmadi


    Full Text Available Drought is one of the most important phenomena which limit crops’ production and yield. Crops demonstrate various morphological, physiological, biochemical, and molecular responses to tackle drought stress. Plants’ vegetative and reproductive stages are intensively influenced by drought stress. Drought tolerance is a complicated trait which is controlled by polygenes and their expressions are influenced by various environmental elements. This means that breeding for this trait is so difficult and new molecular methods such as molecular markers, quantitative trait loci (QTL mapping strategies, and expression patterns of genes should be applied to produce drought tolerant genotypes. In wheat, there are several genes which are responsible for drought stress tolerance and produce different types of enzymes and proteins for instance, late embryogenesis abundant (lea, responsive to abscisic acid (Rab, rubisco, helicase, proline, glutathione-S-transferase (GST, and carbohydrates during drought stress. This review paper has concentrated on the study of water limitation and its effects on morphological, physiological, biochemical, and molecular responses of wheat with the possible losses caused by drought stress.

  5. Robot Position Sensor Fault Tolerance (United States)

    Aldridge, Hal A.


    Robot systems in critical applications, such as those in space and nuclear environments, must be able to operate during component failure to complete important tasks. One failure mode that has received little attention is the failure of joint position sensors. Current fault tolerant designs require the addition of directly redundant position sensors which can affect joint design. A new method is proposed that utilizes analytical redundancy to allow for continued operation during joint position sensor failure. Joint torque sensors are used with a virtual passive torque controller to make the robot joint stable without position feedback and improve position tracking performance in the presence of unknown link dynamics and end-effector loading. Two Cartesian accelerometer based methods are proposed to determine the position of the joint. The joint specific position determination method utilizes two triaxial accelerometers attached to the link driven by the joint with the failed position sensor. The joint specific method is not computationally complex and the position error is bounded. The system wide position determination method utilizes accelerometers distributed on different robot links and the end-effector to determine the position of sets of multiple joints. The system wide method requires fewer accelerometers than the joint specific method to make all joint position sensors fault tolerant but is more computationally complex and has lower convergence properties. Experiments were conducted on a laboratory manipulator. Both position determination methods were shown to track the actual position satisfactorily. A controller using the position determination methods and the virtual passive torque controller was able to servo the joints to a desired position during position sensor failure.

  6. Affective Urbanism

    DEFF Research Database (Denmark)

    Samson, Kristine

    Urban design and architecture are increasingly used as material and affective strategies for setting the scene, for manipulation and the production of urban life: The orchestration of atmospheres, the framing and staging of urban actions, the programming for contemplation, involvement, play, expe...... affects can be choreographed and designed intentionally or whether it arises from unpredictable circumstances within urbanity itself....

  7. Affective Maps

    DEFF Research Database (Denmark)

    Salovaara-Moring, Inka

    of environmental knowledge production. It uses InfoAmazonia, the databased platform on Amazon rainforests, as an example of affective geo-visualization within information mapping that enhances embodiment in the experience of the information. Amazonia is defined as a digitally created affective (map)space within...

  8. Aspect Ratio Model for Radiation-Tolerant Dummy Gate-Assisted n-MOSFET Layout. (United States)

    Lee, Min Su; Lee, Hee Chul


    In order to acquire radiation-tolerant characteristics in integrated circuits, a dummy gate-assisted n-type metal oxide semiconductor field effect transistor (DGA n-MOSFET) layout was adopted. The DGA n-MOSFET has a different channel shape compared with the standard n-MOSFET. The standard n-MOSFET has a rectangular channel shape, whereas the DGA n-MOSFET has an extended rectangular shape at the edge of the source and drain, which affects its aspect ratio. In order to increase its practical use, a new aspect ratio model is proposed for the DGA n-MOSFET and this model is evaluated through three-dimensional simulations and measurements of the fabricated devices. The proposed aspect ratio model for the DGA n-MOSFET exhibits good agreement with the simulation and measurement results.

  9. Damage Tolerance Assessment of Friction Pull Plug Welds (United States)

    McGill, Preston; Burkholder, Jonathan


    Friction stir welding is a solid state welding process developed and patented by The Welding Institute in Cambridge, England. Friction stir welding has been implemented in the aerospace industry in the fabrication of longitudinal welds in pressurized cryogenic propellant tanks. As the industry looks to implement friction stir welding in circumferential welds in pressurized cryogenic propellant tanks, techniques to close out the termination hole associated with retracting the pin tool are being evaluated. Friction pull plug welding is under development as a one means of closing out the termination hole. A friction pull plug weld placed in a friction stir weld results in a non-homogenous weld joint where the initial weld, plug weld, their respective heat affected zones and the base metal all interact. The welded joint is a composite, plastically deformed material system with a complex residual stress field. In order to address damage tolerance concerns associated with friction plug welds in safety critical structures, such as propellant tanks, nondestructive inspection and proof testing may be required to screen hardware for mission critical defects. The efficacy of the nondestructive evaluation or the proof test is based on an assessment of the critical flaw size in the test or service environments. Test data relating residual strength capability to flaw size in two aluminum alloy friction plug weld configurations is presented.

  10. Arsenite tolerance in rice (Oryza sativa L.) involves coordinated role of metabolic pathways of thiols and amino acids. (United States)

    Tripathi, Preeti; Tripathi, Rudra Deo; Singh, Rana Pratap; Dwivedi, Sanjay; Chakrabarty, Debasis; Trivedi, Prabodh K; Adhikari, Bijan


    Thiolic ligands and several amino acids (AAs) are known to build up in plants against heavy metal stress. In the present study, alteration of various AAs in rice and its synchronized role with thiolic ligand was explored for arsenic (As) tolerance and detoxification. To understand the mechanism of As tolerance and stress response, rice seedlings of one tolerant (Triguna) and one sensitive (IET-4786) cultivar were exposed to arsenite (0-25 μM) for 7 days for various biochemical analyses using spectrophotometer, HPLC and ICPMS. Tolerant and sensitive cultivars respond differentially in terms of thiol metabolism, essential amino acids (EEAs) and nonessential amino acids (NEEAs) vis-á-vis As accumulation. Thiol biosynthesis-related enzymes were positively correlated to As accumulation in Triguna. Conversely, these enzymes, cysteine content and GSH/GSSG ratio declined significantly in IET-4786 upon As exposure. The level of identified phytochelatin (PC) species (PC(2), PC(3) and PC(4)) and phytochelatin synthase activity were also more pronounced in Triguna than IET-4786. Nearly all EAAs were negatively affected by As-induced oxidative stress (except phenylalanine in Triguna), but more significantly in IET-4786 than Triguna. However, most of the stress-responsive NEAAs like glutamic acid, histidine, alanine, glycine, tyrosine, cysteine and proline were enhanced more prominently in Triguna than IET-4786 upon As exposure. The study suggests that IET-4786 appears sensitive to As due to reduction of AAs and thiol metabolic pathway. However, a coordinated response of thiolic ligands and stress-responsive AAs seems to play role for As tolerance in Triguna to achieve the effective complexation of As by PCs.

  11. Vacuolar iron transporter BnMEB2 is involved in enhancing iron tolerance of Brassica napus

    Directory of Open Access Journals (Sweden)

    Wei Zhu


    Full Text Available Iron toxicity is a major nutrient disorder that severely affects crop development and yield. Vacuolar detoxification of metal stress is an important strategy for plants to survive and adapt to this adverse environment. Vacuolar iron transporter (VIT members are involved in this process and play essential roles in iron storage and transport. In this study, a rapeseed VIT gene BnMEB2 (BnaC07g30170D was identified. BnMEB2 is a homolog to Arabidopsis MEB2 (At5g24290 and acts as a detoxifier in vacuolar sequestration of divalent metal. Transient expression analysis revealed that BnMEB2 was localized to the vacuolar membrane. Q-PCR detection showed a high expression of BnMEB2 in mature (60-day-old leaves and could be obviously induced by exogenous iron stress in both roots and leaves. Over-expressed BnMEB2 in both Arabidopsis wild type and meb2 mutant seedlings resulted in greatly improved iron tolerability with no significant changes in the expression level of other vacuolar iron transporter genes. The mutant meb2 grew slowly and its root hair elongation was inhibited under high iron concentration condition while BnMEB2 over-expressed transgenic plants of the mutant restored the phenotypes with apparently higher iron storage in roots and dramatically increased iron content in the whole plant. Taken together, these results suggested that BnMEB2 was a VIT gene in rapeseed which was necessary for safe storage and vacuole detoxification function of excess iron to enhance the tolerance of iron toxicity. This research sheds light on a potentially new strategy for attenuating hazardous metal stress from environment and improving iron biofortification in Brassicaceae crops.

  12. The study of the microRNA-181b affect U87 glioma stem cells on the chemotherapy tolerance to temozolomide%microRNA-181b影响U87胶质瘤细胞干细胞对替莫唑胺化疗耐受性的实验研究

    Institute of Scientific and Technical Information of China (English)

    李平; 赵兵; 吴德俊; 王少华; 李德坤; 江涛


    Objective To establish the miR-181b lentiviral vector infected the U87 glioma stem cells model,than detect the U87 glioma stem cells' chemotherapy tolerance to temozolomide (TMZ),and to explore the significance of the miR-181 b for malignant glioma (gliomablastoma multiforme,GBM) in the adjuvant chemotherapy.Methods Using the miR-181b lentiviral vector transfected the U87 glioma stem cells and improve the level of miR-181b in the U87 glioma stem cells.RT-PCR,Secondary neurospheres formed assay,agarose colony formation assay and MTT assay were used to detect the role of the miR-181b affect the U87 glioma stem the TMZ chemotherapy tolerance.Results The level of miR-181b in the U87 glioma stem cells was significantly increased after miR-181b lentiviral vectors were transfected the U87 glioma stem cells,and the growth of U87 glioma stem cells were significantly inhibited.Furthermore,miR-181b can strengthen the role of TMZ in the growth inhibition of U87 glioma stem cells.Condusions We found that miR-181b can strengthen the role of TMZ in the growth inhibition of U87 glioma stem cells,miR-181 b may play a certain role of improving the sensitivity of U87 glioma stem cells to TMZ and reducing the chemotherapy tolerance.%目的 本研究旨在建立miR-181b慢病毒载体感染U87胶质瘤干细胞模型后,检测其对TMZ化疗耐受性的变化,并探讨miR-181b对于恶性脑胶质瘤(GBM)辅助化学治疗的意义.方法 通过miR-181b慢病毒表达载体转染U87胶质瘤干细胞,提高miR-181b在U87胶质瘤干细胞中的表达.进一步通过RT-PCR、二次神经球形成实验、琼脂糖集落形成实验、MTT实验来分析miR-181b对于U87胶质瘤干细胞在TMZ化疗耐受性方面的作用.结果 miR-181b慢病毒表达载体转染U87胶质瘤干细胞后,U87胶质瘤干细胞中的miR-181b明显上调,而且U87胶质瘤干细胞的生长受到明显抑制;miR-181b可以加强TMZ抑制U87胶质瘤干细胞的生长的作用.结论 miR-181b

  13. Metallated metal-organic frameworks

    Energy Technology Data Exchange (ETDEWEB)

    Bury, Wojciech; Farha, Omar K.; Hupp, Joseph T.; Mondloch, Joseph E.


    Porous metal-organic frameworks (MOFs) and metallated porous MOFs are provided. Also provided are methods of metallating porous MOFs using atomic layer deposition and methods of using the metallated MOFs as catalysts and in remediation applications.

  14. Differential response of marine organisms to certain metal and agrichemical pollutants

    Energy Technology Data Exchange (ETDEWEB)

    Lee, H.H.; Xu, C.H.


    Oocyte maturation of the starfish, fertilization and embryogenesis of sea urchins, and the development of amphioxus and brine shrimps were used to assay the effects of several common metals and agrichemicals frequently found in marine environments. While brine shrimp embryos were tolerant to metals and agrichemicals used here, sea urchins and amphioxus showed a differential response to the common metal pollutants. Starfish oocyte maturation process was affected by agrichemicals. The results show that no one single organism, or its embryonic form, or a particular stage of development, can be used as the indicator for a particular pollutant. However, the use of lower forms of marine organisms can be useful collectively for environmental investigations and the management of waste disposal.

  15. Fault Tolerant Computer Architecture

    CERN Document Server

    Sorin, Daniel


    For many years, most computer architects have pursued one primary goal: performance. Architects have translated the ever-increasing abundance of ever-faster transistors provided by Moore's law into remarkable increases in performance. Recently, however, the bounty provided by Moore's law has been accompanied by several challenges that have arisen as devices have become smaller, including a decrease in dependability due to physical faults. In this book, we focus on the dependability challenge and the fault tolerance solutions that architects are developing to overcome it. The two main purposes

  16. Toleration, Synthesis or Replacement?

    DEFF Research Database (Denmark)

    Holtermann, Jakob v. H.; Madsen, Mikael Rask


    , in order to answer is not yet another partisan suggestion, but rather an attempt at making intelligible both the oppositions and the possibilities of synthesis between normative and empirical approaches to law. Based on our assessment and rational reconstruction of current arguments and positions, we...... therefore outline a taxonomy consisting of the following three basic, ideal-types in terms of the epistemological understanding of the interface of law and empirical studies: toleration, synthesis and replacement. This tripartite model proves useful with a view to teasing out and better articulating......) thus ultimately contributes to the development of a genuine basic science-of-law....

  17. Quality assurances and tolerances

    Energy Technology Data Exchange (ETDEWEB)

    Kirschling, G.


    This book presents a comprehensive statistical solution to tolerance problems to be used as an alternative to the conventional arithmetic approach that is used for tolerancing. The book is a translation from an original text in German. The classificatio nof the book would be as a reference text for engineers who are working in the production and quality control fields, particularly in process control. Academics who are teaching such subjects as statistical process control of geometric dimensioning and tolerancing will also find the book useful.


    Isaković, Katarina; Smith, Stanley B.; Waksman, Byron H.


    Rats thymectomized and irradiated as adults were restored to immunologic reactivity by grafts of normal adult rat thymus and bone marrow. Reactivity of the delayed (cellular) type and formation of mercaptoethanol-sensitive (MES) and mercaptoethanol-resistant (MER) antibody returned within 3 weeks, while Arthus reactivity remained subnormal till 9 weeks after irradiation and grafting. When the thymus donor was tolerant to BGG, the recipient showed specific non-reactivity to this antigen 3 weeks and, to a much lesser extent, 6 weeks after grafting. This non-reactivity affected delayed responses and MER antibody. No effect was noted on Arthus reactivity and a slight effect on MES antibody. Controls showed that the non-reactivity was not due to transfer of free antigen at the time of grafting. It was concluded that different source organs are responsible for different immune functions and that specific immunologic tolerance may be induced within such an organ as the thymus. PMID:4159035

  19. Molecular approaches unravel the mechanism of acid soil tolerance in plants

    Institute of Scientific and Technical Information of China (English)

    Miao; Bian; Meixue; Zhou; Dongfa; Sun; Chengdao; Li


    Acid soil is a worldwide problem to plant production. Acid toxicity is mainly caused by a lack of essential nutrients in the soil and excessive toxic metals in the plant root zone. Of the toxic metals, aluminum(Al) is the most prevalent and most toxic. Plant species have evolved to variable levels of tolerance to aluminum enabling breeding of high Al-tolerant cultivars.Physiological and molecular approaches have revealed some mechanisms of Al toxicity in higher plants. Mechanisms of plant tolerance to Al stress include: 1) exclusion of Al from the root tips, and 2) absorbance, but tolerance of Al in root cells. Organic acid exudation to chelate Al is a feature shared by many higher plants. The future challenge for Al tolerance studies is the identification of novel tolerance mechanisms and the combination of different mechanisms to achieve higher tolerance. Molecular approaches have led to significant progress in explaining mechanisms and detection of genes responsible for Al tolerance.Gene-specific molecular markers offer better options for marker-assisted selection in breeding programs than linked marker strategies. This paper mainly focuses on recent progress in the use of molecular approaches in Al tolerance research.

  20. Ethnopoly promotes tolerance

    CERN Multimedia

    CERN Bulletin


    On Friday 23 April, 225 primary school children from the eight schools in Meyrin-Cointrin and their accompanying adults took part in a big game of Ethnopoly. Private individuals, associations, administrations, shopkeepers and CERN all opened their doors to them to talk about their countries, their customs and what they are doing to promote tolerance and integration.   The CERN stand set up at ForumMeyrin for the Ethnopoly game. Scurrying from one place to another, the 10 and 11 year olds were made aware of the rich cultural diversity of their commune, which is home to 130 different nationalities. Physicists and engineers from CERN took up residence in the Forum Meyrin for the day in order to talk to the children about the advantages of international collaboration, a subject dear to the Organization's heart. They welcomed around fifty children in the course of the day, conveying to them a message of tolerance: despite their differences, the 10,000 scientists and other members of the CERN...

  1. Genes That Mediate Arsenic and Heavy Metal Detoxification in Plants

    Energy Technology Data Exchange (ETDEWEB)

    Lee, David A.; Gong, Ji-Ming; Schroeder, Julian I.


    To gain insight into the mechanisms of arsenic tolerance in plants, we developed a genetic screen to isolate Arabidopsis thaliana mutants with altered tolerance to arsenic. We report here on the isolation of ars1, a novel mutant with significantly increased tolerance to arsenate. ars1 accumulates similar levels of arsenic as wild type plants, but ars1 tolerance does not appear to be phytochelatin or glutathione dependent. ars1 plants do have a higher rate of phosphate uptake than wild type plants and plants grown with an excess of phosphate show increased tolerance to arsenate. Traditional models of arsenate tolerance in plants are based on the suppression of phosphate uptake pathways and, consequently, the reduced uptake of arsenate. Our data suggest that arsenate tolerance in ars1 is due to a new mechanism mediated by increased phosphate uptake in ars1. Results exploring increased metal tolerance through engineered phytochelatin expression will also be discussed.

  2. Involvement of vacuolar sequestration and active transport in tolerance of Saccharomyces cerevisiae to hop iso-alpha-acids. (United States)

    Hazelwood, Lucie A; Walsh, Michael C; Pronk, Jack T; Daran, Jean-Marc


    The hop plant, Humulus lupulus L., has an exceptionally high content of secondary metabolites, the hop alpha-acids, which possess a range of beneficial properties, including antiseptic action. Studies performed on the mode of action of hop iso-alpha-acids have hitherto been restricted to lactic acid bacteria. The present study investigated molecular mechanisms of hop iso-alpha-acid resistance in the model eukaryote Saccharomyces cerevisiae. Growth inhibition occurred at concentrations of hop iso-alpha-acids that were an order of magnitude higher than those found with hop-tolerant prokaryotes. Chemostat-based transcriptome analysis and phenotype screening of the S. cerevisiae haploid gene deletion collection were used as complementary methods to screen for genes involved in hop iso-alpha-acid detoxification and tolerance. This screening and further analysis of deletion mutants confirmed that yeast tolerance to hop iso-alpha-acids involves three major processes, active proton pumping into the vacuole by the vacuolar-type ATPase to enable vacuolar sequestration of iso-alpha-acids and alteration of cell wall structure and, to a lesser extent, active export of iso-alpha-acids across the plasma membrane. Furthermore, iso-alpha-acids were shown to affect cellular metal homeostasis by acting as strong zinc and iron chelators.

  3. Immunology of metal allergies. (United States)

    Schmidt, Marc; Goebeler, Matthias


    Allergic contact hypersensitivity to metal allergens is a common health concern worldwide, greatly impacting affected individuals with regard to both quality of life and their ability to work. With an estimated 15-20 % of the Western population hypersensitive to at least one metal allergen, sensitization rates for metallic haptens by far outnumber those reported for other common triggers of allergic contact dermatitis such as fragrances and rubber. Unfortunately, the prevalence of metal-induced hypersensitivity remains high despite extensive legislative efforts to ban/reduce the content of allergy-causing metals in recreational and occupational products. Recently, much progress has been made regarding the perception mechanisms underlying the inflammatory responses to this unique group of contact allergens. This review summarizes recent advances in our understanding of this enigmatic disease. Particular emphasis is put on the mechanisms of innate immune activation and T cell activation by common metal allergens such as nickel, cobalt, palladium, and chromate.

  4. Synthesis and structures of metal chalcogenide precursors (United States)

    Hepp, Aloysius F.; Duraj, Stan A.; Eckles, William E.; Andras, Maria T.


    The reactivity of early transition metal sandwich complexes with sulfur-rich molecules such as dithiocarboxylic acids was studied. Researchers recently initiated work on precursors to CuInSe2 and related chalcopyrite semiconductors. Th every high radiation tolerance and the high absorption coefficient of CuInSe2 makes this material extremely attractive for lightweight space solar cells. Their general approach in early transition metal chemistry, the reaction of low-valent metal complexes or metal powders with sulfur and selenium rich compounds, was extended to the synthesis of chalcopyrite precursors. Here, the researchers describe synthesis, structures, and and routes to single molecule precursors to metal chalcogenides.

  5. Mediating role of self-esteem in affective property and metal healthy of junior middle school students%自尊在初中生情感维度和心理健康的中介效应

    Institute of Scientific and Technical Information of China (English)

    阿拉坦巴根; 李敏; 戈兆娇; 刘丹; 孙文恒; 孙文博


    目的 探索自尊在情感维度与心理健康关系中的中介效应,进而寻找提升初中生心理健康水平的有效途径.方法 采用积极情感和消极情感量表、中国中学生心理健康量表、自尊量表对内蒙古某中学300名初中生进行分层随机抽样调查.利用SPSS 17.0进行数据处理.结果 ①心理健康水平总均分为2.152>2分,各维度因子分显示,被试依次比较容易受到的学习压力、情感不稳定、强迫、焦虑、人际关系敏感几个问题困扰.②心理健康各因子及总均分与自尊、正性情感呈负相关(r=-0.498~-0.314,P<0.05),与负性情感呈正相关(r=0.291~0.520,P<0.05).自尊与正性情感呈正相关(r=0.337,P<0.05),与负性情感相关性差异无统计学意义.③正性情感、自尊对心理健康总均分具有负向预测作用R 2=0.223,负性情感对心理健康总均分具有正向预测作用R 2=0.350.④正性情感对心理健康影响中自尊的中介效应量为ab/c'=0.118,负性情感对心理健康影响不存在调节效应.结论 情感维度中正性情感以自尊为中介,对初中生的心理健康水平具有预测作用.%Objective To explore the mediating role of self-esteem between affective property and metal healthy,and then search effective way to ascent juniors' metal healthy lever.Methods 300 juniors were chosen and received PANAS,MSSMHS and SES assessment.Results ①In sequence,study stress,lability of affect,obsession,anxiety and sensitive of interpersonal relationship produced effect on juniors.②There was a significant negative correlation (r=-0.498~-0.314,P<0.05)between mental health and self-esteem,positive emotions.There was a significant positive correlation(r=0.291~ 0.520,P< 0.05) between mental health and negative emotions.There was a significant positive correlation(r=0.337,P<0.05)between self-esteem and positive emotions.③The degree of self-esteem and positive emotions had an obvious negatively

  6. Affect Regulation

    DEFF Research Database (Denmark)

    Pedersen, Signe Holm; Poulsen, Stig Bernt; Lunn, Susanne


    Gergely and colleagues’ state that their Social Biofeedback Theory of Parental Affect Mirroring” can be seen as a kind of operationalization of the classical psychoanalytic concepts of holding, containing and mirroring. This article examines to what extent the social biofeedback theory of parenta...

  7. Swellable, water- and acid-tolerant polymer sponges for chemoselective carbon dioxide capture. (United States)

    Woodward, Robert T; Stevens, Lee A; Dawson, Robert; Vijayaraghavan, Meera; Hasell, Tom; Silverwood, Ian P; Ewing, Andrew V; Ratvijitvech, Thanchanok; Exley, Jason D; Chong, Samantha Y; Blanc, Frédéric; Adams, Dave J; Kazarian, Sergei G; Snape, Colin E; Drage, Trevor C; Cooper, Andrew I


    To impact carbon emissions, new materials for carbon capture must be inexpensive, robust, and able to adsorb CO2 specifically from a mixture of other gases. In particular, materials must be tolerant to the water vapor and to the acidic impurities that are present in gas streams produced by using fossil fuels to generate electricity. We show that a porous organic polymer has excellent CO2 capacity and high CO2 selectivity under conditions relevant to precombustion CO2 capture. Unlike polar adsorbents, such as zeolite 13x and the metal-organic framework, HKUST-1, the CO2 adsorption capacity for the hydrophobic polymer is hardly affected by the adsorption of water vapor. The polymer is even stable to boiling in concentrated acid for extended periods, a property that is matched by few microporous adsorbents. The polymer adsorbs CO2 in a different way from rigid materials by physical swelling, much as a sponge adsorbs water. This gives rise to a higher CO2 capacities and much better CO2 selectivity than for other water-tolerant, nonswellable frameworks, such as activated carbon and ZIF-8. The polymer has superior function as a selective gas adsorbent, even though its constituent monomers are very simple organic feedstocks, as would be required for materials preparation on the large industrial scales required for carbon capture.

  8. Manufacturing tolerant topology optimization

    DEFF Research Database (Denmark)

    Sigmund, Ole


    In this paper we present an extension of the topology optimization method to include uncertainties during the fabrication of macro, micro and nano structures. More specifically, we consider devices that are manufactured using processes which may result in (uniformly) too thin (eroded) or too thick...... (dilated) structures compared to the intended topology. Examples are MEMS devices manufactured using etching processes, nano-devices manufactured using e-beam lithography or laser micro-machining and macro structures manufactured using milling processes. In the suggested robust topology optimization...... that the method provides manufacturing tolerant designs with little decrease in performance. As a positive side effect the robust design formulation also eliminates the longstanding problem of one-node connected hinges in compliant mechanism design using topology optimization....

  9. Salt Tolerance in Soybean

    Institute of Scientific and Technical Information of China (English)

    Tsui-Hung Phang; Guihua Shao; Hon-Ming Lam


    Soybean is an Important cash crop and its productivity is significantly hampered by salt stress. High salt Imposes negative impacts on growth, nodulation, agronomy traits, seed quality and quantity, and thus reduces the yield of soybean. To cope with salt stress, soybean has developed several tolerance mechanisms, including: (I) maintenance of ion homeostasis; (ii) adjustment in response to osmotic stress; (iii) restoration of osmotic balance; and (iv) other metabolic and structural adaptations. The regulatory network for abiotic stress responses in higher plants has been studied extensively in model plants such as Arabidopsis thaliana. Some homologous components involved in salt stress responses have been identified in soybean. In this review, we tried to integrate the relevant works on soybean and proposes a working model to descdbe Its salt stress responses at the molecular level.

  10. Toleration, Synthesis or Replacement?

    DEFF Research Database (Denmark)

    Holtermann, Jakob v. H.; Madsen, Mikael Rask


    to have considerable problems keeping a clear focus on the key question: What are the implications of this empirical turn in terms of philosophy of legal science, of the social understanding of IL, and, not least, of the place of doctrinal scholarship after the alleged Wende? What is needed, we argue......, in order to answer is not yet another partisan suggestion, but rather an attempt at making intelligible both the oppositions and the possibilities of synthesis between normative and empirical approaches to law. Based on our assessment and rational reconstruction of current arguments and positions, we...... therefore outline a taxonomy consisting of the following three basic, ideal-types in terms of the epistemological understanding of the interface of law and empirical studies: toleration, synthesis and replacement. This tripartite model proves useful with a view to teasing out and better articulating...

  11. Glucose tolerance test - non-pregnant (United States)

    Oral glucose tolerance test - non-pregnant; OGTT - non-pregnant; Diabetes - glucose tolerance test; Diabetic - glucose tolerance test ... The most common glucose tolerance test is the oral glucose tolerance ... Before the test begins, a sample of blood will be taken. You ...

  12. A Multirelational Account of Toleration

    DEFF Research Database (Denmark)

    Ferretti, Maria Paola; Lægaard, Sune


    as wholes, rather than as sets of isolated relations. We explain this by showing how certain cases of toleration are multi-dimensional and how the descriptive concept of toleration might be understood intersectionally. We exemplify this by drawing on case studies of mosque controversies in Germany...

  13. Legal Quality, Inequality, and Tolerance

    DEFF Research Database (Denmark)

    Bjørnskov, Christian

    Previous findings suggest that income inequality leads to lower legal quality. This paper argues that voters' tolerance of inequality exerts an additional influence. Empirical findings suggest that inequality leads to lower legal quality due to its effect on trust while the tolerance of inequalit......, proxied by the political ideology of the median voter, exerts an independent influence....

  14. Legal Quality, Inequality, and Tolerance

    DEFF Research Database (Denmark)

    Bjørnskov, Christian


    Previous findings suggest that income inequality leads to lower legal quality. This paper argues that voters' tolerance of inequality exerts an additional influence. Empirical findings suggest that inequality leads to lower legal quality due to its effect on trust while the tolerance of inequalit......, proxied by the political ideology of the median voter, exerts an independent influence....

  15. Phased Array Detection and Tolerance Analysis on the Base Metal Interlayer of Pressure Equipment in the Hydrogen Environment%临氢承压设备母材夹层的相控阵检测及容限分析

    Institute of Scientific and Technical Information of China (English)

    李修能; 路笃辉; 姜海一; 陈彦泽; 吴远建; 孙小华


    When the pressure equipment runs in the hydrogen and wet hydrogen sulifde environment, it’s easy to form interlayer lfaws which will directly affect the quality and safety of pressure equipment. To ifnd a new useful testing method solving this problem, we used Phased Array Ultrasonic Testing (PAUT) to detect an interlayer lfaw and brielfy analyzed it. At the same time, according to the API 579—2007, Allowable Limit Analysis is used to analyze the surrounding hydrogen blistering of the interlayer lfaw to assess the security of continued using.%当钢制承压设备在临氢以及湿硫化氢环境下运行时,很容易形成夹层缺陷,直接影响到承压设备的质量和安全,带来严重的后果。本文利用相控阵检测技术(PAUT)对夹层缺陷进行了检测,并对检测结果进行简要分析,以期为夹层缺陷检测提供另一种可行的检测方法。同时,依据API 579—2007对夹层缺陷的周围的氢鼓泡进行容限分析,以评估承压设备继续使用的安全性。

  16. High Chromium Tolerant Bacterial Strains from Palar River Basin: Impact of Tannery Pollution

    Directory of Open Access Journals (Sweden)

    K. Sundar


    Full Text Available The basic survey study on tanneries and its pollution in the Palar river basin of Vellore District showed that it has been contaminated with heavy metals especially chromium and salts. This study is to improve our understanding to find the Cr contamination level and the ecology of heavy metal tolerance of the native bacterial flora of our study area. Chromium tolerant strains were isolated from contaminated sediments, water and effluents of various tanneries. The minimum and maximum concentration of chromium sediments was in the range of 47.4 and 682.4 mg/L, with an average of 306.285 mg/L in the study area. Sixty-eight chromium resistant bacterial strains were isolated and Maximum Tolerance Concentration (MTC studies have indicated that the tolerance concentrations of the isolates were in the range of 100-3300 mg/L. These bacterial isolates were also checked for their resistance to other heavy metals like Ni, Pb, Zn, Fe and Cd. Eighty percent of the isolates showed resistance to Ni, Pb, Zn, Fe at 100 ppm level and 45% had shown resistance to Cd. The isolates also had shown tolerance to salt (NaCl up to 9%. Significant note was found in the concentration of chromium and in the chromium tolerance ability of the bacteria in the study area and these chromium tolerance bacteria can be used as the indicator for the Cr contamination.

  17. Mechanical Data for Use in Damage Tolerance Analyses (United States)

    Forth, Scott C.; James, Mark A.; Newman, John A.; Everett, Richard A., Jr.; Johnston, William M., Jr.


    This report describes the results of a research program to determine the damage tolerance properties of metallic propeller materials. Three alloys were selected for investigation: 2025-T6 Aluminum, D6AC Steel and 4340 Steel. Mechanical response, fatigue (S-N) and fatigue crack growth rate data are presented for all of the alloys. The main conclusions that can be drawn from this study are as follows. The damage tolerant design of a propeller system will require a complete understanding of the fatigue crack growth threshold. There exists no experimental procedure to reliably develop the fatigue crack growth threshold data that is needed for damage tolerant design methods. Significant research will be required to fully understand the fatigue crack growth threshold. The development of alternative precracking methods, evaluating the effect of specimen configuration and attempting to identify micromechanical issues are simply the first steps to understanding the mechanics of the threshold.

  18. Affective Networks

    Directory of Open Access Journals (Sweden)

    Jodi Dean


    Full Text Available This article sets out the idea of affective networks as a constitutive feature of communicative capitalism. It explores the circulation of intensities in contemporary information and communication networks, arguing that this circulation should be theorized in terms of the psychoanalytic notion of the drive. The article includes critical engagements with theorists such as Guy Debord, Jacques Lacan, Tiziana Terranova, and Slavoj Zizek.

  19. Evaluation of Chlorophyll Content and Fluorescence Parameters as Indicators of Drought Tolerance in Barley

    Institute of Scientific and Technical Information of China (English)

    LI Rong-hua; GUO Pei-guo; Michael Baum; Stefania Grando; Salvatore Ceccarelli


    Drought is a major abiotic stress that severely affects food production worldwide. Agronomic and physiological traits associated with drought tolerance are suitable indicators for selection of drought tolerance genotypes to reduce the impact of water deficit on crop yield in breeding program. The objective of this study was to identify indicators related to drought tolerance through analysis of photosynthetic traits in barley (Hordeum vulgare L.). These traits included chlorophyll content, initial fluorescence (Fo), maximum primary yield of photochemistry of pho tosystem Ⅱ (Fv / Fo) and maximum quantum yield of photosystem Ⅱ (Fv/Fm). Four genotypes (Tadmor, Arta, Morocco9-75 and WI2291) variable in drought tolerance were used to investigate the correlation between these traits and drought tolerance. The results reflected that all of these traits were affected negatively in the four genotypes at different levels of post-anthesis drought stress, but the decrease in drought tolerant genotypes was much less than that of drought sensitive genotypes. The results further revealed that the components of the photosynthetic apparatus could be damaged significantly in drought sensitive genotypes, while drought tolerant genotypes were relatively less affected. On the other hand, the values of chlorophyll content, Fo, Fv/Fo and Fv/Fm in drought tolerance genotypes were significantly higher than those in drought sensitive genotypes under drought stress. It was concluded that chlorophyll content, Fo, Fv / Fo and Fv / Fm could be considered as reliable indicators in screening barley germplasm for drought tolerance.

  20. Effect of heavy metals on soil fungi (United States)

    Sosak-Świderska, Bożena


    Fungi constitute a high proportion of the microbial biomass in soil.Being widespread in soil their large surface-to-volume ratio and high metabolic activity, fungi can contribute significantly to heavy metal dynamics in soil. At neutral pH heavy metals in soils tend to be immobilized to precipitation and/or absorption to cation exchange sites of clay minerals. In the acidic soils, metals are more mobile and enter food webs easier. Microbial production of acids and chelating agents can mobilize to toxic metals. Mobilization is often by uptake and intracellular accumulation of the heavy metlas, and in this way, the bioavailability of metals towards other organisms can be more reduced. Fungi were isolated from soils from Upper Silesia in Poland and belonged to widespread genera: Aspergillus, Cladosporium, Penicillium and Trichoderma. Fungi from different taxonomic groups differ greatly in their tolerance to heavy metals. This could be related to their wall structure and chemistry as well as biochemical and physiological characteristics of fungi. Localization of metals in fungal cells was studied using electron microscopy analysis. Metal biosorption in the cell wall can be complex as melanin granules. Fungal vacuoles have an important role in the regulation of the cytosolic concentration of metal ions, and may contribute to heavy metal tolerance.In polluted soils with heavy metals, fungal species composition can be changed and their physiological activity can be changed, too.

  1. Peroxotitanates for Biodelivery of Metals

    Energy Technology Data Exchange (ETDEWEB)

    Hobbs, David; Elvington, M.


    Metal-based drugs are largely undeveloped in pharmacology. One limiting factor is the systemic toxicity of metal-based compounds. A solid-phase, sequestratable delivery agent for local delivery of metals could reduce systemic toxicity, facilitating new drug development in this nascent area. Amorphous peroxotitanates (APT) are ion exchange materials with high affinity for several heavy metal ions, and have been proposed to deliver or sequester metal ions in biological contexts. In the current study, we tested a hypothesis that APT are able to deliver metals or metal compounds to cells. We exposed fibroblasts (L929) or monocytes (THP1) to metal-APT materials for 72 h in vitro, then measured cellular mitochondrial activity (SDH-MTT method) to assess the biological impact of the metal-APT materials vs. metals or APT alone. APT alone did not significantly affect cellular mitochondrial activity, but all metal-APT materials suppressed the mitochondrial activity of fibroblasts (by 30-65% of controls). The concentration of metal-APT materials required to suppress cellular mitochondrial activity was below that required for metals alone, suggesting that simple extracellular release of the metals from the metal-APT materials was not the primary mechanism of mitochondrial suppression. In contrast to fibroblasts, no metal-APT material had a measurable effect on THP1 monocyte mitochondrial activity, despite potent suppression by metals alone. This latter result suggested that 'biodelivery' by metal-APT materials may be cell type-specific. Therefore, it appears that APT are plausible solid phase delivery agents of metals or metal compounds to some types of cells for potential therapeutic effect.

  2. General tolerances -- Part 2: Geometrical tolerances for features without individual tolerance indications

    CERN Document Server

    International Organization for Standardization. Geneva


    This part is intended to simplify drawing indications and specifies general tolerances in three tolerance classes. It mainly applies to features which are produced by removal of material. It contains tour tables and an informative annex A with regard to concepts behind general tolerancing of dimensions, as well as an informative annex B with further information.


    Institute of Scientific and Technical Information of China (English)


    Research situation of concurrent tolerance design has been analyzed. As fuzzy factors are objective and unavoidable in concurrent tolerance design, fuzzy optimization theory is applied in the design. A new mathematical model of concurrent tolerance design is constructed.

  4. 76 FR 33184 - Tetrachlorvinphos; Proposed Extension of Time-Limited Interim Pesticide Tolerances (United States)


    ... studies to modify 5 existing livestock tolerances (fat of cattle, hogs and poultry as well as eggs and milk fat) and establish 11 tolerances for additional tissues of cattle, hogs and poultry (such as meat.... Other types of entities not listed in this unit could also be affected. The North American...

  5. Impaired Glucose Tolerance in Healthy Men Treated with St. John's Wort

    DEFF Research Database (Denmark)

    Stage, Tore Bjerregaard; Damkier, Per; Christensen, Mette Marie Hougaard


    The purpose of this study was to examine if the over-the-counter herbal medicinal plant St. John's wort affects glucose tolerance in healthy men. To do this, we included 10 healthy men who were examined by a 2-hr oral glucose tolerance test on three occasions; A: Baseline, B: After 21 days...

  6. St. John's wort impairs glucose tolerance by reducing insulin response in healthy men

    DEFF Research Database (Denmark)

    Stage, Tore Bjerregaard; Damkier, Per; Christensen, Mette Marie Hougaard


    The purpose of this study was to examine if the over-the-counter herbal medicinal plant St. John's wort affects glucose tolerance in healthy men. To do this, we included 10 healthy men who were examined by a 2-hr oral glucose tolerance test on three occasions; A: Baseline, B: After 21 days...

  7. Extreme Environment Ceramic-to-Metal Seal Project (United States)

    National Aeronautics and Space Administration — The proposed Phase 1 program will demonstrate the feasibility of large ceramic to metal joints/seals that can tolerate extreme environments. The immediate...

  8. From immunosuppression to tolerance. (United States)

    Adams, David H; Sanchez-Fueyo, Alberto; Samuel, Didier


    The past three decades have seen liver transplantation becoming a major therapeutic approach in the management of end-stage liver diseases. This is due to the dramatic improvement in survival after liver transplantation as a consequence of the improvement of surgical and anaesthetic techniques, of post-transplant medico-surgical management and of prevention of disease recurrence and other post-transplant complications. Improved use of post-transplant immunosuppression to prevent acute and chronic rejection is a major factor in these improved results. The liver has been shown to be more tolerogenic than other organs, and matching of donor and recipients is mainly limited to ABO blood group compatibility. However, long-term immunosuppression is required to avoid severe acute and chronic rejection and graft loss. With the current immunosuppression protocols, the risk of acute rejection requiring additional therapy is 10-40% and the risk of chronic rejection is below 5%. However, the development of histological lesions in the graft in long-term survivors suggest atypical forms of graft rejection may develop as a consequence of under-immunosuppression. The backbone of immunosuppression remains calcineurin inhibitors (CNI) mostly in association with steroids in the short-term and mycophenolate mofetil or mTOR inhibitors (everolimus). The occurrence of post-transplant complications related to the immunosuppressive therapy has led to the development of new protocols aimed at protecting renal function and preventing the development of de novo cancer and of dysmetabolic syndrome. However, there is no new class of immunosuppressive drugs in the pipeline able to replace current protocols in the near future. The aim of a full immune tolerance of the graft is rarely achieved since only 20% of selected patients can be weaned successfully off immunosuppression. In the future, immunosuppression will probably be more case oriented aiming to protect the graft from rejection and at

  9. Molecular Characterization of Aluminium (aluminum) Tolerance in Rye (United States)

    Aluminium (Al) toxicity, affecting around half of the world’s arable land, severely hinders the ability of crop plants to utilize moisture and nutrients by restricting root growth and function. Among the cultivated cereals, rye is the most Al-tolerant and represents an important potential source of ...

  10. Trait-based Affective Processes in Alcohol-Involved Risk Behaviors


    Wray, Tyler B.; Simons, Jeffrey S.; Dvorak, Robert D.; Gaher, Raluca M.


    This study tested a theoretical model of alcohol use, markers of extreme intoxication, and risk behavior as a function of trait affect, distress tolerance, and affect-based behavior dysregulation. Positive affective pathways to risk behavior were primarily expected to be indirect via high levels of alcohol use, while negative affect paths were expected to be more directly associated with engagement in risk behavior. In addition, we expected trait affectivity and distress tolerance would prima...

  11. Manufacturing tolerant topology optimization

    Institute of Scientific and Technical Information of China (English)

    Ole Sigmund


    In this paper we present an extension of the topology optimization method to include uncertainties during the fabrication of macro, micro and nano structures. More specifically, we consider devices that are manufactured using processes which may result in (uniformly) too thin (eroded)or too thick (dilated) structures compared to the intended topology. Examples are MEMS devices manufactured using etching processes, nano-devices manufactured using e-beam lithography or laser micro-machining and macro structures manufactured using milling processes. In the suggested robust topology optimization approach, under- and over-etching is modelled by image processing-based "erode" and "dilate" operators and the optimization problem is formulated as a worst case design problem. Applications of the method to the design of macro structures for minimum compliance and micro compliant mechanisms show that the method provides manufacturing tolerant designs with little decrease in performance. As a positive side effect the robust design formulation also eliminates the longstanding problem of one-node connected hinges in compliant mechanism design using topology optimization.

  12. Comparing salt tolerance of beet cultivars and their halophytic ancestor: consequences of domestication and breeding programmes. (United States)

    Rozema, Jelte; Cornelisse, Danny; Zhang, Yuancheng; Li, Hongxiu; Bruning, Bas; Katschnig, Diana; Broekman, Rob; Ji, Bin; van Bodegom, Peter


    Salt tolerance of higher plants is determined by a complex set of traits, the timing and rate of evolution of which are largely unknown. We compared the salt tolerance of cultivars of sugar beet and their ancestor, sea beet, in hydroponic studies and evaluated whether traditional domestication and more recent breeding have changed salt tolerance of the cultivars relative to their ancestor. Our comparison of salt tolerance of crop cultivars is based on values of the relative growth rate (RGR) of the entire plant at various salinity levels. We found considerable salt tolerance of the sea beet and slightly, but significantly, reduced salt tolerance of the sugar beet cultivars. This indicates that traditional domestication by selection for morphological traits such as leaf size, beet shape and size, enhanced productivity, sugar content and palatability slightly affected salt tolerance of sugar beet cultivars. Salt tolerance among four sugar beet cultivars, three of which have been claimed to be salt tolerant, did not differ. We analysed the components of RGR to understand the mechanism of salt tolerance at the whole-plant level. The growth rate reduction at higher salinity was linked with reduced leaf area at the whole-plant level (leaf area ratio) and at the individual leaf level (specific leaf area). The leaf weight fraction was not affected by increased salinity. On the other hand, succulence and leaf thickness and the net assimilation per unit of leaf area (unit leaf rate) increased in response to salt treatment, thus partially counteracting reduced capture of light by lower leaf area. This compensatory mechanism may form part of the salt tolerance mechanism of sea beet and the four studied sugar beet cultivars. Together, our results indicate that domestication of the halophytic ancestor sea beet slightly reduced salt tolerance and that breeding for improved salt tolerance of sugar beet cultivars has not been effective.

  13. An Algebra of Fault Tolerance

    CERN Document Server

    Rao, Shrisha


    Every system of any significant size is created by composition from smaller sub-systems or components. It is thus fruitful to analyze the fault-tolerance of a system as a function of its composition. In this paper, two basic types of system composition are described, and an algebra to describe fault tolerance of composed systems is derived. The set of systems forms monoids under the two composition operators, and a semiring when both are concerned. A partial ordering relation between systems is used to compare their fault-tolerance behaviors.

  14. Submergence tolerance in Hordeum marinum

    DEFF Research Database (Denmark)

    Pedersen, Ole; Malik, Al I.; Colmer, Timothy D.


    . All three accessions tolerated complete submergence, but only when in CO(2) enriched floodwater. Plants submerged for 7 days in water at air equilibrium (18 mM CO(2)) suffered loss of biomass, whereas those with 200 mM CO(2) continued to grow. Higher underwater net photosynthesis at 200 mM CO(2......) movement, would all contribute to submergence tolerance in H. marinum. The present study demonstrates that dissolved CO(2) levels can determine submergence tolerance of terrestrial plants. So, submergence experiments should be conducted with defined CO(2) concentrations and enrichment might be needed...

  15. Therapeutic effect and safety of bare metal stent in patients with coronary heart disease complicated im-paired glucose tolerance%冠心病合并糖耐量受损患者应用金属裸支架的疗效及安全性

    Institute of Scientific and Technical Information of China (English)

    王德伟; 黄洁; 杨海英


    Objective:To analyze the clinical therapeutic effect and safety of bare metal stent (BMS)application in patients with coronary heart disease (CHD)complicated impaired glucose tolerance (IGT).Methods:The data of 68 CHD + IGT patients undergoing stent implantation in our hospital were retrospectively analyzed.According to kind of implanted stents,they were divided into BMS group (n=36)and drug eluting stent (DES)group (n=32). Thrombolysis in myocardial infarction (TIMI)flow grade and Gensini score of coronary lesion were compared be-tween two groups via reviewing coronary angiography six months after operation.Incidence rates of re-stenosis,a-cute thrombosis,sub-acute thrombosis,revascularization and sudden death were compared between two groups after one year follow-up.Results:There were no significant difference in TIMI grade and Gensini score of coronary le-sion between two groups after operation (P>0.05).Compared with DES group after one-year follow-up,there were significant reductions in incidence rates of acute thrombosis (6.25% vs. 2.78%), sub-acute thrombosis (15.63% vs.5.56%)and sudden death (6.25% vs.2.78%)in BMS group (P0.05).Conclusion:Application of bare metal stent can reduce incidence rate of postoperative complications and possess better therapeu-tic effect in patients with coronary heart disease complicated impaired glucose tolerance.%目的:在冠心病(CHD)合并糖耐量受损患者应用金属裸支架的疗效及安全性。方法:回顾性分析68例CHD合并糖耐量受损患者在我院行支架植入术的资料,依据植入支架种类分为:金属裸支架(BMS)组(36例),药物涂层支架(DES)组(32例)。术后6月复查冠脉造影,比较两组的心肌梗死溶栓治疗(TIMI)临床试验血流分级及 Gensini冠脉病变积分的差异。随访1年,比较两组患者再狭窄发生率、急性血栓形成、亚急性血栓形成、血运重建率及猝死率等并发症的差异。

  16. [Affective dependency]. (United States)

    Scantamburlo, G; Pitchot, W; Ansseau, M


    Affective dependency is characterized by emotional distress (insecure attachment) and dependency to another person with a low self-esteem and reassurance need. The paper proposes a reflection on the definition of emotional dependency and the confusion caused by various denominations. Overprotective and authoritarian parenting, cultural and socio-environmental factors may contribute to the development of dependent personality. Psychological epigenetic factors, such as early socio-emotional trauma could on neuronal circuits in prefronto-limbic regions that are essential for emotional behaviour.We also focus on the interrelations between dependent personality, domestic violence and addictions. The objective for the clinician is to propose a restoration of self-esteem and therapeutic strategies focused on autonomy.

  17. [Tolerance of ambiguity, art therapy and psychiatric illness]. (United States)

    Grube, Michael


    Tolerance of ambiguity means the ability to tolerate contradictory and incalculable informations. There is the hypothesis that a high degree of tolerance of ambiguity correlates with creativity. It is unclear how various psychiatric illnesses and psychopathological conditions affect tolerance of ambiguity. Therefore we carried out a study concerning the tolerance of ambiguity: 154 persons were systematically investigated with a standardized questionnaire (31 schizophrenic in-patients, 41 neurotic in-patients, 49 members of the staff as control group, 33 artists as control group). In addition we examined the degree of depression in the neurotic group, the anancasm score and the well-being in general. In the schizophrenic group we assessed psychotic symptoms, the positive and negative symptoms, medication, anancasm and depression. Tolerance of ambiguity decreased in the following sequence: artists - members of the staff - neurotic in-patients - schizophrenic in-patients. It became evident that in the schizophrenic group negative symptoms negatively correlates with tolerance of ambiguity. The results seem to confirm the hypothesis that there is a positive correlation between tolerance of ambiguity and creativity. In addition, the higher degree of intolerance of ambiguity in schizophrenic patients may represent a protective mechanism. Intolerance of ambiguity possibly protects from too many contradictory informations. Furthermore the necessity is confirmed that creative therapy methods should be carefully chosen to avoid irritation on the one hand and not to neglect the required training of creative basic functions on the other hand. Although our results weaken the thesis that psychiatric illness is generally associated with an increase of creativity they don't exclude that highly creative performances in some individuals are possible who are especially talented in spite of or even because of their emotional suffering.

  18. The effects of a hatha yoga intervention on facets of distress tolerance

    NARCIS (Netherlands)

    Medina, J.L.; Hopkins, L.B.; Powers, M.B.; Baird, S.O.; Smits, J.A.J.


    Individuals with low distress tolerance (DT) experience negative emotion as particularly threatening and are highly motivated to reduce or avoid such affective experiences. Consequently, these individuals have difficulty regulating emotions and tend to engage in maladaptive strategies, such as overe

  19. Accident tolerant fuel analysis

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Curtis [Idaho National Laboratory; Chichester, Heather [Idaho National Laboratory; Johns, Jesse [Texas A& M University; Teague, Melissa [Idaho National Laboratory; Tonks, Michael Idaho National Laboratory; Youngblood, Robert [Idaho National Laboratory


    Safety is central to the design, licensing, operation, and economics of Nuclear Power Plants (NPPs). Consequently, the ability to better characterize and quantify safety margin holds the key to improved decision making about light water reactor design, operation, and plant life extension. A systematic approach to characterization of safety margins and the subsequent margins management options represents a vital input to the licensee and regulatory analysis and decision making that will be involved. The purpose of the Risk Informed Safety Margin Characterization (RISMC) Pathway research and development (R&D) is to support plant decisions for risk-informed margins management by improving economics and reliability, and sustaining safety, of current NPPs. Goals of the RISMC Pathway are twofold: (1) Develop and demonstrate a risk-assessment method coupled to safety margin quantification that can be used by NPP decision makers as part of their margin recovery strategies. (2) Create an advanced ''RISMC toolkit'' that enables more accurate representation of NPP safety margin. In order to carry out the R&D needed for the Pathway, the Idaho National Laboratory is performing a series of case studies that will explore methods- and tools-development issues, in addition to being of current interest in their own right. One such study is a comparative analysis of safety margins of plants using different fuel cladding types: specifically, a comparison between current-technology Zircaloy cladding and a notional ''accident-tolerant'' (e.g., SiC-based) cladding. The present report begins the process of applying capabilities that are still under development to the problem of assessing new fuel designs. The approach and lessons learned from this case study will be included in future Technical Basis Guides produced by the RISMC Pathway. These guides will be the mechanism for developing the specifications for RISMC tools and for defining how plant

  20. Radiation damage tolerant nanomaterials

    Directory of Open Access Journals (Sweden)

    I.J. Beyerlein


    Full Text Available Designing a material from the atomic level to achieve a tailored response in extreme conditions is a grand challenge in materials research. Nanostructured metals and composites provide a path to this goal because they contain interfaces that attract, absorb and annihilate point and line defects. These interfaces recover and control defects produced in materials subjected to extremes of displacement damage, impurity implantation, stress and temperature. Controlling radiation-induced-defects via interfaces is shown to be the key factor in reducing the damage and imparting stability in certain nanomaterials under conditions where bulk materials exhibit void swelling and/or embrittlement. We review the recovery of radiation-induced point defects at free surfaces and grain boundaries and stabilization of helium bubbles at interphase boundaries and present an approach for processing bulk nanocomposites containing interfaces that are stable under irradiation.

  1. Women’s G Tolerance (United States)


    for the groups matched by age (70 pairs), weight sickness, uncomfortable feelings of distension in arms (26 pairs), and act~vity status (84 pairs...mass-spring-damper) s ,stem Straining G tolerance, being dpendent on skeletal having a resonant frequency above about I Hz. As muscular strength and...of the women’s G tolerance stud\\ scclic variations in muscular strength and endurance. was below 0.1 Hz (11), the production of any significant

  2. Desiccation tolerance of somatic embryoids.


    Tetteroo, F.A.A.


    This thesis describes the research performed on the subject "Desiccation tolerance in somatic embryoids". Somatic embryoids are bipolar structures formed in tissue culture, with both a shoot and a root apex, which resemble very much zygotic embryos found in seeds. Through simultaneous development of root and shoot, these embryoids can grow out into complete plantlets.In Chapter 2 we describe an optimized method to produce completely desiccation tolerant carrot ( Daucus carota ) embryoids. Usi...

  3. Detoxification of multiple heavy metals by a half-molecule ABC transporter, HMT-1, and coelomocytes of Caenorhabditis elegans.

    Directory of Open Access Journals (Sweden)

    Marc S Schwartz

    Full Text Available BACKGROUND: Developing methods for protecting organisms in metal-polluted environments is contingent upon our understanding of cellular detoxification mechanisms. In this regard, half-molecule ATP-binding cassette (ABC transporters of the HMT-1 subfamily are required for cadmium (Cd detoxification. HMTs have conserved structural architecture that distinguishes them from other ABC transporters and allows the identification of homologs in genomes of different species including humans. We recently discovered that HMT-1 from the simple, unicellular organism, Schizosaccharomyces pombe, SpHMT1, acts independently of phytochelatin synthase (PCS and detoxifies Cd, but not other heavy metals. Whether HMTs from multicellular organisms confer tolerance only to Cd or also to other heavy metals is not known. METHODOLOGY/PRINCIPAL FINDINGS: Using molecular genetics approaches and functional in vivo assays we showed that HMT-1 from a multicellular organism, Caenorhabditis elegans, functions distinctly from its S. pombe counterpart in that in addition to Cd it confers tolerance to arsenic (As and copper (Cu while acting independently of pcs-1. Further investigation of hmt-1 and pcs-1 revealed that these genes are expressed in different cell types, supporting the notion that hmt-1 and pcs-1 operate in distinct detoxification pathways. Interestingly, pcs-1 and hmt-1 are co-expressed in highly endocytic C. elegans cells with unknown function, the coelomocytes. By analyzing heavy metal and oxidative stress sensitivities of the coelomocyte-deficient C. elegans strain we discovered that coelomocytes are essential mainly for detoxification of heavy metals, but not of oxidative stress, a by-product of heavy metal toxicity. CONCLUSIONS/SIGNIFICANCE: We established that HMT-1 from the multicellular organism confers tolerance to multiple heavy metals and is expressed in liver-like cells, the coelomocytes, as well as head neurons and intestinal cells, which are cell types

  4. Uninhibited biosynthesis and release of phytosiderophores in the presence of heavy metal (HM) favors HM remediation. (United States)

    Gupta, Chandan Kumar; Singh, Bhupinder


    Production of phytosiderophore (PS) has been causally related to iron-deficiency tolerance in cereals. However, PS can also chelate heavy metal and thus may represent a viable phytoextraction strategy on contaminated soils. Two separate experiments were conducted to assess the affect of heavy metal on phytosiderophore biosynthesis and their release in the rhizosphere of wheat. Root exudates were collected from 10-day-old wheat seedlings raised on Fe-deficient nutrient solution in the presence of 2.5, 5.0, and 10 mM concentration of different heavy metals (Cd, Pb, and Ni) for 3-day period, for the phytosiderophore and the heavy metal analysis. Plant uptake of respective heavy metal was positively correlated with the heavy metal concentration of the nutrient solution. Phytosiderophore release was positively influenced in the presence of the heavy metal. Increasing concentration of Cd, Pb, and Ni showed positive correlation with the PS release until 5 mM concentration followed by a decline at 10 mM. However, a higher induction of PS release was measured in wheat seedlings treated with Cd and Pb than Ni. Further, transcript expression analysis of nicotianamine synthase (NAS) and nicotianamine amino transferase (NAAT), involved in phytosiderophore biosynthesis, was done in roots of 10-day-old Fe-deficient wheat subjected to 2.5, 5.0, and 10 mM of Cd, Pb, and Ni. Both NAS and NAAT were expressed not only under Fe deficiency but also in the presence of Cd, Pb, and Ni. Sequencing of partial cDNA of NAS revealed a nucleotide length of 998 bp, while multiple sequence alignment of NAS with HvNAS revealed 92% sequence similarity. This study irrevocably shows that phytosiderophore biosynthesis and release are not impaired in the presence of heavy metal and that phytosiderophore mediates the uptake of toxic heavy metal.

  5. A novel heavy metal ATPase peptide from Prosopis juliflora is involved in metal uptake in yeast and tobacco. (United States)

    Keeran, Nisha S; Ganesan, G; Parida, Ajay K


    Heavy metal pollution of agricultural soils is one of the most severe ecological problems in the world. Prosopis juliflora, a phreatophytic tree species, grows well in heavy metal laden industrial sites and is known to accumulate heavy metals. Heavy Metal ATPases (HMAs) are ATP driven heavy metal pumps that translocate heavy metals across biological membranes thus helping the plant in heavy metal tolerance and phytoremediation. In the present study we have isolated and characterized a novel 28.9 kDa heavy metal ATPase peptide (PjHMT) from P. juliflora which shows high similarity to the C-terminal region of P1B ATPase HMA1. It also shows the absence of the invariant signature sequence DKTGT, and the metal binding CPX motif but the presence of conserved regions like MVGEGINDAPAL (ATP binding consensus sequence), HEGGTLLVCLNS (metal binding domain) and MLTGD, GEGIND and HEGG motifs which play important roles in metal transport or ATP binding. PjHMT, was found to be upregulated under cadmium and zinc stress. Heterologous expression of PjHMT in yeast showed a higher accumulation and tolerance of heavy metals in yeast. Further, transgenic tobacco plants constitutively expressing PjHMT also showed increased accumulation and tolerance to cadmium. Thus, this study suggests that the transport peptide from P. juliflora may have an important role in Cd uptake and thus in phytoremediation.

  6. Zn tolerance of novel Colocasia esculenta metallothionein and its domains in Escherichia coli and tobacco. (United States)

    Kim, Yeon-Ok; Lee, Yoon Gyo; Patel, Darshan H; Kim, Ho Myeong; Ahn, Sung-Ju; Bae, Hyeun-Jong


    Contrary to extensive researches on the roles of metallothioneins (MTs) in metal tolerance of animals, the roles of plant MTs in metal tolerance are largely under investigation. In this study, we evaluated the functional role of type 2 MT from Colocasia esculenta (CeMT2b) in Zn tolerance of tobacco and E. coli cells. Under Zn-stress conditions, transgenic tobacco overexpressing CeMT2b displayed much better seedling growth, a significant decrease in the levels of H(2)O(2) and an increase in Zn accumulation compared with the wild type. Overexpression of CeMT2b in E. coli greatly enhanced Zn tolerance and Zn accumulation under Zn stresses compared with control cells. CeMT2b bound 5.38 ± 0.29 atoms of Zn per protein. To identify a structural domain of CeMT2b for Zn binding, we investigated the growth of E. coli expressing each of the N-terminal, C-terminal, and central linker domains or a CNC motif deletion from the C-terminus of full-length CeMT2b. The results showed that the CNC motif is required for Zn tolerance, and the N-terminal domain is more effective in Zn tolerance than the C-terminal domain. Taken together, our results provide direct evidence for functional contributions of CeMT2b in Zn tolerance of tobacco and E. coli cells.

  7. 77 FR 45535 - Aldicarb; Proposed Tolerance Actions (United States)


    ...; FRL-9355-8] RIN 2070-ZA16 Aldicarb; Proposed Tolerance Actions AGENCY: Environmental Protection Agency (EPA). ACTION: Proposed rule. SUMMARY: EPA is proposing to revoke certain tolerances for the... specific tolerances and make minor revisions to the tolerance expression for aldicarb. DATES: Comments...

  8. 75 FR 17579 - Aminopyralid; Pesticide Tolerances (United States)


    ... Mexican MRLs have been established for corn commodities. C. Response to Comments EPA received comments... the tolerances and specify how compliance with the tolerances is to be measured. Plant tolerances are... expressed in terms of ``residues of the herbicide aminopyralid.'' The tolerance expression for plants...

  9. 75 FR 11799 - Fatigue Tolerance Evaluation of Metallic Structures (United States)


    ... strategy used to manage fatigue was limited to retirement of the rotorcraft part or component before the... report summarizing each substantive public contact with FAA personnel concerning this proposed...

  10. 76 FR 75435 - Fatigue Tolerance Evaluation of Metallic Structures (United States)


    ... Aviation Organization (ICAO) Standards and Recommended Practices to the maximum extent practicable. The FAA has reviewed the corresponding ICAO Standards and Recommended Practices and has identified...

  11. Enhancement of Radiation Tolerance by Interfaces in Nanostructured Metallic Materials (United States)


    a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. a...flexible construction of various types (coherent vs. incoherent) of interfaces as well as accurate control of the thickness of individual layers. Cu/Nb...Phillpot, H. Gleiter, Acta Materialia, 50 (2002) 5005-5020. [7] K. Lu, L. Lu, S. Suresh, Science, 324 (2009) 349-352. [8] S. Ogata , J. Li, S. Yip

  12. Mathematical model of cylindrical form tolerance

    Institute of Scientific and Technical Information of China (English)

    蔡敏; 杨将新; 吴昭同


    Tolerance is essential for integration of CAD and CAM. Unfortunately, the meaning of tolerances in the national standard is expressed in graphical and language forms and is not adaptable for expression, processing and data transferring with computers. How to interpret its semantics is becoming a focus of relevant studies. This work based on the mathematical definition of form tolerance in ANSI Y 14.5.1 M-1994, established the mathematical model of form tolerance for cylindrical feature. First, each tolerance in the national standard was established by vector equation. Then on the foundation of toler-ance's mathematical definition theory, each tolerance zone's mathematical model was established by inequality based on degrees of feature. At last the variance area of each tolerance zone is derived. This model can interpret the semantics of form tolerance exactly and completely.

  13. Copper and cadmium tolerance, uptake and effect on chloroplast ultrastructure. Studies on Salix purpurea and Phragmites australis

    Energy Technology Data Exchange (ETDEWEB)

    Hakmaoui, A.; Ater, A. [Abdelmalek Essaadi Univ., Tetouan (Morocco). Dept. of Biology; Boka, K. [Eoetvoes Lorand Univ., Budapest (Hungary). Dept. of Plant Anatomy; Baron, M. [Granada Univ. (Spain). Dept. of Biochemistry and Cell and Molecular Biology of Plants


    We have compared the effect of toxic Cu and Cd concentrations on growth, metal accumulation, and chloroplast ultrastructure of willow (Salix purpurea L.) and reed [Phragmites australis (Cav.) Trin. ex Steud.]. After a 10-day treatment, both species have tolerated to some extent the lowest concentration of both metals; however, plant growth was strongly reduced at the highest Cu and Cd concentrations. These plants could be described as Cu-tolerant at the lowest concentration tested, showing a higher tolerance index in reed than in willow; in contrast, willow exhibited higher tolerance against Cd. Both plants appeared to be moderate root accumulators of Cu and Cd. Ultrastructural studies revealed special features that can provide some protection against heavy metals stress, such as ferritin aggregates in the stroma. In addition, Cu and Cd induced distortion of thylakoids, reduction of grana stacks, as well as an increased number and size of plastoglobuli and peripheral vesicles. (orig.)

  14. How does the spin-state of Co ions affect the insulator-metal transition in Bi2A2Co2O8 (A = Ca, Sr, Ba)? (United States)

    Huang, Xiaokun; Zhang, Weiyi


    The misfit layered Bi2A2Co2O8 (A = Ca, Sr, Ba) compounds experience an insulator to metal transition as A’s ionic radius increases. This feature is contradictory to the conventional wisdom that larger lattice constant favors insulating rather than metallic state, and is also difficult to be reconciled using the Anderson weak localization theory. In this paper, we show from the first-principles calculation that an insulator-metal transition takes place from a nonmagnetic low-spin state of Co3+ ions to a hexagonally arranged intermediate-spin low-spin mixed-state in CoO2 plane when ionic radius increases from Ca to Ba. The predicted low-spin state of Bi2Ca2Co2O8 and Bi2Sr2Co2O8 and intermediate-spin low-spin mixed-state of Bi2Ba2Co2O8 are consistent not only with their measured transport properties, but also with the magnetic-field suppressed specific-heat peak observed at the transition temperature. In agreement with experiments, strong electronic correlation is required to stabilize the low-spin insulator and intermediate-spin low-spin metal.

  15. Role of the lipid peroxidation product, 4-hydroxynonenal, in the development of nitrate tolerance. (United States)

    D'Souza, Yohan; Kawamoto, Toshihiro; Bennett, Brian M


    Tolerance to nitrates such as nitroglycerin (GTN) is associated with oxidative stress, inactivation of aldehyde dehydrogenase 2 (ALDH2), and decreased GTN-induced cGMP accumulation and vasodilation. We hypothesized that GTN-induced inactivation of ALDH2 results in increased 4-hydroxy-2-nonenal (HNE) adduct formation of key proteins involved in GTN bioactivation, and, consequently, an attenuated vasodilator response to GTN (i.e., tolerance). We used an in vivo GTN tolerance model, a cell culture model of nitrate action, and Aldh2(-/-) mice to assess whether GTN exposure resulted in HNE adduct formation, and whether exogenous HNE affected GTN-induced relaxation and cGMP accumulation. Immunoblot analysis indicated a marked increase in HNE adduct formation in GTN-tolerant porcine kidney epithelial cells (PK1) and in aortae from GTN-tolerant rats and untreated Aldh2(-/-) mice. Preincubation of PK1 cells with HNE resulted in a dose-dependent decrease in GTN-induced cGMP accumulation, and pretreatment of isolated rat aorta with HNE resulted in dose-dependent decreases in the vasodilator response to GTN, thus mimicking GTN-tolerance. Pretreatment of aortae from Aldh2(-/-) mice with 10 μM HNE resulted in a desensitized vasodilator response to GTN. In the in vivo rat tolerance model, changes in HNE adduct formation correlated well with the onset of GTN tolerance and tolerance reversal. Furthermore, coadministration of an HNE scavenger during the tolerance induction protocol completely prevented HNE adduct formation and GTN tolerance but did not prevent the inactivation of ALDH2. The data are consistent with a novel mechanism of GTN tolerance suggesting a primary role of HNE adduct formation in the development of GTN tolerance.

  16. Copper Tolerance and Biosorption of Saccharomyces cerevisiae during Alcoholic Fermentation. (United States)

    Sun, Xiang-Yu; Zhao, Yu; Liu, Ling-Ling; Jia, Bo; Zhao, Fang; Huang, Wei-Dong; Zhan, Ji-Cheng


    At high levels, copper in grape mash can inhibit yeast activity and cause stuck fermentations. Wine yeast has limited tolerance of copper and can reduce copper levels in wine during fermentation. This study aimed to understand copper tolerance of wine yeast and establish the mechanism by which yeast decreases copper in the must during fermentation. Three strains of Saccharomyces cerevisiae (lab selected strain BH8 and industrial strains AWRI R2 and Freddo) and a simple model fermentation system containing 0 to 1.50 mM Cu2+ were used. ICP-AES determined Cu ion concentration in the must decreasing differently by strains and initial copper levels during fermentation. Fermentation performance was heavily inhibited under copper stress, paralleled a decrease in viable cell numbers. Strain BH8 showed higher copper-tolerance than strain AWRI R2 and higher adsorption than Freddo. Yeast cell surface depression and intracellular structure deformation after copper treatment were observed by scanning electron microscopy and transmission electron microscopy; electronic differential system detected higher surface Cu and no intracellular Cu on 1.50 mM copper treated yeast cells. It is most probably that surface adsorption dominated the biosorption process of Cu2+ for strain BH8, with saturation being accomplished in 24 h. This study demonstrated that Saccharomyces cerevisiae strain BH8 has good tolerance and adsorption of Cu, and reduces Cu2+ concentrations during fermentation in simple model system mainly through surface adsorption. The results indicate that the strain selected from China's stress-tolerant wine grape is copper tolerant and can reduce copper in must when fermenting in a copper rich simple model system, and provided information for studies on mechanisms of heavy metal stress.

  17. Isolation and Characterization of Four Gram-PositiveNickel-Tolerant Microorganisms from Contaminated Riparian Sediments

    Energy Technology Data Exchange (ETDEWEB)

    Van Nostrand, Joy D.; Khijniak, Tatiana V.; Gentry, Terry J.; Novak, Michelle T.; Sowder, Andrew G.; Zhou, Jizhong Z.; Bertsch, PaulM.; Morris, Pamela J.


    Microbial communities from riparian sediments contaminatedwith high levels of Ni and U were examined for metal-tolerantmicroorganisms. Isolation of four aerobic Ni-tolerant, Gram-positiveheterotrophic bacteria indicated selection pressure from Ni. Theseisolates were identified as Arthrobacter oxydans NR-1, Streptomycesgalbus NR-2, Streptomyces aureofaciens NR-3, and Kitasatosporacystarginea NR-4 based on partial 16S rDNA sequences. A functional genemicroarray containing gene probes for functions associated withbiogeochemical cycling, metal homeostasis, and organic contaminantdegradation showed little overlap among the four isolates. Fifteen of thegenes were detected in all four isolates with only two of these relatedto metal resistance, specifically to tellurium. Each of the four isolatesalso displayed resistance to at least one of six antibiotics tested, withresistance to kanamycin, gentamycin, and ciprofloxacin observed in atleast two of the isolates. Further characterization of S. aureofaciensNR-3 and K. cystarginea NR-4 demonstrated that both isolates expressed Nitolerance constitutively. In addition, both were able to grow in higherconcentrations of Ni at pH 6 as compared to pH 7 (42.6 and 8.5 mM Ni atpH 6 and 7, respectively). Tolerance to Cd, Co, and Zn was also examinedin these two isolates; a similar pH-dependent metal tolerance wasobserved when grown with Co and Zn. Neither isolate was tolerant to Cd.These findings suggest that Ni is exerting a selection pressure at thissite for metal-resistant actinomycetes.

  18. Isolation and characterization of an atypical LEA protein coding cDNA and its promoter from drought-tolerant plant Prosopis juliflora. (United States)

    George, Suja; Usha, B; Parida, Ajay


    Plant growth and productivity are adversely affected by various abiotic and biotic stress factors. Despite the wealth of information on abiotic stress and stress tolerance in plants, many aspects still remain unclear. Prosopis juliflora is a hardy plant reported to be tolerant to drought, salinity, extremes of soil pH, and heavy metal stress. In this paper, we report the isolation and characterization of the complementary DNA clone for an atypical late embryogenesis abundant (LEA) protein (Pj LEA3) and its putative promoter sequence from P. juliflora. Unlike typical LEA proteins, rich in glycine, Pj LEA3 has alanine as the most abundant amino acid followed by serine and shows an average negative hydropathy. Pj LEA3 is significantly different from other LEA proteins in the NCBI database and shows high similarity to indole-3 acetic-acid-induced protein ARG2 from Vigna radiata. Northern analysis for Pj LEA3 in P. juliflora leaves under 90 mM H2O2 stress revealed up-regulation of transcript at 24 and 48 h. A 1.5-kb fragment upstream the 5' UTR of this gene (putative promoter) was isolated and analyzed in silico. The possible reasons for changes in gene expression during stress in relation to the host plant's stress tolerance mechanisms are discussed.

  19. Polyamines Function in Stress Tolerance: From Synthesis to Regulation

    Directory of Open Access Journals (Sweden)

    Ji-Hong eLiu


    Full Text Available Plants are challenged by a variety of biotic or abiotic stresses, which can affect their growth and development, productivity and geographic distribution. In order to survive adverse environmental conditions, plants have evolved various adaptive strategies, among which is the accumulation of metabolites that play protective roles. A well-established example of the metabolites that are involved in stress responses, or stress tolerance, is the low-molecular-weight aliphatic polyamines, including putrescine,spermidine and spermine. The critical role of polyamines in stress tolerance is suggested by several lines of evidence: firstly, the transcript levels of polyamine biosynthetic genes, as well as the activities of the corresponding enzymes, are induced by stresses; secondly, elevation of endogenous polyamine levels by exogenous supply of polyamines, or overexpression of polyamine biosynthetic genes, results in enhanced stress tolerance; and thirdly, a reduction of endogenous polyamines is accompanied by compromised stress tolerance. A number of studies have demonstrated that polyamines function in stress tolerance largely by modulating the homeostasis of reactive oxygen species (ROS due to their direct, or indirect, roles in regulating antioxidant systems or suppressing ROS production. The transcriptional regulation of polyamine synthesis by transcription factors is also reviewed here. Meanwhile, future perspectives on polyamine research are also suggested.

  20. Fault-Tolerant Systems with Concurrent Error-Locating Capability

    Institute of Scientific and Technical Information of China (English)

    JIANG JianHui(江建慧); MIN YingHua(闵应骅); PENG ChengLian(彭澄廉)


    Fault-tolerant systems have found wide applications in military, industrial andcommercial areas. Most of these systems are constructed by multiple-modular redundancy or er-ror control coding techniques. They need some fault-tolerant specific components (such as voter,switcher, encoder, or decoder) to implement error-detecting or error-correcting functions. However,the problem of error detection, location or correction for fault-tolerance specific components them-selves has not been solved properly so far. Thus, the dependability of a whole fault-tolerant systemwill be greatly affected. This paper presents a theory of robust fault-masking digital circuits forcharacterizing fault-tolerant systems with the ability of concurrent error location and a new schemeof dual-modular redundant systems with partially robust fault-masking property. A basic robustfault-masking circuit is composed of a basic functional circuit and an error-locating corrector. Sucha circuit not only has the ability of concurrent error correction, but also has the ability of concurrenterror location. According to this circuit model, for a partially robust fault-masking dual-modularredundant system, two redundant modules based on alternating-complementary logic consist of thebasic functional circuit. An error-correction specific circuit named as alternating-complementarycorrector is used as the error-locating corrector. The performance (such as hardware complexity,time delay) of the scheme is analyzed.

  1. A Genetic Analysis of Aluminium Tolerance in Cereals

    Directory of Open Access Journals (Sweden)

    Sheeba Navakode


    Full Text Available Aluminium (Al toxicity is a major threat to agricultural production world wide wherever acid soil exists. Wheat and barley, the major food and feed crops, are severely affected and this necessitates investigations that could help to improve the yield by utilising the available genetic diversity for Al tolerance with the aid of several molecular platforms. We investigated the quantitative trait loci (QTL conferring tolerance to Al toxicity in three different mapping populations of wheat and barley.Using a set of D genome (Ae. tauschii introgression lines, a major Al tolerance locus was assigned to chromosome arm 4DL, explaining 31% of the phenotypic variation displayed by the population. A second major QTL was mapped to chromosome arm 3BL using a set of doubled haploid progeny lines. This major QTL, QaltCS.ipk-3B, originated from ‘Chinese Spring’ accounted for 49% of the variation in the population. The inheritance for Al tolerance in barley was dissected based on a genetic map constructed with genic markers. QTLs were identified on chromosomes 2H, 3H and 4H. A sequence homology search was used to derive the putative function of the genes linked to the QTL, in order to identify potential candidate genes for Al tolerance. Some of these candidates are implicated in stress/defence responses, in particular, stress signal transduction, transcription regulation factors and cell metabolism.

  2. A Genetic Analysis of Aluminium Tolerance in Cereals

    Directory of Open Access Journals (Sweden)

    Sheeba Navakode


    Full Text Available Aluminium (Al toxicity is a major threat to agricultural production world wide wherever acid soil exists. Wheat and barley, the major food and feed crops, are severely affected and this necessitates investigations that could help to improve the yield by utilising the available genetic diversity for Al tolerance with the aid of several molecular platforms. We investigated the quantitative trait loci (QTL conferring tolerance to Al toxicity in three different mapping populations of wheat and barley. Using a set of D genome (Ae. tauschii introgression lines, a major Al tolerance locus was assigned to chromosome arm 4DL, explaining 31% of the phenotypic variation displayed by the population. A second major QTL was mapped to chromosome arm 3BL using a set of doubled haploid progeny lines. This major QTL, QaltCS.ipk-3B, originated from ‘Chinese Spring’ accounted for 49% of the variation in the population. The inheritance for Al tolerance in barley was dissected based on a genetic map constructed with genic markers. QTLs were identified on chromosomes 2H, 3H and 4H. A sequence homology search was used to derive the putative function of the genes linked to the QTL, in order to identify potential candidate genes for Al tolerance. Some of these candidates are implicated in stress/defence responses, in particular, stress signal transduction, transcription regulation factors and cell metabolism.

  3. B Cell Tolerance in Health and Disease

    Directory of Open Access Journals (Sweden)

    Murali Gururajan


    Full Text Available B lymphocyte receptors are generated randomly during the bone marrow developmental phase of B cells. Hence, the B cell repertoire consists of both self and foreign antigen specificities necessitating specific tolerance mechanisms to eliminate self-reactive B cells. This review summarizes the major mechanisms of B cell tolerance, which include clonal deletion, anergy and receptor editing. In the bone marrow presentation of antigen in membrane bound form is more effective than soluble form and the role of dendritic cells in this process is discussed. Toll like receptor derived signals affect activation of B cells by certain ligands such as nucleic acids and have been shown to play crucial roles in the development of autoimmunity in several animal models. In the periphery availability of BAFF, a B cell survival factor plays a critical role in the survival of self-reactive B cells. Antibodies against BAFF have been found to be effective therapeutic agents in lupus like autoimmune diseases. Recent developments are targeting anergy to control the growth of chronic lymphocytic leukemia cells.

  4. Mechanism of Salt Tolerance in Rice

    Institute of Scientific and Technical Information of China (English)



    Shaheen Basma ti was evolved as a salt tolerant fine rice va riety by the Soil Salinity Research Institute,Pindi Bhattian, Pakistan. Water culture studies were conducted to investigate the physiological mechanismexercised by this variety in particular and rice plant in general to face the saline environment. Performanceof this rice variety and the concentration and uptake of ions were studied under stress of three salinity levels(30, 60 and 90 mmol L-1) created with NaCl. Recorded data indicated that shoot dry matter was notsignificantly affected by all the three levels of salinity. However, NaCl levels of 60 and 90 mmol L-1 affectedthe root dry matter significantly. Sodium concentration and uptake was enhanced significantly in root andshoot at the first level of salinity (30 mmol L-1) but thereafter the differences were non-significant, indicatingthe preferential absorption of this cation. The K concentration decreased significantly in shoots at all thelevels. The impact was less pronounced in roots as far as K absorption was concerned. The effect on Ca andMg concentrations was not significant. The values of K:Na, Ca:Na and (Ca+Mg):Na ratios in shoot and rootwere comparatively low under stress conditions, indicating that selective ion absorption may be the principalsalt tolerance mechanism of variety Shaheen Basmati when grown in a saline medium.

  5. Fault-Tolerant Heat Exchanger (United States)

    Izenson, Michael G.; Crowley, Christopher J.


    A compact, lightweight heat exchanger has been designed to be fault-tolerant in the sense that a single-point leak would not cause mixing of heat-transfer fluids. This particular heat exchanger is intended to be part of the temperature-regulation system for habitable modules of the International Space Station and to function with water and ammonia as the heat-transfer fluids. The basic fault-tolerant design is adaptable to other heat-transfer fluids and heat exchangers for applications in which mixing of heat-transfer fluids would pose toxic, explosive, or other hazards: Examples could include fuel/air heat exchangers for thermal management on aircraft, process heat exchangers in the cryogenic industry, and heat exchangers used in chemical processing. The reason this heat exchanger can tolerate a single-point leak is that the heat-transfer fluids are everywhere separated by a vented volume and at least two seals. The combination of fault tolerance, compactness, and light weight is implemented in a unique heat-exchanger core configuration: Each fluid passage is entirely surrounded by a vented region bridged by solid structures through which heat is conducted between the fluids. Precise, proprietary fabrication techniques make it possible to manufacture the vented regions and heat-conducting structures with very small dimensions to obtain a very large coefficient of heat transfer between the two fluids. A large heat-transfer coefficient favors compact design by making it possible to use a relatively small core for a given heat-transfer rate. Calculations and experiments have shown that in most respects, the fault-tolerant heat exchanger can be expected to equal or exceed the performance of the non-fault-tolerant heat exchanger that it is intended to supplant (see table). The only significant disadvantages are a slight weight penalty and a small decrease in the mass-specific heat transfer.

  6. Quantitative Trait Loci for Mercury Tolerance in Rice Seedlings

    Institute of Scientific and Technical Information of China (English)

    WANG Chong-qing; WANG Tao; MU Ping; LI Zi-chao; YANG Ling


    Mercury (Hg) is one of the most toxic heavy metals to living organisms and its conspicuous effect is the inhibition of root growth.However,little is known about the molecular genetic basis for root growth under excess Hg2+ stress.To map quantitative trait loci (QTLs) in rice for Hg2+ tolerance,a population of 120 recombinant inbred lines derived from a cross between two japonica cultivars Yuefu and IRAT109 was grown in 0.5 mmol/L CaCl2 solution.Relative root length (RRL),percentage of the seminal root length in +HgCl2 to -HgCl2,was used for assessing Hg2+ tolerance.In a dose-response experiment,Yuefu had a higher RRL than IRAT109 and showed the most significant difference at the Hg2+ concentration of 1.5 μmol/L.Three putative QTLs for RRL were detected on chromosomes 1,2 and 5,and totally explained about 35.7% of the phenotypic variance in Hg2+ tolerance.The identified QTLs for RRL might be useful for improving Hg2+ tolerance of rice by molecular marker-assisted selection.

  7. The PSE1 gene modulates lead tolerance in Arabidopsis (United States)

    Fan, Tingting; Yang, Libo; Wu, Xi; Ni, Jiaojiao; Jiang, Haikun; Zhang, Qi’an; Fang, Ling; Sheng, Yibao; Ren, Yongbing; Cao, Shuqing


    Lead (Pb) is a dangerous heavy metal contaminant with high toxicity to plants. However, the regulatory mechanism of plant Pb tolerance is poorly understood. Here, we showed that the PSE1 gene confers Pb tolerance in Arabidopsis. A novel Pb-sensitive mutant pse1-1 (Pb-sensitive1) was isolated by screening T-DNA insertion mutants. PSE1 encodes an unknown protein with an NC domain and was localized in the cytoplasm. PSE1 was induced by Pb stress, and the pse1-1 loss-of-function mutant showed enhanced Pb sensitivity; overexpression of PSE1 resulted in increased Pb tolerance. PSE1-overexpressing plants showed increased Pb accumulation, which was accompanied by the activation of phytochelatin (PC) synthesis and related gene expression. In contrast, the pse1-1 mutant showed reduced Pb accumulation, which was associated with decreased PC synthesis and related gene expression. In addition, the expression of PDR12 was also increased in PSE1-overexpressing plants subjected to Pb stress. Our results suggest that PSE1 regulates Pb tolerance mainly through glutathione-dependent PC synthesis by activating the expression of the genes involved in PC synthesis and at least partially through activating the expression of the ABC transporter PDR12/ABCG40. PMID:27335453

  8. Unprecedented simultaneous enhancement in damage tolerance and fatigue resistance of zirconia/Ta composites (United States)

    Smirnov, A.; Beltrán, J. I.; Rodriguez-Suarez, T.; Pecharromán, C.; Muñoz, M. C.; Moya, J. S.; Bartolomé, J. F.


    Dense (>98 th%) and homogeneous ceramic/metal composites were obtained by spark plasma sintering (SPS) using ZrO2 and lamellar metallic powders of tantalum or niobium (20 vol.%) as starting materials. The present study has demonstrated the unique and unpredicted simultaneous enhancement in toughness and strength with very high flaw tolerance of zirconia/Ta composites. In addition to their excellent static mechanical properties, these composites also have exceptional resistance to fatigue loading. It has been shown that the major contributions to toughening are the resulting crack bridging and plastic deformation of the metallic particles, together with crack deflection and interfacial debonding, which is compatible with the coexistence in the composite of both, strong and weak ceramic/metal interfaces, in agreement with predictions of ab-initio calculations. Therefore, these materials are promising candidates for designing damage tolerance components for aerospace industry, cutting and drilling tools, biomedical implants, among many others. PMID:28322343

  9. Unprecedented simultaneous enhancement in damage tolerance and fatigue resistance of zirconia/Ta composites (United States)

    Smirnov, A.; Beltrán, J. I.; Rodriguez-Suarez, T.; Pecharromán, C.; Muñoz, M. C.; Moya, J. S.; Bartolomé, J. F.


    Dense (>98 th%) and homogeneous ceramic/metal composites were obtained by spark plasma sintering (SPS) using ZrO2 and lamellar metallic powders of tantalum or niobium (20 vol.%) as starting materials. The present study has demonstrated the unique and unpredicted simultaneous enhancement in toughness and strength with very high flaw tolerance of zirconia/Ta composites. In addition to their excellent static mechanical properties, these composites also have exceptional resistance to fatigue loading. It has been shown that the major contributions to toughening are the resulting crack bridging and plastic deformation of the metallic particles, together with crack deflection and interfacial debonding, which is compatible with the coexistence in the composite of both, strong and weak ceramic/metal interfaces, in agreement with predictions of ab-initio calculations. Therefore, these materials are promising candidates for designing damage tolerance components for aerospace industry, cutting and drilling tools, biomedical implants, among many others.

  10. Isolation and Characterization of Four Gram-Positive Nickel-Tolerant Microorganisms from Contaminated Sediments

    Energy Technology Data Exchange (ETDEWEB)

    Van Nostrand, J. D.; Khijniak, T. V.; Gentry, T. J.; Novak, M. T.; Sowder, A. G.; Zhou, J. Z.; Bertsch, P. M.; Morris, P. J.


    Microbial communities from riparian sediments contaminated with high levels of Ni and U were examined for metal-tolerant microorganisms. Isolation of four aerobic Ni-tolerant, Gram-positive heterotrophic bacteria indicated selection pressure from Ni. These isolates were identified as Arthrobacter oxydans NR-1, Streptomyces galbus NR-2, Streptomyces aureofaciens NR-3, and Kitasatospora cystarginea NR-4 based on partial 16S rDNA sequences. A functional gene microarray containing gene probes for functions associated with biogeochemical cycling, metal homeostasis, and organic contaminant degradation showed little overlap among the four isolates. Fifteen of the genes were detected in all four isolates with only two of these related to metal resistance, specifically to tellurium. Each of the four isolates also displayed resistance to at least one of six antibiotics tested, with resistance to kanamycin, gentamycin, and ciprofloxacin observed in at least two of the isolates. Further characterization of S. aureofaciens NR-3 and K. cystarginea NR-4 demonstrated that both isolates expressed Ni tolerance constitutively. In addition, both were able to grow in higher concentrations of Ni at pH 6 as compared with pH 7 (42.6 and 8.5 mM Ni at pH 6 and 7, respectively). Tolerance to Cd, Co, and Zn was also examined in these two isolates; a similar pH-dependent metal tolerance was observed when grown with Co and Zn. Neither isolate was tolerant to Cd. These findings suggest that Ni is exerting a selection pressure at this site for metal-resistant actinomycetes.

  11. Mathematical model of cylindrical form tolerance

    Institute of Scientific and Technical Information of China (English)

    蔡敏; 杨将新; 吴昭同


    Tolerance is essential for integration of CAD and CAM.Unfortunately,the meaning of tolerances in the national standard is expressed in graphical and language forms and is not adaptable for expression,processing and data transferring with computers.How to interpret its semantics is becoming a focus of relevant studies.This work based on the mathematical definition of form tolerance in ANSI Y 14.5.1 M-1994,established the mathematical model of form tolerance for cylindrical feature.First,each tolerance in the national standard was established by vector equation.Then on the foundation of tolerance's mathematical definition theory,each tolerance zone's mathematical model was established by inequality based on degrees of feature.At last the variance area of each tolerance zone is derived.This model can interpret the semantics of form tolerance exactly and completely.

  12. Building Intrusion Tolerant Software System

    Institute of Scientific and Technical Information of China (English)

    PENG Wen-ling; WANG Li-na; ZHANG Huan-guo; CHEN Wei


    In this paper, we describe and analyze the hypothesis about intrusion tolerance software system, so that it can provide an intended server capability and deal with the impacts caused by the intruder exploiting the inherent security vulnerabilities. We present some intrusion tolerance technology by exploiting N-version module threshold method in constructing multilevel secure software architecture, by detecting with hash value, by placing an "antigen" word next to the return address on the stack that is similar to human immune system, and by adding "Honey code" nonfunctional code to disturb intruder, so that the security and the availability of the software system are ensured.

  13. Identification of stress-induced genes from the drought-tolerant plant Prosopis juliflora (Swartz) DC. through analysis of expressed sequence tags. (United States)

    George, Suja; Venkataraman, Gayatri; Parida, Ajay


    Abiotic stresses such as cold, salinity, drought, wounding, and heavy metal contamination adversely affect crop productivity throughout the world. Prosopis juliflora is a phreatophyte that can tolerate severe adverse environmental conditions such as drought, salinity, and heavy metal contamination. As a first step towards the characterization of genes that contribute to combating abiotic stress, construction and analysis of a cDNA library of P. juliflora genes is reported here. Random expressed sequence tag (EST) sequencing of 1750 clones produced 1467 high-quality reads. These clones were classified into functional categories, and BLAST comparisons revealed that 114 clones were homologous to genes implicated in stress response(s) and included heat shock proteins, metallothioneins, lipid transfer proteins, and late embryogenesis abundant proteins. Of the ESTs analyzed, 26% showed homology to previously uncharacterized genes in the databases. Fifty-two clones from this category were selected for reverse Northern analysis: 21 were shown to be upregulated and 16 downregulated. The results obtained by reverse Northern analysis were confirmed by Northern analysis. Clustering of the 1467 ESTs produced a total of 295 contigs encompassing 790 ESTs, resulting in a 54.2% redundancy. Two of the abundant genes coding for a nonspecific lipid transfer protein and late embryogenesis abundant protein were sequenced completely. Northern analysis (after polyethylene glycol stress) of the 2 genes was carried out. The implications of the analyzed genes in abiotic stress tolerance are also discussed.

  14. Tolerating extremism : to what extent should intolerance be tolerated?

    NARCIS (Netherlands)

    Guiora, Amos Neuser


    In discussing extremism, the key questions are: to whom is a duty owed and what are the limits of intolerance that are to be tolerated? Answering these questions requires examining limits and rights; analyzing them in the context of extremism is the ‘core’ of this book. While freedom of speech and f

  15. A survey analysis of heavy metals bio-accumulation in internal organs of sea shell animals affected by the sustainable pollution of antifouling paints used for ships anchored at some domestic maritime spaces

    Institute of Scientific and Technical Information of China (English)

    WANG JunLian; WANG FengQi; YU Jie; ZHUANG Yan; ZHOU XiangFeng; ZHANG XiaoBin; PENG BiXian


    Some samples of sea shell animals stuck and multiplied on the bottom (beneath the seawater) coated with antifouling paints were collected at some domestic maritime spaces,and the content of heavy metals was detected through Inductively Coupled Plasma-Mass Spectroscopy.Meanwhile,comparison with sea shell animals was made on market for edible use.It shows that the content of heavy metals in internal organs of these marine animals is very high due to the large amount of copper and zinc con-tained in the antifouling paints,and this also does severely harm to sea environment and ecology.To study and develop the novel antifouling paints without copper(I) oxide is an imperative task which brooks no delay.

  16. Transcript analysis in two alfalfa salt tolerance selected breeding populations relative to a non-tolerant population. (United States)

    Gruber, M Y; Xia, J; Yu, M; Steppuhn, H; Wall, K; Messer, D; Sharpe, A G; Acharya, S N; Wishart, D S; Johnson, D; Miller, D R; Taheri, A


    With the growing limitations on arable land, alfalfa (a widely cultivated, low-input forage) is now being selected to extend cultivation into saline lands for low-cost biofeedstock purposes. Here, minerals and transcriptome profiles were compared between two new salinity-tolerant North American alfalfa breeding populations and a more salinity-sensitive western Canadian alfalfa population grown under hydroponic saline conditions. All three populations accumulated two-fold higher sodium in roots than shoots as a function of increased electrical conductivity. At least 50% of differentially expressed genes (p population growing under high salinity, while expression remained unchanged in the saline-tolerant populations. In particular, most reduction in transcript levels in the salt-sensitive population was observed in genes specifying cell wall structural components, lipids, secondary metabolism, auxin and ethylene hormones, development, transport, signalling, heat shock, proteolysis, pathogenesis-response, abiotic stress, RNA processing, and protein metabolism. Transcript diversity for transcription factors, protein modification, and protein degradation genes was also more strongly affected in salt-tolerant CW064027 than in salt-tolerant Bridgeview and salt-sensitive Rangelander, while both saline-tolerant populations showed more substantial up-regulation in redox-related genes and B-ZIP transcripts. The report highlights the first use of bulked genotypes as replicated samples to compare the transcriptomes of obligate out-cross breeding populations in alfalfa.

  17. Heavy Metal Accumulation in Plants on Mn Mine Tailings

    Institute of Scientific and Technical Information of China (English)

    LIU Yun-Guo; ZHANG Hui-Zhi; ZENG Guang-Ming; HUANG Bao-Rong; LI Xin


    The Xiangtan Manganese (Mn) Mine in the middle of Hunan Province, China, has been mined since 1913 with mine tailings including excavated wastes, wastewater, and smelting wastes. A survey was conducted on the Mn mine tailing soils and eight plants on the Mn mine tailings. The concentrations of soil Mn, Pb, and Cd and the metal-enrichment traits of these eight plants were analyzed simultaneously. Exceptionally high concentrations of these three metals were found in the soils, especially on the tailing dam. Each plant investigated in this study accumulated the three heavy metals, but no hyperaccumulator of these metals was found. However, analysis indicated that Poa pratensis Linn., Gnaphalium affine D. Don, Pteris vittata L., CoRyza canadensis (L.) Cronq., and Phytolacca acinosa Roxb. possessed specially good metalenrichment and metal-tolerant traits. P. pratensis, G. affine, and P. vittata were Pb-tolerant plants; and C. canadensis,P. pratensis, and G. affine were Cd-tolerant plants. P. acinosa had a great tolerance to Mn, and it was a valuable plant for on-site phytoremediation. Phragmites communis Trin. was found to have high metal tolerance and economic benefit as a raw material for paper and should be considered for soil remediation. G. affine and C. canadensis had excessive accumulation of Mn and could be useful in phytoremediation. However, although P. pratensis was a good accumulator,it was not a suitable plant for soil remediation because its biomass was too little.

  18. Stress tolerances of nullmutants of function-unknown genes encoding menadione stress-responsive proteins in Aspergillus nidulans. (United States)

    Leiter, Éva; Bálint, Mihály; Miskei, Márton; Orosz, Erzsébet; Szabó, Zsuzsa; Pócsi, István


    A group of menadione stress-responsive function-unkown genes of Aspergillus nidulans (Locus IDs ANID_03987.1, ANID_06058.1, ANID_10219.1, and ANID_10260.1) was deleted and phenotypically characterized. Importantly, comparative and phylogenetic analyses of the tested A. nidulans genes and their orthologs shed light only on the presence of a TANGO2 domain with NRDE protein motif in the translated ANID_06058.1 gene but did not reveal any recognizable protein-encoding domains in other protein sequences. The gene deletion strains were subjected to oxidative, osmotic, and metal ion stress and, surprisingly, only the ΔANID_10219.1 mutant showed an increased sensitivity to 0.12 mmol l(-1) menadione sodium bisulfite. The gene deletions affected the stress sensitivities (tolerances) irregularly, for example, some strains grew more slowly when exposed to various oxidants and/or osmotic stress generating agents, meanwhile the ΔANID_10260.1 mutant possessed a wild-type tolerance to all stressors tested. Our results are in line with earlier studies demonstrating that the deletions of stress-responsive genes do not confer necessarily any stress-sensitivity phenotypes, which can be attributed to compensatory mechanisms based on other elements of the stress response system with overlapping functions.

  19. Synthesis of Fault Tolerant Reversible Logic Circuits

    CERN Document Server

    Islam, Md Saiful; Begum, Zerina; Hafiz, Mohd Zulfiquar; Mahmud, Abdullah Al; 10.1109/CAS-ICTD.2009.4960883


    Reversible logic is emerging as an important research area having its application in diverse fields such as low power CMOS design, digital signal processing, cryptography, quantum computing and optical information processing. This paper presents a new 4*4 universal reversible logic gate, IG. It is a parity preserving reversible logic gate, that is, the parity of the inputs matches the parity of the outputs. The proposed parity preserving reversible gate can be used to synthesize any arbitrary Boolean function. It allows any fault that affects no more than a single signal readily detectable at the circuit's primary outputs. Finally, it is shown how a fault tolerant reversible full adder circuit can be realized using only two IGs. It has also been demonstrated that the proposed design offers less hardware complexity and is efficient in terms of gate count, garbage outputs and constant inputs than the existing counterparts.

  20. Workshop Oriented Tolerance Synthesis for Spatial PKM

    Institute of Scientific and Technical Information of China (English)

    Jianguang Li; Jian Ding; Yingxue Yao; Zhaohong Yi; Huaijing Jing; Honggen Fang


    To promote the pose accuracy performance of a spatial parallel kinematic Mechanism ( PKM) in service, a workshop oriented tolerance synthesis method based on design of experiment ( DOE) is proposed, which involves two consecutive stages. In the first stage of DOE, the tolerance factor sensitivities are obtained according to initial tolerance settings with the consideration of the current manufacturing capacity, and the second stage of DOE makes use of them to produce multiple tolerance allocations which can adapt to current manufacturing capacity. A tolerance synthesis procedure is developed and integrated in tolerance design system for PKM. Comparing the results with peer method, the validity and practicability of this method is verified.

  1. Prospecting sugarcane genes involved in aluminum tolerance

    Directory of Open Access Journals (Sweden)

    Rodrigo D. Drummond


    Full Text Available Aluminum is one of the major factors that affect plant development in acid soils, causing a substantial reduction in yield in many crops. In South America, about 66% of the land surface is made up of acid soils where high aluminum saturation is one of the main limiting factors for agriculture. The biochemical and molecular basis of aluminum tolerance in plants is far from being completely understood despite a growing number of studies, and in the specific case of sugarcane there are virtually no reports on the effects of gene regulation on aluminum stress. The objective of the work presented in this paper was to prospect the sugarcane expressed sequence tag (SUCEST data bank for sugarcane genes related to several biochemical pathways known to be involved in the responses to aluminum toxicity in other plant species and yeast. Sugarcane genes similar to most of these genes were found, including those coding for enzymes that alleviate oxidative stress or combat infection by pathogens and those which code for proteins responsible for the release of organic acids and signal transducers. The role of these genes in aluminum tolerance mechanisms is reviewed. Due to the high level of genomic conservation in related grasses such as maize, barley, sorghum and sugarcane, these genes may be valuable tools which will help us to better understand and to manipulate aluminum tolerance in these species.Alumínio (Al é um dos principais fatores que afetam o desenvolvimento de plantas em solos ácidos, reduzindo substancialmente a produtividade agrícola. Na América do Sul, cerca de 66% da superfície do solo apresenta acidez, onde a alta saturação de alumínio é uma das maiores limitações à prática agrícola. Apesar do crescente número de estudos, uma compreensão completa das bases bioquímicas e moleculares da tolerância ao alumínio em plantas está longe de ser alcançada. No caso da cana-de-açúcar, não há nada publicado sobre a regulação g

  2. Synthesis and role of salicylic acid in wheat varieties with different levels of cadmium tolerance

    Energy Technology Data Exchange (ETDEWEB)

    Kovács, Viktória; Gondor, Orsolya K.; Szalai, Gabriella; Darkó, Éva; Majláth, Imre; Janda, Tibor; Pál, Magda, E-mail:


    Highlights: • Cd induces the salicylic acid metabolism in wheat. • Salicylic acid is synthesized via benzoic acid and/or ortho-hydroxy-cinnamic acid. • Cd tolerance can be explained by the highly induced glutathione metabolism. • Salicylic acid signalling is correlated with glutathione-related mechanisms. - Abstract: Wheat genotypes with different endogenous SA contents were investigated, in order to reveal how cadmium influences salicylic acid (SA) synthesis, and to find possible relationships between SA and certain protective compounds (members of the antioxidants and the heavy metal detoxification system) and between the SA content and the level of cadmium tolerance. Cadmium exposure induced SA synthesis, especially in the leaves, and it is suggested that the phenyl-propanoid synthesis pathway is responsible for the accumulation of SA observed after cadmium stress. Cadmium influenced the synthesis and activation of protective compounds to varying extents in wheat genotypes with different levels of tolerance; the roots and leaves also responded differently to cadmium stress. Although a direct relationship was not found between the initial SA levels and the degree of cadmium tolerance, the results suggest that the increase in the root SA level during cadmium stress in the Mv varieties could be related with the enhancement of the internal glutathione cycle, thus inducing the antioxidant and metal detoxification systems, which promote Cd stress tolerance in wheat seedlings. The positive correlation between certain SA-related compounds and protective compounds suggests that SA-related signalling may also play a role in the acclimation to heavy metal stress.

  3. Stepping Back from Zero Tolerance (United States)

    Browne-Dianis, Judith


    Schools' use of zero tolerance policies has been increasing since the 1980s as part of a societal movement to crack down on drug abuse and violence among youth. But far from making schools safer, this harsh, inflexible approach to discipline has been eroding the culture of schools and creating devastating consequences for children, writes…

  4. Biocatalysts with enhanced inhibitor tolerance

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Shihui; Linger, Jeffrey; Franden, Mary Ann; Pienkos, Philip T.; Zhang, Min


    Disclosed herein are biocatalysts for the production of biofuels, including microorganisms that contain genetic modifications conferring tolerance to growth and fermentation inhibitors found in many cellulosic feedstocks. Methods of converting cellulose-containing materials to fuels and chemicals, as well as methods of fermenting sugars to fuels and chemicals, using these biocatalysts are also disclosed.

  5. Desiccation tolerance of somatic embryoids.

    NARCIS (Netherlands)

    Tetteroo, F.A.A.


    This thesis describes the research performed on the subject "Desiccation tolerance in somatic embryoids". Somatic embryoids are bipolar structures formed in tissue culture, with both a shoot and a root apex, which resemble very much zygotic embryos found in seeds. Through simultaneous development of

  6. Defining and Assessing Affective Outcomes in Undergraduate Pediatric Dentistry. (United States)

    Cullen, Claire L.


    The affective aspect of the curriculum is defined as the development of appropriate and measurable values such as ethical behavior, honesty, tolerance, and becoming a life-long learner. In outcome assessment of the affective category, the goal is to evaluate the transition of the student to a professional. (MLW)

  7. Metal accumulating plants: Medium's role (United States)

    Rabier, J.; Prudent, P.; Szymanska, B.; Mevy, J.-P.


    To evaluate phytoremediation potentialities by metal accumulation in tolerant plants, trials are carried out using in vitro cultures. Organie compounds influence on metal accumulation is studied with metals supplemented media. The tested compounds on zinc and lead absorption by Brassica juncea, are chelating agents (EDTA, citric acid) and soluble organic fractions of compost. EDTA seems to enhance the transfer of lead in plant but it is the opposite in the case of zinc. Citric acid stimulates root absorption for both zinc and lead. For the aqueous extracts of compost, variable effects are obtained according to the origin of compost (green wastes and food wastes). In'all tested conditions of cultures, zinc is mainly exported towards shoot while lead is stored in root.

  8. Plant transporters involved in heavy metal homeostasis

    Directory of Open Access Journals (Sweden)

    Dorina Podar


    Full Text Available Transition metal ions (predominately manganese, iron, cobalt, nickel, copper and zinc havean array of catalytic and regulatory roles in the growth and development of all living organisms.However, an excess of these metal ions can also be toxic to any life form and therefore every cell andwhole organism needs to maintain the concentration of these essential nutrient metals within a narrowrange: a process known as metal homeostasis. Heavy metal ions are taken up into cells by selectivetransporters and as they cannot be degraded, the “desired” levels of metal ions are achieved by anumber of strategies that involve: chelation, sequestration and export out of the cell. Cation DiffusionFacilitators (CDF is a large family of transporters involved in maintaining the cytosolic metalconcentration. They transport different heavy metal divalent ions, but exhibit main affinity for zinc, ironand manganese. Metal Tolerance Proteins (MTPs are a subfamily of the Cation Diffusion Facilitator (CDFfamily found in plants. There has been much interest in these heavy metal transporters in order toprovide an insight into plant metal homeostasis, which has significant implications in human health andphytoremediation. Although data regarding the CDFs/MTPs mechanism is gathering there is still littleinformation with respect to metal selectivity determinants.

  9. Metal selectivity determinants in a family of transition metal transporters. (United States)

    Podar, Dorina; Scherer, Judith; Noordally, Zeenat; Herzyk, Pawel; Nies, Dietrich; Sanders, Dale


    Metal tolerance proteins (MTPs) are plant members of the cation diffusion facilitator (CDF) transporter family involved in cellular metal homeostasis. Members of the CDF family are ubiquitously found in all living entities and show principal selectivity for Zn(2+), Mn(2+), and Fe(2+). Little is known regarding metal selectivity determinants of CDFs. We identified a novel cereal member of CDFs in barley, termed HvMTP1, that localizes to the vacuolar membrane. Unlike its close relative AtMTP1, which is highly selective for Zn(2+), HvMTP1 exhibits selectivity for both Zn(2+) and Co(2+) as assessed by its ability to suppress yeast mutant phenotypes for both metals. Expression of HvMTP1/AtMTP1 chimeras in yeast revealed a five-residue sequence within the AtMTP1 N-segment of the His-rich intracytoplasmic loop that confines specificity to Zn(2+). Furthermore, mutants of AtMTP1 generated through random mutagenesis revealed residues embedded within transmembrane domain 3 that additionally specify the high degree of Zn(2+) selectivity. We propose that the His-rich loop, which might play a role as a zinc chaperone, determines the identity of the metal ions that are transported. The residues within transmembrane domain 3 can also influence metal selectivity, possibly through conformational changes induced at the cation transport site located within the membrane or at the cytoplasmic C-terminal domain.

  10. A Developmental View of Children's Behavioral Tolerance. (United States)

    Safran, Joan S.; Safran, Stephen P.


    Analysis of scores of 469 third to sixth graders on the Children's Tolerance Scale yielded significant grade level differences with older children generally the most tolerant. The more outer-directed behaviors were rated as most disturbing. (CL)

  11. Urbanism, Migration, and Tolerance: A Reassessment. (United States)

    Wilson, Thomas C.


    Urbanism's impact on the personality may be stronger than previously thought. Finds that urban residence has a strong positive effect on tolerance. Migration also promotes tolerance, regardless of the size of the destination community. (DM)

  12. 77 FR 3617 - Etoxazole; Pesticide Tolerances (United States)


    ... cell tumors (testis) and pancreas benign islet cell adenomas were observed (in females) at the high... Development tolerance calculation procedures, the EPA revised the tolerance levels for corn, field,...

  13. Increased tolerance to humans among disturbed wildlife (United States)

    Samia, Diogo S. M.; Nakagawa, Shinichi; Nomura, Fausto; Rangel, Thiago F.; Blumstein, Daniel T.


    Human disturbance drives the decline of many species, both directly and indirectly. Nonetheless, some species do particularly well around humans. One mechanism that may explain coexistence is the degree to which a species tolerates human disturbance. Here we provide a comprehensive meta-analysis of birds, mammals and lizards to investigate species tolerance of human disturbance and explore the drivers of this tolerance in birds. We find that, overall, disturbed populations of the three major taxa are more tolerant of human disturbance than less disturbed populations. The best predictors of the direction and magnitude of bird tolerance of human disturbance are the type of disturbed area (urbanized birds are more tolerant than rural or suburban populations) and body mass (large birds are more tolerant than small birds). By identifying specific features associated with tolerance, these results guide evidence-based conservation strategies to predict and manage the impacts of increasing human disturbance on birds. PMID:26568451

  14. Bioremediation of heavy metals in liquid media through fungi isolated from contaminated sources. (United States)

    Joshi, P K; Swarup, Anand; Maheshwari, Sonu; Kumar, Raman; Singh, Namita


    Wastewater particularly from electroplating, paint, leather, metal and tanning industries contain enormous amount of heavy metals. Microorganisms including fungi have been reported to exclude heavy metals from wastewater through bioaccumulation and biosorption at low cost and in eco-friendly way. An attempt was, therefore, made to isolate fungi from sites contaminated with heavy metals for higher tolerance and removal of heavy metals from wastewater. Seventy-six fungal isolates tolerant to heavy metals like Pb, Cd, Cr and Ni were isolated from sewage, sludge and industrial effluents containing heavy metals. Four fungi (Phanerochaete chrysosporium, Aspegillus awamori, Aspergillus flavus, Trichoderma viride) also were included in this study. The majority of the fungal isolates were able to tolerate up to 400 ppm concentration of Pb, Cd, Cr and Ni. The most heavy metal tolerant fungi were studied for removal of heavy metals from liquid media at 50 ppm concentration. Results indicated removal of substantial amount of heavy metals by some of the fungi. With respect to Pb, Cd, Cr and Ni, maximum uptake of 59.67, 16.25, 0.55, and 0.55 mg/g was observed by fungi Pb3 (Aspergillus terreus), Trichoderma viride, Cr8 (Trichoderma longibrachiatum), and isolate Ni27 (A. niger) respectively. This indicated the potential of these fungi as biosorbent for removal of heavy metals from wastewater and industrial effluents containing higher concentration of heavy metals.

  15. VLSI metallization

    CERN Document Server

    Einspruch, Norman G; Gildenblat, Gennady Sh


    VLSI Electronics Microstructure Science, Volume 15: VLSI Metallization discusses the various issues and problems related to VLSI metallization. It details the available solutions and presents emerging trends.This volume is comprised of 10 chapters. The two introductory chapters, Chapter 1 and 2 serve as general references for the electrical and metallurgical properties of thin conducting films. Subsequent chapters review the various aspects of VLSI metallization. The order of presentation has been chosen to follow the common processing sequence. In Chapter 3, some relevant metal deposition tec

  16. Relationship between fish size and upper thermal tolerance (United States)

    Recsetar, Matthew S.; Zeigler, Matthew P.; Ward, David L.; Bonar, Scott A.; Caldwell, Colleen A.


    Using critical thermal maximum (CTMax) tests, we examined the relationship between upper temperature tolerances and fish size (fry-adult or subadult lengths) of rainbow trout Oncorhynchus mykiss (41-200-mm TL), Apache trout O. gilae apache (40-220-mm TL), largemouth bass Micropterus salmoides (72-266-mm TL), Nile tilapia Oreochromis niloticus (35-206-mm TL), channel catfish Ictalurus punctatus (62-264 mm-TL), and Rio Grande cutthroat trout O. clarkii virginalis (36-181-mm TL). Rainbow trout and Apache trout were acclimated at 18°C, Rio Grande cutthroat trout were acclimated at 14°C, and Nile tilapia, largemouth bass, and channel catfish were acclimated at 25°C, all for 14 d. Critical thermal maximum temperatures were estimated and data were analyzed using simple linear regression. There was no significant relationship (P > 0.05) between thermal tolerance and length for Nile tilapia (P = 0.33), channel catfish (P = 0.55), rainbow trout (P = 0.76), or largemouth bass (P = 0.93) for the length ranges we tested. There was a significant negative relationship between thermal tolerance and length for Rio Grande cutthroat trout (R2 = 0.412, P 2 = 0.1374, P = 0.028); however, the difference was less than 1°C across all lengths of Apache trout tested and about 1.3°C across all lengths of Rio Grande cutthroat trout tested. Because there was either no or at most a slight relationship between upper thermal tolerance and size, management and research decisions based on upper thermal tolerance should be similar for the range of sizes within each species we tested. However, the different sizes we tested only encompassed life stages ranging from fry to adult/subadult, so thermal tolerance of eggs, alevins, and larger adults should also be considered before making management decisions affecting an entire species.

  17. Influence of substrate process tolerances on transmission characteristics of frequency-selective surface

    Institute of Scientific and Technical Information of China (English)

    He Zhang; Jun Lu; Guancheng Sun; Hongliang Xiao


    Frequency-selective surface (FSS) is a two-dimensional periodic structure consisting of a dielectric substrate and the metal units (or apertures) arranged periodically on it. When manufacturing the substrate, its thickness and dielectric constant suffer process tolerances. This may induce the center frequency of the FSS to shift, and consequently influence its characteristics. In this paper, a bandpass FSS structure is designed. The units are the Jerusalem crosses arranged squarely. The mode-matching technique is used for simulation. The influence of the tolerances of the substrate's thickness and dielectric constant on the center frequency is analyzed. Results show that the tolerances of thickness and dielectric constant have different influences on the center frequency of the FSS. It is necessary to ensure the process tolerance of the dielectric constant in the design and manufacturing of the substrate in order to stabilize the center frequency.

  18. Recent Advances in Durability and Damage Tolerance Methodology at NASA Langley Research Center