720 research outputs found

    Tpr1, a Schizosaccharomyces pombe protein involved in potassium transport

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    AbstractThe Schizosaccharomyces pombe Tpr1 was isolated as suppressor of the Saccharomyces cerevisiae Δ trk1,2 potassium uptake deficient phenotype. Tpr1, for tetratrico peptide repeat, encodes a 1039 amino acid residues protein with several reiterated TPR units displaying significant homology to p150TSP, a recently identified phosphoprotein of mouse, to S. cerevisiae CTR9 and to related sequences of human, Caenorhabditis elegans, Methanoccocus jannaschii and Arabidopsis thaliana. Expression of Tpr1 restored growth on 0.2 mM K+ media, induced K+ transport with a KT of 4.6 mM and resumed inward currents of −90 pÅ at −250 mV (pH 7.2) conducting K+ and other alkali-metal ions. The tetratrico peptide repeat is a degenerate motif of 34 amino acids that is repeated several times within TPR-containing proteins and has been suggested to mediate protein-protein interactions. The sequence and putative binding properties of Tpr1 suggest the protein unlikely as transporter but involved in the enhancement of K+ uptake via conventional carriers

    Breeding of resistant strawberry cultivars for organic fruit production – Diallel crossing strategies and resistance tests for Botrytis cinerea and Xanthomonas fragariae

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    Organic strawberry production suffers from high yield losses caused by numerous fungal and bacterial diseases. Two of the most important diseases are the grey mould disease caused by Botrytis cinerea Pers. (teleomorph Botryotinia fuckeliana), and the bacterial angular leaf spot disease caused by Xanthomonas fragariae (Kennedy & King). Beside cultivation methods and organic plant protection measures, the development of resistant cultivars seems to be the most promising strategy in order to improve the productivity in organic strawberry cultivation. Therefore, we established resistance tests to determine resistant and susceptible strawberry cultivars and breeding selections. In a first run, 40 different cultivars and selections were tested for their susceptibility towards B. cinerea by artificial inoculation of fruits and leaves and evaluation of the disease symptoms. Plants of 40 cultivars were tested for susceptibility to X. fragariae by artificial inoculation in the greenhouse. In a diallel crossing approach, 12 commonly cultivated strawberry cultivars have been crossed reciprocally and propagated in a field trial. Important characteristics of the progeny such as ripening time, yield, morphological traits and occurrence of diseases have been evaluated for a period of two consecutive years and lead to the determination of general (GCA) and specific (SCA) combining abilities. Together with the results of the resistance tests we identified a set of genotypes that show resistant characteristics towards B. cinerea and might be suitable for use in organic cultivation systems. Furthermore, they can be used for targeted breeding experiments in the future

    Streaming instability of slime mold amoebae: An analytical model

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    During the aggregation of amoebae of the cellular slime mould Dictyostelium, the interaction of chemical waves of the signaling molecule cAMP with cAMP-directed cell movement causes the breakup of a uniform cell layer into branching patterns of cell streams. Recent numerical and experimental investigations emphasize the pivotal role of the cell-density dependence of the chemical wave speed for the occurrence of the streaming instability. A simple, analytically tractable, model of Dictyostelium aggregation is developed to test this idea. The interaction of cAMP waves with cAMP-directed cell movement is studied in the form of coupled dynamics of wave front geometries and cell density. Comparing the resulting explicit instability criterion and dispersion relation for cell streaming with the previous findings of model simulations and numerical stability analyses, a unifying interpretation of the streaming instability as a cAMP wave-driven chemotactic instability is proposed

    Soil fauna and litter decomposition in primary and secondary forests and a mixed culture system in Amazonia.

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    Este relatório representa um relato das atividades efetuadas no segundo ano do projeto como também dos resultados obtidos dos dados de 1997-1998 e da primeira serie de experimentos de decomposição com sacos de liteira (serrapilheira). Baseado nos resultados ainda preliminares, as áreas de estudo podem ser organizadas numa série, começando da área de floresta primária FLO via um dos locais de plantação, POC, até o local de floresta secundária, SEC, e o segundo local de plantação, POA.bitstream/item/201401/1/Soil-Fauna-And-Litter-Decomposition-in-Primary...-1998.pdfSHIFT ENV 52. Annual Report 1998

    Стабилизация излучения бетатрона

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    Uso e manejo de leguminosas em agroecossistemas na Amazônia Central.

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    Este estudo teve como objetivo gerar informações que poderão auxiliar os fruticultores da região na tomada de decisão quanto ao uso e manejo de leguminosas, como tefrósia, para inserção em sistemas de produção de fruteiras, visando à melhoria e manutenção da capacidade produtiva do solo, o controle de invasoras e o desenvolvimento e a produtividade das plantas
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