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  • 1
    Electronic Resource
    Electronic Resource
    Evidence for intermolecular interaction as a necessary step for pore-formation activity and toxicity of Bacillus thuringiensis Cry1Ab toxin (2000)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 191 (2000), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Based on the observation of large conductance states formed by Bacillus thuringiensis Cry toxins in synthetic planar lipid bilayers and the estimation of a pore size of 10–20 Å, it has been proposed that the pore could be formed by an oligomer containing four to six Cry toxin monomers. However, there is a lack of information regarding the insertion of Cry toxins into the membrane and oligomer formation. Here we provide direct evidence showing that the intermolecular interaction between Cry1Ab toxin monomers is a necessary step for pore formation and toxicity. Two Cry1Ab mutant proteins affected in different steps of their mode of action (F371A in receptor binding and H168F in pore formation) were affected in toxicity against Manduca sexta larvae. Binding analysis showed that F371A protein bound more efficiently to M. sexta brush border membrane vesicles when mixed with H168F in a one to one ratio. These mutant proteins also recovered pore-formation activity, measured with a fluorescent dye with isolated brush border membrane vesicles, and toxicity against M. sexta larvae when mixed, showing that monomers affected in different steps of their mode of action can form functional hetero-oligomers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.2000.tb09343.x
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  • 2
    Electronic Resource
    Electronic Resource
    Specific detection of Plesiomonas shigelloides isolated from aquatic environments, animals and human diarrhoeal cases by PCR based on 23S rRNA gene (2000)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 29 (2000), S. 0 
    Details
    ISSN: 1574-695X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Twenty-five strains of Plesiomonas shigelloides isolated from aquatic environment, 10 strains from human cases of diarrhoea and five strains from animals were identified by the polymerase chain reaction technique based on 23S rRNA gene. For this purpose, two primers targeted against part of the 5′ half of the 23S rRNA gene of P. shigelloides (Escherichia coli number C-912, G-1195; Plesiomonas number C-906, G-1189) were designed. Results from our study indicated that this method might serve as a tool for a rapid and sensitive identification of P. shigelloides from different environmental and clinical sources.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-695X.2000.tb01512.x
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  • 3
    Electronic Resource
    Electronic Resource
    Implementation of the Decorrelating Receiver for Asynchronous DS-CDMA Systems over Multipath Fading Channels (2000)
    Springer
    Wireless personal communications 15 (2000), S. 79-95 
    Details
    ISSN: 1572-834X
    Keywords: CDMA ; multiuser detection ; multipath fading channel ; decorrelating detector
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract This paper presents a decorrelating detector for DS-CDMAasynchronous systems over multipath fading channels. The decorrelatingreceiver applies the inverse correlation matrix of signature waveformsto detect the received signal. A procedure for finding such an inversematrix is developed. This procedure employs the reciprocal basis,derived from the basis of normalized user signatures, to cancelsimultaneously both the multiuser and the intersymbolinterference. The proposed multiuser detector operates over a finitedetection window, and the only restriction imposed on the set of signaturesis that the signatures must be independent at the receiver end. If the channelis slowly variant, the detectorcan be very efficient for high bit rate transmissions. Theoreticalbounds for the multiuser interference are obtained. Simulationresults, in which both binary and non-binary sequences are used,reveal that the behaviour of the detector approaches the single userbound when an adequate set of signatures is employed. The reducedcomplexity of this detector indicates that it could be a good candidatefor practical implementation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008959121461
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  • 4
    Electronic Resource
    Electronic Resource
    Effect of feeding strategy on Zymomonas mobilis CP4 fed-batch fermentations and mathematical modeling of the system (2000)
    Springer
    Applied microbiology and biotechnology 54 (2000), S. 487-493 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract In this work, the effect of the feeding strategy in Zymomonas mobilis CP4 fed-batch fermentations on the final biomass and ethanol concentrations was studied. Highest glucose yields to biomass (0.018 g/g) and to ethanol (0.188 g/g) were obtained in fed-batch fermentations carried out using different feeding rates with a glucose concentration in the feed equal to 100 g/l. Lower values (0.0102 g biomass/g glucose and 0.085 g ethanol/g glucose) were obtained when glucose accumulated to levels higher than 60 g/l. On the other hand, the highest biomass (5 g/l) and ethanol (39 g/l) concentrations were obtained using a glucose concentration in the feed equal to 220 g/l and exponentially varied feeding rates. Experimental data were used to validate the mathematical model of the system. The prediction errors of the model are 0.39, 14.36 and 3.24 g/l for the biomass, glucose and ethanol concentrations, respectively. Due to the complex relationship for describing the specific growth rate, a fed-batch culture in which glucose concentration is constant would not optimize the process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002530000423
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  • 5
    Electronic Resource
    Electronic Resource
    Accumulation of a maize proteinase inhibitor in response to wounding and insect feeding, and characterization of its activity toward digestive proteinases of Spodoptera littoralis larvae (2000)
    Springer
    Planta 211 (2000), S. 62-71 
    Details
    ISSN: 1432-2048
    Keywords: Key words: Plant-insect interaction – Proteinase inhibitor –Spodoptera– Wound response –Zea (wound response)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. The mpi gene encodes a maize proteinase inhibitor (MPI) protein whose mRNA accumulates in response to mechanical wounding. In this study, mpi gene expression in response to different types of damage was investigated. In mechanically damaged leaves of maize (Zea mays L.), mpi mRNA accumulation was affected by the degree of damage inflicted on the leaf. Consecutive wounds resulted in higher levels of mpi transcripts. The MPI protein was expressed in Escherichia coli and purified. Polyclonal antibodies were then produced and used to study MPI accumulation in insect-wounded and mechanically wounded maize leaves. When larvae of the lepidopteran insect Spodoptera littoralis were fed on maize leaves, MPI accumulated in tissues adjacent to the wound site. The level of inhibitor accumulation was higher in leaves chewed by larvae than in leaves that had been damaged mechanically. Longer feeding periods also resulted in higher levels of MPI accumulation. Additionally, the inhibitory properties of MPI toward mammalian and insect digestive serine proteinases were determined. Contrary to the majority of the plant proteinase inhibitors described, MPI is an inhibitor of mammalian elastase that only weakly inhibits mammalian chymotrypsin. However, both elastase and chymotrypsin-like activities from the larval midgut of S. littoralis were effectively inhibited by MPI. We discuss these results with regard to the function and evolution of plant proteinase inhibitors. The availability of a plant proteinase inhibitor which is able to inhibit the two types of insect digestive proteinase, elastase and chymotrypsin, might be useful for engineering protection against lepidopteran insect pests in transgenic plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004250000258
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  • 6
    Electronic Resource
    Electronic Resource
    Fractal Properties of Fracture Surfaces in Steel 1045 (2000)
    Springer
    International journal of fracture 106 (2000), S. 21-26 
    Details
    ISSN: 1573-2673
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract In this work a study of the fractal properties of fracture surfaces in steel 1045 tested at different temperatures is performed. It is found that measured values of fractal dimension comply to a normal distribution; nevertheless the self-affine correlation length, ξ c , as well as other fracture parameters, possess notable variations with test temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022670017422
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  • 7
    Electronic Resource
    Electronic Resource
    Chemical Imaging of Phase-Separated Polymer Blends by Fluorescence Microscopy (2000)
    Springer
    Journal of fluorescence 10 (2000), S. 135-135 
    Details
    ISSN: 1573-4994
    Keywords: Fluorescence microscopy ; chemical imaging ; polymer blends
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Blends of poly(vinylacetate) (PVAc) and poly(cyclohexylmethacrylate) (PCHMA) labeled by copolymerization with 4-methacryloylamine-4′-nitrostilbene (Sb), with (1-pyrenylmethyl)methacrylate (Py), or with 3-(methacryloylamine)propyl-N-carbazole (Cbz) were prepared by casting dilute solutions in tetrahydrofurane (THF) or chloroform. Films about 10 μm thick were formed. Phase separation in two types of domains is observed by transmission optical microscopy (TOM) and epifluorescence microscopy (EFM): small craters of 1 to 10 μm placed at the polymer-air interface and larger domains, on the scale of 100 μm. The morphology of samples depends on the composition of the polymer blend and on solvent. The green fluorescence of Sb, the violet of Py, or the blue of Cbz provides imaging of the distribution of PCHMA in the different domains and in the matrix. It is thus observed that (i) superficial craters and large domains are formed mainly by PCHMA and (ii) the matrix is composed of PVAc in films cast from THF and it is a blend of the two polymers, homogeneous at the submicrometric scale, for chloroform. The emission intensity of Py, recorded by microfluorescence spectroscopy (MFS), yields a mapping similar to imaging detection. It is remarkable that in films cast from chloroform, the smaller domains are distributed with a 2D hexatic order disrupted by dislocations and disclinations, whereas in films cast from THF, a larger heterogeneity is found, denoting different mechanisms of solvent evaporation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009439024969
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  • 8
    Electronic Resource
    Electronic Resource
    High-density lipoproteins protect endothelial cells from apoptosis induced by oxidized low-density lipoproteins (2000)
    Springer
    Protoplasma 211 (2000), S. 198-206 
    Details
    ISSN: 1615-6102
    Keywords: Apoptosis ; Atherosclerosis ; Endothelium ; Lipoproteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Endothelial lesion by oxidized low-density liproproteins (LDL) is one of the first stages in the development of atherosclerosis. The effect of these lipoproteins can range from a functional lesion of the endothelium to death of the endothelial cells by apoptosis. High-density lipoproteins (HDL) are one of the factors which can have a protective effect against the development of atheromatous plaques. The aim of this study is to establish whether the death of endothelial cells by apoptosis induced by oxidized LDLs is prevented by HDLs. ECV304 endothelial cells and bovine aorta endothelial cells were incubated with native LDLs, oxidized LDLs, and a combination of both oxidized LDLs and HDLs. Oxidized LDLs caused a significant increase of mortality mainly by apoptosis. However, when HDLs were added together with oxidized LDLs the percentage of total mortality, the degree of lipoprotein oxidation in the medium, and the percentage of cells in apoptosis were all significantly decreased. HDLs protect against the cytotoxicity of oxidized LDLs possibly by preventing the propagation of the oxidative chain in these lipoproteins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01304487
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  • 9
    Electronic Resource
    Electronic Resource
    Symbolic object description of strata by segmentation trees (2000)
    Springer
    Computational statistics 15 (2000), S. 13-24 
    Details
    ISSN: 1613-9658
    Keywords: Key words: Tree-growing algorithm, segmentation tree, decision tree, information content measure, symbolic data analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Summary Based in a generalised recursive tree-building algorithm for populations partitioned into strata a method to obtain simple descriptions of strata is presented. Also strata with a common rule are obtained. Common predictors and criterion variable describe population in all strata or classes of individuals. Algorithm considers strata structure in tree-building algorithm and combines in each step maximisation of an information content measure for the criterion variable in a new binary partition of the population and selection of decisional nodes, based in quality of prediction for subsets of strata. Each decisional tree node is composed of a set of strata and a rule for individuals in these strata that will jointly explain the criterion variable. Symbolic data analysis fits the method. Input of the algorithm is composed of classes of individuals. Algorithm is extended to individuals described by probabilistic symbolic objects. As output, symbolic objects describe tree, decisional nodes and strata.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001800050032
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  • 10
    Electronic Resource
    Electronic Resource
    Synthesis of 2-Fluoro Analogues of Frontalin (2000)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1387-1389 
    Details
    ISSN: 1434-193X
    Keywords: Natural products ; Epoxidations ; Asymmetric synthesis ; Fluorine ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The synthesis of enantiomerically and diastereomerically pure (-)-(1R,2R,5R)- and (-)-(1R,2S,5R)-2-fluoro frontalin (7) starting from (+)-(1S)-menthyl-(R)-toluene-4-sulfinate, methylmagnesium bromide, methyl fluoroacetate, 4-pentenyl bromide and diazomethane is described. The absolute stereochemistry was unambiguously determined by X-ray analysis of (+)-(1S,2R,5S,RS)-5, an intermediate in the synthesis of the enantiomeric (+)-(1S,2R,5S)-2-fluoro frontalin (7).
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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