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  • 1
    Electronic Resource
    Electronic Resource
    Dynamics of microbial populations in soil: Indigenous microorganisms degrading 2,4-dinitrophenol (1989)
    Springer
    Microbial ecology 18 (1989), S. 285-296 
    Details
    ISSN: 1432-184X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The mineralization of 2,4-dinitrophenol (DNP) and changes in the DNP-mineralizing population over a wide range of DNP concentrations were monitored to evaluate the dynamics of the DNP-mineralizing populations in two soils (soils 1 and 2). Curves of CO2 evolution were analyzed using nonlinear regression analysis and models incorporating parameters for population size and growth rate. The results of these analyses were compared to independent estimates of the DNP-mineralizing population from most-probable-number (MPN) determinations. The combined results of these analyses showed that 0.1μg of DNP g−1 of soil was too low a concentration to support maintenance or growth of the DNP-mineralizing population, whereas all higher concentrations supported either maintenance or growth of the population in soil 1. Independent estimates of population size showed good agreement between the nonlinear regression and MPN techniques, especially at initial DNP concentrations below 100μg g−1. Estimates of both population size and maximum specific growth rate varied with concentration, possibly indicating the existence of two different DNP-mineralizing populations in soil 1. In the other soil tested (soil 2), the population of DNP-mineralizers was much lower than in the first soil, and no evidence of two populations was obtained. In soil 2, good agreement between the nonlinear regression and MPN estimates of population size was also obtained. Results of this study demonstrate the power of using testable models of population dynamics to obtain useful estimates of parameters of microbial growth and survival in soil.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02075815
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  • 2
    Electronic Resource
    Electronic Resource
    Interactions of bacteria and microflagellates in sequencing batch reactors exhibiting enhanced mineralization of toxic organic chemicals (1992)
    Springer
    Microbial ecology 23 (1992), S. 127-142 
    Details
    ISSN: 1432-184X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Community level interactions were studied in non-axenic sequencing batch reactors (SBRs) being used to treat 2,4-dinitrophenol (DNP). Increasing the influent DNP concentrations from 1 to 10 µg ml−1 eliminated large predatory organisms such as rotifers and ciliated protozoa from the SBRs. Under steady-state conditions at a DNP concentration of 10 µg ml−1, supplemental additions of glucose enhanced DNP degradation and led to the establishment of a microbial community consisting of five species of bacteria and a variety of microflagellates. The bacteria and flagellates exhibited oscillating population dynamics in this system, possibly indicating predator-prey interactions between these two groups. Only two of the five bacteria isolated from this system could utilize glucose as a growth substrate, and one of these two species was the only organism that could mineralize DNP in the system. The other three bacteria could grow using metabolic by-products of one of the glucose-utilizing strains (Bacillus cereus) found in the reactors. Supplemental glucose additions increased the average size of bacterial floc particles to 172 µm, compared with 41 µm in SBRs not receiving glucose. It is theorized that the enhanced mineralization of DNP in this non-axenic system was attributable to increased community interactions resulting in increased bacterial flocculation in SBRs receiving supplemental glucose additions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00172635
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  • 3
    Electronic Resource
    Electronic Resource
    Effects of low-dose atenolol on postural and postprandial changes in heart rate, blood pressure, venous plasma catecholamines, and plasma renin activity (1989)
    Springer
    European journal of clinical pharmacology 37 (1989), S. 121-125 
    Details
    ISSN: 1432-1041
    Keywords: atenolol ; food intake ; catecholamines ; plasma renin activity ; blood pressure ; healthy volunteers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The administration of a single dose of atenolol 50 mg 1 h before a standard 3100 kJ cold meal in fasting healthy subjects reduced the supine preprandial heart rate and systolic blood pressure, and blunted the postural and postprandial rises in mean heart rate and systolic blood pressure relative to placebo. It did not affect the preprandial supine diastolic blood pressure, nor the postural rise and postprandial drop in diastolic blood pressure. Preprandial administration of atenolol blunted the postural and postprandial rises in mean plasma renin activity, and it enhanced the rise in plasma noradrenaline during eating in the sitting position, and the postprandial concentrations of noradrenaline. The findings do not permit the conclusion that beta1-adrenergic stimulation was the predminant cause of these atenolol-responsive changes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00558218
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  • 4
    Electronic Resource
    Electronic Resource
    Accumulation of unsulphated precursors inDictyostelium discoideum during selenate inhibition of growth (1993)
    Springer
    Molecular and cellular biochemistry 126 (1993), S. 109-114 
    Details
    ISSN: 1573-4919
    Keywords: Dictyostelium discoideum ; sulphation ; selenate ; precursors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Incubation ofDictyostelium discoideum cells with selenate is known to inhibit vegetative growth. In this paper we show that in the presence of selenate macromolecules accumulate which can be converted to sulphated products once the selenate is removed. The presence of cycloheximide, an inhibitor of protein synthesis, during the subsequent incubation does not prevent this conversion but tunicamycin, an inhibitor of glycosylation does. It is concluded that, in the presence of selenate, precursors accumulate as unglycosylated proteins, suggesting that feedback inhibition of glycosylation may be operated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00925688
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  • 5
    Electronic Resource
    Electronic Resource
    Production of lactic acid from wastepaper as a cellulosic feedstock (1997)
    Springer
    Journal of industrial microbiology and biotechnology 18 (1997), S. 10-14 
    Details
    ISSN: 1476-5535
    Keywords: Keywords: lactic acid; simultaneous saccharification and fermentation; biomass; cellulose; xylose; wastepaper
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Lactic acid promises to be an important commodity chemical in the future as a monomer for the production of biodegradable polylactic acid (PLA). As the demand for lactic acid increases, the need to explore alternative feedstock sources and process options that are inexpensive and efficient is bound to gain importance. This paper reports the results of a study of the production of lactic acid from wastepaper as a representative cellulosic feedstock, using a batch, bench-scale simultaneous saccharification and fermentation (SSF) process. The effect on process performance of operating parameters such as pH, temperature, enzyme loading, solids concentration, and enzyme preparation has been examined. A lactic acid product yield of 84% of theoretical was achieved at a solids loading of 5%, using 25 filter paper units (FPU) of cellulase per gram of cellulose, at 45°C and pH 5.0. The pH and temperature of operation have been selected to achieve good performance of both the cellulase and the microoganism in the SSF process. Our studies show that a feedstock such as wastepaper offers considerable promise and opportunity in the future for development of a biomass-based process for lactic acid production.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/sj.jim.2900339
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  • 6
    Electronic Resource
    Electronic Resource
    Catabolism of 2,7-dichloro- and 2,4,8-trichlorodibenzofuran by Sphingomonas sp strain RW1 (1999)
    Springer
    Journal of industrial microbiology and biotechnology 23 (1999), S. 359-363 
    Details
    ISSN: 1476-5535
    Keywords: Keywords: biotransformation; Sphingomonas; 2,7-dichlorodibenzofuran; 2,4,8-trichlorodibenzofuran; 6-chloro-2-methyl-4H-chromen-4-one; 7-chloro-2-methyl-4H-chromen-4-one; 6,8-dichloro-2-methyl-4H-chromen-4-one
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Due to their physicochemical and toxicological properties, polychlorinated dibenzofurans are regarded as a class of compounds providing reason for serious environmental concern. While the nonhalogenated basic structure dibenzofuran is effectively mineralized by appropriate bacterial strains, its polychlorinated derivatives are not. To elucidate the ability of the strain Sphingomonas sp RW1 to metabolize some of these chlorinated derivatives, we performed turnover experiments using 2,7-dichloro- and 2,4,8-trichlorodibenzofuran. As indicated by the oxygen-uptake rates determined for these two chlorinated dibenzofurans, Sphingomonassp RW1 can catabolize these chlorinated dibenzofurans yielding small quantities of oxidation products, which we isolated and subsequently characterized employing GC/MS and 1H- as well as 13C-NMR spectroscopy. In the case of 2,7-dichlorodibenzofuran, two metabolites accumulated, which we identified as 6-chloro- and 7-chloro-2-methyl-4H-chromen-4-one. The single metabolite isolated from the turnover experiments performed with 2,4,8-trichlorodibenzofuran was unequivocally identified as 6,8-dichloro-2-methyl-4H-chromen-4-one.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/sj.jim.2900739
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  • 7
    Electronic Resource
    Electronic Resource
    New palaeomagnetic data from Central Iran and a Triassic palaeoreconstruction (1996)
    Springer
    Geologische Rundschau 85 (1996), S. 293-302 
    Details
    ISSN: 0016-7835
    Keywords: Key words Iran ; palaeomagnetism ; Triassic ; Cretaceous ; Central Iran ; geotectonics ; palaeoreconstruction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  New pole positions for Triassic and Cretaceous times have been obtained from volcanic and sedimentary sequences in Central Iran. These new results confirm the general trend of the Apparent Polar Wander Path (APWP) of the Central-East-Iran microplate (CEIM) from the Triassic through the Tertiary as published by Soffel and Förster (1983, 1984). Two new palaeopoles for the Triassic of the CEIM have been obtained; limestones and tuffs from the Nakhlak region yield a mean direction of 094.0°/25.0°, N=12, k=4.1, α95=24.7°, after bedding correction, corresponding to a palaeopole position of 310.8°E; 3.9°S, and volcanic rocks from the Sirjan regions yield a mean direction of 114.5°/35.1°, N=44, k=45.9, α95=3.2° after bedding correction and a palaeopole position of 295.8°E; 10.3°N. Combining these with the two previously published results yields a new palaeopole position of 317.5°E; 12.7°N, for the Triassic of the CEIM, thus confirming that large counterclockwise rotations of the CEIM have occurred since the Triassic time. New results have also been obtained from Cretaceous limestones from the Saghand region of the CEIM. The mean direction of 340.7°/26.3°, N=33, k=44.3, α95=3.8°, and the corresponding palaeopole position of 283.1°E; 64.4°N, is in agreement with previously determined Cretaceous palaeopole positions of the CEIM. Furthermore, results have also been obtained from Triassic dolomite, limestone, sandstone and siltstone from the Natanz region, which is located to the west of the CEIM. A total of 161 specimens from 44 cores taken at five sites gave a mean direction of the five sites at 033.3°/25.1°, N= 5, k=69.0, α95=9.3° and a palaeopole position of 167.2°E; 53.7°N. They pass the positive fold test of McElhinny (1964) on the level of 99% confidence. This pole position is in fairly good agreement with the mean Triassic pole position of the Turan Plate (149°E; 49°N). It indicates that the area of Natanz has not undergone the large counterclockwise rotation relative to the Turan plate since the Triassic, which has been shown for the CEIM. A Triassic palaeogeographic reconstruction of Iran, Arabia (Gondwana) and the Turan Plate (Eurasia) is also presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s005310050075
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  • 8
    Electronic Resource
    Electronic Resource
    New palaeomagnetic data from Central Iran and a Triassic palaeoreconstruction (1996)
    Springer
    International journal of earth sciences 85 (1996), S. 293-302 
    Details
    ISSN: 1437-3262
    Keywords: Iran ; palaeomagnetism ; Triassic ; Cretaceous ; Central Iran ; geotectonics ; palaeoreconstruction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract New pole positions for Triassic and Cretaceous times have been obtained from volcanic and sedimentary sequences in Central Iran. These new results confirm the general trend of the Apparent Polar Wander Path (APWP) of the Central-East-Iran microplate (CEIM) from the Triassic through the Tertiary as published by Soffel and Förster (1983, 1984). Two new palaeopoles for the Triassic of the CEIM have been obtained; limestones and tuffs from the Nakhlak region yield a mean direction of 094.0°/25.0°, N=12, k=4.1,α 95=24.7°, after bedding correction, corresponding to a palaeopole position of 310.8°E; 3.9°S, and volcanic rocks from the Sirjan regions yield a mean direction of 114.5°/35.1°, N=44, k=45.9,α 95=3.2° after bedding correction and a palaeopole position of 295.8°E; 10.3°N. Combining these with the two previously published results yields a new palaeopole position of 317.5°E; 12.7°N, for the Triassic of the CEIM, thus confirming that large counterclockwise rotations of the CEIM have occurred since the Triassic time. New results have also been obtained from Cretaceous limestones from the Saghand region of the CEIM. The mean direction of 340.7°/26.3°, N=33, k=44.3,α 95=3.8°, and the corresponding palaeopole position of 283.1°E; 64.4°N, is in agreement with previously determined Cretaceous palaeopole positions of the CEIM. Furthermore, results have also been obtained from Triassic dolomite, limestone, sandstone and siltstone from the Natanz region, which is located to the west of the CEIM. A total of 161 specimens from 44 cores taken at five sites gave a mean direction of the five sites at 033.3°/25.1°, N=5, k=69.0,α 95=9.3° and a palaeopole position of 167.2°E; 53.7°N. They pass the positive fold test of McElhinny (1964) on the level of 99% confidence. This pole position is in fairly good agreement with the mean Triassic pole position of the Turan Plate (149°E; 49°N). It indicates that the area of Natanz has not undergone the large counterclockwise rotation relative to the Turan plate since the Triassic, which has been shown for the CEIM. A Triassic palaeogeographic reconstruction of Iran, Arabia (Gondwana) and the Turan Plate (Eurasia) is also presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02422235
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  • 9
    Electronic Resource
    Electronic Resource
    Variation in competitive abilities of plants and microbes for specific amino acids (1999)
    Springer
    Biology and fertility of soils 29 (1999), S. 257-261 
    Details
    ISSN: 1432-0789
    Keywords: Key words Alpine nitrogen cycle ; Amino acids ; Kobresia myosuroides ; Organic nitrogen ; Plant-microbe competition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  Microbes are assumed to possess strong competitive advantages over plants for uptake of nutrients from the soil. The finding that non-mycorrhizal plants can obtain a significant fraction of their N requirement from soil amino acids contradicts this assumption. The amino acid glycine (Gly) has been used as a model amino acid in many recent studies. Our preliminary studies showed that Gly was a poor substrate for microbial growth compared to other amino acids. We tested the hypothesis that the alpine sedge Kobresia myosuroides competes better for Gly than for other amino acids because of decreased microbial demand for this compound. Soil microbial populations that could grow using Gly as a sole carbon source were about 5 times lower than those that could grow on glutamate (Glu). Gly supported a significantly lower population than any of the ten other amino acids tested except serine. In contrast, K. myosuroides took up Gly from hydroponic solution at faster rates than Glu. In plant-soil microcosms, plants competed with soil microbes 3.25 times better for Gly than for Glu. We conclude that the low microbial demand and the rapid plant uptake of Gly relative to other amino acids allow Gly to be an especially important nitrogen source for K. myosuroides.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050550
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  • 10
    Electronic Resource
    Electronic Resource
    Improvements in drug purity determination by capillary electrophoresis using UV-absorption and LIF-detection with a UV-laser (1997)
    Springer
    Chromatographia 44 (1997), S. 355-361 
    Details
    ISSN: 1612-1112
    Keywords: Capillary electrophoresis ; Drug purity ; Frequency doubled laser ; Laser induced fluorescence ; Reduced electromigration dispersion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In drug purity determinations by capillary electrophoresis using UV-detection generally a relative high concentration of the main compound has to be injected. Principles how to handle overloading effects are described. NXX-066 is a drug with a native fluorescence which made it possible to use of CE system equipped with a LIF-detection unit. Monitoring drug purity determination with LIF detection results in an improved limit of quantification of the impurities and/or opens a possibility to avoid an overloaded main peak. A frequency doubled (FRED) argon ion laser set at 244 nm was used as excitation source in drug purity determination with the LIF-detection unit and the chemicals used were therefore carefully chosen in order to minimize the background noise level, which easily is enhanced when fluorescence detection is performed in the UV-range. The separation of the fluorescent NXX-066 analogues proved to be a difficult task, but an adequate resolution was obtained when β- and γ-cyclodextrins was added as structural selectors and the separation window was expanded by the use of a repressed/reversed electroosmotic flow. A comparison of the separation capability for the UV-detection system and the laser induced fluorescence detection system was performed, showing that the overloading effects of the main peak can be removed using the CE-LIF system and thereby obtain a substantially improved resolution of the analogues. A comparison of LC-UV and CE-UV for drug purity determination of a crude product from, synthesis of NXX-066 is also included in this paper where a good correlation of the results were obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466310
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