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  • Articles  (40)
  • Chemistry  (30)
  • Kloeckera sp. 2201  (4)
  • Liquid chromatography  (4)
  • General Chemistry  (3)
  • Methanol  (3)
  • Actinorhizas
  • Gonadotrops
  • Seismology
  • 2000-2004
  • 1980-1984  (24)
  • 1940-1944  (6)
  • 1935-1939  (10)
  • 1983  (6)
  • 1982  (18)
  • 1943  (6)
  • 1937  (10)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 131 (1982), S. 174-175 
    ISSN: 1432-072X
    Keywords: Hansenula polymorpha ; Kloeckera sp. 2201 ; Methanol ; Glucose ; Methanol dissimilating enzymes ; Regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A comparative study was made of the regulation of the synthesis of methanol dissimilating enzymes inkloeckera sp. 2201 andHansenula polymorpha using chemostat and batch growth conditions and methanol or glucose as carbon sources. During growth in methanol-limited chemostat cultures similar enzyme patterns for alcohol oxidase, catalase, formaldehyde dehydrogenase and formate dehydrogenase in the two yeasts were found. When growing in batch culture with glucoseH. polymorpha, but notKloeckera sp. 2201, was found to produce ethanol which might affect the synthesis of these enzymes.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 233 (1983), S. 377-388 
    ISSN: 1432-0878
    Keywords: Gonadotrops ; Gonadotropin secretion ; Steroids ; Brain-pituitary-gonadal axis ; Juvenile teleost
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In a cytophysiological study it was investigated whether in juvenile trout gonadal steroids stimulate the gonadotropic (GTH)-cells directly or indirectly via the brain. Pituitaries of donor animals were transplanted into the caudal musculature of testosterone-treated and non-testosterone-treated host fish. Testosterone treatment caused an increase in GTH-content in the in situ pituitaries and in the grafts. Accordingly, the gonadotrops displayed ultrastructural changes such as the appearance of well-developed Golgi systems and large globules. The stimulation of the morphological development of gonadotrops and of synthesis and storage of GTH in the allografted pituitaries indicates that testosterone affects the GTH-cells directly. In untreated juvenile trout the gonadotropin content of the pituitary and the gonadotropin concentration in the plasma vary with the time of year. This variation and the role of testosterone and gonadotropin-releasing hormone on the release of GTH are discussed.
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  • 3
    ISSN: 0365-9631
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 4
    ISSN: 1432-072X
    Keywords: Hansenula polymorpha ; Kloeckera sp. 2201 ; Mixed substrate utilisation ; Chemostat ; Induction ; Repression ; Methanol ; Glucose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The growth of Hansenula polymorpha and Kloeckera sp. 2201 with a mixture of glucose and methanol (38.8%/61.2%, w/w) and the regulation of the methanol dissimilating enzymes alcohol oxidase, catalase, formaldehyde dehydrogenase and formate dehydrogenase were studied in chemostat culture, as a function of the dilution rate. Both organisms utilized and assimilated glucose and methanol simultaneously up to dilution rates of 0.30 h-1 (H. polymorpha) and 0.26h-1, respectively (Kloeckera sp. 2201) which significantly exceeded μmax found for the two yeasts with methanol as the only source of carbon. At higher dilution rates methanol utilisation ceased and only glucose was assimilated. Over the whole range of mixed-substrate growth both carbon sources were assimilated with the same efficiency as during growth with glucose or methanol alone. In cultures of H. polymorpha, however, the growth yield for glucose was lowered by the unmetabolized methanol at high dilution rates. During growth on both carbon sources the repression of the synthesis of all catabolic methanol enzymes which is normally caused by glucose was overcome by the inductive effect of the simultaneously fed methanol. In both organisms the synthesis of alcohol oxidase was found to be regulated differently as compared to catalase, formaldehyde and formate dehydrogenase. Whereas increasing repression of the synthesis of alcohol oxidase was found with increasing dilution rates as indicated by gradually decreasing specific activities of this enzyme in cell-free extracts, the specific activities of this enzyme in cell-free extracts, the specific activities of catalase and the dehydrogenases increased with increasing growth rates until repression started. The results indicate similar patterns of the regulation of the synthesis of methanol dissimilating enzymes in different methylotrophic yeasts.
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  • 5
    ISSN: 1432-072X
    Keywords: Hansenula polymorpha ; Kloeckera sp. 2201 ; Chemostat ; Mixed substrates ; Glucose ; Methanol ; Growth yields ; Enzyme regulation ; Dissimilatory enzymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The influence of the composition of methanol/glucose-mixtures as only sources of carbon and energy on growth and regulation of the synthesis of enzymes involved in methanol-dissimilation was studied under chemostat conditions at a fixed dilution rate with the methylotrophic yeasts Hansenula polymorpha and Kloeckera sp. 2201. Both carbon sources were found to be utilized completely independently of the composition of the C1/C6 mixture. Using mixtures of 14C-labelled methanol and glucose the growth yield for glucose was found to be constant for all C1/C6-mixtures tested and both yeasts. The growth yield for methanol, however, was reduced by up to 25% when the proportion of methanol in the inflowing medium was lower than 20% (w/w with respect to glucose) for H. polymorpha and 50% (w/w with respect to glucose) for Kloeckera sp. 2201 respectively. During growth with C1/C6-mixtures containing higher C1-proportions of methanol regular growth yields for methanol were recorded which corresponded to the growth yields found with methanol as the only carbon source. The regulation of the synthesis of the enzymes of the dissimilatory pathway for methanol was found to be under multiple control. Although glucose was present in the medium methanol had a positive effect on the synthesis of these enzymes. Thus, in addition to derepression induction by methanol was also observed. This inductive effect was found to increase with increasing proportions of methanol in the mixture. Depending on the enzyme, 10–40% methanol in the mixture resulted in a maximal induction with enzyme specific activities equal to those found in cells grown with methanol as the only carbon source. No further enhancements in enzyme specific activities were observed during growth on mixtures containing more than 40% methanol.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 131 (1982), S. 95-101 
    ISSN: 1432-072X
    Keywords: Chemostat ; Nitrogen limitation ; Hansenula polymorpha ; Kloeckera sp. 2201 ; Carbon limitation ; Repression ; Methanol dissimilating enzymes ; Shift experiment ; Catabolite inactivation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The influence of nitrogen limitation on the regulation of the methanol oxidizing enzymes alcohol oxidase, catalase, formaldehyde dehydrogenase and formate dehydrogenase in the two methylotrophic yeastsHansenula polymorpha andKloeckera sp. 2201 was studied in continuous culture. When shifted from carbon-limited growth conditions (with a mixture of glucose and methanol as carbon sources) to a nitrogen-limited environment both cultures were found to go through a transition phase where neither enhanced residual concentrations of the nitrogen source nor of one of the two carbon sources could be detected in the supernatant. As soon as nitrogen became a limiting substrate an immediate reorganisation of the cell composition was initiated: protein content of the cells dropped to approximately 40% of its initial value, glycogen was synthesized and the enzyme composition of the cells was changed. The peroxisomal enzymes alcohol oxidase and catalase in both organisms and the two dehydrogenases for formaldehyde and formate in cells ofKloeckera sp. 2201 were subject to degradation (catabolite inactivation). The measured rates of inactivation indicated that in cells ofH. polymorpha this process might be limited to peroxisomes, whereas inKloeckera sp. 2201 the degradation was found to affect peroxisomal as well as cytoplasmic enzymes. In contrast to methanol dissimilating enzymes the net rate of synthesis of hexokinase, glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase was not affected by this process but those enzymes were synthesized with increased rates.
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  • 7
    ISSN: 1573-5036
    Keywords: Actinorhizas ; (Actinomycetes) ; Ecology ; Hippophaë ; (Mystiflora: Elaeagnaceae) ; Longidorus ; (Nematoda: Longidoridae) ; Nodulation ; Soil ; sterization ; Vegetational succession ; Tylenchorhynchus (Nematoda: Tylenchrohynchidae)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Hippophaë rhamnoides seedlings were grown in sterilized and unsterilized soil from a decliningH. rhamnoides scrub, to which different numbers ofLongidorus sp. andTylenchorhynchus microphasmis were added. In sterilized and unsterilized soil, retardation of growth, content of dry matter in the shoots, and incidence of deformed short lateral roots of test plants were positively correlated with counts of both nematode species. Nitrogen content in the shoots, nodulation on the roots of test plants and increase increase in nematodes were negatively correlated with the initial number of both nematode species in sterilized soil. In unsterilized soil, an unknown biotic factor was present that reduces growth ofH. rhamnoides, nodulation and multiplication of the nematodes. This factor seems to interact with the nematodes in reducing growth ofH. rhamnoides.
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  • 8
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 9
    ISSN: 1612-1112
    Keywords: Liquid chromatography ; Chlorophenols in water ; Preconcentration ; Post-column photochemical dechlorination ; Electrochemical, UV and fluorescence detection ; Column switching
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A specific HPLC method has been developed for the trace analysis of lower chlorinated aromatic compounds. The method consists of an on-line preconcentration and a post-column reaction step. On-line preconcentration of mono- and dichlorophenols from aqueous samples has been performed using PRP1, a divinylbenzene-styrene copolymeric sorbent as packing material for both pre-and analytical column. Enrichment factors of over 300 were obtained compared to regular (100 μl) loop injections, even for the highly polar monochlorophenols. After reversed-phase separation, post-column photochemical dechlorination is carried out directly in the eluent stream, using a photochemical reactor. Upon dechlorination, fluorescent products are formed, which can be detected selectively. The resulting fluorescence signal shows a linear response to the quantity of solute present over 2 to 3 orders of magnitude (correlation coefficients: 0.990–0.98). For the mono- and dichlorophenols, the detection limit of the photoconversion method is in the lower nanogram range. The method is especially suitable for the analysis of complex matrices such as effluent water samples or biological fluids containing traces of the polar chloroaromatic compounds together with large amounts of other constituents, which interfere when using more general methods of detection like UV absorption. The potential of this technique for automation has been demonstrated by using a microprocessor-controlled column switching unit.
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  • 10
    ISSN: 1612-1112
    Keywords: Liquid chromatography ; Photochemical reaction detection ; Chemical post-column reduction ; Fluorimetric detection ; Air segmented flow systems ; Non-aqueous reversed-phase chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new photochemical reaction method for the on-line fluorimetric detection of natural vitamin K homologs was developed. In addition to its high sensitivity, the method features an interesting selectivity for the determination of these compounds in a complex matrix such as human serum. The formation of different photolysis products as a function of reaction conditions, and the optimalisation of a segmented flow reaction system will be discussed. The results indicate that the method is 4 times more sensitive than UV detection, and at least as selective as fluorescence detection after post-column chemical reduction.
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