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  • etf Genes  (2)
  • Dynamic measurements  (1)
  • Springer  (3)
  • American Institute of Physics
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  • Springer  (3)
  • American Institute of Physics
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  • 1
    Electronic Resource
    Electronic Resource
    Bradyrhizobium japonicum possesses two discrete sets of electron transfer flavoprotein genes:fixA, fixB andetfS, etfL (1996)
    Springer
    Archives of microbiology 165 (1996), S. 169-178 
    Details
    ISSN: 1432-072X
    Keywords: Bradyrhizobium japonicum ; Electron transfer flavoprotein ; etf Genes ; fix Genes ; Nitrogen fixation ; Phylogenetic tree ; Protein family
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A group of four co-regulated genes (fixA, fixB, fixC, fixX) essential for symbiotic nitrogen fixation has been described in several rhizobial species, includingBradyrhizobium japonicum. The complete nucleotide sequence of theB. japonicum fixA, fixB andfixC, genes is reported here. The derived amino acid sequences confirmed the previously noted sequence similarity between FixA and the β-subunit and between FixB and the α-subunit of mammalian andParacoccus denitrificans electron transfer flavoproteins (ETF). Since the classical role of ETF is in β-oxidation of fatty acids, a process unrelated to nitrogen fixation, we rationalized thatB. japonicum ought to contain bona fideetf genes in addition to theetf-like genesfixA andfixB. Therefore, we identified, cloned, sequenced, and transcriptionally analyzed theB. japonicum etfSL genes encoding the β-and α-subunits of ETF. TheetfSL genes, but not thefix genes, are transcribed in aerobically grown cells. An amino acid sequence comparison between all available ETFs and ETF-like proteins revealed the existence of two distinguishable subfamilies. Group I comprises housekeeping ETFs that link acyl-CoA dehydrogenase reactions with the respiratory chain, such as in the fatty acid degradation pathway.B. japonicum EtfS and EtfL clearly belong to this group. Group II contains ETF-like proteins that are synthesized only under certain specific growth conditions and receive electrons from the oxidation of specific substrates. The products of the anaerobically inducedfixA andfixB genes ofB. japonicum are members of that group.B. japonicum is the first example of an organism in which genes for proteins of both groups I and II of the ETF family have been identified.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01692858
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Bradyrhizobium japonicum possesses two discrete sets of electron transfer flavoprotein genes: fixA, fixB and etfS, etfL (1996)
    Springer
    Archives of microbiology 165 (1996), S. 169-178 
    Details
    ISSN: 1432-072X
    Keywords: Key wordsBradyrhizobium japonicum ; Electron ; transfer flavoprotein ; etf Genes ; fix Genes ; Nitrogen ; fixation ; Phylogenetic tree ; Protein family
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A group of four co-regulated genes (fixA, fixB, fixC, fixX) essential for symbiotic nitrogen fixation has been described in several rhizobial species, including Bradyrhizobium japonicum. The complete nucleotide sequence of the B. japonicum fixA, fixB and fixC, genes is reported here. The derived amino acid sequences confirmed the previously noted sequence similarity between FixA and the β-subunit and between FixB and the α-subunit of mammalian and Paracoccus denitrificans electron transfer flavoproteins (ETF). Since the classical role of ETF is in β-oxidation of fatty acids, a process unrelated to nitrogen fixation, we rationalized that B. japonicum ought to contain bona fide etf genes in addition to the etf-like genes fixA and fixB. Therefore, we identified, cloned, sequenced, and transcriptionally analyzed the B. japonicum etfSL genes encoding the β- and α-subunits of ETF. The etfSL genes, but not the fix genes, are transcribed in aerobically grown cells. An amino acid sequence comparison between all available ETFs and ETF-like proteins revealed the existence of two distinguishable subfamilies. Group I comprises housekeeping ETFs that link acyl-CoA dehydrogenase reactions with the respiratory chain, such as in the fatty acid degradation pathway. B. japonicum EtfS and EtfL clearly belong to this group. Group II contains ETF-like proteins that are synthesized only under certain specific growth conditions and receive electrons from the oxidation of specific substrates. The products of the anaerobically induced fixA and fixB genes of B. japonicum are members of that group. B. japonicum is the first example of an organism in which genes for proteins of both groups I and II of the ETF family have been identified.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01692858
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Manifestation of phase separation processes in oscillatory shear: droplet-matrix systems versus co-continuous morphologies (1999)
    Springer
    Rheologica acta 38 (1999), S. 274-286 
    Details
    ISSN: 1435-1528
    Keywords: Key words Phase separation ; Rheology ; Polymer blends ; Dynamic measurements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract Phase separation processes in mixtures of poly-α-methylstyrene-co-acrylonitrile (PαMSAN) and poly-methylmethacrylate (PMMA) with lower critical solution temperature (LCST) behavior have been studied, focusing on the manifestation of the interface in oscillatory shear measurements. By using blends of different composition, systems with a droplet-matrix morphology or a co-continuous structure are generated during the phase separation process. The feasibility of probing this morphology development by rheological measurements has been investigated. The development of a disperse droplet phase leads to an increase in the elasticity of the blend at low frequency, showing up as a shoulder in the plot of storage modulus versus frequency. Here, the droplet growth is unaffected by the shear amplitude up to strains of 0.2; therefore the resulting dynamic data are suitable for quantitative analysis. In contrast, for blends in which phase separation leads to a co-continuous structure, the storage modulus shows a power law behavior at low frequency and its value decreases as time proceeds. For the latter systems, effects of the dynamic measurement on the morphology development have been observed, even for strain amplitudes as low as 0.01. To probe the kinetics of morphology evolution in droplet-matrix systems, measurements of the time dependence of the dynamic moduli at fixed frequency should be performed (for a whole series of frequencies). Only from such measurements, curves of the frequency dependence of the moduli at a well defined residence time can be constructed. From fitting these curves to the emulsion model of Palierne, the droplet diameter distribution at that particular stage in the phase separation and growth process can be obtained. It is not appropriate to use a simplified version of the Palierne model containing only the average droplet size, because a morphology with too broad a size distribution is generated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003970050179
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    Paper (German National Licenses)
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