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  • 1980-1984  (5)
  • 1
    Electronic Resource
    Electronic Resource
    Palisa catena: Small volcano chains in the western part of the central highlands (1983)
    Springer
    Earth, moon and planets 28 (1983), S. 23-27 
    Details
    ISSN: 1573-0794
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The morphology of a series of highland volcanoes found on the floor of the crater Palisa is similar to that of mare volcanoes. The superposition of the cones and craters indicate that this volcano complex had a complex, multiphase history of development. A blanket of relatively dark ash, which is between 4 and 13 km wide, is observed surrounding these volcanoes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01371668
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Linear crater chains: Indication of a volcanic organ (1983)
    Springer
    Earth, moon and planets 28 (1983), S. 87-107 
    Details
    ISSN: 1573-0794
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A mathematical investigation of the alignment of the craters of the four best preserved lunar linear crater chains, which lack the characteristics expected if they were of secondary impact origin, shows that, first, the craters lie along the distinct lines with very small deviations. This suggests that the craters were formed along deep crustal fissures. Second, the strikes of the lines or fissures indicate that they are reactivated lunar grid system structures. Third, the morphology of the craters is similar to that of volcanic diatremes. These results, especially the excellent geometric alignment of the craters along the lines, all indicate that these linear crater chains are of volcanic origin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01371675
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Presence of the molybdenum-cofactor in nitrate reductase-deficient mutant cell lines of Nicotiana tabacum (1981)
    Springer
    Molecular genetics and genomics 181 (1981), S. 395-399 
    Details
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Nicotiana tabacum mutant cell cultures lacking nitrate reductase activity were assayed for the presence of the molybdenum-cofactor using its ability to restore NADPH-nitrate reductase activity in extracts of Neurospora crassa nit-1 mycelia. The molybdenum-cofactor of the tobacco wild-type line was shown to complement efficiently the N. crassa nit-1 mutant in vitro. The molybdenum-cofactor seems to exist in a bound form, as acid-treatment was required for release of cofactor activity. Molybdate (5–10 mM), ascorbic acid, and anaerobic conditions greatly increased the activity of the cofactor, demonstrating its high lability and sensitivity to oxygen. Similar results were obtained with two tobacco nia mutants, which are defective in the apoprotein of nitrate reductase. The four cnx mutants studied were shown to contain exclusively an inactive form of the molybdenum-cofactor. This inactive cofactor could be reactivated in vitro and in vivo by unphysiologically high concentrations of molybdate (1–10 mM), thereby converting the cnx cells into highly active cofactor sources in vitro, and restoring nitrate reductase and xanthine dehydrogenase in vivo to partial acitivity. Thus the defect of the cnx mutants resides in a lack of molybdenum as a catalytically active ligand metal for the cofactor, while the structural moiety of the cofactor seems not to be impaired by the mutation. The subunit assembly of the nitrate reductase was found to be independent of the molybdenum content of the cofactor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00425618
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    In vitro reconstitution of NADH: nitrate reductase in nitrate reductase-deficient mutants of barley (1984)
    Springer
    Molecular genetics and genomics 197 (1984), S. 358-362 
    Details
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In vitro complementation of the nitrate reductase-deficient barley mutant nar2a extracts with molybdenum cofactor from commercial xanthine oxidase resulted in reactivation of NADH: nitrate reductase activity. Maximum reactivation was achieved with 7.5 μg/ml xanthine oxidase (final concentration), 10 mM glutathione (final concentration) and incubation for 30 min at room temperature (ca. 25°C). This in vitro complementation assay was used to determine the presence of functional apoprotein and molybdenum cofactor in 12 nitrate reductase-deficient barley mutants. Extracts of all nar1 alleles contained functional molybdenum cofactor (complemented with nar2a) but they lacked functional apoprotein (did not complement with molybdenum cofactor from xanthine oxidase). The nar2a, nar3a and nar3b extracts were able to donate functional apoprotein, but were poor sources of functional molybdenum cofactor. These data are in agreement with our previous assignment of nar1 to the barley NADH: nitrate reductase structural locus and nar2 and nar3 to molybdenum cofactor functions. Wild type cv. Steptoe barley seedlings grown in the absence of nitrate and lacking nitrate reductase activity contained low levels of molybdenum cofactor. Nitrate induction resulted in a several-fold increase in the measurable molybdenum cofactor levels that was correlated with the increase in nitrate reductase activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00329929
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  • 5
    Electronic Resource
    Electronic Resource
    Genetic analysis of nitrate reductase-deficient tobacco plants regenerated from mutant cells (1983)
    Springer
    Molecular genetics and genomics 192 (1983), S. 275-281 
    Details
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Fifteen nitrate reductase (NR)-deficient mutants that had been selected from amphihaploid cell cultures of Nicotiana tabacum and regenerated to fertile amphidiploid plants were genetically analyzed through crosses. All the 15 mutants proved to be allelic. Segregation among F2 progeny from crosses between mutant and wild-type plants and among testcross progeny showed the regenerated plants to be homozygous double mutants. The NR deficiency is conferred by two unlinked recessive nuclear mutations, which thus define a pair of duplicate loci (nia1 nia2). These loci were identified as the structural genes for the apoprotein of NADH-NR. — Two mutants (Nia28, Nia30) were characterized further. Both Nia28 and Nia30 plants had less than 2% of wild-type NR activity, were resistant to chlorate and incapable of sustained growth on nitrate or in soil. However, they grew normally on media containing ammonium succinate (with or without nitrate). Growth test showed that Nia28 seedlings do not utilize nitrate, whereas Nia30 seedlings utilize nitrate at a very small rate. — The examination of single mutants (nia1-28/28 and nia2-28/28) revealed that either of the two loci is able to produce wild-type levels of NR activity. NR activity and chlorate sensitivity respond to nia + gene dosage only at the very early seedling stage. At later developmental stages, both the basal and the nitrate induced levels of NR activity were found to be independent of the number of nia + genes, indicating complete compensation of gene dosage effects by regulatory mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00327678
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    Paper (German National Licenses)
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