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  • Articles: DFG German National Licenses  (2)
  • Chemistry  (1)
  • Mutation induction  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Current genetics 12 (1987), S. 471-474 
    ISSN: 1432-0983
    Keywords: Aspergillus nidulans ; Mutation induction ; Mutagen dose ; Mutant yield
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Since the yield of mutants per surviving cell increases in general with increasing dose of mutagen, it has often been concluded in the literature that it is the most efficient to apply high mutagen doses so that most spores are killed. As high doses of mutagen produce chromosome rearrangements and unnoticed mutations which disturb the genetic background, the relationship between mutant frequency and survival was analyzed with Aspergillus nidulans as a model. It is shown that for different types of mutants the highest mutant yield is obtained at low mutagen doses (20–50% survival). Mutant frequency increases with increasing dose of mutagen but levels off and even decreases at higher dosages. There is no simple linear relationship between mutant frequency and the logarithm of the mutagen dose or the logarithm of the surviving fraction. If appropriate enrichment procedures are also available auxotrophic mutants can best be isolated at low doses of mutagen. Taking into account the disturbance of the genetic background, mutation induction should be done preferentially at a survival level of at least 70%.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 14 (1972), S. 685-714 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Characterization of proteolytic activity in preparations or fermentation broth is accomplished by methods based on a combination of disc electrophoresis and visualization of the activity. The methods permit a direct, comparison with reference preparations. All alkaline proteases studied, including the three subtilisins, were found to consist of several proteolytic components. The zymograms of the subtilisin type preparations show an irregular pattern. At least 14 different components may be observed, belonging to 6 types of mobility pattern, 3 of which could be assigned to the subtilisins. None of the components belongs to the group of metalloproteases. A quite regular pattern is shown by the zymogram of protease preparations produced by the alkalophilic Bacillus strains.A few of the components of the subtilisin preparations Maxatase and protease A were isolated by preparative disc electrophoresis and by disc electrofococusing, allowing a further characterization. Special attention was directed to the determination of properties specific for the application of subtilisins as additives in household detergents. Thermostability in sodium tripolyhosphate solution was found to range from about 10% for one of the minor components to 80% for the main component of Maxatase. Three types of curves representing the effect of pH on the activity were observed. The curve of the main component of Maxatase shows a characteristic shape with a maximum at pH 10.3: with other components lower pH optima were observed. Isoelectric points of the component were found to range from pH 7 to 10.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
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