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  • 1
    ISSN: 1432-0983
    Keywords: Penicillium chrysogenum ; Transformation ; trp ; Penicillin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We report here the development of an endogenous gene transfer system for the industrially-important Deuteromycete Penicillium chrysogenum, utilising a recombinant plasmid designated pPC-31 to complement a tryptophan — auxotrophic strain. Transformation frequencies in the order of 300–1800 transformants per μg DNA have been obtained, and Southern hybridisation analysis has demonstrated that in the majority of cases, integration is mediated by homologous recombination between pPC-31 and the host genome at the site of the resident mutant allele.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0983
    Keywords: Transcription control ; Penicillium chrysogenum ; Penicillin biosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The presence of a transcriptional control simultaneously affecting the expression of the three penicillin biosynthetic genes, pcbAB, pcbC, and penDE (pen genes), was demonstrated in Penicillium chrysogenum. Using probes specific to each gene, it was observed that the highest level of expression of the pen genes occurred during exponential growth, in both the original ancestral strain (NRRL1951) and a high-penicillin producing strain P2. Expression also occurred in the presence of high concentrations of glucose, indicating that carbon catabolite repression was not directly involved in the regulation. Transcription of the pen genes appeared to cease as the growth rate decreased. Growth was limited in a fermenter by the rate of oxygen transfer. The phosphoglycerate kinase gene (pgk), used as a control, was strongly induced by the reduced oxygen levels, suggesting a stress-related response. By maintaining optimum growth conditions in fermenters, no induction of the pgk gene was observed whereas expression of the pen genes could be maintained. It was also possible to re-establish expresion of the pen genes, after normal cessation, by the addition of cycloheximide to the culture medium.
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  • 3
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Mutants sensitive to far ultraviolet light (UV) and 4-nitroquinoline-1-oxide (4NQO) have been isolated from Penicillium chrysogenum NRRL 1951. Two strains HP500 and HP508 are examined in detail. Their cross sensitivity to and altered mutation by UV and 4NQO suggests that damage caused by both agents is repaired through similar pathways in Penicillium chrysogenum. Strain HP500 is refractive to UV and 4NQO mutagenesis and is likely to be defective in an error-prone mechanism of repair. Mutation by N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) in HP500 is also reduced, indicating involvement of an error-prone UV repair process in MNNG mutagenesis in Penicillium chrysogenum. Strain HP508 shows an increase of forward mutation rate up to 4.5 times over that of the wild-type, when compared at similar surviving fractions and is also hypermutable by 4NQO. The repair defect present in strain HP508 has been demonstrated by its inability to remove DNA sites sensitive to single strand specific nuclease during post-irradiation incubation of protoplasts.
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  • 4
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary High molecular weight DNA extracted from Penicillium chrysogenum has been fractionated using RPC-5 Analog, into three distinct types designated 1, 2 and 3. Types 1 and 2 have the same buoyant density of 1.710 g/cm3 and together appear to comprise the nuclear DNA. Type 1 is enriched for repeated sequences which are normally observed in restriction digests of P. chrysogenum total DNA. Conversely, type 2 appears to be composed entirely of non-repetitive sequences. Type 3 has been identified as mitochondrial DNA, having a buoyant density of 1.695 g/cm3 and an estimated molecular weight of 31.6×106 Daltons.
    Type of Medium: Electronic Resource
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