ALBERT

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  • 1
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The comparative chromatographic investigations into the ribosomal proteins of various strains of E. coli have demonstrated that most of the strains including three strains of E. coli subsp. communior had ribosomes with the same protein compositions (C-type). The ribosomes from strain B are different from the C-type ribosomes in having the specific 30-4 (B) component in place of 30-4 (B-type), while those from strains K 12 may be distinguished from the type-C ribosomes by the presence of the specific 30-7 (K) component in place of 30-7 (K-type) or, in addition to 30-7 (K), the presence of 30-9 (W3637) in place of 30-9 (K-3637 type). Two strains, IAM 1132 and IAM 1182, have R-type ribosomes, in which at least six 50s proteins and four 30s protein components are distinct from the corresponding protein components in the C-type ribosomes.
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  • 2
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Methyl-methanesulfonate (MMS) causes gene conversions in heteroallelic diploids of Saccharomyces cerevisiae. The frequency of production of prototrophic convertants is linearly proportional to the square of the time of MMS treatment, and the regression of prototrophs on dose varies depending upon the particular pair of alleles present in the diploid. The regressions show an additivity relationship, in that when a triad of heteroallelic diploids of the type m1/m2, m2/m3, and m1/m3 is considered, two of the regressions add up approximately to the third. MMS can, therefore, be used in fine structure mitotic mapping of genes. Good agreement was found both in relative order and spacing of alleles at the histidine 1 locus of yeast when the fine structure map based on the X-ray mapping method was compared with that based on MMS.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Molecular genetics and genomics 107 (1970), S. 243-255 
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Stocks of coliphage P1 contain infective phage particles (P1), a smaller morphological variant (pP1) and single phage tails. In crude stocks and under certain conditions these particles form stable aggregates of four by adhesion of their base plates. It happens that all the aggregates of P1, pP1 and tails having densities above 1.41 g/cm3 are distributed around five values: 1.422, 1.435, 1.450, 1.459 and 1.473 g/cm3. Consequently they form five rather distinct bands when examined by analytical centrifugation. Formation and dissociation of tetramers results in loss and recovery of phage infectivity. Tetramers formed of four P1 particles have a sedimentation constant of 1,185 S as compared to 715 S for single P1 particles. Within the limits of our methods we could not detect any P1 or pP1 particles containing amounts of DNA different from 10−16 g and 4×10−17 g, respectively.
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  • 4
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A selective enrichment method based upon differential killing by thymine deprivation of inducible as compared to non-inducible lysogens was employed to isolate mutants of Escherichia coli K 12(λ)+ deficient in lysogenic induction. The efficiency of the method is such that about 1% of the surviving colonies are resistant to thymineless induction. About half of the mutants are recA recombination-deficient. Two other classes of non-inducible Rec+ mutants can be distinguished. No temperature conditional bacterial mutations could be obtained. Our results demonstrate that deficiency in the recA gene product is not the only bacterial factor which prevents lysogenic induction.
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  • 5
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Comparative investigations concerning the action of streptomycin (SM) and dihydrostreptomycin (DHSM) on human chromosomes in vitro revealed a strong effectivity of SM in inducing achromatic lesions (AL) while DHSM is ineffective in this respect. Chromatid breaks (B′) and isochromatid breaks (B″) are not induced by the two streptomycins. Chromatid translocations (RB') were found only 3 times in all concentrations tested. The intrachromosomal distribution of the streptomycin-induced AL is very similar to the distribution of AL induced with the alkylating agent Chinon I and the thioxanthon derivative Miracil D. The view is discussed that the appearance of achromatic lesions cannot be interpreted as an indicator for a mutagenic activity of an agent.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Molecular genetics and genomics 108 (1970), S. 41-46 
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Actinomycin sensitive mutants of E. coli K12 have been isolated and shown to have pleiotropic defects in the fermentation of sugars. The locus of a gene controlling actinomycin resistance is very close to that of the lactose gene.
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  • 7
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Erythromycin inhibits the growth of wild type Paramecia and eventually kills the cells. 24 erythromycin resistant mutants (22 U.V. induced, 2 spontaneous) have been isolated. They fall into att least three phenotypic classes on the basis of their level of resistance and of thermosensitivity. Genetic analysis of three mutants shows that the resistance character is cytoplasmically inherited, as evidenced by its clonal inheritance, its transfer through cytoplasmic bridges and its non-segregation at meiosis. The results suggest that these mutants may be mitochondrial mutants analogous to those described in yeast.
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  • 8
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 9
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Effects of metabolic inhibitors on the rejoining of broken single strands of DNA of mouse L cells induced by X-irradiation were studied by the sucrose gradient sedimentation method. Inhibitors of protein and DNA syntheses, such as cycloheximide and 5-fluorodeoxyuridine, could not suppress the rejoining of broken strands, when they were introduced into cultures at the time of irradiation. However, 2.5-hour pretreatment of cells with 5-fluorodeoxyuridine was capable of reducing the rate of rejoining. In addition, proflavin, one of DNA-binding substances tested, prevented the rejoining. These results suggest that pre-existing DNA-related enzymes, for instance, DNA polymerase and ligase, are responsible for the process.
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  • 10
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Streptomycin sensitive (ss) revertants were obtained from the streptomycin dependent mutant sd 3 by transfer to streptomycin-free medium. Contrary to ss-wildtype cells these ss-revertants were able to form new sd-colonies on streptomycin-medium. These secondary sd-cells were identical with the original sd 3-mutant. The frequency of formation of the secondary sd-colonies was different, it varied depending on the revertant strain from 0 to the remarkable number of 10−2. With increasing length of cultivation of the ss-revertants the capability of producing sd-cells decreased continuously. Finallym after 8 weeks the zero value was reached. The rate of decrease was depending on the revertant strain. These results show, that most of the newly formed revertants in addition to ss-information copies still possessed sd-copies which were segregating in the process of cell-division and producing secondary sd-colonies on streptomycin-medium. The sd-information is present in numerous copies; proved through the variable frequency of formation, the variable rate of decrease of sd-formation and the undiminished amount of segregation after cloning. Sager and Ramanis have shown that the genes of the single chloroplasts of the Chlamydomonas-cell are present only in two copies. The sd 3-information is located on the more numerous mitochondria if the statement of Sager and Ramanis proves to be true for the vegetative cells in principle.
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