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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 129 (1972), S. 447-454 
    ISSN: 1432-0878
    Keywords: Nucleoli ; Polyamines ; Nuclear ; Polycations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Structural alterations of the nucleoli of rat liver cells were noted when these nuclei were isolated with spermidine or spermine rather than magnesium. When 5–10 mM spermidine or spermine were used to isolate the nuclei, the nucleoli were a) larger, b) contained numerous and sometimes large lacunae, and c) were less aggregated and had prominent chromatin caps. These chromatin caps gave the nucleolus a ring-shaped appearance in the light microscope. These findings, coupled with physiological data that indicate that polyamines enhance nucleolar RNA polymerase activity (Russell et al., 1971), suggest that spermidine and spermine may be involved in the control of ribosomal RNA synthesis. To our knowledge, this is the first instance of the direct stimulation of ribosomal RNA synthesis during nuclear isolation.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 120 (1971), S. 321-331 
    ISSN: 1432-0878
    Keywords: Liver Cells Polyamines ; Xenopus laevis ; Autoradiography ; RNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The distributions of 3H-putrescine and 3H-uridine were studied autoradiographically in cultured Xenopus laevis liver cells. Biochemical assay showed that at 4 h 10%, and at 24 h 30 % of the putrescine label was recovered as spermidine. Grain counts per unit surface area in light microscopic autoradiographs indicate that the 3H-polyamines show a similar intranuclear accumulation as 3H-uridine with a definite association with the nucleolus. The time course is different, however since 3H-polyamines continue to accumulate in the nucleus, while 3H-uridine reaches a peak nuclear concentration within 30 min and drops to one-half after 24 h. No instance of grains overlying mitotic figures was observed. These findings indicate an association of 3H-polyamines with nuclear and nucleolar RNA.
    Type of Medium: Electronic Resource
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