DNA synthesis associated with a DNA-nuclear-membrane complex from rat liver |
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| Authors: | Akhouri A Sinha Nobuko S Mizuno |
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| Institution: | (1) Medical Research Service, Veterans Administration Hospital, Minneapolis, Minnesota, USA;(2) Departments of Genetics and Cell Biology, and Surgery, University of Minnesota, Minneapolis, Minnesota, USA;(3) Building 49, Room 207, Veterans Administration Hospital, 55417 Minneapolis, Minnesota, USA |
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| Abstract: | Summary Ultrastructural analysis of M-band from nuclei of rat liver showed small amounts of chromatin, fragments of inner nuclear membrane, some amorphous nuclear material, and nucleopores. The outer nuclear membrane with its associated ribosomes was removed by Sarkosyl during the preparation of the M-band sample. Morphological features of nucleopores and the inner nuclear membrane were confirmed by freeze-fracture technique. The gross chemical composition of the M-band was similar to that of nuclear membrane fractions prepared by other techniques. The M-band contained the greatest proportion of newly-labeled DNA and also supported DNA synthesis in vitro. Electron-microscopic autoradiography of the M-band showed localization of silver grains of thymidine-3H presumably over newly synthesized DNA. The DNA synthesis could not be attributed to spurious attachment of DNA polymerase to M-band during its isolation. It was partially removed from the M-band by treatment with 0.5 M KC1, phospholipase A or C; and completely, by the action of pancreatic DNase. DNA synthesis was greater in M-band fractions isolated from nuclei of 24-hour regenerating liver.Supported in part by a grant (CA 10298) from the National Cancer Institute |
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| Keywords: | DNA synthesis DNA Nuclear membrane complex M-band Nucleopores Rat Liver |
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