title: [DNA replication in mammalian cells after the action of factors of a physical, chemical or biological nature. V. The structural reorganization of replicating DNA in HeLa cells after incubation with 5-fluorodeoxyuridine].
abstract: A study was made of sedimentation properties of the nucleoid (chromatin) of HeLa cells with radio- and thermostable mode of DNA synthesis induced by 5-fluorodeoxyuridine (FUdR). After the incubation of HeLa cells with FUdR (10(-6) M, 6 h or 24 h) the rate of nucleoid sedimentation was shown to rise by 40 and 25%, respectively. Maximum relaxation of the nucleoid was observed under 5 mg/ml ethidium bromide concentration in sucrose gradients. After the incubation with FUdR the nucleoid relaxes to a lesser extent, and after irradiation its response to ethidium bromide in various concentrations was similar to that of intact nucleoid, and by this property the "FUdR nucleoid" differs essentially from the irradiated "normal nucleoid". A model of chromatin structure of cells exposed to FUdR is proposed, based on the transformation of large domains in small ones, for the explanation of radioresistant DNA synthesis.
mesh_terms: D002453:Cell Cycle / Q000187:drug effects / Q000528:radiation effects; D004261:DNA Replication / Q000187:drug effects* / Q000528:radiation effects; D004278:DNA, Superhelical / Q000187:drug effects / Q000528:radiation effects; D005467:Floxuridine / Q000494:pharmacology*; D005720:Gamma Rays; D006367:HeLa Cells / Q000187:drug effects* / Q000378:metabolism / Q000528:radiation effects; D006801:Humans; D011836:Radiation Tolerance; D013997:Time Factors
chemical_list: D004278:DNA, Superhelical; D005467:Floxuridine
vernacular_title: Replikatsiia DNK v kletkakh mlekopitaiushchikh posle deĭstviia faktorov fizicheskoĭ, khimicheskoĭ ili biologicheskoĭ prirody. V. Reorganizatsiia struktury replitsiriushcheĭ DNK v kletkakh HeLa posle inkubatsii s 5-ftordezoksiuridinom.