Effect of fluorodeoxyuridine on the sedimentation of nucleoids from HeLa cells in sucrose gradients.
Sedimentation properties of nucleoids from HeLa cells cultured for 6 or 24 h with 10(-6) M fluorodeoxyuridine (FdUrd) were studied in neutral sucrose gradients. Independently on the presence and concentrations of ethidium bromide in the gradient, nucleoids from FdUrd treated cells sedimented farther than those from untreated cells. However, the maximum relaxation of supercoiled DNA, observed at the concentration of 5 micrograms/ml of ethidium bromide, was significantly lower in cells treated with FdUrd, which indicated that prior incubation with FdUrd did not increase the degree of DNA supercoiling but altered by some way the conformation of DNA in nucleus. Previously we have found, that treatment of HeLa cells with FdUrd resulted in the stimulation of DNA synthesis, which proved to be resistant to ultraviolet and gamma-irradiation. From the present results it is possible to suggest, that alterations of chromatine structure should be included in facilitating of DNA synthesis on DNA template damaged by ultraviolet or gamma irradiation.
D002467:Cell Nucleus / Q000378:metabolism; D004247:DNA / Q000187:drug effects*; D005467:Floxuridine / Q000494:pharmacology*; D006367:HeLa Cells; D006801:Humans; D009690:Nucleic Acid Conformation / Q000187:drug effects
D005467:Floxuridine; D004247:DNA