title: Estimation of DNA fork displacement rates from isolated mammalian chromosomes.
abstract: Chromosomes were isolated from Chinese hamster ovary cells that had been pulse-labeled with 3H-thymidine and bromodeoxyuridine and allowed to proceed to metaphase in the presence of colcemid. The chromosomes were then irradiated with 313 nm light and the length of the pulse-labeled DNA segments was estimated by the distribution of 3H-DNA in alkaline sucrose gradients. The average rate of fork displacement, calculated from this measurement, was 0.9 micrometer/min, which was in excellent agreement with measurements from interphase cells. By the same method, hydroxyurea was shown to retard DNA chain growth by 50--60% in both isolated chromosomes and interphase cells.
mesh_terms: D000818:Animals; D001973:Bromodeoxyuridine; D002460:Cell Line; D002875:Chromosomes / Q000378:metabolism* / Q000528:radiation effects; D006224:Cricetinae; D003412:Cricetulus; D004247:DNA / Q000378:metabolism* / Q000528:radiation effects; D004260:DNA Repair; D005260:Female; D007399:Interphase; D008027:Light; D010053:Ovary; D013997:Time Factors
chemical_list: D004247:DNA; D001973:Bromodeoxyuridine