Estimation of DNA fork displacement rates from isolated mammalian chromosomes

✍ Scribed by Jeff Dieden; Robert B. Painter; Leon N. Kapp

• Book ID: 104743431
• Publisher: Springer
• Year: 1980
• Tongue: English
• Weight: 332 KB
• Volume: 81
• Category: Article
• ISSN: 0009-5915
• DOI: 10.1007/bf00368148

✦ Synopsis

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 pulselabeled 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 gm/min, which was in excellent agreement with mcasurcmcnts from intcrphasc cclls. By thc samc mcthod, hydroxyurca was shown to retard DNA chain growth by 50-60% in both isolated chromosomes and interphase cells.