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Reversible accumulation of double- and single-stranded DNA breaks in DNA in growth-arrested cells

Journal Article · · Bull. Exp. Biol. Med. (Engl. Transl.); (United States)
OSTI ID:6478288
The authors study the possibility of the formation and repair of double-stranded breaks in DNA during a change in the proliferative status of cells. Jungarian hamster fibroblasts, transformed by SV-40 virus, were cultured in Carrel's flasks in a nutrient mixture containing Eagle's medium, lactalbumin hydrolysate, and bovine serum in the ratio of 4.5:4.5:1. DNA was labelled by the addition of 0.4 MBq/ml of tritium-thymidine to the incubation medium for 2-7 days. To arrest cell growth, the monolayer formed seven days after seeding was placed in medium with the serum concentration lowered to 1%, and incubated for 7-9 days. The cells were restimulated for division with fresh complete medium. The mitotic index was 20% in the exponentially growing cultures while in the resting cultures it was 1-2% and rose to 16% 2 days after stimulation. Double-stranded DNA breaks were determined by neutral elution of DNA; single-stranded breaks were measured by the alkaline DNA uncoiling method with fixation of hydroxyapatite. The formation of double-stranded DNA breaks and their repair, in response to a change in the proliferative status of the cell, were discovered for the first time.
Research Organization:
Latvian Scientific-Research Institute of Experimental and Clinical Medicine, Riga, USSR
OSTI ID:
6478288
Journal Information:
Bull. Exp. Biol. Med. (Engl. Transl.); (United States), Journal Name: Bull. Exp. Biol. Med. (Engl. Transl.); (United States) Vol. 102:8; ISSN BEXBA
Country of Publication:
United States
Language:
English