DNA Single-strand Break Repair in Cultured Insect and Mammalian Cells after X-irradiation

Abstract
The TN-368 cell line originated from minced adult ovaries of the cabbage looper, Trichoplusia ni. The V-79-4 cell line was derived from lung tissue of a male Chinese hamster, Cricetulus griseus. Values near 2 .times. 108 dalton were obtained for the weight-averaged MW of single-stranded DNA for both unirradiated TN-368 and V-79 cells. The rate of DNA SSB [single strand break] rejoining was slightly higher in TN-368 cells than in V-79 cells, as nearly all the breaks in TN-368 cells were repaired within 10 min and in V-79 cells within 20 min. A superior excision repair mechanism acting on endonuclease-sensitive sites in the DNA may be one of the major factors responsible for the greater radioresistance of the TN-368 cells.