Repair of radiation-induced lethal and mutational damage in chinese hamster cells in vitro.

Abstract

The ability of Chinese hamster hai cells to repair damage related to cell death and mutational change induced by X-rays was studied by using a sensitive forward mutation system from prototrophic CH-hai Cl 23 cells to auxotrophs.The results obtained from the dose rate and split-dose experiments suggest that Chinese hamster hai cells have repair mechanisms for the sublethal and mutational damage induced by X-rays and that these mechanisms act in common for repair of both types of damage.In addition, we also found that these cells have repair abilities for lethal and mutational damage induced by a potentially lethal dose of radiation.

X-ray-induced cell killing and mutations in cultured human cell lines (xeroderma pigmentosum cells and HeLa S3 cells).

“…Such an inverse relation between the radiation-induced mutation frequencies and cell survivals is also observed for various cell types including human diploid cells (Cox and Masson 1976), Chinese hamster cells (Thacker et al 1977) and mouse lymphoma cells (Knaap and Simons 1975), as have already been studied by other workers. These results indicate that there is a close correlation between the degree of the radiationinduced damage of the cells and their mutability, similarly to the previous results obtained from the dose rate, split-dose and potentially lethal dose experiments using Chinese hamster hai cells (Suzuki et al 1979).…”

“…Among these Chinese hamster cell systems hold a special place because of a number of characteristics, such as relatively short generation time, high plating efficiency and small number of chromosomes In the previous studies Horikawa et al 1976), we have also established a sensitive forward mutation system, for detecting the mutations induced by radiations and chemical carcinogens or mutagens, using prototrophic CH-hai Cl 23 cells which were isolated from an original Chinese hamster hai cell line. However, it was found in our recent experiments (Suzuki et al 1977(Suzuki et al , 1979) that this forward mutation system using prototrophic CH-hai Cl 23 cells is not sensitive enough to detect the mutations induced by low doses (especially, less than 200R) of X-rays, because Chinese hamster hai cells have the high repair ability for cell killing and mutational damage induced by low doses of X-rays. These results seem to indicate that it is necessary to use cell lines which have a low repair ability for the sublethal damage (or have an unshouldered exponential survival curve) such as human diploid fibroblasts (Cox and Masson 1976) for maximal detection of the mutations induced by low doses of ionizing radiation.…”