The Graduate School of Veterinary Medicine, Hokkaido University
Doi
Abstract
The LEC rat is reported to exhibit hypersensitivity to X-irradiation, deficiency in DNA double-strand break repair, and radio-resistant DNA synthesis. This character of the LEC rat has been thought to be due to abnormal G１arrest in cells after X-irradiation. In this report, we re-investigated the effect of X-irradiation on the cell cycle in primary-cultured fibroblasts . Primarycultured fibroblasts derived from LEC and BN rats were exposed to４Gy of Xray and their cell cycle analysis was performed with a flow cytometer. Fibroblasts derived from both rats showed normal response of the cell cycle, indicating the arrest at both G１‐and G２／M-phase and no difference in the cell cycle population between fibroblasts derived from both rats. In contrast, when the same analysis was performed using the cell line, L７and W８，which had been established from the lung fibroblasts of LEC and control WKAH rats, respectively, by immortalizing with SV４０T-antigen, L７cells but not W８cells showed impaired G１arrest and abnormal cell cycle. These results suggest that fibroblasts derived from LEC rats possess the normal cell cycle response after Xirradiation, if they are kept naive as not immortalized with SV４０T-antigen
