Abstract: BACKGROUND AND AIM: To explore if the mitochondrial DNA deletions in human lymphoblastoid cell line could be induced by ionizing radiation. MATERIALS AND METHODS: Human normal lymphoblastoid cell line samples were exposed to 10 Gy 60Co γ-rays in vitro, and pure mitochondrial DNA was extracted after 24 h and 48 h. A nested-PCR method was used to analyze the 889 bp, 3 895 bp or 7 436 bp deletions before and after radiation exposure. The final PCR products were purified, sequenced and blasted on standard human mitochondrial genome sequence database. RESULTS: The 889 bp and 3 895 bp deletions were not detected for the cell line samples not exposed to 60 Co γ-rays. The 889 bp and 3 895 bp deletions were detected on samples exposed to 10 Gy 60Co γ-rays, both 24 h and 48 h. The blast results showed that the 889 bp and 3 895 deletions flanked 11 688－12 576, nt 548－4 443, respectively. The 7 436 bp deletion level was not changed much before and after irradiation. CONCLUSION: The 889 bp and 3 895 bp deletion but not the 7 436 bp deletion in mitochondrial DNA,could be induced by ionizing radiation of lymphoblastoid cell lines samples.

Key words: 60Co γ-rays, lymphoblastoid cell line, mitochondrial DNA deletion