Effect of exogenous nucleotides on repair of damaged DNA in mouse thymocytes

    WANG Lanª²Fang, LE Guoª²Wei, DAI Qiuª²Ping

    1Department of Preventive Medicine, School of Basic Medicine, Tongji University, Shanghai 200092, China

    2Key Laboratory of Food Science and Safety of Ministry of Education, Southern Yangtze University, Wuxi 214036, China

    ¡¾Abstract¡¿ AIM: To investigate the effect of exogenous nucleotides on the repair of damaged DNA in mouse thymocytes in vitro. METHODS: Thymocytes from Kunming male mice were treated with Nª²methylª²N¡äª²nitroª²Nª²nitrosoguanidine (MNNG, 10 ¦Ìmol/L) to induce DNA damage. DNAª²damaged cells were cultured in basic or complete RPMI 1640 medium supplemented with different levels of nucleotides (0, 0.1, 1, 10 mmol/L). DNA damage and repair were analyzed at 2, 5 h with singleª²cell gel electrophoresis. RESULTS: Nucleotides had no significant effect on the percentage of comet cells at 2 h in basic medium (P>0.05), but the percentage of comet cells decreased significantly in complete medium with nucleotides supplementation (P<0.01). The nucleotides supplementation significantly decreased the percentage of comet cells at 5 h (P<0.01). Comet tail length had no signiª²ficant difference among groups at 2 h in basic or complete medium (P>0.05). Nucleotides of 1, 10 mmol/L decreased comet tail length at 5 h in basic medium (P<0.01) . The supplementation of 1, 10 mmol/L nucleotides decreased comet tail length at 5 h in complete medium (P<0.01). The percentage of DNAª²repaired cells was increased significantly with nucleotides supplementation between 2 and 5 h in basic (P<0.05) or complete medium (P<0.01). CONCLUSION: The supplementation of nucleotides can accelerate the repair of damaged DNA in mouse thymocytes in vitro. The effect of nucleotides is related with the supplemental levels of nucleotides. ......