A comparison of the mutagenic and apoptotic effects of tritiated water and acute or chronic caesium-137 gamma exposure on spleen T lymphocytes on normal and p53-deficient mice

Abstract

Purpose: This study was carried out to compare the mutagenic effects on spleen T lymphocytes of mice exposed to tritiated water (HTO) and chronic or acute ¹³⁷Cs γ irradiation.

Materials and methods: p53 wild type (p53^+/+) and p53 null type (p53^−/−) mice were exposed to a total dose of 3 Gy of HTO, chronic ¹³⁷Cs and acute ¹³⁷Cs.

Results: In spontaneous T-cell receptor (TCR) variant fractions and fractions following exposure to HTO, chronic ¹³⁷Cs and acute ¹³⁷Cs, TCR variant fractions in p53^+/+ mice were 5.9 × 10^–4, 9.8 × 10^–4, 6.4 × 10^–4 and 20.1 × 10^–4, respectively. In contrast, those fractions were increased in p53^−/− mice to 11.2 × 10^–4, 18.8 × 10^–4, 15.7 × 10^–4 and 31.3 × 10^–4, respectively. The frequency of apoptotic cells of the spleen 12 h after HTO injection increased to 5.0% in p53^+/+ mice, but did not increase at all in p53^−/− mice.

Conclusions: When compared on the basis of induced TCR variant fractions in p53^−/− mice, HTO (7.6 × 10⁻⁴) was 1.7 times more mutagenic than chronic ¹³⁷Cs (4.5 × 10⁻⁴), but 2.6 times less mutagenic than acute ¹³⁷Cs γ irradiation (20.1 × 10⁻⁴).

Keywords:

• tritiated water
• low dose-rate
• mutagenic effect
• p53
• apoptosis

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Erratum

Acknowledgements

This work was supported in part by UOEH Grant for Advanced Research H18-3 and NIFS Collaborative Research Program NIFS07KOBS012.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.