School of Life Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, PR China; Key Lab of National Defense of China, Mianyang 621010, PR China.
J Environ Radioact. 2013 Dec;126:259-63. doi: 10.1016/j.jenvrad.2013.09.005. Epub 2013 Oct 3.
Superoxide dismutase (SOD) is an enzyme that removes free radicals from cells in many organisms. In order to further characterize these repair effects and their mechanism when subjected to radiation, Bacillus subtilis cells were exposed to gamma radiation and the cell survival rate, intracellular SOD activity, and DNA double-strand breakage were investigated. Vegetative cells of B. subtilis were irradiated by (60)Co gamma radiation at varying doses and subsequently exposed to varying levels of exogenous SOD. Standard plate-count, xanthine oxidase, and pulsed-field gel electrophoresis (PFGE) methods were employed to investigate the repair effects. The results showed that the exogenous SOD could significantly improve cell survival rate and intracellular SOD activity after gamma radiation. The cell survival rate was elevated 30-87 times above levels observed in control samples. Adding exogenous SOD into gamma irradiated cells may dramatically increase intracellular SOD activity (p < 0.01), while percentage of DNA release (PR) values may decrease significantly when cells are treated with SOD. The repair effects were observed to vary with the gamma radiation dose and SOD concentration. These findings suggest that exogenous SOD may have the ability to repair vegetative B. subtilis cell damage after irradiated by gamma radiation. DNA strand scission may also be prevented by addition of SOD. This research contributes to better understanding of protection from the effects of free radicals and their mechanisms, an ongoing process in many organisms that involves the cellular response to gamma radiation, which occurs naturally in soil and water, as well as in unusual cases of high-dosage exposure.
超氧化物歧化酶（SOD）是一种酶，可去除许多生物体细胞中的自由基。为了进一步描述这些修复作用及其在辐射下的机制，将枯草芽孢杆菌细胞暴露于γ射线下，研究了细胞存活率、细胞内 SOD 活性和 DNA 双链断裂情况。用（60）Coγ射线照射枯草芽孢杆菌的营养细胞，照射剂量不同，随后用不同水平的外源性 SOD 处理。采用标准平板计数法、黄嘌呤氧化酶法和脉冲场凝胶电泳（PFGE）方法研究修复效果。结果表明，γ射线照射后，外源性 SOD 能显著提高细胞存活率和细胞内 SOD 活性。细胞存活率比对照样品提高了 30-87 倍。向γ射线照射的细胞中添加外源性 SOD 可显著增加细胞内 SOD 活性（p<0.01），而 SOD 处理可使 DNA 释放率（PR）值显著降低。修复效果随γ射线剂量和 SOD 浓度而变化。这些发现表明，外源性 SOD 可能具有修复γ射线照射后的枯草芽孢杆菌营养细胞损伤的能力。添加 SOD 还可以防止 DNA 链断裂。这项研究有助于更好地理解自由基的保护作用及其机制，这是许多生物体中的一个持续过程，涉及细胞对自然存在于土壤和水中以及高剂量暴露等异常情况下的γ辐射的反应。
