Tomura T, van Lancker J L
Biochim Biophys Acta. 1975 Sep 1;402(3):343-50. doi: 10.1016/0005-2787(75)90270-1.
DNA was extracted from rat liver of non-irradiated animals, and was irradiated in vitro, and from animals which received whole body doses of X-radiation. Sedimentation on neutral and alkaline sucrose gradients as well as measurements of 32P release after sequential treatment with endonuclease and alkaline phosphatase and determination of triphosphate incorporation after the sequential treatment with endonuclease, alkaline phosphatase and DNA polymerase indicated that DNA irradiated in vivo and in vitro were effective substrates for the mammalian repair endonuclease. The experiments suggest that in addition to strand breaks, X-radiation causes base damage and they have provided a plausible explanation for the formation of double strand breaks in DNA irradiated in vivo.
从未受辐照动物的大鼠肝脏中提取DNA，并在体外进行辐照，同时也从接受全身X射线辐射剂量的动物中提取DNA。通过在中性和碱性蔗糖梯度上的沉降，以及在用核酸内切酶和碱性磷酸酶顺序处理后对32P释放的测量，和在用核酸内切酶、碱性磷酸酶和DNA聚合酶顺序处理后对三磷酸掺入的测定，表明体内和体外辐照的DNA都是哺乳动物修复核酸内切酶的有效底物。这些实验表明，除了链断裂外，X射线辐射还会导致碱基损伤，并且它们为体内辐照的DNA中双链断裂的形成提供了一个合理的解释。
