应用核酸酶S_1法进行~3H-TdR致哺乳动物细胞DNA单链断裂的检测及氚的RBE值估算

S_1 NUCLEASE USED FOR DETECTING DNA SINGLE STRAND BREAKS IN CULTURED CHL CELLS INDUCED BY INTERNAL β-RAYS FROM INCORPORATED ~3H-THYMIDINE, AND ESTIMATING TRITIUM RBE

应用灵敏的核酸酶S_1法,进行了^(60)Co γ-线及结合氚β射线致CHL细胞DNA单链断裂的检测,并做了剂量-效应分析。以双链百分比F值表示DNAssb损伤程度,发现γ-外照射和β-内照射,在给定的吸收剂量范围内,量-效关系均符合Y=EXP(A+BX+CX^2)模式。分析和比较两者关系式后,估算出RBE均值为1.14。

A sensitive nuclease S, digestion assay was used to measure DNA single-strand breaks in culturedCHL cells exposed to ^(60)Co γ-rays or internal β-rays from incorporated ~3H-thymidine, and dose-response relationships were analysed. If the DNA damage was expressed as the fraction of doublestrands of DNA(F), the dose-response relationships within the ranges of the given absorbed doseswere fitted satisfactorily to the exponential binomial equation: Y=EXP (A+BX+CX^2), either in thecase of external γ-inradiation or internal β-irradiation. The average RBE of tritium estimated bycomparing the two equations in our experiment was 1.14.