DNA DAMAGE AND MUTAGENESIS OF LAMBDA-PHAGE INDUCED BY GAMMA-RAYS
DNA DAMAGE AND MUTAGENESIS OF LAMBDA-PHAGE INDUCED BY GAMMA-RAYS
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DOI：
10.1093/mutage/3.1.29
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发表时间：
1988-01-01
期刊：
影响因子：
2.7
通讯作者：
BERTRAM, H
中科院分区：
文献类型：
--
作者：
BERTRAM, H
在水溶液中对Lambda噬菌体DNA进行伽马辐照，测定辐射引起的单链和双链断裂以及碱不稳定位点(DSB、SSB、ALS)的量。与辐射后的噬菌体悬浮液相比，这种DNA每致命一次的轻微结构损伤(SSB和ALS)是DNA的两倍。体外照射后的DNA被重新包装成具有感染性的颗粒(包装噬菌体)。使用SOS诱导的宿主细胞对Ci或CII顺反子突变的诱导进行评分。体外制备的粒子对伽马射线诱发的诱变具有二级动力学，这表明产生突变需要两个前突变事件。相反，无菌噬菌体悬浮液(‘lys-噬菌体’)在辐照后表现出单击式诱变动力学。噬菌体颗粒突变率的增加主要是由于SSB、ALS和未知碱基损伤等微小病变所致。在赖氏噬菌体中，成簇的DNA损伤可能会增强突变作用--这是包装噬菌体中不存在的一种配置。将感染性损失与结构破坏程度进行对比分析。这里调查的所有损伤都是导致生物失活的原因。Lambda噬菌体对微小病变有一定的耐受性。主要病变，如DSB，是造成传染性丧失的主要原因，可被认为是致命事件。
Lambda phage DNA was gamma-irradiated in aqueous solution and the amount of radiation-induced strand breakage [double- and single-strand breaks and alkali-labile sites (dsb, ssb, als)] was determined. Twice as much minor structural damage (ssb and als) per lethal hit was found in this DNA compared with DNA from irradiated phage suspensions. The in vitro irradiated DNA was re-packaged into infectious particles (''pack-phage''). The induction of mutations in the cI or cII cistron was scored using SOS-induced host cells. The in vitro prepared particles were found to have second-order kinetics for mutagenesis induced by gamma-rays indicating that two pre-mutational events were necessary to produce a mutation. In contrast, bacteria-free phage suspensions (''lys-phage'') showed single hit kinetics for mutagenesis after irradiation. The increase in the mutation rate in the phage particles was mainly due to minor lesions, i.e. ssb, als and unidentified base damage. In lys-phage, mutagenesis might be enhanced by clustered DNA damage - a configuration which does not exist in pack-phage. The loss of infectivity was analysed in comparison with the extent of structural damage. All lesions investigated here contributed to biological inactivation. Minor lesions were tolerated by lambda phage to a limited extent. Major lesions, such as dsb, contributed most to the loss of infectivity and can be considered as lethal events.