纳秒级强脉冲电子束和Ar~＋离子束诱导的烟草种子DNA的损伤修复合成

REPAIR SYNTHESIS OF DAMADGE DNA IN TOBACCO SEEDS INDUCED BY STRONG PULSED ELECTRON AND Ar￣+ ION BEAMS

用３Ｈ－ＴｄＲ（氚标记的胸腺嘧啶脱氧核苷）掺入法结合ＤＮＡ合成抑制剂处理，研究了纳秒级强脉冲电子束和Ａｒ＋离子束诱导的烟草种子的ＤＮＡ损伤修复合成。受辐照种子在萌发的２８～４４ｈ较正常种子有较多的３Ｈ－ＴｄＲ的掺入，在萌发早期（６０ｈ内）出现了两个ＤＮＡ合成峰，而正常种子仅有一个。受辐照种子内的第一个ＤＮＡ合成峰受到ＤＮＡ修复抑制剂咖啡因的强烈抑制，而第二个ＤＮＡ合成峰受到ＤＮＡ复制抑制剂羟基脲的强烈抑制。说明纳秒强脉冲电子束和Ａｒ＋离子束诱发了烟草种子ＤＮＡ的损伤和修复。烟草种子的ＤＮＡ修复合成开始于种子萌发的第２８ｈ，３６ｈ或４０ｈ达到高峰，较ＤＮＡ复制高峰早１２ｈ或１６ｈ。本文还对ＤＮＡ合成抑制剂的作用进行了讨论。

DNA repair synthesis of tobacco seeds induced by strong pulsed electron and Ar+ ion beams was studied with 3H-TdR incorporation method and DNA inhibitor treatment. It was found that there were much more incorporated 3H-TdR during 28～44 hours of germination in implanted seeds than that in normal seeds. and there were two DNA synthesis peaks during early stage of germination (Within 60 hours) in the implanted seeds, but only one peak in normal seeds. The first DNA synthesis peak of the irradiated seeds was strongly suppressed by caffeine which is an inhibitor of DNA repair synthesis. the second one was strongly suppressed by hydroxyurea which is an inhibitor of DNA replication. These results indicated that both of strong pulsed electron and Ar+ ion beams could induce the damadge and repair of DNA in tobacco seeds. DNA repair synthesis started after 28 hours of germination and reached peak at the 36 th or 40 th hour in irradiated seeds. The peak of DNA repair synthesis was 12 or 16 hours earlier than that of DNA replication.