摘要
离子束辐照ｐＵＣ１８质粒ＤＮＡ，可以造成其ＤＮＡ链的断裂。在剂量较低的情况下（５～１５×１０１５Ｎ＋／ｃｍ２），以单链断裂为主，电镜下主要呈开环结构；在相对较高的剂量下（２５×１０１５Ｎ＋／ｃｍ２），由于相对部位双链的断裂出现，电镜下可观察到线性质粒结构。经离子束辐照的质粒ＤＮＡ，其转化活性（即存活率）随处理剂量的增加而降低，且ＬａｃＺ基因也能发生较高频率的突变，与６０Ｃｏ—ｒ射线相比，在存活率相近的情况下，突变率较高。
DNA damage could be induced by ion beam irradiating pUC18 plasmid.The conversion of pUC18 supercoiled molecules (SC)to relaxed open circles(OC)at a low dose(5×1015N+/cm2)was observed since DNA single-strand breaks occurred.Double-strand breaks,which could convert the plasmid to linear molecules(L),were induced at a lesser extent as increasing of dose applied.Average biological survival was measured by transformation of irradiated pUC18 plasmid to E.coli DH5a.host.Because pUC18 DNA contains the lacz promoter/operator region and a part of the lacz gene,lacz transformants showed white colonies instead of blue colonies on x-gal indicator plates.Comparing lacz mutation frequency induced by ion beam irradiation with that by 60Co-r irradiation,ion beam irradiation seemed to be more effective when their average biological survival rates were close
出处
《安徽农业科学》
CAS
1994年第4期300-304,共5页
Journal of Anhui Agricultural Sciences
关键词
离子束
辐照
DNA
转化
突变
Ion beam,Irradiation,DNA,Transformation,Mutation
