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首页> 外文期刊>Molecular and Cellular Biology >Kinds of mutations formed when a shuttle vector containing adducts of benzo[a]pyrene-7,8-diol-9,10-epoxide replicates in COS7 cells.
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Kinds of mutations formed when a shuttle vector containing adducts of benzo[a]pyrene-7,8-diol-9,10-epoxide replicates in COS7 cells.

机译：当包含苯并[a] py-7,8-二醇-9,10-环氧化合物加合物的穿梭载体在COS7细胞中复制时，会形成多种突变。

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We have investigated the kinds of mutations induced when a shuttle vector containing covalently bound residues of the (+/-)-7 beta,8 alpha-dihydroxy-9 alpha,10 alpha-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE) replicates in the monkey kidney cell line COS7. The target for detecting mutations was the 200-base pair gene for a tyrosine suppressor tRNA (supF), inserted at the EcoRI site in shuttle vector p3AC (Sarkar et al., Mol. Cell. Biol. 4:2227-2230, 1984). When introduced by transformation, a functioning supF gene in progeny plasmid recovered from COS7 cells allows suppression of a lacZ amber mutation in the indicator Escherichia coli host. Treatment of p3AC with BPDE caused a linear increase in the number of BPDE residues bound per plasmid. Untreated plasmids and plasmids containing 6.6 BPDE residues were transfected into COS7 cells, and the progeny were assayed for mutations in the supF gene. The frequency of mutants generated during replication of the BPDE-treated plasmids was not higher than that from untreated plasmids, but the two populations differed markedly in the kinds of mutations they contained. Gel electrophoresis analysis of the size alterations of 77 mutant plasmids obtained with untreated DNA and 45 obtained with BPDE-treated DNA showed that the majority of the mutant progeny of untreated plasmids exhibited gross alterations, principally large deletions. In contrast, the majority of the mutants generated during replication of the BPDE-treated plasmids contained only minor alterations, principally point mutations. Sequence analysis of progeny of untreated plasmids containing putative point mutations showed insertions and deletions of bases and a broad spectrum of base substitutions; in those from BPDE-treated plasmids, all base substitutions involved guanosine . cystosine pairs.
机译：我们研究了当穿梭载体含有共价结合的（+/-）-7 beta，8 alpha-dihydroxy-9 alpha，10 alpha-epoxy-7,8,9,10-tetrahydrobenzo []残基时所引起的突变类型。 ]（BPDE）在猴肾细胞系COS7中复制。用于检测突变的靶标是酪氨酸抑制剂tRNA（supF）的200个碱基对的基因，该基因插入穿梭载体p3AC的EcoRI位点（Sarkar等，分子细胞生物学，4：2227-2230，1984）。 。当通过转化引入时，从COS7细胞回收的后代质粒中有功能的supF基因可以抑制指示性大肠杆菌宿主中的lacZ琥珀突变。用BPDE处理p3AC导致每个质粒结合的BPDE残基数量线性增加。将未处理的质粒和含有6.6个BPDE残基的质粒转染到COS7细胞中，并检测后代中supF基因的突变。在BPDE处理的质粒复制过程中产生的突变体的频率不高于未处理的质粒，但是这两个种群所包含的突变种类存在显着差异。对用未处理的DNA获得的77个突变质粒和用BPDE处理的DNA获得的45个突变质粒的大小改变的凝胶电泳分析表明，未处理的质粒的大多数突变后代表现出总体改变，主要是大的缺失。相反，在经BPDE处理的质粒复制过程中产生的大多数突变体仅包含较小的变化，主要是点突变。含有推定的点突变的未处理质粒的后代的序列分析显示碱基的插入和缺失以及广泛的碱基取代。在用BPDE处理的质粒中，所有碱基取代均涉及鸟苷。胱氨酸对。

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