Schwartz S A, Kirsten W H
Proc Natl Acad Sci U S A. 1974 Sep;71(9):3570-4. doi: 10.1073/pnas.71.9.3570.
Rat embryo cells were treated with (3)H-labeled 5-bromodeoxyuridine (BrdU) in order to determine the nature of substitution and distribution of the analog in DNA. At optimal oncornavirus-inducing doses of BrdU (10(-4) M), density gradient centrifugation and DNA.DNA reassociation experiments revealed extensive (>90%) and uniform base substitution in repetitive, intermediate, and unique DNA sequences. Suboptimal doses (10(-7) M) of [(3)H]BrdU resulted in less than 5% thymine replacement and nonrandom labeling of DNA. Treatment of cells with 10(-7) M [(3)H]dT resulted in relatively uniform labeling throughout all DNA sequences. At low concentrations, BrdU was incorporated predominantly within the repetitive and intermediate DNA of rat embryo cells. Moreover, the single-copy DNA sequences were lightly substituted and reassociated extensively only in the presence of excess unlabeled DNA. Such specificity of base substitution may be related to the unusually selective nature of BrdU effects on animal cells.
为了确定类似物在DNA中的取代性质和分布，用（3）H标记的5-溴脱氧尿苷（BrdU）处理大鼠胚胎细胞。在最佳的致肿瘤病毒诱导剂量的BrdU（10^-4 M）下，密度梯度离心和DNA-DNA重缔合实验表明，在重复、中间和单一DNA序列中存在广泛（>90%）且均匀的碱基取代。次优剂量（10^-7 M）的[（3）H]BrdU导致胸腺嘧啶取代少于5%，且DNA标记不随机。用10^-7 M [（3）H]dT处理细胞导致在所有DNA序列中标记相对均匀。在低浓度下，BrdU主要掺入大鼠胚胎细胞的重复和中间DNA中。此外，单拷贝DNA序列仅在存在过量未标记DNA时才被轻度取代并广泛重缔合。这种碱基取代的特异性可能与BrdU对动物细胞异常的选择性作用性质有关。
