碱基置换

序列分析证实，自发tk基因点突变主要为碱基置换。

Spontaneous mutations were substitutions , and most of them were transversions .

推测阳性有机磷农药作为烷化剂，主要是使鸟嘌呤的N－7位甲基化，引起碱基置换；或形成加合物，造成交联，从而引发DNA重组修复而致突变。

The results suggest that positive OPPs may be a kind of alkylating agent , mainly methylated the N-7 position of guanine and induced base pair substitution of formed adduct , and cross linkage to induce DNA recombination and mutation .

结果：重质芳烃无移码突变和碱基置换效应，微核试验显示在316～1580mg/kg·bw剂量范围小鼠骨髓嗜多染红细胞微核率显著增加（与阴性对照组比较P<0.01）；

Results : Ames test was negative in all dosage groups . The frequencies of bone marrow micronucleus were increased significantly at the dose of 316 ~ 1 580 mg / kg · bw .

多数氨基酸位点的变异是由于碱基置换所引起。

The majority of amino acid variation is caused due to base substitutions .

这些化合物不仅能引起碱基置换型突变，也能引起移码型突变。

It was found that these compounds were not only base - pair substituted mutagens but also frameshift mutagens .

在碱基置换中，转换的频率（58.3%）高于颠换的频率（29.2%）。

Interestingly , the frequency of the base transition ( 58.3 % ) is obviously higher than that of the base transversion ( 29.2 % ) among the base replacements .

这些已知序列的突变体〔包括单碱基置换或基因内小段缺失（9～16个碱基）〕，用来分析肽的合成，二聚体的形成和杂工聚体酶活性〔1〕。

These known sequenced mutations , either single base substitutions or small intragenic deletions ( 9-16bp ) were analyzed for peptide production , dimer formation and enzymatic activity of the heterodimer .

试验数据经分析表明，功能红曲提取物及桔霉素的结果均表现为阴性，说明功能红曲提取物及桔霉素并没有引起移码型突变或碱基对置换等对基因的影响。

The data analysis had showed that both functional red kojic rice extract and citrinin failed to cause genie mutation .

Ames试验也说明辐照淀粉不诱发DNA中碱基对的置换型和移码型突变。

Ames test showed that both of the base pair transversion and frameshift mutant in DNA was not induced by irradiated starch .

非编码区亦存在单个碱基缺失及置换突变。

In non-coding region it shows mutation of single nucleotide deletion or substitution .

目的探讨高浓度枸橼酸钠局部抗凝及联机预制的低钠、低碱基、含钙置换液和透析液在高出血风险患者连续性肾脏替代治疗中的价值。

Objective To evaluate the anticoagulant high concentration sodium citrate , and online system prepared replacement fluid in continuous veno veno hemodiafiltration ( CVVHDF ) for patients at high risk of bleeding .

结果：7名MODY家系成员HNF-1α2号外显子上游的内含子均存在一碱基G→A置换，即IVS2nt-42G-A；

Results : IVS2nt-42 G-A was found in the flanking of exon 2 in all seven samples .

在检测到的24个碱基突变中，主要是碱基的置换（87.5%），碱基缺失的比例比较小（12.5%）。

In all of the 24 bases of mutants , the base replacement occupies about 87.5 % of the total mutants with only a small portion of gene deletion ( 12.5 % ) .

总碱基突变率为0.63%，在总数为239个突变碱基中，单碱基置换频率为77.40%，显著高于缺失（13.81%）和插入（8.79%）突变。

The rate of total mutate bases is 0.63 % , in the 239 total mutate base , single base substitution for 77.40 % , significant higher deletion ( 13.81 % ) and insertion ( 8.79 % ) .