ENVIRONMENTAL CHEMICAL AND OXIDATIVE STRESS INDUCED DNA DAMAGE/CARCINOGENESIS

携带中性报告基因的转基因C57 B1/6小鼠（Big Blue tm） 基因ZAP/lacIq可以使用λ穿梭载体和 用潜在的处理后测定的突变频率 环境化学诱变剂。 我们比较了单身和 多次给药方案，并确定了诱导突变体 致癌物乙基亚硝基脲和1，2，3- 三氯丙烷，在两个实验中诱导B6 C3 F1小鼠的肝脏肿瘤， 年致癌研究。 使用优化的λ穿梭载体 救援协议，我们有几个重要的观察 关于该体内诱变测定系统： (1)EtNU诱导的左外侧和右外侧的突变频率相同， 在独立的试验中， 这些显著增加超过对照突变频率。 使用转基因小鼠DNA等分试样进行实验室间比较 用1，2，3-三氯丙烷和相同的优化方案处理 比较有利。 总之，这些结果表明，该测定具有 优化以减少变异性， 来自不同实验室的环境诱变剂是可能的。 （2）在这些小鼠的肝脏中观察到的突变频率为 取决于诱变效力、剂量、剂量率、表达时间 以及整个分析的质量。 效力较低的诱变剂，例如1，2，3- 三氯丙烷，需要更广泛包装和斑块形成 单位观测值，以接近观测到的突变体数量 以确定统计学显著性。 这种转基因小鼠模型（Big Blue tm; ZAP/lacIq）提供了重要的 研究组织特异性体内诱变的优势。

Transgenic C57Bl/6 mice (Big Blue tm) carrying the neutral reporter gene ZAP/lacIq can be rescued using a lambda shuttle vector and the mutant frequency determined after treatment with potential environmental chemical mutagens. We have compared single versus multiple dosage regimens and determined the induced mutant frequencies for the carcinogen, ethylnitrosourea, and 1,2,3- trichloropropane, which induced liver tumors in B6C3F1 mice in a two year carcinogenesis study. Using an optimized lambda shuttle vector rescue protocol, we have made several important observations concerning this in vivo mutagenesis assay system: (1) EtNU induced the same mutant frequency in both the left lateral or medial lobe of the liver of transgenic mice in independent assays and these were significantly increased above control mutant frequencies. Interlaboratory comparisons using aliquots of DNA from transgenic mice treated with 1,2,3-trichloropropane and the same optimized protocol compare favorably. Together these results suggest that the assay has been optimized to reduce variability and that identification of potential environmental mutagens from different laboratories are possible. (2 )Mutant frequencies observed in the liver of these mice are dependent upon mutagenic potency, dose, dose rate, expression time, and the quality of the overall assay. Less potent mutagens, e.g. 1,2,3- trichloropropane, require more extensive packaging and plaque forming unit observations in order to approach the number of observed mutant to determine statistical significance. This transgenic mouse model (Big Blue tm; ZAP/lacIq) offers important advantages to investigate tissue specific in vivo mutagenesis.