ENVIRONMENTAL CHEMICAL AND OXIDATIVE STRESS INDUCED DNA DAMAGE/CARCINOGENESIS

携带中性报告基因的转基因C57BL/6小鼠(Big Blue Tm) 基因ZAP/lacIq可以用lambda穿梭载体和 电势处理后突变频率的测定 环境化学诱变剂。我们已经比较了单人和 多剂量给药方案及诱变菌株的测定 致癌物质乙基亚硝脲和1，2，3- 三氯丙烷诱发B6C3F1小鼠肝脏肿瘤 一年的致癌研究。使用优化的Lambda穿梭载体 救援方案，我们做了几个重要的观察 关于这个体内诱变检测系统： (1)EtNU在左侧或左侧诱发相同的突变频率 转基因小鼠肝脏内侧叶的独立检测和 这些突变频率显著高于对照突变频率。 利用转基因小鼠的等量DNA进行实验室间比较 用1，2，3-三氯丙烷处理，相同的优化方案 有利地比较。总而言之，这些结果表明，化验结果 进行了优化，以减少变异性和识别潜力 来自不同实验室的环境诱变剂是可能的。 (2)在这些小鼠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、 以及整个化验结果的质量。效力较低的诱变剂，例如1，2，3- 三氯丙烷，需要更广泛的包装和斑块形成 单位观察，以接近观察到的突变数量 以确定统计学意义。 这种转基因小鼠模型(Big Blue tm；ZAP/lacIq)提供了重要的 在体内研究组织特异性诱变的优势。

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.