Hour T C, Chen L, Lin J K
Institute of Biochemistry, College of Medicine, National Taiwan University, Taipei, ROC.
Mutagenesis. 1998 Mar;13(2):157-66. doi: 10.1093/mutage/13.2.157.
The Salmonella lactam test is a newly developed method for detecting genotoxins. This technique is based on the ability of DNA damaging agents to reverse expression of the beta-lactamase gene, an important gene that enables microbes to resist beta-lactam antibiotics. A construct p-SELECT Control DNA plasmid containing a beta-lactamase gene site was constructed in many mutant forms, including point and frameshift mutants. These mutant constructs were introduced into Salmonella tester strains whose mutagenicity is based on their ability to reverse expression of the beta-lactamase gene. Fourteen pesticides were evaluated for genotoxicity using our newly developed Salmonella typhimurium strains JK947 and JK3, which are useful for detecting base substitution mutations. Six pesticides, namely allethrin, captan, folpet, monocrotophos, acephate and carbofuran, proved highly mutagenic in strain JK947, while the first four pesticides were more weakly mutagenic in strain JK3. In comparison, results from the Ames test show strain JK947 to be more sensitive to these pesticides than strains TA100 and TA1535. Strains TA98 and JK1 proved insensitive to allethrin, captan, folpet, acephate, carbofuran and monocrotophos. Among the many advantages of the lactam test are: large numbers of cells can treated and the test is operationally simple and inexpensive; revertant colonies form faster in the lactam test (16 h) than in the Ames test (48 h); the lactam test can detect mutagens present in biological specimens contaminated by histidine and biotin, samples that may give false positive results in the Ames test.
沙门氏菌内酰胺试验是一种新开发的检测基因毒素的方法。该技术基于DNA损伤剂逆转β-内酰胺酶基因表达的能力，β-内酰胺酶基因是使微生物能够抵抗β-内酰胺抗生素的重要基因。构建了包含β-内酰胺酶基因位点的p-SELECT对照DNA质粒，其有多种突变形式，包括点突变和移码突变。将这些突变构建体导入沙门氏菌测试菌株，这些菌株的致突变性基于它们逆转β-内酰胺酶基因表达的能力。使用我们新开发的鼠伤寒沙门氏菌菌株JK947和JK3评估了14种农药的遗传毒性，这两种菌株可用于检测碱基替代突变。六种农药，即丙烯菊酯、克菌丹、灭菌丹、久效磷、乙酰甲胺磷和呋喃丹，在菌株JK947中被证明具有高度致突变性，而前四种农药在菌株JK3中的致突变性较弱。相比之下，艾姆斯试验的结果表明，菌株JK947对这些农药比菌株TA100和TA1535更敏感。菌株TA98和JK1对丙烯菊酯、克菌丹、灭菌丹、乙酰甲胺磷、呋喃丹和久效磷不敏感。内酰胺试验的众多优点包括：可以处理大量细胞，试验操作简单且成本低廉；内酰胺试验中回复菌落形成的速度（16小时）比艾姆斯试验（48小时）更快；内酰胺试验可以检测存在于被组氨酸和生物素污染的生物标本中的诱变剂，这些标本在艾姆斯试验中可能会产生假阳性结果。
