Watanabe K, Sakamoto K, Sasaki T
Institute of Environmental Toxicology, Tokyo, Japan.
Mutagenesis. 1995 May;10(3):235-41. doi: 10.1093/mutage/10.3.235.
A collaborative study of interlaboratory variability in bacterial mutagenicity induced by mitomycin C (MMC) and bleomycin (BLM) was performed using the four strains Salmonella typhimurium TA102 and TA2638 and Escherichia coli WP2/pKM101 and WP2 uvrA/pKM101. Thirteen laboratories participated in this study. The four strains and two chemicals were sent from a central source to each laboratory. Each strain was cultured in nutrient broth containing antibiotics and laboratories were requested to ensure that the spontaneous counts for marker check fell within a specified range in the preparation of the original stock culture. Concerning the response to the chemicals, most interlaboratory variability was within a 4-fold range for tests with TA102, TA2638 and WP2/pKM101. From the results of the statistical analysis using the linear regression test, positive results in TA102, TA2638 and WP2/pKM101 and negative results in WP2 uvrA/pKM101 were obtained by MMC testing in all of the laboratories. On the other hand, with BLM testing, considerable interlaboratory variability was observed between the strains, largely because of the variation in results of the repeat experiments. Overall mean spontaneous revertant counts in all laboratories were within acceptable ranges for all four bacterial strains. In conclusion, it is judged that among Japanese laboratories, there is excellent agreement in the tested response of these bacterial strains to a strong mutagen such as MMC, as well as uniformity in the spontaneous reversion rates. However, for chemicals such as BLM that induce a weak response, it may be necessary to repeat experiments several times to obtain clear results. In this study, TA102 was shown to be a useful strain for routine mutagenicity testing. This necessitated control over culture maintenance by the addition of tetracycline and strict selection in the preparation of the original stock cultures.
利用鼠伤寒沙门氏菌TA102和TA2638以及大肠杆菌WP2/pKM101和WP2 uvrA/pKM101这四种菌株，开展了一项关于丝裂霉素C（MMC）和博来霉素（BLM）诱导的细菌致突变性实验室间变异性的合作研究。13个实验室参与了本研究。这四种菌株和两种化学物质从一个中心来源发送至每个实验室。每种菌株在含有抗生素的营养肉汤中培养，要求各实验室确保在制备原始储备培养物时，用于标记检查的自发计数落在指定范围内。关于对化学物质的反应，对于TA102、TA2638和WP2/pKM101的测试，大多数实验室间变异性在4倍范围内。通过线性回归测试的统计分析结果显示，在所有实验室中，MMC测试在TA102、TA2638和WP2/pKM101中得到阳性结果，在WP2 uvrA/pKM101中得到阴性结果。另一方面，对于BLM测试，各菌株之间观察到相当大的实验室间变异性，这主要是由于重复实验结果的差异。所有四个细菌菌株在所有实验室中的总体平均自发回复突变计数均在可接受范围内。总之，可以判断，在日本各实验室中，这些细菌菌株对MMC等强诱变剂的测试反应具有高度一致性，自发回复突变率也具有一致性。然而，对于诱导弱反应的化学物质如BLM，可能需要多次重复实验才能获得明确结果。在本研究中，TA102被证明是用于常规致突变性测试的有用菌株。这就需要通过添加四环素来控制培养物的维持，并在制备原始储备培养物时进行严格筛选。
