Barber E D, Donish W H, Mueller K R
Mutat Res. 1983 Apr;113(2):89-101. doi: 10.1016/0165-1161(83)90222-4.
Growth curves of the 5 commonly used Ames Salmonella tester strains have been measured turbidimetrically in semi-solid agar. Lag times, doubling times and maximum cell densities have been calculated for each of the 5 strains. The time dependence of reversion has been studied in the standard plate incorporation assay using 1-h pulsed doses of (a) bromoethane, a volatile chemical mutagen, and (b) 1-h exposures to visible light. Essentially no reversion takes place during the first 4 h after plating. Reversion is detectable between hours 4 and 16. The cumulative or integrated revertants versus time curve has the characteristics of a growth curve. Conversely the derivatives of the growth curves resemble the curves obtained in the pulsed mutagenicity studies. Thus, the reversion rate in any given 1 h interval is proportional to the growth rate during that same interval. These results suggest that mutagenic chemicals must be present during the bacterial growth cycle (about 4-16 h after plating) in order to revert the tester strains. Short-lived chemical mutagens, then, should produce enhanced results if plated 6-8 h after the bacteria. We have confirmed this for N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), 9-aminoacridine and 2-aminoanthracene (with S9).
已通过比浊法在半固体琼脂中测量了5种常用的艾姆斯沙门氏菌测试菌株的生长曲线。计算了这5种菌株各自的延滞期、倍增时间和最大细胞密度。在标准平板掺入试验中，使用1小时脉冲剂量的（a）溴乙烷（一种挥发性化学诱变剂）和（b）1小时可见光照射，研究了回复突变的时间依赖性。接种后的前4小时基本上没有发生回复突变。在4至16小时之间可检测到回复突变。累积或积分回复子与时间的曲线具有生长曲线的特征。相反，生长曲线的导数类似于在脉冲诱变性研究中获得的曲线。因此，在任何给定的1小时间隔内的回复突变率与同一间隔内的生长速率成正比。这些结果表明，诱变化学物质必须在细菌生长周期内（接种后约4至16小时）存在，才能使测试菌株发生回复突变。那么，对于短寿命的化学诱变剂，如果在细菌接种后6至8小时接种，应该会产生增强的结果。我们已经用N-甲基-N'-硝基-N-亚硝基胍（MNNG）、9-氨基吖啶和2-氨基蒽（加S9）证实了这一点。
