SPONTANEOUS REVERTANTS IN MODIFIED S-TYPHIMURIUM MUTAGENICITY TESTS EMPLOYING ELEVATED NUMBERS OF THE TESTER STRAIN
SPONTANEOUS REVERTANTS IN MODIFIED S-TYPHIMURIUM MUTAGENICITY TESTS EMPLOYING ELEVATED NUMBERS OF THE TESTER STRAIN
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DOI：
10.1016/0165-7992(89)90029-8
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发表时间：
1989-01-01
期刊：
影响因子：
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通讯作者：
WILLIAMS, DT
中科院分区：
文献类型：
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作者：
GEORGHIOU, PE;BLAGDEN, PA;WILLIAMS, DT
有人提出，增加每个培养皿上的细菌数量可以提高鼠伤寒杆菌致突变性试验的敏感性。这些程序有可能通过增加在将细菌应用于有限的组氨酸测试板之前存在的预先存在的回复性（PER）的贡献来提高自发回复性（SR）的数量。我们研究了109种细菌对平板的PER贡献，发现PER的数量取决于用于接种过夜肉汤的培养物的处理和储存。以TA98的冷冻永久菌、冻干永久菌、母板菌和分离菌落接种，培养后PER/109活菌的平均数量分别为267、188、57和13。一个菌株SR数的升高可能导致无法识别致突变反应。建议在使用细菌数量增加的Ames试验的任何修改中监测PER的数量。
It has been proposed that increases in the number of bacteria applied to each plate can enhance the sensitivity of the Ames S. typhimurium mutagenicity assay. These procedures have the potential to elevate the number of spontaneous revertants (SR) by increasing the contribution of pre-existing revertants (PER) present before application of the bacteria to the limited histidine test plates. We have investigated the contribution of PER when 109 bacteria are applied to the plates and found that the number of PER is dependent on the handling and storage of the cultures used to inoculate the overnight broth. The average number of PER/109 viable bacteria after overnight growth in broths inoculated from a frozen permanent, lyophilized permanent, master plate, and an isolated colony, of TA98 were 267, 188, 57 and 13 respectively. The resultant elevation of the number of SR for a strain may result in a failure to identify a mutagenic response. It is recommended that the number of PER be monitored in any modification of the Ames test that makes use of elevated numbers of bacteria.