Effect of bacterial concentration on reversions induced in salmonella typhimurium TA1538 by N‐hydroxy‐2‐acetylaminofluorene

Wiley - Tập 5 Số 4 - Trang 565-575 - 1983
G. L. White1, David T. Beranek2, Robert H. Heflich2
1Division of Mutagenesis, HFT‐120, Department of Health and Human Services, Food and Drug Administration, National Center for Toxicological Research, Jefferson, AR 72079
2Department of Health and Human Services, Food and Drug Administration, National Center for Toxicological Research, Jefferson, Arkansas

Tóm tắt

AbstractReversions induced by N‐hydroxy‐2‐acetylaminofluorene (N‐OH‐AAF) were measured in the Salmonella/microsome quantitative plate assay using various concentrations of Salmonella typhimurium strain TA 1538. The number of induced revertants increased with an increasing number of bacteria/plate, but the variation in reversion frequency was not as great as the variation in bacterial concentration. The effects of bacterial concentration on reversion fixation, phenotypic expression, selection of his+ revertants, and the interaction of the mutagen with bacterial DNA were examined. Suspension cultures of TA 1538 were exposed to N‐OHAAF and various dilutions were prepared and assayed for revertants/108 bacteria. Reversion frequencies were very dependent on bacterial concentration between approximately 0.2 × 108 and 2 × 108 bacteria/plate. Revertants/108 TA 1538 were reduced above about 2 × 108 bacteria/plate, indicating that culture conditions limited reversion fixation, expression and/or selection at these concentrations. The number of spontaneous revertants/plate determined both from bacteria exposed to dimethyl sulfoxide in suspension culture and in the Salmonella/microsome assay were not greatly affected by bacterial concentration. To study the effect of bacterial concentration on the interaction of the mutagen with bacterial DNA, various concentrations of TA 1538 were exposed to the same dose of N‐OH‐AAF. Both revertants/108 TA 1538 and DNA adducts varied inversely with bacterial concentration. The effect of bacterial concentration on both reversion fixation and/or expression and on mutagen binding to DNA may influence reversion frequencies in the Salmonella/microsome assay.

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Tài liệu tham khảo

Ames BN, 1975, Methods for detecting carcinogens and mutagens with the Salmonella/mammalian‐microsome mutagenicity test, Mulat Res, 31, 347

AmesBN McCannJ YamasakiE(1981): Methods for detecting carcinogens and mutagens with the Salmonella/mammalian‐microsome mutagenicity test

A revision of the Ames et al (1975) paper supplied with the tester strains.

10.1016/0165-1161(82)90033-4

10.1038/274020a0

10.1002/em.2860030204

10.1073/pnas.79.17.5175

Bridges BA, 1981, Evaluation of Short‐Term Tests for Carcinogens, 49

10.1016/0165-1161(80)90239-3

Fahl WE, 1981, Relationship between benzo(a)pyrene‐induced DNA base modification and frequency of reverse mutations in mutant strains of Salmonella typhimurium, Cancer Res, 41, 3400

10.1016/0165-7992(82)90018-5

10.1016/0027-5107(82)90164-6

Garner C, 1980, Factors affecting response in bacterial mutagenicity assays, Chem Ind Lond, 1, 844

10.1016/0165-1161(76)90076-5

10.1016/0165-1161(79)90004-9

10.1016/0165-1161(78)90012-2

10.1073/pnas.73.3.950

10.1073/pnas.72.12.5135

10.1016/0006-291X(82)92150-7

10.1016/0165-1218(81)90046-X

10.1016/0165-1161(81)90026-1

10.1002/em.2860020114

10.1016/0165-1161(79)90101-8

10.1002/em.2860030406

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Wiley

Tập 5 Số 4

565-575

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