Mutagenesis bacterial

The production of chromosomal abnormalities by ozone was first observed in plants by Fetner, who noted abnormal anaphases in the root tips of Vicia fava seeds exposed to ozone. Bacterial mutagenesis by ozone has been reported by a number of investigators. Hamelin and Chung noted an increased mutation rate in Escherichia coli exposed to ozone at as low as 0.05 ppm for 5 min and observed that the mutants were sensitive to ozone and X irradiation. They suggested that ozone might interact in DNA repair processes. Other studies indicating ozone-induced... 

Commoner, G., Vlthayathll, A. (. and Henry, J. I. Detection of metabolic carcinogen intermediates in urine of carcinogen-fed rats by means of bacterial mutagenesis, Nature (174) 249, 850. 

Other, more sensitive, tests have been suggested for the evaluation of potential carcinogenic risk of exposure to chemicals. These include the bacterial mutagenesis test devised by Dr. Bruce Ames ( ). This test has been applied to many of the amines listed in Table 1, both alone and after reaction with nitrite in weakly acid solution, followed by neutralization and application to the bacteria. In Table 3 are given the results of a number of such tests, together with comparison of the results of chronic... 

Stage B Short-term in vitro tests 1. mammalian cell DNA repair 2. bacterial mutagenesis (Ames test) 3. mammalian mutagenesis 4. chromosome tests (sister chromatid exchange) 5. cell transformation... 

Bacterial mutagenesis tests have been conducted with distilled water solutions of the freeze-dried residues [concentrated up to 3000-fold (7)] and partially freeze-dried samples [concentrated 10-fold (49)]. High salt concentrations in such concentrates may cause toxicity problems in the bacterial tests. The use of dimethyl sulfoxide, methanol, or supercritical carbon dioxide to extract the organics from the freeze-dried residues for mutagenicity test purposes should be investigated. 

Bacterial Mutagenesis In vitro Assays In vivo Assay... 

Commoner, B. 1976 Reliability of bacterial mutagenesis technlquesto distinguish carcinogenic and non-carcinogenlc chemicals. UISNTIS PB Report EPA-600/1-76-022. 

In both bacterial mutagenesis assays, one plots the number of mutant colonies on the ordinate (y-axis) versus the concentration of test compound on the abscissa (x-axis). The plots are usually linear up to the point at which cytotoxicity overwhelms mutation induction, and the number of mutants passes through a maximum and then declines. Hence, bacterial mutagenesis studies are usually conducted with low concentrations of chemical compounds or radiations that induce a linear frequency of mutations but do not cause significant cytotoxicity. 

The DSSTox web site also provides a database for Salmonella mutagenicity with 506 molecules approximately half of which are designated as positive for mutagenicity [57]. In addition, Simulations Plus, Inc., has a database with approximately 5000 molecules that covers 10 strains of bacterial mutagenesis. 

Beland, F.A., Beranek, D.T., Dooley, K.L., Heflich, R.H., and Kadlubar, F.F. (1983) Arylamine-DNA adducts in vitro and in vivo their role in bacterial mutagenesis and urinary bladder carcinogenesis. Environ. Health PerspecL, 49, 125-134. 

Animal dose tests and bacterial mutagenesis tests were done to confirm the safety of protein-polysaccharide conjugates [21], It has... 

Calomme M, Pieters L, Vlietinck A, Vanden Berghe D. Inhibition of bacterial mutagenesis by citrus flavonoids. PlantaMed i996 62 222-226. 

With the awareness that testing schemes were becoming increasingly complex and expensive, recent efforts have been initiated to reduce the number of tests to an essential core (5,6,8,9-iJ.,- ). Consideration of the various testing schemes that have been proposed reveals that most tiers or batteries are structured around seven tests ( ) bacterial mutagenesis, eukaryote mutagene-... 

Mutagenesis of mammalian cells is recommended for inclusion in the battery because it has a definitive end point like bacterial mutagenesis, but involves effects on the more highly organized eukaryotic genome (, 35). Moreover, differences in the mutagenic response between microbial and mammalian cells have been observed (36). 

Because of the enormous volume of reports of studies on nitrosamines, many of the recent reviews are focused on a narrow topic endogenous N-nitrosation [5], bacterial mutagenesis by nitrosamines [6], occurrence of nitrosamines in foodstuffs, and dietary exposure to nitrosamines [7,8,9], environmental exposure to preformed nitroso compounds [10], and the levels of both N-nitroso compounds and their precursors in the human environment [11]. While bacterially mediated N-nitrosation has been reviewed as a part of endogenous N-nitrosation [6], there have been no comprehensive reviews on the production and degradation of DMNA in various environments, that are closely associated with microbial processes. 

Calomme. M., Pieters, L., Vlietinck, A. and Vanden Berghe, D. 1996, Inhibition of bacterial mutagenesis by Citrus flavonoids , Planta Medica 62 222-226. 

D. Brusick, Bacterial mutagenesis and its role in the identification of potential animal... 

In this chapter, emphasis will be placed on the use of early passage Syrian hamster cells for identifying carcinogens. Results from this cell transformation system will be correlated with reported results from the bacterial mutagenesis system and chronic carcinogenicity tests in animals. 

Table 4 shows that A -nitrosodiphenylamine gave negative results in both short-term tests. Of the six carcinogens, all but A -nitrosodiethylamine (DEN) were positive in the standard test. However, as discussed later, DEN gave positive results after the addition of exogenous metabolic activation systems. Results with the bacterial mutagenesis test concurred completely with the reported carcinogenicity of the compounds. 

Chemical Reported activity T arget culture Hamster cell transformation LTD (Mg/ml) HOT" (Mg/ml) Bacterial mutagenesis... 

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