In the development of mutation assay systems, a number of approaches have been performed with a particular view to improve sensitivity. The inhibition of mutagen-efflux from tester bacteria might lead to increased mutagenic activity as the concentration of mutagen increases inside the cell. In this study, we constructed a series of Escherichia coli CC strains lacking the TolC protein to determi...

Mutations have been induced in single amoebae by treatment with the powerful mutagen, iV-methyl-iV-nitrosourethane. Three mutants, which differ visibly from the parent strain to the extent that individual amoebae are recognizable and change of characteristics from normal to mutant or mutant to normal can be followed in single cells, are described. These mutant strains have been cultured in the ...

It has been reported that hamster liver preparations are more effective for the metabolic activation of N-nitrosodimethylamine (NDMA) to a mutagen than rat liver preparations. The enzymatic basis for this phenomenon, however, has not been clearly elucidated. The present study was undertaken to examine the enzymology of NDMA metabolism by different hepatic subcellular fractions prepared from ham...

Aromatic amines, N-nitroso compounds and heterocyclic amines are suspected human pancreatic carcinogens. Cytochrome P450 (CYP) 1A2, N-acetyltransferase (NAT) 1, NAT2 and sulfotransferase (SULT) are enzymes involved in the metabolism of these carcinogens. To test the hypothesis that genetic variations in carcinogen metabolism modify the risk of pancreatic cancer (PC), we investigated the effect ...

Heterologous expression of a putative manganese superoxide dismutase gene (SOD2) of the basidiomycete Moniliophthora perniciosa complemented the phenotypes of a Saccharomyces cerevisiae sod2Δ mutant. Sequence analysis of the cloned M. perniciosa cDNA revealed an open reading frame (ORF) coding for a 176 amino acid polypeptide with the typical metal-binding motifs of a SOD2 gene, named MpSOD2. P...