TY - JOUR
T1 - Effects of cytosol on mutagenesis induced by N-nitrosodimethylamine, N-nitrosomethylurea and α-acetoxy-N-nitrosodimethylamine in different strains of salmonella
T2 - Evidence for different ultimate mutagens from N-nitrosodimethylmine
AU - Guttenplan, J. B.
N1 - Funding Information:
Supported by USPHS grant ESO3332. I thank Wieslava Kosinska for skilful technical assistance.
PY - 1993/5
Y1 - 1993/5
N2 - N-Nitrosodimethylamine (NDMA), but not N-nitroso-N-methylurea (MNU) was more mutagenic in the Salmonella hisG428 strain, TA104, than in the hisG46 strain, TA100 in the presence of rat or hamster liver S-9 mix. As both NDMA and MNU can give rise to methyldiazonium ion (MDI) it appears that NDMA can be metabolized to an additional mutagen with a higher activity in TA104. The effects of UV and error-prone repair on NDMA and MNU-induced mutagenesis in TA104 were also different. α-Acetoxy-NDMA, which gives rise to the NDMA metabolite, α-hydroxy-NDMA, was more mutagenic in TA104 than TA100, under certain conditions. Several metabolites of NDMA (formaldehyde, 1,1-dimethylhydrazine and nitrite) were not significantly mutagenic at the concentrations that could have been generated from NDMA. It was previously reported that the microsomal-mediated mutagenesis induced by NDMA is greatly increased by cytosol in TA104, but not in TA100. The current study found that when cytosol was separated into a high and a low mol. wt fraction, neither greatly enhanced microsomal-mediated mutagenesis by NDMA in TA104. Addition of NAD to the high, but not the low mol. wt fraction resulted in greatly enhanced activation of NDMA to a mutagen in TA104. The enhancement by cytosol of NDMA-induced mutagenesis in hisG428 was only observed when both microsomes and cytosol were simultaneously present. These observations indicate that (i) the precursor to the ultimate mutagen is relatively short-lived; and (II) the metabolism of α-hydroxy-NDMA to a secondary mutagenic metabolite, possibly N-nitroso-N-methylformamide, by alcohol dehydrogenase may be responsible for the ultimate mutagen with relatively high activity in TA104.
AB - N-Nitrosodimethylamine (NDMA), but not N-nitroso-N-methylurea (MNU) was more mutagenic in the Salmonella hisG428 strain, TA104, than in the hisG46 strain, TA100 in the presence of rat or hamster liver S-9 mix. As both NDMA and MNU can give rise to methyldiazonium ion (MDI) it appears that NDMA can be metabolized to an additional mutagen with a higher activity in TA104. The effects of UV and error-prone repair on NDMA and MNU-induced mutagenesis in TA104 were also different. α-Acetoxy-NDMA, which gives rise to the NDMA metabolite, α-hydroxy-NDMA, was more mutagenic in TA104 than TA100, under certain conditions. Several metabolites of NDMA (formaldehyde, 1,1-dimethylhydrazine and nitrite) were not significantly mutagenic at the concentrations that could have been generated from NDMA. It was previously reported that the microsomal-mediated mutagenesis induced by NDMA is greatly increased by cytosol in TA104, but not in TA100. The current study found that when cytosol was separated into a high and a low mol. wt fraction, neither greatly enhanced microsomal-mediated mutagenesis by NDMA in TA104. Addition of NAD to the high, but not the low mol. wt fraction resulted in greatly enhanced activation of NDMA to a mutagen in TA104. The enhancement by cytosol of NDMA-induced mutagenesis in hisG428 was only observed when both microsomes and cytosol were simultaneously present. These observations indicate that (i) the precursor to the ultimate mutagen is relatively short-lived; and (II) the metabolism of α-hydroxy-NDMA to a secondary mutagenic metabolite, possibly N-nitroso-N-methylformamide, by alcohol dehydrogenase may be responsible for the ultimate mutagen with relatively high activity in TA104.
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U2 - 10.1093/carcin/14.5.1013
DO - 10.1093/carcin/14.5.1013
M3 - Article
C2 - 8504462
AN - SCOPUS:0027159543
SN - 0143-3334
VL - 14
SP - 1013
EP - 1019
JO - Carcinogenesis
JF - Carcinogenesis
IS - 5
ER -