[Investigations on the mutagenic activity of coumarin derivatives in chlamydomonas. II. Extranuclear mutations induced by xanthotoxin plus near ultraviolet light (author's transl)]

Direct recombinogenic effect of dimethylnitrosamine (DMN) on zygotes of Chlamydomonas reinhardtii

We developed a test system with mutant strains of Chlamydomonas reinhardtii requiring arginine. Here, the meiotic recombination between two arginine loci served as an indicator of genotoxicity. After crossing, zygotes were treated with the alkylating agent dimethyl-nitrosamine (DMN) for 30 min. A dose dependent increase of wild type recombinants was found for DMN concentrations ranging from 68 microM to 680 microM. Like in cells of some higher plants, the agent was active in Chlamydomonas zygotes without any exogenous metabolic activation.

Genetic effects of N-methyl-N'-nitro-N-nitrosoguanidine and its homologs

Since the discovery of the mutagenic activity of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in 1960, this compound has become one of the most widely used chemical mutagens. The present paper gives a survey on the chemistry, metabolism, and mode of interaction of MNNG with DNA and proteins, and of the genotoxic effects of this agent on microorganisms, plants, and animals, including human cells cultured in vitro. Data on the carcinogenicity and teratogenicity of MNNG as well as on the genotoxic effects of homologs of MNNG are also presented.