[Modification of mutation processes in culture of human lymphocytes with tea extracts].

Antimutagenic activity of the extracts of tea leaves from different stages of technological processing has been investigated. Culture of human lymphocyte cells was used as a test-object. Mutations have been induced with gamma-rays, N-methyl-N1-nitro-N-nitrosoguanidine (MNNG) and benz-[a]-pyren. All the extracts showed ability to decrease the frequency of chromosome aberrations with high effectiveness. The effectiveness of green tea leaf extracts was higher in comparison with the effectiveness of the extracts from the late stages of processing.

Evaluation of transcriptional fusions with green fluorescent protein versus luciferase as reporters in bacterial mutagenicity tests.

A bacterial plasmid was constructed on which the regulatory region of the umuC gene of Escherichia coli was fused to the coding sequence of the green fluorescent protein gene (gfp) from the jellyfish Aequorea victoria. Escherichia coli AB1157 strains carrying the plasmid emitted fluorescence in the presence of mutagens that induce the SOS DNA repair system. Data on tests with nitrosoguanidine, methylmethane sulphonate and UV radiation (254 nm) are presented. Although fluorescent detection using this system was not as rapid or sensitive as a similar luminescent equivalent (umuC-luxAB), the gfp reporter system was more robust. Escherichia coli umu gene induction was also analysed in Salmonella typhimurium TA1537 cells following plasmid transfer and exposure to the same range of mutagens. There was no significant difference in sensitivity between the two species. These preliminary results will provide the basis for development of mutagenicity test systems useful in the testing of complex mixtures, such as environmental samples, and the investigation of physiological parameters influencing spontaneous mutagenesis in bacteria.