Induction of an SOS function by gaseous nitrogen dioxide

368 tems, modified some of the catalytic properties of RecA protein purified from E. coli. At the optimal concentration of magnesium chloride, the antimutagenic metal stimulated replicative form I DNA-dependent ATPase activity of the RecA protein whereas single-stranded DNA-dependent ATPase was inhibited with concomitant enhancement of both formation and dissociation of Dloops. These results may suggest that the antimutagenicity of this metal is ascribed to the stimulation of the error-free recombinational repair pathway which is dependent on functional RecA protein. This view is also supported by the fact that cobaltous chloride elevated survival fractions of the cells treated with certain mutagenic agents such as 4NQO and AF2.

23 Kobayashi, H., and H. Hayatsu, Faculty of Pharmaceutical Sciences, Okayama University, Okayama (Japan) A time-course study for mutagenicity of smoker's urine A short-term time-course study was made for the urinary mutagenicity caused by cigarette smoking in several volunteers. For collecting the mutagens from urine, the cotton linked to a copper phthalocyanine derivative (blue cotton; Hayatsu, H. et al. (1983) Mutation Res., 119, 233-238) was used as the adsorbent. The mutagenicity as measured by the Ames test on Salmonella typhimurium TA98 in the presence of $9 increased rapidly after the smoking was started. When the smoking was stopped, the activity began to decrease, and after 6-13 h reached the level of that of the non-smoking period. There was no great difference among individuals regarding this time-dependent response. These studies have shown that the appearance and disappearance of mutagenicity in urine in relation to cigarette smoking are rapid processes.

H. Hayatsu 1 Takarazuka Research Center, Sumitomo Chemical Co., Ltd., Takarazuka, and 1 Faculty of Pharmaceutical Sciences, Okayama University, Okayama (Japan) Dynamic adsorption of mutagens to 'blue cotton' 'Blue cotton', which contained trisulfo-copperphthalocyanine moiety linked covalently to cellulose molecules, adsorbed mutagens having 3 or more fused aromatic rings in their structures (Hayatsu et al. (1983) Mutation Res., 119, 233). To determine the potential of 'blue cotton', dynamic adsorption of 10 aromatic chemicals was examined using a column packed with 'blue cotton' or plain (absorbent) cotton. Aqueous solutions (1 × 10 4-5 × 10 4 M) of 9-aminoacridine hydrochloride, harmine hydrochloride, Trp-P-1 acetate, Trp-P-2 acetate, Nacetyl-Trp-P-1, N-acetyl-Trp-P-2, and 2acetylaminofluorene were used for the liquid-phase dynamic adsorption. 'Blue cotton' adsorbed these chemicals more tightly and in greater amounts than plain cotton. One mole of the pigment adsorbed specifically 2.2 2.5 moles each of Trp-P-1, Trp-P-2, harmine and 9-aminoacridine, and 0.6-1.1 moles of N-acetyl-Trp-P-1, N-acetyl-TrpP-2 and 2-acetylaminofluorene. Dynamic adsorption of phenanthrene, pyrene and benzo[a]pyrene in gas phase was also examined. 'Blue cotton' tightly adsorbed these chemicals, and the retention time of pyrene on the 'blue cotton' column was approximately 2 times longer than that on the plain cotton column.

25 Kosaka, H. 1, T. Kimura l, M. Uozumi 1 y. Oda 1 S. Nakamura 1, K. lnoue 1, T. Shibata l', T. Abe ~ and H. Shinagawa 3, 1 Osaka Prefectural Institute of Public Health, Osaka, 2 Kyoto Prefectural University of Medicine, Kyoto, and 3 Research Institute for Microbial Diseases, Osaka University, Osaka (Japan) Induction of an SOS function by gaseous nitrogen dioxide

24 Kogiso, S., M. Suga, H. Suzuki, M. Matsuo and

Inducibility of an SOS function by gaseous

369 nitrogen dioxide was tested by using S. typhimurium TA1535/pSK 1002 carrying umuC'-lac'Z fusion gene (umu test). The level of induction of the umu operon responsible for inducible mutagenesis is measured by the level of fl-galactosidase in the cell, encoded by the fusion gene. To avoid the color change of the medium, due to the xanthoprotein reaction, tyrosine, tryptophan and phenylalanine were excluded from the medium. The levels of induction of fl-galactosidase activity depended on the concentrations of nitrogen dioxide (10-90 ppm) which was bubbled into the medium for 30 rain. This method was found to be applicable for the screening of gaseous compounds with mutagenic activity.

26 Koshi, K., and T. Yagami 1, National Institute of Industrial Health, Kawasaki and i Showa University, School of Medicine, Tokyo (Japan)

Chromosomes of cultured peripheral lymphocytes from stainless steel welders (Part 2) In a preceding study on stainless steel welders, we had observed a small but significant increase (P < 0.05) of aberrant metaphases, chromatid breaks and exchanges in 72-h cultured peripheral lymphocytes. In the present study, chromosome aberrations and sister-chromatid exchanges (SCEs) were reanalysed for the same 44 welders and for 20 age-matched controls after about 1 year from the previous investigation. Both 48- and 72-h cultures of each individual were analysed for chromosome aberrations. Significantly increased aberration frequencies (P<0.05) such as aberrant metaphase, chromatid and chromosome gaps and chromatid breaks were observed in the group of welders as compared to controls. There was no significant difference in the mean value of the frequency of SCE in the peripheral lymphocytes between welders and controls. However, there was significant difference in the variance of SCE frequency between welders and controls. These results of SCE frequency were similar to those of the preceding study. Furthermore, 2 welders with 47 chromosomes in about 70% of total metaphases

were found and they were confirmed to be 46 XY/47 XXY.

27 Kuroda, K., Y.S. Yoo City Institute of Public Sciences, Osaka, and Medical School, Osaka

1 and T. Ishibashi, Osaka Health and Environmental 1 Osaka City University, (Japan)

Antimutagenic activity of food additives The rec assay was carried out on 51 food additives using Bacillus subtilis M45 (rec-) and H17 (rec÷), and 3 flavoring agents, cinnamic aldehyde, benzyl alcohol and undecalactone were positive. Only cinnamic aldehyde among the 3 agents is weakly mutagenic in S. typhimurium (Isidate et al., 1982). The rec assay may be able to detect the chemicals which interfere with the inducible error-prone repair, because the rec gene, defective of M45, and rec A gene of E. coli are identical (deVos and Venema, 1983). So we investigated their antimutagenic activity. These 3 agents were not mutagenic in E. coli WP2 uvrA and, on the contrary, they suppressed the mutagenic activity of furylfuramide (AF-2) without any cytotoxic effect on the bacteria. They did not suppress the mutagenic activity of N-methyl-N'-nitro-N-nitrosoguanidine. These antimutagenic effects were not caused by AF-2-mediated inactivation because AF-2 was removed by washing after the treatment. The curves for the dose-response relationship in the antimutagenic activity of benzyl alcohol and cinnamic aldehyde were similar.

28 Kuroda, Y., National Institute of Genetics, Mishima, Shizuoka (Japan)

Mutagenic activity of Ames test-negative carcinogens in cultured mammalian cells There are some chemicals whose mutagenic activity in the Ames test was negative but which produced tumors in experimental animals. Among