Introduction of Syrian hamster acetyltransferase gene into Salmonella typhimurium

Mutation Research, 272 (1992) 249-292 © 1992 Elsevier Science Publishers B.V. All rights reserved 0165-1161/92/$05.00

249

MUTENV 08845

Environmental Mutagen Society of Japan Selected abstracts of the 20th A n n u a l Meeting 6-8 November 1991, Tokyo (Japan) (Received 25 May 1992) (Accepted 2 June 1992)

Keywords: Japanese Environmental Mutagen Society; Abstracts; Annual Meeting 1991

1 Akaiwa, E. i, N. Suzuki i, K. Shimoi 2, M. Sano i, Y. Nakamura ~ and I. Tomita I, I School of Pharmaceutical Sciences and 2 School of Food and Nutritional Sciences, University of Shizuoka, 52-I, Yada, Shizuoka 422 (Japan) Bio-antimutagenic activities of vitamin

B6

in E.

coil and mouse peripheral blood cells The bio-antimutagenic effects of various vitamins have been investigated on UV or chemically induced mutagenesis in E. coil B/r WP2. Pyridoxal (PL) and pyridoxal 5'-phosphate (PLP) showed marked activity. No delay for the first cell division was seen by post-treatment with PL after UV irradiation. PL also reduced 4NQO induced mutation, while it was ineffective in MNNG or ~,-ray treated cells. Besides, this bio.antimutagenie effect was not seen in DNA excision repair deficient strain WP2suvrA. PLP showed a dose-dependent reduction of the frequency of mitomycin C (2 mg/kg, i.p.) induced micronucleated peripheral reticulocytes (MNRETs). Simultaneous or subsequent (7.5 h) oral administration of PLP (25 mg/kg) signifi-

Correspondence: Shigeaki Sato, Department of Hygiene, Kobe University School of Medicine, Knsunoki-cho, Chuo-ku Kobe 650, Japan.

cantly suppressed the induction of MNRETs. PLP also decreased the frequency of MNRETs induced by cis-DDP (2 mg/kg, i.p.). However, such an anticlastogenic effect was not observed in cyclophosphamide (50 mg/kg, i.p.), MNU (30 mg/kg, p.o.) or y-ray treated mice. These results ,suggest that PL and PLP stimulate DNA excision repair directly or indirectly, and this leads to the demonstrated bio-antimutagenic effects in E. coli and mouse peripheral blood cells.

2 Ando, M., Y. Shindo, M. Fujita, S. Ozawa ~, Y. Yamazoe ~ and R. Kato m, Pharmaceutical Research Center, Meiji Seika Kaisha, Ltd., 760, Morooka-cho, Kohoku-ku, Yokohama 222 and i Department of Pharmacology, School of Medicine, Keio University, 35, Shinanomachi, Shinjuku-ku, Tokyo 160 (Japan) Introduction of Syrian hamster acetyltransferase gene into Salmonella typhimurium

Acetyltransferase catalyzes the activation of arylamines including heterocyclic aromatic amines to their reactive metabolites. Two forms of acetyltransferase, AT-I and AT-If, which differ in their substrate specificities exist in hamster livers. AT-I utilizes arylhydroxamic acids as acetyl donors and

~o also has arylhydroxamic acid N,O-transacetylating activity. In contrast, an acetyltransferase in Salmonella has no detectable arylhydroxamic acid N,O-transacetylating activity. The cDNA encoding AT-I was introduced into S. typhimurium strain TA1538 using an expression vector pKK223-3. AT-I protein was found to be expressed efficiently by Western blot. The new strain, designated SAT138, showed remarkably high sensitivity (> 10,000 fold) for N-hydroxy-2acetylaminofluorene in the absence of $9 mix, in the Ames mutagenesis test, compared to the parent strain TA1538. SAT138 also had 400- and 600-fold higher sensitivty for N-hydroxy-2aminofluorene and 2-acetylaminofluorene in the absence and presence of $9 mix, respectively. The unique characteristic of SAT138, having high arylhydroxamic acid N,O-transacetylating activity, which is defective in Salmonella acetyltransferase, provides a broader and greater sensitivity for the detection of mutagenic N-substituted chemicals in the Salmonella mutagenesis test.

3 Aoki, K. ~, H. Lec 2, H. Sakagami "~,T. Yoshida i and Y. Kuroiwa i, i Dept. of Biochemical Toxicology, Pharmaceutical Sciences and "~First Dept. of Biochemistry, School of Medicine, Showa University, 1-5-8, Hatanodai, Shinagawa-ku, Tokyo 142 (Japan) and : Korea Research Institute of Chemical Technology, Daedeog-Danji, Daejeon 305-606 (Korea)

Antlmutagenicity of pine cone extract Fr.VI (PCVl) PC-VI, the acid precipitate of 1% NaOH extract from the pine cone of Pinus parviflora SIEB. et Zucc., shows diverse biological activities such as antitumor, antiviral and immunopotentiating ones. The antimutagenic activity of PC-VI was examined by the Ames test with S. typhimurium TA98. PC-VI decreased the mutagenicity of promutagens such as benzo[a]pyrene (BP) and 2aminoanthracene (AA), but had llo effect on the mutagenicity of direct-acting mutagens such as 2-(2-furyl)-3-(5-nitro-2-furyi)acrylamide and N-

methyl-N'-nitro-N-nitrosoguanidine. The addition of PC-VI to rat hepatic microsomes resulted in a decrease in activity of aminopyrine N-demethylase, aniline hydroxylase and NADPH-cytochrome c reductase, and content of cytochrome P-450. After incubation of AA and PC-VI, the amount of AcOEt-extractable AA decreased with the content of PC-VI. PC-VI had no effect on the mutagenicity of bacteria pretreated with BP and AA. It is concluded that PC-VI shows indirect antimutagenicity by interfering with cytochrome P450-dependent bioactivation and desmutagenic activity.

4 Arimoto, S., S. Fukuoka, C. Itome and H. Hayatsu, Faculty of Pharmaceutical Scieces, Okayama University, Tsushima, Okayama 700 (Japan)

Adsorption of mutagens to Sepharose bearing covalently bound chlorophyllin We have reported antimutagenic actions of chlorophyll and chlorophyllin (the chromophore of chlorophyll). A mechanism likely to be operating in these inhibitory actions is trapping of the mutagens by the chromophore, thereby rendering them unavailable to the target cells. To explore this mechanism, we prepared Sepharose bearing covalently bound chlorophyllin derivatives (Cu, Fe or no-metal chlorin), and the adsorption of mutagens to these Sepharose preparations was measured using the method previously applied for blue cotton adsorption. 14 compounds out of 26 with 3 or more fused rings in their structures were adsorbed more than 50% to Cu chiorophyllin-Sepharose. All 11 compounds with 2, 1 or 0 ring(s) were adsorbed only poorly. Similar results were obtained with the Fe and no-metal chlorin-Sepharose, suggesting that in this adsorption the role of metal in the iigand is not crucial. The adsorption of quinacrine and Rhodamine 6G to Cu chlorin-Sepharose was analyzed by use of the Langmuir equation and the dissociation constants found were in the order of 10 -5 M. The capabilities of the chlorophyllins to adsorb these mutagens and to inhibit their actions