- Email: [email protected]
Chromosomal damages induced by PhIP in cultured mammalian cells. II. SCE induction
281
genesis Division, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104 (Japan) Chromosomal damages induced by PhlP in cultured mammalian cells. 11. SCE induction A few reports have been published on SCE induction by the cooked food mutagen PhIP (2amino- 1-met hyl-6-phenylimidazo[4,5-b]pyridine) in mammalian cells. No finding, however, has been reported that PhIP could induce SCEs in the system without $9 mix. We examined the SCE induction in more detail to evaluate cytogenetic effects of PhIP with and without $9 mix, using Chinese hamster lung fibroblasts (CHL/IU) and human peripheral blood lymphocytes (HPBLs). The present study showed that PhIP induced SCEs at doses more than 1.56/zg/ml in C H L / I U and more prominently in HPBLs in the presence of $9 mix. In both cultures, SCE frequencies per cell increased 3 times more at 12.5/zg/ml when compared with the control level. On the other hand, a slight but statistically significant increase in SCEs was also detected with a dose dependence at the level up to 100/~g/ml even without $9 mix, more in C H L / I U than HPBLs. Furthermore, HPBLs showed a marked delay in the cell cycle after the treatment with PhlP and $9 mix even at low doses when compared with CHL/IU, but such effects were not observed in both cultures without $9 mix. Thus, these results indicate that the possible mechanism involved in the induction of SCEs by PhIP in the presence of 89 mix is different from that in the cells in the absence of $9 mix. Studies on the specific metabolic pathway and the mechanisms involved in SCE induction by PhlP are in progress. 79 Seki, H., M. Kuramochi and T. Tazawa, Mutagenicity Test Division, BML, Inc., 1361-1, Matoba, Kawagoe-shi, Saitama 350 (Japan) The micronucleus test on p.aminoazobenzene using mice The effect of p-aminoazobenzene (p-AAB) in the micronucleus test was studied using ddY male
mice (8 weeks old). The present study was carried out as the following tests: in test 1, the animals were intraperitoneally injected once with p-AAB (50-300 mg/kg), and the bone marrow cells were sampled 24 h after injection and stained with Giemsa. In test 2, the animals v.,ere treated twice with 50, 100 and 150 mg/kg of p-AAB by intraperitoneai injection. Peripheral blood was sampled 0 and 24 h after the 1st injection, 24, 48 and 72 h after the 2nd injection, and stained with acridine orange. In test 1, the number of micronucleated polychromatic erythrocytes increased significantly after treatment with 200 and 300 mg/kg of p-AAB. 4 of 6 mice died on 300 mg/kg of p-AAB. In test 2, p-AAB treatment produced significant dosedependent increases in the number of micronucleated reticulocytes at 24 and 48 h after the 2nd injection. The present experiments showed clearly positive results.
80 Sekijima, M. ~, D. Whong ~, H. Watabe 2, K. Sugai 2, S. Sekita a and Y. Ueno ~, ~ Department of Toxicology and Microbial Chemistry, Faculty of Pharmaceutical Sciences, Science University of Tokyo, Ichigaya, Tokyo 162, 2 Mitsubishi Yuka BCL, Ami, lnashiki, lbaraki 300-03 and 3 Division of Pharmacognosy and Phytochemistry, National Institute of Hygienic Sciences, Kamiyoga, Setagaya, Tokyo 158 (Japan) Mutagenicity of sterigmatocystin and related compounds 5'-Hydroxy-averantin (5'-HA), a novel product related to sterigmatocystin (STG), was isolated from the culture filtrate of Aspergillus rersicolor, and we investigated the mutagenicities of STG and related compounds in this study. STG, 5'-HA and averufin (AV) were isolated from the products of A. rersicolor, and O-Me-STG and O-AcSTG were synthesized from STG. AFB~ was purchased from Sigma. The Ames test in Salmonella typhi, iur;um TA98 and TA100 and the chromosomal aberration test in Chinese hamster cell line (CHL) were employed with or without rat $9 mix. In the Ames test with $9, STG, 5'-HA, AV,
genesis Division, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104 (Japan) Chromosomal damages induced by PhlP in cultured mammalian cells. 11. SCE induction A few reports have been published on SCE induction by the cooked food mutagen PhIP (2amino- 1-met hyl-6-phenylimidazo[4,5-b]pyridine) in mammalian cells. No finding, however, has been reported that PhIP could induce SCEs in the system without $9 mix. We examined the SCE induction in more detail to evaluate cytogenetic effects of PhIP with and without $9 mix, using Chinese hamster lung fibroblasts (CHL/IU) and human peripheral blood lymphocytes (HPBLs). The present study showed that PhIP induced SCEs at doses more than 1.56/zg/ml in C H L / I U and more prominently in HPBLs in the presence of $9 mix. In both cultures, SCE frequencies per cell increased 3 times more at 12.5/zg/ml when compared with the control level. On the other hand, a slight but statistically significant increase in SCEs was also detected with a dose dependence at the level up to 100/~g/ml even without $9 mix, more in C H L / I U than HPBLs. Furthermore, HPBLs showed a marked delay in the cell cycle after the treatment with PhlP and $9 mix even at low doses when compared with CHL/IU, but such effects were not observed in both cultures without $9 mix. Thus, these results indicate that the possible mechanism involved in the induction of SCEs by PhIP in the presence of 89 mix is different from that in the cells in the absence of $9 mix. Studies on the specific metabolic pathway and the mechanisms involved in SCE induction by PhlP are in progress. 79 Seki, H., M. Kuramochi and T. Tazawa, Mutagenicity Test Division, BML, Inc., 1361-1, Matoba, Kawagoe-shi, Saitama 350 (Japan) The micronucleus test on p.aminoazobenzene using mice The effect of p-aminoazobenzene (p-AAB) in the micronucleus test was studied using ddY male
mice (8 weeks old). The present study was carried out as the following tests: in test 1, the animals were intraperitoneally injected once with p-AAB (50-300 mg/kg), and the bone marrow cells were sampled 24 h after injection and stained with Giemsa. In test 2, the animals v.,ere treated twice with 50, 100 and 150 mg/kg of p-AAB by intraperitoneai injection. Peripheral blood was sampled 0 and 24 h after the 1st injection, 24, 48 and 72 h after the 2nd injection, and stained with acridine orange. In test 1, the number of micronucleated polychromatic erythrocytes increased significantly after treatment with 200 and 300 mg/kg of p-AAB. 4 of 6 mice died on 300 mg/kg of p-AAB. In test 2, p-AAB treatment produced significant dosedependent increases in the number of micronucleated reticulocytes at 24 and 48 h after the 2nd injection. The present experiments showed clearly positive results.
80 Sekijima, M. ~, D. Whong ~, H. Watabe 2, K. Sugai 2, S. Sekita a and Y. Ueno ~, ~ Department of Toxicology and Microbial Chemistry, Faculty of Pharmaceutical Sciences, Science University of Tokyo, Ichigaya, Tokyo 162, 2 Mitsubishi Yuka BCL, Ami, lnashiki, lbaraki 300-03 and 3 Division of Pharmacognosy and Phytochemistry, National Institute of Hygienic Sciences, Kamiyoga, Setagaya, Tokyo 158 (Japan) Mutagenicity of sterigmatocystin and related compounds 5'-Hydroxy-averantin (5'-HA), a novel product related to sterigmatocystin (STG), was isolated from the culture filtrate of Aspergillus rersicolor, and we investigated the mutagenicities of STG and related compounds in this study. STG, 5'-HA and averufin (AV) were isolated from the products of A. rersicolor, and O-Me-STG and O-AcSTG were synthesized from STG. AFB~ was purchased from Sigma. The Ames test in Salmonella typhi, iur;um TA98 and TA100 and the chromosomal aberration test in Chinese hamster cell line (CHL) were employed with or without rat $9 mix. In the Ames test with $9, STG, 5'-HA, AV,