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mg/kg body weight by gastric intubation to male F344 rats induced a more than 100-fold increase in ODC activity (formation of up to 1120 pmoles CO2/30 min /mg protein) with a maximum after 24 h. Administration of NIAN at doses of 20-300 m g / kg body weight also induced an up to 10-fold increase in DNA synthesis (incorporation of 9400 dpm of [3H]thymidine//~g DNA) with a maxi- mum after 16 h, and induced apparent UDS in the pyloric mucosa of the stomach within 4 h after its administration. These results indicate that NIAN probably has tumor-promoting activity and may also have tumor-initiating activity in carcinogene- sis in the glandular stomach.

4 Furukawa H., K. Kawai and H. Tokiwa 1, Labora- tory of Biological Science, Faculty of Pharmacy, Meijo University, Tempaku-ku, Nagoya 468, and l Fukuoka Environmental Research Center, Fuku- oka 818-01 (Japan)

Photonitration and photooxidation of polycyclic aromatic hydrocarbons

Environmental mutagens such as nitroarenes and arenequinones were formed by visible light irradiation to polycyclic aromatic hydrocarbons (PAHs) under nitrogen dioxide. Products were analyzed by G C - M S (Hitachi M52) equipped with 1.5% silicone OV-1 column. Mononitrochrysene (m/z 273) and dinitrochrysene (m/z 318), mono- nitropyrene (m/z 247) and dinitropyrene (m/z 297), mononitrofluorene (m/z 211) and dinitro- fluorene (rn/z 256), mononitroanthracene (m/z 223) and dinitroanthracene (m/z 268), mono- nitroperylene (m/z 297), dinitrobenzo[a]pyrene (rn/z 342) were obtained from corresponding PAHs chrysene (m/z 228), pyrene (m/z 202), fluorene (m/z 166), anthracene (rn/z 178), per- ylene (m/z 252) and benzo[a]pyrene (rn/z 252). Anthraquinone (m/z 208), benz[a]anthraquinone (m/z 258), naphthacenequinone (m/z 258) and dibenz[a,h]anthraquinone (m/z 308) were ob- tained by exposure of corresponding PAHs anthracene (m/z 178), benz[a]anthracene (m/z 228), naphthacene (m/z 228) and dibenz[a,h]- anthracene (m/z 278) to nitrogen dioxide gas with

visible light irradiation. Chloroform-insoluble compounds were obtained on exposure of pyrene and perylene to nitrogen dioxide gas with visible light irradiation.

5 Hara, T., T. Shibuya, M. Katoh and Y. Matsuda, Laboratory of Genetic Toxicology, Hatano Re- search Institute, Food and Drug Safety Center, 729-50chiai , Hadano, Kanagawa 257 (Japan)

The causes of Drosophila wing spots induced by alkylating agents

Many kinds of genetic lesions can be detected in Drosophila wing spot test, e.g. gene mutation, deletion, recombination and nondisjunction. This character of test is favorable to find various types of mutagens but makes the causes of spots some- what ambiguous. This study was carried out to estimate the proportion of the spots which were caused by recombination when flies were treated with two kinds of alkylating agents. Virgin females of mwh strain were mated to males of flr strain and F 1 larvae were treated with several doses of EMS or MMS 72 h after oviposition. Two types of F 1 flies emerged. Recombination in the 3rd chro- mosome was suppressed in the one type (yellow body color) and not suppressed in the other type (normal body color). From the comparison of these types, the proportion of spots which were caused by recombination was estimated. A little less than 60% and 60-70% of wing spots were caused by recombination when flies were treated with EMS and MMS, respectively. The mean size class of spots which were caused by recombination was higher than that of other types of spots, indicating that recombination was accompanied with relatively little damage to cells. It is im- portant to clarify the causes of Drosophila wing spots in connection with the evaluation of carcino- genicity and genotoxicity of chemical compounds.

6 Hayatsu, H., Y. Ohara, T. Hayatsu, S. Arimoto, Y. Saito, M. Mifune and Y. Tanaka, Faculty of