Ae mice

294 absence of $9 mix. The AcOEt ext was applied to a Sep-Pak silica cartridge and the adsorbate was eluted with dichloromethane, ethylacetate and then methanol. These three fractions induced 246 revs/100/~g, 414 r e v s / 5 0 0 / x g and 147 revs/500 ~g, respectively. When the chromosome aberration test using CHO-K1 cells was carried out, the frequencies of aberrant cells after treatment with dichloromethane and ethylacetate fractions were 12%/9.8 tzg and 3 6 % / 2 0 /zg, respectively. But the methanol fraction showed no effect at an amount of 65 ~g. The dichloromethane fraction contained MX. These results show the existence of new mutagens in the ethylacetate fraction. Purification of new mutagens using H P L C was achieved. Identification of the chemical structures is under way. 82 Sutou, S., and N. Higashikuni, ltoham Central Res. Inst., 1-2 Kubogaoka, Moriya, Ibaraki 302-01, Japan The whole mitochondrial DNA sequence of M S / Ae mice Since many carcinogens judged to be quasipositive or inconclusive inducers of micronuclei become positive when M S / A e mice are used, MS mice have been proposed to be effective for screening. Because the mechanism of high sensitivity of the MS mice is not clear, however, interpretation of results obtained with MS mice is difficult. When males and females of MS and CD-1, the original strain of MS, were crossed and indices of high sensitivity, body weight, and the number of offspring were examined to clarify the mechanism, a maternal effect was prominent. Mitochondria relate to maternal inheritance. It is said that D N A repair capability is poor and mutations occur rather readily in mitochondria. MS mice are also sensitive to y-rays, of which the effect is related to radical formation rather than changes of drug metabolizing enzymes. Thus, we examined the mitochondria of MS. Mitochondrial D N A of MS mice was isolated and the whole sequence was determined by the shotgun method, by kilo-sequencing, or by subcloning of fragments after restriction enzyme di-

gestion. When the sequence was compared with 16,295 bases of mouse L cells determined by Bibbs et al., 6 transitions, 3 transversions, 1 insertion of a single base, 2 insertions of triplets, and 2 deletions of a single base were found, giving a total of 16,300 bases, 5 bases longer than the mitochondrial D N A of L cells. The mitochondrial DNAs from MS and L cells are currently being compared with that of CD-1. 83 Suzuki, J., S. Hattori, Y. Nakajo, M. Ochiai and S. Suzuki, Faculty of Pharmaceutical Sciences, Science University of Tokyo, 12 Ichigaya, Shinjuku-ku, Tokyo 162, Japan Levels of urinary mutagenicity and excretion of l-aminopyrene in humans exposed to automobile exhaust Levels of urinary mutagenicity and excretion of 1-aminopyrene (1-AP) in persons exposed to automobile exhaust for 4 h at a typical street intersection with a large traffic volume were compared with those in nonsmokers and smokers in order to find an indicator for monitoring exposure level to automobile exhaust. Mutagens and 1-AP in urine were extracted with blue rayon after hydrolysis under acidic conditions and then measured by means of mutation assay with $9 mix using S. typhimurium YG1024 and a fluorescence-HPLC method. Urine mutagenicity was not so increased by exposure to automobile exhaust as by smoking. Urinary excretion level of 1-AP in persons exposed to automobile exhaust (2307 _+ 1746 n g / g creatinine, n = 7) was significantly higher than in nonsmokers (140 _+ 60 ng/g, n = 5) and smokers (146 _+ 102 ng/g, n = 4), although their individual variations were very large. A high-level of 1-AP was also observed in the urines of policemen who were on duty in a police box in a commercial district with a large traffic volume. Additionally, mutagenicity and 1-AP levels of urine of two persons exposed to automobile exhaust were followed over a period of 24 h. The result also indicated that 1-AP excreted in urine is a useful indicator for monitoring exposure to automobile exhaust.