Environmental and Molecular Mutagenesis - Legacy Tobacco ...

f 1989 EMS Abstracts 195
Notes
(CSGMT) to scrutinize protoc,Qts and to reach a standard protocol so that all participants
can obtain data under optimal conditions, and thus results can be compared regardless
of time, place, and person . Firstly, we examined sex-related difference in the test and
suggested that the use of male mice is sufficient for general screening (Mutation Res .,
172, 151, 1986) . Secondly, we examined strain-related difference and concluded that
any strain could be used as a tester, though MS/Ae tended to show the highest
response, especially at higher doses (op . cit ., 204, 307, 1988) . Thirdly, administration
route (ip and po)-related difference was exaaained ; the results will be presented
separately in the present meeting . Fourthly, dosing times and sampling timing are now
under study . Some preliminary results are presented and discussed .
566
MATERNAL INHERITANCE OF ms GENE, S . Sutou and S . Sato
(Central Research Institute, Itoham Foods Inc ., 1-6-21 Mita, Meguro,
Tokyo, 153 Japan)
MS/Ae mice, which are mutagen-sensitive in both the dominant lethal
test and micronucleus test, and CD-1 mice, which are the parental strain of
MS/Ae, were mated in all four possible combinations . Both male and
female offspring were subjected to the micronucleus test using mitomycin
C(MMC), colchicine (Col), and 6-mercaptopurine (6-MP). Col showed
equivocal results . However, MMC and 6-MP clearly showed differential
responses in that both male and female offspring from CD-1 dams had
lower incidences of micronucleated polychromatic erythrocytes than those
from MS/Ae dams regardless of sire strains . In addition, body weights of '
offspring from MS/Ae dams were lower than those from CD-1 dams
regardless of sires . These results strongly suggest that 1he ms gene (or
genes), which regulates the characteristics of MS/Ae, is maternally inherited .
567
IN VITRO tdICRONOCLEI IN THE MOUSE MAMMARY EPITSSLIAL C$LIS GROWN UNDER
SERIIM-FREE CULTURE CONDITIONS
Kunio ,Suzuki and Tomotari Mitsuoka, Animal and Cellular Systems
Laboratory, and Frontier Research Programs, The Institute of Physical
and Chemical Research (RIKEN), Wako, Saitama 351-01, Japan .
Although epidemiological studies suggest that dietary factors are
associated with breast carcinogenesis, the specific carcinogen involved
in cancer of the breast remains to be identified experimentally . In an
attempt to establish an in vitro short-term test for breast carcinogens,
we studied several known carcinogens tested by micronucleus assay in the
primary cultures of mouse mammary epithelial cells . Mammary epithelial
cells from 2 month old ICR virgin mice were cultured on collagen gel in
serum-free Ham's F-12/Dulbecco's modified Eagle's medium supplemented
with insulin, bovine serum albumin, epidermal growth factor, transferrin
and cholera toxin . At day 6 of culture, known chemical carcinogens were
added to the cultures, and the number of micronuclei per 1,000 cells was
scored at 24 hr after treatment . Two breast carcinogens, g-methyl-gnitrosourea
(MNU) and 7,12-dimethylbenz[a]anthracene (DMBA), increased
the micronuclei incidence in the cultures . The cells grown in this
serum-free medium metabolized DPIBAA to the activated form . These results
suggest that the .quantitation of micronuclei in the mouse mammary
epithelial cells cultured under serum-free conditions might be used as
an in vitro short-term screen for breast carcinogens .
568
CANCER PROMOTERS AND THEIR EFFECT ON THE MUTAGENICITY OF MUTACARCINOGENS
Dalisay Chionglo Sy, U .of Santo Tomas, Fac .of Medicine,Dept of Biochem .
Studies have indicated the cancer-promoting activities of phenobarbital(pheno)
and saccharin (sacl . The possibility that their effects occur
thru enhancement of a pre-existing mutagenic condition was tested using
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