Environmental and Molecular Mutagenesis - Legacy Tobacco ...

148 1989 EMS Abstracts
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http://legacy.library.ucsf.edu/tid/clb93d00/pdf
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.+ CENOTOXIC AC9MT#S06F MUCONDIALDEHYDE . Y . 0ehiro I C .E . Piper,l S .C . Gad,1 E .
Rohrbacher,l 1r-S . Balwierz,l S .G . Soelter,l C . Nitzi and B .D . Goldstein .2 G .D . Searle
& Co .,l Skokie, IL jMW77 and Dept . of Environmental and Community Medicine,2
University of-4d nd Dentistry of New Jersey, Piscataway, NJ 08854 .
Trans, trans-mucondialdehyde 1s a benzene metabolite that is speculated to cause
leukemia in humans . We have examined its genotoxic activities using the Ames test, a
CHO/HGPRT/micronucleus combined end-point assay and the rat primary hepatocyte UDS
assay . In the first Ames experiment, TA1535, TA100, TA1538, TA98 and TA97 strains were
treated with mucondialdehyde at six concentrations ranging from 0 .5 to 100 Ug/plate .
The high dose of 100 yg/plate was toxic to the cells and there were indications of
activity with TA100 and TA97 at 10 and 50 pg/plate . A second experiment using test
concentrations from 5 to 70 Ug/plate showed a dose-related increase with TA100, but
the response did not reach twice the value of the solvent control . However . TA97
showed dose-related mutagenic activity that exceeded two times the solvent control at
25 yg/plate and higher without S9, and at 60 ug/plate and higher with S9 . Mucondialdehyde
was toxic at concentrations above 5 yg/ml in the rat primary hepatocyte UDS
assay and there was no evidence of induction of DNA repair at lower test concentrations
. Likewise, mucondialdehyde was toxic (17% survival at 0 .8 yg/ml), but negative
for induction of HGPRT mutations in CHO cells, at concentrations from 0 .1 to
0 .8 ug/ml without S9 . Cells from this experiment examined for micronucleus induction
showed a dose-related effect, with significant clastogenic activity detected at 0 .4,
0 .6 and 0 .8 ug/ml . Further studies with mucondialdehyde are ongoing, including in vivo
micronucleus assays . The results to date indicate that mucondialdehyde is toxic,
mutagenic, and clastogenic in vitro .
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MODIFICATION OF AFLATOZIN B, INDUCED LYg00gNESIS IT ANTIBODIES . O .A . Osowole and A .0 .
Uwaifo . Biochemistry Department, University of Ibadan, Ibadan, Nigeria .
Lysogeneais, a consequence of induction of the SOS pathway, results from chromosomal
DNA lesions persisting after constitutive repair . Lysogenic induction tests in
prokaryotes are a good measure of the carcinogenicity and mutagenicity of a given
carcinogen . The effect of antiserum against aflatoxin B1-bovine serum albumin complex on
aflatoxin B1 induced lysogenesia was studied using Escherichia SAi Ku . Antibody against
aflatoxin Bi-bovina serum albumin complex was obtained after a single intradermal multiple
site injection of water in oil emulsion of the complex (66 .67yg/ml) into rabbits . The
antiserum used was obtained in the seventh week after isseunization . The results obtained
ahowed a marked reduction in the degree of lysogenesis induced by aflatoxin 81 after the
addition of the antiserum to the reaction medium prior to microsomal enzyme activation
of aflatoxin B1 . The result also showed that there was no detectable effects of the
antibody when the antiserum was added after aflatoxin 31 activation . This suggests that
the antibody in the aflatoxin B1-bovine serum albumin antiserum could interact with
aflatoxin B1 prior to its activation . It seems probable therefore, that an immune
protective effect may be exerted if the antibody intervenes before activation . Results
from equilibrium dialysis study of the interactfon of purified immunoglobulin G from the
antisera with aflatoxin 31 showed the average number of binding sites on the antibody
molecule for aflatoxin B1 being 1 .65t0 .27 with a F1' of 5 .40 Kcal/mole while the average
association constant was 1 .81f0 .19x10s 3 . These results indicate that the antibody has
high affinity for aflatoxin B1 . A possible explanation for the reduction in aflatoxin B1
induced lysogenesis is that antibody binding to aflatoxin B1 reduces epoxide formation .
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X-RAY-INDUCED MULTILOCUS DELETIONS IN THE g4--3. REGION OF A TWO-COMPONENT HETEROKARYON
OF Neurosoora rr Up COVERING THE 31174 AND hj;-l LOCI LACK THE WILD-TYPE hi;_.$ DNA IN
RESTRICTION ENZYME ANALYSES . L .K . Overton . J .S . Dubins . R .R . Cobb and ~,Z ~g ~grres .
Center for Life Sciences and Toxicology . Chemistry and Life Sciences . Research
Triangle Institute, Research Triangle Park, NC 27709 (USA)
4 mutant 1-226-565 results from a 1 .8 kb insertion in the hjgj- locus and as a
consequence has an altered banding pattern upon Ps_% I digestion and hybridization to
the hi,U- probe pNH6O (Oubins et al ., Mutations Res ., submitted) . After such
treatment fragments of 1 .4 . 4 .9 . and 7 .9 kb were seen . Similar treatment of the DNA
from the wild-type strain 74-0R23-1A showed fragments of 1 .4 . 4 .9 . and 5 .9 kb . A
series of 30 X-ray-induced pA,1 mutants (genotype $cj:,3A jg=20) induced in a twocomponent
heterokaryon (N-12) of " . Srassa have also been shown to cover the two
proximal loci . IJ,i_;=1 and 1vs-4, (de Serres . Mutation Res . . in press) . These mutants
have been subjected to restriction enzyme analysis to determine whether they resulted
from interstitial deletion . The DNA from forced dikaryons between each of the 30 AQ-
,3A ,gq=J@ mutants and mutant 1-226-565 was analyzed for the presence of "wild-type"
DNA that should be missing if these 30 mutants resulted from deletions . The
5 .9 kb fragment was missing in 27/30 forced dikaryons analyzed, indicating that the
"wild-type" his-$ locus was ∎issing in these 27 mutants ; 2/30 mutants showed a partial
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