Environmental and Molecular Mutagenesis - Legacy Tobacco ...

guanosine at the highest lonr.entration tested (1 .50 nmol/well) . Antibody 1oB4
re•rofnizod the 4-Al1}'-guHnosine adducl, with similar sensit .ivity when it is present. in
d~rn atured DNA or as the moaoadduct . A rompetitive ELTSA with fluorescence endpoint
d~_•tecl.ion wus developed lo increase assay svnsitivlty (SOt inhibition at . 400 fmol) .
SPnsitivity can be further increased by enzymatic digestion of DNA and isolation of
ndducte by immunoaffinit .y chromcd ottraphy or HPLC before analysis . These antibodies
will be used to monitor adduct levels in biological samples from smokers and
nonsmokers and r•valunted as a marker of evpusru-e• to aromat.ic aminos . This work wns
supported by a grant from NCI-CA21111 .
560
BLEOMYCIN-INDUCED ABASIC SITES WITH CLOSELY OPPOSED STRAND BREAKS : STRUCTURE,
SEQUENCE SPECIFICITY AND ROLE IN MUTAGENESIS R .J . Steighner and L .F . Povirk, Department
of Pharmacology and Toxicology, Medical College of Virginia, Richmond, VA 23298
Bleomycin-induced mutations in the lambda cI gene occur preferentially at hotspots
which share the sequence C-G-C-C . When an end-labeled restriction fragment of _cI DNA
was treated with bleomycin, and the resulting abasic (AP) sites were cleaved with
putrescine, discrete shorter double-stranded fragments were produced, whose
electrophoretic mobilities were consistent with putrescine-dependent double-strand
cleavage at or near each of the mutational hotspots . The shorter double-stranded
fragments were eluted, denatured and run on sequencing gels . Analysis of cleavage
sites and termini in each strand indicated that bivalent lesions consisting of a
strand break at the C residue in the C-G-C-C sequence, plus an AP site at the G
residue directly opposite, were formed by bleomycin at each hotspot . In separate
experiments, bleomycin-induced mutagenesis of repackaged lambda phage was reduced 2to
4-fold by treatment of the DNA with putrescine prior to repackaging . This
reduction in mutation frequency may be attributable to cleavage of AP sites with
directly opposed breaks, since endonuclease IV (which cleaved only "nonopposed" AP
sites) had no effect . Our results strongly suggest that AP sites with directly
opposed breaks are intermediates in bleomycin-induced mutagenesis . The potent
mutagenicity of these lesions is probably attributable to the simultaneous loss of
coding information at the same position in both DNA strands . The sequence
specificity for formation of these lesions was distinctly different from thsyt of
bleomycin-induced single-strand breaks .
561
MUTAGENIC EFFECTS OF PHTHALATE ESTERS AND ASSESSMENT OF RISKS POSED
TO THE ENVIRONMENT
K . Strobel and T . Grummt, Research Institute for yyg iene and Microbiology,
GDR - 9933 Bad Elster, H .-Heine-StraBe 12 (GDR)
with an annual production of about one billion pounds phthalste esters
are in wide use . In some plastic materials they make up to 50 %
of volume . By now they are widely dispersed in the environment . Knowledge
on mutagenic effects of phthalate esters is incomplete and partly
controversial . Therefore, we investigated the mutagenic activity of
i8 phthalate esters in the AMES-test and in cell cultures (FAF-celle
of Chinese hamsters) . Mutagenic effects were detected in one or both
test systems for a number of these substances . Their toxic, and partly
mutagenic, end/or carcinogenic potential as well se the fact, that
concentrations of e .g . DEHP and di-(n-butyl)phthelate in water samples
and sediment were higher than those of DDT end PCBs, have to be considered
in risk assessment for phthalate esters . The hazards which are
posed by this group of substances to the environment give rise for the
conclusion that guideline values for their presence in drinking water
have to be elaborated, aspecielly in view of the revision of WHO Drinking
water Guidelines which is being performed at present .
562
INHIBITORY EFFECT OF ASPARAGUS ON DMH-INDUCED MICRONUCLEI AND APOPTOSIS IN THE COLON
CRYPT CELLS OF MICE . H . Sun, Q . Zhu, S . Fu, Y . An, G . Dou, B . Yang and Y . Wang . Henan
Medical University, Zhengzhou, Henan 450052, People's Republic of China
By assaying of micronuclei and apoptosis in the colon crypt cells of C57 mice, we
studied the potential inhibitory effect of asparagus toward the intestinal carcinogen
1,2-dimethylhydrazine (DMH) . The original liquid squeezed from fresh asparagus
was applied as inhibitor in this study . Three groups (5 mice/group) were treated with
asparagud liquid in the dosage of 0 .1 ml, 0 .5 ml and 1 .0 ml/ mouse respectively by
stomach intubation, one hour before DMH were injected intraperitoneally . Mice injected
with DMH only were positive control and mice injected with EDTA only were negative
control . Twenty-four hours after infection with DMH, all the animals were sacrified .
http://legacy.library.ucsf.edu/tid/clb93d00/pdf
A
1989 EMS Abstracts 193
Notes