Environmental and Molecular Mutagenesis - Legacy Tobacco ...

junction protein mRNA in liver, but not in the kidney or in the stomach . Gap junctional
co®unication also plays W important role in the behavior of cancer calls . These
cells can attain inhibition of intercellular communication with surrounding normal
cells by one of two different vays : 1) Decrease of intrinsic gap junctional intercellular
communication among themselves ; 2) Maintainanca of their intrinsic intercellular
communication capacity, but with selective inhibition of communication with
surrounding normal cells . Taken together, available evidence suggests that altered
gap junctional intercellular communication plays an important role in the process of
carcinogenesis and the maintainance of the phenotype of tumor calls . Supported in
part by NCI Grant No . ROL CA40534. ' --
653
COMPARING THE FREQUENCY AND SPECTRA OF MUTATIONS INDUCED WHEN DNA CONTAINING
COVALENTLY-BOUND RESIDUES OF POLYCYCLIC AROMATIC CARCINOGENS REPLICATES IN HUMAN
CELLS . J .-L . Yang, M .C .-M . Mah, V .M . Maher, and J .J . McCormick, Carcinogenesis
Laboratory, Michigan State University, ast Lansing, MI (USA)
To gain insight into the mechanisms by which carcinogens induce mutations in
human cells, we are using a shuttle vector, pZ189, carrying a bacterial suppressor
tRNA (juRF) as the target for mutations Induced when the plasmid replicates in
human cells . We have treated the plasmid with 7,8-diol-9,10-epoxide of
benzo[a]pyrene (BPDE), 1-nitrosopyrene (1-NOP), and N-acetoxy-2-acetylamnofluorene
(N-AcO-AAF) and determined the frequency and spectra of mutations induced . BPDE
binds principally to the N2 position of guanine, 1-NOP binds to CS guanine, and
N-AcO-AAF forms deacetylated AF adducts at C8 guanine . To obtain AF adducts In
vitro, we used the trifluoro derivative . Each agent caused a linear increase in
the frequency of supF mutants as a functi Qn of DNA adducts formed, reachi qg
frequencies as high as 20 x 10'4 to 40 x 10-4, above a background of 1 .4 x 10-4 .
When compared on the basis of adducts formed, BPDE was 4 times more mutagenic than
the other 2 carcinogens . This difference may reflect intrinsic differences in
the nature of the adducts and/or their location in the gene, but may also reflect
differences in rate of removal of particular adducts . The majority of mutants
from untreated plasmids involved large deletions or insertions . Almost all of
those from treated plasmids involved base substitutions, mainly ` G-C T•A
transversions, but each agent produced its own spectrum of mutations . The hot
spots for mutations could not be explained merely by hot spots for adduct formation .
(Supported by NIH Grant CA21253 and by Contract #87-2 Arom the HEI .)
654
MUTAGENESIS BY DNA CROSSLINK PRODUCED AT MULTI-CLONING SITE OF pUC19
Fumio Yatagai, Sumiyu Hachiya, Kiyomi Nakajima (The Inst . Phys . Chem .
Res . Saitama351-01 JAPAN) and Barry W . Glickman (York University .
Toronto M3J 1p3, CANADA)
To elucidate mutation induced by site-specific DNA damage, we selected
muticloning-site of plasmid as the target . This site seems relatively
insensitive for selecting base substitution events, but it is very
useful for the detection of frameshift, deletion, and rearrangement
events . Following the treatment of pUC19 with UVA (365nm,
1 .5mw/cm2)plus 4'-hydroxymethyl-4,5',8-trimethylpsoralen (HMT, 50
ug/ml), the 51 bp of EcoRI-HindlII fragment containing the crosslink
was recovered from a 20% denaturating polyacrylamide gel . This fragment
was ligated into the large EcoRk-HindlII fragment (2635bp) and
used to transform E,_c411 JM105 . Amp transformants were rtecovered
using pre-UV (254nm, 5J/m ) irradiated E~ DII11 host . TrAnsformation
efficiency was about 13% . Approximately 5 .6% of the Amp transformants
recovered following UVA plus HMT carried i ;gZ mutations . Dideoxy
sequencing analysis of these mutations revealed three classes :
1)minus T frameshift at the EcoRl site, 2) deletion of 302 bp (315-
616), and 3) rearrangements at position 186 (involving intact 51bptarget
sequence) . These results indicate the involvement of crosslinks
in the induction of these SOS-dependent mutations .
655
SiUffiES ON THE GENOTOXICI'IY OF DLSIr'FFCI'ANTS WfA-I SOS CMOMOTFS'f
Yin Muquan, Qxn Yao[u, WangAng
Departma:t o[ Toxxx:Iogy, Second IvFititary Medical Ucriwrsty, Shanghai, China
The 906 O:ramotest is a sapd, teqiricing os+ly a singlo stnsin and a'mp1e oolotanctric enzyme as~ay,
and it doea nottoqwrc survival of tho testa stn~ thus it ooud be wed to d'etact the patooddty af
di9nfoctanl In the peraent peptr we sttxjiod the grnoto)ddty of 14 disinfoctants utdud~ng
fm :mldchyd4 glutaraidehYde, ethylaie oxide, sodium diclilaoisocyanurate, peraoetic add, hydropen
prioxid5 etltianoi, isoprophl aloohol, carbobc add lysd brarno 8asttainum, wdi=
diddon :socyu :urate mucUmq fungieide and Giangtistt using the SOS dromotest . RasuNs Bnta sttdy
http://legacy.library.ucsf.edu/tid/clb93d00/pdf
1989 EMS Abstracts 225
Notes
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