Environmental and Molecular Mutagenesis - Legacy Tobacco ...

200 1989 EMS Abstracts 71
Glickman, B .W., MUTATIONAL SPECIFICITY AS A WINDOW ON THE MECHANISMS Notes
OF MUTATION, Biology Department, York University,4700 Keele Street,
Toronto, Canada M3J 1P3
The development of cloning and sequencing technology has permitted the examination
of the nature of mutation at the molecular level . These studies have in many cases
confirmed the targeted nature of mutation and hence, provided insights into the lesions
responsible. Mutational spectra obtained following treatment with a variety of agents
also confirm that mutation is non-random . In some cases this appears to be related to
the initial deposition of damage, in others, it likely reflects differences in the efficiency
of repair at different sites . Spectra may also reveal a component of mutation that
reflects the influence of the local DNA sequence on the accuracy of repair or replication
past a DNA lesion . Studies with a diverse series of agents over a broad ran*e of doses
in several repair deficient backgrounds have contributed to our current view of the
mechanisms of mutation. This lecture will concentrate on the kinds of lessons that
might be )earned from the study of mutational spectra . In particular, we will examine the
mutational specificity of a series of alkylating agents and discuss the basis of their
mutational specificity in light of both the expected lesions and the role for DNA repair
in the avoidance and/or fixation of mutation .
201
MOLECULAR SPECTRA OF L5178Y/tk'/' MUTANTS INDUCED BY DIVERSE MUTAGENS . P .
Gbver, R . Krehl and D. Clive, Wellcome Research Laboratories, Research Triangle Park, NC 27709
U5A
Southern blot analyses were performed on DNA from at least 10 large and 10 small colony tk-Imutants
induced by each of 10 mutagens [2-amino-N6-hydroxyadenlne (AHA), EMS, MMS, 2-AAF,
methotrexate (Mtx), caffeine, methapyrilene (MP), m-AMSA, hycanthone methanesulfonate,
procarbazine (Proc)) . Two molecular mutant genotypes were recognized upon digestion with Nco-1 and
subsequent probing with 1 .1 kb cDNA Insert from plasmid pMtk 4 (ATCC N37556) : (1) no detectable
alteration and (2) absence of the newly mutated tk allele as Indicated by the absence of the 6 .2 kb
fragment (Applegate and Hozier, Banbury #28 : page 213, 1987) . In combination with the previously
established chromosomal nature of most small colony tk -I' mutants (Moore et al ., 1985), this
pemritted the classification of these 10 mutagens according to the relative proportions of each of 4
classes of genetic damage they Induced . AHA and EMS gave mutational spectra consistent with their point
mutational effects In other systems . The other 8 mutagens Induced mostly small colony mutants, most of
which had lost the entire tk allele . Mtx Induced high frequenciei of large colony mutants at the rk
locus, mostly lacking the tk allele, and was weakly or nonmutagenic at the hemizygous hprt locus . Four
mutagens--Mtx, caffeine, MP and Proc--lack structural alerts for DNA reactivity (Ashby and Tennant,
Mutation Res ., 204 : 17-115, 1988) Implying a major class of non-DNA targets for mutagenicity in
mammalian cells (Clive, these abstracts) . The mutagenicity spectra for 2-AAF . Hyc and caffeine are
quite similar, raising the possibility that the DNA adducts of 2-AAF and the Intercalating activity of Hyc
may not be their principle mechanisms of mutagenicity In mammalian cells .
202
EVALUATION OF THE CLASTOGENIC AND MUTAGENIC POTENTIAL OF DIETHYLENETRIAMINE (DETA)
B . Bhaskar Gollapudi, V . Ann Linscombe, and Anil K . Sinha, The Dow Chemical Company,
Health and Environmental Sciences, Freeport, TX 77541
DETA (C .A .S . N111-40-0), a colorless/yellowish hygroscopic liquid, is widely used
in the production of paper wet-strength resins, epoxy-curing agents, chelating
agents, lubricating oil and fuel additives, surfactants, and corrosion inhibitors .
The clastogenic potential of DETA was evaluated in vitro by treating Chinese hamster
ovary cells in culture for 4 h with 250, 833, and 2500 pg/ml DETA in the presence
and absence of a metabolic activation system (Aroclor 1254-induced rat liver S-9) .
The treatments did not induce significant increases in the chromosomal aberration
frequency in cells harvested 18 h after termination of the treatment
. DETA, when
ad .inistered by oral gavage to CD-1 mice at dose levels of 85, 283, and 850 mg/kg
body weight, did not significantly increase the frequency of micronucleated bone
marrow polychromatic erythrocytes at any of the three sampling times (24, 48, or 72
h) . The mutagenic potential of DETA was evaluated in the male germ cells of
Drosophila melanogaster by the sex-linked recessive lethal (SLRL) assay . Adult
Canton-S males were allowed to feed on treatment solutions containing 60 mM DETA for
22-24 h . The treated post-meiotic male germ cells were sampled in three broods of
3, 2, and 2 days each . The treatment did not significantly increase the frequency
of SLRL mutations . Thus, DETA failed to induce a genotoxic response in any of the
test systems employed .
http://legacy.library.ucsf.edu/tid/clb93d00/pdf