Environmental and Molecular Mutagenesis - Legacy Tobacco ...

376 1989 EMS Abstracts
CLONING OF DNA REPAIR GENES IN HAEMOPHILUS INFLUENZAE RD Notes
R. Mody, V.P. Joshi and N.K. Notani, ion e ica 3roua BFi-fiFa AtQn ic Research Centre,
B3nbay 400085, India.
We have reported a recanbinational DNA repair systan which Is more clearly manifest
in strains like Uvr1 in which excision repair is deficient . With another UV-sensitive strain
Mbo2 also, we now observe much more of recQnbinational repair than is noted in a wild
type strain. We have earlier reported cloning of uvrl gene on an 11 .3 kb insert. The
plasrid pKuvrl fully cQnplanents Uvrl strain but not a Uvr2 strain . We now report cloning
of mbo2 gene on a 17 .7 kb insert which fully canplanents the UV-sensitivity of Mbo2
strain but not of Uvrl strain indicating that uvrl and mbo2 are not allelic . EcoRl cutting
produces two fragm ents from the 17 .7 kb insert, the Terger one of 13 kb anChe sn aller
one of 4.7 kb . Both these fragn ents have been subctoned 13 kb fragm ent subclone does
not conpianent the UV-sensitiwty of Mbo2 strain but 4 .7 kb subclone gives a partial camplem
entation. It is inferred that atleast san e of the genetic infotm ation for expressing
UV-resistance is carried on 4 .7 kb fragm ent.
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ETHENO-ADDUCT PRODUCTION BY CARCINOGENIC AND ENDOGENOUS AGENTS
Ruth A . Modzelewski, Mary K . Conner, Noriko Kawatani, Departments of Biostatistics and
Industrial Environmental Health Sciences, Graduate School of Public Health, University
of Pittsburgh, PA ., 15162 (USA)
Ethyl carbamate (EC) is a carcinogen which produces highly fluorescent etheno-adenine
(c-A) adducts in RNA . Its active metabolite is presumed to be an analogue of
chloroacetaldehyde . The abundant adenylate pool is an obvious target for c-A adduct
formation . Several e-A derivatives are potent inducers of SCEs and multiple complex
chromosomal aberrations .
Choline is an essential dietary element, cell membrane component, and a biochemical
substrate . Arsenocholine (AsCh) is a arsenic analogue of choline found in seafood, including
shrimp, crab, and some fish . Simple oxidation of the hydroxyl, moiety of choline
or its arsenic analogue produces an analogue of chloroacetaldehyde .
EC, Choline, and AsCh yielded incredibly similar fluorescent chromatogramS in extracts
of murine red blood cells exposed in vivo . HPLC elution times of several fluorescent
peaks correspond to those of standard c-adenine derivatives . The significance
and long term consequences of c-A adduct production by carcinogens and endogenous
agents remains to be elucidated . Supported by : BRSG 2 S07 RR05451-27, Biomedical Research
Support Grant Program, NIH, and Center for Environmental Epidemiology, University
of Pittsburgh, EPA CR 812761 .
378
METHODS FOR SCREENING FOR GERMINAL MUTATIONS: DETECTION OF "NON-POINT"
MUTATIONS USING A MODIFICATION OF THE "RFLP" ANALYSIS STRATEGY . H . W .
Mohrenweiser and B . A . Perry, Biomedical Sciences Division, Lawrence Livermore National Laboratory,
Livermore CA 94550
Insertions, deletions and rearrangements (I/D/R) of the DNA of the human genome have been identified
during molecular analysis of both de novo germinal mutations and inherited variants causing genetic diseases .
This class of molecular alteration in DNA structure is expected to predominate among radiation induced
mutations. A modified restriction enzyme site (RFLP) mapping strategy, using only a single restriction
enzyme digestion and then repetitively analyzing each sample with a series of probes for different loci, has
the potential to screen a significant portion of the genome in each proband for heritable, "non-point"
mutations . Results from screening 130 unrelated Caucasian individuals for variation at 40 independent loci,
using this RFLP mapping strategy, indicate the frequency of rare, inherited I/D/R variants is 3 .1 variants/
1000 loci screened. A prototype mutation screening experiment that involves screening DNA from 50
independent, clonally derived human lymphoblastoid cell ltnes, established in the absence of selective criteria
following exposure of cell cultures to a mutagenic agent, has been initiated . Two ap nt mutations have
been identified during the initial scteening of the DNA from these cell lines with sevet~NA probes, one in
the progeny of ENU treated cells and one in a cell line established following exposure of the parental cells to
X-ray. Confirmation of these apparent mutations and analysis of the molecular alteration in DNA structure is
in progress, as is continued screening of the DNA from these cells with probes for additional loci . It should
be possible with only minor enhancements of this RFLP mapping strategy to generate a significant data base
regarding the frequency of germinal I/D/R mutations in an exposed population . Workperfotmmed under
auspices of the US DOE by the Lawrence Livermore National Laboratory ; contract No.W-7d05-ENO-48
379
METABOLISM AND GENOTOXIC EFFECTS, IN VIVO . OF A MARKER FOR NfIRO-PAH . 2-NlIRO-
FLUORENE . COMMONLY FOUND IN THE ENVIRON1vIENf .
L . MBllert, J . Raftert . S . Tbmqulstt . B . BeIJe9, R ToRgArdt . T. Mldtvedt2 . M . Cortie2 and J-A .
Gustafssont, Departments of Medical Nutritlonl and Medical Microbial Ecology2. ISarolinaka
Institute and Department of Genetic and Cellular Toxicology3 . University of Stockholm .
Stockholm. Sweden
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