Environmental and Molecular Mutagenesis - Legacy Tobacco ...

188 1989 EMS Abstracts
NOteS " : ..
promutagenic adiucts can be studied as biologically relevant endpoints in tumor
induction studies (~t e of adduct formation, persistence, repair), as well as in
epidemiology-stddiei:3Md risk assessment calculations . Examples using model compounds
(alkylating agents, acrylonitrile) will be presented to illustrate the importance of
determining the types of mutations induced by chemicals and determining promutagenic
adducts .
http://legacy.library.ucsf.edu/tid/clb93d00/pdf
545
MOLECULAR ANALYSES OF A NOVEL LESCH-NYHAN SYNDROME MUTATION (hcstHon r ) 81 USE OP
T-LYHPHOJYTE CULTU~ES . T .R~ Skogek, L . Recig, D . SimpsonD L . ba4f~ire , S .$ .
Nelancon , H . Ogier , J .P . 0 Neill , H .T . Falta , J .A . Nicklas , and R .J . A1$ertini .
Chemical Industry Institute of Toticology, Research Triangle Park, NC (USA) ; Hospital
Saint Justine, Hontreal, Canada ; University of Vermont, Burlinton, VT (USA) .
The frequency of hprt mutants in peripheral blood T-lymphocytes of two putative
Lesch-Nyhan individuals and their parents was determined by a cell cloning assay to
quantify the frequency of thioguanine resistant mutants . The results confirm the
Lesch-Nyhan diagnosis and demonstrate that the mother has an elevated mutant frequency
consistent with being heterozygous for an hprt mutation . Mass cultures of Tlymphocytes
from both the children and their mother, as well as cultures of hDrt
mutant clones from the mother, were employed as sources of aRNA for cDNA sequence
analysis . These hprt mutants show a single base substitution (T + C transition) at
position 269 (exon 3) . The predicted amino acid change is the substitution of
threonine for methionineS7 . We term this new Leach-Nyhan mutation hertHontreal'
546
ROLE OF METABOLISM IN BENZENE-INDUCED MYELOTOXICITY AND LEUXEMOGENESIS
Smith, M .T., Yager, J .W ., Robertson, M .L ., and Eastmond, D .A .' School of Public Health,
University of California, Berkeley, CA 94720 and "Biomedical Sciences Division,
Lawrence Livermore National Laboratory, Livermore, CA 94550 .
The principal metabolitea of benzene include phenol, hydroquinone, catechol and
trans, trans-muconic acid . The repeated co-administration of two of these metabolites,
phenol and hydroquinone, produces bone marrow toxicity in mice similar to that caused
by benzene . In parallel studies, phenol has been shown to stimulate the conversion of
hydroquinone to the highly toxic 1,4-benzoquinone by myeloperoxidase, the major peroxidase
enzyme in the bone marrow . A mechanism of benzene-induced myelotoxicity involving
the accumulation of phenol and hydroquinone in the bone marrow and subsequent
stimulation of peroxidase-dependent 1,4-bensoquinone formation has therefore been proposed
. The same metabolites may also be responsible for benzene's genotoxic and leukemogenic
effects . In order to study this further, we have determined the aneuploidyinducing
and clastogenic properties of beniena's phenolic metabolites using a micronucleus
assay in cytokinesis-blocked human lymphocytes . These studies revealed that
hydroquinone was by far the most effective inducer of clastogenicity and the only
phenolic metabolite which caused a consistent, dose-related increase in aneuploid
cells . Interestingly, these effects were inhibited by the inclusion of ascorbic acid
in the incubation medium . These results suggest that an oxidation product of hydroquinone
is the metabolite responsible for the aneuploidy and clastogenicity observed
following occupational benzene exposure and thus potentially benzene-induced leukemia .
Supported by NIH grants P42 ES04705 and P30 9801896 . Work performed in part under the
auspices of US DOE by the LLNL under contract no . W-7405-ENG48 .
547
PROTEIN CONTENT OF TOBACCO CELLS IN RELATION TO THE PLANT AC'TIVATION OF
m-PHENYLENEDIAMINE AND 2-AMINOFLUORENE. S .R. Smith, M .M . Verdier, ED . Wagner and
MJ. Plewa. Institute for Environmental Studies, University of Illinois, Urbana, IL 61801 USA.
'Ibbacco cell suspension cultures activate the promutagens m-phenylenediamine and 2-aminoQuorene
with his• reversion of Sa/mondla 7jphimurium strain TA98 as the genetic end point . 7b help identify the
biochemical mechanism involved, a growth curve was established for these cells by first Inoculating several
flasks with 3 g each from a 7-day culture and then measuring fresh weight at approodmately 12-h Intervals
for 2 weeks. At the same time, protein content was analyzed using the Bio-Rad protein assay which is
based on the absorbance of the dye Coomassic Brilliant Blue 0-250 that shifts to 595 nm upon binding
to protein. Fresh tobacco cells were titered, sonicated, and centrifuged, leaving the extracted protein in
the supernatant fluid. Frozen cells were also analyzed but gave iaconsistent results . A standard curve was
determined using bovine gamma-globulin for each 24-h sample . After a lag phase of 3 to 4 days, the cells
entered log phase ; stationary phase was reached by day 7 . Protein content, however, did not follow the
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