Environmental and Molecular Mutagenesis - Legacy Tobacco ...

1989 EMS Abstracts 117
of selection pressure . The dCTP pools in the 743X and Aphhs cell lines were not Notes
significantly different . The level of total DNA polymerase activity in crude
extract from aphhs-2 clone was 30% of that observed in the parental clone . We
developed a method to quantitate DNA polymerase-a antigen at single oells in situ
using monoclonal antibody SJK 132-20 and fluorescence pseudocolor image . We found
that the antigen of DNA polymerase-a in aphhs-2 was 40 - 50% of that in the
parental 743X cells . The underproduction of the antigen of DNA polymerase-o
provides a basis for the observed Aphhs phenotype . A possible mechanism for the
underproduction of DNA polymerase-a in aphhs-2 clone is presented . (Supported by
grants from NSF : DCB 8600659 and from CWRU : RIF-Liu to PKL) .
336
4ICR0NU,C(LEI INDUC!? BY FORMALDEHYI~E IN ERYTHROCYTES OF MICE, F . P . Loaroal, G . G .
Arreola , A . Perez and T . H . Ma , Centro de Eatudios Aoalemicoe sobre Contaminacion
Anbiental, Universidad Autonoma de Queretaro, QRO Mexico, Institute for Environmental
Mamagement and Department of Biological Sciences, Western Illinois University, Macomb,
IL 61455 (USA)
Subchronic doses of formaldehyde were tested for the clastogenioity using Mouse-
Peripheral Erythrocyte-Micronucleus bioassay . Young (6 weeks old) female white aioe
(CD-7) were divided into groups of 5, and administered biweekly with 5 mg/&g, 10
mg/Kg, and 15 mg/Kg of formaldehyde (diluted with saline solution) through intraperitoneal
injection for a period of 3 months . Peripheral erythrocytes were collected
repeatedly from the tail monthly from the beginning of the experiment . Blood smears
were double stained with hematoxylin and Giemsa for micronuclei in the peripheral
erythrocytes . Micronuclei frequencies were scored (10,000 cell per slide) from each
of the treated and control (saline solution) groups . Significantly higher frequencies
of micronuclei in all the treated groups (around 0 .42) than that in the control
(around 0 .2%) groups were noted in the first month blood samples . The differences of
micronuclei frequencies in the blood samples of the second and third months were
reduced to the insignificant levels (around 0 .1% and 0 .2%) . Whether this was due to
the aging effect or adaptation to the chronic exposure or sexual specificity requires
further investigation . Results of similar studies conducted earlier in .male mice
showed no decline of MCN frequencies at the end of the third month .
337
The Role of Carcinogen DNA Adduct Structure in the Induation of Nutations .
L .L . Loechler,1 M . Benaautti,2 A .K . Basu,2 C .L . Green,2 and J .M . Lssigmann2 ;
1Boston University, Boston, MA 02215 ;
2Massachueetts Institute of Technology, Cambridge, MA 02139 .
Carcinogens induce cancer by reacting with DNA to form DNA adducts, which are
processed by cells to yield mutations ; particular mutations in proto-oncogenes can
lead to their activation to oncogenes . One of the key questions in earoinogenesis
is : what are the mechanism by which carcinogen DNA adducts induce mutations? To
answer this question, the mutations induced by specific DNA adducts in vivo must be
known, and rationale for the mutations that each induces must be der vd. Using a
combination of chemical synthetic and recombinant DNA techniques, individual DNA
adducts have been built into several vectors in vitro, these vectors placed into
bacterial cells, and the mutations induced in v vo n progeny vectors by each
individual adduct determined . Adducts to be considered include 06-Methylguanine
(o6MeGua), which is produced when carcinogenic methylating agents react with DNA, and
Thymine Glycol (TG), which is produced both by ionizing radiation and through
oxidative pathways . O6MeGua induces G to A mutations, and TG induces T to C
mutations . Proposed mechanisms of mutagenesie for each adduct will be discussed,
including the use of molecular modeling techniques to interpret the results with TG .
Preliminary data on the mutations induced by the major adduct formed in DNA from
activated benro(a)pyrene (i .e ., BP-N2-Gua) will also be discussed .
338
COMMON AND UNCOMMON INDOOR SOURCES OF MUTAGENIC AEROSOL PARTICULATE MATTER .
G6ran Ldfroth and Charlotte Stensman, Nordic School of Public Health,
S-402 42 Gothenburg (Sweden)
A number of pyrolysis precesses, which are performed indoors, have been investigated
with respect to the emission of aerosol particulate matter and its mutagenic activity
in the Ames Salmonella assay with the plate incorporation and microsuspension
methods . The emission of the gaseous pollutants carbon monoxide, isoprene and benzene
was also determined . Processes studied include smoking (sidestream) of tobacco and
herbal cigarettes, mosquito coil and incense burning and frying of minced, lean pork .
Expressed in the unit of mg per 9 material, the emission of aerosol particulate matter
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