Environmental and Molecular Mutagenesis - Legacy Tobacco ...

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presence of .c_,lyDhimuriu_.n TA 98, TA 98NR and TA 98/1,8DNP6 . Cytosol, (0.8 mg/plate) as the sole
exogenous enzyme fraction, enlUnced the mutagenicity of 2- and 3-nitrofluoranthene (2-NP and 3-NF) and
1,3 dinitrofluoranthene (1,3-I7NF) in the three strains 2- to 9-fold over that observed in its absence . However,
the number of revertants with 1,2 dinitrofluoranthene (1,2-DNF) was decreased 70% by cytosol. The
inclusion of microsomes alone (0.2 mg/plate) decreased the mutagenic response by 57-98% . The addition of
both cytosol and microsomes, to reconstitute S9, resulted in a marked decrease In the mutagenicity of the
compounds . In a related study, the mutagenicity of three dinitropyrenes, 1,3-, 1,6- and 1,8-dinitropyrene
(1,3-, 1,6- and 1,8-DNP) was also rnarkedly enhanced by cytosol m TA 100. This was especialily noticeable
when 1,3 DNP was the substrate . Amongst other possibilities, these findings suggest that cytosol may contain
enzymes more potent than the constitutive bacterial .naroroductases and/or acetylases in the activation of
nitroarenes to mutagens or that the bacterial enzymes are rate limiting components of the system . Microsomes
contain deactivating enzymes and when combined with cytosol to reconstitute S9, the deactivation potential of
the microsomes overshadows the activation potential of the cytosol and a decreased mutagenic response is
expressed .
525
ALTEltATIONS IN DNA CONTENT AND CHRONOciOHE COMPOSITION AS
RELATED TO AGEING IN MAMMALS
A . Sharma, S,Sen, G . Talukder, Human Genetics Unit, Centre for Advanced $
Study in Cell & Chromosome Kesearch, Department of Botany, University
of Calcutta,' Calcutta 700019, India
In view of the hypothesis that DNA is involved in the process of
ageing, the present investigation was undertaken to find out the
relationship between DNA content and progressive ageing in ratss
in vivo and human leucocyte cultures in ~itrQ Chromosome studies
from bone marrow cells of Kattus norvea-Lcus of .twelve different age
groups showed a significant increase in the frequency of hypodiploid
cells with ageing . This increase was, however, not seen in the .gonadal
cells . A similar enhancement was recorded in the number of hypodiploid
cells in the cultured lymphocytes from sex-mrtched human subjects of
ten different age groups . DNA estimated in situ in bone marrow nuclei
did not change to a significant extent with ~ncieased age . The observations
made in proliferating human lymphocytes supported those made on rats
in vivo . DNA contents of differentiated tissues, including brain, lung,
lve lr, heart and kidney from fetal to adult rats showed an organ-specific
variation(within the limits of statistical significance) . It may be
due to controlled DNA amplification during differentiation and
maturation of the tissues .
526
GENOTOXIC EFFECTS OF INDU3TKIALISATION IN SELECTED POPULATIONS
A .Sharma, A. Raychoudhury, A . Banerjee, M .De, T .Das, M.Joardar,
K . Agarwal, A .K . itoy, S . Maity, G alukder, Human Genetics Unit .
Centre for Advanced Study in Cel & Chromosome Research, Department
of Botany, University of Calcutta, Calcutta 700019, India .
A comparison was carried out between selected populations from the
Eastern India, who had been exposed, directly and indirectly, to
industrialisation for 10 to 40 years and non-exposed populations
from totally rural areas . The endpoints observed were blood genetic
markers and cytogenetic parameters . In 1648 blood samples from
healthy male age-matched donors, the frequency of abnormal variants
of lipoprotein and hemoglobin was significantly higher in the
exposed populations . There was no appreciable difference, however .
in the incidence of markers not related to life style or diet, like
haptoglobin, transferrin, acid phosphatase, lactate dehydrogenase .
ABO system and Rh factor . The frequencies of chromosomal aberrations,
micronuclei and sister chromatid exchanges were significantly higher
in leucocyte cultures set up from 437 individuals tested from the
exposed group, as compared with corresponding cultures from persons
belonging to the non-exposed group . The difference between persons
who had been exposed directly and those who had been exposed
indirectly was not statisticilly significant .
http://legacy.library.ucsf.edu/tid/clb93d00/pdf
1989 EMS Abstracts 181
Notes