Environmental and Molecular Mutagenesis - Legacy Tobacco ...

: 1989 EMS Abstracts
optimally at 25 'C in ttSg TC-199 medium containing 10% fetal bovine serum, but slower Notes
growth continued down ta 4°C, where they could be stored for prolonged periods . They
had a 32-h cell cycle time laken up by a 20-h S period as determined by the
autoradiographic analysis of the fraction of labeled mitosis . 'Itre cultures showed
relatively high mitotic index (0 .84-2 .35%) during exponential growth phase lasting about
7 d . Karyological analysis of the cells at the different subculture passages revealed
constant chromosome modal number of 23 consisting of metacentric or submetacentric
chromosomes which were primarily similar to those of in vivo cells except one additional
chromosome . The spontaneous-sister chromatid exchange rate was 5 .3 per metaphase . When
ULF-23HU cells were exposed to N-methyl-N'-mitro-N-nitoreoguanindine, mitomycin C,
N-methyl-N-nitrosourea, 4-nitroquinolin-N-oxide and cie-platinum (II) diamine dichloride
dose-dependent increases in sister chromatid exchanges were clearly detected .
FLthermore, ULF-23HU cells responded to the indirectly acting mutagens (aflatoxin B1,
cyclophosphamide and 4-aminoazobenzene) without adding a drug activation system . These
rrsurts offered the high possibility of the use of this cell line as a suitable in vitro
model for clastogenicity studies in fish .
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CFUtOMOSOME CHANGES IN CELL TRANSFORMANTS INDUCED BY GENOTOXIC AND NON-GENOTOXIC AGENTS .
E . M . Parry, J;M . Parry, T . Issa, M . Kadhim, R . Porter, D . Devi, School of Biological
Sciences, University College of Swansea, Swansea SA2 8PP .
Syrian hamster dermal (SRD) cultures exposed to carcinogens undergo progressive
changes from primary isolation via the formation of immortal cultures to the production
of transformed tumourigenic clones (Newbold et al 1982) . Thase culture rhanges may be
induced by treatments with agents characterised as acting predominantly by mechanisms
involving DNA interactions (genotoxic) and by a variety of non-genotoxins . We have been
investigating the chromosomal (numerical and structural) and division characteristics
(eg mitotic spindle fidelity) of SHD cultures exposed to both genotoxins and nongenotoxins
. Immortal cultures which escape culture senescence (normally occurs after 15
population doublings) generally show the presence of significant numbers of polyploid
cells and high levels of spindle fidelity . Treatment of immortal cultures with
carcinogens results in the progressive loss of chromosebes (predominantly from the
polyploid population) resulting in the formation of hyperdiploids and the production of
fully transformed colonies . Karyotype analysis of transformed SHD cultures has
demonstrated a variety of aberrations with a transloc,ation of chromosome 11 being the
most common event . This translocation is found in all the cells of clones transformed
with alkylating agents and benzo(a)pyrene and initially at a low frequency in cultures
transformed with diethylstilboestrol . With further subculturing, individual clones
progress to become homozygous for the translocated chromosome 11 . Our data sugfest that
the SHD system provides a suitable model for the study of the mechanism of action of
both genotoxins and non-genotoxins . Newbold, R . F ., Overe11,R . W . and Connell, J . R .
(1982), Nature ?Q9, 633-635 .
438
THE DETECTION OF ANEUGENS USING YEASTS AND CULTURED MA64fALIAN CELLS . J . M . Parry, E . M .
Parry, T . Warr, A . Lynch, S . James . Biological Sciences, U .C . Swansea SA2 8PP .
The EEC's aneuploidy project involves a study of a range of assays using a common
series of chemicals . The core chemicals selected for their ranPe of cellular activities
consists of colchicine (COL), econazole (EZ), Chloral hydrate (CR), hydroquinone (HQ),
diazepam (DZ), thiabendazole (TB), cadmium chloride (CD), tbimerosal (TM),
pyrimethamine (PY) and vinblastine (VB) . These chemicals are being tested in assays
ranging from in vitro polymerisation of tubulin to the induction of numerical
chromosome changes in the germ cells of intact rodents . We have been studying the 10
chemicals to measure their ability to induce chroswsome loss in yeast D6, cell division
aberrations, chromosome number changes and micronuclei formation in primary and
immortal Chinese hamster cultures using a variety of protocols . In yeast D6, five'of
the chemicals namely EZ, TM, TB, HQ and CH produced significant increases in chromosome
loss, CD, PY and DZ produced only marginal increases in monosozd and COL and VB were
inactive . These data suggest that fungi are at best only capable of detecting a
fraction of those chemicals which are capable of inducing aneuploidy in mammalian cells
(Parry and Parry (1988) . In our hands the most time and cost effective in vitro assay
for detecting potential aneugens was the measurement of aberrations of aell division
using procedures which differentially stain the spindle and chromosomes (Parry et al
1985) . This assay was capable of detecting induced division abnormalities after
exposure to all the test chemicals using relatively simple protocols and in a variety
of cell types . Parry E . M . et al (1985) Mutation Res . 150, 369-381 . Parry E . M . and
Parry, J . M . (1988) Aneuploidy, Part B : n uction and 3et Svstems, 169-1g8 . Alan R .
Liss Inc . New York .
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