Environmental and Molecular Mutagenesis - Legacy Tobacco ...

96 1989 EMS Abstracts
6
Notes
http://legacy.library.ucsf.edu/tid/clb93d00/pdf
:d witli the atract cf C]i6rae emdidne at 3TC for 2 boun, thepn ~eh(ye ~activity 11 -Balactoaidau was tottad which
L~daa~ea~ : the S06~set~pon io t~~ Sv : e~t td I0a/ft af tlrc~aonlr~d rapo~ivebr. aythe +~icneo o-
OW 1 (rec~A441) te o~'% SOe~ and 60e/. ~ the~aaurob but had not eda(on SOB rctw~a~k gene app osion i~ E6
a.df QW1107 ( laulSl )(arore tlrn 9SK of tbe controi) . So it tu+mtm that thtae l~e nn&ars coetaui the
ialr~iton of RxA proteaoe and nay be utod u antinutayr~u and/a antxarrirwgau .
274
CNRONOSORE ABERRATIORS IR NUNAR LYNPNOCYTES AS AR IROICATOR OF RADIATIOR DANACE
Jin Cuithen, Institute of Radiation Nedicine, Beijing, China
The analyses of chroaosoae aberrations in huean lymphocytes have shown their
usability for the estioation of individual doses of over-exposed persons in radiation
accidents and for the assesseent of their late radiation effects . Our laboratory
has been involved in the cytogenetic studies for radiation accidents in
China . The aain results can be suosarited as follows : 1) Under the circumstances
of single acute exposure, the vast oajority of aberrations observed soon after
the exposure were of unstable types . Among thes, the incidence of dicentries
plus rings could be used to ∎ake reliable dose estisation . The results were eonsistent
with the clinical courses of the vioties . 2) If the blood culture ras
done s .veral eonths after the exposura, the aberration frequencies could not
be used as a biological dosimeter, but it still showed sooe general correlation
vith radiation dose previously received . 3) Follor-up studies on over-exposed
peraons indicated that most of the remaining aberrations were of stable types .
4) The chroeosoae analyses for victims following protracted exposure lasted half
year exhibited evidence that the frequencies of unstable types were coeparable
vith that of stable types . 5) G-banded chromosome analyses carrying out on 5
victies, vho received accidental over-exposure several years ago, showed a nonrando∎
distribution of break-points . They vere eainly clustered in soae chroeosoees
and vere preferentially located in the regions Sq3, 6q2, 9q3, 14q3, etc . Soae
break-points were near or at the map sites of the known oncogenes .
275
TEMPERATURE EFFECTS ON RADIATION-INDUCED CHROHOSOHAL ABERRATIONS IN THE PRESENCE OR
ABSEN*E OF DIMETHYL SULFOXIDE . E .E . Joiner, L . G . Littlefie~d, S .P Colyer* and E .L .
Frome 1, Oak Ridge Assoc . Univer ., and Oak Ridge Nat 1 . Lab . , Oak Ridge, TN (USA)
Studies of the dose response relationship for dicentrics in human lynphocytes
exposed to X-rays at 37°C or 4°C demonstrated that radiation temperature acts as a
dose-modifying factor by influencing the for .ation of chromatin lesions that lead to
aberrations (Gumrich st al ., Int . J . Rad . Eiol ., 49 :665-672, 1986) . We employed DNSO
as a model OH radical scavenger in experiments to determine to what extent radiation
temperature modifies the proportions of aberrations resulting from DNA damage indueed
by direct ionisations vs OH radical attack . Human whole blood was maintained at
temperatures of 4°C vs 37°C in the presence or absence of 1M DHSO during exposures to
1 .04, 2 .08 and 4 .17 Gy X-radiation . Lymphocytes were washed and cultured for 48 hr .,
and aberrations were scored in lst division metaphases . Dicentric yields in cells
irradiated at 37°C in the presence of Dtt30 shoved reductions of 650 compared to
yields observed in unprotected cells . For lymphocytes irradiated in the absence of
DNSO, dicentric yields were 411 lover following exposures at 4°C than the yields
observed at 37°C . In contrast, when cells protected by Dt4S0 were irradiated,
dicentric yields at 4°C were only 211 lover than those observed at 37°C . These
preliminary results suggest that the effects of cold temperature (4°C) on the yields
of radiation-induced chromosomal exchange aberrations in human whole blood
lymphocytes are primarily due to the inhibltion of the indirect radiochemical actions
of OH radicals on DNA targets . Supported by U .S . DOE/ORAU Contract
DE-AC05-760R00033 .
276
MOLECULAR ANALYSIS OF RADON-INDUCED MUTANTS R .F. Jostesl, R .A . Giesi,
T .L . Morganl, E .N . Fleck:, K .P . Gasperi, and F .T .Crossl . lPacific Northwest
Laboratory, Richland, Washington and $WhitRian College, Nalla Walla, Washington .
An in vitro system for exposing RutRtiaalian cells to radon gas and its daughters has
been developed in our laboratory . Cells are exposed in spinner flasks and the doses
reported here are to the cell culture medium . Radon-induced mutations at the HGPRT
locus in Chinese hamster ovary cells show a linear dose response with an induced
frequency of 1 .0 x 10-o mutations per viable cell per c6y . To date we have isolated
35 mutants for molecular analysis . Southern blot analysis of DNA from 21 radoninduced
HGPRT- cell lines indicated that 11 (52k) were caused by a complete deletion
of the gene . Three mutations (14%) showed altered bandin~ patterns indicative of
subtotal deletions and the remaining 7 mutations (34%) conta ned changes undetectable
by this analysis . (Work supported by the U .S . Department of Energy under Contract
DE-AC06-76RL0 1830) .
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