Environmental and Molecular Mutagenesis - Legacy Tobacco ...

116 1989 EMS Abstracts
Notes chromatin ia becoming altered by a time-dependent process. After 10-20 min of poet-UV incubation at 37T~ the
relative DNA-damaging effects (measured as DNA strand breaks or DNA cross-links) of bleomycin, gamma
radiation and 8-methoxypsoralen was increased 50% . However, after 60 mm the eHectswere back to control levels .
These alterations might reflect events preparing the chromatin for the repair of W-induoed DNA damages .
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LACK OP INDUCTION OF SCEs IN HUMAN LYMPHOCYTES EXPOSED TO MONOENERGETIC NEUTRONS
L .G . Littlsfield, E .L . Proae*I, E .E. Joiner, apd S .P . Colysrt, Oak Ridge Associated
Universities and Oak Ridge National Laboratoryl, Oak Ridge, TN (USA)
Low-LET X- or gamaa rays induce few (if any) DNA lesions in boasn lymphocytes that
are axpressed as SCEs . Recently, however, increased SCEs have bsen observed in
lymphocytes exposed to 42 MsV d-Ee neutrons pro .pting the suggestion that the REE for
SCE induction by higb-LET radiation suy be effectively infinite (J . Savage, M .
Holloway, Sr . J . Radiol . 61 :231, 1988) . We conducted studiss to determine whether
aonoenergetic neutrons induce DNA lesions that lead to SCE formation, and if so,
whether such damage is modifiable by radioprotsctive cheaicals that selectively
scavenge OH radicals . Busan lymphocytes suspended in culture sedium with or without
1M DMSO were exposed to 5 doses each of 6 .0 and .44 M.V neutrons at RARAP . Chromosome
aberrations and SCEs were evaluated in 1at or 2nd division staphases from 48br
cultures . As expected, the two high-LET radiations ware considerably more efficient
in inducing aberrations than X-rays, with maxisum calculated RBEs of 6 and 16 for
dieantric induction by the 6 .0 and .44 NeV neutrons . Eased on results of curve
fitting data, we estimated that OH radical aisdiated lesions in DNA contribute 402 and
15% . respectively, of the dose dependency for aberrations resulting from exposures to
the 6 .0 and .44 MsV neutrons . In contrast, SCE frequencies showed no correlation with
neutron energy, radiation dose, nor presence or absence of radioprotector during
exposure . We conclude that while high LET radiations are extremely efficient in
inducing DNA lesions that lead to chroaoso .e aberrations, sonoensrgetic 6 .0 or .44 M .V
neutrons do not induce DNA lesions that lead to SCEs . Supported by DOE contract
DOE-AC05-760R00033 .
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MUTAGP.NICITY SLREENING OF WATER EXTRACT8 PROM 102 XIKIIS OF CRUDE DRUGR IK CHIKF.SE RF.DICINC9
Liu Dexiana , Yin Xuojun
Laboratory of Medical Gonetics of Kestern Region Hospital,Orweehi,Xinjit-ig ,
- People's Republic of China
In an a!tenpt to explore the autagonicity of the Chinese Medicinal herbs,102 crudo drx s :.n nu-.ber,
eeployed comm,~only as traditional Chineso medicines,vore chosen and boiled,and then uaod tlieir obtained
water extracts as the sample of aasay .Each extract vas assayed by Ames bioaa.ay system with TA 38 and
TA 100 strains .At aame time,tho intreperitoneal injection in mice vaa aivon with the ditferent doses .
and obaerved their ehromoaomal aberration (CA) and micronucleir (PC3KF) .Aaes test revealed thut,p
extracts of the crude drugs (for instsnos,Astr .galus Meaberaneous Ege,,3ophora Japonica L.and xuceh~+la
Ulnoidea Oliv .) vore poaitivs (3/102 ;2 .97t) .Aatragalua Kenberancous Ege in the presence of E9 mix vith
strain TA 98 could induce tho number of revertant colonies to increase threo tieos (40mr,/platc) enre
than spontaneous revertant colonies ;Sopho{~a Japonica L .in the presence or in tha abscnce ol £9 aix vith
strain TA 98 could induce the number of revertant colonies to increase nine to ton point two tiscc
(40mg/ylste') more than spontaneous ones (in those samples' probably eontainin~ certain frnaer .lift r.utegena)
;Eucommia Ulaoidss Oliv .in the presence or in the absence of 59 aix with strain TA 100 could
induce the number of revertant colonies to increase three to four timee (40ag/plati) morro than sppntaneua
ones (in these samples' probably containing mutagenie factor indueir,g base chantoa in DNA)a ihe
increasement of the number of revertant colonies inducing by these 3 hinds of erude drugs van eort'olated
to incoparation into four dosea
.Yith CA and PCEKN asaays in mice,the postive results voro riven to
13 water extracts of the crude drugs (13/102;12 .7¢),suoh as,Astragalus 1(embranaceus BE,Euconnia
tRaoides Oliv.,Sophora Japonica L.,Datura Metal L .,Artemisia Capillaris Thunb.,Rehmennia Olutinosa
(Oaertn .)Liboach,Carthsaue Tinctoriu L .,Forsythia Suspensa (Thunb .) Yahl,Paeonia Suffruticosa Andr .,
Platycodon Orandiflorum (Jacq .)A .D.C .,Cinnanomum Cassia Presl,Kotopterygiua Incisum Ting .and Sophora
Flavescens Ait .The CA and PCEMN induced by these drugs rere positive correlation to injecting medicines
into intraperitoneal cavity in nice .
The results have shown that the Aaes assay and the miee test (CA and PCE?4f) were positive results
(23%;3/13) .The false negative rate of Ames aasqy was higher than the CA and PCEMK if the aberration of
sucaryotio cells was taken .as assay eriteria .
A QUANTITATIVE ASSAY OF DNA POLYMERASE-a IN SITU AT SINGLE CELLS USING FLUORESCENCE
PSEUDO-COLOR IMAGE AND ACAS 470 .
P .K . Liu, B . Goudreau, and G .S . Hsu, Case Western Reserve University, Cleveland, OH
(USA), and Chia-Cheng Chang, Michigan State University, E . Lansing, MI . (USA)
Aphidicolin is a speoifio inhibitor of DNA polymerase-o and 8 in eukaryotio
oells . Because of the specificity of this inhibitor, it is potentially a useful
probe for the detailed studies of the function of these polymerases . A DNA
polys,erase-o mutant isolated on the basis of resistance to aphidioolin has been
described (Proo . Natl . Aoad . Soi .,USA 80 :797-801, 1983) . We and others have
isolated 4 variants which exhibit hypersensitivities to aphidicolin (Aphho) from
Chinese hamster V79/743X fibroblasts (In : DNA Replication and Mutagenesis, ASM . Pp .
163-172, 1988) . These variants are designated aphhs-1, aphhs-2, aphhs-3 and aphna-
4 . We reported here results of studies involving i®unoohemieal characterization .
The Aphhs phenotype in all mutants was stable for at least 30 days in the absence
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