Environmental and Molecular Mutagenesis - Legacy Tobacco ...

in the presenoe of specific inhibitors of cytochrome P-450 . In these eorditions, vanadyl
genotwcicity renaiz>aa unaffected, while the presenoe of inhibitors determined an increase
in mitotic yene conversion an3 point reverse mutation irr3uaed by vanadate . Therefore,
tcrmooxygenase system cytochrome P-450 depertflent is probably involved in the vanaditm tretabolism
reducirg vanadate, but not oxidating vanadyl ..
183
DIFFEREhTIAL MUTAGENIC RESPOOiSE CF A SYtVCi-ic .~l'IC pYR::THRCID, DELTAMETHR4tv,
IN SUB-MAN:MALIAN AND MAMNALIAN TEST SYSTfVIS . G . Gandhi, J .b . Chowt9'tury,
P .K .Sareen and I .S .Grover, Scliool of Life Scit•aces,GNDU,Amritsar,India .
Deltamethrin is one of the most commonly used pesticides in North
India . Mence,•-tts genoto•ricity was studied for germ-cell mutagenesis in
Dromvhil~ and for clastogenicity in the mouse bone-marrow !• :0 test . LM
(solvent) exhibited mutation rates comparable to the norn :al control v luas
while EMS elicited a positive response in all the test assays . il.iA
were exposed to media containing varying concentrations of the insecticide
(0 .2, 0 .4, 0 .6, 0 .8 and 1 .0 ppn) for the induction of dominant
lethals . A steady but non-significant increase in lethality fr(m 32 .58:4
at 0 .20 ppm to 5O .05X at 1 .00 ppm was ob served . Also none of the concentrations
i nduced significa nt SLRLs (2 .45%) even at the highest eoncent ration
tested (0 .80 pgo) . Cytogenetic damage in mice was screened for three
ip administered doses (32 .50, 162 .50 and 300 .00 tng/kg b .w), selected from
estimated LD50 (325 mg/),-.g b .w) . significant genetic damage (1 .26 and
'1 .35% micronucleated PCES) was observed at the two higher doses . The PCE/
tCZ
ratio demonstrated a significant ir.crease in the percentage of pCES,
at lower doses sig nifying a stimulatcry eff ect of deltamethrin . Though,
deltameth rin showed no germ-cell mutagenesis in ro• :nnhd .11, yet it acted
as a strong clastogerl/sPindle ir4fibitor in the mouse . Its differential
response has rather made it desirable to investigate its ; genotoxicity in
oth er systems too .
184
RFGULA'TION OF NUM,AN DNA GLYCOSYLASFS 'rdAT INT'fTA'TF gAgfy FXCISION RFPAIR OF OXii)ATTVE
PYHf,lIjL2F MODIFICA'TTONS . Tapan Cang-il y and aahum J . Duker, Temple University
School of Nndicine, Philadelphia, PA (OSA)
DNA oxid,rrive damap,ea are among the most frequPOt~ tyoes encountered in the
lifetime of a cell . TheaPe can result from ionizing or gamma radiation and froaa
activated oxygen species Renerated from metabolic procesees . Fxciaion of oxidized
bases from DNA of hurnan cella ia initiated by DNA qlycosylaees . The oxidized
t7yminrc moiety 5-hydroxyrethyluracil is removed frorn DNA by 5-hydroxyerethyluracil-
DNA e,lycosylase . A redoxyendonuclease, active against a wide variety of substrates,
has ;lycosylic activity aF,ai .ist many modified DNA pyrimidiiea . We studied
re.gul .ation of these enzymes in proliferating human cella . Both glycosylases were
assayed by measurement of direct telease of modified free bases from their DNA
substrates . Serum-atimulated JI-38 Sunan cells were the sources of enzyme
a .tiviries assayed in crude extracts as a function of cell division . 5hydroxyaret.hyluracil-DNA
qlycosylase activity did not vary significantly during the
cell cycle . ny contrast, the glycosylic activity of the redoxyendonucleaee
increased four-fold as a function of cell growth . Maximum stimulation was obtained
during peak DNA synthesis . Tnis enzyme activity increased once again aa thn cella
entered a second growth cycle . This ia similar to the stimulation observed for
uracil-UNA glycosylase in a aynchronous cell population . Theae results indicate
that the glycosylasea that initiate base excision repair of oxidised DNA are not
coor3inately induced during the cell cycle .
185
LATE EFFECTS OF FEMALE SEX HORMONES
han Fengeing, )laog Hsnyfug, and Yu Yannao, Dept . of Blological Effect of
Radislion, Laboratory of tnduslrial Nygiens, Ministry of Public Health . I
Xinkang Street, Desheng.enr,l, Beijing, (China)
Inj . Hydroxyprugesterone Co . (containing hydroxyprogesterons capruste (P)
250 •g and estradiol valerate (E) S sfgi .l of vehit•ls, .EP) was Isjecled
intrseuscularly into fe .ale Vister rats and different strains of rtee of both
sexes with doses of 5 to 100 ti .es that used Is huans ones or twice a month for
10 to 24 ti .es . In so .e experl .ents EP was co .bined with •hole-body 3 Gy ga. .a
radiation once or twice . The purpose of this work was to detsr .ine whether F•P
would possess carcleogenleity or not and whether synergistic cercinogeeicily
would exist when EP had been ad .lnistered In coebination of ga . .a radletion .
Results show that EP has ubvious carcloogenicity/tu .our lncidence was siegnifi-
http://legacy.library.ucsf.edu/tid/clb93d00/pdf
1989 EMS Abstracts 65
Notes