Environmental and Molecular Mutagenesis - Legacy Tobacco ...

26 1989 EMS Abstracts 68
Notes MITOD8PRL88IVE El7ECT8 OF PJ1R11QUAT Ill 71LLIU![ CEPA .
R . A . Boroffice . Department of Biological and Chemical Sciences, Lagos
State University, Ojo .
Cells of Allium ceoa root meristems were exposed to different
concentrations of paraquat (5, 10, 25, and 50mg/i) . There was a doserelated
reduction in mitotic index which was directly associated with
length of exposure . There was a relative reduction in mitotic index in
treatments allowed recovery periods .
http://legacy.library.ucsf.edu/tid/clb93d00/pdf
SCREFNING FOR BASE MUPATICNS IN THE HPRT AND PAH LflCUS USING THE POLYMFRASE CHAIN
REACfION (PCR) IN COMIDINATICN WITH DENATURING GRADIENT GEL ELDCIROPHORESIS (DGGE) .
A .-L . BOrresen,l E . Hbvig,l B . S . Smrensen,l H . Vrieling2 and A . Brogger .l
Inst, Cancer Research, The Norwegian Radium Hospital, Oslo, Norway
2) Dept . of Rai . Gen . and Chen . Mutagenesis, Univ . of Leiden, The Netherlands
We have u9ej the polymerase chain reaction (pCR) and denaturing gradient gel
electrophoresis (DGGE) to screen for base mutations in the PAH (phenylalamin
hydroxylase) locus and the HPRT (Hypottanthine guanine phospho-ribosyl transferase)
locus . For the PAH locus a 245 base pair fragnent containing exon 12 with flanking
intronic sequences was amplifie8 . In this DNA sequence a single base substitution has
beert found in 30% of the Norwegian PKU patients . This mutation gives a different
melting profile of the 245 bp fragments resulting in a different migration on DGGE .
The hu3e amplificaton of the genamic DNA fragments by PCR allows detection by direct
EtBr staining of the gel making a rapid and easy method to screen for this PKU
mutation in newborns .
For the HPRT locus exon 3 was amplified fran a collection of 13 W and ENU induced
mouse and hamster mutants, all shown to contain a mutation in the 3rd exon after
sequencing . 8 of these mutants could be detected on DGGE after PCR . A collection of
12 unknown HPRT mutants induced by porphyrins plus W were screened for mutations in
exon 3 using these methods . No deletions of exon 3 were fourd, and no base mutations
in the lower melting domain of exon 3 have been found so far . The use of PCR in
combination with DG3E is a rapid and applicable method for screening both known and
unknown mutations, inherited or induced in the lower melting domain of a given
DNA-sequence .
MEJ-41 AND OTHER REPAIR GENES OF DROSOPHILA . James B . Boyd and Satnam S . Bangs. Department of
Genetics, University of California . Davis CA 95616
Genetic studies of repair deficient mutants in Drosophila have revealed the existence of extensive overlap in the
functions that participate in DNA repair, recombination and synthesis . Mutants in several genes are known, for
example, to be deficient in both DNA repair and meiotk recombinadon . A forward genetie approach is currently
being employed in this laboratory to clone the repeir related genea nui-9 and ntef-I1 . Mutants at these loci are
highly pleiotropic in that they influettce both meiotic reeombbttdon and a broad tpectrttm of DNA repair responses .
Yamamoto and Mason have succeeded in mutageniztng both ioci In crosaes that mobilize transposable P elements .
A combination of in siru hybridization and tevusiott atulysis has established that the recovered mutants were indeed
induced by transposon insertions. Chromosome walking has been employed to recover all of the etei-41 gene .
Transcriptionally active sequences adjacent to the P insertioa sites have been used to isolate a 2 .2 kb embryonic
cDNA clone whose homology extends over 14 kb of the ohrumosomal walk . That cDNA represents a mei-01
transcript because It exhibits homology to genomio sequences on both sides of the P insertion sites . Norihern blots
prepared with poly(A)+ RNA from both embryos and adult females have Identified a single 2.2 kb transcript with
homology to the cDNA clone .
EVALUATION OF GENOTOXICFIY OF N-NfTROSODIBENZYlA1vIINE IN CHINESE
HAMSTER V79 CELIS AND IN SALMONEIdA . B.G. Boyes. C.O . Rogers, N .P. Sen
and T.I . Matula, Toxicology Research and Food Research Divisions . Food Directorate
and
. Health and Welfare Canada .
Ottawa~OntariolCANADAI• sion, Drugs Directorate
Health concerns have arisen due to the formation of N-nitrasodibenzylamine
(NDBzA) in pork processed in a new type of rubber netting . While NDBzA was
reported to be non-carcinogenic in an early in vivo study (Druckrey ct 2 .
Krebsforsch .69:103, 1967), the potent carclnogenicity of related nitrasamines eg . Nnitroso-n-dlbutylamine
and N-nitrosodiethylamtne) prompted evahxation this
compound for genotoxicity in y= in both Chinese hamster V79 cells and In
Salmonella . Concentrations up to 25 Ng/ml were tested in V79 cells with and
without activation by rat or hamster hepatocytes . Under any of these conditions
there was no significant elevation of sister-chromatid exchange levels . Mutation to
6-thioguanine resistance was also negative, except for a weakpoaitive in only one of
three replicate experiments, at 25 pg/ml, and only In the absence of hepatocytes
which was considered not biologically siArti9cant . At concentrations up to 1000
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