Environmental and Molecular Mutagenesis - Legacy Tobacco ...

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of chilli, were not mutagenic in Salmonella typhimurium TA98 and TA100 with and
without S9 mix . The mutagenic component(s) in shallot and greater galangal will be
further isolated and chaxa~cterized .
This study was supported by the China Medical Board Grant, Fac .of Medicine,
Chiang Mai University .
nYVCSncw77omTOwARDS THE Srwra)Aantzw11MorZNB ausaYAtlAxs,TOTTti4i wmr uu+PIDt@rraaC6stnAws
W . VoDcner• . E .W . M3ller• and H .G . Miltenburger, Institute for Zoology, Technical University, 6100 Darmstadt, F .R.G .
•Preunt address: Cytotest Cell Research (CCR) GmbH, 6101 RoBdorf, F .R.G.
The mammalian spot test (MST), developed by Russell and Major (Generfea I2161-175, 1957), is a procedure for the
detection of chemically induced mutations (especially gene mutations) and/or reeombinational processes (Fahrf$
Funkt .Brol.Med5:287-297, 1985) in somatic cells of the mouse. The method uses an exposure of embryonic eella ja utero
via treatment of pregnant females with mutagens . This can lead to an alteration of wild type aUe4 at different coat colour
genes in pigment precursor cells of the beterozygous Fl-embryos . Under the precondition of several subsequent
divisions of the genetically altered precursor cell the recessive phenotype can be expressed, constituting a spot of
changed colour on a black (nonagouti) background of the F~-~mouse fur
The aim of our investigations was to compare the suitability of different . crosaes . We expected that the use of a cross
DBA x NMRI, could minimize the efforts to reach satisfactory Fl-numbers. A possible disadvantage resulting from a
smaller set of genetic markers as compared to the uosses T x liT and T x C57BI could not be excluded. We performed
experiments to determine the spontaneous spot rates and to quantify potential sensttiviry differences between the crosses
T x C57BU61 and DBA x NMRI using the well known point mutagen ethylnitrosourea (ENU) . Neither the spontaneous
nor the ENU-induced spot frequencies did sub.taatially differ between the ctosses . However, a much lower number of
pregnant females was required to reach the recommended sample dzea per experimental group of 200 - 300 Fl-anintala
(Braun, Russel4 Schdteich ; Mutation Research D7:155 161, 1982) in the cross DBA x NMRI . In additional experiments we
exposed embryos carrying only one or two heterozygous markers in various combinations to an ENU-treatment . It was
proven by these tests that the value of detectable genetically relevant spots depended on the marker used . The sum of
spot rates at the loci brown, dilute and albino equalled the value from a comparable treatment of the hybrids of the cross
DBA x NMRI in which these markers are involved and was in the same range as known from the cross T x C57B1 .
In conclusion the cross DBA x NMR] can be mommended jor the routine and standardtzed pedormance ojthe MST.
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COMPARISON OF THE PLANT CELL ACTIVATION OF TWU PROMUTAGENS USINC3 ENZYME
INHIBITORS . E .D. Wagner, M .M. Verdier and MJ . Plewa . Institute for Environmental Studies, University
of Illinois, Urbana, IL 61801 USA .
We are studying the mechanisms involved in the plant activation of 2-aminofluorene (2AF) and mphenylenediamine
(m-PDA). Tbbacco cells (TX1) were the activating system and reversion in SaGnonelta
ryphimurium (TA98) was the genetic endpoint . Specific inhibitors were introduced into the coincubation
mixture of TX1 cells at mid-log phase, TA98 cells and a constant amount of 50 µM 2AF or 500 pM m-
PDA. The endpoints of mutation induction, plant cell viability, and bacteria viability were assayed .
Diethyldithiocarbamate, a metal chelator, inhibited the activation of both 2AF and m-PDA with no
concomitant decrease in cell viability . Likewise acetaminophen, a peroxddase inhibitor, also reduced the
activation of both 2AF and m-PDA . Metyrapone, an inhibitor of cytochrome P-450, had no effect on either
the activation of 2AF or m-PDA, but was toxic . (+)-Catechin enhanced the plant activation of 2AF at low
concentrations and inhibited activation at higher concentrations . (+)-Catechin reduced the activation of m-
PDA Low concentrations of 7,8-bcnzoflavone (a cytochrome P-448 inhibitor) reduced the number of plantactivated
2AF-induced TA98 revertants . 7,8-benzoflavone had no effect on m-PDA activation . Methimazole,
a high-affinity flavin-containing monooxygenase substrate did not influence 2AF activation but did inhibit
the activation of m-PDA . We conclude that cytochrome P-450 is not involved in 2AF or m-PDA activation.
A peroxidase pathway plays a role in the activation of both promutagens. In addition, a cytochrome R448type
N-hydroxylase is implicated in 2AF activation, whereas a flavin-containing monooxygenase pathway is
important in m-PDA activation. Research funded in part by USAF grant tM88-AF-P-0511 .
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IDENTIFICATION OF FOOD MUTAGENS . K. Wakabayashi, National Cancer Center Research
Institute, Tokyo (Japan)
Identification of mutagens in food is the first step in determining their
contribution to human cancer development . By using mutagenicity in Salmonella ss a
monitoring system, we have found and identified many mutagens and nitrosatable
mutagen precursors in foods .
Various kinds of heterocyclic aminea were identified as mutagens in cooked meat
and fish, and nine of the compounds were proven to be carcinogenic in rodents . IQ
was shown to be carcinogenic in monkeys . Carcinogenic Trp-P-I and Trp-P-2 were found
to be very potent inhibitors of monoamine oxidase . Some heterocyclic amines were
detected in human brain, blood and urine . Thus, heterocyclic'amines may be involved
http://legacy.library.ucsf.edu/tid/clb93d00/pdf
1989 EMS Abstracts 211
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