S. Takehisa

A comparison of Vicia-faba-root S10 and rat-liver S9 activation of ethanol, maleic hydrazide and cyclophosphamide as measured by sister-chromatid exchange induction in Chinese hamster ovary cells.

A comparison of Vicia-faba-root S10 with rat-liver S9 was made in their capacity to bring about, in vitro, the metabolic activation of ethanol, maleic hydrazide (MH) and cyclophosphamide (CP) that can lead to the induction of sister-chromatid exchanges (SCEs) in CHO cells. When NADP was a cofactor in the S9 mix, ethanol, MH and CP all induced an increase of SCEs with rat-liver S9. With Vicia-root S10, however, ethanol induction of SCEs was very weak and no effect at all was observed with MH and CP. When NAD was a cofactor in the S9 mix, Vicia-root S10 activated ethanol and produced an increase in SCEs.

On Adaptive Responses of Plant Meristem Cells in Vivo - Protection Against Induction of Chromatid Aberrations

When cells are confronted with environmental stress they may react by adaptive responses which eventually enhance their resistance to the damaging impact and provide additional capacities to survive the crisis.

Promutagen activation by Vicia faba: an assay based on the induction of sister-chromatid exchanges in Chinese hamster ovary cells.

Plant activation of promutagens was studied using Vicia faba S10 (in vitro activation) and the extracts prepared from promutagen-treated roots of Vicia faba (in vivo activation). The induction of sister-chromatid exchanges in Chinese hamster ovary cells was used as an endpoint to evaluate the cytogenetic effects of promutagens activated by Vicia faba. Cyclophosphamide and ethyl alcohol were activated both by Vicia S10 and by the Vicia extracts, and their activation resulted in an increase in SCEs. Benzo[a]pyrene, 2-aminofluorene, and maleic hydrazide were not activated. Aniline was activated, but without effect on the induction of SCEs. The activation capacity in vitro and in vivo of Vicia faba was not very pronounced, except for the activation of ethyl alcohol, when compared with that of rat-liver S9, and showed differences in activation for the 6 chemical agents tested.

SCE induction in human lymphocytes by combined treatment with aniline and norharman

In human lymphocytes, aniline was unable to induce an increase of SCEs in vitro with or without metabolic activation by S9 mix. p-Aminophenol, one of the C-hydroxylation metabolites of aniline in the body, however, increased the SCE frequencies of lymphocytes at a concentration of 10-4 M. The addition of norharman to aniline plus S9 mix increased the SCE frequencies. The increase, however, was due to the SCE-inducing activity of norharman. These data show that the addition of norharman, which enhances the sensitivity of the Salmonella/microsome test, does not produce an enhancement of the sensitivity of the SCE test.

Ammonium chloride and zinc sulfate pretreatments reduce the yield of chromatid aberrations induced by TEM and maleic hydrazide in Vicia faba

Abstract Pretreatment of Vicia faba root-tip meristems with ammonium chloride and zinc sulfate prior to challenge treatment with maleic hydrazide (MH) and TEM, respectively, resulted in significant reductions of the yield of metaphases with chromatid aberrations. Ammonium sulfate pretreatment was without effect on aberration yield. Similar to heat-shocks and a variety of other agents, which induce the heat-shock response, the protective effects of ammonium chloride and zinc sulfate are presumed to be due to stress-responses of the root meristem cells which eventually result in inducible anticlastogenic functions.

Induction of SCEs in CHO cells by extracts from Vicia faba roots exposed to ethanol

Though extensive studies have been done on potential genetic effects of ethanol, results ,~btained so far are conflicting with respect to the effectiveness of ethanol in inducing chromosomal aberrations and sister-chromatid exchanges (SCEs) in mammalian cells. (For review see Obe and Ristow, 1979.) Alcoholics showed significant increases of chromosomal aberrations (Obe and Herha, 1975) and SCEs (Butler et al., 1981). Application of ethanol in vivo did not induce chromosomal aberrations in bone-marrow cells or lymphocytes of rats (Tates et al., 1980) or in lymphocytes of Chinese hamster (Korte et al., 1981). After treatment with ethanol in vivo an increase in SCEs was found in fetal liver cells of mice (Alvarez et al., 1980b), embryo cells of pregnant mice (Czajka et ah, 1980), lymphocytes of rats (Tates et al., 1980), and bone-marrow cells of mice (Obe et al., 1979), but no increase was observed in bone-marrow cells of rats (Tates et al., 1980) or those of Chinese hamster (Korte et al., 1980). Treatment with ethanol in vitro did not increase the frequencies of SCEs in CHO cells (Obe and Ristow, 1977) or chromosomal aberrations in human lymphocytes (Obe and Ristow, 1979), but increased SCEs in human lymphocytes (Alvarez et al., 1980a). From the observation that acetaldehyde induces SCEs in CHO cells (Obe and Ristow, 1977) and in human lymphocytes (Ristow and Obe, 1978), Obe and Ristow (1979) concluded that ethanol is mutagenic via its first metabolite, acetaldehyde. This implies that ethanol itself is not a clastogenic and SCE-inducing agent and that the mode of metabolism of ethanol is important with respect to the chromosomedamaging activity of ethanol. To verify this hypothesis, we looked for effects of an extract from the roots of Viciafaba treated with ethanol on the frequency of SCEs in CHO cells. In Vicia faba, ethanol induced chromatid aberrations (Michaelis et al., 1959; Rieger and Michaelis, 1960a) and SCEs (Schubert et al., 1979). Acetaldehyde gave rise to chromatid aberrations in Vicia faba (Rieger and Michaelis, 1960b). It is

‘Clastogenic cross-adaptation’ is dependent on the clastogens used for induction of chromatid aberrations in Vicia faba root-tip meristems

Abstract “Clastogenic cross-adaptation” is the triggering, by “conditioning⌉ pretreatment with a low dose of one clastogen, of protective effects against the induction of chromatid aberrations by another (“challenge” treatment) clastogen. All alkylating agents tested in this respect (TEM, NMU, EMS) were found to be able to substitute for each other in arousing such protective effects in Vicia faba root-tip cells. Combinations of MH (pretreatment) with TEM or NMU (‘challenge’ treatment), and vice versa, did not result in clastogenic cross-adaptation. The data are discussed as to the causes (inducible functions) which may give rise to clastogenic adaptation.

Clastogenic adaptation triggered by S-phase-independent clastogens in Vicia faba

Abstract Conditioning pretreatment of Vicia faba root-tip meristem cells with small doses of X-rays (0.06 Gy) or bleomycin, S-phase-independent clastogens, significantly reduced the yield of metaphases with chromatid aberrations induced by challenge doses of the same clastogens, administered 2 h after conditioning, i.e., resulted in clastogenic adaptation. Both clastogens were found to be able to substitute for each other in arousing protective effects (clastogenic cross-adaptation).

Involvement of phytochelatins in NiCl2-triggered protection against induction of chromatid aberrations by TEM and MH in Vicia faba root tip meristems?

Conditioning treatment of Vicia faba root tip meristem cells with NiCl2 prior to challenge treatment with triethylenemelamine (TEM) or maleic hydrazide (MH) triggered protective functions against both these clastogens, i.e., resulted in a significantly reduced yield of metaphases with chromatid aberrations. Protection was prevented by pretreatment with buthionine sulfoximine (BSI), an inhibitor of the synthesis of plant phytochelatins (PCs), indicating that the NiCl2-triggered PC synthesis may be involved in the protective functions induced by NiCl2 conditioning treatment. BSI (instead of NiCl2) conditioning treatment triggered protection against MH but not against TEM.

Low temperature between conditioning and challenge treatment prevents the ‘adaptive response’ of Vicia faba root tip meristem cells

When the temperature during intertreatment time (2 h) between conditioning and challenge treatment of Vicia faba root tip meristems with either triethylenemelamine or maleic hydrazide was reduced from 24 degrees C to 12 degrees C no adaptive response occurred any more. The yield of metaphases with chromatid aberrations under these circumstances was similar to that observed after challenge treatment alone, i.e., no reduction occurred. This indicates that the metabolic state of the cells is of critical importance for the presence or absence of adaptive responses.