Vicia faba chromosomal aberration assay

The international program on plant bioassays and the report of the follow-up study after the hands-on workshop in China

Among the seven plant bioassays reviewed by the US Environmental Protection Agency (EPA) Gene-Tox program in 1980, the Allium/Vicia root tip chromosome aberration assay and the Tradescantia stamen hair mutation and micronucleus assays were adopted by the International Program on Plant Bioassays (IPPB) for monitoring or testing environmental pollutants. These assays are highly sensitive and capable of detecting mutagens, clastogens and carcinogens from the environment. They are effective in situ monitors. These bioassays were validated and their protocols were standardized through a program under the International Program on Chemical Safety (IPPB), the precursor of the IPPB program which currently is in operation under the auspices of the United Nations Environment Program (UNEP). Six different categories of environmental studies, ranging from wastewater, surface or ground water, soil samples, ambient air, pesticides, and radiation, were carried out and are reported in this special issue. The mission of the IPPB/UNEP is to use these bioassays to monitor or test environmental mutagens and clastogens in the air, water, and soil to safeguard the quality of these essential elements in life and to use these simple and clear indicators of pollution damage as the tool for environmental education for the general public. The published reports of the monitoring and testing results will establish the database for environmental conditions in a number of locations around the world. An international monitoring network for the detection of genotoxicity of environmental pollutants is being established under the auspices of UNEP to protect the global environment.

Assessment of the genotoxicity of contaminated soil with the Allium/Vicia-micronucleus and the Tradescantia-micronucleus assays

The present study concerns the genotoxicity of contaminated soil near Metz, France. Three plant bioassays, the Vicia faba (broad bean), the Allium cepa (white onion) and the Tradescantia (spiderwort) micronuclei tests were used to evaluate for genotoxicity. Two soil samples were tested: soil sample A (from an industrial waste site) and soil sample B (from a cokeworks waste site). Maleic hydrazide was used as the positive control. Aqueous extracts of the soil samples were used to treat the roots of Vicia and Allium, and plant cuttings of Tradescantia according to the standard protocol for these plant assays established by the International Program on Chemical Safety and the World Health Organization. The results of these tests showed differential sensitivity in the three different bioassays. Soil sample A was more toxic than soil sample B.

Genotoxicity of water samples from Dianchi lake detected by the Vicia faba micronucleus test

Dianchi Lake covers about a 300 km2 area. Kunming city on the edge of the lake is surrounded by industrial establishments. Farm land surrounds the remaining areas of the lake. The lake water is polluted by the Kunming city municipal sewage from 3 million inhabitants, the industrial effluent and farm runoff. Water samples were collected from 12 sites along the shore of the lake during the dry (May) and rainy (August) seasons for genotoxicity testing with the Vicia micronucleus assay during the year 1995. Genotoxicity in terms of micronuclei (MCN) frequencies in the root tip cells of Vicia showed a consistent elevated frequency of MCN over the control sample at the 0.05-0.01 levels of significance in both seasons. The MCN frequencies of sites A (Daguanhe), B (Gaoqiao) and C (Xiyuan) were 3.5-4 times as high as the control values (5.25/1000 cells) in the dry season. In the rainy season, the MCN frequencies of water samples from most of the 12 sites were relatively lower than those of the dry season except sites J (Haikou), and K (Kunyang). The average MCN frequency of the dry season samples was 14.97 per 1000 cells and that of the rainy season samples was 12.24 per 1000 cells while the average control value was around 5.00/1000 cells.

Clastogenicity of chromium contaminated soil samples evaluated by Vicia root-micronucleus assay

Chromium compounds have been known to be highly toxic in biological systems and to some individuals act as strong allergens. A chromium processing plant in Tianjin city has been abandoned for many years and the chromium residue has been dispersed into the nearby soil. This study was designed to detect the genotoxicity of contaminated soil samples collected at various distances of 100 to 1000 m from the source using the Vicia faba root micronucleus test. Water solutions extracted from the soil samples were used to treat the roots of the Vicia beans. Micronuclei frequencies observed from the root meristems were used to determine the degree of genotoxicity. Micronuclei frequencies of the contaminated soil samples show linear dose responses to chromium contents in the soil, which were inversely proportional to the distance from the source.

Higher plant assays for the detection of chromosomal aberrations and gene mutations-a brief historical background on their use for screening and monitoring environmental chemicals

Higher plants are recognized as excellent indicators of cytogenetic and mutagenic effects of environmental chemicals and are applicable for the detection of environmental mutagens both indoor and outdoor. They are highly reliable bioassays with a high sensitivity for monitoring and testing for genotoxins. A brief review of major steps in the development of higher plant genotoxic assays is given.

Allium cepa anaphase-telophase root tip chromosome aberration assay on N-methyl-N-nitrosourea, maleic hydrazide, sodium azide, and ethyl methanesulfonate

The Allium anaphase-telophase assay was used to show genotoxicity of N-methyl-N-nitrosourea (MNU), maleic hydrazide (MH), sodium azide (NaN3) and ethyl methanesulfonate (EMS). All agents induced chromosome aberrations at statistically significant levels. The rank of the lowest doses with positive effect was as follows: NaN3 0.3 mg/l < MH 1 mg/l < MNU 41 mg/l < EMS 100 mg/l. The results were compared with results from other plant assays (Arabidopsis, Vicia, Tradescantia) and for MH and MNU the values were found to be within the same range, whereas the results in the Allium test for NaN3 and EMS were in a lower range than that found for the other plant assays. EMS and MMS (methyl methanesulfonate), two chemicals used as positive controls in mutagenicity testing, were compared in the Allium test, and MMS was found to be about ten times more potent in inducing chromosome aberrations than EMS. Recording of micronuclei in interphase cells showed that this endpoint does not give more information of clastogenicity than recording of chromosome aberrations in anaphase-telophase cells.

Sodium azide induces mitotic recombination in Drosophila melanogaster larvae

Sodium azide (NaN3), a potent mutagen for bacteria and barley, was tested for somatic mutation and mitotic recombination induction in wing imaginal disc cells of Drosophila melanogaster. Comparisons were made among inversion-free flr3/mwh, inversion-heterozygous TM3, Ser/mwh, and inversion-free, high bioactivation OR(R), flr3/mwh flies. Third instar larvae were exposed chronically for 48 h to sodium azide at 0.5, 0.63, 0.75, 0.88 and 1.0 mM. The frequencies of spots per wing obtained in the three kinds of progeny scored were compared. In inversion-free flies, sodium azide induced large single and total spots at all concentrations tested, and small single and twin spots at 0.75 mM and higher concentrations. In contrast, it failed to increase the frequency of small and large single spots in inversion-heterozygous flies. In high bioactivation flies (which are inversion-free), sodium azide increased the frequency of large single spots at 0.63, 0.88 and 1.0 mM and the frequency of total spots at 0.63 mM. From the absence of genotoxic activity observed in inversion-heterozygous flies it is concluded that sodium azide induces exclusively mitotic recombination in wing somatic cells of Drosophila melanogaster larvae after chronic exposure. This recombinogenic activity is reduced in the presence of high bioactivation capacity.

The comparative genotoxicological study of new local anesthetics, 3-(2-alkoxyphenylcarbamoyloxy)quinuclidium chlorides, on Salmonella typhimurium, Saccharromyces cerevisiae, Vicia faba, Hordeum vulgare and Drosophila melanogaster

Potential gentoxicity of five new local anesthetics, derivatives of phenylcarbamic acid differing in the length of the alkyl chain of the alkoxy substituent, was studied on five test systems. There was a direct relationship with increased toxic effect in bacteria and yeast as a function of the elongation of the alkyl chain of the alkoxy substituents of the phenylcarbamic acid esters. On the other hand, no structure-toxicity relationship was found after application of 3-(2-alkoxyphenylcarbamoyloxy)-quinuclidium chlorides on plants and Drosophila. All anesthetics were nonmutagenic to Salmonella typhimurium strains TA97, TA98, TA100, and TA102 in the absence and in the presence of S9 mix. Pentyloxy and heptyloxy derivatives increased rates of genetic changes in Saccharomyces cerevisiae, mainly revertants at the isoleucine locus. Pentyloxy and hexyloxy derivatives increased the frequency of chromosome aberrations in Vicia faba root-tip meristems. No chlorophyll mutations were detected after treatment of Hordeum vulgare with pentyloxy, hexyloxy and heptyloxy derivatives. No sex-linked recessive lethals were scored in Drosphila melanogaster males. The rates of aneuploids induced in their germ cells were significantly increased after treatment with butoxy and octyloxy derivatives. However, the local toxic and genotoxic effects of test anesthetics on the microorganisms of the anesthetized tissues may be of some importance. In particular, the genotoxic effect exhibited in fungi by the heptyloxy derivative, a potent local anesthetic, was remarkable.

Vicia faba as a bioindicator of oil pollution

In 1990, the Gulf War caused an unprecedented environmental catastrophe. More than 700 oil wells were set on fire, emitting thousands of tons of oxides of nitrogen, sulfur, soot and oil mist at high temperatures. The blazing oil wells and lakes were the major cause of environmental pollution, damaging flora and fauna throughout Kuwait and the surrounding region. We set up this study in order to investigate whether Vicia faba could be used as a bioindicator of oil pollution. Growth parameters of Vicia faba, such as levels of photosynthetic pigments, proteins, free amino acids, phenols, sugars, biomass, moisture and fatty acids, were studied. Levels of total reducible sugars, phenols, proteins, free amino acids and proline were found to be higher in plants grown in hydrocarbon-polluted soil, compared to those grown in control soil. However, biomass, moisture, pheophytin, the 435/415 nm ratio for chlorophylls and the chlorophyll a/carotenoid ratio, were higher in the plants grown in control soil than those grown in polluted soil. Our results indicate that Vicia faba can be used as a bioindicator of pollution and a ratio of the fatty acid C(20:1)/C(18:1) is an important index of environmental oil pollution.