Micronucleus assays with fish have been shown to be useful in vivo techniques for genotoxicity testing, and show potential for in situ monitoring of water quality In this paper, we review the literature on the clastogenic effects of chemical and physical agents on fish cells, with emphasis on the induction of micronuclei in teleosts Included in the review is a description of the mechanisms for formation of micronuclei in cells, and a summary of the various techniques that have been used for micronucleus analysis in fish This review is directed to assisting laboratories in the development of fish genotoxicity assays for water quality monitoring

Fish micronuclei for assessing genotoxicity in water

This public health statement tells you about chromium and the effects of exposure to it.The Environmental Protection Agency (EPA) identifies the most serious hazardous waste sites in the nation. These sites are then placed on the National Priorities List (NPL) and are targeted for long-term federal clean-up activities. Chromium has been found in at least 1,127 of the 1,699 current or former NPL sites. Although the total number of NPL sites evaluated for this substance is not known, the possibility exists that the number of sites at which chromium is found may increase in the future as more sites are evaluated. This information is important because these sites may be sources of exposure and exposure to this substance may be harmful.When a substance is released either from a large area, such as an industrial plant, or from a container, such as a drum or bottle, it enters the environment. Such a release does not always lead to exposure. You can be exposed to a substance only when you come in contact with it. You may be exposed by breathing, eating, or drinking the substance, or by skin contact.If you are exposed to chromium, many factors will determine whether you will be harmed. These factors include the dose (how much), the duration (how long), the form (chromium VI as opposed to chromium III), and how you come in contact with it. You must also consider any other chemicals you are exposed to and your age, sex, diet, family traits, lifestyle, and state of health.

Toxicological Profile for Chromium

Cytotoxicity of metals is important because some metals are potential mutagens able to induce tumors in humans and experimental animals. Chromium can damage DNA in several ways, including DNA double strand breaks (DSBs) which generate chromosomal aberrations, micronucleus formation, sister chromatid exchange, formation of DNA adducts and alterations in DNA replication and transcription. In our study, water samples from three sites in the Corrego dos Bagres stream in the Franca municipality of the Brazilian state of Sao Paulo were subjected to the comet assay and micronucleus test using erythrocytes from the fish Oreochromis niloticus. Nuclear abnormalities of the erythrocytes included blebbed, notched and lobed nuclei, probably due to genotoxic chromium compounds. The greatest comet assay damage occurred with water from a chromium-containing tannery effluent discharge site, supporting the hypothesis that chromium residues can be genotoxic. The mutagenicity of the water samples was assessed using the onion root-tip cell assay, the most frequent chromosomal abnormalities observed being: c-metaphases, stick chromosome, chromosome breaks and losses, bridged anaphases, multipolar anaphases, and micronucleated and binucleated cells. Onion root-tip cell mutagenicity was highest for water samples containing the highest levels of chromium.

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Genotoxicity and mutagenicity of water contaminated with tannery effluents, as evaluated by the micronucleus test and comet assay using the fish Oreochromis niloticus and chromosome aberrations in onion root-tips

Aquatic pollutants produce multiple consequences at organism, population, community and ecosystem level, affecting organ function, reproductive status, population size, species survival and thus biodiversity Among these, carcinogenic and mutagenic compounds are the most dangerous as their effects may exert a damage beyond that of individual and may be active through several generations The application of genotoxicity biomarkers in sentinel organisms allows for the assessment of mutagenic hazards and/or for the identification of the sources and fate of the contaminants Micronucleus (MN) test as an index of accumulated genetic damage during the lifespan of the cells is one of the most suitable techniques to identify integrated response to the complex mixture of contaminants MN assay is today widely applied in a large number of wild and transplanted aquatic species The large majority of studies or programmes on the genotoxic effect of the polluted water environment have been carried out with the use of bivalves and fish Haemocytes and gill cells are the target tissues most frequently considered for the MN determination in bivalves The MN test was widely validated and was successfully applied in a large number of field studies using bivalves from the genera Mytilus MN in fish can be visualised in different cell types: erythrocytes and gill, kidney, hepatic and fin cells The use of peripheral erythrocytes is more widely used because it avoids the complex cell preparation and the killing of the animals The MN test in fish erythrocytes was validated in laboratory with different species after exposure to a large number of genotoxic agents The erythrocyte MN test in fish was also widely and frequently applied for genotoxicity assessment of freshwater and marine environment in situ using native or caged animals following different periods of exposure Large interspecies differences in sensitivity for MN induction were observed Further validation studies are needed in order to better characterise the different types of nuclear alterations and to clarify the role of biotic and abiotic factors in interspecies and inter-individual variability

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Micronucleus assay in aquatic animals

The micronucleus test in piscine erythrocytes.

An investigation of the cytogenetic effects of chromium (Cr(VI) and Cr(III)) in Prussian carp (Carassius auratus gibelio) was made. For detecting cytogenetic damage, micronuclei induction in fish erythrocyte cells was employed. Fish were investigated 100 m above and 400 m below the discharge of leather waste products into the river Ljubljanica, and by exposing fish to three doses of chromium (Cr(VI) and Cr(III)) in the laboratory. The exposure of fish to various concentration levels (sub-lethal) of chromium under laboratory and field conditions caused an increase in the frequency of micronuclei compared with the control groups.

K. Al‐Sabti

Papers

Chromium‐induced micronuclei in fish