INDUCTION OF MICRONUCLEI IN CHALCALBURNUS TARICHI (PALLAS, 1811) EXPOSED TO SUB-LETHAL CONCENTRATIONS OF METHYL PARATHION

摘要

The micronucleus assay (MNT) is a mutagenicity test system for determining pollution and chemicals causing changes in DNA fragments, such as micronuclei (MN) in the cytoplasm of interphase cells. Damage caused in the DNA by genotoxic pollutants is the first consequence occurring in the aquatic organisms. The MNT in fish erythro-cytes has increasingly been used to detect the genotoxic effects of environmental mutagens, and its frequency is considered to reflect the genotoxic damage to cells, mainly the chromosomes. In this study, the genotoxic effects of methyl para-thion (MP), one of the most commonly used pesticides in Lake Van Basin, on Chalcalburnus tarichi (Pallas, 1811), which is an economically important endemic species in the basin, were investigated. The experiment was carried out over a period of 30 days using an in vivo method on samples of peripheral erythrocytes of C. tarichi taken at sampling times. The fish were exposed to increasing concentrations of MP (1.47, 2.1, 3.0, 4.28 and 6.11 mg L~(-1)) under semi-static conditions in the laboratory. The increase in micronucleus frequency was significant as well as altered cells' frequencies. Thus, it was attempted to determine whether MP affected the erythrocytes of C. tarichi at the level of DNA by means of the MN test. According to the results of the present study, the highest level of frequency of MN was found at 6.11 mg L~(-1). In conclusion, this study indicates that the MN test gives sensitive results in determining the genotoxicity of pesticides, and thus, it might be used as a standard method for regularly monitoring the genotoxic effects of pesticides.