engleski

Environmental genotoxicity assessment using freshwater crayfish Astacus leptodactylus

Genotoxic effects are often one of the earliest signs of pollution-related environmental disturbance. In this study comet assay was applied to assess DNA damage in haemocytes of freshwater narrow-clawed crayfish Astacus leptodactylus exposed to environmental pollution in situ. Animals collected at the reference site (the Mrežnica River) were exposed in cages for one week at three sites of different pollution intensity along the Sava River (Zagreb, Sisak, Krapje). A separate crayfish group caged at the reference site was used as a control. Significant increase in DNA damage measured by the comet assay was observed at all three polluted sites comparing to the reference site. On the polluted site Zagreb, native individuals from the mildly polluted site (Krapje) were cage exposed along with the ones from the reference site. Induced DNA damage was lower in crayfish originating from the Krapje site, indicating higher activity of adaptive mechanisms in animals from pollution-stressed environment. To determine influence of various abiotic factors on crayfish DNA integrity, animals were exposed in laboratory to air, different water temperatures, or were deprived of food. Increased temperature (25°C, 30°C) induced significant increase in DNA damage, but returned to control levels within one week of recovery. Air exposure caused inducement of DNA damage after 6 hours but decreased to control levels within next 18 hours. Two weeks of food deprivation did not cause any detectable genotoxic effects. In this study freshwater crayfish were used for the first time as sentinel organisms in environmental genotoxicity studies. Our results indicate that crayfish are easily adapted to abiotic environmental changes, what is considered preferential for sentinel species. Moreover, we have proved applicability of caging exposure of crayfish A. leptodactylus in freshwater biomonitoring and confirmed usefulness of comet assay as suitable tool for detection of pollution-related genotoxicity.

genotoxicity assessment; comet assay; freshwater crayfish

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