Monitoring DNA Damage in Gills of Freshwater Mussels (Anodonta anatina) Exposed to Heavy Metals
Monitoring DNA Damage in Gills of Freshwater Mussels (Anodonta anatina) Exposed to Heavy Metals
Muhammad Sohail1,*, Muhammad Naeem Khan1, Naureen Aziz Qureshi2 and Abdul Shakoor Chaudhry3
ABSTRACT
Study was carried out to investigate the genotoxic effect of different levels of heavy metals on gill cells of freshwater mussels (Anodonta anatina), a sentinel species in aquatic environment. Freshwater mussels were exposed to none (0µg L-1), low (120 µg L-1), medium (240 µg L-1) and high (360 µg L-1) levels of lead (Pb), chromium (Cr) and copper (Cu) alone and in combinations (Pb + Cr + Cu) for 15 days under laboratory conditions. Gill cells of mussels were used to determine the DNA damage by comet assay. The tail DNA (%), comet tail length and olive tail moment (OTM) were the parameters selected to detect DNA damage. Low doses (120 µg L-1) of each metal induced significantly higher levels of DNA strands breaks as compared to medium dose (240 µg L-1) and very low levels of DNA damaged was observed at high dose (360 µg L-1). Cu and Pb showed significantly higher value of % of tail DNA (56.74±1.81, 47.36±1.23) and comet tail length (41.30±0.758, 49.15±1.90), respectively, as compared to Cr and combined metal exposure (Pb + Cu + Cr). The lowest levels of DNA damage for all the parameters were observed in combined metal treatment. Genotoxic effect of metals on freshwater mussels is very important to assess the aquatic health and could be suggested as biomarker. It is concluded that the Cu and Pb induced more DNA damage as compared to Cr and combined metal exposure (Pb + Cu + Cr). Moreover, our results showed that the low dose treatment of metals have more genotoxic effect as compared to the medium and high doses.
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