Micronuclei Assay: A Suitable Tool for Evaluating the Heavy Metals Induced Genotoxicity in Fish, Labeo rohita

Increasing load of heavy metals from industrial, agricultural and commercial chemicals discharged into aquatic habitats could pose a serious threat to the aquatic life like fish. These metals have ability to induce the production of reactive oxygen species (ROS). These ROS can interact with nucleic acids and cause oxidation of DNA. The potential of ROS to damage DNA has become a topic of significant interest for environmental toxicology studies. The present research was conducted to assess the genotoxic potential of cobalt (Co) and chromium (Cr) mixture to fish Labeo rohita by using micronuclei assay. Fish were exposed to the four sub-lethal doses (26.61, 13.30, 19.98 and 7.98 mgL(-1)) of Cr+Cr mixture for 28 days and blood was sampled after 7 days interval. A group (n=10) of fish were also kept in clean water (negative control=NC) and cyclophasphamid (positive control=PC), separately. Blood from caudal vein of fish was collected to see the micronuclei (MN) and de-shape nuclei (DN). Results showed that test dose 26.61 mgL(-1) induced significantly higher mean MN followed by 13.30 mgL(-1), 19.98 mgL(-1), 7.98 mgL(-1), PC and NC. However the result of DN showed minor difference. The frequency of DN in RBCs was maximum in fish exposed to 26.61 mgL(-1) dose followed by the order: 13.30 mgL(-1)> 19.98 mgL(-1)> PC > 7.98 mgL(-1)> NC. Micronuclei and deshaped nuclei frequency differ with the exposure period as 28>21>14>7 days. This study concluded that metals present in mixture in aquatic environment can induce DNA damage in fish.

Automated summary

The increasing load of heavy metals in aquatic habitats poses a serious threat to aquatic life, inducing DNA damage and increasing the frequency of micronuclei and de-shaped nuclei.