Effects of heavy metals on antioxidants and expression of HSP70 in different tissues of Milk fish (Chanos chanos) of Kaattuppalli Island, Chennai, India.

Distribution of heavy metals and its associated oxidative stress, ultrastructure and expression of HSP 70 were studied in varies tissues of Chanos chanos collected from polluted sites compared with the fish collected from less polluted sites of Kaattuppalli Island. The concentrations of copper, lead, zinc, cadmium, manganese and iron were quantified in gills and liver. The results showed marked differences between the two sites as well as significant variations within the tissues. The decreasing trend of metals in the tissues of fish sampled from both polluted and less polluted sites was in the order of Fe>Mn>Zn>Cu>Pb>Cd. Overall, the highest metal concentrations were found in the fish collected from polluted sites. Similarly increase of antioxidant enzymes biomarkers due to heavy metals was also evident in gills and liver of the fish collected from polluted sites. These tissues were further investigated by scanning and electron microscopy and the results were compared with the reference less polluted sites. The presence of large lipid droplets in liver and increase of mucous cells in gills were some of the most noticeable alterations observed and were related to heavy metal contaminants. It is concluded that scanning, ultrastructural and useful of HSP70 biomarkers for heavy metal induced oxidative stress, and demonstrate that precautions need to be taken in polluted sites of Kaattuppalli Island in order to prevent heavy metal pollution that can occur in the future.

Integrated use of histological and ultrastructural biomarkers in Mugil cephalus for assessing heavy metal pollution in Ennore estuary, Chennai.

Bioaccumulation of heavy metals and its associated histological perturbations were studied in various tissues of Mugil cephalus collected from Ennore estuary and compared with the fish collected from off-shore region. The concentration of copper, lead, zinc, cadmium, manganese and iron were quantified in gills, liver and muscle. The results showed marked differences between the two sites as well as significant variations within the tissues. The decreasing trend of metals in the tissues of fish sampled from both Ennore estuary and off-shore was in the order of Fe>Mn>Zn>Cu>Pb>Cd. Overall, the highest metal concentrations were found in the fish collected from Ennore estuary. The accumulation in the gills and liver of M. cephalus was found to be quite high in comparison with the muscle. These tissues were further investigated by light and electron microscopy and the results were compared with the reference site (off-shore region). The presence of large lipid droplets in liver and increase of mucous cells in gills were some of the most noticeable alterations observed and were related to heavy metal contaminants. It is concluded that histopathological and ultrastructural biomarkers provide reliable and discriminatory data to augment heavy metal pollution in Ennore estuary. Therefore, long-term monitoring is necessary to assess the eco-health of the Ennore estuarine environment by choosing bio-indicator species like M. cephalus, which provide accurate, reliable measurements of environmental quality.