Ultrastructural aberrations in the hepatopancreas of Metapenaeus dobsoni (Miers) exposed to mercury

Abstract

Toxic effect of mercury on, the flower-tail shrimp, Metapenarus dobsoni (Miers) was investigated by exposing the animal to sub-lethal concentrations of 0.005 and 0.015 ppm of the metal. As pollutant-induced stress leads to cellular responses and often gets manifested as ultrastructural alterations, an attempt was made to delineate the alterations and damage caused to fine structure level with the help of electron microscopy. The hepatopancreas, which has been identified as a target organ, depicted considerable' ultrastructural alterations. Mitochondria1 membrane was damaged and the cristae were swollen, assuming circular shape at many instances. Endoplasmic reticulum was totally damaged. Excessive accumulation of lipid was noticed in the R-cells. Electron-dense inclusions were found "nipped off' from the basal lamina. Merging of vesicles resulted in collection of electron-dense materials in larger residual vacuoles. The damage seemed to be dosedependent. Ultrastructural damage of the cellular components was found to render the cardinal organelles less or non-functional, thus affecting the functional integrity of the organism. Pollutant induced injuries of this kind often prove to be useful biological tools to assess the stress profile