Bioaccumulation and localization of exogenous cadmium in a teleost by electron microscopy (TEM) and its specific quantitation by electron probe X-ray microanalysis (EPMA)

• Published in: Bioorganic & medicinal chemistry 2000-03, Vol.8 (3), p.475-482
• Main Authors: TAYAL, A. K, KAUR, I, MATHUR, R. P
• Format: Article
• Language: English
• Subjects: Agnatha. Pisces; Animal, plant and microbial ecology; Animals; Applied ecology; Biological and medical sciences; Cadmium - pharmacokinetics; Cations, Divalent - metabolism; Cations, Monovalent - metabolism; Ecotoxicology, biological effects of pollution; Effects of pollution and side effects of pesticides on vertebrates; Electron Probe Microanalysis; Fishes - metabolism; Fundamental and applied biological sciences. Psychology; Gills - chemistry; Gills - cytology; Gills - ultrastructure; Liver - chemistry; Liver - cytology; Microscopy, Electron; Muscles - chemistry; Muscles - cytology; Silver Compounds; Silver Staining; Time Factors; Tissue Distribution
• ISSN: 0968-0896; 1464-3391
• DOI: 10.1016/S0968-0896(99)00296-5

A cadmium bioconcentration study was carried out in a fresh water teleost, Colisa fasciatus, to study the bioaccumulation kinetics and fate of exogenous cadmium (Cd) in biological tissues. Study shows that on exposure of the fish to a sublethal concentration of cadmium in test water, Cd uptake results in its bioconcentration in gills, liver and muscle tissues. To explore whether the accumulated Cd reaches the membranes or inside the cells, transmission electron microscopy (TEM) of the thin sections of tissues was done after histochemical localization of Cd in cells by modified SST method. TEM studies of sections of gills, liver and muscle tissues showed the deposits of exogenous Cd (visualized as dense clouds) in biological cells. This suggests the presence of free or loosely bound Cd on the membranes and inside the cells, which in the presence of Na2S is converted into insoluble metal sulfides. Electron probe X-ray microanalysis (EPMA) studies confirmed the presence of Cd on the membrane surface as well as inside the cells of bioindicator organs suggesting involvement of membrane transport of exogenous Cd inside the cells and its deposition as loosely bound insoluble metal complexes.