The sea mammal Dugong dugon and its environment: Chemical analysis and speciation studies

Ibrahim Haji Abdul Rahman

Samples of sediment, seagrass and dugong tissues were analyzed for selected elements: Fe, Zn, Cu, Pb, Mn, Cd, Ni, Co, Al, P and S. Iron was the most interesting element found in relation to the samples analyzed. The level of iron in dugong liver tissue is extraordinarily high, ranging from 12 691- 71 123 µg g-1 dry weight. Ferritins from liver of dugong were isolated and characterized. Ferritin was purified by heat treatment and two-column gel filtration on Sephadex G-75 and Sephacryl S-300. Isolation of ferritin was monitored by determining iron to protein ratio. For reference, ferritin was also isolated from human liver and spleen. Purity of the isolated ferritin was determined by analytical electrophoresis. The amino acid composition and subunit nature of the purified ferritin are within the normal range reported for the well-characterized human liver and spleen ferritins and horse spleen ferritin. The core size of purified dugong ferritin was determined by electron microscopy, which also indicated that purified dugong ferritin had a limited crystallinity. Mossbauer spectra of purified ferritin at 78K indicated the presence of ferrihydrite (5Fe2O39H2O) rather than geothite-like (α-FeOOH) iron oxide. This latter iron oxide was detected in the whole liver tissue of dugong. Overall, the characteristics of purified dugong ferritin are similar to other mammalian ferritins. The elemental analysis of dugong tissue, seagrass and sediment in its environment indicated that the dugong studied live in areas of minimum anthropogenic activity. The naturally high level of iron in its environment and food is reflected in the high liver iron values. The ability of the liver tissue to withstand the high concentration of iron in the tissue without apparently damaging the tissue deserves further study.

The sea mammal Dugong dugon and its environment: Chemical analysis and speciation studies

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