A Proteomic approach to the development of potential estuarine biomarkers for metal contamination using the Sydney Rock Oyster (Saccostrea glomerata), NSW Australia

The introduction of waste products into rivers and estuaries in industrial and urbanised areas since the industrial revolution has led to significant increases in chemical contamination. As such, it is now imperative to develop effective monitoring methods to protect biota and the environment. Biomarkers provide information on the cause and effect paradigm of contamination by linking contaminants directly to their effects on biota. However, traditional single parameter biomarker analyses can be insensitive, especially at low contaminant levels. Proteomics provides a new method for identifying potentially hundreds of species specific biomarkers simultaneously at extremely low levels of contamination and over short time periods, allowing early detection of environmental damage. The current study uses proteomics to assess the effects of metal contamination on Sydney Rock oysters. Saccostrea glomerata were exposed for four days to three environmentally relevant concentrations (100 µg/l, 50 µg/l and 5 µg/l) of copper, lead and zinc. Oyster haemolymph from metal-exposed oysters was compared to haemolymph from non-exposed controls by 2-dimensional electrophoresis to identify differentially expressed proteins. Differential proteins were subsequently characterised using tandem mass spectrometry (LC-MS/MS) so that their putative biological functions could be assigned. The data suggest that there are unique protein expression profiles not only for each metal, but at each concentration of metal. Exposure to 100 µg/l of copper, lead and zinc yielded a total of 21 differentially expressed proteins. Only one of these proteins was common to all three metals. Differentially expressed proteins were putatively assigned 11 different biological functions, of which cytoskeletal activity accounted for 25%. Ongoing work includes testing the efficacy of these potential protein biomarkers in the natural environment using oyster samples from field studies conducted in Lake Macquarie, NSW, Australia.