PT12 Metals and Bioaccumulation
Exhibit Hall
8:00 AM - Tuesday
(PT147) Dynamics of metal subcellular distribution and its relationship with metal uptake in the marine bivalves.
Ng, T.1, Wang, W.-X.1, 1 Department of Biology, The Hong Kong U. of Science & Technology, Hong Kong
ABSTRACT- Subcellular distribution of metals in the marine animals plays an important role in metal toxicity, detoxification and trophic transfer in the aquatic systems. Recent studies also suggest the biochemical controls of metal bioavailability to bivalves. This study investigated the dynamic change of subcellular metal distribution and the correlation between each biochemical pool and metal uptake in the marine mussels and oysters. During the uptake from the dissolved phase, metals were redistributed over the 24-exposure period. Metals binding to the heat-sensitive proteins reduced over time. In addition, Cd binding to metallothionein-like protein increased in the mussels and Zn in insoluble fraction decreased in the oysters. Percentage of metals associated with the heat-sensitive protein had a positive relationship with the dissolved uptake in the mussels but the biochemical distribution of metals in the oysters was not correlated with the uptake except for Ag. In contrast to the dissolved exposure, subcellular distribution of metals in mussels fed with metal-bound diatom was similar within 6 d, also among individuals fed with metal-bound diatom and sediment between 6 h and 60 h. The metal partitioning was also not correlated with the metal assimilation efficiency in the mussels. In general, our results implied that the heat-sensitive protein is the dynamic pool of metals during the aqueous exposure and a faster uptake may lead to higher percentage of metals in the pool, however metal uptake from the dietary phase is not controlled by the biochemical pool.
Key words: subcellular distribution, metals, uptake, bivalves