MP9 Metals and Bioaccumulation
Monday, 14 November 2005: 8:00 AM - 5:30 PM in Exhibit Hall

(LEE-1117-612152) Comparison of sub-cellular partitioning of Cd and Zn in the oyster, Crassostrea gigas and clam, Ruditapes philippinarum.

Jung, S.K.¹, Lee, B.G.¹, Yang, S.Y.¹, Lee, J.S.², ¹ Chonnam National University, Kwangju, S. Korea² NeoEnBiz, Seoul, S. Korea

ABSTRACT- A radiotracer study was conducted to evaluate partitioning of Cd and Zn in different organs and sub-cellular pools of the oyster, Crasssostrea gigas. Adult oysters were exposed for 3 wks. to 3 different concentrations of dissolved stable Cd and Zn together with their radiotracers, 109-Cd and 65-Zn and then depurated in uncontaminated seawater for 3 wks. During exposure and depuration, metals in soft tissue of the oyster were separated periodically into 3 organs (gill, digestive gland and remaining tissue) and several sub-cellular pools (enzymes, organells, metallothioneins, metal-rich granules, and cellular debris). Neither metal concentrations nor exposure/ depuration time affected distribution of Cd and Zn in the 3 organs. Gill tissue contained 41 and 23%, digestive gland contained 18% each, and residue tissues 42 and 59% of total soft tissue Cd and Zn, respectively. Most of the soft tissue Cd and Zn partitioned into metal-rich granules (54-72%) followed by enzymes (14-26%), organelles, metallothioneins, and cellular debris. In contrast, sub-cellular partitioning of Cd in the clam, Ruditapes philippinarum was highest in the cellular debris (40%), followed by enzymes (26%), metallothioneins (15%), metal-rich granules (13%), and organells (7%), while that of Zn were similar (26-28%) among cellular debris, metal-rich granules, and organells. Overall, the metals in the oysters were partitioned more in detoxified forms (metal-rich granules and metallothioneins) (60-75%) than those in the clam (28-34%), but less in trophically available forms (enzymes, organells and metallothioneins) (26-43%) than in the clam (45-47%).

Key words: Sub-cellular partition, Bivalves, Metal, Bioaccumulation