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2C - Biomarkers (TUP/108) Metallothioneins in earthworms as a biomarker of copper and zinc exposure: application of a spectrophotometric method. Lukkari, Tuomas1, Taavitsainen, Mirka1, Soimasuo, Markus1, Haimi, Jari1, Oikari, Aimo1, 1 University of Jyväskylä, Jyväskylä, Finland ABSTRACT- Metallothionein (MT) concentration in earthworm Aporrectodea tuberculata was measured to find out: 1) induction of MT during copper and zinc exposure; 2) differences between two populations with different exposure history; 3) potential for using MT in earthworms as a biomarker of metal exposure. A spectrophotometric method previously used for molluscs was utilised to measure MT concentration in earthworm tissues. MT concentration in A. tuberculata was measured from populations sampled at three distances (1, 2 and 4 km) from a steel smelter. Two A. tuberculata populations, with and without earlier metal exposure, were tested in laboratory with three Cu/Zn concentrations (100/175, 200/350, 400/700 mg kg-1 d.w. of soil) and for 2, 7 and 14 days. In the field samples, MT concentration decreased with increasing distance from the smelter. In the laboratory, MT concentration depended on the duration and degree of exposure, and the population. Cu/Zn exposure caused biochemical effects on A. tuberculata without changes in biomass or mortality. Soil metal concentrations correlated positively with MT concentration after 2 and 7 days of exposure. After 14 days, only the population with earlier exposure had higher MT concentration in contaminated soil. In addition, the population with earlier exposure had higher MT concentration than the population without earlier exposure. Increased MT in exposed worms is assumed to be involved in storage and redistribution of metal cations as a high capacity detoxification pathway. The spectrophotometric method applied appeared to be simple, repeatable and effective in measuring MT concentration in earthworm tissues, and suitable for ecotoxicological monitoring as well as experimental research. Key words: Aporrectodea tuberculata, Earthworms, Metallothioneins, Biomarker |
