Meeting Abstract

36.6  Sunday, Jan. 5 09:15  Metallothionein gene expression differs in populations with different exposure history MUSTONEN, MS; HAIMI, J; KNOTT, KE*; University of Jyvaskyla; University of Jyvaskyla; University of Jyvaskyla emily.knott@jyu.fi

Metal pollutants in soils can harm organisms and decrease species diversity. Species can cope with metal contamination with the help of metallothioneins, small metal-binding proteins that are involved in homeostasis and detoxification of metals. We studied the expression of metallothionein with qPCR in a small, epigeic earthworm, Dendrobaena octaedra, collected from two sites differing in metal exposure: Harjavalta, contaminated by a local Cu-Ni smelter, and Jyväskylä, an uncontaminated site. Worms from both sites were exposed to different concentrations of copper (control, 50, 100 or 200 mg/kg) or zinc (control, 75,150 or 300 mg/kg) for 7, 14 or 28 days to see if there is a time related dose response in gene expression. Population comparison showed that earthworms from the two populations differed in metallothionein expression (F=83.616, df=1, P< 0.001), being higher in earthworms from the contaminated site. There was a positive correlation between metallothionein expression and Cu, Zn and Cd concentration in earthworms from Jyväskylä, but not in worms from Harjavalta, suggesting that higher gene expression in worms from the contaminated site may aid regulation of metal body burdens. In the exposure experiment, a dose response to zinc was found (F=7.112, df=3,P< 0.001) but there was no response to copper (F= 0.849, df=3, p=0.472), suggesting that this isoform of metallothionein might not be strongly induced by copper, but moreso by zinc or some other metal that was not included in the experiment. Exposure time also affected expression, but only for earthworms from Jyväskylä (Cu: F= 17.601, df=2, P< 0.001, Zn: F=9.437, df=2, P< 0.001), suggesting that there is a delay in the metallothionein response of earthworms in this population. Adaptation of D. octaedra to metal contamination can explain its persistence in contaminated forest soils.