engleski

Coping strategies in earthworms to low levels of Cd

Earthworms are ecologically important soil dwelling organisms which are affected by anthropogenic pollution through agriculture and industry. Cd is one of the main soil pollutants with a high carcinogenic and toxicogenic potential. Lumbricus terrestris, the common earthworm, has therefore been used in lab exposures to low doses of environmentally relevant Cd concentrations over three months with a subsequent recovery period in control soil followed by an exposure to high levels of Cd. Quantitative RealTime PCR, comet assay, and enzyme activity assays have been applied to determine metallothionein (MT) and phytochelatin synthase (PCS) levels as well as DNA damage and oxidative stress in earthworms. MTs are probably able to act as the exclusive mechanism to detoxify low doses of Cd over several months and to prevent the organism from Cd-induced damages and oxidative stress. Control earthworms exposed to high Cd concentrations revealed an increase of MT gene expression levels. Low dose Cd-exposed earthworms which face a high Cd concentration are able to induce MT expression to a much higher degree. The transcriptional regulation mechanism of MTs is therefore suggested to be responsive to the exposure history. Therefore, it seems that highly flexible coping strategies have evolved in earthworms facing environmental stress like Cd pollution.

Lumbricus terrestris, metalothioneins, Cadmium

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