SUBTOXIC CADMIUM-CONCENTRATIONS REDUCE COPPER-TOXICITY IN THE EARTHWORM ENCHYTRAEUS-BUCHHOLZI

The toxicity of copper (Cu) and cadmium (Cd) for the earthworm Enchytr aeus buchholzi was investigated in an aquatic test system. Cu was much more toxic than Cd. The 2 day-LC(50)-values amounted to 0.43 mg Cu/l and 9.0 mg Cd/l, respectively. The Cu-toxicity was significantly reduc ed when the worms were pre-exposed to the subtoxic Cd-concentration of 0.1 mg/l for 2 days. Cd induces a gene encoding a cysteine-rich, non- metallothionein 25 kDa-protein, designated CRP. The CRP-gene is induce d at only minimal levels by Cu. However, Cu enhances CRP-gene expressi on when CRP is once induced by pre-exposure of worms to Cd. Copyright (C) 1996 Elsevier Science Ltd