Calcium moderation of cadmium stress explored using a stress-inducible transgenic strain of Caenorhabditis elegans.

In a transgenic strain of Caenorhabditis elegans carrying a stress-inducible lacZ reporter gene, short-term sublethal exposure to heavy metals activates transgene expression. The transgene response to Cd2+ is strongly inhibited by Ca2+ ions; furthermore, Ca2+ reduces the net accumulation of Cd2+ by worms. Both Ca2+ and a variety of calcium uptake inhibitors (nifedipine, La3+, verapamil) depress the dose response of the transgene to Cd2+. Calcium ionophore (A23187) slightly increases transgene activity in control and Cd2+ treated worms, but has a much larger effect in the case of Mn2+, reflecting its much greater affinity for this ion.