THE EFFECTS OF CADMIUM AND IRON ON CATALASE ACTIVITIES IN TUBIFEX

The effects of 1 mu M Cd(II), alone and in combination with several co ncentrations of Fe(II), were investigated in Tubifex tubifex (a fresh water worm) by the determination of catalase activities in vivo at 6, 12, 24, and 48 h. At 6 h postexposure the catalase activities in all c admium-exposed groups dropped below control values. At 12 and 24 h the values rose; at 48 h the catalase activities exceeded control values. The combination of 1 mu M Cd(II) plus 100 mu M Fe(II) exhibited the l east inhibition of catalase activity at 6 h and the most increased act ivity at 48 h. By comparison, the in vitro results of incubating bovin e liver catalase for 6 h with different concentrations of Cd(II) and F e(II) showed that Cd alone at 10 mu M had no inhibitory effect on cata lase activity and that 100 mu M Fe(II) decreased the catalase activity to 40% of the control. The effects of Fe(II) on Cd(II) LC(50) values were also studied. Adding 100 mu M Fe(II) or pretreating for 48 h with a mixture of 1 mu M Cd(II) and 100 mu M Fe(II) decreased the toxicity of Cd(II) by almost 70%. These studies indicate (a) that a mixture of Cd(II) and Fe(II) will increase catalase activities in vivo after a 2 -day exposure and (b) that certain concentrations of Fe(II) can protec t the worm against Cd(II) toxicity. One suggested mechanism is that Fe (II) can inhibit Cd uptake and transfer. An enhanced catalase activity appears to protect the worms against the toxic effects of Cd(II).