METAL-PROTEIN BINDING PATTERNS IN THE POLYCHAETE WORM NEREIS-DIVERSICOLOR DURING SHORT-TERM ACUTE CADMIUM STRESS

Cadmium-binding patterns of the worm (Nereis diversicolor) were analys ed in response to exposure to the sublethal dose of 80 mg of Cd/l for 1, 12, 24, 48 and 72 hr. The exposure of animals to cadmium resulted i n the accumulation of a large amount of the metal in whole body worms. The cadmium was distributed between the insoluble and the soluble fra ctions of animals. The accumulation process of cadmium followed a line ar relationship with the time of exposure. The main accumulation occur red in the soluble fraction of the worms and reached, in terms of conc entrations, the value of the exposure medium between 24 and 48 hr. In the soluble fraction, the cadmium was distributed among high and low m olecular weight components previously determined as the extracellular haemoglobin and a myohaemerythrin-like protein respectively. The bindi ng of cadmium appeared mainly to the haemoglobin and increased with ti me of exposure. The exposure of animals to cadmium and the subsequent accumulation of the metal seemed to provoke a disturbance of the endog enous iron metabolism of the worm consisting in a reduction of the amo unt of iron in the insoluble fraction and an increase in the soluble f raction. In the latter compartment, the iron concentration of the haem oglobin containing peak was observed to increase with time of exposure .