Effects of TBT on functional responses of coelomocytes in the marine worm Sipunculus nudus

We investigated the effects of TBT on some functional responses of cultured coelomocytes from the marine worm Sipunculus nudus, a sediment-feeding sipunculan common in the littoral zone of the North Adriatic Sea (Italy), in order to evaluate the possibility of using these animals as sentinel organism in biomonitoring studies. At 10 μM TBT, the viability of coelomocytes, measured by Trypan Blue dye exclusion test, was 70%, so that concentrations in the range 0.01-10 µM were considered to be sublethal. At 10 μM TBT, cytolysis of haemerythrocytes was also observed. After TBT exposure, the cell spreading index, i.e., percentage of coelomocytes with amoeboid shape, and the endocytotic index, i.e., percentage of coelomocytes with ingested Neutral Red dye, were significantly (p<0.001) inhibited even at 1 μM TBT. The apoptotic index, i.e., percentage of coelomocytes with chromatin condensation detected with Acridine Orange, showed a significant (p<0.001) increase at 1 μM after 60 min exposure to the xenobiotic. The lysozyme activity index, was significantly (p<0.05) reduced at 0.05 μM TBT. All these indexes may be proposed as biomarkers, being sensitive, rapid, reproducible, and useful tools for monitoring TBTcontaminated marine sediments.