CHEMICAL AND PHYSICAL METHODS OF TRIPLOIDY INDUCTION IN Crassostrea gigas (THUNBERG, 1793)

Three methods of triploidy (3N) induction were tested in diploid (2N) oysters Crassostrea gigas: two chemical methods cytochalasin-B (CB) and 6-dimethylaminopurine (6-DMAP), and one physical method with temperature shock. The objective was to evaluate the triploidy induction technology using flow cytometry as a tool to check the results of induction. The experiments were performed in separate and a seawater temperature in the tanks was maintained at 25 degrees C for all experiments. In the experiment I, the efficacy of triploidy induction was evaluated using CB (0.5 mg L-1) and 6-DMAP (390 mu mols L-1). In the experiment II, the efficiency of triploidy induction was tested using CB (0.5 mg L-1) and 6-DMAP (450 mu mols L-1). In the experiment III, the efficiency of triploidy induction was evaluated using CB (0.5 mg L-1) and temperature shock (25 to 36 degrees C). In all three experiments, viable triploid larvae were obtained. However, in the experiments I and II (with chemical methods), high mortality of larvae was observed, especially for the treatment CB. From these results, it is suggested the replacement of CB by other methods of triploidy induction, due to its high cost and high toxicity to humans and to the environment.