Polyploidy in the Manila clam Ruditapes philippinarum. II. Chemical induction of tetraploid embryos.
Tetraploidy was induced in embryos of Manila clams by treating the eggs with a solution of cytochalasin B (1 mg/litre) 0-10 min after insemination (before formation of the 1st polar body) or 45 min after insemination (before 1st cleavage). Treatment, started 5 and 45 min after insemination, produced 64.4±7.8 and 28.3±2.3% tetraploid embryos resp. after 6 h. However, no tetraploids were detected in 4-month old spat.