TETRAPLOID INDUCTION IN PATINOPECTEN YESSOENSIS WITH CHEMICALS

The scallop (Patinopecten yessoensis) were released and cultured in north China sea transplanted from Japan since 1980. Tetraploid veliger were carried out with four chemicals on this scallop in 1998-2000. Tetraploid were induced by inhibition of the polar body and first mitosis with cytoplalasin B (CB), colchicine, 6-DMAP and caffeine combined with CB, respectively. It indicated that the yield of tetraploidy not more than 25% induced by inhibiting the first mitosis with CB, colchicine and 6-DMAP, respectively, while it can be induced with higher percentage by blocking PB_(1) releasing with CB. The tetraploidy percentage of groups shock began at 15-22min after fertilization are h igher than that shock began at 42min, and the yield of tetraploidy also increased with the CB density and time lasting. The highest tetraploid percentage at veliger larvae stage is 56.5%, shocked with CB after 20-22 to 62-67 minutes after fertilization at 12deg C. Development speed of shocked group embryo was 48 hours later than control to veliger, there are a lot of trochophore in shocked groups after fertilization which chromosome are 21-28.