Blocking polar body with cytochalasin B in the fertilized eggs of thesmall abalone, Haliotis diversicolor supertexta (Lischke), and thedevelopment and ploidy of the resultant embryos

摘要

The effects of blocking polar body I (PB1) or polar body II (PB2) with four different dosages of cytochalasin B (CB) on the development and ploidy of resultant embryos were studied in the small abalone, Haliotis diversicolor supertexta (Lischke), To block the release of PB1. the fertilized eggs were treated with 0.25, 0.5, 1.0 or 2.0 mg L-1 of CB for 10 min beginning at 3 min post-fertilization at 24 degrees C. To block the release of PB2, the fertilized eggs were treated under the same conditions as PB1, except that the treatment was begun 10 min post-fertilization. In the control group, only 41.8% of the cells had a diploid number of 32 chromosomes, although spontaneous haploids (9.0%), tripolids (7.5%) and aneuploids (41.7%) were also observed, In CB treatment of PB1 and PB2 groups, 5.0-28.6% of the cells remained as diploid, triploids (10.0-18.9%) and aneuploids (41.1-61.0%), With regard to the development of the resultant embryos, the proportion of normal embryos in the control group was 87%, while in the treatment groups, the proportions of normal embryos in the PB1 and PB2 groups were 57-58% and 53-56% in the 0.25 mg L-1 and 0.5 mg L-1 CB treatments, respectively. From this data on induced triploids and the resultant development of normal embryos, the proportions suggest that 0.25-0.5 mg L-1 of CB for 10 min was sufficient for blocking the release of PB1 or PB2 to produce triploids in the small abalone.