栉孔扇贝第1卵裂抑制型雌核发育二倍体的研究

Gynogenetic diploid induced by suppression of first cleavage of Chlamys farreri

利用6-二甲基氨基嘌呤(60μg/cm3;6-DMAP)和细胞松弛素B(0.5μg/cm3;CB)抑制受精卵的第1次卵裂,授精后60和65 min分别用CB和6-DMAP持续处理20和15 min,可诱导出12.5%和27.5%的第1卵裂抑制型雌核发育二倍体.细胞学观察显示,6-DMAP抑制第1次卵裂产生的雌核发育二倍体主要在第1次有丝分裂后期的受精卵,由于破坏了纺锤体和阻止了染色体分离,导致一个二倍性雌核的形成,而CB有效地阻止了第1次卵裂的胞质分裂.尽管倍化率和D型幼虫发生率较低,但该研究首次报道了栉孔扇贝第1卵裂抑制型雌核发育二倍体诱导的可行性.

Conditions required for the induction of gynogenetic diploid by suppression of first cleavage of Chlarnys farreri were examined using treatments of cytochalasin B （0. 5 g/cm^3 ; CB） and 6-dimethylaminopurine （60 g/cm^3;6-DMAP）. Treatments with CB and 6-DMAP were effective in inhibiting not only meiosis but also mitosis, and the optimum time for the suppression of first cleavage began at 60-65 min with 20 and 15 min duration time after insemination. This resulted in 12.5% and 27. 5% mitotic gynogenetic diploids （mitotic-G2N） respectively. Cytological observations indicated that 6-DMAP disrupted the spindle at mitosis and inhibited chromosome movement, resulting in the formation of one diploid female nucleus, while CB inhibited the cytokinesis of first cleavage but not the segregation of chromosomes. Although attempts to produce mitotic-G2N demonstrated that ploidy levels and the developmental rate of D-shaped larvae are low, the results of this study suggest the possibility of producing mitotic-G2N Chalarnys farreri.