6—DMAP诱导太平洋牡蛎三倍体——抑制受精卵第二极体释放↑（*）

于１９９６～１９９７年，用６－ＤＭＡＰ抑制太平洋牡蛎受精卵第二极体的释放，诱导产生三倍体，最高诱导率为９３．８％。该实验组胚胎孵化率为８１．０％，Ｄ形幼虫畸形率为１７．６％。实验选用Ｌ９（３４）设计，进行三因素三水平的正交试验：６－ＤＭＡＰ浓度，设３００、４５０和６００μｍｏｌ／Ｌ等三水平；诱导时机（观察静止状态的受精卵，以受精卵出现第一极体的百分率指示），设１０％、３０％和５０％等三水平；诱导持续时间，设１０、１５和２０ｍｉｎ等三水平，试验设三次重复。解剖法获取精卵，人工授精。染色体倍性检查采用染色体计数法。根据正交试验直观分析结果，得出诱导太平洋牡蛎三倍体各因素的最优水平组合：当３０％受精卵出现第一极体时，将受精卵浸泡在含６－ＤＭＡＰ４５０μｍｏｌ／Ｌ的海水中１０ｍｉｎ；三因素的主次顺序：６－ＤＭＡＰ浓度→诱导时机→诱导持续时间。６－ＤＭＡＰ的浓度和诱导时机对三倍体诱导率的影响显著；但诱导持续时间影响不显著。部分试验组得到４．２％～１３．６％的四倍体和１０％左右的非整倍体，这种情况可能与受精不同步抑制第一极体释放而导致的染色体多极分离有关。

Triploidy of Crassostrea gigas induced with 6-DMA P: by blocking the second polar body of the zygotes

From 1996 to 1997,a number of experiments were undertaken to induce triploid of Pacific oysters, Crassostrea gigas by blocking the second polar body of the zygotes with 6-Dimethylaminopurine (6-DMAP). L9(34)design was selected to engage in orthogonal experiment of 3 factors and 3 levels:the 3 concentrations of 6-DMAP were 300,450 and 600 mol/L;the 3 levels of induced occasion (the percentage of zygotes with polar body I when observing the zygotes in still) were 10%,30% and 50%; and the 3 levels of induced duration were 10,15 and 20 min,respectively. Each experiment was repeated 3 times. Sperms and ovums were obtained with anatomy method,ripen in vitro.Ovums were washed and inseminated artificially. Ploidy was identified by chromosome counts.The results indicated that the highest inductivity of triploid is 93.8%;the hatch rate is 81. 0% and the percentage of abnormal D-shaped larvae is 17.6%.The sequence of the 3 decisive factors is as follows:induced occasion,the concentration of 6-DMAP,and the duration of treatment.The induced occasion and the concentration of 6-DMAP are main factors;and the duration is secondary factor. The optimal conditions of treatment is the 6- DMAP concentration of 450 mol/L, the induced occasion when 30% of zygotes presenting polar body I, and the duration of 10 min. We also obtained 4.2.6% tetraploids and 10% aneuploid in the experiment. The reasons maybe relate to the multipolarity of chromosomal aberration.