CB诱导熊本牡蛎三倍体及其存活率与倍化率的变化关系

为诱导熊本牡蛎三倍体，研究了细胞松弛素B (CB)浓度、诱导起始时间、诱导持续时间等因素对卵裂率、D幼率、三倍体率的影响，并分析了幼虫、稚贝及成贝的存活率和三倍体率的变化特征。结果显示，CB浓度为0.5~0.6 mg/L，诱导起始时间为40%受精卵释放第一极体，诱导持续时间为20 min时可获得87%的三倍体率。卵裂率、D幼率、三倍体率的最大影响因素分别为CB浓度、诱导持续时间、诱导起始时间与诱导持续时间。三倍体率与卵裂率无显著负相关性，而与D幼率呈显著正相关。因此，减小CB浓度或诱导持续时间，可同时获得较高的三倍体率与幼虫产量。3~15日龄三倍体组与对照组的存活率分别由71.27%与96.09%降低至34.14%与58.80%，成贝期450日龄(9月)三倍体组与对照组的存活率分别为53.62%与44.67%。3~9日龄三倍体率从87%降低至77%，而90~450日龄三倍体率平均值为59.21%±4.99%，表明幼贝与成贝期三倍体率变化较小，三倍体率的维持与存活率无显著相关性。

Triploidy induction by CB and their survival rate and triploidy rate in Kumamoto oyster (Crossostrea sikamea)

In order to induce triploid using cytochalasin B (CB) in Crossostrea sikamea, three effecting factors, including CB concentration, initial time of induction, and duration time of induction, were optimized by the cleavage rate, D larvae rate, and triploidy rate. In addition, the variations of survival rate and triploidy rate were also compared for larvae and adults. The results suggested that the optimal method of triploid induction were 0.5 mg/L CB, 40% first polar body releasing for initial time of induction, and 20 min for duration time of induction. The triploidy rate of 87% was obtained by the optimal method. The first effecting factor for cleavage rate, D larvae rate, and triploidy rate was CB concentration, duration time of induction and initial time of induction, and duration time of induction, respectively. Furthermore, there was insignificant negative relationship between triploidy rate and cleavage rate. Whereas, the positive relationship was significant between triploidy rate and D larvae rate. As a result, high triploidy rate and high larvae production could be obtained by decreasing both CB concentration and duration time of induction. The survival rates were 71.27% and 96.09% at 3 days, and 34.14% and 58.80% at 15 days for triploid and control groups, respectively. Comparatively, the survival rate were 53.62% and 44.67% for adults at 450 days (September) in triploid and control groups, respectively. The triploidy rate declined from 87% to 77% during the period of 3 to 9 days. Whereas, the triploidy rate was 59.21%±4.99% on average from 90 to 450 days, suggesting that there was no correlativity between triploidy rate and survival rate, with a small variation of triploidy rate for adults. This study provides valuable data for further exploration into triploidy of C. sikamea.