牙鲆同质雌核发育二倍体的诱导及其早期生长研究

Studies on the Induction of Mitogynogenetic Diploids and Their Early Growth of Olive Flounder Paralichthys olivaceus

人工诱导雌核发育是水产动物性别控制的重要技术手段之一,同时也是快速建立近交系或纯系、建立遗传作图群体的方法之一。采用静水压力抑制受精卵第一次卵裂的方法诱导了牙鲆同质雌核发育二倍体。不同的处理起始时刻、不同压力及压力持续的时间对受精卵的发育及染色体加倍率有较大影响。处理组受精卵发育相对缓慢,畸形率较高,正常仔鱼孵化率较低。如果处理前受精卵保持在(15.5±0.5)℃,压力处理受精卵的最佳条件是:从受精后75 min开始、用55 MPa的压力处理6 min,该条件下处理组正常仔鱼孵化率较高,为13.7%,染色体观察和最大核仁数计数结果表明,此时的二倍体诱导率也最高。染色体观察结果还显示在不同处理组中存在不同比例的非整倍体。利用获得的最佳诱导条件处理获得了数千尾雌核发育幼鱼,观察表明,雌核发二倍体鱼的生长速度明显低于普通二倍体,且个体间差异较大。该研究为进一步开展牙鲆全雌育种和连锁图谱的构建提供技术支撑。

Artificial production of gynogenetic diploids is one of the methods for sex control in aquatic an- imals, for the establishment of inbreeding or pure lines and for the construction of mapping material. In this study we produced viable mitogynogenetic diploids by hydrostatic pressure shocks in olive flounder Paralichthys olivaceus. The timing, different pressures and different treatment durations greatly affected the development as well as the diploidy rates of treated embryos. Treated eggs showed slower develop- ment speed, higher malformation rate and lower hatching rate than normal diploid did. When the fertilized eggs were maintained at （15.5±0. 5） ℃ before any treatment, the optimal hatching rate of normal fry was achieved by pressure shocks of 55 MPa applied at 75min after fertilization with 6min duration. Under these conditions, the normal fry hatching rate of the treated eggs was 13.7~. Chromosome observation and counting of the maximum number of nucleolus showed that the diploidy rate was the highest. Chro- mosome observation also defined some aneup[oids in the treated groups. Several thousand of gynogens were obtained by treatment with the optimal conditions. These diploid gyngens showed slower growth rate and bigger among-individual variation than the normal diploid control did. The successful production of mitogynogenetic diploids provided materials for sex control breeding and for the construction of fine ge- netic map in this species.