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雄性三倍体虹鳟(Oncorhyncus mykiss)可以发育至生理成熟并表现出较强的雄性副性征,性腺发育基本正常;雌性三倍体虹鳟性腺几乎不发育,并且存在着类雄性化的发育趋势。本研究拟通过对虹鳟杂交胚胎(2n♀×3n♂)发育状况及其DNA倍性的分析,进而确认三倍体虹鳟是否具有与二倍体虹鳟类似的生育能力并分析其原因。选取经两个世代家系选育的虹鳟优良品系二倍体雌性虹鳟作为母本,以热休克方法人工诱导的优质雄性三倍体虹鳟为父本,常规人工采集精卵授精,获得三倍体雄性与二倍体雌性杂交胚胎,观察杂交胚胎的发育进程,通过流式细胞仪检测杂交胚胎的DNA含量,进而与二倍体雌雄交配获得的胚胎对照确定杂交胚胎的倍性。结果表明,杂交胚胎的受精率、发眼率和孵化率均显著地低于对照组,杂交胚胎多数在发眼期之前死亡,破膜的胚胎在仔鱼期上浮前全部死亡。杂交胚胎的DNA含量分布范围较大,大致可以分为两个水平,接近84%的胚胎的DNA含量介于二倍体与三倍体之间,约为对照组DNA含量的2.5倍;约有16%的胚胎的DNA含量在三倍体和四倍体之间。本研究认为,染色体非整倍体化可能会引起杂交胚胎细胞核质不相容,进而导致基因表达调控紊乱,从而使杂交胚胎不能正常发育,无法完成由母体卵黄供给的内源营养向外源营养的转换,成为导致杂交胚胎发育过程中大量死亡,以及杂交仔鱼在破膜之后开始进食之前全部死亡的一个重要原因。
The male Triploid rainbow trout (Oncorhynchus mykiss) can develop to physiological maturity and showed strong male phenotype, gonadal development is basically normal; female triploid rainbow trout gonads almost undeveloped, and there is a male-like development trend. In this study, we analyzed the developmental status and DNA ploidy of hybrid rainbow trout embryos (2n♀ × 3n♂), and then confirmed whether triploid rainbow trout had similar fertility to the diploid rainbow trout and analyzed its causes. The diploid female rainbow trout (Triticum aestivum L.), a strain of rainbow trout bred by two generations of pedigrees, was selected as the female parent. The high-quality male triploid rainbow trout (TGP) induced by heat shock method was used as the male parent. And diploid female hybrid embryos observed hybrid embryonic development process, by flow cytometry hybridization embryos DNA content, and then diploid and male and female mating embryos obtained to determine the ploidy of hybrid embryos. The results showed that the fertilization rate, the rate of eye formation and the hatching rate of hybrid embryos were significantly lower than those of the control group. Most embryos of hybrid embryos died before the onset of eye period. All the ruptured embryos died before the floating period of larvae. The DNA content of the hybrid embryos distributed in a wide range and could be roughly divided into two levels. Nearly 84% of the embryos had DNA content between diploid and triploid, which was about 2.5 times that of the control group. 16% of embryos have DNA content between triploid and tetraploid. This study suggests that chromosome aneuploidy may cause incompatible nucleocytoplasm in hybrid embryonic cells, leading to disorder of gene expression regulation, so that hybrid embryos can not develop normally, and endogenous nutrition supplied by maternal egg yolk can not be completed to exogenous nutrition Conversion is a major cause of mass deaths during hybrid embryo development and the complete death of hybrid larvae prior to rupture of membranes.