四带小鲃胚胎发育及系统进化分析

Embryonic development and phylogenetic analysis of Puntius tetrazona

  • 摘要: 四带小鲃是一种具有较高经济价值的小型热带观赏鲤科鱼类。本实验利用光学显微镜观察了其胚胎发育全过程,采用小鱼游泳法和流式细胞术检测了其染色体数目及DNA含量,最后利用线粒体基因组序列对其在鲃亚科中的系统进化地位进行了分析。结果显示,水温28 °C条件下,四带小鲃的胚胎发育经历了卵裂前期、卵裂期、囊胚期、原肠期、神经胚期、器官形成期和出膜期7个时期,24 h孵化出膜。与斑马鱼出膜时开始形成色素不同,四带小鲃出膜时色素未形成,这有利于早期器官形成和发育的观察。以公鸡血细胞DNA含量2.30 pg/2c为标准,四带小鲃DNA含量为1.50 pg/2c。四带小鲃染色体为2n=50,系统进化树显示,四带小鲃在鲃亚科鱼类进化史上属于较早出现的鱼类,染色体数为原始的数目类型,鲃亚科其他属的鱼类独立发生多倍化。上述结果为四带小鲃的繁殖和遗传改良研究提供了基础资料。

     

    Abstract: Puntius tetrazona is a small tropical ornamental fish with high economic value. In this study, the process of embryonic development was observed. The chromosome number and DNA content of P. tetrazona were detected with the small fish swimming method and the flow cytometry. Meanwhile, the phylogenetic analysis of the Barbinae subfamily was performed with mitochondrial genome sequences. The results showed that the embryonic development process of P. tetrazona was classified into 7 stages, including the fertilized egg stage, cleavage stage, blastocyst stage, gastrula stage, neurula stage, organogenesis stage and hatching stage. Compared to zebrafish which hatched out 48 hours post fertilization (hpf) with pigment, P. tetrazona hatched 24 hpf at the water temperature of 28 °C without pigment. The chromosome number and DNA content of P. tetrazona are 2n=50 and 1.50 pg/2c, respectively. The phylogenetic tree showed that P. tetrazona appeared earlier during the speciation of the Barbinae subfamily. These results will provide the basis for P. tetrazona breeding and genetic improvement.

     

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