日本东京湾云纹石斑鱼染色体核型研究

Chromosome Karyotype of Epinephelus moara (Temminck & Schlegel 1842) of Tokyo Bay Population

中文关键词: 云纹石斑鱼  染色体  核型

英文关键词: Epinephelus moara  Chromosome  Karyotype

中文摘要:

      采用PHA体内直接注射法制备了云纹石斑鱼(Epinephelus moara Temminck & Schlegel 1842)东京湾群体头肾组织染色体标本并分析其核型。结果显示，其东京湾群体二倍体染色体数为48，其中，亚中部着丝粒3对；其余21对染色体为端部着丝粒染色体，其染色体臂数NF为54，核型公式为：2n = 48，6sm + 42t，NF = 54；第24对染色体的短臂的形态具有多态性。该鱼染色体臂数高于石斑鱼类的原始核型类群，属于石斑鱼属的特化类群。云纹石斑鱼日本东京湾群体与厦门群体染色体核型存在显著差异，东京湾群体比厦门群体多1对亚中部着丝粒染色体，可能是长期隔离导致染色体重组进化形成的。结果表明，云纹石斑鱼不同地理群体间存在丰富的遗传差异，可利用不同地理群体间的种内杂交优势改良云纹石斑鱼种质。

英文摘要:

      Cytogenetic analysis is a valuable tool for germplasm study and protection. In order to clarify the Germplasm resources of Epinephelus moara, the metaphase chromosomes of E. moara of Tokyo Bay population were obtained from the head kidney tissue by the method of PHA and colchicine injection and the karyotype was analyzed by using microscopes. We observed 464 mitotic metaphases from 6 individuals, and 356 of all observed mitotic metaphases (76.72%) showed 2n = 48 chromosomes, which indicated that there were 48 chromosomes in the diploid. We then analyzed 10 mitotic metaphases and calculated the relative length and arm ratio of the chromosomes. The relative length of the chromosomes in E. moara of Tokyo Bay population varied from (5.13±0.15) % to (2.81±0.13) %. The arm ratio of the 14th chromosome was 2.35±0.14, and the arm ratio of the 16th chromosome was 2.71±0.24. The 24th chromosome had the minimum arm ratio, which was 1.99±0.13. According to arm ratio, the diploid consisted of 6 submetacentric, and 42 telocentric chromosomes, and the fundamental number of chromosome arms was 54, which indicated karyotypic formula in E. moara of Tokyo Bay population was 2n = 48，6sm + 42t，NF = 54. The form of the 24th chromosome was changed in different metaphase from the same individual (the shorter arm changed among filiform, T type, and SM type), which may be related with the expressed activity of the rDNA in nucleolar organizing region. By comparison with the chromosome karyotypes of other Epinephelus species, E. moara has the evolutive characteristics of karyotypic pattern and belongs to the specialization group. As detected, the karyotypes of E. moara were different between Japan (Tokyo Bay) and China (Xiamen coastal waters) samples, which may be caused by geographic isolation. There were abundant genetic diversity among different geographic populations, and the germplasm improvement of E. moara could be accelerated by heterosis among different geographic groups.