凤鲚染色体核型研究

为了解凤鲚(Coilia mystus)染色体数量和核型结构,以上海市临港近岸的1~2龄性成熟凤鲚为材料,采用鳃丝细胞进行短期离体培养方法制备染色体标本,对凤鲚染色体核型进行了研究。结果表明,凤鲚雌雄染色体数量存在差异,雌性染色体数目为2n=47,雄性染色体数目为2n=48;核型公式为2n(♀)=47 t,2n(♂)=48 t;雌性染色体臂数(NF)=47,雄性NF=48。雄性凤鲚染色体相对长度范围为(2.66±0.27)^5.54±0.25,雌性凤鲚染色体相对长度范围为(2.83±0.32)^5.70±0.38,雌雄凤鲚的染色体相对长度不存在显著差异(P>0.05),各相邻两对染色体之间相对长度无明显差异(P>0.05)。在凤鲚的染色体中,最长的一对染色体上存在随体,次缢痕。凤鲚存在性染色体,其性染色体类型为ZO/ZZ型。

Karyotype of Coilia mystus

In recent years,the quantity of Coilia mystus resources has been seriously reduced,so it is urgent to study the protection of C.mystus germplasm resources.In order to understand the number and karyotype structure of C.mystus,the cytogenetic data of C.mystus were supplemented,and the basis was laid for the protection of the genetic resources and genetic breeding of C.mystus,this study collected silk of sexually mature individuals with the age of 1 to 2 years old as the materials from Shanghai Lingang inshore.The C.mystus chromosomes karyotype was studied based on the operation process of colchicine pre-treatment,hypotonic treatment,fixation,dissociation,thermal treatment and dyeing.The results showed that chromosome from the male and female C.mystus were different.The female C.mystus had 47 chromosomes in the diploid and the karyotype formula was 2n=47t,and the male C.mystus had 48 chromosomes in the diploid and the karyotype formula was 2n=48t.The female chromosome number of arms(NF)was 47,and that of male was 48.The relative length of male C.mystus chromosome was in the range of 2.66±0.27 to 5.54±0.25,while the relative length of female C.mystus chromosome was in the range of 2.83±0.32 to 5.70±0.38.There was no significant difference(P>0.05)in relative length of chromosome between male and female C.mystus,and there was also no significant difference(P>0.05)in the relative length between each two adjacent pairs of chromosomes.The longest pair of chromosomes had follows and subconstriction in the chromosome of C.mystus.C.mystus had sex chromosomes,and its sex chromosome type was ZO/ZZ,which was rare not only in fish but also in vertebrates.Reference studies showed that the sex chromosome types of Coilia were all ZO/ZZ.From the perspective of genetic cytology,this discovery explains that the three species of fish are closely related,and the ZO/ZZ sex chromosomes should be the common phenomenon of Coilia fish.In this study,the traditional chromosome preparation method was improved.Due to the strong stress and short on-shore survival time of C.mystus,the specimens of C.mystus were prepared by short-term in vitro culture of living C.mystus cells.The results of this study supplement the cytogenetic data of C.mystus and the reference data of the germplasm test of C.mystus,providing data for the classification and evolution of Coilia fish from the chromosome level.