匙吻鲟的细胞遗传学分析

采用体内注射PHA和秋水仙素,肾细胞短期培养,常规空气干燥法制备匙吻鲟(Polyodon spathula)的染色体标本.对其肾细胞染色体数目统计分析表明,匙吻鲟染色体组南120条染色体所组成.以测得的核型参数和按Levan,et al.提出的染色体划分标准得出:具有22对中部着丝粒染色体(m),16对亚中部着丝粒染色体(sm),22对亚端部着丝粒染色体(st)和端部着丝粒染色体(t);染色体臂数(NF)为196,核型公式为44 m + 32am + 44st,t.再采用流式细胞仪分析系统测定匙吻鲟体细胞的DNA含量,与鸡血细胞标准对照相比为2.69±0.19,以鸡红细胞DNA含量2.3 pg/N测算.则匙吻鲟体细胞DNA含量为6.18 pg/N.根据所得到的结果并结合已发表的鲟鱼类DNA含量和染色体资料,判定匙吻鲟为四倍体物种.鲟形目伍类全部为多倍体起源的鱼类,在细胞水平的进化比较特殊,以染色体加倍的方式进行.染色体加倍及分化,可能是造成鲟形目鱼类种类较多及多倍体类型(4n、8n、12n等)丰富的主要原因.

Cytogenetic analysis of Polyodon spathula

Metaphase chromosome specimens of Polyodon spathula, injected with PHA and colchicin, were prepared from short-term culture of kidney cells with air-drying technique. It diploid chromosome number was 2n = 120. The karyotype was composed of 44m, 32sm and 44st, t chromosomes, NF = 196. Diploid nucleus DNA content was measured from the somatic cell of P. spathula, using flow cytometer(Beckman cell Lab Quant, made in USA) and the DNA content (2.3pg/N) of erythrocytes of chicken (Gallus domestica) as standard. The DNA content of P. spathula was 6.18pg/N, which was corresponded with the result measured chromosome number as ploidy. According to the present results and date reported, P. spathula was possibly a tetraploid (4n). Combination of the present results and data reported among Acipenseriformes including two families and six genera, Acipenseriformes was the polyploid origin's fish, and was quite completely special at the cell level which evolved by chromosome doubling. The chromosome’s doubling and differentiation possibly were primary caused of polyploidization and polyploid type (4n, 8n, 12n and so on) richly. Polyoidization had played an important role in the diversity of Acipenseriformes.