中国胭脂鱼的细胞遗传学分析

采用植物血凝素、秋水仙素活体注射和肾细胞直接制片法分析了中国胭脂鱼(Myxiocyprinus asiaticus)的染色体核型和Ag-NORs显带;并以中国胭脂鱼血细胞为样本,鸡血细胞DNA含量为标准(2.50 pg),用流式细胞仪测定了中国胭脂鱼的 DNA 含量.结果表明:(1)中国胭脂鱼染色体数目2n=100,核型公式为10 m+4 sm+12 st+74 t, NF=114,未观察到次缢痕及随体,亦未发现有性染色体.(2)中国胭脂鱼染色体具有1对Ag-NORs,位于第1对染色体短臂上,间期核中Ag-NORs的数目为1~2个,未见Ag-NORs的联合现象.(3)PI和DAPI作为荧光染料,得出中国胭脂鱼DNA含量分别为5.50±0.24 pg和6.16±0.03 pg.(4)中国胭脂鱼为四倍体,在特定的分类阶元中属于较原始的鱼类.

Cytogenetic analysis of Chinese sucker Myxocyprinus asiaticus

We documented the karyotype and Ag-NORs of Myxocyprinus asiaticus using a routine method including intraperitoneal injection of PHA and colchicine, air-drying, and staining. In addition, we determined the erythrocyte nuclear DNA content of M. asiaticus using flow cytometry, with chicken erythrocytes (2.50 pg) as a standard. The diploid chromosome number of M. asiaticus was 2n=100, and the karyotype was 2n=10 m+4 sm+12 st+74 t, NF=114. The secondary constriction, satellite chromosomes, and heterosomes were not observed. Silver staining revealed that most chromosomes featured a pair of Ag-NORs. The number of Ag-NORs ranged from 1 to 2 in the interphase nucleus, but Ag-NOR combinations were not observed. We estimated the diploid cellular DNA content of M. asiaticus was(5.50±0.24)pg and (6.16±0.03)pg using PI and DAPI fluorescent dyes, respectively. M. asiaticus was tetraploid, and is a member of the primitive fishes in the specific classification order.