点带石斑鱼染色体显带技术及其描绘研究

点带石斑鱼(Epinephelus malabaricus)属于鲈形目, 科、石斑鱼亚科、石斑鱼属, 是中国东南沿海暖水性礁栖的名贵海产经济鱼类. 采用PHA活体注射结合秋水仙素培养, 取点带石斑鱼全肾, 低渗处理, 空气干燥制片法制作染色体标本, 利用Alu I 限制性内切酶介导的原位切口平移显带技术, 在点带石斑鱼有丝分裂中期染色体上诱导出带纹清晰、分散良好的多重带. 结果显示, 多数染色体显现出8-10条带纹, 最少的一对染色体也有4条带纹, 同源染色体带纹基本一致, 在每对染色体上的数目及其分布具明显特征性且相对稳定, 同时发现不同分裂相的同一号染色体上, 特征带纹鲜明一致, 带纹数目基本吻合, 具有可重复性和可操作性; 然后用人X和Y染色体文库特异DNA为探针, 对点带石斑鱼的有丝分裂中期分裂相染色体进行了描绘研究. 结果表明, 点带石斑鱼染色体组中测出了人X染色体特异DNA同源片段的3个保守同线群, 分别在点带石斑鱼的第7、第13和第22号同源染色体上, 它们的杂交信号最近边距着丝粒的百分比距离分别大约为62.3%、43.4%及44.4%; 人X染色质同源片段的大小约占点带石斑鱼基因组的4.63％. 但用人Y染色体DNA描绘点带石斑鱼染色体时, 没有检测出可见的同源片段. 研究结果可以为从低等脊椎动物到人类性染色体的进化过程提供一种新的研究思路.  

Banding techniques and painting on chromosome of Epinephelus malabaricus

Epinephelus malabaricus (Perciformes, Serranidae), a rare marine commercial fish, inhabits in the warm-water reef along the southeast coast of China. Chromosome specimens of grouper E. malabaricus, sampled from kidney cells in metaphase by vivo injection of phytohemagglutinin (PHA) and treatment with colchicine, from which well-scattered, clear, and longitudinal bands were obtained by restriction endonucleases (Alu I) demonstrated by in situ nick translations. Most chromosomes presented 8-10 bands, at least 4. The number and characteristics of the bands in the homologous chromosomes were stable, and the major features of the same serial chromosomes from different mitotic metaphase figures were identical. The chromosome specimens were then painted with human X and Y chromosome-specific DNA probes. Surprisingly, some homologous segments of human X chromosome were found in the E. malabaricus genome, and all the segments were scattered in three pairs (t7, t13, t22) in homologous grouper chromosomes. The nearest distance between the centromere and the fluorescent in situ hybridization (FISH) signal from the t7, t13 and t22, was 62.3%, 43.4% and 44.4%, respectively, and the homologous segment of human X chromosome was about 4.63% of the E. malabaricus genome. No homologous segment of the human Y chromosome was found. These may provide a new research approach for the evolution from lower vertebrates to human sex chromosomes.