中文摘要：

利用荧光原位杂交（FISH）技术将5S rDNA基因定位在牙鲆和半滑舌鳎染色体上,结果表明,5S rDNA基因在雌、雄性半滑舌鳎的一对同源染色体上分别存在2个杂交信号位点;在二、三倍体牙鲆的同源染色体上分别存在2个和3个杂交信号位点,杂交信号明显且特异。本研究首次将5S rDNA基因定位在半滑舌鳎和三倍体牙鲆的染色体上,为牙鲆及半滑舌鳎倍性鉴定、染色体鉴别提供了有效方法。此外,根据牙鲆5S rDNA基因编码区序列设计引物,扩增出大菱鲆和半滑舌鳎5S rDNA基因编码区序列,与鲽、塞内加尔鳎、大口黑鲈、七鳃鳗的5SrDNA基因序列进行同源性比较后发现,5种鲽形目鱼类5S rDNA基因序列同源性高达98.3%,系统发生分析结果显示5种鲽形目鱼类聚为一支;各序列中GC含量均显著高于AT含量。

英文摘要：

Using fluorescence in situ hybridization （FISH）, 5S rDNA gene was mapped on chromosomes of half-smooth tongue-sole（Cynoglossus semilaevis）and olive flounder（Paralichthys olivaceus）for the first time. The results showed that 5S rDNA has two hybridization signal loci in a pair of homologous chromosomes of male and female half-smooth tongue-sole, respectively; 5S rDNA has two and three hy- bridization signal loci in a pair of homologous chromosomes of diploid and triploid olive flounder, respec- tively, referring to the clear and specific hybridization signals. FISH mapping of 5S rDNA genes on the chromosomes of diploid half-smooth tongue-sole and triploid olive flounder provides a feasible method for ploidy and chromosome identification of half-smooth tongue-sole and olive flounder. In addition, the coding region sequences of 5S rDNA gene of turbot （Scophthalmus maximus） and half-smooth tongue-sole were amplified using same primers designed for olive flounder 5 S rDNA gene, and the phylogenetic analysis of the 5S rDNA genes in four species of flatfishes, including plaice（Pleuronectes platessa）, senegalese sole （Solea senegalensis）, largemouth bass（Micropterus salmoides） and arctic lam- prey（Lampetrajaponica） showed that the 5S rDNA gene of five species of flatfishes shared high homology （98.3%） and gathered into a branch. The GC content was significantly higher than the AT content in con- servative sequence of 5 S rDNA coding region of these five species of flatfishes.