应用聚合酶链式反应和限制性内切酶酶切技术鉴别鳕鱼

大西洋鳕鱼（Gadus morhua）作为一种具有高营养价值的海洋经济鱼类，常常会被掺入劣质、价格低廉的阿拉斯加狭鳕鱼（Theragra chalcogramma）或白姑鱼（Argyrosomus argentatus）等。通过对大西洋鳕鱼、阿拉斯加狭鳕鱼和白姑鱼的线粒体细胞色素c氧化酶亚基Ⅰ（cytochrome c oxidase subunit Ⅰ，COⅠ）基因序列进行比对分析，分别设计特异性引物。结果表明：通过聚合酶链式反应（polymerase chain reaction，PCR）扩增得到大西洋鳕鱼和阿拉斯加狭鳕鱼COⅠ 基因扩增产物大小为579 bp，白姑鱼为399 bp；进一步使用BstE Ⅱ限制性内切酶对大西洋鳕鱼和阿拉斯加狭鳕鱼COⅠ 基因的PCR产物进行酶切，大西洋鳕鱼不能被酶切，而阿拉斯加狭鳕鱼被酶切为长度分别为361、218 bp的2 个片段，从而有效区分大西洋鳕鱼、阿拉斯加狭鳕鱼和白姑鱼。

Identification of Cod by Polymerase Chain Reaction and Restriction Endonuclease Digestion

Gadus morhua, an economically important marine fish with high nutritive value, is often adulterated with some inferior and cheap fish species such as Theragra chalcogramma or Argyrosomus argentatus. By comparative analysis of the sequence of mitochondrial gene (COⅠ ) encoding cytochrome c oxidase subunit Ⅰ between Gadus morhua, Theragra chalcogramma and Argyrosomus argentatus, specific primers were designed separately for each fish species. The polymerase chain reaction (PCR) amplicons of COⅠ gene from Gadus morhua and Theragra chalcogramma were both 579 bp in length, while the amplified product of COⅠ gene from Argyrosomus argentatus was 399 bp in length. The PCR product of COⅠ gene from Gadus morhua could not be digested by the BstEII restriction endonuclease, while the PCR product of COⅠ gene from Theragra chalcogramma was digested into two fragments (361 and 218 bp). As a result, Gadus morhua, Theragra chalcogramma and Argyrosomus argentatus could be effectively differentiated from one another.