黄鳝脂肪酸去饱和酶及延长酶基因cDNA的克隆与表达

为了解黄鳝合成长链多不饱和脂肪酸(LC-PUFA)的能力,利用Trizol提取黄鳝肝脏总RNA,经RT获得cDNA,基于脂肪酸去饱和酶(FAD)及延长酶(FAE)基因同源系列设计简并引物进行黄鳝cDNA的PCR扩增、测序,获得黄鳝FAD及FAE基因部分片段序列。然后分析黄鳝FAD及FAE的同源性和系统进化情况及黄鳝胚胎和胚后发育期仔鱼该两个基因的表达水平。结果表明:黄鳝FAD与军曹鱼的△6去饱和酶同源性高达85%,其次是大菱鲆(83%),FAE与军曹鱼、线鳢、澳大利亚金枪鱼等的同源性高达89%;但FAD和FAE在系统发育树中均自呈一支。FAD和FAE基因在黄鳝胚胎和胚后发育阶段均有表达,以出膜后2～4 d表达量最高。提示黄鳝具有合成LC-PUFA的能力,但不同发育阶段合成能力不同。

Cloning and Expression of Partial Sequences of the Fatty Acids Desaturase and Elongase cDNA of Rice Field Eel

To understand the ability of ricefield eel(Monopterus albus) to synthesize long-chain polyunsaturated fatty acids(LC-PUFA),trizol and RT technique were used to get total RNA and cDNAs from liver of rice field eel,respectively.The cDNAs were amplificated by PCR with the degenerative primers designed based on GenBank homologous series of fatty acid desaturase gene and elongase gene sequences,respectively.The PCR products were cloned and sequenced to obtain partial sequences of fatty acid desaturase(FAD)and elongase(FAE) gene sequences of rice field eel.Then their genetic homology and phylogenetic relationship and their expression level during the embryonic and past-embryonic period were analyed,respectively.These results show that the fatty acid desaturase of rice field eel showed a highest homology(85%) with Rachycentron canadum in homology tree,forward Psetta maxima(83%),Channa striata(79%),Xiphophorus Helleri(78%);Fatty acid elongase of rice field eel showed a high homology(89%) with Rachycentron canadum,Channa striata and Thunnus maccoyii.The fatty acid desaturase of rice field eel dominated one branch in phylogenetic tree,independently.Similarly,the fatty acid elongase.The FAD and FAE genes expression level could be detected during the embryonic and post-embryonic development stages and the peak appeared in the fry(2-4 d past hatching).This means that the rice field eel possesses the ability to synthesize LC-PUFA during the embryonic and post-embryonic development stages,but the ability is different in different development stages.