转基因哺乳动物细胞自合成多不饱和脂肪酸

亚油酸、亚麻酸是哺乳动物体内的必需脂肪酸,但哺乳动物由于缺乏△12和ω-3脂肪酸脱氢酶而自身不能合成．△12和ω-3脂肪酸脱氢酶存在于真菌、植物和一些低等动物中．为了实现哺乳动物细胞亚油酸的自身合成,克隆了线虫编码△12脂肪酸脱氢酶的FAT-2基因eDNA序列,通过优化密码子,构建真核表达载体,稳定转染细胞,经抗生素筛选获得稳定整合FAT-2基因的CHO细胞．PCR和RNA印迹（Northern blot）验证了基因的整合和表达．气相色谱分析细胞的脂肪酸含量表明,FAT-2基因的表达显著提高了转基因细胞中亚油酸的含量,亚油酸含量为阴性对照细胞的2．4倍．研究结果表明,低等动物△12脂肪酸脱氢酶可以重建哺乳动物多不饱和脂肪酸合成途径,并利用细胞中的油酸合成亚油酸．上述研究为进一步利用转基因技术促进农业动物合成多不饱和脂肪酸从而提高食品营养价值奠定基础．     

MicroRNAs与脂类代谢

本文综述了miRNAs在脂类代谢调控以及脂肪酸对miRNAs影响的研究进展.miRNA能够在转录后水平参与脂类代谢的多个层面,其中miR-122、miR-370、miR33等能够通过与靶基因(Cpt1α、ABCA1等)结合,直接或间接调节细胞内脂肪酸生成、脂肪酸氧化、甘油三酯合成、胆固醇流动及脂蛋白合成等多个路径.而饮食中的脂类,尤其是必需脂肪酸,能够通过对miRNAs表达的调节参与到包括癌症抵抗、炎症缓解等多个生物学进程中.     

食物中的反式脂肪酸

反式脂肪酸是指含一个或多个独立反式双键的脂肪酸．主要产生于油脂的氢化及反刍动物的生物氢化过程。煎炸烘烤的食品、反刍动物制品、人造奶油是食物中反式脂肪酸的主要来源。研究表明,反式脂肪酸对机体可能有一定负面作用。大量摄入可能会导致冠心病的发生及婴幼儿的发育不良。     

Determination of Essential Fatty Acid Composition among Mutant Lines of Canola （Brassica napus）, through High Pressure Liquid Chromatography

The present study aimed to quantify the methyl esters of lenoleic acid (LA), γ-lenolenic acid (LNA) and oleic acid (OL) in the oil of Brassica napus mutants. Five stable mutants (ROO-75/1, ROO-100/6, ROO-125/12, ROO-125/14, and ROO-125/17)of B. napus cv. 'Rainbow' (P) and three mutants (W97-95116, W97-0.75/11 and W97-.075/13) of B. napus cv. 'Westar' (P) at M6 stage, exhibiting better yield and yield components, were analyzed for essential fatty acids. The highest seed yield was observed in the mutant (ROO-100/6) followed by ROO-125/14 of Rainbow, that is, 34% and 32% higher than their parent plants, respectively. Westar mutant W97-75/11 also showed 30% higher seed yield than its parent plant. High performance liquid chromatography analysis of the composition of fatty acids indicated that OL was the most dominant fatty acid, ranging from 39.1 to 66.3%; LA was second (15.3-41.6%) and LNA was third (18.1-28.9%). Mutant ROO-125/14 showed higher OL contents than parent (Rainbow). These results are expected to support the approval of ROO-125/14 in the National Uniform Varietal Yield Trials (NUVYT) as a new variety based on high oil quality.