缺刻缘绿藻三酰甘油（TAG）中花生四烯酸（ArA）的含量占其总脂肪酸的68.0%，几乎是它占细胞总脂肪酸百分数的3倍，表明TAG在合成过程中存在着偏好ArA的现象。鉴于多不饱和脂肪酸（PUFA）是在膜脂上经过酰基修饰而产生以及藻类一般的TAG合成途径，推测这些途径中的相关酶偏好ArA，才能确保ArA被优先用来合成TAG。为此，本研究拟在缺刻缘绿藻酰基编辑和TAG合成代谢途径中相关8个酶的基因克隆、功能鉴定及亚细胞定位等基础上，重点调查这些酶对不同脂肪酸底物的催化反应动力学参数，弄清哪些酶有利于ArA被优先合成为TAG；检测该藻在氮饥饿胁迫培养前后这些酶基因的表达量变化，结合脂质组学的定性和定量分析结果，解析ArA被优先用于TAG合成的代谢途径并探讨其可能的机制。本研究有助于进一步了解藻细胞怎么能利用PUFA合成TAG，并通过基因工程手段使微藻能合成更多符合人类对不同种类脂肪酸需求的TAG。

Arachidonic acid (ArA) accounts for 68.0% of the total fatty acids in the triacylglycerol (TAG) isolated from Myrmecia incisa, and it is nearly 3 times the percentage of total cellular fatty acids, suggesting that this microalga has a preference for ArA in the process of TAG biosynthesis. In regard to the fact that polyunsaturated fatty acids (PUFA) are generated in the membrane via acyl modification and the general synthesis pathway of TAG in microalgae, it is hypothesized that the enzymes in these pathways should have a preference for ArA in order to ensure that ArA was preferentially used for the biosynthesis of TAG. To confirm this hypothesis, this proposal focused on gene cloning, function identification and subcellular localization of 8 enzymes related to acyl editing and TAG synthesis pathways in M. incisa. The estimation of the kinetic parameters of these enzymes on different fatty acid substrates will clarify which enzyme in these pathways is beneficial for the preferential use of ArA in the TAG synthesis. Based on the measurement of relative transcription of the genes related to TAG biosynthesis and qualitative and quantitative analysis of the combination of lipidomics, the pathway of ArA used preferably to TAG biosynthesis and its possible mechanism will be explored. This study is helpful to further understand how the algae cells can use PUFA to synthesize TAG, and through the genetic engineering method, the microalgae can meet the human requirements of different kinds of fatty acids.