Stolyhwo Andrzej, Mol Jolanta
Faculty of Human Nutrition and Consumer Sciences, Warsaw University of Life Sciences (SGGW), Warszawa, Poland.
Acta Biochim Pol. 2007;54(4):741-6. Epub 2007 Dec 9.
Changes in the composition of fatty acids (FA) were determined in lipid extracts isolated from developing ovaries containing ovules and developing seeds of Echium vulgare L. The samples were collected successively over 20 days beginning with the first day after flowering. The contents of the n-6 FA family members, i.e., gamma-linolenic (GLA) (C(18:3)) and linoleic (LA) (C(18:2)) acids changed in a parallel manner and reached the maximum of 13.9% and 24%, respectively, on the 12th day, after which they fell systematically down to 8.6% and 18.2%, respectively, on the 20th day after flowering. Starting with day 13, the content of alpha-linolenic acid (ALA) (C(18:3) n-3) begins to grow intensively, from 24.2% to 39.3% on the 20th day after flowering. The increase in the content of stearidonic acid (SDA) (C(18:4) n-3), up to 10.5% on the 20th day after flowering, occurred steadily as the seeds developed, and was independent of the changes in the content of GLA and LA. The pattern of changes in the content of SDA, GLA, LA and ALA during the development of seeds, and the occurrence of SDA in the seed oil of other plants, demonstrate that the biosynthesis of SDA in the seeds is critically dependent on the presence of ALA. The above condition indicates that SDA biosynthesis in the seeds of Echium vulgare follows the scheme LA --> simultaneous, competitive, action of Delta(6) and Delta(15) desaturases, leading to the formation of GLA and ALA, respectively, and then ALA (Delta(6) des) --> SDA. The biosynthesis according to the scheme: GLA (Delta(15) des) --> SDA is highly unlikely.
从含胚珠的发育中的卵巢和蓝蓟发育中的种子中分离出的脂质提取物中，测定了脂肪酸（FA）组成的变化。从开花后的第一天开始，在20天内连续采集样本。n-6脂肪酸家族成员，即γ-亚麻酸（GLA）（C(18:3)）和亚油酸（LA）（C(18:2)）的含量以平行方式变化，在第12天分别达到最大值13.9%和24%，此后在开花后第20天分别系统地降至8.6%和18.2%。从第13天开始，α-亚麻酸（ALA）（C(18:3) n-3）的含量开始急剧增加，从开花后第20天的24.2%增加到39.3%。随着种子的发育，硬脂酸（SDA）（C(18:4) n-3）的含量稳步增加，在开花后第20天达到10.5%，且与GLA和LA含量的变化无关。种子发育过程中SDA、GLA、LA和ALA含量的变化模式，以及SDA在其他植物种子油中的存在情况，表明种子中SDA的生物合成严重依赖于ALA的存在。上述情况表明，蓝蓟种子中SDA的生物合成遵循LA --> Δ(6)和Δ(15)去饱和酶同时、竞争性作用的方案，分别导致GLA和ALA的形成，然后ALA（Δ(6)去饱和酶） --> SDA。按照GLA（Δ(15)去饱和酶） --> SDA的方案进行生物合成的可能性极小。
