The role of triacylglycerol as a reservoir of polyunsaturated fatty acids for the rapid production of chloroplastic lipids in certain microalgae
The role of triacylglycerol as a reservoir of polyunsaturated fatty acids for the rapid production of chloroplastic lipids in certain microalgae
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DOI：
10.1042/0300-5127:0280740
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发表时间：
2000-12-01
影响因子：
3.9
通讯作者：
Bigogno, C
中科院分区：
文献类型：
--
作者：
Cohen, Z;Khozin-Goldberg, I;Bigogno, C
众所周知，许多微藻会积累三酰甘油（TAG），尤其是在硝酸盐饥饿的情况下。一般来说，这些标签主要由饱和和单不饱和脂肪酸构成。相比之下，红色微藻 Porphyridium currentum 的 TAG 富含花生四烯酸（AA，20:4 omega6）和二十碳五烯酸（EPA，20:5 omega3）。这种藻类的突变体在次优温度下生长受损，其 EPA 和单半乳糖基二酰基甘油 (MGDG) 真核分子种类的水平降低，而 TAG 的水平升高。标记实验表明，野生型TAG的标记减少，而突变体的标记仍然很高。目前，突变体的真核 MGDG 标记较少。同样，绿藻T12的TAG可以在低温下生长，其AA含量极其丰富。我们用放射性AA标记了保持在25℃下呈指数生长的T12培养物，并在25℃、12℃或4℃下将培养物进一步培养12小时。在低温下，标记的 AA 从 TAG 转移到极性脂质。这些发现可能表明多不饱和脂肪酸可以融入膜中，使生物体能够快速响应低温引起的应激。
Many microalgae are known to accumulate triacylglycerols (TAGs), especially under nitrate starvation. Generally, these TAGs are predominantly constructed of saturated and monounsaturated fatty acids. In contrast, the TAGs of the red microalga Porphyridium currentum are rich in arachidonic acid (AA, 20 :4 omega6) and eicosapenta-enoic acid (EPA, 20:5 omega3). A mutant of this alga, impaired of growth at suboptimal temperatures, was shown to have reduced levels of EPA and of the eukaryotic molecular species of monogalactosyldiacylglycerol (MGDG) and an elevated level of TAG. Labelling experiments have shown that labelling of wild-type TAGs decreased, whereas that of the mutant remained high. Contemporarily, eukaryotic MGDG of the mutant was less labelled. Similarly, TAGs of the green alga T12, which can grow at a low temperature, are extremely rich in AA. We have labelled exponentially growing cultures of T12 kept at 25 degreesC with radioactive AA and cultivated the cultures for a further 12 h at 25 degreesC, 12 degreesC or 4 degreesC. At lowtemperatures, labelled AA was transferred from TAGs to polar lipids. These findings may indicate that polyunsaturated fatty acids that can be incorporated into the membranes, enabling the organism to quickly respond to low-temperature-induced stress.