Shibata Shiori, Arimura Shin-Ichi, Ishikawa Takahiro, Awai Koichiro
Graduate School of Integrated Science and Technology, Shizuoka University, Shizuoka, Japan.
Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.
Front Plant Sci. 2018 Mar 27;9:370. doi: 10.3389/fpls.2018.00370. eCollection 2018.
Euglenoids are unique protists that can grow photoautotrophically, photomixotrophically, and heterotrophically. Here we grew under these different growth conditions and determined cellular contents of seven membrane lipids and one storage lipid (triacylglycerol), which account for more than 94 mol% of total membrane lipids. We also describe the relationship among chloroplast and mitochondria developments with lipid contents, protein contents, and oxygen evolution/consumption rates. In photoautotrophic growth conditions, . cells accumulated chlorophyll, photosynthetic proteins, and glycolipids typical to thylakoid membranes. The same occurred for the cells grown under photomixotrophic conditions with higher respiration rates. In heterotrophic conditions, . cells had higher respiration rates compared to cells grown in other conditions with the accumulation of pyruvate: NADP+ oxidoreductase, a mitochondrial protein and phospholipid common in mitochondria. Cells were also observed using a confocal laser scanning microscope and found to show more chlorophyll autofluorescence when grown photoautotrophically and photomixotrophycally, and fluorescence of MitoTracker when grown photomixotrophically and heterotrophically. These results suggest that under illumination, . develops functional thylakoid membranes with membrane lipids and proteins for photosynthesis. In the medium with glucose, the cells develop mitochondria with phospholipids and proteins for respiration. Possible application based on lipid analysis for the enhancement of wax ester or alkene synthesis is discussed.
裸藻是独特的原生生物，能够进行光合自养、光合混合营养和异养生长。在此，我们让其在这些不同的生长条件下生长，并测定了七种膜脂和一种储存脂质（三酰甘油）的细胞含量，这些脂质占总膜脂的94摩尔%以上。我们还描述了叶绿体和线粒体发育与脂质含量、蛋白质含量以及氧气释放/消耗速率之间的关系。在光合自养生长条件下，细胞积累叶绿素、光合蛋白以及类囊体膜特有的糖脂。在光合混合营养条件下生长且呼吸速率较高的细胞也出现同样情况。在异养条件下，与在其他条件下生长的细胞相比，细胞呼吸速率更高，且积累了丙酮酸：NADP⁺氧化还原酶，这是一种线粒体蛋白和线粒体中常见的磷脂。还使用共聚焦激光扫描显微镜观察细胞，发现当光合自养和光合混合营养生长时细胞显示出更多叶绿素自发荧光，而当光合混合营养和异养生长时显示出线粒体追踪染料的荧光。这些结果表明，在光照下，细胞形成具有用于光合作用的膜脂和蛋白质的功能性类囊体膜。在含有葡萄糖的培养基中，细胞形成具有用于呼吸作用的磷脂和蛋白质的线粒体。讨论了基于脂质分析在增强蜡酯或烯烃合成方面的可能应用。
