The purpose of this work is to develop an integrated imaging approach to characterize without labeling at the sub-cellular level the formation of lipid body droplets (LBs) in microalgae undergoing nitrogen starvation. First conventional optical microscopy approaches, gas chromatography, and turbidimetry measurements allowed to monitor the biomass and the total lipid content in the oleaginous microalgae Parachlorella kesslerii during the starvation process. Then a local analysis of the LBs was proposed using an innovative infrared nanospectroscopy technique called atomic force microscopy-based infrared spectroscopy (AFM-IR). This label-free technique assessed the formation of LBs and allowed to look into the LB composition thanks to the acquisition of local infrared spectra. Last correlative measurements using fluorescence microscopy and AFM-IR were performed to investigate the subcellular reorganization of LB and the chloroplasts.

这项工作的目的是开发一种综合成像方法，无需在亚细胞水平上标记，即可在经历氮饥饿的微藻中形成脂体液滴 (LBs)。第一个传统的光学显微镜方法、气相色谱法和比浊法测量允许监测产油微藻Parachlorella kesslerii 中的生物量和总脂质含量在饥饿过程中。然后建议使用一种称为基于原子力显微镜的红外光谱 (AFM-IR) 的创新红外纳米光谱技术对 LB 进行局部分析。由于获取了局部红外光谱，这种无标记技术评估了 LB 的形成，并允许查看 LB 的组成。最后使用荧光显微镜和 AFM-IR 进行相关测量以研究 LB 和叶绿体的亚细胞重组。