Research Institute for Electronic Science, Hokkaido University, Kita21, Nishi10, Kita-ku, Sapporo 001-0021, Japan.
Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
Anal Chem. 2021 Dec 21;93(50):16796-16803. doi: 10.1021/acs.analchem.1c03216. Epub 2021 Dec 6.
Phototrophs assimilate CO into organic compounds that accumulate in storage organelles. Elucidation of the carbon dynamics of storage organelles could enhance the production efficiency of valuable compounds and facilitate the screening of strains with high photosynthetic activity. To comprehensively elucidate the carbon dynamics of these organelles, the intraorganellar distribution of the carbon atoms that accumulate at specific time periods should be probed. In this study, the biosynthesis of polysaccharides in storage organelles was spatiotemporally probed via stimulated Raman scattering (SRS) microscopy using a stable isotope (C) as the tracking probe. Paramylon granules (a storage organelle of β-1,3-glucan) accumulated in a unicellular photosynthetic alga, , were investigated as a model organelle. The carbon source of the culture medium was switched from NaHCO to NaHCO during the production of the paramylon granules; this resulted in the distribution of the C and C constituents in the granules, so that the biosynthetic process could be tracked. Taking advantage of high-resolution SRS imaging and label switching, the localization of the C and C constituents inside a single paramylon granule could be visualized in three dimensions, thus revealing the growth process of paramylon granules. We propose that this method can be used for comprehensive elucidation of the dynamic activities of storage organelles.
光能自养生物将 CO 同化到积累在储存细胞器中的有机化合物中。阐明储存细胞器的碳动态可以提高有价值化合物的生产效率，并有助于筛选具有高光合活性的菌株。为了全面阐明这些细胞器的碳动态，应该探测在特定时间段内积累的碳原子在细胞器内的分布。在这项研究中，使用稳定同位素 (C) 作为示踪探针，通过受激拉曼散射 (SRS) 显微镜对储存细胞器中多糖的生物合成进行了时空探测。以一种单细胞光合藻类， 为模型细胞器，研究了其储存细胞器——副淀粉粒（β-1,3-葡聚糖的储存细胞器）的生物合成。在副淀粉粒的生产过程中，培养基中的碳源从 NaHCO 切换为 NaHCO；这导致 C 和 C 成分在颗粒中的分布，从而可以跟踪生物合成过程。利用高分辨率 SRS 成像和标记切换，可以在三维空间中可视化单个副淀粉粒内 C 和 C 成分的定位，从而揭示副淀粉粒的生长过程。我们提出，这种方法可用于全面阐明储存细胞器的动态活性。
