Institute of Physics, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, CZ-12116 Prague 2, Czech Republic.
Institute of Bio- and Geosciences/Plant Sciences (IBG-2), Forschungszentrum Jülich, Wilhelm-Johnen-Straße, D-52428 Jülich, Germany.
Cells. 2021 Jan 3;10(1):62. doi: 10.3390/cells10010062.
Photosynthetic energy conversion and the resulting photoautotrophic growth of green algae can only occur in daylight, but DNA replication, nuclear and cellular divisions occur often during the night. With such a light/dark regime, an algal culture becomes synchronized. In this study, using synchronized cultures of the green alga the dynamics of starch, lipid, polyphosphate, and guanine pools were investigated during the cell cycle by two independent methodologies; conventional biochemical analyzes of cell suspensions and confocal Raman microscopy of single algal cells. Raman microscopy reports not only on mean concentrations, but also on the distribution of pools within cells. This is more sensitive in detecting lipids than biochemical analysis, but both methods-as well as conventional fluorescence microscopy-were comparable in detecting polyphosphates. Discrepancies in the detection of starch by Raman microscopy are discussed. The power of Raman microscopy was proven to be particularly valuable in the detection of guanine, which was traceable by its unique vibrational signature. Guanine microcrystals occurred specifically at around the time of DNA replication and prior to nuclear division. Interestingly, guanine crystals co-localized with polyphosphates in the vicinity of nuclei around the time of nuclear division.
光合作用能量转换和由此产生的绿藻光自养生长只能在白天发生，但 DNA 复制、核和细胞分裂经常发生在夜间。在这种明暗制度下，藻类培养物会同步化。在这项研究中，使用绿藻的同步培养物，通过两种独立的方法研究了细胞周期中淀粉、脂质、多磷酸盐和鸟嘌呤库的动态；细胞悬浮液的常规生化分析和单个藻类细胞的共焦拉曼显微镜。拉曼显微镜不仅报告平均浓度，还报告细胞内池的分布。这比生化分析更能灵敏地检测脂质，但两种方法——以及常规荧光显微镜——在检测多磷酸盐方面具有可比性。拉曼显微镜检测淀粉的差异进行了讨论。拉曼显微镜的强大功能被证明在检测鸟嘌呤方面特别有价值，鸟嘌呤可以通过其独特的振动特征进行追踪。鸟嘌呤微晶专门出现在 DNA 复制前后和核分裂之前。有趣的是，鸟嘌呤晶体与核分裂前后核附近的多磷酸盐共定位。
