Boccara Martine, Wostrikoff Katia, Bailleuil Benjamin, Boccara Claude
Institut Langevin, ESPCI Paris, PSL Research University, CNRS UMR 7587, 1 Rue Jussieu, 75005, Paris, France.
ISYEB, Muséum National d'Histoire Naturelle, CNRS, Sorbonne Université, EPHE, Université Des Antilles, 57 Rue Cuvier, 75005, Paris, France.
Eur Phys J E Soft Matter. 2025 Jul 11;48(6-7):38. doi: 10.1140/epje/s10189-025-00499-y.
We developed a label-free optical microscopy method to study movements of different frequencies and amplitudes within a cell. We use optical transmission tomography (OTT) that operates in transmission, and we record the changes of signal values of all the pixels of movies taken for a few seconds (dynamic signal). This signal is a metabolic signal in algae as it decreased in the presence of photosystem II inhibitors or when samples were illuminated at wavelengths where the photoreceptors are poorly operative. We used as model organism Chlamydomonas for which mutants are available. We used a mutant deleted of the chloroplastic gene encoding the large subunit of the Rubisco, ΔrbcL. This mutant is unable to fix atmospheric CO and is devoid of pyrenoid. We compared the dynamic signal between wild-type strain and ΔrbcL mutant of Chlamydomonas grown in dark condition and found it to be 5 to 10 times higher. This mutant overproduced starch, and we tempted to associate the metabolic signal to the cost in ATP consumption for building starch. The method is easy to implement and could be very valuable for studies of phytoplankton in situ or virus-infected cells.
我们开发了一种无标记光学显微镜方法，用于研究细胞内不同频率和幅度的运动。我们使用在透射模式下运行的光学透射断层扫描（OTT），并记录拍摄几秒钟的电影中所有像素的信号值变化（动态信号）。在藻类中，这种信号是一种代谢信号，因为在光系统II抑制剂存在的情况下或当样品在光感受器作用不佳的波长下照射时，该信号会降低。我们使用衣藻作为模式生物，衣藻有可用的突变体。我们使用了一个缺失编码核酮糖-1,5-二磷酸羧化酶/加氧酶（Rubisco）大亚基的叶绿体基因的突变体，即ΔrbcL。这个突变体无法固定大气中的二氧化碳，并且没有淀粉核。我们比较了在黑暗条件下生长的衣藻野生型菌株和ΔrbcL突变体之间的动态信号，发现突变体的信号比野生型高5到10倍。这个突变体过量产生淀粉，我们试图将代谢信号与合成淀粉时ATP消耗的成本联系起来。该方法易于实施，对于原位研究浮游植物或病毒感染细胞可能非常有价值。
