Subcellular architecture and metabolic connection in the planktonic photosymbiosis between Collodaria (radiolarians) and their microalgae
Subcellular architecture and metabolic connection in the planktonic photosymbiosis between Collodaria (radiolarians) and their microalgae
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DOI：
10.1111/1462-2920.15766
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发表时间：
2021-10-01
影响因子：
5.1
通讯作者：
Musat, Niculina
中科院分区：
文献类型：
--
作者：
Decelle, Johan;Veronesi, Giulia;Musat, Niculina
光共生现象在海洋浮游生物中广泛存在，具有重要的生态学意义，但目前对其研究甚少。在这里，我们使用多模态亚细胞成像，调查殖民胶甲藻和他们的microarrhodinoflagellate（Brandtodinium）之间的光共生。我们发现，这种共生是非常动态的，其中共生体通过细胞外囊泡内的殖民地与不同的宿主细胞相互作用。三维电子显微镜显示，微藻的光合机构更庞大的共生相比，自由生活，而线粒体的体积是相似的。稳定同位素探针结合NanoSIMS分析表明，碳和氮分别储存在淀粉颗粒和嘌呤晶体中的共生微生物中。氮也被分配到藻类核仁。在宿主中，在高尔基体中检测到低C-13转移。金属图谱显示，细胞内铁浓度在自由生活和共生微藻中是相似的（c。40 ppm）和两倍高的主机，而铜浓度增加共生体和检测到的宿主细胞和细胞外囊泡。共生体（染色质和蛋白核）中的硫浓度大约是宿主的两倍。这项研究提高了我们对这种海洋光共生功能的理解，并为更多的研究铺平了道路，以进一步评估其生物地球化学意义。
Photosymbiosis is widespread and ecologically important in the oceanic plankton but remains poorly studied. Here, we used multimodal subcellular imaging to investigate the photosymbiosis between colonial Collodaria and their microalga dinoflagellate (Brandtodinium). We showed that this symbiosis is very dynamic whereby symbionts interact with different host cells via extracellular vesicles within the colony. 3D electron microscopy revealed that the photosynthetic apparatus of the microalgae was more voluminous in symbiosis compared to free-living while the mitochondria volume was similar. Stable isotope probing coupled with NanoSIMS showed that carbon and nitrogen were stored in the symbiotic microalga in starch granules and purine crystals respectively. Nitrogen was also allocated to the algal nucleolus. In the host, low C-13 transfer was detected in the Golgi. Metal mapping revealed that intracellular iron concentration was similar in free-living and symbiotic microalgae (c. 40 ppm) and twofold higher in the host, whereas copper concentration increased in symbionts and was detected in the host cell and extracellular vesicles. Sulfur concentration was around two times higher in symbionts (chromatin and pyrenoid) than their host. This study improves our understanding on the functioning of this oceanic photosymbiosis and paves the way for more studies to further assess its biogeochemical significance.