Dellisanti Walter, Murthy Swathi, Bollati Elena, Prehn Sandberg Sara, Kühl Michael
Marine Biology Section, Department of Biology, University of Copenhagen, Helsingør, Denmark.
J Phycol. 2025 Jun;61(3):558-573. doi: 10.1111/jpy.70002. Epub 2025 Mar 30.
Dinoflagellates in the family Symbiodiniaceae are fundamental in coral reef ecosystems and facilitate essential processes such as photosynthesis, nutrient cycling, and calcium carbonate production. Iron (Fe) is an essential element for the physiological processes of Symbiodiniaceae, yet its role remains poorly understood in the context of cellular development and metabolic health. Here, we investigated the effect of iron availability-0-100 nM Fe(III)-on Symbiodinium sp. ITS2 type A1 cultures and quantified cellular content using flow cytometry and holotomography. Moderate levels of dissolved Fe (50 nM) enhanced growth rates and cellular content development in Symbiodinium sp., including lipids and proteins. We observed distinct growth patterns, pigment concentrations, and cellular morphology under increasing Fe concentrations, indicating the influence of iron availability on cellular physiology. Nondestructive, label-free holotomographic microscopy enabled single-cell in vivo imaging, revealing higher intracellular lipid accumulation (+57%) in response to 50 nM Fe(III) enrichment. Our findings contribute to a deeper understanding of the relationship between iron availability and Symbiodinium sp. growth and cellular development, with potential implications for coral health and reef resilience in the face of environmental stressors.
共生藻科的甲藻在珊瑚礁生态系统中至关重要，有助于光合作用、营养循环和碳酸钙生成等重要过程。铁（Fe）是共生藻科生理过程的必需元素，但其在细胞发育和代谢健康方面的作用仍知之甚少。在此，我们研究了铁可用性（0 - 100 nM Fe(III)）对共生藻ITS2 A1型培养物的影响，并使用流式细胞术和全层析成像对细胞内容物进行了定量分析。中等水平的溶解铁（50 nM）提高了共生藻的生长速率和细胞内容物的发育，包括脂质和蛋白质。在铁浓度增加的情况下，我们观察到了不同的生长模式、色素浓度和细胞形态，表明铁可用性对细胞生理的影响。非破坏性、无标记的全层析显微镜实现了单细胞体内成像，揭示了在50 nM Fe(III)富集下细胞内脂质积累增加（+57%）。我们的研究结果有助于更深入地理解铁可用性与共生藻生长和细胞发育之间的关系，对面对环境压力时的珊瑚健康和珊瑚礁恢复力具有潜在意义。
