Although sulfate ions are the main form of sulfur in the ocean, there is limited knowledge on their use by living organisms. Stable isotope labelling and NanoSIMS analysis were used in this study to clarify how sulfate, in seawater, is assimilated by corals and zooxanthellae at the cellular level. Aposymbiotic and symbiotic coral juveniles from the genus Acropora were incubated for 2 days in filtered seawater with ³⁴S‐labelled sulfate. Further, the labelled corals were incubated for additional 2 days in natural seawater. Mapping of sulfur isotopes (³⁴S/³²S) showed that the ‘hotspots’ were enriched in ³⁴S on a sub‐micro level and were heterogeneously distributed in the coral soft tissues. Specifically, ³⁴S hotspots were found in both the symbiotic zooxanthellae and coral host tissues. In aposymbiotic corals, ³⁴S was detected in the tissues, indicating that the host corals directly assimilated the sulfate ions without any aid from the zooxanthellae. Even after 2 days in normal seawater, the ³⁴S label was clearly seen in both symbiotic and aposymbiotic corals, indicating that the assimilated sulfur was retained for at least 2 days.

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非共生和共生虫黄藻在珊瑚中的硫同化

尽管硫酸根离子是海洋中硫的主要形式，但关于它们被生物体使用的知识却很有限。本研究使用稳定同位素标记和 NanoSIMS 分析来阐明海水中的硫酸盐如何在细胞水平上被珊瑚和虫黄藻同化。来自鹿角珊瑚属的非共生和共生珊瑚幼体在含有³⁴ S 标记的硫酸盐的过滤海水中培养 2 天。此外，标记的珊瑚在天然海水中再培养 2 天。硫同位素 ( ³⁴ S/ ³² S) 的绘图表明，“热点”在亚微米水平上富含^{34 S，并且在珊瑚软组织中分布不均。}具体来说，在共生虫黄藻和珊瑚宿主组织中均发现了^{34 S 热点。}在非共生珊瑚中，组织中检测到³⁴ S，表明宿主珊瑚直接同化硫酸根离子而没有虫黄藻的任何帮助。即使在正常海水中 2 天后，在共生和非共生珊瑚中都可以清楚地看到³⁴ S 标签，表明同化的硫至少保留了 2 天。