Gabay Yasmin, Weis Virginia M, Davy Simon K
Biol Bull. 2018 Feb;234(1):1-10. doi: 10.1086/696365. Epub 2018 Mar 21.
The genus Symbiodinium is physiologically diverse and so may differentially influence symbiosis establishment and function. To explore this, we inoculated aposymbiotic individuals of the sea anemone Exaiptasia pallida (commonly referred to as "Aiptasia"), a model for coral symbiosis, with one of five Symbiodinium species or types (S. microadriaticum, S. minutum, phylotype C3, S. trenchii, or S. voratum). The spatial pattern of colonization was monitored over time via confocal microscopy, and various physiological parameters were measured to assess symbiosis functionality. Anemones rapidly formed a symbiosis with the homologous symbiont, S. minutum, but struggled or failed to form a long-lasting symbiosis with Symbiodinium C3 or S. voratum, respectively. Symbiodinium microadriaticum and S. trenchii were successful but reached their peak density two weeks after S. minutum. The spatial pattern of colonization was identical for all Symbiodinium taxa that were ultimately successful, starting in the oral disk and progressing to the tentacles, before invading the column and, finally, the pedal disk. In all cases, proliferation through the anemone's tentacles was patchy, suggesting that symbionts were being expelled into the gastrovascular cavity and re-phagocytosed by the host. However, the timing of these various spatial events differed between the different Symbiodinium taxa. Furthermore, S. microadriaticum and S. trenchii were less beneficial to the host, as indicated by lower rates of photosynthesis, anemone growth, and pedal laceration. This study enhances our understanding of the link between symbiont identity and the performance of the overall symbiosis, which is important for understanding the potential establishment and persistence of novel host-symbiont pairings. Importantly, we also provide a baseline for further studies on this topic with the globally adopted "Aiptasia" model system.
共生藻属在生理上具有多样性，因此可能对共生关系的建立和功能产生不同影响。为了探究这一点，我们用五种共生藻物种或类型（微小共生藻、微小亚心形共生藻、C3型藻株、特伦奇共生藻或沃拉共生藻）之一接种了作为珊瑚共生模型的海葵苍白艾氏海葵（通常称为“艾氏海葵”）的无共生体个体。通过共聚焦显微镜随时间监测定殖的空间模式，并测量各种生理参数以评估共生功能。海葵迅速与同源共生体微小亚心形共生藻形成共生关系，但分别与C3型藻株或沃拉共生藻形成持久共生关系时遇到困难或失败。微小共生藻和特伦奇共生藻成功定殖，但在微小亚心形共生藻之后两周达到峰值密度。所有最终成功的共生藻分类群的定殖空间模式都是相同的，从口盘开始，发展到触手，然后侵入柱体，最后到达足盘。在所有情况下，通过海葵触手的增殖都是不连续的，这表明共生体被排入消化循环腔并被宿主重新吞噬。然而，这些不同空间事件的时间在不同的共生藻分类群之间有所不同。此外，微小共生藻和特伦奇共生藻对宿主的益处较小，光合作用速率、海葵生长和足盘撕裂率较低表明了这一点。这项研究增进了我们对共生体身份与整体共生性能之间联系的理解，这对于理解新的宿主 - 共生体配对的潜在建立和持久性很重要。重要的是，我们还为使用全球通用的“艾氏海葵”模型系统对该主题的进一步研究提供了基线。
