Cellular mechanisms responsible for the regulation of nutrient exchange, immune responses, and symbiont population growth in the cnidarian-dinoflagellate symbiosis are poorly resolved, particularly with respect to the dinoflagellate symbiont. Here, we characterised proteomic changes in the native symbiont Breviolum minutum during colonisation of its host sea anemone Exaiptasia diaphana (“Aiptasia”). We also compared the proteome of this native symbiont in the established symbiotic state with that of a non-native symbiont, Durusdinium trenchii. The onset of symbiosis between Aiptasia and Branchioglossum minutum increased accumulation of symbiont proteins associated with acquisition of inorganic carbon and photosynthesis, nitrogen metabolism, micro- and macronutrient starvation, suppression of host immune responses, tolerance to low pH, and management of oxidative stress. Such responses are consistent with a functional, persistent symbiosis. In contrast, D. trenchii predominantly showed elevated levels of immunosuppressive proteins, consistent with the view that this symbiont is an opportunist that forms a less beneficial, less well-integrated symbiosis with this model anemone. By adding symbiont analysis to the already known responses of the host proteome, our results provide a more holistic view of cellular processes that determine host-symbiont specificity and how differences in symbiont partners (i.e., native versus non-native symbionts) may impact the fitness of the cnidarian–dinoflagellate symbiosis.

中文翻译：

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天然和非天然共生体的蛋白质组揭示了刺胞动物-甲藻共生中宿主-共生体特异性的反应


在刺胞动物-甲藻共生体中负责调节营养交换、免疫反应和共生体种群增长的细胞机制尚不清楚，尤其是关于甲藻共生体。在这里，我们表征了天然共生体 Breviolum minutum 在其宿主海葵 Exaiptasia diaphana（“Aiptasia”）定植过程中的蛋白质组学变化。我们还将这种处于已建立共生状态的天然共生体的蛋白质组与非天然共生体 Durusdinium trenchii 的蛋白质组进行了比较。Aiptasia 和 Branchioglossum minutum 之间共生的开始增加了与无机碳和光合作用、氮代谢、微量和常量营养素饥饿、宿主免疫反应的抑制、对低 pH 值的耐受性和氧化应激管理相关的共生体蛋白的积累。这种反应与功能性的、持续的共生关系是一致的。相比之下，D. trenchii 主要表现出免疫抑制蛋白水平升高，这与这种共生体是一种机会主义的观点一致，它与该模型海葵形成不太有益、整合较差的共生关系。通过将共生体分析添加到宿主蛋白质组的已知反应中，我们的结果提供了更全面的细胞过程视图，这些过程决定了宿主-共生体特异性，以及共生体伙伴（即天然与非天然共生体）的差异如何影响刺胞动物-甲藻共生的适应性。