School of Biological Sciences, Victoria University of Wellington, Wellington 6140, New Zealand.
Metabolomics Australia, School of Botany, The University of Melbourne, Parkville 3052, Victoria, Australia.
Proc Biol Sci. 2018 Nov 28;285(1892):20182336. doi: 10.1098/rspb.2018.2336.
Metabolite exchange is fundamental to the viability of the cnidarian-Symbiodiniaceae symbiosis and survival of coral reefs. Coral holobiont tolerance to environmental change might be achieved through changes in Symbiodiniaceae species composition, but differences in the metabolites supplied by different Symbiodiniaceae species could influence holobiont fitness. Using C stable-isotope labelling coupled to gas chromatography-mass spectrometry, we characterized newly fixed carbon fate in the model cnidarian (Aiptasia) when experimentally colonized with either native or non-native Relative to anemones containing , -colonized hosts exhibited a 4.5-fold reduction in C-labelled glucose and reduced abundance and diversity of C-labelled carbohydrates and lipogenesis precursors, indicating symbiont species-specific modifications to carbohydrate availability and lipid storage. Mapping carbon fate also revealed significant alterations to host molecular signalling pathways. In particular, colonized hosts exhibited a 40-fold reduction in C-labelled -inositol, a potential interpartner signalling molecule in symbiosis specificity. C-labelling also highlighted differential antioxidant- and ammonium-producing pathway activities, suggesting physiological responses to different symbiont species. Such differences in symbiont metabolite contribution and host utilization may limit the proliferation of stress-driven symbioses; this contributes valuable information towards future scenarios that select in favour of less-competent symbionts in response to environmental change.
代谢物交换对于水螅虫-共生藻共生体的存活和珊瑚礁的生存至关重要。珊瑚共生体对环境变化的耐受可能是通过共生藻物种组成的变化来实现的，但不同共生藻物种提供的代谢物差异可能会影响共生体的适应性。我们使用 C 稳定同位素标记结合气相色谱-质谱法，研究了模型腔肠动物（海葵）在与天然或非天然共生藻共生时新固定碳的命运。与含有共生藻的海葵相比， -共生的宿主的 C 标记葡萄糖减少了 4.5 倍，C 标记碳水化合物和脂生成前体的丰度和多样性降低，表明共生藻物种特异性地改变了碳水化合物的可用性和脂质储存。碳命运的映射还揭示了对宿主分子信号通路的显著改变。特别是，被共生藻感染的宿主的 C 标记 -肌醇减少了 40 倍，肌醇是共生体特异性中潜在的互作信号分子。C 标记还突出了不同抗氧化剂和氨产生途径活性的差异，表明对不同共生藻物种的生理反应。共生体代谢物贡献和宿主利用的这种差异可能限制了应激驱动共生体的增殖；这为未来的情景提供了有价值的信息，这些情景有利于在环境变化时选择竞争力较弱的共生体。
