Emiliania huxleyi is a calcifying haptophyte, contributing to both the organic and inorganic marine carbon cycles. In marine ecosystems, light is a major driver of phytoplankton physiology and ultimately carbon flow through the ecosystem. Here, we analysed a Lagrangian time-series of metatranscriptomes collected in the North Pacific Subtropical Gyre (NPSG) to examine how in situ populations of E. huxleyi modulate gene expression over day-night transitions. Many E. huxleyi contigs had a diel expression pattern, with 61% of contigs clustering into modules with statistically significant diel periodicity. Contigs involved in processes that build up energy stores, like carbon fixation and lipid synthesis, peaked around dawn. In contrast, contigs involved in processes that released energy stores, like respiration and lipid degradation, peaked mid-day and towards dusk. These patterns suggest an orchestrated cycle of building, then consuming energy stores in E. huxleyi populations in the NPSG. Selected contigs related to the cell cycle also exhibited significant diel periodicity consistent with phased modulations of division observed in culture. Overall, these patterns of gene expression suggest a daily metabolic cascade that could contribute to both organic and inorganic carbon flow in this nutrient depleted ecosystem.

中文翻译：

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在北太平洋亚热带环流中的Emiliaania huxleyi的转录模式揭示了其代谢潜能的日常节律。

Emiliania huxleyi是钙化的附生植物，对有机和无机海洋碳循环都有贡献。在海洋生态系统中，光是浮游植物生理的主要驱动力，最终是碳通过生态系统的主要驱动力。在这里，我们分析了在北太平洋亚热带环流（NPSG）中收集的元转录组的拉格朗日时间序列，以检查huxleyi的原位种群如何在昼夜过渡过程中调节基因表达。许多人肠埃希菌重叠群都具有diel表达模式，其中61％的重叠群聚类为具有统计学上显着的diel周期性的模块。重叠群参与建立能量储存的过程，例如碳固定和脂质合成，在黎明左右达到顶峰。相反，重叠群参与释放能量存储的过程，例如呼吸和脂质降解，中午时分达到顶峰，接近黄昏。这些模式表明，有序的建筑周期，然后消耗了NPSG中huxleyi种群的能量。与细胞周期有关的选定重叠群也表现出显着的狄尔周期，这与在培养物中观察到的分裂的分阶段调节相一致。总体而言，这些基因表达模式提示了每天的代谢级联反应，这可能会导致营养缺乏的生态系统中的有机碳和无机碳流动。