The temporal dynamics of phytoplankton growth and activity have large impacts on fluxes of matter and energy, yet obtaining in situ metabolic measurements of sufficient resolution for even dominant microorganisms remains a considerable challenge. We performed Lagrangian diel sampling with synoptic measurements of population abundances, dinitrogen (N₂) fixation, mortality, productivity, export and transcription in a bloom of Crocosphaera over eight days in the North Pacific Subtropical Gyre (NPSG). Quantitative transcriptomic analyses revealed clear diel oscillations in transcript abundances for 34% of Crocosphaera genes identified, reflecting a systematic progression of gene expression in diverse metabolic pathways. Significant time-lagged correspondence was evident between nifH transcript abundance and maximal N₂ fixation, as well as sepF transcript abundance and cell division, demonstrating the utility of transcriptomics to predict the occurrence and timing of physiological and biogeochemical processes in natural populations. Indirect estimates of carbon fixation by Crocosphaera were equivalent to 11% of net community production, suggesting that under bloom conditions this diazotroph has a considerable impact on the wider carbon cycle. Our cross-scale synthesis of molecular, population and community-wide data underscores the tightly coordinated in situ metabolism of the keystone N₂-fixing cyanobacterium Crocosphaera, as well as the broader ecosystem-wide implications of its activities.

中文翻译：

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单细胞固氮蓝藻Crocosphaera自然种群中生长，活性和转录的协调调控。

浮游植物生长和活动的时间动态对物质和能量通量有很大影响，但是即使对于优势微生物，也要获得足够分辨率的原位代谢测量仍然是一个巨大的挑战。我们对天气进行了拉格朗日diel抽样，并进行了人口数量，二氮（N ₂）在北太平洋亚热带环流（NPSG）中，在八天的鳄科花期中的固着，死亡率，生产力，出口和转录。定量转录组学分析显示，已鉴定出34％的Crocosphaera基因在转录本丰度上存在明显的diel振荡，反映出基因在各种代谢途径中的系统进展。nifH转录丰度与最大N ₂之间存在明显的时间滞后对应固定以及sepF转录本的丰度和细胞分裂，证明了转录组学可用于预测自然种群中生理和生物地球化学过程的发生和时间。Crocosphaera对碳固定的间接估计相当于社区净生产的11％，这表明在开花条件下，这种重氮营养对更广泛的碳循环有相当大的影响。我们的分子，人口和社区范围数据的跨尺度综合强调了固定N _2的基色蓝细菌Crocosphaera的紧密协调的原位代谢，以及其活动对整个生态系统的影响。