Under nitrogen deficiency situation, Nannochloropsis spp. accumulate large amounts of lipids in the form of triacylglycerides (TAG). Mechanisms of this process from the perspective of transcriptome and metabolome have been obtained previously, yet proteome analysis is still sparse which hinders the analysis of dynamic adaption to nitrogen deficiency. Here, proteomes for 3 h, 6 h, 12 h, 24 h, 48 h and 10th day of nitrogen deplete (N−) and replete (N+) conditions were obtained and integrated with previous transcriptome data for N. oceanica. Physiological adaptations to N− not apparent from transcriptome data were unveiled: (a) abundance of proteins related to photosynthesis only slightly decreased in the first 48 h, indicating that photosynthesis is still working efficiently, and protein amounts adjust gradually with reduction in chloroplast size. (b) Most proteins related to the TCA cycle were strongly upregulated after 48 h under N−, suggesting that respiration is enhanced after 48 h and that TCA cycle efflux supports the carbon required for lipid synthesis. (c) Proteins related to lipid accumulation via the Kennedy pathway increased their abundance at 48 h, synchronous with the previously reported diversification of fatty acids after 48 h. This study adds a proteome perspective on the major pathways for TAG accumulation in Nannochloropsis spp. Temporal changes of proteome exhibited distinct adaptation phases that are usually delayed relative to transcriptomic responses. Notably, proteome data revealed that photosynthesis and carbon fixation are still ongoing even after 48 h of N−. Moreover, sometimes completely opposite trends in proteome and transcriptome demonstrate the relevance of underexplored post-transcriptional regulation for N− adaptation.

中文翻译：

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蛋白质组和转录组的整合改进了海洋微拟球藻石油生产的关键分子过程。

在缺氮情况下，Nannochloropsis spp。以甘油三酯 (TAG) 的形式积累大量脂质。此前已经从转录组和代谢组的角度获得了这一过程的机制，但蛋白质组分析仍然很少，这阻碍了对氮缺乏动态适应的分析。在这里，获得了 3 小时、6 小时、12 小时、24 小时、48 小时和第 10 天的缺氮 (N-) 和充足 (N+) 条件的蛋白质组，并将其与 N. Oceanica 的先前转录组数据整合。揭示了从转录组数据中不明显的对 N- 的生理适应：（a）与光合作用相关的蛋白质丰度在前 48 小时仅略有下降，表明光合作用仍在有效进行，并且蛋白质量随着叶绿体大小的减小而逐渐调整。（b）大多数与 TCA 循环相关的蛋白质在 N-下 48 小时后强烈上调，表明 48 小时后呼吸增强，并且 TCA 循环流出支持脂质合成所需的碳。（ c ）通过肯尼迪途径与脂质积累相关的蛋白质在 48 小时时增加了它们的丰度，与之前报道的 48 小时后脂肪酸的多样化同步。这项研究增加了关于微球藻中 TAG 积累的主要途径的蛋白质组学观点。蛋白质组的时间变化表现出明显的适应阶段，这些阶段通常相对于转录组反应延迟。值得注意的是，蛋白质组数据显示，即使在 N- 48 小时后，光合作用和碳固定仍在进行中。而且，