Table_2_Quantitative Proteomics Reveals Common and Specific Responses of a Marine Diatom Thalassiosira pseudonana to Different Macronutrient Deficiencies.DOCX

Macronutrients such as nitrogen (N), phosphorus (P), and silicon (Si) are essential for the productivity and distribution of diatoms in the ocean. Responses of diatoms to a particular macronutrient deficiency have been investigated, however, we know little about their common or specific responses to different macronutrients. Here, we investigated the physiology and quantitative proteomics of a diatom Thalassiosira pseudonana grown in nutrient-replete, N-, P-, and Si-deficient conditions. Cell growth was ceased in all macronutrient deficient conditions while cell volume and cellular C content under P- and Si-deficiencies increased. Contents of chlorophyll a, protein and cellular N decreased in both N- and P-deficient cells but chlorophyll a and cellular N increased in the Si-deficient cells. Cellular P content increased under N- and Si-deficiencies. Proteins involved in carbon fixation and photorespiration were down-regulated under all macronutrient deficiencies while neutral lipid synthesis and carbohydrate accumulation were enhanced. Photosynthesis, chlorophyll biosynthesis, and protein biosynthesis were down-regulated in both N- and P-deficient cells, while Si transporters, light-harvesting complex proteins, chloroplastic ATP synthase, plastid transcription and protein synthesis were up-regulated in the Si-deficient cells. Our results provided insights into the common and specific responses of T. pseudonana to different macronutrient deficiencies and identified specific proteins potentially indicating a particular macronutrient deficiency.

氮（N）、磷（P）与硅（Si）等大量营养元素（macronutrients）对于海洋硅藻（diatom）的生产力与分布至关重要。尽管已有研究针对硅藻对单一大量营养元素缺乏的响应展开了探讨，但目前学界对其针对不同大量营养元素缺乏的共性与特异性响应仍知之甚少。本研究以生长于全营养、氮缺乏、磷缺乏及硅缺乏培养条件下的假微型海链藻（Thalassiosira pseudonana）为材料，对其生理学与定量蛋白质组学（quantitative proteomics）进行了系统分析。结果显示，所有大量营养元素缺乏条件下，藻细胞的生长均被抑制；而磷缺乏与硅缺乏条件下，细胞体积及细胞碳含量均有所升高。氮缺乏与磷缺乏的藻细胞中，叶绿素a、蛋白质及细胞氮含量均出现下降；但硅缺乏的藻细胞中，叶绿素a与细胞氮含量则有所上升。此外，氮缺乏与硅缺乏条件下，细胞磷含量均出现提升。所有大量营养元素缺乏条件下，参与碳固定与光呼吸过程的蛋白质均被下调；而中性脂质合成与碳水化合物积累过程则得到增强。氮缺乏与磷缺乏的藻细胞中，光合作用、叶绿素生物合成及蛋白质生物合成过程均被下调；而硅缺乏的藻细胞中，硅转运蛋白、捕光复合物蛋白、叶绿体ATP合酶（chloroplastic ATP synthase）以及质体转录与蛋白质合成过程均得到上调。本研究结果不仅阐明了假微型海链藻针对不同大量营养元素缺乏的共性与特异性响应机制，还筛选出了可潜在指示特定大量营养元素缺乏的特异性蛋白质。