Table_3_Comparative Proteomic Analysis Reveals New Insights Into the Common and Specific Metabolic Regulation of the Diatom Skeletonema dohrnii to the Silicate and Temperature Availability.XLSX

Silicate (Si) and temperature are essential drivers for diatom growth and development in the ocean. Response of diatoms to these particular stress has been investigated; however, their common and specific responses to regulate intracellular development and growth are not known. Here, we investigated the combination of physiological characteristics and comparative proteomics of the diatom Skeletonema dohrnii grown in silicate- and temperature-limited conditions. Results show that cell carbon and lipid quotas were higher at lower-temperature cells, whereas cellular phosphate was higher in cells grown with lower Si. In silicate-limited cells, nitrate transporters were downregulated and resulted in lower nitrate assimilation, whereas the phosphate transporters and its assimilation were reduced in lower-temperature conditions. In photosynthesis, lower silicate caused impact in the linear electron flow and NADPH production, whereas cycling electron transport and ATP production were affected by the lower temperature. Concerning cell cycle, imbalances in the translation process were observed in lower-silicate cells, whereas impact in the transcription mechanism was observed in lower-temperature cells. However, proteins associated with carbon fixation and photorespiration were downregulated in both stress conditions, while the carbohydrate and lipid synthesis proteins were upregulated. Our results showed new insights into the common and specific responses on the proteome and physiology of S. dohrnii to silicate and temperature limitation, providing particular nutrient (Si)- and temperature-dependent mechanisms in diatoms.

海洋中，硅酸盐（Silicate）与温度是驱动硅藻生长发育的关键驱动因子。此前已有研究针对硅藻对这两种胁迫的响应展开了探究，但二者在调控细胞内发育与生长过程中的共有及特异性响应机制仍未明确。本研究针对硅酸盐限制与温度限制条件下培养的多恩海链藻（Skeletonema dohrnii），开展了生理特征与比较蛋白质组学的联合分析。研究结果显示，低温培养的细胞其碳与脂质配额更高，而低硅培养的细胞胞内磷酸盐含量更高。在硅酸盐限制的细胞中，硝酸盐转运蛋白表达下调，导致硝酸盐同化作用减弱；而在低温条件下，磷酸盐转运蛋白及其同化作用均受到抑制。光合作用过程中，低硅胁迫会影响线性电子流与烟酰胺腺嘌呤二核苷酸磷酸（NADPH）的生成，而低温则会对循环电子传递与三磷酸腺苷（ATP）的产生造成影响。在细胞周期层面，低硅胁迫的细胞中出现了翻译过程失衡的现象，而低温条件下则观察到转录机制受到干扰。不过，两种胁迫条件下，与碳固定及光呼吸相关的蛋白均出现下调表达，而碳水化合物与脂质合成相关蛋白则呈现上调表达。本研究结果为多恩海链藻应对硅酸盐与温度限制的蛋白质组及生理层面的共有与特异性响应提供了新的认知，并为硅藻中依赖于硅酸盐（Si）与温度的调控机制提供了理论支撑。