Kong Liangliang, Price Neil M
Department of Biology, McGill University, Montréal, QC, Canada.
College of Marine Life Sciences, Ocean University of China, Qingdao, Shandong, China.
Environ Microbiol. 2022 Feb;24(2):951-966. doi: 10.1111/1462-2920.15609. Epub 2021 Jun 14.
Copper (Cu) concentration is greatly reduced in the open sea so that phytoplankton must adjust their uptake systems and acclimate to sustain growth. Acclimation to low Cu involves changes to the photosynthetic apparatus and specific biochemical reactions that use Cu, but little is known how Cu affects cellular metabolic networks. Here we report results of whole transcriptome analysis of a plastocyanin-containing diatom, Thalassiosira oceanica 1005, during its initial stages of acclimation and after long-term adaptation in Cu-deficient seawater. Gene expression profiles, used to identify Cu-regulated metabolic pathways, show downregulation of anabolic and energy-yielding reactions in Cu-limited cells. These include the light reactions of photosynthesis, carbon fixation, nitrogen assimilation and glycolysis. Reduction of these pathways is consistent with reduced growth requirements for C and N caused by slower rates of photosynthetic electron transport. Upregulation of oxidative stress defence systems persists in adapted cells, suggesting cellular damage by increased reactive oxygen species (ROS) occurs even after acclimation. Copper deficiency also alters fatty acid metabolism, possibly in response to an increase in lipid peroxidation and membrane damage driven by ROS. During the initial stages of Cu-limitation the majority of differentially regulated genes are associated with photosynthetic metabolism, highlighting the chloroplast as the primary target of low Cu availability. The results provide insights into the mechanisms of acclimation and adaptation of T. oceanica to Cu deficiency.
公海中铜（Cu）的浓度大幅降低，因此浮游植物必须调整其摄取系统并适应环境以维持生长。适应低铜环境涉及光合作用装置的变化以及使用铜的特定生化反应，但人们对铜如何影响细胞代谢网络知之甚少。在此，我们报告了含质体蓝素的硅藻——海洋硅藻1005在适应初期以及在缺铜海水中长期适应后的全转录组分析结果。用于识别铜调节代谢途径的基因表达谱显示，在铜限制的细胞中，合成代谢和能量产生反应下调。这些反应包括光合作用的光反应、碳固定、氮同化和糖酵解。这些途径的减少与光合电子传递速率减慢导致的对碳和氮的生长需求降低相一致。适应细胞中氧化应激防御系统持续上调，这表明即使在适应后，活性氧（ROS）增加也会导致细胞损伤。铜缺乏还会改变脂肪酸代谢，这可能是对ROS驱动的脂质过氧化和膜损伤增加的一种反应。在铜限制的初始阶段，大多数差异调节基因与光合代谢相关，这突出了叶绿体是低铜可用性的主要靶点。这些结果为海洋硅藻适应和适应缺铜环境的机制提供了见解。
