The molecular mechanisms behind the adaptive responses for interactions between organisms and nanoparticles, such as silver nanoparticles (AgNPs), are of great concern. In this study, the transcriptome of freshwater alga Chlamydomonas reinhardtii was characterized via RNA sequencing (RNA-seq) after exposure to a nontoxic concentration of AgNPs (0.5 mg/L). The cytochrome c6 (CYC6) and ferredoxin-5 (FDX5) genes were identified with the greatest increase in expression level, which were indications of the copper deficiency in the algae. Gene set enrichment analysis also showed significant enrichment of copper deficiency responsive genes in the transcriptome of algae exposed to AgNPs. These results indicated that AgNPs induced a copper deficiency response in algae, and the excessive intracellular copper content suggested this was due to functional copper deficiency. This deficiency response was further validated to be regulated by transcription factor CRR1 (copper response regulator 1) according to the assays on the mutant strain with defect of CRR1. To the best of our knowledge, this is the first corroboration of a CRR1-targeted copper deficiency response in algae following AgNP exposure. Given the function of copper in fundamental metabolic pathways, such as photosynthesis and respiration, we propose a potential role of CRR1-targeted copper deficiency as an adaptation of algae after exposure to AgNPs.

中文翻译：

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在暴露于银纳米颗粒的莱茵衣藻中发现CRR1靶向铜缺乏反应。

生物与纳米粒子（例如银纳米粒子（AgNPs））之间的相互作用的适应性反应背后的分子机制引起了极大的关注。在这项研究中，在暴露于无毒浓度的AgNPs（0.5 mg / L）后，通过RNA测序（RNA-seq）对淡水藻类衣藻衣藻的转录组进行了表征。鉴定出细胞色素c6（CYC6）和铁氧还蛋白5（FDX5）基因的表达水平增加幅度最大，这表明藻中铜缺乏。基因集富集分析还显示，暴露于AgNPs的藻类转录组中铜缺乏反应基因显着富集。这些结果表明，AgNPs诱导藻类中的铜缺乏反应，细胞内铜含量过高表明这是由于功能性铜缺乏所致。根据对具有CRR1缺陷的突变株的分析，进一步证实了该缺陷反应受转录因子CRR1（铜响应调节剂1）的调控。据我们所知，这是首次证实AgNP暴露后藻类中以CRR1为目标的铜缺乏反应。鉴于铜在基本的代谢途径（例如光合作用和呼吸作用）中的功能，我们提出了以CRR1为目标的铜缺乏作为潜在的藻类暴露于AgNP后的适应性作用。据我们所知，这是首次证实AgNP暴露后藻类中以CRR1为目标的铜缺乏反应。鉴于铜在基本的代谢途径（例如光合作用和呼吸作用）中的功能，我们提出了以CRR1为目标的铜缺乏作为潜在的藻类暴露于AgNP后的适应性作用。据我们所知，这是首次证实AgNP暴露后藻类中以CRR1为靶标的铜缺乏反应。鉴于铜在基本的代谢途径（例如光合作用和呼吸作用）中的功能，我们提出了以CRR1为目标的铜缺乏作为潜在的藻类暴露于AgNP后的适应性作用。