Platinum group element levels have increased in natural aquatic environments in the last few decades, in particular as a consequence of the use of automobile catalytic converters on a global scale. Concentrations of Pt over tens of μg L⁻¹ have been observed in rivers and effluents. This raises questions regarding its possible impacts on aquatic ecosystems, as Pt natural background concentrations are extremely low to undetectable. Primary producers, such as microalgae, are of great ecological importance, as they are at the base of the food web. The purpose of this work was to better understand the impact of Pt on a cellular level for freshwater unicellular algae. Two species with different characteristics, a green alga C. reinhardtii and a diatom N. palea, were studied. The bioaccumulation of Pt as well as its effect on growth were quantified. Moreover, the induction or repression factors of 16 specific genes were determined and allowed for the determination of possible intracellular effects and pathways of Pt. Both species seemed to be experiencing copper deficiency as suggested by inductions of genes linked to copper transporters. This is an indication that Pt might be internalized through the Cu(I) metabolic pathway. Moreover, Pt could possibly be excreted using an efflux pump. Other highlights include a concentration-dependent negative impact of Pt on mitochondrial metabolism for C. reinhardtii which is not observed for N. palea. These findings allowed for a better understanding of some of the possible impacts of Pt on freshwater primary producers, and also lay the foundations for the investigation of pathways for Pt entry at the base of the aquatic food web.

Graphical Abstract

中文翻译：

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转录组学揭示淡水微藻莱茵衣藻和古菱形藻中铂的潜在细胞靶标

过去几十年来，自然水生环境中的铂族元素含量有所增加，特别是由于全球范围内使用汽车催化转换器。在河流和污水中观察到Pt 浓度超过数十 μg L ^{-1 。}这引发了关于其对水生生态系统可能影响的问题，因为铂的自然背景浓度极低至无法检测到。初级生产者，如微藻，具有重要的生态重要性，因为它们位于食物网的基础。这项工作的目的是更好地了解 Pt 对淡水单细胞藻类细胞水平的影响。研究了两种具有不同特征的物种：绿藻C. Reinhardtii和硅藻N. papea。对 Pt 的生物累积及其对生长的影响进行了量化。此外，还确定了 16 个特定基因的诱导或抑制因子，并允许确定 Pt 可能的细胞内效应和途径。与铜转运蛋白相关的基因的诱导表明，这两个物种似乎都缺乏铜。这表明 Pt 可能通过 Cu(I) 代谢途径内化。此外，Pt 可能会使用外排泵排出。其他亮点包括 Pt 对莱茵衣藻线粒体代谢的浓度依赖性负面影响，而在苍白猪笼草中未观察到这种影响。这些发现有助于更好地了解 Pt 对淡水初级生产者的一些可能影响，并为研究 Pt 进入水生食物网底部的途径奠定基础。

图形概要