Potential cellular targets of platinum in the freshwater microalgae Chlamydomomas reinhardtii and Nitzschia palea revealed by transcriptomics

Abstract

Abstract Platinum group element (PGE) 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. This raises questions regarding their possible impacts on aquatic ecosystems, as the natural background concentrations of these rare metals are extremely low. 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. The use of molecular tools also allowed for the determination of possible intracellular effects and pathways of Pt. Both species that could be experiencing copper deficiency: inductions of genes corresponding to copper transporter suggest 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 dependant negative impact of Pt on mitochondrial metabolism for C. reinhardtii which is not observed for N. palea.