Evaluation of Apical and Molecular Effects of Algae to Cerium Oxide Nanoparticles.

Cerium oxide engineered nanoparticles (nCeO) are widely used in various applications and are, also, increasingly being detected in different environmental matrixes. However, their impacts on the aquatic environment remain poorly quantified. Hence, there is a need to investigate their effects on non-target aquatic organisms. Here, we evaluated the cytotoxic and genotoxic effects of <25 nm uncoated-nCeO on algae . Apical (growth and chlorophyll (Chl ) content) and genotoxic effects were investigated at 62.5-1000 µg/L after 72 and 168 h. Results demonstrated that nCeO induced significant growth inhibition after 72 h and promotion post 96-168 h. Conversely, nCeO induced enhanced Chl content post 72 h, but no significant changes were observed between nCeO-exposed and control samples after 168 h. Hence, the results indicate photosynthetic system recovery ability to nCeO effects under chronic-exposure conditions. RAPD-PCR profiles showed the appearance and/or disappearance of normal bands relative to controls; indicative of DNA damage and/or DNA mutation. Unlike cell recovery observed post 96 h, DNA damage persisted over 168 h. Thus, sub-lethal nCeO-induced toxicological effects may pose a more serious threat to algae than at present anticipated.