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

Cerium oxide engineered nanoparticles (nCeO 2 ) 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 2 on algae Pseudokirchneriella subcapitata . Apical (growth and chlorophyll a (Chl a ) content) and genotoxic effects were investigated at 62.5-1000 µg/L after 72 and 168 h. Results demonstrated that nCeO 2 induced significant growth inhibition after 72 h and promotion post 96-168 h. Conversely, nCeO 2 induced enhanced Chl a content post 72 h, but no significant changes were observed between nCeO 2 -exposed and control samples after 168 h. Hence, the results indicate P. subcapitata photosynthetic system recovery ability to nCeO 2 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 2 -induced toxicological effects may pose a more serious threat to algae than at present anticipated.