Abstract:
Cerium oxide engineered nanoparticles (nCeO2) 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-nCeO2 on algae Pseudokirchneriella subcapitata. Apical (growth and chlorophyll
a (Chl a) content) and genotoxic effects were investigated at 62.5–1000 g/L after 72 and 168 h.
Results demonstrated that nCeO2 induced significant growth inhibition after 72 h and promotion
post 96–168 h. Conversely, nCeO2 induced enhanced Chl a content post 72 h, but no significant
changes were observed between nCeO2–exposed and control samples after 168 h. Hence, the results
indicate P. subcapitata photosynthetic system recovery ability to nCeO2 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 nCeO2-induced toxicological effects
may pose a more serious threat to algae than at present anticipated.
Description:
SUPPLEMENTARY MATERIALS: TABLE S1: The composition of 10% BG-11 medium; FIGURE S1: Size characterization of nCeO2 (a) TEM images [36], (b) size distribution; FIGURE S2: Algal growth of P. subcapitata at different concentrations of K2Cr2O7: FIGURE S3: in situ nCeO2 concentration (particles/mL) characterization examined using Nanoparticle Tracking Analysis [92].