title: Genotoxic and cytotoxic effects of ZnO nanoparticles for Dunaliella tertiolecta and comparison with SiO2 and TiO2 effects at population growth inhibition levels.
abstract: The increasing use of oxide nanoparticles (NPs) in commercial products has intensified the potential release into the aquatic environment where algae represent the basis of the trophic chain. NP effects upon algae population growth were indeed already reported in literature, but the concurrent effects at cellular and genomic levels are still largely unexplored. Our work investigates the genotoxic (by COMET assay) and cytotoxic effects (by qualitative ROS production and cell viability) of ZnO nanoparticles toward marine microalgae Dunaliella tertiolecta. A comparison at defined population growth inhibition levels (i.e. 50% Effect Concentration, EC50, and No Observed Effect Concentration, NOEC) with SiO2 and TiO2 genotoxic effects and previously investigated cytotoxic effects (Manzo et al., 2015) was performed in order to elucidate the possible diverse mechanisms leading to algae growth inhibition. After 72h exposure, ZnO particles act firstly at the level of cell division inhibition (EC50: 2mg Zn/L) while the genotoxic action is evident only starting from 5mg Zn/L. This outcome could be ascribable mainly to the release of toxic ions from the aggregate of ZnO particle in the proximity of cell membrane. In the main, at EC50 and NOEC values for ZnO NPs showed the lowest cytotoxic and genotoxic effect with respect to TiO2 and SiO2. Based on Mutagenic Index (MI) the rank of toxicity is actually: TiO2>SiO2>ZnO with TiO2 and SiO2 that showed similar MI values at both NOEC and EC50 concentrations. The results presented herein suggest that up to TiO2 NOEC (7.5mg/L), the algae DNA repair mechanism is efficient and the DNA damage does not result in an evident algae population growth inhibition. A similar trend for SiO2, although at lower effect level with respect to TiO2, is observable. The comparison among all the tested nanomaterial toxicity patterns highlighted that the algae population growth inhibition occurred through pathways specific for each NP also related to their different physicochemical behaviors in seawater.
authors: Enea CR Portici, P. le E. Fermi, 1, 80055 Portici, Naples, Italy. Electronic address: simonaschiavo@gmail.com.
authors: S
authors: S
authors: Schiavo
authors: Enea CR Portici, P. le E. Fermi, 1, 80055 Portici, Naples, Italy.
authors: M
authors: M
authors: Oliviero
authors: Enea CR Portici, P. le E. Fermi, 1, 80055 Portici, Naples, Italy.
authors: M
authors: M
authors: Miglietta
authors: Enea CR Portici, P. le E. Fermi, 1, 80055 Portici, Naples, Italy.
authors: G
authors: G
authors: Rametta
authors: Enea CR Portici, P. le E. Fermi, 1, 80055 Portici, Naples, Italy.
authors: S
authors: S
authors: Manzo
mesh_terms: D000460:Chlorophyta / Q000187:drug effects* / Q000254:growth & development; D020552:Comet Assay; D053768:Metal Nanoparticles / Q000633:toxicity*; D009153:Mutagens; D012822:Silicon Dioxide / Q000633:toxicity*; D014025:Titanium / Q000633:toxicity*; D014874:Water Pollutants, Chemical / Q000633:toxicity*; D015034:Zinc Oxide / Q000633:toxicity*
chemical_list: D009153:Mutagens; D014874:Water Pollutants, Chemical; C009495:titanium dioxide; D012822:Silicon Dioxide; D014025:Titanium; D015034:Zinc Oxide
keywords: Cell viability; Comet assay; DNA damage; Marine microalgae; Oxidative stress